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Sample records for octopole reaction system

Octopole and hexapole end cells for tandem mirrors

International Nuclear Information System (INIS)

Devoto, R.S.

1985-01-01

To date, nearly all operating or planned tandem mirror experiments use quadrupole magnetic fields in the end cells for stabilization of magnetohydrodynamic (MHD) instabilities. A disadvantage with quadrupole fields is the considerable aximuthal asymmetry in the magnetic field. As a result, those center-cell ions which pass into the end cell can suffer a radial deflection and be lost by radial diffusion. The diffusion can be minimized by adding C-coils to the end cell to symmetrize the geodesic curvature in the end cell. Very small radial deflection can be obtained on each field line. Such a method is used in the design of the MFTF-B experiment and the MARS reactor. A disadvantage of this approach is the large number of coils required. In addition, since ions drift azimuthally as they reflect in the end cell, even perfect cancellation on individual field lines will, in general, not lead to zero radial diffusion. One way to form a more symmetric field in the end cells is to use multipoles higher than quadrupole. The use of an octopole end cell for a small tandem-mirror reactor was recently proposed/sup L/ and has been adopted for the miniMARS reactor study. In this paper the author discusses some feature of octopole, and to a lesser extent, hexapole end cells in both reactor and experimental (MFTF-B) applications
Low energy cross section data for ion-molecule reactions in hydrogen systems and for charge transfer of multiply charged ions with atoms and molecules

International Nuclear Information System (INIS)

Okuno, Kazuhiko

2007-04-01

Systematic cross section measurements for ion-molecule reactions in hydrogen systems and for charge transfer of multiply charged ions in low energy collisions with atoms and molecules have been performed continuously by the identical apparatus installed with an octo-pole ion beam guide (OPIG) since 1980 till 2004. Recently, all of accumulated cross section data for a hundred collision systems has been entered into CMOL and CHART of the NIFS atomic and molecular numerical database together with some related cross section data. In this present paper, complicated ion-molecule reactions in hydrogen systems are revealed and the brief outlines of specific properties in low energy charge transfer collisions of multiply charged ions with atoms and molecules are introduced. (author)
High-Resolution State-Selected Ion-Molecule Reaction Studies Using Pulsed Field Ionization Photoelectron-Secondary Ion Coincidence Method

National Research Council Canada - National Science Library

Qian, X

2003-01-01

We have developed an octopole-quadrupole photoionization apparatus at the Advanced Light Source for absolute integral cross-section measurements of rovibrational-state-selected ion-molecule reactions...
Determination of low concentrations of iron, arsenic, selenium, cadmium, and other trace elements in natural samples using an octopole collision/reaction cell equipped quadrupole-inductively coupled plasma mass spectrometer.

Science.gov (United States)

Dial, Angela R; Misra, Sambuddha; Landing, William M

2015-04-30

Accurate determination of trace metals has many applications in environmental and life sciences, such as constraining the cycling of essential micronutrients in biological production and employing trace metals as tracers for anthropogenic pollution. Analysis of elements such as Fe, As, Se, and Cd is challenged by the formation of polyatomic mass spectrometric interferences, which are overcome in this study. We utilized an Octopole Collision/Reaction Cell (CRC)-equipped Quadrupole-Inductively Coupled Plasma Mass Spectrometer for the rapid analysis of small volume samples (~250 μL) in a variety of matrices containing HNO3 and/or HCl. Efficient elimination of polyatomic interferences was demonstrated by the use of the CRC in Reaction Mode (RM; H2 gas) and in Collision-Reaction Mode (CRM; H2 and He gas), in addition to hot plasma (RF power 1500 W) and cool plasma (600 W) conditions. It was found that cool plasma conditions with RM achieved the greatest signal sensitivity while maintaining low detection limits (i.e. (56) Fe in 0.44 M HNO3 has a sensitivity of 160,000 counts per second (cps)-per-1 µg L(-1) and a limit of detection (LoD) of 0.86 ng L(-1) ). The average external precision was ≤ ~10% for minor (≤10 µg L(-1) ) elements measured in a 1:100 dilution of NIST 1643e and for iron in rainwater samples under all instrumental operating conditions. An improved method has been demonstrated for the rapid multi-element analysis of trace metals that are challenged by polyatomic mass spectrometric interferences, with a focus on (56) Fe, (75) As, (78) Se and (111) Cd. This method can contribute to aqueous environmental geochemistry and chemical oceanography, as well as other fields such as forensic chemistry, agriculture, food chemistry, and pharmaceutical sciences. Copyright © 2015 John Wiley & Sons, Ltd.
Nonlinear Ion Harmonics in the Paul Trap with Added Octopole Field: Theoretical Characterization and New Insight into Nonlinear Resonance Effect.

Science.gov (United States)

Xiong, Caiqiao; Zhou, Xiaoyu; Zhang, Ning; Zhan, Lingpeng; Chen, Yongtai; Nie, Zongxiu

2016-02-01

The nonlinear harmonics within the ion motion are the fingerprint of the nonlinear fields. They are exclusively introduced by these nonlinear fields and are responsible to some specific nonlinear effects such as nonlinear resonance effect. In this article, the ion motion in the quadrupole field with a weak superimposed octopole component, described by the nonlinear Mathieu equation (NME), was studied by using the analytical harmonic balance (HB) method. Good accuracy of the HB method, which was comparable with that of the numerical fourth-order Runge-Kutta (4th RK), was achieved in the entire first stability region, except for the points at the stability boundary (i.e., β = 1) and at the nonlinear resonance condition (i.e., β = 0.5). Using the HB method, the nonlinear 3β harmonic series introduced by the octopole component and the resultant nonlinear resonance effect were characterized. At nonlinear resonance, obvious resonant peaks were observed in the nonlinear 3β series of ion motion, but were not found in the natural harmonics. In addition, both resonant excitation and absorption peaks could be observed, simultaneously. These are two unique features of the nonlinear resonance, distinguishing it from the normal resonance. Finally, an approximation equation was given to describe the corresponding working parameter, q nr , at nonlinear resonance. This equation can help avoid the sensitivity degradation due to the operation of ion traps at the nonlinear resonance condition.
Multi-element Analysis of variable sample matrices using collision/reaction cell inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Zahran, N.F.; Helal, A.I.; Amr, M.A.; Amr, M.A.; Al-saad, K.A.

2008-01-01

An ICP-MS with an octopole reaction/collision cell is used for the multielement determination of trace elements in water, plants, and soil samples. The use of a reaction or collision gas reduces serious spectral interferences from matrix elements such as Ar Cl or Ar Na. The background equivalent concentration (BEC) is reduced one order of magnitude at helium flow rate of 1 mL/min. Certified reference material namely , NIST Water-1643d, Tomato leaves 1573a, and Montana soil 2711 are used. The trace elements Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Cd and Pb are determined in the different matrices with a accuracy better than 8% to the certified values
Sleeve reaction chamber system

Science.gov (United States)

Northrup, M Allen [Berkeley, CA; Beeman, Barton V [San Mateo, CA; Benett, William J [Livermore, CA; Hadley, Dean R [Manteca, CA; Landre, Phoebe [Livermore, CA; Lehew, Stacy L [Livermore, CA; Krulevitch, Peter A [Pleasanton, CA

2009-08-25

A chemical reaction chamber system that combines devices such as doped polysilicon for heating, bulk silicon for convective cooling, and thermoelectric (TE) coolers to augment the heating and cooling rates of the reaction chamber or chambers. In addition the system includes non-silicon-based reaction chambers such as any high thermal conductivity material used in combination with a thermoelectric cooling mechanism (i.e., Peltier device). The heat contained in the thermally conductive part of the system can be used/reused to heat the device, thereby conserving energy and expediting the heating/cooling rates. The system combines a micromachined silicon reaction chamber, for example, with an additional module/device for augmented heating/cooling using the Peltier effect. This additional module is particularly useful in extreme environments (very hot or extremely cold) where augmented heating/cooling would be useful to speed up the thermal cycling rates. The chemical reaction chamber system has various applications for synthesis or processing of organic, inorganic, or biochemical reactions, including the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction.
Extent of reaction in open systems with multiple heterogeneous reactions

Science.gov (United States)

Friedly, John C.

1991-01-01

The familiar batch concept of extent of reaction is reexamined for systems of reactions occurring in open systems. Because species concentrations change as a result of transport processes as well as reactions in open systems, the extent of reaction has been less useful in practice in these applications. It is shown that by defining the extent of the equivalent batch reaction and a second contribution to the extent of reaction due to the transport processes, it is possible to treat the description of the dynamics of flow through porous media accompanied by many chemical reactions in a uniform, concise manner. This approach tends to isolate the reaction terms among themselves and away from the model partial differential equations, thereby enabling treatment of large problems involving both equilibrium and kinetically controlled reactions. Implications on the number of coupled partial differential equations necessary to be solved and on numerical algorithms for solving such problems are discussed. Examples provided illustrate the theory applied to solute transport in groundwater flow.
Frozen orientation disorder and rotation excitation in solid mixtures of methane and krypton (neutron diffraction experiments)

International Nuclear Information System (INIS)

Grondey, S.

1986-09-01

The effect of a statistical replacement of CH 4 molecules by Kr atoms on the rotational states in solid methane has been examined. Obviously the anisotropic molecular interaction (octopole-octopole interaction) is disturbed in a way analogous to magnetic systems with random internal fields. Inelastic neutron scattering experiments on solid mixtures (CH 4 ) 1-x Kr x with 0≤x≤0.35 have been carried out, and simple models have been developed to interpret the spectra. (orig./BHO)
Chemical reactions in reverse micelle systems

Science.gov (United States)

Matson, Dean W.; Fulton, John L.; Smith, Richard D.; Consani, Keith A.

1993-08-24

This invention is directed to conducting chemical reactions in reverse micelle or microemulsion systems comprising a substantially discontinuous phase including a polar fluid, typically an aqueous fluid, and a microemulsion promoter, typically a surfactant, for facilitating the formation of reverse micelles in the system. The system further includes a substantially continuous phase including a non-polar or low-polarity fluid material which is a gas under standard temperature and pressure and has a critical density, and which is generally a water-insoluble fluid in a near critical or supercritical state. Thus, the microemulsion system is maintained at a pressure and temperature such that the density of the non-polar or low-polarity fluid exceeds the critical density thereof. The method of carrying out chemical reactions generally comprises forming a first reverse micelle system including an aqueous fluid including reverse micelles in a water-insoluble fluid in the supercritical state. Then, a first reactant is introduced into the first reverse micelle system, and a chemical reaction is carried out with the first reactant to form a reaction product. In general, the first reactant can be incorporated into, and the product formed in, the reverse micelles. A second reactant can also be incorporated in the first reverse micelle system which is capable of reacting with the first reactant to form a product.
Reaction chemistry of nitrogen species in hydrothermal systems: Simple reactions, waste simulants, and actual wastes

International Nuclear Information System (INIS)

Dell'Orco, P.; Luan, L.; Proesmans, P.; Wilmanns, E.

1995-01-01

Results are presented from hydrothermal reaction systems containing organic components, nitrogen components, and an oxidant. Reaction chemistry observed in simple systems and in simple waste simulants is used to develop a model which presents global nitrogen chemistry in these reactive systems. The global reaction path suggested is then compared with results obtained for the treatment of an actual waste stream containing only C-N-0-H species
Periosteal reaction in systemic lupus erythematosus

International Nuclear Information System (INIS)

Glickstein, M.; Neustadter, L.; Dalinka, M.; Kricun, M.

1986-01-01

The authors report three patients with systemic lupus erythematosus and periosteal reaction. Two of the three cases had systemic vasculitis and the third had local ischemia with ischemic necrosis. (orig.)
Mass transfer with chemical reaction in multiphase systems

International Nuclear Information System (INIS)

Alper, E.

1983-01-01

These volumes deal with the phenomenon of 'mass transfer with chemical reaction' which is of industrial, biological and physiological importance. In process engineering, it is encountered both in separation processes and in reaction engineering and both aspects are covered here in four sections: introduction; gas-liquid system; liquid-liquid system; and gas-liquid-solid system
Probabilistic sensitivity analysis of biochemical reaction systems.

Science.gov (United States)

Zhang, Hong-Xuan; Dempsey, William P; Goutsias, John

2009-09-07

Sensitivity analysis is an indispensable tool for studying the robustness and fragility properties of biochemical reaction systems as well as for designing optimal approaches for selective perturbation and intervention. Deterministic sensitivity analysis techniques, using derivatives of the system response, have been extensively used in the literature. However, these techniques suffer from several drawbacks, which must be carefully considered before using them in problems of systems biology. We develop here a probabilistic approach to sensitivity analysis of biochemical reaction systems. The proposed technique employs a biophysically derived model for parameter fluctuations and, by using a recently suggested variance-based approach to sensitivity analysis [Saltelli et al., Chem. Rev. (Washington, D.C.) 105, 2811 (2005)], it leads to a powerful sensitivity analysis methodology for biochemical reaction systems. The approach presented in this paper addresses many problems associated with derivative-based sensitivity analysis techniques. Most importantly, it produces thermodynamically consistent sensitivity analysis results, can easily accommodate appreciable parameter variations, and allows for systematic investigation of high-order interaction effects. By employing a computational model of the mitogen-activated protein kinase signaling cascade, we demonstrate that our approach is well suited for sensitivity analysis of biochemical reaction systems and can produce a wealth of information about the sensitivity properties of such systems. The price to be paid, however, is a substantial increase in computational complexity over derivative-based techniques, which must be effectively addressed in order to make the proposed approach to sensitivity analysis more practical.
Parametric spatiotemporal oscillation in reaction-diffusion systems.

Science.gov (United States)

Ghosh, Shyamolina; Ray, Deb Shankar

2016-03-01

We consider a reaction-diffusion system in a homogeneous stable steady state. On perturbation by a time-dependent sinusoidal forcing of a suitable scaling parameter the system exhibits parametric spatiotemporal instability beyond a critical threshold frequency. We have formulated a general scheme to calculate the threshold condition for oscillation and the range of unstable spatial modes lying within a V-shaped region reminiscent of Arnold's tongue. Full numerical simulations show that depending on the specificity of nonlinearity of the models, the instability may result in time-periodic stationary patterns in the form of standing clusters or spatially localized breathing patterns with characteristic wavelengths. Our theoretical analysis of the parametric oscillation in reaction-diffusion system is corroborated by full numerical simulation of two well-known chemical dynamical models: chlorite-iodine-malonic acid and Briggs-Rauscher reactions.
Machine assisted reaction optimization: A self-optimizing reactor system for continuous-flow photochemical reactions

KAUST Repository

Poscharny, K.; Fabry, D.C.; Heddrich, S.; Sugiono, E.; Liauw, M.A.; Rueping, Magnus

2018-01-01

A methodology for the synthesis of oxetanes from benzophenone and furan derivatives is presented. UV-light irradiation in batch and flow systems allowed the [2 + 2] cycloaddition reaction to proceed and a broad range of oxetanes could be synthesized in manual and automated fashion. The identification of high-yielding reaction parameters was achieved through a new self-optimizing photoreactor system.
Machine assisted reaction optimization: A self-optimizing reactor system for continuous-flow photochemical reactions

KAUST Repository

Poscharny, K.

2018-04-07

A methodology for the synthesis of oxetanes from benzophenone and furan derivatives is presented. UV-light irradiation in batch and flow systems allowed the [2 + 2] cycloaddition reaction to proceed and a broad range of oxetanes could be synthesized in manual and automated fashion. The identification of high-yielding reaction parameters was achieved through a new self-optimizing photoreactor system.
Propagating fronts in reaction-transport systems with memory

Energy Technology Data Exchange (ETDEWEB)

Yadav, A. [Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314 (United States)], E-mail: ayadav1@lsu.edu; Fedotov, Sergei [School of Mathematics, University of Manchester, Manchester M60 1DQ (United Kingdom)], E-mail: sergei.fedotov@manchester.ac.uk; Mendez, Vicenc [Grup de Fisica Estadistica, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)], E-mail: vicenc.mendez@uab.es; Horsthemke, Werner [Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314 (United States)], E-mail: whorsthe@smu.edu

2007-11-26

In reaction-transport systems with non-standard diffusion, the memory of the transport causes a coupling of reactions and transport. We investigate the effect of this coupling for systems with Fisher-type kinetics and obtain a general analytical expression for the front speed. We apply our results to the specific case of subdiffusion.
Low energy collision experiments using the beam guide technique. Charge transfer cross sections of Ar/sup 3+/ and Kr/sup 3+/ in their own gases

Energy Technology Data Exchange (ETDEWEB)

Okuno, Kazuhiko; Kaneko, Yozaburo

1986-12-01

The trajectories of charged particles moving in an octopole ion beam guide (OPIG) are computer-simulated for various initial conditions of motion. Boundary conditions between the stable and unstable regions of beam trajectory in OPIG are obtained. These calculated results are very useful for operation of OPIG under the best condition. In low energy collision experiments using the beam guide technique, cross sections of one-, two- and three-electron capture processes in collision systems of Ar/sup 3+/-Ar and Kr/sup 3+/-Kr are measured in energy region from 0.375 to 768 eV in center-of-mass system. In both collision systems, one-electron capture reaction is predominant in higher energy side, however, the dominant reaction changes from one-electron capture reaction to the symmetric resonant three-electron capture reaction in the low energy region below about 10 eV. As was predicted, it was first confirmed that each cross section obtained for symmetric resonant triple-charge-transfer reaction of Ar/sup 3+/ and Kr/sup 3+/ at the low energy end of Ecm = 0.375 eV is larger than both cross sections of symmetric resonant double-charge-transfer for the doubly charged ion and symmetric resonant single-charge-transfer for the singly charged ion.
Long life reaction control system design

Science.gov (United States)

Fanciullo, Thomas J.; Judd, Craig

1993-02-01

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

Analytically solvable models of reaction-diffusion systems

Energy Technology Data Exchange (ETDEWEB)

Zemskov, E P; Kassner, K [Institut fuer Theoretische Physik, Otto-von-Guericke-Universitaet, Universitaetsplatz 2, 39106 Magdeburg (Germany)

2004-05-01

We consider a class of analytically solvable models of reaction-diffusion systems. An analytical treatment is possible because the nonlinear reaction term is approximated by a piecewise linear function. As particular examples we choose front and pulse solutions to illustrate the matching procedure in the one-dimensional case.
Sodium-water reaction product flow system

Energy Technology Data Exchange (ETDEWEB)

Shirataki, K; Wada, H

1978-11-18

Purpose: To provide the subject equipments wherein thermal insulating layers which neither exfoliate nor react by the impact due to high temperature sodium and hydrogen gas and are used for mitigating the thermal impact are provided on the inner surfaces of the emission system equipments, thereby preventing the destruction of the emission system equipments. Constitution: Thermal insulating layers are formed on the inner surfaces of sodium-water reaction product emission system equipments, that is, the inner surface of the emission system pipeline, that of the accommodation vessel and the surface of the cyclone separator, by film treatment, coating or heat resisting coating, and these surfaces are covered with the layers. Each of the layers is made of a material which does not cause a rapid reaction with high temperature sodium or hydrogen gas nor exfoliates and is withstandable for several seconds in which the thermal impact of at least the emission system comes into question, and its thickness is more than one capable of securing the necessary thermal resistance computed by the thermal impact analysis of the emission system.
Sodium-water reaction product flow system

International Nuclear Information System (INIS)

Shirataki, Koji; Wada, Hozumi.

1978-01-01

Purpose: To provide the subject equipments wherein thermal insulating layers which neither exfoliate nor react by the impact due to high temperature sodium and hydrogen gas and are used for mitigating the thermal impact are provided on the inner surfaces of the emission system equipments, thereby preventing the destruction of the emission system equipments. Constitution: Thermal insulating layers are formed on the inner surfaces of sodium-water reaction product emission system equipments, that is, the inner surface of the emission system pipeline, that of the accommodation vessel and the surface of the cyclone separator, by film treatment, coating or heat resisting coating, and these surfaces are covered with the layers. Each of the layers is made of a material which does not cause a rapid reaction with high temperature sodium or hydrogen gas nor exfoliates and is withstandable for several seconds in which the thermal impact of at least the emission system comes into question, and its thickness is more than one capable of securing the necessary thermal resistance computed by the thermal impact analysis of the emission system. (Yoshihara, H.)
Experimental evaluation of improved dual temperature hydrogen isotopic exchange reaction system

International Nuclear Information System (INIS)

Asakura, Yamato; Uchida, Shunsuke

1984-01-01

A proposed dual temperature hydrogen isotopic exchange reaction system between water and hydrogen gas is evaluated experimentally. The proposed system is composed of low temperature co-current reactors for reaction between water mists and hydrogen gas and high temperature co-current reactors for reaction between water vapor and hydrogen gas. Thus, operation is possible under atmospheric pressure with high reaction efficiency. Using the pilot test system which is composed of ten low temperature (30 0 C) reaction units and ten high temperature (200 0 C) reaction units, an experimental separation of deuterium from light water is carried out. The enrichment factor under steady state conditions, its dependency on operating time, and the reaction period necessary to obtain the steady state enrichment factor are determined experimentally and compared with calculations. It is shown that separation ability in a multistage reaction system can be estimated by numerical calculation using actual reaction efficiency in a unit reactor. (author)
Action-reaction based parameters identification and states estimation of flexible systems

OpenAIRE

Khalil, Islam; Kunt, Emrah Deniz; Şabanoviç, Asif; Sabanovic, Asif

2012-01-01

This work attempts to identify and estimate flexible system's parameters and states by a simple utilization of the Action-Reaction law of dynamical systems. Attached actuator to a dynamical system or environmental interaction imposes an action that is instantaneously followed by a dynamical system reaction. The dynamical system's reaction carries full information about the dynamical system including system parameters, dynamics and externally applied forces that arise due to system interaction...
Nonlinear analysis of a reaction-diffusion system: Amplitude equations

Energy Technology Data Exchange (ETDEWEB)

Zemskov, E. P., E-mail: zemskov@ccas.ru [Russian Academy of Sciences, Dorodnicyn Computing Center (Russian Federation)

2012-10-15

A reaction-diffusion system with a nonlinear diffusion term is considered. Based on nonlinear analysis, the amplitude equations are obtained in the cases of the Hopf and Turing instabilities in the system. Turing pattern-forming regions in the parameter space are determined for supercritical and subcritical instabilities in a two-component reaction-diffusion system.
The incidence and features of systemic reactions to skin prick tests.

Science.gov (United States)

Sellaturay, Priya; Nasser, Shuaib; Ewan, Pamela

2015-09-01

Skin prick testing (SPT) has been regarded as a safe procedure with few systemic reactions. To evaluate the rate of systemic reactions and their associations after SPT in the largest population to date. In this study reactions were recorded prospectively in a specialist UK allergy clinic for 6 years (2007-2013). An estimated 31,000 patients underwent SPT. Twenty-four patients (age range 7 months to 56 years, mean 23.5 years, 17 female patients, 12 with asthma) had systemic reactions. The rate of systemic reactions to SPT was 0.077%. The likely allergens causing the reaction were foods (18; peanut, 7; walnut, 1; Brazil nut, 2; pistachio, 1; lupin, 1; cow's milk, 2; shrimp, 1; spinach, 1; legume, 1; soy, 1), aeroallergens (4; rabbit, 1; rat, 1; ragwort, 1; grass pollen, 1), wasp venom (1), and Tazocin (1). The causative SPT wheal was larger than 8 mm in 75%. The reaction to Tazocin was severe, with anaphylaxis occurring minutes after SPT. Reactions were treated immediately in the clinic and did not require further medical care. In this largest single-center study, the rate of systemic reactions after SPT was 77 per 100,000 patients. It is the first study to identify foods as a common and important cause (75%), with nuts posing the highest risk. This study reports the first systemic reaction to venom SPT and the first anaphylactic reaction after drug SPT. There was an association with a history of severe reactions and large skin test reaction. There are risks, albeit small, when undertaking SPT. Copyright © 2015 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.
Decay to Equilibrium for Energy-Reaction-Diffusion Systems

KAUST Repository

Haskovec, Jan

2018-02-06

We derive thermodynamically consistent models of reaction-diffusion equations coupled to a heat equation. While the total energy is conserved, the total entropy serves as a driving functional such that the full coupled system is a gradient flow. The novelty of the approach is the Onsager structure, which is the dual form of a gradient system, and the formulation in terms of the densities and the internal energy. In these variables it is possible to assume that the entropy density is strictly concave such that there is a unique maximizer (thermodynamical equilibrium) given linear constraints on the total energy and suitable density constraints. We consider two particular systems of this type, namely, a diffusion-reaction bipolar energy transport system, and a drift-diffusion-reaction energy transport system with confining potential. We prove corresponding entropy-entropy production inequalities with explicitly calculable constants and establish the convergence to thermodynamical equilibrium, first in entropy and later in L norm using Cziszár–Kullback–Pinsker type inequalities.
Decay to Equilibrium for Energy-Reaction-Diffusion Systems

KAUST Repository

Haskovec, Jan; Hittmeir, Sabine; Markowich, Peter A.; Mielke, Alexander

2018-01-01

We derive thermodynamically consistent models of reaction-diffusion equations coupled to a heat equation. While the total energy is conserved, the total entropy serves as a driving functional such that the full coupled system is a gradient flow. The novelty of the approach is the Onsager structure, which is the dual form of a gradient system, and the formulation in terms of the densities and the internal energy. In these variables it is possible to assume that the entropy density is strictly concave such that there is a unique maximizer (thermodynamical equilibrium) given linear constraints on the total energy and suitable density constraints. We consider two particular systems of this type, namely, a diffusion-reaction bipolar energy transport system, and a drift-diffusion-reaction energy transport system with confining potential. We prove corresponding entropy-entropy production inequalities with explicitly calculable constants and establish the convergence to thermodynamical equilibrium, first in entropy and later in L norm using Cziszár–Kullback–Pinsker type inequalities.
Action-reaction based parameters identification and states estimation of flexible systems

OpenAIRE

Khalil, Islam Shoukry Mohammed; Şabanoviç, Asif; Sabanovic, Asif

2010-01-01

This work attempts to identify and estimate flexible system’s parameters and states by a simple utilization of the Action-Reaction law of dynamical systems. Attached actuator to a dynamical system or environmental interaction imposes an action that is instantaneously followed by a dynamical system reaction. The dynamical system’s reaction carries full information about the dynamical system including system parameters, dynamics and externally applied forces that arise due to system interaction...
Thermodynamically consistent Bayesian analysis of closed biochemical reaction systems

Directory of Open Access Journals (Sweden)

Goutsias John

2010-11-01

Full Text Available Abstract Background Estimating the rate constants of a biochemical reaction system with known stoichiometry from noisy time series measurements of molecular concentrations is an important step for building predictive models of cellular function. Inference techniques currently available in the literature may produce rate constant values that defy necessary constraints imposed by the fundamental laws of thermodynamics. As a result, these techniques may lead to biochemical reaction systems whose concentration dynamics could not possibly occur in nature. Therefore, development of a thermodynamically consistent approach for estimating the rate constants of a biochemical reaction system is highly desirable. Results We introduce a Bayesian analysis approach for computing thermodynamically consistent estimates of the rate constants of a closed biochemical reaction system with known stoichiometry given experimental data. Our method employs an appropriately designed prior probability density function that effectively integrates fundamental biophysical and thermodynamic knowledge into the inference problem. Moreover, it takes into account experimental strategies for collecting informative observations of molecular concentrations through perturbations. The proposed method employs a maximization-expectation-maximization algorithm that provides thermodynamically feasible estimates of the rate constant values and computes appropriate measures of estimation accuracy. We demonstrate various aspects of the proposed method on synthetic data obtained by simulating a subset of a well-known model of the EGF/ERK signaling pathway, and examine its robustness under conditions that violate key assumptions. Software, coded in MATLAB®, which implements all Bayesian analysis techniques discussed in this paper, is available free of charge at http://www.cis.jhu.edu/~goutsias/CSS%20lab/software.html. Conclusions Our approach provides an attractive statistical methodology for
Reaction-Transport Systems Mesoscopic Foundations, Fronts, and Spatial Instabilities

CERN Document Server

Horsthemke, Werner; Mendez, Vicenc

2010-01-01

This book is an introduction to the dynamics of reaction-diffusion systems, with a focus on fronts and stationary spatial patterns. Emphasis is on systems that are non-standard in the sense that either the transport is not simply classical diffusion (Brownian motion) or the system is not homogeneous. A important feature is the derivation of the basic phenomenological equations from the mesoscopic system properties. Topics addressed include transport with inertia, described by persistent random walks and hyperbolic reaction-transport equations and transport by anomalous diffusion, in particular subdiffusion, where the mean square displacement grows sublinearly with time. In particular reaction-diffusion systems are studied where the medium is in turn either spatially inhomogeneous, compositionally heterogeneous or spatially discrete. Applications span a vast range of interdisciplinary fields and the systems considered can be as different as human or animal groups migrating under external influences, population...
Reaction dynamics in polyatomic molecular systems

Energy Technology Data Exchange (ETDEWEB)

Miller, W.H. [Lawrence Berkeley Laboratory, CA (United States)

1993-12-01

The goal of this program is the development of theoretical methods and models for describing the dynamics of chemical reactions, with specific interest for application to polyatomic molecular systems of special interest and relevance. There is interest in developing the most rigorous possible theoretical approaches and also in more approximate treatments that are more readily applicable to complex systems.
The Theory of Thermodynamics for Chemical Reactions in Dispersed Heterogeneous Systems

Science.gov (United States)

Yongqiang; Baojiao; Jianfeng

1997-07-01

In this paper, the expressions of Gibbs energy change, enthalpy change, entropy change, and equilibrium constant for chemical reactions in dispersed heterogeneous systems are derived using classical thermodynamics theory. The thermodynamical relations for the same reaction system between the dispersed and the block state are also derived. The effects of degree of dispersion on thermodynamical properties, reaction directions, and chemical equilibria are discussed. The results show that the present equation of thermodynamics for chemical reactions is only a special case of the above-mentioned formulas and that the effect of the dispersity of a heterogeneous system on the chemical reaction obeys the Le Chatelier principle of movement of equilibria.
Splitting Schemes & Segregation In Reaction-(Cross-)Diffusion Systems

OpenAIRE

Carrillo, José A.; Fagioli, Simone; Santambrogio, Filippo; Schmidtchen, Markus

2017-01-01

One of the most fascinating phenomena observed in reaction-diffusion systems is the emergence of segregated solutions, i.e. population densities with disjoint supports. We analyse such a reaction cross-diffusion system. In order to prove existence of weak solutions for a wide class of initial data without restriction about their supports or their positivity, we propose a variational splitting scheme combining ODEs with methods from optimal transport. In addition, this approach allows us to pr...
Chemical modeling of irreversible reactions in nuclear waste-water-rock systems

International Nuclear Information System (INIS)

Wolery, T.J.

1981-02-01

Chemical models of aqueous geochemical systems are usually built on the concept of thermodynamic equilibrium. Though many elementary reactions in a geochemical system may be close to equilibrium, others may not be. Chemical models of aqueous fluids should take into account that many aqueous redox reactions are among the latter. The behavior of redox reactions may critically affect migration of certain radionuclides, especially the actinides. In addition, the progress of reaction in geochemical systems requires thermodynamic driving forces associated with elementary reactions not at equilibrium, which are termed irreversible reactions. Both static chemical models of fluids and dynamic models of reacting systems have been applied to a wide spectrum of problems in water-rock interactions. Potential applications in nuclear waste disposal range from problems in geochemical aspects of site evaluation to those of waste-water-rock interactions. However, much further work in the laboratory and the field will be required to develop and verify such applications of chemical modeling
Recent developments in biocatalysis in multiphasic ionic liquid reaction systems.

Science.gov (United States)

Meyer, Lars-Erik; von Langermann, Jan; Kragl, Udo

2018-06-01

Ionic liquids are well known and frequently used 'designer solvents' for biocatalytic reactions. This review highlights recent achievements in the field of multiphasic ionic liquid-based reaction concepts. It covers classical biphasic systems including supported ionic liquid phases, thermo-regulated multi-component solvent systems (TMS) and polymerized ionic liquids. These powerful concepts combine unique reaction conditions with a high potential for future applications on a laboratory and industrial scale. The presence of a multiphasic system simplifies downstream processing due to the distribution of the catalyst and reactants in different phases.
Generic Model-Based Tailor-Made Design and Analysis of Biphasic Reaction Systems

DEFF Research Database (Denmark)

Anantpinijwatna, Amata

systems have a broad range of application, such as the manufacture of petroleum based chemicals, pharmaceuticals, and agro-bio products. Major considerations in the design and analysis of biphasic reaction systems are physical and chemical equilibria, kinetic mechanisms, and reaction rates. The primary...... contribution of this thesis is the development of a systematic modelling framework for the biphasic reaction system. The developed framework consists of three modules describing phase equilibria, reactions and mass transfer, and material balances of such processes. Correlative and predictive thermodynamic......Biphasic reaction systems are composed of immiscible aqueous and organic liquid phases where reactants, products, and catalysts are partitioned. These biphasic conditions point to novel synthesis paths, higher yields, and faster reactions, as well as facilitate product separation. The biphasic...
Options for axisymmetric operation of MFTF-B

International Nuclear Information System (INIS)

Fenstermacher, M.E.; Devoto, R.S.; Thomassen, K.I.

1986-01-01

The flexibility of MFTF-B for axisymmetric experiments has been investigated. Interhcanging the axicell coils and increasing their separation results in an axisymmetric plug cell with 12:1 and 6:1 inner and outer mirror ratios, respectively. For axisymmetric operation, the sloshing-ion neutral beams, ECRH gyrotrons, and the pumping system would be moved to the axicell. Stabilization by E-rings could be explored in this configuration. With the addition of octopole magnets, off-axis multipole stabilization could also be tested. Operating points for octopole and E-ring-stabilized configurations with properties similar to those of the quadrupole MFTF-B, namely T/sub ic/ = 10 - 15 keV and n/sub c/ approx. = 3 x 10 13 cm -3 , have been obtained. Because of the negligible radial transport of central-cell ions, the required neutral-beam power in the central cell has been dramatically reduced. In addition, because MHD stabilization is achieved by off-axis hot electrons in both cases, much lower barrier beta is possible, which aids in reducing the barrier ECRH power. Total ECRH power in the end cell is projected to be approx. =1 MW. Possible operating points for both octopole and E-ring configurations are described along with the stability considerations involved
Elastic and inelastic pion reactions on few nucleon systems

International Nuclear Information System (INIS)

Lensky, V.

2007-01-01

In the present work, we are studying elastic and inelastic pion reactions on few-body systems within the framework of chiral effective theory. We consider two specific reactions involving pions on few-nucleon systems, namely pion production in nucleon-nucleon collisions, and incoherent pion photoproduction on the deuteron. These two reactions are closely related to the issue of dispersive and absorptive corrections to the pion-deuteron scattering length, which we also consider in our analysis. The incoherent pion photoproduction is also considered as the possible source for a high-precision determination of the neutron-neutron scattering length. (orig.)

Elastic and inelastic pion reactions on few nucleon systems

Energy Technology Data Exchange (ETDEWEB)

Lensky, V.

2007-09-29

In the present work, we are studying elastic and inelastic pion reactions on few-body systems within the framework of chiral effective theory. We consider two specific reactions involving pions on few-nucleon systems, namely pion production in nucleon-nucleon collisions, and incoherent pion photoproduction on the deuteron. These two reactions are closely related to the issue of dispersive and absorptive corrections to the pion-deuteron scattering length, which we also consider in our analysis. The incoherent pion photoproduction is also considered as the possible source for a high-precision determination of the neutron-neutron scattering length. (orig.)
Versatile Dual Photoresponsive System for Precise Control of Chemical Reactions.

Science.gov (United States)

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

2017-08-22

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

International Nuclear Information System (INIS)

Scagliarini, A; Biferale, L; Sbragaglia, M; Mantovani, F; Pivanti, M; Schifano, S F; Tripiccione, R; Pozzati, F; Toschi, F

2011-01-01

A special feature of Rayleigh-Taylor systems with chemical reactions is the competition between turbulent mixing and the 'burning processes', which leads to a highly non-trivial dynamics. We studied the problem performing high resolution numerical simulations of a 2d system, using a thermal lattice Boltzmann (LB) model. We spanned the various regimes emerging at changing the relative chemical/turbulent time scales, from slow to fast reaction; in the former case we found numerical evidence of an enhancement of the front propagation speed (with respect to the laminar case), providing a phenomenological argument to explain the observed behaviour. When the reaction is very fast, instead, the formation of sharp fronts separating patches of pure phases, leads to an increase of intermittency in the small scale statistics of the temperature field.
Mars Ascent Vehicle Reaction Control System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — During this Phase I NASA program, Valley Tech Systems (VTS) will develop an innovative solid Reaction Control System (RCS) architecture concept design that can...
The entropy dissipation method for spatially inhomogeneous reaction-diffusion-type systems

KAUST Repository

Di Francesco, M.; Fellner, K.; Markowich, P. A

2008-01-01

and reaction terms and admit fewer conservation laws than the size of the system. In particular, we successfully apply the entropy approach to general linear systems and to a nonlinear example of a reaction-diffusion-convection system arising in solid
Amplitude equations for a sub-diffusive reaction-diffusion system

International Nuclear Information System (INIS)

Nec, Y; Nepomnyashchy, A A

2008-01-01

A sub-diffusive reaction-diffusion system with a positive definite memory operator and a nonlinear reaction term is analysed. Amplitude equations (Ginzburg-Landau type) are derived for short wave (Turing) and long wave (Hopf) bifurcation points
Synthesis of hexagonal gold nanoparticles using a microfluidic reaction system

International Nuclear Information System (INIS)

Weng, Chen-Hsun; Lee, Gwo-Bin; Huang, Chih-Chia; Yeh, Chen-Sheng; Lei, Huan-Yao

2008-01-01

A new microfluidic reaction system capable of mixing, transporting and reacting is developed for the synthesis of gold nanoparticles. It allows for a rapid and a cost-effective approach to accelerate the synthesis of gold nanoparticles. The microfluidic reaction chip is made from micro-electro-mechanical-system technologies which integrate a micro-mixer, micro-pumps, a micro-valve, micro-heaters and a micro temperature sensor on a single chip. Successful synthesis of dispersed gold nanoparticles has been demonstrated within a shorter period of time, as compared to traditional methods. It is experimentally found that precise control of the mixing/heating time for gold salts and reducing agents plays an essential role in the synthesis of gold nanoparticles. The growth process of hexagonal gold nanoparticles by a thermal aqueous approach is also systematically studied by using the same microfluidic reaction system. The development of the microfluidic reaction system could be promising for the synthesis of functional nanoparticles for future biomedical applications
Inertial confinement fusion reaction chamber and power conversion system study

International Nuclear Information System (INIS)

Maya, I.; Schultz, K.R.; Battaglia, J.M.

1984-09-01

GA Technologies has developed a conceptual ICF reactor system based on the Cascade rotating-bed reaction chamber concept. Unique features of the system design include the use of low activation SiC in a reaction chamber constructed of box-shaped tiles held together in compression by prestressing tendons to the vacuum chamber. Circulating Li 2 O granules serve as the tritium breeding and energy transport material, cascading down the sides of the reaction chamber to the power conversion system. The total tritium inventory of the system is 6 kg; tritium recovery is accomplished directly from the granules via the vacuum system. A system for centrifugal throw transport of the hot Li 2 O granules from the reaction chamber to the power conversion system has been developed. A number of issues were evaluated during the course of this study. These include the response of first-layer granules to the intense microexplosion surface heat flux, cost effective fabrication of Li 2 O granules, tritium inventory and recovery issues, the thermodynamics of solids-flow options, vacuum versus helium-medium heat transfer, and the tradeoffs of capital cost versus efficiency for alternate heat exchange and power conversion system option. The resultant design options appear to be economically competitive, safe, and environmentally attractive
Delay-induced wave instabilities in single-species reaction-diffusion systems

Science.gov (United States)

Otto, Andereas; Wang, Jian; Radons, Günter

2017-11-01

The Turing (wave) instability is only possible in reaction-diffusion systems with more than one (two) components. Motivated by the fact that a time delay increases the dimension of a system, we investigate the presence of diffusion-driven instabilities in single-species reaction-diffusion systems with delay. The stability of arbitrary one-component systems with a single discrete delay, with distributed delay, or with a variable delay is systematically analyzed. We show that a wave instability can appear from an equilibrium of single-species reaction-diffusion systems with fluctuating or distributed delay, which is not possible in similar systems with constant discrete delay or without delay. More precisely, we show by basic analytic arguments and by numerical simulations that fast asymmetric delay fluctuations or asymmetrically distributed delays can lead to wave instabilities in these systems. Examples, for the resulting traveling waves are shown for a Fisher-KPP equation with distributed delay in the reaction term. In addition, we have studied diffusion-induced instabilities from homogeneous periodic orbits in the same systems with variable delay, where the homogeneous periodic orbits are attracting resonant periodic solutions of the system without diffusion, i.e., periodic orbits of the Hutchinson equation with time-varying delay. If diffusion is introduced, standing waves can emerge whose temporal period is equal to the period of the variable delay.
Externally controlled anisotropy in pattern-forming reaction-diffusion systems.

Science.gov (United States)

Escala, Dario M; Guiu-Souto, Jacobo; Muñuzuri, Alberto P

2015-06-01

The effect of centrifugal forces is analyzed in a pattern-forming reaction-diffusion system. Numerical simulations conducted on the appropriate extension of the Oregonator model for the Belousov-Zhabotinsky reaction show a great variety of dynamical behaviors in such a system. In general, the system exhibits an anisotropy that results in new types of patterns or in a global displacement of the previous one. We consider the effect of both constant and periodically modulated centrifugal forces on the different types of patterns that the system may exhibit. A detailed analysis of the patterns and behaviors observed for the different parameter values considered is presented here.
Nonlinear reaction-diffusion systems conditional symmetry, exact solutions and their applications in biology

CERN Document Server

Cherniha, Roman

2017-01-01

This book presents several fundamental results in solving nonlinear reaction-diffusion equations and systems using symmetry-based methods. Reaction-diffusion systems are fundamental modeling tools for mathematical biology with applications to ecology, population dynamics, pattern formation, morphogenesis, enzymatic reactions and chemotaxis. The book discusses the properties of nonlinear reaction-diffusion systems, which are relevant for biological applications, from the symmetry point of view, providing rigorous definitions and constructive algorithms to search for conditional symmetry (a nontrivial generalization of the well-known Lie symmetry) of nonlinear reaction-diffusion systems. In order to present applications to population dynamics, it focuses mainly on two- and three-component diffusive Lotka-Volterra systems. While it is primarily a valuable guide for researchers working with reaction-diffusion systems and those developing the theoretical aspects of conditional symmetry conception,...
Development of nuclear reaction data retrieval system on Meme media

International Nuclear Information System (INIS)

Ohbayasi, Yosihide; Masui, Hiroshi; Aoyama, Shigeyoshi; Kato, Kiyoshi; Chiba, Masaki

2000-01-01

A newly designed retrieval system of charged particle nuclear reaction data is developed on Meme media architecture. We designed the network-based (client-server) retrieval system. The server system is constructed on a UNIX workstation with a relational database, and the client system is constructed on Microsoft Windows PC using an IntelligentPad software package. The IntelligentPad is currently available as developing Meme media. We will develop the system to realize effective utilization of nuclear reaction data: I. 'Re-production, Re-edit, Re-use', II. 'Circulation, Coordination and Evolution', III. 'Knowledge discovery'. (author)
Stochastic thermodynamics and entropy production of chemical reaction systems

Science.gov (United States)

Tomé, Tânia; de Oliveira, Mário J.

2018-06-01

We investigate the nonequilibrium stationary states of systems consisting of chemical reactions among molecules of several chemical species. To this end, we introduce and develop a stochastic formulation of nonequilibrium thermodynamics of chemical reaction systems based on a master equation defined on the space of microscopic chemical states and on appropriate definitions of entropy and entropy production. The system is in contact with a heat reservoir and is placed out of equilibrium by the contact with particle reservoirs. In our approach, the fluxes of various types, such as the heat and particle fluxes, play a fundamental role in characterizing the nonequilibrium chemical state. We show that the rate of entropy production in the stationary nonequilibrium state is a bilinear form in the affinities and the fluxes of reaction, which are expressed in terms of rate constants and transition rates, respectively. We also show how the description in terms of microscopic states can be reduced to a description in terms of the numbers of particles of each species, from which follows the chemical master equation. As an example, we calculate the rate of entropy production of the first and second Schlögl reaction models.
Reaction-diffusion systems in intracellular molecular transport and control.

Science.gov (United States)

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

2010-06-07

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

International Nuclear Information System (INIS)

Peng Xiaoshi; Wang Feng; Liu Shenye; Jiang Xiaohua; Tang Qi

2010-01-01

In order to accurately measure the history of fusion reaction for experimental study of inertial confinement fusion, we advance the design of a fusion reaction-history measurement system with high temporal resolution. The diagnostic system is composed of plastic scintillator and nose cone, an optical imaging system and the system of optic streak camera. Analyzing the capability of the system indicated that the instrument measured fusion reaction history at temporal resolution as low as 55ps and 40ps correspond to 2.45MeV DD neutrons and 14.03MeV DT neutrons. The instrument is able to measure the fusion reaction history at yields 1.5 x 10 9 DD neutrons, about 4 x 10 8 DT neutrons are required for a similar quality signal. (authors)
Estimation and prediction of convection-diffusion-reaction systems from point measurement

NARCIS (Netherlands)

Vries, D.

2008-01-01

Different procedures with respect to estimation and prediction of systems characterized by convection, diffusion and reactions on the basis of point measurement data, have been studied. Two applications of these convection-diffusion-reaction (CDR) systems have been used as a case study of the
Environmental radioactivity research on the Fukushima Dai-ichi Nuclear Power Plant accident by ICP-MS

International Nuclear Information System (INIS)

Ohno, Takeshi; Muramatsu, Yasuyuki

2015-01-01

Inductively coupled plasma (ICP) is characterized by high ionization efficiency for almost all elements. Recently, a triple quadrupole ICP-MS (ICP-MS/MS) has been applied to the measurements of isotope ratios for ultra-low level radioisotopes. The ICP-MS/MS features an additional quadrupole mass filter situated in front of the octopole reaction cell and quadrupole mass filter, which allows only the analyte ion to enter the cell by rejecting all the other ions. In this manuscript, we review recent studies on environmental radioactivity in Fukushima achieved by ICP-MS/MS techniques. (author)
The effects of reactants ratios, reaction temperatures and times on Maillard reaction products of the L-ascorbic acid/L-glutamic acid system

Directory of Open Access Journals (Sweden)

Yong-Yan ZHOU

2016-01-01

Full Text Available Abstract The transformation law of the Maillard reaction products with three different reactants ratios - equimolar reactants, excess L-glutamic acid and excess L-ascorbic acid reaction respectively, five different temperatures, and different time conditions for the L-ascorbic acid / L-glutamic acid system were investigated. Results showed that, the increase of the reaction time and temperature led to the increase of the browning products, uncoloured intermediate products, as well as aroma compounds. Compared with the equimolar reaction system, the excess L-ascorbic acid reaction system produced more browning products and uncoloured intermediate products, while the aroma compounds production remained the same. In the excess L-glutamic acid system, the uncoloured intermediate products increased slightly, the browning products remained the same, while the aroma compounds increased.
Stochastic modeling and simulation of reaction-diffusion system with Hill function dynamics.

Science.gov (United States)

Chen, Minghan; Li, Fei; Wang, Shuo; Cao, Young

2017-03-14

Stochastic simulation of reaction-diffusion systems presents great challenges for spatiotemporal biological modeling and simulation. One widely used framework for stochastic simulation of reaction-diffusion systems is reaction diffusion master equation (RDME). Previous studies have discovered that for the RDME, when discretization size approaches zero, reaction time for bimolecular reactions in high dimensional domains tends to infinity. In this paper, we demonstrate that in the 1D domain, highly nonlinear reaction dynamics given by Hill function may also have dramatic change when discretization size is smaller than a critical value. Moreover, we discuss methods to avoid this problem: smoothing over space, fixed length smoothing over space and a hybrid method. Our analysis reveals that the switch-like Hill dynamics reduces to a linear function of discretization size when the discretization size is small enough. The three proposed methods could correctly (under certain precision) simulate Hill function dynamics in the microscopic RDME system.
Capability of LEP-type surfaces to describe noncollinear reactions 2 - Polyatomic systems

CERN Document Server

Espinosa-Garcia, Joaquin

2001-01-01

In this second article of the series, the popular LEP-type surface for collinear reaction paths and a "bent" surface, which involves a saddle point geometry with a nonlinear central angle, were used to examine the capacity of LEP-type surfaces to describe the kinetics and dynamics of noncollinear reaction paths in polyatomic systems. Analyzing the geometries, vibrational frequencies, curvature along the reaction path (to estimate the tunneling effect and the reaction coordinate-bound modes coupling), and the variational transition- state theory thermal rate constants for the NH//3 + O(**3P) reaction, we found that the "collinear" LEP-type and the "bent" surfaces for this polyatomic system show similar behavior, thus allowing a considerable saving in time and computational effort. This agreement is especially encouraging for this polyatomic system because in the Cs symmetry the reaction proceeds via two electronic states of symmetries **3A prime and **3A double prime , which had to be independently calibrated....

Saponification reaction system: a detailed mass transfer coefficient determination.

Science.gov (United States)

Pečar, Darja; Goršek, Andreja

2015-01-01

The saponification of an aromatic ester with an aqueous sodium hydroxide was studied within a heterogeneous reaction medium in order to determine the overall kinetics of the selected system. The extended thermo-kinetic model was developed compared to the previously used simple one. The reaction rate within a heterogeneous liquid-liquid system incorporates a chemical kinetics term as well as mass transfer between both phases. Chemical rate constant was obtained from experiments within a homogeneous medium, whilst the mass-transfer coefficient was determined separately. The measured thermal profiles were then the bases for determining the overall reaction-rate. This study presents the development of an extended kinetic model for considering mass transfer regarding the saponification of ethyl benzoate with sodium hydroxide within a heterogeneous reaction medium. The time-dependences are presented for the mass transfer coefficient and the interfacial areas at different heterogeneous stages and temperatures. The results indicated an important role of reliable kinetic model, as significant difference in k(L)a product was obtained with extended and simple approach.
The Simplest Chronoscope V: A Theory of Dual Primary and Secondary Reaction Time Systems.

Science.gov (United States)

Montare, Alberto

2016-12-01

Extending work by Montare, visual simple reaction time, choice reaction time, discriminative reaction time, and overall reaction time scores obtained from college students by the simplest chronoscope (a falling meterstick) method were significantly faster as well as significantly less variable than scores of the same individuals from electromechanical reaction timers (machine method). Results supported the existence of dual reaction time systems: an ancient primary reaction time system theoretically activating the V5 parietal area of the dorsal visual stream that evolved to process significantly faster sensory-motor reactions to sudden stimulations arising from environmental objects in motion, and a secondary reaction time system theoretically activating the V4 temporal area of the ventral visual stream that subsequently evolved to process significantly slower sensory-perceptual-motor reactions to sudden stimulations arising from motionless colored objects. © The Author(s) 2016.
Point source identification in nonlinear advection–diffusion–reaction systems

International Nuclear Information System (INIS)

Mamonov, A V; Tsai, Y-H R

2013-01-01

We consider a problem of identification of point sources in time-dependent advection–diffusion systems with a nonlinear reaction term. The linear counterpart of the problem in question can be reduced to solving a system of nonlinear algebraic equations via the use of adjoint equations. We extend this approach by constructing an algorithm that solves the problem iteratively to account for the nonlinearity of the reaction term. We study the question of improving the quality of source identification by adding more measurements adaptively using the solution obtained previously with a smaller number of measurements. (paper)
Pattern formation in reaction diffusion systems with finite geometry

International Nuclear Information System (INIS)

Borzi, C.; Wio, H.

1990-04-01

We analyze the one-component, one-dimensional, reaction-diffusion equation through a simple inverse method. We confine the system and fix the boundary conditions as to induce pattern formation. We analyze the stability of those patterns. Our goal is to get information about the reaction term out of the preknowledgment of the pattern. (author). 5 refs
An incomplete assembly with thresholding algorithm for systems of reaction-diffusion equations in three space dimensions IAT for reaction-diffusion systems

International Nuclear Information System (INIS)

Moore, Peter K.

2003-01-01

Solving systems of reaction-diffusion equations in three space dimensions can be prohibitively expensive both in terms of storage and CPU time. Herein, I present a new incomplete assembly procedure that is designed to reduce storage requirements. Incomplete assembly is analogous to incomplete factorization in that only a fixed number of nonzero entries are stored per row and a drop tolerance is used to discard small values. The algorithm is incorporated in a finite element method-of-lines code and tested on a set of reaction-diffusion systems. The effect of incomplete assembly on CPU time and storage and on the performance of the temporal integrator DASPK, algebraic solver GMRES and preconditioner ILUT is studied
Development of a utility system for nuclear reaction data file: WinNRDF

International Nuclear Information System (INIS)

Aoyama, Shigeyoshi; Ohbayasi, Yosihide; Masui, Hiroshi; Chiba, Masaki; Kato, Kiyoshi; Ohnishi, Akira

2000-01-01

A utility system, WinNRDF, is developed for charged particle nuclear reaction data of NRDF (Nuclear Reaction Data File) on the Windows interface. By using this system, we can easily search the experimental data of a charged particle nuclear reaction in NRDF than old retrieval systems on the mainframe and also see graphically the experimental data on GUI (Graphical User Interface). We adopted a mechanism of making a new index of keywords to put to practical use of the time dependent properties of the NRDF database. (author)
Coding the Assembly of Polyoxotungstates with a Programmable Reaction System.

Science.gov (United States)

Ruiz de la Oliva, Andreu; Sans, Victor; Miras, Haralampos N; Long, De-Liang; Cronin, Leroy

2017-05-01

Chemical transformations are normally conducted in batch or flow mode, thereby allowing the chemistry to be temporally or spatially controlled, but these approaches are not normally combined dynamically. However, the investigation of the underlying chemistry masked by the self-assembly processes that often occur in one-pot reactions and exploitation of the potential of complex chemical systems requires control in both time and space. Additionally, maintaining the intermediate constituents of a self-assembled system "off equilibrium" and utilizing them dynamically at specific time intervals provide access to building blocks that cannot coexist under one-pot conditions and ultimately to the formation of new clusters. Herein, we implement the concept of a programmable networked reaction system, allowing us to connect discrete "one-pot" reactions that produce the building block{W 11 O 38 } ≡ {W 11 } under different conditions and control, in real time, the assembly of a series of polyoxometalate clusters {W 12 O 42 } ≡ {W 12 }, {W 22 O 74 } ≡ {W 22 } 1a, {W 34 O 116 } ≡ {W 34 } 2a, and {W 36 O 120 } ≡ {W 36 } 3a, using pH and ultraviolet-visible monitoring. The programmable networked reaction system reveals that is possible to assemble a range of different clusters using {W 11 }-based building blocks, demonstrating the relationship between the clusters within the family of iso-polyoxotungstates, with the final structural motif being entirely dependent on the building block libraries generated in each separate reaction space within the network. In total, this approach led to the isolation of five distinct inorganic clusters using a "fixed" set of reagents and using a fully automated sequence code, rather than five entirely different reaction protocols. As such, this approach allows us to discover, record, and implement complex one-pot reaction syntheses in a more general way, increasing the yield and reproducibility and potentially giving access to
Systemic Inflammatory Reaction in Operative Gynecological Care

Directory of Open Access Journals (Sweden)

A. V. Pronoza

2008-01-01

Full Text Available Objective: to evaluate the impact of various methods of anesthesia and treatment on the development of a systemic inflammatory reaction (SIR in gynecological patients. Subjects and methods. The manifestations of SIR were studied in 426 patients who had undergone standard operations on the uterine appendages via traditional laparoscopic access. Ninety-seven women had unoptimized anesthetic maintenance and postoperative preventive antibacterial therapy (Group 1; 95 women had unop-timized anesthetic maintenance and pre- and postoperative massive antibacterial therapy (Group 2; 103 women had optimized anesthetic maintenance and preventive antibacterial therapy (Group 3; 131 women had optimized anesthetic maintenance and massive antibacterial therapy (Group 4. Results. Antibacterial therapy was not found to affect the manifestations of SIR significantly. The optimized anesthetic maintenance that differed from the unoptimized one in higher nociceptive defense had a considerable impact on the manifestation of SIR. Low molecular-weight heparins and preoperative hyperv-olemic hemodilution with hydroxyethyl starch preparations positively affected the study indices. The observed SIR belonged to the second stage of release of the small amount of mediators into systemic circulation. The transition of SIR to the third stage of inflammatory reaction generalization was suggested by changes in other monitored parameters, simultaneously informing about this or that degree of multiple organ dysfunction. Conclusion. Laparoscopic surgical intervention, multicom-ponent preoperative sedation, preventive preoperative analgesia with nonsteroidal anti-inflammatory drugs, prevention of microcirculatory disorders with low molecular-weight heparins, preoperative hypervolemic hemodilution with hydroxyethyl starch, and use of the loading doses of opioids in the period of induction to anesthesia in combination with propofol lower the level of a systemic inflammatory response
NASA Ares I Launch Vehicle Roll and Reaction Control Systems Design Status

Science.gov (United States)

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

2009-01-01

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

KAUST Repository

Di Francesco, M.

2008-12-08

We study the long-time asymptotics of reaction-diffusion-type systems that feature a monotone decaying entropy (Lyapunov, free energy) functional. We consider both bounded domains and confining potentials on the whole space for arbitrary space dimensions. Our aim is to derive quantitative expressions for (or estimates of) the rates of convergence towards an (entropy minimizing) equilibrium state in terms of the constants of diffusion and reaction and with respect to conserved quantities. Our method, the so-called entropy approach, seeks to quantify convergence to equilibrium by using functional inequalities, which relate quantitatively the entropy and its dissipation in time. The entropy approach is well suited to nonlinear problems and known to be quite robust with respect to model variations. It has already been widely applied to scalar diffusion-convection equations, and the main goal of this paper is to study its generalization to systems of partial differential equations that contain diffusion and reaction terms and admit fewer conservation laws than the size of the system. In particular, we successfully apply the entropy approach to general linear systems and to a nonlinear example of a reaction-diffusion-convection system arising in solid-state physics as a paradigm for general nonlinear systems. © 2008 The Royal Society.
Modeling Reaction Control System Effects on Mars Odyssey

National Research Council Canada - National Science Library

Hanna, Jill

2002-01-01

...) simulations to determine rotational motion of the spacecraft. The main objective of this study was to assess the reaction control system models and their effects on the atmospheric flight of Odyssey...
Mutagenicity of heated sugar-casein systems: effect of the Maillard reaction.

Science.gov (United States)

Brands, C M; Alink, G M; van Boekel, M A; Jongen, W M

2000-06-01

The formation of mutagens after the heating of sugar-casein model systems at 120 degrees C was examined by the Ames test, using Salmonella typhimurium strain TA100. Several sugars (glucose, fructose, galactose, tagatose, lactose, and lactulose) were compared in their mutagenicities. Mutagenicity could be fully ascribed to Maillard reaction products and strongly varied with the kind of sugar. The differences in mutagenicity among the sugar-casein systems were caused by a difference in reaction rate and a difference in reaction mechanism. Sugars with a comparable reaction mechanism (glucose and galactose) showed a higher mutagenic activity corresponding with a higher Maillard reactivity. Disaccharides showed no mutagenic activity (lactose) or a lower mutagenic activity (lactulose) than their corresponding monosaccharides. Ketose sugars (fructose and tagatose) showed a remarkably higher mutagenicity compared with their aldose isomers (glucose and galactose), which was due to a difference in reaction mechanism.
Design of the US-CRBRP sodium/water reaction pressure relief system

International Nuclear Information System (INIS)

Kruger, G.B.; Murdock, T.B.; Rodwell, E.; Sane, J.O.

1976-01-01

Protection against intermediate sodium system overpressure from the sodium/water reaction associated with large leaks within the CRBRP Steam Generators is provided by the sodium/water reaction pressure relief system (SWRPRS). This system consists of rupture disks connected to the intermediate sodium piping adjacent to the inlet to the superheater and outlet from the evaporator modules. The rupture discs relieve into piping that leads to reaction produce separator tanks, which in turn are vented to a centrifugal separator and flare stack arranged to burn hydrogen gas exhausting into the atmosphere. Analyses have been conducted using the TRANSWRAP Computer Code to predict the system pressures and flow rates during the large leak event. Experimental tests to be conducted in the large leak test rig (LLTR) will be used to confirm the analysis techniques used in the design
Development of charged particle nuclear reaction data retrieval system on IntelligentPad

International Nuclear Information System (INIS)

Ohbayashi, Yosihide; Masui, Hiroshi; Aoyama, Shigeyoshi; Kato, Kiyoshi; Chiba, Masaki

1999-01-01

An newly designed database retrieval system of charged particle nuclear reaction database system is developed with IntelligentPad architecture. We designed the network-based (server-client) data retrieval system, and a client system constructs on Windows95, 98/NT with IntelligentPad. We set the future aim of our database system toward the 'effective' use of nuclear reaction data: I. 'Re-produce, Re-edit, Re-use', II. 'Circulation, Evolution', III. 'Knowledge discovery'. Thus, further developments are under way. (author)
System Identification for Experimental Study for Polymerization Catalyst Reaction in Fluidized Bed

Directory of Open Access Journals (Sweden)

Ahmmed Saadi Ibrehem

2011-11-01

Full Text Available In this work, system identification method is used to capture the reactor characteristics of production rate of polyethylene (PE based on published experimental data. The identification method is used to measure the percentage effect on the production rate of PE by measuring the effect of input factors of temperature of reaction, hydrogen concentration, and [Al]/[Ti] molar catalyst ratio. Temperature of reaction has big effects equal 52.4 % on the output of the system and 47.6 % on interaction of the system's parameters compare to other two factors. Also, hydrogen concentration has big effect equal 45.66 % on the output of the system and 14.7 % on interaction of the system's parameters. [Al]/[Ti] molar catalyst ratio has big effect on interaction of the system equal 28.6 and 1.94 % on the output of the system but less than the reaction temperature and hydrogen concentration. All these results depend on experiment results and these results are very important in industrial plants. ©2011 BCREC UNDIP. All rights reserved(Received: 13rd May 2011; Revised: 27th July 2011; Accepted: 22th September 2011[How to Cite: Ahmmed S. Ibrehem. (2011. System Identification for Experimental Study for Polymerization Catalyst Reaction in Fluidized Bed. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (2: 137-146. doi:10.9767/bcrec.6.2.874.137-146][How to Link / DOI: http://dx,doi.org/10.9767/bcrec.6.2.874.137-146 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/874 ] | View in
Development of the Automatic Modeling System for Reaction Mechanisms Using REX+JGG

Science.gov (United States)

Takahashi, Takahiro; Kawai, Kohei; Nakai, Hiroyuki; Ema, Yoshinori

The identification of appropriate reaction models is very helpful for developing chemical vapor deposition (CVD) processes. In this study, we developed an automatic modeling system that analyzes experimental data on the cross- sectional shapes of films deposited on substrates with nanometer- or micrometer-sized trenches. The system then identifies a suitable reaction model to describe the film deposition. The inference engine used by the system to model the reaction mechanism was designed using real-coded genetic algorithms (RCGAs): a generation alternation model named "just generation gap" (JGG) and a real-coded crossover named "real-coded ensemble crossover" (REX). We studied the effect of REX+JGG on the system's performance, and found that the system with REX+JGG was the most accurate and reliable at model identification among the algorithms that we studied.
Control of transversal instabilities in reaction-diffusion systems

Science.gov (United States)

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

2018-05-01

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

DEFF Research Database (Denmark)

Yang, Tiankui; MORTEN, REBSDORF; ULRIK, ENGELRUD

2005-01-01

TL IM and Novozym 435 were employed in a batch reaction system. Novozym 435 showed better properties in glycerolysis. The increased temperature and high glycerol/oil ratio had little effect on the yield of MAGs in such a system. The reaction in a packed bed reactor (PBR) gave lower yield of MAGs...
Reaction of long-lived radicals and vitamin C in γ-irradiated mammalian cells and their model system at 295 K. Tunneling reaction in biological system

International Nuclear Information System (INIS)

Matsumoto, Takuro; Miyazaki, Tetsuo; Kosugi, Yoshio; Kumada, Takayuki; Koyama, Sinji; Kodama, Seiji; Watanabe, Masami.

1996-01-01

When golden hamster embryo (GHE) cells or concentrated albumin solution (0.1 kg dm -3 ) that is a model system of cells is irradiated with γ-rays at 295 K, organic radicals produced can be observed by ESR. The organic radicals survive at both 295 K and 310 K for such a long time as 20 hr. The long-lived radicals in GHE cells and the albumin solution react with vitamin C by the rate constants of 0.007 dm 3 mol -1 s -1 and 0.014 dm 3 mol -1 s -1 , respectively. The long-lived radicals in human cells cause gene mutation, which is suppressed by addition of vitamin C. The isotope effect on the rate constant (k) for the reaction of the long-lived radicals and vitamin C has been studied in the albumin solution by use of protonated vitamin C and deuterated vitamin C. The isotope effect (k H /k D ) was more than 20-50 and was interpreted in terms of tunneling reaction. When GHE cells or the aqueous albumin solution (0.1 kg dm -3 ) is irradiated with γ-rays at 295 K, organic radicals produced survive for more than 24 hr at room temperature. Very recently we have found that vitamin C reacts with the long-lived organic radicals in the γ-irradiated albumin solution at high concentration of 0.1 kg dm -3 by the rate constant of 0.014 dm 3 mol -1 s -1 . Since most of reactions in biological systems including the reaction of vitamin C are a transfer of a hydrogen atom or a proton that has a large wave character, it is generally expected that the tunneling reaction may play an important role in biological systems at room temperature. The studies of isotope effects on reactions will give an information on the contribution of tunneling reaction. (J.P.N.)
Experimental studies of water hammer in propellant feed system of reaction control system

Directory of Open Access Journals (Sweden)

Avanish Kumar

2018-03-01

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

Conservation-dissipation structure of chemical reaction systems.

Science.gov (United States)

Yong, Wen-An

2012-12-01

In this Brief Report, we show that balanced chemical reaction systems governed by the law of mass action have an elegant conservation-dissipation structure. From this structure a number of important conclusions can be easily deduced. In particular, with the help of this structure we can rigorously justify the classical partial equilibrium approximation in chemical kinetics.
A Weak Comparison Principle for Reaction-Diffusion Systems

Directory of Open Access Journals (Sweden)

José Valero

2012-01-01

Full Text Available We prove a weak comparison principle for a reaction-diffusion system without uniqueness of solutions. We apply the abstract results to the Lotka-Volterra system with diffusion, a generalized logistic equation, and to a model of fractional-order chemical autocatalysis with decay. Moreover, in the case of the Lotka-Volterra system a weak maximum principle is given, and a suitable estimate in the space of essentially bounded functions L∞ is proved for at least one solution of the problem.
Redox reaction in photochemical and ionizing irradiation systems

International Nuclear Information System (INIS)

Slama-Schwok, A.

1985-09-01

This work presents a basic study of electron transfer reactions which could be involved in appropriate systems for photochemical conversion and storage of solar energy. The aim was to extend the knowledge to new photosensitizers and quenchers and to compare them with the most popular photosensitizers-quenchers system, i.e. a rubidium complex. The photosensitizer studied here is an irridium complex. We studied in this work the air oxidation of bromide to Br 3 - and H 2 O 2 using the irridium complex as the sensitizer. The reducing properties of the reduced irridium complex photosensitizer were studied, using the pulse radiolysis techniques. In conclusion, the oxidation reduction properties of the irridium and its lowest excited state correspond to most of the photosensitizer for electron transfer reactions. The energy temporary present in the charge separation products can be stored using appropriate environment such as polyelectrolytes
Global dynamics of a reaction-diffusion system

Directory of Open Access Journals (Sweden)

Yuncheng You

2011-02-01

Full Text Available In this work the existence of a global attractor for the semiflow of weak solutions of a two-cell Brusselator system is proved. The method of grouping estimation is exploited to deal with the challenge in proving the absorbing property and the asymptotic compactness of this type of coupled reaction-diffusion systems with cubic autocatalytic nonlinearity and linear coupling. It is proved that the Hausdorff dimension and the fractal dimension of the global attractor are finite. Moreover, the existence of an exponential attractor for this solution semiflow is shown.
Large-scale alignments from WMAP and Planck

CERN Document Server

Copi, Craig J.; Schwarz, Dominik J.; Starkman, Glenn D.

2015-01-01

We revisit the alignments of the largest structures observed in the cosmic microwave background (CMB) using the seven and nine-year WMAP and first-year Planck data releases. The observed alignments -- the quadrupole with the octopole and their joint alignment with the direction of our motion with respect to the CMB (the dipole direction) and the geometry of the Solar System (defined by the Ecliptic plane) -- are generally in good agreement with results from the previous WMAP data releases. However, a closer look at full-sky data on the largest scales reveals discrepancies between the earlier WMAP data releases (three to seven-year) and the final nine-year release. There are also discrepancies between all the WMAP data releases and the first-year Planck release. Nevertheless, both the WMAP and Planck data confirm the alignments of the largest observable CMB modes in the Universe. In particular, the p-values for the mutual alignment between the quadrupole and octopole, and the alignment of the plane defined by ...
MINIMARS: An attractive small tandem mirror fusion reactor

International Nuclear Information System (INIS)

Perkins, L.J.; Logan, B.G.; Doggett, J.N.; Devoto, R.S.

1986-01-01

Through the innovative design of a novel end plug scheme employing octopole MHD stabilization, the authors present the conceptual design of ''MINIMARS'', a small commercial fusion reactor based on the tandem mirror principle. The current baseline for MINIMARS has a net electric output of 600 MWe and they have configured the design for short construction times, factory-built modules, inherently safe blanket systems, and multiplexing in station sizes of ≅ 600-2400 MWe. They demonstrate that the compact octopole end cell provides a number of advantages over the more conventional quadrupole (yin-yang) end cell encountered in the MARS tandem mirror reactor study, and enables ignition to be achieved with much shorter central cell lengths. Accordingly, being economic in small sizes, MINIMARS provides an attractive alternative to the more conventional larger conceptual fusion reactors encountered to date, and would contribute significantly to the lowering of utility financial risk in a developing fusion economy
Stability Analysis of a Reaction-Diffusion System Modeling Atherogenesis

KAUST Repository

Ibragimov, Akif; Ritter, Laura; Walton, Jay R.

2010-01-01

This paper presents a linear, asymptotic stability analysis for a reaction-diffusionconvection system modeling atherogenesis, the initiation of atherosclerosis, as an inflammatory instability. Motivated by the disease paradigm articulated by Ross
Computer aided design, analysis and experimental investigation of membrane assisted batch reaction-separation systems

DEFF Research Database (Denmark)

Mitkowski, Piotr Tomasz; Buchaly, Carsten; Kreis, Peter

2009-01-01

Membrane assisted batch reaction operation offers an interesting option for equilibrium limited reaction systems in chemical and biochemical manufacturing by selective removal of one of the products and thereby increasing the product yield. The design of such hybrid systems need to take into acco......Membrane assisted batch reaction operation offers an interesting option for equilibrium limited reaction systems in chemical and biochemical manufacturing by selective removal of one of the products and thereby increasing the product yield. The design of such hybrid systems need to take...... into account the performance of each constituent element and the optimisation of the design must take into consideration their interdependency. In this paper use of a membrane, to assist in the synthesis of propyl-propionate is investigated through the use of a hybrid process design framework, which consists...... and separation functionalities and to design/analyse the hybrid scheme. The generated hybrid scheme has been validated through experiments involving an esterification reaction....
Fabrication of a pen-shaped portable biochemical reaction system based on magnetic bead manipulation

International Nuclear Information System (INIS)

Shikida, Mitsuhiro; Inagaki, Noriyuki; Okochi, Mina; Honda, Hiroyuki; Sato, Kazuo

2011-01-01

A pen-shaped platform that is similar to a mechanical pencil is proposed for producing a portable reaction system. A reaction unit, as the key component in the system, was produced by using a heat shrinkable tube. A mechanical pencil supplied by Mitsubishi Pencil Co. Ltd was used as the pen-shaped platform for driving the reaction cylinder. It was actuated using an inchworm motion. We confirmed that the magnetic beads were successfully manipulated in the droplet in the cylinder-shaped reaction units. (technical note)
Coupled enzyme reactions performed in heterogeneous reaction media: experiments and modeling for glucose oxidase and horseradish peroxidase in a PEG/citrate aqueous two-phase system.

Science.gov (United States)

Aumiller, William M; Davis, Bradley W; Hashemian, Negar; Maranas, Costas; Armaou, Antonios; Keating, Christine D

2014-03-06

The intracellular environment in which biological reactions occur is crowded with macromolecules and subdivided into microenvironments that differ in both physical properties and chemical composition. The work described here combines experimental and computational model systems to help understand the consequences of this heterogeneous reaction media on the outcome of coupled enzyme reactions. Our experimental model system for solution heterogeneity is a biphasic polyethylene glycol (PEG)/sodium citrate aqueous mixture that provides coexisting PEG-rich and citrate-rich phases. Reaction kinetics for the coupled enzyme reaction between glucose oxidase (GOX) and horseradish peroxidase (HRP) were measured in the PEG/citrate aqueous two-phase system (ATPS). Enzyme kinetics differed between the two phases, particularly for the HRP. Both enzymes, as well as the substrates glucose and H2O2, partitioned to the citrate-rich phase; however, the Amplex Red substrate necessary to complete the sequential reaction partitioned strongly to the PEG-rich phase. Reactions in ATPS were quantitatively described by a mathematical model that incorporated measured partitioning and kinetic parameters. The model was then extended to new reaction conditions, i.e., higher enzyme concentration. Both experimental and computational results suggest mass transfer across the interface is vital to maintain the observed rate of product formation, which may be a means of metabolic regulation in vivo. Although outcomes for a specific system will depend on the particulars of the enzyme reactions and the microenvironments, this work demonstrates how coupled enzymatic reactions in complex, heterogeneous media can be understood in terms of a mathematical model.
Development of utility system of charged particle Nuclear Reaction Data on Unified Interface

International Nuclear Information System (INIS)

Aoyama, Shigeyoshi; Ohbayashi, Yosihide; Kato, Kiyoshi; Masui, Hiroshi; Ohnishi, Akira; Chiba, Masaki

1999-01-01

We have developed a utility system, WinNRDF, for a nuclear charged particle reaction data of NRDF (Nuclear Reaction Data File) on a unified interface of Windows95, 98/NT. By using the system, we can easily search the experimental data of a charged particle reaction in NRDF and also see the graphic data on GUI (Graphical User Interface). Furthermore, we develop a mechanism of making a new index of keywords in order to include the time developing character of the NRDF database. (author)
Pneumatic tool torque reaction: reaction forces, displacement, muscle activity and discomfort in the hand-arm system.

Science.gov (United States)

Kihlberg, S; Kjellberg, A; Lindbeck, L

1993-06-01

Reaction forces, hand-arm displacement, muscle activity and discomfort ratings were studied during the securing of threaded fasteners with three angle nutrunners with different shut-off mechanisms, but with the same spindle torque (72-74 Nm). The three tools were tested according to the method specified in ISO 6544. One of the tools had an almost instantaneous shut-off. Another had a more slowly declining torque curve. For the third tool the maximum torque was maintained for a while before shut-off. Twelve male subjects participated in the study. A force platform measured the reaction force between the subject and the floor. The option of the hand-arm system and the shoulder was measured with an optoelectronic measuring system. The muscle activity (EMG) in six muscles in the arm and shoulder was measured with surface electrodes. Significant differences in the arm movements and ground reaction forces were found between the three tools. The smallest values were found with the fast shut-off tool while the delayed shut-off tool caused the largest values. The EMG measures gave inconsistent response patterns. Discomfort ratings were highly correlated with the time for which the tool torque exceeded 90% of peak preset torque, but the time for which the tool torque exceeded 90% of peak calculated by the method specified in ISO 6544. Nutrunners with a shut-off mechanism that causes a slowly decreasing torque or a torque that is maintained for a while before shut-off should be avoided. If no substitutes are available, then a torque reaction bar should be mounted on the tool.
Reaction factoring and bipartite update graphs accelerate the Gillespie Algorithm for large-scale biochemical systems.

Science.gov (United States)

Indurkhya, Sagar; Beal, Jacob

2010-01-06

ODE simulations of chemical systems perform poorly when some of the species have extremely low concentrations. Stochastic simulation methods, which can handle this case, have been impractical for large systems due to computational complexity. We observe, however, that when modeling complex biological systems: (1) a small number of reactions tend to occur a disproportionately large percentage of the time, and (2) a small number of species tend to participate in a disproportionately large percentage of reactions. We exploit these properties in LOLCAT Method, a new implementation of the Gillespie Algorithm. First, factoring reaction propensities allows many propensities dependent on a single species to be updated in a single operation. Second, representing dependencies between reactions with a bipartite graph of reactions and species requires only storage for reactions, rather than the required for a graph that includes only reactions. Together, these improvements allow our implementation of LOLCAT Method to execute orders of magnitude faster than currently existing Gillespie Algorithm variants when simulating several yeast MAPK cascade models.
Invariant boxes and stability of some systems from biomathematics and chemical reactions

International Nuclear Information System (INIS)

Pavel, N.H.

1984-08-01

A general theorem on the flow-invariance of a time-dependent rectangular box with respect to a differential system is first recalled [''Analysis of some non-linear problems'' in Banach Spaces and Applications, Univ. of Iasi (Romania) (1982)]. Then a theorem applicable to the study of some differential systems from biomathematics and chemical reactions is given and proved. The theorem can be applied to enzymatic reactions, the chemical mechanism in the Belousov reaction, and the kinetic system for the chemical scheme of Hanusse of two processes with three intermediate species [in Pavel, N.H., Differential Equations, Flow-invariance and Applications, Pitman Publishing, Ltd., London (to appear)]. Next, the matrices A for which the corresponding linear system x'=Ax is component-wise positive asymptotically stable are characterized. In the Appendix a partial answer to an open problem regarding the preservation of both continuity and dissipativity in the extension of functions to a Banach space is given
Formal modeling of a system of chemical reactions under uncertainty.

Science.gov (United States)

Ghosh, Krishnendu; Schlipf, John

2014-10-01

We describe a novel formalism representing a system of chemical reactions, with imprecise rates of reactions and concentrations of chemicals, and describe a model reduction method, pruning, based on the chemical properties. We present two algorithms, midpoint approximation and interval approximation, for construction of efficient model abstractions with uncertainty in data. We evaluate computational feasibility by posing queries in computation tree logic (CTL) on a prototype of extracellular-signal-regulated kinase (ERK) pathway.
Is the low-l microwave background cosmic?

Science.gov (United States)

Schwarz, Dominik J; Starkman, Glenn D; Huterer, Dragan; Copi, Craig J

2004-11-26

The large-angle (low-l) correlations of the cosmic microwave background exhibit several statistically significant anomalies compared to the standard inflationary cosmology. We show that the quadrupole plane and the three octopole planes are far more aligned than previously thought (99.9% C.L.). Three of these planes are orthogonal to the ecliptic at 99.1% C.L., and the normals to these planes are aligned at 99.6% C.L. with the direction of the cosmological dipole and with the equinoxes. The remaining octopole plane is orthogonal to the supergalactic plane at 99.6% C.L.
Bee and bee products allergy in Turkish beekeepers: determination of risk factors for systemic reactions.

Science.gov (United States)

Celikel, S; Karakaya, G; Yurtsever, N; Sorkun, K; Kalyoncu, A F

2006-01-01

The prevalence of allergic reactions due to bee stings in beekeepers varies in different regions of the world. The aim of this study was to evaluate the characteristics of sting reactions and the risk factors for developing systemic reactions in Turkish beekeepers. A self-administered questionnaire was distributed to 1250 beekeepers to be completed in seven different cities of Turkey. A total of 494 (39.6 %) questionnaires were returned. There were 444 subjects (89.9 %) with a history of sting exposure in the previous 12 months. Systemic reactions were present in 29 subjects (6.5 %) and nine (2 %) reactions were anaphylactic. Fifty-five percent of beekeepers reported more than 100 bee stings in the previous year. When systemic reactions were controlled by age and duration of beekeeping in a logistic regression model, seasonal rhinitis (OR: 4.4, 95 % CI: 1.2-11.5), perennial rhinitis (OR: 4.6, 95 % CI: 1.2-18.2), food allergy (OR:7.0, 95 % CI: 2.0-25.0), physician-diagnosed asthma (OR: 8.0, 95 % CI: 2.5-25.6), having an atopic disease of any type (OR: 3.3, 95 % CI: 1.2-8.7) and having two or more atopic diseases (OR: 10.9, 95 % CI: 3.5-33.8) were significantly associated with systemic reactions due to bee sting in the previous 12 months. The incidence of systemic reactions in Turkish beekeepers is low, which might be due to the protective effect of a high frequency of bee stings. The risk of systemic reactions increases approximately three-fold when one atopic disease is present and eleven-fold when two or more concurrent atopic diseases are present with respect to no atopic disease.
Dichotomous-noise-induced pattern formation in a reaction-diffusion system

Science.gov (United States)

Das, Debojyoti; Ray, Deb Shankar

2013-06-01

We consider a generic reaction-diffusion system in which one of the parameters is subjected to dichotomous noise by controlling the flow of one of the reacting species in a continuous-flow-stirred-tank reactor (CSTR) -membrane reactor. The linear stability analysis in an extended phase space is carried out by invoking Furutzu-Novikov procedure for exponentially correlated multiplicative noise to derive the instability condition in the plane of the noise parameters (correlation time and strength of the noise). We demonstrate that depending on the correlation time an optimal strength of noise governs the self-organization. Our theoretical analysis is corroborated by numerical simulations on pattern formation in a chlorine-dioxide-iodine-malonic acid reaction-diffusion system.
ON THE REACTIONS IN ILMENITE, ALUMINUM AND GRAPHITE SYSTEM

Directory of Open Access Journals (Sweden)

R. Khoshhal

2016-03-01

Full Text Available Al2O3/TiC composites are used as cutting tools for machining gray cast iron and steels. The addition of iron improves the toughness of Al2O3/TiC composites. Ilmenite, aluminum and graphite can be used to produce in-situ Al2O3/TiC–Fe composites. However, the formation mechanism and reaction sequences of this system are not clear enough. Therefore, the present research is designed to determine the reactions mechanism of the first step of reactions that may be occurred between raw materials. In this research, pure ilmenite was synthesized to eliminate the effects of impurities available in the natural ilmenite in the system. The milled and pressed samples, prepared from the synthesized ilmenite, aluminum and graphite mixture with a molar ratio of 1:2:1, were heat treated at 720°C for 48h. In addition, two samples one containing ilmenite and aluminum with a molar ratio of 1:2 and ilmenite and graphite with a molar ratio of 1:1 were heat treated at 720°C for 48h. The final products were analyzed with XRD. It was found that at 720°C, aluminum reacts with FeTiO3, forming Fe, TiO2 and Al2O3. Since the aluminum content used in the mixture was more than the stoichiometry for reaction of ilmenite and aluminum, some unreacted aluminum remains. Therefore, the residual aluminum reacts with the reduced Fe to form Fe2Al5.
Thermo effect of chemical reaction in irreversible electrochemical systems

International Nuclear Information System (INIS)

Tran Vinh Quy; Nguyen Tang

1989-01-01

From first law of thermodynamics the expressions of statistical calculation of 'Fundamental' and 'Thermo-chemical' thermal effects are obtained. Besides, method of calculation of thermal effect of chemical reactions in non-equilibrium electro-chemical systems is accurately discussed. (author). 7 refs

Concentration fluctuations in non-isothermal reaction-diffusion systems. II. The nonlinear case

NARCIS (Netherlands)

Bedeaux, D.; Ortiz de Zárate, J.M.; Pagonabarraga, I.; Sengers, J.V.; Kjelstrup, S.

2011-01-01

In this paper, we consider a simple reaction-diffusion system, namely, a binary fluid mixture with an association-dissociation reaction between two species. We study fluctuations at hydrodynamic spatiotemporal scales when this mixture is driven out of equilibrium by the presence of a temperature
Photon- and pion-induced reactions in the few body systems

International Nuclear Information System (INIS)

Laget, J.M.

1985-05-01

The study of the interplay of the degrees of freedom of the many nuclear system and the internal degrees of freedom of its constituents is reviewed. First nucleon-nucleon interaction mechanisms are recalled in relation to the interaction range. It appears that pion and photon induced reactions should provide two complementary ways to disentangle these various mechanisms. Most of pion and photon induced reactions, performed until now, can be understood in terms of nucleons, pions and deltas. But after a short description of the method of analysis of the reactions it is shown that this agreement is achieved at the price of the adjustment of two parameters (the πNN form factor and the rho-nucleon coupling contant) which may simulate more subtle short range effects. Then the relevance of the analysis of the same reactions in terms of quark degrees of freedom is discussed briefly
Reaction factoring and bipartite update graphs accelerate the Gillespie Algorithm for large-scale biochemical systems.

Directory of Open Access Journals (Sweden)

Sagar Indurkhya

Full Text Available ODE simulations of chemical systems perform poorly when some of the species have extremely low concentrations. Stochastic simulation methods, which can handle this case, have been impractical for large systems due to computational complexity. We observe, however, that when modeling complex biological systems: (1 a small number of reactions tend to occur a disproportionately large percentage of the time, and (2 a small number of species tend to participate in a disproportionately large percentage of reactions. We exploit these properties in LOLCAT Method, a new implementation of the Gillespie Algorithm. First, factoring reaction propensities allows many propensities dependent on a single species to be updated in a single operation. Second, representing dependencies between reactions with a bipartite graph of reactions and species requires only storage for reactions, rather than the required for a graph that includes only reactions. Together, these improvements allow our implementation of LOLCAT Method to execute orders of magnitude faster than currently existing Gillespie Algorithm variants when simulating several yeast MAPK cascade models.
Reaction Factoring and Bipartite Update Graphs Accelerate the Gillespie Algorithm for Large-Scale Biochemical Systems

Science.gov (United States)

Indurkhya, Sagar; Beal, Jacob

2010-01-01

ODE simulations of chemical systems perform poorly when some of the species have extremely low concentrations. Stochastic simulation methods, which can handle this case, have been impractical for large systems due to computational complexity. We observe, however, that when modeling complex biological systems: (1) a small number of reactions tend to occur a disproportionately large percentage of the time, and (2) a small number of species tend to participate in a disproportionately large percentage of reactions. We exploit these properties in LOLCAT Method, a new implementation of the Gillespie Algorithm. First, factoring reaction propensities allows many propensities dependent on a single species to be updated in a single operation. Second, representing dependencies between reactions with a bipartite graph of reactions and species requires only storage for reactions, rather than the required for a graph that includes only reactions. Together, these improvements allow our implementation of LOLCAT Method to execute orders of magnitude faster than currently existing Gillespie Algorithm variants when simulating several yeast MAPK cascade models. PMID:20066048
Experimental study of peripheral reactions in the 16O +63,65 Cu systems

International Nuclear Information System (INIS)

Razeto, G.R.

1987-01-01

In this work elastic scattering and ( 16 O,N) ( 16 O,C) transfer reaction data are presented for the 16 O + 63,65 Cu systems at the incident energy range of 40 to 64MeV. The data was analized with the Optical Model, and the total reaction cross section was compared with the fusion cross section data available from a previus work. Furthermore correlation was made between transfer processes with the different optical potential parameters for these systems. The Frahnand Venter fenomelogical modelo and DWBA calculations were employed for analysis of the transfer reaction data. For the 16 O + 63 Cu system beside the threshold anomaly, an atypical angles (θ cm > 140 0 ). The Regge poles ressonances formalism was used to explain it. (author) [pt
Development of a utility system for charged particle nuclear reaction data by using intelligentPad

International Nuclear Information System (INIS)

Aoyama, Shigeyoshi; Ohbayashi, Yoshihide; Masui, Hiroshi; Kato, Kiyoshi; Chiba, Masaki

2000-01-01

We have developed a utility system, WinNRDF2, for a nuclear charged particle reaction data of NRDF (Nuclear Reaction Data File) on the IntelligentPad architecture. By using the system, we can search the experimental data of a charged particle reaction of NRDF. Furthermore, we also see the experimental data by using graphic pads which was made through the CONTIP project. (author)
Distribution in flowing reaction-diffusion systems

KAUST Repository

Kamimura, Atsushi; Herrmann, Hans J.; Ito, Nobuyasu

2009-01-01

A power-law distribution is found in the density profile of reacting systems A+B→C+D and 2A→2C under a flow in two and three dimensions. Different densities of reactants A and B are fixed at both ends. For the reaction A+B, the concentration of reactants asymptotically decay in space as x-1/2 and x-3/4 in two dimensions and three dimensions, respectively. For 2A, it decays as log (x) /x in two dimensions. The decay of A+B is explained considering the effect of segregation of reactants in the isotropic case. The decay for 2A is explained by the marginal behavior of two-dimensional diffusion. A logarithmic divergence of the diffusion constant with system size is found in two dimensions. © 2009 The American Physical Society.
Distribution in flowing reaction-diffusion systems

KAUST Repository

Kamimura, Atsushi

2009-12-28

A power-law distribution is found in the density profile of reacting systems A+B→C+D and 2A→2C under a flow in two and three dimensions. Different densities of reactants A and B are fixed at both ends. For the reaction A+B, the concentration of reactants asymptotically decay in space as x-1/2 and x-3/4 in two dimensions and three dimensions, respectively. For 2A, it decays as log (x) /x in two dimensions. The decay of A+B is explained considering the effect of segregation of reactants in the isotropic case. The decay for 2A is explained by the marginal behavior of two-dimensional diffusion. A logarithmic divergence of the diffusion constant with system size is found in two dimensions. © 2009 The American Physical Society.
Fragmentation and reactivity of energy-selected ferrocenium ions

International Nuclear Information System (INIS)

Mestdagh, H.; Dutuit, O.; Heninger, M.; Thissen, R.; Alcaraz, C.

2002-01-01

In this study, results concerning the discussion of state-selected ferrocenium ions (c-C 5 H 5 ) 2 Fe + commonly called Cp 2 Fe + , as well as their reactions with methanol and ethanol are presented. Parent ions Cp 2 Fe + were produced by vacuumultraviolett (VUV) photoionization of neutral ferrocene using synchrotron radiation, and selected in internal energy by threshold photoelectron-photoion coincidences. The apparatus is divided into three differentially pumped regions: the source, the reaction and the detection zones. In source, state-selected parent ions are formed and can be selected in mass by a first quadrupole filter. State-selected ions are then injected in the second zone which is a RF octopole ion guide where reaction product ions are mass analyzed by a second quadrupole filter and detected by microchannelplates. In addition, the long flight time in the octopoles (several hundreds of microseconds) allows studying long-lived metastable ions. Total mass spectra were recorded at different photon energies, in addition to the main CpFe + and Fe + fragments, several minor fragments were detected such as C 10 H 10 + which reflects the formation of a C-C bond between the two Cp ligands. Losses of CH 3 , C 2 H 2 and C-4H 4 also indicate that important structure rearrangements take place before cleavage. The appearance energies of each mass-selected fragment ion were measured by recording fragment ion yields as a function of photon energy. Surprisingly, all fragments were found to have the same energy onset, i.e. 13.2 eV photon energy, except for C 3 H 3 Fe + (m/z 95). For Fe + ions, a sharp increase was observed at 17 eV, above the thermochemical onset of Fe + + 2 Cp. The 13.2 eV appearance energy of Fe + is thus assigned to the formation of Fe - + C 10 H 10 . The reactivity of ferrocenium ion with methanol and ethanol was investigated as a function of photon energy. While no reaction occurs at lower photon energies, several reaction products appear at 13.0 e
Central nervous system reactions to cervical myelography

International Nuclear Information System (INIS)

Vestergaard, A.; Dons, K.; Eskesen, V.; Kruse-Larsen, C.; Blatt Lyon, B.; Arlien Soeborg, P.; Jensen, N.O.; Praestholm, J.

1991-01-01

In a double blind prospective study of side effects to cervical myelography 38 patients were evaluated with neurologic examination, electroencephalography (EEG), brainstem evoked response (BER), somatosensory evoked responses (SSER), and continuous reaction times prior to and at 6 h and 24 h after myelography with either metrizamide or iohexol. A difference in the incidence of side effects (for example headache, dizziness, nausea, and neck pain) to the two different contrast media indicated that the inconveniences related to myelography were not only due to the spinal puncture. A contrast medium effect on the central nervous system varying from one agent to another was present. A high frequency of EEG deteriorations among patients with adverse clinical reactions and on only discrete affection upon BER indicated the reaction to be located to the cerebral cortex. Weakened tendon reflexes and reduced strength in the upper extremities were probably caused by blockade in the motor roots as SSER were normal indicating no affection of the sensory pathways. This hypothesis is in agreement with the fact the patients were in the prone position in the first phase of the investigation causing the highest concentration of contrast medium around the motor roots and the anterior part of the spinal cord. Difference in metabolic effect may explain differences in side effects of metrizamide and iohexol. (orig.)
Central nervous system reactions to cervical myelography

Energy Technology Data Exchange (ETDEWEB)

Vestergaard, A; Dons, K; Eskesen, V; Kruse-Larsen, C; Blatt Lyon, B; Arlien Soeborg, P; Jensen, N O; Praestholm, J [Hvidovre Hospital (Denmark). Depts. of Diagnostic Radiology, Neurosurgery, Neurology, and Clinical Neurophysiology

1991-09-01

In a double blind prospective study of side effects to cervical myelography 38 patients were evaluated with neurologic examination, electroencephalography (EEG), brainstem evoked response (BER), somatosensory evoked responses (SSER), and continuous reaction times prior to and at 6 h and 24 h after myelography with either metrizamide or iohexol. A difference in the incidence of side effects (for example headache, dizziness, nausea, and neck pain) to the two different contrast media indicated that the inconveniences related to myelography were not only due to the spinal puncture. A contrast medium effect on the central nervous system varying from one agent to another was present. A high frequency of EEG deteriorations among patients with adverse clinical reactions and on only discrete affection upon BER indicated the reaction to be located to the cerebral cortex. Weakened tendon reflexes and reduced strength in the upper extremities were probably caused by blockade in the motor roots as SSER were normal indicating no affection of the sensory pathways. This hypothesis is in agreement with the fact the patients were in the prone position in the first phase of the investigation causing the highest concentration of contrast medium around the motor roots and the anterior part of the spinal cord. Difference in metabolic effect may explain differences in side effects of metrizamide and iohexol. (orig.).
Turing Patterns in a Reaction-Diffusion System

International Nuclear Information System (INIS)

Wu Yanning; Wang Pingjian; Hou Chunju; Liu Changsong; Zhu Zhengang

2006-01-01

We have further investigated Turing patterns in a reaction-diffusion system by theoretical analysis and numerical simulations. Simple Turing patterns and complex superlattice structures are observed. We find that the shape and type of Turing patterns depend on dynamical parameters and external periodic forcing, and is independent of effective diffusivity rate σ in the Lengyel-Epstein model. Our numerical results provide additional insight into understanding the mechanism of development of Turing patterns and predicting new pattern formations.
Nonequilibrium Contribution to the Rate of Reaction. III. Isothermal Multicomponent Systems

Science.gov (United States)

Shizgal, B.; Karplus, M.

1970-10-01

The nonequilibrium contribution to the reaction rate of an isothermal multicomponent system is obtained by solution of the appropriate Chapman-Enskog equation; the system is composed of reactive species in contact with a heat bath of inert atoms M.
Heterogeneous-catalytic redox reactions in nitrate - formate systems

International Nuclear Information System (INIS)

Ananiev, A.V.; Shilov, V.P.; Tananaev, I.G.; Brossard, Ph.; Broudic, J.Ch.

2000-01-01

It was found that an intensive destruction of various organic and mineral substances - usual components of aqueous waste solutions (oxalic acid, complexones, urea, hydrazine, ammonium nitrate, etc.) takes place under the conditions of catalytic denitration. Kinetics and mechanisms of urea and ammonium nitrate decomposition in the system HNO 3 - HCOOH - Pt/SiO 2 are comprehensively investigated. The behaviour of uranium, neptunium and plutonium under the conditions of catalytic denitration is studied. It is shown, that under the certain conditions the formic acid is an effective reducer of the uranium (VI), neptunium (VI, V) and plutonium (VI, IV) ions. Kinetics of heterogeneous-catalytic red-ox reactions of uranium (VI), neptunium (VI, V) and plutonium (VI, IV) with formic acid are investigated. The mechanisms of the appropriate reactions are evaluated. (authors)
Modelling biochemical reaction systems by stochastic differential equations with reflection.

Science.gov (United States)

Niu, Yuanling; Burrage, Kevin; Chen, Luonan

2016-05-07

In this paper, we gave a new framework for modelling and simulating biochemical reaction systems by stochastic differential equations with reflection not in a heuristic way but in a mathematical way. The model is computationally efficient compared with the discrete-state Markov chain approach, and it ensures that both analytic and numerical solutions remain in a biologically plausible region. Specifically, our model mathematically ensures that species numbers lie in the domain D, which is a physical constraint for biochemical reactions, in contrast to the previous models. The domain D is actually obtained according to the structure of the corresponding chemical Langevin equations, i.e., the boundary is inherent in the biochemical reaction system. A variant of projection method was employed to solve the reflected stochastic differential equation model, and it includes three simple steps, i.e., Euler-Maruyama method was applied to the equations first, and then check whether or not the point lies within the domain D, and if not perform an orthogonal projection. It is found that the projection onto the closure D¯ is the solution to a convex quadratic programming problem. Thus, existing methods for the convex quadratic programming problem can be employed for the orthogonal projection map. Numerical tests on several important problems in biological systems confirmed the efficiency and accuracy of this approach. Copyright © 2016 Elsevier Ltd. All rights reserved.
Open quantum system approach to the modeling of spin recombination reactions.

Science.gov (United States)

Tiersch, M; Steiner, U E; Popescu, S; Briegel, H J

2012-04-26

In theories of spin-dependent radical pair reactions, the time evolution of the radical pair, including the effect of the chemical kinetics, is described by a master equation in the Liouville formalism. For the description of the chemical kinetics, a number of possible reaction operators have been formulated in the literature. In this work, we present a framework that allows for a unified description of the various proposed mechanisms and the forms of reaction operators for the spin-selective recombination processes. On the basis of the concept that master equations can be derived from a microscopic description of the spin system interacting with external degrees of freedom, it is possible to gain insight into the underlying microscopic processes and develop a systematic approach toward determining the specific form of the reaction operator in concrete scenarios.
Exact substitute processes for diffusion-reaction systems with local complete exclusion rules

International Nuclear Information System (INIS)

Schulz, Michael; Reineker, Peter

2005-01-01

Lattice systems with one species diffusion-reaction processes under local complete exclusion rules are studied analytically starting from the usual master equations with discrete variables and their corresponding representation in a Fock space. On this basis, a formulation of the transition probability as a Grassmann path integral is derived in a straightforward manner. It will be demonstrated that this Grassmann path integral is equivalent to a set of Ito stochastic differential equations. Averages of arbitrary variables and correlation functions of the underlying diffusion-reaction system can be expressed as weighted averages over all solutions of the system of stochastic differential equations. Furthermore, these differential equations are equivalent to a Fokker-Planck equation describing the probability distribution of the actual Ito solutions. This probability distribution depends on continuous variables in contrast to the original master equation, and their stochastic dynamics may be interpreted as a substitute process which is completely equivalent to the original lattice dynamics. Especially, averages and correlation functions of the continuous variables are connected to the corresponding lattice quantities by simple relations. Although the substitute process for diffusion-reaction systems with exclusion rules has some similarities to the well-known substitute process for the same system without exclusion rules, there exists a set of remarkable differences. The given approach is not only valid for the discussed single-species processes. We give sufficient arguments to show that arbitrary combinations of unimolecular and bimolecular lattice reactions under complete local exclusions may be described in terms of our approach
Turing instability in reaction-diffusion systems with nonlinear diffusion

Energy Technology Data Exchange (ETDEWEB)

Zemskov, E. P., E-mail: zemskov@ccas.ru [Russian Academy of Sciences, Dorodnicyn Computing Center (Russian Federation)

2013-10-15

The Turing instability is studied in two-component reaction-diffusion systems with nonlinear diffusion terms, and the regions in parametric space where Turing patterns can form are determined. The boundaries between super- and subcritical bifurcations are found. Calculations are performed for one-dimensional brusselator and oregonator models.
Optimization of Maillard Reaction in Model System of Glucosamine and Cysteine Using Response Surface Methodology.

Science.gov (United States)

Arachchi, Shanika Jeewantha Thewarapperuma; Kim, Ye-Joo; Kim, Dae-Wook; Oh, Sang-Chul; Lee, Yang-Bong

2017-03-01

Sulfur-containing amino acids play important roles in good flavor generation in Maillard reaction of non-enzymatic browning, so aqueous model systems of glucosamine and cysteine were studied to investigate the effects of reaction temperature, initial pH, reaction time, and concentration ratio of glucosamine and cysteine. Response surface methodology was applied to optimize the independent reaction parameters of cysteine and glucosamine in Maillard reaction. Box-Behnken factorial design was used with 30 runs of 16 factorial levels, 8 axial levels and 6 central levels. The degree of Maillard reaction was determined by reading absorption at 425 nm in a spectrophotometer and Hunter's L, a, and b values. ΔE was consequently set as the fifth response factor. In the statistical analyses, determination coefficients (R 2 ) for their absorbance, Hunter's L, a, b values, and ΔE were 0.94, 0.79, 0.73, 0.96, and 0.79, respectively, showing that the absorbance and Hunter's b value were good dependent variables for this model system. The optimum processing parameters were determined to yield glucosamine-cysteine Maillard reaction product with higher absorbance and higher colour change. The optimum estimated absorbance was achieved at the condition of initial pH 8.0, 111°C reaction temperature, 2.47 h reaction time, and 1.30 concentration ratio. The optimum condition for colour change measured by Hunter's b value was 2.41 h reaction time, 114°C reaction temperature, initial pH 8.3, and 1.26 concentration ratio. These results can provide the basic information for Maillard reaction of aqueous model system between glucosamine and cysteine.
A discrete model to study reaction-diffusion-mechanics systems.

Science.gov (United States)

Weise, Louis D; Nash, Martyn P; Panfilov, Alexander V

2011-01-01

This article introduces a discrete reaction-diffusion-mechanics (dRDM) model to study the effects of deformation on reaction-diffusion (RD) processes. The dRDM framework employs a FitzHugh-Nagumo type RD model coupled to a mass-lattice model, that undergoes finite deformations. The dRDM model describes a material whose elastic properties are described by a generalized Hooke's law for finite deformations (Seth material). Numerically, the dRDM approach combines a finite difference approach for the RD equations with a Verlet integration scheme for the equations of the mass-lattice system. Using this framework results were reproduced on self-organized pacemaking activity that have been previously found with a continuous RD mechanics model. Mechanisms that determine the period of pacemakers and its dependency on the medium size are identified. Finally it is shown how the drift direction of pacemakers in RDM systems is related to the spatial distribution of deformation and curvature effects.

A discrete model to study reaction-diffusion-mechanics systems.

Directory of Open Access Journals (Sweden)

Louis D Weise

Full Text Available This article introduces a discrete reaction-diffusion-mechanics (dRDM model to study the effects of deformation on reaction-diffusion (RD processes. The dRDM framework employs a FitzHugh-Nagumo type RD model coupled to a mass-lattice model, that undergoes finite deformations. The dRDM model describes a material whose elastic properties are described by a generalized Hooke's law for finite deformations (Seth material. Numerically, the dRDM approach combines a finite difference approach for the RD equations with a Verlet integration scheme for the equations of the mass-lattice system. Using this framework results were reproduced on self-organized pacemaking activity that have been previously found with a continuous RD mechanics model. Mechanisms that determine the period of pacemakers and its dependency on the medium size are identified. Finally it is shown how the drift direction of pacemakers in RDM systems is related to the spatial distribution of deformation and curvature effects.
Illustration of reaction mechanism in polyatomic systems via computer movies

International Nuclear Information System (INIS)

Raff, L.M.

1974-01-01

The CD 4 + T* systems is suited for classroom illustration of reaction dynamics. Questions about the system can be illustrated by reducing selected many-body trajectories to a 16 mm color movie that represents the six-body motion in projected coordinates. Such a movie has been produced for this system. The production procedure used is reported, and a detailed description of the contents of the movie is given. (U.S.)
Brake reactions of distracted drivers to pedestrian Forward Collision Warning systems.

Science.gov (United States)

Lubbe, Nils

2017-06-01

Forward Collision Warning (FCW) can be effective in directing driver attention towards a conflict and thereby aid in preventing or mitigating collisions. FCW systems aiming at pedestrian protection have been introduced onto the market, yet an assessment of their safety benefits depends on the accurate modeling of driver reactions when the system is activated. This study contributes by quantifying brake reaction time and brake behavior (deceleration levels and jerk) to compare the effectiveness of an audio-visual warning only, an added haptic brake pulse warning, and an added Head-Up Display in reducing the frequency of collisions with pedestrians. Further, this study provides a detailed data set suited for the design of assessment methods for car-to-pedestrian FCW systems. Brake response characteristics were measured for heavily distracted drivers who were subjected to a single FCW event in a high-fidelity driving simulator. The drivers maintained a self-regulated speed of 30km/h in an urban area, with gaze direction diverted from the forward roadway by a secondary task. Collision rates and brake reaction times differed significantly across FCW settings. Brake pulse warnings resulted in the lowest number of collisions and the shortest brake reaction times (mean 0.8s, SD 0.29s). Brake jerk and deceleration were independent of warning type. Ninety percent of drivers exceeded a maximum deceleration of 3.6m/s 2 and a jerk of 5.3m/s 3 . Brake pulse warning was the most effective FCW interface for preventing collisions. In addition, this study presents the data required for driver modeling for car-to-pedestrian FCW similar to Euro NCAP's 2015 car-to-car FCW assessment. Practical applications: Vehicle manufacturers should consider the introduction of brake pulse warnings to their FCW systems. Euro NCAP could introduce an assessment that quantifies the safety benefits of pedestrian FCW systems and thereby aid the proliferation of effective systems. Copyright © 2017
Cross-diffusional effect in a telegraph reaction diffusion Lotka-Volterra two competitive system

International Nuclear Information System (INIS)

Abdusalam, H.A; Fahmy, E.S.

2003-01-01

It is known now that, telegraph equation is more suitable than ordinary diffusion equation in modelling reaction diffusion in several branches of sciences. Telegraph reaction diffusion Lotka-Volterra two competitive system is considered. We observed that this system can give rise to diffusive instability only in the presence of cross-diffusion. Local and global stability analysis in the cross-diffusional effect are studied by considering suitable Lyapunov functional
Web-Based Search and Plot System for Nuclear Reaction Data

International Nuclear Information System (INIS)

Otuka, N.; Nakagawa, T.; Fukahori, T.; Katakura, J.; Aikawa, M.; Suda, T.; Naito, K.; Korennov, S.; Arai, K.; Noto, H.; Ohnishi, A.; Kato, K.

2005-01-01

A web-based search and plot system for nuclear reaction data has been developed, covering experimental data in EXFOR format and evaluated data in ENDF format. The system is implemented for Linux OS, with Perl and MySQL used for CGI scripts and the database manager, respectively. Two prototypes for experimental and evaluated data are presented
Rethinking pattern formation in reaction-diffusion systems

Science.gov (United States)

Halatek, J.; Frey, E.

2018-05-01

The present theoretical framework for the analysis of pattern formation in complex systems is mostly limited to the vicinity of fixed (global) equilibria. Here we present a new theoretical approach to characterize dynamical states arbitrarily far from (global) equilibrium. We show that reaction-diffusion systems that are driven by locally mass-conserving interactions can be understood in terms of local equilibria of diffusively coupled compartments. Diffusive coupling generically induces lateral redistribution of the globally conserved quantities, and the variable local amounts of these quantities determine the local equilibria in each compartment. We find that, even far from global equilibrium, the system is well characterized by its moving local equilibria. We apply this framework to in vitro Min protein pattern formation, a paradigmatic model for biological pattern formation. Within our framework we can predict and explain transitions between chemical turbulence and order arbitrarily far from global equilibrium. Our results reveal conceptually new principles of self-organized pattern formation that may well govern diverse dynamical systems.
Kinetics of isotope exchange reactions involving intra- and intermolecular reactions: 1. Rate law for a system with two chemical compounds and three exchangeable atoms

International Nuclear Information System (INIS)

Xuelei Chu; Ohmoto, Hiroshi

1991-01-01

For an isotopic exchange reaction between two compounds (X and AB) in a homogeneous system, such as a gaseous or aqueous system, where one (AB) of them possesses two exchangeable atoms in non-equivalent positions and where one intramolecular isotope exchange (A ↔ B) and two intermolecular isotope exchange reactions (X ↔ A and X ↔ B) may occur, its rate law no longer obeys a pseudo-first order rate equation described for simple two-component systems by many previous investigators. The change with time of the δ value of each of the three components (X, A, and B) in a closed and homogeneous system is a complicated function of the initial δ values of the three components, the chemical concentrations of the two compounds, and the overall rate constants of the forward and reverse reactions involving the two intermolecular and one intramolecular reactions of isotope exchanges. Also, for some one of the three components, the change of its δ value with time may not be monotonic, and the relationship of 1n (1 - F) with time may be non-linear in a plot of 1n (1 - F) vs. t. In addition, the rate law of the isotope exchange reaction in this system also provides a quantitative method to estimate the overall rate constants for the one-intra-and two intermolecular isotope exchanges and the equilibrium isotopic fractionation factors among the three components
Communication: CO oxidation by silver and gold cluster cations: Identification of different active oxygen species

International Nuclear Information System (INIS)

Popolan, Denisia M.; Bernhardt, Thorsten M.

2011-01-01

The oxidation of carbon monoxide with nitrous oxide on mass-selected Au 3 + and Ag 3 + clusters has been investigated under multicollision conditions in an octopole ion trap experiment. The comparative study reveals that for both gold and silver cations carbon dioxide is formed on the clusters. However, whereas in the case of Au 3 + the cluster itself acts as reactive species that facilitates the formation of CO 2 from N 2 O and CO, for silver the oxidized clusters Ag 3 O x + (n= 1-3) are identified as active in the CO oxidation reaction. Thus, in the case of the silver cluster cations N 2 O is dissociated and one oxygen atom is suggested to directly react with CO, whereas a second kind of oxygen strongly bound to silver is acting as a substrate for the reaction.
Communication: CO oxidation by silver and gold cluster cations: Identification of different active oxygen species

Science.gov (United States)

Popolan, Denisia M.; Bernhardt, Thorsten M.

2011-03-01

The oxidation of carbon monoxide with nitrous oxide on mass-selected Au3+ and Ag3+ clusters has been investigated under multicollision conditions in an octopole ion trap experiment. The comparative study reveals that for both gold and silver cations carbon dioxide is formed on the clusters. However, whereas in the case of Au3+ the cluster itself acts as reactive species that facilitates the formation of CO2 from N2O and CO, for silver the oxidized clusters Ag3Ox+ (n = 1-3) are identified as active in the CO oxidation reaction. Thus, in the case of the silver cluster cations N2O is dissociated and one oxygen atom is suggested to directly react with CO, whereas a second kind of oxygen strongly bound to silver is acting as a substrate for the reaction.
Drug reaction with eosinophilia and systemic symptoms syndrome.

Science.gov (United States)

Spriet, Sarah; Banks, Taylor A

2015-01-01

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a potentially life-threatening adverse drug reaction. To increase awareness of the potential for recurrence in patients with a history of DRESS syndrome and provide a brief review of the clinical characteristics, diagnosis, and management of this disease process. The authors selected and reviewed salient articles on the topic and incorporated pertinent information from the patient's clinical course. A case of recurrent DRESS triggered by a structurally unrelated drug is presented, followed by discussion of the clinical characteristics, diagnosis, and management. Clinical pearls and pitfalls are emphasized for the practicing allergist, clinical immunologist, and fellow-in-training. The most important steps in the treatment of this condition are the identification and removal of the offending agent. Providers should be aware of the potential for recurrent DRESS and recognize the importance of prompt management.
Analysis of diffusivity of the oscillating reaction components in a microreactor system

Directory of Open Access Journals (Sweden)

Martina Šafranko

2017-01-01

Full Text Available When performing oscillating reactions, periodical changes in the concentrations of reactants, intermediaries, and products take place. Due to the mentioned periodical changes of the concentrations, the information about the diffusivity of the components included into oscillating reactions is very important for the control of the oscillating reactions. Non-linear dynamics makes oscillating reactions very interesting for analysis in different reactor systems. In this paper, the analysis of diffusivity of the oscillating reaction components was performed in a microreactor, with the aim of identifying the limiting component. The geometry of the microreactor microchannel and a well defined flow profile ensure optimal conditions for the diffusion phenomena analysis, because diffusion profiles in a microreactor depend only on the residence time. In this paper, the analysis of diffusivity of the oscillating reaction components was performed in a microreactor equipped with 2 Y-shape inlets and 2 Y-shape outlets, with active volume of V = 4 μL at different residence times.
A review of post-column photochemical reaction systems coupled to electrochemical detection in HPLC

International Nuclear Information System (INIS)

Fedorowski, Jennifer; LaCourse, William R.

2010-01-01

Post-column photochemical reaction systems have developed into a common approach for enhancing conventional methods of detection in HPLC. Photochemical reactions as a means of 'derivatization' have a significant number of advantages over chemical reaction-based methods, and a significant effort has been demonstrated to develop an efficient photochemical reactor. When coupled to electrochemical (EC) detection, the technique allows for the sensitive and selective determination of a variety of compounds (e.g., organic nitro explosives, beta-lactam antibiotics, sulfur-containing antibiotics, pesticides and insecticides). This review will focus on developments and methods using post-column photochemical reaction systems followed by EC detection in liquid chromatography. Papers are presented in chronological order to emphasize the evolution of the approach and continued importance of the application.
The CCONE Code System and its Application to Nuclear Data Evaluation for Fission and Other Reactions

Science.gov (United States)

Iwamoto, O.; Iwamoto, N.; Kunieda, S.; Minato, F.; Shibata, K.

2016-01-01

A computer code system, CCONE, was developed for nuclear data evaluation within the JENDL project. The CCONE code system integrates various nuclear reaction models needed to describe nucleon, light charged nuclei up to alpha-particle and photon induced reactions. The code is written in the C++ programming language using an object-oriented technology. At first, it was applied to neutron-induced reaction data on actinides, which were compiled into JENDL Actinide File 2008 and JENDL-4.0. It has been extensively used in various nuclear data evaluations for both actinide and non-actinide nuclei. The CCONE code has been upgraded to nuclear data evaluation at higher incident energies for neutron-, proton-, and photon-induced reactions. It was also used for estimating β-delayed neutron emission. This paper describes the CCONE code system indicating the concept and design of coding and inputs. Details of the formulation for modelings of the direct, pre-equilibrium and compound reactions are presented. Applications to the nuclear data evaluations such as neutron-induced reactions on actinides and medium-heavy nuclei, high-energy nucleon-induced reactions, photonuclear reaction and β-delayed neutron emission are mentioned.
The CCONE Code System and its Application to Nuclear Data Evaluation for Fission and Other Reactions

Energy Technology Data Exchange (ETDEWEB)

Iwamoto, O., E-mail: iwamoto.osamu@jaea.go.jp; Iwamoto, N.; Kunieda, S.; Minato, F.; Shibata, K.

2016-01-15

A computer code system, CCONE, was developed for nuclear data evaluation within the JENDL project. The CCONE code system integrates various nuclear reaction models needed to describe nucleon, light charged nuclei up to alpha-particle and photon induced reactions. The code is written in the C++ programming language using an object-oriented technology. At first, it was applied to neutron-induced reaction data on actinides, which were compiled into JENDL Actinide File 2008 and JENDL-4.0. It has been extensively used in various nuclear data evaluations for both actinide and non-actinide nuclei. The CCONE code has been upgraded to nuclear data evaluation at higher incident energies for neutron-, proton-, and photon-induced reactions. It was also used for estimating β-delayed neutron emission. This paper describes the CCONE code system indicating the concept and design of coding and inputs. Details of the formulation for modelings of the direct, pre-equilibrium and compound reactions are presented. Applications to the nuclear data evaluations such as neutron-induced reactions on actinides and medium-heavy nuclei, high-energy nucleon-induced reactions, photonuclear reaction and β-delayed neutron emission are mentioned.
Anomalous dimension in a two-species reaction-diffusion system

Science.gov (United States)

Vollmayr-Lee, Benjamin; Hanson, Jack; McIsaac, R. Scott; Hellerick, Joshua D.

2018-01-01

We study a two-species reaction-diffusion system with the reactions A+A\\to (0, A) and A+B\\to A , with general diffusion constants D A and D B . Previous studies showed that for dimensions d≤slant 2 the B particle density decays with a nontrivial, universal exponent that includes an anomalous dimension resulting from field renormalization. We demonstrate via renormalization group methods that the scaled B particle correlation function has a distinct anomalous dimension resulting in the asymptotic scaling \\tilde CBB(r, t) ˜ tφf(r/\\sqrt{t}) , where the exponent ϕ results from the renormalization of the square of the field associated with the B particles. We compute this exponent to first order in \
A cellular automata approach to chemical reactions : 1 reaction controlled systems

NARCIS (Netherlands)

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

2013-01-01

A direct link between the chemical reaction controlled (shrinking core) model and cellular automata, to study the dissolution of particles, is derived in this paper. Previous research on first and second order reactions is based on the concentration of the reactant. The present paper describes the
Comparative Analysis of Clinical Samples Showing Weak Serum Reaction on AutoVue System Causing ABO Blood Typing Discrepancies.

Science.gov (United States)

Jo, Su Yeon; Lee, Ju Mi; Kim, Hye Lim; Sin, Kyeong Hwa; Lee, Hyeon Ji; Chang, Chulhun Ludgerus; Kim, Hyung Hoi

2017-03-01

ABO blood typing in pre-transfusion testing is a major component of the high workload in blood banks that therefore requires automation. We often experienced discrepant results from an automated system, especially weak serum reactions. We evaluated the discrepant results by the reference manual method to confirm ABO blood typing. In total, 13,113 blood samples were tested with the AutoVue system; all samples were run in parallel with the reference manual method according to the laboratory protocol. The AutoVue system confirmed ABO blood typing of 12,816 samples (97.7%), and these results were concordant with those of the manual method. The remaining 297 samples (2.3%) showed discrepant results in the AutoVue system and were confirmed by the manual method. The discrepant results involved weak serum reactions (serum reactions, samples from patients who had received stem cell transplants, ABO subgroups, and specific system error messages. Among the 98 samples showing ≤1+ reaction grade in the AutoVue system, 70 samples (71.4%) showed a normal serum reaction (≥2+ reaction grade) with the manual method, and 28 samples (28.6%) showed weak serum reaction in both methods. ABO blood tying of 97.7% samples could be confirmed by the AutoVue system and a small proportion (2.3%) needed to be re-evaluated by the manual method. Samples with a 2+ reaction grade in serum typing do not need to be evaluated manually, while those with ≤1+ reaction grade do.
Physical attraction to reliable, low variability nervous systems: Reaction time variability predicts attractiveness.

Science.gov (United States)

Butler, Emily E; Saville, Christopher W N; Ward, Robert; Ramsey, Richard

2017-01-01

The human face cues a range of important fitness information, which guides mate selection towards desirable others. Given humans' high investment in the central nervous system (CNS), cues to CNS function should be especially important in social selection. We tested if facial attractiveness preferences are sensitive to the reliability of human nervous system function. Several decades of research suggest an operational measure for CNS reliability is reaction time variability, which is measured by standard deviation of reaction times across trials. Across two experiments, we show that low reaction time variability is associated with facial attractiveness. Moreover, variability in performance made a unique contribution to attractiveness judgements above and beyond both physical health and sex-typicality judgements, which have previously been associated with perceptions of attractiveness. In a third experiment, we empirically estimated the distribution of attractiveness preferences expected by chance and show that the size and direction of our results in Experiments 1 and 2 are statistically unlikely without reference to reaction time variability. We conclude that an operating characteristic of the human nervous system, reliability of information processing, is signalled to others through facial appearance. Copyright © 2016 Elsevier B.V. All rights reserved.
Emergent structures in reaction-advection-diffusion systems on a sphere

Science.gov (United States)

Krause, Andrew L.; Burton, Abigail M.; Fadai, Nabil T.; Van Gorder, Robert A.

2018-04-01

We demonstrate unusual effects due to the addition of advection into a two-species reaction-diffusion system on the sphere. We find that advection introduces emergent behavior due to an interplay of the traditional Turing patterning mechanisms with the compact geometry of the sphere. Unidirectional advection within the Turing space of the reaction-diffusion system causes patterns to be generated at one point of the sphere, and transported to the antipodal point where they are destroyed. We illustrate these effects numerically and deduce conditions for Turing instabilities on local projections to understand the mechanisms behind these behaviors. We compare this behavior to planar advection which is shown to only transport patterns across the domain. Analogous transport results seem to hold for the sphere under azimuthal transport or away from the antipodal points in unidirectional flow regimes.
System and process for pulsed multiple reaction monitoring

Science.gov (United States)

Belov, Mikhail E

2013-05-17

A new pulsed multiple reaction monitoring process and system are disclosed that uses a pulsed ion injection mode for use in conjunction with triple-quadrupole instruments. The pulsed injection mode approach reduces background ion noise at the detector, increases amplitude of the ion signal, and includes a unity duty cycle that provides a significant sensitivity increase for reliable quantitation of proteins/peptides present at attomole levels in highly complex biological mixtures.

The analysis of magnesium oxide hydration in three-phase reaction system

Energy Technology Data Exchange (ETDEWEB)

Tang, Xiaojia; Guo, Lin; Chen, Chen; Liu, Quan; Li, Tie; Zhu, Yimin, E-mail: ntp@dlmu.edu.cn

2014-05-01

In order to investigate the magnesium oxide hydration process in gas–liquid–solid (three-phase) reaction system, magnesium hydroxide was prepared by magnesium oxide hydration in liquid–solid (two-phase) and three-phase reaction systems. A semi-empirical model and the classical shrinking core model were used to fit the experimental data. The fitting result shows that both models describe well the hydration process of three-phase system, while only the semi-empirical model right for the hydration process of two-phase system. The characterization of the hydration product using X-Ray diffraction (XRD) and scanning electron microscope (SEM) was performed. The XRD and SEM show hydration process in the two-phase system follows common dissolution/precipitation mechanism. While in the three-phase system, the hydration process undergo MgO dissolution, Mg(OH){sub 2} precipitation, Mg(OH){sub 2} peeling off from MgO particle and leaving behind fresh MgO surface. - Graphical abstract: There was existence of a peeling-off process in the gas–liquid–solid (three-phase) MgO hydration system. - Highlights: • Magnesium oxide hydration in gas–liquid–solid system was investigated. • The experimental data in three-phase system could be fitted well by two models. • The morphology analysis suggested that there was existence of a peel-off process.
Large-time behavior of solutions to a reaction-diffusion system with distributed microstructure

NARCIS (Netherlands)

Muntean, A.

2009-01-01

Abstract We study the large-time behavior of a class of reaction-diffusion systems with constant distributed microstructure arising when modeling diffusion and reaction in structured porous media. The main result of this Note is the following: As t ¿ 8 the macroscopic concentration vanishes, while
Pattern dynamics of the reaction-diffusion immune system.

Science.gov (United States)

Zheng, Qianqian; Shen, Jianwei; Wang, Zhijie

2018-01-01

In this paper, we will investigate the effect of diffusion, which is ubiquitous in nature, on the immune system using a reaction-diffusion model in order to understand the dynamical behavior of complex patterns and control the dynamics of different patterns. Through control theory and linear stability analysis of local equilibrium, we obtain the optimal condition under which the system loses stability and a Turing pattern occurs. By combining mathematical analysis and numerical simulation, we show the possible patterns and how these patterns evolve. In addition, we establish a bridge between the complex patterns and the biological mechanism using the results from a previous study in Nature Cell Biology. The results in this paper can help us better understand the biological significance of the immune system.
Reaction mechanism and reaction coordinates from the viewpoint of energy flow

Energy Technology Data Exchange (ETDEWEB)

Li, Wenjin; Ma, Ao, E-mail: aoma@uic.edu [Department of Bioengineering, The University of Illinois at Chicago, 851 South Morgan Street, Chicago, Illinois 60607 (United States)

2016-03-21

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

International Nuclear Information System (INIS)

Li, Wenjin; Ma, Ao

2016-01-01

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

Directory of Open Access Journals (Sweden)

Ai-Nong YU

Full Text Available Abstract Under the conditions of weak basis and the reaction temperature range of 110-150 °C, lysine, arginine and histidine were reacted with L-ascorbic acid at equal amount for 30-150 min, respectively and the formation of browning products was monitored with UV–vis spectrometry. The kinetic characteristics of their non-enzymatic browning reaction were investigated. The study results indicated that the non-enzymatic browning reaction of these three amino acids with L-ascorbic acid to form browning products was zero-order reaction. The apparent activation energies for the formation of browning products from L-ascorbic acid/lysine, L-ascorbic acid/arginine and L-ascorbic acid/histidine systems were 54.94, 50.08 and 35.31kJ/mol. The activation energy data indicated the degree of effects of reaction temperature on non-enzymatic browning reaction. Within the temperature range of 110-150 °C, the reaction rate of L-ascorbic acid/lysine system was the fastest one, followed by that of the L-ascorbic acid/arginine system. The reaction rate of L-ascorbic acid/histidine system was the slowest one. Based on the observed kinetic data, the formation mechanisms of browning products were proposed.
[Production of sugar syrup containing rare sugar using dual-enzyme coupled reaction system].

Science.gov (United States)

Han, Wenjia; Zhu, Yueming; Bai, Wei; Izumori, Ken; Zhang, Tongcun; Sun, Yuanxia

2014-01-01

Enzymatic conversion is very important to produce functional rare sugars, but the conversion rate of single enzymes is generally low. To increase the conversion rate, a dual-enzyme coupled reaction system was developed. Dual-enzyme coupled reaction system was constructed using D-psicose-3-epimerase (DPE) and L-rhamnose isomerase (L-RhI), and used to convert D-fructose to D-psicose and D-allose. The ratio of DPE and L-RhI was 1:10 (W/W), and the concentration of DPE was 0.05 mg/mL. The optimum temperature was 60 degrees C and pH was 9.0. When the concentration of D-fructose was 2%, the reaction reached its equilibrium after 10 h, and the yield of D-psicose and D-allose was 5.12 and 2.04 g/L, respectively. Using the dual-enzymes coupled system developed in the current study, we could obtain sugar syrup containing functional rare sugar from fructose-rich raw material, such as high fructose corn syrup.
An optics-based variable-temperature assay system for characterizing thermodynamics of biomolecular reactions on solid support

Energy Technology Data Exchange (ETDEWEB)

Fei, Yiyan; Landry, James P.; Zhu, X. D., E-mail: xdzhu@physics.ucdavis.edu [Department of Physics, University of California, One Shields Avenue, Davis, California 95616 (United States); Li, Yanhong; Yu, Hai; Lau, Kam; Huang, Shengshu; Chokhawala, Harshal A.; Chen, Xi [Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616 (United States)

2013-11-15

A biological state is equilibrium of multiple concurrent biomolecular reactions. The relative importance of these reactions depends on physiological temperature typically between 10 °C and 50 °C. Experimentally the temperature dependence of binding reaction constants reveals thermodynamics and thus details of these biomolecular processes. We developed a variable-temperature opto-fluidic system for real-time measurement of multiple (400–10 000) biomolecular binding reactions on solid supports from 10 °C to 60 °C within ±0.1 °C. We illustrate the performance of this system with investigation of binding reactions of plant lectins (carbohydrate-binding proteins) with 24 synthetic glycans (i.e., carbohydrates). We found that the lectin-glycan reactions in general can be enthalpy-driven, entropy-driven, or both, and water molecules play critical roles in the thermodynamics of these reactions.
New model of chlorine-wall reaction for simulating chlorine concentration in drinking water distribution systems.

Science.gov (United States)

Fisher, Ian; Kastl, George; Sathasivan, Arumugam

2017-11-15

Accurate modelling of chlorine concentrations throughout a drinking water system needs sound mathematical descriptions of decay mechanisms in bulk water and at pipe walls. Wall-reaction rates along pipelines in three different systems were calculated from differences between field chlorine profiles and accurately modelled bulk decay. Lined pipes with sufficiently large diameters (>500 mm) and higher chlorine concentrations (>0.5 mg/L) had negligible wall-decay rates, compared with bulk-decay rates. Further downstream, wall-reaction rate consistently increased (peaking around 0.15 mg/dm 2 /h) as chlorine concentration decreased, until mass-transport to the wall was controlling wall reaction. These results contradict wall-reaction models, including those incorporated in the EPANET software, which assume wall decay is of either zero-order (constant decay rate) or first-order (wall-decay rate reduces with chlorine concentration). Instead, results are consistent with facilitation of the wall reaction by biofilm activity, rather than surficial chemical reactions. A new model of wall reaction combines the effect of biofilm activity moderated by chlorine concentration and mass-transport limitation. This wall reaction model, with an accurate bulk chlorine decay model, is essential for sufficiently accurate prediction of chlorine residuals towards the end of distribution systems and therefore control of microbial contamination. Implementing this model in EPANET-MSX (or similar) software enables the accurate chlorine modelling required for improving disinfection strategies in drinking water networks. New insight into the effect of chlorine on biofilm can also assist in controlling biofilm to maintain chlorine residuals. Copyright © 2017 Elsevier Ltd. All rights reserved.
The urgent need for a harmonized severity scoring system for acute allergic reactions

DEFF Research Database (Denmark)

Muraro, Antonella; Fernandez-Rivas, Montserrat; Beyer, Kirsten

2018-01-01

The accurate assessment and communication of the severity of acute allergic reactions is important to patients, clinicians, researchers, the food industry, public health and regulatory authorities. Severity has different meanings to different stakeholders with patients and clinicians rating...... of different stakeholder groups. We propose a novel approach to develop and then validate a harmonized scoring system for acute allergic reactions, based on a data-driven method that is informed by clinical and patient experience and other stakeholders' perspectives. We envisage two formats: (i) a numerical...... the significance of particular symptoms very differently. Many severity scoring systems have been generated, most focusing on the severity of reactions following exposure to a limited group of allergens. They are heterogeneous in format, none has used an accepted developmental approach and none has been validated...
Chemical reaction of hexagonal boron nitride and graphite nanoclusters in mechanical milling systems

Energy Technology Data Exchange (ETDEWEB)

Muramatsu, Y.; Grush, M.; Callcott, T.A. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

1997-04-01

Synthesis of boron-carbon-nitride (BCN) hybrid alloys has been attempted extensively by many researchers because the BCN alloys are considered an extremely hard material called {open_quotes}super diamond,{close_quotes} and the industrial application for wear-resistant materials is promising. A mechanical alloying (MA) method of hexagonal boron nitride (h-BN) with graphite has recently been studied to explore the industrial synthesis of the BCN alloys. To develop the MA method for the BCN alloy synthesis, it is necessary to confirm the chemical reaction processes in the mechanical milling systems and to identify the reaction products. Therefore, the authors have attempted to confirm the chemical reaction process of the h-BN and graphite in mechanical milling systems using x-ray absorption near edge structure (XANES) methods.
Chemical reaction of hexagonal boron nitride and graphite nanoclusters in mechanical milling systems

International Nuclear Information System (INIS)

Muramatsu, Y.; Grush, M.; Callcott, T.A.

1997-01-01

Synthesis of boron-carbon-nitride (BCN) hybrid alloys has been attempted extensively by many researchers because the BCN alloys are considered an extremely hard material called open-quotes super diamond,close quotes and the industrial application for wear-resistant materials is promising. A mechanical alloying (MA) method of hexagonal boron nitride (h-BN) with graphite has recently been studied to explore the industrial synthesis of the BCN alloys. To develop the MA method for the BCN alloy synthesis, it is necessary to confirm the chemical reaction processes in the mechanical milling systems and to identify the reaction products. Therefore, the authors have attempted to confirm the chemical reaction process of the h-BN and graphite in mechanical milling systems using x-ray absorption near edge structure (XANES) methods
Interchange reaction of disulfides and denaturation of oxytocin by copper(II)/ascorbic acid/O2 system.

Science.gov (United States)

Inoue, H; Hirobe, M

1987-05-29

The interchange reaction of disulfides was caused by the copper(II)/ascorbic acid/O2 system. The incubation of two symmetric disulfides, L-cystinyl-bis-L-phenylalanine (PP) and L-cystinyl-bis-L-tyrosine (TT), with L-ascorbic acid and CuSO4 in potassium phosphate buffer (pH 7.2, 50 mM) resulted in the formation of an asymmetric disulfide, L-cystinyl-L-phenylalanine-L-tyrosine (PT), and the final ratio of PP:PT:TT was 1:2:1. As the reaction was inhibited by catalase and DMSO only at the initial time, hydroxyl radical generated by the copper(II)/ascorbic acid/O2 system seemed to be responsible for the initiation of the reaction. Oxytocin and insulin were denatured by this system, and catalase and DMSO similarly inhibited these denaturations. As the composition of amino acids was unchanged after the reaction, hydroxyl radical was thought to cause the cleavage and/or interchange reaction of disulfides to denature the peptides.
Conditional symmetries for systems of PDEs: new definitions and their application for reaction-diffusion systems

International Nuclear Information System (INIS)

Cherniha, Roman

2010-01-01

New definitions of Q-conditional symmetry for systems of PDEs are presented, which generalize the standard notation of non-classical (conditional) symmetry. It is shown that different types of Q-conditional symmetry of a system generate a hierarchy of conditional symmetry operators. A class of two-component nonlinear reaction-diffusion systems is examined to demonstrate the applicability of the definitions proposed and it is shown when different definitions of Q-conditional symmetry lead to the same operators.
Exchange reactions in the systems of alkali metal, silver and thallium, sulfates, niobates and tantalates

International Nuclear Information System (INIS)

Belyaev, I.N.; Lupejko, T.G.; Nalbandyan, V.B.; Abanina, E.V.

1978-01-01

Investigated are exchange interactions in diagonal cross sections of twenty triple mutual systems with A and A' cations and SO 4 and MO 3 anions where A and A'-Li, Na, K, Ag, Tl, M-Nb, Ta using the methods of X-ray phase, chemical and differential thermal analyses. Exchange reaction between crystal complex oxide and melted salt are effective synthesis method. These reactions in particular permitted to obtain pure AgNbO 3 , AgTaO 3 and their solid solutions at temperatures hundreds degrees lower than in displacement reactions. Equilibrium samples of AMO 3 -A'MO 3 systems, continuous or discontinuous solid solutions, compounds (except NaMO 3 -KMO 3 , and also LiTaO 3 -KTaO 3 ) are formed in exchange reactions when there is sulfate shortage. Thus, exchange reactions can be applied for solid solution synthesis, and also for phase diagram study
A comparison of approximation techniques for variance-based sensitivity analysis of biochemical reaction systems

Directory of Open Access Journals (Sweden)

Goutsias John

2010-05-01

Full Text Available Abstract Background Sensitivity analysis is an indispensable tool for the analysis of complex systems. In a recent paper, we have introduced a thermodynamically consistent variance-based sensitivity analysis approach for studying the robustness and fragility properties of biochemical reaction systems under uncertainty in the standard chemical potentials of the activated complexes of the reactions and the standard chemical potentials of the molecular species. In that approach, key sensitivity indices were estimated by Monte Carlo sampling, which is computationally very demanding and impractical for large biochemical reaction systems. Computationally efficient algorithms are needed to make variance-based sensitivity analysis applicable to realistic cellular networks, modeled by biochemical reaction systems that consist of a large number of reactions and molecular species. Results We present four techniques, derivative approximation (DA, polynomial approximation (PA, Gauss-Hermite integration (GHI, and orthonormal Hermite approximation (OHA, for analytically approximating the variance-based sensitivity indices associated with a biochemical reaction system. By using a well-known model of the mitogen-activated protein kinase signaling cascade as a case study, we numerically compare the approximation quality of these techniques against traditional Monte Carlo sampling. Our results indicate that, although DA is computationally the most attractive technique, special care should be exercised when using it for sensitivity analysis, since it may only be accurate at low levels of uncertainty. On the other hand, PA, GHI, and OHA are computationally more demanding than DA but can work well at high levels of uncertainty. GHI results in a slightly better accuracy than PA, but it is more difficult to implement. OHA produces the most accurate approximation results and can be implemented in a straightforward manner. It turns out that the computational cost of the
A Review of Study on Thermal Energy Transport System by Synthesis and Decomposition Reactions of Methanol

Science.gov (United States)

Liu, Qiusheng; Yabe, Akira; Kajiyama, Shiro; Fukuda, Katsuya

The study on thermal energy transport system by synthesis and decomposition reactions of methanol was reviewed. To promote energy conservation and global environment protection, a two-step liquid-phase methanol synthesis process, which starts with carbonylation of methanol to methyl formate, then followed by the hydrogenolysis of the formate, was studied to recover wasted or unused discharged heat from industrial sources for the thermal energy demands of residential and commercial areas by chemical reactions. The research and development of the system were focused on the following three points. (1) Development of low-temperature decomposition and synthetic catalysts, (2) Development of liquid phase reactor (heat exchanger accompanying chemical reaction), (3) Simulation of the energy transport efficiency of entire system which contains heat recovery and supply sections. As the result of the development of catalyst, promising catalysts which agree with the development purposes for the methyl formate decomposition reaction and the synthetic reaction are being developed though some studies remain for the methanol decomposition and synthetic reactions. In the fundamental development of liquid phase reactor, the solubilities of CO and H2 gases in methanol and methyl formate were measured by the method of total pressure decrease due to absorption under pressures up to 1500kPa and temperatures up to 140°C. The diffusivity of CO gas in methanol was determined by measuring the diameter and solution time of single CO bubbles in methanol. The chemical reaction rate of methanol synthesis by hydrogenolysis of methyl formate was measured using a plate-type of Raney copper catalyst in a reactor with rectangular channel and in an autoclave reactor. The reaction characteristics were investigated by carrying out the experiments at various temperatures, flow rates and at various catalyst development conditions. We focused on the effect of Raney copper catalyst thickness on the liquid
Variationally optimal selection of slow coordinates and reaction coordinates in macromolecular systems

Science.gov (United States)

Noe, Frank

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

NARCIS (Netherlands)

Zheng, Kunpeng; Adriaensens, Peter; De Schutter, Geert; Ye, G.; Taerwe, Luc

2016-01-01

This work is intended to provide a better understanding about the properties and roles of the reaction rim in an alkali-silica reaction. A simplified calcium-alkali-silicate system was created to simulate the multiple interactions among reactive silica, alkaline solution and portlandite near the
Comparison of no gas and He/H2 cell modes used for reduction of isobaric interferences in selenium speciation by ion chromatography with inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Chen Zuliang; Wang Weihong; Mallavarapu, Megharaj; Naidu, Ravendra

2008-01-01

Inductively coupled plasma mass spectrometry (ICP-MS) used for the detection of most common selenium isotopes 78 Se (23.8%, abundance) and 80 Se (49.6%, abundance) is interfered in the presence of 38 Ar 40 Ar + and 40 Ar 40 Ar + in argon (Ar) gas. To address this issue, ICP-MS with an octopole reaction system (ORS) was explored for the detection of selenite and selenate, which was separated by anion-exchange chromatography. Results indicate that it was possible to detect 78 Se using no collusion gas, while to detect 80 Se a H 2 as the collusion/reaction gas was recommended since the background and noise were significantly reduced using H 2 as the gas. The selenium speciation interested was separated on a new column (G3154/101A, Agilent technologies) within 5 min using a mobile phase containing 10 mM NH 4 H 2 PO 4 and 20 mM NH 4 NO 3 at pH 6.5. Linear plots were obtained in a concentration range of 1-200 μg/L with detection limits less than of 0.4 μg/L for 80 Se (IV) and 0.6 μg/L for 80 Se (VI) using H 2 as the reaction gas. Finally, the proposed method was used in the determination of selenium in water and soil

Cutaneous and systemic hypersensitivity reactions to metallic implants

DEFF Research Database (Denmark)

Basko-Plluska, Juliana L; Thyssen, Jacob P; Schalock, Peter C

2011-01-01

Cutaneous reactions to metal implants, orthopedic or otherwise, are well documented in the literature. The first case of a dermatitis reaction over a stainless steel fracture plate was described in 1966. Most skin reactions are eczematous and allergic in nature, although urticarial, bullous....... However, other metal ions as well as bone cement components can cause such hypersensitivity reactions. To complicate things, patients may also develop delayed-type hypersensitivity reactions to metals (ie, in-stent restenosis, prosthesis loosening, inflammation, pain, or allergic contact dermatitis...
Polymerase chain reaction system using magnetic beads for analyzing a sample that includes nucleic acid

Science.gov (United States)

Nasarabadi, Shanavaz [Livermore, CA

2011-01-11

A polymerase chain reaction system for analyzing a sample containing nucleic acid includes providing magnetic beads; providing a flow channel having a polymerase chain reaction chamber, a pre polymerase chain reaction magnet position adjacent the polymerase chain reaction chamber, and a post pre polymerase magnet position adjacent the polymerase chain reaction chamber. The nucleic acid is bound to the magnetic beads. The magnetic beads with the nucleic acid flow to the pre polymerase chain reaction magnet position in the flow channel. The magnetic beads and the nucleic acid are washed with ethanol. The nucleic acid in the polymerase chain reaction chamber is amplified. The magnetic beads and the nucleic acid are separated into a waste stream containing the magnetic beads and a post polymerase chain reaction mix containing the nucleic acid. The reaction mix containing the nucleic acid flows to an analysis unit in the channel for analysis.
Discussion of the Investigation Method on the Reaction Kinetics of Metallurgical Reaction Engineering

Science.gov (United States)

Du, Ruiling; Wu, Keng; Zhang, Jiazhi; Zhao, Yong

Reaction kinetics of metallurgical physical chemistry which was successfully applied in metallurgy (as ferrous metallurgy, non-ferrous metallurgy) became an important theoretical foundation for subject system of traditional metallurgy. Not only the research methods were very perfect, but also the independent structures and systems of it had been formed. One of the important tasks of metallurgical reaction engineering was the simulation of metallurgical process. And then, the mechanism of reaction process and the conversion time points of different control links should be obtained accurately. Therefore, the research methods and results of reaction kinetics in metallurgical physical chemistry were not very suitable for metallurgical reaction engineering. In order to provide the definite conditions of transmission, reaction kinetics parameters and the conversion time points of different control links for solving the transmission and reaction equations in metallurgical reaction engineering, a new method for researching kinetics mechanisms in metallurgical reaction engineering was proposed, which was named stepwise attempt method. Then the comparison of results between the two methods and the further development of stepwise attempt method were discussed in this paper. As a new research method for reaction kinetics in metallurgical reaction engineering, stepwise attempt method could not only satisfy the development of metallurgical reaction engineering, but also provide necessary guarantees for establishing its independent subject system.
Problem of designing composite systems with allowance for reactions between phases

International Nuclear Information System (INIS)

Seredenko, V.N.; Yatsko, B.G.

1986-01-01

The authors study the effect of interphase chemical reactions on the formation of a composite, determine its corrected mechanical characteristics, and subsequently study the stress-strain state of the composite system in the presence of interphase structures. Specific examples of composite systems with a titanium matrix and reinforcing boron fibers are examined. Two cases are considered, the fibers have or do not have a coating of silicon carbide. Graphs illustrate the stress concentration for the boron-titanium composite system
Thermochemical study of deuterium exchange reactions in water-alcohol and alcohol-alcohol systems

International Nuclear Information System (INIS)

Khurma, J.R.; Fenby, D.V.

1979-01-01

Molar excess enthalpies of water-alcohol systems have been analyzed to give equilibrium constants and enthalpies of the reactions 2ROH + D 2 O = 2ROD + H 2 O (R = CH 3 , C 2 H 5 , n-C 3 H 7 ). The equilibrium constants are significantly greater than the ''random'' value. Molar excess enthalpies of alcohol-alcohol systems have been analyzed to give enthalpies of reactions ROH + R'OD = ROD + R'OH. The enthalpies of water-alcohol and alcohol-alcohol exchange reactions form a self-consistent set and are in good agreement with values from earlier studies. Molar excess enthalpies at 298.15 K are reported for n-C 3 H 7 OH and n-C 3 H 7 OD with H 2 O, D 2 O, CH 3 OH, CH 3 OD, C 2 H 5 OH, and C 2 H 5 OD
Stability analysis of non-autonomous reaction-diffusion systems: the effects of growing domains

KAUST Repository

Madzvamuse, Anotida; Gaffney, Eamonn A.; Maini, Philip K.

2009-01-01

By using asymptotic theory, we generalise the Turing diffusively-driven instability conditions for reaction-diffusion systems with slow, isotropic domain growth. There are two fundamental biological differences between the Turing conditions on fixed and growing domains, namely: (i) we need not enforce cross nor pure kinetic conditions and (ii) the restriction to activator-inhibitor kinetics to induce pattern formation on a growing biological system is no longer a requirement. Our theoretical findings are confirmed and reinforced by numerical simulations for the special cases of isotropic linear, exponential and logistic growth profiles. In particular we illustrate an example of a reaction-diffusion system which cannot exhibit a diffusively-driven instability on a fixed domain but is unstable in the presence of slow growth. © Springer-Verlag 2009.
Stability analysis of non-autonomous reaction-diffusion systems: the effects of growing domains

KAUST Repository

Madzvamuse, Anotida

2009-08-29

By using asymptotic theory, we generalise the Turing diffusively-driven instability conditions for reaction-diffusion systems with slow, isotropic domain growth. There are two fundamental biological differences between the Turing conditions on fixed and growing domains, namely: (i) we need not enforce cross nor pure kinetic conditions and (ii) the restriction to activator-inhibitor kinetics to induce pattern formation on a growing biological system is no longer a requirement. Our theoretical findings are confirmed and reinforced by numerical simulations for the special cases of isotropic linear, exponential and logistic growth profiles. In particular we illustrate an example of a reaction-diffusion system which cannot exhibit a diffusively-driven instability on a fixed domain but is unstable in the presence of slow growth. © Springer-Verlag 2009.
Robotic reactions: Delay-induced patterns in autonomous vehicle systems

Science.gov (United States)

Orosz, Gábor; Moehlis, Jeff; Bullo, Francesco

2010-02-01

Fundamental design principles are presented for vehicle systems governed by autonomous cruise control devices. By analyzing the corresponding delay differential equations, it is shown that for any car-following model short-wavelength oscillations can appear due to robotic reaction times, and that there are tradeoffs between the time delay and the control gains. The analytical findings are demonstrated on an optimal velocity model using numerical continuation and numerical simulation.
Robotic reactions: delay-induced patterns in autonomous vehicle systems.

Science.gov (United States)

Orosz, Gábor; Moehlis, Jeff; Bullo, Francesco

2010-02-01

Fundamental design principles are presented for vehicle systems governed by autonomous cruise control devices. By analyzing the corresponding delay differential equations, it is shown that for any car-following model short-wavelength oscillations can appear due to robotic reaction times, and that there are tradeoffs between the time delay and the control gains. The analytical findings are demonstrated on an optimal velocity model using numerical continuation and numerical simulation.
Numerical simulation of reaction-diffusion systems by modified cubic B-spline differential quadrature method

International Nuclear Information System (INIS)

Mittal, R.C.; Rohila, Rajni

2016-01-01

In this paper, we have applied modified cubic B-spline based differential quadrature method to get numerical solutions of one dimensional reaction-diffusion systems such as linear reaction-diffusion system, Brusselator system, Isothermal system and Gray-Scott system. The models represented by these systems have important applications in different areas of science and engineering. The most striking and interesting part of the work is the solution patterns obtained for Gray Scott model, reminiscent of which are often seen in nature. We have used cubic B-spline functions for space discretization to get a system of ordinary differential equations. This system of ODE’s is solved by highly stable SSP-RK43 method to get solution at the knots. The computed results are very accurate and shown to be better than those available in the literature. Method is easy and simple to apply and gives solutions with less computational efforts.
Cutaneous and systemic hypersensitivity reactions to metallic implants

DEFF Research Database (Denmark)

Basko-Plluska, Juliana L; Thyssen, Jacob P; Schalock, Peter C

2011-01-01

) following the insertion of intravascular stents, dental implants, cardiac pacemakers, or implanted gynecologic devices. Despite repeated attempts by researchers and clinicians to further understand this difficult area of medicine, the association between metal sensitivity and cutaneous allergic reactions......Cutaneous reactions to metal implants, orthopedic or otherwise, are well documented in the literature. The first case of a dermatitis reaction over a stainless steel fracture plate was described in 1966. Most skin reactions are eczematous and allergic in nature, although urticarial, bullous......, and vasculitic eruptions may occur. Also, more complex immune reactions may develop around the implants, resulting in pain, inflammation, and loosening. Nickel, cobalt, and chromium are the three most common metals that elicit both cutaneous and extracutaneous allergic reactions from chronic internal exposure...
Simulations of pattern dynamics for reaction-diffusion systems via SIMULINK.

Science.gov (United States)

Wang, Kaier; Steyn-Ross, Moira L; Steyn-Ross, D Alistair; Wilson, Marcus T; Sleigh, Jamie W; Shiraishi, Yoichi

2014-04-11

Investigation of the nonlinear pattern dynamics of a reaction-diffusion system almost always requires numerical solution of the system's set of defining differential equations. Traditionally, this would be done by selecting an appropriate differential equation solver from a library of such solvers, then writing computer codes (in a programming language such as C or Matlab) to access the selected solver and display the integrated results as a function of space and time. This "code-based" approach is flexible and powerful, but requires a certain level of programming sophistication. A modern alternative is to use a graphical programming interface such as Simulink to construct a data-flow diagram by assembling and linking appropriate code blocks drawn from a library. The result is a visual representation of the inter-relationships between the state variables whose output can be made completely equivalent to the code-based solution. As a tutorial introduction, we first demonstrate application of the Simulink data-flow technique to the classical van der Pol nonlinear oscillator, and compare Matlab and Simulink coding approaches to solving the van der Pol ordinary differential equations. We then show how to introduce space (in one and two dimensions) by solving numerically the partial differential equations for two different reaction-diffusion systems: the well-known Brusselator chemical reactor, and a continuum model for a two-dimensional sheet of human cortex whose neurons are linked by both chemical and electrical (diffusive) synapses. We compare the relative performances of the Matlab and Simulink implementations. The pattern simulations by Simulink are in good agreement with theoretical predictions. Compared with traditional coding approaches, the Simulink block-diagram paradigm reduces the time and programming burden required to implement a solution for reaction-diffusion systems of equations. Construction of the block-diagram does not require high-level programming
Limits for Stochastic Reaction Networks

DEFF Research Database (Denmark)

Cappelletti, Daniele

Reaction systems have been introduced in the 70s to model biochemical systems. Nowadays their range of applications has increased and they are fruitfully used in dierent elds. The concept is simple: some chemical species react, the set of chemical reactions form a graph and a rate function...... is associated with each reaction. Such functions describe the speed of the dierent reactions, or their propensities. Two modelling regimes are then available: the evolution of the dierent species concentrations can be deterministically modelled through a system of ODE, while the counts of the dierent species...... at a certain time are stochastically modelled by means of a continuous-time Markov chain. Our work concerns primarily stochastic reaction systems, and their asymptotic properties. In Paper I, we consider a reaction system with intermediate species, i.e. species that are produced and fast degraded along a path...
The TDF System for Thermonuclear Plasma Reaction Rates, Mean Energies and Two-Body Final State Particle Spectra

International Nuclear Information System (INIS)

Warshaw, S I

2001-01-01

The rate of thermonuclear reactions in hot plasmas as a function of local plasma temperature determines the way in which thermonuclear ignition and burning proceeds in the plasma. The conventional model approach to calculating these rates is to assume that the reacting nuclei in the plasma are in Maxwellian equilibrium at some well-defined plasma temperature, over which the statistical average of the reaction rate quantity σv is calculated, where σ is the cross-section for the reaction to proceed at the relative velocity v between the reacting particles. This approach is well-understood and is the basis for much nuclear fusion and astrophysical nuclear reaction rate data. The Thermonuclear Data File (TDF) system developed at the Lawrence Livermore National Laboratory (Warshaw 1991), which is the topic of this report, contains data on the Maxwellian-averaged thermonuclear reaction rates for various light nuclear reactions and the correspondingly Maxwellian-averaged energy spectra of the particles in the final state of those reactions as well. This spectral information closely models the output particle and energy distributions in a burning plasma, and therefore leads to more accurate computational treatments of thermonuclear burn, output particle energy deposition and diagnostics, in various contexts. In this report we review and derive the theoretical basis for calculating Maxwellian-averaged thermonuclear reaction rates, mean particle energies, and output particle spectral energy distributions for these reactions in the TDF system. The treatment of the kinematics is non-relativistic. The current version of the TDF system provides exit particle energy spectrum distributions for two-body final state reactions only. In a future report we will discuss and describe how output particle energy spectra for three- and four-body final states can be developed for the TDF system. We also include in this report a description of the algorithmic implementation of the TDF
Cutaneous and systemic hypersensitivity reactions to metallic implants.

Science.gov (United States)

Basko-Plluska, Juliana L; Thyssen, Jacob P; Schalock, Peter C

2011-01-01

Cutaneous reactions to metal implants, orthopedic or otherwise, are well documented in the literature. The first case of a dermatitis reaction over a stainless steel fracture plate was described in 1966. Most skin reactions are eczematous and allergic in nature, although urticarial, bullous, and vasculitic eruptions may occur. Also, more complex immune reactions may develop around the implants, resulting in pain, inflammation, and loosening. Nickel, cobalt, and chromium are the three most common metals that elicit both cutaneous and extracutaneous allergic reactions from chronic internal exposure. However, other metal ions as well as bone cement components can cause such hypersensitivity reactions. To complicate things, patients may also develop delayed-type hypersensitivity reactions to metals (ie, in-stent restenosis, prosthesis loosening, inflammation, pain, or allergic contact dermatitis) following the insertion of intravascular stents, dental implants, cardiac pacemakers, or implanted gynecologic devices. Despite repeated attempts by researchers and clinicians to further understand this difficult area of medicine, the association between metal sensitivity and cutaneous allergic reactions remains to be fully understood. This review provides an update of the current knowledge in this field and should be valuable to health care providers who manage patients with conditions related to this field.
Drug reaction with eosinophilia and systemic symptoms without skin rash.

Science.gov (United States)

Sasidharanpillai, Sarita; Binitha, Manikoth P; Manikath, Neeraj; Janardhanan, Anisha K

2015-01-01

Drug reaction with eosinophilia and systemic symptoms (DRESS) or drug hypersensitivity syndrome is considered as a severe cutaneous adverse drug reaction which is most commonly precipitated by aromatic anticonvulsants, lamotrigine, dapsone, allopurinol, minocycline, and salazopyrin. Its clinical manifestations are often variable. On rare occasions, it can present with only systemic involvement without any cutaneous features. A complete drug history is of paramount importance in making an early diagnosis. We report the case of a male patient who presented with fever, lymphadenopathy, hepatosplenomegaly, and hepatitis, 2 weeks after starting salazopyrin. The presence of atypical lymphocytes in the peripheral smear was indicative of a viral infection or a hematological dyscrasia. Bone marrow examination revealed a normocellular marrow with an increase in eosinophil precursors. Investigations for the common causes for fever and hepatitis were negative. The presence of eosinophilia, the temporal relationship of the symptoms with the initiation of treatment with salazopyrin, and the marked improvement on withdrawal of the drug along with the administration of systemic corticosteroids, were features consistent with the diagnosis of DRESS. With the incidence of this condition showing a rising trend, it is important for the clinician to be aware of its variable manifestations, as a delay in diagnosis and treatment can be fatal.
Modeling and simulation of enzymatic gluconic acid production using immobilized enzyme and CSTR-PFTR circulation reaction system.

Science.gov (United States)

Li, Can; Lin, Jianqun; Gao, Ling; Lin, Huibin; Lin, Jianqiang

2018-04-01

Production of gluconic acid by using immobilized enzyme and continuous stirred tank reactor-plug flow tubular reactor (CSTR-PFTR) circulation reaction system. A production system is constructed for gluconic acid production, which consists of a continuous stirred tank reactor (CSTR) for pH control and liquid storage and a plug flow tubular reactor (PFTR) filled with immobilized glucose oxidase (GOD) for gluconic acid production. Mathematical model is developed for this production system and simulation is made for the enzymatic reaction process. The pH inhibition effect on GOD is modeled by using a bell-type curve. Gluconic acid can be efficiently produced by using the reaction system and the mathematical model developed for this system can simulate and predict the process well.
Configuration of a pulse radiolysis system for the study of gas-phase reactions and kinetic investigations of the reactions of hydroxyl radicals with methyl and ethyl radicals

International Nuclear Information System (INIS)

Fagerstroem, K.

1993-01-01

The work that is presented in this thesis deals with the assembling and testing of a pulse radiolysis system for kinetic studies of gas-phase reactions as well as with the kinetics of the gas-phase reactions of hydroxyl radicals with methyl and ethyl radicals. These radicals are very important as these are formed at an early stage in hydrocarbon combustion processes. The two studied reactions are key reactions in those processes. (6 refs., 4 figs., 2 tabs.)
Interfacial reactions in the Sb–Sn/(Cu, Ni) systems: Wetting experiments

International Nuclear Information System (INIS)

Novakovic, R.; Lanata, T.; Delsante, S.; Borzone, G.

2012-01-01

Interfacial reactions in the Sb–Sn/Cu and Sb–Sn/Ni systems have been investigated by means of wetting experiments. The wetting behaviour of two lead-free alloys, namely, Sb 2.5 Sn 97.5 and Sb 14.5 Sn 85.5 (at.%), in contact with Cu and Ni-substrates has been studied in view of possible applications as high-temperature solders in the electronics industry. The contact angle measurements on Cu and Ni plates were performed by using a sessile drop apparatus. The solder/substrate interface was characterised by the SEM-EDS analyses. -- Highlights: ► Sb–Sn alloys are used as high temperature lead-free solders. ► Sb–Sn alloys have good wetting properties on Cu and Ni substrates. ► Interfacial reactions and products are important for joint properties. ► Interfacial reactions/products data can be used to study the phase diagrams.
Thermodynamic Vent System for an On-Orbit Cryogenic Reaction Control Engine

Science.gov (United States)

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

2012-01-01

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

On microscopic simulations of systems with model chemical reactions

International Nuclear Information System (INIS)

Gorecki, J.; Gorecka, J.N.

1998-01-01

Large scale computer simulations of model chemical systems play the role of idealized experiments in which theories may be tested. In this paper we present two applications of microscopic simulations based on the reactive hard sphere model. We investigate the influence of internal fluctuations on an oscillating chemical system and observe how they modify the phase portrait of it. Another application, we consider, is concerned with the propagation of a chemical wave front associated with a thermally activated reaction. It is shown that the nonequilibrium effects increase the front velocity if compared with the velocity of the front generated by a nonactivated process characterized by the same rate constant. (author)
Drug reaction with eosinophilia and systemic symptoms syndrome in a patient taking phenytoin and levetiracetam: a case report

Directory of Open Access Journals (Sweden)

Hall David Jeffrey

2013-01-01

Full Text Available Abstract Introduction Drug reaction with eosinophilia and systemic symptoms syndrome is a potentially life-threatening hypersensitivity reaction with rash, fever, and internal organ involvement, often hepatitis, occurring most commonly two to eight weeks after initiation of a medication. The present case is an example of severe and potentially life-threatening hepatitis as a manifestation of drug reaction with eosinophilia and systemic symptoms syndrome. Case presentation We report a case of anti-epileptic-induced drug reaction with eosinophilia and systemic symptoms syndrome in an 18-year-old African-American man who presented with a five-day history of rash, periorbital and upper extremity edema, hepatitis and fever. Laboratory findings revealed an atypical lymphocytosis, eosinophilia, and elevated serum transaminases. No drug allergies were reported at the time of presentation, but phenytoin and levetiracetam therapy had been initiated five weeks prior to hospital admission for new-onset seizures. Both medications were discontinued on hospital admission, and after three days of high-dose corticosteroid therapy the patient experienced resolution of both his symptoms and laboratory markers of inflammation. Conclusion Given the significant mortality attributed to drug reaction with eosinophilia and systemic symptoms syndrome, medical personnel should be aware of the potential for this severe hypersensitivity reaction and should ensure close follow-up and offer anticipatory guidance when beginning any new medication, particularly anti-epileptic therapy. Early recognition of drug reaction with eosinophilia and systemic symptoms syndrome and initiation of appropriate therapy are imperative in limiting morbidity.
Thermochemical Heat Storage: from Reaction Storage Density to System Storage Density

NARCIS (Netherlands)

Jong, A.J. de; Vliet, L.D. van; Hoegaerts, C.L.G.; Roelands, C.P.M.; Cuypers, R.

2016-01-01

Long-term and compact storage of solar energy is crucial for the eventual transition to a 100% renewable energy economy. For this, thermochemical materials provide a promising solution. The compactness of a long-term storage system is determined by the thermochemical reaction, operating conditions,
The Paterno-Buchi reaction

DEFF Research Database (Denmark)

Brogaard, Rasmus Yding; Schalk, Oliver; Boguslavskiy, Andrey E.

2012-01-01

The Paternò-Büchi (PB) reaction between an excited carbonyl compound and an alkene has been widely studied, but so far little is known about the excited-state dynamics of the reaction. In this investigation, we used a compound in which a formyl and a vinyl group are attached to a [2.......2]paracyclophane in order to obtain a model system in pre-reactive conformation for the PB reaction. We studied the excited-state dynamics of the isolated molecule in a molecular beam using femtosecond time-resolved photoelectron spectroscopy and ab initio calculations. The results show that inter-system crossing...... within two picoseconds competes efficiently with the reaction in the singlet manifold. Thus, the PB reaction in this model system takes place in the triplet state on a time scale of nanoseconds. This result stresses the importance of triplet states in the excited-state pathway of the PB reaction...
Mode-locking in advection-reaction-diffusion systems: An invariant manifold perspective

Science.gov (United States)

Locke, Rory A.; Mahoney, John R.; Mitchell, Kevin A.

2018-01-01

Fronts propagating in two-dimensional advection-reaction-diffusion systems exhibit a rich topological structure. When the underlying fluid flow is periodic in space and time, the reaction front can lock to the driving frequency. We explain this mode-locking phenomenon using the so-called burning invariant manifolds (BIMs). In fact, the mode-locked profile is delineated by a BIM attached to a relative periodic orbit (RPO) of the front element dynamics. Changes in the type (and loss) of mode-locking can be understood in terms of local and global bifurcations of the RPOs and their BIMs. We illustrate these concepts numerically using a chain of alternating vortices in a channel geometry.
Methylene blue as a lignin surrogate in manganese peroxidase reaction systems.

Science.gov (United States)

Goby, Jeffrey D; Penner, Michael H; Lajoie, Curtis A; Kelly, Christine J

2017-11-15

Manganese peroxidase (MnP) is associated with lignin degradation and is thus relevant to lignocellulosic-utilization technologies. Technological applications require reaction mixture optimization. A surrogate substrate can facilitate this if its susceptibility to degradation is easily monitored and mirrors that of lignin. The dye methylene blue (MB) was evaluated in these respects as a surrogate substrate by testing its reactivity in reaction mixtures containing relevant redox mediators (dicarboxylic acids, fatty acids). Relative rates of MB degradation were compared to available literature reports of lignin degradation under similar conditions, and suggest that MB can be a useful lignin surrogate in MnP systems. Copyright © 2017 Elsevier Inc. All rights reserved.
Reaction networks as systems for resource allocation: a variational principle for their non-equilibrium steady states.

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Andrea De Martino

Full Text Available Within a fully microscopic setting, we derive a variational principle for the non-equilibrium steady states of chemical reaction networks, valid for time-scales over which chemical potentials can be taken to be slowly varying: at stationarity the system minimizes a global function of the reaction fluxes with the form of a Hopfield Hamiltonian with hebbian couplings, that is explicitly seen to correspond to the rate of decay of entropy production over time. Guided by this analogy, we show that reaction networks can be formally re-cast as systems of interacting reactions that optimize the use of the available compounds by competing for substrates, akin to agents competing for a limited resource in an optimal allocation problem. As an illustration, we analyze the scenario that emerges in two simple cases: that of toy (random reaction networks and that of a metabolic network model of the human red blood cell.
Interplay of break-up and transfer processes in reactions involving weakly-bound systems

Science.gov (United States)

Vitturi, Andrea; Moschini, Laura

2018-02-01

In this note we illustrate some applications of a simple model which has been devised to clarify the reaction mechanism and the interplay of different reaction channels (elastic, inelastic, transfer, break-up) in heavy-ion collisions. The model involves two potential wells moving in one dimension and few active particles; in spite of its simplicity, it is supposed to maintain the main features, the properties and the physics of the full three-dimensional case. Special attention is given to the role of continuum states in reactions involving weakly-bound systems, and different approximation schemes (as first-order or coupled-channels) as well as different continuum discretization procedures are tested. In the case of two active particles the reaction mechanism associated with two-particle transfer and the effect of pairing intearction are investigated. Work done in collaboration with Antonio Moro and Kouichi Hagino
Incomplete fusion reactions in 16O+159Tb system: Spin distribution measurements

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Sharma Vijay R.

2015-01-01

Full Text Available In order to explore the reaction modes on the basis of their entry state spin population, an experiment has been done by employing particle-γ coincidence technique carried out at the Inter University Accelerator Centre, New Delhi. The preliminary analysis conclusively demonstrates, spin distribution for some reaction products populated via complete and/or incomplete fusion of 16O with 159Tb system found to be distinctly different. Further, the existence of incomplete fusion at low bombarding energies indicates the possibility to populate high spin states.
Multiscale simulations of patchy particle systems combining Molecular Dynamics, Path Sampling and Green's Function Reaction Dynamics

Science.gov (United States)

Bolhuis, Peter

Important reaction-diffusion processes, such as biochemical networks in living cells, or self-assembling soft matter, span many orders in length and time scales. In these systems, the reactants' spatial dynamics at mesoscopic length and time scales of microns and seconds is coupled to the reactions between the molecules at microscopic length and time scales of nanometers and milliseconds. This wide range of length and time scales makes these systems notoriously difficult to simulate. While mean-field rate equations cannot describe such processes, the mesoscopic Green's Function Reaction Dynamics (GFRD) method enables efficient simulation at the particle level provided the microscopic dynamics can be integrated out. Yet, many processes exhibit non-trivial microscopic dynamics that can qualitatively change the macroscopic behavior, calling for an atomistic, microscopic description. The recently developed multiscale Molecular Dynamics Green's Function Reaction Dynamics (MD-GFRD) approach combines GFRD for simulating the system at the mesocopic scale where particles are far apart, with microscopic Molecular (or Brownian) Dynamics, for simulating the system at the microscopic scale where reactants are in close proximity. The association and dissociation of particles are treated with rare event path sampling techniques. I will illustrate the efficiency of this method for patchy particle systems. Replacing the microscopic regime with a Markov State Model avoids the microscopic regime completely. The MSM is then pre-computed using advanced path-sampling techniques such as multistate transition interface sampling. I illustrate this approach on patchy particle systems that show multiple modes of binding. MD-GFRD is generic, and can be used to efficiently simulate reaction-diffusion systems at the particle level, including the orientational dynamics, opening up the possibility for large-scale simulations of e.g. protein signaling networks.
Gas dynamic reaction process and system for laser chemistry

International Nuclear Information System (INIS)

Garbuny, M.

1979-01-01

A reaction system is disclosed wherein a moving, unidirectional stream of an activatable gaseous species is produced, the individual members of which have the forward components of their velocities at least 10 times greater than the lateral components of their velocities. The stream is irradiated with substantially monochromatic light having a frequency which activates at least some of the individual members of the species. The activated members can then be reacted with another stream or otherwise utilized
Reaction diffusion in chromium-zircaloy-2 system

International Nuclear Information System (INIS)

Xiang Wenxin; Ying Shihao

2001-01-01

Reaction diffusion in the chromium-zircaloy-2 diffusion couples is investigated in the temperature range of 1023 - 1123 K. Scanning electron microscope (SEM) and energy dispersive spectrum (EDS) were used to measure the thickness of the reaction layer and to determine the Zr, Fe and Cr concentration penetrate profile in reaction layer, respectively. The growth kinetics of reaction layer has been studied and the results show that the growth of intermetallic compound is controlled by the process of volume diffusion as the layer growth approximately obeys the parabolic law. Interdiffusion coefficients were calculated using Boltzmann-Matano-Heumann model. Calculated interdiffusion coefficients were compared with those obtained on the condition that Cr dissolves in Zr and merely forms dilute solid solution. The comparison indicates that Cr diffuses in dilute solid solution is five orders of magnitude faster than in Zr(Fe, Cr) 2 intermetallic compound
Optimization of ISSR-PCR reaction system and selection of primers in Bryum argenteum

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Ma Xiaoying

2017-02-01

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

Energy Technology Data Exchange (ETDEWEB)

Liang, Yunhong; Zhao, Qian; Li, Xiujuan; Zhang, Zhihui, E-mail: zhzh@jlu.edu.cn; Ren, Luquan

2016-09-15

The thermal explosion (TE) reaction behavior of Cu−Ti−C systems with different Ti and C particle sizes was investigated under air and Ar atmospheres. It was found that increasing the Ti and C particle sizes leads to higher ignition temperatures under both atmospheres and that the maximum combustion temperature decreases with increasing C particle size. The TE reaction is much easier to activate (i.e., it has a lower ignition temperature) in air because of the heat released from Ti oxidation and nitridation and Cu oxidation reactions on the Cu−Ti−C compact surface. TiC ceramic particles are successfully prepared in the bulk Cu−Ti−C compacts under both air and Ar atmospheres through a dissolution-diffusion-precipitation mechanism. Differential thermal and thermodynamic analyses show that the TE reaction ignition process in air is mainly controlled by the Ti particle size. - Highlights: • Variation of Ti and C particle sizes affects thermal reaction (TE) behaviors. • Ignition temperature under air is much lower than that under Ar atmosphere. • Heat of oxidation and nitridation reactions reduces ignition temperature under air.
Instability induced by cross-diffusion in reaction-diffusion systems

DEFF Research Database (Denmark)

Tian, Canrong; Lin, Zhigui; Pedersen, Michael

2010-01-01

In this paper the instability of the uniform equilibrium of a general strongly coupled reaction–diffusion is discussed. In unbounded domain and bounded domain the sufficient conditions for the instability are obtained respectively. The conclusion is applied to the ecosystem, it is shown that cros...... can induce the instability of an equilibrium which is stable for the kinetic system and for the self-diffusion–reaction system.......In this paper the instability of the uniform equilibrium of a general strongly coupled reaction–diffusion is discussed. In unbounded domain and bounded domain the sufficient conditions for the instability are obtained respectively. The conclusion is applied to the ecosystem, it is shown that cross-diffusion...
Global asymptotic stability of bistable traveling fronts in reaction-diffusion systems and their applications to biological models

International Nuclear Information System (INIS)

Wu Shiliang; Li Wantong

2009-01-01

This paper deals with the global asymptotic stability and uniqueness (up to translation) of bistable traveling fronts in a class of reaction-diffusion systems. The known results do not apply in solving these problems because the reaction terms do not satisfy the required monotone condition. To overcome the difficulty, a weak monotone condition is proposed for the reaction terms, which is called interval monotone condition. Under such a weak monotone condition, the existence and comparison theorem of solutions is first established for reaction-diffusion systems on R by appealing to the theory of abstract differential equations. The global asymptotic stability and uniqueness (up to translation) of bistable traveling fronts are then proved by the elementary super- and sub-solution comparison and squeezing methods for nonlinear evolution equations. Finally, these abstract results are applied to a two species competition-diffusion model and a system modeling man-environment-man epidemics.
Existence of weak solutions to a nonlinear reaction-diffusion system with singular sources

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Ida de Bonis

2017-09-01

Full Text Available We discuss the existence of a class of weak solutions to a nonlinear parabolic system of reaction-diffusion type endowed with singular production terms by reaction. The singularity is due to a potential occurrence of quenching localized to the domain boundary. The kind of quenching we have in mind is due to a twofold contribution: (i the choice of boundary conditions, modeling in our case the contact with an infinite reservoir filled with ready-to-react chemicals and (ii the use of a particular nonlinear, non-Lipschitz structure of the reaction kinetics. Our working techniques use fine energy estimates for approximating non-singular problems and uniform control on the set where singularities are localizing.
Nuclear-reaction studies via the observation of unbound outgoing systems

International Nuclear Information System (INIS)

Bice, A.N.

1982-01-01

The mechanisms involved in the production of fast α-particles in 12 C induced reactions have been investigated for the 12 C + 208 Pb system at bombarding energies of E( 12 C) = 132, 187 and 230 MeV. Absolute cross sections have been determined for the reactions 208 Pb ( 12 C, 8 Be (g.s.)), 208 Pb( 12 C, 8 Be (2.94 MeV)) and 208 Pb ( 12 C, 12 C* → α + 8 Be) by double and triple coincidence measurements of the sequential decay α-particles. Inclusive α-particle production cross sections were also measured at E ( 12 C) = 187 MeV for comparison. It is found that the simple inelastic scattering process ( 12 C, 12 C* → α + 8 Be) does not contribute significantly to the production of fast α-particles but that the production of 8 Be nuclei by projectile fragmentation is an important source of α-particles. At the highest bombarding energy investigated (19 MeV/A) it appears that the 12 C → 3α fragmentation reaction becomes more prominent at the expense of the 12 C → α + 8 Be fragmentation channel. It is concluded that projectile spectroscopic properties and/or final state interactions are important in fragmentation reactions for these bombarding energies. In a kinematically complete experiment the direct and the sequential breakup channels of 10 MeV/A 7 Li projectiles have been investigated with 12 C and 208 Pb targets. By appropriate arrangement of detector telescopes it was possible to define a kinematical window which allowed for the unambigious observation of both the direct (to the α-t continuum) and the sequential components of a heavy-ion projectile breakup reaction. A semiclassical Monte Carlo type projectile breakup calculation was constructed which qualitatively reproduced the measured α-t coincidence cross section as a function of the laboratory angle
High-intensity ultrasound production of Maillard reaction flavor compounds in a cysteine-xylose model system.

Science.gov (United States)

Ong, Olivia X H; Seow, Yi-Xin; Ong, Peter K C; Zhou, Weibiao

2015-09-01

Application of high intensity ultrasound has shown potential in the production of Maillard reaction odor-active flavor compounds in model systems. The impact of initial pH, sonication duration, and ultrasound intensity on the production of Maillard reaction products (MRPs) by ultrasound processing in a cysteine-xylose model system were evaluated using Response Surface Methodology (RSM) with a modified mathematical model. Generation of selected MRPs, 2-methylthiophene and tetramethyl pyrazine, was optimal at an initial pH of 6.00, accompanied with 78.1 min of processing at an ultrasound intensity of 19.8 W cm(-2). However, identification of volatiles using gas chromatography-mass spectrometry (GC/MS) revealed that ultrasound-assisted Maillard reactions generated fewer sulfur-containing volatile flavor compounds as compared to conventional heat treatment of the model system. Likely reasons for this difference in flavor profile include the expulsion of H2S due to ultrasonic degassing and inefficient transmission of ultrasonic energy. Copyright © 2015 Elsevier B.V. All rights reserved.
Fusion Power Demonstration III

International Nuclear Information System (INIS)

Lee, J.D.

1985-07-01

This is the third in the series of reports covering the Fusion Power Demonstration (FPD) design study. This volume considers the FPD-III configuration that incorporates an octopole end plug. As compared with the quadrupole end-plugged designs of FPD-I and FPD-II, this octopole configuration reduces the number of end cell magnets and shortens the minimum ignition length of the central cell. The end-cell plasma length is also reduced, which in turn reduces the size and cost of the end cell magnets and shielding. As a contiuation in the series of documents covering the FPD, this report does not stand alone as a design description of FPD-III. Design details of FPD-III subsystems that do not differ significantly from those of the FPD-II configuration are not duplicated in this report

Continuous optical measurement system of hemolysis during a photosensitization reaction using absorption spectrum

Science.gov (United States)

Hamada, R.; Ogawa, E.; Arai, T.

2018-02-01

To investigate hemolysis phenomena during a photosensitization reaction with the reaction condition continuously and simultaneously for a safety assessment of hemolysis side effect, we constructed an optical system to measure blood sample absorption spectrum during the reaction. Hemolysis degree might be under estimated in general evaluation methods because there is a constant oxygen pressure assumption in spite of oxygen depression take place. By investigating hemoglobin oxidation and oxygen desorption dynamics obtained from the contribution of the visible absorption spectrum and multiple regression analysis, both the hemolysis phenomena and its oxygen environment might be obtained with time. A 664 nm wavelength laser beam for the reaction excitation and 475-650 nm light beam for measuring the absorbance spectrum were arranged perpendicularly crossing. A quartz glass cuvette with 1×10 mm in dimensions for the spectrum measurement was located at this crossing point. A red blood cells suspension medium was arranged with low hematocrit containing 30 μg/ml talaporfin sodium. This medium was irradiated up to 40 J/cm2 . The met-hemoglobin, oxygenatedhemoglobin, and deoxygenated-hemoglobin concentrations were calculated by a multiple regression analysis from the measured spectra. We confirmed the met-hemoglobin concentration increased and oxygen saturation decreased with the irradiation time, which seems to indicate the hemolysis progression and oxygen consumption, respectively. By using our measuring system, the hemolysis progression seems to be obtained with oxygen environment information.
Spatiotemporal chaos of self-replicating spots in reaction-diffusion systems.

Science.gov (United States)

Wang, Hongli; Ouyang, Qi

2007-11-23

The statistical properties of self-replicating spots in the reaction-diffusion Gray-Scott model are analyzed. In the chaotic regime of the system, the spots that dominate the spatiotemporal chaos grow and divide in two or decay into the background randomly and continuously. The rates at which the spots are created and decay are observed to be linearly dependent on the number of spots in the system. We derive a probabilistic description of the spot dynamics based on the statistical independence of spots and thus propose a characterization of the spatiotemporal chaos dominated by replicating spots.
Optimised formation of blue Maillard reaction products of xylose and glycine model systems and associated antioxidant activity.

Science.gov (United States)

Yin, Zi; Sun, Qian; Zhang, Xi; Jing, Hao

2014-05-01

A blue colour can be formed in the xylose (Xyl) and glycine (Gly) Maillard reaction (MR) model system. However, there are fewer studies on the reaction conditions for the blue Maillard reaction products (MRPs). The objective of this study is to investigate characteristic colour formation and antioxidant activities in four different MR model systems and to determine the optimum reaction conditions for the blue colour formation in a Xyl-Gly MR model system, using the random centroid optimisation program. The blue colour with an absorbance peak at 630 nm appeared before browning in the Xyl-Gly MR model system, while no blue colour formation but only browning was observed in the xylose-alanine, xylose-aspartic acid and glucose-glycine MR model systems. The Xyl-Gly MR model system also showed higher antioxidant activity than the other three model systems. The optimum conditions for blue colour formation were as follows: xylose and glycine ratio 1:0.16 (M:M), 0.20 mol L⁻¹ NaHCO₃, 406.1 mL L⁻¹ ethanol, initial pH 8.63, 33.7°C for 22.06 h, which gave a much brighter blue colour and a higher peak at 630 nm. A characteristic blue colour could be formed in the Xyl-Gly MR model system and the optimum conditions for the blue colour formation were proposed and confirmed. © 2013 Society of Chemical Industry.
Atmospheric reaction systems as null-models to identify structural traces of evolution in metabolism.

Directory of Open Access Journals (Sweden)

Petter Holme

Full Text Available The metabolism is the motor behind the biological complexity of an organism. One problem of characterizing its large-scale structure is that it is hard to know what to compare it to. All chemical reaction systems are shaped by the same physics that gives molecules their stability and affinity to react. These fundamental factors cannot be captured by standard null-models based on randomization. The unique property of organismal metabolism is that it is controlled, to some extent, by an enzymatic machinery that is subject to evolution. In this paper, we explore the possibility that reaction systems of planetary atmospheres can serve as a null-model against which we can define metabolic structure and trace the influence of evolution. We find that the two types of data can be distinguished by their respective degree distributions. This is especially clear when looking at the degree distribution of the reaction network (of reaction connected to each other if they involve the same molecular species. For the Earth's atmospheric network and the human metabolic network, we look into more detail for an underlying explanation of this deviation. However, we cannot pinpoint a single cause of the difference, rather there are several concurrent factors. By examining quantities relating to the modular-functional organization of the metabolism, we confirm that metabolic networks have a more complex modular organization than the atmospheric networks, but not much more. We interpret the more variegated modular arrangement of metabolism as a trace of evolved functionality. On the other hand, it is quite remarkable how similar the structures of these two types of networks are, which emphasizes that the constraints from the chemical properties of the molecules has a larger influence in shaping the reaction system than does natural selection.
Modeling of the interplay between single-file diffusion and conversion reaction in mesoporous systems

Energy Technology Data Exchange (ETDEWEB)

Wang, Jing [Iowa State Univ., Ames, IA (United States)

2013-01-11

We analyze the spatiotemporal behavior of species concentrations in a diffusion-mediated conversion reaction which occurs at catalytic sites within linear pores of nanometer diameter. A strict single-file (no passing) constraint occurs in the diffusion within such narrow pores. Both transient and steady-state behavior is precisely characterized by kinetic Monte Carlo simulations of a spatially discrete lattice–gas model for this reaction–diffusion process considering various distributions of catalytic sites. Exact hierarchical master equations can also be developed for this model. Their analysis, after application of mean-field type truncation approximations, produces discrete reaction–diffusion type equations (mf-RDE). For slowly varying concentrations, we further develop coarse-grained continuum hydrodynamic reaction–diffusion equations (h-RDE) incorporating a precise treatment of single-file diffusion (SFD) in this multispecies system. Noting the shortcomings of mf-RDE and h-RDE, we then develop a generalized hydrodynamic (GH) formulation of appropriate gh-RDE which incorporates an unconventional description of chemical diffusion in mixed-component quasi-single-file systems based on a refined picture of tracer diffusion for finite-length pores. The gh-RDE elucidate the non-exponential decay of the steady-state reactant concentration into the pore and the non-mean-field scaling of the reactant penetration depth. Then an extended model of a catalytic conversion reaction within a functionalized nanoporous material is developed to assess the effect of varying the reaction product – pore interior interaction from attractive to repulsive. The analysis is performed utilizing the generalized hydrodynamic formulation of the reaction-diffusion equations which can reliably capture the complex interplay between reaction and restricted transport for both irreversible and reversible reactions.
Modeling of a Reaction-Distillation-Recycle System to Produce Dimethyl Ether through Methanol Dehydration

Science.gov (United States)

Muharam, Y.; Zulkarnain, L. M.; Wirya, A. S.

2018-03-01

The increase in the dimethyl ether yield through methanol dehydration due to a recycle integration to a reaction-distillation system was studied in this research. A one-dimensional phenomenological model of a methanol dehydration reactor and a shortcut model of distillation columns were used to achieve the aim. Simulation results show that 10.7 moles/s of dimethyl ether is produced in a reaction-distillation system with the reactor length being 4 m, the reactor inlet pressure being 18 atm, the reactor inlet temperature being 533 K, the reactor inlet velocity being 0.408 m/s, and the distillation pressure being 8 atm. The methanol conversion is 90% and the dimethyl ether yield is 48%. The integration of the recycle stream to the system increases the dimethyl ether yield by 8%.
Evaluation of urogenital Chlamydia trachomatis infections by cell culture and the polymerase chain reaction using a closed system

DEFF Research Database (Denmark)

Østergaard, Lars; Traulsen, J; Birkelund, Svend

1991-01-01

the two test systems were compared, the overall sensitivity of the polymerase chain reaction was 96% and the specificity 94% when compared to the cell culture technique. By use of a closed system for DNA extraction and sample transfer for the polymerase chain reaction, contamination of the samples......Two hundred and fifty-four specimens from males and females consulting a clinic for sexually transmitted diseases were analyzed for genital Chlamydia trachomatis infection. Each clinical sample was tested by the cell culture technique and the polymerase chain reaction using a closed system. When...... not detect Chlamydia trachomatis after sufficient antibiotic treatment of the chlamydial infections....
Evaluation of urogenital Chlamydia trachomatis infections by cell culture and the polymerase chain reaction using a closed system

DEFF Research Database (Denmark)

Østergaard, Lars; Traulsen, J; Birkelund, Svend

1993-01-01

the two test systems were compared, the overall sensitivity of the polymerase chain reaction was 96% and the specificity 94% when compared to the cell culture technique. By use of a closed system for DNA extraction and sample transfer for the polymerase chain reaction, contamination of the samples......Two hundred and fifty-four specimens from males and females consulting a clinic for sexually transmitted diseases were analyzed for genital Chlamydia trachomatis infection. Each clinical sample was tested by the cell culture technique and the polymerase chain reaction using a closed system. When...... not detect Chlamydia trachomatis after sufficient antibiotic treatment of the chlamydial infections....
Experimental and numerical analysis of the combustor for a cogeneration system based on the aluminum/water reaction

International Nuclear Information System (INIS)

Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio; Stefani, Matteo

2014-01-01

Highlights: • Aluminum reaction with water is studied as a technology for hydrogen production. • A test rig is developed for the analysis of aluminum/water reaction. • The system is the core component of a cogeneration plant for hydrogen/power production. • The interaction of liquid aluminum jet and water steam stream is investigated. • The main capabilities of the injection system are assessed. - Abstract: The paper focuses on the design of the experimental apparatus aimed at analyzing the performance of the combustion chamber of a cogeneration system based on the reaction of liquid aluminum and water steam. The cogeneration system exploits the heat released by the oxidation of aluminum with water for super-heating the vapor of a steam cycle and simultaneously producing hydrogen. The only by-product is alumina, which in a closed loop can be recycled back and transformed again into aluminum. Therefore, aluminum is used as an energy carrier to transport the energy from the alumina reduction plant to the location of the proposed system. The water is also used in a closed loop since the amount of water produced employing the hydrogen obtained by the proposed system corresponds to the oxidizing water for the Al/H 2 O reaction. This study investigates the combustor where the liquid aluminum–steam reaction takes place. In particular, the design of the combustion chamber and the interaction between the liquid aluminum jet and the water steam flow are evaluated using a numerical and an experimental approach. The test rig is specifically designed for the analysis of the liquid aluminum injection in a slightly super-heated steam stream. The first experiments are carried out to verify the correct behavior of the test rig. Thermography is employed to qualitatively assess the steam entrainment of the liquid aluminum jet. Finally, the experimental measurements are compared with the multi-dimension multi-phase flow simulations in order to estimate the influence of
The Diels-Alder reaction: A powerful tool for the design of drug delivery systems and biomaterials.

Science.gov (United States)

Gregoritza, Manuel; Brandl, Ferdinand P

2015-11-01

Click reactions have the potential to greatly facilitate the development of drug delivery systems and biomaterials. These reactions proceed under mild conditions, give high yields, and form only inoffensive by-products. The Diels-Alder cycloaddition is one of the click reactions that do not require any metal catalyst; it is one of the most useful reactions in synthetic organic chemistry and material design. Herein, we highlight possible applications of the Diels-Alder reaction in pharmaceutics and biomedical engineering. Particular focus is placed on the synthesis of polymers and dendrimers for drug delivery, the preparation of functionalized surfaces, bioconjugation techniques, and applications of the Diels-Alder reaction in nanotechnology. Moreover, applications of the reaction for the preparation of hydrogels for drug delivery and tissue engineering are reviewed. A general introduction to the Diels-Alder reaction is presented, along with a discussion of potential pitfalls and challenges. At the end of the article, we provide a set of tools that may facilitate the application of the Diels-Alder reaction to solve important pharmaceutical or biomedical problems. Copyright © 2015 Elsevier B.V. All rights reserved.
Development of the system for excitation function automatic measurement of nuclear reactions

International Nuclear Information System (INIS)

Sapozhnikov, A.B.

2004-01-01

Full text: The resonance nuclear reaction method is applied at the tandem accelerator UKP-2-1 to determinate films thickness and obtain light element depth distribution. The system for automatic measurement of the nuclear reaction excitation curve has been developed. It allowed to obtain an excitation function of nuclear reaction using continuous changing potential of the target with energy step of 6 eV. Saw-tooth voltage with amplitude up to 6 kV from the block of scanning beam is fed to a target. The amplitude is determined by constant voltage from the scanning beam block control. Nal(Tl) detector detects gamma quanta - the products of a nuclear reaction and transforms they in voltage impulses. The impulses through the amplifier income in the single-channel analyzer which forms impulses to start the analog-to-digital converter. The value of saw-tooth voltage corresponding to the moment of gamma quantum detection is read by the analog-to-digital converter, where it is transformed to digital code and transmitted to the computer. The computer program has been developed to control the process of accumulation of excitation function. The dependence a detected γ-quanta yield from a target potential is automatically plotted by the program. This dependence corresponds to the nuclear reaction excitation function. If scanning amplitude is not enough in order to scan need depth of a sample, an operator increases energy of the proton beam changing high voltage potential of the terminal up 3 keV and measures the nuclear reaction excitation function with the new energy. This procedure can be repeated some times. After that 'sewing' of excitation functions is carried out by the program under the hypothesis that nuclear reaction yield in last points be identical
Library of neutron reaction cross-sections in the ABBN-93 constant system

International Nuclear Information System (INIS)

Zabrodskaya, S.V.; Korchagina, Zh.A.; Koshcheev, V.N.; Nikolaev, M.N.; Tsibulya, A.M.

2001-01-01

The library of neutron reaction group cross-sections in the ABBN-93 constant set is described. The format used for data representation, the content and purpose of the sub-libraries and their practical application in the SCALE criticality safety estimation system are discussed. (author)
Mathematical Modeling and Dynamic Simulation of Metabolic Reaction Systems Using Metabolome Time Series Data

Directory of Open Access Journals (Sweden)

Kansuporn eSriyudthsak

2016-05-01

Full Text Available The high-throughput acquisition of metabolome data is greatly anticipated for the complete understanding of cellular metabolism in living organisms. A variety of analytical technologies have been developed to acquire large-scale metabolic profiles under different biological or environmental conditions. Time series data are useful for predicting the most likely metabolic pathways because they provide important information regarding the accumulation of metabolites, which implies causal relationships in the metabolic reaction network. Considerable effort has been undertaken to utilize these data for constructing a mathematical model merging system properties and quantitatively characterizing a whole metabolic system in toto. However, there are technical difficulties between benchmarking the provision and utilization of data. Although hundreds of metabolites can be measured, which provide information on the metabolic reaction system, simultaneous measurement of thousands of metabolites is still challenging. In addition, it is nontrivial to logically predict the dynamic behaviors of unmeasurable metabolite concentrations without sufficient information on the metabolic reaction network. Yet, consolidating the advantages of advancements in both metabolomics and mathematical modeling remain to be accomplished. This review outlines the conceptual basis of and recent advances in technologies in both the research fields. It also highlights the potential for constructing a large-scale mathematical model by estimating model parameters from time series metabolome data in order to comprehensively understand metabolism at the systems level.
Mathematical Modeling and Dynamic Simulation of Metabolic Reaction Systems Using Metabolome Time Series Data.

Science.gov (United States)

Sriyudthsak, Kansuporn; Shiraishi, Fumihide; Hirai, Masami Yokota

2016-01-01

The high-throughput acquisition of metabolome data is greatly anticipated for the complete understanding of cellular metabolism in living organisms. A variety of analytical technologies have been developed to acquire large-scale metabolic profiles under different biological or environmental conditions. Time series data are useful for predicting the most likely metabolic pathways because they provide important information regarding the accumulation of metabolites, which implies causal relationships in the metabolic reaction network. Considerable effort has been undertaken to utilize these data for constructing a mathematical model merging system properties and quantitatively characterizing a whole metabolic system in toto. However, there are technical difficulties between benchmarking the provision and utilization of data. Although, hundreds of metabolites can be measured, which provide information on the metabolic reaction system, simultaneous measurement of thousands of metabolites is still challenging. In addition, it is nontrivial to logically predict the dynamic behaviors of unmeasurable metabolite concentrations without sufficient information on the metabolic reaction network. Yet, consolidating the advantages of advancements in both metabolomics and mathematical modeling remain to be accomplished. This review outlines the conceptual basis of and recent advances in technologies in both the research fields. It also highlights the potential for constructing a large-scale mathematical model by estimating model parameters from time series metabolome data in order to comprehensively understand metabolism at the systems level.
Development of wide area reaction system for Reel-to-Reel TFA-MOD process

International Nuclear Information System (INIS)

Nomoto, Sukeharu; Aoki, Yuji; Teranishi, Ryo; Sato, Akihiro; Izumi, Teruo; Shiohara, Yuh

2006-01-01

The previously developed numerical simulation method for the TFA-MOD process, which calculated the YBCO growth kinetics, gas element diffusion and gas flow, was applied to study the suitable gas flow mode for a multi-turning Reel-to-Reel tape conveyance system of a long YBCO coated conductors. The high YBCO production rate with uniform J c distribution among tape lines is desired in the system. It was found by the numerical simulation for the vertical gas flow onto the tape surface to realize the above demands even in a wider reaction area. We developed a new wide area reaction tube for the Reel-to-Reel TFA-MOD process according to the numerically designed gas flow configuration. The demand for the new tube was confirmed to be satisfied by experiments
Characterization and reactions of a Salix extractive with a unique ring system

Science.gov (United States)

Lawrence Landucci; Sally Ralph; Kolby Hirth

2003-01-01

An extractive compound with a novel ring system was isolated from the wood of Salix alba and was given the name Salucci. The compound was primarily identified from the 1D NMR, 2D NMR and LC-MSMS data and the structure investigated through reactions and derivatizations.
Nanolithographic Fabrication and Heterogeneous Reaction Studies ofTwo-Dimensional Platinum Model Catalyst Systems

Energy Technology Data Exchange (ETDEWEB)

Contreras, Anthony Marshall [Univ. of California, Berkeley, CA (United States)

2006-05-20

In order to better understand the fundamental components that govern catalytic activity, two-dimensional model platinum nanocatalyst arrays have been designed and fabricated. These catalysts arrays are meant to model the interplay of the metal and support important to industrial heterogeneous catalytic reactions. Photolithography and sub-lithographic techniques such as electron beam lithography, size reduction lithography and nanoimprint lithography have been employed to create these platinum nanoarrays. Both in-situ and ex-situ surface science techniques and catalytic reaction measurements were used to correlate the structural parameters of the system to catalytic activity.
An Improved Protocol for the Aldehyde Olefination Reaction Using (bmim ( as Reaction Medium

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Vivek Srivastava

2013-01-01

Full Text Available [Ru(CODCl2]/CuCl2·2H2O/LiCl catalytic system works efficiently in ionic liquid media for aldehyde olefination reaction. It offers good yield and selectivity with the added advantage of 5 times recyclability for [Ru(CODCl2] /CuCl2·2H2O/LiCl catalytic system. We also successfully reduced the reaction time from 12 hours to 9 hours for the aldehyde olefination reaction.
Nuclear-reaction studies via the observation of unbound outgoing systems

Energy Technology Data Exchange (ETDEWEB)

Bice, A.N.

1982-01-01

The mechanisms involved in the production of fast ..cap alpha..-particles in /sup 12/C induced reactions have been investigated for the /sup 12/C + /sup 208/Pb system at bombarding energies of E(/sup 12/C) = 132, 187 and 230 MeV. Absolute cross sections have been determined for the reactions /sup 208/Pb (/sup 12/C, /sup 8/Be (g.s.)), /sup 208/Pb(/sup 12/C, /sup 8/Be (2.94 MeV)) and /sup 208/Pb (/sup 12/C, /sup 12/C* ..-->.. ..cap alpha.. + /sup 8/Be) by double and triple coincidence measurements of the sequential decay ..cap alpha..-particles. Inclusive ..cap alpha..-particle production cross sections were also measured at E (/sup 12/C) = 187 MeV for comparison. It is found that the simple inelastic scattering process (/sup 12/C, /sup 12/C* ..-->.. ..cap alpha.. + /sup 8/Be) does not contribute significantly to the production of fast ..cap alpha..-particles but that the production of /sup 8/Be nuclei by projectile fragmentation is an important source of ..cap alpha..-particles. At the highest bombarding energy investigated (19 MeV/A) it appears that the /sup 12/C ..-->.. 3..cap alpha.. fragmentation reaction becomes more prominent at the expense of the /sup 12/C ..-->.. ..cap alpha.. + /sup 8/Be fragmentation channel. It is concluded that projectile spectroscopic properties and/or final state interactions are important in fragmentation reactions for these bombarding energies. In a kinematically complete experiment the direct and the sequential breakup channels of 10 MeV/A /sup 7/Li projectiles have been investigated with /sup 12/C and /sup 208/Pb targets. By appropriate arrangement of detector telescopes it was possible to define a kinematical window which allowed for the unambigious observation of both the direct (to the ..cap alpha..-t continuum) and the sequential components of a heavy-ion projectile breakup reaction. A semiclassical Monte Carlo type projectile breakup calculation was constructed which qualitatively reproduced the measured ..cap alpha
Evolution of the Maillard Reaction in Glutamine or Arginine-Dextrinomaltose Model Systems

Directory of Open Access Journals (Sweden)

Silvia Pastoriza

2016-12-01

Full Text Available Enteral formulas are foods designed for medical uses to feed patients who are unable to eat normally. They are prepared by mixing proteins, amino acids, carbohydrates and fats and submitted to sterilization. During thermal treatment, the Maillard reaction takes place through the reaction of animo acids with reducing sugars. Thus, although glutamine and arginine are usually added to improve the nutritional value of enteral formulas, their final concentration may vary. Thus, in the present paper the early, intermediate, and advanced states of the Maillard reaction were studied in model systems by measuring loss of free amino acids through the decrease of fluorescence intensity with o-phtaldialdehyde (OPA, 5-Hydroximethylfurfural (HMF, furfural, glucosylisomaltol, fluorescence, and absorbance at 420 nm. The systems were prepared by mixing glutamine or arginine with dextrinomaltose (similar ingredients to those used in special enteral formula, and heated at 100 °C, 120 °C and 140 °C for 0 to 30 min. The recorded changes in the concentration of furanic compounds was only useful for longer heating times of high temperatures, while absorbance and fluorescence measurements were useful in all the assayed conditions. In addition, easiness and sensitivity of absorbance and fluorescence make them useful techniques that could be implemented as indicators for monitoring the manufacture of special enteral formulas. Glucosylisomaltol is a useful indicator to monitor the manufacture of glutamine-enriched enteral formulas.

Magnetic field effects on geminate reactions. Study of anthraquinone - hydrogen donors systems

International Nuclear Information System (INIS)

Vidal, Marie-Helene

1987-01-01

This study is devoted to magnetic field effects on chemical reactions which involve a radical pair with correlated spins (radical in a 'cage'). In the first part, the radical pair theory is described: mechanisms of singlet-triplet mixing, the different interactions inside the pair and a quantum mechanical treatment of the radical pair. The details of the experimental method (nanosecond laser flash photolysis) are reported in the second part. In the third part are shown experimental results obtained on Anthraquinone (AQ) - Hydrogen donors systems: - There is no magnetic field effect in homogeneous solution even at a high viscosity. The absorption spectra of the different reaction intermediates are obtained. - However a magnetic field effect is put forward when AQ is introduced in SDS micelles which are hydrogen donors. The absorption spectrum of the AQH · . semi-quinone radical in 'cage' is shown and a mechanism is proposed for its disappearance to generate the AQH-S and AQH 2 species. - The addition of 9, 10 Dihydroanthracene (DH2) inside the micelle near AQ induces an increase of the magnetic field effect by creation of (AQH · . - DH · . ) pairs which diffuse slowly. - Fixed radical pairs in a protein matrix were studied in reaction centers of photosynthetic bacteria: in that case, the half effect field is shifted to low fields when compared to the previously described systems. (author) [fr
Evolution of the Maillard Reaction in Glutamine or Arginine-Dextrinomaltose Model Systems.

Science.gov (United States)

Pastoriza, Silvia; Rufián-Henares, José Ángel; García-Villanova, Belén; Guerra-Hernández, Eduardo

2016-12-07

Enteral formulas are foods designed for medical uses to feed patients who are unable to eat normally. They are prepared by mixing proteins, amino acids, carbohydrates and fats and submitted to sterilization. During thermal treatment, the Maillard reaction takes place through the reaction of animo acids with reducing sugars. Thus, although glutamine and arginine are usually added to improve the nutritional value of enteral formulas, their final concentration may vary. Thus, in the present paper the early, intermediate, and advanced states of the Maillard reaction were studied in model systems by measuring loss of free amino acids through the decrease of fluorescence intensity with o -phtaldialdehyde (OPA), 5-Hydroximethylfurfural (HMF), furfural, glucosylisomaltol, fluorescence, and absorbance at 420 nm. The systems were prepared by mixing glutamine or arginine with dextrinomaltose (similar ingredients to those used in special enteral formula), and heated at 100 °C, 120 °C and 140 °C for 0 to 30 min. The recorded changes in the concentration of furanic compounds was only useful for longer heating times of high temperatures, while absorbance and fluorescence measurements were useful in all the assayed conditions. In addition, easiness and sensitivity of absorbance and fluorescence make them useful techniques that could be implemented as indicators for monitoring the manufacture of special enteral formulas. Glucosylisomaltol is a useful indicator to monitor the manufacture of glutamine-enriched enteral formulas.
Evolution of the Fusion Power Demonstration tandem mirror reactor configuration

International Nuclear Information System (INIS)

O'Toole, J.A.; Lousteau, D.C.

1985-01-01

This paper gives a presentation of the evolution of configurations proposed for tandem mirror Fusion Power Demonstration (FPD) machines. The FPD study was undertaken to scope the mission as well as the technical and design requirements of the next tandem mirror device. Three configurations, entitled FPD I, II, and III were studied. During this process new systems were conceived and integrated into the design, resulting in a significantly changed overall machine configuration. The machine can be divided into two areas. A new center cell configuration, minimizing magnetic field ripple and thus maximizing center cell fusion power, features a semicontinuous solenoid. A new end cell has evolved which maintains the required thermal barrier in a significantly reduced axial length. The reduced end cell effective length leads to a shorter central cell length being required to obtain minimum ignition conditions. Introduced is the concept of an electron mantle stabilized octopole arrangement. The engineering features of the new end cell and maintenance concepts developed are influenced to a great extent by the octopole-based design. The new ideas introduced during the FPD study have brought forth a new perspective of the size, design, and maintenance of tandem mirror reactors, making them more attractive as commercial power sources
Inflight performance of the Ulysses reaction control system

Science.gov (United States)

McGarry, Andrew; Berry, William; Parker, David

1997-01-01

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

International Nuclear Information System (INIS)

Peng Xiaoshi; Wang Feng; Tang Daorun; Liu Shenye; Huang Tianxuan; Liu Yonggang; Xu Tao; Chen Ming; Mei Yu

2011-01-01

Fusion reaction rate is an important parameter for measuring compression during the implosion in inertial confinement fusion experiment. We have developed a system for fusion reaction history measurement with high temporal resolution. The system is composed of plastic scintillator and nose cone, optical system and streak camera. We have applied this system on the SG-III prototype for fusion reaction rate measuring. For the first time, fusion reaction rate history have been measured for deuterium-tritium filled targets with neutrons yields about 10 10 . We have analyzed possible influence factor during fusion reaction rate measuring. It indicates that the instrument measures fusion reaction bang time at temporal resolutions as low as 30 ps.(authors)
A transformation theory of stochastic evolution in Red Moon methodology to time evolution of chemical reaction process in the full atomistic system.

Science.gov (United States)

Suzuki, Yuichi; Nagaoka, Masataka

2017-05-28

Atomistic information of a whole chemical reaction system, e.g., instantaneous microscopic molecular structures and orientations, offers important and deeper insight into clearly understanding unknown chemical phenomena. In accordance with the progress of a number of simultaneous chemical reactions, the Red Moon method (a hybrid Monte Carlo/molecular dynamics reaction method) is capable of simulating atomistically the chemical reaction process from an initial state to the final one of complex chemical reaction systems. In the present study, we have proposed a transformation theory to interpret the chemical reaction process of the Red Moon methodology as the time evolution process in harmony with the chemical kinetics. For the demonstration of the theory, we have chosen the gas reaction system in which the reversible second-order reaction H 2 + I 2 ⇌ 2HI occurs. First, the chemical reaction process was simulated from the initial configurational arrangement containing a number of H 2 and I 2 molecules, each at 300 K, 500 K, and 700 K. To reproduce the chemical equilibrium for the system, the collision frequencies for the reactions were taken into consideration in the theoretical treatment. As a result, the calculated equilibrium concentrations [H 2 ] eq and equilibrium constants K eq at all the temperatures were in good agreement with their corresponding experimental values. Further, we applied the theoretical treatment for the time transformation to the system and have shown that the calculated half-life τ's of [H 2 ] reproduce very well the analytical ones at all the temperatures. It is, therefore, concluded that the application of the present theoretical treatment with the Red Moon method makes it possible to analyze reasonably the time evolution of complex chemical reaction systems to chemical equilibrium at the atomistic level.
Transfer of energy from irradiated crystals to redox reactions: iodide/bromate and nitrite/bromate systems

International Nuclear Information System (INIS)

Arnikar, H.J.; Madhava Rao, B.S.; Bedekar, M.J.

1978-01-01

Earlier it had been shown by the authors that some of the redox reactions, which do not take place at room temperature can be induced by γ radiation. The yields are proportional to the dose. Results reported here show that instead of direct irradiation, the energy stored in irradiated crystals in the form of F and hole centres can be available, in part, in effecting redox reactions. The mechanism of such an energy transfer is discussed with reference to reactions in the I - +BrO 3 - and NO 2 - +BrO 3 - systems due to the addition of irradiated NaCl. (author)
Hypersensitivity Reactions from Excipients in Systemic Glucocorticoid Formulations

DEFF Research Database (Denmark)

Calogiuri, Gianfranco; Garvey, Lene H; Romita, Paolo

2016-01-01

Glucocorticoids are the most widely used drugs for the treatment of hypersensitivity, however these drugs themselves and the excipients contained in commercial corticosteroid formulations are able to induce severe immediate-type hypersensitivity reactions. Reactions involving excipients have been...
Asymptotic stability of a coupled advection-diffusion-reaction system arising in bioreactor processes

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Maria Crespo

2017-08-01

Full Text Available In this work, we present an asymptotic analysis of a coupled system of two advection-diffusion-reaction equations with Danckwerts boundary conditions, which models the interaction between a microbial population (e.g., bacteria, called biomass, and a diluted organic contaminant (e.g., nitrates, called substrate, in a continuous flow bioreactor. This system exhibits, under suitable conditions, two stable equilibrium states: one steady state in which the biomass becomes extinct and no reaction is produced, called washout, and another steady state, which corresponds to the partial elimination of the substrate. We use the linearization method to give sufficient conditions for the linear asymptotic stability of the two stable equilibrium configurations. Finally, we compare our asymptotic analysis with the usual asymptotic analysis associated to the continuous bioreactor when it is modeled with ordinary differential equations.
Chemiluminescence development after initiation of Maillard reaction in aqueous solutions of glycine and glucose: nonlinearity of the process and cooperative properties of the reaction system

Science.gov (United States)

Voeikov, Vladimir L.; Naletov, Vladimir I.

1998-06-01

Nonenzymatic glycation of free or peptide bound amino acids (Maillard reaction, MR) plays an important role in aging, diabetic complications and atherosclerosis. MR taking place at high temperatures is accompanied by chemiluminescence (CL). Here kinetics of CL development in MR proceeding in model systems at room temperature has been analyzed for the first time. Brief heating of glycine and D-glucose solutions to t greater than 93 degrees Celsius results in their browning and appearance of fluorescencent properties. Developed In solutions rapidly cooled down to 20 degrees Celsius a wave of CL. It reached maximum intensity around 40 min after the reaction mixture heating and cooling it down. CL intensity elevation was accompanied by certain decoloration of the solution. Appearance of light absorbing substances and development of CL depended critically upon the temperature of preincubation (greater than or equal to 93 degrees Celsius), initial pH (greater than or equal to 11,2), sample volume (greater than or equal to 0.5 ml) and reagents concentrations. Dependence of total counts accumulation on a system volume over the critical volume was non-monotonous. After reaching maximum values CL began to decline, though only small part of glucose and glycin had been consumed. Brief heating of such solutions to the critical temperature resulted in emergence of a new CL wave. This procedure could be repeated in one and the same reaction system for several times. Whole CL kinetic curve best fitted to lognormal distribution. Macrokinetic properties of the process are characteristic of chain reactions with delayed branching. Results imply also, that self-organization occurs in this system, and that the course of the process strongly depends upon boundary conditions and periodic interference in its course.
Corrosion potential detection method, potential characteristic simulation method for reaction rate and plant monitoring system using the same

International Nuclear Information System (INIS)

Sakai, Masanori; Onaka, Noriyuki; Takahashi, Tatsuya; Yamanaka, Hiroshi.

1995-01-01

In a calculation controlling device for a plant monitoring system, concentrations of materials concerning reaction materials in a certain state of a reaction process, and an actually measured value for the potential of a material in this state are substituted into a reaction rate equation obtained in accordance with a reaction process model. With such procedures, a relation between the reaction rate (current value) and the potential of the material can be obtained. A potential at which the reaction rates of an anode reaction and a cathode reaction contained in a corrosion reaction are made equal is determined by a numerical value calculation, based on an electrochemical hybrid potential logic by using the reaction rate equation, the reaction rate information relative to the corrosion reaction of the material and the concentration of the material concerning the corrosion reaction is obtained by a numerical value calculation. Then, simulation for the corrosion potential is enabled based on the handling corresponding to the actual reaction. Further, even for a portion which can not be measured actually, the corrosion potential can be recognized by simulation. (N.H.)
The rate coefficients of unimolecular reactions in the systems with power-law distributions

Science.gov (United States)

Yin, Cangtao; Guo, Ran; Du, Jiulin

2014-08-01

The rate coefficient formulae of unimolecular reactions are generalized to the systems with the power-law distributions based on nonextensive statistics, and the power-law rate coefficients are derived in the high and low pressure limits, respectively. The numerical analyses are made of the rate coefficients as functions of the ν-parameter, the threshold energy, the temperature and the number of degrees of freedom. We show that the new rate coefficients depend strongly on the ν-parameter different from one (thus from a Boltzmann-Gibbs distribution). Two unimolecular reactions, CH3CO→CH3+CO and CH3NC→CH3CN, are taken as application examples to calculate their power-law rate coefficients, which obtained with the ν-parameters slightly different from one can be exactly in agreement with all the experimental studies on these two reactions in the given temperature ranges.
Analysis of coupled mass transfer and sol-gel reaction in a two-phase system

NARCIS (Netherlands)

Castelijns, H.J.; Huinink, H.P.; Pel, L.; Zitha, P.L.J.

2006-01-01

The coupled mass transfer and chemical reactions of a gel-forming compound in a two-phase system were studied in detail. Tetra-methyl-ortho-silicate (TMOS) is often used as a precursor in sol-gel chemistry to produce silica gels in aqueous systems. TMOS can also be mixed with many hydrocarbons
Preliminary delineation of natural geochemical reactions, Snake River Plain aquifer system, Idaho National Engineering Laboratory and vicinity, Idaho

International Nuclear Information System (INIS)

Knobel, L.L.; Bartholomay, R.C.; Orr, B.R.

1997-05-01

The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, is conducting a study to determine the natural geochemistry of the Snake River Plain aquifer system at the Idaho National Engineering Laboratory (INEL), Idaho. As part of this study, a group of geochemical reactions that partially control the natural chemistry of ground water at the INEL were identified. Mineralogy of the aquifer matrix was determined using X-ray diffraction and thin-section analysis and theoretical stabilities of the minerals were used to identify potential solid-phase reactants and products of the reactions. The reactants and products that have an important contribution to the natural geochemistry include labradorite, olivine, pyroxene, smectite, calcite, ferric oxyhydroxide, and several silica phases. To further identify the reactions, analyses of 22 representative water samples from sites tapping the Snake River Plain aquifer system were used to determine the thermodynamic condition of the ground water relative to the minerals in the framework of the aquifer system. Principal reactions modifying the natural geochemical system include congruent dissolution of olivine, diopside, amorphous silica, and anhydrite; incongruent dissolution of labradorite with calcium montmorillonite as a residual product; precipitation of calcite and ferric oxyhydroxide; and oxidation of ferrous iron to ferric iron. Cation exchange reactions retard the downward movement of heavy, multivalent waste constituents where infiltration ponds are used for waste disposal
ReactionMap: an efficient atom-mapping algorithm for chemical reactions.

Science.gov (United States)

Fooshee, David; Andronico, Alessio; Baldi, Pierre

2013-11-25

Large databases of chemical reactions provide new data-mining opportunities and challenges. Key challenges result from the imperfect quality of the data and the fact that many of these reactions are not properly balanced or atom-mapped. Here, we describe ReactionMap, an efficient atom-mapping algorithm. Our approach uses a combination of maximum common chemical subgraph search and minimization of an assignment cost function derived empirically from training data. We use a set of over 259,000 balanced atom-mapped reactions from the SPRESI commercial database to train the system, and we validate it on random sets of 1000 and 17,996 reactions sampled from this pool. These large test sets represent a broad range of chemical reaction types, and ReactionMap correctly maps about 99% of the atoms and about 96% of the reactions, with a mean time per mapping of 2 s. Most correctly mapped reactions are mapped with high confidence. Mapping accuracy compares favorably with ChemAxon's AutoMapper, versions 5 and 6.1, and the DREAM Web tool. These approaches correctly map 60.7%, 86.5%, and 90.3% of the reactions, respectively, on the same data set. A ReactionMap server is available on the ChemDB Web portal at http://cdb.ics.uci.edu .
Global Controllability of Chemical Reactions

OpenAIRE

Drexler, Dániel András; Tóth, János

2015-01-01

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

International Nuclear Information System (INIS)

Kim, Yeong Geol

1990-10-01

This deals with chemical reaction engineering with thirteen chapters. The contents of this book are introduction on reaction engineering, chemical kinetics, thermodynamics and chemical reaction, abnormal reactor, non-isothermal reactor, nonideal reactor, catalysis in nonuniform system, diffusion and reaction in porosity catalyst, design catalyst heterogeneous reactor in solid bed, a high molecule polymerization, bio reaction engineering, reaction engineering in material process, control multi-variable reactor process using digital computer.
Clinical value of the major types of reactions of the body’s stress-regulating systems in ischemic stroke

Directory of Open Access Journals (Sweden)

Aleksandr Mikhailovich Dolgov

2013-01-01

Full Text Available The time course of changes in the parameters reflecting the status of different components of the body’s regulatory systems was studied in 125patients with hemispheric ischemic stroke via comprehensive evaluation of the hypothalamo-pituitary axes and some endocrine glands. There were three types of reactions of the body’s stress-regulating systems: 1 normergic; 2 hyperergic; 3 disergic, which characterized adaptive and disadaptive reactions in stroke. The changes in the nitroxydergic mechanisms of vascular tone regulation, which constrain the possible involvement of the vascular wall endothelium in the body’s adaptive reactions, progress as the condition becomes severe.
Investigation of (n,γ) reactions in fissionable fluids in a hybrid reactor system

International Nuclear Information System (INIS)

Guenay, Mehtap

2014-01-01

In this study, the effect of (n,γ) reactions in spent fuel-grade (SFG)-PuO 2 , UO 2 , NpO 2 and UCO contents was investigated in a designed hybrid reactor system. In this system, the molten salt-heavy metal mixtures 93 - 85 % Li 20 Sn 80 + 5 % SFG-PuO 2 and 2 - 10 % UO 2 , 93 - 85 % Li 20 Sn 80 + 5 % SFG-PuO 2 and 2 - 10 % NpO 2 , 93 - 85 % Li 20 Sn 80 + 5 % SFG-PuO 2 and 2 - 10 % UCO were used as fluids. Beryllium (Be) is used as neutron multiplier by (n,2n) reactions. Thence, a Be zone with a width of 3 cm was used in order to contribute on fissile fuel breeding between the liquid first wall and blanket. (n,γ) reactions were calculated in the liquid first wall, blanket and shield zones, which SFG-PuO 2 , UO 2 , NpO 2 and UCO contents. 9Cr2WVTa ferritic steel with the width of 4 cm was used as the structural material. Three-dimensional nucleonic calculations were performed using the most recent version MCNPX-2.7.0 the Monte Carlo code and nuclear data library ENDF/B-VII.0. (orig.)
Non-Toxic Orbiter Maneuvering System (OMS) and Reaction Control System

Science.gov (United States)

Hurlbert, Eric A.; Nicholson, Leonard S. (Technical Monitor)

1999-01-01

NASA is pursuing the technology and advanced development of a non-toxic (NT) orbital maneuvering system (OMS) and reaction control system (RCS) for shuttle upgrades, RLV, and reusable first stages. The primary objectives of the shuttle upgrades program are improved safety, improved reliability, reduced operations time and cost, improved performance or capabilities, and commonality with future space exploration needs. Non-Toxic OMS/RCS offers advantages in each of these categories. A non-toxic OMS/RCS eliminates the ground hazards and the flight safety hazards of the toxic and corrosive propellants. The cost savings for ground operations are over $24M per year for 7 flights, and the savings increase with increasing flight rate up to $44M per year. The OMS/RCS serial processing time is reduced from 65 days to 13 days. The payload capability can be increased up to 5100 Ibms. The non-toxic OMS/RCS also provides improved space station reboost capability up to 20 nautical miles over the current toxic system of 14 nautical miles. A NT OMS/RCS represents a clear advancement in the SOA over MMH/NTO. Liquid oxygen and ethanol are clean burning, high-density propellants that provide a high degree of commonality with other spacecraft subsystems including life support, power, and thermal control, and with future human exploration and development of space missions. The simple and reliable pressure-fed design uses sub-cooled liquid oxygen at 250 to 350 psia, which allows a propellant to remain cryogenic for longer periods of time. The key technologies are thermal insulation and conditioning techniques are used to maintain the sub-cooling. Phase I successfully defined the system architecture, designed an integrated OMS/RCS propellant tank, analyzed the feed system, built and tested the 870 lbf RCS thrusters, and tested the 6000 lbf OMS engine. Phase 11 is currently being planned for the development and test of full-scale prototype of the system in 1999 and 2000

HELP: a model for evaluating the feasibility of using various chemical reaction systems as electronic lasers

Energy Technology Data Exchange (ETDEWEB)

Herbelin, J M; Cohen, N

1975-09-01

An analytical model for estimating the minimum requirements of a chemically pumped electronic laser is developed. From a knowledge of the basic spectroscopic and thermodynamic properties of a particular reaction, the model can quickly classify the system in accordance with the feasibility of generating stimulated emission at different possible wavelengths. Sample calculations of the reactions of barium atoms with nitrous oxide and nitrogen dioxide indicate that the model is sufficiently sensitive to distinguish between very similar systems and, therefore, should be useful in providing classification criteria in the search for a chemically pumped electronic laser.
Employee reactions to the use of management control systems in hospitals: motivation vs. threat

Directory of Open Access Journals (Sweden)

Ernesto Lopez-Valeiras

2018-03-01

Conclusions: The results obtained contribute to creating specific knowledge on the reactions of employees to the use of management control systems in hospitals. This information may be important in adapting management control systems to the characteristics of the hospital and its employees, which may in turn contribute to reducing dysfunctional worker behavior.
Performance and cost of energy transport and storage systems for dish applications using reversible chemical reactions

Science.gov (United States)

Schredder, J. M.; Fujita, T.

1984-01-01

The use of reversible chemical reactions for energy transport and storage for parabolic dish networks is considered. Performance and cost characteristics are estimated for systems using three reactions (sulfur-trioxide decomposition, steam reforming of methane, and carbon-dioxide reforming of methane). Systems are considered with and without storage, and in several energy-delivery configurations that give different profiles of energy delivered versus temperature. Cost estimates are derived assuming the use of metal components and of advanced ceramics. (The latter reduces the costs by three- to five-fold). The process that led to the selection of the three reactions is described, and the effects of varying temperatures, pressures, and heat exchanger sizes are addressed. A state-of-the-art survey was performed as part of this study. As a result of this survey, it appears that formidable technical risks exist for any attempt to implement the systems analyzed in this study, especially in the area of reactor design and performance. The behavior of all components and complete systems under thermal energy transients is very poorly understood. This study indicates that thermochemical storage systems that store reactants as liquids have efficiencies below 60%, which is in agreement with the findings of earlier investigators.
Kinetics and mechanism of oxygen reduction reaction at CoPd system synthesized on XC72

International Nuclear Information System (INIS)

Tarasevich, M.R.; Chalykh, A.E.; Bogdanovskaya, V.A.; Kuznetsova, L.N.; Kapustina, N.A.; Efremov, B.N.; Ehrenburg, M.R.; Reznikova, L.A.

2006-01-01

Studies are presented of the kinetics and mechanism of oxygen electroreduction reaction on CoPd catalysts synthesized on carbon black XC72. As shown both in model conditions and in the tests within the cathodes of hydrogen-oxygen fuel cells with proton conducting electrolyte, CoPd/C system features a higher activity, as compared to Co/C. The highest activity in the oxygen reduction reaction is demonstrated by the catalysts with the Pd:Co atomic ratio being 7:3 and 4:1. The structural studies (XPS and XRD, and also the data of CO desorption measurements) evidence the CoPd alloy formation, which is reflected in the negative shift of the bonding energy maximum as compared to Pd/C and in the appearance of the additional CO desorption maximums on the voltammograms. It is found by means of structural research that CoPd alloy is formed in the course of the catalyst synthesis which features a higher catalytic activity of the binary systems. Besides, CoPd/C catalyst is more stable in respect to corrosion than Pd supported on carbon black. The measurements on the rotating disc electrode and rotating ring-disc electrode evidence that CoPd/C system provides the predominant oxygen reduction to water in the practically important range of potentials (E > 0.7 V). The proximity of kinetic parameters of the oxygen reduction reaction on CoPd/C and Pt/C catalysts points to the similar reaction mechanism. The slow step of the reaction is the addition of the first electron to the adsorbed and previously protonated O 2 molecule. The assumptions are offered about the reasons causing the higher activity and selectivity of the binary catalyst towards oxygen reduction to water, as compared to Co/C. The studies of the most active catalysts within the fuel cell cathodes are performed
Remodelling of cellular excitation (reaction) and intercellular coupling (diffusion) by chronic atrial fibrillation represented by a reaction-diffusion system

Science.gov (United States)

Zhang, Henggui; Garratt, Clifford J.; Kharche, Sanjay; Holden, Arun V.

2009-06-01

Human atrial tissue is an excitable system, in which myocytes are excitable elements, and cell-to-cell electrotonic interactions are via diffusive interactions of cell membrane potentials. We developed a family of excitable system models for human atrium at cellular, tissue and anatomical levels for both normal and chronic atrial fibrillation (AF) conditions. The effects of AF-induced remodelling of cell membrane ionic channels (reaction kinetics) and intercellular gap junctional coupling (diffusion) on atrial excitability, conduction of excitation waves and dynamics of re-entrant excitation waves are quantified. Both ionic channel and gap junctional coupling remodelling have rate dependent effects on atrial propagation. Membrane channel conductance remodelling allows the propagation of activity at higher rates than those sustained in normal tissue or in tissue with gap junctional remodelling alone. Membrane channel conductance remodelling is essential for the propagation of activity at rates higher than 300/min as seen in AF. Spatially heterogeneous gap junction coupling remodelling increased the risk of conduction block, an essential factor for the genesis of re-entry. In 2D and 3D anatomical models, the dynamical behaviours of re-entrant excitation waves are also altered by membrane channel modelling. This study provides insights to understand the pro-arrhythmic effects of AF-induced reaction and diffusion remodelling in atrial tissue.
Nonlinear waves in reaction-diffusion systems: The effect of transport memory

International Nuclear Information System (INIS)

Manne, K. K.; Hurd, A. J.; Kenkre, V. M.

2000-01-01

Motivated by the problem of determining stress distributions in granular materials, we study the effect of finite transport correlation times on the propagation of nonlinear wave fronts in reaction-diffusion systems. We obtain results such as the possibility of spatial oscillations in the wave-front shape for certain values of the system parameters and high enough wave-front speeds. We also generalize earlier known results concerning the minimum wave-front speed and shape-speed relationships stemming from the finiteness of the correlation times. Analytic investigations are made possible by a piecewise linear representation of the nonlinearity. (c) 2000 The American Physical Society
Nonlinear waves in reaction-diffusion systems: The effect of transport memory

Science.gov (United States)

Manne, K. K.; Hurd, A. J.; Kenkre, V. M.

2000-04-01

Motivated by the problem of determining stress distributions in granular materials, we study the effect of finite transport correlation times on the propagation of nonlinear wave fronts in reaction-diffusion systems. We obtain results such as the possibility of spatial oscillations in the wave-front shape for certain values of the system parameters and high enough wave-front speeds. We also generalize earlier known results concerning the minimum wave-front speed and shape-speed relationships stemming from the finiteness of the correlation times. Analytic investigations are made possible by a piecewise linear representation of the nonlinearity.
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.
The browning value changes and spectral analysis on the Maillard reaction product from glucose and methionine model system

Science.gov (United States)

Al-Baarri, A. N.; Legowo, A. M.; Widayat

2018-01-01

D-glucose has been understood to provide the various effect on the reactivity in Maillard reaction resulting in the changes in physical performance of food product. Therefore this research was done to analyse physical appearance of Maillard reaction product made of D-glucose and methionine as a model system. The changes in browning value and spectral analysis model system were determined. The glucose-methionine model system was produced through the heating treatment at 50°C and RH 70% for 24 hours. The data were collected for every three hour using spectrophotometer. As result, browning value was elevated with the increase of heating time and remarkably high if compare to the D-glucose only. Furthermore, the spectral analysis showed that methionine turned the pattern of peak appearance. As conclusion, methionine raised the browning value and changed the pattern of spectral analysis in Maillard reaction model system.
Thermodynamics of random reaction networks.

Science.gov (United States)

Fischer, Jakob; Kleidon, Axel; Dittrich, Peter

2015-01-01

Reaction networks are useful for analyzing reaction systems occurring in chemistry, systems biology, or Earth system science. Despite the importance of thermodynamic disequilibrium for many of those systems, the general thermodynamic properties of reaction networks are poorly understood. To circumvent the problem of sparse thermodynamic data, we generate artificial reaction networks and investigate their non-equilibrium steady state for various boundary fluxes. We generate linear and nonlinear networks using four different complex network models (Erdős-Rényi, Barabási-Albert, Watts-Strogatz, Pan-Sinha) and compare their topological properties with real reaction networks. For similar boundary conditions the steady state flow through the linear networks is about one order of magnitude higher than the flow through comparable nonlinear networks. In all networks, the flow decreases with the distance between the inflow and outflow boundary species, with Watts-Strogatz networks showing a significantly smaller slope compared to the three other network types. The distribution of entropy production of the individual reactions inside the network follows a power law in the intermediate region with an exponent of circa -1.5 for linear and -1.66 for nonlinear networks. An elevated entropy production rate is found in reactions associated with weakly connected species. This effect is stronger in nonlinear networks than in the linear ones. Increasing the flow through the nonlinear networks also increases the number of cycles and leads to a narrower distribution of chemical potentials. We conclude that the relation between distribution of dissipation, network topology and strength of disequilibrium is nontrivial and can be studied systematically by artificial reaction networks.
Exclusive Measurements of Breakup Reactions in the 7Li+144Sm System

International Nuclear Information System (INIS)

Heimann, D. Martinez; Pacheco, A. J.; Arazi, A.; Figueira, J. M.; Negri, A.; Capurro, O. A.; Carnelli, P.; Fimiani, L.; Grinberg, P.; Marti, G. V.; Testoni, J. E.; Monteiro, D. S.; Niello, J. O. Fernandez; Marta, H. D.

2009-01-01

Breakup reactions induced by a 30 MeV 7 Li beam on a 144 Sm target were measured through the coincident detection of the light particles emitted in the reaction plane. The emphasis of the measurements and data analysis was placed in the complete characterization of the reaction by means of the identification of the breakup products and the experimental extraction of the physically relevant magnitudes. The coincident yield of the emitted light particles was compared with the results of kinematical calculations that were done assuming different distributions for these magnitudes and taking into account the geometric response of the detection system. The results of this comparison indicate in all cases a clear dominance of a process compatible with the breakup of 6 Li through the 3 + resonant state at 2.186 MeV following one-neutron transfer from the projectile to the target, over the breakup of the projectile itself. Relative cross sections as a function of the emission angle of the 6 Li and the in-plane anisotropy of the subsequent emission of breakup products were extracted from the data.
Solid-state interfacial reaction in molybdenum-carbide systems at high temperature-pressure, and its application to bonding technique

International Nuclear Information System (INIS)

Horiguchi, Akihiro; Suganuma, Katsuaki; Miyamoto, Yoshinari; Koizumi, Mitsue; Shimada, Masahiko.

1986-01-01

Diffusion couples of molybdenum with several carbides, i.e. SiC, B 4 C, TiC, ZrC, HfC and TaC, were heated at various temperatures ranging from 1500 to 1840 deg C under high pressures of 3 GPa and 100 MPa for up to 4 hr. The couples were then examined for the composition of reaction products, the growth rate of reaction layers, interfacial structures, and tensile strength. In case of Mo-transition metal carbides, Mo 2 C layer was mainly formed, so that the carbides, which had supplied carbon, resulted in having the nonstoichiometric composition near the interface. The activation energy for the growth of Mo 2 C layer in Mo-TiC system was 332 kJ/mol, and that in Mo-TaC system was 366 kJ/mol. In Mo-SiC system, Mo 2 C layer, the mixed phase of Mo 2 C and Mo 5 Si 3 , and Mo 5 Si 3 C layer were formed in order from the Mo side. In Mo-B 4 C system, the mixed phase of Mo 2 B and MoB, and Mo 2 BC layer appeared. The decomposed graphite from B 4 C was also observed between B 4 C and Mo 2 BC phase. The activation energy for the growth of total reaction layer in Mo-SiC system was 531 kJ/mol, and that in Mo-B 4 C system was 183 kJ/mol. It can be said that the growth of reaction layers is controlled by diffusion. The orientation of crystals was observed in all reaction products except for Mo 2 BC phase in Mo-B 4 C system and (Mo, Ta) 2 C phase in Mo-TaC system. In HIPed couples, the magnitude of tensile strength was dependent on the difference in thermal expansion coefficient between Mo and carbides. HIPed Mo-TaC couple had the best weldability among the systems examined in the present investigation. (author)
Systemic Immediate Hypersensitive Reactions after Treatment with Sweet Bee Venom: A Case Report

Directory of Open Access Journals (Sweden)

NaYoung Jo

2015-12-01

Full Text Available Objectives: A previous study showed that bee venom (BV could cause anaphylaxis or other hypersensitivity reactions. Although hypersensitivity reactions due to sweet bee venom (SBV have been reported, SBV has been reported to be associated with significantly reduced sensitization compared to BV. Although no systemic immediate hypersensitive response accompanied by abnormal vital signs has been reported with respect to SBV, we report a systemic immediate hypersensitive response that we experienced while trying to use SBV clinically. Methods: The patient had undergone BV treatment several times at other Oriental medicine clinics and had experienced no adverse reactions. She came to acupuncture & moxibustion department at Semyung university hospital of Oriental medicine (Je-cheon, Korea complaining of facial hypoesthesia and was treated using SBV injections, her first SBV treatment. SBV, 0.05 cc, was injected at each of 8 acupoints, for a total of 0.40 cc: Jichang (ST4, Daeyeong (ST5, Hyeopgeo (ST6, Hagwan (ST7, Yepung (TE17, Imun (TE21, Cheonghoe (GB2, and Gwallyeo (SI18. Results: The patient showed systemic immediate hypersensitive reactions. The main symptoms were abdominal pain, nausea and perspiration, but common symptoms associated with hypersensitivity, such as edema, were mild. Abdominal pain was the most long-lasting symptom and was accompanied by nausea. Her body temperature decreased due to sweating. Her diastolic blood pressure could not be measured on three occasions. She remained alert, though the symptoms persisted. The following treatments were conducted in sequence; intramuscular epinephrine, 1 mg/mL, injection, intramuscular dexamethasone, 5 mg/mL, injection, intramuscular buscopan, 20 mg/mL, injection, oxygen (O2 inhalation therapy, 1 L/minutes, via a nasal prong, and intravascular injection of normal saline, 1 L. After 12 hours of treatment, the symptoms had completely disappeared. Conclusion: This case shows that the use of SBV
Mathematical analysis and numerical simulation of patterns in fractional and classical reaction-diffusion systems

International Nuclear Information System (INIS)

Owolabi, Kolade M.

2016-01-01

The aim of this paper is to examine pattern formation in the sub— and super-diffusive scenarios and compare it with that of classical or standard diffusive processes in two-component fractional reaction-diffusion systems that modeled a predator-prey dynamics. The focus of the work concentrates on the use of two separate mathematical techniques, we formulate a Fourier spectral discretization method as an efficient alternative technique to solve fractional reaction-diffusion problems in higher-dimensional space, and later advance the resulting systems of ODEs in time with the adaptive exponential time-differencing solver. Obviously, the fractional Fourier approach is able to achieve spectral convergence up to machine precision regardless of the fractional order α, owing to the fact that our approach is able to give full diagonal representation of the fractional operator. The complexity of the dynamics in this system is theoretically discussed and graphically displayed with some examples and numerical simulations in one, two and three dimensions.
Phase space conduits for reaction in multidimensional systems : HCN isomerization in three dimensions

NARCIS (Netherlands)

Waalkens, Holger; Burbanks, Andrew; Wiggins, Stephen

2004-01-01

The three-dimensional hydrogen cyanide/isocyanide isomerization problem is taken as an example to present a general theory for computing the phase space structures which govern classical reaction dynamics in systems with an arbitrary (finite) number of degrees of freedom. The theory, which is
Uranium/water vapor reactions in gaseous atmospheres

International Nuclear Information System (INIS)

Jackson, R.L.; Condon, J.B.; Steckel, L.M.

1977-07-01

Experiments have been performed to determine the effect of varying humidities, gaseous atmospheres, and temperatures on the uranium/water vapor reaction. A balance, which allowed continuous in-system weighings, was used to determine the rates of the uranium/water vapor reactions at water vapor pressures of 383, 1586, and 2853 Pa and at temperatures of 80, 100, and 150 0 C in atmospheres of hydrogen, argon, or argon/oxygen mixtures. Based on rate data, the reactions were characterized as hydriding or nonhydriding. Hydriding reactions were found to be preferred in moist hydrogen systems at the higher temperatures and the lower humidities. The presence of hydrogen in hydriding systems was found to initially inhibit the reaction, but causes an acceleration of the rate in the final stages. In general, reaction rates of hydriding systems approached the hydriding rates calculated and observed in dry hydrogen. Hydriding and nonhydriding reaction rates showed a positive correlation to temperature and water vapor pressure. Final reaction rates in moist argon/oxygen mixtures of 1.93, 4.57, and 9.08 mole percent oxygen were greater than the rates observed in moist hydrogen or argon. Final reaction rates were negatively correlated to the oxygen concentration
Kinetics of ion/molecule reactions in Xe++acteone system

International Nuclear Information System (INIS)

Vinogradov, P.S.; Misharin, A.S.

2002-01-01

A reaction of Xe+ ion with acetone and subsequent transformations of the product ions at a buffer gas pressure (He) of 1.1 Torr were studied by the flow reactor technique mass spectrometry. A kinetic scheme describing the evolution of the ionic composition has been determined. The rate constants of the key reactions involved in the scheme have been evaluated. A channel of the production of acetone cation in A state in a charge transfer reaction was observed. A production of slowly reacting isomer of the acetone cation in secondary reactions was detected. Its product in the reaction with acetone is the 'nonprotonated dimer'. The kinetics of the production of ternary ions - ( CH 3 CO + CH 3 COCH 3 )(m/e=101), CH 3 COCH 3 H + (m/e=59) as well as the production of ions of the fourth generation ( CH 3 CO + (CH 3 COCH 3 ) 2 ) (m/e=159) and (CH 3 COCH 3 ) 2 H + was observed. CH 3 CO + ion (m/e=43) was found as the main reaction product. The main pathways scheme of ionic transformations is shown. (nevyjel)
The Norwegian National Reporting System and Register of Severe Allergic Reactions to Food

Directory of Open Access Journals (Sweden)

Martinus Løvik

2009-10-01

Full Text Available The Norwegian National Reporting System and Register of Severe Allergic Reactions to Food, or the Food Allergy Register, is a nation-wide, government-funded permanent reporting and registration system for severe allergic reactions to food. The Food Allergy Register collects information based on a one-page reporting form, serum samples for specific IgE analysis, and food samples for food allergen analysis. Reporting physicians receive in return an extensive commentary on the reported case and the relevant allergies, and results of the specific IgE analysis and food allergen analysis.The Food Allergy Register has, after being active for a little more than four years, given valuable information about several important aspects of food allergy in Norway. The Food Allergy Register has revealed food safety problems in relation to allergy that probably could be discovered only with the help of a systematic, nation-wide registration of cases. The reactions of peanut allergic individuals to lupine flour in bakery products is an example of how the Food Allergy Register is able to reveal potentially serious problems that would otherwise probably have gone unnoticed and certainly unexplained. The amount and the value of the information from the Food Allergy Register are increasing as new reports of more cases are added. The typical Norwegian patient with a severe allergic reaction to food appears to be a young adult, female rather than male. The offending meal is consumed at a restaurant or fast-food stand or in a private party away from home, and peanuts, nuts and shellfish are among the most common offending foods, while fish allergy appears to be rather rare.
An Immunosensing System Using Stilbene Glycoside as a Fluorogenic Substrate for an Enzymatic Reaction Model

Directory of Open Access Journals (Sweden)

Ya-Fei Tan

2008-09-01

Full Text Available A natural product, stilbene glycoside (2,3,5,4Ã¢Â€Â™-tetrahydroxydiphenylethylene-2-O-glucoside, TBG, has been evaluated for the first time as a potential substrate for horseradish peroxidase (HRP-catalyzed fluorogenic reactions. The properties of TBG as a fluorogenic substrate for HRP and its application in a fluorometric enzyme-linked immunosensing system were compared with commercially available substrates such as p-hydroxyphenylpropionic acid (pHPPA, chavicol and Amplex red using Brucella melitensis antibody (BrAb as a model analyte. The immunosensing body based on HRP-BrAb was constructed by dispersing graphite, BrAg and paraffin wax at room temperature. In a competitive immunoassay procedure, the BrAb competed with HRP-BrAb to react with the immobilized BrAg. In the enzymatic reaction, the binding HRP-BrAb on the sensing body surface can catalyze the polymerization reaction of TBG by H2O2 forming fluorescent dimers and causing an increase in fluorescence intensity. TBG showed comparable ability for HRP detection and its enzyme-linked immunosensing reaction system, in a linear detection ranging of 3.5Ã‚Â´10-8~7.6Ã‚Â´10-6g/L and with a detection limit of 1.7Ã‚Â´10-9 g/L. The immobilized biocomposite surface could be regenerated with excellent reproducibility (RSD=3.8% by simply polishing with an alumina paper. The proposed immunosensing system has been used to determine the BrAb in rabbit serum samples with satisfactory results.
Characterization of ionic liquid‐based biocatalytic two‐phase reaction system for production of biodiesel

DEFF Research Database (Denmark)

Prabhavathi Devi, Bethala Lakshmi Anu; Guo, Zheng; Xu, Xuebing

2011-01-01

The property of a variety of ionic liquids (ILs) as reaction media was evaluated for the production of biodiesel by enzymatic methanolysis of rapeseed oil. The IL Ammoeng 102, containing tetraaminum cation with C18 acyl and oligoethyleneglycol units, was found to be capable of forming oil....../IL biphasic reaction system by mixing with substrates, which is highly effective for the production of biodiesel with more than 98% biodiesel yield and nearly 100% conversion of oil. Conductor‐like screening model for real solvent (COSMO‐RS) in silico prediction of substrate solubility and simulation...... of partition coefficient change vs. reaction evolution indicated that the amphiphilic property of Ammoeng 102 might be responsible for creating efficient interaction of immiscible substrates; while big difference of partition coefficients of generated biodiesel and glycerol between the two phases suggests...

Convergence to Equilibrium in Energy-Reaction-Diffusion Systems Using Vector-Valued Functional Inequalities

Science.gov (United States)

Mielke, Alexander; Mittnenzweig, Markus

2018-04-01

We discuss how the recently developed energy dissipation methods for reaction diffusion systems can be generalized to the non-isothermal case. For this, we use concave entropies in terms of the densities of the species and the internal energy, where the importance is that the equilibrium densities may depend on the internal energy. Using the log-Sobolev estimate and variants for lower-order entropies as well as estimates for the entropy production of the nonlinear reactions, we give two methods to estimate the relative entropy by the total entropy production, namely a somewhat restrictive convexity method, which provides explicit decay rates, and a very general, but weaker compactness method.
Waterhammer modeling for the Ares I Upper Stage Reaction Control System cold flow development test article

Science.gov (United States)

Williams, Jonathan Hunter

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

Science.gov (United States)

Williams, Jonathan H.

2010-01-01

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

Science.gov (United States)

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

2016-07-13

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

Czech Academy of Sciences Publication Activity Database

Eisner, J.; Väth, Martin

2016-01-01

Roč. 135, April (2016), s. 158-193 ISSN 0362-546X Institutional support: RVO:67985840 Keywords : reaction-diffusion system * turing instability * global bifurcation Subject RIV: BA - General Mathematics Impact factor: 1.192, year: 2016 http://www.sciencedirect.com/science/article/pii/S0362546X16000146
Thermodynamics of random reaction networks.

Directory of Open Access Journals (Sweden)

Jakob Fischer

Full Text Available Reaction networks are useful for analyzing reaction systems occurring in chemistry, systems biology, or Earth system science. Despite the importance of thermodynamic disequilibrium for many of those systems, the general thermodynamic properties of reaction networks are poorly understood. To circumvent the problem of sparse thermodynamic data, we generate artificial reaction networks and investigate their non-equilibrium steady state for various boundary fluxes. We generate linear and nonlinear networks using four different complex network models (Erdős-Rényi, Barabási-Albert, Watts-Strogatz, Pan-Sinha and compare their topological properties with real reaction networks. For similar boundary conditions the steady state flow through the linear networks is about one order of magnitude higher than the flow through comparable nonlinear networks. In all networks, the flow decreases with the distance between the inflow and outflow boundary species, with Watts-Strogatz networks showing a significantly smaller slope compared to the three other network types. The distribution of entropy production of the individual reactions inside the network follows a power law in the intermediate region with an exponent of circa -1.5 for linear and -1.66 for nonlinear networks. An elevated entropy production rate is found in reactions associated with weakly connected species. This effect is stronger in nonlinear networks than in the linear ones. Increasing the flow through the nonlinear networks also increases the number of cycles and leads to a narrower distribution of chemical potentials. We conclude that the relation between distribution of dissipation, network topology and strength of disequilibrium is nontrivial and can be studied systematically by artificial reaction networks.
Investigation of (n,γ) reactions in fissionable fluids in a hybrid reactor system

Energy Technology Data Exchange (ETDEWEB)

Guenay, Mehtap [Inoenue Univ., Malatya (Turkey). Physics Dept.

2014-06-15

In this study, the effect of (n,γ) reactions in spent fuel-grade (SFG)-PuO{sub 2}, UO{sub 2}, NpO{sub 2} and UCO contents was investigated in a designed hybrid reactor system. In this system, the molten salt-heavy metal mixtures 93 - 85 % Li{sub 20}Sn{sub 80} + 5 % SFG-PuO{sub 2} and 2 - 10 % UO{sub 2}, 93 - 85 % Li{sub 20}Sn{sub 80} + 5 % SFG-PuO{sub 2} and 2 - 10 % NpO{sub 2}, 93 - 85 % Li{sub 20}Sn{sub 80} + 5 % SFG-PuO{sub 2} and 2 - 10 % UCO were used as fluids. Beryllium (Be) is used as neutron multiplier by (n,2n) reactions. Thence, a Be zone with a width of 3 cm was used in order to contribute on fissile fuel breeding between the liquid first wall and blanket. (n,γ) reactions were calculated in the liquid first wall, blanket and shield zones, which SFG-PuO{sub 2}, UO{sub 2}, NpO{sub 2} and UCO contents. 9Cr2WVTa ferritic steel with the width of 4 cm was used as the structural material. Three-dimensional nucleonic calculations were performed using the most recent version MCNPX-2.7.0 the Monte Carlo code and nuclear data library ENDF/B-VII.0. (orig.)
The complex reaction kinetics of neptunium including redox and extraction process in 30% TBP-nitric acid system

International Nuclear Information System (INIS)

Hu Zhang; Zhan-yuan Liu; Xian-ming Zhou; Li Li

2017-01-01

In order to understand the complex and dynamic neptunium process chemistry in the TBP-HNO_3 system, the kinetics involved reversible redox reaction and extraction mass transfer was investigated. The results indicates that the mass transfer rate of Np(VI) is much faster than the redox reaction in aqueous solution. The concentrations of nitric acid and nitrous acid not only can change the Np(V) oxidation reaction and Np(VI) reduction reaction rate, but also can ultimately determine the distribution of neptunium extraction equilibrium. The variety of temperature can only influence the extraction equilibrium time, but cannot alter the equilibrium state of neptunium. (author)
Reaction of long-lived radicals and vitamin C in γ-irradiated mammalian cells and their model system at 295 K. Tunneling reaction in biological system

International Nuclear Information System (INIS)

Matsumoto, Takuro; Kumada, Takayuki; Kodama, Seiji; Watanabe, Masami

1997-01-01

When golden hamster embryo (GHE) cells or concentrated albumin solution (0.1 kg dm -3 ), that is a model system of cells, is irradiated with γ-rays at 295 K, organic radicals produced can be observed by ESR. The organic radicals survive at both 295 and 310 K for as long as 20 h. The long-lived radicals in GHE cells and the albumin solution react with vitamin C by the rate constants of 0.007 dm 3 mol -1 s -1 and 0.014 dm 3 mol -1 s -1 , respectively. The long-lived radicals in human cells cause gene mutation, which is suppressed by the addition of vitamin C. The isotope effect on the rate constant (κ) for the reaction of the long-lived radicals and vitamin C has been studied in the albumin solution by use of protonated vitamin C and deuterated vitamin C. The isotope effect (κ H /κ D ) was more than 20 ∼ 50 and was interpreted in terms of tunnelling reaction. (author)
Geochemical constraints on chemolithoautotrophic reactions in hydrothermal systems

Science.gov (United States)

Shock, Everett L.; McCollom, Thomas; Schulte, Mitchell D.

1995-06-01

Thermodynamic calculations provide the means to quantify the chemical disequilibrium inherent in the mixing of redeuced hydrothermal fluids with seawater. The chemical energy available for metabolic processes in these environments can be evaluated by taking into account the pressure and temperature dependence of the apparent standard Gibbs free energies of reactions in the S-H2-H2O system together with geochemical constraints on pH, activities of aqueous sulfur species and fugacities of H2 and/or O2. Using present-day mixing of hydrothermal fluids and seawater as a starting point, it is shown that each mole of H2S entering seawater from hydrothermal fluids represents about 200,000 calories of chemical energy for metabolic systems able to catalyze H2S oxidation. Extrapolating to the early Earth, which was likely to have had an atmosphere more reduced than at present, shows that this chemical energy may have been a factor of two or so less. Nevertheless, mixing of hydrothermal fluids with seawater would have been an abundant source of chemical energy, and an inevitable consequence of the presence of an ocean on an initially hot Earth. The amount of energy available was more than enough for organic synthesis from CO2 or CO, and/or polymer formation, indicating that the vicinity of hydrothermal systems at the sea floor was an ideal location for the emergence of the first chemolithoautotrophic metabolic systems.
Lattice-enabled nuclear reactions in the nickel and hydrogen gas system

International Nuclear Information System (INIS)

Nagel, David J.

2015-01-01

Thousands of lattice-enabled nuclear reaction (LENR) experiments involving electrochemical loading of deuterium into palladium have been conducted and reported in hundreds of papers. But, it appears that the first commercial LENR power generators will employ gas loading of hydrogen onto nickel. This article reviews the scientific base for LENR in the gas-loaded Ni-H system, and some of the tests of pre-commercial prototype generators based on this combination. (author)
Significance of grafting in radiation curing reactions. Comparison of ionising radiation and UV systems

International Nuclear Information System (INIS)

Zilic, E.; Ng, L.; Viengkhou, V.; Garnett, J.L.

1998-01-01

Full text: Radiation curing is now an accepted commercial technology where both ionising radiation (electron beam) and ultra violet light (UV) sources are used. Grafting is essentially the copolymerisation of a monomer/oligomer to a backbone polymer whereas curing is the rapid polymerisation of a monomer/oligomer mixture onto the surface of the substrate. There is no time scale theoretically associated with grafting processes which can occur in minutes or hours whereas curing reactions are usually very rapid, occurring within a fraction of a second. An important difference between grafting and curing is the nature of the bonding occurring in each process. In grafting covalent carbon-carbon bonds are formed, whereas in curing, bonding usually involves weaker Van der Waals or London dispersion forces. The bonding properties of the systems are important in determining their use commercially. Thus the possibility that concurrent grafting during curing could occur in a system is important since if present, grafting would not only minimise delamination of the coated product but could also, in some circumstances, render difficulties recycling of the finished product especially if it were cellulosic. Hence the conditions for observing the occurrence of concurrent grafting during radiation curing are important. In the present paper, this problem has been studied by examining the effect that the components used in radiation curing exert on a typical reaction. Instead of electron beam sources, the spent fuel element facility at Lucas Heights is used to simulate such ionising radiation sources. The model system utilised is the grafting of a typical methacrylate to cellulose. This is the generic chemistry used in curing systems. The effect of typical additives from curing systems including polyfunctional monomer and oligomers in the grafting reactions have been studied. The ionising radiation results have been compared with analogous data from UV experiments. The significance
Verification of cold nuclear fusion reaction, (1)

International Nuclear Information System (INIS)

Yoshida, Zenko; Aratono, Yasuyuki; Hirabayashi, Takakuni

1991-01-01

Can cold nuclear fusion reaction occur as is expected? If it occurs, what extent is its reaction probability? At present after 2 years elapsed since its beginning, the clear solution of these questions is not yet obtained. In many reaction systems employing different means, the experiments to confirm the cold nuclear fusion reaction have been attempted. In order to confirm that the nuclear fusion reaction of deuterium mutually has occurred, the neutrons, He-3, protons, tritium or generated heat, which were formed by the reaction and released from the system, are measured. Since it is considered that the frequency of the occurrence at normal temperature of the reaction is very low, it is necessary to select the most suitable method upon evaluating the limit of detection peculiar to the measuring methods. The methods of measuring neutrons, protons, gamma ray and generated heat, and the reaction systems by electrolytic process and dry process are explained. The detection of plural kinds of the reaction products and the confirmation of synchronism of signals are important. (K.I.)
Highly selective transformation of ammonia nitrogen to N2 based on a novel solar-driven photoelectrocatalytic-chlorine radical reactions system.

Science.gov (United States)

Ji, Youzhi; Bai, Jing; Li, Jinhua; Luo, Tao; Qiao, Li; Zeng, Qingyi; Zhou, Baoxue

2017-11-15

A highly selective method for transforming ammonia nitrogen to N 2 was proposed, based on a novel solar-driven photoelectrocatalytic-chlorine radical reactions (PEC-chlorine) system. The PEC-chlorine system was facilitated by a visible light response WO 3 nanoplate array (NPA) electrode in an ammonia solution containing chloride ions (Cl - ). Under illumination, photoholes from WO 3 promote the oxidation of Cl - to chlorine radical (Cl). This radical can selectively transform ammonia nitrogen to N 2 (79.9%) and NO 3 - (19.2%), similar to the breakpoint chlorination reaction. The ammonia nitrogen removal efficiency increased from 10.6% (PEC without Cl - ) to 99.9% with the PEC-chlorine system within 90 min operation, which can be attributed to the cyclic reactions between Cl - /Cl and the reaction intermediates (NH 2 , NHCl, etc.) that expand the degradation reactions from the surface of the electrodes to the whole solution system. Moreover, Cl is the main radical species contributing to the transformation of ammonia nitrogen to N 2 , which is confirmed by the tBuOH capture experiment. Compared to conventional breakpoint chlorination, the PEC-chlorine system is a more economical and efficient means for ammonia nitrogen degradation because of the fast removal rate, no additional chlorine cost, and its use of clean energy (since it is solar-driven). Copyright © 2017 Elsevier Ltd. All rights reserved.
A dynamical theory of incomplete fusion reactions: The breakup-fusion reaction approach

International Nuclear Information System (INIS)

Udagawa, T.

1984-01-01

A dynamical theory of partial fusion reactions is presented, which may fill the gap between direct and compound nuclear reaction theories. With the new theory one can calculate partial fusion taking place in three-body (and many more) channels reached via direct reactions, e.g., breakup and knockout reactions. The authors present first the results for the cross section for such reactions, taking as an example breakup followed by fusion. They then discuss a physical picture which emerges from their theory, namely that the partial fusion reactions, particularly of the massive-transfer type, take place in a so-called deep peripheral region. It is also shown that the deep peripheral character of such processes diminishes as the mass of the fused system decreases, so that the reactions essentially evolve to the usual peripheral character. Finally, comparisons are made of results of numerical calculations with experimental data, taking as an example the /sup 159/Tb(/sup 14/N,α) reaction with E/sub lab/ = 95 MeV
Nonlinear variational models for reaction and diffusion systems

International Nuclear Information System (INIS)

Tanyi, G.E.

1983-08-01

There exists a natural metric w.r.t. which the density dependent diffusion operator is harmonic in the sense of Eells and Sampson. A physical corollary of this statement is the property that any two regular points on the orbit of a reaction or diffusion operator can be connected by a path along which the reaction rate is constant. (author)
Communication: Rovibrationally selected absolute total cross sections for the reaction H{sub 2}O{sup +}(X{sup 2}B{sub 1}; v{sub 1}{sup +}v{sub 2}{sup +}v{sub 3}{sup +}= 000; N{sup +}{sub Ka+Kc+)}+ D{sub 2}: Observation of the rotational enhancement effect

Energy Technology Data Exchange (ETDEWEB)

Xu Yuntao; Xiong Bo; Chang, Yih Chung; Ng, C. Y. [Department of Chemistry, University of California, Davis, California 95616 (United States)

2012-12-28

By employing the newly established vacuum ultraviolet laser pulsed field ionization-photoion (PFI-PI) double quadrupole-double octopole ion guide apparatus, we have measured the rovibrationally selected absolute total cross sections of the ion-molecule reaction H{sub 2}O{sup +}(X{sup 2}B{sub 1}; v{sub 1}{sup +}v{sub 2}{sup +}v{sub 3}{sup +}= 000; N{sup +}{sub Ka+Kc+)}+ D{sub 2}{yields} H{sub 2}DO{sup +}+ D in the center-of-mass collision energy (E{sub cm}) range of 0.05-10.00 eV. The pulsing scheme used for the generation of PFI-PIs has made possible the preparation of reactant H{sub 2}O{sup +}(X{sup 2}B{sub 1}; v{sub 1}{sup +}v{sub 2}{sup +}v{sub 3}{sup +}= 000) ions in single N{sup +}{sub Ka+Kc+} rotational levels with high kinetic energy resolutions. The absolute total cross sections observed in different N{sup +}{sub Ka+Kc+} levels with rotational energies in the range of 0-200 cm{sup -1} were found to exhibit a significant rotational enhancement on the reactivity for the titled reaction. In contrast, the measured cross sections reveal a decreasing trend with increasing E{sub cm}, indicating that the rotational enhancement observed is not a total energy effect, but a dynamical effect. Furthermore, the rotational enhancement is found to be more pronounced as E{sub cm} is decreased. This experiment provided evidence that the coupling of the core rotational angular momentum with the orbital angular momentum could play a role in chemical reactivity, particularly at low E{sub cm}.
Nobel Prize 1992: Rudolph A. Marcus: theory of electron transfer reactions in chemical systems

International Nuclear Information System (INIS)

Ulate Segura, Diego Guillermo

2011-01-01

A review of the theory developed by Rudolph A. Marcus is presented, who for his rating to the theory of electron transfer in chemical systems was awarded the Nobel Prize in Chemistry in 1992. Marcus theory has constituted not only a good extension of the use of a spectroscopic principle, but also has provided an energy balance and the application of energy conservation for electron transfer reactions. A better understanding of the reaction coordinate is exposed in terms energetic and establishing the principles that govern the transfer of electrons, protons and some labile small molecular groups as studied at present. Also, the postulates and equations described have established predictive models of reaction time, very useful for industrial environments, biological, metabolic, and others that involve redox processes. Marcus theory itself has also constituted a large contribution to the theory of complex transition [es
Non-Archimedean reaction-ultradiffusion equations and complex hierarchic systems

Science.gov (United States)

Zúñiga-Galindo, W. A.

2018-06-01

We initiate the study of non-Archimedean reaction-ultradiffusion equations and their connections with models of complex hierarchic systems. From a mathematical perspective, the equations studied here are the p-adic counterpart of the integro-differential models for phase separation introduced by Bates and Chmaj. Our equations are also generalizations of the ultradiffusion equations on trees studied in the 1980s by Ogielski, Stein, Bachas, Huberman, among others, and also generalizations of the master equations of the Avetisov et al models, which describe certain complex hierarchic systems. From a physical perspective, our equations are gradient flows of non-Archimedean free energy functionals and their solutions describe the macroscopic density profile of a bistable material whose space of states has an ultrametric structure. Some of our results are p-adic analogs of some well-known results in the Archimedean setting, however, the mechanism of diffusion is completely different due to the fact that it occurs in an ultrametric space.
Progress in microscopic direct reaction modeling of nucleon induced reactions

Energy Technology Data Exchange (ETDEWEB)

Dupuis, M.; Bauge, E.; Hilaire, S.; Lechaftois, F.; Peru, S.; Pillet, N.; Robin, C. [CEA, DAM, DIF, Arpajon (France)

2015-12-15

A microscopic nuclear reaction model is applied to neutron elastic and direct inelastic scatterings, and pre-equilibrium reaction. The JLM folding model is used with nuclear structure information calculated within the quasi-particle random phase approximation implemented with the Gogny D1S interaction. The folding model for direct inelastic scattering is extended to include rearrangement corrections stemming from both isoscalar and isovector density variations occurring during a transition. The quality of the predicted (n,n), (n,n{sup '}), (n,xn) and (n,n{sup '}γ) cross sections, as well as the generality of the present microscopic approach, shows that it is a powerful tool that can help improving nuclear reactions data quality. Short- and long-term perspectives are drawn to extend the present approach to more systems, to include missing reactions mechanisms, and to consistently treat both structure and reaction problems. (orig.)

Polymeric reaction of polymer-monomer system for pressure sensitive adhesives by low energy electron beam

International Nuclear Information System (INIS)

Takiguchi, R.; Uryu, T.

1985-01-01

Application of low-energy electron beam to non-solvent type pressure sensitive adhesives is investigated. The adhesive properties such as peel strength and holding time (dead-load strength) were closely related to the reaction of acrylate polymer-monomer systems. The reaction behavior is elucidated by combining the measurement of gel fraction, infrared spectrum of gel, and the molecular weight distribution detected by gel permeation chromatography. It was important for the production of pressure sensitive adhesives by electron beam that the adhesive with high peel strength and long holding time is composed of a proper combination of three factors, that is, about 35% gel fraction, 25% monomer units in gel, and 15% graft efficiency by irradiating the polymer-monomer system containing low molecular weight poly (butyl acrylate). (author)
Toward a Kinetic Model for Acrylamide Formation in a Glucose-Asparagine Reaction System

NARCIS (Netherlands)

Knol, J.J.; Loon, W.A.M.; Linssen, J.P.H.; Ruck, A.L.; Boekel, van M.A.J.S.

2005-01-01

A kinetic model for the formation of acrylamide in a glucose-asparagine reaction system is pro-posed. Equimolar solutions (0.2 M) of glucose and asparagine were heated at different tempera-tures (120-200 C) at pH 6.8. Besides the reactants, acrylamide, fructose, and melanoidins were quantified after
Effective dynamics along given reaction coordinates, and reaction rate theory.

Science.gov (United States)

Zhang, Wei; Hartmann, Carsten; Schütte, Christof

2016-12-22

In molecular dynamics and related fields one considers dynamical descriptions of complex systems in full (atomic) detail. In order to reduce the overwhelming complexity of realistic systems (high dimension, large timescale spread, limited computational resources) the projection of the full dynamics onto some reaction coordinates is examined in order to extract statistical information like free energies or reaction rates. In this context, the effective dynamics that is induced by the full dynamics on the reaction coordinate space has attracted considerable attention in the literature. In this article, we contribute to this discussion: we first show that if we start with an ergodic diffusion process whose invariant measure is unique then these properties are inherited by the effective dynamics. Then, we give equations for the effective dynamics, discuss whether the dominant timescales and reaction rates inferred from the effective dynamics are accurate approximations of such quantities for the full dynamics, and compare our findings to results from approaches like Mori-Zwanzig, averaging, or homogenization. Finally, by discussing the algorithmic realization of the effective dynamics, we demonstrate that recent algorithmic techniques like the "equation-free" approach and the "heterogeneous multiscale method" can be seen as special cases of our approach.
High energy nuclear reactions ('Spallation') and their application in calculation of the Acceleration Driven Systems (ADS)

International Nuclear Information System (INIS)

Rossi, Pedro Carlos Russo

2011-01-01

This work presents a study of high energy nuclear reactions which are fundamental to dene the source term in accelerator driven systems. These nuclear reactions, also known as spallation, consist in the interaction of high energetic hadrons with nucleons in the atomic nucleus. The phenomenology of these reactions consist in two step. In the rst, the proton interacts through multiple scattering in a process called intra-nuclear cascade. It is followed by a step in which the excited nucleus, coming from the intranuclear cascade, could either, evaporates particles to achieve a moderate energy state or fission. This process is known as competition between evaporation and fission. In this work the main nuclear models, Bertini and Cugnon are reviewed, since these models are fundamental for design purposes of the source term in ADS, due to lack of evaluated nuclear data for these reactions. The implementation and validation of the calculation methods for the design of the source is carried out to implement the methodology of source design using the program MCNPX (Monte Carlo N-Particle eXtended), devoted to calculation of transport of these particles and the validation performed by an international cooperation together with a Coordinated Research Project (CRP) of the International Atomic Energy Agency and available jobs, in order to qualify the calculations on nuclear reactions and the de-excitation channels involved, providing a state of the art of design and methodology for calculating external sources of spallation for source driven systems. The CRISP, is a brazilian code for the phenomenological description of the reactions involved and the models implemented in the code were reviewed and improved to continue the qualification process. Due to failure of the main models in describing the production of light nuclides, the multifragmentation reaction model was studied. Because the discrepancies in the calculations of production of these nuclides are attributes to the
CHEMSIMUL - A program package for numerical simulation of chemical reaction systems

International Nuclear Information System (INIS)

Lang Rasmussen, O.; Bjergbakke, E.

1984-01-01

A description is given of a program package, CHEMSIMUL, for numerical simulation of chemical reaction systems. The main components in the package are a translator of chemical equations to differential equations, a balance equation program, a differential equation solver, EPISODE, and an input/output program. The performance of the program is demonstrated by four examples. A manual for the input file and the complete program text with comments are given in Appendices I and II. (author)
Pulse radiolysis studies of fast reactions in molecular systems. Progress report, November 1976--October 1977

International Nuclear Information System (INIS)

Dorfman, L.M.

1977-01-01

Results from research in the following two areas are given: formation, properties, and reactivity of molecular ionic species in irradiated liquid systems; and pulse radiolysis of elementary reactions in protein function
Possibilities of achieving fusion reaction with a 4{pi} focusing system

Energy Technology Data Exchange (ETDEWEB)

Barsanti, G; Barsella, B; Camerini, M; Federighi, U; Musumeci, L; Talini, N [CAMEN., Leghorn (Italy)

1958-07-01

The 4{pi} focusing by means of an electromagnetic field is analysed. The following points considered: (a) The general solutions of system for equations of motion of a mass m with charge +e valid for arbitrary initial conditions. This is necessary for the consideration of imperfectly focused primary trajectories, of the effect of collisions in the vicinity of the origin and of ions produced in the neutral gas which diffuses into the reaction chamber. (b) Investigation of the primary ion injection system, of the density of the ions in the chamber and of the energy balance as a matter of principle. (c) The experimental apparatus needed for 4{pi} focusing of deuterons and a sketch of a fusion reactor.
Gas-Phase Reaction Pathways and Rate Coefficients for the Dichlorosilane-Hydrogen and Trichlorosilane-Hydrogen Systems

Science.gov (United States)

Dateo, Christopher E.; Walch, Stephen P.

2002-01-01

As part of NASA Ames Research Center's Integrated Process Team on Device/Process Modeling and Nanotechnology our goal is to create/contribute to a gas-phase chemical database for use in modeling microelectronics devices. In particular, we use ab initio methods to determine chemical reaction pathways and to evaluate reaction rate coefficients. Our initial studies concern reactions involved in the dichlorosilane-hydrogen (SiCl2H2--H2) and trichlorosilane-hydrogen (SiCl2H-H2) systems. Reactant, saddle point (transition state), and product geometries and their vibrational harmonic frequencies are determined using the complete-active-space self-consistent-field (CASSCF) electronic structure method with the correlation consistent polarized valence double-zeta basis set (cc-pVDZ). Reaction pathways are constructed by following the imaginary frequency mode of the saddle point to both the reactant and product. Accurate energetics are determined using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations (CCSD(T)) extrapolated to the complete basis set limit. Using the data from the electronic structure calculations, reaction rate coefficients are obtained using conventional and variational transition state and RRKM theories.
Fracture behavior of reaction layers in W and SiC joint system

International Nuclear Information System (INIS)

Son, S.J.; Kohyama, A.; Yu, I.K.; Cho, S.

2007-01-01

Full text of publication follows: SiC and SiC/SiC composites are considering as attractive structural materials for fusion reactors, because of their excellent physical, chemical and nuclear properties in fusion environments. For the application of these materials to gas-cooled fusion blanket systems, they have to satisfy specific requirements, such as hermeticity and surface features, in addition to baseline thermo-mechanical and irradiation properties. One of the critical issues for a fusion technology is a plasma facing material, which is considered in the connection with joining, heat transfer control and protection from helium gas in high temperature components. Tungsten as a coating material for SiC-based plasma-facing components has excellent advantages, such as a small mismatch in coefficient of thermal expansion, a very low sputtering yield, inherent heat resistance and high thermal conductivity. Therefore, tungsten and its alloys are promising as potential coating materials for divertor and first wall applications. In the present work, by using micron-sized tungsten and nano-SiC powders, W-SiC joints were prepared by simultaneous and sequential hot-pressing process. Various reaction products in the tungsten-SiC system were revealed by microstructural analyses. The interfacial phases and thickness were strongly depended on the temperature and time of hot pressing. The fracture characteristics of the reaction layers determine the robustness of W/SiC systems. Therefore, in this work, fracture behaviors by analyzing the indentation induced cracks in each phase and mechanical properties of W/SiC joints were examined. The most high shear strength was obtained in the joints fabricated at the conditions of 1780 deg. C, 20 MPa, 1 hr holding time. Easy crack extension was confirmed in the region of WC phase. The fracture of 1870 deg. C fabrication samples, which showed comparatively low shear strength, occurred at the wide region of reaction phases (WC+W 5 Si 3 +W
[The adaptation reactions in hormonal systems to the internal use of mineral waters].

Science.gov (United States)

Polushina, N D

1991-01-01

A single intake of mineral water Essentuki 17 by male Wistar rats (n-130, b. w. 180-250 g) leads to stress reactions. It is evident from elevated levels of ACTH, hydrocortisone, leuenkephaline, glucagon and gastrin. Course intake of the water brings about a rise in most of the hormones levels studied. However, single doses of Essentuki 17 inhibit production of hormones in the adrenals, hypophysis, hypothalamus, the system of endogenic opiates. The enhancement of relevant levels are noted in the gastroenteropancreatic system.
The EFF-2 evaluation for the reaction systems n + 52Cr, 56Fe, 58Ni and 60Ni

International Nuclear Information System (INIS)

Uhl, M.; Gruppelaar, H.; Kamp, H.A.J. van der; Kopecky, J.; Nierop, D.

1991-05-01

The evaluated cross sections for incident energies between 1 and 20 MeV are essentially based on nuclear reaction model calculations. Model parameters were chosen so as to simultaneously reproduce many available experimental data. At low energies the cross sections were taken from other evaluations. Calculations consider the spherical optical model, the statistical compound nucleus model under consideration of angular momentum and parity, the exciton model for first change pre-equilibrium emission of particles and photons and a direct reaction model for in-elastic scattering. The exciton model employed accounted for angular momentum conservation. For each reaction system evaluation comprises the following cross sections: total, elastic, production of light reaction products (photons, neutrons, protons and alphas) and production of heavy reaction products (about 10 residual nuclei for each target). Furthermore included are the energy-angle distributions of the light reaction products and of the heavy reaction products (i.e. the double differential recoil spectra). (author). 34 refs.; 4 figs
Existence and exponential stability of traveling waves for delayed reaction-diffusion systems

Science.gov (United States)

Hsu, Cheng-Hsiung; Yang, Tzi-Sheng; Yu, Zhixian

2018-03-01

The purpose of this work is to investigate the existence and exponential stability of traveling wave solutions for general delayed multi-component reaction-diffusion systems. Following the monotone iteration scheme via an explicit construction of a pair of upper and lower solutions, we first obtain the existence of monostable traveling wave solutions connecting two different equilibria. Then, applying the techniques of weighted energy method and comparison principle, we show that all solutions of the Cauchy problem for the considered systems converge exponentially to traveling wave solutions provided that the initial perturbations around the traveling wave fronts belong to a suitable weighted Sobolev space.
Explore the reaction mechanism of the Maillard reaction: a density functional theory study.

Science.gov (United States)

Ren, Ge-Rui; Zhao, Li-Jiang; Sun, Qiang; Xie, Hu-Jun; Lei, Qun-Fang; Fang, Wen-Jun

2015-05-01

The mechanism of Maillard reaction has been investigated by means of density functional theory calculations in the gaseous phase and aqueous solution. The Maillard reaction is a cascade of consecutive and parallel reaction. In the present model system study, glucose and glycine were taken as the initial reactants. On the basis of previous experimental results, the mechanisms of Maillard reaction have been proposed, and the possibility for the formation of different compounds have been evaluated through calculating the relative energy changes for different steps of reaction under different pH conditions. Our calculations reveal that the TS3 in Amadori rearrangement reaction is the rate-determining step of Maillard reaction with the activation barriers of about 66.7 and 68.8 kcal mol(-1) in the gaseous phase and aqueous solution, respectively. The calculation results are in good agreement with previous studies and could provide insights into the reaction mechanism of Maillard reaction, since experimental evaluation of the role of intermediates in the Maillard reaction is quite complicated.
Square Turing patterns in reaction-diffusion systems with coupled layers

Energy Technology Data Exchange (ETDEWEB)

Li, Jing [State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871 (China); Wang, Hongli, E-mail: hlwang@pku.edu.cn, E-mail: qi@pku.edu.cn [State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871 (China); Center for Quantitative Biology, Peking University, Beijing 100871 (China); Ouyang, Qi, E-mail: hlwang@pku.edu.cn, E-mail: qi@pku.edu.cn [State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871 (China); Center for Quantitative Biology, Peking University, Beijing 100871 (China); The Peking-Tsinghua Center for Life Sciences, Beijing 100871 (China)

2014-06-15

Square Turing patterns are usually unstable in reaction-diffusion systems and are rarely observed in corresponding experiments and simulations. We report here an example of spontaneous formation of square Turing patterns with the Lengyel-Epstein model of two coupled layers. The squares are found to be a result of the resonance between two supercritical Turing modes with an appropriate ratio. Besides, the spatiotemporal resonance of Turing modes resembles to the mode-locking phenomenon. Analysis of the general amplitude equations for square patterns reveals that the fixed point corresponding to square Turing patterns is stationary when the parameters adopt appropriate values.
Effect of reaction systems and surfactant additives on the morphology evolution of hydroxyapatite nanorods obtained via a hydrothermal route

Energy Technology Data Exchange (ETDEWEB)

Ma Tianyuan; Xia Zhiguo [School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China); Liao Libing, E-mail: lbliao@cugb.edu.cn [School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China)

2011-02-15

Well-dispersed hydroxyapatite (HA) nanorods with different morphologies were synthesized by a hydrothermal method in oleic acid, ethanol and water reaction system, and the surfactant assisted modifications effect was also comparatively studied. The structure and morphology of samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM), respectively. The effect of reaction systems and surfactant additives on the morphology evolution of HA nanorods were discussed in detail. The results showed that the controlled experimental conditions in the systems, such as the content ratio of oleic acid/ethanol, pH value and the content ratio of Ca/P source had an significant effect on the morphology evolution of as-prepared HA nanorods. Further, the selected surfactant additives, such as cetyltriethylammnonium bromide (CTAB), sodium dodecyl sulfate (K12) also play an important role in the formation of the uniform morphology of HA nanorods. Some possible formation mechanisms of the HA nanorods in the present reaction systems is proposed.
Roles of different initial Maillard intermediates and pathways in meat flavor formation for cysteine-xylose-glycine model reaction systems.

Science.gov (United States)

Hou, Li; Xie, Jianchun; Zhao, Jian; Zhao, Mengyao; Fan, Mengdie; Xiao, Qunfei; Liang, Jingjing; Chen, Feng

2017-10-01

To explore initial Maillard reaction pathways and mechanisms for maximal formation of meaty flavors in heated cysteine-xylose-glycine systems, model reactions with synthesized initial Maillard intermediates, Gly-Amadori, TTCA (2-threityl-thiazolidine-4-carboxylic acids) and Cys-Amadori, were investigated. Relative relativities were characterized by spectrophotometrically monitoring the development of colorless degradation intermediates and browning reaction products. Aroma compounds formed were determined by solid-phase microextraction combined with GC-MS and GC-olfactometry. Gly-Amadori showed the fastest reaction followed by Cys-Amadori then TTCA. Free glycine accelerated reaction of TTCA, whereas cysteine inhibited that of Gly-Amadori due to association forming relatively stable thiazolidines. Cys-Amadori/Gly had the highest reactivity in development of both meaty flavors and brown products. TTCA/Gly favored yielding meaty flavors, whereas Gly-Amadori/Cys favored generation of brown products. Conclusively, initial formation of TTCA and pathway involving TTCA with glycine were more applicable to efficiently produce processed-meat flavorings in a cysteine-xylose-glycine system. Copyright © 2017 Elsevier Ltd. All rights reserved.
Citric acid-modified Fenton's reaction for the oxidation of chlorinated ethylenes in soil solution systems.

Science.gov (United States)

Seol, Yongkoo; Javandel, Iraj

2008-06-01

Fenton's reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an in situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to create an acidic condition needed for catalytic oxidation. Fenton's reaction often involves pressure buildup and precipitation of reaction products, which can cause safety hazards and diminish efficiency. We selected citric acid, a food-grade substance, as an acidifying agent to evaluate its efficiencies for organic contaminant removal in Fenton's reaction, and examined the impacts of using citric acid on the unwanted reaction products. A series of batch and column experiments were performed with varying H2O2 concentrations to decompose selected chlorinated ethylenes. Either dissolved iron from soil or iron sulfate salt was added to provide the iron catalyst in the batch tests. Batch experiments revealed that both citric and sulfuric acid systems achieved over 90% contaminant removal rates, and the presence of iron catalyst was essential for effective decontamination. Batch tests with citric acid showed no signs of pressure accumulation and solid precipitations, however the results suggested that an excessive usage of H2O2 relative to iron catalysts (Fe2+/H2O2<1/330) would result in lowering the efficiency of contaminant removal by iron chelation in the citric acid system. Column tests confirmed that citric acid could provide suitable acidic conditions to achieve higher than 55% contaminant removal rates.
Effects of intrinsic stochasticity on delayed reaction-diffusion patterning systems

KAUST Repository

Woolley, Thomas E.; Baker, Ruth E.; Gaffney, Eamonn A.; Maini, Philip K.; Seirin-Lee, Sungrim

2012-01-01

Cellular gene expression is a complex process involving many steps, including the transcription of DNA and translation of mRNA; hence the synthesis of proteins requires a considerable amount of time, from ten minutes to several hours. Since diffusion-driven instability has been observed to be sensitive to perturbations in kinetic delays, the application of Turing patterning mechanisms to the problem of producing spatially heterogeneous differential gene expression has been questioned. In deterministic systems a small delay in the reactions can cause a large increase in the time it takes a system to pattern. Recently, it has been observed that in undelayed systems intrinsic stochasticity can cause pattern initiation to occur earlier than in the analogous deterministic simulations. Here we are interested in adding both stochasticity and delays to Turing systems in order to assess whether stochasticity can reduce the patterning time scale in delayed Turing systems. As analytical insights to this problem are difficult to attain and often limited in their use, we focus on stochastically simulating delayed systems. We consider four different Turing systems and two different forms of delay. Our results are mixed and lead to the conclusion that, although the sensitivity to delays in the Turing mechanism is not completely removed by the addition of intrinsic noise, the effects of the delays are clearly ameliorated in certain specific cases. © 2012 American Physical Society.
Effects of intrinsic stochasticity on delayed reaction-diffusion patterning systems

KAUST Repository

Woolley, Thomas E.

2012-05-22

Cellular gene expression is a complex process involving many steps, including the transcription of DNA and translation of mRNA; hence the synthesis of proteins requires a considerable amount of time, from ten minutes to several hours. Since diffusion-driven instability has been observed to be sensitive to perturbations in kinetic delays, the application of Turing patterning mechanisms to the problem of producing spatially heterogeneous differential gene expression has been questioned. In deterministic systems a small delay in the reactions can cause a large increase in the time it takes a system to pattern. Recently, it has been observed that in undelayed systems intrinsic stochasticity can cause pattern initiation to occur earlier than in the analogous deterministic simulations. Here we are interested in adding both stochasticity and delays to Turing systems in order to assess whether stochasticity can reduce the patterning time scale in delayed Turing systems. As analytical insights to this problem are difficult to attain and often limited in their use, we focus on stochastically simulating delayed systems. We consider four different Turing systems and two different forms of delay. Our results are mixed and lead to the conclusion that, although the sensitivity to delays in the Turing mechanism is not completely removed by the addition of intrinsic noise, the effects of the delays are clearly ameliorated in certain specific cases. © 2012 American Physical Society.
A Systematic Approach for the Design and Analysis of Reaction-Separation Systems with Recycle

DEFF Research Database (Denmark)

Gani, Rafiqul; Jimenez, Edgar Ramirez

2004-01-01

This paper presents a methodology for a systematic model-based analysis and the results obtained from it for an integrated design and analysis of reaction-separation systems with recycle. The methodology (systematic approach) consists of three stages where stage 1 identifies the limiting values...

Interfacial reactions in intermetallic matrix composites

International Nuclear Information System (INIS)

Cantrell, L.B.; Clevenger, E.M.; Perepezko, J.H.

1993-01-01

The thermal stability of advanced composites is dominated by the behavior of internal interfaces. Analysis of these internal interfaces often involves consideration of at least ternary order phase equilibria. Limited thermodynamic data exists for ternary and higher order systems. However, a combined approach based upon the use of binary data to estimate ternary phase equilibria and experimentally determined reaction pathways is effective in the analysis of interface reactions in composite systems. In blended powder samples, thermal analysis was used to find possible reaction temperatures, while X-ray analysis, EDS, and EPMA of diffusion couples were used to assess interdiffusion reaction pathways. The approach is illustrated by compatibility studies between TiAl and TiSi 2 at 1,100 C, and in-situ reactions between B 4 C and TiAl at 1300 C where multiple reaction sequences have been analyzed to provide guidance for the design of in-situ reaction processing of composites
Nonequilibrium transition and pattern formation in a linear reaction-diffusion system with self-regulated kinetics

Science.gov (United States)

Paul, Shibashis; Ghosh, Shyamolina; Ray, Deb Shankar

2018-02-01

We consider a reaction-diffusion system with linear, stochastic activator-inhibitor kinetics where the time evolution of concentration of a species at any spatial location depends on the relative average concentration of its neighbors. This self-regulating nature of kinetics brings in spatial correlation between the activator and the inhibitor. An interplay of this correlation in kinetics and disparity of diffusivities of the two species leads to symmetry breaking non-equilibrium transition resulting in stationary pattern formation. The role of initial noise strength and the linear reaction terms has been analyzed for pattern selection.
Stripping reactions in a three-body system. Comparison of DWBA and exact solutions

International Nuclear Information System (INIS)

Brinati, J.R.

1976-01-01

Stripping reactions 'a estados no continuo' are studied in a three particle system. Since the three-body problem has an exact treatment, comparison will be made between the exact solution and the DWBA model solution. This problem is more complex in the continuous case, as shown in the convergence problem of the standard DWBA amplitude radial integral
A Moessbauer spectroscopic study of corrosion related reactions in the iron-hydrogen fluoride-water-oxygen system

International Nuclear Information System (INIS)

Crouse, P.L.

1989-03-01

The results of a study of a number of corrosion related reactions in the Fe-HF-H 2 O-O2 system are presented. The primary techniques used were transmission and conversion electron Moessbauer spectroscopy. Conversion electron Moessbauer spectra were recorded at very low γ-photon glancing angles and at normal incidence. Depth profiles of surface layers were obtained by recording spectra at different glancing angles. The initial product which forms when an iron surface is exposed to the vapour of azeotropic hydrofluoric acid was identified as FeF 25 ·47H 2 O. With increasing film thickness, a product, identified as non-stoichiometric Fe 2 F 5 ·7H 2 O, was shown to occur. A thermodynamic analysis of the system is presented which shows FeF 3 ·3H 2 O to be the most stable compound under the experimental conditions used, and suggests a stepwise reaction sequence in which FeF 2 ·4H 2 O forms first, followed by Fe 2 F 5 ·7H 2 O and finally FeF 3 ·3H 2 O. Results obtained in a gravimetric study reveal the rate of reaction of metallic iron with the azeotropic vapour to be controlled by the rate of diffusion of the gaseous species through the product layer. In the case of the reactions with the vapour of higher dilutions of aqueous HF, the chemical reaction between the iron substrate and the gaseous species is rate controlling. 86 refs., 61 figs., 14 tabs
Kinetic modelling of reactions in heated disaccharide-casein systems

NARCIS (Netherlands)

Brands, C.M.J.; Boekel, van M.A.J.S.

2003-01-01

The reactions occurring in disaccharide-casein reaction mixtures during heating at 120 degreesC and pH 6.8 were studied. The existence of two main degradation routes were established: (1) Isomerisation of the aldose sugars lactose and maltose in their ketose isomers lactulose and maltulose,
Employee reactions to the use of management control systems in hospitals: motivation vs. threat.

Science.gov (United States)

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

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

International Nuclear Information System (INIS)

Meyer, R.E.; Arnold, W.D.; Kelmers, A.D.; Kessler, J.H.; Clark, R.J.; Johnson, J.S. Jr.; Young, G.C.; Case, F.I.; Westmoreland, C.G.

1985-01-01

Sorption isotherms and apparent concentration limits for Tc(VII) and Np(V) for a variety of groundwater/basalt systems were determined using Grande Ronde basalt samples representative of the Hanford Site candidate high-level waste repository. Under oxic redox conditions (air present), little or no sorption of technetium was observed; neptunium exhibited low to moderate sorption ratios. Under anoxic redox conditions (oxygen-free), low to moderate sorption of technetium was often observed, but the extent of sorption was highly dependent upon the groundwater composition and the method of pretreatment (if any) of the basalt. Sorption isotherms for technetium under reducing redox conditions (hydrazine added) indicate an apparent concentration limit of approximately 10 -6 mol/l Tc. No apparent concentration limit was found for neptunium for concentrations in groundwater up to 10 -6 mol/l and 8 x 10 -7 mol/l under oxic and reducing (hydrazine added) redox conditions, respectively. Valence control and valence analysis experiments suggest that the sorption or precipitation of Tc and Np from groundwater in the presence of basalt may result from a heterogeneous reaction occurring on the surface of the basalt. One of the critical factors of this reduction reaction appears to be the accessibility of the reactive ferrous iron component of the basalt. The laboratory simulation of groundwater redox conditions representative of the repository environment through the use of solution phase redox reagents is of questionable validity, and information obtained by such experimental methods may not be defensible for site performance assessment calculations. Anoxic experiments conducted in an argon-filled glove box appear better suited for the laboratory simulation of in situ redox conditions. 15 references, 6 figures
Technetium and neptunium reactions in basalt/groundwater systems

International Nuclear Information System (INIS)

Meyer, R.E.; Arnold, W.D.; Kelmers, A.D.; Kessler, J.H.; Clark, R.J.; Johnson, J.S. Jr.; Young, G.C.; Case, F.I.; Westmoreland, C.G.; Florida State Univ., Tallahassee)

1984-01-01

Sorption isotherms and apparent concentration limits for Tc(VII) and Np(V) for a variety of groundwater/basalt systems were determined using Grande Ronde basalt samples representative of the Hanford Site candidate high-level waste repository. Under oxic redox conditions (air present), little or no sorption of technetium was observed; neptunium exhibited low to moderate sorption ratios. Under anoxic redox conditions (oxygen-free), low to moderate sorption of technetium was often observed, but the extent of sorption was highly dependent upon the groundwater composition and the method of pretreatment (if any) of the basalt. Sorption isotherms for technetium under reducing redox conditions (hydrazine added) indicate an apparent concentration limit of approximately 10 -6 mol/L Tc. No apparent concentration limit was found for neptunium for concentrations in groundwater up to approx. 10 -6 mol/L and 8 x 10 -7 mol/L under oxic and reducing (hydrazine added) redox conditions, respectively. Valence control and valence analysis experiments suggest that the sorption or precipitation of Tc and Np from groundwater in the presence of basalt may result from a heterogeneous reaction occurring on the surface of the basalt. One of the critical factors of this reduction reaction appears to be the accessibility of the reactive ferrous iron component of the basalt. The laboratory simulation of groundwater redox conditions representative of the repository environment through the use of solution phase redox reagents is of questionable validity, and information obtained by such experimental methods may not be defensible for site performance assessment calculations. Anoxic experiments conducted in an argon-filled glove box appear better suited for the laboratory simulation of in situ redox conditions. 15 refs., 6 tabs
Modeling Chemical Reactions by QM/MM Calculations: The Case of the Tautomerization in Fireflies Bioluminescent Systems.

Science.gov (United States)

Berraud-Pache, Romain; Garcia-Iriepa, Cristina; Navizet, Isabelle

2018-01-01

In less than half a century, the hybrid QM/MM method has become one of the most used technique to model molecules embedded in a complex environment. A well-known application of the QM/MM method is for biological systems. Nowadays, one can understand how enzymatic reactions work or compute spectroscopic properties, like the wavelength of emission. Here, we have tackled the issue of modeling chemical reactions inside proteins. We have studied a bioluminescent system, fireflies, and deciphered if a keto-enol tautomerization is possible inside the protein. The two tautomers are candidates to be the emissive molecule of the bioluminescence but no outcome has been reached. One hypothesis is to consider a possible keto-enol tautomerization to treat this issue, as it has been already observed in water. A joint approach combining extensive MD simulations as well as computation of key intermediates like TS using QM/MM calculations is presented in this publication. We also emphasize the procedure and difficulties met during this approach in order to give a guide for this kind of chemical reactions using QM/MM methods.
Modelling chemical reactions by QM/MM calculations: the case of the tautomerization in fireflies bioluminescent systems

Science.gov (United States)

Berraud-Pache, Romain; Garcia-Iriepa, Cristina; Navizet, Isabelle

2018-04-01

In less than half a century, the hybrid QM/MM method has become one of the most used technique to model molecules embedded in a complex environment. A well-known application of the QM/MM method is for biological systems. Nowadays, one can understand how enzymatic reactions work or compute spectroscopic properties, like the wavelength of emission. Here, we have tackled the issue of modelling chemical reactions inside proteins. We have studied a bioluminescent system, fireflies, and deciphered if a keto-enol tautomerization is possible inside the protein. The two tautomers are candidates to be the emissive molecule of the bioluminescence but no outcome has been reached. One hypothesis is to consider a possible keto-enol tautomerization to treat this issue, as it has been already observed in water. A joint approach combining extensive MD simulations as well as computation of key intermediates like TS using QM/MM calculations is presented in this publication. We also emphasize the procedure and difficulties met during this approach in order to give a guide for this kind of chemical reactions using QM/MM methods.
Primary reaction control system/remote manipulator system interaction with loaded arm. Space shuttle engineering and operations support

Science.gov (United States)

Taylor, E. C.; Davis, J. D.

1978-01-01

A study of the interaction between the orbiter primary reaction control system (PRCS) and the remote manipulator system (RMS) with a loaded arm is documented. This analysis was performed with the Payload Deployment and Retrieval Systems Simulation (PDRSS) program with the passive arm bending option. The passive-arm model simulates the arm as massless elastic links with locked joints. The study was divided into two parts. The first part was the evaluation of the response of the arm to step inputs (i.e. constant jet torques) about each of the orbiter body axes. The second part of the study was the evaluation of the response of the arm to minimum impulse primary RCS jet firings with both single pulse and pulse train inputs.
Dynamics of interface in three-dimensional anisotropic bistable reaction-diffusion system

International Nuclear Information System (INIS)

He Zhizhu; Liu, Jing

2010-01-01

This paper presents a theoretical investigation of dynamics of interface (wave front) in three-dimensional (3D) reaction-diffusion (RD) system for bistable media with anisotropy constructed by means of anisotropic surface tension. An equation of motion for the wave front is derived to carry out stability analysis of transverse perturbations, which discloses mechanism of pattern formation such as labyrinthine in 3D bistable media. Particularly, the effects of anisotropy on wave propagation are studied. It was found that, sufficiently strong anisotropy can induce dynamical instabilities and lead to breakup of the wave front. With the fast-inhibitor limit, the bistable system can further be described by a variational dynamics so that the boundary integral method is adopted to study the dynamics of wave fronts.
Reaction Null Space of a multibody system with applications in robotics

Directory of Open Access Journals (Sweden)

D. N. Nenchev

2013-02-01

Full Text Available This paper provides an overview of implementation examples based on the Reaction Null Space formalism, developed initially to tackle the problem of satellite-base disturbance of a free-floating space robot, when the robot arm is activated. The method has been applied throughout the years to other unfixed-base systems, e.g. flexible-base and macro/mini robot systems, as well as to the balance control problem of humanoid robots. The paper also includes most recent results about complete dynamical decoupling of the end-link of a fixed-base robot, wherein the end-link is regarded as the unfixed-base. This interpretation is shown to be useful with regard to motion/force control scenarios. Respective implementation results are provided.
Learning to predict chemical reactions.

Science.gov (United States)

Kayala, Matthew A; Azencott, Chloé-Agathe; Chen, Jonathan H; Baldi, Pierre

2011-09-26

Being able to predict the course of arbitrary chemical reactions is essential to the theory and applications of organic chemistry. Approaches to the reaction prediction problems can be organized around three poles corresponding to: (1) physical laws; (2) rule-based expert systems; and (3) inductive machine learning. Previous approaches at these poles, respectively, are not high throughput, are not generalizable or scalable, and lack sufficient data and structure to be implemented. We propose a new approach to reaction prediction utilizing elements from each pole. Using a physically inspired conceptualization, we describe single mechanistic reactions as interactions between coarse approximations of molecular orbitals (MOs) and use topological and physicochemical attributes as descriptors. Using an existing rule-based system (Reaction Explorer), we derive a restricted chemistry data set consisting of 1630 full multistep reactions with 2358 distinct starting materials and intermediates, associated with 2989 productive mechanistic steps and 6.14 million unproductive mechanistic steps. And from machine learning, we pose identifying productive mechanistic steps as a statistical ranking, information retrieval problem: given a set of reactants and a description of conditions, learn a ranking model over potential filled-to-unfilled MO interactions such that the top-ranked mechanistic steps yield the major products. The machine learning implementation follows a two-stage approach, in which we first train atom level reactivity filters to prune 94.00% of nonproductive reactions with a 0.01% error rate. Then, we train an ensemble of ranking models on pairs of interacting MOs to learn a relative productivity function over mechanistic steps in a given system. Without the use of explicit transformation patterns, the ensemble perfectly ranks the productive mechanism at the top 89.05% of the time, rising to 99.86% of the time when the top four are considered. Furthermore, the system
Learning to Predict Chemical Reactions

Science.gov (United States)

Kayala, Matthew A.; Azencott, Chloé-Agathe; Chen, Jonathan H.

2011-01-01

Being able to predict the course of arbitrary chemical reactions is essential to the theory and applications of organic chemistry. Approaches to the reaction prediction problems can be organized around three poles corresponding to: (1) physical laws; (2) rule-based expert systems; and (3) inductive machine learning. Previous approaches at these poles respectively are not high-throughput, are not generalizable or scalable, or lack sufficient data and structure to be implemented. We propose a new approach to reaction prediction utilizing elements from each pole. Using a physically inspired conceptualization, we describe single mechanistic reactions as interactions between coarse approximations of molecular orbitals (MOs) and use topological and physicochemical attributes as descriptors. Using an existing rule-based system (Reaction Explorer), we derive a restricted chemistry dataset consisting of 1630 full multi-step reactions with 2358 distinct starting materials and intermediates, associated with 2989 productive mechanistic steps and 6.14 million unproductive mechanistic steps. And from machine learning, we pose identifying productive mechanistic steps as a statistical ranking, information retrieval, problem: given a set of reactants and a description of conditions, learn a ranking model over potential filled-to-unfilled MO interactions such that the top ranked mechanistic steps yield the major products. The machine learning implementation follows a two-stage approach, in which we first train atom level reactivity filters to prune 94.00% of non-productive reactions with a 0.01% error rate. Then, we train an ensemble of ranking models on pairs of interacting MOs to learn a relative productivity function over mechanistic steps in a given system. Without the use of explicit transformation patterns, the ensemble perfectly ranks the productive mechanism at the top 89.05% of the time, rising to 99.86% of the time when the top four are considered. Furthermore, the system
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.
Domino Wittig Diels-Alder reaction: An expeditious entry into the AB ring system of furanosesquiterpenes

Digital Repository Service at National Institute of Oceanography (India)

Patre, R.E.; Gawas, S.; Sen, S.; Parameswaran, P.S.; Tilve, S.G.

A domino Wittig Diels - Alder reaction has been employed in delineating a short and flexible synthetic stratagem for ready access to the AB ring system and the tricyclic framework of furanosesquiterpenes, such as the bioactive natural products...
Numerical verification of B-WIM system using reaction force signals

International Nuclear Information System (INIS)

Chang, Sung Jin; Kim, Nam Sik

2012-01-01

Bridges are ones of fundamental facilities for roads which become social overhead capital facilities and they are designed to get safety in their life cycles. However as time passes, bridge can be damaged by changes of external force and traffic environments. Therefore, a bridge should be repaired and maintained for extending its life cycle. The working load on a bridge is one of the most important factors for safety, it should be calculated accurately. The most important load among working loads is live load by a vehicle. Thus, the travel characteristics and weight of vehicle can be useful for bridge maintenance if they were estimated with high reliability. In this study, a B-WIM system in which the bridge is used for a scale have been developed for measuring the vehicle loads without the vehicle stop. The vehicle loads can be estimated by the developed B-WIM system with the reaction responses from the supporting points. The algorithm of developed B-WIM system have been verified by numerical analysis
Laser application for nuclear reaction product detecting system alignment

International Nuclear Information System (INIS)

Grantsev, V.I.; Dryapachenko, I.P.; Kornilov, V.A.; Nemets, O.F.; Rudenko, B.A.; Sokolov, M.V.; Struzhko, B.G.; Gnatovskij, A.V.; Bojchuk, V.N.

1982-01-01

A method for optical alignment of nuclear particle detector system using a laser beam and hologram is described. The method permits to arrange detectors very precisely in accordance with any chosen space coordinate values. The results of modelling the geometry of an experiment based on using the suggested method on cyclotron beams are described. A gas helium-neon laser with wavelength of 0.63 μm radiation power of an order of 2 MW and angular beam divergence less than 10 angular minutes is used for modelling. It is concluded that the laser and hologram application provides large possibilities for the modelling the geometry of experiments on nuclear reaction investigation. When necessary it is possible to obtain small nonius scale of reference beams by means of multiplicating properties of the wave front modulator-hologram system. It is also possible to record holograms shaping the reference beams in two or several planes crossing along the central beam direction. Such holograms can be used for modelling the noncoplanar geometry of correlation experiments [ru
Stability Analysis of a Reaction-Diffusion System Modeling Atherogenesis

KAUST Repository

Ibragimov, Akif

2010-01-01

This paper presents a linear, asymptotic stability analysis for a reaction-diffusionconvection system modeling atherogenesis, the initiation of atherosclerosis, as an inflammatory instability. Motivated by the disease paradigm articulated by Ross, atherogenesis is viewed as an inflammatory spiral with a positive feedback loop involving key cellular and chemical species interacting and reacting within the intimal layer of muscular arteries. The inflammatory spiral is initiated as an instability from a healthy state which is defined to be an equilibrium state devoid of certain key inflammatory markers. Disease initiation is studied through a linear, asymptotic stability analysis of a healthy equilibrium state. Various theorems are proved, giving conditions on system parameters guaranteeing stability of the health state, and a general framework is developed for constructing perturbations from a healthy state that exhibit blow-up, which are interpreted as corresponding to disease initiation. The analysis reveals key features that arterial geometry, antioxidant levels, and the source of inflammatory components (through coupled third-kind boundary conditions or through body sources) play in disease initiation. © 2010 Society for Industrial and Applied Mathematics.

Redox regulation and pro-oxidant reactions in the physiology of circadian systems.

Science.gov (United States)

Méndez, Isabel; Vázquez-Martínez, Olivia; Hernández-Muñoz, Rolando; Valente-Godínez, Héctor; Díaz-Muñoz, Mauricio

2016-05-01

Rhythms of approximately 24 h are pervasive in most organisms and are known as circadian. There is a molecular circadian clock in each cell sustained by a feedback system of interconnected "clock" genes and transcription factors. In mammals, the timing system is formed by a central pacemaker, the suprachiasmatic nucleus, in coordination with a collection of peripheral oscillators. Recently, an extensive interconnection has been recognized between the molecular circadian clock and the set of biochemical pathways that underlie the bioenergetics of the cell. A principle regulator of metabolic networks is the flow of electrons between electron donors and acceptors. The concomitant reduction and oxidation (redox) reactions directly influence the balance between anabolic and catabolic processes. This review summarizes and discusses recent findings concerning the mutual and dynamic interactions between the molecular circadian clock, redox reactions, and redox signaling. The scope includes the regulatory role played by redox coenzymes (NAD(P)+/NAD(P)H, GSH/GSSG), reactive oxygen species (superoxide anion, hydrogen peroxide), antioxidants (melatonin), and physiological events that modulate the redox state (feeding condition, circadian rhythms) in determining the timing capacity of the molecular circadian clock. In addition, we discuss a purely metabolic circadian clock, which is based on the redox enzymes known as peroxiredoxins and is present in mammalian red blood cells and in other biological systems. Both the timing system and the metabolic network are key to a better understanding of widespread pathological conditions such as the metabolic syndrome, obesity, and diabetes. Copyright © 2015 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.
Reactions of sulphur mustard on impregnated carbons.

Science.gov (United States)

Prasad, G K; Singh, Beer

2004-12-31

Activated carbon of surface area 1100 m2/gm is impregnated with 4% sodium hydroxide plus 3% Cr(VI) as CrO3 with and without 5% ethylene diamine (EDA), 4% magnesium nitrate and 5% ruthenium chloride by using their aqueous solutions. These carbons are characterized for surface area analysis by BET conventional method and exposed to the vapours of sulphur mustard (HD) at room temperature (30 degrees C). After 24 h, the reaction products are extracted in dichloromethane and analyzed using gas chromatography and mass spectrometry (GC-MS). Hemisulphur mustard, thiodiglycol, 1,4-oxathiane are observed to be the products of reaction between sulphur mustard and NaOH/CrO3/C system, whereas on NaOH/CrO3/EDA/C system HD reacted to give 1,4-thiazane. On Mg(NO3)2/C system it gave hemisulphur mustard and thiodiglycol. On RuCl3/C system it degraded to divinyl sulphone. Residual sulphur mustard is observed along with reaction products in all systems studied. Reaction mechanisms are also proposed for these interesting surface reactions. Above-mentioned carbons can be used in filtration systems for protection against hazardous gases such as sulphur mustard.
Reactions of sulphur mustard on impregnated carbons

International Nuclear Information System (INIS)

Prasad, G.K.; Singh, Beer

2004-01-01

Activated carbon of surface area 1100 m 2 /gm is impregnated with 4% sodium hydroxide plus 3% Cr(Vi) as CrO 3 with and without 5% ethylene diamine (EDA), 4% magnesium nitrate and 5% ruthenium chloride by using their aqueous solutions. These carbons are characterized for surface area analysis by BET conventional method and exposed to the vapours of sulphur mustard (HD) at room temperature (30 deg. C). After 24 h, the reaction products are extracted in dichloromethane and analyzed using gas chromatography and mass spectrometry (GC-MS). Hemisulphur mustard, thiodiglycol, 1,4-oxathiane are observed to be the products of reaction between sulphur mustard and NaOH/CrO 3 /C system, whereas on NaOH/CrO 3 /EDA/C system HD reacted to give 1,4-thiazane. On Mg(NO 3 ) 2 /C system it gave hemisulphur mustard and thiodiglycol. On RuCl 3 /C system it degraded to divinyl sulphone. Residual sulphur mustard is observed along with reaction products in all systems studied. Reaction mechanisms are also proposed for these interesting surface reactions. Above-mentioned carbons can be used in filtration systems for protection against hazardous gases such as sulphur mustard
Products and stability of phosphate reactions with lead under freeze-thaw cycling in simple systems

International Nuclear Information System (INIS)

Hafsteinsdottir, Erla G.; White, Duanne A.; Gore, Damian B.; Stark, Scott C.

2011-01-01

Orthophosphate fixation of metal contaminated soils in environments that undergo freeze-thaw cycles is understudied. Freeze-thaw cycling potentially influences the reaction rate, mineral chemical stability and physical breakdown of particles during fixation. This study determines what products form when phosphate (triple superphosphate [Ca(H 2 PO 4 ) 2 ] or sodium phosphate [Na 3 PO 4 ]) reacts with lead (PbSO 4 or PbCl 2 ) in simple chemical systems in vitro, and assesses potential changes in formation during freeze-thaw cycles. Systems were subjected to multiple freeze-thaw cycles from +10 deg. C to -20 deg. C and then analysed by X-ray diffractometry. Pyromorphite formed in all systems and was stable over multiple freeze-thaw cycles. Low temperature lead orthophosphate reaction efficiency varied according to both phosphate and lead source; the most time-efficient pyromorphite formation was observed when PbSO 4 and Na 3 PO 4 were present together. These findings have implications for the manner in which metal contaminated materials in freezing ground can be treated with phosphate. - Highlights: → Formation of lead phosphate products in cold environments is identified. → Potential change in formation during freeze-thaw cycling is assessed. → Lead phosphate reaction efficiency varies according to phosphate and lead source. → Pyromorphite formation is stable during 240 freeze-thaw cycles. - Pyromorphite, formed from Pb phosphate fixation, is stable during multiple freeze-thaw cycles but the efficiency of the fixation depends on the phosphate source and the type of Pb mineral.
Ion-beam-induced reactions in metal-thin-film-/BP system

International Nuclear Information System (INIS)

Kobayashi, N.; Kumashiro, Y.; Revesz, P.; Mayer, J.W.

1989-01-01

Ion-beam-induced reactions in Ni thin films on BP(100) have been investigated and compared with the results of the thermal reaction. The full reaction of Ni layer with BP induced by energetic heavy ion bombardments (600 keV Xe) was observed at 200degC and the formation of the crystalline phase corresponding to a composition of Ni 4 BP was observed. Amorphous layer with the same composition was formed by the bombardments below RT. For thermally annealed samples the reaction of the Ni layer on BP started at temperatures between 350degC and 400degC and full reaction was observed at 450degC. Metal-rich ternary phase or mixed binary phase is thought to be the first crystalline phase formed both in the ion-beam-induced and in the thermally induced reactions. The crystalline phase has the same composition and X-ray diffraction pattern both for ion-beam-induced and thermal reactions. Linear dependence of the reacted thickness on the ion fluence was also observed. The authors would like to express their sincere gratitude to Jian Li and Shi-Qing Wang for X-ray diffraction measurements at Cornell University. One of the authors (N.K.) acknowledge the Agency of Science and Technology of Japan for the financial support of his stay at Cornell. We also acknowledge Dr. H. Tanoue at ETL for his help in ion bombardment experiments. (author)
Dynamics of the fusion reaction in the dtμ- system

International Nuclear Information System (INIS)

Belyaev, V.B.; Revai, J.; Zubarev, A.L.

1988-08-01

A dynamical scheme based on the (td,αn) two-channel model is derived for the description of the fusion reaction in the dtμ - system. Special attention is paid to the correct specification of the final states. Several possibilities are pointed out for the systematic improvement of the sudden approximation for the sticking coefficient. It seems to be useful to outline a general formulation of these processes which would allow a clear comparison of existing approaches. The lack of satisfactory agreement between experimental and theoretical values of the sticking coefficient is a further argument in favour of the programme. (R.P.) 10 refs
Pd@[nBu₄][Br] as a Simple Catalytic System for N-Alkylation Reactions with Alcohols.

Science.gov (United States)

Cacciuttolo, Bastien; Pascu, Oana; Aymonier, Cyril; Pucheault, Mathieu

2016-08-10

Palladium nanoparticles, simply and briefly generated in commercial and cheap onium salts using supercritical carbon dioxide, have been found to be an effective catalytic system for additive free N-alkylation reaction using alcohols via cascade oxidation/condensation/reduction steps.
Tattoo reaction: Case series

Directory of Open Access Journals (Sweden)

Muneer Mohamed

2018-04-01

Full Text Available Tattoo is going to be a very common practice especially among young people and we are witnessing a gradual increase of numerous potential complications to tattoo placement which are often seen by physicians, but generally unknown to the public. The most common skin reactions to tattoo include a transient acute inflammatory reaction due to trauma of the skin with needles and medical complications such as superficial and deep local infections, systemic infections, allergic contact dermatitis, photodermatitis, granulomatous and lichenoid reactions, and skin diseases localized on tattooed area (eczema, psoriasis, lichen, and morphea. In this series we present three cases of tattoo reaction.
Fast Neutral reactions in cold interstellar clouds

International Nuclear Information System (INIS)

Graff, M.M.

1989-01-01

The dynamics of exothermic neutral reactions between radical species have been examined, with particular attention to reactivity at the very low energies characteristic of cold interstellar clouds. Long-range interactions (electrostatic and spin-orbit) were considered within in the adiabatic capture-infinite order sudden approximation (ACIOSA). Analytic expressions have been developed for cross sections and rate constants of exothermic reactions between atoms and dipolar radicals at low temperatures. A method for approximating the adiabatic potential surface for the reactive state will be presented. The reaction systems O+OH and O+CH are both predicted to be fast at low temperatures. The systems C+CH and C+OH are expected to be nonreactive at low temperatures, and upper limits of rate constants for these reactions have been estimated. General predictions are made for other reaction systems. Implications for interstellar chemistry will be discussed
Continuous thermal degradation of pyrolytic oil in a bench scale CSTR reaction system

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyong Hwan; Nam, Ki Yun [Climate Change Technology Research Division, Korea Institute of Energy Research, 102 Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea)

2010-05-15

Continuous thermal degradation of two pyrolytic oils with low (LPO) and high boiling point distribution (HPO) was conducted in a constant stirrer tank reactor (CSTR) with bench scale. Raw pyrolytic oil as a reactant was obtained from the commercial rotary kiln pyrolysis plant for municipal plastic waste. The degradation experiment was conducted by temperature programming with 10 C/min of heating rate up to 450 C and then maintained with long lapse time at 450 C. Liquid product was sampled at initial reaction time with different degradation temperatures up to 450 C and then constant interval lapse time at 450 C. The product characteristics over two pyrolytic oils were compared by using a continuous reaction system. As a reactant, heavy pyrolytic oil (HPO) showed higher boiling point distribution than that of diesel and also light pyrolytic oil (LPO) was mainly consisting of a mixture of gasoline and kerosene range components. In the continuous reaction, LPO showed higher yield of liquid product and lower residue than those of HPO. The characteristics of liquid products were influenced by the type of raw pyrolytic oil. Also, the result obtained under degradation temperature programming was described. (author)
Elastic scattering and total reaction cross section for the 6He +58Ni system

Science.gov (United States)

Morcelle, V.; Lichtenthäler, R.; Lépine-Szily, A.; Guimarães, V.; Mendes, D. R., Jr.; Pires, K. C. C.; de Faria, P. N.; Barioni, A.; Gasques, L.; Morais, M. C.; Shorto, J. M. B.; Zamora, J. C.; Scarduelli, V.; Condori, R. Pampa; Leistenschneider, E.

2014-11-01

Elastic scattering measurements of 6He + 58Ni system have been performed at the laboratory energy of 21.7 MeV. The 6He secondary beam was produced by a transfer reaction 9Be (7Li , 6He ) and impinged on 58Ni and 197Au targets, using the Radioactive Ion Beam (RIB) facility, RIBRAS, installed in the Pelletron Laboratory of the Institute of Physics of the University of São Paulo, Brazil. The elastic angular distribution was obtained in the angular range from 15° to 80° in the center of mass frame. Optical model calculations have been performed using a hybrid potential to fit the experimental data. The total reaction cross section was derived.
Computer-assisted design for scaling up systems based on DNA reaction networks.

Science.gov (United States)

Aubert, Nathanaël; Mosca, Clément; Fujii, Teruo; Hagiya, Masami; Rondelez, Yannick

2014-04-06

In the past few years, there have been many exciting advances in the field of molecular programming, reaching a point where implementation of non-trivial systems, such as neural networks or switchable bistable networks, is a reality. Such systems require nonlinearity, be it through signal amplification, digitalization or the generation of autonomous dynamics such as oscillations. The biochemistry of DNA systems provides such mechanisms, but assembling them in a constructive manner is still a difficult and sometimes counterintuitive process. Moreover, realistic prediction of the actual evolution of concentrations over time requires a number of side reactions, such as leaks, cross-talks or competitive interactions, to be taken into account. In this case, the design of a system targeting a given function takes much trial and error before the correct architecture can be found. To speed up this process, we have created DNA Artificial Circuits Computer-Assisted Design (DACCAD), a computer-assisted design software that supports the construction of systems for the DNA toolbox. DACCAD is ultimately aimed to design actual in vitro implementations, which is made possible by building on the experimental knowledge available on the DNA toolbox. We illustrate its effectiveness by designing various systems, from Montagne et al.'s Oligator or Padirac et al.'s bistable system to new and complex networks, including a two-bit counter or a frequency divider as well as an example of very large system encoding the game Mastermind. In the process, we highlight a variety of behaviours, such as enzymatic saturation and load effect, which would be hard to handle or even predict with a simpler model. We also show that those mechanisms, while generally seen as detrimental, can be used in a positive way, as functional part of a design. Additionally, the number of parameters included in these simulations can be large, especially in the case of complex systems. For this reason, we included the
Spallation reactions - physics and applications

International Nuclear Information System (INIS)

Kelic, A.; Ricciardi, M.; Schmidt, K-H.

2009-01-01

Spallation reactions have become an ideal tool for studying the equation of state and thermal instabilities of nuclear matter. In astrophysics, the interactions of cosmic rays with the interstellar medium have to be understood in detail for deducing their original composition and their production mechanisms. Renewed interest in spallation reactions with protons around 1 GeV came up recently with the developments of spallation neutron sources. The project of an accelerator-driven system (ADS) as a technological solution for incinerating the radioactive waste even intensified the efforts for better understanding the physics involved in the spallation process. Experiments on spallation reactions were performed for determining the production cross sections and properties of particles, fragments and heavy residues. Traditional experiments on heavy residues, performed in direct kinematics, were limited to the direct observation of long-lived radioactive nuclides and did not provide detailed information on the kinematics of the reaction. Therefore, an innovative experimental method has been developed, based on inverse kinematics, which allowed to identify all reaction residues in-flight, using the high resolution magnetic spectrometer FRS of GSL Darmstadt. It also gives direct access to the reaction kinematics. An experimental campaign has been carried out in a Europe-wide collaboration, investigating the spallation of several nuclei ranging from 56 Fe to 238 U Complementary experiments were performed with a full-acceptance detection system, yielding total fission cross sections. Recently, another detection system using the large acceptance ALADIN dipole and the LAND neutron detector was introduced to measure light particles in coincidence with the heavy residues. Another intense activity was dedicated to developing codes, which cover nuclear reactions occurring in an ADS. The first phase of the reaction is successfully described by a sequence of quasi-free nucleon
Palladium-catalyzed coupling reactions

CERN Document Server

Molnár, Árpád

2013-01-01

This handbook and ready reference brings together all significant issues of practical importance for interested readers in one single volume. While covering homogeneous and heterogeneous catalysis, the text is unique in focusing on such important aspects as using different reaction media, microwave techniques or catalyst recycling. It also provides a comprehensive treatment of modern-day coupling reactions and emphasizes those topics that show potential for future development, such as continuous flow systems, water as a reaction medium, and catalyst immobilization, among others. With i
Modelling human behaviours and reactions under dangerous environment

OpenAIRE

Kang, J; Wright, D K; Qin, S F; Zhao, Y

2005-01-01

This paper describes the framework of a real-time simulation system to model human behavior and reactions in dangerous environments. The system utilizes the latest 3D computer animation techniques, combined with artificial intelligence, robotics and psychology, to model human behavior, reactions and decision making under expected/unexpected dangers in real-time in virtual environments. The development of the system includes: classification on the conscious/subconscious behaviors and reactions...
Redox reactions in micellar systems. communication 4. Eosin-photosensitized reduction of methylviologen

Energy Technology Data Exchange (ETDEWEB)

Nadtochenko, V.; Dzhabiev, T.S.; Rubtsov, I.V.

1985-12-10

The authors present data on photosensitized reduction of methylviologen (MV/sup 2 +/) by disodium ethylenediaminetetraacetate (EDTA) in micellar systems modeling, in a first approximation, the structural organization of components of the chain of energy and electron transfer in natural photosynthesis. Photosensitized reduction of methylviologen by EDTA in micellar solutions can model photosystem I of plants with structure formation of reagents and transfer of excitation energy before the step of occurrence of a redox reaction in the active center.
Reaction of the hemocoagulation system to tissue hypoxia in patients with chronic obstructive pulmonary disease

Directory of Open Access Journals (Sweden)

Anna A. Bulanova

2017-01-01

Full Text Available Background. Nowadays little data related to the hemostatic system and fibrinolysis in patients with chronic obstructive pulmonary disease (COPD are available. This is due to the lack of standardized methods for studying the hemostasis system, as well as to the lack of a single functional test that allows the evaluation of the complete fibrinogenesis cycle in whole blood.Aim. The aim of our study was to develop a functional test capable of analyzing the blood gas composition in the “point-of-care test” method for the evaluation of the hemostatic potential in patients with COPD, based on a standardized test stimulus, which is tissue hypoxia. The current level of clinical and laboratory diagnostics requires personification and research of the hemo-coagulation system in real time (point-of-care test, which allows low-frequency piezotromboelastography(NVTEG to be performed.Materials and methods. NVTEG was chosen to estimate the state of the hemocoagulation system. Ten patients with COPD and 10 healthy volunteers were examined. Hypoxia was selected as a standardized test stimulus. Hypoxia conditions were caused by smoking one standard cigarette (composition: resin 10 mg/cig., nicotine 0,7 mg/cig., CO 10 mg/cig.. The degree of tissue hypoxia was assessed with the GASTAT-navi blood gas analyzer.Results. The study has shown that in response to the standard test stimulus, which is the tissue hypoxia caused by smoking of a standardized cigarette, two types of haemostatic potential reaction were detected both in patients with COPD and healthy volunteers. The first type of reaction – “hypercoagulation” – is characterized by the formation of chronometric and structural hypercoagulation at all stages of fibrinogenesis and increased coagulation activity by 25–30% compared with the response in healthy individuals. The second type of reaction – “hypocoagulation” – is characterized by the formation of chronometric and structural
Nuclear reactions of the system 6 Li on 58 Ni near the Coulomb barrier

International Nuclear Information System (INIS)

Lizcano, D.; Aguilera, E.F.; Garcia M, H.; Martinez Q, E.

2004-01-01

Protons, alpha particles and deuterons coming from the reactions 6 Li + 58 Ni are detected to three different energy around the Coulomb barrier. The possible effects of the weakly bound character of the projectile are studied and the results are compared with previous data for the system 6 Li + 59 Co. (Author)
Heterogeneity induces spatiotemporal oscillations in reaction-diffusion systems

Science.gov (United States)

Krause, Andrew L.; Klika, Václav; Woolley, Thomas E.; Gaffney, Eamonn A.

2018-05-01

We report on an instability arising in activator-inhibitor reaction-diffusion (RD) systems with a simple spatial heterogeneity. This instability gives rise to periodic creation, translation, and destruction of spike solutions that are commonly formed due to Turing instabilities. While this behavior is oscillatory in nature, it occurs purely within the Turing space such that no region of the domain would give rise to a Hopf bifurcation for the homogeneous equilibrium. We use the shadow limit of the Gierer-Meinhardt system to show that the speed of spike movement can be predicted from well-known asymptotic theory, but that this theory is unable to explain the emergence of these spatiotemporal oscillations. Instead, we numerically explore this system and show that the oscillatory behavior is caused by the destabilization of a steady spike pattern due to the creation of a new spike arising from endogeneous activator production. We demonstrate that on the edge of this instability, the period of the oscillations goes to infinity, although it does not fit the profile of any well-known bifurcation of a limit cycle. We show that nearby stationary states are either Turing unstable or undergo saddle-node bifurcations near the onset of the oscillatory instability, suggesting that the periodic motion does not emerge from a local equilibrium. We demonstrate the robustness of this spatiotemporal oscillation by exploring small localized heterogeneity and showing that this behavior also occurs in the Schnakenberg RD model. Our results suggest that this phenomenon is ubiquitous in spatially heterogeneous RD systems, but that current tools, such as stability of spike solutions and shadow-limit asymptotics, do not elucidate understanding. This opens several avenues for further mathematical analysis and highlights difficulties in explaining how robust patterning emerges from Turing's mechanism in the presence of even small spatial heterogeneity.
Carbonylative Heck Reactions Using CO Generated ex Situ in a Two-Chamber System

DEFF Research Database (Denmark)

Hermange, Philippe; Gøgsig, Thomas; Lindhardt, Anders Thyboe

2011-01-01

A carbonylative Heck reaction of aryl iodides and styrene derivatives employing a two-chamber system using a stable, crystalline, and nontransition metal based carbon monoxide source is reported. By applying near-stoichiometric amounts of the carbon monoxide precursor, an effective exploitation o...... of the hazardous CO gas is obtained affording chalcone derivatives in good yields. Application to isotope labeling, incorporating 13CO, was further established....

Designing driver assistance systems with crossmodal signals: multisensory integration rules for saccadic reaction times apply.

Directory of Open Access Journals (Sweden)

Rike Steenken

Full Text Available Modern driver assistance systems make increasing use of auditory and tactile signals in order to reduce the driver's visual information load. This entails potential crossmodal interaction effects that need to be taken into account in designing an optimal system. Here we show that saccadic reaction times to visual targets (cockpit or outside mirror, presented in a driving simulator environment and accompanied by auditory or tactile accessories, follow some well-known spatiotemporal rules of multisensory integration, usually found under confined laboratory conditions. Auditory nontargets speed up reaction time by about 80 ms. The effect tends to be maximal when the nontarget is presented 50 ms before the target and when target and nontarget are spatially coincident. The effect of a tactile nontarget (vibrating steering wheel was less pronounced and not spatially specific. It is shown that the average reaction times are well-described by the stochastic "time window of integration" model for multisensory integration developed by the authors. This two-stage model postulates that crossmodal interaction occurs only if the peripheral processes from the different sensory modalities terminate within a fixed temporal interval, and that the amount of crossmodal interaction manifests itself in an increase or decrease of second stage processing time. A qualitative test is consistent with the model prediction that the probability of interaction, but not the amount of crossmodal interaction, depends on target-nontarget onset asynchrony. A quantitative model fit yields estimates of individual participants' parameters, including the size of the time window. Some consequences for the design of driver assistance systems are discussed.
Products and stability of phosphate reactions with lead under freeze-thaw cycling in simple systems

Energy Technology Data Exchange (ETDEWEB)

Hafsteinsdottir, Erla G., E-mail: erla.hafsteinsdottir@gmail.com [Department of Environment and Geography, Macquarie University, NSW 2109 (Australia); White, Duanne A., E-mail: duanne.white@mq.edu.au [Department of Environment and Geography, Macquarie University, NSW 2109 (Australia); Gore, Damian B., E-mail: damian.gore@mq.edu.au [Department of Environment and Geography, Macquarie University, NSW 2109 (Australia); Stark, Scott C., E-mail: scott.stark@aad.gov.au [Environmental Protection and Change, Australian Antarctic Division, Department of Sustainability, Environment, Water, Population and Communities, Tasmania 7050 (Australia)

2011-12-15

Orthophosphate fixation of metal contaminated soils in environments that undergo freeze-thaw cycles is understudied. Freeze-thaw cycling potentially influences the reaction rate, mineral chemical stability and physical breakdown of particles during fixation. This study determines what products form when phosphate (triple superphosphate [Ca(H{sub 2}PO{sub 4}){sub 2}] or sodium phosphate [Na{sub 3}PO{sub 4}]) reacts with lead (PbSO{sub 4} or PbCl{sub 2}) in simple chemical systems in vitro, and assesses potential changes in formation during freeze-thaw cycles. Systems were subjected to multiple freeze-thaw cycles from +10 deg. C to -20 deg. C and then analysed by X-ray diffractometry. Pyromorphite formed in all systems and was stable over multiple freeze-thaw cycles. Low temperature lead orthophosphate reaction efficiency varied according to both phosphate and lead source; the most time-efficient pyromorphite formation was observed when PbSO{sub 4} and Na{sub 3}PO{sub 4} were present together. These findings have implications for the manner in which metal contaminated materials in freezing ground can be treated with phosphate. - Highlights: > Formation of lead phosphate products in cold environments is identified. > Potential change in formation during freeze-thaw cycling is assessed. > Lead phosphate reaction efficiency varies according to phosphate and lead source. > Pyromorphite formation is stable during 240 freeze-thaw cycles. - Pyromorphite, formed from Pb phosphate fixation, is stable during multiple freeze-thaw cycles but the efficiency of the fixation depends on the phosphate source and the type of Pb mineral.
Development of interactive graphic user interfaces for modeling reaction-based biogeochemical processes in batch systems with BIOGEOCHEM

Science.gov (United States)

Chang, C.; Li, M.; Yeh, G.

2010-12-01

The BIOGEOCHEM numerical model (Yeh and Fang, 2002; Fang et al., 2003) was developed with FORTRAN for simulating reaction-based geochemical and biochemical processes with mixed equilibrium and kinetic reactions in batch systems. A complete suite of reactions including aqueous complexation, adsorption/desorption, ion-exchange, redox, precipitation/dissolution, acid-base reactions, and microbial mediated reactions were embodied in this unique modeling tool. Any reaction can be treated as fast/equilibrium or slow/kinetic reaction. An equilibrium reaction is modeled with an implicit finite rate governed by a mass action equilibrium equation or by a user-specified algebraic equation. A kinetic reaction is modeled with an explicit finite rate with an elementary rate, microbial mediated enzymatic kinetics, or a user-specified rate equation. None of the existing models has encompassed this wide array of scopes. To ease the input/output learning curve using the unique feature of BIOGEOCHEM, an interactive graphic user interface was developed with the Microsoft Visual Studio and .Net tools. Several user-friendly features, such as pop-up help windows, typo warning messages, and on-screen input hints, were implemented, which are robust. All input data can be real-time viewed and automated to conform with the input file format of BIOGEOCHEM. A post-processor for graphic visualizations of simulated results was also embedded for immediate demonstrations. By following data input windows step by step, errorless BIOGEOCHEM input files can be created even if users have little prior experiences in FORTRAN. With this user-friendly interface, the time effort to conduct simulations with BIOGEOCHEM can be greatly reduced.
A plant chamber system with downstream reaction chamber to study the effects of pollution on biogenic emissions.

Science.gov (United States)

Timkovsky, J; Gankema, P; Pierik, R; Holzinger, R

2014-01-01

A system of two plant chambers and a downstream reaction chamber has been set up to investigate the emission of biogenic volatile organic compounds (BVOCs) and possible effects of pollutants such as ozone. The system can be used to compare BVOC emissions from two sets of differently treated plants, or to study the photochemistry of real plant emissions under polluted conditions without exposing the plants to pollutants. The main analytical tool is a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) which allows online monitoring of biogenic emissions and chemical degradation products. The identification of BVOCs and their oxidation products is aided by cryogenic trapping and subsequent in situ gas chromatographic analysis.
Thermally multiplexed polymerase chain reaction.

Science.gov (United States)

Phaneuf, Christopher R; Pak, Nikita; Saunders, D Curtis; Holst, Gregory L; Birjiniuk, Joav; Nagpal, Nikita; Culpepper, Stephen; Popler, Emily; Shane, Andi L; Jerris, Robert; Forest, Craig R

2015-07-01

Amplification of multiple unique genetic targets using the polymerase chain reaction (PCR) is commonly required in molecular biology laboratories. Such reactions are typically performed either serially or by multiplex PCR. Serial reactions are time consuming, and multiplex PCR, while powerful and widely used, can be prone to amplification bias, PCR drift, and primer-primer interactions. We present a new thermocycling method, termed thermal multiplexing, in which a single heat source is uniformly distributed and selectively modulated for independent temperature control of an array of PCR reactions. Thermal multiplexing allows amplification of multiple targets simultaneously-each reaction segregated and performed at optimal conditions. We demonstrate the method using a microfluidic system consisting of an infrared laser thermocycler, a polymer microchip featuring 1 μl, oil-encapsulated reactions, and closed-loop pulse-width modulation control. Heat transfer modeling is used to characterize thermal performance limitations of the system. We validate the model and perform two reactions simultaneously with widely varying annealing temperatures (48 °C and 68 °C), demonstrating excellent amplification. In addition, to demonstrate microfluidic infrared PCR using clinical specimens, we successfully amplified and detected both influenza A and B from human nasopharyngeal swabs. Thermal multiplexing is scalable and applicable to challenges such as pathogen detection where patients presenting non-specific symptoms need to be efficiently screened across a viral or bacterial panel.
Vorticity field, helicity integral and persistence of entanglement in reaction-diffusion systems

International Nuclear Information System (INIS)

Trueba, J L; Arrayas, M

2009-01-01

We show that a global description of the stability of entangled structures in reaction-diffusion systems can be made by means of a helicity integral. A vorticity vector field is defined for these systems, as in electromagnetism or fluid dynamics. We have found under which conditions the helicity is conserved or lost through the boundaries of the medium, so the entanglement of structures observed is preserved or disappears during time evolution. We illustrate the theory with an example of knotted entanglement in a FitzHugh-Nagumo model. For this model, we introduce new non-trivial initial conditions using the Hopf fibration and follow the time evolution of the entanglement. (fast track communication)
Vorticity field, helicity integral and persistence of entanglement in reaction-diffusion systems

Energy Technology Data Exchange (ETDEWEB)

Trueba, J L; Arrayas, M [Area de Electromagnetismo, Universidad Rey Juan Carlos, Camino del Molino s/n, 28943 Fuenlabrada, Madrid (Spain)

2009-07-17

We show that a global description of the stability of entangled structures in reaction-diffusion systems can be made by means of a helicity integral. A vorticity vector field is defined for these systems, as in electromagnetism or fluid dynamics. We have found under which conditions the helicity is conserved or lost through the boundaries of the medium, so the entanglement of structures observed is preserved or disappears during time evolution. We illustrate the theory with an example of knotted entanglement in a FitzHugh-Nagumo model. For this model, we introduce new non-trivial initial conditions using the Hopf fibration and follow the time evolution of the entanglement. (fast track communication)
A Comparison of Deterministic and Stochastic Modeling Approaches for Biochemical Reaction Systems: On Fixed Points, Means, and Modes.

Science.gov (United States)

Hahl, Sayuri K; Kremling, Andreas

2016-01-01

In the mathematical modeling of biochemical reactions, a convenient standard approach is to use ordinary differential equations (ODEs) that follow the law of mass action. However, this deterministic ansatz is based on simplifications; in particular, it neglects noise, which is inherent to biological processes. In contrast, the stochasticity of reactions is captured in detail by the discrete chemical master equation (CME). Therefore, the CME is frequently applied to mesoscopic systems, where copy numbers of involved components are small and random fluctuations are thus significant. Here, we compare those two common modeling approaches, aiming at identifying parallels and discrepancies between deterministic variables and possible stochastic counterparts like the mean or modes of the state space probability distribution. To that end, a mathematically flexible reaction scheme of autoregulatory gene expression is translated into the corresponding ODE and CME formulations. We show that in the thermodynamic limit, deterministic stable fixed points usually correspond well to the modes in the stationary probability distribution. However, this connection might be disrupted in small systems. The discrepancies are characterized and systematically traced back to the magnitude of the stoichiometric coefficients and to the presence of nonlinear reactions. These factors are found to synergistically promote large and highly asymmetric fluctuations. As a consequence, bistable but unimodal, and monostable but bimodal systems can emerge. This clearly challenges the role of ODE modeling in the description of cellular signaling and regulation, where some of the involved components usually occur in low copy numbers. Nevertheless, systems whose bimodality originates from deterministic bistability are found to sustain a more robust separation of the two states compared to bimodal, but monostable systems. In regulatory circuits that require precise coordination, ODE modeling is thus still
On the graph and systems analysis of reversible chemical reaction networks with mass action kinetics

NARCIS (Netherlands)

Rao, Shodhan; Jayawardhana, Bayu; Schaft, Arjan van der

2012-01-01

Motivated by the recent progresses on the interplay between the graph theory and systems theory, we revisit the analysis of reversible chemical reaction networks described by mass action kinetics by reformulating it using the graph knowledge of the underlying networks. Based on this formulation, we
Critical behavior in reaction-diffusion systems exhibiting absorbing phase transition

CERN Document Server

Ódor, G

2003-01-01

Phase transitions of reaction-diffusion systems with site occupation restriction and with particle creation that requires n>1 parents and where explicit diffusion of single particles (A) exists are reviewed. Arguments based on mean-field approximation and simulations are given which support novel kind of non-equilibrium criticality. These are in contradiction with the implications of a suggested phenomenological, multiplicative noise Langevin equation approach and with some of recent numerical analysis. Simulation results for the one and two dimensional binary spreading 2A -> 4A, 4A -> 2A model display a new type of mean-field criticality characterized by alpha=1/3 and beta=1/2 critical exponents suggested in cond-mat/0210615.
Multi-scale simulation of reaction-diffusion systems

NARCIS (Netherlands)

Vijaykumar, A.

2017-01-01

In many reaction-diffusion processes, ranging from biochemical networks, catalysis, to complex self-assembly, the spatial distribution of the reactants and the stochastic character of their interactions are crucial for the macroscopic behavior. The recently developed mesoscopic Green’s Function
A plant chamber system with downstream reaction chamber to study the effects of pollution on biogenic emissions

NARCIS (Netherlands)

Timovsky, J.; Gankema, Paulien; Pierik, Ronald; Holzinger, Rupert

2014-01-01

A system of two plant chambers and a downstream reaction chamber has been set up to investigate the emission of biogenic volatile organic compounds (BVOCs) and possible effects of pollutants such as ozone. The system can be used to compare BVOC emissions from two sets of differently treated plants,
Insights into the mechanisms on chemical reactions: reaction paths for chemical reactions

International Nuclear Information System (INIS)

Dunning, T.H. Jr.; Rosen, E.; Eades, R.A.

1987-01-01

We report reaction paths for two prototypical chemical reactions: Li + HF, an electron transfer reaction, and OH + H 2 , an abstraction reaction. In the first reaction we consider the connection between the energetic terms in the reaction path Hamiltonian and the electronic changes which occur upon reaction. In the second reaction we consider the treatment of vibrational effects in chemical reactions in the reaction path formalism. 30 refs., 9 figs
Distributed order reaction-diffusion systems associated with Caputo derivatives

Science.gov (United States)

Saxena, R. K.; Mathai, A. M.; Haubold, H. J.

2014-08-01

This paper deals with the investigation of the solution of an unified fractional reaction-diffusion equation of distributed order associated with the Caputo derivatives as the time-derivative and Riesz-Feller fractional derivative as the space-derivative. The solution is derived by the application of the joint Laplace and Fourier transforms in compact and closed form in terms of the H-function. The results derived are of general nature and include the results investigated earlier by other authors, notably by Mainardi et al. ["The fundamental solution of the space-time fractional diffusion equation," Fractional Calculus Appl. Anal. 4, 153-202 (2001); Mainardi et al. "Fox H-functions in fractional diffusion," J. Comput. Appl. Math. 178, 321-331 (2005)] for the fundamental solution of the space-time fractional equation, including Haubold et al. ["Solutions of reaction-diffusion equations in terms of the H-function," Bull. Astron. Soc. India 35, 681-689 (2007)] and Saxena et al. ["Fractional reaction-diffusion equations," Astrophys. Space Sci. 305, 289-296 (2006a)] for fractional reaction-diffusion equations. The advantage of using the Riesz-Feller derivative lies in the fact that the solution of the fractional reaction-diffusion equation, containing this derivative, includes the fundamental solution for space-time fractional diffusion, which itself is a generalization of fractional diffusion, space-time fraction diffusion, and time-fractional diffusion, see Schneider and Wyss ["Fractional diffusion and wave equations," J. Math. Phys. 30, 134-144 (1989)]. These specialized types of diffusion can be interpreted as spatial probability density functions evolving in time and are expressible in terms of the H-function in compact forms. The convergence conditions for the double series occurring in the solutions are investigated. It is interesting to observe that the double series comes out to be a special case of the Srivastava-Daoust hypergeometric function of two variables
Modeling of fluctuating reaction networks

International Nuclear Information System (INIS)

Lipshtat, A.; Biham, O.

2004-01-01

Full Text:Various dynamical systems are organized as reaction networks, where the population size of one component affects the populations of all its neighbors. Such networks can be found in interstellar surface chemistry, cell biology, thin film growth and other systems. I cases where the populations of reactive species are large, the network can be modeled by rate equations which provide all reaction rates within mean field approximation. However, in small systems that are partitioned into sub-micron size, these populations strongly fluctuate. Under these conditions rate equations fail and the master equation is needed for modeling these reactions. However, the number of equations in the master equation grows exponentially with the number of reactive species, severely limiting its feasibility for complex networks. Here we present a method which dramatically reduces the number of equations, thus enabling the incorporation of the master equation in complex reaction networks. The method is examplified in the context of reaction network on dust grains. Its applicability for genetic networks will be discussed. 1. Efficient simulations of gas-grain chemistry in interstellar clouds. Azi Lipshtat and Ofer Biham, Phys. Rev. Lett. 93 (2004), 170601. 2. Modeling of negative autoregulated genetic networks in single cells. Azi Lipshtat, Hagai B. Perets, Nathalie Q. Balaban and Ofer Biham, Gene: evolutionary genomics (2004), In press
Design and Stability of an On-Orbit Attitude Control System Using Reaction Control Thrusters

Science.gov (United States)

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

2016-01-01

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

DEFF Research Database (Denmark)

Christensen, H.; Kiil, Søren; Dam-Johansen, Kim

2006-01-01

The Buchwald-Hartwig amination reaction between p-bromotoluene and piperazine in the presence of the homogeneous catalytic system Pd(dba)(2)/(+/-)-BINAP and the base NaO-t-Bu was investigated in two different classes of solvents: aprotic, nonpolar and aprotic, polar. The reaction was carried out...... solvent for the Buchwald-Hartwig amination reaction under the conditions applied was m-xylene....
The thermodynamic assessment of the As-Pt system and the analysis of the Pt/GaAs interfacial reactions

International Nuclear Information System (INIS)

Li, Mei; Li, Changrong; Wang, Fuming; Zhang, Weijing

2007-01-01

In order to analyze the Pt/GaAs interfacial reaction sequence, the As-Pt binary system was thermodynamically assessed. A consistent thermodynamic data set for the As-Pt binary system have been obtained by means of calculation of phase diagrams (CALPHAD) technology. The intermetallic compound, As 2 Pt, was treated as stoichiometric compound. The gas phase was treated as an ideal mixture. Using the present thermodynamic data set for the As-Pt system and the literatures reported ones for the Ga-Pt and As-Ga systems, the isothermal sections of the As-Ga-Pt system at different temperatures 873 and 298 K were constructed by extending the related binaries. The calculated phase diagrams reproduce the experimental results well. Based on the present optimized data and the phase equilibrium calculation, the interfacial reactions of (bulk Pt)/GaAs and (thin-film Pt)/GaAs couples were analyzed and the phase formation sequences were predicted. The calculation results agree well with the reported experiments
Multiresponse kinetic modelling of Maillard reaction and caramelisation in a heated glucose/wheat flour system.

Science.gov (United States)

Kocadağlı, Tolgahan; Gökmen, Vural

2016-11-15

The study describes the kinetics of the formation and degradation of α-dicarbonyl compounds in glucose/wheat flour system heated under low moisture conditions. Changes in the concentrations of glucose, fructose, individual free amino acids, lysine and arginine residues, glucosone, 1-deoxyglucosone, 3-deoxyglucosone, 3,4-dideoxyglucosone, 5-hydroxymethyl-2-furfural, glyoxal, methylglyoxal and diacetyl concentrations were determined to form a multiresponse kinetic model for isomerisation and degradation reactions of glucose. Degradation of Amadori product mainly produced 1-deoxyglucosone. Formation of 3-deoxyglucosone proceeded directly from glucose and also Amadori product degradation. Glyoxal formation was predominant from glucosone while methylglyoxal and diacetyl originated from 1-deoxyglucosone. Formation of 5-hydroxymethyl-2-furfural from fructose was found to be a key step. Multi-response kinetic modelling of Maillard reaction and caramelisation simultaneously indicated quantitatively predominant parallel and consecutive pathways and rate limiting steps by estimating the reaction rate constants. Copyright © 2016 Elsevier Ltd. All rights reserved.
Radiation reactions and care of the patient

International Nuclear Information System (INIS)

Lochhead, J.N.M.

1983-01-01

Many of the radiation reactions which may occur in patients following radiotherapy and the care of these reactions are described. These include the systemic reaction, reactions of the blood and skin, reactions occurring after treatment of the breast and chest wall, reactions after irradiation of the mouth and throat, intrathoracic tumours, the abdominal alimentary tract and pelvis, bone, the CNS and the eye. Patient care during the treatment of children and also during treatment using small sealed sources is also described. (U.K.)

Torus C-I field reversed theta-pinch at UNICAMP

International Nuclear Information System (INIS)

Machida, M.; Collares, M.P.; Honda, R.Y.; Sakanaka, P.H.; Scheid, V.H.B.

1984-01-01

The influence of multipole fields (octopole and quadrupole) on supressing the n=2 rotational instability, field reconnection, particle loss effects is studied, and the viability of transforming the theta-pinch from Campinas, Brazil (100Kv, 55Kj) to the field reversed theta-pinch with plasma translation program is analyzed. (E.G.) [pt
EQ6, a computer program for reaction path modeling of aqueous geochemical systems: Theoretical manual, user's guide, and related documentation (Version 7.0)

International Nuclear Information System (INIS)

Wolery, T.J.; Daveler, S.A.

1992-01-01

EQ6 is a FORTRAN computer program in the EQ3/6 software package (Wolery, 1979). It calculates reaction paths (chemical evolution) in reacting water-rock and water-rock-waste systems. Speciation in aqueous solution is an integral part of these calculations. EQ6 computes models of titration processes (including fluid mixing), irreversible reaction in closed systems, irreversible reaction in some simple kinds of open systems, and heating or cooling processes, as well as solve ''single-point'' thermodynamic equilibrium problems. A reaction path calculation normally involves a sequence of thermodynamic equilibrium calculations. Chemical evolution is driven by a set of irreversible reactions (i.e., reactions out of equilibrium) and/or changes in temperature and/or pressure. These irreversible reactions usually represent the dissolution or precipitation of minerals or other solids. The code computes the appearance and disappearance of phases in solubility equilibrium with the water. It finds the identities of these phases automatically. The user may specify which potential phases are allowed to form and which are not. There is an option to fix the fugacities of specified gas species, simulating contact with a large external reservoir. Rate laws for irreversible reactions may be either relative rates or actual rates. If any actual rates are used, the calculation has a time frame. Several forms for actual rate laws are programmed into the code. EQ6 is presently able to model both mineral dissolution and growth kinetics
EDITAR: a module for reaction rate editing and cross-section averaging within the AUS neutronics code system

International Nuclear Information System (INIS)

Robinson, G.S.

1986-03-01

The EDITAR module of the AUS neutronics code system edits one and two-dimensional flux data pools produced by other AUS modules to form reaction rates for materials and their constituent nuclides, and to average cross sections over space and energy. The module includes a Bsub(L) flux calculation for application to cell leakage. The STATUS data pool of the AUS system is used to enable the 'unsmearing' of fluxes and nuclide editing with minimal user input. The module distinguishes between neutron and photon groups, and printed reaction rates are formed accordingly. Bilinear weighting may be used to obtain material reactivity worths and to average cross sections. Bilinear weighting is at present restricted to diffusion theory leakage estimates made using mesh-average fluxes
Microfabricated sleeve devices for chemical reactions

Science.gov (United States)

Northrup, M. Allen

2003-01-01

A silicon-based sleeve type chemical reaction chamber that combines heaters, such as doped polysilicon for heating, and bulk silicon for convection cooling. The reaction chamber combines a critical ratio of silicon and non-silicon based materials to provide the thermal properties desired. For example, the chamber may combine a critical ratio of silicon and silicon nitride to the volume of material to be heated (e.g., a liquid) in order to provide uniform heating, yet low power requirements. The reaction chamber will also allow the introduction of a secondary tube (e.g., plastic) into the reaction sleeve that contains the reaction mixture thereby alleviating any potential materials incompatibility issues. The reaction chamber may be utilized in any chemical reaction system for synthesis or processing of organic, inorganic, or biochemical reactions, such as the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction, which are examples of a synthetic, thermal-cycling-based reaction. The reaction chamber may also be used in synthesis instruments, particularly those for DNA amplification and synthesis.
Adverse drug reactions reported by consumers for nervous system medications in Europe 2007 to 2011

DEFF Research Database (Denmark)

Aagaard, Lise; Hansen, Ebba Holme

2013-01-01

Reporting of adverse drug reactions (ADRs) has traditionally been the sole province of healthcare professionals. In the European Union, more countries have allowed consumers to report ADRs directly to the regulatory agencies. The aim of this study was to characterize ADRs reported by European...... consumer for nervous system medications....
Curved fronts in the Belousov-Zhabotinskii reaction-diffusion systems in R2

Science.gov (United States)

Niu, Hong-Tao; Wang, Zhi-Cheng; Bu, Zhen-Hui

2018-05-01

In this paper we consider a diffusion system with the Belousov-Zhabotinskii (BZ for short) chemical reaction. Following Brazhnik and Tyson [4] and Pérez-Muñuzuri et al. [45], who predicted V-shaped fronts theoretically and discovered V-shaped fronts by experiments respectively, we give a rigorous mathematical proof of their results. We establish the existence of V-shaped traveling fronts in R2 by constructing a proper supersolution and a subsolution. Furthermore, we establish the stability of the V-shaped front in R2.
Pickering interfacial catalysis for biphasic systems: from emulsion design to green reactions.

Science.gov (United States)

Pera-Titus, Marc; Leclercq, Loïc; Clacens, Jean-Marc; De Campo, Floryan; Nardello-Rataj, Véronique

2015-02-09

Pickering emulsions are surfactant-free dispersions of two immiscible fluids that are kinetically stabilized by colloidal particles. For ecological reasons, these systems have undergone a resurgence of interest to mitigate the use of synthetic surfactants and solvents. Moreover, the use of colloidal particles as stabilizers provides emulsions with original properties compared to surfactant-stabilized emulsions, microemulsions, and micellar systems. Despite these specific advantages, the application of Pickering emulsions to catalysis has been rarely explored. This Minireview describes very recent examples of hybrid and composite amphiphilic materials for the design of interfacial catalysts in Pickering emulsions with special emphasis on their assets and challenges for industrially relevant biphasic reactions in fine chemistry, biofuel upgrading, and depollution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Calculation of reaction energies and adiabatic temperatures for waste tank reactions

International Nuclear Information System (INIS)

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 2 O in place of N 2 are also considered, as are reactions where an excess of caustic is present. Oxidants other than nitrate and nitrite are considered briefly
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.
Rapid establishment of polymerase chain reaction-restriction ...

African Journals Online (AJOL)

RFLP) optimization reaction system for cpDNA in tea [Camellia sinensis (L.) O. Kuntze] was rapidly established. Results show that the optimal PCR reaction system was 100 ng template DNA, 200 μmolL-1 dNTPs, 1.5 mmolL-1 MgCl2, 50 ng primer, ...
Chemical reaction networks as a model to describe UVC- and radiolytically-induced reactions of simple compounds.

Science.gov (United States)

Dondi, Daniele; Merli, Daniele; Albini, Angelo; Zeffiro, Alberto; Serpone, Nick

2012-05-01

When a chemical system is submitted to high energy sources (UV, ionizing radiation, plasma sparks, etc.), as is expected to be the case of prebiotic chemistry studies, a plethora of reactive intermediates could form. If oxygen is present in excess, carbon dioxide and water are the major products. More interesting is the case of reducing conditions where synthetic pathways are also possible. This article examines the theoretical modeling of such systems with random-generated chemical networks. Four types of random-generated chemical networks were considered that originated from a combination of two connection topologies (viz., Poisson and scale-free) with reversible and irreversible chemical reactions. The results were analyzed taking into account the number of the most abundant products required for reaching 50% of the total number of moles of compounds at equilibrium, as this may be related to an actual problem of complex mixture analysis. The model accounts for multi-component reaction systems with no a priori knowledge of reacting species and the intermediates involved if system components are sufficiently interconnected. The approach taken is relevant to an earlier study on reactions that may have occurred in prebiotic systems where only a few compounds were detected. A validation of the model was attained on the basis of results of UVC and radiolytic reactions of prebiotic mixtures of low molecular weight compounds likely present on the primeval Earth.
Chemical effects of (n,2n) reactions on iodate and periodates systems

International Nuclear Information System (INIS)

Mendonca, J.M.A. de.

1975-12-01

The chemical consequences of (n,2n) reactions on cristalline sodium iodate and periodates were investigated measuring the initial yield and the post irradiation thermal annealing yields (90 0 C) of the separated fractions I - , IO 3 - and IO 4 - . NaIO 3 , NaIO 3 .H 2 O and NaIO 4 , Na 4 H 2 IO 6 , Na 4 I 2 O 9 .3H 2 O containing 127 I and 129 I, or both, were irradiated with 14 MeV neutrons. Results obtained show different effects for each system and that 126 I and 128 I isotopes keep the same behaviour in the irradiated compounds containing only α 127 I or 129 I and in compounds having both 127 I and 129 I. Neither isotope effect nor qualitative differences on thermal annealing at 90 0 C were observed. The annealed fractions in the three studied periodates were IO - 3 and IO - 4 . These results differ from the ones reported previously for (n,γ) reactions on the same compounds [pt
Traveling and Pinned Fronts in Bistable Reaction-Diffusion Systems on Networks

Science.gov (United States)

Kouvaris, Nikos E.; Kori, Hiroshi; Mikhailov, Alexander S.

2012-01-01

Traveling fronts and stationary localized patterns in bistable reaction-diffusion systems have been broadly studied for classical continuous media and regular lattices. Analogs of such non-equilibrium patterns are also possible in networks. Here, we consider traveling and stationary patterns in bistable one-component systems on random Erdös-Rényi, scale-free and hierarchical tree networks. As revealed through numerical simulations, traveling fronts exist in network-organized systems. They represent waves of transition from one stable state into another, spreading over the entire network. The fronts can furthermore be pinned, thus forming stationary structures. While pinning of fronts has previously been considered for chains of diffusively coupled bistable elements, the network architecture brings about significant differences. An important role is played by the degree (the number of connections) of a node. For regular trees with a fixed branching factor, the pinning conditions are analytically determined. For large Erdös-Rényi and scale-free networks, the mean-field theory for stationary patterns is constructed. PMID:23028746
The study of thermodynamic properties and transport properties of multicomponent systems with chemical reactions

Directory of Open Access Journals (Sweden)

Samujlov E.

2013-04-01

Full Text Available In case of system with chemical reaction the most important properties are heat conductivity and heat capacity. In this work we have considered the equation for estimate the component of these properties caused by chemical reaction and ionization processes. We have evaluated the contribution of this part in heat conductivity and heat capacity too. At the high temperatures contribution in heat conductivity from ionization begins to play an important role. We have created a model, which describe partial and full ionization of gases and gas mixtures. In addition, in this work we present the comparison of our result with experimental data and data from numerical simulation. We was used the data about transport properties of middle composition of Russian coals and the data of thermophysical properties of natural gas for comparison.
An experimental and theoretical study of reaction steps relevant to the methanol-to-hydrocarbons reaction

Energy Technology Data Exchange (ETDEWEB)

Svelle, Stian

2004-07-01

The primary objective of the present work is to obtain new insight into the reaction mechanism of the zeolite catalyzed methanol-to-hydrocarbons (MTH) reaction. It was decided to use both experimental and computational techniques to reach this goal. An investigation of the n-butene + methanol system was therefore initiated. Over time, it became apparent that it was possible to determine the rate for the methylation of n-butene by methanol. The ethene and propene systems were therefore reexamined in order to collect kinetic information also for those cases. With the development of user-friendly quantum chemistry programs such as the Gaussian suite of programs, the possibility of applying quantum chemical methods to many types of problems has become readily available even for non-experts. When performing mechanistic studies, there is quite often a considerable synergy effect when combining experimental and computational approaches. The methylation reactions mentioned above turned out to be an issue well suited for quantum chemical investigations. The incentive for examining the halomethane reactivity was the clear analogy to the MTH reaction system. Alkene dimerization was also a reaction readily examined with quantum chemistry. As discussed in the introduction of this thesis, polymethylbenzenes, or their cationic counterparts, are suspected to be key intermediates in the MTH reaction. It was therefore decided to investigate the intrinsic reactivity of these species in the gas-phase by employing sophisticated mass spectrometric (MS) techniques in collaboration with the MS group at the Department of Chemistry, University of Oslo The data thus obtained will also be compared with results from an ongoing computational study on gas phase polymethylbenzenium reactivity. 6 papers presenting various studies are included. The titles are: 1) A Theoretical Investigation of the Methylation of Alkenes with Methanol over Acidic Zeolites. 2) A Theoretical Investigation of the
The unified theory of nuclear reactions

International Nuclear Information System (INIS)

Tobocman, W.

A unified nuclear reaction theory is a formalism for the scattering reactions of many-body nuclear systems which is capable of describing both direct interaction and compound nucleus formation processes. The Feshbach projection operator formalism is the original unified nuclear reaction theory. An alternative unified nuclear reaction theory called the X-matrix formalism is described. The X-matrix formalism is a generalization of the Brown-de Dominicis formalism. It does not require projection operators and is readly applied to rearrangement collisions
Copper-Mediated Reactions of Nitriles with Nitromethanes: Aza-Henry Reactions and Nitrile Hydrations.

Science.gov (United States)

Kuwabara, Jun; Sawada, Yoshiharu; Yoshimatsu, Mitsuhiro

2018-02-16

In this study, the first aza-Henry reaction of nitriles with nitromethane in a CuI/Cs 2 CO 3 /DBU system is described. The process was conveniently and directly used for the synthesis of β-aminonitroalkenes 2a-x and tolerated aryl-, alkyl-, hetaryl-, alkenyl-, and alkynylnitriles. The resulting aminonitroalkenes 2 could be successfully transformed to the corresponding 2-nitroacetophenones, 2-amino-1-halonitroalkenes, 2-alkylaminonitroalkenes, or 3-nitropyridines. In the presence of H 2 O, the aza-Henry reaction turned the reaction path to the nitrile hydration to exclusively yield the amides 3a-s.
Isospin influence on the decay modes of the systems produced in the 78,86Kr +40,48Ca reactions at 10 AMeV

Directory of Open Access Journals (Sweden)

Gnoffo B.

2016-01-01

Full Text Available The results of the analysis of the reactions 78,86Kr +40,48 Ca at 10 AMeV are presented. The experiment was performed at the INFN Laboratori Nazionali del Sud (LNS in Catania by using the 4π multidetector CHIMERA, with beams delivered by the Superconductive Cyclotron. The competition among the various disintegration paths and in particular the isospin effects on the decay modes of the produced composite systems are investigated; this provides information about fundamental nuclear quantities such as level density, fission barrier and viscosity. Different isotopic composition and relative richness are observed among the reaction products of the two systems. An odd-even staggering effect is present in the charge distributions, in particular for the light fragments produced by the neutron-poor system. The kinematical characteristics of the IMF seem to indicate a high degree of the relaxation of the formed system. Besides, global features analysis seems to show some differences in the contribution arising from the various reaction mechanisms for the two reactions.
Pd@[nBu4][Br] as a Simple Catalytic System for N-Alkylation Reactions with Alcohols

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Bastien Cacciuttolo

2016-08-01

Full Text Available Palladium nanoparticles, simply and briefly generated in commercial and cheap onium salts using supercritical carbon dioxide, have been found to be an effective catalytic system for additive free N-alkylation reaction using alcohols via cascade oxidation/condensation/reduction steps.
Electromagnetic reactions of few-body systems with the Lorentz integral transform method

International Nuclear Information System (INIS)

Leidemann, W.

2007-01-01

Various electromagnetic few-body break-up reactions into the many-body continuum are calculated microscopically with the Lorentz integral transform (LIT) method. For three- and four-body nuclei the nuclear Hamiltonian includes two- and three-nucleon forces, while semirealistic interactions are used in case of six- and seven-body systems. Comparisons with experimental data are discussed. In addition various interesting aspects of the 4 He photodisintegration are studied: investigation of a tetrahedrical symmetry of 4 He and a test of non-local nuclear force models via the induced two-body currents

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

International Nuclear Information System (INIS)

Imre, K.; Odian, G.

1979-01-01

The effect of diffusion on radiation-initiated graft polymerization has been studied with emphasis on the single- and two-penetrant cases. When the physical properties of the penetrants are similar, the two-penetrant problems can be reduced to the single-penetrant problem by redefining the characteristic parameters of the system. The diffusion-free graft polymerization rate is assumed to be proportional to the upsilon power of the monomer concentration respectively, and, in which the proportionality constant a = k/sub p/R/sub i//sup w//k/sub t//sup z/, where k/sub p/ and k/sub t/ are the propagation and termination rate constants, respectively, and R/sub i/ is the initiation rate. The values of upsilon, w, and z depend on the particular reaction system. The results of earlier work were generalized by allowing a non-Fickian diffusion rate which predicts an essentially exponential dependence on the monomer concentration of the diffusion coefficient, D = D 0 [exp(deltaC/M)], where M is the saturation concentration. A reaction system is characterized by the three dimensionless parameters, upsilon, delta, and A = (L/2)[aM/sup (upsilon--1)//D 0 ]/sup 1/2/, where L is the polymer film thickness. Graft polymerization tends to become diffusion controlled as A increases. Larger values of delta and ν cause a reaction system to behave closer to the diffusion-free regime. Transition from diffusion-free to diffusion-controlled reaction involves changes in the dependence of the reaction rate on film thickness, initiation rate, and monomer concentration. Although the diffusion-free rate is w order in initiation rate, upsilon order in monomer, and independent of film thickness, the diffusion-controlled rate is w/2 order in initiator rate and inverse first-order in film thickness. Dependence of the diffusion-controlled rate on monomer is dependent in a complex manner on the diffusional characteristics of the reaction system. 11 figures, 4 tables
Reaction of Aldehydes/Ketones with Electron-Deficient 1,3,5-Triazines Leading to Functionalized Pyrimidines as Diels-Alder/Retro-Diels-Alder Reaction Products: Reaction Development and Mechanistic Studies.

Science.gov (United States)

Yang, Kai; Dang, Qun; Cai, Pei-Jun; Gao, Yang; Yu, Zhi-Xiang; Bai, Xu

2017-03-03

Catalytic inverse electron demand Diels-Alder (IEDDA) reactions of heterocyclic aza-dienes are rarely reported since highly reactive and electron-rich dienophiles are often found not compatible with strong acids such as Lewis acids. Herein, we disclose that TFA-catalyzed reactions of electron-deficient 1,3,5-triazines and electron-deficient aldehydes/ketones can take place. These reactions led to highly functionalized pyrimidines as products in fair to good yields. The reaction mechanism was carefully studied by the combination of experimental and computational studies. The reactions involve a cascade of stepwise inverse electron demand hetero-Diels-Alder (ihDA) reactions, followed by retro-Diels-Alder (rDA) reactions and elimination of water. An acid was required for both ihDA and rDA reactions. This mechanism was further verified by comparing the relative reactivity of aldehydes/ketones and their corresponding vinyl ethers in the current reaction system.
Reaction path simulations in multicomponent materials

International Nuclear Information System (INIS)

Seifert, H.J.

1999-01-01

The CALPHAD (calculation of phase diagrams) method is used in combination with selected experimental investigations to derive reaction paths in multicomponent systems. The method is illustrated by applying computerized thermodynamic databases and suitable software to explain quantitatively the thermal degradation of precursor-derived Si-C-N ceramics and the nitridation of titanium carbide. Reaction sequences in the Si 3 N 4 -SiC-TiC x N l-x -C-N system are illustrated by graphical representation of compatibility regions and indicated reaction paths. From these results the experimentally known microstructure development of TiC reinforced Si 3 N 4 ceramics is explained and quantitative information is provided to optimize the microstructure of such materials. The concept of reaction paths for the understanding of rapid solidification processes is shown by the example of AZ type Mg casting alloys. (orig.)
Identifying Reaction Pathways and their Environments

DEFF Research Database (Denmark)

Maronsson, Jon Bergmann

Finding the mechanisms and estimating the rate of chemical reactions is an essential part of modern research of atomic scale systems. In this thesis, the application of well established methods for reaction rates and paths to important systems for hydrogen storage is considered before developing...... extensions to further identify the reaction environment for a more accurate rate. Complex borohydrides are materials of high hydrogen storage capacity and high thermodynamic stability (too high for hydrogen storage). In an effort to gain insight into the structural transitions of two such materials, Ca(BH4......-interstitial defects. In good agreement with the experiments, C3-type rotations activate at lower temperature than C2-type rotations. In order to investigate the environment of reaction pathways, a method for finding the ridge between first order saddle points on a multidimensional surface was developed...
Citric Acid-Modified Fenton's Reaction for the Oxidation of Chlorinated Ethylenes in Soil Solution Systems

Energy Technology Data Exchange (ETDEWEB)

Seol, Yongkoo; Javandel, Iraj

2008-03-15

Fenton's reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an in-situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to create an acidic condition needed for catalytic oxidation. Fenton's reaction often involves pressure buildup and precipitation of reaction products, which can cause safety hazards and diminish efficiency. We selected citric acid, a food-grade substance, as an acidifying agent to evaluate its efficiencies for organic contaminant removal in Fenton's reaction, and examined the impacts of using citric acid on the unwanted reaction products. A series of batch and column experiments were performed with varying H{sub 2}O{sub 2} concentrations to decompose selected chlorinated ethylenes. Either dissolved iron from soil or iron sulfate salt was added to provide the iron catalyst in the batch tests. Batch experiments revealed that both citric and sulfuric acid systems achieved over 90% contaminant removal rates, and the presence of iron catalyst was essential for effective decontamination. Batch tests with citric acid showed no signs of pressure accumulation and solid precipitations, however the results suggested that an excessive usage of H{sub 2}O{sub 2} relative to iron catalysts (Fe{sup 2+}/H{sub 2}O{sub 2} < 1/330) would result in lowering the efficiency of contaminant removal by iron chelations in the citric acid system. Column tests confirmed that citric acid could provide suitable acidic conditions to achieve higher than 55% contaminant removal rates.
Correlations between reaction product yields as a tool for probing heavy-ion reaction scenarios

International Nuclear Information System (INIS)

Gawlikowicz, W.; Agnihotri, D. K.; Baldwin, S. A.; Schroeder, W. U.; Toke, J.; Charity, R. J.; Sarantites, D. G.; Sobotka, L. G.; Souza, R. T. de; Barczyk, T.; Grotowski, K.; Micek, S.; Planeta, R.; Sosin, Z.

2010-01-01

Experimental multidimensional joint distributions of neutrons and charged reaction products were analyzed for 136 Xe + 209 Bi reactions at E/A=28, 40, and 62 MeV and were found to exhibit several different types of prominent correlation patterns. Some of these correlations have a simple explanation in terms of the system excitation energy and pose little challenge to most statistical decay theories. However, several other types of correlation patterns are difficult to reconcile with some, but not other, possible reaction scenarios. In this respect, correlations between the average atomic numbers of intermediate-mass fragments, on the one hand, and light particle multiplicities, on the other, are notable. This kind of multiparticle correlation provides a useful tool for probing reaction scenarios, which is different from the traditional approach of interpreting inclusive yields of individual reaction products.
Catalytic Wittig and aza-Wittig reactions

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Zhiqi Lao

2016-11-01

Full Text Available This review surveys the literature regarding the development of catalytic versions of the Wittig and aza-Wittig reactions. The first section summarizes how arsenic and tellurium-based catalytic Wittig-type reaction systems were developed first due to the relatively easy reduction of the oxides involved. This is followed by a presentation of the current state of the art regarding phosphine-catalyzed Wittig reactions. The second section covers the field of related catalytic aza-Wittig reactions that are catalyzed by both phosphine oxides and phosphines.
Effect of Barium-Precursors on Reaction Kinetics in Y-Ba-Cu-O System

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

The reactions of stoichiometric Y2O3, CuO, and different Ba salts or oxides (BaCO3, Ba(NO3)2, BaO2, BaCuO2) for forming various compounds in the Y-Ba-Cu-O system (i.e., YBa2Cu3O7-δ, BaCuO2, Y2BaCuO5 and Y2Cu2O5) were systematically investigated by thermal analysis and X-ray diffractometry. The relevant activation energies were calculated from thermogravimetric data. It is found that the reaction pathway significantly depends on the thermal stability of the Ba precursors. Binary BaO-CuO phases form at low temperature (650～700 ℃) when in presence of easy-to-decompose Ba precursors, and then slowly transform to ternary compounds. On the contrary, when Ba ions are released at temperature higher than 900 ℃, ternary phases form directly from the components.
Reaction Mechanisms and Structural and Physicochemical Properties of Caffeic Acid Grafted Chitosan Synthesized in Ascorbic Acid and Hydroxyl Peroxide Redox System.

Science.gov (United States)

Liu, Jun; Pu, Huimin; Chen, Chong; Liu, Yunpeng; Bai, Ruyu; Kan, Juan; Jin, Changhai

2018-01-10

The ascorbic acid (AA) and hydroxyl peroxide (H 2 O 2 ) redox pair induced free radical grafting reaction is a promising approach to conjugate phenolic groups with chitosan (CS). In order to reveal the exact mechanisms of the AA/H 2 O 2 redox pair induced grafting reaction, free radicals generated in the AA/H 2 O 2 redox system were compared with hydroxyl radical ( • OH) produced in the Fe 2+ /H 2 O 2 redox system. Moreover, the structural and physicochemical properties of caffeic acid grafted CS (CA-g-CS) synthesized in these two redox systems were compared. Results showed that only ascorbate radical (Asc •- ) was produced in the AA/H 2 O 2 system. The reaction between Asc •- and CS produced novel carbon-centered radicals, whereas no new free radicals were detected when • OH reacted with CS. Thin layer chromatography, UV-vis, Fourier transform infrared, and nuclear magnetic resonance spectroscopic analyses all confirmed that CA was successfully grafted onto CS through Asc •- . However, CA could be hardly grafted onto CS via • OH. CA-g-CS synthesized through Asc •- exhibited lower thermal stability and crystallinity than the reaction product obtained through • OH. For the first time, our results demonstrated that the synthesis of CA-g-CS in the AA/H 2 O 2 redox system was mediated by Asc •- rather than • OH.
Consistent analysis of peripheral reaction channels and fusion for the 16,18O+58Ni systems

International Nuclear Information System (INIS)

Alves, J.J.S.; Gomes, P.R.S.; Lubian, J.; Chamon, L.C.; Pereira, D.; Anjos, R.M.; Rossi, E.S.; Silva, C.P.; Alvarez, M.A.G.; Nobre, G.P.A.; Gasques, L.R.

2005-01-01

We have measured elastic scattering and peripheral reaction channel cross sections for the 16,18 O+ 58 Ni systems at ELab=46 MeV. The data were analyzed through extensive coupled-channel calculations. It was investigated the consistency of the present analysis with a previous one at sub-barrier energies. Experimental fusion cross sections for these systems are also compared with the corresponding predictions of the coupled-channel calculations
Synthesis of the AB ring system of clifednamide utilizing Claisen rearrangement and Diels-Alder reaction as key steps.

Science.gov (United States)

Loke, Inga; Bentzinger, Guillaume; Holz, Julia; Raja, Aruna; Bhasin, Aman; Sasse, Florenz; Köhn, Andreas; Schobert, Rainer; Laschat, Sabine

2016-01-21

In order to construct the functionalized AB ring system of clifednamide, member of the class of macrocyclic tetramic acid lactams, a synthesis was developed which utilized an Ireland-Claisen rearrangement and an intramolecular Diels-Alder reaction. Starting from di-O-isopropylidene-d-mannitol the allyl carboxylate precursor for the sigmatropic rearrangement was prepared. This rearrangement proceeded diastereoselectively only in the presence of an allyl silyl ether instead of the parent enone in the side chain, as suggested by deuteration experiments. A subsequent Diels-Alder reaction yielded the target ethyl hexahydro-1H-indene-carboxylate with high diastereoselectivity. Quantum-chemical investigations of this intramolecular Diels-Alder reaction support the proposed configuration of the final product.
Reactions of SO 2 on hydrated cement particle system for atmospheric pollution reduction: A DRIFTS and XANES study

Energy Technology Data Exchange (ETDEWEB)

Ramakrishnan, Girish; Wu, Qiyuan; Moon, Juhyuk; Orlov, Alexander

2017-07-01

An investigation of the adsorptive property of hydrated cement particle system for sulfur dioxide (SO2) removal was conducted. In situ and ex situ experiments using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and X-ray Absorption Near Edge Spectroscopy (XANES) characterization techniques were employed to identify surface species formed during the exposure to SO2. Oxidation of SO2 to sulfate and sulfite species observed during these experiments indicated dominant reaction pathways for SO2 reaction with concrete constituents, such as calcium hydroxide, which were also moderated by adsorption on porous surfaces of crushed aggregates. The impact of variable composition of concrete on its adsorption capacity and reaction mechanisms was also proposed in this work.
Oscillatory pulses and wave trains in a bistable reaction-diffusion system with cross diffusion.

Science.gov (United States)

Zemskov, Evgeny P; Tsyganov, Mikhail A; Horsthemke, Werner

2017-01-01

We study waves with exponentially decaying oscillatory tails in a reaction-diffusion system with linear cross diffusion. To be specific, we consider a piecewise linear approximation of the FitzHugh-Nagumo model, also known as the Bonhoeffer-van der Pol model. We focus on two types of traveling waves, namely solitary pulses that correspond to a homoclinic solution, and sequences of pulses or wave trains, i.e., a periodic solution. The effect of cross diffusion on wave profiles and speed of propagation is analyzed. We find the intriguing result that both pulses and wave trains occur in the bistable cross-diffusive FitzHugh-Nagumo system, whereas only fronts exist in the standard bistable system without cross diffusion.
Connecting localized DNA strand displacement reactions

Science.gov (United States)

Mullor Ruiz, Ismael; Arbona, Jean-Michel; Lad, Amitkumar; Mendoza, Oscar; Aimé, Jean-Pierre; Elezgaray, Juan

2015-07-01

Logic circuits based on DNA strand displacement reactions have been shown to be versatile enough to compute the square root of four-bit numbers. The implementation of these circuits as a set of bulk reactions faces difficulties which include leaky reactions and intrinsically slow, diffusion-limited reaction rates. In this paper, we consider simple examples of these circuits when they are attached to platforms (DNA origamis). As expected, constraining distances between DNA strands leads to faster reaction rates. However, it also induces side-effects that are not detectable in the solution-phase version of this circuitry. Appropriate design of the system, including protection and asymmetry between input and fuel strands, leads to a reproducible behaviour, at least one order of magnitude faster than the one observed under bulk conditions.Logic circuits based on DNA strand displacement reactions have been shown to be versatile enough to compute the square root of four-bit numbers. The implementation of these circuits as a set of bulk reactions faces difficulties which include leaky reactions and intrinsically slow, diffusion-limited reaction rates. In this paper, we consider simple examples of these circuits when they are attached to platforms (DNA origamis). As expected, constraining distances between DNA strands leads to faster reaction rates. However, it also induces side-effects that are not detectable in the solution-phase version of this circuitry. Appropriate design of the system, including protection and asymmetry between input and fuel strands, leads to a reproducible behaviour, at least one order of magnitude faster than the one observed under bulk conditions. Electronic supplementary information (ESI) available. See DOI: 10.1039/C5NR02434J
The nuclear reaction n + 3He -> 1H + 3H as proximity reaction

International Nuclear Information System (INIS)

Hilber, H.C.

1982-01-01

The present thesis tries to give by means of the nuclear reaction n + 3 He -> 1 H + 3 H as proximity reaction on the three-particle system 3 He + 9 Be -> 1 H + 3 H + 8 Be an experimental verification to the second term of a multiple scattering series. The study of these rescattering effects is of great interest for the present theory of the final-state interaction. At three incident energies (7.08 MeV, 8.98 MeV, and 6.37 MeV) to detector telescopes identify the exit channel of the three-particle system in list-mode coincidence experiments according to protons and tritons. Peaks on the kinematical curves occur. The detailed study of their kinematic behaviour allows to exclude the inconcurrence to the proximity reaction lying cascade decays via intermediate states in 4 He, 9 B, and 11 B. Regarding the Coulomb interaction the experimental results can be also explained in the sense of the classical kinematics by the proximity model. (orig.) [de
Ion exchange equilibrium for some uni-univalent and uni-divalent reaction systems using strongly basic anion exchange resin Duolite A-102 D

Directory of Open Access Journals (Sweden)

R.S. Lokhande

2008-04-01

Full Text Available The study on thermodynamics of ion exchange equilibrium for uni-univalent Cl-/I-, Cl-/Br-, and uni-divalent Cl-/SO42-, Cl-/C2O42- reaction systems was carried out using ion exchange resin Duolite A-102 D. The equilibrium constant K was calculated by taking into account the activity coefficient of ions both in solution as well as in the resin phase. The K values calculated for uni-univalent and uni-divalent anion exchange reaction systems was observed to increase with rise in temperature, indicating the endothermic exchange reactions having enthalpy values of 13.7, 38.0, 23.9, 22.9 kJ/mol, respectively.
Experimental Study of Closed System in the Chlorine Dioxide-Iodide-Sulfuric Acid Reaction by UV-Vis Spectrophotometric Method

Directory of Open Access Journals (Sweden)

Na Li

2011-01-01

Full Text Available The mole ratio r(r=[I−]0/[ClO2]0 has great influence on ClO2-I−-H2SO4 closed reaction system. By changing the initiate concentration of potassium iodide, the curve of absorbance along with the reaction time was obtained at 350 nm and 297 nm for triiodide ion, and 460 nm for iodine. The changing point of the absorbance curve's shape locates at r=6.00. For the reaction of ClO2-I− in the absence of H2SO4, the curve of absorbance along with the reaction time can be obtained at 350 nm for triiodide ion, 460 nm for iodine. The mole ratio r is equal to 1.00 is the changing point of the curve's shape no matter at which wavelength to determine the reaction. For the reaction of ClO2-I−-H+ in different pH buffer solution, the curve of absorbance along with the reaction time was recorded at 460 nm for iodine. When r is greater than 1.00, the transition point of the curve's shape locates at pH 2.0, which is also the point of producing chlorite or chloride for chlorine dioxide at different pH. When r is less than 1.00, the transition point locates at pH 7.0.
ReactionPredictor: prediction of complex chemical reactions at the mechanistic level using machine learning.

Science.gov (United States)

Kayala, Matthew A; Baldi, Pierre

2012-10-22

Proposing reasonable mechanisms and predicting the course of chemical reactions is important to the practice of organic chemistry. Approaches to reaction prediction have historically used obfuscating representations and manually encoded patterns or rules. Here we present ReactionPredictor, a machine learning approach to reaction prediction that models elementary, mechanistic reactions as interactions between approximate molecular orbitals (MOs). A training data set of productive reactions known to occur at reasonable rates and yields and verified by inclusion in the literature or textbooks is derived from an existing rule-based system and expanded upon with manual curation from graduate level textbooks. Using this training data set of complex polar, hypervalent, radical, and pericyclic reactions, a two-stage machine learning prediction framework is trained and validated. In the first stage, filtering models trained at the level of individual MOs are used to reduce the space of possible reactions to consider. In the second stage, ranking models over the filtered space of possible reactions are used to order the reactions such that the productive reactions are the top ranked. The resulting model, ReactionPredictor, perfectly ranks polar reactions 78.1% of the time and recovers all productive reactions 95.7% of the time when allowing for small numbers of errors. Pericyclic and radical reactions are perfectly ranked 85.8% and 77.0% of the time, respectively, rising to >93% recovery for both reaction types with a small number of allowed errors. Decisions about which of the polar, pericyclic, or radical reaction type ranking models to use can be made with >99% accuracy. Finally, for multistep reaction pathways, we implement the first mechanistic pathway predictor using constrained tree-search to discover a set of reasonable mechanistic steps from given reactants to given products. Webserver implementations of both the single step and pathway versions of Reaction
Silicon-based sleeve devices for chemical reactions

Science.gov (United States)

Northrup, M. Allen; Mariella, Jr., Raymond P.; Carrano, Anthony V.; Balch, Joseph W.

1996-01-01

A silicon-based sleeve type chemical reaction chamber that combines heaters, such as doped polysilicon for heating, and bulk silicon for convection cooling. The reaction chamber combines a critical ratio of silicon and silicon nitride to the volume of material to be heated (e.g., a liquid) in order to provide uniform heating, yet low power requirements. The reaction chamber will also allow the introduction of a secondary tube (e.g., plastic) into the reaction sleeve that contains the reaction mixture thereby alleviating any potential materials incompatibility issues. The reaction chamber may be utilized in any chemical reaction system for synthesis or processing of organic, inorganic, or biochemical reactions, such as the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction, which are examples of a synthetic, thermal-cycling-based reaction. The reaction chamber may also be used in synthesis instruments, particularly those for DNA amplification and synthesis.
Allergic reactions seen in orthodontic treatment

Directory of Open Access Journals (Sweden)

Hande Görücü Coşkuner

2016-01-01

Full Text Available Allergy can be defined as inappropriate and harmful response to harmless and ordinary materials. Allergic reactions, like in other fields of dentistry, can also be seen in the field of orthodontics. The reactions that occur against orthodontic materials can be seen as irritant or hypersensitivity reactions. The main reason of the irritant reactions is friction between soft tissues and orthodontic appliances. However, the reason of the hypersensitivity reactions is usually the antigenicity of the materials. Hypersensitivity reactions are usually seen as allergic contact dermatitis on face and neck; the occurrence of mucosal-gingival reactions and dermal and systemic reactions are rare. Latex, metal and acrylic resins are the most common allergens in orthodontics. Apart from these materials, allergic reactions can occur against bonding materials, extraoral appliances, disinfectants and antimicrobial agents. The reactions that occur against extraoral appliances usually result from metallic and elastic parts of the appliances or the appliance parts that are in contact with skin. Orthodontists should be aware of the allergic reactions to protect their patients’ health. The aim of this review was to evaluate the allergic reactions seen in orthodontic patients and discuss the cautions that orthodontists can take.

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

Science.gov (United States)

Akhtulov, A. L.

2018-01-01

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

Science.gov (United States)

Noorman, H J; Heijnen, J J; Ch A M Luyben, K

1991-09-01

In microbial reaction systems, there are a number of linear relations among net conversion rates. These can be very useful in the analysis of experimental data. This article provides a general approach for the formation and application of the linear relations. Two type of system descriptions, one considering the biomass as a black box and the other based on metabolic pathways, are encountered. These are defined in a linear vector and matrix algebra framework. A correct a priori description can be obtained by three useful tests: the independency, consistency, and observability tests. The independency are different. The black box approach provides only conservations relations. They are derived from element, electrical charge, energy, and Gibbs energy balances. The metabolic approach provides, in addition to the conservation relations, metabolic and reaction relations. These result from component, energy, and Gibbs energy balances. Thus it is more attractive to use the metabolic description than the black box approach. A number of different types of linear relations given in the literature are reviewed. They are classified according to the different categories that result from the black box or the metabolic system description. Validation of hypotheses related to metabolic pathways can be supported by experimental validation of the linear metabolic relations. However, definite proof from biochemical evidence remains indispensable.
Reconstitution of Low Bandwidth Reaction History

International Nuclear Information System (INIS)

May, M.; Clancy, T.; Fittinghoff, D.; Gennaro, P.; Hagans, K.; Halvorson, G.; Lowry, M.; Perry, T.; Roberson, P.; Smith, D.; Teruya, A.; Blair, J.; Davis, B.; Hunt, E.; Emkeit, B.; Galbraith, J.; Kelly, B.; Montoya, R.; Nickel, G.; Ogle, J.; Wilson, K.; Wood, M.

2004-01-01

The goal of the Test Readiness Program is to transition to a 24 month test readiness posture and if approved move to an 18-month posture. One of the key components of the Test Readiness Program necessary to meet this goal is the reconstitution of the important diagnostics. Since the end of nuclear testing, the ability to field diagnostics on a nuclear test has deteriorated. Reconstitution of diagnostics before those who had experience in nuclear testing either retire or leave is essential to achieving a shorter test readiness posture. Also, the data recording systems have not been used since the end of testing. This report documents the reconstitution of one vital diagnostic: the low bandwidth reaction history diagnostic for FY04. Reaction history is one of the major diagnostics that has been used on all LLNL and LANL tests since the early days of nuclear testing. Reaction history refers to measuring the time history of the gamma and neutron output from a nuclear test. This gives direct information on the nuclear reactions taking place in the device. The reaction history measurements are one of the prime measurements the nuclear weapon scientists use to validate their models of device performance. All tests currently under consideration require the reaction history diagnostic. Thus moving to a shorter test readiness posture requires the reconstitution of the ability to make reaction history measurements. Reconstitution of reaction history was planned to be in two steps. Reaction history measurements that have been used in the past can be broadly placed into two categories. The most common type of reaction history and the one that has been performed on virtually all nuclear tests is termed low bandwidth reaction history. This measurement has a time response that is limited by the bandpass of kilometer length coaxial cables. When higher bandwidth has been required for specific measurements, fiber optic techniques have been used. This is referred to as high
Catalyst Initiation in the Oscillatory Carbonylation Reaction

Directory of Open Access Journals (Sweden)

Katarina Novakovic

2011-01-01

Full Text Available Palladium(II iodide is used as a catalyst in the phenylacetylene oxidative carbonylation reaction that has demonstrated oscillatory behaviour in both pH and heat of reaction. In an attempt to extract the reaction network responsible for the oscillatory nature of this reaction, the system was divided into smaller parts and they were studied. This paper focuses on understanding the reaction network responsible for the initial reactions of palladium(II iodide within this oscillatory reaction. The species researched include methanol, palladium(II iodide, potassium iodide, and carbon monoxide. Several chemical reactions were considered and applied in a modelling study. The study revealed the significant role played by traces of water contained in the standard HPLC grade methanol used.
Maillard-reaction-induced modification and aggregation of proteins and hardening of texture in protein bar model systems.

Science.gov (United States)

Zhou, Peng; Guo, Mufan; Liu, Dasong; Liu, Xiaoming; Labuza, Teodore P

2013-03-01

The hardening of high-protein bars causes problems in their acceptability to consumers. The objective of this study was to determine the progress of the Maillard reaction in model systems of high-protein nutritional bars containing reducing sugars, and to illustrate the influences of the Maillard reaction on the modification and aggregation of proteins and the hardening of bar matrices during storage. The progress of the Maillard reaction, glycation, and aggregation of proteins, and textural changes in bar matrices were investigated during storage at 25, 35, and 45 °C. The initial development of the Maillard reaction caused little changes in hardness; however, further storage resulted in dramatic modification of protein with formation of high-molecular-weight polymers, resulting in the hardening in texture. The replacement of reducing sugars with nonreducing ingredients such as sugar alcohols in the formula minimized the changes in texture. The hardening of high-protein bars causes problems in their acceptability to consumers. Maillard reaction is one of the mechanisms contributing to the hardening of bar matrix, particularly for the late stage of storage. The replacement of reducing sugars with nonreducing ingredients such as sugar alcohols in the formula will minimize the changes in texture. © 2013 Institute of Food Technologists®
Local and systemic inflammatory and immunologic reactions to cyathostomin larvicidal therapy in horses.

Science.gov (United States)

Nielsen, M K; Loynachan, A T; Jacobsen, S; Stewart, J C; Reinemeyer, C R; Horohov, D W

2015-12-15

Encysted cyathostomin larvae are ubiquitous in grazing horses. Arrested development occurs in this population and can lead to an accumulation of encysted larvae. Large numbers of tissue larvae place the horse at risk for developing larval cyathostominosis. This disease complex is caused by mass emergence of these larvae and is characterized by a generalized acute typhlocolitis and manifests itself as a profuse protein-losing watery diarrhea with a reported case-fatality rate of about 50%. Two anthelmintic formulations have a label claim for larvicidal therapy of these encysted stages; moxidectin and a five-day regimen of fenbendazole. There is limited knowledge about inflammatory and immunologic reactions to larvicidal therapy. This study was designed to evaluate blood acute phase reactants as well as gene expression of pro-inflammatory cytokines, both locally in the large intestinal walls and systemically. Further, mucosal tissue samples were evaluated histopathologically as well as analyzed for gene expression of pro- and anti-inflammatory cytokines, cluster of differentiation (CD) cell surface proteins, and select transcription factors. Eighteen juvenile horses with naturally acquired cyathostomin infections were randomly assigned to three treatment groups; one group served as untreated controls (Group 1), one received a five-day regimen of fenbendazole (10mg/kg) (Group 2), and one group received moxidectin (0.4mg/kg) (Group 3). Horses were treated on day 0 and euthanatized on days 18-20. Serum and whole blood samples were collected on days 0, 5, and 18. All horses underwent necropsy with collection of tissue samples from the ventral colon and cecum. Acute phase reactants measured included serum amyloid A, iron and fibrinogen, and the cytokines evaluated included interferon γ, tumor necrosis factor α, transforming growth factor (TGF)-β, and interleukins 1β, 4, 5, 6, and 10. Transcription factors evaluated were FoxP3, GATA3 and tBet, and CD markers included
Intramolecular anionic diels-alder reactions of 1-aryl-4-oxahepta-1,6-diyne systems in DMSO.

Science.gov (United States)

Kudoh, Takayuki; Mori, Tomoko; Shirahama, Mitsuhito; Yamada, Masashi; Ishikawa, Teruhiko; Saito, Seiki; Kobayashi, Hisayoshi

2007-04-25

Base-promoted cycloaddition reactions of 1-aryl- or 1-aryl-7-substituted-4-oxahepta-1,6-diyne systems in DMSO have proven to involve an anionic intramolecular Diels-Alder process taking place even at room temperature in spite of the reaction suffering from temporary disruption of aromaticity. Although initially formed alpha-arylallenide anion can be protonated by DMSO, it can be back to the allenide anion probably because of a small acidity difference between alpha-arylallene and DMSO. The alpha-arylallenide anion in combination with the alpha-aryl substituent can constitute an anionic diene structure that undergoes the intramolecular Diels-Alder reaction involving the C(6)-yne part, a very fast process probably because of the increased HOMO-1 level of the anionic diene, as shown by DFT calculations. Diversified substituted naphthalenes, benzofurans, phenanthrenes, and quinolines, including biaryl architectures, are available from 4-oxahepta-1,6-diynes in a highly expeditious way.
In vitro antioxidant and cytoprotective properties of Maillard reaction products from phloridzin-amino acid model systems.

Science.gov (United States)

Han, Linna; Li, Feng; Yu, Qijian; Li, Dapeng

2018-01-01

The aim of this study was to investigate in vitro antioxidant activities and cytoprotective effect of Maillard reaction products (MRPs) from phloridzin (Pz)-amino acid model systems. Their structures were also characterised by Fourier transform-infrared spectroscopy (FTIR). MRPs were prepared from the Pz-methionine (Met), Pz-lysine (Lys), Pz-isoleucine (Ile), Pz-histidine (His) or Pz-glutamic acid (Glu) model system. The Pz-Lys MRPs, rich in antioxidant potency, were subjected to ultrafiltration to yield four MRPs fractions with different molecular weights (Mw). The fraction with Mw 30-50 kDa had significantly (P Maillard reaction. The results obtained in this study may provide some basis for the purported health-promoting effects of MRPs and their potential application as antioxidant agents in food industry. Also, it is important for our understanding of the variation of bioactive substances in food during thermal processing. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
Reaction chemistry in rechargeable Li-O2 batteries.

Science.gov (United States)

Lim, Hee-Dae; Lee, Byungju; Bae, Youngjoon; Park, Hyeokjun; Ko, Youngmin; Kim, Haegyeom; Kim, Jinsoo; Kang, Kisuk

2017-05-22

The seemingly simple reaction of Li-O 2 batteries involving lithium and oxygen makes this chemistry attractive for high-energy-density storage systems; however, achieving this reaction in practical rechargeable Li-O 2 batteries has proven difficult. The reaction paths leading to the final Li 2 O 2 discharge products can be greatly affected by the operating conditions or environment, which often results in major side reactions. Recent research findings have begun to reveal how the reaction paths may be affected by the surrounding conditions and to uncover the factors contributing to the difficulty in achieving the reactions of lithium and oxygen. This progress report describes the current state of understanding of the electrode reaction mechanisms in Li-O 2 batteries; the factors that affect reaction pathways; and the effect of cell components such as solvents, salts, additives, and catalysts on the discharge product and its decomposition during charging. This comprehensive review of the recent progress in understanding the reaction chemistry of the Li-O 2 system will serve as guidelines for future research and aid in the development of reliable high-energy-density rechargeable Li-O 2 batteries.
An integrated one-chip-sensor system for microRNA quantitative analysis based on digital droplet polymerase chain reaction

Science.gov (United States)

Tsukuda, Masahiko; Wiederkehr, Rodrigo Sergio; Cai, Qing; Majeed, Bivragh; Fiorini, Paolo; Stakenborg, Tim; Matsuno, Toshinobu

2016-04-01

A silicon microfluidic chip was developed for microRNA (miRNA) quantitative analysis. It performs sequentially reverse transcription and polymerase chain reaction in a digital droplet format. Individual processes take place on different cavities, and reagent and sample mixing is carried out on a chip, prior to entering each compartment. The droplets are generated on a T-junction channel before the polymerase chain reaction step. Also, a miniaturized fluorescence detector was developed, based on an optical pick-up head of digital versatile disc (DVD) and a micro-photomultiplier tube. The chip integrated in the detection system was tested using synthetic miRNA with known concentrations, ranging from 300 to 3,000 templates/µL. Results proved the functionality of the system.
Chemical memory reactions induced bursting dynamics in gene expression.

Science.gov (United States)

Tian, Tianhai

2013-01-01

Memory is a ubiquitous phenomenon in biological systems in which the present system state is not entirely determined by the current conditions but also depends on the time evolutionary path of the system. Specifically, many memorial phenomena are characterized by chemical memory reactions that may fire under particular system conditions. These conditional chemical reactions contradict to the extant stochastic approaches for modeling chemical kinetics and have increasingly posed significant challenges to mathematical modeling and computer simulation. To tackle the challenge, I proposed a novel theory consisting of the memory chemical master equations and memory stochastic simulation algorithm. A stochastic model for single-gene expression was proposed to illustrate the key function of memory reactions in inducing bursting dynamics of gene expression that has been observed in experiments recently. The importance of memory reactions has been further validated by the stochastic model of the p53-MDM2 core module. Simulations showed that memory reactions is a major mechanism for realizing both sustained oscillations of p53 protein numbers in single cells and damped oscillations over a population of cells. These successful applications of the memory modeling framework suggested that this innovative theory is an effective and powerful tool to study memory process and conditional chemical reactions in a wide range of complex biological systems.
An experimental and theoretical study of reaction steps relevant to the methanol-to-hydrocarbons reaction

Energy Technology Data Exchange (ETDEWEB)

Svelle, Stian

2004-07-01

The primary objective of the present work is to obtain new insight into the reaction mechanism of the zeolite catalyzed methanol-to-hydrocarbons (MTH) reaction. It was decided to use both experimental and computational techniques to reach this goal. An investigation of the n-butene + methanol system was therefore initiated. Over time, it became apparent that it was possible to determine the rate for the methylation of n-butene by methanol. The ethene and propene systems were therefore reexamined in order to collect kinetic information also for those cases. With the development of user-friendly quantum chemistry programs such as the Gaussian suite of programs, the possibility of applying quantum chemical methods to many types of problems has become readily available even for non-experts. When performing mechanistic studies, there is quite often a considerable synergy effect when combining experimental and computational approaches. The methylation reactions mentioned above turned out to be an issue well suited for quantum chemical investigations. The incentive for examining the halomethane reactivity was the clear analogy to the MTH reaction system. Alkene dimerization was also a reaction readily examined with quantum chemistry. As discussed in the introduction of this thesis, polymethylbenzenes, or their cationic counterparts, are suspected to be key intermediates in the MTH reaction. It was therefore decided to investigate the intrinsic reactivity of these species in the gas-phase by employing sophisticated mass spectrometric (MS) techniques in collaboration with the MS group at the Department of Chemistry, University of Oslo The data thus obtained will also be compared with results from an ongoing computational study on gas phase polymethylbenzenium reactivity. 6 papers presenting various studies are included. The titles are: 1) A Theoretical Investigation of the Methylation of Alkenes with Methanol over Acidic Zeolites. 2) A Theoretical Investigation of the
Enzyme Stability and Activity in Non-Aqueous Reaction Systems: A Mini Review

Directory of Open Access Journals (Sweden)

Shihui Wang

2016-02-01

Full Text Available Enormous interest in biocatalysis in non-aqueous phase has recently been triggered due to the merits of good enantioselectivity, reverse thermodynamic equilibrium, and no water-dependent side reactions. It has been demonstrated that enzyme has high activity and stability in non-aqueous media, and the variation of enzyme activity is attributed to its conformational modifications. This review comprehensively addresses the stability and activity of the intact enzymes in various non-aqueous systems, such as organic solvents, ionic liquids, sub-/super-critical fluids and their combined mixtures. It has been revealed that critical factors such as Log P, functional groups and the molecular structures of the solvents define the microenvironment surrounding the enzyme molecule and affect enzyme tertiary and secondary structure, influencing enzyme catalytic properties. Therefore, it is of high importance for biocatalysis in non-aqueous media to elucidate the links between the microenvironment surrounding enzyme surface and its stability and activity. In fact, a better understanding of the correlation between different non-aqueous environments and enzyme structure, stability and activity can contribute to identifying the most suitable reaction medium for a given biotransformation.
An EAACI “European Survey on Adverse Systemic Reactions in Allergen Immunotherapy (EASSI)”: the methodology

DEFF Research Database (Denmark)

Calderón, Moises A; Rodríguez Del Río, Pablo; Vidal, Carmen

2014-01-01

and a "harmonised terminology" according to MedDRA, we aimed to prospectively collect systemic adverse reactions due to AIT from real life clinical settings. Under the framework of the EAACI, a team of European specialists in AIT, pharmacovigilance, epidemiology and drugs regulation set up a web-based prospective...
Heterogeneous redox reactions in groundwater flow systems - Investigation and application of two different coupled codes

Energy Technology Data Exchange (ETDEWEB)

Pfingsten, W.; Carnahan, C.L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1995-05-01

Two simulators of reactive chemical transport are applied to a set of problems involving heterogeneous reactions of uranium species. The simulators use similar algorithms to compute the heterogeneous chemical equilibria, but they use different approaches to the computation of solute transport and to the coupling of transport with chemical reactions. One simulator (MCOTAC) sequentially couples calculations of static chemical equilibria to a random-walk simulation of solute advection and dispersion. The other simulator (THCC) directly couples mass action relations for chemical equilibria to finite-difference representations of the solute transport equations. The aim of the comparison was to demonstrate the applicability of the newly developed code MCOTAC to redox problems, and to identify and investigate general differences between the two types of codes within these applications. The chosen heterogeneous redox systems are hypothetically generate systems which provide numerical difficulties within the coupled code calculation. Uranium, an important component of heterogeneous redox systems consisting of uraniferous solids and natural groundwaters, was chosen as a main component in the example redox systems because of practical interest for performance assessment of geological repositories for nuclear wastes. The calculations show reasonable agreement, in general, between the two computational approaches. Specific areas of disagreement arise from numerical difficulties to each approach. Such `benchmarking` can enhance confidence in the overall performance of individual simulators while identifying aspects that may require further investigations and possible modifications. (author) figs., tabs., 7 refs.
Physical organic studies of organometallic reactions

Energy Technology Data Exchange (ETDEWEB)

Bergman, Robert G. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

1981-01-01

The mechanisms of reactions of organotransition metal complexes have only begun to be understood in detail during the last ten years. The complementary interaction of techniques and concepts developed earlier in studies of organic reaction mechanisms, with those commonly used in inorganic chetnistry, has played a crucial role in helping to elucidate organor.1etall.ic reaction mechanisms. A few systems in which this interaction has proved especially fruitful are discussed in this article.
Automatic simplification of systems of reaction-diffusion equations by a posteriori analysis.

Science.gov (United States)

Maybank, Philip J; Whiteley, Jonathan P

2014-02-01

Many mathematical models in biology and physiology are represented by systems of nonlinear differential equations. In recent years these models have become increasingly complex in order to explain the enormous volume of data now available. A key role of modellers is to determine which components of the model have the greatest effect on a given observed behaviour. An approach for automatically fulfilling this role, based on a posteriori analysis, has recently been developed for nonlinear initial value ordinary differential equations [J.P. Whiteley, Model reduction using a posteriori analysis, Math. Biosci. 225 (2010) 44-52]. In this paper we extend this model reduction technique for application to both steady-state and time-dependent nonlinear reaction-diffusion systems. Exemplar problems drawn from biology are used to demonstrate the applicability of the technique. Copyright © 2014 Elsevier Inc. All rights reserved.
Oxygen evolution reaction catalysis

Energy Technology Data Exchange (ETDEWEB)

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.
The reaction process of the Bi-Sr-Ca-Cu-O system and the forming mechanism of the 2212 superconducting phase

International Nuclear Information System (INIS)

Xiong Guohong; Wang Minquan; Fan Xianping; Tang Xiaoming

1993-01-01

The reaction process and the reaction behavior of each component in the Bi-Sr-Ca-Cu-O system are presented in this paper. It reveals that the reaction is carried out in three different stages: forming of an insulating interphase at 680 C-790 C, forming of the 2212 superconducting phase at 790 C-860 C and forming of semiconducting phases in the presence of the liquid phase at 860 C-970 C. It is also confirmed that the 2212 superconducting phase (T c =85 K) is formed by the reaction of a trinary interphase together with CuO, SrO and CaO. A new two-step method is presented to prepare the 2212 superconducting phase by a presynthesized interphase. (orig.)
The reaction process of the Bi-Sr-Ca-Cu-O system and the forming mechanism of the 2212 superconducting phase

Science.gov (United States)

Xiong, Guohong; Wang, Minquan; Fan, Xianping; Tang, Xiaoming

1993-02-01

The reaction process and the reaction behavior of each component in the Bi-Sr-Ca-Cu-O system are presented in this paper. It reveals that the reaction is carried out in three different stages: forming of an insulating interphase at 680°C 790°C, forming of the 2212 superconducting phase at 790°C 860°C and forming often semiconducting phases in the presence of the liquid phase at 860°C 970°C. It is also confirmed that the 2212 superconducting phase ( T c=85 K) is formed by the reaction of a trinary interphase together with CuO, SrO and CaO. A new two-step method is presented to prepare the 2212 superconducting phase by a presynthesized interphase.

The reaction process of the Bi-Sr-Ca-Cu-O system and the forming mechanism of the 2212 superconducting phase

Energy Technology Data Exchange (ETDEWEB)

Xiong Guohong (Zhejiang Univ., Hangzhou (China). Dept. of Materials Science and Engineering); Wang Minquan (Zhejiang Univ., Hangzhou (China). Dept. of Materials Science and Engineering); Fan Xianping (Zhejiang Univ., Hangzhou (China). Dept. of Materials Science and Engineering); Tang Xiaoming (Zhejiang Univ., Hangzhou (China). Center for Analysis and Measurement)

1993-02-01

The reaction process and the reaction behavior of each component in the Bi-Sr-Ca-Cu-O system are presented in this paper. It reveals that the reaction is carried out in three different stages: forming of an insulating interphase at 680 C-790 C, forming of the 2212 superconducting phase at 790 C-860 C and forming of semiconducting phases in the presence of the liquid phase at 860 C-970 C. It is also confirmed that the 2212 superconducting phase (T[sub c]=85 K) is formed by the reaction of a trinary interphase together with CuO, SrO and CaO. A new two-step method is presented to prepare the 2212 superconducting phase by a presynthesized interphase. (orig.)
Isotope exchange reaction in uranous-uranyl-sulphuric acid system

International Nuclear Information System (INIS)

Ling Daren; Yue Tingsheng; Mu Dehai; Wang Yani

1990-01-01

The kinetics of the isotope exchange reaction between U(IV) and U(VI) has been studied in low concentrations of sulphuric acid. A minimum exchange rate appears at 0.25 M H 2 SO 4 . From the rates at different temperatures ranging from 20deg to 35deg C, an apparent activation energy of 86 kcal/mole was calculated. The exchange rate was found to be accelerated by the addition of ferrous ions, and a half-life of less than 1 s, was obtained. Probable mechanisms for the acceleration of the uranium isotope exchange reactions by acidity and ferrous ions are proposed. (orig.)
Synchronous parallel kinetic Monte Carlo for continuum diffusion-reaction systems

International Nuclear Information System (INIS)

Martinez, E.; Marian, J.; Kalos, M.H.; Perlado, J.M.

2008-01-01

A novel parallel kinetic Monte Carlo (kMC) algorithm formulated on the basis of perfect time synchronicity is presented. The algorithm is intended as a generalization of the standard n-fold kMC method, and is trivially implemented in parallel architectures. In its present form, the algorithm is not rigorous in the sense that boundary conflicts are ignored. We demonstrate, however, that, in their absence, or if they were correctly accounted for, our algorithm solves the same master equation as the serial method. We test the validity and parallel performance of the method by solving several pure diffusion problems (i.e. with no particle interactions) with known analytical solution. We also study diffusion-reaction systems with known asymptotic behavior and find that, for large systems with interaction radii smaller than the typical diffusion length, boundary conflicts are negligible and do not affect the global kinetic evolution, which is seen to agree with the expected analytical behavior. Our method is a controlled approximation in the sense that the error incurred by ignoring boundary conflicts can be quantified intrinsically, during the course of a simulation, and decreased arbitrarily (controlled) by modifying a few problem-dependent simulation parameters
A Comparison of Analytical and Numerical Methods for Modeling Dissolution and Other Reactions in Transport Limited Systems

Science.gov (United States)

Hochstetler, D. L.; Kitanidis, P. K.

2009-12-01

Modeling the transport of reactive species is a computationally demanding problem, especially in complex subsurface media, where it is crucial to improve understanding of geochemical processes and the fate of groundwater contaminants. In most of these systems, reactions are inherently fast and actual rates of transformations are limited by the slower physical transport mechanisms. There have been efforts to reformulate multi-component reactive transport problems into systems that are simpler and less demanding to solve. These reformulations include defining conservative species and decoupling of reactive transport equations so that fewer of them must be solved, leaving mostly conservative equations for transport [e.g., De Simoni et al., 2005; De Simoni et al., 2007; Kräutle and Knabner, 2007; Molins et al., 2004]. Complex and computationally cumbersome numerical codes used to solve such problems have also caused De Simoni et al. [2005] to develop more manageable analytical solutions. Furthermore, this work evaluates reaction rates and has reaffirmed that the mixing rate,▽TuD▽u, where u is a solute concentration and D is the dispersion tensor, as defined by Kitanidis [1994], is an important and sometimes dominant factor in determining reaction rates. Thus, mixing of solutions is often reaction-limiting. We will present results from analytical and computational modeling of multi-component reactive-transport problems. The results have applications to dissolution of solid boundaries (e.g., calcite), dissolution of non-aqueous phase liquids (NAPLs) in separate phases, and mixing of saltwater and freshwater (e.g. saltwater intrusion in coastal carbonate aquifers). We quantify reaction rates, compare numerical and analytical results, and analyze under what circumstances which approach is most effective for a given problem. References: DeSimoni, M., et al. (2005), A procedure for the solution of multicomponent reactive transport problems, Water Resources Research, 41
Ion-molecule reactions: their role in radiation chemistry

International Nuclear Information System (INIS)

Lias, S.G.; Ausloos, P.

1975-01-01

A comprehensive review of ion--molecule reactions is presented, including information from mass spectrometric, organic chemistry, and NMR studies, from theoretical calculations, and from gas and liquid phase radiation chemistry. Special emphasis is placed on interpreting the role of ion--molecule reactions in systems under high energy irradiation. The discussion is presented under the following chapter headings: ion--molecule reactions and their role in radiation chemistry; unimolecular processes: the nature and structure of ionic intermediates in radiolysis; ion lifetimes and the fate of unreactive ions; kinetics and mechanisms of ion--molecule reactions; proton transfer reactions; negative atom and two-atom transfer reactions; condensation reactions; and, association or clustering reactions
Phase Equilibria of the Sn-Ni-Si Ternary System and Interfacial Reactions in Sn-(Cu)/Ni-Si Couples

Science.gov (United States)

Fang, Gu; Chen, Chih-chi

2015-07-01

Interfacial reactions in Sn/Ni-4.5 wt.%Si and Sn-Cu/Ni-4.5 wt.%Si couples at 250°C, and Sn-Ni-Si ternary phase equilibria at 250°C were investigated in this study. Ni-Si alloys, which are nonmagnetic, can be regarded as a diffusion barrier layer material in flip chip packaging. Solder/Ni-4.5 wt.%Si interfacial reactions are crucial to the reliability of soldered joints. Phase equilibria information is essential for development of solder/Ni-Si materials. No ternary compound is present in the Sn-Ni-Si ternary system at 250°C. Extended solubility of Si in the phases Ni3Sn2 and Ni3Sn is 3.8 and 6.1 at.%, respectively. As more Si dissolves in these phases their lattice constants decrease. No noticeable ternary solubility is observed for the other intermetallics. Interfacial reactions in solder/Ni-4.5 wt.%Si are similar to those for solder/Ni. Si does not alter the reaction phases. No Si solubility in the reaction phases was detected, although rates of growth of the reaction phases were reduced. Because the alloy Ni-4.5 wt.%Si reacts more slowly with solders than pure Ni, the Ni-4.5 wt.%Si alloy could be a potential new diffusion barrier layer material for flip chip packaging.
Molecular codes in biological and chemical reaction networks.

Directory of Open Access Journals (Sweden)

Dennis Görlich

Full Text Available Shannon's theory of communication has been very successfully applied for the analysis of biological information. However, the theory neglects semantic and pragmatic aspects and thus cannot directly be applied to distinguish between (bio- chemical systems able to process "meaningful" information from those that do not. Here, we present a formal method to assess a system's semantic capacity by analyzing a reaction network's capability to implement molecular codes. We analyzed models of chemical systems (martian atmosphere chemistry and various combustion chemistries, biochemical systems (gene expression, gene translation, and phosphorylation signaling cascades, an artificial chemistry, and random reaction networks. Our study suggests that different chemical systems possess different semantic capacities. No semantic capacity was found in the model of the martian atmosphere chemistry, the studied combustion chemistries, and highly connected random networks, i.e. with these chemistries molecular codes cannot be implemented. High semantic capacity was found in the studied biochemical systems and in random reaction networks where the number of second order reactions is twice the number of species. We conclude that our approach can be applied to evaluate the information processing capabilities of a chemical system and may thus be a useful tool to understand the origin and evolution of meaningful information, e.g. in the context of the origin of life.
Papulo-Nodular Reactions in Black Tattoos as Markers of Sarcoidosis: Study of 92 Tattoo Reactions from a Hospital Material.

Science.gov (United States)

Sepehri, Mitra; Hutton Carlsen, Katrina; Serup, Jørgen

2016-01-01

Sarcoidosis is, from historical data, suggested to be more prevalent among patients with tattoo reactions. We aimed to evaluate this association in a systematic study. This is a consecutive study of patients with tattoo complications, diagnosed in the "Tattoo Clinic" at Bispebjerg University Hospital in Copenhagen, Denmark, from 2008 to 2015, based on clinical assessment and histology. From the overall group of 494 tattoo complications in 406 patients, 92 reactions in 72 patients showed a papulo-nodular pattern studied for local and systemic sarcoidosis, since sarcoidosis is expected to be nodular. Of the 92 reactions with a papulo-nodular pattern, 27 (29%) reactions in 19 patients were diagnosed as cutaneous or systemic sarcoidosis, supported by histology; 65 (71%) were diagnosed as non-sarcoidosis due to histology and no clinical sarcoid manifestations. "Rush phenomenon" with concomitant reaction in many other black tattoos, triggered by a recent tattoo with a papulo-nodular reaction, was observed in 70% in the sarcoidosis group and 28% in the non-sarcoidosis group, indicating a predisposing factor which may be autoimmune and linked with sarcoidosis. Agglomerates of black pigment forming foreign bodies may in the predisposed individual trigger widespread reaction in the skin and internal organs. Black tattoos with papulo-nodular reactions should be seen as markers of sarcoidosis. Papulo-nodular reactions may, as triggers, induce widespread reactions in other black tattoos - a "rush phenomenon" - depending on individual predisposition. Sarcoidosis is estimated to be 500-fold increased in papulo-nodular reactions compared to the prevalence in the general population, and the association with black tattoos is strong. © 2017 S. Karger AG, Basel.
Experiments on multi-nucleon transfer reactions with the systems {sup 58,64}Ni+{sup 207}Pb at SHIP

Energy Technology Data Exchange (ETDEWEB)

Fernandovich Comas Lijachev, Victor

2012-07-01

This work presents experimental results on multi-nucleon transfer reactions in the collision systems {sup 58}Ni+{sup 207}Pb and {sup 64}Ni+{sup 207}Pb which were measured at the velocity filter SHIP at GSI. The reactions were performed at beam energies below and up to 10% above the Coulomb barrier. The work was motivated by theoretical predictions to apply multi-nucleon transfer reactions in heavy systems to synthesize new neutron-rich isotopes in the region of superheavy nuclei with Z>100 and in the region of the closed neutron shell N=126. The expected cross-sections for the production of these nuclei in transfer reactions are small and reach typically nanobarn and below. Therefore, efficient separation techniques have to be applied and the detection system must allow for the identification of single nuclei. A dedicated experimental setup to study such rare transfer products does not exist presently. But already existing facilities which are used for the synthesis of superheavy fusion products meet the requirements for the detection of rare reaction products. In this context, the velocity filter SHIP offers the possibility to separate heavy target-like transfer products from projectiles and projectile-like reaction products before they reach the detection system where the particles are identified by their alpha-decay properties. At SHIP, a cross-section limit of 10 pb can be reached at usual beam intensities. In the present work on collisions of {sup 58,64}Ni+{sup 207}Pb the influence of the projectile neutron number on the cross-sections, isotopic distributions and excitation energies of the transfer products was studied. Especially with the more neutron-rich {sup 64}Ni projectiles a transfer of up to seven protons and eight neutrons to the target nucleus was observed. The largest cross-sections for the most neutron-rich isotopes were reached at the beam energies around the Coulomb barrier. The transfer was accompanied by the full dissipation of the available
In operando observation system for electrochemical reaction by soft X-ray absorption spectroscopy with potential modulation method

International Nuclear Information System (INIS)

Nagasaka, Masanari; Kosugi, Nobuhiro; Yuzawa, Hayato; Horigome, Toshio

2014-01-01

In order to investigate local structures of electrolytes in electrochemical reactions under the same scan rate as a typical value 100 mV/s in cyclic voltammetry (CV), we have developed an in operando observation system for electrochemical reactions by soft X-ray absorption spectroscopy (XAS) with a potential modulation method. XAS spectra of electrolytes are measured by using a transmission-type liquid flow cell with built-in electrodes. The electrode potential is swept with a scan rate of 100 mV/s at a fixed photon energy, and soft X-ray absorption coefficients at different potentials are measured at the same time. By repeating the potential modulation at each fixed photon energy, it is possible to measure XAS of electrochemical reaction at the same scan rate as in CV. We have demonstrated successful measurement of the Fe L-edge XAS spectra of aqueous iron sulfate solutions and of the change in valence of Fe ions at different potentials in the Fe redox reaction. The mechanism of these Fe redox processes is discussed by correlating the XAS results with those at different scan rates
Polarization transfer in (d-vector,n-vector) reactions

International Nuclear Information System (INIS)

Walter, R.L.; Tornow, W.

1986-01-01

The status of the measurements and the role of polarization transfer coefficients for (d/sup →/,n/sup →/) reactions is reviewed. Emphasis is given to reactions, involving light-nuclei systems. The importance of (d/sup →/,n/sup →/) reactions as sources of polarized neutrons is pointed out
Research on Liquid Management Technology in Water Tank and Reactor for Propulsion System with Hydrogen Production System Utilizing Aluminum and Water Reaction

Science.gov (United States)

Imai, Ryoji; Imamura, Takuya; Sugioka, Masatoshi; Higashino, Kazuyuki

2017-12-01

High pressure hydrogen produced by aluminum and water reaction is considered to be applied to space propulsion system. Water tank and hydrogen production reactor in this propulsion system require gas and liquid separation function under microgravity condition. We consider to install vane type liquid acquisition device (LAD) utilizing surface tension in the water tank, and install gas-liquid separation mechanism by centrifugal force which swirling flow creates in the hydrogen reactor. In water tank, hydrophilic coating was covered on both tank wall and vane surface to improve wettability. Function of LAD in water tank and gas-liquid separation in reaction vessel were evaluated by short duration microgravity experiments using drop tower facility. In the water tank, it was confirmed that liquid was driven and acquired on the outlet due to capillary force created by vanes. In addition of this, it was found that gas-liquid separation worked well by swirling flow in hydrogen production reactor. However, collection of hydrogen gas bubble was sometimes suppressed by aluminum alloy particles, which is open problem to be solved.
Lagrangian descriptors of driven chemical reaction manifolds.

Science.gov (United States)

Craven, Galen T; Junginger, Andrej; Hernandez, Rigoberto

2017-08-01

The persistence of a transition state structure in systems driven by time-dependent environments allows the application of modern reaction rate theories to solution-phase and nonequilibrium chemical reactions. However, identifying this structure is problematic in driven systems and has been limited by theories built on series expansion about a saddle point. Recently, it has been shown that to obtain formally exact rates for reactions in thermal environments, a transition state trajectory must be constructed. Here, using optimized Lagrangian descriptors [G. T. Craven and R. Hernandez, Phys. Rev. Lett. 115, 148301 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.148301], we obtain this so-called distinguished trajectory and the associated moving reaction manifolds on model energy surfaces subject to various driving and dissipative conditions. In particular, we demonstrate that this is exact for harmonic barriers in one dimension and this verification gives impetus to the application of Lagrangian descriptor-based methods in diverse classes of chemical reactions. The development of these objects is paramount in the theory of reaction dynamics as the transition state structure and its underlying network of manifolds directly dictate reactivity and selectivity.
Theoretical analysis of consecutive reactions in adiabatic stirred tank reactors

International Nuclear Information System (INIS)

Jo, Byung Wook; Kim, Sun Il; Hong, Won Hae; Cha, Wol Suk; Kim, Soong Pyung; Kim, Jung Gyu

1990-01-01

By mathematical model for the case of the consecutive first-order exothermic reaction in an adiabatic CSTR, the effects of the system parameter i. e. relative residence time, heat of reaction and thermal sensitivity of reaction rate constant, on the concentration profile of the intermediate product of a consecutive reaction were obtained as follows. For fixed values of the ratio of the reaction rate constants t 1 / t 2 , the ratio of the correponding system parameter α where α>1 and the sensitivities of the reaction rate constants S1 and S2, the maximum value of the intermediate production dimensionless concentration increases with increase in the values of the relative energy parameter E1 and E2 and it decreases with a decrease in E1 and E2. For fixed values of the ratio of the reaction rate constants t 1 / t 2 , the ratio of the corresponding system parameter α where α 1 and t 2 and it increases with a decrease in S1 and S2. For fixed values of the ratio of the reaction rate constants t 1 / t 2 , the ratio of the corresponding system parameters α where α=1 and the relative energy parameters E1 and E2, the maximum value of the intermediate product dimensionless is constant with either increase or decrease in the sensitivities of the reaction rate constants S1 and S2. (Author)
A Networks Approach to Modeling Enzymatic Reactions.

Science.gov (United States)

Imhof, P

2016-01-01

Modeling enzymatic reactions is a demanding task due to the complexity of the system, the many degrees of freedom involved and the complex, chemical, and conformational transitions associated with the reaction. Consequently, enzymatic reactions are not determined by precisely one reaction pathway. Hence, it is beneficial to obtain a comprehensive picture of possible reaction paths and competing mechanisms. By combining individually generated intermediate states and chemical transition steps a network of such pathways can be constructed. Transition networks are a discretized representation of a potential energy landscape consisting of a multitude of reaction pathways connecting the end states of the reaction. The graph structure of the network allows an easy identification of the energetically most favorable pathways as well as a number of alternative routes. © 2016 Elsevier Inc. All rights reserved.
Scattering theory and chemical reactions

International Nuclear Information System (INIS)

Kuppermann, A.

1988-01-01

In this course, scattering theory and chemical reactions are presented including scattering of one particle by a potential, n-particle systems, colinear triatomic molecules and the study of reactive scattering for 3-dimensional triatomic systems. (A.C.A.S.) [pt
Systemic allergic reaction and diarrhoea after pineapple ingestion

NARCIS (Netherlands)

Kabir, I.; Speelman, P.; Islam, A.

1993-01-01

Some foods may initiate allergic reactions. Anaphylaxis due to mangoes, oranges, nuts and other foods has been reported earlier. We report the clinical and laboratory features of 32 patients who became symptomatic shortly after they had eaten pineapples. Seventeen patients were males and 15 females
Molecular dynamics simulation of a chemical reaction

International Nuclear Information System (INIS)

Gorecki, J.; Gryko, J.

1988-06-01

Molecular dynamics is used to study the chemical reaction A+A→B+B. It is shown that the reaction rate constant follows the Arrhenius law both for Lennard-Jones and hard sphere interaction potentials between substrate particles. A. For the denser systems the reaction rate is proportional to the value of the radial distribution function at the contact point of two hard spheres. 10 refs, 4 figs
Recent Advances in Recoverable Systems for the Copper-Catalyzed Azide-Alkyne Cycloaddition Reaction (CuAAC

Directory of Open Access Journals (Sweden)

Alessandro Mandoli

2016-09-01

Full Text Available The explosively-growing applications of the Cu-catalyzed Huisgen 1,3-dipolar cycloaddition reaction between organic azides and alkynes (CuAAC have stimulated an impressive number of reports, in the last years, focusing on recoverable variants of the homogeneous or quasi-homogeneous catalysts. Recent advances in the field are reviewed, with particular emphasis on systems immobilized onto polymeric organic or inorganic supports.
Reactions of H2O3 in the pulse-irradiated Fe(II)-O2 system

DEFF Research Database (Denmark)

Sehested, Knud; Bjergbakke, Erling; Lang Rasmussen, O.

1969-01-01

G(Fe(III)] is measured in pulse-irradiated O2-saturated solutions of 20 to 160 μMFe(II), at the p H's 0.46, 1.51, and 2.74 H2SO4 and HClO4 and with dose rates between 1 and 8 krad/1 μsec pulse. Based on homogeneous kinetics, the results are interpreted by a system of 18 reactions. The formation...

Reaction of ketene ions with ammonia

International Nuclear Information System (INIS)

Iraqi, M.; Lifshitz, C.; Reuben, B.G.

1991-01-01

Reactions of ketene ions with NH 3 , ND 3 , H 2 O, and CH 4 were investigated in a selected ion flow tube (SIFT). There were no observable products for H 2 O and CH 4 and no ion/neutral complex stabilization in any of the systems investigated. The ammonia system demonstrated two reaction channels, in agreement with previous FTICR data (1) distonic ion CH 2 NH 3 sm-bullet + formation, with a branching ratio of 0.2 and (2) proton transfer, with a branching ratio of 0.8. The overall second-order rate constant for NH 3 is (2.2 ± 0.15) x 10 -9 cm 3 molecule -1 s -1 , in agreement with the gas kinetic ion-dipole collision rate. Isotope scrambling was studied for primary (CH 2 CO + ) and for secondary (CH 2 NX 3 sm-bullet + and NX 4 + , X = H or D) proton-transfer reactions with ND 3 ; CH 2 NH 3 sm-bullet + appears to transfer an X + ion to ND 3 without any scrambling. CH 2 CO sm-bullet + undergoes reactions with partial scrambling and NX 4 + seems to react with almost complete scrambling. The results are compared with these of Adams, Smith, and Henchman on the NH 4 + /ND 3 system
Copy number ratios determined by two digital polymerase chain reaction systems in genetically modified grains

Science.gov (United States)

Pérez Urquiza, M.; Acatzi Silva, A. I.

2014-02-01

Three certified reference materials produced from powdered seeds to measure the copy number ratio sequences of p35S/hmgA in maize containing MON 810 event, p35S/Le1 in soybeans containing GTS 40-3-2 event and DREB1A/acc1 in wheat were produced according to the ISO Guides 34 and 35. In this paper, we report digital polymerase chain reaction (dPCR) protocols, performance parameters and results of copy number ratio content of genetically modified organisms (GMOs) in these materials using two new dPCR systems to detect and quantify molecular deoxyribonucleic acid: the BioMark® (Fluidigm) and the OpenArray® (Life Technologies) systems. These technologies were implemented at the National Institute of Metrology in Mexico (CENAM) and in the Reference Center for GMO Detection from the Ministry of Agriculture (CNRDOGM), respectively. The main advantage of this technique against the more-used quantitative polymerase chain reaction (qPCR) is that it generates an absolute number of target molecules in the sample, without reference to standards or an endogenous control, which is very useful when not much information is available for new developments or there are no standard reference materials in the market as in the wheat case presented, or when it was not possible to test the purity of seeds as in the maize case presented here. Both systems reported enhanced productivity, increased reliability and reduced instrument footprint. In this paper, the performance parameters and uncertainty of measurement obtained with both systems are presented and compared.
A study of KK-bar system produced in the reaction Π-p#-> #KK-barn at 63 GeV

International Nuclear Information System (INIS)

Palka, H.

1983-01-01

An analysis of KK-bar system produced in the reaction Π - p#-> #KK-barn at 63 GeV and measured by ACCMOR (Amsterdam-CERN-Cracow-Munich-Oxford-Rutherford) collaboration at the CERN SPS accelelator is presented. (author)
Systems Concepts for Integrated Air Defense of Multinational Mobile Crisis Reaction Forces (Concepts de systemes pour la defense aerienne integree de forces internationales mobiles d'intervention en situation de crise)

National Research Council Canada - National Science Library

2001-01-01

The meeting proceedings from this symposium on System Concepts for Integrated Air Defense of Multinational Mobile Crisis Reaction Forces was organized and sponsored by the Systems Concepts and Integration (SCI...
One-step Conversion of Levulinic Acid to Succinic Acid Using I2/t-BuOK System: The Iodoform Reaction Revisited.

Science.gov (United States)

Kawasumi, Ryosuke; Narita, Shodai; Miyamoto, Kazunori; Tominaga, Ken-Ichi; Takita, Ryo; Uchiyama, Masanobu

2017-12-21

The iodoform reaction has long been used as a qualitative test for acetyl and/or ethanol units in organic molecules. However, its synthetic applications are quite limited. Here, we describe a tuned iodoform reaction for oxidative demethylation reaction with I 2 and t-BuOK in t-BuOH, in which in situ-generated t-BuOI serves as the chemoselective iodinating agent. This system enables one-step conversion of levulinic acid to succinic acid, a major four-carbon chemical feedstock. This oxidative demethylation is also applicable to other compounds containing an acetyl group/ethanol unit, affording the corresponding carboxylic acids in a selective manner.
Simulation experiments for a large leak sodium-water reaction analysis. Volume 4. IHTS/relief system simulation tests

International Nuclear Information System (INIS)

Ploeger, D.W.

1978-09-01

Tests were performed in which a simplified 1/8-scale model of the intermediate heat transfer system and relief system of a LMFBR was subjected to a simulated sodium-water reaction in a steam generator. Pressures in the intermediate heat exchanger (IHX) and in the pipe were measured. The flow of water through the relief system was photographed and its velocity was measured. The forces on the relief system elbows resulting from the fluid flow were also measured. The tests were performed primarily to validate pulse propagation codes used for design and for direct use as design data
Investigation of Na-CO2 Reaction with Initial Reaction in Various Reacting Surface

International Nuclear Information System (INIS)

Kim, Hyun Su; Park, Gunyeop; Kim, Soo Jae; Park, Hyun Sun; Kim, Moo Hwan; Wi, Myung-Hwan

2015-01-01

The reaction products that cause oxidation and erosion are threaten the heat transfer tubes so that it is necessary to investigate Na-CO 2 reaction according to various experimental parameter. Unlike SWR, Na-CO 2 reaction is more complex to deal with reaction kinetics. Since a comprehensive understanding of Na-CO 2 reaction mechanism is crucial for the safety analysis, the reaction phenomenon under the various conditions was investigated. The current issue is to make a database for developing computational code for CO 2 gas leak situation because it is experimentally difficult to analyze the actual accident situation. Most studies on Na-CO 2 interaction reports that chemical reaction is getting vigorous as temperature increased and reactivity is sensitive as temperature change between 400 .deg. C and 600 .deg. C. Therefore, temperature range is determined based on the operating condition (450 - 500 .deg. C) of KALIMER-600 employed as supercritical CO 2 brayton cycle energy conversion system for Na-CO 2 heat exchanger. And next parameter is sodium surface area which contact between sodium and CO 2 when CO 2 is injected into sodium pool in the accident situation. So, the fundamental surface reaction is experimentally studied in the range of 8 - 12cm 2 . Additionally, it has been reported in recent years that CO 2 Flow rate affects reactivity less significantly and CO 2 flow rate is assumed that 5 SLPM (standard liter per minute) is suitable as a basis for a small leakage. The finally selected control parameters is sodium temperature and reacting surface area with constant CO 2 flow rate. Na-CO 2 reaction test is performed for investigating risk of potential accident which contacts with liquid sodium and CO 2 . Amount of reaction is saturated as time passed because of kept a balance between production of solid phase reaction products and amount of diffusivity. These results contribute to make a database for the SFR safety analysis and additional experiments are needed
Statistical theory of precompound nuclear reactions

International Nuclear Information System (INIS)

Nishioka, H.

1986-01-01

The purpose of the paper is to show the application of the Grassmann-integration method (or the graded-symmetry method) to a pre-equilibrium process in nuclear reactions. The Grassmann-integration method for random systems was first introduced by Efetov and later largely extended and applied to nuclear physics by Verbaarschot, Weidenmuller and Zirnbauer (referred to as VWZ). They have applied it to the equilibrium nuclear reactions; namely; the compound-nucleus reactions. It will be shown in this paper that this method is also applicable to non-equilibrium nuclear reactions. Applying this method to precompound nuclear reactions, the authors have obtained the same expression of the cross-section as Agassi, Weidenmuller and Mantzouranis (referred to as AWM) in the weak-coupling limit. In the general case their results show an important modification to AWM
Elastic scattering and total reaction cross section for the {sup 6}He+{sup 58}Ni system

Energy Technology Data Exchange (ETDEWEB)

Morcelle, V. [Instituto de Física - Universidade Federal Fluminense, 24210-346, Rio de Janeiro, Brazil and Universidade Federal de Itajubá, 35900-030, Itabira (Brazil); Lichtenthäler, R.; Lépine-Szily, A.; Guimarães, V.; Gasques, L.; Scarduelli, V.; Condori, R. Pampa; Leistenschneider, E. [Depto de Física Nuclear, Universidade de São Paulo, C.P. 66318, 05389-970, São Paulo (Brazil); Mendes Jr, D. R.; Faria, P. N. de [Instituto de Física - Universidade Federal Fluminense, 24210-346, Rio de Janeiro (Brazil); Pires, K. C. C. [Universidade Tecnológica Federal do Paraná, 86300-000, Cornélio Procópio (Brazil); Barioni, A. [Instituto de Física, Universidade Federal da Bahia, 40210-340, Bahia (Brazil); Morais, M. C. [Centro Brasileiro de Pesquisas Físicas, 22290-180, Rio de Janeiro (Brazil); Shorto, J. M. B. [Instituto de Pesquisas Energéticas e Nucleares- IPEN, 05508-000, São Paulo (Brazil); Zamora, J. C. [Departament of Physics, Technische Universität Darmstadt (Germany)

2014-11-11

Elastic scattering measurements of {sup 6}He + {sup 58}Ni system have been performed at the laboratory energy of 21.7 MeV. The {sup 6}He secondary beam was produced by a transfer reaction {sup 9}Be ({sup 7}Li, {sup 6}He) and impinged on {sup 58}Ni and {sup 197}Au targets, using the Radioactive Ion Beam (RIB) facility, RIBRAS, installed in the Pelletron Laboratory of the Institute of Physics of the University of São Paulo, Brazil. The elastic angular distribution was obtained in the angular range from 15° to 80° in the center of mass frame. Optical model calculations have been performed using a hybrid potential to fit the experimental data. The total reaction cross section was derived.
Drug Reaction with Eosinophilia and Systemic Symptom (DRESS) induced by carbamazepine: a case report and literature review

Science.gov (United States)

EL Omairi, Nissrine; Abourazzak, Sanae; Chaouki, Sanae; Atmani, Samir; Hida, Moustapha

2014-01-01

Drug-induced hypersensitivity or Drug Reaction with Eosinophilia and Systemic Symptom (DRESS) is a severe adverse drug-induced reaction. Diagnosing DRESS is challenging due to the diversity of cutaneous eruption and organs involved. Most of the aromatic anticonvulsants, such as phenytoin, phenobarbital, and carbamazepine, can induce DRESS. Culprit drug withdrawal and corticosteroids constituted the mainstay of DRESS treatment. We describe a 6 year-old boy who presented fever and rash 4 weeks after starting carbamazepine. Investigation revealed leukocytosis, atypical lymphocytosis, and elevated serum transaminases. The diagnosis of DREES syndrome was made, Carbamazepine was stopped and replaced initially by Clobazam and by Valproic acid after discharge, no systemic corticotherapy was prescribed. Symptoms began to resolve within two weeks, and by one month later her laboratory values had returned to normal. The aim of this work is to raise awareness general practitioner and pediatricians to suspect Dress syndrome in patients who present with unusual complaints and skin findings after starting any antiepileptic drug. PMID:25360193
Differences between Drug-Induced and Contrast Media-Induced Adverse Reactions Based on Spontaneously Reported Adverse Drug Reactions.

Science.gov (United States)

Ryu, JiHyeon; Lee, HeeYoung; Suh, JinUk; Yang, MyungSuk; Kang, WonKu; Kim, EunYoung

2015-01-01

We analyzed differences between spontaneously reported drug-induced (not including contrast media) and contrast media-induced adverse reactions. Adverse drug reactions reported by an in-hospital pharmacovigilance center (St. Mary's teaching hospital, Daejeon, Korea) from 2010-2012 were classified as drug-induced or contrast media-induced. Clinical patterns, frequency, causality, severity, Schumock and Thornton's preventability, and type A/B reactions were recorded. The trends among causality tools measuring drug and contrast-induced adverse reactions were analyzed. Of 1,335 reports, 636 drug-induced and contrast media-induced adverse reactions were identified. The prevalence of spontaneously reported adverse drug reaction-related admissions revealed a suspected adverse drug reaction-reporting rate of 20.9/100,000 (inpatient, 0.021%) and 3.9/100,000 (outpatients, 0.004%). The most common adverse drug reaction-associated drug classes included nervous system agents and anti-infectives. Dermatological and gastrointestinal adverse drug reactions were most frequently and similarly reported between drug and contrast media-induced adverse reactions. Compared to contrast media-induced adverse reactions, drug-induced adverse reactions were milder, more likely to be preventable (9.8% vs. 1.1%, p contrast media-induced adverse reactions (56.6%, p = 0.066). Causality patterns differed between the two adverse reaction classes. The World Health Organization-Uppsala Monitoring Centre causality evaluation and Naranjo algorithm results significantly differed from those of the Korean algorithm version II (p contrast media-induced adverse reactions. The World Health Organization-Uppsala Monitoring Centre and Naranjo algorithm causality evaluation afforded similar results.
Women's Experiences of Social Reactions From Informal and Formal Supports: Using a Modified Administration of the Social Reactions Questionnaire.

Science.gov (United States)

DePrince, Anne P; Dmitrieva, Julia; Gagnon, Kerry L; Srinivas, Tejaswinhi

2017-11-01

A growing literature links social reactions to disclosures of intimate violence to posttraumatic outcomes. The Social Reactions Questionnaire (SRQ), a widely used measure developed to assess social reactions, asks about reactions received from people generally. The ability to examine the impact of social reactions from specific groups of people-such as criminal justice personnel versus community-based providers-has become increasingly more important from both research and practice perspectives. For example, as sexual assault responses nationally have relied on community-coordinated models that involve both criminal justice and community-based systems, tools are lacking to systematically assess the impact of social reactions from criminal justice personnel and community-based providers on survivors. Using the SRQ, the current study asked women to report separately on reactions received from criminal justice personnel, community-based providers, and informal supports. We recruited a diverse community sample of women ( N = 228, ages 18-63, 19% lesbian/bisexual, 44% ethnic minority) who experienced a sexual assault in the previous year and disclosed to the criminal justice system and/or a community-based provider. Multilevel analyses revealed considerable variability in the social reactions reported by women across criminal justice personnel, community-based providers, and informal supports. Analyses supported a seven-factor structure for the SRQ when the measure is yoked to particular experiences of disclosure, in this case to criminal justice personnel, community-based providers, or informal supports. The utility of this modified administration and scoring of the SRQ and the importance of considering reactions across different groups are described.
EQ6, a computer program for reaction path modeling of aqueous geochemical systems: Theoretical manual, user`s guide, and related documentation (Version 7.0); Part 4

Energy Technology Data Exchange (ETDEWEB)

Wolery, T.J.; Daveler, S.A.

1992-10-09

EQ6 is a FORTRAN computer program in the EQ3/6 software package (Wolery, 1979). It calculates reaction paths (chemical evolution) in reacting water-rock and water-rock-waste systems. Speciation in aqueous solution is an integral part of these calculations. EQ6 computes models of titration processes (including fluid mixing), irreversible reaction in closed systems, irreversible reaction in some simple kinds of open systems, and heating or cooling processes, as well as solve ``single-point`` thermodynamic equilibrium problems. A reaction path calculation normally involves a sequence of thermodynamic equilibrium calculations. Chemical evolution is driven by a set of irreversible reactions (i.e., reactions out of equilibrium) and/or changes in temperature and/or pressure. These irreversible reactions usually represent the dissolution or precipitation of minerals or other solids. The code computes the appearance and disappearance of phases in solubility equilibrium with the water. It finds the identities of these phases automatically. The user may specify which potential phases are allowed to form and which are not. There is an option to fix the fugacities of specified gas species, simulating contact with a large external reservoir. Rate laws for irreversible reactions may be either relative rates or actual rates. If any actual rates are used, the calculation has a time frame. Several forms for actual rate laws are programmed into the code. EQ6 is presently able to model both mineral dissolution and growth kinetics.
The Pictet-Spengler reaction in solid-phase combinatorial chemistry

DEFF Research Database (Denmark)

Nielsen, Thomas E; Diness, Frederik; Meldal, Morten

2003-01-01

The Pictet-Spengler reaction is an important reaction for the generation of tetrahydro-beta-carbolines and tetrahydroisoquinoline ring systems, which exhibit a range of biological and pharmacological properties. This review covers the solid-phase Pictet-Spengler reaction, as employed in solid...
Adverse reactions to cosmetic products and the Notification System in Health Surveillance: a survey.

Science.gov (United States)

Huf, Gisele; Rito, Priscila da Nobrega; Presgrave, Rosaura de Farias; Boas, Maria Helena Simoes Villas

2013-12-01

This paper is part of a study that investigates the quality of cosmetic products and evaluates the cosmetic surveillance system. This study presents the results of a research that aimed to describe the point of view of the population in terms of the prevalence of Adverse Reactions (AR) and information about the surveillance system. A structured questionnaire was applied to a random sample of 200 people from the administrative staff of the Municipal Guard of Rio de Janeiro. 38% of the participants declared AR to some cosmetic product used in the past two years. To our knowledge, this is an unpublished study in Brazil, which presents results regarding the estimated prevalence of AR similarly to international studies.
Nuclear reaction database on Meme Media

Energy Technology Data Exchange (ETDEWEB)

Ohbayashi, Yoshihide; Masui, Hiroshi [Meme Media Laboratory, Hokkaido University, Sapporo, Hokkaido (Japan); Aoyama, Shigeyoshi [Information Processing Center, Kitami Institute of Technology, Kitami, Hokkaido (Japan); Kato, Kiyoshi [Division of Physics, Graduate School of Science, Hokkaido Univ., Sapporo, Hokkaido (Japan); Chiba, Masaki [Division of Social Information, Sapporo Gakuin University, Ebetsu, Hokkaido (Japan)

2000-03-01

We have developed the system of charged particle nuclear reaction data (CPND) on the IntelligentPad architecture. We called the system CONTIP, which is an abbreviation of 'Creative, Cooperative and Cultural Objects for Nuclear data and Tools'. NRDF (Nuclear Reaction Data File), which is a kind of CPND compilation, is applied as an application example. Although CONTIP is currently applied to NRDF, the framework can be generalized to use the othernuclear database. We will develop CONTIP to give the framework for effective utilization of nuclear data. (author)
Nuclear reaction database on Meme Media

International Nuclear Information System (INIS)

Ohbayashi, Yoshihide; Masui, Hiroshi; Aoyama, Shigeyoshi; Kato, Kiyoshi; Chiba, Masaki

2000-01-01

We have developed the system of charged particle nuclear reaction data (CPND) on the IntelligentPad architecture. We called the system CONTIP, which is an abbreviation of 'Creative, Cooperative and Cultural Objects for Nuclear data and Tools'. NRDF (Nuclear Reaction Data File), which is a kind of CPND compilation, is applied as an application example. Although CONTIP is currently applied to NRDF, the framework can be generalized to use the other nuclear database. We will develop CONTIP to give the framework for effective utilization of nuclear data. (author)
Supramolecular Systems and Chemical Reactions in Single-Molecule Break Junctions.

Science.gov (United States)

Li, Xiaohui; Hu, Duan; Tan, Zhibing; Bai, Jie; Xiao, Zongyuan; Yang, Yang; Shi, Jia; Hong, Wenjing

2017-04-01

The major challenges of molecular electronics are the understanding and manipulation of the electron transport through the single-molecule junction. With the single-molecule break junction techniques, including scanning tunneling microscope break junction technique and mechanically controllable break junction technique, the charge transport through various single-molecule and supramolecular junctions has been studied during the dynamic fabrication and continuous characterization of molecular junctions. This review starts from the charge transport characterization of supramolecular junctions through a variety of noncovalent interactions, such as hydrogen bond, π-π interaction, and electrostatic force. We further review the recent progress in constructing highly conductive molecular junctions via chemical reactions, the response of molecular junctions to external stimuli, as well as the application of break junction techniques in controlling and monitoring chemical reactions in situ. We suggest that beyond the measurement of single molecular conductance, the single-molecule break junction techniques provide a promising access to study molecular assembly and chemical reactions at the single-molecule scale.
Empire-3.2 Malta. Modular System for Nuclear Reaction Calculations and Nuclear Data Evaluation. User's Manual

International Nuclear Information System (INIS)

Herman, M.; Capote, R.; Sin, M.

2013-08-01

EMPIRE is a modular system of nuclear reaction codes, comprising various nuclear models, and designed for calculations over a broad range of energies and incident particles. The system can be used for theoretical investigations of nuclear reactions as well as for nuclear data evaluation work. Photons, nucleons, deuterons, tritons, helions ( 3 He), α's, and light or heavy ions can be selected as projectiles. The energy range starts just above the resonance region in the case of a neutron projectile, and extends up to few hundred MeV for heavy ion induced reactions. The code accounts for the major nuclear reaction models, such as optical model, Coupled Channels and DWBA (ECIS06 and OPTMAN), Multi-step Direct (ORION + TRISTAN), NVWY Multi-step Compound, exciton model (PCROSS), hybrid Monte Carlo simulation (DDHMS), and the full featured Hauser-Feshbach model including width fluctuations and the optical model for fission. Heavy ion fusion cross section can be calculated within the simplified coupled channels approach (CCFUS). A comprehensive library of input parameters based on the RIPL-3 library covers nuclear masses, optical model parameters, ground state deformations, discrete levels and decay schemes, level densities, fission barriers, and γ-ray strength functions. Effects of the dynamic deformation of a fast rotating nucleus can be taken into account in the calculations (BARFIT, MOMFIT). The results can be converted into the ENDF-6 format using the accompanying EMPEND code. Modules of the ENDF Utility Codes and the ENDF Pre-Processing codes are applied for ENDF file verification. The package contains the full EXFOR library of experimental data in computational format C4 that are automatically retrieved during the calculations. EMPIRE contains the resonance module that retrieves data from the electronic version of the Atlas of Neutron Resonances by Mughabghab (not provided with the EMPIRE distribution), to produce resonance section and related covariances for the
Normal Reactions to Orthostatic Stress in Rett Syndrome

Science.gov (United States)

Larsson, Gunilla; Julu, Peter O. O.; Engerstrom, Ingegerd Witt; Sandlund, Marlene; Lindstrom, Britta

2013-01-01

The aim of this study was to investigate orthostatic reactions in females with Rett syndrome (RTT), and also whether the severity of the syndrome had an impact on autonomic reactions. Based on signs of impaired function of the central autonomic system found in RTT, it could be suspected that orthostatic reactions were affected. The orthostatic…

Quantum mechanical calculations of vibrational population inversion in chemical reactions - Numerically exact L-squared-amplitude-density study of the H2Br reactive system

Science.gov (United States)

Zhang, Y. C.; Zhang, J. Z. H.; Kouri, D. J.; Haug, K.; Schwenke, D. W.

1988-01-01

Numerically exact, fully three-dimensional quantum mechanicl reactive scattering calculations are reported for the H2Br system. Both the exchange (H + H-prime Br to H-prime + HBr) and abstraction (H + HBR to H2 + Br) reaction channels are included in the calculations. The present results are the first completely converged three-dimensional quantum calculations for a system involving a highly exoergic reaction channel (the abstraction process). It is found that the production of vibrationally hot H2 in the abstraction reaction, and hence the extent of population inversion in the products, is a sensitive function of initial HBr rotational state and collision energy.
Tutorial Review: Simulation of Oscillating Chemical Reactions Using Microsoft Excel Macros

Directory of Open Access Journals (Sweden)

Abdolhossein Naseri

2016-12-01

Full Text Available Oscillating reactions are one of the most interesting topics in chemistry and analytical chemistry. Fluctuations in concentrations of one the reacting species (usually a reaction intermediate create an oscillating chemical reaction. In oscillating systems, the reaction is far from thermodynamic equilibrium. In these systems, at least one autocatalytic step is required. Developing an instinctive feeling for how oscillating reactions work will be invaluable to future generations of chemists. Some software programs have been released for simulating oscillating systems; however, the algorithm details of such software are not transparent to chemists. In contrast, function of spreadsheet tools, like Microsoft Excel, is well understood, and the software is nearly universally available. In this work, the simulation and visualization of different oscillating systems are performed using Microsoft excel. The simple repetitive solving of the ordinary differential equation of an autocatalytic reaction (a spreadsheet row followed by time, easily automated by a subroutine (a “Macro” in Excel, readily simulates an oscillating reaction. This permits the simulation of some oscillating systems such asBelousov-Zhabotinsky. The versatility of an easily understandable computational platform further enables the simulation of the effects of linear and nonlinear parameters such as concentrations of reactants and catalyst, and kinetic constants. These parameters are readily changed to examine their effects.
Hypersensitivity reactions in patients receiving hemodialysis.

Science.gov (United States)

Butani, Lavjay; Calogiuri, Gianfranco

2017-06-01

To describe hypersensitivity reactions in patients receiving maintenance hemodialysis. PubMed search of articles published during the past 30 years with an emphasis on publications in the past decade. Case reports and review articles describing hypersensitivity reactions in the context of hemodialysis. Pharmacologic agents are the most common identifiable cause of hypersensitivity reactions in patients receiving hemodialysis. These include iron, erythropoietin, and heparin, which can cause anaphylactic or pseudoallergic reactions, and topical antibiotics and anesthetics, which lead to delayed-type hypersensitivity reactions. Many hypersensitivity reactions are triggered by complement activation and increased bradykinin resulting from contact system activation, especially in the context of angiotensin-converting enzyme inhibitor use. Several alternative pharmacologic preparations and dialyzer membranes are available, such that once an etiology for the reaction is established, recurrences can be prevented without affecting the quality of care provided to patients. Although hypersensitivity reactions are uncommon in patients receiving hemodialysis, they can be life-threatening. Moreover, considering the large prevalence of the end-stage renal disease population, the implications of such reactions are enormous. Most reactions are pseudoallergic and not mediated by immunoglobulin E. The multiplicity of potential exposures and the complexity of the environment to which patients on dialysis are exposed make it challenging to identify the precise cause of these reactions. Great diligence is needed to investigate hypersensitivity reactions to avoid recurrence in this high-risk population. Copyright © 2017 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.
Studies of complex fragment emission in heavy ion reactions

International Nuclear Information System (INIS)

Charity, R.J.; Sobotka, L.G.

1993-01-01

The study of intermediate-energy heavy-ion nuclear reactions is reported. This work has two foci: the properties of nuclear matter under abnormal conditions, in this energy domain, predominately low densities and the study of the relevant reaction mechanisms. Nuclear matter properties, such as phase transitions, are reflected in the dynamics of the reactions. The process leads to an understanding of the reaction mechanism themselves and therefore to the response characteristics of finite, perhaps non-equilibrium, strongly interacting systems. The program has the following objectives: to study energy, mass, and angular momentum deposition by studying incomplete fusion reactions; to gain confidence in the understanding of how highly excited systems decompose by studying all emissions from the highly excited systems; to push these kinds of studies into the intermediate energy domain (where intermediate mass fragment emission is not improbable) with excitation function studies; and to learn about the dynamics of the decays using particle-particle correlations. The last effort focuses on simple systems, where definitive statements are possible. These avenues of research share a common theme, large complex fragment production. It is this feature, more than any other, which distinguishes the intermediate energy domain
Vibrational-rotational excitation: chemical reactions of vibrationally excited molecules

International Nuclear Information System (INIS)

Moore, C.B.; Smith, I.W.M.

1979-03-01

This review considers a limited number of systems, particularly gas-phase processes. Excited states and their preparation, direct bimolecular reactions, reactions of highly excited molecules, and reactions in condensed phases are discussed. Laser-induced isotope separation applications are mentioned briefly. 109 references
Unimolecular and collisionally induced ion reactions

International Nuclear Information System (INIS)

Beynon, J.H.; Boyd, R.K.

1978-01-01

The subject is reviewed under the following headings: introduction (mass spectroscopy and the study of fragmentation reactions of gaseous positive ions); techniques and methods (ion sources, detection systems, analysis of ions, data reduction); collision-induced reactions of ions and unimolecular fragmentations of metastable ions; applications (ion structure, energetic measurements, analytical applications, other applications). 305 references. (U.K.)
Drug Reaction with Eosinophilia and Systemic Symptom in a Patient with Pneumonia and Hyperthyroidism.

Science.gov (United States)

Jin, Hualiang; Wang, Limin; Ye, Jian

2017-01-01

Drug rash with eosinophilia and systemic symptoms syndrome is an idiosyncratic drug reaction characterized by fever, skin eruption, lymph node enlargement, and internal organ involvement. We report a case of a patient with pneumonia who developed clinical manifestations of fever, rash, lymphadenopathy, hypereosinophilia, and visceral involvement (renal failure and eosinophilic pneumonitis) caused by methimazole. The patient improved remarkably with drug withdrawal. A high index of clinical suspicion is emphasized to facilitate prompt diagnosis of medication-related adverse effect and its discontinuation.
Analysis of kinetic reaction mechanisms

CERN Document Server

Turányi, Tamás

2014-01-01

Chemical processes in many fields of science and technology, including combustion, atmospheric chemistry, environmental modelling, process engineering, and systems biology, can be described by detailed reaction mechanisms consisting of numerous reaction steps. This book describes methods for the analysis of reaction mechanisms that are applicable in all these fields. Topics addressed include: how sensitivity and uncertainty analyses allow the calculation of the overall uncertainty of simulation results and the identification of the most important input parameters, the ways in which mechanisms can be reduced without losing important kinetic and dynamic detail, and the application of reduced models for more accurate engineering optimizations. This monograph is invaluable for researchers and engineers dealing with detailed reaction mechanisms, but is also useful for graduate students of related courses in chemistry, mechanical engineering, energy and environmental science and biology.
Asymptotic behavior of equilibrium states of reaction-diffusion systems with mass conservation

Science.gov (United States)

Chern, Jann-Long; Morita, Yoshihisa; Shieh, Tien-Tsan

2018-01-01

We deal with a stationary problem of a reaction-diffusion system with a conservation law under the Neumann boundary condition. It is shown that the stationary problem turns to be the Euler-Lagrange equation of an energy functional with a mass constraint. When the domain is the finite interval (0 , 1), we investigate the asymptotic profile of a strictly monotone minimizer of the energy as d, the ratio of the diffusion coefficient of the system, tends to zero. In view of a logarithmic function in the leading term of the potential, we get to a scaling parameter κ satisfying the relation ε : =√{ d } =√{ log ⁡ κ } /κ2. The main result shows that a sequence of minimizers converges to a Dirac mass multiplied by the total mass and that by a scaling with κ the asymptotic profile exhibits a parabola in the nonvanishing region. We also prove the existence of an unstable monotone solution when the mass is small.
Rate Constant Change of Photo Reaction of Bacteriorhodopsin Observed in Trimeric Molecular System.

Science.gov (United States)

Tsujiuchi, Yutaka; Masumoto, Hiroshi; Goto, Takashi

2016-04-01

To elucidate the time evolution of photo reaction of bacteriorhodopsin in glycerol mixed purple membrane at around 196 K under irradiation by red light, a kinetic model was constructed. The change of absorption with irradiation at times of 560 nm and 412 nm was analyzed for the purpose of determining reaction rates of photo reaction of bacteriorhodopsin and its product M intermediate. In this study it is shown that reaction rates of conversion from bacteriorhodopsin to the M intermediate can be explained by a set of linear differential equations. This model analysis concludes that bacteriorhodopsin in which constitutes a trimer unit with other two bacteriorhodopsin molecules changes into M intermediates in the 1.73 of reaction rate, in the initial step, and according to the number of M intermediate in a trimer unit, from three to one, the reaction rate of bacteriorhodopsin into M intermediates smaller as 1.73, 0.80, 0.19 which caused by influence of inter-molecular interaction between bacteriorhodopsin.
Evaluation of maillard reaction variables and their effect on heterocyclic amine formation in chemical model systems.

Science.gov (United States)

Dennis, Cara; Karim, Faris; Smith, J Scott

2015-02-01

Heterocyclic amines (HCAs), highly mutagenic and potentially carcinogenic by-products, form during Maillard browning reactions, specifically in muscle-rich foods. Chemical model systems allow examination of in vitro formation of HCAs while eliminating complex matrices of meat. Limited research has evaluated the effects of Maillard reaction parameters on HCA formation. Therefore, 4 essential Maillard variables (precursors molar concentrations, water amount, sugar type, and sugar amounts) were evaluated to optimize a model system for the study of 4 HCAs: 2-amino-3-methylimidazo-[4,5-f]quinoline, 2-amino-3-methylimidazo[4,5-f]quinoxaline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, and 2-amino-3,4,8-trimethyl-imidazo[4,5-f]quinoxaline. Model systems were dissolved in diethylene glycol, heated at 175 °C for 40 min, and separated using reversed-phase liquid chromatography. To define the model system, precursor amounts (threonine and creatinine) were adjusted in molar increments (0.2/0.2, 0.4/0.4, 0.6/0.6, and 0.8/0.8 mmol) and water amounts by percentage (0%, 5%, 10%, and 15%). Sugars (lactose, glucose, galactose, and fructose) were evaluated in several molar amounts proportional to threonine and creatinine (quarter, half, equi, and double). The precursor levels and amounts of sugar were significantly different (P < 0.05) in regards to total HCA formation, with 0.6/0.6/1.2 mmol producing higher levels. Water concentration and sugar type also had a significant effect (P < 0.05), with 5% water and lactose producing higher total HCA amounts. A model system containing threonine (0.6 mmol), creatinine (0.6 mmol), and glucose (1.2 mmol), with 15% water was determined to be the optimal model system with glucose and 15% water being a better representation of meat systems. © 2015 Institute of Food Technologists®
A Multilevel Adaptive Reaction-splitting Simulation Method for Stochastic Reaction Networks

KAUST Repository

Moraes, Alvaro; Tempone, Raul; Vilanova, Pedro

2016-01-01

In this work, we present a novel multilevel Monte Carlo method for kinetic simulation of stochastic reaction networks characterized by having simultaneously fast and slow reaction channels. To produce efficient simulations, our method adaptively classifies the reactions channels into fast and slow channels. To this end, we first introduce a state-dependent quantity named level of activity of a reaction channel. Then, we propose a low-cost heuristic that allows us to adaptively split the set of reaction channels into two subsets characterized by either a high or a low level of activity. Based on a time-splitting technique, the increments associated with high-activity channels are simulated using the tau-leap method, while those associated with low-activity channels are simulated using an exact method. This path simulation technique is amenable for coupled path generation and a corresponding multilevel Monte Carlo algorithm. To estimate expected values of observables of the system at a prescribed final time, our method bounds the global computational error to be below a prescribed tolerance, TOL, within a given confidence level. This goal is achieved with a computational complexity of order O(TOL-2), the same as with a pathwise-exact method, but with a smaller constant. We also present a novel low-cost control variate technique based on the stochastic time change representation by Kurtz, showing its performance on a numerical example. We present two numerical examples extracted from the literature that show how the reaction-splitting method obtains substantial gains with respect to the standard stochastic simulation algorithm and the multilevel Monte Carlo approach by Anderson and Higham. © 2016 Society for Industrial and Applied Mathematics.
A Multilevel Adaptive Reaction-splitting Simulation Method for Stochastic Reaction Networks

KAUST Repository

Moraes, Alvaro

2016-07-07

In this work, we present a novel multilevel Monte Carlo method for kinetic simulation of stochastic reaction networks characterized by having simultaneously fast and slow reaction channels. To produce efficient simulations, our method adaptively classifies the reactions channels into fast and slow channels. To this end, we first introduce a state-dependent quantity named level of activity of a reaction channel. Then, we propose a low-cost heuristic that allows us to adaptively split the set of reaction channels into two subsets characterized by either a high or a low level of activity. Based on a time-splitting technique, the increments associated with high-activity channels are simulated using the tau-leap method, while those associated with low-activity channels are simulated using an exact method. This path simulation technique is amenable for coupled path generation and a corresponding multilevel Monte Carlo algorithm. To estimate expected values of observables of the system at a prescribed final time, our method bounds the global computational error to be below a prescribed tolerance, TOL, within a given confidence level. This goal is achieved with a computational complexity of order O(TOL-2), the same as with a pathwise-exact method, but with a smaller constant. We also present a novel low-cost control variate technique based on the stochastic time change representation by Kurtz, showing its performance on a numerical example. We present two numerical examples extracted from the literature that show how the reaction-splitting method obtains substantial gains with respect to the standard stochastic simulation algorithm and the multilevel Monte Carlo approach by Anderson and Higham. © 2016 Society for Industrial and Applied Mathematics.
Caging in high energy reactions

International Nuclear Information System (INIS)

Ache, H.J.

1977-01-01

The concept of caging high energy reactions is considered. It is noted that there is no easy and unambiguous way, short of a complete and very tedious product and mechanistic analysis, which is feasible only for very few systems, to determine the contribution made by caging. It is emphasized that some products resulting from the hot reaction with a certain substrate may be formed via caging while others are not. In research on the mechanism of caging the results of Roots work on the reactions of hot 18 F with the CF 3 CH 3 system seem to provide evidence for caging, with 18 F being the caged moiety, thus proceeding via a radical--radical recombination mechanism. Their work with H 2 S additive also seems to indicate that scavenging via hydrogen abstraction from H 2 S to form does not interfere with the radical--radical recombination consistent with Bunkers molecular approach to explain the cage effects. In other research a series of observations resulting from stereochemical and combined stereochemical density variation techniques seem to favor a caged-complex. It is clear that a more conclusive answer can only be reached by more systematic studies, utilizing the whole range of nuclear reactions such as (n,2n), (n,γ) and E.C. processes in mechanistically well defined systems to elucidate the effect of variations in the recoil energies, by carrying out studies in different solvents or host substances to assess the effect of the physical parameters, such as molecule size and intermolecular interactions on the escape probability or caging efficiencies
Dynamics of synchrotron VUV-induced intracluster reactions

Energy Technology Data Exchange (ETDEWEB)

Grover, J.R. [Brookhaven National Laboratory, Upton, NY (United States)

1993-12-01

Photoionization mass spectrometry (PIMS) using the tunable vacuum ultraviolet radiation available at the National Synchrotron Light Source is being exploited to study photoionization-induced reactions in small van der Waals mixed complexes. The information gained includes the observation and classification of reaction paths, the measurement of onsets, and the determination of relative yields of competing reactions. Additional information is obtained by comparison of the properties of different reacting systems. Special attention is given to finding unexpected features, and most of the reactions investigated to date display such features. However, understanding these reactions demands dynamical information, in addition to what is provided by PIMS. Therefore the program has been expanded to include the measurement of kinetic energy release distributions.
Modular verification of chemical reaction network encodings via serializability analysis

Science.gov (United States)

Lakin, Matthew R.; Stefanovic, Darko; Phillips, Andrew

2015-01-01

Chemical reaction networks are a powerful means of specifying the intended behaviour of synthetic biochemical systems. A high-level formal specification, expressed as a chemical reaction network, may be compiled into a lower-level encoding, which can be directly implemented in wet chemistry and may itself be expressed as a chemical reaction network. Here we present conditions under which a lower-level encoding correctly emulates the sequential dynamics of a high-level chemical reaction network. We require that encodings are transactional, such that their execution is divided by a “commit reaction” that irreversibly separates the reactant-consuming phase of the encoding from the product-generating phase. We also impose restrictions on the sharing of species between reaction encodings, based on a notion of “extra tolerance”, which defines species that may be shared between encodings without enabling unwanted reactions. Our notion of correctness is serializability of interleaved reaction encodings, and if all reaction encodings satisfy our correctness properties then we can infer that the global dynamics of the system are correct. This allows us to infer correctness of any system constructed using verified encodings. As an example, we show how this approach may be used to verify two- and four-domain DNA strand displacement encodings of chemical reaction networks, and we generalize our result to the limit where the populations of helper species are unlimited. PMID:27325906
[Synthetic Studies of Bioactive Heterocyclic Natural Products and Fused Heterocyclic Compounds Based on the Thermal Electrocyclic or Azaelectocyclic Reaction of 6π-Electron or Aza-6π-electron Systems].

Science.gov (United States)

Hibino, Satoshi

2016-01-01

Since 1979, synthetic studies of bioactive heterocyclic natural products and condensed heteroaromatic compounds based on the thermal electrocyclic reaction of 6π-electron or aza-6π-electron systems incorporating the double bond of the principal aromatic or heteroaromatic ring have been conducted by our research group. In this review, five types of electrocyclic and azaelectrocyclic reaction are described: 1) the synthesis of the carbazole alkaloids hyellazole and 6-chlorohyellazole through the electrocyclic reaction of 2,3-bisalkenylindoles; 2) synthetic studies of the pyridocarbazole alkaloids ellipticine and olivacine through the electrocyclic reactions of the indole-2,3- and pyridine-3,4-quinodimethane intermediates; 3) synthetic studies of polysubstituted carbazole alkaloids through the allene-mediated electrocyclic reactions involving the indole 2,3-bond; 4) synthetic studies of fused pyridine rings through the azaelectrocyclic reaction of the 1-aza-6π-electron system using the oxime or oxime ether; and 5) synthetic studies of fused pyridine rings through the azaelectrocyclic reaction of the 2-aza-6π-electron system using a carbodiimide or isocyanate.
Outline of an ultracorrector compensating for all primary chromatic and geometrical aberrations of charged-particle lenses

International Nuclear Information System (INIS)

Rose, Harald

2004-01-01

A novel ultracorrector is outlined which compensates for the primary and secondary first-order chromatic aberrations and all third-order geometrical aberrations of electron optical systems with a straight axis. Owing to the imposed symmetry conditions on the fields and the paraxial fundamental rays, the corrector does not introduce aberrations with 2-fold symmetry. The chromatic aberrations are corrected by means of crossed electric magnetic quadrupoles while the third-order geometrical aberrations are eliminated by octopoles. By placing these elements at distinct positions within the corrector, it is possible to successively eliminate the third-order aberrations in such a way that each subsequent correction does not affect the aberrations corrected in the preceding correction steps
A variational approach to bifurcation points of a reaction-diffusion system with obstacles and neumann boundary conditions

Czech Academy of Sciences Publication Activity Database

Eisner, Jan; Kučera, Milan; Väth, Martin

2016-01-01

Roč. 61, č. 1 (2016), s. 1-25 ISSN 0862-7940 R&D Projects: GA ČR GA13-12580S Institutional support: RVO:67985904 ; RVO:67985840 Keywords : reaction-diffusion system * unlateral condition * variational inequality Subject RIV: EG - Zoology; BA - General Mathematics (MU-W) Impact factor: 0.618, year: 2016
A reaction-based paradigm to model reactive chemical transport in groundwater with general kinetic and equilibrium reactions

International Nuclear Information System (INIS)

Zhang, Fan; Yeh, Gour-Tsyh; Parker, Jack C.; Brooks, Scott C; Pace, Molly; Kim, Young Jin; Jardine, Philip M.; Watson, David B.

2007-01-01

This paper presents a reaction-based water quality transport model in subsurface flow systems. Transport of chemical species with a variety of chemical and physical processes is mathematically described by M. partial differential equations (PDEs). Decomposition via Gauss-Jordan column reduction of the reaction network transforms M. species reactive transport equations into two sets of equations: a set of thermodynamic equilibrium equations representing NE equilibrium reactions and a set of reactive transport equations of M-NE kinetic-variables involving no equilibrium reactions (a kinetic-variable is a linear combination of species). The elimination of equilibrium reactions from reactive transport equations allows robust and efficient numerical integration. The model solves the PDEs of kinetic-variables rather than individual chemical species, which reduces the number of reactive transport equations and simplifies the reaction terms in the equations. A variety of numerical methods are investigated for solving the coupled transport and reaction equations. Simulation comparisons with exact solutions were performed to verify numerical accuracy and assess the effectiveness of various numerical strategies to deal with different application circumstances. Two validation examples involving simulations of uranium transport in soil columns are presented to evaluate the ability of the model to simulate reactive transport with complex reaction networks involving both kinetic and equilibrium reactions

A reaction-based paradigm to model reactive chemical transport in groundwater with general kinetic and equilibrium reactions.

Science.gov (United States)

Zhang, Fan; Yeh, Gour-Tsyh; Parker, Jack C; Brooks, Scott C; Pace, Molly N; Kim, Young-Jin; Jardine, Philip M; Watson, David B

2007-06-16

This paper presents a reaction-based water quality transport model in subsurface flow systems. Transport of chemical species with a variety of chemical and physical processes is mathematically described by M partial differential equations (PDEs). Decomposition via Gauss-Jordan column reduction of the reaction network transforms M species reactive transport equations into two sets of equations: a set of thermodynamic equilibrium equations representing N(E) equilibrium reactions and a set of reactive transport equations of M-N(E) kinetic-variables involving no equilibrium reactions (a kinetic-variable is a linear combination of species). The elimination of equilibrium reactions from reactive transport equations allows robust and efficient numerical integration. The model solves the PDEs of kinetic-variables rather than individual chemical species, which reduces the number of reactive transport equations and simplifies the reaction terms in the equations. A variety of numerical methods are investigated for solving the coupled transport and reaction equations. Simulation comparisons with exact solutions were performed to verify numerical accuracy and assess the effectiveness of various numerical strategies to deal with different application circumstances. Two validation examples involving simulations of uranium transport in soil columns are presented to evaluate the ability of the model to simulate reactive transport with complex reaction networks involving both kinetic and equilibrium reactions.
Escherichia coli Phosphoenolpyruvate-Dependent Phosphotransferase System. Functional Asymmetry in Enzyme I Subunits Demonstrated by Reaction with 3-Bromopyruvate

NARCIS (Netherlands)

Hoeve-Duurkens, Ria ten; Robillard, George T.

1984-01-01

In the bacterial phosphoenolpyruvate-dependent sugar transport systems, enzyme I (EI) is responsible for the initial reaction step which is the transfer of the phosphoryl group from phosphoenolpyruvate to a cytoplasmic phosphocarrier protein (HPr). The inactivation of enzyme I by the substrate
Online reputation systems: The effects of feedback comments and reactions on building and rebuilding trust in online auctions

NARCIS (Netherlands)

Utz, S.; Matzat, U.; Snijders, C.

2009-01-01

Previous research on reputation systems primarily focused on their trust-building function. The present research addresses their trust-rebuilding function-specifically, the role of the short text comments given in reaction to negative feedback. Rebuilding trust is often necessary because on-line
Potential surfaces in symmetric heavy-ion reactions

International Nuclear Information System (INIS)

Royer, G.; Piller, C.; Mignen, J.; Raffray, Y.

1989-01-01

The entrance channel in symmetric heavy-ion reactions is studied in the liquid-drop model approach including the nuclear proximity energy and allowing ellipsoidal deformations of the colliding nuclei. In the whole mass range a sudden transition occurs from oblate to prolate shapes when the proximity forces become important. This strongly affects the effective moment of inertia. The ellipsoidal deformations reduce the fusion barrier width for light systems and lower the potential barrier height for medium and heavy nuclei. The results are in agreement with the empirical effective barrier shift determined by Aguiar et al for the 58 Ni + 58 Ni, 74 Ge + 74 Ge and 80 Se + 80 Se systems. The sub-barrier fusion enhancement in heavy-ion reactions might be explained by the slowness of the process. Below the static fusion barrier, the reaction time is long; allowing some adiabaticity and deformations of the colliding ions. Above the barrier, the reaction is more sudden and the deformation degree of freedom is frozen
A STUDY ON ADVERSE DRUG REACTIONS INVOLVING CENTRAL NERVOUS SYSTEM, ITS SEVERITY AND CAUSALITY ASSESSMENT IN PEDIATRIC PATIENTS ADMITTED TO A TERTIARY CARE HOSPITAL

Directory of Open Access Journals (Sweden)

Arati

2015-09-01

Full Text Available A retrospective study was conducted in Department of pediatrics SCB Medical College and SVPPGIP for a period of 2 years i.e. September 2012 to August 2014 . All the patients from birth to 14 years admitted to the pediatric ward in this study were under ADR surveillance. Patients admitted to our hospital with adverse drug reaction o r patients developing adverse drug reaction in our hospital were studied; only those cases where the central nervous system was involved were taken in our study. The cases were compiled and the causality of offending drugs was found using WHO - UMC causality assessment score. The severity of drug reaction in every case was determined by using HARTWIG’s severity scoring scale. Total 350 Adverse reactions were reported in this period with prevalence rate of 2.04% i.e. 20 out of 1000 children faced ADR due to dr ugs, with annual incidence rate of 0.9% and 1.14% over two years. Out of total 350 cases dermatological system was most commonly involved i.e. 207 cases (59.14%. This is followed by involvement of central nervous system 46 number of cases (13.14%. The GI system was involved in 34 cases i.e. (9.71%. Life threatening reactions like anaphylaxis, angioedema and shock like immediate life threatening ADRs were reported in 16 cases. Our study group was the patient in whom the ADR involved the CNS. Out of 46 suc h cases, there were 25 female and 21 male. Various reaction due to drug were encephalopathy , eps, febrile seizure, tremor, head reeling, ototoxicity, persistant cry, pseudotumor cerebri, psychosis, seizure, status epilepticus, toxic amblyopia, tremor, atax ia etc. The most common CNS manifestation was Extra pyramidal side effects (EPS involving 21% of cases. The most common Drug causing CNS manifestation was ATT (HRZE causing blindness, Eps, psychosis , toxic amblyopia blindness etc.
Combustion kinetics and reaction pathways

Energy Technology Data Exchange (ETDEWEB)

Klemm, R.B.; Sutherland, J.W. [Brookhaven National Laboratory, Upton, NY (United States)

1993-12-01

This project is focused on the fundamental chemistry of combustion. The overall objectives are to determine rate constants for elementary reactions and to elucidate the pathways of multichannel reactions. A multitechnique approach that features three independent experiments provides unique capabilities in performing reliable kinetic measurements over an exceptionally wide range in temperature, 300 to 2500 K. Recent kinetic work has focused on experimental studies and theoretical calculations of the methane dissociation system (CH{sub 4} + Ar {yields} CH{sub 3} + H + Ar and H + CH{sub 4} {yields} CH{sub 3} + H{sub 2}). Additionally, a discharge flow-photoionization mass spectrometer (DF-PIMS) experiment is used to determine branching fractions for multichannel reactions and to measure ionization thresholds of free radicals. Thus, these photoionization experiments generate data that are relevant to both reaction pathways studies (reaction dynamics) and fundamental thermochemical research. Two distinct advantages of performing PIMS with high intensity, tunable vacuum ultraviolet light at the National Synchrotron Light Source are high detection sensitivity and exceptional selectivity in monitoring radical species.
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.
Japan Nuclear Reaction Data Centre (JCPRG), Progress Report

International Nuclear Information System (INIS)

Aikawa, M.

2012-01-01

In this report, we review the activities of Japan Nuclear Reaction Data Centre (JCPRG) since the last NRDC meeting in 2011. Our main objectives are as follows: a) Compilation of nuclear reaction data for two databases, NRDF and EXFOR b) Evaluation of astrophysical nuclear reaction data c) Development of software and systems d) Development of collaboration among Asian countries. (author)
Computing molecular fluctuations in biochemical reaction systems based on a mechanistic, statistical theory of irreversible processes.

Science.gov (United States)

Kulasiri, Don

2011-01-01

We discuss the quantification of molecular fluctuations in the biochemical reaction systems within the context of intracellular processes associated with gene expression. We take the molecular reactions pertaining to circadian rhythms to develop models of molecular fluctuations in this chapter. There are a significant number of studies on stochastic fluctuations in intracellular genetic regulatory networks based on single cell-level experiments. In order to understand the fluctuations associated with the gene expression in circadian rhythm networks, it is important to model the interactions of transcriptional factors with the E-boxes in the promoter regions of some of the genes. The pertinent aspects of a near-equilibrium theory that would integrate the thermodynamical and particle dynamic characteristics of intracellular molecular fluctuations would be discussed, and the theory is extended by using the theory of stochastic differential equations. We then model the fluctuations associated with the promoter regions using general mathematical settings. We implemented ubiquitous Gillespie's algorithms, which are used to simulate stochasticity in biochemical networks, for each of the motifs. Both the theory and the Gillespie's algorithms gave the same results in terms of the time evolution of means and variances of molecular numbers. As biochemical reactions occur far away from equilibrium-hence the use of the Gillespie algorithm-these results suggest that the near-equilibrium theory should be a good approximation for some of the biochemical reactions. © 2011 Elsevier Inc. All rights reserved.
Development of automatic nuclear emulsion plate analysis system and its application to elementary particle reactions, 2

International Nuclear Information System (INIS)

Ushida, Noriyuki; Otani, Masashi; Kumazaki, Noriyasu

1984-01-01

This system is composed of precise coordinate measuring apparatuses, a stage controller and various peripherals, employing NOVA 4/C as the host computer. The analyzed results are given as the output to a printer or an XY plotter. The data required for experiment, sent from Nagoya University and others, are received by the host computer through an acoustic coupler, and stored in floppy disks. This paper contains simple explanation on the monitor for the events which occur immediately after the on-line measurement ''MTF 1'', the XY plotter and the acoustic coupler, which hold important position in the system in spite of low cost, due to the development of useful program, as those were not described in the previous paper. The three-dimensional reconstruction of tracks and various errors, corrective processing and analytical processing after corrective processing as off-line processing are also described. In addition, the application of the system was made to the E-531 neutrino experiment in Fermi National Accelerator Laboratory, which attempted to measure the life of the charm particles generated in neutrino reaction with a composite equipment composed of nuclear plates and various counters. First, the outline of the equipment, next, the location of neutrino reaction and the surveillance of charm particle decay using MTF program as the analyzing method at the target, and thirdly, the emulsion-counter data fitting are explained, respectively. (Wakatsuki, Y.)
Stability and Hopf Bifurcation of a Reaction-Diffusion Neutral Neuron System with Time Delay

Science.gov (United States)

Dong, Tao; Xia, Linmao

2017-12-01

In this paper, a type of reaction-diffusion neutral neuron system with time delay under homogeneous Neumann boundary conditions is considered. By constructing a basis of phase space based on the eigenvectors of the corresponding Laplace operator, the characteristic equation of this system is obtained. Then, by selecting time delay and self-feedback strength as the bifurcating parameters respectively, the dynamic behaviors including local stability and Hopf bifurcation near the zero equilibrium point are investigated when the time delay and self-feedback strength vary. Furthermore, the direction of the Hopf bifurcation and the stability of bifurcating periodic solutions are obtained by using the normal form and the center manifold theorem for the corresponding partial differential equation. Finally, two simulation examples are given to verify the theory.
Development of a system of measuring double-differential cross sections for proton-induced reactions

Energy Technology Data Exchange (ETDEWEB)

Harada, M.; Watanabe, Y.; Sato, K. [Kyushu Univ., Fukuoka (Japan); Meigo, S.

1997-03-01

We report the present status of a counter telescope and a data acquisition system which are being developed for the measurement of double-differential cross sections of all light-charged particles emitted from proton-induced reactions on {sup 12}C at incident energies less than 90 MeV. The counter telescope consists of an active collimator made of a plastic scintillator, two thin silicon {Delta}E-detectors and a CsI(Tl) E-detectors with photo-diode readout. Signals from each detector are processed using the data acquisition system consisting of the front-end electronics (CAMAC) and two computers connected with the ethernet LAN: a personal computer as the data collector and server, and a UNIX workstation as the monitor and analyzer. (author)
Drug Reactions in Oral Mucosa

Directory of Open Access Journals (Sweden)

Emine Derviş

2012-12-01

Full Text Available Both immunologic and nonimmunologic drug reactions can be seen in oral mucosa. Since considerable number of these reactions heals spontaneously without being noticed by the patients, exact frequency of the lesions is unknown. Most common lesions are xerostomia, taste disorders, mucosal ulcerations and edema. In this article, oral lesions resulting from drug intake similar to those from oral lesions of local and systemic diseases, and diagnostic problems caused by these similarities, have been reviewed.
The hexadehydro-Diels-Alder reaction.

Science.gov (United States)

Hoye, Thomas R; Baire, Beeraiah; Niu, Dawen; Willoughby, Patrick H; Woods, Brian P

2012-10-11

Arynes (aromatic systems containing, formally, a carbon-carbon triple bond) are among the most versatile of all reactive intermediates in organic chemistry. They can be 'trapped' to give products that are used as pharmaceuticals, agrochemicals, dyes, polymers and other fine chemicals. Here we explore a strategy that unites the de novo generation of benzynes-through a hexadehydro-Diels-Alder reaction-with their in situ elaboration into structurally complex benzenoid products. In the hexadehydro-Diels-Alder reaction, a 1,3-diyne is engaged in a [4+2] cycloisomerization with a 'diynophile' to produce the highly reactive benzyne intermediate. The reaction conditions for this simple, thermal transformation are notable for being free of metals and reagents. The subsequent and highly efficient trapping reactions increase the power of the overall process. Finally, we provide examples of how this de novo benzyne generation approach allows new modes of intrinsic reactivity to be revealed.
Nuclear reaction studies using inverse kinematics

International Nuclear Information System (INIS)

Shapira, D.

1985-01-01

Reaction studies with reversed kinematics refer to studies of nuclear reactions induced by a heavy projectile colliding with lighter target nuclei. The technique of using reversed kinematics is costly in terms of the available center-of-mass energy. Most of the projectile's energy goes into forward motion of the reaction products in the laboratory system. Examples are presented where the use of reversed kinematics techniques has provided new information on certain reaction processes. A list of kinematic properties and advantages they may afford is shown. Clearly the possible studies listed can be done without using reversed kinematics but because of the difficulty associated with some of these studies they were never performed until more energetic heavier beams have become available and the reversed kinematics technique was utilized
Reaction rate of hydrolysis of iodine

International Nuclear Information System (INIS)

Miyake, Yoshikazu; Eguchi, Wataru; Adachi, Motonari

1979-01-01

Absorption rates of dilute iodine vapor contained in air by aqueous mixtures of sodium hydroxide and boric acid were measured using a laminar liquid jet column absorber at 298 K. Absorption rates in this system are controlled by a series of complex reactions taking place in the liquid phase. The reaction rate constant of iodine hydrolysis in the aqueous phase was determined from the absorption rates observed under the conditions that the base-catalytic hydrolysis reaction of iodine can be considered to be irreversible and that other reactions can be neglected. The absorption rates calculated theoretically with the rate constant value obtained above were in good accordance with the whole experimental data observed for a wide range of experimental conditions. (author)
Reaction sintering of ceramic-metal composites

International Nuclear Information System (INIS)

Botta Filho, W.J.; Rodrigues, J.A.; Tomasi, R.; Pandolfelli, V.C.; Passos, J.F.S.S.; Folgueras, M.V.

1990-01-01

Reaction sintering experiments have been carried out in the system Al 2 O 3 -ZrAl 2 -Nb 2 O 5 with the objective of producing ceramic-metal composites of improved toughness. The sintering treatments have been done in the temperature range of 700 0 C to 1400 0 C under different conditions of vacuum and in air and argon atmospheres. The treated samples have been analysed by X-ray diffraction and analytical electron microscopy. The results are discussed in function of the degree of reaction, the development of microstructure and the densification. These results have shown that although an exchange reaction can occur to produce a composite, the control of the reaction to obtain a dense microstructure has not been possible yet. (author) [pt
Systems biology and the origins of life? part II. Are biochemical networks possible ancestors of living systems? networks of catalysed chemical reactions: non-equilibrium, self-organization and evolution.

Science.gov (United States)

Ricard, Jacques

2010-01-01

The present article discusses the possibility that catalysed chemical networks can evolve. Even simple enzyme-catalysed chemical reactions can display this property. The example studied is that of a two-substrate proteinoid, or enzyme, reaction displaying random binding of its substrates A and B. The fundamental property of such a system is to display either emergence or integration depending on the respective values of the probabilities that the enzyme has bound one of its substrate regardless it has bound the other substrate, or, specifically, after it has bound the other substrate. There is emergence of information if p(A)>p(AB) and p(B)>p(BA). Conversely, if p(A)equilibrium. Moreover, in such systems, emergence results in an increase of the energy level of the ternary EAB complex that becomes closer to the transition state of the reaction, thus leading to the enhancement of catalysis. Hence a drift from quasi-equilibrium is, to a large extent, responsible for the production of information and enhancement of catalysis. Non-equilibrium of these simple systems must be an important aspect that leads to both self-organization and evolutionary processes. These conclusions can be extended to networks of catalysed chemical reactions. Such networks are, in fact, networks of networks, viz. meta-networks. In this formal representation, nodes are chemical reactions catalysed by poorly specific proteinoids, and links can be identified to the transport of metabolites from proteinoid to proteinoid. The concepts of integration and emergence can be applied to such situations and can be used to define the identity of these networks and therefore their evolution. Defined as open non-equilibrium structures, such biochemical networks possess two remarkable properties: (1) the probability of occurrence of their nodes is dependant upon the input and output of matter in, and from, the system and (2) the probability of occurrence of the nodes is strictly linked to their degree of
Chelate-Modified Fenton Reaction for the Degradation of Trichloroethylene in Aqueous and Two-Phase Systems

Energy Technology Data Exchange (ETDEWEB)

Lewis, Scott [Univ of KY, dept of chemical and materials engineering; lynch, Andrew [Univ of KY, dept of chemical and materials engineering; Bachas, Leonidas [Univ of KY, Dept of Chemistry; hampson, Steve [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Ormsbee, Lindelle [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Bhattacharyya, Dibakar [Univ of KY, dept of chemical and materials engineering

2008-06-01

The Standard Fenton reaction has been used for In-Situ Chemical Oxidation (ISCO) of toxic organics in groundwater. However, it requires low pH operating conditions, and thus has limitations for in situ applications. In addition, hydroxyl radicals are rapidly consumed by hydroxyl scavengers found in the subsurface. These problems are alleviated through the chelate-modified Fenton (hydroxyl radical) reaction, which includes the addition of nontoxic chelate (L) such as citrate or gluconic acid. This chelate allows the reaction to take place at bear neutral pH and control hydrogen peroxide consumption by binding to Fe(II), forming an FeL complex. The chelate also binds to Fe(III), preventing its precipitation as ferric hydroxide and thus prevents problems associated with injection well plugging. The rate of TCE dechlorination in chelate-modified Fenton systems is a function of pH, H2O2 concentration, and FE:L ratio. The primary objective of this research is to model and apply this process to the destruction of trichloroethylene (TCE) present in both the aqueous and organic (in the form of droplets) phases. Experimentation proved the chelate-modified Fenton reaction effectively dechlorinates TCE in both the aqueous and organic phases at near-neutral pH. Other focuses of this work include determining the effect of [L]:[Fe] ratios on H2O2 and TCE degradation as well as reusability of the FE citrate solution under repeated H2O2 injections. Generalized models were developed to predict the concentration of TCE in the aqueous phase and TCE droplet radius as a function of time using established hydroxyl radial kinetics and mass transfer relationships.
Uranium reactions with water vapor. Final progress report

International Nuclear Information System (INIS)

Condon, J.B.; Cristy, S.S.; Kirkpatrick, J.R.

1983-01-01

The reaction kinetics and ion microprobe mass analyzer (IMMA) depth-profile data for water-oxygen-uranium reaction is explained in terms of the perfusive-precipitation model. This model is reviewed extensively enough to deal with this interacting, 3-element reaction system. The model, based on simultaneous diffusion and product precipitation, can be applied to several systems in a parameterless fashion. It is applied to the uranium-water reaction in the absence and presence of the oxygen inhibitor. The results of the calculations of the model are compared to the experimental rates and the IMMA depth profiles obtained when 18 O-labeled water is used. The predictions are excellent for the pressure dependence of the rates, the activation energies for both the oxygen-poisoned and oxygen-free reactions, the absolute rates for the oxygen-poisoned case, and the IMMA depth profiles. The prediction of the absolute rate for the oxygen-free case is only within a factor of five due to the approximations made for the thermodynamics of the product layer that fixes the oxygen activity. Comparison of the model to experimental data for other metal-oxidation systems such as iron, silicon, copper, zirconium with oxygen, and thorium with water, is also presented to lend credibility to the modeling technique

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