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Sample records for chemically reactive non-isothermal

  1. Modeling non-isothermal multiphase multi-species reactive chemical transport in geologic media

    Energy Technology Data Exchange (ETDEWEB)

    Tianfu Xu; Gerard, F.; Pruess, K.; Brimhall, G.

    1997-07-01

    The assessment of mineral deposits, the analysis of hydrothermal convection systems, the performance of radioactive, urban and industrial waste disposal, the study of groundwater pollution, and the understanding of natural groundwater quality patterns all require modeling tools that can consider both the transport of dissolved species as well as their interactions with solid (or other) phases in geologic media and engineered barriers. Here, a general multi-species reactive transport formulation has been developed, which is applicable to homogeneous and/or heterogeneous reactions that can proceed either subject to local equilibrium conditions or kinetic rates under non-isothermal multiphase flow conditions. Two numerical solution methods, the direct substitution approach (DSA) and sequential iteration approach (SIA) for solving the coupled complex subsurface thermo-physical-chemical processes, are described. An efficient sequential iteration approach, which solves transport of solutes and chemical reactions sequentially and iteratively, is proposed for the current reactive chemical transport computer code development. The coupled flow (water, vapor, air and heat) and solute transport equations are also solved sequentially. The existing multiphase flow code TOUGH2 and geochemical code EQ3/6 are used to implement this SIA. The flow chart of the coupled code TOUGH2-EQ3/6, required modifications of the existing codes and additional subroutines needed are presented.

  2. Non-isothermal gas absorption with reversible chemical reaction

    NARCIS (Netherlands)

    Vas Bhat, R.D.; Swaaij, W.P.M. van; Benes, N.E.; Kuipers, J.A.M.; Versteeg, G.F.

    1997-01-01

    A fundamental description of non-isothermal mass transfer accompanied by a single reversible chemical reaction has been presented. The description is based on the Higbie penetration theory. Arrhenius type dependence of solubility, reaction rates and diffusivities on temperature has been assumed.

  3. Non-isothermal gas absorption with reversible chemical reaction.

    NARCIS (Netherlands)

    Vas bhat, R.D.; van Swaaij, Willibrordus Petrus Maria; Benes, Nieck Edwin; Kuipers, J.A.M.; Versteeg, Geert

    1997-01-01

    A fundamental description of non-isothermal mass transfer accompanied by a single reversible chemical reaction has been presented. The description is based on the Higbie penetration theory. Arrhenius type dependence of solubility, reaction rates and diffusivities on temperature has been assumed.

  4. TOURGHREACT: A Simulation Program for Non-isothermal MultiphaseReactive Geochemical Transport in Variably Saturated GeologicMedia

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu; Sonnenthal, Eric; Spycher, Nicolas; Pruess, Karsten

    2004-12-07

    TOUGHREACT is a numerical simulation program for chemically reactive non-isothermal flows of multiphase fluids in porous and fractured media. The program was written in Fortran 77 and developed by introducing reactive geochemistry into the multiphase fluid and heat flow simulator TOUGH2. A variety of subsurface thermo-physical-chemical processes are considered under a wide range of conditions of pressure, temperature, water saturation, ionic strength, and pH and Eh. Interactions between mineral assemblages and fluids can occur under local equilibrium or kinetic rates. The gas phase can be chemically active. Precipitation and dissolution reactions can change formation porosity and permeability. The program can be applied to many geologic systems and environmental problems, including geothermal systems, diagenetic and weathering processes, subsurface waste disposal, acid mine drainage remediation, contaminant transport, and groundwater quality. Here we present two examples to illustrate applicability of the program: (1) injectivity effects of mineral scaling in a fractured geothermal reservoir and (2) CO2 disposal in a deep saline aquifer.

  5. TOUGHREACT Version 2.0: A simulator for subsurface reactive transport under non-isothermal multiphase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, T.; Spycher, N.; Sonnenthal, E.; Zhang, G.; Zheng, L.; Pruess, K.

    2010-08-01

    TOUGHREACT is a numerical simulation program for chemically reactive non-isothermal flows of multiphase fluids in porous and fractured media, and was developed by introducing reactive chemistry into the multiphase fluid and heat flow simulator TOUGH2 V2. The first version of TOUGHREACT was released to the public through the U.S. Department of Energy's Energy Science and Technology Software Center (ESTSC) in August 2004. It is among the most frequently requested of ESTSC's codes. The code has been widely used for studies in CO{sub 2} geological sequestration, nuclear waste isolation, geothermal energy development, environmental remediation, and increasingly for petroleum applications. Over the past several years, many new capabilities have been developed, which were incorporated into Version 2 of TOUGHREACT. Major additions and improvements in Version 2 are discussed here, and two application examples are presented: (1) long-term fate of injected CO{sub 2} in a storage reservoir and (2) biogeochemical cycling of metals in mining-impacted lake sediments.

  6. A comparison of results obtained with two subsurface non-isothermal multiphase reactive transport simulators, FADES-CORE and TOUGHREACT

    Energy Technology Data Exchange (ETDEWEB)

    Juncosa Rivera, Ricardo; Xu, Tianfu; Pruess, Karsten

    2001-01-01

    FADES-CORE and TOUGHREACT are codes used to model the non-isothermal multiphase flow with multicomponent reactive transport in porous media. Different flow and reactive transport problems were used to compare the FADES-CORE and TOUGHREACT codes. These problems take into account the different cases of multiphase flow with and without heat transport, conservative transport, and reactive transport. Consistent results were obtained from both codes, which use different numerical methods to solve the differential equations resulting from the various physicochemical processes. Here we present the results obtained from both codes for various cases. Some results are slightly different with minor discrepancies, which have been remedied, so that both codes would be able to reproduce the same processes using the same parameters. One of the discrepancies found is related to the different calculation for thermal conductivity in heat transport, which affects the calculation of the temperatures, as well as the pH of the reaction of calcite dissolution problem modeled. Therefore it is possible to affirm that the pH is highly sensitive to temperature. Generally speaking, the comparison was concluded to be highly satisfactory, leading to the complete verification of the FADES-CORE code. However, we must keep in mind that, as there are no analytical solutions available with which to verify the codes, the TOUGHREACT code has been thoroughly corroborated, given that the only possible way to prove that the code simulation is correct, is by comparing the results obtained with both codes for the identical problems, or to validate the simulation results with actual measured data.

  7. TOUGHREACT User's Guide: A Simulation Program for Non-isothermal Multiphase Reactive geochemical Transport in Variable Saturated Geologic Media

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu; Sonnenthal, Eric; Spycher, Nicolas; Pruess, Karsten

    2004-05-24

    Coupled modeling of subsurface multiphase fluid and heat flow, solute transport and chemical reactions can be used for the assessment of mineral alteration in hydrothermal systems, waste disposal sites, acid mine drainage remediation, contaminant transport, and groundwater quality. A comprehensive non-isothermal multi-component reactive fluid flow and geochemical transport simulator, TOUGHREACT, has been developed. A wide range of subsurface thermo-physical-chemical processes is considered under various thermohydrological and geochemical conditions of pressure, temperature, water saturation, and ionic strength. The program can be applied to one-, two- or three-dimensional porous and fractured media with physical and chemical heterogeneity. The model can accommodate any number of chemical species present in liquid, gas and solid phases. A variety of equilibrium chemical reactions are considered, such as aqueous complexation, gas dissolution/exsolution, and cation exchange. Mineral dissolution/precipitation can proceed either subject to local equilibrium or kinetic conditions. Changes in porosity and permeability due to mineral dissolution and precipitation can be considered. Linear adsorption and decay can be included. For the purpose of future extensions, surface complexation by double layer model is coded in the program. Xu and Pruess (1998) developed a first version of a non-isothermal reactive geochemical transport model, TOUGHREACT, by introducing reactive geochemistry into the framework of the existing multi-phase fluid and heat flow code TOUGH2 (Pruess, 1991). Xu, Pruess, and their colleagues have applied the program to a variety of problems such as: (1) supergene copper enrichment (Xu et al, 2001), (2) caprock mineral alteration in a hydrothermal system (Xu and Pruess, 2001a), and (3) mineral trapping for CO{sub 2} disposal in deep saline aquifers (Xu et al, 2003b and 2004a). For modeling the coupled thermal, hydrological, and chemical processes during

  8. TOUGHREACT: a new code of the TOUGH Family for Non-Isothermal multiphase reactive geochemical transport in variably saturated geologic media

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu; Sonnenthal, Eric; Spycher, Nicolas; Pruess, Karsten

    2003-03-11

    Coupled modeling of subsurface multiphase fluid and heat flow, solute transport and chemical reactions can be used for the assessment of acid mine drainage remediation, waste disposal sites, hydrothermal convection, contaminant transport, and groundwater quality. We have developed a comprehensive numerical simulator, TOUGHREACT, which considers non-isothermal multi-component chemical transport in both liquid and gas phases. A wide range of subsurface thermo-physical-chemical processes is considered under various thermohydrological and geochemical conditions of pressure, temperature, water saturation, and ionic strength. The code can be applied to one-, two- or three-dimensional porous and fractured media with physical and chemical heterogeneity.

  9. A Non-Isothermal Chemical Lattice Boltzmann Model Incorporating Thermal Reaction Kinetics and Enthalpy Changes

    Directory of Open Access Journals (Sweden)

    Stuart Bartlett

    2017-08-01

    Full Text Available The lattice Boltzmann method is an efficient computational fluid dynamics technique that can accurately model a broad range of complex systems. As well as single-phase fluids, it can simulate thermohydrodynamic systems and passive scalar advection. In recent years, it also gained attention as a means of simulating chemical phenomena, as interest in self-organization processes increased. This paper will present a widely-used and versatile lattice Boltzmann model that can simultaneously incorporate fluid dynamics, heat transfer, buoyancy-driven convection, passive scalar advection, chemical reactions and enthalpy changes. All of these effects interact in a physically accurate framework that is simple to code and readily parallelizable. As well as a complete description of the model equations, several example systems will be presented in order to demonstrate the accuracy and versatility of the method. New simulations, which analyzed the effect of a reversible reaction on the transport properties of a convecting fluid, will also be described in detail. This extra chemical degree of freedom was utilized by the system to augment its net heat flux. The numerical method outlined in this paper can be readily deployed for a vast range of complex flow problems, spanning a variety of scientific disciplines.

  10. Long-term non-isothermal reactive transport model of compacted bentonite, concrete and corrosion products in a HLW repository in clay.

    Science.gov (United States)

    Mon, Alba; Samper, Javier; Montenegro, Luis; Naves, Acacia; Fernández, Jesús

    2017-02-01

    Radioactive waste disposal in deep geological repositories envisages engineered barriers such as carbon-steel canisters, compacted bentonite and concrete liners. The stability and performance of the bentonite barrier could be affected by the corrosion products at the canister-bentonite interface and the hyper-alkaline conditions caused by the degradation of concrete at the bentonite-concrete interface. Additionally, the host clay formation could also be affected by the hyper-alkaline plume at the concrete-clay interface. Here we present a non-isothermal multicomponent reactive transport model of the long-term (1Ma) interactions of the compacted bentonite with the corrosion products of a carbon-steel canister and the concrete liner of the engineered barrier of a high-level radioactive waste repository in clay. Model results show that magnetite is the main corrosion product. Its precipitation reduces significantly the porosity of the bentonite near the canister. The degradation of the concrete liner leads to the precipitation of secondary minerals and the reduction of the porosity of the bentonite and the clay formation at their interfaces with the concrete liner. The reduction of the porosity becomes especially relevant at t=104years. The zones affected by pore clogging at the canister-bentonite and concrete-clay interfaces at 1Ma are approximately equal to 1 and 3.3cm thick, respectively. The hyper-alkaline front (pH>8.5) spreads 2.5cm into the clay formation after 1Ma. Our simulation results share the key features of the models reported by others for engineered barrier systems at similar chemical conditions, including: 1) Pore clogging at the canister-bentonite and concrete-clay interfaces; 2) Narrow alteration zones; and 3) Limited smectite dissolution after 1Ma. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. TOUGHREACT User's Guide: A Simulation Program for Non-isothermal Multiphase Reactive Geochemical Transport in Variably Saturated Geologic Media, V1.2.1

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu; Sonnenthal, Eric; Spycher, Nicolas; Pruess, Karsten

    2008-09-29

    Coupled modeling of subsurface multiphase fluid and heat flow, solute transport, and chemical reactions can be applied to many geologic systems and environmental problems, including geothermal systems, diagenetic and weathering processes, subsurface waste disposal, acid mine drainage remediation, contaminant transport, and groundwater quality. TOUGHREACT has been developed as a comprehensive non-isothermal multi-component reactive fluid flow and geochemical transport simulator to investigate these and other problems. A number of subsurface thermo-physical-chemical processes are considered under various thermohydrological and geochemical conditions of pressure, temperature, water saturation, and ionic strength. TOUGHREACT can be applied to one-, two- or three-dimensional porous and fractured media with physical and chemical heterogeneity. The code can accommodate any number of chemical species present in liquid, gas and solid phases. A variety of equilibrium chemical reactions are considered, such as aqueous complexation, gas dissolution/exsolution, and cation exchange. Mineral dissolution/precipitation can take place subject to either local equilibrium or kinetic controls, with coupling to changes in porosity and permeability and capillary pressure in unsaturated systems. Chemical components can also be treated by linear adsorption and radioactive decay. The first version of the non-isothermal reactive geochemical transport code TOUGHREACT was developed (Xu and Pruess, 1998) by introducing reactive geochemistry into the framework of the existing multi-phase fluid and heat flow code TOUGH2 (Pruess, 1991). TOUGHREACT was further enhanced with the addition of (1) treatment of mineral-water-gas reactive-transport under boiling conditions, (2) an improved HKF activity model for aqueous species, (3) gas species diffusion coefficients calculated as a function of pressure, temperature, and molecular properties, (4) mineral reactive surface area formulations for fractured

  12. Core 2D. A code for non-isothermal water flow and reactive solute transport. Users manual version 2

    Energy Technology Data Exchange (ETDEWEB)

    Samper, J.; Juncosa, R.; Delgado, J.; Montenegro, L. [Universidad de A Coruna (Spain)

    2000-07-01

    Understanding natural groundwater quality patterns, quantifying groundwater pollution and assessing the effects of waste disposal, require modeling tools accounting for water flow, and transport of heat and dissolved species as well as their complex interactions with solid and gases phases. This report contains the users manual of CORE ''2D Version V.2.0, a COde for modeling water flow (saturated and unsaturated), heat transport and multicomponent Reactive solute transport under both local chemical equilibrium and kinetic conditions. it is an updated and improved version of CORE-LE-2D V0 (Samper et al., 1988) which in turns is an extended version of TRANQUI, a previous reactive transport code (ENRESA, 1995). All these codes were developed within the context of Research Projects funded by ENRESA and the European Commission. (Author)

  13. Characterization, non-isothermal decomposition kinetics and photocatalytic water splitting of green chemically synthesized polyoxoanions of molybdenum containing phosphorus as hetero atom

    Energy Technology Data Exchange (ETDEWEB)

    D’Cruz, Bessy [Department of Chemistry, Mar Ivanios College, Thiruvananthapuram 695015 (India); Samuel, Jadu, E-mail: jadu_samuel@yahoo.co.in [Department of Chemistry, Mar Ivanios College, Thiruvananthapuram 695015 (India); George, Leena [Catalysis and Inorganic Chemistry Division, National Chemical Laboratory, Pune 411008 (India)

    2014-11-20

    Highlights: • CPM nanorods were synthesized by applying the principles of green chemistry. • The isoconversional method was used to analyze the effective activation energy. • The appropriate reaction models of the two decomposition stages were determined. • Photocatalytic water splitting was investigated in the presence of platinum co-catalyst. - Abstract: In here, the green synthesis and thermal characterization of a novel polyoxoanions of molybdenum containing phosphorus as hetero atom are reported. The composition and morphology of the nanorods were established by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and inductively coupled plasma atomic emission spectroscopic (ICP-AES) techniques. Thermal properties of the nanoparticles were investigated by non-isothermal analysis under nitrogen atmosphere. The values activation energy of each stage of thermal decomposition for all heating rates was calculated by Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunnose (KAS) methods. Invariant kinetic parameter (IKP) method and master plot method were also used to evaluate the kinetic parameters and mechanism for the thermal decomposition of cetylpyridinium phosphomolybdate (CPM). Photocatalytic water oxidation mechanism using CPM catalyst in the presence of platinum (Pt) co-catalyst enhances the H{sub 2} evolution and was found to be 1.514 mmol/g/h.

  14. Chemical Reactivity Test (CRT)

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-13

    The Chemical Reactivity Test (CRT) is used to determine the thermal stability of High Explosives (HEs) and chemical compatibility between (HEs) and alien materials. The CRT is one of the small-scale safety tests performed on HE at the High Explosives Applications Facility (HEAF).

  15. Chemical reactivities of bleomycin.

    Science.gov (United States)

    Padbury, G; Sligar, S S

    1985-07-05

    Ferric bleomycin was tested for its ability to catalyze a set of six oxidative reactions characteristic of the heme-containing proteins, cytochrome P-450 and chloroperoxidase. These reactions included peroxyacid decarboxylation and aliphatic hydroxylation as typical cytochrome P-450 chemistries. Peroxyacid-supported oxygen evolution and hydrogen peroxide-mediated chlorination were utilized as characteristic chloroperoxidase reactivities. A typical peroxidative reaction and heteroatom dealkylation, common to both O2 activating enzymes, were also studied. Bleomycin was found to catalyze peroxidation of o-dianisidine. The ferric drug complex was found competent in carrying out N-demethylation of N,N-dimethylaniline when peroxides or peroxyacids or iodosobenzene were used as the oxidants. N-Demethylation was not achieved when N,N-dimethylaniline-N-oxide was substituted as the oxidant under similar conditions. Hydroxylation of cumene and decarboxylation of phenylperacetic acid were not found to be catalyzed by bleomycin. Oxygen evolution from m-chloroperbenzoic acid and chlorination of monochlorodimedone from chloride ion and hydrogen peroxide were found to be catalyzed by bleomycin. Cytochrome P-450cam was also evaluated for O2 evolution, and halogenation activity and was found not to demonstrate such reactivities. The results of this initial survey, along with those of previous studies, appear to indicate that the chemical reactivity of bleomycin can be more closely aligned with the reactivities demonstrated by chloroperoxidase than those of cytochrome P-450.

  16. Modelling of simultaneous mass and heat transfer with chemical reaction using the Maxwell-Stefan theory II. Non-isothermal study

    NARCIS (Netherlands)

    Frank, M.J.W.; Frank, M.J.W.; Kuipers, J.A.M.; Krishna, R.; van Swaaij, Willibrordus Petrus Maria

    1995-01-01

    In Part I a general applicable model has been developed which calculates mass and heat transfer fluxes through a vapour/gas-liquid interface in case a reversible chemical reaction with associated heat effect takes place in the liquid phase. In this model the Maxwell-Stefan theory has been used to

  17. Numerical analysis for magnetohydrodynamic chemically reacting and radiating fluid past a non-isothermal uniformly moving vertical surface adjacent to a porous regime

    Directory of Open Access Journals (Sweden)

    Sahin Ahmed

    2014-09-01

    Full Text Available A mathematical model is conducted for the unsteady magnetohydrodynamic viscous, incompressible free convective flow of an electrically conducting Newtonian fluid over an impulsively-started semi-infinite vertical plate adjacent to saturated porous medium in the presence of appreciable thermal radiation heat transfer and chemical reaction of first order taking transverse magnetic field into account. The fluid is assumed optically thin gray gas, absorbing-emitting radiation, but a non-scattering medium. The governing non-linear partial differential equations are non-dimensionalized and are solved by an implicit finite difference scheme of Crank–Nicholson type. It is found that, increasing magnetic parameter serves to decelerate the flow, but increased temperatures and concentration values. An increase in the porosity parameter (K is found to escalate the local skin friction (τx, Nusselt number (Nux and the Sherwood number (Shx. Applications of the model include fundamental magneto-fluid dynamics, MHD energy systems and magneto-metallurgical processing for aircraft materials.

  18. Homogenization in chemical reactive flows

    Directory of Open Access Journals (Sweden)

    Carlos Conca

    2004-03-01

    Full Text Available This paper concerns the homogenization of two nonlinear models for chemical reactive flows through the exterior of a domain containing periodically distributed reactive solid grains (or reactive obstacles. In the first model, the chemical reactions take place on the walls of the grains, while in the second one the fluid penetrates the grains and the reactions take place therein. The effective behavior of these reactive flows is described by a new elliptic boundary-value problem containing an extra zero-order term which captures the effect of the chemical reactions.

  19. Non-isothermal crystallization kinetics of polyethylene–clay ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Non-isothermal crystallization kinetics of pure medium density polyethylene (MDPE) and MDPE– clay nanocomposites have been investigated by differential scanning calorimeter. The modified Avrami,. Ozawa, Liu and Ziabicki equations have been applied to describe non-isothermal crystallization process. The.

  20. Synthesis, non-isothermal crystallization and magnetic properties of ...

    Indian Academy of Sciences (India)

    A non-isothermal study of the crystallization kinetic of ferrite/PEVA nanocomposite was carried out by differential scanning calorimetry (DSC), scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques. It was observed that the Ozawa equation describes perfectly the primary process of non-isothermal ...

  1. Quantum Entanglement and Chemical Reactivity.

    Science.gov (United States)

    Molina-Espíritu, M; Esquivel, R O; López-Rosa, S; Dehesa, J S

    2015-11-10

    The water molecule and a hydrogenic abstraction reaction are used to explore in detail some quantum entanglement features of chemical interest. We illustrate that the energetic and quantum-information approaches are necessary for a full understanding of both the geometry of the quantum probability density of molecular systems and the evolution of a chemical reaction. The energy and entanglement hypersurfaces and contour maps of these two models show different phenomena. The energy ones reveal the well-known stable geometry of the models, whereas the entanglement ones grasp the chemical capability to transform from one state system to a new one. In the water molecule the chemical reactivity is witnessed through quantum entanglement as a local minimum indicating the bond cleavage in the dissociation process of the molecule. Finally, quantum entanglement is also useful as a chemical reactivity descriptor by detecting the transition state along the intrinsic reaction path in the hypersurface of the hydrogenic abstraction reaction corresponding to a maximally entangled state.

  2. Non-isothermal crystallization kinetics of polyethylene–clay ...

    Indian Academy of Sciences (India)

    MDPE) and MDPE–clay nanocomposites have been investigated by differential scanning calorimeter. The modified Avrami, Ozawa, Liu and Ziabicki equations have been applied to describe non-isothermal crystallization process. The results of ...

  3. Pyrolysis kinetics of coking coal mixed with biomass under non-isothermal and isothermal conditions.

    Science.gov (United States)

    Jeong, Ha Myung; Seo, Myung Won; Jeong, Sang Mun; Na, Byung Ki; Yoon, Sang Jun; Lee, Jae Goo; Lee, Woon Jae

    2014-03-01

    To investigate the kinetic characteristics of coking coal mixed with biomass during pyrolysis, thermogravimetric (TG) and thermo-balance reactor (TBR) analyses were conducted under non-isothermal and isothermal condition. Yellow poplar as a biomass (B) was mixed with weak coking coal (WC) and hard coking coal (HC), respectively. The calculated activation energies of WC/B blends were higher than those of HC/B blends under non-isothermal and isothermal conditions. The coal/biomass blends show increased reactivity and decreased activation energy with increasing biomass blend ratio, regardless of the coking properties of the coal. The different char structures of the WC/B and HC/B blends were analyzed by BET and SEM. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Nonequilibrium steady state of biochemical cycle kinetics under non-isothermal conditions

    CERN Document Server

    Jin, Xiao

    2016-01-01

    Nonequilibrium steady state of isothermal biochemical cycle kinetics has been extensively studied, but much less investigated under non-isothermal conditions. However, once the heat exchange between subsystems is rather slow, the isothermal assumption of the whole system meets great challenge, which is indeed the case inside many kinds of living organisms. Here we generalize the nonequilibrium steady-state theory of isothermal biochemical cycle kinetics, in the master-equation models, to the situation in which the temperatures of subsystems can be far from uniform. We first obtain a new thermodynamic relation between the chemical reaction rates and thermodynamic potentials under such a non-isothermal circumstances, which immediately implies simply applying the isothermal transition-state rate formula for each chemical reaction in terms of only the reactants' temperature, is not thermodynamically consistent. Therefore, we mathematically derive several revised reaction-rate formulas which not only obey the new ...

  5. Non-isothermal Moisture Transport Through Insulation Materials

    DEFF Research Database (Denmark)

    Peuhkuri, Ruut Hannele; Rode, Carsten; Hansen, Kurt Kielsgaard

    2008-01-01

    conclusions and therefore the question about existence of the type of transport forms driven by the non-isothermal effects remains open. Rather surprisingly, all the materials, including the almost non-hygroscopic materials (e.g. rock wool) and very hygroscopic materials (e.g. cellulose insulation) showed...

  6. Non-isothermal crystallization kinetics and thermal behaviour of ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The thermal behaviour and crystallization kinetics of PA12/SEBS-g-MA blends were investigated under non-isothermal and isothermal conditions using thermogravimetric analysis and differential scanning calorimetry, respectively. The macrokinetic model given by Avrami was used to analyse both the non-.

  7. LES of droplet-laden non-isothermal channel flow

    NARCIS (Netherlands)

    Michalek, W.R.; Liew, R.; Kuerten, Johannes G.M.; Zeegers, J.C.H.

    In this paper subgrid models for LES of droplet-laden non-isothermal channel flow are tested and improved for three Reynolds numbers based on friction velocity, Reτ of 150, 395, and 950 with the aim to develop a simulation method for LES of a droplet-laden Ranque-Hilsch vortex tube. A new subgrid

  8. Solvent effects and chemical reactivity

    National Research Council Canada - National Science Library

    Tapia, Orlando; Bertrán, J

    1996-01-01

    ... original contributions from a selected group of distinguished researchers that are actively working in the theory and practical applications of solvent effects and chemical reactions. The importance...

  9. LES of droplet-laden non-isothermal channel flow

    Science.gov (United States)

    Michałek, W. R.; Liew, R.; Kuerten, J. G. M.; Zeegers, J. C. H.

    2011-12-01

    In this paper subgrid models for LES of droplet-laden non-isothermal channel flow are tested and improved for three Reynolds numbers based on friction velocity, Reτ of 150, 395, and 950 with the aim to develop a simulation method for LES of a droplet-laden Ranque-Hilsch vortex tube. A new subgrid model combining the beneficial properties of the dynamic eddy-viscosity model and the approximate deconvolution model is proposed. Furthermore, the subgrid model in the droplet equations based on approximate deconvolution is found to perform well also in non-isothermal channel flow. At the highest Reynolds number in the test the dynamic model yields results with a similar accuracy as the approximate deconvolution model.

  10. LES of droplet-laden non-isothermal channel flow

    Energy Technology Data Exchange (ETDEWEB)

    Michalek, W R; Kuerten, J G M [Department of Mechanical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Liew, R; Zeegers, J C H, E-mail: w.michalek@tue.nl [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2011-12-22

    In this paper subgrid models for LES of droplet-laden non-isothermal channel flow are tested and improved for three Reynolds numbers based on friction velocity, Re{sub {tau}} of 150, 395, and 950 with the aim to develop a simulation method for LES of a droplet-laden Ranque-Hilsch vortex tube. A new subgrid model combining the beneficial properties of the dynamic eddy-viscosity model and the approximate deconvolution model is proposed. Furthermore, the subgrid model in the droplet equations based on approximate deconvolution is found to perform well also in non-isothermal channel flow. At the highest Reynolds number in the test the dynamic model yields results with a similar accuracy as the approximate deconvolution model.

  11. Hydrophobic interactions and chemical reactivity

    NARCIS (Netherlands)

    Otto, Sijbren; Engberts, Jan B.F.N.

    2003-01-01

    This perspective describes how kinetic studies of organic reactions can be used to increase our understanding of hydrophobic interactions. In turn, our understanding of hydrophobic interactions can be used as a tool to influence chemical reactions.

  12. Steam-chemical reactivity for irradiated beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, R.A.; McCarthy, K.A.; Oates, M.A.; Petti, D.A.; Pawelko, R.J.; Smolik, G.R. [Idaho National Engineering and Environmental Lab., Idaho Falls, ID (United States)

    1998-01-01

    This paper reports the results of an experimental investigation to determine the influence of neutron irradiation effects and annealing on the chemical reactivity of beryllium exposed to steam. The work entailed measurements of the H{sub 2} generation rates for unirradiated and irradiated Be and for irradiated Be that had been previously annealed at different temperatures ranging from 450degC to 1200degC. H{sub 2} generation rates were similar for irradiated and unirradiated Be in steam-chemical reactivity experiments at temperatures between 450degC and 600degC. For irradiated Be exposed to steam at 700degC, the chemical reactivity accelerated rapidly and the specimen experienced a temperature excursion. Enhanced chemical reactivity at temperatures between 400degC and 600degC was observed for irradiated Be annealed at temperatures of 700degC and higher. This reactivity enhancement could be accounted for by the increased specific surface area resulting from development of a surface-connected porosity in the irradiated-annealed Be. (author)

  13. Haptenation: Chemical Reactivity and Protein Binding

    Directory of Open Access Journals (Sweden)

    Itai Chipinda

    2011-01-01

    Full Text Available Low molecular weight chemical (LMW allergens are commonly referred to as haptens. Haptens must complex with proteins to be recognized by the immune system. The majority of occupationally related haptens are reactive, electrophilic chemicals, or are metabolized to reactive metabolites that form covalent bonds with nucleophilic centers on proteins. Nonelectrophilic protein binding may occur through disulfide exchange, coordinate covalent binding onto metal ions on metalloproteins or of metal allergens, themselves, to the major histocompatibility complex. Recent chemical reactivity kinetic studies suggest that the rate of protein binding is a major determinant of allergenic potency; however, electrophilic strength does not seem to predict the ability of a hapten to skew the response between Th1 and Th2. Modern proteomic mass spectrometry methods that allow detailed delineation of potential differences in protein binding sites may be valuable in predicting if a chemical will stimulate an immediate or delayed hypersensitivity. Chemical aspects related to both reactivity and protein-specific binding are discussed.

  14. Study on non-isothermal kinetics for modified coal tar pitch

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.; Shui, H.; Feng, Y. [East China Institute of Metallurgy, Maanshan (China). Dept of Chemical Engineering

    2001-04-01

    The non-isothermal kinetics for the mesophase transformation of Baogang-I coal tar pitch (I-CTP), soft pitch consisted of I-CTP and 18% phenanthrene residue oil (PRO) or I-CTP and 30% PRO have been studied in a thermal conversion unit. Kinetic parameters were calculated by using and integral method. Results showed that the process of mesophase pitch transformation could be described in first order reaction. The activation energy of I-CTP is 175.36 kJ/mol. But adding 30% PRO, which improved the reactivity of I-CTP with activation energy 138.07 kJ/mol, is not beneficial to the mesophase transformation. 7 refs., 2 figs., 6 tabs.

  15. Precision retrieval of non-isothermal exo-atmospheres

    Science.gov (United States)

    Waldmann, Ingo Peter; Rocchetto, Marco

    2015-12-01

    Spectroscopy of extrasolar planets is as fast moving as it is new. When trying to characterise the atmospheres of these foreign worlds, we are faced with three challenges: 1) The correct treatment of atmospheric opacities at high temperatures, 2) Low signal-to-noise of the observed data, and 3) Large, degenerate parameter spaces. To advance in the interpretation of exoplanetary atmospheres, one must address these challenges in one coherent framework. This is particularly true for emission spectroscopy, where the need for non-isothermal temperature-pressure profiles significantly increases degeneracies in low signal-to-noise data. In the light of these challenges, we developed a novel, bayesian atmospheric retrieval suite, Tau-REx (Waldmann et al. 2015a,b). Tau-REx is a full line-by-line emission/transmission spectroscopy retrieval code based on the most complete hot line-lists from the ExoMol project. For emission spectroscopy, the correct retrieval of the atmosphere’s thermal gradient is extremely challenging with sparse and/or low SNR data. Tau-REx implements a novel two-stage retrieval algorithm which allows the code to iteratively adapt its retrieval complexity to the likelihood surface of the observed data. This way we achieve a very high retrieval accuracy and robustness to low SNR data. Using nested-sampling in conjunction with large scale cluster computing, Tau-REx integrates the full Bayesian Evidence, which allows for precise model selection of the exoplanet’s chemistry and thermal dynamics. Precision and statistical rigour is paramount in the measurement of quantities such as the carbon-oxygen ratio of planets which allow insights into the formation history of these exotic worlds. In this conference I will discuss the intricacies of retrieving the thermal emission of non-isothermal atmospheres and what can be learned from data of current and future facilities.

  16. Modeling of Non-isothermal Austenite Formation in Spring Steel

    Science.gov (United States)

    Huang, He; Wang, Baoyu; Tang, Xuefeng; Li, Junling

    2017-12-01

    The austenitization kinetics description of spring steel 60Si2CrA plays an important role in providing guidelines for industrial production. The dilatometric curves of 60Si2CrA steel were measured using a dilatometer DIL805A at heating rates of 0.3 K to 50 K/s (0.3 °C/s to 50 °C/s). Based on the dilatometric curves, a unified kinetics model using the internal state variable (ISV) method was derived to describe the non-isothermal austenitization kinetics of 60Si2CrA, and the abovementioned model models the incubation and transition periods. The material constants in the model were determined using a genetic algorithm-based optimization technique. Additionally, good agreement between predicted and experimental volume fractions of transformed austenite was obtained, indicating that the model is effective for describing the austenitization kinetics of 60Si2CrA steel. Compared with other modeling methods of austenitization kinetics, this model, which uses the ISV method, has some advantages, such as a simple formula and explicit physics meaning, and can be probably used in engineering practice.

  17. A numerical study of non-isothermal turbulent coaxial jets

    Energy Technology Data Exchange (ETDEWEB)

    Kriaa, Wassim; Abderrazak, Kamel; Mhiri, Hatem [Ecole Nationale d' Ingenieurs de Monastir, Laboratoire de Mecanique des Fluides et Thermique, Monastir (Tunisia); Palec, Georges le; Bournot, Philippe [Institut de Mecanique de Marseille, Marseille (France)

    2008-07-15

    In this work, we propose to study non isothermal air-air coaxial jets with two different approaches: parabolic and elliptic approaches. The standard k-{epsilon} model and the RSM model were applied in this study. The numerical resolution of the equations governing this flow type was carried out for: the parabolic approach, by a ''home-made'' CFD code based on a finite difference method, and the elliptic approach by an industrial code (FLUENT) based on a finite volume method. In forced convection mode (Fr={infinity}), the two turbulence models are valid for the prediction of the mean flow. But for turbulent sizes, k-{epsilon} model gives results closer to those achieved in experiments compared to RSM Model. Concerning the limit of validity of the parabolic and elliptic approaches, we showed that for velocities ratio r lower than 1, the results of the two approaches were satisfactory. On the other hand, for r>1, the difference between the results became increasingly significant. In mixed convection mode (Fr{approx_equal}20), the results obtained by the two turbulence models for the mean axial velocity were very different even in the plume region. For the temperature and the turbulent sizes the two models give satisfactory results which agree well with the correlations suggested by the experimenters for X{>=}20. Thus, the second order model with {sigma}{sub t}=0.85 is more effective for a coaxial jet study in a mixed convection mode. (orig.)

  18. Layer of protection analysis for reactive chemical risk assessment.

    Science.gov (United States)

    Wei, Chunyang; Rogers, William J; Mannan, M Sam

    2008-11-15

    Reactive chemical hazards have been a significant concern for the chemical process industries (CPI). Without sufficient control and mitigation of chemical reaction hazards, reactive incidents have led to severe consequences, such as release of flammable and toxic materials, fires and explosions, and threats to human lives, properties, and the environment. Consequence of reactive hazards can be well understood through calorimetric testing and computational techniques. However, risks of incidents caused by reactive chemicals have not been well addressed due partly to sparse failure frequency data. In this paper, the semi-quantitative layer of protection analysis (LOPA) approach is used to estimate reactive chemical risk, and the probabilities or frequencies of failure scenarios are addressed. Using LOPA, reactive risks can be evaluated with respect to predefined criteria, and the effectiveness of risk reduction measures can be assessed. The hydroxylamine (HA) production system is employed as a case study to demonstrate the application of LOPA to reactive chemical risk assessment.

  19. Thermodynamic Model Formulations for Inhomogeneous Solids with Application to Non-isothermal Phase Field Modelling

    Science.gov (United States)

    Gladkov, Svyatoslav; Kochmann, Julian; Reese, Stefanie; Hütter, Markus; Svendsen, Bob

    2016-04-01

    The purpose of the current work is the comparison of thermodynamic model formulations for chemically and structurally inhomogeneous solids at finite deformation based on "standard" non-equilibrium thermodynamics [SNET: e. g. S. de Groot and P. Mazur, Non-equilibrium Thermodynamics, North Holland, 1962] and the general equation for non-equilibrium reversible-irreversible coupling (GENERIC) [H. C. Öttinger, Beyond Equilibrium Thermodynamics, Wiley Interscience, 2005]. In the process, non-isothermal generalizations of standard isothermal conservative [e. g. J. W. Cahn and J. E. Hilliard, Free energy of a non-uniform system. I. Interfacial energy. J. Chem. Phys. 28 (1958), 258-267] and non-conservative [e. g. S. M. Allen and J. W. Cahn, A macroscopic theory for antiphase boundary motion and its application to antiphase domain coarsening. Acta Metall. 27 (1979), 1085-1095; A. G. Khachaturyan, Theory of Structural Transformations in Solids, Wiley, New York, 1983] diffuse interface or "phase-field" models [e. g. P. C. Hohenberg and B. I. Halperin, Theory of dynamic critical phenomena, Rev. Modern Phys. 49 (1977), 435-479; N. Provatas and K. Elder, Phase Field Methods in Material Science and Engineering, Wiley-VCH, 2010.] for solids are obtained. The current treatment is consistent with, and includes, previous works [e. g. O. Penrose and P. C. Fife, Thermodynamically consistent models of phase-field type for the kinetics of phase transitions, Phys. D 43 (1990), 44-62; O. Penrose and P. C. Fife, On the relation between the standard phase-field model and a "thermodynamically consistent" phase-field model. Phys. D 69 (1993), 107-113] on non-isothermal systems as a special case. In the context of no-flux boundary conditions, the SNET- and GENERIC-based approaches are shown to be completely consistent with each other and result in equivalent temperature evolution relations.

  20. An autonomous organic reaction search engine for chemical reactivity

    Science.gov (United States)

    Dragone, Vincenza; Sans, Victor; Henson, Alon B.; Granda, Jaroslaw M.; Cronin, Leroy

    2017-06-01

    The exploration of chemical space for new reactivity, reactions and molecules is limited by the need for separate work-up-separation steps searching for molecules rather than reactivity. Herein we present a system that can autonomously evaluate chemical reactivity within a network of 64 possible reaction combinations and aims for new reactivity, rather than a predefined set of targets. The robotic system combines chemical handling, in-line spectroscopy and real-time feedback and analysis with an algorithm that is able to distinguish and select the most reactive pathways, generating a reaction selection index (RSI) without need for separate work-up or purification steps. This allows the automatic navigation of a chemical network, leading to previously unreported molecules while needing only to do a fraction of the total possible reactions without any prior knowledge of the chemistry. We show the RSI correlates with reactivity and is able to search chemical space using the most reactive pathways.

  1. Chemical Reactivity as Described by Quantum Chemical Methods

    Directory of Open Access Journals (Sweden)

    F. De Proft

    2002-04-01

    Full Text Available Abstract: Density Functional Theory is situated within the evolution of Quantum Chemistry as a facilitator of computations and a provider of new, chemical insights. The importance of the latter branch of DFT, conceptual DFT is highlighted following Parr's dictum "to calculate a molecule is not to understand it". An overview is given of the most important reactivity descriptors and the principles they are couched in. Examples are given on the evolution of the structure-property-wave function triangle which can be considered as the central paradigm of molecular quantum chemistry to (for many purposes a structure-property-density triangle. Both kinetic as well as thermodynamic aspects can be included when further linking reactivity to the property vertex. In the field of organic chemistry, the ab initio calculation of functional group properties and their use in studies on acidity and basicity is discussed together with the use of DFT descriptors to study the kinetics of SN2 reactions and the regioselectivity in Diels Alder reactions. Similarity in reactivity is illustrated via a study on peptide isosteres. In the field of inorganic chemistry non empirical studies of adsorption of small molecules in zeolite cages are discussed providing Henry constants and separation constants, the latter in remarkable good agreement with experiments. Possible refinements in a conceptual DFT context are presented. Finally an example from biochemistry is discussed : the influence of point mutations on the catalytic activity of subtilisin.

  2. Evaluating the Energy Recovery Potential of Nigerian Coals under Non-Isothermal Thermogravimetry

    Science.gov (United States)

    Bevan Nyakuma, Bemgba; Oladokun, Olagoke; Jauro, Aliyu; Damian Nyakuma, Denen

    2017-07-01

    This study investigated the fuel properties and energy recovery potential of two coal samples from Ihioma (IHM) and Ogboligbo (OGB) environs in Nigeria. The ultimate, proximate, and bomb calorimetric analyses of the coal were examined. Next, the rank classification and potential application of the coals were evaluated according to the ASTM standard D388. Lastly, thermal decomposition behaviour was examined by non-isothermal thermogravimetry (TG) under pyrolysis conditions from 30 - 900 °C. The results indicated IHM and OGB contain high proportions of combustible elements for potential thermal conversion. The higher heating value (HHV) of IHM was 20.37 MJ/kg whereas OGB was 16.33 MJ/kg. TG analysis revealed 55% weight loss for OGB and 76% for IHM. The residual mass was 23% for IHM and 44% for OGB. Based on the temperature profile characteristics (TPCs); Ton , Tmax , and Toff , IHM was more reactive than OGB due to its higher volatile matter (VM). Overall, results revealed the coals are Lignite (Brown) low-rank coals (LRCs) with potential for electric power generation.

  3. Modeling and analysis for general non-isothermal convective phase field systems

    OpenAIRE

    Haas, Robert

    2007-01-01

    In this work general non-isothermal phase field models for multi-phase and multi-component systems are considered. The modelling of the free energy by Ginzburg-Landau functionals for multi-phase systems is considered and analyzed theoretically and numerically. Furthermore a general non-isothermal phase field model for convective systems with multiple components and phases has been derived. Finally for a isothermal multi-phase phase field model the existence of a solution is proved in...

  4. Isothermal and non-isothermal torrefaction characteristics and kinetics of microalga Scenedesmus obliquus CNW-N.

    Science.gov (United States)

    Chen, Wei-Hsin; Wu, Zih-Ying; Chang, Jo-Shu

    2014-03-01

    Isothermal and non-isothermal torrefaction characteristics and kinetics of microalga Scenedesmus obliquus (S. obliquus) CNW-N are studied using thermogravimetric analysis. The pyrolysis of S. obliquus CNW-N with increasing temperature is characterized by four-stage decomposition. Depending on the torrefaction temperature, light, mild, and severe torrefaction from the weight loss and the maximum decomposition rate of the microalga can be classified. Under the same average temperature and torrefaction duration, non-isothermal torrefaction gives more severe pretreatment than the isothermal one. Increasing the heating rate of non-isothermal torrefaction also intensifies the pretreatment severity. Therefore, microalgae can be torrefied via non-isothermal torrefaction in a shorter time under the same pretreatment extent. The atomic H/C ratio in the microalga decreases with increasing torrefaction severity, whereas the atomic O/C ratio rises. The analysis suggests that the activation energy of isothermal torrefaction is 57.52×10(3)Jmol(-1), while it is between 40.14×10(3) and 88.41×10(3)Jmol(-1) for non-isothermal torrefaction. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Efficient and Safe Chemical Gas Generators with Nanocomposite Reactive Materials

    Science.gov (United States)

    2015-11-30

    2015 Approved for Public Release; Distribution Unlimited Final Report: Efficient and Safe Chemical Gas Generators with Nanocomposite Reactive Materials...Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 Energetic materials, gas generators, nanoenergetics REPORT DOCUMENTATION PAGE 11...Building, Room 209 El Paso, TX 79968 -0587 12-Sep-2015 ABSTRACT Final Report: Efficient and Safe Chemical Gas Generators with Nanocomposite Reactive

  6. Chemical reactor modeling multiphase reactive flows

    CERN Document Server

    Jakobsen, Hugo A

    2014-01-01

    Chemical Reactor Modeling closes the gap between Chemical Reaction Engineering and Fluid Mechanics.  The second edition consists of two volumes: Volume 1: Fundamentals. Volume 2: Chemical Engineering Applications In volume 1 most of the fundamental theory is presented. A few numerical model simulation application examples are given to elucidate the link between theory and applications. In volume 2 the chemical reactor equipment to be modeled are described. Several engineering models are introduced and discussed. A survey of the frequently used numerical methods, algorithms and schemes is provided. A few practical engineering applications of the modeling tools are presented and discussed. The working principles of several experimental techniques employed in order to get data for model validation are outlined. The monograph is based on lectures regularly taught in the fourth and fifth years graduate courses in transport phenomena and chemical reactor modeling, and in a post graduate course in modern reactor m...

  7. Ultraviolet Spectrum And Chemical Reactivity Of CIO Dimer

    Science.gov (United States)

    Demore, William B.; Tschuikow-Roux, E.

    1992-01-01

    Report describes experimental study of ultraviolet spectrum and chemical reactivity of dimer of chlorine monoxide (CIO). Objectives are to measure absorption cross sections of dimer at near-ultraviolet wavelengths; determine whether asymmetrical isomer (CIOCIO) exists at temperatures relevant to Antarctic stratosphere; and test for certain chemical reactions of dimer. Important in photochemistry of Antarctic stratosphere.

  8. Spectroscopic and chemical reactivity analysis of D-Myo-Inositol ...

    Indian Academy of Sciences (India)

    2017-06-20

    Jun 20, 2017 ... Home; Journals; Pramana – Journal of Physics; Volume 89; Issue 1. Spectroscopic and chemical reactivity analysis of D-Myo-Inositol using quantum chemical approach and its experimental verification. DEVENDRA P MISHRA ANCHAL SRIVASTAVA R K SHUKLA. Special Issue Volume 89 Issue 1 July ...

  9. Kinetics of magnetite oxidation under non-isothermal conditions

    Science.gov (United States)

    Sardari, Aref; Alamdari, Eskandar Keshavarz; Noaparast, Mohammad; Shafaei, Sied Ziaedin

    2017-05-01

    Oxidation of magnetite concentrates, which occurs during the pellet induration process, must be deeply understood to enable the appropriate design of induration machines. In the present paper, the kinetics of the magnetite oxidation reaction was studied. Primary samples were obtained from the Gol-e-Gohar iron ore deposit. Magnetic separation and flotation decreased the sulfur content in the samples to be approximately 0.1wt%. Thermogravimetric analysis was used to measure mass changes during the oxidation of magnetite and, consequently, the conversion values. The aim of this study was to use isoconversional methods to calculate the kinetic parameters. The Coats-Redfern method was also used to obtain the activation energy. Thermogravimetric analyses were run at three different heating rates. The Coats-Redfern results were too ambiguous for a meaningful interpretation. In the case of the isoconversional method, however, the mean activation energy and pre-exponential factor of the oxidation reaction were obtained as 67.55 kJ and 15.32 × 108 min-1, respectively. Such a large activation energy implies that temperature strongly affects the reaction rate. The oxidation reaction exhibits a true multi-step nature that is predominantly controlled by chemical reaction and diffusion mechanisms.

  10. Reactive chemical dynamics through conical intersections

    Indian Academy of Sciences (India)

    WINTEC

    fore paid by various research groups to devise accu- rate quantum mechanical model in order to simulate chemical .... interaction between the reagent atom and diatom. This WP is propagated in the coupled manifold of ... function for the approach of the atom to the diatom and the rovibrational wavefunction of the diatomic.

  11. Non-isothermal effects on multi-phase flow in porous medium

    DEFF Research Database (Denmark)

    Singh, Ashok; Wang, W; Park, C. H.

    2010-01-01

    In this paper a ppT -formulation for non-isothermal multi-phase flow is given including diffusion and latent heat effects. Temperature and pressure dependencies of governing parameters are considered, in particular surface tension variation on phase interfaces along with temperature changes. A weak...

  12. A simple method of evaluating non-isothermal crystallization kinetics in multicomponent polymer systems

    Czech Academy of Sciences Publication Activity Database

    Kratochvíl, Jaroslav; Kelnar, Ivan

    2015-01-01

    Roč. 47, October (2015), s. 79-86 ISSN 0142-9418 R&D Projects: GA ČR(CZ) GA13-15255S Institutional support: RVO:61389013 Keywords : non-isothermal crystallization kinetics * cumulative curves * inflection point Subject RIV: JI - Composite Materials Impact factor: 2.350, year: 2015

  13. Non-isothermal diffusion in a binary mixture with smoothed particle hydrodynamics

    NARCIS (Netherlands)

    Thieulot, C; Espanol, P

    2005-01-01

    We explore the possibility of controlling the pattern formation in a purely diffusive binary mixture described by a van der Waals equation of state in non-isothermal situations. Simulations are conducted with a previously formulated thermodynamically consistent smoothed particle hydrodynamics model

  14. Non-isothermal kinetics model to predict accurate phase transformation and hardness of 22MnB5 boron steel

    Energy Technology Data Exchange (ETDEWEB)

    Bok, H.-H.; Kim, S.N.; Suh, D.W. [Graduate Institute of Ferrous Technology, POSTECH, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongsangbuk-do (Korea, Republic of); Barlat, F., E-mail: f.barlat@postech.ac.kr [Graduate Institute of Ferrous Technology, POSTECH, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongsangbuk-do (Korea, Republic of); Lee, M.-G., E-mail: myounglee@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Anam-dong, Seongbuk-gu, Seoul (Korea, Republic of)

    2015-02-25

    A non-isothermal phase transformation kinetics model obtained by modifying the well-known JMAK approach is proposed for application to a low carbon boron steel (22MnB5) sheet. In the modified kinetics model, the parameters are functions of both temperature and cooling rate, and can be identified by a numerical optimization method. Moreover, in this approach the transformation start and finish temperatures are variable instead of the constants that depend on chemical composition. These variable reference temperatures are determined from the measured CCT diagram using dilatation experiments. The kinetics model developed in this work captures the complex transformation behavior of the boron steel sheet sample accurately. In particular, the predicted hardness and phase fractions in the specimens subjected to a wide range of cooling rates were validated by experiments.

  15. Modeling food matrix effects on chemical reactivity: Challenges and perspectives.

    Science.gov (United States)

    Capuano, Edoardo; Oliviero, Teresa; van Boekel, Martinus A J S

    2017-06-29

    The same chemical reaction may be different in terms of its position of the equilibrium (i.e., thermodynamics) and its kinetics when studied in different foods. The diversity in the chemical composition of food and in its structural organization at macro-, meso-, and microscopic levels, that is, the food matrix, is responsible for this difference. In this viewpoint paper, the multiple, and interconnected ways the food matrix can affect chemical reactivity are summarized. Moreover, mechanistic and empirical approaches to explain and predict the effect of food matrix on chemical reactivity are described. Mechanistic models aim to quantify the effect of food matrix based on a detailed understanding of the chemical and physical phenomena occurring in food. Their applicability is limited at the moment to very simple food systems. Empirical modeling based on machine learning combined with data-mining techniques may represent an alternative, useful option to predict the effect of the food matrix on chemical reactivity and to identify chemical and physical properties to be further tested. In such a way the mechanistic understanding of the effect of the food matrix on chemical reactions can be improved.

  16. Managing the challenge of chemically reactive metabolites in drug development

    NARCIS (Netherlands)

    Park, B. Kevin; Boobis, Alan; Clarke, Stephen; Goldring, Chris E P; Jones, David T; Kenna, J. Gerry; Lambert, Craig; Laverty, Hugh G.; Naisbitt, Dean J.; Nelson, Sidney; Nicoll-Griffith, Deborah A.; Obach, R. Scott; Routledge, Philip; Smith, Dennis A.; Tweedie, Donald J.; Vermeulen, Nico; Williams, Dominic P.; Wilson, Ian D.; Baillie, Thomas A.

    The normal metabolism of drugs can generate metabolites that have intrinsic chemical reactivity towards cellular molecules, and therefore have the potential to alter biological function and initiate serious adverse drug reactions. Here, we present an assessment of the current approaches used for the

  17. Application of Non-Isothermal Thermogravimetric Method to Interpret the Decomposition Kinetics of , and

    Science.gov (United States)

    Pouretedal, H. R.; Ebadpour, R.

    2014-05-01

    The non-isothermal thermogravimetric method was used to study the thermal decomposition of , and at heating rates of (5, 10, 15, and 20) . The activation energy of thermal decomposition reactions was computed by isoconversional methods of Ozawa-Flynn-Wall, Kissinger-Akahiro-Sunose, and Friedman equations. Also, the kinetic triplet of the thermal decomposition of salts was determined by the model-fitting method of the modified Coats-Redfern equation. The activation energies of , and of (293 to 307, 160 to 209, and 192 to 245) , respectively, are obtained by non-isothermal isoconversional methods. The modified Coats and Redfern method showed that the most probable mechanism functions of (model A3: Arami-Erofeev equation) and (model F2: second order) can be used to predict the decomposition mechanisms of , , and , respectively.

  18. Mathematical quantification of the induced stress resistance of microbial populations during non-isothermal stresses.

    Science.gov (United States)

    Garre, Alberto; Huertas, Juan Pablo; González-Tejedor, Gerardo A; Fernández, Pablo S; Egea, Jose A; Palop, Alfredo; Esnoz, Arturo

    2018-02-02

    This contribution presents a mathematical model to describe non-isothermal microbial inactivation processes taking into account the acclimation of the microbial cell to thermal stress. The model extends the log-linear inactivation model including a variable and model parameters quantifying the induced thermal resistance. The model has been tested on cells of Escherichia coli against two families of non-isothermal profiles with different constant heating rates. One of the families was composed of monophasic profiles, consisting of a non-isothermal heating stage from 35 to 70°C; the other family was composed of biphasic profiles, consisting of a non-isothermal heating stage followed by a holding period at constant temperature of 57.5°C. Lower heating rates resulted in a higher thermal resistance of the bacterial population. This was reflected in a higher D-value. The parameter estimation was performed in two steps. Firstly, the D and z-values were estimated from the isothermal experiments. Next, the parameters describing the acclimation were estimated using one of the biphasic profiles. This set of parameters was able to describe the remaining experimental data. Finally, a methodology for the construction of diagrams illustrating the magnitude of the induced thermal resistance is presented. The methodology has been illustrated by building it for a biphasic temperature profile with a linear heating phase and a holding phase. This diagram provides a visualization of how the shape of the temperature profile (heating rate and holding temperature) affects the acclimation of the cell to the thermal stress. This diagram can be used for the design of inactivation treatments by industry taking into account the acclimation of the cell to the thermal stress. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Method to Predict Tempering of Steels Under Non-isothermal Conditions

    Science.gov (United States)

    Poirier, D. R.; Kohli, A.

    2017-05-01

    A common way of representing the tempering responses of steels is with a "tempering parameter" that includes the effect of temperature and time on hardness after hardening. Such functions, usually in graphical form, are available for many steels and have been applied for isothermal tempering. In this article, we demonstrate that the method can be extended to non-isothermal conditions. Controlled heating experiments were done on three grades in order to verify the method.

  20. Influence of rare earth oxides on the non-isothermal crystallization of phosphosilicate melts during cooling

    DEFF Research Database (Denmark)

    Liu, S.J.; Shan, Z.T.; Fu, G.Z.

    2014-01-01

    We report a detailed calorimetric study concerning the influence of Yb2O3 and Er2O3 on the non-isothermal crystallization in phosphosilicate melts. The results show that Yb3+/Er3+ ions promote the Zn2SiO4 crystal formation, but suppress the Na3PO4 and AlPO4 formation during cooling. The non-isoth...

  1. Modeling of the non-isothermal crystallization kinetics of polyamide 6 composites during thermoforming

    Science.gov (United States)

    Kugele, Daniel; Dörr, Dominik; Wittemann, Florian; Hangs, Benjamin; Rausch, Julius; Kärger, Luise; Henning, Frank

    2017-10-01

    The combination of thermoforming processes of continuous-fiber reinforced thermoplastics and injection molding offers a high potential for cost-effective use in automobile mass production. During manufacturing, the thermoplastic laminates are initially heated up to a temperature above the melting point. This is followed by continuous cooling of the material during the forming process, which leads to crystallization under non-isothermal conditions. To account for phase change effects in thermoforming simulation, an accurate modeling of the crystallization kinetics is required. In this context, it is important to consider the wide range of cooling rates, which are observed during processing. Consequently, this paper deals with the experimental investigation of the crystallization at cooling rates varying from 0.16 K/s to 100 K/s using standard differential scanning calorimetry (DSC) and fast scanning calorimetry (Flash DSC). Two different modeling approaches (Nakamura model, modified Nakamura-Ziabicki model) for predicting crystallization kinetics are parameterized according to DSC measurements. It turns out that only the modified Nakamura-Ziabicki model is capable of predicting crystallization kinetics for all investigated cooling rates. Finally, the modified Nakamura-Ziabicki model is validated by cooling experiments using PA6-CF laminates with embedded temperature sensors. It is shown that the modified Nakamura-Ziabicki model predicts crystallization at non-isothermal conditions and varying cooling rates with a good accuracy. Thus, the study contributes to a deeper understanding of the non-isothermal crystallization and presents an overall method for modeling crystallization under process conditions.

  2. Physical Characterization and Steam Chemical Reactivity of Carbon Fiber Composites

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, Robert Andrew; Pawelko, Robert James; Smolik, Galen Richard

    2001-05-01

    This report documents experiments and analyses that have been done at the Idaho National Engineering and Environmental Laboratory (INEEL) to measure the steam chemical reactivity of two types of carbon fiber composites, NS31 and NB31, proposed for use at the divertor strike points in an ITER-like tokamak. These materials are 3D CFCs constituted by a NOVOLTEX preform and densified by pyrocarbon infiltration and heat treatment. NS31 differs from NB31 in that the final infiltration was done with liquid silicon to reduce the porosity and enhance the thermal conductivity of the CFC. Our approach in this work was twofold: (1) physical characterization measurements of the specimens and (2) measurements of the chemical reactivity of specimens exposed to steam.

  3. Geometry, chemical reactivity and Raman spectra of gold clusters

    Directory of Open Access Journals (Sweden)

    Ngangbam Bedamani Singh

    2015-12-01

    Full Text Available Structures, stability, and chemical reactivity of Aun (n = 2-10 clusters are investigated using density functional theory (DFT. We have studied the reactivity parameters of the clusters in terms of relevant electronic structure principles. It is observed that stability and properties are strongly dependent on the cluster size. Clusters with an even number of atoms are found to be energetically and chemically more stable than odd-numbered clusters. Electronic structure of clusters has been investigated using partial density of states (PDOS. PDOS analysis clearly shows that energy states of highest occupied molecular orbital and lowest unoccupied molecular orbital are predominantly contributed by s orbital. From time-dependent DFT calculations, it is shown that absorption spectra of even-numbered clusters are more intense and are observed at lower wavelength region than the odd-sized gold clusters.

  4. Local Chemical Reactivity of a Metal Alloy Surface

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Scheffler, Matthias

    1995-01-01

    The chemical reactivity of a metal alloy surface is studied by density functional theory investigating the interaction of H2 with NiAl(110). The energy barrier for H2 dissociation is largely different over the Al and Ni sites without, however, reflecting the barriers over the single component metal...... surfaces. This local chemical behavior is due to the covalent nature of the ( H2 σg)-(Ni 3dz2) and ( H2 σu*)-(Ni 3dxz) interactions. Thus, it cannot be described in terms of the Harris-Andersson model (i.e., Pauli repulsion and its weakening by empty d states)....

  5. An experimental investigation of thermo-capillary convection in solution of lithium bromide at non-isothermal absorption

    National Research Council Canada - National Science Library

    Bufetov N. S; Dekhtyar R. A; Ovchinikov V. V

    2016-01-01

    The aim of this work is to obtain new experimental data on the development of thermo-capillary convection in a solution of lithium bromide with non-isothermal absorption of water vapor in a confined vessel...

  6. Non-isothermal buoyancy-driven exchange flows in inclined pipes

    Science.gov (United States)

    Eslami, B.; Shariatnia, S.; Ghasemi, H.; Alba, K.

    2017-06-01

    We study non-isothermal buoyancy-driven exchange flow of two miscible Newtonian fluids in an inclined pipe experimentally. The heavy cold fluid is released into the light hot one in an adiabatic small-aspect-ratio pipe under the Boussinesq limit (small Atwood number). At a fixed temperature, the two fluids involved have the same viscosity. Excellent qualitative and quantitative agreement is first found against rather recent studies in literature on isothermal flows where the driving force of the flow comes from salinity as opposed to temperature difference. The degree of flow instability and mixing enhances as the pipe is progressively inclined towards vertical. Similar to the isothermal limit, maximal rate of the fluids interpenetration in the non-isothermal case occurs at an intermediate angle, β . The interpenetration rate increases with the temperature difference. The degree of fluids mixing and diffusivity is found to increase in the non-isothermal case compared to the isothermal one. There has also been observed a novel asymmetric behavior in the flow, never reported before in the isothermal limit. The cold finger appears to advance faster than the hot one. Backed by meticulously designed supplementary experiments, this asymmetric behavior is hypothetically associated with the wall contact and the formation of a warm less-viscous film of the fluid lubricating the cold more-viscous finger along the pipe. On the other side of the pipe, a cool more-viscous film forms decelerating the hot less-viscous finger. Double diffusive effects associated with the diffusion of heat and mass (salinity) are further investigated. In this case and for the same range of inclination angles and density differences, the level of flow asymmetry is found to decrease. The asymmetric behaviour of the flow is quantified over the full range of experiments. Similar to the study of Salort et al. ["Turbulent velocity profiles in a tilted heat pipe," Phys. Fluids 25(10), 105110

  7. Wall modeling for the simulation of highly non-isothermal unsteady flows; Modelisation de paroi pour la simulation d'ecoulements instationnaires non-isothermes

    Energy Technology Data Exchange (ETDEWEB)

    Devesa, A

    2006-12-15

    Nuclear industry flows are most of the time characterized by their high Reynolds number, density variations (at low Mach numbers) and a highly unsteady behaviour (low to moderate frequencies). High Reynolds numbers are un-affordable by direct simulation (DNS), and simulations must either be performed by solving averaged equations (RANS), or by solving only the large eddies (LES), both using a wall model. A first investigation of this thesis dealt with the derivation and test of two variable density wall models: an algebraic law (CWM) and a zonal approach dedicated to LES (TBLE-{rho}). These models were validated in quasi-isothermal cases, before being used in academic and industrial non-isothermal flows with satisfactory results. Then, a numerical experiment of pulsed passive scalars was performed by DNS, were two forcing conditions were considered: oscillations are imposed in the outer flow; oscillations come from the wall. Several frequencies and amplitudes of oscillations were taken into account in order to gain insights in unsteady effects in the boundary layer, and to create a database for validating wall models in such context. The temporal behaviour of two wall models (algebraic and zonal wall models) were studied and showed that a zonal model produced better results when used in the simulation of unsteady flows. (author)

  8. Simulations of coupled non-isothermal soil moisture transport and evaporation fluxes in a forest area

    Directory of Open Access Journals (Sweden)

    Shao Wei

    2017-12-01

    Full Text Available This study focuses on the quantification of non-isothermal soil moisture transport and evaporation fluxes in vegetated area. A one-dimensional numerical model is developed by integrating a multi-phase flow model with a twolayer energy-balance model. The non-isothermal multi-phase flow model solves four governing equations for coupled air, vapour, moisture, and heat transport in soil porous medium. The two-layer energy balance model estimates evaporation fluxes from transpiration, interception, and soil surface. The model was implemented to an oak forest area in Missouri, USA. For model calibration and validation, measurements of energy fluxes, soil moisture, and soil temperature were used. The proposed model is compared with a simple model that couples the Penman-Monteith equation with the Richards’ equation. The results indicate that the simple model underestimate the total evaporation rate. On the contrary, the proposed model includes a more detailed description of energy transfer, which could improve the accuracy in estimating evaporation rates. The proposed model could be a promising tool to quantify the energy and moisture fluxes in a soil-vegetation-atmosphere continuum in vegetated area.

  9. Non-isothermal Crystallization Kinetics of Mold Fluxes for Casting High-Aluminum Steels

    Science.gov (United States)

    Zhou, Lejun; Li, Huan; Wang, Wanlin; Wu, Zhaoyang; Yu, Jie; Xie, Senlin

    2017-12-01

    This paper investigates the crystallization behavior of CaO-SiO2- and CaO-Al2O3-based mold fluxes for casting high-aluminum steels using single hot thermocouple technology, developed kinetic models, and scanning electron microscope. The results showed that the crystallization ability of the typical CaO-SiO2-based Flux A (CaO/SiO2 0.62, Al2O3 2 mass pct) is weaker than that of CaO-Al2O3-based Flux B (CaO/SiO2 4.11, Al2O3 31.9 mass pct) because of its higher initial crystallization temperature. The crystallization kinetics of Flux A was "surface nucleation and growth, interface reaction control" in the overall non-isothermal crystallization process, whereas that of Flux B was "constant nucleation rate, 1-dimensional growth, diffusion control, in the primary crystallization stage, and then transformed into constant nucleation rate, 3-dimensional growth, interface reaction control in the secondary crystallization stage." The energy dispersive spectroscopy results for Flux B suggested that the variations in the crystallization kinetics for Flux B are due to different crystals precipitating in the primary (BaCa2Al8O15) and secondary (CaAl2O4) crystallization periods during the non-isothermal crystallization process.

  10. Non-isothermal Crystallization Kinetics of Mold Fluxes for Casting High-Aluminum Steels

    Science.gov (United States)

    Zhou, Lejun; Li, Huan; Wang, Wanlin; Wu, Zhaoyang; Yu, Jie; Xie, Senlin

    2017-10-01

    This paper investigates the crystallization behavior of CaO-SiO2- and CaO-Al2O3-based mold fluxes for casting high-aluminum steels using single hot thermocouple technology, developed kinetic models, and scanning electron microscope. The results showed that the crystallization ability of the typical CaO-SiO2-based Flux A (CaO/SiO2 0.62, Al2O3 2 mass pct) is weaker than that of CaO-Al2O3-based Flux B (CaO/SiO2 4.11, Al2O3 31.9 mass pct) because of its higher initial crystallization temperature. The crystallization kinetics of Flux A was "surface nucleation and growth, interface reaction control" in the overall non-isothermal crystallization process, whereas that of Flux B was "constant nucleation rate, 1-dimensional growth, diffusion control, in the primary crystallization stage, and then transformed into constant nucleation rate, 3-dimensional growth, interface reaction control in the secondary crystallization stage." The energy dispersive spectroscopy results for Flux B suggested that the variations in the crystallization kinetics for Flux B are due to different crystals precipitating in the primary (BaCa2Al8O15) and secondary (CaAl2O4) crystallization periods during the non-isothermal crystallization process.

  11. Non-isothermal cure and exfoliation of tri-functional epoxy-clay nanocomposites

    Directory of Open Access Journals (Sweden)

    F. Shiravand

    2015-08-01

    Full Text Available The non-isothermal cure kinetics of polymer silicate layered nanocomposites based on a tri-functional epoxy resin has been investigated by differential scanning calorimetry. From an analysis of the kinetics as a function of the clay content, it can be concluded that the non-isothermal cure reaction can be considered to consist of four different processes: the reaction of epoxy groups with the diamine curing agent; an intra-gallery homopolymerisation reaction which occurs concurrently with the epoxy-amine reaction; and two extra-gallery homopolymerisation reactions, catalysed by the onium ion of the organically modified clay and by the tertiary amines resulting from the epoxy-amine reaction. The final nanostructure displays a similar quality of exfoliation as that observed for the isothermal cure of the same nanocomposite system. This implies that the intra-gallery reaction, which is responsible for the exfoliation, is not significantly inhibited by the extra-gallery epoxy-amine cross-linking reaction.

  12. Non-isothermal crystallization kinetics of As30Te60Ga10 glass

    Science.gov (United States)

    Mohamed, Mansour; Abd-Elnaiem, Alaa M.; Hassan, R. M.; Abdel-Rahim, M. A.; Hafiz, M. M.

    2017-08-01

    The crystallization study under non-isothermal conditions of As30Te60Ga10 glass was investigated. The studied composition was synthesized by melt-quenching technique and characterized by different techniques such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The XRD analysis revealed that the as-prepared and annealed bulk glass of As30Te60Ga10 exhibit the amorphous, and polycrystalline nature, respectively. The DSC results showed that the heating rate affects the characteristic temperatures, for instance, the glass transition, onset, and peak crystallization temperatures. Furthermore, some thermal analysis methods such as the Kissinger and Matusita et al., approximations were employed to determine the crystallization parameters: for example Avrami exponent and the activation energies for glass transition and crystallization process. In addition, we have compared the experimental DSC data with the calculated ones based on the Johnson-Mehl-Avrami (JMA) and Sestak-Berggren SB(M,N) models. The results indicated that the SB(M,N) model is more suitable for describing the non-isothermal crystallization kinetics of the investigated composition.

  13. Non-isothermal cold crystallization kinetics of poly(3-hydoxybutyrate) filled with zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Ries, Andreas, E-mail: ries750@yahoo.com.br [Electrical Engineering Department, Federal University of Paraíba, João Pessoa, PB 58051-900 (Brazil); Canedo, Eduardo L. [Materials Engineering Department, Federal University of Campina Grande, Campina Grande, PB 58429-900 (Brazil); Souto, Cícero R. [Electrical Engineering Department, Federal University of Paraíba, João Pessoa, PB 58051-900 (Brazil); Wellen, Renate M.R. [Materials Engineering Department, Federal University of Paraíba, João Pessoa, PB 58051-900 (Brazil)

    2016-08-10

    Highlights: • Non-isothermal cold crystallization kinetics of PHB filled with ZnO is presented. • Pseudo-Avrami model is best for describing an individual crystallization condition. • Mo model is allows to judge the kinetics of a condition untested in this work. • ZnO affects the kinetics irregularly. - Abstract: The non-isothermal cold crystallization kinetics of poly(3-hydroxybutyrate) (PHB) and PHB-ZnO composites, with ZnO content of 1%, 5% and 10% per weight, was investigated at different heating rates (5, 7.5, 10, 15, 20 and 30 °C/min) using differential scanning calorimetry. Both, Kissinger and Friedman activation energies predict correctly the slowest and fastest crystallizing composition. It was further found, that ZnO can neither be classified as a crystallization accelerator, nor as a crystallization inhibitor; its action is strongly concentration dependent. The empirical Pseudo-Avrami model has the best overall capability for fitting the experimental kinetic data. However, since the Pseudo-Avrami exponent was found to vary irregularly with heating rate and filler content, this model should not be applied for kinetic predictions of an arbitrary composition or an untested heating rate. In such cases, Mo's model should be used.

  14. Thermal stability and non-isothermal crystallization kinetics of Pd82Si18 amorphous ribbon

    Science.gov (United States)

    Wang, Xutong; Zeng, Mo; Nollmann, Niklas; Wilde, Gerhard; Wang, Jiang; Tang, Chengying

    2017-06-01

    Rapidly quenched Pd82Si18 ribbon was prepared by melt spinning. The thermal stability and non-isothermal crystallization kinetics of Pd82Si18 amorphous ribbon were investigated by differential scanning calorimeter measurements. Its structure was investigated by X-ray diffraction and transmission electronic microscopy. The activation energy was calculated by the Kissinger method, and the nucleation and growth during non-isothermal crystallization were investigated by the local activation energy and local Avrami exponent. The average activation energy for Pd82Si18 amorphous ribbon based on the Kissinger method is 330.672 kJ/mol, indicating that it has high thermal stability. The local activation energy of the glass ribbon was determined by the Kissinger-Akahira-Sunose method, and the local Avrami exponent was obtained based on the Johnson-Mehl-Avrami model. The calculated local activation energy increases to a maximum when the crystallization column fraction reaches 0.3, and it then decreases, which shows that crystallization is a multistep process. The local Avrami exponent indicates that the crystallization process of Pd82Si18 amorphous ribbon is controlled by volume nucleation with three-dimensional growth at various nucleation rates.

  15. Thermal stability and non-isothermal crystallization kinetics of Pd82Si18 amorphous ribbon

    Directory of Open Access Journals (Sweden)

    Xutong Wang

    2017-06-01

    Full Text Available Rapidly quenched Pd82Si18 ribbon was prepared by melt spinning. The thermal stability and non-isothermal crystallization kinetics of Pd82Si18 amorphous ribbon were investigated by differential scanning calorimeter measurements. Its structure was investigated by X-ray diffraction and transmission electronic microscopy. The activation energy was calculated by the Kissinger method, and the nucleation and growth during non-isothermal crystallization were investigated by the local activation energy and local Avrami exponent. The average activation energy for Pd82Si18 amorphous ribbon based on the Kissinger method is 330.672 kJ/mol, indicating that it has high thermal stability. The local activation energy of the glass ribbon was determined by the Kissinger–Akahira–Sunose method, and the local Avrami exponent was obtained based on the Johnson–Mehl–Avrami model. The calculated local activation energy increases to a maximum when the crystallization column fraction reaches 0.3, and it then decreases, which shows that crystallization is a multistep process. The local Avrami exponent indicates that the crystallization process of Pd82Si18 amorphous ribbon is controlled by volume nucleation with three-dimensional growth at various nucleation rates.

  16. The effect of Pglass state on the non-isothermal cold and melt crystallization processes of PET matrix

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huichao [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Ma, Jinghong, E-mail: mjh68@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Gong, Jinghua [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Xu, Jian, E-mail: jxu@iccas.ac.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Beijing National Laboratory for Molecular Sciences, Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-08-10

    Highlights: • Pglass is an inorganic polymer with low T{sub g} and mutable viscosity. • Kinetics models and activation energy can be used to analyze the process. • Pglass can play different effect on the crystallization process of PET. - Abstract: The physical state of phosphate glass (Pglass) has an influence on the non-isothermal crystallization behaviors of PET matrix in the PET/Pglass blends, which has been investigated via heating the glassy state and cooling the melt state of the blends at various scanning rates, respectively, by means of differential scanning calorimetry (DSC) technique. The kinetics models based on the Avrami and Mo equations were used to analyze the non-isothermal crystallization process. Furthermore, the activation energy of non-isothermal crystallization, according to Kissinger theory for heating process and Friedman theory for cooling process, has been evaluated. The results showed that the Pglass accelerated the non-isothermal cold crystallization rate of PET matrix due to its nucleation effect. In contrast, for the non-isothermal melt crystallization, the Pglass hindered the crystallization process due to its large melt viscosity.

  17. Non-isothermal flow of viscous liquids: engineering correlations for scale-up guidelines

    Energy Technology Data Exchange (ETDEWEB)

    Dey, A.K.

    1988-10-01

    Measurements of pressure distribution and temperature distribution along the length of model pipeline test rigs were made at varying operating variables for laminar flow of newtonion and power-law liquids. Flow data were also collected for different concentrations of Sobhason Field crude oil mixed with various mixtures of petroleum products. The pressure gradient was found to vary with the length of pipe. The departure of the results from a Poiseuille type equation were examined in the light of related information available in the literature. The selection of proper operating variables could reduce power consumption substantially. The relationships developed from experimental results for a varying range of non-isothermal parameters based on inlet condition and ambient temperature acclaimed importance to scale up in designing pipelines for a given flow rate or pressure drop under variable heat flux conditions. 11 figs., 10 refs., 3 tabs.

  18. Migration of a surfactant-laden droplet in non-isothermal Poiseuille flow

    CERN Document Server

    Das, Sayan; Som, S K; Chakraborty, Suman

    2016-01-01

    The motion of a surfactant-laden viscous droplet in the presence of background non-isothermal Poiseuille flow is studied analytically and numerically. Specifically, the effect of interfacial Marangoni stress due to non-uniform distribution of surfactants and temperature at the droplet interface on the velocity and direction of motion of the droplet along the centerline of imposed Poiseuille flow is investigated in the presence of linearly varying temperature field. In the absence of thermal convection, fluid inertia and shape deformation, the interfacial transport of bulk-insoluble surfactants is governed by the surface Peclet number which represents the relative strength of the advective transport of surfactant over the diffusive transport. We obtain analytical solution for small and large values of the surface Peclet number. Numerical solution is obtained for arbitrary surface Peclet number, which compares well with the analytical solution. Depending on the direction of temperature gradient with respect to ...

  19. Non-isothermal kinetic analysis of processes occurring during thermal treatment of kaolinite

    Science.gov (United States)

    Ondro, Tomáš; Trník, Anton

    2017-07-01

    A non-isothermal kinetic analysis of processes occurring during thermal treatment of kaolinite is carried out using differential thermal analysis on powder samples with heating rates from 1 to 10 °C min-1 in static air atmosphere. For the parameterization of dehydroxylation process and crystallization of Al-Si spinel phase from metakaolinite the Kissinger method is used. The determined values of apparent activation energy for the dehydroxylation of kaolinite and formation of Al-Si spinel phase are (163 ± 11) kJ mol-1 and (826 ± 16) kJ mol-1, respectively. For the dehydroxylation of kaolinite the diffusion controlled growth of a new phase with a decreasing nucleation rate is determined as a mechanism of the process. The results also show that the formation of Al-Si spinel phase from metakaolinite is controlled by grain edge nucleation after saturation.

  20. A study of the non-isothermal crystallization kinetic of Zn10Se90 glass

    Science.gov (United States)

    Abdel-Rahim, M. A.; Hafiz, M. M.; Abdel-Latief, A. Y.; Abd-Elnaiem, Alaa M.; Alwany, A. Elwhab. B.

    2015-06-01

    The glass transition and the crystallization kinetics of Zn10Se90 glass by differential thermal analysis (DTA) technique under non-isothermal conduction were studied. The effective activation energies of the glass transition and the crystallization have been evaluated on the basses of the Kissinger and Matusita et al. approximations. Kinetic parameters of the crystallization process are significantly influenced by the heating rate. We have compared the experimental DTA with the calculated data curves for Zn10Se90 system using the Johanson-Mehl-Avrami (JMA) and Sestak-Berggren SB( M, N) models. Simulation results indicated that the SB( M, N) model is more suitable for describing the crystallization kinetics for the studied composition. Furthermore, the crystalline phases of annealed Zn10Se90 were characterized by X-ray diffraction. The surface morphology of the annealed samples was examined using scanning electron microscopy.

  1. Non-isothermal curing kinetics and physical properties of MMT-reinforced unsaturated polyester (UP) resins

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, María A., E-mail: angelesvh@yahoo.com [Tecnológico de Estudios Superiores de Ecatepec, Av. Tecnológico S/N, Valle de Anáhuac, 55210 Ecatepec de Morelos (Mexico); Vázquez, H. [Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Física, Av. San Rafael Atlixco 186, col. Vicentina, Mexico, D.F. 09340 (Mexico); Guthausen, G. [KIT, Pro2NMR at MVM and IBG, Karlsruhe (Germany)

    2015-07-10

    Highlights: • Non-isothermal DSC analysis results have shown that the addition of MMT to a UP resin produces a delay in the cure reaction. • The shape of experimental heat-flow DSC curves showed two exothermic peaks for all the samples at different heating rates. • The overall kinetic analysis was performed by isoconversional methods. • It was found that the dependence of the activation energy (E{sub a}) on degree of reaction (α) is complex. - Abstract: Cure behavior of unsaturated polyester (UP)/montmorillonite (MMT)/methyl ethyl ketone peroxide (MEKP)/cobalt octoate intercalated nanocomposites with various MMT loadings was investigated by dynamic differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). UP/MMT nanocomposites were prepared by sequential mixing. Non-isothermal DSC curves were obtained by applying heating rates ranging from 5 to 20 °C/min. They presented two exothermic peaks, which should correspond to two independent cure reactions. The effective activation energy E{sub a}, was determined by applying both the Kissinger’s and Starink’s methods. The results showed slightly higher activation energy for nanocomposites, except for UP/10-MMT. It was found that the dependence of E{sub a} on α is complex. All the systems in this study fitted Sesták–Berggren (SB) model in overall reaction controlled kinetics and the corresponding model parameters, n, m, A were obtained, but it was insufficient in depicting the complex reaction kinetics. Transmission electron microscopy data support the formation of a partially delaminated nanocomposite material. UP and nanocomposites showed similar behavior on thermal stability.

  2. Estimation of Physical Properties and Chemical Reactivity Parameters of Organic Compounds for Environmental Modeling by SPARC

    Science.gov (United States)

    Mathematical models for predicting the transport and fate of pollutants in the environment require reactivity parameter values that is value of the physical and chemical constants that govern reactivity. Although empirical structure activity relationships have been developed th...

  3. Isothermal and non-isothermal sublimation kinetics of zirconium tetrachloride (ZrCl{sub 4}) for producing nuclear grade Zr

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jae Hong [Department of Materials Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Choi, Mi Sun [Research Institute of Industrial Science and Technology (RIST), Pohang 790-330 (Korea, Republic of); Min, Dong Joon [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Park, Joo Hyun, E-mail: basicity@hanyang.ac.kr [Department of Materials Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of)

    2014-02-14

    Sublimation of ZrCl{sub 4} is important for the production of nuclear grade metallic Zr in Kroll's process. The sublimation kinetics of ZrCl{sub 4} was investigated by thermogravimetric analysis under both isothermal and non-isothermal conditions. The sublimation rate of ZrCl{sub 4} increased with increasing temperature under isothermal conditions. ZrCl{sub 4} sublimation was confirmed to be a zero-order process under isothermal conditions, whereas it was first-order kinetics under non-isothermal conditions. The activation energy of ZrCl{sub 4} sublimation under isothermal conditions was 21.7 kJ mol{sup −1}. The activation energy for non-isothermal sublimation was 101.4 kJ mol{sup −1} and 108.1 kJ mol{sup −1} with the Kissinger method and Flynn–Wall–Ozawa method, respectively. These non-isothermal activation energies were very close to the heat of sublimation (103.3 kJ mol{sup −1}). Sublimation occurs by two elementary steps: surface reaction and desorption. Therefore, the overall activation energy of ZrCl{sub 4} sublimation is 104.8 (±3.4) kJ mol{sup −1}. The activation energy of the surface reaction and desorption steps are proposed to be 83.1 kJ mol{sup −1} and 21.7 kJ mol{sup −1}, respectively. - Highlights: • Sublimation kinetics of ZrCl{sub 4} was quantitatively analyzed using TGA method. • Isothermal and non-isothermal sublimation kinetics were quantitatively evaluated. • Activation energies of isothermal and non-isothermal kinetics were obtained. • Sublimation mechanism was proposed from kinetic analyses and SEM observations. • This kinetic information will be very useful in production of nuclear grade Zr.

  4. Machine learning of chemical reactivity from databases of organic reactions.

    Science.gov (United States)

    Carrera, Gonçalo V S M; Gupta, Sunil; Aires-de-Sousa, João

    2009-07-01

    Databases of chemical reactions contain knowledge about the reactivity of specific reagents. Although information is in general only explicitly available for compounds reported to react, it is possible to derive information about substructures that do not react in the reported reactions. Both types of information (positive and negative) can be used to train machine learning techniques to predict if a compound reacts or not with a specific reagent. The whole process was implemented with two databases of reactions, one involving BuNH2 as the reagent, and the other NaCNBH3. Negative information was derived using MOLMAP molecular descriptors, and classification models were developed with Random Forests also based on MOLMAP descriptors. MOLMAP descriptors were based exclusively on calculated physicochemical features of molecules. Correct predictions were achieved for approximately 90% of independent test sets. While NaCNBH3 is a selective reducing reagent widely used in organic synthesis, BuNH2 is a nucleophile that mimics the reactivity of the lysine side chain (involved in an initiating step of the mechanism leading to skin sensitization).

  5. Phase rule calculations and the thermodynamics of reactive systems under chemical equilibrium

    OpenAIRE

    PLATT G. M.; Medeiros,J. L.

    1999-01-01

    In this paper, we examine the resolution of some phase rule problems within the context of multiple chemical equilibrium reactions, using cubic equations of state and an activity coefficient model. Bubble and dew reactive surfaces, reactive azeotropic loci and reactive critical loci are generated and presented in graphical form. Also isobaric bubble and dew reactive enthalpy loci, which may be useful in the modeling of reactive distillation operations, are depicted. All the formalism here emp...

  6. Non-isothermal kinetics of phase transformations in magnetron sputtered alumina films with metastable structure

    Energy Technology Data Exchange (ETDEWEB)

    Zuzjaková, Š., E-mail: sazuz@kfy.zcu.cz; Zeman, P.; Kos, Š.

    2013-11-20

    Highlights: • Non-isothermal kinetics of phase transformations in alumina films was investigated. • The structure of alumina films affects kinetics of the transformation processes. • Kinetic triplets of all transformation processes were determined. • The KAS, FWO, FR and IKP methods for determination of E{sub a} and A were used. • The Málek method for determination of the kinetic model was used. - Abstract: The paper reports on non-isothermal kinetics of transformation processes in magnetron sputtered alumina thin films with an amorphous and γ-phase structure leading ultimately to the formation of the thermodynamically stable α-Al{sub 2}O{sub 3} phase. Phase transformation sequences in the alumina films were investigated using differential scanning calorimetry (DSC) at four different heating rates (10, 20, 30, 40 °C/min). Three isoconversional methods (Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO) and Friedman (FR) method) as well as the invariant kinetic parameters (IKP) method were used to determine the activation energies for transformation processes. Moreover, the pre-exponential factors were determined using the IKP method. The kinetic models of the transformation processes were determined using the Málek method. It was found that the as-deposited structure of alumina films affects kinetics of the transformation processes. The film with the amorphous as-deposited structure heated at 40 °C/min transforms to the crystalline γ phase at a temperature of ∼930 °C (E{sub a,IKP} = 463 ± 10 kJ/mol) and subsequently to the crystalline α phase at a temperature of ∼1200 °C (E{sub a,IKP} = 589 ± 10 kJ/mol). The film with the crystalline γ-phase structure heated at 40 °C/min is thermally stable up to ∼1100 °C and transforms to the crystalline α phase (E{sub a,IKP} = 511 ± 16 kJ/mol) at a temperature of ∼1195 °C. The empirical two-parameter Šesták–Berggren kinetic model was found to be the most adequate one to describe

  7. Study of Glass-Transition Kinetics of Pb-Modified SeIn System by Using Non-isothermal Differential Scanning Calorimetry

    Science.gov (United States)

    Ram, Indra Sen; Singh, Kedar

    2014-01-01

    Glass-transition kinetics of ( 0, 5, 10, and 15) chalcogenide glasses have been carried out at different heating rates by using differential scanning calorimeter (DSC) under the non-isothermal condition. The glass-transition temperature and peak glass-transition temperature have been determined from DSC thermograms. The reduced glass temperature , total relaxation time thermal-stability parameters and , the activation energy of glass transition , the fragility index , and the average coordination number have been calculated on the basis of the experimental results. The temperature differences , and are found to be maxima for glass. This indicates that glass has the highest thermal stability and glass-forming ability in the investigated compositional range. These results could be explained on the basis of modification of the chemical bond formation due to incorporation of Pb in the Se-In glassy matrix.

  8. Non-isothermal degradation kinetics of filled with rise husk ash polypropene composites

    Directory of Open Access Journals (Sweden)

    2008-02-01

    Full Text Available The thermal stability and kinetics of non-isothermal degradation of polypropene and polypropene composites filled with 20 mass% vigorously grounded and mixed raw rice husks (RRH, black rice husks ash (BRHA, white rice husks ash (WRHA and Aerosil Degussa (AR were studied. The calculation procedures of Coats – Redfern, Madhysudanan et al., Tang et al., Wanjun et al. and 27 model kinetic equations were used. The kinetics of thermal degradation were found to be best described by kinetic equations of n-th order (Fn mechanism. The kinetic parameters E, A, ΔS≠, ΔH≠and ΔG≠for all the samples studied were calculated. The highest values of n, E and A were obtained for the composites filled with WRHA and AR. A linear dependence between lnA and E was observed, known also as kinetic compensation effect. The results obtained were considered enough to conclude that the cheap RRH and the products of its thermal degradation BRHA and WRHA, after vigorously grounding and mixing, could successfully be used as fillers for polypropene instead of the much more expensive synthetic material Aerosil to prepare various polypropene composites.

  9. Replicative manufacturing of complex lighting optics by non-isothermal glass molding

    Science.gov (United States)

    Kreilkamp, Holger; Vu, Anh Tuan; Dambon, Olaf; Klocke, Fritz

    2016-09-01

    The advantages of LED lighting, especially its energy efficiency and the long service life have led to a wide distribution of LED technology in the world. However, in order to make fully use of the great potential that LED lighting offers, complex optics are required to distribute the emitted light from the LED efficiently. Nowadays, many applications use polymer optics which can be manufactured at low costs. However, due to ever increasing luminous power, polymer optics reach their technological limits. Due to its outstanding properties, especially its temperature resistance, resistance against UV radiation and its long term stability, glass is the alternative material of choice for the use in LED optics. This research is introducing a new replicative glass manufacturing approach, namely non-isothermal glass molding (NGM) which is able to manufacture complex lighting optics in high volumes at competitive prices. The integration of FEM simulation at the early stage of the process development is presented and helps to guarantee a fast development cycle. A coupled thermo-mechanical model is used to define the geometry of the glass preform as well as to define the mold surface geometry. Furthermore, simulation is used to predict main process outcomes, especially in terms of resulting form accuracy of the molded optics. Experiments conducted on a commercially available molding machine are presented to validate the developed simulation model. Finally, the influence of distinct parameters on important process outcomes like form accuracy, surface roughness, birefringence, etc. is discussed.

  10. A NON-ISOTHERMAL THEORY FOR INTERPRETING SODIUM LINES IN TRANSMISSION SPECTRA OF EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Kevin; Lavie, Baptiste [University of Bern, Physics Institute, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Wyttenbach, Aurélien; Ehrenreich, David; Lovis, Christophe [Observatoire de l’Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny (Switzerland); Sing, David K., E-mail: kevin.heng@csh.unibe.ch [Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

    2015-04-10

    We present a theory for interpreting the sodium lines detected in transmission spectra of exoplanetary atmospheres. Previous analyses employed the isothermal approximation and dealt only with the transit radius. By recognizing the absorption depth and the transit radius as being independent observables, we develop a theory for jointly interpreting both quantities, which allows us to infer the temperatures and number densities associated with the sodium lines. We are able to treat a non-isothermal situation with a constant temperature gradient. Our novel diagnostics take the form of simple-to-use algebraic formulae and require measurements of the transit radii (and their corresponding absorption depths) at line center and in the line wing for both sodium lines. We apply our diagnostics to the HARPS data of HD 189733b, confirm the upper atmospheric heating reported by Huitson et al., derive a temperature gradient of 0.4376 ± 0.0154 K km{sup −1}, and find densities ∼1–10{sup 4} cm{sup −3}.

  11. Non-isothermal kinetic studies on co-processing of vacuum residue, plastics, coal and petrocrop

    Energy Technology Data Exchange (ETDEWEB)

    Ahmaruzzaman, M.; Sharma, D.K. [Centre for Energy Studies, Indian Institute of Technology, New Delhi 110016 (India)

    2005-06-15

    Co-processing of petroleum vacuum residue (BVR) with plastics (polypropylene, bakelite), coal (Samla coal), and biomass (bagasse, Calotropis procera) was carried out in a thermogravimetric analyzer (TGA) reaction system in nitrogen atmosphere with a view to comparing the process of the mixture with those of the individual components. Experiments were conducted at heating rate of 40{sup o}C/min, in the temperature range of 30-900{sup o}C. Based on the results obtained, three temperature regimes were selected for studying the non-isothermal kinetics of TGA of individual BVR, plastics, coal, biomass as well as of the co-processing of these with BVR, i.e., below 400{sup o}C, between 400 and 500{sup o}C and above 500{sup o}C. The kinetic studies were performed using Coats and Redfern kinetic-modeling equations. The overall activation energies were 60.83kJ/mole for petroleum residue, 99.41kJ/mole for polypropylene, 21.08kJ/mole for coal, 22.68kJ/mole for C. procera and 31.9kJ/mole for the mixture of these four materials. Thus, it has been found that there exists an overall synergy, when four materials were co-processed together. The overall orders and activation energies change during co-processing of two, three or four different macromolecules including petroleum residue as observed presently. The results obtained are being reported.

  12. Evaluation of agricultural residues pyrolysis under non-isothermal conditions: Thermal behaviors, kinetics, and thermodynamics.

    Science.gov (United States)

    Chen, Jianbiao; Wang, Yanhong; Lang, Xuemei; Ren, Xiu'e; Fan, Shuanshi

    2017-10-01

    The thermal conversion characteristics, kinetics, and thermodynamics of agricultural residues, rape straw (RS) and wheat bran (WB), were investigated under non-isothermal conditions. TGA experiments showed that the pyrolysis characteristics of RS were quite different from those of WB. As reflected by the comprehensive devolatilization index, when the heating rate increased from 10 to 30Kmin-1, the pyrolysis performance of RS and WB were improved 5.27 and 5.96 times, respectively. The kinetic triplets of the main pyrolysis process of agricultural residues were calculated by the Starink method and the integral master-plots method. Kinetic analysis results indicated that the most potential kinetic models for the pyrolysis of RS and WB were D2 and F2.7, respectively. The thermodynamic parameters (ΔH, ΔG, and ΔS) were determined by the activated complex theory. The positive ΔH, positive ΔG, and negative ΔS at characteristic temperatures validated that the pyrolysis of agricultural residues was endothermic and non-spontaneous. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Non-isothermal precipitation behaviors of Al-Mg-Si-Cu alloys with different Zn contents

    Energy Technology Data Exchange (ETDEWEB)

    Guo, M.X., E-mail: mingxingguo@skl.ustb.edu.cn; Zhang, Y.; Zhang, X.K.; Zhang, J.S.; Zhuang, L.Z.

    2016-07-04

    The non-isothermal precipitation behaviors of Al–Mg–Si–Cu alloys with different Zn contents were investigated by differential scanning calorimetry (DSC) analysis, hardness measurement and high resolution transmission electron microscope characterization. The results show that Zn addition has a significant effect on the GP zone dissolution and precipitation of Al-Mg-Si-Cu alloys. And their activation energies change with the changes of Zn content and aging conditions. Precipitation kinetics can be improved by adding 0.5 wt% or 3.0 wt%Zn, while be suppressed after adding 1.5 wt%Zn. The Mg-Si precipitates (GP zones and β″) are still the main precipitates in the Al-Mg-Si-Cu alloys after heated up to 250 °C, and no Mg-Zn precipitates are observed in the Zn-added alloy due to the occurrence of Mg-Zn precipitates reversion. The measured age-hardening responses of the alloys are corresponding to the predicted results by the established precipitation kinetic equations. Additionally, a double-hump phenomenon of hardness appears in the artificial aging of pre-aged alloy with 3.0 wt% Zn addition, which resulted from the formation of pre-β″ and β″ precipitates. Finally, the precipitation mechanism of Al-Mg-Si-Cu alloys with different Zn contents was proposed based on the microstructure evolution and interaction forces between Mg, Si and Zn atoms.

  14. Navier-Stokes-Fourier analytic solutions for non-isothermal Couette slip gas flow

    Directory of Open Access Journals (Sweden)

    Milićev Snežana S.

    2016-01-01

    Full Text Available The explicit and reliable analytical solutions for steady plane compressible non-isothermal Couette gas flow are presented. These solutions for velocity and temperature are developed by macroscopic approach from Navier-Stokes-Fourier system of continuum equations and the velocity slip and the temperature jump first order boundary conditions. Variability of the viscosity and thermal conductivity with temperature is involved in the model. The known result for the gas flow with constant and equal temperatures of the walls (isothermal walls is verified and a new solution for the case of different temperature of the walls is obtained. Evan though the solution for isothermal walls correspond to the gas flow of the Knudsen number Kn≤0.1, i.e. to the slip and continuum flow, it is shown that the gas velocity and related shear stress are also valid for the whole range of the Knudsen number. The deviation from numerical results for the same system is less than 1%. The reliability of the solution is confirmed by comparing with results of other authors which are obtained numerically by microscopic approach. The advantage of the presented solution compared to previous is in a very simple applicability along with high accuracy. [Projekat Ministarstva nauke Republike Srbije, br. 35046 i 174014

  15. Non-isothermal pyrolysis of de-oiled microalgal biomass: Kinetics and evolved gas analysis.

    Science.gov (United States)

    Maurya, Rahulkumar; Ghosh, Tonmoy; Saravaia, Hitesh; Paliwal, Chetan; Ghosh, Arup; Mishra, Sandhya

    2016-12-01

    Non-isothermal (β=5, 10, 20, 35°C/min) pyrolysis of de-oiled microalgal biomass (DMB) of Chlorella variabilis was investigated by TGA-MS (30-900°C, Argon atmosphere) to understand thermal decomposition and evolved gas analysis (EGA). The results showed that three-stage thermal decomposition and three volatilization zone (100-400°C, 400-550°C and 600-750°C) of organic matters during pyrolysis. The highest rate of weight-loss is 8.91%/min at 302°C for 35°C/min heating-rate. Kinetics of pyrolysis were investigated by iso-conversional (KAS, FWO) and model-fitting (Coats-Redfern) method. For Zone-1and3, similar activation energy (Ea) is found in between KAS (α=0.4), FWO (α=0.4) and Avrami-Erofe'ev (n=4) model. Using the best-fitted kinetic model Avrami-Erofe'ev (n=4), Ea values (R(2)=>0.96) are 171.12 (Zone-1), 404.65 (Zone-2) and 691.42kJ/mol (Zone-3). EGA indicate the abundance of most gases observed consequently between 200-300°C and 400-500°C. The pyrolysis of DMB involved multi-step reaction mechanisms for solid-state reactions having different Ea values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Kink Waves in Non-isothermal Stratified Solar Waveguides: Effect of the External Magnetic Field

    Science.gov (United States)

    Lopin, I.; Nagorny, I.

    2017-10-01

    We study the effect of an external magnetic field on the properties of kink waves, propagating along a thin non-isothermal stratified and diverging magnetic flux tube. A wave equation, governing the propagation of kink waves under the adopted model is derived. It is shown that the vertical gradient of temperature introduces a spatially local cut-off frequency ω c . The vertical distribution of the cut-off frequency is calculated for the reference VAL-C model of the solar atmosphere and for different values of a ratio of external to internal magnetic fields. The results show that the cut-off frequency is negative below the temperature minimum due to the negative temperature gradient. In the chromosphere the cut-off frequency at a given height is smaller for a stronger external magnetic field. For the appropriate range of a ratio B e /B i ≈ 0-0.8, the cutoff lies in the range ω c ≈ 0.003-0.010 s-1 (periods 600 , ω 2/ω 1 < 2. This reduction grows for a larger ratio of temperature at the loop top to the temperature at the footpoints. Moreover, the effect of reduction is most pronounced for the steeper temperature profiles.

  17. Non-isothermal crystallization kinetics of the heavy-group lanthanide dititanates

    Science.gov (United States)

    Milićević, Bojana; Kuzman, Sanja; Porobić, Slavica J.; Marinović-Cincović, Milena; Dramićanin, Miroslav D.

    2017-12-01

    The systematic investigation of crystallization kinetics of heavy-group lanthanide dititanate pyrochlores, HL2Ti2O7 (HL=Lu, Tm, Er, Ho, Y, Dy, and Tb) is presented. Materials are prepared by the Pechini-type polymerized complex route, and their thermal properties were studied by differential thermal analysis under non-isothermal conditions. For this group, the crystallization temperature became larger with increasing the ionic radius of lanthanides, from 1066 K for Lu2Ti2O7 to 1125 K for Tb2Ti2O7. The linear dependence of crystallization temperature on radius of heavy lanthanide ions is found to follows Tc [ K ] = 168.86 + 920.89 ×rion [ Å ] semi-empirical equation. Apparent activation energies of crystallization were obtained from calculations based on the Arrhenius equation, isoconversional method and Pérez-Maqueda method, and are ∼805 kJ mol-1 calculated by three different methods. The crystallization kinetics followed the so-called Avrami-Erofeev (A3) model, as confirmed using several criteria, namely, the Málek, master plot, and Pérez-Maqueda methods. The crystallization mechanism of all lanthanide dititanate pyrochlores is found to be the same, and the crystallization process involves a constant rate of nucleation and two-dimensional growth of nuclei.

  18. Encoding of Fundamental Chemical Entities of Organic Reactivity Interest using chemical ontology and XML.

    Science.gov (United States)

    Durairaj, Vijayasarathi; Punnaivanam, Sankar

    2015-09-01

    Fundamental chemical entities are identified in the context of organic reactivity and classified as appropriate concept classes namely ElectronEntity, AtomEntity, AtomGroupEntity, FunctionalGroupEntity and MolecularEntity. The entity classes and their subclasses are organized into a chemical ontology named "ChemEnt" for the purpose of assertion, restriction and modification of properties through entity relations. Individual instances of entity classes are defined and encoded as a library of chemical entities in XML. The instances of entity classes are distinguished with a unique notation and identification values in order to map them with the ontology definitions. A model GUI named Entity Table is created to view graphical representations of all the entity instances. The detection of chemical entities in chemical structures is achieved through suitable algorithms. The possibility of asserting properties to the entities at different levels and the mechanism of property flow within the hierarchical entity levels is outlined. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Pyrolysis of olive residue and sugar cane bagasse: non-isothermal thermogravimetric kinetic analysis.

    Science.gov (United States)

    Ounas, A; Aboulkas, A; El Harfi, K; Bacaoui, A; Yaacoubi, A

    2011-12-01

    Thermal degradation and kinetics for olive residue and sugar cane bagasse have been evaluated under dynamic conditions in the presence of nitrogen atmosphere, using a non-isothermal thermogravimetric method (TGA). The effect of heating rate was evaluated in the range of 2-50 K min(-1) providing significant parameters for the fingerprinting of the biomass. The DTG plot for the olive residue and sugar cane bagasse clearly shows that the bagasse begins to degrade at 473 K and exhibits two major peaks. The initial mass-loss was associated with hemicellulose pyrolysis and responsible for the first peak (538-543 K) whereas cellulose pyrolysis was initiated at higher temperatures and responsible for the second peak (600-607 K). The two biomass mainly devolatilized around 473-673 K, with total volatile yield of about 70-75%. The char in final residue was about 19-26%. Mass loss and mass loss rates were strongly affected by heating rate. It was found that an increase in heating rate resulted in a shift of thermograms to higher temperatures. Ozawa-Flynn-Wall and Vyazovkin methods were applied to determine apparent activation energy to the olive residue and sugar cane bagasse. Two different steps were detected with apparent activation energies in the 10-40% conversion range have a value of 153-162 kJ mol(-1) and 168-180 kJ mol(-1) for the hemicellulose degradation of olive residue and sugar cane bagasse, respectively. In the 50-80% conversion range, this value is 204-215 kJ mol(-1) and 231-240 kJ mol(-1) for the cellulose degradation of olive residue and sugar cane bagasse, respectively. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Non-isothermal crystallization kinetics and characterization of biodegradable poly(butylene succinate-co-neopentyl glycol succinate) copolyesters.

    Science.gov (United States)

    Xie, Wen-Jie; Zhou, Xiao-Ming

    2015-01-01

    Both biodegradable aliphatic neat poly(butylene succinate) (PBS) and poly(butylene succinate-co-neopentyl glycol succinate) (P(BS-co-NPGS)) copolyesters with different 1,4-butanediol/neopentyl glycol ratios were synthesized through a two-step process of transesterification and polycondensation using stannous chloride and 4-Methylbenzenesulfonic acid as the co-catalysts. The structure, non-isothermal crystallization behavior, crystalline morphology and crystal structure of neat PBS and P(BS-co-NPGS) copolyesters were characterized by (1)H NMR, differential scanning calorimetry (DSC), polarized optical microscope (POM) and wide angle X-ray diffraction (WAXD), respectively. The Avrami equation modified by Jeziorny and Mo's method was employed to describe the non-isothermal crystallization kinetics of the neat PBS and its copolyesters. The modified Avrami equation could adequately describe the primary stage of non-isothermal crystallization kinetics of the neat PBS and its copolyesters. Mo's method provided a fairly satisfactory description of the non-isothermal crystallization of neat PBS and its copolyesters. Interestingly, the values of 1/t1/2, Zc and F(T) obtained by the modified Avrami equation and Mo's method analysis indicated that the crystallization rate increased first and then decreased with an increase of NPGS content compared that of neat PBS, whereas the crystallization mechanism almost kept unchanged. The results of tensile testing showed that the ductility of PBS was largely improved by incorporating NPGS units. The elongation at break increased remarkably with increasing NPGS content. In particular, the sample with 20% NPGS content showed around 548% elongation at break. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Modeling the growth of Lactobacillus viridescens under non-isothermal conditions in vacuum-packed sliced ham.

    Science.gov (United States)

    Silva, Nathália Buss da; Longhi, Daniel Angelo; Martins, Wiaslan Figueiredo; Laurindo, João Borges; Aragão, Gláucia Maria Falcão de; Carciofi, Bruno Augusto Mattar

    2017-01-02

    Lactic acid bacteria (LAB) are responsible for spoiling vacuum-packed meat products, such as ham. Since the temperature is the main factor affecting the microbial dynamic, the use of mathematical models describing the microbial behavior into a non-isothermal environment can be very useful for predicting food shelf life. In this study, the growth of Lactobacillus viridescens was measured in vacuum-packed sliced ham under non-isothermal conditions, and the predictive ability of primary (Baranyi and Roberts, 1994) and secondary (Square Root) models were assessed using parameters estimated in MRS culture medium under isothermal conditions (between 4 and 30°C). Fresh ham piece was sterilized, sliced, inoculated, vacuum-packed, and stored in a temperature-controlled incubator at five different non-isothermal conditions (between 4 and 25°C) and one isothermal condition (8°C). The mathematical models obtained in MRS medium were assessed by comparing predicted values with L. viridescens growth data in vacuum-packed ham. Its predictive ability was assessed through statistical indexes, with good results (bias factor between 0.95 and 1.03; accuracy factor between 1.04 and 1.07, and RMSE between 0.76 and 1.33), especially in increasing temperature, which predictions were safe. The model parameters obtained from isothermal growth data in MRS medium enabled to estimate the shelf life of a commercial ham under non-isothermal conditions in the temperature range analyzed. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Effect of polypyrrole embedment on non-isothermal crystallization kinetics of poly (vinylidene fluoride-co-hexafluoropropylene)

    Science.gov (United States)

    Biswas, Swarup; Bhattacharya, S.

    2017-05-01

    Polypyrrole (PPy)/Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) blend is synthesized by in situ polymerization of pyrrole. FTIR confirms the formation of Polypyrrole (PPy) within PVDF-HFP matrices. Weight percentages of different components within composites are estimated by TGA. Detailed study of nucleation and kinetics at its melt condition under non-isothermal environment is done by the DSC measurement. The presence of PPy within the PVDF-HFP matrices accelerated the nucleation rate of the polymer.

  3. On the Inclusion of Inorganic Chemical Reactivity in High School Chemistry: The Reactivity Network.

    Science.gov (United States)

    Mellon, E. K.

    1989-01-01

    Reports the function of the Reactivity Network which is to translate reactivity data from the primary literature into some 30 reviews for high school teachers and curriculum developers and to disseminate that information nationwide. Discusses a needs assessment done for the project. (MVL)

  4. Production of valuable pyrolytic oils from mixed Municipal Solid Waste (MSW in Indonesia using non-isothermal and isothermal experimental

    Directory of Open Access Journals (Sweden)

    Indra Mamad Gandidi

    2017-09-01

    Full Text Available Municipal solid waste (MSW, disposed of at open dumping sites, poses health risks, contaminates surface water, and releases greenhouse gasses such as methane. However, pyrolysis offers the opportunity to convert MSW into Bio-Oil (BO for clean energy resource. In this paper, an MSW sample consisting of plastic, paper and cardboard, rubber and textiles, and vegetable waste is pyrolysed on a laboratory scale in a fixed-bed vacuum reactor. In the non-isothermal process, the sample was fed into the reactor and then heated. In the isothermal process, the reactor is first heated and then the sample is added. The non-isothermal process created greater BO in both quality and quantity. The BO had a larger amount of gasoline species than diesel-48 fuel, with at 33.44%the BO produced by isothermal pyrolysis and 36.42% in non-isothermal pyrolysis. However the product of isothermal pyrolysis had a higher acid content that reduced its heating value.

  5. Isothermal and non-isothermal infiltration and deuterium transport: a case study on undisturbed soil column from headwater catchment

    Science.gov (United States)

    Sobotkova, Martina; Snehota, Michal; Tesar, Miroslav

    2017-04-01

    Isothermal and non-isothermal infiltration experiments with tracer breakthrough were carried out in the laboratory on intact column of sandy loam soil taken from Roklan site (Sumava Mountains, Czech Republic). In the case of isothermal experiment, the temperature of infiltrating water was almost equal to the initial temperature of the sample. For the non-isothermal case the infiltration was performed using water approximately 10 °C colder than was the initial temperature of soil sample. The experiments were otherwise conducted under the same initial and boundary conditions. Pressure heads and temperatures in two depths (8.8 and 15.3 cm) inside the soil were monitored as well as the temperature of water entering and leaving the sample. Water drained freely through the perforated plate at the bottom of the sample by gravity and outflow was measured using tipping bucket flowmeter. Permeability of the sample calculated for steady state stages of the experiment showed that significant difference between water flow rates recorded during two experiment could not be justified only by temperature induced changes of water viscosity and density. Results of deuterium breakthrough were nearly identical for isothermal and non-isothermal conditions.

  6. Modeling the reactivities of hydroxyl radical and ozone towards atmospheric organic chemicals using quantitative structure-reactivity relationship approaches.

    Science.gov (United States)

    Gupta, Shikha; Basant, Nikita; Mohan, Dinesh; Singh, Kunwar P

    2016-07-01

    The persistence and the removal of organic chemicals from the atmosphere are largely determined by their reactions with the OH radical and O3. Experimental determinations of the kinetic rate constants of OH and O3 with a large number of chemicals are tedious and resource intensive and development of computational approaches has widely been advocated. Recently, ensemble machine learning (EML) methods have emerged as unbiased tools to establish relationship between independent and dependent variables having a nonlinear dependence. In this study, EML-based, temperature-dependent quantitative structure-reactivity relationship (QSRR) models have been developed for predicting the kinetic rate constants for OH (kOH) and O3 (kO3) reactions with diverse chemicals. Structural diversity of chemicals was evaluated using a Tanimoto similarity index. The generalization and prediction abilities of the constructed models were established through rigorous internal and external validation performed employing statistical checks. In test data, the EML QSRR models yielded correlation (R (2)) of ≥0.91 between the measured and the predicted reactivities. The applicability domains of the constructed models were determined using methods based on descriptors range, Euclidean distance, leverage, and standardization approaches. The prediction accuracies for the higher reactivity compounds were relatively better than those of the low reactivity compounds. Proposed EML QSRR models performed well and outperformed the previous reports. The proposed QSRR models can make predictions of rate constants at different temperatures. The proposed models can be useful tools in predicting the reactivities of chemicals towards OH radical and O3 in the atmosphere.

  7. Thermodynamic characterization of polymeric materials subjected to non-isothermal flows: Experiment, theory and simulation

    Science.gov (United States)

    Ionescu, Tudor Constantin

    Frictional or viscous heating phenomena are found in virtually every industrial operation dealing with processing of polymeric materials. This work is aimed at addressing some of the existing shortcomings in modeling non-isothermal polymer flowing processes. Specifically, existing theories suggest that when a polymer melt is subjected to deformation, its internal energy changes very little compared to its conformational entropy. This statement forms the definition of the Theory of Purely Entropic Elasticity (PEE) applied to polymer melts. Under the auspices of this theory, the temperature evolution equation for modeling the polymer melt under an applied deformation is greatly simplified. In this study, using a combination of experimental measurements, continuum-based computer modeling and molecular simulation techniques, the validity of this theory is tested for a wide range of processing conditions. First, we present experimental evidence that this theory is only valid for low deformation regimes. Furthermore, using molecular theory, a direct correlation is found between the relaxation characteristics of the polymer and the flow regime where this theory stops being valid. We present a new and improved form of the temperature equation containing an extra term previously neglected under the PEE assumption, followed by a recipe for evaluating the extra term. The corrected temperature equation is found to give more accurate predictions for the temperature profiles in the high flow rate regimes, in excellent agreement with our experimental measurements. Next, in order to gain a molecular-level understanding of our experimental findings, a series of polydisperse linear alkane systems with average chain lengths between 24 and 78 carbon atoms are modeled with an applied "orienting field" using a highly efficient non-equilibrium Monte Carlo scheme. Our simulation results appear to substantiate our experimental findings. The internal energy change of the oriented

  8. Non-isothermal kinetics of the thermal desorption of mercury from a contaminated soil

    Directory of Open Access Journals (Sweden)

    López, Félix A.

    2014-03-01

    Full Text Available The Almadén mining district (Ciudad Real, Spain was the largest cinnabar (mercury sulphide mine in the world. Its soils have high levels of mercury a consequence of its natural lithology, but often made much worse by its mining history. The present work examines the thermal desorption of two contaminated soils from the Almadén area under non-isothermal conditions in a N2 atmosphere, using differential scanning calorimetry (DSC. DSC was performed at different heating rates between room temperature and 600 °C. Desorption temperatures for different mercury species were determined. The Friedman, Flynn-Wall-Ozawa and Coasts–Redfern methods were employed to determine the reaction kinetics from the DSC data. The activation energy and pre-exponential factor for mercury desorption were calculated.El distrito minero de Almadén (Ciudad Real, España tiene la mayor mina de cinabrio (sulfuro de mercurio del mundo. Sus suelos tienen altos niveles de mercurio como consecuencia de su litología natural, pero a menudo su contenido en mercurio es mucho más alto debido a la historia minera de la zona. Este trabajo examina la desorción térmica de dos suelos contaminados procedentes de Almadén bajo condiciones isotérmicas en atmósfera de N2, empleando calorimetría diferencial de barrido (DSC. La calorimetría se llevó a cabo a diferentes velocidades de calentamiento desde temperatura ambiente hasta 600 °C. Se determinaron las diferentes temperaturas de desorción de las especies de mercurio presentes en los suelos. Para determinar la cinética de reacción a partir de los datos de DSC se utilizaron los métodos de Friedman, Flynn-Wall-Ozawa y Coasts–Redfern. Además se calcularon las energías de activación y los factores pre-exponenciales para la desorción del mercurio.

  9. Material characterization and finite element simulations of aluminum alloy sheets during non-isothermal forming process

    Science.gov (United States)

    Zhang, Nan

    The utilization of more non-ferrous materials is one of the key factors to succeed out of the constantly increasing demand for lightweight vehicles in automotive sector. Aluminum-magnesium alloys have been identified as the most promising substitutions to the conventional steel without significant compromise in structural stiffness and strength. However, the conventional forming methods to deform the aluminum alloy sheets are either costly or insufficient in formability which limit the wide applications of aluminum alloy sheets. A recently proposed non-isothermal hot stamping approach, which is also referred as Hot Blank - Cold Die (HB-CD) stamping, aims at fitting the commercial grade aluminum alloy sheets, such as AA5XXX and AA7XXX, into high-volume and cost-effective production for automotive sector. In essence, HB-CD is a mutation of the conventional hot stamping approach for boron steel (22MnB5) which deforms the hot blank within the cold tool set. By elevating the operation temperature, the formability of aluminum alloy sheets can be significantly improved. Meanwhile, heating the blank only and deforming within the cold tool sets allow to reduce the energy and time consumed. This research work aims at conducting a comprehensive investigation of HB-CD with particular focuses on material characterization, constitutive modeling and coupled thermo-mechanical finite element simulations with validation. The material properties of AA5182-O, a popular commercial grade of aluminum alloy sheet in automotive sector, are obtained through isothermal tensile testing at temperatures from 25° to 300°, covering a quasi-static strain-rate range (0.001--0.1s-1). As the state-of-the-art non-contact strain measurement technique, digital image correlation (DIC) system is utilized to evaluate the stress-strain curves as well as to reveal the details of material deformation with full-field and multi-axis strain measurement. Material anisotropy is characterized by extracting the

  10. Modeling of the non isothermal and non isobaric transformations kinetics. Application to the kaolinite de-hydroxylation and to the tri-uranium octo-oxide reduction by hydrogen; Modelisation de la cinetique de transformations non isothermes et (ou) non isobares. Application a la deshydroxylation de la kaolinite et a la reduction de l'octooxyde de triuranium par l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, St

    2002-12-15

    The aim of this work is to be able to describe transformations, occurring when solids and gases are in non isothermal and non isobaric conditions, with kinetic models. A methodology has been used. Two essential processes have to be taken into account: the germination and the growth. The germs are supposed to be formed (at constant temperature and pressure) in the grains surface with a constant velocity by surface unit, (gamma), called germination surface frequency (number of germs.m{sup -2}.s{sup -1}. The growth velocity is characterized by a growth surface reactivity, (phi) (in mol.m{sup -2}.s{sup -1}). With an appropriate transformation model, it is possible to obtain the variations of (gamma) and (phi) in terms of the temperature and pressure which are then used in the calculation of the velocity in non isothermal and non isobaric conditions. In order to validate the developed method, two reactions have been studied. For the first one, the kaolinite de-hydroxylation, an anisotropic germination-growth model, where the step limiting the growth is a diffusion step, has been developed in order to explain the experimental kinetic curves. Nevertheless the velocity curves calculated from this model do not allow to describe the reaction for some temperature variations. This result shows the difficulty to precisely determine the germination surface frequency what induces an important approximation on the kinetic curves. The second reaction is the tri-uranium octo-oxide reduction by hydrogen. It has been shown that this reaction occurs according to three successive transformations. A kinetic model has been developed for each of these reactions considering germination as instantaneous. At last, in comparing this model with the experimental velocity curves, a very good agreement has been verified as well as for a temperature variation than for a hydrogen partial pressure change during the reaction. (O.M.)

  11. Reactive hydro- end chlorocarbons in the troposphere and lower stratosphere : sources, distributions, and chemical impact

    NARCIS (Netherlands)

    Scheeren, H.A.

    2003-01-01

    The work presented in this thesis focuses on measurements of chemical reactive C2 C7 non-methane hydrocarbons (NMHC) and C1 C2 chlorocarbons with atmospheric lifetimes of a few hours up to about a year. The group of reactive chlorocarbons includes the most abundant atmospheric species with large

  12. Chemical reactivity of hypervalent silicon compounds: The local ...

    Indian Academy of Sciences (India)

    Unknown

    at silicon. The object of the present work is to make use of the hard and soft acids and bases (HSAB) principle4–9 and of its local version,10–12 and density functional theory (DFT)13,14 to analyze the global behaviour of hypervalent silicon compounds, and the role of the silicon atom in the reactivity of tetra and pentacoor-.

  13. Chemical reactivity of the compressed noble gas atoms and their ...

    Indian Academy of Sciences (India)

    Attempts are made to gain insights into the effect of confinement of noble gas atoms on their various reactivity indices. Systems become harder, less polarizable and difficult to excite as the compression increases. Ionization also causes similar effects. A quantum fluid density functional technique is adopted in order to study ...

  14. Models for risk assessment of reactive chemicals in aquatic toxicology

    NARCIS (Netherlands)

    Freidig, Andreas Peter

    2000-01-01

    A quantitative structure property relationship (QSPR) for a,b-unsaturated carboxylates (mainly acrylates and methacrylates) was established in chapter 2. Chemical reaction rate constants were measured for 12 different chemicals with three different nucleophiles, namely H 2 O, OH - and glutathione

  15. Dynamic behavior of chemical reactivity indices in density functional ...

    Indian Academy of Sciences (India)

    Dynamic behaviors of chemical concepts in density functional theory such as frontier orbitals (HOMO/LUMO), chemical potential, hardness, and electrophilicity index have been investigated in this work in the context of Bohn-Oppenheimer quantum molecular dynamics in association with molecular conformation changes.

  16. Synthesis and Non-isothermal Carbothermic Reduction of FeTiO3-Fe2O3 Solid Solution Systems

    Science.gov (United States)

    Liu, Yiran; Zhang, Jianliang; Xing, Xiangdong; Liu, Zhengjian; Liu, Xingle; Li, Naiyao; Shen, Yansong

    2017-10-01

    To investigate the carbothermic reduction behaviors of xFeTiO3·(1 - x)Fe2O3 solid solutions, the solid solutions with different x values were synthesized and used in the corresponding reactions. With an increase in x, the temperature pertaining to the onset of carbothermic reduction increased, while the rate of reduction of the solid solutions, α, decreased. The lattice parameters calculated from XRD patterns indicated that the solid solution with a higher x led to a larger lattice distortion. The non-isothermal kinetics were calculated, and an average activation energy E value of 3.0 × 102 kJ/mol was obtained.

  17. Approximations to the Non-Isothermal Distributed Activation Energy Model for Biomass Pyrolysis Using the Rayleigh Distribution

    Directory of Open Access Journals (Sweden)

    Dhaundiyal Alok

    2017-09-01

    Full Text Available This paper deals with the influence of some parameters relevant to biomass pyrolysis on the numerical solutions of the nonisothermal nth order distributed activation energy model using the Rayleigh distribution. Investigated parameters are the integral upper limit, the frequency factor, the heating rate, the reaction order and the scale parameters of the Rayleigh distribution. The influence of these parameters has been considered for the determination of the kinetic parameters of the non-isothermal nth order Rayleigh distribution from the experimentally derived thermoanalytical data of biomass pyrolysis.

  18. Optimal experimental design for improving the estimation of growth parameters of Lactobacillus viridescens from data under non-isothermal conditions.

    Science.gov (United States)

    Longhi, Daniel Angelo; Martins, Wiaslan Figueiredo; da Silva, Nathália Buss; Carciofi, Bruno Augusto Mattar; de Aragão, Gláucia Maria Falcão; Laurindo, João Borges

    2017-01-02

    In predictive microbiology, the model parameters have been estimated using the sequential two-step modeling (TSM) approach, in which primary models are fitted to the microbial growth data, and then secondary models are fitted to the primary model parameters to represent their dependence with the environmental variables (e.g., temperature). The Optimal Experimental Design (OED) approach allows reducing the experimental workload and costs, and the improvement of model identifiability because primary and secondary models are fitted simultaneously from non-isothermal data. Lactobacillus viridescens was selected to this study because it is a lactic acid bacterium of great interest to meat products preservation. The objectives of this study were to estimate the growth parameters of L. viridescens in culture medium from TSM and OED approaches and to evaluate both the number of experimental data and the time needed in each approach and the confidence intervals of the model parameters. Experimental data for estimating the model parameters with TSM approach were obtained at six temperatures (total experimental time of 3540h and 196 experimental data of microbial growth). Data for OED approach were obtained from four optimal non-isothermal profiles (total experimental time of 588h and 60 experimental data of microbial growth), two profiles with increasing temperatures (IT) and two with decreasing temperatures (DT). The Baranyi and Roberts primary model and the square root secondary model were used to describe the microbial growth, in which the parameters b and Tmin (±95% confidence interval) were estimated from the experimental data. The parameters obtained from TSM approach were b=0.0290 (±0.0020) [1/(h(0.5)°C)] and Tmin=-1.33 (±1.26) [°C], with R(2)=0.986 and RMSE=0.581, and the parameters obtained with the OED approach were b=0.0316 (±0.0013) [1/(h(0.5)°C)] and Tmin=-0.24 (±0.55) [°C], with R(2)=0.990 and RMSE=0.436. The parameters obtained from OED approach

  19. A Conceptual Framework for Predicting the Toxicity of Reactive Chemicals: Modeling Soft Electrophilicity

    Science.gov (United States)

    Although the literature is replete with QSAR models developed for many toxic effects caused by reversible chemical interactions, the development of QSARs for the toxic effects of reactive chemicals lacks a consistent approach. While limitations exit, an appropriate starting-point...

  20. Phase rule calculations and the thermodynamics of reactive systems under chemical equilibrium

    Directory of Open Access Journals (Sweden)

    PLATT G. M.

    1999-01-01

    Full Text Available In this paper, we examine the resolution of some phase rule problems within the context of multiple chemical equilibrium reactions, using cubic equations of state and an activity coefficient model. Bubble and dew reactive surfaces, reactive azeotropic loci and reactive critical loci are generated and presented in graphical form. Also isobaric bubble and dew reactive enthalpy loci, which may be useful in the modeling of reactive distillation operations, are depicted. All the formalism here employed is developed within the coordinate transformation of Ung and Doherty, which is appropriate for equilibrium reactive or multireactive systems. The major contribution of this work is the determination of critical loci for reactive or multireactive equilibrium systems. Since it is known that for some class of chemical reactions the kinetics and product distribution exhibit high sensitivity to pressure near criticality, the present study may be useful as a predicting tool in these cases if the chemical equilibrium condition is not too far from the real phenomenon.

  1. Investigation of non-isothermal electron effects on the dust acoustic waves in four components dusty plasma

    Science.gov (United States)

    Nazari-Golshan, A.; Nourazar, S. S.; Parvin, P.; Ghafoori-Fard, H.

    2014-01-01

    The time fractional modified KdV, the so-called TFMKdV equation is solved to study the nonlinear propagation of the dust acoustic (DA) solitary waves in un-magnetized four components dusty plasma. This plasma consists of positively charged warm adiabatic dust, negatively charged cold dust, non-isothermal electrons and Maxwellian ions. The TFMKdV equation is derived by using semi-inverse and Agrawal's method and solved by the Laplace Adomian decomposition method (LADM). The effects of the time fractional order ( β), the ratio of dust to ion temperature ( δ d ), the time ( τ), the mass and charge ratio ( α), the non-isothermal parameter ( γ) and wave velocity ( v) on the DA solitary wave are studied. Our results show that the variations of the amplitude of DA solitary wave versus ( γ) are in agreement with the results obtained previously. Moreover, the time fractional order plays a role of higher order perturbation in modulating the soliton shape. The achievements of this research for the DA solitary waves may be applicable in space plasma environments and laboratory plasmas.

  2. Non-isothermal crystallization kinetics of As{sub 30}Te{sub 60}Ga{sub 10} glass

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Mansour; Abd-Elnaiem, Alaa M.; Abdel-Rahim, M.A.; Hafiz, M.M. [Assiut University, Physics Department, Faculty of Science, Assiut (Egypt); Hassan, R.M. [Assiut University, Physics Department, Faculty of Science, Assiut (Egypt); Aden University, Physics Department, Faculty of Education-Zingiber, Aden (Yemen)

    2017-08-15

    The crystallization study under non-isothermal conditions of As{sub 30}Te{sub 60}Ga{sub 10} glass was investigated. The studied composition was synthesized by melt-quenching technique and characterized by different techniques such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The XRD analysis revealed that the as-prepared and annealed bulk glass of As{sub 30}Te{sub 60}Ga{sub 10} exhibit the amorphous, and polycrystalline nature, respectively. The DSC results showed that the heating rate affects the characteristic temperatures, for instance, the glass transition, onset, and peak crystallization temperatures. Furthermore, some thermal analysis methods such as the Kissinger and Matusita et al., approximations were employed to determine the crystallization parameters: for example Avrami exponent and the activation energies for glass transition and crystallization process. In addition, we have compared the experimental DSC data with the calculated ones based on the Johnson-Mehl-Avrami (JMA) and Sestak-Berggren SB(M,N) models. The results indicated that the SB(M,N) model is more suitable for describing the non-isothermal crystallization kinetics of the investigated composition. (orig.)

  3. EFFECT OF POLY (N- VINYPYRROLIDONE ON THE NON-ISOTHERMAL CRYSTALLIZATION KINETICS AND VISCOELASTIC PROPERTIES OF PVDF FILMS

    Directory of Open Access Journals (Sweden)

    A. Mashak

    Full Text Available Abstract Poly(vinylidene fluoride (PVDF and PVDF blends with various molecular weights of poly (N- vinylpyrrolidone (PVP films were prepared in dimethyl formamide through the solution casting method. Non-isothermal melt crystallization studies of PVDF films were carried out by cooling the molten samples at different temperatures using differential scanning calorimetry (DSC. The obtained films have been characterized by dynamic mechanical thermal analysis (DMTA. Crystallization kinetics of PVDF films were successfully described by the Jeziorney, Mo and Ziabicki models. The Ozawa equation was found to be invalid for describing the crystallization kinetics. Kinetic parameters such as t1/2, Zc and F(T indicated that the crystallization rate decreased for PVDF/PVP films as compared to neat PVDF films and was affected by the molecular weight of PVP. The results based on Ziabicki's model revealed that the addition of PVP decreased the ability of PVDF to crystallize under non-isothermal melt crystallization conditions. The activation energy was calculated through Friedman and advanced isoconversional methods. Results showed that the addition of PVP to PVDF films caused an increase in activation energy. By comparing DMTA results of PVDF/PVP blends with neat PVDF films, it could be concluded that blending PVDF with PVP caused an increase in the glass transition temperature (Tg while the storage modulus was decreased.

  4. The effects of non-isothermal deformation on martensitic transformation in 22MnB5 steel

    Energy Technology Data Exchange (ETDEWEB)

    Naderi, M. [Department of Materials Science and Engineering, Faculty of Engineering, Arak University, Shariati Street, Arak (Iran, Islamic Republic of)], E-mail: malek.naderi@iehk.rwth-aachen.de; Saeed-Akbari, A.; Bleck, W. [Department of Ferrous Metallurgy, RWTH Aachen University, Aachen (Germany)

    2008-07-25

    In the present paper, the effects of process parameters on phase transformations during non-isothermal deformations are described and discussed. Non-isothermal high temperature compressive deformations were conducted on 22MnB5 boron steel by using deformation dilatometry. Cylindrical samples were uniaxially deformed at different strain rates ranging from 0.05 to 1.0 s{sup -1} to a maximum compressive strain of 50%. Qualitative and quantitative investigations were carried out using surface hardness mapping data as well as dilatation curves. It was observed that a higher initial deformation temperatures resulted in a higher martensite fraction of the microstructure, while a variation in the martensite start temperature was negligible. Another conclusion was that by applying larger amounts of strain as well as higher force levels, not only the martensite start temperature, but also the amount of martensite was reduced. Moreover, it was concluded that using surface hardness mapping technique and dilatometry experiments were very reliable methods to quantify and qualify the coexisting phases.

  5. Kinetic and safety parameters analysis for 1,1,-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane in isothermal and non-isothermal conditions.

    Science.gov (United States)

    Tseng, Jo-Ming; Lin, Chun-Ping; Huang, Sheng-Tien; Hsu, Johnson

    2011-09-15

    Over the past 30 years, the field of thermal analysis of organic peroxides has become an important issue in chemical engineering departments, safety departments, and in companies working with polymerization, petrifaction process, and so on. The contributions of thermal analysis to the evaluation and prediction of the runaway reactions have been important for decreasing or preventing a hazard, such as fire or explosion accident. This study was carried out using differential scanning calorimetry (DSC) to evaluate the kinetic and safety parameters in isothermal and non-isothermal conditions, for instance, temperature of no return (T(NR)), self accelerating decomposition temperature (SADT), time to maximum rate (TMR), activation energy (E(a)), frequency factor (A), reaction order (n), and reaction heat (ΔH), in terms of the hazardous material of 1,1,-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane (TMCH) 88 mass%. On the basis of this study, we demonstrated that TMCH 88 mass% must be well controlled in the manufacturing process due to the unstable structure of O-O, which releases a great quantity of heat, higher than 1300 J/g under decomposition. Results of this study could contribute to the relevant plants adopting TMCH 88mass% in a process, in order to prevent a fire or explosion accident from happening. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Mechano-chemical oscillations and waves in reactive gels

    Science.gov (United States)

    Yashin, Victor V.; Kuksenok, Olga; Dayal, Pratyush; Balazs, Anna C.

    2012-06-01

    We review advances in a new area of interdisciplinary research that concerns phenomena arising from inherent coupling between non-linear chemical dynamics and mechanics. This coupling provides a route for chemical-to-mechanical energy transduction, which enables materials to exhibit self-sustained oscillations and/or waves in both concentration and deformation fields. We focus on synthetic polymer gels, where the chemo-mechanical behavior can be engineered into the material. We provide a brief review of experimental observations on several types of chemo-mechanical oscillations in gels. Then, we discuss methods used to theoretically and computationally model self-oscillating polymer gels. The rest of the paper is devoted to describing results of theoretical and computational modeling of gels that undergo the oscillatory Belousov-Zhabotinsky (BZ) reaction. We discuss a remarkable form of mechano-chemical transduction in these materials, where the application of an applied force or mechanical contact can drive the system to switch between different dynamical behavior, or alter the mechanical properties of the material. Finally, we discuss ways in which photosensitive BZ gels could be used to fabricate biomimetic self-propelled objects. In particular, we describe how non-uniform illumination can be used to direct the movement of BZ gel ‘worms’ along complex paths, guiding them to bend, reorient and turn.

  7. Importance of asparagine on the conformational stability and chemical reactivity of selected anti-inflammatory peptides

    Energy Technology Data Exchange (ETDEWEB)

    Soriano-Correa, Catalina, E-mail: csorico@comunidad.unam.mx [Química Computacional, Facultad de Estudios Superiores (FES)-Zaragoza, Universidad Nacional Autónoma de México (UNAM), Iztapalapa, C.P. 09230 México, D.F. (Mexico); Barrientos-Salcedo, Carolina [Laboratorio de Química Médica y Quimiogenómica, Facultad de Bioanálisis Campus Veracruz-Boca del Río, Universidad Veracruzana, C.P. 91700 Veracruz (Mexico); Campos-Fernández, Linda; Alvarado-Salazar, Andres [Química Computacional, Facultad de Estudios Superiores (FES)-Zaragoza, Universidad Nacional Autónoma de México (UNAM), Iztapalapa, C.P. 09230 México, D.F. (Mexico); Esquivel, Rodolfo O. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa (UAM-Iztapalapa), C.P. 09340 México, D.F. (Mexico)

    2015-08-18

    Highlights: • Asparagine plays an important role to anti-inflammatory effect of peptides. • The electron-donor substituent groups favor the formation of the hydrogen bonds, which contribute in the structural stability of peptides. • Chemical reactivity and the physicochemical features are crucial in the biological functions of peptides. - Abstract: Inflammatory response events are initiated by a complex series of molecular reactions that generate chemical intermediaries. The structure and properties of peptides and proteins are determined by the charge distribution of their side chains, which play an essential role in its electronic structure and physicochemical properties, hence on its biological functionality. The aim of this study was to analyze the effect of changing one central amino acid, such as substituting asparagine for aspartic acid, from Cys–Asn–Ser in aqueous solution, by assessing the conformational stability, physicochemical properties, chemical reactivity and their relationship with anti-inflammatory activity; employing quantum-chemical descriptors at the M06-2X/6-311+G(d,p) level. Our results suggest that asparagine plays a more critical role than aspartic acid in the structural stability, physicochemical features, and chemical reactivity of these tripeptides. Substituent groups in the side chain cause significant changes on the conformational stability and chemical reactivity, and consequently on their anti-inflammatory activity.

  8. Mesoscopic non-equilibrium thermodynamics of non-isothermal reaction-diffusion.

    Science.gov (United States)

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

    2010-10-21

    We show how the law of mass action can be derived from a thermodynamic basis, in the presence of temperature gradients, chemical potential gradients and hydrodynamic flow. The solution gives the law of mass action for the forward and the reverse contributions to the net chemical reaction. In addition we derive the fluctuation-dissipation theorem for the fluctuating contributions to the reaction rate, heat flux and mass fluxes. All these results arise without any other assumptions than those which are common in mesoscopic non-equilibrium thermodynamics; namely quasi-stationary transport across a high activation energy barrier, and local equilibrium along the reaction coordinate. Arrhenius-type behaviour of the kinetic coefficients is recovered. The thermal conductivity, Soret coefficient and diffusivity are significantly influenced by the presence of a chemical reaction. We thus demonstrate how chemical reactions can be fully reconciled with non-equilibrium thermodynamics.

  9. Effect of mechanical activation on structure changes and reactivity in further chemical modification of lignin.

    Science.gov (United States)

    Zhao, Xiaohong; Zhang, Yanjuan; Hu, Huayu; Huang, Zuqiang; Yang, Mei; Chen, Dong; Huang, Kai; Huang, Aimin; Qin, Xingzhen; Feng, Zhenfei

    2016-10-01

    Lignin was treated by mechanical activation (MA) in a customized stirring ball mill, and the structure and reactivity in further esterification were studied. The chemical structure and morphology of MA-treated lignin and the esterified products were analyzed by chemical analysis combined with UV/vis spectrometer, FTIR,NMR, SEM and particle size analyzer. The results showed that MA contributed to the increase of aliphatic hydroxyl, phenolic hydroxyl, carbonyl and carboxyl groups but the decrease of methoxyl groups. Moreover, MA led to the decrease of particle size and the increase of specific surface area and roughness of surface in lignin. The reactivity of lignin was enhanced significantly for the increase of hydroxyl content and the improvement of mass transfer in chemical reaction caused by the changes of molecular structure and morphological structure. The process of MA is green and simple, and is an effective method for enhancing the reactivity of lignin. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Steam chemical reactivity of plasma-sprayed beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, R.A.; Pawelko, R.J.; Smolik, G.R. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Castro, R.G. [Los Alamos National Lab., NM (United States)

    1998-07-01

    Plasma-spraying with the potential for in-situ repair makes beryllium a primary candidate for plasma facing and structural components in experimental magnetic fusion machines. Deposits with good thermal conductivity and resistance to thermal cycling have been produced with low pressure plasma-spraying (LPPS). A concern during a potential accident with steam ingress is the amount of hydrogen produced by the reactions of steam with hot components. In this study the authors measure the reaction rates of various deposits produced by LPPS with steam from 350 C to above 1,000 C. They correlate these reaction rates with measurements of density, open porosity and BET surface areas. They find the reactivity to be largely dependent upon effective surface area. Promising results were obtained below 600 C from a 94% theoretical dense (TD) deposit with a BET specific surface area of 0.085 m{sup 2}/g. Although reaction rates were higher than those for dense consolidated beryllium they were substantially lower, i.e., about two orders of magnitude, than those obtained from previously tested lower density plasma-sprayed deposits.

  11. Modeling turbulence structure. Chemical kinetics interaction in turbulent reactive flows

    Energy Technology Data Exchange (ETDEWEB)

    Magnussen, B.F. [The Norwegian Univ. of Science and Technology, Trondheim (Norway)

    1997-12-31

    The challenge of the mathematical modelling is to transfer basic physical knowledge into a mathematical formulation such that this knowledge can be utilized in computational simulation of practical problems. The combustion phenomena can be subdivided into a large set of interconnected phenomena like flow, turbulence, thermodynamics, chemical kinetics, radiation, extinction, ignition etc. Combustion in one application differs from combustion in another area by the relative importance of the various phenomena. The difference in fuel, geometry and operational conditions often causes the differences. The computer offers the opportunity to treat the individual phenomena and their interactions by models with wide operational domains. The relative magnitude of the various phenomena therefore becomes the consequence of operational conditions and geometry and need not to be specified on the basis of experience for the given problem. In mathematical modelling of turbulent combustion, one of the big challenges is how to treat the interaction between the chemical reactions and the fluid flow i.e. the turbulence. Different scientists adhere to different concepts like the laminar flamelet approach, the pdf approach of the Eddy Dissipation Concept. Each of these approaches offers different opportunities and problems. All these models are based on a sound physical basis, however none of these have general validity in taking into consideration all detail of the physical chemical interaction. The merits of the models can only be judged by their ability to reproduce physical reality and consequences of operational and geometric conditions in a combustion system. The presentation demonstrates and discusses the development of a coherent combustion technology for energy conversion and safety based on the Eddy Dissipation Concept by Magnussen. (author) 30 refs.

  12. Chemical Modification on Reactive Dye Adsorption Capacity of Castor Seeds

    Directory of Open Access Journals (Sweden)

    V. Dharmalingam

    2011-01-01

    Full Text Available Abstract: The roles played by four major functional groups (amine, carboxyl, azo, hydroxyl groups in the biomass of castor seeds in adsorption of seven dyes were investigated. These functional groups in castor seeds were chemically modified individually to determine their contribution to the adsorption of ionic dyes. The dyes used were remazol red B, procino yellow, fast green FCF, brilliant cresyl blue, methylene blue, neutral red, red-141. It was found that hydroxyl group inhibited the adsorption of anionic dyes but it was major functional group in the adsorption of cationic dyes, hydroxyl group was important functional group in the adsorption of all seven dyes and the effect of methylation of amino group was not significant on the adsorption of seven dyes.

  13. Thermal decomposition of wood in oxidizing atmosphere: A kinetic study from non-isothermal TG experiments

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, T.; Rodriguez-Maroto, F.G.; Rodriguez, J.J. (Univ. of Malaga (Spain))

    1991-11-22

    The kinetics of thermal decomposition of four wood species in oxygen-bearing atmospheres of 5, 10 and 20% molar O{sub 2} concentrations have been studied from temperature-programmed experiments carried out at 5, 10 and 20 K min{sup {minus}1} heating rate. Devolatilization as well as combustion of the reamining solid have been considered to analyze the weight loss curves. The homogeneous volume reaction (VR) model has been used to describe devolatilization, whereas for solid combustion the grain model has been also checked. A two-stage approach has been used to fit the conversion-time curves and to derive the corresponding apparent kinetic parameters. The VR/VR (pyrolysis/combustion) combination provided a better description of the experimental {alpha}-t curves than the VR/grain combination. Holm oak and cork oak showed very close reactivities, whereas some differences were observed for aleppo pine and eucalyptus. 6 figs. 8 tabs., 20 refs.

  14. Mixed convection boundary layer flows of a non-Newtonian Jeffrey’s fluid from a non-isothermal wedge

    Directory of Open Access Journals (Sweden)

    S. Abdul Gaffar

    2017-06-01

    Full Text Available This article presents the nonlinear, steady state mixed convection boundary layer flow, heat and mass transfer of an incompressible non-Newtonian Jeffrey’s fluid past a non-isothermal wedge. The transformed conservation equations are solved numerically subject to physically appropriate boundary conditions using a versatile, implicit finite-difference Keller box technique. The influence of a number of emerging non-dimensional parameters, namely Deborah number (De, ratio of relaxation to retardation times (λ, pressure gradient parameter (m, Buoyancy ratio parameter (N, mixed convection parameter (λ1, radiation parameter (F and heat generation/absorption parameter (Δ on velocity, temperature and concentration evolution in the boundary layer regime is examined in detail. Also, the effects of these parameters on surface heat transfer rate, mass transfer rate and local skin friction are investigated.

  15. Morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate)/poly(ethylene-co-methacrylic acid) blends

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J.-W. [Department of Styling and Cosmetology, Tainan University of Technology, 529 Chung Cheng Rd., Yung Kang City 710, Taiwan (China)], E-mail: jw.huang@msa.hinet.net; Wen, Y.-L. [Department of Nursing, Meiho Institute of Technology, 23 Ping Kuang Rd., Neipu Hsiang, Pingtung 912, Taiwan (China); Department of Resources Engineering, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China); Kang, C.-C. [R and D Center, Hi-End Polymer Film Co., Ltd. 15-1 Sin Jhong Rd., Sin Ying City 730, Taiwan (China); Yeh, M.-Y. [Department of Chemistry, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China); Sustainable Environment Research Centre, National Cheng Kung University, Taiwan (China); Wen, S.-B. [Department of Nursing, Meiho Institute of Technology, 23 Ping Kuang Rd., Neipu Hsiang, Pingtung 912, Taiwan (China); Department of Resources Engineering, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China)

    2007-12-15

    The morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate) (PBT) and poly(ethylene-co-methacrylic acid) (PEMA) blends were studied with scanning electron microscopy, X-ray diffraction and differential scanning calorimetry (DSC). PEMA forms immiscible, yet compatible, blends with PBT. Subsequent DSC scans on melt-crystallized samples exhibited two melting endotherms (T{sub mI} and T{sub mII}). The presence of PEMA would facilitate the recrystallization during heating scan and retard PBT molecular chains to form a perfect crystal in cooling crystallization. The dispersion phases of molten PEMA acts as nucleating agents to enhance the crystallization rate of PBT. The solidified PBT could act as nucleating agents to enhance the crystallization of PEMA, but also retard the molecular mobility to reduce crystallization rate. The U* and K{sub g} of Hoffman-Lauritzen theory were also determined by Vyazovkin's methods to support the interpretation.

  16. Interpretation and evaluation of monitoring results for main pipelines hydraulic pressure testing under non-isothermal conditions

    Science.gov (United States)

    Kraus, Ju. A.; Ivanov, R. N.; Grinevich, V. A.; Pakhotin, A. N.

    2017-08-01

    The paper examines hydraulic pressure testing of main oil pipelines. The research objective is to identify and describe the characteristic features of pressure changes in pressure testing of the main pipeline, caused by temperature changes. The notions on the interpretation and evaluation of the results for pipeline pressure testing under non-isothermal conditions are given, the number of pressure sampling points and temperature information being limited; and considering the elevation difference along the length of the test section (where applicable). A formula for calculating the fresh water volumetric expansion coefficient correlation with temperature and pressure is proposed. A method for interpreting the hydraulic pressure testing results is developed, considering the parameters spread effect on the coefficients of the volumetric expansion and the modulus of elasticity for the test fluid, as well as the coefficients of linear expansion and Young's modulus for pipe steel. The application of the method allows to monitor the hydraulic pressure testing for main oil pipelines.

  17. Impact of thermal radiation on MHD slip flow of a ferrofluid over a non-isothermal wedge

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, A.M.

    2017-01-15

    This article is concerned with the problem of magnetohydrodynamic (MHD) mixed convection flow of Cobalt-kerosene ferrofluid adjacent a non-isothermal wedge under the influence of thermal radiation and partial slip. Such type of problems are posed by electric generators and biomedical enforcement. The governing equations are solved using the Thomas algorithm with finite-difference type and solutions for a wide range of magnet parameter are presented. It is found that local Nusselt number manifests a considerable diminishing for magnetic parameter and magnifies intensively in case of slip factor, thermal radiation and surface temperature parameters. Further, the skin friction coefficient visualizes a sufficient enhancement for the parameters thermal radiation, surface temperature and magnetic field, but a huge reduction is recorded by promoting the slip factor.

  18. Study of Non-Isothermal Crystallization Kinetics of Biodegradable Poly(ethylene adipate/SiO2 Nanocomposites

    Directory of Open Access Journals (Sweden)

    M. R. Memarzadeh

    2013-09-01

    Full Text Available Poly(ethylene adipte and poly(ethylene adipate/silica nanocomposite (PEAd/SiO2 containing 3 wt. % SiO2  were prepared by an in situ method. The examinations on the non-isothermal crystallization kinetic behavior have been conducted by means of differential scanning calorimeter (DSC. The Avrami, Ozawa, and combined Avrami and Ozawa equations were applied to describe the crystallization kinetics and to determine the crystallization parameters of the prepared PEAd/SiO2 nanocomposites. It is found that the inclusion of the silica nanoparticles can accelerate the nucleation rate due to heterogeneous nucleation effect of silica on the polymer matrix. According to the obtained results, the combined Avrami and Ozawa equation shown that the better model for examination of this system.

  19. Withdrawal and drainage of thin film flow of a generalized Oldroyd-B fluid on non-isothermal cylindrical surfaces

    Directory of Open Access Journals (Sweden)

    Saif Ullah

    2015-12-01

    Full Text Available This investigation deals with analytical solutions of thin film flow for withdrawal and drainage of an incompressible generalized Oldroyd-B fluid on a vertical cylinder under the influence of non-isothermal effects. The derived solutions are presented under series form for velocity profile, temperature distribution, volume flux, average film velocity and shear stress in both cases. These solutions satisfy both the governing equations and all imposed initial and boundary conditions. The corresponding exact solutions for Newtonian fluid are also obtained as a special case of our derived solutions. Moreover, solutions for generalized Maxwell fluid and Power Law model, performing the same motion, can be obtained as limiting cases of our general solutions. The influence of pertinent parameters on the fluid motion is also underlined by graphical illustration.

  20. Study on the non-isothermal curing kinetics of a polyfurfuryl alcohol bioresin by DSC using different amounts of catalyst

    DEFF Research Database (Denmark)

    Dominguez Toribio, Juan Carlos; Grivel, Jean-Claude; Madsen, Bo

    2012-01-01

    The curing kinetics of a biomass-based polyfurfuryl alcohol resin with three different amounts of catalyst was studied by DSC non-isothermal measurements using seven heating rates. The change of the activation energy of the curing process was obtained by the isoconversional methods of Kissinger...... and gelling of the resin which leads to a constrained mobility of the polymer chains; and a final stage, where the activation energy decreases more rapidly due to the formation of a rigid molecular network that restricts diffusion processes. Altogether, the obtained knowledge of the curing kinetics will form...... a valuable contribution to the design of improved cure cycles for manufacturing of composite materials with a polyfurfuryl alcohol matrix....

  1. Kinetic analysis for non-isothermal decomposition of un-irradiated and gamma-irradiated anhydrous cadmium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Culas, S.; Samuel, J. [Mar Ivanios College, Kerala (India). Dept. of Chemistry

    2014-04-01

    The thermal decomposition of untreated and γ-irradiated samples of anhydrous cadmium nitrate was performed under non-isothermal conditions at different heating rates (5, 10, 15 and 20 C min{sup -1}). The results showed that the decomposition proceeds in one major step with the formation of cadmium oxide as solid residue. The data were analysed by using both isoconversional and non-isoconversional methods. The activation energy was calculated by various model-free isoconversional methods: Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman (FR) methods. Irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy decreases on irradiation. The appropriate conversion model for the thermal decomposition process selected by means of the master-plot method agrees with phase boundary reaction with spherical symmetry (R3 mechanism) for both untreated and irradiated salts at all heating rates. (orig.)

  2. A study by non-isothermal thermal methods of spruce wood bark materialss after their application for dye removal

    Directory of Open Access Journals (Sweden)

    VIORICA DULMAN

    2005-11-01

    Full Text Available This paper deals with a study of some materials obtained from spruce bark (Picea abies, Romania, after retention of some dyes frequently used in dyeing processes in the textile industry and waste water treatment. These materials obtained by dye retention exhibit a particular thermal behavior which is different from that of the blank sample (spruce bark. The characteristic temperatures, weight losses, the residue remaining after thermo-oxidative degradation, as well as the activation energies of the significant thermo-destruction stages, estimated from non-isothermal thermogravimetric data, together with the thermal quantities calculated from DTAdata support the conclusion presented in a previous study on dye retention from aqueous solution. The obtained results made evident that, under optimal retention conditions, spruce bark shows the highest retention capacity for the Basic Blue dye, followed by Direct Brown 95 and Direct Brown 2.

  3. Non isothermal decomposition of lanthanum titanates precursors prepared by sol gel process: A kinetic and thermodynamic study

    Energy Technology Data Exchange (ETDEWEB)

    Bassil, S. [Université Lyon 1, CNRS, UMR 5256, IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon, 2 avenue Albert Einstein, F-69626 Villeurbanne (France); Kaddouri, A., E-mail: akim.kaddouri@ircelyon.univ-lyon1.fr [Université Lyon 1, CNRS, UMR 5256, IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon, 2 avenue Albert Einstein, F-69626 Villeurbanne (France); Béguin, B.; Gélin, P. [Université Lyon 1, CNRS, UMR 5256, IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon, 2 avenue Albert Einstein, F-69626 Villeurbanne (France)

    2013-09-10

    Highlights: ► Metal-propionates is a most promising route for the preparation of La{sub 0.8}Sr{sub 0.2}TiO{sub 3+δ} (LST) at a temperature substantially lower than that used for the preparation of the same solid by traditional methods. ► Activation energy and isothermal thermodynamic parameters calculated for the decomposition process are close to those observed for metal organic compounds. ► Sol gel-prepared LST presented low propensity to coke deposition and high stability with time during the critical long term exposure to methane and steam at high temperatures. - Abstract: The single phase La{sub 0.8}Sr{sub 0.2}TiO{sub 3+δ} was prepared via the sol gel process using propionic acid. Kinetics of the thermal decomposition of the precursors has been studied using differential thermogravimetry under non-isothermal conditions in different atmospheres (air and helium). Non isothermal kinetic (A and ΔE) and thermodynamic parameters (ΔH, ΔS and Cp) were determined using different heating rates. La{sub 2}O{sub 3}, SrO and TiO{sub 2} products crystallized at temperatures of ca. 730, 960 and 470 °C respectively while pure La{sub 0.8}Sr{sub 0.2}TiO{sub 3+δ} phase was obtained at 1200 °C, temperature substantially lower than that used for the preparation of La{sub 0.8}Sr{sub 0.2}TiO{sub 3+δ} by conventional solid state method. Precursors and/or final solids were characterized by thermogravimetric analysis (TG), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, diffuse reflectance ultraviolet–visible spectroscopy (DR-UV–vis) and methane steam reforming under water deficient conditions.

  4. A reactive BGK-type model: influence of elastic collisions and chemical interactions

    OpenAIRE

    Monaco, Roberto; Pandolfi Bianchi, M.; Soares, A.J.

    2005-01-01

    A BGK‐type model for a reactive multicomponent gas undergoing chemical bimolecular reactions is here presented. The mathematical and physical consistency of the model is stated in detail. The relaxation process towards local Maxwellians, depending on mass and numerical densities of each species, as well as on common mean velocity and temperature, is investigated with respect to chemical equilibrium. Such a trend is numerically tested within the hydrogen‐air reaction mechanism.

  5. Morphology and non-isothermal crystallization kinetics of CuInS{sub 2} nanocrystals synthesized by solvo-thermal method

    Energy Technology Data Exchange (ETDEWEB)

    Majeed Khan, M.A., E-mail: majeed_phys@yahoo.co.in [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Kumar, Sushil [Department of Physics, Chaudhary Devi Lal University, Sirsa 125055 (India); Alsalhi, M.S. [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Department of Physics and Astronomy, King Saud University, Riyadh 11451 (Saudi Arabia); Ahamed, Maqusood [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Alhoshan, Mansour [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Chemical Engineering Department, King Saud University, Riyadh 11451 (Saudi Arabia); Alrokayan, Salman A. [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Ahamad, Tansir [Department of Chemistry, King Saud University, Riyadh 11451 (Saudi Arabia)

    2012-03-15

    Nanocrystals of copper indium disulphide (CuInS{sub 2}) were synthesized by a solvo-thermal method. The structure, morphology and non-isothermal crystallization kinetic behavior of samples were investigated using X-ray diffraction, field emission scanning electron microscopy, field emission transmission electron microscopy, thermogravimetric analysis and differential thermal analysis techniques. Non-isothermal measurements at different heating rates were carried out and the crystallization kinetics of samples were analyzed using the most reliable non-isothermal kinetic methods. The kinetic parameters such as glass transition temperature, thermal stability, activation energy, Avrami exponent etc. were evaluated. - Highlights: Black-Right-Pointing-Pointer CuInS{sub 2} nanocrystals have scientific and technological importance. Black-Right-Pointing-Pointer Samples have been prepared by solvo-thermal method. Black-Right-Pointing-Pointer Synthesized samples exhibit excellent morphology and thermal properties. Black-Right-Pointing-Pointer Investigated properties may be utilized in design and fabrication of solar cell devices.

  6. Non isothermal kinetic study of the aluminium titanate formation in alumina-titania mixtures

    Directory of Open Access Journals (Sweden)

    N. M. Rendtorff

    2014-09-01

    Full Text Available Aluminum titanate (Al2TiO5 is a high refractoriness material with excellent thermal shock resistance. Hence it is suitable for several applications at elevated temperatures where insulation and thermal shock resistance are required. Such as components of internal combustion engines, exhaust port liners, metallurgy, and thermal barriers. The thermal instability of Al2TiO5 at high temperature is another characteristic of this material that has been studied and controlled by the incorporation of several additives. The Al2TiO5 formation from pure oxides presents an endothermic peak in the differential thermal analysis (DTA. The thermodynamic temperature is 1280 ºC. But experimentally, as in every other DTA experiment, these peaks strongly depend on the heating rate: this fact has been extensively employed for the kinetic study of transformation processes and the mechanism determination of chemical reactions. Both activation energies (Ea and nucleation rates can be obtained from these experiments. The present work reports the formation Ea of Al2TiO5 prepared from pure oxides at air atmosphere by the Kissinger DTA based methods. Previously the particle size distribution of the starting powders together with X-ray diffraction analysis of the starting powders and the resulting materials was carried out. The properties of the Al2TiO5 formation were grouped into two groups corresponding to the low and high heating rates, below and over 5 K/min. Ea values were obtained after the Avrami (n constant evidenced that the crystallization mechanism is strongly related to the heating rate, even in the wide range studied which includes the technological ones(0.5-40 K/min.

  7. Fluid Creep Effects on Near-Wall Solute Transport for Non-Isothermal Ampoules

    Science.gov (United States)

    Papadopoulos, Dimitrios; Rosner, Daniel E.

    1996-01-01

    There is a growing practical and theoretical interest in developing accurate macroscopic modelling for flows arising in chemical or physical vapor transport (VT) crystal growth experiments, including those conducted in reduced gravity environments. Rosner was the first person to point out that previously neglected rarefield gas dynamics phenomena (Stefan and bouyancy-driven flows) become rather important sources of convection. In particular, the combination of rarefaction and strong gradients of temperature (and/or concentration) tangential to the side-walls of the ampoule induces convective flows known as thermal (and concentration) 'creep' respectively. His order-of-magnitude estimates revealed that thermal creep effects can be non-negligible even at normal gravitational levels. On the macroscopic level, the bulk fluid mechanics can be adequately described by the familiar macroscopic equations as long as the boundary conditions are modified to account for the integrated effect of kinetic boundary layers adjacent to solid boundaries. Motivated by the growing importance of these phenomena, we have embarked on a series of computational studies to elucidate these fundamental creep-induced effects for a rarefied gas in simple, two-dimensional confined geometries. However, unlike previous related studies, we resort to a microscopic description of the gas, mathematically expressed by the Boltzmann integro-differential equation. We employ the direct simulation Monte Carlo (DSMC) method of Bird, the theoretical foundations and several practical applications. In the case of thermally induced flows, the no-time counter method of Bird is used, as implemented for a hard-sphere gas. The scheme has been also extended to account for realistic molecular interaction models, an extension necessary if the diffusion physics underlying concentration creep are to be captured.

  8. Computational Study of Chemical Reactivity Using Information-Theoretic Quantities from Density Functional Reactivity Theory for Electrophilic Aromatic Substitution Reactions.

    Science.gov (United States)

    Wu, Wenjie; Wu, Zemin; Rong, Chunying; Lu, Tian; Huang, Ying; Liu, Shubin

    2015-07-23

    The electrophilic aromatic substitution for nitration, halogenation, sulfonation, and acylation is a vastly important category of chemical transformation. Its reactivity and regioselectivity is predominantly determined by nucleophilicity of carbon atoms on the aromatic ring, which in return is immensely influenced by the group that is attached to the aromatic ring a priori. In this work, taking advantage of recent developments in quantifying nucleophilicity (electrophilicity) with descriptors from the information-theoretic approach in density functional reactivity theory, we examine the reactivity properties of this reaction system from three perspectives. These include scaling patterns of information-theoretic quantities such as Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy and information gain at both molecular and atomic levels, quantitative predictions of the barrier height with both Hirshfeld charge and information gain, and energetic decomposition analyses of the barrier height for the reactions. To that end, we focused in this work on the identity reaction of the monosubstituted-benzene molecule reacting with hydrogen fluoride using boron trifluoride as the catalyst in the gas phase. We also considered 19 substituting groups, 9 of which are ortho/para directing and the other 9 meta directing, besides the case of R = -H. Similar scaling patterns for these information-theoretic quantities found for stable species elsewhere were disclosed for these reactions systems. We also unveiled novel scaling patterns for information gain at the atomic level. The barrier height of the reactions can reliably be predicted by using both the Hirshfeld charge and information gain at the regioselective carbon atom. The energy decomposition analysis ensued yields an unambiguous picture about the origin of the barrier height, where we showed that it is the electrostatic interaction that plays the dominant role, while the roles played by exchange-correlation and

  9. Biomass Chars: The Effects of Pyrolysis Conditions on Their Morphology, Structure, Chemical Properties and Reactivity

    Directory of Open Access Journals (Sweden)

    Chamseddine Guizani

    2017-06-01

    Full Text Available Solid char is a product of biomass pyrolysis. It contains a high proportion of carbon, and lower contents of H, O and minerals. This char can have different valorization pathways such as combustion for heat and power, gasification for Syngas production, activation for adsorption applications, or use as a soil amendment. The optimal recovery pathway of the char depends highly on its physical and chemical characteristics. In this study, different chars were prepared from beech wood particles under various pyrolysis operating conditions in an entrained flow reactor (500–1400 °C. Their structural, morphological, surface chemistry properties, as well as their chemical compositions, were determined using different analytical techniques, including elementary analysis, Scanning Electronic Microscopy (SEM coupled with an energy dispersive X-ray spectrometer (EDX, Fourier Transform Infra-Red spectroscopy (FTIR, and Raman Spectroscopy. The biomass char reactivity was evaluated in air using thermogravimetric analysis (TGA. The yield, chemical composition, surface chemistry, structure, morphology and reactivity of the chars were highly affected by the pyrolysis temperature. In addition, some of these properties related to the char structure and chemical composition were found to be correlated to the char reactivity.

  10. Technical Assessment of Isothermal and Non-Isothermal Modelings of Natural Gas Pipeline Operational Conditions Évaluation technique de modélisations isothermes et non isothermes de conditions opérationnelles de conduites de gaz naturel

    Directory of Open Access Journals (Sweden)

    Sanaye S.

    2012-05-01

    Full Text Available Modeling of equipment in a gas pipeline was performed here by deriving a new form of conservation equation set for compressible flow. Then a section of the third Iranian gas transmission pipeline (Nourabad-Pataveh-Dorahan, N-P-D was investigated by isothermal (IT and non-isothermal (NIT modeling approaches taking into account the effects of ground temperature. In the first part, the steady state operation of the N-P-D pipeline including a compressor station at Pataveh was studied. For the known values of natural gas mass flow rate, and inlet/outlet gas pressures at Nourabad/Dorahan points, the IT and NIT modelings showed about 33.7%, 16.6% and 23% maximum difference percent points for the compressors head, compressors rotational speed and fuel consumption rates respectively. In the second part, the unsteady operation of the N-P-D pipeline due to the shutdown of a compressor at Pataveh Compressor Station (PCS was studied. The results confirmed that at lower ground temperatures (0 and 20°C, the remaining compressors could compensate the loss of one compressor. However, at higher ground temperatures (40 and 50°C, the compressors had to run faster than the highest permissible speed to be able to deliver a certain mass flow rate without reducing the required pipeline pressure. In all above studied cases, the computing time for the non-isothermal modeling was about three times longer than that for the isothermal one. Une modélisation d'équipement au sein d'un gazoduc a été réalisée en dérivant une nouvelle forme d'ensemble d'équations de conservation pour un écoulement compressible. Une section du troisième réseau de distribution de gaz iranien (Nourabad-Pataveh-Dorahan, N-P-D a été ensuite étudiée selon des approches de modélisation isotherme (IT et non isotherme (NIT en prenant en compte les effets de la température du sol. Dans la première partie, le fonctionnement en régime stationnaire du gazoduc N-P-D, comprenant une station

  11. The chemical reactivity and structure of collagen studied by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Wess, T.J.; Wess, L.; Miller, A. [Univ. of Stirling (United Kingdom)

    1994-12-31

    The chemical reactivity of collagen can be studied using neutron diffraction (a non-destructive technique), for certain reaction types. Collagen contains a number of lysine and hydroxylysine side chains that can react with aldehydes and ketones, or these side chains can themselves be converted to aldehydes by lysyl oxidase. The reactivity of these groups not only has an important role in the maintenance of mechanical strength in collagen fibrils, but can also manifest pathologically in the cases of aging, diabetes (reactivity with a variety of sugars) and alcoholism (reactivity with acetaldehyde). The reactivity of reducing groups with collagen can be studied by neutron diffraction, since the crosslink formed in the adduction process is initially of a Schiff base or keto-imine nature. The nature of this crosslink allows it to be deuterated, and the position of this relatively heavy scattering atom can be used in a process of phase determination by multiple isomorphous replacement. This process was used to study the following: the position of natural crosslinks in collagen; the position of adducts in tendon from diabetic rats in vivo and the in vitro position of acetaidehyde adducts in tendon.

  12. Preparation of polypropylene/Mg–Al layered double hydroxides nanocomposites through wet pan-milling: non-isothermal crystallization behaviour

    Science.gov (United States)

    Zheng, Yilei

    2018-01-01

    Differential scanning calorimeter was used to extensively investigate the non-isothermal crystallization of polypropylene (PP)/layered double hydroxides (LDHs) nanocomposites prepared through wet solid-state shear milling. The corresponding crystallization kinetics was further investigated by using Ozawa, modified Avrami and combined Avrami–Ozawa method, respectively. The results showed that the Ozawa method could not well describe the crystallization kinetics of pure PP and its nanocomposites. Comparatively, the modified Avrami method as well as the combined Avrami–Ozawa method gives the satisfactory results. Under the effect of pan-milling, the produced LDH nano intercalated/exfoliated particles exhibit the inhibitive effect on the PP nucleation but more remarkable promotion effect on the spherulite growth, leading to enhancement in the overall crystallization rate. This is reflected in increase of the calculated fold surface free energy σe and also the supercooling degree ΔT required for crystallization nucleation. In addition, the polarized optical microscopy observation also verifies the higher spherulite growth rate of PP/LDHs nanocomposites than that of pure PP. PMID:29410819

  13. Thermodiffusion as a close-to-interface effect that matters in non-isothermal (dis)orderly protein aggregations

    Energy Technology Data Exchange (ETDEWEB)

    Gadomski, A., E-mail: agad@utp.edu.pl; Kruszewska, N., E-mail: nkruszewska@utp.edu.pl

    2014-08-01

    The goal of this discussion letter is to argue how and why an inherent nanoscale thermodiffusion (Soret-type) effect can be relevant in (dis)orderly protein aggregation. We propose a model in which the aggregation of proteins, in the presence of temperature gradient, is described in terms of Smoluchowski dynamics in the phase space of nuclei sizes. The Soret coefficient of the aggregation is proportional to the variations of the aggregation free energy over temperature. The free energy is related to the (interface) boundary condition of the system. When boundary condition is of equilibrium Gibbs–Thomson type, with a well-stated surface tension of the nucleus, to the system can be assigned a negative Soret effect. On the contrary, when a non-equilibrium perturbing (salting-out) term enters the boundary condition, a positive Soret effect may manifest. A zero-value Soret regime is expected to occur in between, yielding very soft (“fragile”) non-Kossel protein-type crystals. - Highlights: • Comprehension for non-isothermal formation of (dis)orderly protein aggregation. • Classification of temperature-sensitive morphologies in colloid-type aggregation. • Morphologies split into near-equilibrium and nonequilibrium structural outcomes. • Classification on mesoscopic nonequilibrium thermodynamics near local equilibrium.

  14. Effects of Covalent Functionalization of MWCNTs on the Thermal Properties and Non-Isothermal Crystallization Behaviors of PPS Composites

    Directory of Open Access Journals (Sweden)

    Myounguk Kim

    2017-09-01

    Full Text Available In this study, a PPS/MWCNTs composite was prepared with poly(phenylene sulfide (PPS, as well as pristine and covalent functionalized multi-walled carbon nanotubes (MWCNTs via melt-blending techniques. Moreover, the dispersion of the MWCNTs on the PPS matrix was improved by covalent functionalization as can be seen from a Field-Emission Scanning Electron Microscope (FE-SEM images. The thermal properties of the PPS/MWCNTs composites were characterized using a thermal conductivity analyzer, and a differential scanning calorimeter (DSC. To analyze the crystallization behavior of polymers under conditions similar with those in industry, the non-isothermal crystallization behaviors of the PPS/MWCNTs composites were confirmed using various kinetic equations, such as the modified Avrami equation and Avrami-Ozawa combined equation. The crystallization rate of PPS/1 wt % pristine MWCNTs composite (PPSP1 was faster because of the intrinsic nucleation effect of the MWCNTs. However, the crystallization rates of the composites containing covalently-functionalized MWCNTs were slower than PPSP1 because of the destruction of the MWCNTs graphitic structure via covalent functionalization. Furthermore, the activation energies calculated by Kissinger’s method were consistently decreased by covalent functionalization.

  15. Modelling of Non-isothermal Flow Abnormally Viscous Fluid in the Channels with Various Geometry of Boundaries

    Directory of Open Access Journals (Sweden)

    K. V. Litvinov

    2016-01-01

    Full Text Available In this paper, we analyzed the flat non-isothermal stationary flow of abnormally viscous fluid in the channels with asymmetric boundary conditions and an unknown output boundary. The geometry of the channels in which the problem is considered, is such regions, that at the transition to bipolar a system of coordinates map into rectangles. This greatly simplifies the boundary conditions, since it is possible to use an orthogonal grid and boundary conditions are given in its nodes. Fields of this type are often found in applications. The boundary conditions are set as follows: the liquid sticks to the boundaries of the channels, which rotate at different speeds and have different radius and temperature; moreover, temperature at the entrance to deformation is known, while on the boundary with the surface the material has the surface temperature; the pressure on the enter and exit of the region becomes zero. The rheological model only takes into account the anomaly of viscosity. The material is not compressible. This process can be described by a system consisting of continuity equations, the equations of conservation of momentum and an energy equation: ∇

  16. Parallel numerical modeling of hybrid-dimensional compositional non-isothermal Darcy flows in fractured porous media

    Science.gov (United States)

    Xing, F.; Masson, R.; Lopez, S.

    2017-09-01

    This paper introduces a new discrete fracture model accounting for non-isothermal compositional multiphase Darcy flows and complex networks of fractures with intersecting, immersed and non-immersed fractures. The so called hybrid-dimensional model using a 2D model in the fractures coupled with a 3D model in the matrix is first derived rigorously starting from the equi-dimensional matrix fracture model. Then, it is discretized using a fully implicit time integration combined with the Vertex Approximate Gradient (VAG) finite volume scheme which is adapted to polyhedral meshes and anisotropic heterogeneous media. The fully coupled systems are assembled and solved in parallel using the Single Program Multiple Data (SPMD) paradigm with one layer of ghost cells. This strategy allows for a local assembly of the discrete systems. An efficient preconditioner is implemented to solve the linear systems at each time step and each Newton type iteration of the simulation. The numerical efficiency of our approach is assessed on different meshes, fracture networks, and physical settings in terms of parallel scalability, nonlinear convergence and linear convergence.

  17. Rheometric Non-Isothermal Gelatinization Kinetics of Chickpea Flour-Based Gluten-Free Muffin Batters with Added Biopolymers

    Science.gov (United States)

    Alvarez, María Dolores; Cuesta, Francisco Javier; Herranz, Beatriz; Canet, Wenceslao

    2017-01-01

    An attempt was made to analyze the elastic modulus (G′) of chickpea flour (CF)-based muffin batters made with CF alone and with added biopolymers (whey protein (WP), xanthan gum (XG), inulin (INL), and their blends) in order to evaluate their suitability to be a wheat flour (WF) substitute in muffins, and to model the heat-induced gelatinization of batters under non-isothermal heating condition from 25 °C to 90 °C. A rheological approach is proposed to determine the kinetic parameters (reaction order (n), frequency factor (k0), and activation energy (Ea)) using linearly-increasing temperature. Zero-order reaction kinetics adequately described batter gelatinization process, therefore assuming a constant rate independent of the initial G′ value. The change of the derivative of G′ with respect to time (dG′/dt) versus temperature is described by one exponential function with activation energies ranging from 118 to 180 kJ·mol−1. Control wheat gluten batter, with higher and lower starch and protein contents, respectively, than CF-based batters, exhibited the highest Ea value. Formulation of CF-based gluten-free batters with starch and protein contents closer to the levels of WF-based batter could be a strategy to decrease differences in kinetic parameters of muffin batters and, therefore, in technological characteristics of baked muffins. PMID:28231082

  18. The deformation and acoustic emission of aluminum-magnesium alloy under non-isothermal thermo-mechanical loading

    Energy Technology Data Exchange (ETDEWEB)

    Makarov, S. V.; Plotnikov, V. A., E-mail: plotnikov@phys.asu.ru; Lysikov, M. V. [Altai State University, Barnaul, 656049 (Russian Federation); Kolubaev, E. A., E-mail: eak@ispms.ru [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The following study investigates the deformation behavior and acoustic emission in aluminum-magnesium alloy under conditions of non-isothermal thermo-mechanical loading. The accumulation of deformation in the alloy, in conditions of change from room temperature to 500°C, occurs in two temperature intervals (I, II), characterized by different rates of deformation. The rate of deformation accumulation is correlated with acoustic emission. With load increasing in cycles from 40 to 200 MPa, the value of the boundary temperature (T{sub b}) between intervals I and II changes non-monotonically. In cycles with load up to 90 MPa, the T{sub b} value increases, while an increase up to 200 MPa makes T{sub b} shift toward lower temperatures. This suggests that the shift of boundaries in the region of low temperatures and the appearance of high-amplitude pulses of acoustic emission characterize the decrease of the magnitude of thermal fluctuations with increasing mechanical load, leading to the rupture of interatomic bonds in an elementary deformation act.

  19. Non-isothermal crystallization kinetics of partially miscible ethylene-vinyl acetate copolymer/low density polyethylene blends

    Directory of Open Access Journals (Sweden)

    2010-03-01

    Full Text Available The non-isothermal crystallization kinetics of ethylene-vinyl acetate copolymer (EVA, 14 wt% vinyl acetate content, low density polyethylene (LDPE and their binary blends with different blending ratio were investigated via differential scanning calorimetry. Jeziorny theory and Mo’s method were utilized in evaluating the crystallization behavior of both neat materials successfully. In the primary crystallization stage both EVA and LDPE had three-dimensional spherulitic growth mechanism. Apparently the crystallization rate of LDPE was faster than that of EVA at a low cooling rate. Increase in cooling rate limited the spherulites’ growth, which narrowed their rate difference. Influences from blending on the crystallization kinetics of each component in EVA/LDPE mixture were evaluated by Kissinger’s activation energy (∆E and Khanna’s crystallization rate coefficient (CRC. Inter-molecular interaction in the melt increased the ∆E of both EVA and LDPE components at the beginning of cooling. During the primary crystallization stage of LDPE, dilution effect from EVA facilitated the crystal growth in LDPE. Co-crystallization between EVA component and the secondary crystallization stage of LDPE component also increased the CRC of EVA. In blend of EVA/LDPE = 7/3, LDPE obtained the maximal CRC value of 174.2 h–1. Results obtained from various approaches accorded well with each other, which insured the rationality of conclusion.

  20. Oxidative synthesis of a novel polyphenol having pendant Schiff base group: Synthesis, characterization, non-isothermal decomposition kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Dilek, Deniz [Faculty of Education, Secondary Science and Mathematics Education, Canakkale Onsekiz Mart University, 17100 Canakkale (Turkey); Dogan, Fatih, E-mail: fatihdogan@comu.edu.tr [Faculty of Education, Secondary Science and Mathematics Education, Canakkale Onsekiz Mart University, 17100 Canakkale (Turkey); Bilici, Ali, E-mail: alibilici66@hotmail.com [Control Laboratory of Agricultural and Forestry Ministry, 34153 Istanbul (Turkey); Kaya, Ismet [Department of Chemistry, Faculty of Science and Arts, Canakkale Onsekiz Mart University, Canakkale (Turkey)

    2011-05-10

    Research highlights: {yields} In this study, the synthesis and thermal characterization of a new functional polyphenol are reported. {yields} Non-isothermal methods were used to evaluate the thermal decomposition kinetics of resulting polymer. {yields} Thermal decomposition of polymer follows a diffusion type kinetic model. {yields} It is noted that this kinetic model is quite rare in polymer degradation studies. - Abstract: In here, the facile synthesis and thermal characterization of a novel polyphenol containing Schiff base pendant group, poly(4-{l_brace}[(4-hydroxyphenyl)imino]methyl{r_brace}benzene-1,2,3-triol) [PHPIMB], are reported. UV-vis, FT-IR, {sup 1}H NMR, {sup 13}C NMR, GPC, TG/DTG-DTA, CV (cyclic voltammetry) and solid state conductivity measurements were utilized to characterize the obtained monomer and polymer. The spectral analyses results showed that PHPIMB was composed of polyphenol main chains containing Schiff base pendant side groups. Thermal properties of the polymer were investigated by thermogravimetric analyses under a nitrogen atmosphere. Five methods were used to study the thermal decomposition of PHPIMB at different heating rate and the results obtained by using all the kinetic methods were compared with each other. The thermal decomposition of PHPIMB was found to be a simple process composed of three stages. These investigated methods were those of Flynn-Wall-Ozawa (FWO), Tang, Kissinger-Akahira-Sunose (KAS), Friedman and Kissinger methods.

  1. Consolidation and conversion of carbon powders into TiC by reactive chemical vapour infiltration

    OpenAIRE

    Ledain, Olivier; JACQUES, Sylvain; Maillé, Laurence

    2016-01-01

    International audience; Ceramic samples were prepared using a hybrid process in which the ceramic powder route was combined with Reactive Chemical Vapour Infiltration, a new gas phase route. In this technique, a carbide growth occurs from the conversion of a carbon-bearing powder and slows down with increase in carbide thickness due to solid-state diffusion limitation. This self-limitation is expected to allow a self-regulation of the growth between the interior and the surface of the sample ...

  2. Evidence for chemical and cellular reactivities of the formaldehyde releaser bronopol, independent of formaldehyde release.

    Science.gov (United States)

    Kireche, Mustapha; Peiffer, Jean-Luc; Antonios, Diane; Fabre, Isabelle; Giménez-Arnau, Elena; Pallardy, Marc; Lepoittevin, Jean-Pierre; Ourlin, Jean-Claude

    2011-12-19

    Formaldehyde and formaldehyde releasers are widely used preservatives and represent an important group of skin sensitizers. Formaldehyde is very often suspected to be the sensitizing agent of formaldehyde-releasers; however, many reported clinical cases of contact allergy to these molecules such as bronopol (2-bromo-2-nitropropane-1,3-diol) indicate negative skin reactions to formaldehyde suggesting a more complex mechanism. The aim of this study was to compare the chemical reactivity and biological activity of formaldehyde with those of two formaldehyde releasers: 2-bromo-2-nitropropane-1,3-diol and 1,3-dimethylol-5,5-dimethylhydantoin. A key step in the sensitization to chemicals is the formation of the hapten-protein antigenic complex via covalent binding between the chemical sensitizer and amino acids in proteins. The chemical reactivity of the three compounds was thus addressed using (13)C NMR analysis of adduct formation upon incubation with a set of nucleophilic amino acids. The biological activity was measured in two in vitro models based on dendritic cells and a monocytic cell line (CD34-DC and THP-1 model) through monitoring of a panel of biomarkers. The results obtained show that 2-bromo-2-nitropropane-1,3-diol produces low amount of free formaldehyde in physiological buffers but that its degradation generates various molecules including 2-bromoethanol. In addition, 2-bromo-2-nitropropane-1,3-diol also generates adducts with amino acids, not observed with formaldehyde alone, that could be explained by the reactivity of 2-bromoethanol. In parallel, in a cellular approach using the human monocytic THP-1 cell line, 2-bromo-2-nitropropane-1,3-diol activates THP-1 cells at concentrations that are not correlated to simple formaldehyde release. This observation is confirmed in the more physiological model CD34-DC. Moreover, in the THP-1 model, the expression profiles of several biomarkers are specific to 2-bromo-2-nitropropane-1,3-diol. Finally, the use in the

  3. Inorganic chemical composition and chemical reactivity of settled dust generated by the World Trade Center building collapse: Chapter 12

    Science.gov (United States)

    Plumlee, Geoffrey S.; Hageman, Philip L.; Lamothe, Paul J.; Ziegler, Thomas L.; Meeker, Gregory P.; Theodorakos, Peter M.; Brownfield, Isabelle; Adams, Monique G.; Swayze, Gregg A.; Hoefen, Todd M.; Taggart, Joseph E.; Clark, Roger N.; Wilson, S.; Sutley, Stephen J.

    2009-01-01

    Samples of dust deposited around lower Manhattan by the September 11, 2001, World Trade Center (WTC) collapse have inorganic chemical compositions that result in part from the variable chemical contributions of concrete, gypsum wallboard, glass fibers, window glass, and other materials contained in the buildings. The dust deposits were also modified chemically by variable interactions with rain water or water used in street washing and fire fighting. Chemical leach tests using deionized water as the extraction fluid show the dust samples can be quite alkaline, due primarily to reactions with calcium hydroxide in concrete particles. Calcium and sulfate are the most soluble components in the dust, but many other elements are also readily leached, including metals such as Al, Sb, Mo Cr, Cu, and Zn. Indoor dust samples produce leachates with higher pH, alkalinity, and dissolved solids than outdoor dust samples, suggesting most outdoor dust had reacted with water and atmospheric carbon dioxide prior to sample collection. Leach tests using simulated lung fluids as the extracting fluid suggest that the dust might also be quite reactive in fluids lining the respiratory tract, resulting in dissolution of some particles and possible precipitation of new phases such as phosphates, carbonates, and silicates. Results of these chemical characterization studies can be used by health scientists as they continue to track and interpret health effects resulting from the short-term exposure to the initial dust cloud and the longer-term exposure to dusts resuspended during cleanup.

  4. Ab initio studies of equations of state and chemical reactions of reactive structural materials

    Science.gov (United States)

    Zaharieva, Roussislava

    The motivations for the research issues addressed in this thesis are based on the needs of the aerospace structural analysis and the design community. The specific focus is related to the characterization and shock induced chemical reactions of multi-functional structural-energetic materials that are also known as the reactive structural materials and their reaction capabilities. Usually motivation for selection of aerospace structural materials is to realize required strength characteristics and favorable strength to weight ratios. The term strength implies resistance to loads experienced during the service life of the structure, including resistance to fatigue loads, corrosion and other extreme conditions. Thus, basically the structural materials are single function materials that resist loads experienced during the service life of the structure. However, it is desirable to select materials that are capable of offering more than one basic function of strength. Very often, the second function is the capability to provide functions of sensing and actuation. In this thesis, the second function is different. The second function is the energetic characteristics. Thus, the choice of dual functions of the material are the structural characteristics and energetic characteristics. These materials are also known by other names such as the reactive material structures or dual functional structural energetic materials. Specifically the selected reactive materials include mixtures of selected metals and metal oxides that are also known as thermite mixtures, reacting intermetallic combinations and oxidizing materials. There are several techniques that are available to synthesize these structural energetic materials or reactive material structures and new synthesis techniques constitute an open research area. The focus of this thesis, however, is the characterization of chemical reactions of reactive material structures that involve two or more solids (or condensed matter). The

  5. CFD modeling of reactive pollutant dispersion in simplified urban configurations with different chemical mechanisms

    Science.gov (United States)

    Sanchez, Beatriz; Santiago, Jose-Luis; Martilli, Alberto; Palacios, Magdalena; Kirchner, Frank

    2016-09-01

    An accurate understanding of urban air quality requires considering a coupled behavior between the dispersion of reactive pollutants and atmospheric dynamics. Currently, urban air pollution is mostly dominated by traffic emission, where nitrogen oxides (NOx) and volatile organic compounds (VOCs) are the primary emitted pollutants. However, modeling reactive pollutants with a large set of chemical reactions, using a computational fluid dynamic (CFD) model, requires a large amount of computational (CPU) time. In this sense, the selection of the chemical reactions needed in different atmospheric conditions becomes essential in finding the best compromise between CPU time and accuracy. The purpose of this work is to assess the differences in NO and NO2 concentrations by considering three chemical approaches: (a) passive tracers (non-reactive), (b) the NOx-O3 photostationary state and (c) a reduced complex chemical mechanism based on 23 species and 25 reactions. The appraisal of the effects of chemical reactions focuses on studying the NO and NO2 dispersion in comparison with the tracer behavior within the street. In turn, the effect of including VOC reactions is also analyzed taking into account several VOC / NOx ratios of traffic emission. Given that the NO and NO2 dispersion can also be affected by atmospheric conditions, such as wind flow or the background concentration from season-dependent pollutants, in this work the influence of wind speeds and background O3 concentrations are studied. The results show that the presence of ozone in the street plays an important role in NO and NO2 concentrations. Therefore, greater differences linked to the chemical approach used are found with higher O3 concentrations and faster wind speeds. This bears relation to the vertical flux as a function of ambient wind speed since it increases the pollutant exchange between the street and the overlying air. This detailed study allows one to ascertain under which atmospheric conditions

  6. CFD modeling of reactive pollutant dispersion in simplified urban configurations with different chemical mechanisms

    Directory of Open Access Journals (Sweden)

    B. Sanchez

    2016-09-01

    Full Text Available An accurate understanding of urban air quality requires considering a coupled behavior between the dispersion of reactive pollutants and atmospheric dynamics. Currently, urban air pollution is mostly dominated by traffic emission, where nitrogen oxides (NOx and volatile organic compounds (VOCs are the primary emitted pollutants. However, modeling reactive pollutants with a large set of chemical reactions, using a computational fluid dynamic (CFD model, requires a large amount of computational (CPU time. In this sense, the selection of the chemical reactions needed in different atmospheric conditions becomes essential in finding the best compromise between CPU time and accuracy. The purpose of this work is to assess the differences in NO and NO2 concentrations by considering three chemical approaches: (a passive tracers (non-reactive, (b the NOx–O3 photostationary state and (c a reduced complex chemical mechanism based on 23 species and 25 reactions. The appraisal of the effects of chemical reactions focuses on studying the NO and NO2 dispersion in comparison with the tracer behavior within the street. In turn, the effect of including VOC reactions is also analyzed taking into account several VOC ∕ NOx ratios of traffic emission. Given that the NO and NO2 dispersion can also be affected by atmospheric conditions, such as wind flow or the background concentration from season-dependent pollutants, in this work the influence of wind speeds and background O3 concentrations are studied. The results show that the presence of ozone in the street plays an important role in NO and NO2 concentrations. Therefore, greater differences linked to the chemical approach used are found with higher O3 concentrations and faster wind speeds. This bears relation to the vertical flux as a function of ambient wind speed since it increases the pollutant exchange between the street and the overlying air. This detailed study allows one to ascertain under which

  7. An experimental investigation of thermo-capillary convection in solution of lithium bromide at non-isothermal absorption

    Directory of Open Access Journals (Sweden)

    Bufetov N. S.

    2016-09-01

    Full Text Available The aim of this work is to obtain new experimental data on the development of thermo-capillary convection in a solution of lithium bromide with non-isothermal absorption of water vapor in a confined vessel. In experiments the contactless method of measuring the temperature of the interface based on using thermal imaging equipment, and the visualization method of the flow arising in the absorbent layer by introducing markers into solution have been used. The immobile layer of lithium bromide solution with an initial concentration of 58 % and a layer thickness of 20 mm in a confined vessel of 70 mm in diameter has been chosen as an object of investigation. The water vapor has been used as the absorbed gas, whose pressure was kept constant during the absorption (approximately 2 000 Pa. The absorption process has started after the steam supply to the absorber where the initial pressure has corresponded to saturated water vapor pressure at the temperature of the solution (250–300 Pa. The speed and duration of convective motion in the layer absorption on the basis of imaging arising due to thermo-capillary convection have been measured. The thermograms of the interface for various operating parameters have been obtained with the development of thermo-concentration convection. The characteristic time of the thermo-capillary convection development has been determined. Based on the experimental data analysis the empirical expressions for duration of the convective motion depending on the vapor pressure in the absorber and the thickness of the absorbent layer have been proposed. It has been shown that lowering the initial temperature of the solution leads to enhancement of thermo-concentration convection. The results are useful for the design and optimization of elements of refrigeration engineering of the absorption type.

  8. Initial precipitation and hardening mechanism during non-isothermal aging in an Al–Mg–Si–Cu 6005A alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wenchao, E-mail: yangwenchao1985@163.com [School of material Science and Engineering, Central South University, Changsha, 410083 (China); Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University, Uxbridge, UB8 3PH (United Kingdom); Ji, Shouxun [Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University, Uxbridge, UB8 3PH (United Kingdom); Huang, Lanping [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 (China); Sheng, Xiaofei; Li, Zhou; Wang, Mingpu [School of material Science and Engineering, Central South University, Changsha, 410083 (China)

    2014-08-15

    The characterization of precipitation and hardening mechanism during non-isothermal aging had been investigated using high resolution transmission electron microscopy for an Al–Mg–Si–Cu 6005A alloy. It was proposed that the needle-shaped β″ precipitates with a three-dimension coherency strain-field and an increased number density in the Al matrix provided the maximum strengthening effect for the Al–Mg–Si–Cu 6005A alloy. Simultaneously, it was also found that the formation and evolution of clusters in the early precipitation were associated with the vacancy binding energy, during which Si atoms played an important role in controlling the numbers density of Mg/Si co-clusters, and the excess Si atoms provided the increased number of nucleation sites for the subsequent precipitates to strengthen and improve the precipitation rate. Finally, based on the experimental observation and theoretical analysis, the precipitation sequence during the early precipitation in the Al–Mg–Si–Cu 6005A alloy was proposed as: supersaturated solid solution → Si-vacancy pairs, Mg-vacancy pairs and Mg clusters → Si clusters, and dissolution of Mg clusters → Mg atoms diffusion into the existing Si clusters → Mg/Si co-clusters → GP zone. - Highlights: • β″ precipitates provide the maximum strengthening effect for the 6005A alloy. • Si atoms play an important role in controlling the numbers of Mg/Si co-clusters. • The early aging sequence is deduced based on the solute-vacancy binding energy.

  9. Bioassays for the detection of chemicals that can form bioactivation-dependent reactive free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Sanderson, J.T.; Commandeur, J.N.M.; Wezel, A. van; Vermeulen, N.P.E. (Free Univ. of Amsterdam (Netherlands). Div. of Molecular Toxicology National Inst. for Coastal and Marine Management, Den Haag (Netherlands))

    1999-06-01

    In vitro bioassays were developed for the detection of chemicals that can be bioactivated to reactive free radical species in microsomal fractions. Two methods were deployed, a down-scaled spectrophotometric method for the detection of chemicals that can cause lipid peroxidation using the measurement of thiobarbituric acid-reactive substances (TBARS) and a fluorometric method for the detection of chemicals that can undergo redox cycling to generate superoxide radicals based on the detection of hydrogen peroxide. The response of these systems to prototypical and environmentally relevant chemicals, including tetrachloromethane and paraquat, was examined. The detection limit of the lipid peroxidation bioassay, based on the formation of TBARS, was about 1 [micro]M for tetrachloromethane; that of the bioassay for redox cyclers, based on the production of hydrogen peroxide, was about 2 [micro]M for paraquat and about 100-fold lower for the potent redox cycler 2,3,5,6-tetramethylbenzoquinone (TMBQ). Several binary mixtures of chemicals were tested for potential nonadditive effects in both in vitro systems. Some antagonistic effects among halogenated methanes were observed in the lipid peroxidation assay. In the hydrogen peroxide production assay, greater than additive effects were seen between small concentrations of paraquat and TMBQ. A number of surface water concentrates from several locations in The Netherlands, with various levels of chemical contamination, exhibited a weak response in the hydrogen peroxide production assay. Acetone was found to interfere with the response of the bioassay to redox cyclers and, therefore, the water concentrates (originally in acetone) were transferred to ethanol prior to testing. A good correlation was observed between the response of the water concentrates in the hydrogen peroxide production assay and their acute toxicity in Daphnia magna. No correlation was observed between this bioassay response and toxicity in the Microtox

  10. THE INTEGRATED USE OF COMPUTATIONAL CHEMISTRY, SCANNING PROBE MICROSCOPY, AND VIRTUAL REALITY TO PREDICT THE CHEMICAL REACTIVITY OF ENVIRONMENTAL SURFACES

    Science.gov (United States)

    In the last decade three new techniques scanning probe microscopy (SPM), virtual reality (YR) and computational chemistry ave emerged with the combined capability of a priori predicting the chemically reactivity of environmental surfaces. Computational chemistry provides the cap...

  11. Nitrous oxide production from reactive nitrification intermediates: a concerted action of biological and chemical processes

    Science.gov (United States)

    Brüggemann, Nicolas; Heil, Jannis; Liu, Shurong; Wei, Jing; Vereecken, Harry

    2017-04-01

    This contribution tries to open up a new perspective on biogeochemical N2O production processes, taking the term bio-geo-chemistry literally. What if a major part of N2O is produced from reactive intermediates of microbiological N turnover processes ("bio…") leaking out of the involved microorganisms into the soil ("…geo…") and then reacting chemically ("…chemistry") with the surrounding matrix? There are at least two major reactive N intermediates that might play a significant role in these coupled biological-chemical reactions, i.e. hydroxylamine (NH2OH) and nitrite (NO2-), both of which are produced during nitrification under oxic conditions, while NO2- is also produced during denitrification under anoxic conditions. Furthermore, NH2OH is assumed to be also a potential intermediate of DNRA and/or anammox. First, this contribution will summarize information about several chemical reactions involving NH2OH and NO2- leading to the formation of N2O. These abiotic reactions are: reactions of NO2- with reduced metal cations, nitrosation reactions of NO2- and soil organic matter (SOM), the reaction between NO2- and NH2OH, and the oxidation of NH2OH by oxidized metal ions. While these reactions can occur over a broad range of soil characteristics, they are ignored in most current N trace gas studies in favor of biological processes only. Disentangling microbiological from purely chemical N2O production is further complicated by the fact that the chemically formed N2O is either undiscernible from N2O produced during nitrification, or shows an intermediate 15N site preference between that of N2O from nitrification and denitrification, respectively. Results from experiments with live and sterilized soil samples, with artificial soil mixtures and with phenolic lignin decomposition model compounds will be presented that demonstrate the potential contribution of these abiotic processes to soil N trace gas emissions, given a substantial leakage rate of these reactive

  12. Specific chemical reactivities of spatially separated 3-aminophenol conformers with cold Ca+ ions.

    Science.gov (United States)

    Chang, Yuan-Pin; Długołęcki, Karol; Küpper, Jochen; Rösch, Daniel; Wild, Dieter; Willitsch, Stefan

    2013-10-04

    Many molecules exhibit multiple rotational isomers (conformers) that interconvert thermally and are difficult to isolate. Consequently, a precise characterization of their role in chemical reactions has proven challenging. We have probed the reactivity of specific conformers by using an experimental technique based on their spatial separation in a molecular beam by electrostatic deflection. The separated conformers react with a target of Coulomb-crystallized ions in a trap. In the reaction of Ca(+) with 3-aminophenol, we find a twofold larger rate constant for the cis compared with the trans conformer (differentiated by the O-H bond orientation). This result is explained by conformer-specific differences in the long-range ion-molecule interaction potentials. Our approach demonstrates the possibility of controlling reactivity through selection of conformational states.

  13. XCHEM-1D: A Heat Transfer/Chemical Kinetics Computer Program for multilayered reactive materials

    Energy Technology Data Exchange (ETDEWEB)

    Gross, R.J.; Baer, M.R.; Hobbs, M.L.

    1993-10-01

    An eXplosive CHEMical kinetics code, XCHEM, has been developed to solve the reactive diffusion equations associated with thermal ignition of energetic materials. This method-of-lines code uses stiff numerical methods and adaptive meshing to resolve relevant combustion physics. Solution accuracy is maintained between multilayered materials consisting of blends of reactive components and/or inert materials. Phase change and variable properties are included in one-dimensional slab, cylindrical and spherical geometries. Temperature-dependent thermal properties have been incorporated and the modification of thermal conductivities to include decomposition effects are estimated using solid/gas volume fractions determined by species fractions. Gas transport properties, including high pressure corrections, have also been included. Time varying temperature, heat flux, convective and thermal radiation boundary conditions, and layer to layer contact resistances have also been implemented.

  14. Prediction of monomer reactivity in radical copolymerizations from transition state quantum chemical descriptors

    Directory of Open Access Journals (Sweden)

    Zhengde Tan

    2013-01-01

    Full Text Available In comparison with the Q-e scheme, the Revised Patterns Scheme: the U, V Version (the U-V scheme has greatly improved both its accessibility and its accuracy in interpreting and predicting the reactivity of a monomer in free-radical copolymerizations. Quantitative structure-activity relationship (QSAR models were developed to predict the reactivity parameters u and v of the U-V scheme, by applying genetic algorithm (GA and support vector machine (SVM techniques. Quantum chemical descriptors used for QSAR models were calculated from transition state species with structures C¹H3 - C²HR³• or •C¹H2 - C²H2R³ (formed from vinyl monomers C¹H²=C²HR³ + H•, using density functional theory (DFT, at the UB3LYP level of theory with 6-31G(d basis set. The optimum support vector regression (SVR model of the reactivity parameter u based on Gaussian radial basis function (RBF kernel (C = 10, ε = 10- 5 and γ = 1.0 produced root-mean-square (rms errors for the training, validation and prediction sets being 0.220, 0.326 and 0.345, respectively. The optimal SVR model for v with the RBF kernel (C = 20, ε = 10- 4 and γ = 1.2 produced rms errors for the training set of 0.123, the validation set of 0.206 and the prediction set of 0.238. The feasibility of applying the transition state quantum chemical descriptors to develop SVM models for reactivity parameters u and v in the U-V scheme has been demonstrated.

  15. Modeling and analysis of time-dependent processes in a chemically reactive mixture

    Science.gov (United States)

    Ramos, M. P.; Ribeiro, C.; Soares, A. J.

    2018-01-01

    In this paper, we study the propagation of sound waves and the dynamics of local wave disturbances induced by spontaneous internal fluctuations in a reactive mixture. We consider a non-diffusive, non-heat conducting and non-viscous mixture described by an Eulerian set of evolution equations. The model is derived from the kinetic theory in a hydrodynamic regime of a fast chemical reaction. The reactive source terms are explicitly computed from the kinetic theory and are built in the model in a proper way. For both time-dependent problems, we first derive the appropriate dispersion relation, which retains the main effects of the chemical process, and then investigate the influence of the chemical reaction on the properties of interest in the problems studied here. We complete our study by developing a rather detailed analysis using the Hydrogen-Chlorine system as reference. Several numerical computations are included illustrating the behavior of the phase velocity and attenuation coefficient in a low-frequency regime and describing the spectrum of the eigenmodes in the small wavenumber limit.

  16. Modeling and analysis of time-dependent processes in a chemically reactive mixture

    Science.gov (United States)

    Ramos, M. P.; Ribeiro, C.; Soares, A. J.

    2017-08-01

    In this paper, we study the propagation of sound waves and the dynamics of local wave disturbances induced by spontaneous internal fluctuations in a reactive mixture. We consider a non-diffusive, non-heat conducting and non-viscous mixture described by an Eulerian set of evolution equations. The model is derived from the kinetic theory in a hydrodynamic regime of a fast chemical reaction. The reactive source terms are explicitly computed from the kinetic theory and are built in the model in a proper way. For both time-dependent problems, we first derive the appropriate dispersion relation, which retains the main effects of the chemical process, and then investigate the influence of the chemical reaction on the properties of interest in the problems studied here. We complete our study by developing a rather detailed analysis using the Hydrogen-Chlorine system as reference. Several numerical computations are included illustrating the behavior of the phase velocity and attenuation coefficient in a low-frequency regime and describing the spectrum of the eigenmodes in the small wavenumber limit.

  17. The chemical and mechanical behaviors of polymer / reactive metal systems under high strain rates

    Science.gov (United States)

    Shen, Yubin

    As one category of energetic materials, impact-initiated reactive materials are able to release a high amount of stored chemical energy under high strain rate impact loading, and are used extensively in civil and military applications. In general, polymers are introduced as binder materials to trap the reactive metal powders inside, and also act as an oxidizing agent for the metal ingredient. Since critical attention has been paid on the metal / metal reaction, only a few types of polymer / reactive metal interactions have been studied in the literature. With the higher requirement of materials resistant to different thermal and mechanical environments, the understanding and characterization of polymer / reactive metal interactions are in great demand. In this study, PTFE (Polytetrafluoroethylene) 7A / Ti (Titanium) composites were studied under high strain rates by utilizing the Taylor impact and SHPB tests. Taylor impact tests with different impact velocities, sample dimensions and sample configurations were conducted on the composite, equipped with a high-speed camera for tracking transient images during the sudden process. SHPB and Instron tests were carried out to obtain the stress vs. strain curves of the composite under a wide range of strain rates, the result of which were also utilized for fitting the constitutive relations of the composite based on the modified Johnson-Cook strength model. Thermal analyses by DTA tests under different flow rates accompanied with XRD identification were conducted to study the reaction mechanism between PTFE 7A and Ti when only heat was provided. Numerical simulations on Taylor impact tests and microstructural deformations were also performed to validate the constitutive model built for the composite system, and to investigate the possible reaction mechanism between two components. The results obtained from the high strain rate tests, thermal analyses and numerical simulations were combined to provide a systematic study on

  18. Computational Nutraceutics: Chemical Reactivity Properties of the Flavonoid Naringin by Means of Conceptual DFT

    Directory of Open Access Journals (Sweden)

    Jorge Ignacio Martínez-Araya

    2013-01-01

    Full Text Available The M06 family of density functionals has been assessed for the calculation of the molecular structure and properties of the Naringin molecule. The chemical reactivity descriptors have been calculated through Conceptual DFT. The active sites for nucleophilic and electrophilic attacks have been chosen by relating them to the Fukui function indices and the dual descriptor f(2(r. A comparison between the descriptors calculated through vertical energy values and those arising from the Koopmans' theorem approximation has been performed in order to check for the validity of the last procedure.

  19. Fluidizable zinc titanate materials with high chemical reactivity and attrition resistance

    Science.gov (United States)

    Gupta, Raghubir P.; Gangwal, Santosh K.; Jain, Suresh C.

    1993-01-01

    Highly durable and chemically reactive zinc titanate materials are prepared in a particle size range of 50 to 400 .mu.m suitable for a fluidized-bed reactor for removing reduced sulfur species in a gaseous form by granulating a mixture of fine zinc oxide and titanium oxide with inorganic and organic binders and by optional additions of small amounts of activators such as CoO and MoO.sub.3 ; and then indurating it at 800.degree. to 900.degree. C. for a time sufficient to produce attrition-resistant granules.

  20. Complex Burgers' Equation: Evolution of Shock Waves with a Pair of Non-isothermal Ions in an Arbitrarily Charged Dusty Plasma

    Science.gov (United States)

    Dev, Apul N.; Deka, Manoj Kr.

    2017-10-01

    The evolution characteristics of dust-acoustic shock wave phenomenon in an arbitrarily charged dusty plasma in presence of pair-ion are investigated by deriving modified Complex Burgers' equation. In this work, the effect of state of both the ions on the shock wave potential is analysed and discussed in detail. It has been observed that the variation of the non-linear coefficient is more consistent with the non-isothermal positive ions moving toward thermal equilibrium than with non-isothermal negative ions. A significant effect on the amplitude of the shock wave potential is observed as the distribution of the non-isothermal positive and negative ions changes from a hump shape through the flat-topped to Boltzmann type. A weighty effect on the height of the shock wave is observed as and when the Mach number of positive and negative ions changes. The shock wave potential shows a greater (lesser) value with negative (positive) ions moving ahead for thermal equilibrium.

  1. Hydrodynamic boundary conditions for one-component liquid-gas flows on non-isothermal solid substrates

    KAUST Repository

    Xu, Xinpeng

    2012-01-01

    Recently, liquid-gas flows related to droplets, bubbles, and thin films on solid surfaces with thermal and wettability gradients have attracted widespread attention because of the many physical processes involved and their promising potential applications in biology, chemistry, and industry. Various new physical effects have been discovered at fluid-solid interfaces by experiments and molecular dynamics simulations, e.g., fluid velocity slip, temperature slip (Kapitza resistance), mechanical-thermal cross coupling, etc. There have been various models and theories proposed to explain these experimental and numerical observations. However, to the best of our knowledge,a continuum hydrodynamic model capable of predicting the temperature and velocity profiles of liquid-gas flows on non-isothermal, heterogeneous solid substrates is still absent. The purpose of this work is to construct a continuum model for simulating the liquid-gas flows on solid surfaces that are flat and rigid, and may involve wettability gradients and thermal gradients. This model is able to describe fluid velocity slip, temperature slip, and mechanical-thermal coupling that may occur at fluid-solid interfaces. For this purpose, we first employ the diffuse interface modeling to formulate the hydrodynamic equations for one-component liquid-gas flows in the bulk region. This reproduces the dynamic van der Waals theory of Onuki [Phys. Rev. Lett., 94: 054501, 2005]. We then extendWaldmann\\'s method [Z. Naturforsch. A, 22: 1269-1280, 1967] to formulate the boundary conditions at the fluid-solid interface that match the hydrodynamic equations in the bulk. The effects of the solid surface curvature are also briefly discussed in the appendix. The guiding principles of our model derivation are the conservation laws and the positive definiteness of entropy production together with the Onsager reciprocal relation. The derived model is self-consistent in the sense that the boundary conditions are

  2. Interactions between ingredients in IMX-101: Reactive Chemical Processes Control Insensitive Munitions Properties

    Energy Technology Data Exchange (ETDEWEB)

    Maharrey, Sean P.; Wiese-Smith, Deneille; Highley, Aaron M.; Behrens, Richard,; Kay, Jeffrey J

    2014-03-01

    Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry (STMBMS) measurements have been conducted on a new Insensitive Munitions (IM) formulation. IMX-101 is the first explosive to be fully IM qualified under new NATO STANAG guidelines for fielded munitions. The formulation uses dinitroanisole (DNAN) as a new melt cast material to replace TNT, and shows excellent IM performance when formulated with other energetic ingredients. The scope of this work is to explain this superior IM performance by investigating the reactive processes occurring in the material when subjected to a well-controlled thermal environment. The dominant reactive processes observed were a series of complex chemical interactions between the three main ingredients (DNAN, NQ, and NTO) that occurs well below the onset of the normal decomposition process of any of the individual ingredients. This process shifts the thermal response of the formulations to a much lower temperature, where the kinetically controlled reaction processes are much slower. This low temperature shift has the effect of allowing the reactions to consume the reactive solids (NQ, NTO) well before the reaction rates increase and reach thermal runaway, resulting in a relatively benign response to the external stimuli. The main findings on the interaction processes are presented.

  3. Experimental study on corrosion and precipitation in non-isothermal Pb-17Li system for development of liquid breeder blanket of fusion reactor

    Science.gov (United States)

    Kondo, Masatoshi; Ishii, Masaomi; Norimatsu, Takayoshi; Muroga, Takeo

    2017-07-01

    The corrosion characteristics of RAFM steel JLF-1 in a non-isothermal Pb-17Li flowing system were investigated by means of the corrosion test using a non-isothermal mixing pot. The corrosion test was performed at 739K with a temperature gradient of 14K for 500 hours. The corrosion tests at a static and a flowing conditions in an isothermal Pb-17Li system were also performed at the same temperature for the same duration with the non-isothermal test. Then, the effect of mass transfer both by the flow and the temperature gradient on the corrosion behaviors was featured by the comparison of these results. The corrosion was caused by the dissolution of Fe and Cr from the steel surface into the flowing Pb-17Li. The specimen surface revealed a fine granular microstructure after the corrosion tests. A large number of pebbleshaped protrusions were observed on the specimen surface. This microstructure was different from the original martensite microstructure of the steel, and might be formed by the influence of the reaction with Li component in the alloy. The formation of the granular microstructure was accelerated by the flow and the temperature gradient. Some pebble-shaped protrusions had gaps at their bases. The removal of these pebble-shaped granules by the flowing Pb-17Li might cause a small-scale corrosion-erosion. The results of metallurgical analysis indicated that a large-scale corrosion-erosion was also caused by their destruction of the corroded layer on the surface. The non-isothermal mixing pot equipped a cold trap by a metal mesh in the low temperature region. The metal elements of Fe and Cr were recovered as they precipitated on the surface of the metal mesh. It was found that a Fe-Cr binary intermetallic compound was formed in the precipitation procedure. The overall mass transfer coefficient for the dissolution type corrosion in the non-isothermal system was much bigger than that in the isothermal system. This model evaluation indicated that the temperature

  4. The influence of condensed tannin structure on rate of microbial mineralization and reactivity to chemical assays.

    Science.gov (United States)

    Norris, Charlotte E; Preston, Caroline M; Hogg, Karen E; Titus, Brian D

    2011-03-01

    We examined how tannin structure influences reactivity in tannin assays and carbon and nitrogen mineralization. Condensed tannins from the foliage of ten tree and shrub species and from pecan shells (Carya illinoensis) had different proportions of: (a) epicatechin (cis) and catechin (trans) isomers, (b) procyanidin (PC) and prodelphinidin (PD) monomers, and (c) different chain lengths. The response of each tannin to several widely used tannin assays was determined. Although there was some variation in response to proanthocyanidin (butanol/HCl) and Folin Ciocalteu assays, we did not deduce any predictable relationship between tannin structure and response to either assay. There was little variation in protein precipitation among the different tannins. To assess biological activity, six of the tannins were incubated with forest humus for 22 days. We determined that, while PC-based tannins remained at least partly extractable for the duration of the incubation, tannins with a high proportion of PD subunits rapidly became unextractable from soil. There was a positive correlation between net nitrogen mineralization and cis chemical structure. Carbon mineralization was enhanced initially by the addition of tannins to humus, but after 22 days, a negative correlation between the proportion of cis subunits and respiration was determined. Overall, we were not able to demonstrate consistent effects of structure on either microbial mineralization or reactivity to chemical assays; such relationships remain elusive.

  5. Chemical reactivity and skin sensitization potential for benzaldehydes: can Schiff base formation explain everything?

    Science.gov (United States)

    Natsch, Andreas; Gfeller, Hans; Haupt, Tina; Brunner, Gerhard

    2012-10-15

    Skin sensitizers chemically modify skin proteins rendering them immunogenic. Sensitizing chemicals have been divided into applicability domains according to their suspected reaction mechanism. The widely accepted Schiff base applicability domain covers aldehydes and ketones, and detailed structure-activity-modeling for this chemical group was presented. While Schiff base formation is the obvious reaction pathway for these chemicals, the in silico work was followed up by limited experimental work. It remains unclear whether hydrolytically labile Schiff bases can form sufficiently stable epitopes to trigger an immune response in the living organism with an excess of water being present. Here, we performed experimental studies on benzaldehydes of highly differing skin sensitization potential. Schiff base formation toward butylamine was evaluated in acetonitrile, and a detailed SAR study is presented. o-Hydroxybenzaldehydes such as salicylaldehyde and the oakmoss allergens atranol and chloratranol have a high propensity to form Schiff bases. The reactivity is highly reduced in p-hydroxy benzaldehydes such as the nonsensitizing vanillin with an intermediate reactivity for p-alkyl and p-methoxy-benzaldehydes. The work was followed up under more physiological conditions in the peptide reactivity assay with a lysine-containing heptapeptide. Under these conditions, Schiff base formation was only observable for the strong sensitizers atranol and chloratranol and for salicylaldehyde. Trapping experiments with NaBH₃CN showed that Schiff base formation occurred under these conditions also for some less sensitizing aldehydes, but the reaction is not favored in the absence of in situ reduction. Surprisingly, the Schiff bases of some weaker sensitizers apparently may react further to form stable peptide adducts. These were identified as the amides between the lysine residues and the corresponding acids. Adduct formation was paralleled by oxidative deamination of the parent

  6. Biological and chemical reactivity and phosphorus forms of buffalo manure compost, vermicompost and their mixture with biochar.

    Science.gov (United States)

    Ngo, Phuong-Thi; Rumpel, Cornelia; Ngo, Quoc-Anh; Alexis, Marie; Velásquez Vargas, Gabriela; Mora Gil, Maria de la Luz; Dang, Dinh-Kim; Jouquet, Pascal

    2013-11-01

    This study characterized the carbon and phosphorus composition of buffalo manure, its compost and vermicompost and investigated if presence of bamboo biochar has an effect on their chemical and biological reactivity. The four substrates were characterized for chemical and biochemical composition and P forms. The biological stability of the four substrates and their mixtures were determined during an incubation experiment. Their chemical reactivity was analyzed after acid dichromate oxidation. Biological reactivity of these substrates was related to their soluble organic matter content, which decreased in the order buffalo manure>compost>vermicompost. Phosphorus was labile in all organic substrates and composting transformed organic P into plant available P. The presence of biochar led to a protection of organic matter against chemical oxidation and changed their susceptibility to biological degradation, suggesting that biochar could increase the carbon sequestration potential of compost, vermicompost and manure, when applied in mixture. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Chemical composition and photochemical reactivity of exhaust from aircraft turbine engines

    Directory of Open Access Journals (Sweden)

    T. F. Lyon

    Full Text Available Assessment of the environmental impact of aircraft emissions is required by planners and policy makers. Seveal areas of concern are: 1. exposure of airport workers and urban residents to toxic chemicals emitted when the engines operate at low power (idle and taxi on the ground; 2. contributions to urban photochemical air pollution of aircraft volatile organic and nitrogen oxides emissions from operations around airports; and 3. emissions of nitrogen oxides and particles during high-altitude operation. The environmental impact of chemicals emitted from jet aircraft turbine engines has not been firmly established due to lack of data regarding emission rates and identities of the compounds emitted. This paper describes an experimental study of two different aircraft turbine engines designed to determine detailed organic emissions, as well as emissions of inorganic gases. Emissions were measured at several engine power settings. Measurements were made of detailed organic composition from C1 through C17, CO, CO2, NO, NOx, and polycyclic aromatic hydrocarbons. Measurements were made using a multi-port sampling pro be positioned directly behind the engine in the exhaust exit plane. The emission measurements have been used to determine the organic distribution by carbon number and the distribution by compound class at each engine power level. The sum of the organic species was compared with an independent measurement of total organic carbon to assess the carbon mass balance. A portion of the exhaust was captured and irradiated in outdoor smog chambers to assess the photochemical reactivity of the emissions with respect to ozone formation. The reactivity of emissions from the two engines was apportioned by chemical compound class.

  8. Chemical composition and photochemical reactivity of exhaust from aircraft turbine engines

    Directory of Open Access Journals (Sweden)

    C. W. Spicer

    1994-08-01

    Full Text Available Assessment of the environmental impact of aircraft emissions is required by planners and policy makers. Seveal areas of concern are: 1. exposure of airport workers and urban residents to toxic chemicals emitted when the engines operate at low power (idle and taxi on the ground; 2. contributions to urban photochemical air pollution of aircraft volatile organic and nitrogen oxides emissions from operations around airports; and 3. emissions of nitrogen oxides and particles during high-altitude operation. The environmental impact of chemicals emitted from jet aircraft turbine engines has not been firmly established due to lack of data regarding emission rates and identities of the compounds emitted. This paper describes an experimental study of two different aircraft turbine engines designed to determine detailed organic emissions, as well as emissions of inorganic gases. Emissions were measured at several engine power settings. Measurements were made of detailed organic composition from C1 through C17, CO, CO2, NO, NOx, and polycyclic aromatic hydrocarbons. Measurements were made using a multi-port sampling pro be positioned directly behind the engine in the exhaust exit plane. The emission measurements have been used to determine the organic distribution by carbon number and the distribution by compound class at each engine power level. The sum of the organic species was compared with an independent measurement of total organic carbon to assess the carbon mass balance. A portion of the exhaust was captured and irradiated in outdoor smog chambers to assess the photochemical reactivity of the emissions with respect to ozone formation. The reactivity of emissions from the two engines was apportioned by chemical compound class.

  9. New chemical-DSMC method in numerical simulation of axisymmetric rarefied reactive flow

    Science.gov (United States)

    Zakeri, Ramin; Kamali Moghadam, Ramin; Mani, Mahmoud

    2017-04-01

    The modified quantum kinetic (MQK) chemical reaction model introduced by Zakeri et al. is developed for applicable cases in axisymmetric reactive rarefied gas flows using the direct simulation Monte Carlo (DSMC) method. Although, the MQK chemical model uses some modifications in the quantum kinetic (QK) method, it also employs the general soft sphere collision model and Stockmayer potential function to properly select the collision pairs in the DSMC algorithm and capture both the attraction and repulsion intermolecular forces in rarefied gas flows. For assessment of the presented model in the simulation of more complex and applicable reacting flows, first, the air dissociation is studied in a single cell for equilibrium and non-equilibrium conditions. The MQK results agree well with the analytical and experimental data and they accurately predict the characteristics of the rarefied flowfield with chemical reaction. To investigate accuracy of the MQK chemical model in the simulation of the axisymmetric flow, air dissociation is also assessed in an axial hypersonic flow around two geometries, the sphere as a benchmark case and the blunt body (STS-2) as an applicable test case. The computed results including the transient, rotational and vibrational temperatures, species concentration in the stagnation line, and also the heat flux and pressure coefficient on the surface are compared with those of the other chemical methods like the QK and total collision energy (TCE) models and available analytical and experimental data. Generally, the MQK chemical model properly simulates the chemical reactions and predicts flowfield characteristics more accurate rather than the typical QK model. Although in some cases, results of the MQK approaches match with those of the TCE method, the main point is that the MQK does not need any experimental data or unrealistic assumption of specular boundary condition as used in the TCE method. Another advantage of the MQK model is the

  10. Evidence for Different Reactive Hg Sources and Chemical Compounds at Adjacent Valley and High Elevation Locations.

    Science.gov (United States)

    Sexauer Gustin, Mae; Pierce, Ashley M; Huang, Jiaoyan; Miller, Matthieu B; Holmes, Heather A; Loria-Salazar, S Marcela

    2016-11-15

    The spatial distribution of chemical compounds and concentration of reactive mercury (RM), defined as the sum of gaseous oxidized mercury (GOM) and sources (GOM = nitrogen and sulfur-based compounds), and the high elevation site (GOM = halogen-based compounds) was affected by long-range transport in the free troposphere over the marine boundary layer into Nevada. Data collected at these two locations demonstrate that different GOM compounds exist depending on the oxidants present in the air. Measurements of GOM made by the KCl denuder in the Tekran instrument located at the low elevation site were lower than that measured using membranes by 1.7-13 times. Accurate measurements of atmospheric concentrations and chemistry of RM are necessary for proper assessment of environmental impacts, and field measurements are essential for atmospheric models, which in turn influence policy decisions.

  11. Reactive Chemical Vapor Deposition Method as New Approach for Obtaining Electroluminescent Thin Film Materials

    Directory of Open Access Journals (Sweden)

    Valentina V. Utochnikova

    2012-01-01

    Full Text Available The new reactive chemical vapor deposition (RCVD method has been proposed for thin film deposition of luminescent nonvolatile lanthanide aromatic carboxylates. This method is based on metathesis reaction between the vapors of volatile lanthanide dipivaloylmethanate (Ln(dpm3 and carboxylic acid (HCarb orH2Carb′ and was successfully used in case of HCarb. Advantages of the method were demonstrated on example of terbium benzoate (Tb(bz3 and o-phenoxybenzoate thin films, and Tb(bz3 thin films were successfully examined in the OLED with the following structure glass/ITO/PEDOT:PSS/TPD/Tb(bz3/Ca/Al. Electroluminescence spectra of Tb(bz3 showed only typical luminescent bands, originated from transitions of the terbium ion. Method peculiarities for deposition of compounds of dibasic acids H2Carb′ are established on example of terbium and europium terephtalates and europium 2,6-naphtalenedicarboxylate.

  12. Assessment of Salmonella spp. and Escherichia coli O157:H7 growth on lettuce exposed to isothermal and non-isothermal conditions.

    Science.gov (United States)

    de Oliveira Elias, Susana; Noronha, Tiago Baptista; Tondo, Eduardo Cesar

    2018-06-01

    This study aimed to assess the growth of Salmonella and Escherichia coli O157:H7 on lettuce exposed to isothermal and non-isothermal conditions. Pathogens were inoculated on lettuce separately and stored under isothermal condition at 5 °C, 10 °C, 25 °C, 37 °C for both bacteria, at 40 °C for Salmonella and 42 °C for E. coli O157:H7. Growth curves were built by fitting the data to the Baranyi's DMFit, generating R2 values greater than 0.92 for primary models. Secondary models were fitted with Ratkowsky equations, generating R2 values higher than 0.91 and RMSE lower than 0.1. Experimental data showed that both bacteria could grow at all temperatures. Also, the growth of both pathogens under non-isothermal conditions was studied simulating temperatures found from harvest to supermarkets in Brazil. Models were analysed by R2, RMSE, bias factor (Bf) and accuracy factor (Af). Salmonella and E. coli O157:H7 were able to grow in this temperature profile and the models could predict the behavior of these microorganisms on lettuce under isothermal and non-isothermal conditions. Based on the results, a negligible growth time (ς) was proposed to provide the time which lettuce could be exposed to a specific temperature and do not present an expressive growth of bacteria. The ς was developed based on Baranyi's primary model equation and on growth potential concept. ς is the value of lag phase added of the time necessary to population grow 0.5 log CFU/g. The ς of lettuce exposed to 37 °C was 1.3 h, while at 5 °C was 3.3 days. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Formulation of strongly non-local, non-isothermal dynamics for heterogeneous solids based on the GENERIC with application to phase-field modeling

    Science.gov (United States)

    Hütter, Markus; Svendsen, Bob

    2017-12-01

    The purpose of the current work is the formulation of models for conservative and non-conservative dynamics in solid systems with the help of the General Equation for the Non-Equilibrium Reversible-Irreversible Coupling (GENERIC: e.g., Grmela and Öttinger, Phys. Rev. E 56(6), 6620 (1997); Öttinger and Grmela, Phys. Rev. E 56(6), 6633 (1997)). In this context, the resulting models are inherently spatially strongly non-local (i.e., functional) and non-isothermal in character. They are applicable in particular to the modeling of phase transitions as well as mass and heat transport in multiphase, multicomponent solids. In the last part of the work, the strongly non-local model formulation is reduced to weakly non-local form with the help of generalized gradient approximation of the energy and entropy functionals. On this basis, the current model formulation is shown to be consistent with and reduce to a recent non-isothermal generalization (Gladkov et al., J. Non-Equilib. Thermodyn. 41(2), 131 (2016)) of the well-known phase-field models of Cahn and Hilliard (J. Chem. Phys. 28(2), 258 (1958)) for conservative dynamics and of Allen and Cahn (Acta Metall. 27(6), 1085 (1979)) for non-conservative dynamics. Finally, the current approach is applied to derive a non-isothermal generalization of a phase-field crystal model for binary alloys (see, e.g., Elder et al., Phys. Rev. B 75(6), 064107 (2007)).

  14. Pore-scale modelling of the combined effect of physical and chemical heterogeneity on reactive flows

    Science.gov (United States)

    Oliveira, T. D. S.; Bijeljic, B.; Blunt, M. J.

    2016-12-01

    We perform direct numerical simulations to study the combined impact of physical and chemical heterogeneity in subsurface rock to provide insights into the source of the discrepancy observed between mineral dissolution rates observed in laboratory experiments and in field-scale natural systems. The ultimate goal of this work is to use pore-scale simulation to compute upscaled properties - such as effective reaction rate - for use in larger-scale models.We present a methodology to simulate multispecies reactive flow through pore-space images obtained from micro-tomography. Using the sequential non-iterative approach, we couple the simulation of the transport equations with an advanced geochemical solver designed specifically for applications that require sequential equilibrium calculations. This geochemical solver uses novel numerical methods for the solution of multiphase chemical equilibrium and kinetics problems in a well-stirred batch model. Our model assumes that reactions can be classified into fast reactions, which are considered to be in equilibrium, and slow reactions, considered to be controlled by kinetics. This assumption of partial equilibrium simplifies the problem by replacing differential equations with algebraic ones. We allow for chemical heterogeneity of the solid phase by associating each voxel to a different mineral and reaction rate. A steady-state flow problem is solved in the pore space using a finite volume method to calculate the velocity field. Then we solve an advection-diffusion equation for the concentration and, modelling each liquid voxel as a well-mixed batch with a solid wall where applicable, we calculate reaction using the aforementioned geochemical solver. Both fluid-fluid and fluid-solid reactions are considered, geometry changes due to dissolution and precipitation are taken into account, and the velocity field is updated. We present the validation tests for acidic brine injected into rock for a range of transport (P

  15. Effect of chemical degradation on fluxes of reactive compounds – a study with a stochastic Lagrangian transport model

    Directory of Open Access Journals (Sweden)

    J. Rinne

    2012-06-01

    Full Text Available In the analyses of VOC fluxes measured above plant canopies, one usually assumes the flux above canopy to equal the exchange at the surface. Thus one assumes the chemical degradation to be much slower than the turbulent transport. We used a stochastic Lagrangian transport model in which the chemical degradation was described as first order decay in order to study the effect of the chemical degradation on above canopy fluxes of chemically reactive species. With the model we explored the sensitivity of the ratio of the above canopy flux to the surface emission on several parameters such as chemical lifetime of the compound, friction velocity, stability, and canopy density. Our results show that friction velocity and chemical lifetime affected the loss during transport the most. The canopy density had a significant effect if the chemically reactive compound was emitted from the forest floor. We used the results of the simulations together with oxidant data measured during HUMPPA-COPEC-2010 campaign at a Scots pine site to estimate the effect of the chemistry on fluxes of three typical biogenic VOCs, isoprene, α-pinene, and β-caryophyllene. Of these, the chemical degradation had a major effect on the fluxes of the most reactive species β-caryophyllene, while the fluxes of α-pinene were affected during nighttime. For these two compounds representing the mono- and sesquiterpenes groups, the effect of chemical degradation had also a significant diurnal cycle with the highest chemical loss at night. The different day and night time loss terms need to be accounted for, when measured fluxes of reactive compounds are used to reveal relations between primary emission and environmental parameters.

  16. Chemical instability of graphene oxide following exposure to highly reactive radicals in advanced oxidation processes.

    Science.gov (United States)

    Wang, Zhaohui; Sun, Linyan; Lou, Xiaoyi; Yang, Fei; Feng, Min; Liu, Jianshe

    2017-12-01

    The rapidly increasing and widespread use of graphene oxide (GO) as catalyst supports, requires further understanding of its chemical stability in advanced oxidation processes (AOPs). In this study, UV/H2O2 and UV/persulfate (UV/PS) processes were selected to test the chemical instability of GO in terms of their performance in producing highly reactive hydroxyl radicals (OH) and sulfate radicals (SO4(-)), respectively. The degradation intermediates were characterized using UV-visible absorption spectra (UV-vis), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Experimental data indicate that UV/PS process was more effective in enhancing GO degradation than the UV/H2O2 system. The overall oxygen-containing functionalities (e.g. CO, CO and OCO groups) dramatically declined. After radical attack, sheet-like GO was destructed into lots of flakes and some low-molecular-weight molecules were detected. The results suggest GO is most vulnerable against SO4(-) radical attack, which deserves special attention while GO acts as a catalyst support or even as a catalyst itself. Therefore, stability of GO and its derivatives should be carefully assessed before they are applied to SO4(-)-based AOPs. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Local and linear chemical reactivity response functions at finite temperature in density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Franco-Pérez, Marco, E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México, D.F. 09340 (Mexico); Ayers, Paul W., E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Gázquez, José L., E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México, D.F. 09340 (Mexico); Vela, Alberto, E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Departamento de Química, Centro de Investigación y de Estudios Avanzados (Cinvestav), Av. Instituto Politécnico Nacional 2508, México, D.F. 07360 (Mexico)

    2015-12-28

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.

  18. Accelerating moderately stiff chemical kinetics in reactive-flow simulations using GPUs

    CERN Document Server

    Niemeyer, Kyle E

    2014-01-01

    The chemical kinetics ODEs arising from operator-split reactive-flow simulations were solved on GPUs using explicit integration algorithms. Nonstiff chemical kinetics of a hydrogen oxidation mechanism (9 species and 38 irreversible reactions) were computed using the explicit fifth-order Runge-Kutta-Cash-Karp method, and the GPU-accelerated version performed faster than single- and six-core CPU versions by factors of 126 and 25, respectively, for 524,288 ODEs. Moderately stiff kinetics, represented with mechanisms for hydrogen/carbon-monoxide (13 species and 54 irreversible reactions) and methane (53 species and 634 irreversible reactions) oxidation, were computed using the stabilized explicit second-order Runge-Kutta-Chebyshev (RKC) algorithm. The GPU-based RKC implementation demonstrated an increase in performance of nearly 59 and 10 times, for problem sizes consisting of 262,144 ODEs and larger, than the single- and six-core CPU-based RKC algorithms using the hydrogen/carbon-monoxide mechanism. With the met...

  19. Chemical Imaging and Dynamical Studies of Reactivity and Emergent Behavior in Complex Interfacial Systems. Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Sibener, Steven J. [Univ. of Chicago, IL (United States). James Franck Inst. and Dept. of Chemistry

    2014-03-11

    This research program explored the efficacy of using molecular-level manipulation, imaging and scanning tunneling spectroscopy in conjunction with supersonic molecular beam gas-surface scattering to significantly enhance our understanding of chemical processes occurring on well-characterized interfaces. One program focus was on the spatially-resolved emergent behavior of complex reaction systems as a function of the local geometry and density of adsorbate-substrate systems under reaction conditions. Another focus was on elucidating the emergent electronic and related reactivity characteristics of intentionally constructed single and multicomponent atom- and nanoparticle-based materials. We also examined emergent chirality and self-organization in adsorbed molecular systems where collective interactions between adsorbates and the supporting interface lead to spatial symmetry breaking. In many of these studies we combined the advantages of scanning tunneling (STM) and atomic force (AFM) imaging, scanning tunneling local electronic spectroscopy (STS), and reactive supersonic molecular beams to elucidate precise details of interfacial reactivity that had not been observed by more traditional surface science methods. Using these methods, it was possible to examine, for example, the differential reactivity of molecules adsorbed at different bonding sites in conjunction with how reactivity is modified by the local configuration of nearby adsorbates. At the core of this effort was the goal of significantly extending our understanding of interfacial atomic-scale interactions to create, with intent, molecular assemblies and materials with advanced chemical and physical properties. This ambitious program addressed several key topics in DOE Grand Challenge Science, including emergent chemical and physical properties in condensed phase systems, novel uses of chemical imaging, and the development of advanced reactivity concepts in combustion and catalysis including carbon

  20. A randomized, controlled, clinical trial of a chemically-reactive heated humidifier.

    Science.gov (United States)

    Broach, S D; Durbin, C G

    2001-01-01

    Inspired gases can be warmed and humidified in a variety of ways. The effect of a chemically-reactive heated heat and moisture exchanger/hygroscopic condenser humidifier (HME/HCH) on secretions, rate of core body warming, blood loss, and time to extubation was studied in hypothermic post-cardiac surgery patients. Fifty patients with normal ventricular function, undergoing coronary bypass grafting, were randomized to receive either a conventional HME (Gibeck, Humid-Vent 1 [PN 11112], Hudson RCI, Temecula, California) or a chemically-heated HME (Thermax HCH Filter [PN 9302], Enternet Medical, Las Vegas, Nevada) following surgery or on arrival in the ICU. Effects on secretions, core temperature, postoperative bleeding, duration of intubation, and added resistance were measured. The Thermax weighs 67 g and adds 79 mL of dead space. The Humid-Vent 1 weighs 9.4 g and adds 10 mL of dead space. There was no significant difference between the 2 devices in time to extubation, blood loss, or quality or quantity of secretions. Use of the Thermax device, however, resulted in a more rapid rise in body temperature (0.299 degrees C/h with the Thermax vs 0.073 degrees C/h with the Humid-Vent 1, p = 0.001) and more added resistance (0.0672 cm H(2)O/L/s with the Thermax vs 0.0123 cm H(2)O/L/s with the Humid-Vent 1, p = 0.00000172). The Thermax chemically-heated HME results in more rapid warming of mildly hypothermic patients following cardiopulmonary bypass than does a conventional passive HME.

  1. Effect of inflow condition on near-field prediction of Large Eddy Simulations of isothermal and non-isothermal turbulent jets

    Science.gov (United States)

    Salkhordeh, Sasan; Kimber, Mark

    2017-11-01

    In order to develop an experimentally validated computational model, turbulent round jets have been studied extensively under both isothermal and non-isothermal conditions using Large Eddy Simulation (LES) methodology. Capturing the near-field physics of a turbulent jet has been a challenge when utilizing LES. To address this concern, the effect of inlet flow profile and turbulent fluctuations on the evolution of both type of jets has been analyzed in detail by performing separate large eddy simulations of the flow in the nozzle upstream of the jet inlet to accurately determine the inlet turbulent spectra. From the precursor simulations, the accurate turbulence fluctuations at the jet nozzle can be sampled and then implement to the inlet boundary of the main jet simulation. Properly specifying the turbulent fluctuations at the jet inlet was found to play a vital role in order to accurately predict key characteristics throughout the computational domain. For isothermal jets, the experimental measurements of Hussein et al. (Journal of Fluid Mechanics. 1994 Jan;258:31-75) has been simulated computationally using LES. The experimental measurement of Mi et al. (Journal of Fluid Mechanics. 2001 Apr;432:91-125) has been chosen for performing LES for a non-isothermal jet at the same Reynolds number and identical temperature difference. The LES results show good agreement for first and higher order statistics of velocities and temperatures in both near field and far-field data.

  2. Model Free Approach for Non-Isothermal Decomposition of Un-Irradiated and g-Irradiated Silver Acetate: New Route for Synthesis of Ag2O Nanoparticles

    Directory of Open Access Journals (Sweden)

    Naser M. Abd El-Salam

    2010-09-01

    Full Text Available Kinetic studies for the non-isothermal decomposition of unirradiated and γ‑irradiated silver acetate with 103 kGy total γ-ray doses were carried out in air. The results showed that the decomposition proceeds in one major step in the temperature range of (180–270 °C with the formation of Ag2O as solid residue. The non-isothermal data for un‑irradiated and γ-irradiated silver acetate were analyzed using Flynn-Wall-Ozawa (FWO and nonlinear Vyazovkin (VYZ iso-conversional methods. These free models on the investigated data showed a systematic dependence of Ea on a indicating a simple decomposition process. No significant changes in the thermal decomposition behavior of silver acetate were recorded as a result of γ-irradiation. Calcinations of γ-irradiated silver acetate (CH3COOAg at 200 °C for 2 hours only led to the formation of pure Ag2O mono-dispersed nanoparticles. X-ray diffraction, FTIR and SEM techniques were employed for characterization of the synthesized nanoparticles.

  3. Thermo-kinetic prediction of metastable and stable phase precipitation in Al–Zn–Mg series aluminium alloys during non-isothermal DSC analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lang, Peter, E-mail: pl404@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road 27, Cambridge CB3 0FS (United Kingdom); Wojcik, Tomasz [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Povoden-Karadeniz, Erwin [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Christian Doppler Laboratory “Early Stages of Precipitation”, Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Falahati, Ahmad [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Kozeschnik, Ernst [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Christian Doppler Laboratory “Early Stages of Precipitation”, Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria)

    2014-10-01

    Highlights: • Comparison of laboratory Al–Zn–Mg alloy to industrial Al 7xxx series. • Heat flow evolution during non-isothermal DSC analysis is calculated. • TEM investigations of laboratory Al–Zn–Mg alloy at three pronounced temperatures. • Simulation and modelling of precipitation sequence. • Calculation and prediction of heat flow curves of Al 7xxx series. - Abstract: The technological properties of heat treatable Al–Zn–Mg alloys originate in the morphology and distribution of metastable particles. Starting from the solution-annealed condition, this paper describes the precipitate evolution during non-isothermal temperature changes, namely continuous heating differential scanning calorimetry (DSC) analysis. The distribution and the morphology of the metastable and stable precipitates and the heat flow accompanying the precipitation process is investigated experimentally and calculated by numerical thermo-kinetic simulations. The computer simulation results of the sizes and distributions are confirmed by transmission electron microscopy (TEM). The theoretical background and the results of the investigations are discussed.

  4. Advanced Chemical Reduction of Reduced Graphene Oxide and Its Photocatalytic Activity in Degrading Reactive Black 5

    Directory of Open Access Journals (Sweden)

    Christelle Pau Ping Wong

    2015-10-01

    Full Text Available Textile industries consume large volumes of water for dye processing, leading to undesirable toxic dyes in water bodies. Dyestuffs are harmful to human health and aquatic life, and such illnesses as cholera, dysentery, hepatitis A, and hinder the photosynthetic activity of aquatic plants. To overcome this environmental problem, the advanced oxidation process is a promising technique to mineralize a wide range of dyes in water systems. In this work, reduced graphene oxide (rGO was prepared via an advanced chemical reduction route, and its photocatalytic activity was tested by photodegrading Reactive Black 5 (RB5 dye in aqueous solution. rGO was synthesized by dispersing the graphite oxide into the water to form a graphene oxide (GO solution followed by the addition of hydrazine. Graphite oxide was prepared using a modified Hummers’ method by using potassium permanganate and concentrated sulphuric acid. The resulted rGO nanoparticles were characterized using ultraviolet-visible spectrophotometry (UV-Vis, X-ray powder diffraction (XRD, Raman, and Scanning Electron Microscopy (SEM to further investigate their chemical properties. A characteristic peak of rGO-48 h (275 cm−1 was observed in the UV spectrum. Further, the appearance of a broad peak (002, centred at 2θ = 24.1°, in XRD showing that graphene oxide was reduced to rGO. Based on our results, it was found that the resulted rGO-48 h nanoparticles achieved 49% photodecolorization of RB5 under UV irradiation at pH 3 in 60 min. This was attributed to the high and efficient electron transport behaviors of rGO between aromatic regions of rGO and RB5 molecules.

  5. TMVOC-MP: a parallel numerical simulator for Three-PhaseNon-isothermal Flows of Multicomponent Hydrocarbon Mixtures inporous/fractured media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Keni; Yamamoto, Hajime; Pruess, Karsten

    2008-02-15

    TMVOC-MP is a massively parallel version of the TMVOC code (Pruess and Battistelli, 2002), a numerical simulator for three-phase non-isothermal flow of water, gas, and a multicomponent mixture of volatile organic chemicals (VOCs) in multidimensional heterogeneous porous/fractured media. TMVOC-MP was developed by introducing massively parallel computing techniques into TMVOC. It retains the physical process model of TMVOC, designed for applications to contamination problems that involve hydrocarbon fuels or organic solvents in saturated and unsaturated zones. TMVOC-MP can model contaminant behavior under 'natural' environmental conditions, as well as for engineered systems, such as soil vapor extraction, groundwater pumping, or steam-assisted source remediation. With its sophisticated parallel computing techniques, TMVOC-MP can handle much larger problems than TMVOC, and can be much more computationally efficient. TMVOC-MP models multiphase fluid systems containing variable proportions of water, non-condensible gases (NCGs), and water-soluble volatile organic chemicals (VOCs). The user can specify the number and nature of NCGs and VOCs. There are no intrinsic limitations to the number of NCGs or VOCs, although the arrays for fluid components are currently dimensioned as 20, accommodating water plus 19 components that may be either NCGs or VOCs. Among them, NCG arrays are dimensioned as 10. The user may select NCGs from a data bank provided in the software. The currently available choices include O{sub 2}, N{sub 2}, CO{sub 2}, CH{sub 4}, ethane, ethylene, acetylene, and air (a pseudo-component treated with properties averaged from N{sub 2} and O{sub 2}). Thermophysical property data of VOCs can be selected from a chemical data bank, included with TMVOC-MP, that provides parameters for 26 commonly encountered chemicals. Users also can input their own data for other fluids. The fluid components may partition (volatilize and/or dissolve) among gas, aqueous

  6. Chemical reactivity at buried-interfaces. II. Iron on nonstoichiometric and/or defected molybdenite

    Science.gov (United States)

    Zabinski, J. S.; George, T.; Tatarchuk, B. J.

    1991-01-01

    The role of defects and nonstoichioinetries in molybdenite substrates, and their influence on the chemical reactivity at buried MoS 2Fe interfaces, were investigated using conversion electron Mössbauer spectroscopy and X-ray photoelectron spectroscopy. Defects in the molybdenite crystal structure intentionally introduced by Ar + bombardment, or from the inherent structure of small MoS 2 crystallites, provide pathways for the diffusion and reaction of surface iron into the bulk of MoS 2 to form FeMo 2S 4. In comparison, iron overlayers do not react appreciably with undamaged molybdenite single crystals. Excess sulfur within molybdenite, when present, migrates towards deposited iron overlayers where it forms Fe 1- xs (pyrrhotite) and FeS (troilite). Annealing temperature determines the relative fraction of pyrrhotite to troilite and the orientational relationship between the ĉ-axis of the iron sulfide and the ĉ-axis of the molybdenite substrate. The stoichiometry of the molybdenite substrate, the presence of defects, and the annealing temperature provide a number of means to adjust the properties of the MoS 2Fe interface. Therefore, it may be possible to optimize/control processing conditions so as to impact either the tribochemical or catalytic properties of this important materials.

  7. Towards Tetraradicaloid: The Effect of Fusion Mode on Radical Character and Chemical Reactivity

    KAUST Repository

    Hu, Pan

    2015-12-30

    Open-shell singlet diradicaloids display unique electronic, non-linear optical and magnetic activity and could become novel molecular materials for organic electronics, photonics and spintronics. However, design and synthesis of diradicaloids with a significant polyradical character is a challenging task for chemists. In this article, we report our efforts toward tetraradicaloid system. A series of potential tetraradicaloids by fusion of two p-quinodimethane (p-QDM) units with naphthalene or benzene rings in different modes were synthesized. Their model compounds containing one p-QDM moiety were also prepared and compared. Their ground-state structures, physical properties and chemical reactivity were systematically investigated by various exper-imental methods such as steady-state and transient absorption, two-photon absorption, X-ray crystallographic analysis, electron spin resonance, superconducting quantum interference device and electrochemistry, assisted by density functional theory calculations. It was found that their diradical and tetraradical characters show a clear dependence on the fusion mode. Upon the introducing of more five-membered rings, the diradical characters greatly decrease. This difference can be explained by the pro-aromaticity/anti-aromaticity of the molecules as well as the intramolecular charge transfer. Our comprehensive studies provide a guideline for the design and synthesis of stable open-shell singlet polycyclic hydrocarbons with significant polyradical characters.

  8. Fluorescent silica nanoparticles with chemically reactive surface: Controlling spatial distribution in one-step synthesis.

    Science.gov (United States)

    Vera, María L; Cánneva, Antonela; Huck-Iriart, Cristián; Requejo, Felix G; Gonzalez, Mónica C; Dell'Arciprete, María L; Calvo, Alejandra

    2017-06-15

    The encapsulation of fluorescent dyes inside silica nanoparticles is advantageous to improve their quality as probes. Inside the particle, the fluorophore is protected from the external conditions and its main emission parameters remains unchanged even in the presence of quenchers. On the other hand, the amine-functionalized nanoparticle surface enables a wide range of applications, as amino groups could be easily linked with different biomolecules for targeting purposes. This kind of nanoparticle is regularly synthesized by methods that employ templates, additional nanoparticle formation or multiple pathway process. However, a one-step synthesis will be an efficient approach in this sort of bifunctional hybrid nanoparticles. A co-condensation sol-gel synthesis of hybrid fluorescent silica nanoparticle where developed. The chemical and morphological characterization of the particles where investigated by DRIFTS, XPS, SEM and SAXS. The nanoparticle fluorescent properties were also assessed by excitation-emission matrices and time resolved experiments. We have developed a one-pot synthesis method that enables the simultaneous incorporation of functionalities, the fluorescent molecule and the amino group, by controlling co-condensation process. An exhaustive characterization allows the definition of the spatial distribution of the fluorescent probe, fluorescein isothiocyanate, inside the particle and reactive amino groups on the surface of the nanoparticle with diameter about 100nm. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Chemical and Molecular Descriptors for the Reactivity of Amines with CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Anita S.; Kitchin, John R.

    2012-10-24

    Amine-based solvents are likely to play an important role in CO{sub 2} capture applications in the future, and the identification of amines with superior performance will facilitate their use in CO{sub 2} capture. While some improvements in performance will be achieved through process modifications, modifying the CO{sub 2} capture performance of an amine also implies in part an ability to modify the reactions between the amine and CO{sub 2} through development of new functionalized amines. We present a computational study of trends in the reactions between CO{sub 2} and functionalized amines with a focus on identifying molecular descriptors that determine trends in reactivity. We examine the formation of bicarbonate and carbamate species on three classes of functionalized amines: alkylamines, alkanolamines, and fluorinated alkylamines including primary, secondary and tertiary amines in each class. These functional groups span electron-withdrawing to donating behavior, hydrogen-bonding, extent of functionalization, and proximity effects of the functional groups. Electron withdrawing groups tend to destabilize CO{sub 2} reaction products, whereas electron-donating groups tend to stabilize CO{sub 2} reaction products. Hydrogen bonding stabilizes CO{sub 2} reaction products. Electronic structure descriptors based on electronegativity were found to describe trends in the bicarbonate formation energy. A chemical correlation was observed between the carbamate formation energy and the carbamic acid formation energy. The local softness on the reacting N in the amine was found to partially explain trends carbamic acid formation energy.

  10. Charge transfer effects on the chemical reactivity of Pd(x)Cu(1-x) nanoalloys.

    Science.gov (United States)

    Castegnaro, M V; Gorgeski, A; Balke, B; Alves, M C M; Morais, J

    2016-01-07

    This work reports on the synthesis and characterization of PdxCu1-x (x = 0.7, 0.5 and 0.3) nanoalloys obtained via an eco-friendly chemical reduction method based on ascorbic acid and trisodium citrate. The average size of the quasi-spherical nanoparticles (NPs) obtained by this method was about 4 nm, as observed by TEM. The colloids containing different NPs were then supported on carbon in order to produce powder samples (PdxCu1-x/C) whose electronic and structural properties were probed by different techniques. XRD analysis indicated the formation of crystalline PdCu alloys with a nanoscaled crystallite size. Core-level XPS results provided a fingerprint of a charge transfer process between Pd and Cu and its dependency on the nanoalloy composition. Additionally, it was verified that alloying was able to change the NP's reactivity towards oxidation and reduction. Indeed, the higher the amount of Pd in the nanoalloy, less oxidized are both the Pd and the Cu atoms in the as-prepared samples. Also, in situ XANES experiments during thermal treatment under a reducing atmosphere showed that the temperature required for a complete reduction of the nanoalloys depends on their composition. These results envisage the control at the atomic level of novel catalytic properties of such nanoalloys.

  11. Advantages of using non-isothermal bioreactors for the enzymatic synthesis of antibiotics: the penicillin G acylase as enzyme model

    NARCIS (Netherlands)

    Travascio, P.; Zito, E.; Maio, de A.; Schroën, C.G.P.H.; Durante, D.; Luca, de P.; Bencivenga, U.

    2002-01-01

    A new hydrophobic and catalytic membrane was prepared by immobilizing Penicillin G acylase (PGA, EC.3.5.1.11) from E. coli on a nylon membrane, chemically grafted with butylmethacrylate (BMA). Hexamethylenediamine (HMDA) and glutaraldehyde (Glu) were used as a spacer and coupling agent,

  12. Influence of thermophoresis and Soret-Dufour on magnetohydrodynamic heat and mass transfer over a non-isothermal wedge with thermal radiation and Ohmic dissipation

    Science.gov (United States)

    Pal, Dulal; Mondal, Hiranmoy

    2013-04-01

    The present paper deals with the thermophoresis particle deposition and Soret-Dufour effects on the convective flow, heat and mass transfer characteristics of an incompressible Newtonian electrically conducting fluid having temperature-dependent viscosity over a non-isothermal wedge in the presence of thermal radiation. The governing boundary layer equations are written into a dimensionless form by similarity transformations. The transformed coupled non-linear ordinary differential equations are solved numerically. The effects of various important physical parameters are analyzed in detail. It is found that the skin friction coefficient and the local Sherwood number increase with increase in the values of thermal radiation parameter in the presence of heat generation/absorption whereas reverse effect is seen on the local Nusselt number.

  13. Evaluation of a High-Throughput Peptide Reactivity Format Assay for Assessment of the Skin Sensitization Potential of Chemicals.

    Science.gov (United States)

    Wong, Chin Lin; Lam, Ai-Leen; Smith, Maree T; Ghassabian, Sussan

    2016-01-01

    The direct peptide reactivity assay (DPRA) is a validated method for in vitro assessment of the skin sensitization potential of chemicals. In the present work, we describe a peptide reactivity assay using 96-well plate format and systematically identified the optimal assay conditions for accurate and reproducible classification of chemicals with known sensitizing capacity. The aim of the research is to ensure that the analytical component of the peptide reactivity assay is robust, accurate, and reproducible in accordance with criteria that are used for the validation of bioanalytical methods. Analytical performance was evaluated using quality control samples (QCs; heptapeptides at low, medium, and high concentrations) and incubation of control chemicals (chemicals with known sensitization capacity, weak, moderate, strong, extreme, and non-sensitizers) with each of three synthetic heptapeptides, viz Cor1-C420 (Ac-NKKCDLF), cysteine- (Ac-RFAACAA), and lysine- (Ac-RFAAKAA) containing heptapeptides. The optimal incubation temperature for all three heptapeptides was 25°C. Apparent heptapeptide depletion was affected by vial material composition. Incubation of test chemicals with Cor1-C420, showed that peptide depletion was unchanged in polypropylene vials over 3-days storage in an autosampler but this was not the case for borosilicate glass vials. For cysteine-containing heptapeptide, the concentration was not stable by day 3 post-incubation in borosilicate glass vials. Although the lysine-containing heptapeptide concentration was unchanged in both polypropylene and borosilicate glass vials, the apparent extent of lysine-containing heptapeptide depletion by ethyl acrylate, differed between polypropylene (24.7%) and glass (47.3%) vials. Additionally, the peptide-chemical complexes for Cor1-C420-cinnamaldehyde and cysteine-containing heptapeptide-2, 4-dinitrochlorobenzene were partially reversible during 3-days of autosampler storage. These observations further highlight

  14. Charge transfer effects on the chemical reactivity of PdxCu1-x nanoalloys

    Science.gov (United States)

    Castegnaro, M. V.; Gorgeski, A.; Balke, B.; Alves, M. C. M.; Morais, J.

    2015-12-01

    This work reports on the synthesis and characterization of PdxCu1-x (x = 0.7, 0.5 and 0.3) nanoalloys obtained via an eco-friendly chemical reduction method based on ascorbic acid and trisodium citrate. The average size of the quasi-spherical nanoparticles (NPs) obtained by this method was about 4 nm, as observed by TEM. The colloids containing different NPs were then supported on carbon in order to produce powder samples (PdxCu1-x/C) whose electronic and structural properties were probed by different techniques. XRD analysis indicated the formation of crystalline PdCu alloys with a nanoscaled crystallite size. Core-level XPS results provided a fingerprint of a charge transfer process between Pd and Cu and its dependency on the nanoalloy composition. Additionally, it was verified that alloying was able to change the NP's reactivity towards oxidation and reduction. Indeed, the higher the amount of Pd in the nanoalloy, less oxidized are both the Pd and the Cu atoms in the as-prepared samples. Also, in situ XANES experiments during thermal treatment under a reducing atmosphere showed that the temperature required for a complete reduction of the nanoalloys depends on their composition. These results envisage the control at the atomic level of novel catalytic properties of such nanoalloys.This work reports on the synthesis and characterization of PdxCu1-x (x = 0.7, 0.5 and 0.3) nanoalloys obtained via an eco-friendly chemical reduction method based on ascorbic acid and trisodium citrate. The average size of the quasi-spherical nanoparticles (NPs) obtained by this method was about 4 nm, as observed by TEM. The colloids containing different NPs were then supported on carbon in order to produce powder samples (PdxCu1-x/C) whose electronic and structural properties were probed by different techniques. XRD analysis indicated the formation of crystalline PdCu alloys with a nanoscaled crystallite size. Core-level XPS results provided a fingerprint of a charge transfer process

  15. Chemical Identity of Interaction of Protein with Reactive Metabolite of Diosbulbin B In Vitro and In Vivo

    Directory of Open Access Journals (Sweden)

    Kai Wang

    2017-08-01

    Full Text Available Diosbulbin B (DIOB, a hepatotoxic furan-containing compound, is a primary ingredient in Dioscorea bulbifera L., a common herbal medicine. Metabolic activation is required for DIOB-induced liver injury. Protein covalent binding of an electrophilic reactive intermediate of DIOB is considered to be one of the key mechanisms of cytotoxicity. A bromine-based analytical technique was developed to characterize the chemical identity of interaction of protein with reactive intermediate of DIOB. Cysteine (Cys and lysine (Lys residues were found to react with the reactive intermediate to form three types of protein modification, including Cys adduction, Schiff’s base, and Cys/Lys crosslink. The crosslink showed time- and dose-dependence in animals given DIOB. Ketoconazole pretreatment decreased the formation of the crosslink derived from DIOB, whereas pretreatment with dexamethasone or buthionine sulfoximine increased such protein modification. These data revealed that the levels of hepatic protein adductions were proportional to the severity of hepatotoxicity of DIOB.

  16. Drop drying on surfaces determines chemical reactivity - the specific case of immobilization of oligonucleotides on microarrays

    Science.gov (United States)

    2013-01-01

    Background Drop drying is a key factor in a wide range of technical applications, including spotted microarrays. The applied nL liquid volume provides specific reaction conditions for the immobilization of probe molecules to a chemically modified surface. Results We investigated the influence of nL and μL liquid drop volumes on the process of probe immobilization and compare the results obtained to the situation in liquid solution. In our data, we observe a strong relationship between drop drying effects on immobilization and surface chemistry. In this work, we present results on the immobilization of dye labeled 20mer oligonucleotides with and without an activating 5′-aminoheptyl linker onto a 2D epoxysilane and a 3D NHS activated hydrogel surface. Conclusions Our experiments identified two basic processes determining immobilization. First, the rate of drop drying that depends on the drop volume and the ambient relative humidity. Oligonucleotides in a dried spot react unspecifically with the surface and long reaction times are needed. 3D hydrogel surfaces allow for immobilization in a liquid environment under diffusive conditions. Here, oligonucleotide immobilization is much faster and a specific reaction with the reactive linker group is observed. Second, the effect of increasing probe concentration as a result of drop drying. On a 3D hydrogel, the increasing concentration of probe molecules in nL spotting volumes accelerates immobilization dramatically. In case of μL volumes, immobilization depends on whether the drop is allowed to dry completely. At non-drying conditions, very limited immobilization is observed due to the low oligonucleotide concentration used in microarray spotting solutions. The results of our study provide a general guideline for microarray assay development. They allow for the initial definition and further optimization of reaction conditions for the immobilization of oligonucleotides and other probe molecule classes to different

  17. Analysis of chemical reactivity of aminocyclopyrachlor herbicide through the Fukui function

    Directory of Open Access Journals (Sweden)

    Mendoza-Huizar Luis Humberto

    2015-01-01

    Full Text Available We have calculated global and local DFT reactivity descriptors for aminocyclopyrachlor herbicide at the MP2/6-311++G (2d,2p level of theory in the aqueous phase. Global reactivity descriptors such as ionization energy, molecular hardness, electrophilicity, and total energies were calculated to evaluate the aminocyclopyrachlor reactivity. Local reactivity was evaluated through the Fukui function. Our results suggest that the cationic and dipolar forms of aminocyclopyrachlor exhibit similar global reactivity and they are susceptible to deamination and decarboxylation. Also, the opening of the ring might become factible through free radical attacks to the neutral form, while a similar process is caused by nucleophilic attacks on the anionic form.

  18. Solving the non-isothermal reaction-diffusion model equations in a spherical catalyst by the variational iteration method

    Science.gov (United States)

    Wazwaz, Abdul-Majid

    2017-07-01

    In this work we address the Lane-Emden boundary value problems which appear in chemical applications, biochemical applications, and scientific disciplines. We apply the variational iteration method to solve two specific models. The first problem models reaction-diffusion equation in a spherical catalyst, while the second problem models the reaction-diffusion process in a spherical biocatalyst. We obtain reliable analytical expressions of the concentrations and the effectiveness factors. Proper graphs will be used to illustrate the obtained results. The proposed analysis demonstrates reliability and efficiency applicability of the employed method.

  19. Numerical investigation of the influence of electromagnetic treatment on calcium carbonate scaling rate in non-isothermal pipe flow

    Science.gov (United States)

    Kireev, Victor; Kovaleva, Liana; Isakov, Andrey; Alimbekova, Sofya

    2017-11-01

    In the present paper, an attempt to explain the mechanisms of the electromagnetic field influence on the process of formation and deposition of calcium carbonate from supersaturated brine solution has been made using numerical modeling. The one-dimensional mathematical model of the brine laminar flow through a cylindrical tube with non-uniform temperature field is written in the form of the system of transient convection-diffusion-reaction partial differential equations describing temperature field and chemical components concentrations (Ca2+, HCO3-, CaCO3). The influence of the temperature on the kinetics of formation of calcium carbonate is taken into account and it is described in accordance with the Arrhenius equation. The kinetics of the calcium carbonate precipitation on the wall of the pipe is given on the basis of the Henry isotherm. It has been established that the electromagnetic treatment of brine solution leads to a decrease of the adsorption rate constant and Henry's constant but it does not significantly influence on the chemical reaction rate of calcium carbonate formation. It also has been shown that treatment with electromagnetic field significantly reduces the amount of calcium carbonate deposits on the wall of the pipe.

  20. Fault Reactivation Can Generate Hydraulic Short Circuits in Underground Coal Gasification—New Insights from Regional-Scale Thermo-Mechanical 3D Modeling

    Directory of Open Access Journals (Sweden)

    Christopher Otto

    2016-09-01

    Full Text Available Underground coal gasification (UCG has the potential to increase worldwide coal reserves by utilization of coal deposits not mineable by conventional methods. This involves combusting coal in situ to produce a synthesis gas, applicable for electricity generation and chemical feedstock production. Three-dimensional (3D thermo-mechanical models already significantly contribute to UCG design by process optimization and mitigation of the environmental footprint. We developed the first 3D UCG model based on real structural geological data to investigate the impacts of using isothermal and non-isothermal simulations, two different pillar widths and four varying regional stress regimes on the spatial changes in temperature and permeability, ground surface subsidence and fault reactivation. Our simulation results demonstrate that non-isothermal processes have to be considered in these assessments due to thermally-induced stresses. Furthermore, we demonstrate that permeability increase is limited to the close reactor vicinity, although the presence of previously undetected faults can introduce formation of hydraulic short circuits between single UCG channels over large distances. This requires particular consideration of potentially present sub-seismic faults in the exploration and site selection stages, since the required pillar widths may be easily underestimated in presence of faults with different orientations with respect to the regional stress regime.

  1. Fragmentation and reactivity in collisions of protonated diglycine with chemically modified perfluorinated alkylthiolate-self-assembled monolayer surfaces

    Science.gov (United States)

    Barnes, George L.; Young, Kelsey; Yang, Li; Hase, William L.

    2011-03-01

    Direct dynamics simulations are reported for quantum mechanical (QM)/molecular mechanical (MM) trajectories of N-protonated diglycine (gly2-H+) colliding with chemically modified perfluorinated octanethiolate self-assembled monolayer (SAM) surfaces. The RM1 semiempirical theory is used for the QM component of the trajectories. RM1 activation and reaction energies were compared with those determined from higher-level ab initio theories. Two chemical modifications are considered in which a head group (-COCl or -CHO) is substituted on the terminal carbon of a single chain of the SAM. These surfaces are designated as the COCl-SAM and CHO-SAM, respectively. Fragmentation, peptide reaction with the SAM, and covalent linkage of the peptide or its fragments with the SAM surface are observed. Peptide fragmentation via concerted CH2-CO bond breakage is the dominant pathway for both surfaces. HCl formation is the dominant species produced by reaction with the COCl-SAM, while for the CHO-SAM a concerted H-atom transfer from the CHO-SAM to the peptide combined with either a H-atom or radical transfer from the peptide to the surface to form singlet reaction products is the dominant pathway. A strong collision energy dependence is found for the probability of peptide fragmentation, its reactivity, and linkage with the SAM. Surface deposition, i.e., covalent linkage between the surface and the peptide, is compared to recent experimental observations of such bonding by Laskin and co-workers [Phys. Chem. Chem. Phys. 10, 1512 (2008)]. Qualitative differences in reactivity are seen between the COCl-SAM and CHO-SAM showing that chemical identity is important for surface reactivity. The probability of reactive surface deposition, which is most closely analogous to experimental observables, peaks at a value of around 20% for a collision energy of 50 eV.

  2. Unravelling chemical priming machinery in plants: the role of reactive oxygen-nitrogen-sulfur species in abiotic stress tolerance enhancement.

    Science.gov (United States)

    Antoniou, Chrystalla; Savvides, Andreas; Christou, Anastasis; Fotopoulos, Vasileios

    2016-10-01

    Abiotic stresses severely limit crop yield and their detrimental effects are aggravated by climate change. Chemical priming is an emerging field in crop stress management. The exogenous application of specific chemical agents before stress events results in tolerance enhancement and reduction of stress impacts on plant physiology and growth. However, the molecular mechanisms underlying the remarkable effects of chemical priming on plant physiology remain to be elucidated. Reactive oxygen, nitrogen and sulfur species (RONSS) are molecules playing a vital role in the stress acclimation of plants. When applied as priming agents, RONSS improve stress tolerance. This review summarizes the recent knowledge on the role of RONSS in cell signalling and gene regulation contributing to abiotic stress tolerance enhancement. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Two-phase reactive transport of an oil-soluble chemical : An NMR study

    NARCIS (Netherlands)

    Castelijns, H.J.

    2007-01-01

    An oil-soluble chemical (OSC) is a chemical substance which is soluble and chemically inert in oil, but reacts with water to form a gel. Application of an OSC can be found in oil- and gas production. An increased water production, which usually occurs in mature oil fields, can be remedied by

  4. Recent Advances in Numerical Modeling of Reactive Chemical Transport in Sulfur-Bearing Rock-Fluid Systems

    Science.gov (United States)

    Pruess, K.; Xu, T.; Apps, J. A.

    2004-05-01

    Redox processes that involve sulfur-bearing mineral phases play a crucial role in the development of ore deposits, in the degradation of mining wastes, and in geologic disposal and sequestration of sour gases. The underlying processes involve considerable physical and chemical complexity, and microbial interactions may play an important role as well. Fluid flow and mass transport typically take place in settings that involve heterogeneities on multiple scales, and may be dominated by fast preferential pathways such as fractures. Both aqueous and gas phases may actively participate in chemical interactions, and redox processes that are kinetically controlled may play a dominant role. System behavior is further complicated by non-stoichiometric and metastable mineral phases, and by feedbacks between hydraulic, chemical, and thermal effects. Effective processes and their characteristic parameters are dependent on space and time scales, and vastly different time scales can be relevant for the hydraulic and chemical systems. The complexity and diversity of sulfur-bearing rock-fluid systems is illustrated with two examples of reactive transport, the supergene enrichment of copper protores due to weathering processes during desertification over geologic time, and the disposal of gas mixtures including SO2 and H2S through underground injection. We highlight the description of physical and chemical processes, mathematical modeling approaches, numerical solution techniques, and illustrative results. Mineral assemblages in natural analog systems provide important constraints for thermodynamic data, that must be honored in order that realistic results may be obtained. Our paper concludes with a summary of current challenges for modeling reactive chemical transport. This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

  5. Evaluation of a high-throughput peptide reactivity format assay for assessment of the skin sensitization potential of chemicals

    Directory of Open Access Journals (Sweden)

    Chin Lin eWong

    2016-03-01

    Full Text Available The direct peptide reactivity assay (DPRA is a validated method for in vitro assessment of the skin sensitization potential of chemicals. In the present work, we describe a peptide reactivity assay using 96-well plate format and systematically identified the optimal assay conditions for accurate and reproducible classification of chemicals with known sensitizing capacity. The aim of the research is to ensure that the analytical component of the peptide reactivity assay is robust, accurate and reproducible in accordance with criteria that are used for the validation of bioanalytical methods. Analytical performance was evaluated using quality control samples (QCs; heptapeptides at low, medium and high concentrations and incubation of control chemicals (chemicals with known sensitization capacity, weak, moderate, strong, extreme and non-sensitizers with each of three synthetic heptapeptides, viz Cor1-C420 (Ac-NKKCDLF, cysteine- (Ac-RFAACAA and lysine- (Ac-RFAAKAA containing heptapeptides. The optimal incubation temperature for all three heptapeptides was 25°C. Apparent heptapeptide depletion was affected by vial material composition. Incubation of test chemicals with Cor1-C420, showed that peptide depletion was unchanged in polypropylene vials over 3-days storage in an autosampler but this was not the case for borosilicate glass vials. For cysteine-containing heptapeptide, the concentration was not stable by day 3 post-incubation in borosilicate glass vials. Although the lysine-containing heptapeptide concentration was unchanged in both polypropylene and borosilicate glass vials, the apparent extent of lysine-containing heptapeptide depletion by ethyl acrylate, differed between polypropylene (24.7% and glass (47.3% vials. Additionally, the peptide-chemical complexes for Cor1-C420-cinnamaldehyde and cysteine-containing heptapeptide-2,4-dinitrochlorobenzene were partially reversible during 3-days of autosampler storage. These observations further

  6. Characterization of crystallization kinetics of a Ni- (Cr, Fe, Si, B, C, P) based amorphous brazing alloy by non-isothermal differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Raju, S. [Physical Metallurgy Section, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102 (India)]. E-mail: sraju@igcar.gov.in; Kumar, N.S. Arun [Physical Metallurgy Section, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102 (India); Jeyaganesh, B. [Physical Metallurgy Section, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102 (India); Mohandas, E. [Physical Metallurgy Section, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102 (India); Mudali, U. Kamachi [Corrosion Science and Technology Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102 (India)

    2007-08-16

    The thermal stability and crystallization kinetics of a Ni- (Cr, Si, Fe, B, C, P) based amorphous brazing foil have been investigated by non-isothermal differential scanning calorimetry. The glass transition temperature T {sub g}, is found to be 720 {+-} 2 K. The amorphous alloy showed three distinct, yet considerably overlapping crystallization transformations with peak crystallization temperatures centered around 739, 778 and 853 {+-} 2 K, respectively. The solidus and liquidus temperatures are estimated to be 1250 and 1300 {+-} 2 K, respectively. The apparent activation energies for the three crystallization reactions have been determined using model free isoconversional methods. The typical values for the three crystallization reactions are: 334, 433 and 468 kJ mol{sup -1}, respectively. The X-ray diffraction of the crystallized foil revealed the presence of following compounds Ni{sub 3}B (Ni{sub 4}B{sub 3}), CrB, B{sub 2}Fe{sub 15}Si{sub 3}, CrSi{sub 2}, and Ni{sub 4.5}Si{sub 2}B.

  7. Computational solutions for non-isothermal, nonlinear magneto-convection in porous media with hall/ionslip currents and ohmic dissipation

    Directory of Open Access Journals (Sweden)

    O. Anwar Bég

    2016-03-01

    Full Text Available A theoretical and numerical study is presented to analyze the nonlinear, non-isothermal, magnetohydrodynamic (MHD free convection boundary layer flow and heat transfer in a non-Darcian, isotropic, homogenous porous medium, in the presence of Hall currents, Ionslip currents, viscous heating and Joule heating. A power-law variation is used for the temperature at the wall. The governing nonlinear coupled partial differential equations for momentum conservation in the x and z directions and heat conservation, in the flow regime are transformed from an (x, y, z coordinate system to a (ξ,η coordinate system in terms of dimensionless x-direction velocity (∂F/∂η and z-direction velocity (G and dimensionless temperature function (H under appropriate boundary conditions. Both Darcian and Forchheimer porous impedances are incorporated in both momentum equations. Computations are also provided for the variation of the x and z direction shear stress components and also local Nusselt number. Excellent correlation is achieved with a Nakamura tridiagonal finite difference scheme (NTM. The model finds applications in magnetic materials processing, MHD power generators and purification of crude oils.

  8. Rheometric Non-Isothermal Gelatinization Kinetics of Chickpea Flour-Based Gluten-Free Muffin Batters with Added Biopolymers.

    Science.gov (United States)

    Alvarez, María Dolores; Cuesta, Francisco Javier; Herranz, Beatriz; Canet, Wenceslao

    2017-01-02

    An attempt was made to analyze the elastic modulus (G0) of chickpea flour (CF)-based muffin batters made with CF alone and with added biopolymers (whey protein (WP), xanthan gum (XG), inulin (INL), and their blends) in order to evaluate their suitability to be a wheat flour (WF) substitute in muffins, and to model the heat-induced gelatinization of batters under non-isothermal heating condition from 25 ◦C to 90 ◦C. A rheological approach is proposed to determine the kinetic parameters (reaction order (n), frequency factor (k0), and activation energy (Ea)) using linearly-increasing temperature. Zero-order reaction kinetics adequately described batter gelatinization process, therefore assuming a constant rate independent of the initial G0 value. The change of the derivative of G0 with respect to time (dG0/dt) versus temperature is described by one exponential function with activation energies ranging from 118 to 180 kJ·mol-1. Control wheat gluten batter, with higher and lower starch and protein contents, respectively, than CF-based batters, exhibited the highest Ea value. Formulation of CF-based gluten-free batters with starch and protein contents closer to the levels of WF-based batter could be a strategy to decrease differences in kinetic parameters of muffin batters and, therefore, in technological characteristics of baked muffins.

  9. Rheometric Non-Isothermal Gelatinization Kinetics of Chickpea Flour-Based Gluten-Free Muffin Batters with Added Biopolymers

    Directory of Open Access Journals (Sweden)

    María Dolores Alvarez

    2017-01-01

    Full Text Available An attempt was made to analyze the elastic modulus (G0 of chickpea flour (CF-based muffin batters made with CF alone and with added biopolymers (whey protein (WP, xanthan gum (XG, inulin (INL, and their blends in order to evaluate their suitability to be a wheat flour (WF substitute in muffins, and to model the heat-induced gelatinization of batters under non-isothermal heating condition from 25 ◦C to 90 ◦C. A rheological approach is proposed to determine the kinetic parameters (reaction order (n, frequency factor (k0, and activation energy (Ea using linearly-increasing temperature. Zero-order reaction kinetics adequately described batter gelatinization process, therefore assuming a constant rate independent of the initial G0 value. The change of the derivative of G0 with respect to time (dG0/dt versus temperature is described by one exponential function with activation energies ranging from 118 to 180 kJ·mol−1. Control wheat gluten batter, with higher and lower starch and protein contents, respectively, than CF-based batters, exhibited the highest Ea value. Formulation of CF-based gluten-free batters with starch and protein contents closer to the levels of WF-based batter could be a strategy to decrease differences in kinetic parameters of muffin batters and, therefore, in technological characteristics of baked muffins.

  10. Non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 bulk metallic glass investigated by differential scanning calorimetry

    Science.gov (United States)

    Gong, Pan; Zhao, Shaofan; Wang, Xin; Yao, Kefu

    2015-07-01

    The non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 glassy alloy were investigated by differential scanning calorimetry. The activation energies corresponding to the characteristic temperatures have been calculated by Kissinger and Ozawa equations. Based on Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models, it has been found that the local activation energy is higher at the beginning of the crystallization process for the first exothermic peak. The local Avrami exponent indicates that the first-step crystallization is mainly a high-dimensional nucleation and growth with an increasing nucleation rate. According to the calculated fragility index, Ti41Zr25Be28Fe6 alloy can be classified as "strong glass former." The studied alloy also possesses a critical size up to centimeter order, and the high glass-forming ability is probably related to the relatively low Gibbs energy difference between the liquid and crystalline states. The critical cooling rate of Ti41Zr25Be28Fe6 glassy alloy has also been determined using Barandiaran-Colmenero's method.

  11. Effects of pressure, temperature, and treatment time on oscillatory rheological properties and non-isothermal gelatinization kinetics of chickpea (Cicer arietinum L.) flour slurry

    Science.gov (United States)

    Canet, W.; Cuesta, F. J.; Fuentes, R.; Alvarez, M. D.

    2017-10-01

    The effect of high hydrostatic pressure (HHP), temperature at pressurization, and treatment time at three levels (200, 400, 600 MPa; 10, 25, 50 °C 5, 15, 25 min) on the gelatinization of chickpea flour (CF) slurry during non-isothermal heating from 25 to 95 °C and gel rheological properties after subsequent cooling to 25 °C was investigated. CF gelatinization kinetics from the cross-over of elastic modulus (G’) and viscous modulus (G″) to 95 °C were considered for rate estimation. Zero-order reaction kinetics adequately described the CF gelatinization process. Structure development rate (dG‧/dt) is described by two exponential functions with activation energies ranging from 51.2 to 576.6 and –128.9 to 538.9 kJ mol–1 for downward and upward gelatinization curves, respectively. Changes in dG‧/dt vs. temperature seem to be closely related to the degree of gelatinization induced by HHP pre-treatment.

  12. Non-isothermal flow in low permeable porous media: A comparison of Richards' and two-phase flow approaches

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.; Rutqvist, J.; Gorke, U.-J.; Birkholzer, J.T.; Kolditz, O.

    2010-03-15

    The present work compares the performance of two alternative flow models for the simulation of thermal-hydraulic coupled processes in low permeable porous media: non-isothermal Richards and two-phase flow concepts. Both models take vaporization processes into account: however, the Richards model neglects dynamic pressure variations and bulk flow of the gaseous phase. For the comparison of the two approaches first published data from a laboratory experiment is studied involving thermally driven moisture flow in a partially saturated bentonite sample. Then a benchmark test of longer-term thermal-hydraulic behavior in the engineered barrier system of a geological nuclear waste repository is analyzed (DECOVALEX project). It was found that both models can be used to reproduce the vaporization process if the intrinsic permeability is relative high. However, when a thermal-hydraulic coupled problem has the same low intrinsic permeability for both the liquid and the gas phase, only the two-phase flow approach provides reasonable results.

  13. Non-isothermal decomposition kinetics of magnesite Decomposição não isotérmica de magnesita

    Directory of Open Access Journals (Sweden)

    S. Maitra

    2007-09-01

    Full Text Available Kinetics of thermal decomposition of Indian magnesite was studied by thermo-gravimetric analysis under non-isothermal condition. Coats and Redfern Integral approximation method was used to determine the kinetic parameters. Using the kinetic parameters different kinetic functions were analyzed with the experimental data to ascertain the decomposition mechanism of magnesium carbonate and it was observed that the decomposition reaction followed a contracting sphere kinetic mechanism.A cinética de decomposição térmica de magnesita indiana foi estudada por análise termogravimétrica sob condição não-isotérmica. O método da aproximação da integral de Coats e Redfern foi usado para determinar os parâmetros cinéticos. Usando estes parâmetros, foram analisadas diferentes funções cinéticas com os dados experimentais para avaliar o mecanismo de decomposição do carbonato de magnésio e foi observado que a reação de decomposição segue o mecanismo cinético de contração de esfera.

  14. A Simple Visualization of Double Bond Properties: Chemical Reactivity and UV Fluorescence

    Science.gov (United States)

    Grayson, Scott M.

    2012-01-01

    A simple, easily visualized thin-layer chromatography (TLC) staining experiment is presented that highlights the difference in reactivity between aromatic double bonds and nonaromatic double bonds. Although the stability of aromatic systems is a major theme in organic chemistry, the concept is rarely reinforced "visually" in the undergraduate…

  15. Methyl Salicylate: A Reactive Chemical Warfare Agent Surrogate to Detect Reaction with Hypochlorite (POSTPRINT)

    Science.gov (United States)

    2011-05-01

    acid (Fisher Scientific, Fair Lawn, NJ) was diluted to 1.0 M in water purified by reverse osmosis . Methods. Reactions were initially examined by...reactivity of hypochlorite neutralizants delivered onto a substrate is strongly diffusion limited, an observation likely to be useful as a

  16. Spectroscopic link between adsorption site occupation and local surface chemical reactivity

    DEFF Research Database (Denmark)

    Baraldi, A.; Lizzit, S.; Comelli, G.

    2004-01-01

    In this Letter we show that sequences of adsorbate-induced shifts of surface core level (SCL) x-ray photoelectron spectra contain profound information on surface changes of electronic structure and reactivity. Energy shifts and intensity changes of time-lapsed spectral components follow simple ru...

  17. Chemical Analysis of Complex Organic Mixtures Using Reactive Nanospray Desorption Electrospray Ionization Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Laskin, Julia; Eckert, Peter A.; Roach, Patrick J.; Heath, Brandi S.; Nizkorodov, Sergey A.; Laskin, Alexander

    2012-08-21

    Reactive nanospray desorption electrospray ionization (nano-DESI) combined with high-resolution mass spectrometry was utilized for the analysis of secondary organic aerosol produced through ozonolysis of limonene (LSOA). Previous studies showed that LSOA constituents are multifunctional compounds containing aldehyde and ketone groups. In this study, we used the selectivity of the Girard T (GT) reagent towards carbonyl compounds to examine the utility of reactive nano-DESI for the analysis of complex organic mixtures. In these experiments, 1-100 {micro}M GT solution was used as a working solvent for reactive nano-DESI analysis. Abundant products of a single addition of GT to LSOA constituents were observed at GT concentrations in excess of 10 {micro}M. We found that LSOA compounds with 18-20 carbon atoms (dimers) and 27-30 carbon atoms (trimers) react with GT through a simple addition reaction resulting in formation of the carbinolamine derivative. In contrast, reactions of GT with monomeric species result in formation of both the carbinolamine and the hydrazone derivatives. In addition, several monomers did not react with GT on the timescale of our experiment. These molecules were characterized by relatively high values of the double bond equivalent (DBE) and low oxygen content. Furthermore, because addition of a charged GT tag to a neutral molecule eliminates the discrimination against the low proton affinity compounds in the ionization process, reactive nano-DESI analysis enables quantification of individual compounds in the complex mixture. For example, we were able to estimate for the first time the amounts of dimers and trimers in the LSOA mixture. Specifically, we found that the most abundant LSOA dimer was detected at ca. 0.5 pg level and the total amount of dimers and trimers in the analyzed sample was just around 11 pg. Our results indicate that reactive nano-DESI is a valuable approach for examining the presence of specific functional groups and

  18. A Graph Theoretical and Topological Approach to Chemical Structure, Reactivity, and Dynamics

    Science.gov (United States)

    1988-10-01

    34The Pioneering Contributions of Cayley and Sylvester to the Mathematical Description of Chemical Structure," J. Mol. Struct. THEOCHEM, in press. 89. Lee...Superconductors II," (Eds., D.L. Nelson and T.F. George ), American Chemical Society, Washington, DC, 1988, pp. 54-63. 94. King, R.B. "Metal Cluster

  19. Chemical and enzymatic reductive activation of acylfulvene to isomeric cytotoxic reactive intermediates.

    Science.gov (United States)

    Pietsch, Kathryn E; Neels, James F; Yu, Xiang; Gong, Jiachang; Sturla, Shana J

    2011-11-21

    Acylfulvenes (AFs), a class of semisynthetic analogues of the sesquiterpene natural product illudin S, are cytotoxic toward cancer cells. The minor structural changes between illudin S and AFs translate to an improved therapeutic window in preclinical cell-based assays and xenograft models. AFs are, therefore, unique tools for addressing the chemical and biochemical basis of cytotoxic selectivity. AFs elicit cytotoxic responses by alkylation of biological targets, including DNA. While AFs are capable of direct alkylation, cytosolic reductive bioactivation to an electrophilic intermediate is correlated with enhanced cytotoxicity. Data obtained in this study illustrate chemical aspects of the process of AF activation. By tracking reaction mechanisms with stable isotope-labeled reagents, enzymatic versus chemical activation pathways for AF were compared for reactions involving the NADPH-dependent enzyme prostaglandin reductase 1 (PTGR1) or sodium borohydride, respectively. These two processes resulted in isomeric products that appear to give rise to similar patterns of DNA modification. The chemically activated isomer has been newly isolated and chemically characterized in this study, including an assessment of its relative stereochemistry and stability at varying pH and under bioassay conditions. In mammalian cancer cells, this chemically activated analogue was shown to not rely on further cellular activation to significantly enhance cytotoxic potency, in contrast to the requirements of AF. On the basis of this study, we anticipate that the chemically activated form of AF will serve as a useful chemical probe for evaluating biomolecular interactions independent of enzyme-mediated activation.

  20. Substitution Effects on Reactivity of N-Acyl-2-amino-2-desoxyglucopyranoses. Quantum Chemical Study

    Directory of Open Access Journals (Sweden)

    Gytis Vektaris

    2000-12-01

    Full Text Available Quantum mechanical calculations were carried out to study the molecular geometry and electronic structure of 2-amino-2-desoxyglucopyranose (AG and the Nacetyl-, N-ethanoyl-, series of N-phthalimidoalkanoyl-AG. The total charge density, electrostatic potential, spatial distribution and positions of HOMO and LUMO of N-acyl-AGs with respect to their substitutes yield information on the reactivity of the molecules.

  1. Reactive Chemical Transport Simulation to Study Geothermal Production with Mineral Recovery and Silica Scaling

    OpenAIRE

    Xu, Tianfu; Pruess, Karsten; Pham, Minh; Klein, Christopher; Sanyal, Subir

    2001-01-01

    There are vast reserves of dissolved minerals in the hypersaline brines of geothermal fields in the Imperial Valley of California. Recovery of zinc from geothermal brines is being practiced in this area, and recovery of silica, manganese, silver, lead and lithium has been or is being considered. Therefore, the ability to model mineral recovery is very significant in terms of economic development and resource utilization. The reactive geochemical transport simulator TOUGHREACT has been used to...

  2. Mixed convection flow of Eyring-Powell nanofluid over a cone and plate with chemical reactive species

    Directory of Open Access Journals (Sweden)

    Imad Khan

    Full Text Available This article concerns with mixed convection, heat and mass transfer characteristics of Eyring-Powell nanofluid over a cone and plate with chemical reactive species. The nonlinear partial differential equations (PDE’S are normalized by means of appropriate transformations. Governing equations are solved computationally by using shooting technique with fifth order Runge-Kutta scheme. A comparison for the cone and plate is given in each graph and table. The effects of emerging physical parameters such as porosity parameter, Lewis number, Prandtl number, Brownian moment, magnetic field parameter, thermophoresis parameter and mixed convection parameter on the momentum, temperature and concentration profiles are examined through graphs and tables. Keywords: Mixed convection flow, Eyring-Powell nanofluid, Chemical reaction, Cone and plate

  3. Modification of sodium channel inactivation in single myelinated nerve fibers by methionine-reactive chemicals.

    Science.gov (United States)

    Wang, G K

    1984-01-01

    Several methionine-reactive reagents, including N-bromoacetamide, N-bromosuccinimide, chloramine-T, and N-chlorosuccinimide, irreversibly slowed and prevented Na channel inactivation in single myelinated nerve fibers, whereas sulfhydryl- or tyrosine-modifying reagents had little effect. The activation process was not modified by the reagents that altered inactivation and could be modulated normally by Ca++ ions and Centruroides scorpion toxin II alpha. These results suggest that externally applied N-bromoacetamide and its related compounds specifically affect Na channel inactivation by modifying methionine residues of the channel. PMID:6331542

  4. Heavy Grignard Reagents: Synthesis, Physical and Structural Properties, Chemical Behavior, and Reactivity.

    Science.gov (United States)

    Westerhausen, Matthias; Koch, Alexander; Görls, Helmar; Krieck, Sven

    2017-01-31

    The Grignard reaction offers a straight forward atom-economic synthesis of organomagnesium halides, which undergo redistribution reactions (Schlenk equilibrium) yielding diorganylmagnesium and magnesium dihalides. The homologous organocalcium complexes (heavy Grignard reagents) gained interest only quite recently owing to several reasons. The discrepancy between the inertness of this heavy alkaline earth metal and the enormous reactivity of its organometallics hampered a vast and timely development after the first investigation more than 100 years ago. In this overview the synthesis of organocalcium reagents is described as is the durability in ethereal solvents. Aryl-, alkenyl-, and alkylcalcium halides are prepared by direct synthesis. Characteristic structural features and NMR parameters are discussed. Ligand redistribution reactions can be performed by addition of potassium tert-butanolate to ethereal solutions of arylcalcium iodides yielding soluble diarylcalcium, whereas sparingly soluble potassium iodide and calcium bis(tert-butanolate) precipitate. Furthermore, reactivity studies with respect to metalation and addition to unsaturated organic compounds and metal-based Lewis acids, leading to the formation of heterobimetallic complexes, are presented. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Fractionation, concentration and flow: A model coupling stable isotope ratios to fluid travel time and chemical reactivity

    Science.gov (United States)

    Druhan, J. L.; Maher, K.

    2014-12-01

    From the point of infiltration to the point of discharge, the chemical signature imparted to fluid flowing through catchments represents the weathering flux from the landscape. The magnitude of this flux is linked to both the time water spends in the system and the time required for reactions to influence fluid chemistry. The ratio of these characteristic times is often represented as a Damköhler number (Da), which links the parameters governing reactivity and flow. Stable isotope ratios are now commonly applied to identify and even quantify the processes and rates of primary mineral weathering, secondary mineral formation and biogeochemical cycling within catchments. Here, we derive a series of fractionation-discharge relationships for a variety of governing chemical rate laws utilizing Da coefficients. These equations can be used to isolate and quantify the effects of (1) fluid travel time distributions and (2) chemical weathering efficiency on observed stable isotope ratios. The analytical solutions are verified against multi-component reactive transport simulations of stable isotope fractionation in homogeneous and spatially correlated heterogeneous flow fields using the CrunchTope code and evaluated against field observations. We demonstrate that for an irreversible reaction, the relationship between stable isotope enrichment and reactant concentration obeys a Rayleigh-type model across a wide range of reaction rates. However, this relationship is violated when a heterogeneous travel time distribution is considered. This observation highlights an important discrepancy in the commonly assumed relationship between fractionation and concentration for irreversible reactions. We further extend our derivation to consider isotope fractionation associated with a reversible reaction (i.e. a kinetically controlled approach to equilibrium) in a steady-state flow field. Due to the dependence of the observed isotope ratio on the flow rate, kinetic enrichment and

  6. Chemical probes for molecular imaging and detection of hydrogen sulfide and reactive sulfur species in biological systems.

    Science.gov (United States)

    Lin, Vivian S; Chen, Wei; Xian, Ming; Chang, Christopher J

    2015-07-21

    Hydrogen sulfide (H2S), a gaseous species produced by both bacteria and higher eukaryotic organisms, including mammalian vertebrates, has attracted attention in recent years for its contributions to human health and disease. H2S has been proposed as a cytoprotectant and gasotransmitter in many tissue types, including mediating vascular tone in blood vessels as well as neuromodulation in the brain. The molecular mechanisms dictating how H2S affects cellular signaling and other physiological events remain insufficiently understood. Furthermore, the involvement of H2S in metal-binding interactions and formation of related RSS such as sulfane sulfur may contribute to other distinct signaling pathways. Owing to its widespread biological roles and unique chemical properties, H2S is an appealing target for chemical biology approaches to elucidate its production, trafficking, and downstream function. In this context, reaction-based fluorescent probes offer a versatile set of screening tools to visualize H2S pools in living systems. Three main strategies used in molecular probe development for H2S detection include azide and nitro group reduction, nucleophilic attack, and CuS precipitation. Each of these approaches exploits the strong nucleophilicity and reducing potency of H2S to achieve selectivity over other biothiols. In addition, a variety of methods have been developed for the detection of other reactive sulfur species (RSS), including sulfite and bisulfite, as well as sulfane sulfur species and related modifications such as S-nitrosothiols. Access to this growing chemical toolbox of new molecular probes for H2S and related RSS sets the stage for applying these developing technologies to probe reactive sulfur biology in living systems.

  7. Topological analysis (BCP) of vibrational spectroscopic studies, docking, RDG, DSSC, Fukui functions and chemical reactivity of 2-methylphenylacetic acid

    Science.gov (United States)

    Kavimani, M.; Balachandran, V.; Narayana, B.; Vanasundari, K.; Revathi, B.

    2018-02-01

    Experimental FT-IR and FT-Raman spectra of 2-methylphenylacetic acid (MPA) were recorded and theoretical values are also analyzed. The non-linear optical (NLO) properties were evaluated by determination of first (5.5053 × 10- 30 e.s.u.) and second hyper-polarizabilities (7.6833 × 10- 36 e.s.u.) of the title compound. The Multiwfn package is used to find the weak non-covalent interaction (Van der Wall interaction) and strong repulsion (steric effect) of the molecule and examined by reduced density gradient. The molecular electrostatic potential (MEP) analysis used to find the most reactive sites for the electrophilic and nucleophilic attack. The chemical activity (electronegativity, hardness, chemical softness and chemical potential) of the title compound was predicted with the help of HOMO-LUMO energy values. The natural bond orbital (NBO) has been analyzed the stability of the molecule arising from the hyper-conjugative interaction. DSSCs were discussed in structural modifications that improve the electron injection efficiency of the title compound (MPA). The Fukui functions are calculated in order to get information associated with the local reactivity properties of the title compound. The binding sites of the two receptors were reported by molecular docking field and active site bond distance is same 1.9 Å. The inhibitor of the title compound forms a stable complex with 1QYV and 2H1K proteins at the binding energies are - 5.38 and - 5.85 (Δ G in kcal/mol).

  8. Physicochemical model for reactive sputtering of hot target

    Energy Technology Data Exchange (ETDEWEB)

    Shapovalov, Viktor I., E-mail: vishapovalov@mail.ru; Karzin, Vitaliy V.; Bondarenko, Anastasia S.

    2017-02-05

    A physicochemical model for reactive magnetron sputtering of a metal target is described in this paper. The target temperature in the model is defined as a function of the ion current density. Synthesis of the coating occurs due to the surface chemical reaction. The law of mass action, the Langmuir isotherm and the Arrhenius equation for non-isothermal conditions were used for mathematical description of the reaction. The model takes into consideration thermal electron emission and evaporation of the target surface. The system of eight algebraic equations, describing the model, was solved for the tantalum target sputtered in the oxygen environment. It was established that the hysteresis effect disappears with the increase of the ion current density. - Highlights: • When model is applied for a cold target, hysteresis width is proportional to the ion current density. • Two types of processes of hot target sputtering are possible, depending on the current density: with and without the hysteresis. • Sputtering process is dominant at current densities less than 50 A/m{sup 2} and evaporation can be neglected. • For current densities over 50 A/m{sup 2} the hysteresis width reaches its maximum and the role of evaporation increases.

  9. Development of a QSAR for worst case estimates of acute toxicity of chemically reactive compounds

    NARCIS (Netherlands)

    Freidig, A.P.; Dekkers, S.; Verwei, M.; Zvinavashe, E.; Bessems, J.G.M.; Sandt, J.J.M. van de

    2007-01-01

    Future EU legislations enforce a fast hazard and risk assessment of thousands of existing chemicals. If conducted by means of present data requirements, this assessment will use a huge number of test animals and will be neither cost nor time effective. The purpose of the current research was to

  10. Quantum mechanical reactive scattering theory for simple chemical reactions: Recent developments in methodology and applications

    Energy Technology Data Exchange (ETDEWEB)

    Miller, W.H.

    1989-08-01

    It has recently been discovered that the S-matrix version of the Kohn variational principle is free of the Kohn anomalies'' that have plagued other versions and prevented its general use. This has made a major contribution to heavy particle reactive (and also to electron-atom/molecule) scattering which involve non-local (i.e., exchange) interactions that prevent solution of the coupled channel equations by propagation methods. This paper reviews the methodology briefly and presents a sample of integral and differential cross sections that have been obtained for the H + H{sub 2} {yields} H{sub 2} +H and D + H{sub 2} {yields} HD + H reactions in the high energy region (up to 1.2 eV translational energy) relevant to resonance structures reported in recent experiments. 35 refs., 11 figs.

  11. Thermal-mechanical-chemical responses of polymer-bonded explosives using a mesoscopic reactive model under impact loading.

    Science.gov (United States)

    Wang, XinJie; Wu, YanQing; Huang, FengLei

    2017-01-05

    A mesoscopic framework is developed to quantify the thermal-mechanical-chemical responses of polymer-bonded explosive (PBX) samples under impact loading. A mesoscopic reactive model is developed for the cyclotetramethylenetetranitramine (HMX) crystal, which incorporates nonlinear elasticity, crystal plasticity, and temperature-dependent chemical reaction. The proposed model was implemented in the finite element code ABAQUS by the user subroutine VUMAT. A series of three-dimensional mesoscale models were constructed and calculated under low-strength impact loading scenarios from 100m/s to 600m/s where only the first wave transit is studied. Crystal anisotropy and microstructural heterogeneity are responsible for the nonuniform stress field and fluctuations of the stress wave front. At a critical impact velocity (≥300m/s), a chemical reaction is triggered because the temperature contributed by the volumetric and plastic works is sufficiently high. Physical quantities, including stress, temperature, and extent of reaction, are homogenized from those across the microstructure at the mesoscale to compare with macroscale measurements, which will advance the continuum-level models. The framework presented in this study has important implications in understanding hot spot ignition processes and improving predictive capabilities in energetic materials. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. 3D imaging using X-Ray tomography and SEM combined FIB to study non isothermal creep damage of (111) oriented samples of γ / γ ′ nickel base single crystal superalloy MC2

    KAUST Repository

    Jouiad, Mustapha

    2012-01-01

    An unprecedented investigation consisting of the association of X-Ray tomography and Scanning Electron Microscopy combined with Focus Ion Beam (SEM-FIB) is conducted to perform a 3D reconstruction imaging. These techniques are applied to study the non-isothermal creep behavior of close (111) oriented samples of MC2 nickel base superalloys single crystal. The issue here is to develop a strategy to come out with the 3D rafting of γ\\' particles and its interaction whether with dislocation structures or/and with the preexisting voids. This characterization is uncommonly performed away from the conventional studied orientation [001] in order to feed the viscoplastic modeling leading to its improvement by taking into account the crystal anisotropy. The creep tests were performed at two different conditions: classical isothermal tests at 1050°C under 140 MPa and a non isothermal creep test consisting of one overheating at 1200°C and 30 seconds dwell time during the isothermal creep life. The X-Ray tomography shows a great deformation heterogeneity that is pronounced for the non-isothermal tested samples. This deformation localization seems to be linked to the preexisting voids. Nevertheless, for both tested samples, the voids coalescence is the precursor of the observed damage leading to failure. SEM-FIB investigation by means of slice and view technique gives 3D views of the rafted γ\\' particles and shows that γ corridors evolution seems to be the main creep rate controlling parameter. © 2012 Trans Tech Publications, Switzerland.

  13. Chemical and enzymatic reductive activation of acylfulvene to isomeric cytotoxic reactive intermediates

    OpenAIRE

    Pietsch, Kathryn E.; Neels, James F.; Yu, Xiang; Gong, Jiachang; Sturla, Shana J.

    2011-01-01

    Acylfulvenes, a class of semisynthetic analogues of the sesquiterpene natural product illudin S, are cytotoxic towards cancer cells. The minor structural changes between illudin S and AFs translate to an improved therapeutic window in preclinical cell-based assays and xenograft models. AFs are, therefore, unique tools for addressing the chemical and biochemical basis of cytotoxic selectivity. AFs elicit cytotoxic responses by alkylation of biological targets, including DNA. While AFs are capa...

  14. Selective Reactivity, Ultrafast Energy Transfer and the Development of Chemically Pumped Visible Lasers

    Science.gov (United States)

    1992-11-01

    the lne -or evew-hq instructions. searmnnq exott’q data wutrces. awirng the cctrec’Ton of’ nformation Send ,om rents egr • lomg this O.roen est crmate...additional analog systems suggests that the two concepts considered will be generic, 14. SUBJECT TERMS 1S. NUMBER OF PAGES Visible Chem. Lasers, Energy...successful production of visible chemical laser amplifiers using the highly efficient and selective formation of alkali dimer, M2 = Na2 , (Li 2 ), excited

  15. Octazethrene and Its Isomer with Different Diradical Characters and Chemical Reactivity: The Role of the Bridge Structure

    KAUST Repository

    Hu, Pan

    2016-03-11

    The fundamental relationship between structure and diradical character is important for the development of open-shell diradicaloid-based materials. In this work, we synthesized two structural isomers bearing a 2,6-naphthoquinodimethane or a 1,5-naphthoquinodimethane bridge and demonstrated that their diradical characters and chemical reactivity are quite different. The mesityl or pentafluorophenyl substituted octazethrene derivatives OZ-M/OZ-F and their isomer OZI-M (with mesityl substituents) were synthesized via an intramolecular Friedel-Crafts alkylation followed by oxidative dehydrogenation strategy from the key building blocks 4 and 11. Our detailed experimental and theoretical studies showed that both isomers have an open-shell singlet ground state with a remarkable diradical character (y0 = 0.35 and 0.34 for OZ-M and OZ-F, and y0 = 0.58 for OZI-M). Compounds OZ-M and OZ-F have good stability under the ambient environment while OZI-M has high reactivity and can be easily oxidized to a dioxo-product 15, which can be correlated to their different diradical characters. Additionally, we investigated the physical properties of OZ-M, OZ-F and 15.

  16. A case study of Asian dust storm particles: chemical composition, reactivity to SO2 and hygroscopic properties.

    Science.gov (United States)

    Ma, Qingxin; Liu, Yongchun; Liu, Chang; Ma, Jinzhu; He, Hong

    2012-01-01

    Mineral dust comprises a great fraction of the global aerosol loading, but remains the largest uncertainty in predictions of the future climate due to its complexity in composition and physico-chemical properties. In this work, a case study characterizing Asian dust storm particles was conducted by multiple analysis methods, including SEM-EDS, XPS, FT-IR, BET, TPD/mass and Knudsen cell/mass. The morphology, elemental fraction, source distribution, true uptake coefficient for SO2, and hygroscopic behavior were studied. The major components of Asian dust storm particles are aluminosilicate, SiO2 and CaCO3, with organic compounds and inorganic nitrate coated on the surface. It has a low reactivity towards SO2 with a true uptake coefficient, 5.767 x 10(-6), which limits the conversion of SO2 to sulfate during dust storm periods. The low reactivity also means that the heterogeneous reactions of SO2 in both dry and humid air conditions have little effect on the hygroscopic behavior of the dust particles.

  17. Non-isothermal crystallization kinetic study on Ga{sub 15}Se{sub 85-x}Ag{sub x} chalcogenide glasses by using differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ghamdi, A.A.; Alvi, M.A. [Department of Physics, King Abdul Aziz University, Jeddah 21589 (Saudi Arabia); Khan, Shamshad A., E-mail: shamshad_phys@yahoo.com [Department of Physics, King Abdul Aziz University, Jeddah 21589 (Saudi Arabia)

    2011-02-03

    Research highlights: > The Ag doped chalcogenide glasses can be used as optical memory, materials for holography and also be used as sensitive electrochemical electrodes or their membranes for sensors for potentiometric determination. > On the basis of the obtained experimental data, the temperature difference (T{sub c} - T{sub g}) and the enthalpy released ({Delta}H{sub c}) are found to be maximum and minimum, respectively, for Ga{sub 15}Se{sub 77}Ag{sub 8} glass, which indicate that this glass is thermally most stable in the composition range under investigation. > In our study volume nucleation with two dimensional growth is responsible during amorphous-crystallization phase transformation. > The speed of rate of crystallization, is faster with Ag at 8% in the present system. > It is observed that Ga{sub 10}Se{sub 90} has a larger probability to jump to a state of lower configurationally energy. - Abstract: At different heating rates, the glass transition temperature (T{sub g}) and the crystallization temperature (T{sub c}) are obtained from the non-isothermal differential scanning calorimetry (DSC) measurements of bulk Ga{sub 15}Se{sub 85-x}Ag{sub x} (x = 0, 2, 4, 6 and 8) chalcogenide glasses prepared by melt quenching technique. Their amorphous state was verified by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was observed that the glass transition temperature and crystallization temperatures both increase with increasing heating rates and also by increasing Ag concentration in Ga-Se system. The activation energy of crystallization (E{sub c}), activation energy of glass transition (E{sub g}), crystallization enthalpy ({Delta}H{sub c}) and the Avrami exponent (n) have been determined from the dependence of T{sub g} and T{sub c} on the heating rate ({beta}). The obtained value of the n indicates that the volume nucleation with two dimensional growth is responsible for amorphous-crystallization phase transformation. On the basis of

  18. Non-isothermal scavenging of highly soluble gaseous pollutants by rain in the atmosphere with non-uniform vertical concentration and temperature distributions

    Science.gov (United States)

    Elperin, Tov; Fominykh, Andrew; Krasovitov, Boris

    2014-08-01

    We suggest a non-isothermal one-dimensional model of precipitation scavenging of highly soluble gaseous pollutants in inhomogeneous atmosphere. When gradients of soluble trace gases' concentrations and temperature in the atmosphere are small, scavenging of gaseous pollutants is governed by two linear wave equations that describe propagation of a scavenging and temperature waves in one direction. If wash-down front velocity is much larger than the velocity of the temperature front, scavenging is determined by propagating scavenging front in the atmosphere with inhomogeneous temperature distribution. We solved the derived equation by the method of characteristics and determined scavenging coefficient and the rates of precipitation scavenging for wet removal of sulfur dioxide using measured initial distributions of trace gases and temperature in the atmosphere. It is shown that in the case of exponential initial distribution of soluble trace gases and linear temperature distribution in the atmosphere, scavenging coefficient in the region between the ground and the position of a scavenging front is proportional to rainfall rate, solubility parameter in the under-cloud region, adjacent to a bottom of a cloud and to the growth constant in the formula for the initial profile of a soluble trace gas in the atmosphere. The derived formula yields the same value of scavenging coefficient for sulfur dioxide scavenging by rain as field estimates presented by McMahon and Denison (Atmos Environ 13:571-585, 1979). It is demonstrated that in the case when the altitude variation of temperature in the atmosphere is determined by the environmental lapse rate, scavenging coefficient increases with height in the region between the scavenging front and the ground. In the case when altitude temperature variation in the atmosphere is determined by temperature inversion, scavenging coefficient decreases with height in a region between the scavenging front and the ground. Theoretical

  19. Synthesis, spectral and chemical reactivity analysis of 2,4-dinitrophenyl hydrazone having pyrrole moiety

    Science.gov (United States)

    Rawat, Poonam; Singh, R. N.

    2015-10-01

    In this paper we present combined experimental and theoretical study on a newly synthesized ethyl 2-cyano-3-[5-(2,4-dinitrophenyl)-hydrazonomethyl)-1H-pyrrol-2-yl]-acrylate (ECDHPA). Quantum chemical calculations have been performed using HF/6-31G(d,p), B3LYP/6-31G(d,p) and B3LYP/6-31++G(d,p) levels. The results obtained from quantum chemical calculations matches well with the experimental finding. Molecular electrostatic potential (MEP) surface of N17sbnd H39⋯O42dbnd N37 zone show green color having moderate electrostatic potential indicating hydrogen bonding. For the interactions N17sbnd H34⋯O42 electron density and its Laplacian (∇2ρBCP) are in the range 0.051-0.119 a.u., indicating interaction follows the Koch and Popelier criteria. The observed Nsbnd H (νN17sbnd H34) stretch of sbnd CHdbnd Nsbnd NH sbnd part of molecule at 3262 cm-1 indicate the red shift and the involvement in hydrogen bonding. Natural bond orbital (NBO) investigation shows various intramolecular interactions within molecule. Electrophilic charge transfer (ECT) has been calculated to investigate the relative electrophilic or nucleophilic behavior of reactant molecules involved in chemical reaction. The first hyperpolarizability (β0) value of ECDHPA is calculated as 22.42 × 10-30 esu. The solvent-induced effects on the non-linear optical properties (NLO) were studied using self-consistent reaction field (SCRF) method and observed that the β0 value increases as solvent polarity increases. DFT based electronic descriptors analysis reveals that studied molecule is a strong electrophile and it would undergo to form various heterocyclic compounds.

  20. Molecular Beam Studies of Hot Atom Chemical Reactions: Reactive Scattering of Energetic Deuterium Atoms

    Science.gov (United States)

    Continetti, R. E.; Balko, B. A.; Lee, Y. T.

    1989-02-01

    A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H{sub 2} -> DH + H and the substitution reaction D + C{sub 2}H{sub 2} -> C{sub 2}HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible.

  1. Molecular beam studies of hot atom chemical reactions: Reactive scattering of energetic deuterium atoms

    Energy Technology Data Exchange (ETDEWEB)

    Continetti, R.E.; Balko, B.A.; Lee, Y.T.

    1989-02-01

    A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H/sub 2/ /minus/> DH + H and the substitution reaction D + C/sub 2/H/sub 2/ /minus/> C/sub 2/HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible. 18 refs., 9 figs.

  2. Effect of incarcerated HF on the exohedral chemical reactivity of HF@C60.

    Science.gov (United States)

    Vidal, Sara; Izquierdo, Marta; Alom, Shamim; Garcia-Borràs, Marc; Filippone, Salvatore; Osuna, Sílvia; Solà, Miquel; Whitby, Richard J; Martín, Nazario

    2017-10-05

    The first chemical modification on the brand new endohedral HF@C60 is reported. In particular, the isomerization from optically pure (2S,5S)-cis-pyrrolidino[3,4:1,2][60]fullerene 2b to (2S,5R)-trans-pyrrolidino[3,4:1,2][60]fullerene 2b has been studied and compared with empty C60 (2a) and endohedral H2O@C60 (3). The comparative study shows a kinetic order for the isomerization process of H2O@C60 > HF@C60 > C60, thus confirming the effect of the incarcerated species on the zwitterionic intermediate stability.

  3. Chemically reactive flow of micropolar fluid accounting viscous dissipation and Joule heating

    Science.gov (United States)

    Khan, Muhammad Ijaz; Waqas, Muhammad; Hayat, Tasawar; Alsaedi, Ahmed

    Inspired by the several applications of non-Newtonian materials, the current investigation manages a theoretical analysis of series solutions in MHD flow of micropolar material towards nonlinear stretchable surface. Mathematical modeling is developed through viscous dissipation, mixed convection, chemical reaction and Joule heating. The phenomenon of heat and mass transfer are investigated simultaneously. The technique of local similarity transformation is utilized in order to transform the governing expressions from PDEs into ODEs. The established non-linear expressions have been tackled analytically by means of homotopic concept. The interference influences and the flow aspects are presented in the form of liquid velocity, temperature and concentration fields. The results described here demonstrate that material parameter boosts the velocity and micro-rotation velocity. It is noticed that thermal and concentration fields are higher when Eckert number and destructive chemical reaction parameter are enhanced. Besides this for the verification of the present findings, the results of presented analysis have been compared with the available works in particular situations.

  4. Chemical control over the formation and reactivity of ultra-thin films and amino-terminated layers on silicon

    Science.gov (United States)

    Rodriguez-Reyes, Juan Carlos F.

    The physical-chemical properties of several interfacial systems of technological relevance are investigated, having as a common goal the elucidation of strategies towards their atomic- and molecular-level control. Such systems can be classified in three groups: (i) ultra-thin films deposited using metalorganic precursors, (ii) metalorganic monolayers on silicon, and (iii) amine-functionalized silicon surfaces. Experimental, theoretical and chemometric methods are conveniently combined to gain a solid understanding of these systems. The ultra-thin films under investigation are titanium carbonitride (TiNC) and hafnium oxide (HfO2). Since these films may serve as substrates for deposition of other materials in circuit components, their surface chemistry needs to be understood and controlled in order to facilitate further deposition steps. The surface of a TiCN film is transformed to titanium nitride (TiN) through nitridation with ammonia; this compositional change can be reversed by the partial decomposition of ethylene molecules on the surface. The surface reactivity is observed to depend on the film composition, and therefore the method described above serves to reversibly tune the reactivity of Ti-based films. As for HfO2 films, it is found that the deposition temperature affects the degree of crystallinity of the films, which in turn affects their surface chemistry. Thus, together with a control of the composition, it is found that the reactivity of a film can be controlled precisely by controlling the crystallinity. The investigation of metalorganic monolayers on silicon surfaces was motivated by the need for understanding the first steps of metalorganic-based deposition of films, which is usually characterized by a heavy presence of contaminants that degrade the film properties. Through a combination of vibrational (infrared) spectroscopy and theoretical methods, a feasible pathway for the adsorption and decomposition of Ti[N(CH3)2]4 is found. This pathway

  5. Comparative Studies on Dyeability with Direct, Acid and Reactive Dyes after Chemical Modification of Jute with Mixed Amino Acids Obtained from Extract of Waste Soya Bean Seeds

    Science.gov (United States)

    Bhaumik, Nilendu Sekhar; Konar, Adwaita; Roy, Alok Nath; Samanta, Ashis Kumar

    2017-06-01

    Jute fabric was treated with mixed natural amino acids obtained from waste soya bean seed extract for chemical modification of jute for its cataionization and to enhance its dyeability with anionic dyes (like direct, reactive and acid dye) as well enabling soya modified jute for salt free dyeing with anionic reactive dyes maintaining its eco-friendliness. Colour interaction parameters including surface colour strength were assessed and compared for both bleached and soya-modified jute fabric for reactive dyeing and compared with direct and acid dye. Improvement in K/S value (surface colour strength) was observed for soya-modified jute even in absence of salt applied in dye bath for reactive dyes as well as for direct and acid dyes. In addition, reactive dye also shows good dyeability even in acid bath in salt free conditions. Colour fastness to wash was evaluated for bleached and soya-modified jute fabric after dyeing with direct, acid and reactive dyes are reported. Treatment of jute with soya-extracted mixed natural amino acids showed anchoring of some amino/aldemine groups on jute cellulosic polymer evidenced from Fourier Transform Infra-Red (FTIR) Spectroscopy. This amino or aldemine group incorporation in bleached jute causes its cationization and hence when dyed in acid bath for reactive dye (instead of conventional alkali bath) showed dye uptake for reactive dyes. Study of surface morphology by Scanning Electron Microscopy (SEM) of said soya-modified jute as compared to bleached jute was studied and reported.

  6. Comparative Studies on Dyeability with Direct, Acid and Reactive Dyes after Chemical Modification of Jute with Mixed Amino Acids Obtained from Extract of Waste Soya Bean Seeds

    Science.gov (United States)

    Bhaumik, Nilendu Sekhar; Konar, Adwaita; Roy, Alok Nath; Samanta, Ashis Kumar

    2017-12-01

    Jute fabric was treated with mixed natural amino acids obtained from waste soya bean seed extract for chemical modification of jute for its cataionization and to enhance its dyeability with anionic dyes (like direct, reactive and acid dye) as well enabling soya modified jute for salt free dyeing with anionic reactive dyes maintaining its eco-friendliness. Colour interaction parameters including surface colour strength were assessed and compared for both bleached and soya-modified jute fabric for reactive dyeing and compared with direct and acid dye. Improvement in K/S value (surface colour strength) was observed for soya-modified jute even in absence of salt applied in dye bath for reactive dyes as well as for direct and acid dyes. In addition, reactive dye also shows good dyeability even in acid bath in salt free conditions. Colour fastness to wash was evaluated for bleached and soya-modified jute fabric after dyeing with direct, acid and reactive dyes are reported. Treatment of jute with soya-extracted mixed natural amino acids showed anchoring of some amino/aldemine groups on jute cellulosic polymer evidenced from Fourier Transform Infra-Red (FTIR) Spectroscopy. This amino or aldemine group incorporation in bleached jute causes its cationization and hence when dyed in acid bath for reactive dye (instead of conventional alkali bath) showed dye uptake for reactive dyes. Study of surface morphology by Scanning Electron Microscopy (SEM) of said soya-modified jute as compared to bleached jute was studied and reported.

  7. Chemical characterization of diesel and hydrotreated vegetable oil (HVO) soot after reactive gas probing using diffuse reflectance FTIR spectroscopy (DRIFTS).

    Science.gov (United States)

    Tapia, A; Salgado, M S; Martín, M P; Rodríguez-Fernández, J; Rossi, M J; Cabañas, B

    2017-03-01

    A chemical characterization of diesel and hydrotreated vegetable oil (HVO) soot has been developed using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) before and after the reaction with different probe gases. Samples were generated under combustion conditions corresponding to an urban operation mode of a diesel engine and were reacted with probe gas-phase molecules in a Knudsen flow reactor. Specifically, NH2OH, O3 and NO2 were used as reactants (probes) and selected according to their reactivities towards specific functional groups on the sample surface. Samples of previously ground soot were diluted with KBr and were introduced in a DRIFTS accessory. A comparison between unreacted and reacted soot samples was made in order to establish chemical changes on the soot surface upon reaction. It was concluded that the interface of diesel and HVO soot before reaction mainly consists polycyclic aromatic hydrocarbons, nitro and carbonyl compounds, as well as ether functionalities. The main difference between both soot samples was observed in the band of the C=O groups that in diesel soot was observed at 1719 cm-1 but not in HVO soot. After reaction with probe gases, it was found that nitro compounds remain on the soot surface, that the degree of unsaturation decreases for reacted samples, and that new spectral bands such as hydroxyl groups are observed.

  8. Electron Transfer Reactivity Patterns at Chemically Modified Electrodes: Fundamentals and Application to the Optimization of Redox Recycling Amplification Systems

    Energy Technology Data Exchange (ETDEWEB)

    Bergren, Adam Johan [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Electroanalytical chemistry is often utilized in chemical analysis and Fundamental studies. Important advances have been made in these areas since the advent of chemically modified electrodes: the coating of an electrode with a chemical film in order to impart desirable, and ideally, predictable properties. These procedures enable the exploitation of unique reactivity patterns. This dissertation presents studies that investigate novel reaction mechanisms at self-assembled monolayers on gold. In particular, a unique electrochemical current amplification scheme is detailed that relies on a selective electrode to enable a reactivity pattern that results in regeneration of the analyte (redox recycling). This regenerating reaction can occur up to 250 times for each analyte molecule, leading to a notable enhancement in the observed current. The requirements of electrode selectivity and the resulting amplification and detection limit improvements are described with respect to the heterogeneous and homogeneous electron transfer rates that characterize the system. These studies revealed that the heterogeneous electrolysis of the analyte should ideally be electrochemically reversible, while that for the regenerating agent should be held to a low level. Moreover, the homogeneous reaction that recycles the analyte should occur at a rapid rate. The physical selectivity mechanism is also detailed with respect to the properties of the electrode and redox probes utilized. It is shown that partitioning of the analyte into/onto the adlayer leads to the extraordinary selectivity of the alkanethiolate monolayer modified electrode. Collectively, these studies enable a thorough understanding of the complex electrode mechanism required for successful redox recycling amplification systems, Finally, in a separate (but related) study, the effect of the akyl chain length on the heterogeneous electron transfer behavior of solution-based redox probes is reported, where an odd-even oscillation

  9. Chemical reactivity of {alpha}-isosaccharinic acid in heterogeneous alkaline systems

    Energy Technology Data Exchange (ETDEWEB)

    Glaus, M. A.; Loon, L. R. Van

    2009-05-15

    Cellulose degradation under alkaline conditions is of relevance for the mobility of many radionuclides in the near-field of a cementitious repository for radioactive waste, because metal-binding degradation products may be formed. Among these, {alpha}- isosaccharinic acid ({alpha}-ISA) is the strongest complexant. The prediction of the equilibrium concentration of {alpha}-ISA in cement pore water is therefore an important step in the assessment of the influence of cellulose degradation products on the speciation of radionuclides in such environments. The present report focuses on possible chemical transformation reactions of {alpha}-ISA in heterogeneous alkaline model systems containing either Ca(OH){sub 2} or crushed hardened cement paste. The transformation reactions were monitored by measuring the concentration of {alpha}-ISA by high performance anion exchange chromatography and the formation of reaction products by high performance ion exclusion chromatography. The overall loss of organic species from solution was monitored by measuring the concentration of non-purgeable organic carbon. The reactions were examined in diluted and compacted suspensions, at either 25 {sup o}C or 90 {sup o}C, and under anaerobic atmospheres obtained by various methods. It was found that {alpha}-ISA was transformed under all conditions tested to some extent. Reaction products, such as glycolate, formate, lactate and acetate, all compounds with less complexing strength than {alpha}-ISA, were detected. The amount of reaction products identified by the chromatographic technique applied was {approx} 50 % of the amount of {alpha}-ISA reacted. Sorption of {alpha}-ISA to Ca(OH){sub 2} contributed only to a minor extent to the loss of {alpha}-ISA from the solution phase. As the most important conclusion of the present work it was demonstrated that the presence of oxidising agents had a distinctive influence on the turnover of {alpha}-ISA. Under aerobic conditions {alpha}-ISA was

  10. Chemical exposure-response relationship between air pollutants and reactive oxygen species in the human respiratory tract

    Science.gov (United States)

    Lakey, P. S. J.; Berkemeier, T.; Tong, H.; Arangio, A. M.; Lucas, K.; Poeschl, U.; Shiraiwa, M.

    2016-12-01

    The inhalation of air pollutants such as O3 and particulate matter can lead to the formation of reactive oxygen species (ROS) which can cause damage to biosurfaces such as the lung epithelium unless they are effectively scavenged. Although the chemical processes that lead to ROS formation within the ELF upon inhalation of pollutants are well understood qualitatively, ROS concentrations within the ELF have hardly been quantified so far. The kinetic multi-layer model of surface and bulk chemistry in the epithelial lining fluid (KM-SUB-ELF) has been developed to describe chemical reactions and mass transport and to quantify ROS production rates and concentrations within the epithelial lining fluid. KM-SUB-ELF simulations suggest that O3 will rapidly saturate the ELF whereas antioxidants and surfactant species are effective scavengers of OH. High ambient concentrations of O3 can lead to the depletion of surfactants and antioxidants within the ELF, potentially leading to oxidative stress. KM-SUB-ELF reproduced measurements for the formation of H2O2 and OH due to the presence of iron, copper and quinones in surrogate lung lining fluid. This enabled ROS production rates and concentrations in the ELF to be quantified. We found that in polluted megacities the ROS concentration in the ELF due to inhalation of pollutants was at least as high as the concentrations in the ELF of patients suffering from respiratory diseases. Cu and Fe are found to be the most important redox-active aerosol components for ROS production upon inhalation of PM2.5 in polluted regions. Therefore, a reduction in the emission of Cu and Fe should be major targets of air pollution control. Chemical exposure-response relations provide a quantitative basis for assessing the relative importance of specific air pollutants in different regions of the world, showing that aerosol-induced epithelial ROS levels in polluted megacity air can be several orders of magnitude higher than in pristine rainforest air.

  11. Numerical solution of chemically reactive non-Newtonian fluid flow: Dual stratification

    Science.gov (United States)

    Rehman, Khalil Ur; Malik, M. Y.; Khan, Abid Ali; Zehra, Iffat; Zahri, Mostafa; Tahir, M.

    2017-12-01

    We have found that only a few attempts are available in the literature relatively to the tangent hyperbolic fluid flow induced by stretching cylindrical surfaces. In particular, temperature and concentration stratification effects have not been investigated until now with respect to the tangent hyperbolic fluid model. Therefore, we have considered the tangent hyperbolic fluid flow induced by an acutely inclined cylindrical surface in the presence of both temperature and concentration stratification effects. To be more specific, the fluid flow is attained with the no slip condition, which implies that the bulk motion of the fluid particles is the same as the stretching velocity of a cylindrical surface. Additionally, the flow field situation is manifested with heat generation, mixed convection and chemical reaction effects. The flow partial differential equations give a complete description of the present problem. Therefore, to trace out the solution, a set of suitable transformations is introduced to convert these equations into ordinary differential equations. In addition, a self-coded computational algorithm is executed to inspect the numerical solution of these reduced equations. The effect logs of the involved parameters are provided graphically. Furthermore, the variations of the physical quantities are examined and given with the aid of tables. It is observed that the fluid temperature is a decreasing function of the thermal stratification parameter and a similar trend is noticed for the concentration via the solutal stratification parameter.

  12. [Studying the influence of some reactive oxygen species on physical and chemical parameters of blood].

    Science.gov (United States)

    Martusevich, A K; Martusevich, A A; Solov'eva, A G; Peretyagin, S P

    2014-01-01

    The aim of this work was to estimate the dynamics of blood physical and chemical parameters when blood specimens were processed by singlet oxygen in vitro. Our experiments were executed with whole blood specimens of healthy people (n=10). Each specimen was divided into five separate portions of 5 ml. The first portion was a control (without any exposures). The second one was processed by an oxygen-ozone mixture (at ozone concentration of 500 mcg/l, the third portion--by oxygen, and the fourth and fifth ones were processed by a gas mixture with singlet oxygen (50 and 100% of generator power). In blood samples after processing we studied the activity of lactate dehydrogenase, aldehyde dehydrogenase and superoxide dismutase, erythrocyte and plasma levels of glucose and lactate, acid-base balance and the partial pressure of gases in blood. It was found out, that blood processing by singlet oxygen leads to optimization of energy, detoxication and antioxidant enzymes functioning with changes in plasma and erythrocyte level of glucose and lactate, normalization of blood gases level and acid-base balance. Our results show, that the effect of singlet oxygen on enzyme activity is more pronounced than exposure to an oxygen-ozone gas mixture.

  13. Relative humidity hysteresis in solid-state chemical reactivity: a pharmaceutical case study.

    Science.gov (United States)

    Waterman, Kenneth C; Gerst, Paul; Macdonald, Bruce C

    2012-02-01

    The chemical reaction rate for solid-state product formation in a pharmaceutical case study was monitored by equilibration with either a 75%, 21.5%, 75% relative humidity (RH) cycle ("high-low-high", HLH) or a 21.5%, 75%, 21.5% RH cycle ("low-high-low", LHL). For the HLH cycle, it was found that the degradant formation rate was reversible; that is, the rate at the final 75% RH step was equivalent to the rate at the initial 75% RH step. For samples equilibrated with the LHL cycle, a significantly higher rate of product formation was seen when the low RH condition was re-established than for the initial sample that had never been exposed to high RH. The observed hysteresis in degradant formation rate as a function of RH is not explained by hysteresis in the bulk moisture sorption isotherm, which is minimal in the case studied. It is suggested that high RH exposure impacts the solid-solid interface by either changing the amount of solid-solution present, by altering the mechanical properties of the material such that there is a greater mobility even when moisture is removed, or by altering the interfacial material to have a greater amount of moisture present even when dried. Copyright © 2011 Wiley Periodicals, Inc.

  14. Applications of the Information Theory to Problems of Molecular Electronic Structure and Chemical Reactivity

    Directory of Open Access Journals (Sweden)

    Roman F. Nalewajski

    2002-04-01

    Full Text Available Abstract: Recent studies on applications of the information theoretic concepts to molecular systems are reviewed. This survey covers the information theory basis of the Hirshfeld partitioning of molecular electron densities, its generalization to many electron probabilities, the local information distance analysis of molecular charge distributions, the charge transfer descriptors of the donor-acceptor reactive systems, the elements of a “thermodynamic” description of molecular charge displacements, both “vertical” (between molecular fragments for the fixed overall density and “horizontal” (involving different molecular densities, with the entropic representation description provided by the information theory. The average uncertainty measures of bond multiplicities in molecular “communication” systems are also briefly summarized. After an overview of alternative indicators of the information distance (entropy deficiency, missing information between probability distributions the properties of the “stockholder” densities, which minimize the entropy deficiency relative to the promolecule reference, are summarized. In particular, the surprisal analysis of molecular densities is advocated as an attractive information-theoretic tool in the electronic structure theory, supplementary to the familiar density difference diagrams. The subsystem information density equalization rules satisfied by the Hirshfeld molecular fragments are emphasized: the local values of alternative information distance densities of subsystems are equal to the corresponding global value, characterizing the molecule as a whole. These local measures of the information content are semi-quantitatively related to the molecular density difference function. In the density functional theory the effective external potentials of molecular fragments are defined, for which

  15. Influence of reactive media composition and chemical oxygen demand as methanol on autotrophic sulfur denitrification.

    Science.gov (United States)

    Qambrani, Naveed Ahmed; Oh, Sang-Eun

    2012-08-01

    Sulfur-utilizing autotrophic denitrification relies on an inorganic carbon source to reduce the nitrate by producing sulfuric acid as an end product and can be used for the treatment of wastewaters containing high levels of nitrates. In this study, sulfur-denitrifying bacteria were used in anoxic batch tests with sulfur as the electron donor and nitrate as the electron acceptor. Various medium components were tested under different conditions. Sulfur denitrification can drop the medium pH by producing acid, thus stopping the process half way. To control this mechanism, a 2:1 ratio of sulfur to oyster shell powder was used. Oyster shell powder addition to a sulfurdenitrifying reactor completely removed the nitrate. Using 50, 100, and 200 g of sulfur particles, reaction rate constants of 5.33, 6.29, and 7.96 mg(1/2)/l(1/2)·h were obtained, respectively; and using 200 g of sulfur particles showed the highest nitrate removal rates. For different sulfur particle sizes ranging from small (0.85-2.0 mm), medium (2.0-4.0 mm), and large (4.0-4.75 mm), reaction rate constants of 31.56, 10.88, and 6.23 mg(1/2)/l(1/2)·h were calculated. The fastest nitrate removal rate was observed for the smallest particle size. Addition of chemical oxygen demand (COD), methanol as the external carbon source, with the autotrophic denitrification in sufficiently alkaline conditions, created a balance between heterotrophic denitrification (which raises the pH) and sulfur-utilizing autotrophic denitrification, which lowers the pH.

  16. Structural determinant of chemical reactivity and potential health effects of quinones from natural products.

    Science.gov (United States)

    Tu, Tingting; Giblin, Daryl; Gross, Michael L

    2011-09-19

    Although many phenols and catechols found as polyphenol natural products are antioxidants and have putative disease-preventive properties, others have deleterious health effects. One possible route to toxicity is the bioactivation of the phenolic function to quinones that are electrophilic, redox-agents capable of modifying DNA and proteins. The structure-property relationships of biologically important quinones and their precursors may help understand the balance between their health benefits and risks. We describe a mass-spectrometry-based study of four quinones produced by oxidizing flavanones and flavones. Those with a C2-C3 double bond on ring C of the flavonoid stabilize by delocalization of an incipient positive charge from protonation and render the protonated quinone particularly susceptible to nucleophilic attack. We hypothesize that the absence of this double bond is one specific structural determinant that is responsible for the ability of quinones to modify biological macromolecules. Those quinones containing a C2-C3 single bond have relatively higher aqueous stability and longer half-lives than those with a double bond at the same position; the latter have short half-lives at or below ∼1 s. Quinones with a C2-C3 double bond show little ability to depurinate DNA because they are rapidly hydrated to unreactive species. Molecular-orbital calculations support that quinone hydration by a highly structure-dependent mechanism accounts for their chemical properties. The evidence taken together support a hypothesis that those flavonoids and related natural products that undergo oxidation to quinones and are then rapidly hydrated are unlikely to damage important biological macromolecules.

  17. A Structural Determinant of Chemical Reactivity and Potential Health Effects of Quinones from Natural Products

    Science.gov (United States)

    Tu, Tingting; Giblin, Daryl; Gross, Michael L.

    2011-01-01

    Although many phenols and catechols found as polyphenol natural products are antioxidants and have putative disease-preventive properties, others have deleterious health effects. One possible route to toxicity is the bioactivation of the phenolic function to quinones that are electrophilic, redox-agents capable of modifying DNA and proteins. The structure-property relationships of biologically important quinones and their precursors may help understand the balance between their health benefits and risks. We describe a mass-spectrometry-based study of four quinones produced by oxidizing flavanones and flavones. Those with a C2-C3 double bond on ring C of the flavonoid stabilize by delocalization an incipient positive charge from protonation and render the protonated quinone particularly susceptible to nucleophilic attack. We hypothesize that the absence of this double bond is one specific structural determinant that is responsible for the ability of quinones to modify biological macromolecules. Those quinones containing a C2-C3 single bond have relative higher aqueous stability and longer half-lives than those with a double bond at the same position; the latter have short half-lives at or below ~ 1 s. Quinones with a C2-C3 double bond show little ability to depurinate DNA because they are rapidly hydrated to unreactive species. Molecular-orbital calculations support that quinone hydration by a highly structure-dependent mechanism accounts for their chemical properties. The evidence taken together support a hypothesis that those flavonoids and related natural products that undergo oxidation to quinones and are then rapidly hydrated are unlikely to damage important biological macromolecules. PMID:21721570

  18. Structure, surface reactivity and physico-chemical degradation of fluoride containing phospho-silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kansal, Ishu; Goel, Ashutosh; Tulyaganov, Dilshat U.; Santos, Luis F.; Ferreira, Jose M.

    2011-03-28

    We report on the structure, apatite-forming ability and physicochemical degradation of glasses along fluorapatite [FA; Ca5(PO4)3F] - diopside (Di; CaMgSi2O6) join. A series of glasses with varying FA/Di ratio have been synthesised by melt-quenching technique. The amorphous glasses could be obtained only for compositions up to 40 wt.% of FA. The detailed structural analysis of glasses has been made by infra-red spectroscopy (FTIR), Raman spectroscopy and magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR). Silicon was predominantly present as Q2 (Si) species while phosphorus was found in orthophosphate type environment in all the investigated glasses. The apatite forming ability of glasses was investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1 h – 28 days. An extensive precipitation of calcite (CaCO3) after immersion in SBF was found in all the glasses which considerably masked the formation of hydroxyapatite [HA; Ca5(PO4)3OH] as depicted by X-ray diffraction (XRD) and FTIR. The possible mechanism favouring formation of calcite instead of HA has been explained on the basis of experimental results obtained for structure of glasses, leaching profile of glass powders in SBF solution and pH variation in SBF solution. Further, physico-chemical degradation of glasses has been studied in accordance with ISO 10993-14 “Biological evaluation of medical devices – Part 14: Identification and quantification of degradation products from ceramics” in Tris HCl and citric acid buffer. All the FA containing glasses exhibited a weight gain (instead of weight loss) after immersion in citric acid buffer due to the formation of different crystalline products.

  19. DFT/TDDFT investigation on the chemical reactivities, aromatic properties, and UV-Vis absorption spectra of 1-butoxy-4-methoxybenzenepillar[5]arene constitutional isomers.

    Science.gov (United States)

    Zhang, Jian; Ren, Shuqing

    2016-09-01

    We investigate the chemical reactivities, aromatic properties, and UV-Vis absorption spectra of four constitutional isomers of 1-butoxy-4-methoxybenzenepillar[5]arene with the DFT and TDDFT methods. These characteristics in the gas and solvent phases are discussed on the basis of electronic energy, the highest occupied molecular orbital energy, electrophilicity, global hardness, chemical potential, and nucleus-independent chemical shift. The out-of-plane component of the NICS values reveals that there is a great contrast between aromatic rings of the isomer and benzene. The most intense wavelengths of BMpillar[5]arenes are all made up of delocalized-delocalized π → π* transition.

  20. Chemical Reactivity Dynamics and Quantum Chaos in Highly Excited Hydrogen Atoms in an External Field: A Quantum Potential Approach

    Directory of Open Access Journals (Sweden)

    B. Maiti

    2002-04-01

    Full Text Available Abstract: Dynamical behavior of chemical reactivity indices like electronegativity, hardness, polarizability, electrophilicity and nucleophilicity indices is studied within a quantum fluid density functional framework for the interactions of a hydrogen atom in its ground electronic state (n = 1 and an excited electronic state (n = 20 with monochromatic and bichromatic laser pulses. Time dependent analogues of various electronic structure principles like the principles of electronegativity equalization, maximum hardness, minimum polarizability and maximum entropy have been found to be operative. Insights into the variation of intensities of the generated higher order harmonics on the color of the external laser field are obtained. The quantum signature of chaos in hydrogen atom has been studied using a quantum theory of motion and quantum fluid dynamics. A hydrogen atom in the electronic ground state (n = 1 and in an excited electronic state ( n = 20 behaves differently when placed in external oscillating monochromatic and bichromatic electric fields. Temporal evolutions of Shannon entropy, quantum Lyapunov exponent and Kolmogorov – Sinai entropy defined in terms of the distance between two initially close Bohmian trajectories for these two cases show marked differences. It appears that a larger uncertainty product and a smaller hardness value signal a chaotic behavior.

  1. Toxic inhibition of smooth muscle contractility by plant-derived sesquiterpenes caused by their chemically reactive alpha-methylenebutyrolactone functions.

    Science.gov (United States)

    Hay, A. J.; Hamburger, M.; Hostettmann, K.; Hoult, J. R.

    1994-01-01

    1. Previous studies have shown that extracts of feverfew (Tanacetum parthenium) and parthenolide, a sesquiterpene alpha-methylenebutyrolactone obtained from it, inhibit smooth muscle contractility in a time-dependent, non-specific and irreversible manner. 2. The hypothesis that this toxic effect is due specifically to the presence in the sesquiterpene lactone of the potentially reactive alpha-methylene function was tested on rabbit isolated aortic ring preparations. This was done (a) by comparing the effects of two plant-derived sesquiterpene lactones purified from yellow star thistle (Centaurea solstitialis): cynaropicrin (an alpha-methylenebutyrolactone) and solstitialin 13-acetate (lacking the alpha-methylene function), and (b) by chemically inactivating the alpha-methylene functions in cynaropicrin and parthenolide by reaction with cysteine. 3. The results show that the characteristic smooth muscle inhibitory profile is demonstrated by the two alpha-methylenebutyrolactones (parthenolide and cynaropicrin), but not by the compound lacking this functional group (solstitialin 13-acetate), or by those previously active compounds in which it has been inactivated with cysteine. 4. Thus the alpha-methylene function is critical for this aspect of the toxic pharmacological profile of the sesquiterpene butyrolactones, which are natural products widely distributed in the Compositae family of flowering plants. PMID:8032668

  2. Eulerian-Lagrangian simulation of non-isothermal gas-solid flows: particle-turbulence interactions in pipe flows; Simulation eulerienne-lagrangienne d'ecoulements gaz-solide non isothermes: interactions particules-turbulence, application aux ecoulements en conduite

    Energy Technology Data Exchange (ETDEWEB)

    Chagras, V.

    2004-03-15

    The aim of this work is to contribute to the numerical modeling of turbulent gas-solid flows in vertical or horizontal non isothermal pipes, which can be found in many industrial processes (pneumatic transport, drying, etc). The model is based on an Eulerian-Lagrangian approach allowing a fine description of the interactions between the two phases (action of the fluid upon the particles (dispersion), action of the particles upon the fluid (two way coupling) and between particles (collisions)), more or less influential according to the characteristics of the flow. The influence of the gas phase turbulence on the particle motion is taken into account using a non-isotropic dispersion model, which allows the generation of velocity and temperature fluctuations of the fluid seen by the particles. The numerical developments brought to the model for vertical and horizontal pipe flow have been validated by comparison with available experimental results from the literature. The sensitivity tests highlight the influence of the dispersion model, collisions and turbulence modulation (direct and non direct modifications ) on the dynamic and thermal behavior of the suspension. The model is able to predict the heat exchanges in the presence of particles for a wide range of flows in vertical and horizontal pipes. However numerical problems still exist in two-way coupling for very small particles and loading ratios above one. This is related to the problems encountered when modeling the coupling terms between the two phases (parameters C{sub {epsilon}}{sub 2} and C{sub {epsilon}}{sub 3} ) involved in the turbulence dissipation balance. (author)

  3. Chemical Reactivity of Isoproturon, Diuron, Linuron, and Chlorotoluron Herbicides in Aqueous Phase: A Theoretical Quantum Study Employing Global and Local Reactivity Descriptors

    Directory of Open Access Journals (Sweden)

    Luis Humberto Mendoza-Huizar

    2015-01-01

    Full Text Available We have calculated global and local DFT reactivity descriptors for isoproturon, diuron, linuron, and chlorotoluron herbicides at the MP2/6-311++G(2d,2p level of theory. The results suggest that, in aqueous conditions, chlorotoluron, linuron, and diuron herbicides may be degraded by elimination of urea moiety through electrophilic attacks. On the other hand, electrophilic, nucleophilic, and free radical attacks on isoproturon may cause the elimination of isopropyl fragment.

  4. Chemical reactivity of C-F bonds attached to graphene with diamines depending on their nature and location.

    Science.gov (United States)

    Li, Baoyin; He, Taijun; Wang, Zaoming; Cheng, Zheng; Liu, Yang; Chen, Teng; Lai, Wenchuan; Wang, Xu; Liu, Xiangyang

    2016-06-29

    The attachment of fluorine to graphene is a facile means to activate the carbon bonds for subsequent covalent bonding to other molecules for the preparation of desired graphene derivatives. Therefore, an insight into the chemical reactivity of fluorinated graphene (FG) is very essential to enable precise control of the composition and structure of the final products. In this study, FG has been treated with various mass amounts of poly(oxypropylene)diamine (PEA) ranging from starvation to saturation to explore the dependence of a substitution reaction of diamines on the nature and location (attached onto the basal planes or along defects or edges) of C-F bonds. X-ray photoelectron spectroscopy directly tracked the atomic percentage of fluorine present and the carbon 1s bonding state, showing that the grafting ratio of diamines gradually increases with increased diamine mass ratio. The varying of the types and orientation of C-F bonds characterized by polarized attenuated total reflectance Fourier transform infrared spectroscopy indicates that "covalent" C-F bonds are more sensitive to the substitution reaction of diamines than ''semi-ionic'' C-F bonds, and the C-F bonds attached onto basal planes more preferably participate in the functionalization reaction of diamines than that of C-F bonded on non-coplanar regions (edges or defects). The one-dimensional expansion along the graphene c-axis shown by wide angle X-ray diffraction provides further evidence on the preferred functionalization reaction of C-F attached on the basal planes, resulting in a change of the average intersheet distance by various magnitudes.

  5. A DFT study of the chemical reactivity of cimetidine A, C and D in the gas, H2O, MeOH and EtOH solvents

    Directory of Open Access Journals (Sweden)

    Mendoza Huizar Luis Humberto

    2017-01-01

    In the present work, we have analyzed the chemical reactivity of cimetidine A, C and D in different solvents; through the evaluation of global and local DFT reactivity descriptors. In the gas, MeOH and EtOH phases, cimetidine A, C and D exhibit energy differences of 3-11 kcal mol-1. But, in the aqueous phase, cimetidine A and D are approximately isoenergetic. The values of the hardness indicate that cimetidine A, C and D are more reactive in the presence of a solvent than in the gas phase. Also, our results suggest that CimC and CimD are better nucleophiles that CimA. The Fukui Function values suggest that the more reactive sites of CimA are not modified in the different solvents. In the case of CimC, the more reactive sites to electrophilic and free radical attacks are located on the thioether sulfur. For CimD, the number and place of the electrophilic and free radical sites are independent of the solvent.

  6. Comparison of CH, C3, CHF, and CF2 surface reactivities during plasma-enhanced chemical vapor deposition of fluorocarbon films.

    Science.gov (United States)

    Liu, Dongping; Cuddy, Michael F; Fisher, Ellen R

    2009-04-01

    The overall character of films deposited using plasma-enhanced chemical vapor deposition relies on the interactions of gas-phase molecules with the depositing film surface. The steady-state surface interactions of CH, C3, CHF, and CF2 have been characterized at the interface of depositing fluorocarbon (FC) films using the imaging of radicals interacting with surfaces (IRIS) technique. IRIS measurements show that the relative gas-phase densities of CH, C3, CHF, and CF2 in mixed FC plasmas depend on the CH2F2/C3F8 ratio. Similar results are found using optical emission spectroscopy to monitor the production of excited-state plasma species. The effects of plasma parameters, such as the feed gas composition and substrate bias on the radical surface, were measured. Under all conditions, the surface reactivity for CH radicals is near unity, whereas those for C3, CHF, and CF2 exhibit very low surface reactivity but also show some dependence on experimental parameters. Under some conditions, CF2 and CHF are generated at the surface of the depositing film. Surface reactivity measurements indicate that CF2, CHF, and C3 may contribute to FC growth only when adsorbing at reactive sites at the film surface. Moreover, the low surface reactivities of singlet species such as C3, CF2, and CHF may be related to the electronic configuration of the molecules.

  7. Non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} on dehydrogenation high-energy ball milled MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tiebang, E-mail: tiebangzhang@nwpu.edu.cn; Hou, Xiaojiang; Hu, Rui; Kou, Hongchao; Li, Jinshan

    2016-11-01

    MgH{sub 2}-M (M = TiF{sub 3} or Nb{sub 2}O{sub 5} or both of them) composites prepared by high-energy ball milling are used in this work to illustrate the dehydrogenation behavior of MgH{sub 2} with the addition of catalysts. The phase compositions, microstructures, particle morphologies and distributions of MgH{sub 2} with catalysts have been evaluated. The non-isothermal synergetic catalytic-dehydrogenation effect of TiF{sub 3} and Nb{sub 2}O{sub 5} evaluated by differential scanning calorimetry gives the evidences that the addition of catalysts is an effective strategy to destabilize MgH{sub 2} and reduce hydrogen desorption temperatures and activation energies. Depending on additives, the desorption peak temperatures of catalyzed MgH{sub 2} reduce from 417 °C to 341 °C for TiF{sub 3} and from 417 °C to 336 °C for Nb{sub 2}O{sub 5}, respectively. The desorption peak temperature reaches as low as 310 °C for MgH{sub 2} catalyzed by TiF{sub 3} coupling with Nb{sub 2}O{sub 5}. The non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} is mainly attributed to electronic exchange reactions with hydrogen molecules, which improve the recombination of hydrogen atoms during dehydrogenation process of MgH{sub 2}. - Highlights: • Catalytic surface for MgH{sub 2} is achieved by high-energy ball milling. • Non-isothermal dehydrogenation behavior of MgH{sub 2} with TiF{sub 3} and/or Nb{sub 2}O{sub 5} is illustrated. • Dehydrogenation activation energies of synergetic catalyzed MgH{sub 2} are obtained. • Synergetic catalytic-dehydrogenation mechanism of TiF{sub 3} and Nb{sub 2}O{sub 5} is proposed.

  8. Revealing the importance of linkers in K-series oxime reactivators for tabun-inhibited AChE using quantum chemical, docking and SMD studies

    Science.gov (United States)

    Ghosh, Shibaji; Chandar, Nellore Bhanu; Jana, Kalyanashis; Ganguly, Bishwajit

    2017-08-01

    Inhibition of acetylcholinesterase (AChE) with organophosphorus compounds has a detrimental effect on human life. Oxime K203 seems to be one of the promising reactivators for tabun-inhibited AChE than (K027, K127, and K628). These reactivators differ only in the linker units between the two pyridinium rings. The conformational analyses performed with quantum chemical RHF/6-31G* level for K027, K127, K203 and K628 showed that the minimum energy conformers have different orientations of the active and peripheral pyridinium rings for these reactivator molecules. K203 with (-CH2-CH=CH-CH2-) linker unit possesses more open conformation compared to the other reactivators. Such orientation of K203 experiences favorable interaction with the surrounding residues of catalytic anionic site (CAS) and peripheral anionic site (PAS) of tabun-inhibited AChE. From the steered molecular dynamics simulations, it has been observed that the oxygen atom of the oxime group of K203 reactivator approaches nearest to the P-atom of the SUN203 (3.75 Å) at lower time scales (less than 1000 ps) as compared to the other reactivators. K203 experiences less number of hydrophobic interaction with the PAS residues which is suggested to be an important factor for the efficient reactivation process. In addition, K203 crates large number of H-bonding with CAS residues SUN203, Phe295, Tyr337, Phe338 and His447. K203 barely changes its conformation during the SMD simulation process and hence the energy penalty to adopt any other conformation is minimal in this case as compared to the other reactivators. The molecular mechanics and Poisson-Boltzmann surface area binding energies obtained for the interaction of K203 inside the gorge of tabun inhibited AChE is substantially higher (-290.2 kcal/mol) than the corresponding K628 reactivator (-260.4 kcal/mol), which also possess unsaturated aromatic linker unit.

  9. Non-isothermal crystallization kinetics and fragility of (Cu{sub 46}Zr{sub 47}Al{sub 7}){sub 97}Ti{sub 3} bulk metallic glass investigated by differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Man, E-mail: zhuman0428@126.com [School of Materials and Chemical Engineering, Xi’an Technological University, Xi’an, Shaanxi 710032 (China); Li, Junjie [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, Shaanxi 710072 (China); Yao, Lijuan; Jian, Zengyun; Chang, Fang’e [School of Materials and Chemical Engineering, Xi’an Technological University, Xi’an, Shaanxi 710032 (China); Yang, Gencang [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, Shaanxi 710072 (China)

    2013-08-10

    Highlights: • Non-isothermal crystallization kinetics of (Cu{sub 46}Zr{sub 47}Al{sub 7}){sub 97}Ti{sub 3} BMGs was studied. • Two-stage of crystallization process is confirmed by DSC. • The nucleation process is difficult than growth process during crystallization. • The second crystallization process is the most sensitive to heating rate. • Kinetic fragility index is evaluated suggesting it is an intermediate glass. - Abstract: In this paper, bulk metallic glasses with the composition of (Cu{sub 46}Zr{sub 47}Al{sub 7}){sub 97}Ti{sub 3} were prepared by copper mold casting technique. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to investigate its structure and non-isothermal crystallization kinetics. DSC traces revealed that it undergoes two-stage crystallization. The activation energies corresponding to the characteristic temperatures have been calculated, and the results reveal that the as-cast alloys have a good thermal stability in thermodynamics. Based on Kissinger equation, the activation energies for glass transition, the first and second crystallization processes were obtained as 485 ± 16 kJ/mol, 331 ± 7 kJ/mol and 210 ± 3 kJ/mol, respectively, suggesting that the nucleation process is more difficult than the grain growth process. The fitting curves using Lasocka's empirical relation show that the influence of the heating rate for crystallization is larger than glass transition. Furthermore, the kinetic fragility for (Cu{sub 46}Zr{sub 47}Al{sub 7}){sub 97}Ti{sub 3} bulk metallic glasses is evaluated. Depending on the fragility index, (Cu{sub 46}Zr{sub 47}Al{sub 7}){sub 97}Ti{sub 3} bulk metallic glasses should be considered as “intermediate glasses”.

  10. A Frontier Orbital Study with Ab Initio Molecular Dynamics of the Effects of Solvation on Chemical Reactivity: Solvent-Induced Orbital Control in FeO-Activated Hydroxylation Reactions

    NARCIS (Netherlands)

    Bernasconi, L.; Baerends, E.J.

    2013-01-01

    Solvation effects on chemical reactivity are often rationalized using electrostatic considerations: the reduced stabilization of the transition state results in higher reaction barriers and lower reactivity in solution. We demonstrate that the effect of solvation on the relative energies of the

  11. Characterization of the chemical reactivity and nephrotoxicity of N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine sulfoxide, a potential reactive metabolite of trichloroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Irving, Roy M. [Molecular and Environmental Toxicology Center, University of Wisconsin-Madison, Madison, WI 53706 (United States); Pinkerton, Marie E. [Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706 (United States); Elfarra, Adnan A., E-mail: elfarra@svm.vetmed.wisc.edu [Molecular and Environmental Toxicology Center, University of Wisconsin-Madison, Madison, WI 53706 (United States); Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2013-02-15

    N-Acetyl-S-(1,2-dichlorovinyl)-L-cysteine (NA-DCVC) has been detected in the urine of humans exposed to trichloroethylene and its related sulfoxide, N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine sulfoxide (NA-DCVCS), has been detected as hemoglobin adducts in blood of rats dosed with S-(1,2-dichlorovinyl)-L-cysteine (DCVC) or S-(1,2-dichlorovinyl)-L-cysteine sulfoxide (DCVCS). Because the in vivo nephrotoxicity of NA-DCVCS was unknown, in this study, male Sprague–Dawley rats were dosed (i.p.) with 230 μmol/kg b.w. NA-DCVCS or its potential precursors, DCVCS or NA-DCVC. At 24 h post treatment, rats given NA-DCVC or NA-DCVCS exhibited kidney lesions and effects on renal function distinct from those caused by DCVCS. NA-DCVC and NA-DCVCS primarily affected the cortico-medullary proximal tubules (S{sub 2}–S{sub 3} segments) while DCVCS primarily affected the outer cortical proximal tubules (S{sub 1}–S{sub 2} segments). When NA-DCVCS or DCVCS was incubated with GSH in phosphate buffer pH 7.4 at 37 °C, the corresponding glutathione conjugates were detected, but NA-DCVC was not reactive with GSH. Because NA-DCVCS exhibited a longer half-life than DCVCS and addition of rat liver cytosol enhanced GSH conjugate formation, catalysis of GSH conjugate formation by the liver could explain the lower toxicity of NA-DCVCS in comparison with DCVCS. Collectively, these results provide clear evidence that NA-DCVCS formation could play a significant role in DCVC, NA-DCVC, and trichloroethylene nephrotoxicity. They also suggest a role for hepatic metabolism in the mechanism of NA-DCVC nephrotoxicity. - Highlights: ► NA-DCVCS and NA-DCVC toxicity are distinct from DCVCS toxicity. ► NA-DCVCS readily reacts with GSH to form mono- and di-GSH conjugates. ► Liver glutathione S-transferases enhance NA-DCVCS GSH conjugate formation. ► Renal localization of lesions suggests a role for NA-DCVCS in TCE nephrotoxicity.

  12. Distillation and isolation of commodity chemicals from Bio-oil made by tail-gas reactive prolysis

    Science.gov (United States)

    Owing to instabilities, very little has been accomplished with regards to simple cost-effective separations of fast-pyrolysis bio-oil. However, recent developments in the use of tail-gas reactive pyrolysis (TGRP) (Mullen and Boateng 2013) provide higher quality bio-oils that are thermally stable. We...

  13. Assessment of conformational, spectral, antimicrobial activity, chemical reactivity and NLO application of Pyrrole-2,5-dicarboxaldehyde bis(oxaloyldihydrazone)

    Science.gov (United States)

    Rawat, Poonam; Singh, R. N.

    2015-04-01

    An orange colored pyrrole dihydrazone: Pyrrole-2,5-dicarboxaldehyde bis(oxaloyldihydrazone) (PDBO) has been synthesized by reaction of oxalic acid dihydrazide with 2,5 diformyl-1H-pyrrole and has been characterized by spectroscopic analysis (1H, 13C NMR, UV-visible, FT-IR and DART Mass). The properties of the compound has been evaluated using B3LYP functional and 6-31G(d,p)/6-311+G(d,p) basis set. The symmetric (3319, 3320 cm-1) and asymmetric (3389, 3382 cm-1) stretching wave number confirm free NH2 groups in PDBO. NBO analysis shows, inter/intra molecular interactions within the molecule. Topological parameters have been analyzed by QTAIM theory and provide the existence of intramolecular hydrogen bonding (N-H⋯O). The local reactivity descriptors analyses determine the reactive sites within molecule. The calculated first hyperpolarizability value (β0 = 23.83 × 10-30 esu) of pyrrole dihydrazone shows its suitability for non-linear optical (NLO) response. The preliminary bioassay suggested that the PDBO exhibits relatively good antibacterial and fungicidal activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes, Candida albicans, Aspergillus niger. The local reactivity descriptors - Fukui functions (fk+, fk-), local softnesses (sk+, sk-) and electrophilicity indices (ωk+, ωk-) analyses have been used to determine the reactive sites within molecule.

  14. Stereo-specific glucose consumption may be used to distinguish between chemical and biological reactivity on Mars: a preliminary test on Earth.

    Science.gov (United States)

    Sun, Henry J; Saccomanno, Vienna; Hedlund, Brian; McKay, Christopher P

    2009-06-01

    Two alternative hypotheses explain the degradation of organics in the Viking Labeled Release experiment on Mars. Either martian soil contains live indigenous microorganisms or it is sterile but chemically reactive. These two possibilities could be distinguished by the use of pure preparations of glucose isomers. In the laboratory, selected eukaryotes, bacteria, and archaea consumed only D-glucose, not L-glucose, while permanganate oxidized both isomers. On Mars, selective consumption of either D- or L-glucose would constitute evidence for biological activity.

  15. Formation of distinctive structures of GaN by inductively-coupled-plasma and reactive ion etching under optimized chemical etching conditions

    Directory of Open Access Journals (Sweden)

    N. Okada

    2017-06-01

    Full Text Available We focused on inductively coupled plasma and reactive ion etching (ICP–RIE for etching GaN and tried to fabricate distinctive GaN structures under optimized chemical etching conditions. To determine the optimum chemical etching conditions, the flow rates of Ar and Cl2, ICP power, and chamber pressure were varied in the etching of c-plane GaN layers with stripe patterns. It was determined that the combination of Ar and Cl2 flow rates of 100 sccm, chamber pressure of 7 Pa, and ICP power of 800 W resulted in the most enhanced reaction, yielding distinctive GaN structures such as pillars with inverted mesa structures for c-plane GaN and a semipolar GaN layer with asymmetric inclined sidewalls. The selectivity and etching rate were also investigated.

  16. Generation and Role of Reactive Oxygen and Nitrogen Species Induced by Plasma, Lasers, Chemical Agents, and Other Systems in Dentistry

    Science.gov (United States)

    Jha, Nayansi; Ryu, Jae Jun

    2017-01-01

    The generation of reactive oxygen and nitrogen species (RONS) has been found to occur during inflammatory procedures, during cell ischemia, and in various crucial developmental processes such as cell differentiation and along cell signaling pathways. The most common sources of intracellular RONS are the mitochondrial electron transport system, NADH oxidase, and cytochrome P450. In this review, we analyzed the extracellular and intracellular sources of reactive species, their cell signaling pathways, the mechanisms of action, and their positive and negative effects in the dental field. In dentistry, ROS can be found—in lasers, photosensitizers, bleaching agents, cold plasma, and even resin cements, all of which contribute to the generation and prevalence of ROS. Nonthermal plasma has been used as a source of ROS for biomedical applications and has the potential for use with dental stem cells as well. There are different types of dental stem cells, but their therapeutic use remains largely untapped, with the focus currently on only periodontal ligament stem cells. More research is necessary in this area, including studies about ROS mechanisms with dental cells, along with the utilization of reactive species in redox medicine. Such studies will help to provide successful treatment modalities for various diseases. PMID:29204250

  17. Generation and Role of Reactive Oxygen and Nitrogen Species Induced by Plasma, Lasers, Chemical Agents, and Other Systems in Dentistry.

    Science.gov (United States)

    Jha, Nayansi; Ryu, Jae Jun; Choi, Eun Ha; Kaushik, Nagendra Kumar

    2017-01-01

    The generation of reactive oxygen and nitrogen species (RONS) has been found to occur during inflammatory procedures, during cell ischemia, and in various crucial developmental processes such as cell differentiation and along cell signaling pathways. The most common sources of intracellular RONS are the mitochondrial electron transport system, NADH oxidase, and cytochrome P450. In this review, we analyzed the extracellular and intracellular sources of reactive species, their cell signaling pathways, the mechanisms of action, and their positive and negative effects in the dental field. In dentistry, ROS can be found-in lasers, photosensitizers, bleaching agents, cold plasma, and even resin cements, all of which contribute to the generation and prevalence of ROS. Nonthermal plasma has been used as a source of ROS for biomedical applications and has the potential for use with dental stem cells as well. There are different types of dental stem cells, but their therapeutic use remains largely untapped, with the focus currently on only periodontal ligament stem cells. More research is necessary in this area, including studies about ROS mechanisms with dental cells, along with the utilization of reactive species in redox medicine. Such studies will help to provide successful treatment modalities for various diseases.

  18. Oral Administration of the Japanese Traditional Medicine Keishibukuryogan-ka-yokuinin Decreases Reactive Oxygen Metabolites in Rat Plasma: Identification of Chemical Constituents Contributing to Antioxidant Activity

    Directory of Open Access Journals (Sweden)

    Yosuke Matsubara

    2017-02-01

    Full Text Available Insufficient detoxification and/or overproduction of reactive oxygen species (ROS induce cellular and tissue damage, and generated reactive oxygen metabolites become exacerbating factors of dermatitis. Keishibukuryogan-ka-yokuinin (KBGY is a traditional Japanese medicine prescribed to treat dermatitis such as acne vulgaris. Our aim was to verify the antioxidant properties of KBGY, and identify its active constituents by blood pharmacokinetic techniques. Chemical constituents were quantified in extracts of KBGY, crude components, and the plasma of rats treated with a single oral administration of KBGY. Twenty-three KBGY compounds were detected in plasma, including gallic acid, prunasin, paeoniflorin, and azelaic acid, which have been reported to be effective for inflammation. KBGY decreased level of the diacron-reactive oxygen metabolites (d-ROMs in plasma. ROS-scavenging and lipid hydroperoxide (LPO generation assays revealed that gallic acid, 3-O-methylgallic acid, (+-catechin, and lariciresinol possess strong antioxidant activities. Gallic acid was active at a similar concentration to the maximum plasma concentration, therefore, our findings indicate that gallic acid is an important active constituent contributing to the antioxidant effects of KBGY. KBGY and its active constituents may improve redox imbalances induced by oxidative stress as an optional treatment for skin diseases.

  19. Chemically adjusting plasma temperature, energy, and reactivity (CAPTEAR) method using NOx and combustion for selective synthesis of Sc3N@C80 metallic nitride fullerenes.

    Science.gov (United States)

    Stevenson, Steven; Thompson, M Corey; Coumbe, H Louie; Mackey, Mary A; Coumbe, Curtis E; Phillips, J Paige

    2007-12-26

    Goals are (1) to selectively synthesize metallic nitride fullerenes (MNFs) in lieu of empty-cage fullerenes (e.g., C60, C70) without compromising MNF yield and (2) to test our hypothesis that MNFs possess a different set of optimal formation parameters than empty-cage fullerenes. In this work, we introduce a novel approach for the selective synthesis of metallic nitride fullerenes. This new method is "Chemically Adjusting Plasma Temperature, Energy, and Reactivity" (CAPTEAR). The CAPTEAR approach with copper nitrate hydrate uses NOx vapor from NOx generating solid reagents, air, and combustion to "tune" the temperature, energy, and reactivity of the plasma environment. The extent of temperature, energy, and reactive environment is stoichiometrically varied until optimal conditions for selective MNF synthesis are achieved. Analysis of soot extracts indicate that percentages of C60 and Sc3N@C80 are inversely related, whereas the percentages of C70 and higher empty-cage C2n fullerenes are largely unaffected. Hence, there may be a "competitive link" in the formation and mechanism of C60 and Sc3N@C80. Using this CAPTEAR method, purified MNFs (96% Sc3N@C80, 12 mg) have been obtained in soot extracts without a significant penalty in milligram yield when compared to control soot extracts (4% Sc3N@C80, 13 mg of Sc3N@C80). The CAPTEAR process with Cu(NO3)2.2.5H2O uses an exothermic nitrate moiety to suppress empty-cage fullerene formation, whereas Cu functions as a catalyst additive to offset the reactive plasma environment and boost the Sc3N@C80 MNF production.

  20. Cross-reactivity virtual profiling of the human kinome by X-react(KIN): a chemical systems biology approach.

    Science.gov (United States)

    Brylinski, Michal; Skolnick, Jeffrey

    2010-12-06

    Many drug candidates fail in clinical development due to their insufficient selectivity that may cause undesired side effects. Therefore, modern drug discovery is routinely supported by computational techniques, which can identify alternate molecular targets with a significant potential for cross-reactivity. In particular, the development of highly selective kinase inhibitors is complicated by the strong conservation of the ATP-binding site across the kinase family. In this paper, we describe X-React(KIN), a new machine learning approach that extends the modeling and virtual screening of individual protein kinases to a system level in order to construct a cross-reactivity virtual profile for the human kinome. To maximize the coverage of the kinome, X-React(KIN) relies solely on the predicted target structures and employs state-of-the-art modeling techniques. Benchmark tests carried out against available selectivity data from high-throughput kinase profiling experiments demonstrate that, for almost 70% of the inhibitors, their alternate molecular targets can be effectively identified in the human kinome with a high (>0.5) sensitivity at the expense of a relatively low false positive rate (human kinome are freely available to the academic community at http://cssb.biology.gatech.edu/kinomelhm/ .

  1. Using laboratory flow experiments and reactive chemical transport modeling for designing waterflooding of the Agua Fria Reservoir, Poza Rica-Altamira Field, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Birkle, P.; Pruess, K.; Xu, T.; Figueroa, R.A. Hernandez; Lopez, M. Diaz; Lopez, E. Contreras

    2008-10-01

    Waterflooding for enhanced oil recovery requires that injected waters must be chemically compatible with connate reservoir waters, in order to avoid mineral dissolution-and-precipitation cycles that could seriously degrade formation permeability and injectivity. Formation plugging is a concern especially in reservoirs with a large content of carbonates, such as calcite and dolomite, as such minerals typically react rapidly with an aqueous phase, and have strongly temperature-dependent solubility. Clay swelling can also pose problems. During a preliminary waterflooding pilot project, the Poza Rica-Altamira oil field, bordering the Gulf coast in the eastern part of Mexico, experienced injectivity loss after five months of reinjection of formation waters into well AF-847 in 1999. Acidizing with HCl restored injectivity. We report on laboratory experiments and reactive chemistry modeling studies that were undertaken in preparation for long-term waterflooding at Agua Frma. Using analogous core plugs obtained from the same reservoir interval, laboratory coreflood experiments were conducted to examine sensitivity of mineral dissolution and precipitation effects to water composition. Native reservoir water, chemically altered waters, and distilled water were used, and temporal changes in core permeability, mineral abundances and aqueous concentrations of solutes were monitored. The experiments were simulated with the multi-phase, nonisothermal reactive transport code TOUGHREACT, and reasonable to good agreement was obtained for changes in solute concentrations. Clay swelling caused an additional impact on permeability behavior during coreflood experiments, whereas the modeled permeability depends exclusively on chemical processes. TOUGHREACT was then used for reservoir-scale simulation of injecting ambient-temperature water (30 C, 86 F) into a reservoir with initial temperature of 80 C (176 F). Untreated native reservoir water was found to cause serious porosity and

  2. Modeling Subsurface Reactive Flows Using Leadership-Class Computing

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Richard T [ORNL; Hammond, Glenn [Pacific Northwest National Laboratory (PNNL); Lichtner, Peter [Los Alamos National Laboratory (LANL); Sripathi, Vamsi K [ORNL; Mahinthakumar, Gnanamanika [ORNL; Smith, Barry F [Argonne National Laboratory (ANL)

    2009-01-01

    We describe our experiences running PFLOTRAN - a code for simulation of coupled hydro-thermal-chemical processes in variably saturated, non-isothermal, porous media - on leadership-class supercomputers, including initial experiences running on the petaflop incarnation of Jaguar, the Cray XT5 at the National Center for Computational Sciences at Oak Ridge National Laboratory. PFLOTRAN utilizes fully implicit time-stepping and is built on top of the Portable, Extensible Toolkit for Scientific Computation (PETSc). We discuss some of the hurdles to 'at scale' performance with PFLOTRAN and the progress we have made in overcoming them on leadership-class computer architectures.

  3. Modeling subsurface reactive flows using leadership-class computing

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Richard Tran [Computational Earth Sciences Group, Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6015 (United States); Hammond, Glenn E [Hydrology Group, Environmental Technology Division, Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Lichtner, Peter C [Hydrology, Geochemistry, and Geology Group, Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Sripathi, Vamsi [Department of Computer Science, North Carolina State University, Raleigh, NC 27695-8206 (United States); Mahinthakumar, G [Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, NC 27695-7908 (United States); Smith, Barry F, E-mail: rmills@ornl.go, E-mail: glenn.hammond@pnl.go, E-mail: lichtner@lanl.go, E-mail: vamsi_s@ncsu.ed, E-mail: gmkumar@ncsu.ed, E-mail: bsmith@mcs.anl.go [Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439-4844 (United States)

    2009-07-01

    We describe our experiences running PFLOTRAN-a code for simulation of coupled hydro-thermal-chemical processes in variably saturated, non-isothermal, porous media- on leadership-class supercomputers, including initial experiences running on the petaflop incarnation of Jaguar, the Cray XT5 at the National Center for Computational Sciences at Oak Ridge National Laboratory. PFLOTRAN utilizes fully implicit time-stepping and is built on top of the Portable, Extensible Toolkit for Scientific Computation (PETSc). We discuss some of the hurdles to 'at scale' performance with PFLOTRAN and the progress we have made in overcoming them on leadership-class computer architectures.

  4. Non-isothermal crystallization kinetics of Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass containing nucleation agent P{sub 2}O{sub 5}/TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bin, E-mail: stra-ceo@163.com; Wang, Yongya; Luo, Wenqin; Li, Jingfen [Huzhou University, Department of Material Chemistry (China); Li, Jianyou [Huzhou Central Hospital, Orthopedic Department (China)

    2017-03-15

    Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass ceramics containing nucleation agent P{sub 2}O{sub 5}/TiO{sub 2} were prepared by sol-gel method. The samples were characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The activation energy and kinetic parameters for crystallization of the samples were calculated by the Johnson-Mehi-Avrami (JMA) model and Augis-Bennett method according to the results of DSC. The results showed that the crystallization mechanism of Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass, whose non-isothermal kinetic parameter n = 2.3, was consistent with surface crystallization of the JMA model. The kinetics model function of Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass, f(α) = 2.3(1–α)[–ln(1–α)]{sup 0.57}, was also obtained. The addition of nucleation agent P{sub 2}O{sub 5}/TiO{sub 2} could reduce the activation energy, which made the crystal growth modes change from onedimensional to three-dimensional.

  5. Non-isothermal crystallization kinetics and glass-forming ability of Ti{sub 41}Zr{sub 25}Be{sub 28}Fe{sub 6} bulk metallic glass investigated by differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Pan; Zhao, Shaofan; Yao, Kefu [Tsinghua University, School of Materials Science and Engineering, Beijing (China); Wang, Xin [Hebei University of Technology, School of Materials Science and Engineering, Tianjin (China)

    2015-07-15

    The non-isothermal crystallization kinetics and glass-forming ability of Ti{sub 41}Zr{sub 25}Be{sub 28}Fe{sub 6} glassy alloy were investigated by differential scanning calorimetry. The activation energies corresponding to the characteristic temperatures have been calculated by Kissinger and Ozawa equations. Based on Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models, it has been found that the local activation energy is higher at the beginning of the crystallization process for the first exothermic peak. The local Avrami exponent indicates that the first-step crystallization is mainly a high-dimensional nucleation and growth with an increasing nucleation rate. According to the calculated fragility index, Ti{sub 41}Zr{sub 25}Be{sub 28}Fe{sub 6} alloy can be classified as ''strong glass former.'' The studied alloy also possesses a critical size up to centimeter order, and the high glass-forming ability is probably related to the relatively low Gibbs energy difference between the liquid and crystalline states. The critical cooling rate of Ti{sub 41}Zr{sub 25}Be{sub 28}Fe{sub 6} glassy alloy has also been determined using Barandiaran-Colmenero's method. (orig.)

  6. Optical and Chemical Properties of Mixed-valent Rhenium Oxide Films Synthesized by Reactive DC Magnetron Sputtering

    Science.gov (United States)

    2015-04-03

    Identification and Interpretation of XPS Data, Physical Electronics Eden Prairie, MN, 1995. [23] Neal Fairley, Casa Software Ltd., CasaXPS Version 2.3.16...Reference Book of Chemical and Physical Data, CRC Press , Boca Raton, FL, 2004. [28] A. Ferrari, A. Libassi, B. Tanner, V. Stolojan, J. Yuan, L. Brown, S

  7. Chemical and biological explorations of the electrophilic reactivity of the bioactive marine natural product halenaquinone with biomimetic nucleophiles.

    Science.gov (United States)

    Wang, Jiayi; Bourguet-Kondracki, Marie-Lise; Longeon, Arlette; Dubois, Joëlle; Valentin, Alexis; Copp, Brent R

    2011-02-15

    The electrophilic reactivity of the bioactive marine sponge natural product halenaquinone has been investigated by reaction with the biomimetic nucleophiles N-acetyl-L-cysteine and N(α)-acetyl-L-lysine. While cysteine reacted at the vacant quinone positions C-14 and C-15, lysine was found to react preferentially at the keto-furan position C-1. A small library of analogues was prepared by reaction of halenaquinone with primary amines, and evaluated against a range of biological targets including phospholipase A(2), farnesyltransferases (FTases) and Plasmodium falciparum. Geranylamine analogue 11 exhibited the most potent activity towards FTases (IC(50) 0.017-0.031 μM) and malaria (IC(50) 0.53-0.62 μM). Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. Investigating the Chemical Reactivity for Hydrogen in Siliciclastic Sediments: two Work Packages of the H2STORE Project

    Science.gov (United States)

    De Lucia, M.; Pilz, P.

    2014-12-01

    The H2STORE ("Hydrogen to Store") collaborative project, funded by the German government, investigates the feasibility of industrial-scale hydrogen storage from excess wind energy in siliciclastic depleted gas and oil reservoirs or suitable saline aquifers. In particular, two work packages (geochemical experiments and modelling) hosted at the German Research Centre for Geosciences (GFZ) focus on the possible impact of hydrogen on formation fluids and on the mineralogical, geochemical and petrophysical properties of reservoirs and caprocks. Laboratory experiments expose core samples from several potential reservoirs to pure hydrogen or hydrogen mixtures under site-specific conditions (temperatures up to 200 °C and pressure up to 300 bar). The resulting qualitative and, whereas possible, quantitative data are expected to ameliorate the precision of predictive geochemical and reactive transport modelling, which is also performed within the project. The combination of experiments and models will improve the knowledge about: (1) solubility model and mixing rule for of hydrogen and its gas mixtures in high saline formation fluids; (2) hydrogen reactivity in a broad spectrum of P-T conditions; (3) thermodynamics and kinetics of mineral dissolution or precipitation reactions and redox processes. It is known that under specific P-T conditions reactions between hydrogen and anorganic rock components such as carbonates can occur. However these conditions have never been precisely defined to date. A precise estimation of the hydrogen impact on reservoir behavior of different siliciclastic rock types is crucial for site selection and optimization of storage depth. Enhancing the overall understanding of such systems will benefit the operational reliability, the ecological tolerance, and the economic efficiency of future energy storing plants, crucial aspects for public acceptance and for industrial investors.

  9. Flows of Reactive Fluids

    CERN Document Server

    Prud'homme, Roger

    2010-01-01

    The modeling of reactive flows has progressed mainly with advances in aerospace, which gave birth to a new science called aerothermochemistry, as well as through developments in chemical and process engineering. The methods employed, the phenomena investigated, and the aims of modeling differ for each field; however, in all cases, the results obtained have considerably enriched the working knowledge of reactive flows. This work examines basic concepts and methods necessary to study reactive flows and transfer phenomena in areas such as fluid mechanics, thermodynamics, and chemistry. Specific topics covered include: * Equations of state * Transfer phenomena and chemical kinetics * Balance equations of reactive flows * Dimensionless numbers and similarity * Chemical reactors * Coupled phenomena * Turbulent flow concepts * Boundary layers and fluid layers * Reactive and nonreactive waves * Interface phenomena * Multiphase flow concepts The book presents tools of interest to graduate students, researchers in math...

  10. Responses of Solid Tumor Cells in DMEM to Reactive Oxygen Species Generated by Non-Thermal Plasma and Chemically Induced ROS Systems

    Science.gov (United States)

    Kaushik, Neha; Uddin, Nizam; Sim, Geon Bo; Hong, Young June; Baik, Ku Youn; Kim, Chung Hyeok; Lee, Su Jae; Kaushik, Nagendra Kumar; Choi, Eun Ha

    2015-02-01

    In this study, we assessed the role of different reactive oxygen species (ROS) generated by soft jet plasma and chemical-induced ROS systems with regard to cell death in T98G, A549, HEK293 and MRC5 cell lines. For a comparison with plasma, we generated superoxide anion (O2-), hydroxyl radical (HO.), and hydrogen peroxide (H2O2) with chemicals inside an in vitro cell culture. Our data revealed that plasma decreased the viability and intracellular ATP values of cells and increased the apoptotic population via a caspase activation mechanism. Plasma altered the mitochondrial membrane potential and eventually up-regulated the mRNA expression levels of BAX, BAK1 and H2AX gene but simultaneously down-regulated the levels of Bcl-2 in solid tumor cells. Moreover, a western blot analysis confirmed that plasma also altered phosphorylated ERK1/2/MAPK protein levels. At the same time, using ROS scavengers with plasma, we observed that scavengers of HO. (mannitol) and H2O2 (catalase and sodium pyruvate) attenuated the activity of plasma on cells to a large extent. In contrast, radicals generated by specific chemical systems enhanced cell death drastically in cancer as well as normal cell lines in a dose-dependent fashion but not specific with regard to the cell type as compared to plasma.

  11. Experiments on non-isothermal spreading

    Energy Technology Data Exchange (ETDEWEB)

    Ehrhard, P.

    1992-09-01

    Experiments are performed on axisymmetric spreading of viscous drops on glass plates. Two liquids are investigated: silicone oil (M-100) spreads to `infinity` and paraffin oil spreads to a finite-radius steady state. The experiments with silicone oil partly recover the behaviour of previous workers data; those experiments with paraffin oil provide new data. It is found that gravitational forces dominate at long enough times while at shorter times capillary forces dominate. When the plate is heated or cooled with respect to the ambient gas, thermocapillary forces generate flows that alter the spreading dynamics. Heating (cooling) the plate is found to retard (augment) the streading. Moreover, in case of partial wetting, the finally-approached drop radius is smaller (larger) for a heated (cooled) plate. These data are all new. All these observations are in excellent quantitative agreement with the related model predictions of Ehrhard and Davis (1991). A breakdown of the axisymmetric character of the flow is observed only for very long times and/or very thin liquid layers. (orig.). [Deutsch] Es werden Experimente zur Ausbreitung achsensymmetrischer, viskoser Fluessigkeitstropfen auf Glas vorgestellt. Zwei Fluessigkeiten werden betrachtet: Fuer Silikonoeltropfen (M-100) beobachten wir eine unbeschraenkte Ausbreitung, waehrend sich Paraffinoeltropfen gegen eine stationaere Endkontur entwickeln. Die Silikonoelexperimente bestaetigen teilweise die Ergebnisse frueherer Experimentatoren, die Paraffinoelexperimente liefern gaenzlich neue Daten. Wir finden, dass die Schwerkraft fuer lange Zeiten den Ausbreitungsprozess kontrolliert. Fuer kurze Zeiten spielen dagegen Kapillaritaetskraefte eine wichtigere Rolle. Wird die Glasplatte gegenueber der Umgebung zusaetzlich erwaermt oder gekuehlt, so treiben thermokapillare Kraefte eine Stroemung innerhalb des Tropfens. Die Dynamik der Ausbreitung wird dadurch massgeblich geaendert. Eine Erwaermung (Kuehlung) fuehrt zu einer verzoegerten (beschleunigten) Ausbreitung der Tropfen. Im Falle der teilweisen Benetzung wird zusaetzlich der stationaere Endradius beeinflusst. Er ist kleiner (groesser) im Falle einer beheizten (gekuehlten) Platte. Diese Ergebnisse sind neu. Die experimentellen Beobachtungen befinden sich fuer alle Faelle in guter quantitativer Uebereinstimmung mit dem theoretischen Modell von Ehrhard und Davis (1991). Abweichungen von einer achsensymmetrischen Form der Tropfen treten nur fuer sehr lange Zeiten und/oder sehr flache Tropfen auf. (orig.).

  12. Steepest-entropy-ascent quantum thermodynamic framework for describing the non-equilibrium behavior of a chemically reactive system at an atomistic level

    CERN Document Server

    Beretta, Gian Paolo

    2015-01-01

    Steepest-Entropy-Ascent Quantum Thermodynamics (SEAQT) provides a general framework for the description of non-equilibrium phenomena at any level, particularly the atomistic one. This theory and its dynamical postulate are used here to develop a general mathematical framework, which at an atomistic level, in particular, can be used to predict the non-equilibrium evolution in state of a closed, chemically reactive mixture such as the one examined here, i.e., a mixture of hydrogen (H2) and flourine (F) contained in an isolated tank of fixed volume. The general framework provided, however, is written for a reactive system subject to multiple reaction mechanisms. To predict this evolution in state, both the energy and particle number eigenvalue problems for a dilute gas are set up and solved analytically. Wall and non-ideal-gas behavior effects are neglected, although the extension to dense gases is straightforward but left for a future paper. The system-level energy and particle number eigenvalues and eigenstate...

  13. Lattice-Boltzmann simulation methods for chemically reactive systems in the micro area; Lattice Boltzmann Simulationsmethoden fuer chemisch reaktive Systeme im Microbereich - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Karlin, I.; Frouzakis, Ch.; Boulouchos, K.

    2007-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) reports on work done in 2007 at the Swiss Federal Institute of Technology ETH in Zurich on simulation methods for chemically reactive systems at the micrometer scale. The Lattice-Boltzmann method using lattice models is examined and the results obtained are discussed. A three-dimensional thermal model was developed and used to analyse flows with considerable temperature and density variations. The model was also used for the analysis of flows in diluted gases. A method for the reduction of complex reaction mechanisms was developed and tested for future combustion applications. 30 publications are noted and new possibilities for the analysis of flows in micro-channels and porous media - as used in reformers, catalyzers and fuel cells - are discussed.

  14. A quantum chemical study of the reactivity of acetaminophen (paracetamol) toxic metabolite N-acetyl-p-benzoquinone imine with deoxyguanosine and glutathione.

    Science.gov (United States)

    Klopčič, Ivana; Poberžnik, Matic; Mavri, Janez; Dolenc, Marija Sollner

    2015-12-05

    Acetaminophen (APAP) forms some reactive metabolites that can react with DNA. APAP is a potentially genotoxic drug and is classified as a Group 3 drug according to International Agency for Research on Cancer (IARC). One of the possible mechanisms of APAP genotoxicity after long term of use is that its reactive quinone imine (QI) metabolite of acetaminophen (NAPQI), can chemically react with DNA after glutathione (GSH) depletion. A quantum chemical study of the reactions between the NAPQI and deoxyguanosine (dG) or GSH was performed. Activation energies (ΔG(ǂ)) for the reactions associated with the 1, 4-Michael addition were calculated on the M062X/6-311++G (d,p) level of theory. We modeled the reaction with dG as a multi-step process. The first step is rate-limiting (ΔG(ǂ) = 26.7 kcal/mol) and consists of formation of a C-N bond between the C3 atom of the QI moiety and the N7 atom of dG. The second step involves proton transfer from the C3 moiety to the nitrogen atom of the QI with ΔG(ǂ) of 13.8 kcal/mol. The depurination reaction that follows has a ΔG(ǂ) of 25.7 kcal/mol. The calculated ΔG(ǂ) for the nucleophilic attack of the deprotonated S atom of GSH on the C3 atom of the NAPQI is 12.9 kcal/mol. Therefore, the QI will react with GSH much faster than with DNA. Our study gives mechanistic insight into the genotoxicity of the APAP metabolite and will be useful for estimating the genotoxic potential of existing drugs with a QI moiety. Our results show that clinical application of APAP is safe, while in the case of severely depleted GSH levels APAP should be administered with caution. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  15. Understanding the Polar Character Trend in a Series of Diels-Alder Reactions Using Molecular Quantum Similarity and Chemical Reactivity Descriptors

    Directory of Open Access Journals (Sweden)

    Alejandro Morales-Bayuelo

    2014-01-01

    Full Text Available In molecular similarity there is a premise “similar molecules tend to behave similarly”; however in the actual quantum similarity field there is no clear methodology to describe the similarity in chemical reactivity, and with this end an analysis of charge-transfer (CT processes in a series of Diels-Alder (DA reactions between cyclopentadiene (Cp and cyano substitutions on ethylene has been studied. The CT analysis is performed in the reagent assuming a grand canonical ensemble and the considerations for an electrophilic system using B3LYP/6-31G(d and M06-2X/6-311 + G(d,p methods. An analysis for CT was performed in agreement with the experimental results with a good statistical correlation (R2=0.9118 relating the polar character to the bond force constants in DA reactions. The quantum distortion analysis on the transition states (TS was performed using molecular quantum similarity indexes of overlap and coulomb showing good correlation (R2=0.8330 between the rate constants and quantum similarity indexes. In this sense, an electronic reorganization based on molecular polarization in terms of CT is proposed; therefore, new interpretations on the electronic systematization of the DA reactions are presented, taking into account that today such electronic systematization is an open problem in organic physical chemistry. Additionally, one way to quantify the similarity in chemical reactivity was shown, taking into account the dependence of the molecular alignment on properties when their position changes; in this sense a possible way to quantify the similarity of the CT in systematic form on these DA cycloadditions was shown.

  16. Mixed CuFe and ZnFe (hydr)oxides as reactive adsorbents of chemical warfare agent surrogates.

    Science.gov (United States)

    Florent, Marc; Giannakoudakis, Dimitrios A; Wallace, Rajiv; Bandosz, Teresa J

    2017-05-05

    Two sets of zinc-iron and copper-iron mixed (hydr)oxides were prepared by a simple co-precipitation method. Either nitrate or chloride was a source of the metals. The decontamination ability of the materials was tested in closed vials saturated with vapors of 2-chloroethyl ethyl sulfide (CEES) or dimethyl chlorophosphate (DMCP), a blister agent and a nerve agent surrogate, respectively. In both cases, the weight uptakes on the mixed oxides were superior to the ones reported for the pure metal oxides or hydroxides. When exposed to CEES for 5days, zinc-iron (hydr)oxides show much higher activity than the copper-iron ones. The products of reactions in the vessel headspace were investigated by GC/MS and on the surface by FTIR. Ethyl vinylsulfide and chloromethane are the main products of the reactive adsorption of CEES and DMCP, respectively. This indicates that CEES is mainly degraded by dehydrochlorination and DMCP- by hydrolysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Physical aspects of nanoparticles in non-Newtonian liquid in the presence of chemically reactive species through parabolic approach

    Directory of Open Access Journals (Sweden)

    Imad Khan

    Full Text Available An article is made to report physical aspects of nanoparticles along with mutual interaction of chemical reaction and mixed convection on boundary layer Eyring Powell fluid flow yields by stretching surface. The fluid flow is engaged due to no slip condition i-e the velocity of particles is directly related to velocity of surface due to stretching. The physical situation within the real concerned constraints is achieved in terms of differential equations as a boundary value problem. To make implementation of numerical algorithm possible partial differential equations are transformed into ordinary differential equations by means of appropriate transformation. Then these constructed ordinary differential equations are solved numerically by using shooting scheme charted with Runge-Kutta algorithm. The effect logs of an involved pertinent flow parameters are explored by way of graphical outcomes. It is observed that in the presence of nanoparticles Eyring-Powell fluid velocity increases for positive values of both thermal Grashof and solutal Grashof numbers. A parabolic curve fitting way of communication is executed to represent the impact of both thermophoresis parameter and Brownian motion parameter on heat and mass transfer rates. It is found that heat transfer rate is decreasing function of thermophoresis parameter but mass transfer rate exhibit an inciting nature towards Brownian motion parameter. Keywords: Eyring-Powell nanofluid model, Parabolic curve fitting, Mixed convection, Chemical reaction

  18. T2Well/ECO2N Version 1.0: Multiphase and Non-Isothermal Model for Coupled Wellbore-Reservoir Flow of Carbon Dioxide and Variable Salinity Water

    Energy Technology Data Exchange (ETDEWEB)

    Pan, L.; Oldenburg, C.M.; Wu, Y.-S.; Pruess, K.

    2011-02-14

    At its most basic level, the injection of CO{sub 2} into geologic CO{sub 2} storage sites involves a system comprising the wellbore and the target reservoir. The wellbore is the only conduit available to emplace CO{sub 2} into reservoirs for long-term storage. At the same time, wellbores in general have been identified as the most likely conduit for CO{sub 2} and brine leakage from geologic carbon sequestration (GCS) sites, especially those in sedimentary basins with historical hydrocarbon production. We have developed a coupled wellbore and reservoir model for simulating the dynamics of CO{sub 2} injection and leakage through wellbores. The model describes the following processes: (1) upward or downward wellbore flow of CO{sub 2} and variable salinity water with transition from supercritical to gaseous CO{sub 2} including Joule-Thomson cooling, (2) exsolution of CO{sub 2} from the aqueous phase as pressure drops, and (3) cross flow into or interaction with layers of surrounding rock (reservoirs). We use the Drift-Flux Model and related conservation equations for describing transient two-phase non-isothermal wellbore flow of CO{sub 2}-water mixtures under different flow regimes and interacting with surrounding rock. The mass and thermal energy balance equations are solved numerically by a finite difference scheme with wellbore heat transmission to the surrounding rock handled either semi-analytically or numerically. The momentum balance equation for the flow in the wellbore is solved numerically with a semi-explicit scheme. This manual provides instructions for compilation and use of the new model, and presents some example problems to demonstrate its use.

  19. Quantum chemical study of relative reactivities of a series of amines and nitriles - Relevance to prebiotic chemistry

    Science.gov (United States)

    Loew, G. H.; Berkowitz, D.; Chang, S.

    1975-01-01

    Using the Iterative Extended Huckel Theory (IEHT) calculations of the electron distribution and orbital energies of a series of thirteen amines, nitriles and amino-nitriles relevant to prebiotic and cosmo-chemistry have been carried out. Ground state properties such as the energy and nature of the highest occupied (HOMO) and lowest empty (LEMO) molecular orbitals, net atomic charges and number of nonbonding electrons have been identified as criteria for correlating the relative nucleophilicity of amine and nitrile nitrogens and the electrophilicity of nitrile and other unsaturated carbon atoms. The results of such correlations can be partially verified by known chemical behavior of these compounds and are used to predict and understand their role in prebiotic organic synthesis.

  20. Chemical pneumonitis and subsequent reactive airways dysfunction syndrome after a single exposure to a household product: a case report

    Directory of Open Access Journals (Sweden)

    Khalid Imran

    2009-11-01

    Full Text Available Abstract Introduction Household products are usually safe to use. Adverse events arising from their use are mostly reported in patients with pre-existing atopy or pulmonary problems and usually only after a prolonged exposure to such products. We report the case of a patient with no prior problems who developed significant side effects from a single exposure to a domestic product. Case presentation A 43-year-old Caucasian American man, previously in good health, used a domestic aerosol product called 'Stand N' Seal "Spray-On" Grout Sealer' in an enclosed room in his house. The product contained n-butyl acetate ( Conclusion A household product may still prove unsafe to use even after it has gone through vigorous testing and approval processes. Even healthy individuals are susceptible to adverse outcomes after a brief exposure. Extra precautions should be taken when using any chemical product at home.

  1. Reactive transport modeling of chemical and isotope data to identify degradation processes of chlorinated ethenes in a diffusion-dominated media

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia; Damgaard, Ida; Jeannottat, Simon

    Chlorinated ethenes are among the most widespread contaminants in the subsurface and a major threat to groundwater quality at numerous contaminated sites. Many of these contaminated sites are found in low-permeability media, such as clay tills, where contaminant transport is controlled by diffusi...... is an important finding, that is further supported by microbial and chemical data. Improved understanding of degradation processes in clay tills is useful for improving the reliability of risk assessment and the design of remediation schemes for chlorinated solvents........ Degradation and transport processes of chlorinated ethenes are not well understood in such geological settings, therefore risk assessment and remediation at these sites are particularly challenging. In this work, a combined approach of chemical and isotope analysis on core samples, and reactive transport...... the source zone (between 6 and 12 mbs). Concentrations and stable isotope ratios of the mother compounds and their daughter products, as well as redox parameters, fatty acids and microbial data, were analyzed with discrete sub-sampling along the cores. More samples (each 5 mm) were collected around...

  2. Effect of multiple slip on a chemically reactive MHD non-Newtonian nanofluid power law fluid flow over a stretching sheet with microorganism

    Science.gov (United States)

    Basir, Mohammad Faisal Mohd; Ismail, Fazreen Amira; Amirsom, Nur Ardiana; Latiff, Nur Amalina Abdul; Ismail, Ahmad Izani Md.

    2017-04-01

    The effect of multiple slip on a chemically reactive magnetohydrodynamic (MHD) non-Newtonian power law fluid flow over a stretching sheet with microorganism was numerically investigated. The governing partial differential equations were transformed into nonlinear ordinary differential equations using the similarity transformations developed by Lie group analysis. The reduced governing nonlinear ordinary differential equations were then numerically solved using the Runge-Kutta-Fehlberg fourth-fifth order method. Good agreement was found between the present numerical solutions with the existing published results to support the validity and the accuracy of the numerical computations. The influences of the velocity, thermal, mass and microorganism slips, the magnetic field parameter and the chemical reaction parameter on the dimensionless velocity, temperature, nanoparticle volume fraction, microorganism concentration, the distribution of the density of motile microorganisms have been illustrated graphically. The effects of the governing parameters on the physical quantities, namely, the local heat transfer rate, the local mass transfer rate and the local microorganism transfer rate were analyzed and discussed.

  3. Assessment of groundwater chemical evolution for a spent nuclear fuel repository under prolonged temperate conditions: an application of efficient coupled groundwater flow and reactive transport simulation

    Science.gov (United States)

    Gylling, B.; Hartley, L. J.; Joyce, S. J.; Woollard, H.; Marsic, N.; Sidborn, M.; Puigdomenech, I.; Selroos, J. O.

    2014-12-01

    SKB has submitted a license application for a spent nuclear fuel repository at Forsmark sited in crystalline rocks of the Fennoscandian shield. In support of this application various quantitative assessments were made to demonstrate the long-term safety of the proposed repository. One such assessment involved simulation of groundwater chemical evolution to quantify impacts on safety functions for the disposal system related to the geochemical conditions, particularly salinity, pH and redox conditions. In the reference case the current temperate period lasts until 12,000 AD. A case of prolonged meteoric infiltration to 60,000 AD is also considered resulting from e.g. global warming. This is to fulfil a regulatory request to assess whether extended dilute water infiltration might lead to a rise in redox potential and also to an increase in erosion of the bentonite barrier due to formation of colloids. In order to perform long transient simulations of groundwater flow and solute transport with water-solute-rock interactions, new tools have been developed to closely couple geochemical, groundwater flow and transport calculations, and perform these efficiently using parallel computing techniques. In assessing this case, sensitivities are tested to the geochemical reaction schemes appropriate to the site. The results of this work predict that the chemical environment at repository depth stabilises at around 20,000 AD and shows little change beyond that. The salinity of the groundwater is governed by the low permeability (c. 10-19 m2) of the bedrock and by rock matrix diffusion, resulting in relatively shallow and slow circulation of groundwater. The chemical reactions influence concentrations of reactive species, the calculated pH and redox potential. In particular, the redox reactions thought to be relevant for the Forsmark site maintain reducing conditions at repository depth, even with infiltration at the ground surface of meteoric water with relatively high redox

  4. Hybrid graphene oxide/DAB-Am-16 dendrimer: Preparation, characterization chemical reactivity and their electrocatalytic detection of L-Dopamine

    Science.gov (United States)

    Do Carmo, Devaney Ribeiro; Fernandes, Daniela Silvestrini

    2017-09-01

    Graphene oxide (GO) was chemically modified with a poly(propylene)imine Generation 3.0 dendrimer (DAB-Am-16). The characterization, structure and properties of hybrid graphene oxide/DAB-Am-16 dendrimer was studied by Raman spectroscopy, Fourier-Transforming Infrared Spectroscopy (FT-IR), X-Ray Photoelectron Spectroscopic (XPS), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Thermogravimetric analysis. After functionalized the hybrid material (GOD) can interact with copper and subsequently with hexacyanoferrate (III) ions (GODHCu). The GODHCu incorporated into a graphite paste electrode (20% w/w) was applied to an electrocatalytic detection of neurotransmitter L-dopamine using differential pulse voltammetry. The analytical curve showed a linear response in the concentration range from 1.0 × 10-7 to 1.0 × 10-5 mol L-1 with a corresponding equation Y(A) = 1.706 × 10-5 + 0.862 [L-dopamine] and a correlation coefficient r2 = 0.998. The detection limit was 6.36 × 10-7 mol L-1 with a relative standard deviation of ±4% (n = 3) and an amperometric sensitivity of 0.862 A/mol L-1.

  5. Chemical dynamics between wells across a time-dependent barrier: Self-similarity in the Lagrangian descriptor and reactive basins

    Science.gov (United States)

    Junginger, Andrej; Duvenbeck, Lennart; Feldmaier, Matthias; Main, Jörg; Wunner, Günter; Hernandez, Rigoberto

    2017-08-01

    In chemical or physical reaction dynamics, it is essential to distinguish precisely between reactants and products for all times. This task is especially demanding in time-dependent or driven systems because therein the dividing surface (DS) between these states often exhibits a nontrivial time-dependence. The so-called transition state (TS) trajectory has been seen to define a DS which is free of recrossings in a large number of one-dimensional reactions across time-dependent barriers and thus, allows one to determine exact reaction rates. A fundamental challenge to applying this method is the construction of the TS trajectory itself. The minimization of Lagrangian descriptors (LDs) provides a general and powerful scheme to obtain that trajectory even when perturbation theory fails. Both approaches encounter possible breakdowns when the overall potential is bounded, admitting the possibility of returns to the barrier long after the trajectories have reached the product or reactant wells. Such global dynamics cannot be captured by perturbation theory. Meanwhile, in the LD-DS approach, it leads to the emergence of additional local minima which make it difficult to extract the optimal branch associated with the desired TS trajectory. In this work, we illustrate this behavior for a time-dependent double-well potential revealing a self-similar structure of the LD, and we demonstrate how the reflections and side-minima can be addressed by an appropriate modification of the LD associated with the direct rate across the barrier.

  6. A chemical test of critical point isomorphism: reactive dissolution of ionic solids in isobutyric acid + water near the consolute point.

    Science.gov (United States)

    Baird, James K; Baker, Jonathan D; Hu, Baichuan; Lang, Joshua R; Joyce, Karen E; Sides, Alison K; Richey, Randi D

    2015-03-12

    Binary liquid mixtures having a consolute point can be used as solvents for chemical reactions. When excess cerium(IV) oxide is brought into equilibrium with a mixture of isobutyric acid + water, and the concentration of cerium in the liquid phase is plotted in van't Hoff form, a straight line results for temperatures sufficiently in excess of the critical solution temperature. Within 1 K of the critical temperature, however, the concentration becomes substantially suppressed, and the van't Hoff slope diverges toward negative infinity. According to the phase rule, one mole fraction can be fixed. Given this restriction, the temperature behavior of the data is in exact agreement with the predictions of both the principle of critical point isomorphism and the Gibbs-Helmholtz equation. In addition, we have determined the concentration of lead in the liquid phase when crystalline lead(II) sulfate reacts with potassium iodide in isobutyric acid + water. When plotted in van't Hoff form, the data lie on a straight line for all temperatures including the critical region. The phase rule indicates that two mole fractions can be fixed. With this restriction, the data are in exact agreement with the principle of critical point isomorphism.

  7. Physical aspects of nanoparticles in non-Newtonian liquid in the presence of chemically reactive species through parabolic approach

    Science.gov (United States)

    Khan, Imad; ur Rehman, Khalil; Malik, M. Y.

    An article is made to report physical aspects of nanoparticles along with mutual interaction of chemical reaction and mixed convection on boundary layer Eyring Powell fluid flow yields by stretching surface. The fluid flow is engaged due to no slip condition i-e the velocity of particles is directly related to velocity of surface due to stretching. The physical situation within the real concerned constraints is achieved in terms of differential equations as a boundary value problem. To make implementation of numerical algorithm possible partial differential equations are transformed into ordinary differential equations by means of appropriate transformation. Then these constructed ordinary differential equations are solved numerically by using shooting scheme charted with Runge-Kutta algorithm. The effect logs of an involved pertinent flow parameters are explored by way of graphical outcomes. It is observed that in the presence of nanoparticles Eyring-Powell fluid velocity increases for positive values of both thermal Grashof and solutal Grashof numbers. A parabolic curve fitting way of communication is executed to represent the impact of both thermophoresis parameter and Brownian motion parameter on heat and mass transfer rates. It is found that heat transfer rate is decreasing function of thermophoresis parameter but mass transfer rate exhibit an inciting nature towards Brownian motion parameter.

  8. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  9. PSI's 1kW imaging furnace-A tool for high-temperature chemical reactivity studies

    Energy Technology Data Exchange (ETDEWEB)

    Guesdon, C.; Alxneit, I.; Tschudi, H.R.; Wuillemin, D.; Brunner, Y.; Winkel, L.; Sturzenegger, M. [Laboratory for High-Temperature Solar Technology, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Petrasch, J. [Professorship for Renewable Energy Carriers, ETHZ Zentrum, 8092 Zurich (Switzerland)

    2006-10-15

    A new experiment has been installed to conduct studies at temperatures as high as 2500K on chemical reactions that involve solids or melts and the release of condensable gases. The sample is radiatively heated by a 1kW xenon short arc lamp placed in the upper focus of a vertically oriented ellipsoid of revolution. The optimal optical configuration has been determined by a Monte-Carlo Ray tracing method. Several methods to machine the reflector have been evaluated by experimentally determining the optical quality of the surface of plane test pieces. In the imaging furnace the sample is placed on a water-cooled support and heated by the concentrated radiation. This arrangement allows for fast heating and impedes the reaction of the sample with crucible material. A remotely controlled hammer allows for freezing the high-temperature composition of the sample by a fast quench. Thus, the sample can be later analyzed by conventional methods such as XRD or TEM. To allow for measurements under defined atmospheres and to protect the ellipsoidal reflector from liberated condensable products, the entire sample stage is enclosed by a hemispherical glass dome. The dome itself is protected from condensable compounds by a laminar flow of inert gas. Experiments with an incense cone at the place of the sample to visualize the gas flow showed that a steady layer of inert gas protects the dome from smoke, if the inert gas flow is properly adjusted. Measured peak flux densities clearly exceed 500Wcm{sup -2} required to access temperatures of at least 2500K. Decomposition experiments on copper sulfides confirmed the operation of the furnace. In the near future flash assisted multi-wavelength pyrometry (FAMP) will be implemented to measure sample temperatures online. Though the imaging furnace was developed to study the decomposition of metal sulfides it is obviously suited to conduct high-temperature studies on most materials relevant for high-temperature solar technology. (author)

  10. The reactivity of quaternary ammonium- versus potassium-fluorides supported on metal oxides: paving the way to an instantaneous detoxification of chemical warfare agents.

    Science.gov (United States)

    Zafrani, Yossi; Yehezkel, Lea; Goldvaser, Michael; Marciano, Daniele; Waysbort, Daniel; Gershonov, Eytan; Columbus, Ishay

    2011-12-21

    The reactions of the chemical warfare agents (CWAs) 2,2'-dichloroethyl sulfide (HD), O-ethyl S-2-(diisopropylamino)-ethyl methylphosphonothioate (VX) and isopropyl methylphosphonofluoridate (GB) with various metal oxide-supported quaternary ammonium fluorides (QAF) and/or potassium fluoride (KF) reagents are described. These active sorbents, which were prepared by a modified procedure, include alumina, silica and titania, enriched with "available" (not bound to the surface) fluoride ions. Alumina-based fluoride reagents were found to be more active than their silica or titania counterparts. QAF/Al(2)O(3) reagents, compared to KF/Al(2)O(3), exhibit an exceptional reactivity toward HD, as demonstrated both in reaction rates and product identity. For example, with TBAF, t(1/2) is 15 min for the formation of the elimination product divinyl sulfide (DVS), while with KF, t(1/2) is 10 h for the formation of the hydrolysis product thiodiglycol (TDG). On the other hand, both sorbents reacted similarly against the nerve agents GB or VX. In order to increase the "available" fluoride content on the solid surface, the mixed active sorbent TBAF/KF/Al(2)O(3) (20/20/60) was developed. On this powder, all three CWAs were degraded instantaneously at the low loading of 1 wt% (t(1/2) fluoride (KF) acts synergistically as a reservoir for the more reactive organic fluorides (TBAF). Moreover, the alumina surface hydroxyl groups may also operate as a water reservoir for the hydrolysis of VX or GB. Therefore, TBAF/KF/Al(2)O(3) might be considered as a promising destructive sorbent for CWAs.

  11. Host-guest complex of N-(2-chloroethyl), N-nitroso, N‧, N‧ -dicyclohexylsulfamid with β-cyclodextrin: Fluorescence, QTAIM analysis and structure-chemical reactivity

    Science.gov (United States)

    Bensouilah, Nadjia; Fisli, Hassina; Bensouilah, Hamza; Zaater, Sihem; Abdaoui, Mohamed; Boutemeur-Kheddis, Baya

    2017-10-01

    In this work, the inclusion complex of DCY/CENS: N-(2-chloroethyl), N-nitroso, N‧, N‧-dicyclohexylsulfamid and β-cyclodextrin (β-CD) is investigated using the fluorescence spectroscopy, PM3, ONIOM2 and DFT methods. The experimental part reveals that DCY/CENS forms a 1:1 stoichiometric ratio inclusion complex with β-CD. The constant of stability is evaluated using the Benesi-Hildebrand equation. The results of the theoretical optimization showed that the lipophilic fraction of molecule (cyclohexyl group) is inside of β-CD. Accordingly, the Nitroso-Chloroethyl moiety is situated outside the cavity of the macromolecule host. The favorable structure of the optimized complex indicates the existence of weak intermolecular hydrogen bonds and the most important van der Waals (vdW) interactions which are studied on the basis of Natural Bonding Orbital (NBO) analysis. The NBO is employed to compute the electronic donor-acceptor exchanges between drug and β-CD. Furthermore, a detailed topological charge density analysis based on the quantum theory of atoms in molecules (QTAIM), has been accomplished on the most favorable complex using B3LYP/6-31G(d) method. The presence of stabilizing intermolecular hydrogen bonds and van der Waals interactions in the most favorable complex is predicted. Also, the energies of these interactions are estimated with Espinosa's formula. The findings of this investigation reveal that the correlation between the structural parameters and the electronic density is good. Finally, and based on DFT calculations, the reactivity of the interesting molecule in free state was studied and compared with that in the complexed state using chemical potential, global hardness, global softness, electronegativity, electrophilicity and local reactivity descriptors.

  12. TOGA: A TOUGH code for modeling three-phase, multi-component, and non-isothermal processes involved in CO2-based Enhanced Oil Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Lehua [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Oldenburg, Curtis M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)

    2016-10-10

    TOGA is a numerical reservoir simulator for modeling non-isothermal flow and transport of water, CO2, multicomponent oil, and related gas components for applications including CO2-enhanced oil recovery (CO2-EOR) and geologic carbon sequestration in depleted oil and gas reservoirs. TOGA uses an approach based on the Peng-Robinson equation of state (PR-EOS) to calculate the thermophysical properties of the gas and oil phases including the gas/oil components dissolved in the aqueous phase, and uses a mixing model to estimate the thermophysical properties of the aqueous phase. The phase behavior (e.g., occurrence and disappearance of the three phases, gas + oil + aqueous) and the partitioning of non-aqueous components (e.g., CO2, CH4, and n-oil components) between coexisting phases are modeled using K-values derived from assumptions of equal-fugacity that have been demonstrated to be very accurate as shown by comparison to measured data. Models for saturated (water) vapor pressure and water solubility (in the oil phase) are used to calculate the partitioning of the water (H2O) component between the gas and oil phases. All components (e.g., CO2, H2O, and n hydrocarbon components) are allowed to be present in all phases (aqueous, gaseous, and oil). TOGA uses a multiphase version of Darcy’s Law to model flow and transport through porous media of mixtures with up to three phases over a range of pressures and temperatures appropriate to hydrocarbon recovery and geologic carbon sequestration systems. Transport of the gaseous and dissolved components is by advection and Fickian molecular diffusion. New methods for phase partitioning and thermophysical property modeling in TOGA have been validated against experimental data published in the literature for describing phase partitioning and phase behavior. Flow and transport has been verified by testing against related TOUGH2 EOS modules and

  13. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems, t...

  14. Mathematical Analysis of a Series of 4-Acetylamino-2-(3,5-dimethylpyrazol-1-yl-6-pyridylpyrimidines: A Simple Way to Relate Quantum Similarity to Local Chemical Reactivity Using the Gaussian Orbitals Localized Theory

    Directory of Open Access Journals (Sweden)

    Alejandro Morales-Bayuelo

    2014-01-01

    Full Text Available Molecular Quantum Similarity (MQS descriptors and Density Functional Theory (DFT based reactivity descriptors were studied for a series of 4-Acetylamino-2-(3,5-dimethylpyrazol-1-yl-6-pyridylpyrimidines compounds used for Parkinson’s disease (PD treatment. The quantification of the steric and electronic effects was shown through scales of quantitative convergence; such scales allow us to establish a methodology to quantify the similarity from the local chemical reactivity (Fukui Functions point of view. This procedure provides new considerations in the local reactivity of the A2A Adenosine receptor antagonists in a disease of difficult control as PD. In addition, we present new considerations to the localized bonding theory and show a new methodology for quantum similarity on the Fukui Functions. Considering that the Fukui functions under a condensation scheme may have ambiguities in the (DFT context.

  15. Índices de reatividade química a partir da teoria do funcional de densidade: formalismo e perspectivas Chemical reactivity indexes from density functional theory: formalism and perspectives

    Directory of Open Access Journals (Sweden)

    Hélio Anderson Duarte

    2001-08-01

    Full Text Available The fundaments of the modern Density Functional Theory (DFT, its basic theorems, principles and methodology are presented. This review also discuss important and widely used concepts in chemistry but that had not been precisely defined until the development of the DFT. These concepts were proposed and used from an empirical base, but now their precise definition are well established in the DFT formalism. Concepts such as chemical potential (electronegativity, hardness, softness and Fukui function are presented and their consequences to the understanding of chemical reactivity are discussed.

  16. DFT study on structure, electronic properties, and reactivity of cis ...

    Indian Academy of Sciences (India)

    DFT global chemical reactivity descriptors (chemical hardness, total energy, electronic chemical potential, and electrophilicity) are calculated for the isomers and used to predict their relative stability and reactivity. The chemical reactivity indices are found to be related to the bond angle defined by the cis carbonyls and the ...

  17. pH-Specific structural speciation of the ternary V(V)-peroxido-betaine system: a chemical reactivity-structure correlation.

    Science.gov (United States)

    Gabriel, C; Kioseoglou, E; Venetis, J; Psycharis, V; Raptopoulou, C P; Terzis, A; Voyiatzis, G; Bertmer, M; Mateescu, C; Salifoglou, A

    2012-06-04

    (V)-diperoxido units, thereby stabilizing a dinuclear V(V)-tetraperoxido dianion. Structural comparisons of the anions in 1-3 with other known dinuclear V(V)-tetraperoxido binary anionic species provide insight into the chemical reactivity of V(V)-diperoxido systems and their potential link to cellular events such as insulin mimesis and anitumorigenicity modulated by the presence of betaine.

  18. Prediction of in vivo potential for metabolic activation of drugs into chemically reactive intermediate: correlation of in vitro and in vivo generation of reactive intermediates and in vitro glutathione conjugate formation in rats and humans.

    Science.gov (United States)

    Masubuchi, Noriko; Makino, Chie; Murayama, Nobuyuki

    2007-03-01

    The covalent binding of reactive intermediates to macromolecules might have potential involvement in severe adverse drug reactions. Thus, quantification of reactive metabolites is necessary during the early stage of drug discovery to avoid serious toxicity. In this study, the relationship between covalent binding and glutathione (GSH) conjugate formation in rat and human liver microsomes were investigated using 10 representative radioactive compounds that have been reported as hepatotoxic or having other toxicity derived from their reactive intermediates: acetaminophen, amodiaquine, carbamazepine, clozapine, diclofenac, furosemide, imipramine, indomethacin, isoniazid, and tienilic acid, all at a concentration of 10 microM. The GSH conjugate formation rate correlates well with the covalent binding of radioactivity (both rat and human, r2 = 0.93), which suggests that quantification of the GSH conjugate can be used to estimate covalent binding. To quantify the GSH-conjugation rate with non-radiolabeled compounds in vitro, the validation study for the determination of GSH conjugate formation using 35S-GSH by radio-HPLC was useful to predict metabolic activation. Following oral administration of 20 mg/kg of the radiolabeled compounds to rats, radioactivity that covalently bound to plasma and liver proteins was determined. The in vivo maximum covalent binding level in liver based on the free fraction of plasma area under the concentration curve (AUC) and in vitro covalent binding rate was found to correlate well (r2 = 0.79). Therefore, this model for in vitro covalent binding studies in human and rat and in vivo rat studies might be useful in predicting human metabolic activation of compounds.

  19. [Reactive arthritis].

    Science.gov (United States)

    Gerloni, V; Fantini, F

    1990-01-01

    The term reactive arthritis was introduced to describe an acute non-purulent arthritis complicating an infection elsewhere in the body. Reactive arthritis can also be classified into HLA-B27 associated and non-associated forms. Rheumatic fever is an example of the HLA-B27 non-associated forms with genetic factors other than HLA-B27 involved. HLA-B27 associated reactive arthritis includes enteric, urogenic and idiopathic arthritides. The bacteria known to trigger post-enteritic reactive arthritis are: Yersinia, Salmonella, Shigella, Campylobacter, Clostridium difficile and Brucella; those known to trigger post-urethritic reactive arthritis are Chlamydia trachomatis and Ureaplasma urealyticum, but often the germ remains unidentified. Mechanisms through which susceptibility to reactive arthritis is linked to HLA-B27 antigen are still incompletely understood, but a clue could be cross-reactivity between B27 and a surface antigen of pathogenic germs. The clinical profile of the disease is characterized by an asymmetrical oligoarthritis with involvement particularly of the peripheral joints of the lower limbs. The arthritis generally recovers without sequelae within a few weeks or months. Accompanying features can be the involvement of enthesis and tendon sheets in form of a talalgia or dactylitis. In some cases the arthritis can relapse and chronicize. In some cases, in addition, involvement of the axial skeleton can occur (spondylitis and/or sacroiliitis). Another feature of the disease is the frequent association with typical extra-articular manifestations such as uveitis and muco-cutaneous lesions.

  20. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems......, the need for mathematically based formal methodology is increasingly important. There are many books that look at particular methodologies for such systems. This book offers a more balanced introduction for graduate students and describes the various approaches, their strengths and weaknesses, and when...

  1. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems, t...... into account. The book has arisen from various courses taught in Denmark and Iceland and is designed to give students a broad introduction to the area, with exercises throughout....

  2. Determinação da constante cinética de cristalização não-isotérmica de polipropilenos modificados com ácido acrílico e anidrido maleico Determination of the non-isothermal crystallization rate constant of grafted maleic anhydride and grafted acrylic acid polypropylenes

    Directory of Open Access Journals (Sweden)

    Benjamim de M. Carvalho

    2006-12-01

    Full Text Available O propósito do presente trabalho foi testar a validade do Método da Curva Mestre para a determinação da constante de cristalização não-isotérmica de polipropilenos modificados com anidrido maleico e ácido acrílico. Experimentos de cristalização não-isotérmica foram realizados a diversas taxas de resfriamento por meio de Calorimetria Exploratória Diferencial (DSC. Para serem usadas no Método da Curva Mestre, as curvas originais obtidas em DSC foram corrigidas em termos da defasagem de temperatura entre a amostra polimérica e o forno do equipamento. A equação de Nakamura e a constante de cristalização determinada foram utilizadas para simular as curvas de cristalinidade relativa em função da temperatura para as diversas taxas de resfriamento. As curvas simuladas apresentaram boa concordância com as curvas experimentais para ambas as amostras de polipropileno modificado, mostrando que o Método da Curva Mestre pode ser empregado com sucesso para este polímero.The purpose of the present work was to evaluate the Master Curve Approach in the determination of the non-isothermal crystallization constant, for samples of two modified polypropylenes (grafted maleic anhydride and grafted acrylic acid polypropylenes. Non-isothermal crystallization experiments were carried out in a differential scanning calorimeter, DSC, at several cooling rates. The original DSC curves were corrected for the temperature lag between the sample and the DSC furnace. The Nakamura equation and the non-isothermal crystallization constant obtained by the Master Curve Approach were employed to simulate the curves of relative crystallinity as a function of temperature, for the different cooling rates. The generated curves presented good agreement with the experimental data for both samples of grafted polypropylene, showing that the Master Curve Approach can be successfully employed for these polymers.

  3. Chemical and mineralogical characterization of highly and less reactive coal from Northern Natal and Venda-Pafuri coalfields in South Africa

    Science.gov (United States)

    Kataka, M. O.; Matiane, A. R.; Odhiambo, B. D. O.

    2018-01-01

    Spontaneous combustion of coal is a major hazard associated with the coal mining industry over centuries. It also a major cause of underground fires in South African collieries and in opencast operations, spoil heaps and stockpiles. Spontaneous combustion incidents are manifested in all major aspects of coal mining namely, underground mining, surface mining, including during sea-borne transportation, storage and waste disposal. Previous studies indicate that there are various factors (both intrinsic and extrinsic) that influence the spontaneous combustion of coals. This paper characterizes highly reactive coal from the Vryheid coalfields and less reactive coal from at Venda-Pafuri coalfield, to identify and delineate some intrinsic coal parameters that are considered to be most critical in terms of heat 'generation' and relationships between the two coals types by tracing their similarities and differences in their spontaneous combustion parameters. Various tests were carried out to characterize these coals in terms of their intrinsic properties, namely: ultimate, proximate, petrographic analysis and Glasser spontaneous tests. The ultimate and proximate analysis showed that spontaneous coal has high contents of carbon, oxygen, and volatile matter as compared to non-spontaneous coal, making it more susceptible to spontaneous combustion. Non-spontaneous coal has higher ash content than the spontaneous coal. Furthermore, the petrographic analysis showed that spontaneous coal has high total reactivity compared to the non-spontaneous coal. Results from Glasser spontaneous test indicate that spontaneous coal absorbs more oxygen than non-spontaneous coal, which explains why spontaneous coal is more susceptible to spontaneous combustion. High reactive coal has low values of critical self-heating temperature (CSHT), indicating that this coal has potential of spontaneous ignition.

  4. Scale Alpha and Beta of Quantitative Convergence and Chemical Reactivity Analysis in Dual Cholinesterase/Monoamine Oxidase Inhibitors for the Alzheimer Disease Treatment Using Density Functional Theory (DFT

    Directory of Open Access Journals (Sweden)

    Alejandro Morales-Bayuelo

    2013-01-01

    Full Text Available Molecular quantum similarity descriptors and Density Functional Theory (DFT based reactivity descriptors were studied for a series of cholinesterase/monoamine oxidase inhibitors used for the Alzheimer's disease treatment (AD. This theoretical study is expected to shed some light onto some molecular aspects that could contribute to the knowledge of the molecular mechanics behind interactions of these molecules with acetylcholinesterase (AChE and butyrylcholinesterase (BuChE, as well as with monoamine oxidase (MAO A and B. The Topogeometrical Superposition Algorithm to handle flexible molecules (TGSA-Flex alignment method was used to solve the problem of the relative orientation in the quantum similarity (QS field. Using the molecular quantum similarity (MQS field and reactivity descriptors supported in the DFT was possible the quantification of the steric and electrostatic effects through of the Coulomb and Overlap quantitative convergence scales (alpha and beta. In addition, an analysis of reactivity indexes is development, using global and local descriptors, identifying the binding sites and selectivity in the (cholinesterase/monoamine oxidase inhibitors, understanding the retrodonor process, and showing new insight for drugs design in a disease of difficult control as Alzheimer.

  5. Assessment of surface reactivity of thorium oxide in conditions close to chemical equilibrium by isotope exchange {sup 229}Th/{sup 232}Th method

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki-Muresan, Tomo; Perrigaud, Katy; Vandenborre, Johan; Ribet, Solange; Grambow, Bernd [Nantes Univ., CNRS/IN2P3 (France). SUBATECH Unite Mixte de Recherche 6457; Takamasa, Inai [TOKAI Univ., Kanagawa (Japan)

    2017-08-01

    This work aims to assess the solubility and the surface reactivity of crystallized thorium at pH 3.0 in presence of three types of solids: synthesized powder at 1300 C, crushed kernel, and intact kernel. In this study, the kernel is composed by the core solid from high temperature reactors (HTR) sphere particles. The originality of this work consisted in following in a sequential order the kinetic of dissolution, the surface reactivity in presence of isotope tracer {sup 229}Th, and its desorption process. Long time experiments (634 days) allowed to get deeper understanding on the behavior of the surface reactivity in contact with the solution. Solubility values are ranging from 0.3 x 10{sup -7} mol.L{sup -1} to 3 x 10{sup -7} mol.L{sup -1} with a dissolution rate of 10{sup -6}-10{sup -4} g.m{sup -2} day{sup -1}. PHREEQC modeling showed that crystallized ThO{sub 2}(cr, 20 nm) phase controls the equilibrium in solution. Isotope exchange between {sup 229}Th and {sup 232}Th indicated that well-crystallized phase exist as an inert surface regarding to the absence of exchange between surface solid and solution.

  6. Reactive arthritis.

    Science.gov (United States)

    Keat, A

    1999-01-01

    Reactive arthritis is one of the spondyloarthropathy family of clinical syndromes. The clinical features are those shared by other members of the spondyloarthritis family, though it is distinguished by a clear relationship with a precipitating infection. Susceptibility to reactive arthritis is closely linked with the class 1 HLA allele B27; it is likely that all sub-types pre-dispose to this condition. The link between HLA B27 and infection is mirrored by the development of arthritis in HLA B27-transgenic rats. In this model, arthritis does not develop in animals maintained in a germ-free environment. Infections of the gastrointestinal, genitourinary and respiratory tract appear to provoke reactive arthritis and a wide range of pathogens has now been implicated. Although mechanistic parallels may exist, reactive arthritis is distinguished from Lyme disease, rheumatic fever and Whipple's disease by virtue of the distinct clinical features and the link with HLA B27. As in these conditions both antigens and DNA of several micro-organisms have been detected in joint material from patients with reactive arthritis. The role of such disseminated microbial elements in the provocation or maintenance of arthritis remains unclear. HLA B27-restricted T-cell responses to microbial antigens have been demonstrated and these may be important in disease pathogenesis. The importance of dissemination of bacteria from sites of mucosal infection and their deposition in joints has yet to be fully understood. The role of antibiotic therapy in the treatment of reactive arthritis is being explored; in some circumstances, both the anti-inflammatory and anti-microbial effects of certain antibiotics appear to be valuable. The term reactive arthritis should be seen as a transitory one, reflecting a concept which may itself be on the verge of replacement, as our understanding of the condition develops. Nevertheless it appropriately describes arthritis that is associated with demonstrable

  7. Subsurface Transport Over Reactive Multiphases (STORM): A general, coupled, nonisothermal multiphase flow, reactive transport, and porous medium alteration simulator, Version 2 user's guide

    Energy Technology Data Exchange (ETDEWEB)

    DH Bacon; MD White; BP McGrail

    2000-03-07

    The Hanford Site, in southeastern Washington State, has been used extensively to produce nuclear materials for the US strategic defense arsenal by the Department of Energy (DOE) and its predecessors, the US Atomic Energy Commission and the US Energy Research and Development Administration. A large inventory of radioactive and mixed waste has accumulated in 177 buried single- and double shell tanks. Liquid waste recovered from the tanks will be pretreated to separate the low-activity fraction from the high-level and transuranic wastes. Vitrification is the leading option for immobilization of these wastes, expected to produce approximately 550,000 metric tons of Low Activity Waste (LAW) glass. This total tonnage, based on nominal Na{sub 2}O oxide loading of 20% by weight, is destined for disposal in a near-surface facility. Before disposal of the immobilized waste can proceed, the DOE must approve a performance assessment, a document that described the impacts, if any, of the disposal facility on public health and environmental resources. Studies have shown that release rates of radionuclides from the glass waste form by reaction with water determine the impacts of the disposal action more than any other independent parameter. This report describes the latest accomplishments in the development of a computational tool, Subsurface Transport Over Reactive Multiphases (STORM), Version 2, a general, coupled non-isothermal multiphase flow and reactive transport simulator. The underlying mathematics in STORM describe the rate of change of the solute concentrations of pore water in a variably saturated, non-isothermal porous medium, and the alteration of waste forms, packaging materials, backfill, and host rocks.

  8. The ab initio study and NBO interpretation of solvent effects on the structural stability and the chemical reactivity of penicillin-V conformations

    Directory of Open Access Journals (Sweden)

    Ali Akbar Salari

    2017-05-01

    Full Text Available Quantum mechanics (QM methods were used to examine the electronic structure and the relative stability of penicillin-V (PV conformations in the gas phase and the different solvent media. The effects of solvent dielectric constant and the computational methods were analyzed on the conformational stability of β-lactam-thiazolidine bicyclic system, its geometry and its reactivity. Our findings indicated that in the PV, the axial form of thiazolidine ring is more stable than equatorial form one in all of the tested media. This is in agreement with the NMR studies performed on PV that indicate the axial conformation is the dominant form in solid state. Furthermore, the atomic charges computations and natural bond orbital Interpretation (NBO represented that by increasing the solvent dielectric constant, the charge values on the C5 and C7 atoms of the β-lactam ring decrease, while HOMO–LUMO gap and occupancy values of the contained bonds in β-lactam ring of the interested structures increase. Hence, the β-lactam ring possesses the lowest reactivity against nucleophilic attacks and the highest stability in presence of implicit waters. However, it can be concluded that the structural stability of penicillin-V conformations is controlled by solvent’s polarity and its dielectric constant, the electrophilic nature of β-lactam ring and HOMO–LUMO gap.

  9. Physico-chemical properties and gasification reactivity of co-pyrolysis char from different rank of coal blended with lignocellulosic biomass: Effects of the cellulose.

    Science.gov (United States)

    Wu, Zhiqiang; Wang, Shuzhong; Luo, Zhengyuan; Chen, Lin; Meng, Haiyu; Zhao, Jun

    2017-07-01

    In this paper, the influence of cellulose on the physicochemical properties and the gasification reactivity of co-pyrolysis char was investigated. A specific surface area analyzer and an X-ray diffraction system were used to characterize the pore structure and the micro-crystalline structure of char. Fractal theory and deconvolution method were applied to quantitatively investigate the influence of cellulose on the structure of co-pyrolysis char. The results indicate that the improvements in the pore structure due to the presence of cellulose are more pronounced in the case of anthracite char with respect to bituminous char. Cellulose promotes the ordering of micro-scale structure and the uniformity of both anthracite and bituminous char, while the negative synergetic effect was observed during gasification of co-pyrolysis char. The exponential relationships between fractal dimension and specific surface area were determined, along with the relations between the gasification reactivity index and the microcrystalline structure parameter. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Involvement of laser photo-CIDNP (chemically induced dynamic nuclear polarization)-reactive amino acid side chains in ligand binding by galactoside-specific lectins in solution

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Siebert, H.-C; Adar, R.; Arango, R.; Burchert, M.; Kaltner, H.; Kayser, G.; Tajkhorshid, C.-W.

    1997-01-01

    For proteins in solution the validity of certain crystallographic parameters can be ascertained by a combination of molecular-dynamics (MD) simulations and NMR spectroscopy. Using the laser photoCIDNP (chemically induced dynamic nuclear polarization) technique as a measure for surface accessibility

  11. Reactivity and chemical characterization of effluent organic nitrogen from wastewater treatment plants determined by Fourier transform ion cyclotron resonance mass spectrometry.

    Science.gov (United States)

    Mesfioui, Rajaa; Love, Nancy G; Bronk, Deborah A; Mulholland, Margaret R; Hatcher, Patrick G

    2012-03-01

    In advanced wastewater treatment plants that achieve high levels of nitrogen (N) removal, up to one-third of the N in effluent is organic, herein referred to as effluent organic N (EON). While we know that inorganic N is highly labile, it is unclear what fraction of EON is bioavailable. In this study, we demonstrate the utility of a method that can be used to examine the reactivity of EON in natural receiving waters to better understand both the ecosystem response and the potential bioavailability of EON. The technique is suitable for analyzing polar organic matter in natural waters; electrospray ionization coupled with Fourier transform mass spectrometry. Bioassays were performed on samples collected at the end of the biological process from two wastewater treatment plants achieving advanced N removal. The samples were concentrated, and then added to natural water samples collected from the oligohaline James River, a major tributary of the Chesapeake Bay. Our results demonstrate that while the lignin-like fraction of the effluent dissolved organic matter (some of which contains N) was conserved, a large portion of aliphatic and aromatic compounds containing N was removed (79-100%) during incubations, while other compounds were produced. Furthermore, the two effluents exhibited differences in the degree of degradation and type of degradation, which can be related both to the various processes employed in the two WWTPs and the dramatic differences in the type of influent they received. These findings suggest that EON is highly reactive in the natural environment and that simple assays examining net consumption or production of bulk dissolved organic N pools are inadequate for assessing the bioavailability of EON. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems, t...... into account. The book has arisen from various courses taught in Denmark and Iceland and is designed to give students a broad introduction to the area, with exercises throughout......., the need for mathematically based formal methodology is increasingly important. There are many books that look at particular methodologies for such systems. This book offers a more balanced introduction for graduate students and describes the various approaches, their strengths and weaknesses, and when...... they are best used. Milner's CCS and its operational semantics are introduced, together with the notions of behavioural equivalences based on bisimulation techniques and with recursive extensions of Hennessy-Milner logic. In the second part of the book, the presented theories are extended to take timing issues...

  13. On Diffusion of Chemically Reactive Species in a Convective Flow Past an Inclined Plate with Variable Surface Temperature and Variable Mass Diffusion

    Directory of Open Access Journals (Sweden)

    Kirubavathi J.D.

    2016-12-01

    Full Text Available A numerical solution of a transient natural convection flow past a semi-infinite inclined plate under the combined buoyancy effects of heat and mass transfer along with chemical reaction is presented herewith. The governing boundary layer equations for the above flow problem for a first order homogeneous chemical reaction are set up and non-dimensionalised. An implicit finite difference method is employed to solve the unsteady, nonlinear, integro and coupled partial differential equation. Numerical results are presented for various parameters occurring in the problem. The unsteady velocity, temperature and concentration profiles, local and average skin friction, Nusselt number and Sherwood number are studied for both a generative and destructive reaction.

  14. On doubly stratified chemically reactive flow of Powell–Eyring liquid subject to non-Fourier heat flux theory

    Directory of Open Access Journals (Sweden)

    T. Hayat

    Full Text Available This investigation addresses the chemical reaction and double stratification effects in the flow induced by a nonlinear stretching surface with variable thickness. Flow formulation is developed using rheological expressions of Eyring–Powell liquid. Salient features of heat transfer are examined by considering non-Fourier heat flux model. Formulation is arranged for variable thermal conductivity. Flux model under consideration is the generalized form of Fourier’s classical expression with thermal relaxation time. Ordinary differential systems are obtained through implementation of appropriate transformations. Convergent series solutions are constructed. Non-dimensional velocity, temperature, concentration, skin friction and Sherwood number are displayed and discussed. It is anticipated that thermal and concentration stratified parameters decay the temperature and concentration respectively. Keywords: Double stratification, Chemical reaction, Eyring–Powell liquid, Non-Fourier heat flux model, Variable thermal conductivity

  15. Identification of the binding sites of the SR49059 nonpeptide antagonist into the V1a vasopressin receptor using sulfydryl-reactive ligands and cysteine mutants as chemical sensors.

    Science.gov (United States)

    Tahtaoui, Chouaïb; Balestre, Marie-Noëlle; Klotz, Philippe; Rognan, Didier; Barberis, Claude; Mouillac, Bernard; Hibert, Marcel

    2003-10-10

    To identify the binding site of the human V1a vasopressin receptor for the selective nonpeptide antagonist SR49059, we have developed a site-directed irreversible labeling strategy that combines mutagenesis of the receptor and use of sulfydryl-reactive ligands. Based on a three-dimensional model of the antagonist docked into the receptor, hypothetical ligand-receptor interactions were investigated by replacing the residues potentially involved in the binding of the antagonist into cysteines and designing analogues of SR49059 derivatized with isothiocyanate or alpha-chloroacetamide moieties. The F225C, F308C, and K128C mutants of the V1a receptor were expressed in COS-7 or Chinese hamster ovary cells, and their pharmacological properties toward SR49059 and its sulfydryl-reactive analogues were analyzed. We demonstrated that treatment of the F225C mutant with the isothiocyanate-derivative compound led to dose-dependent inhibition of the residual binding of the radio-labeled antagonist [125I]HO-LVA. This inhibition is probably the consequence of a covalent irreversible chemical modification, which is only possible when close contacts and optimal orientations exist between reactive groups created both on the ligand and the receptor. This result validated the three-dimensional model hypothesis. Thus, we propose that residue Phe225, located in transmembrane domain V, directly participates in the binding of the V1a-selective nonpeptide antagonist SR49059. This conclusion is in complete agreement with all our previous data on the definition of the agonist/antagonist binding to members of the oxytocin/vasopressin receptor family.

  16. 1D Thermal-Hydraulic-Chemical (THC) Reactive transport modeling for deep geothermal systems: A case study of Groß Schönebeck reservoir, Germany

    Science.gov (United States)

    Driba, D. L.; De Lucia, M.; Peiffer, S.

    2014-12-01

    Fluid-rock interactions in geothermal reservoirs are driven by the state of disequilibrium that persists among solid and solutes due to changing temperature and pressure. During operation of enhanced geothermal systems, injection of cooled water back into the reservoir disturbs the initial thermodynamic equilibrium between the reservoir and its geothermal fluid, which may induce modifications in permeability through changes in porosity and pore space geometry, consequently bringing about several impairments to the overall system.Modeling of fluid-rock interactions induced by injection of cold brine into Groß Schönebeck geothermal reservoir system situated in the Rotliegend sandstone at 4200m depth have been done by coupling geochemical modeling Code Phreeqc with OpenGeoSys. Through batch modeling the re-evaluation of the measured hydrochemical composition of the brine has been done using Quintessa databases, the results from the calculation indicate that a mineral phases comprising of K-feldspar, hematite, Barite, Calcite and Dolomite was found to match the hypothesis of equilibrium with the formation fluid, Reducing conditions are presumed in the model (pe = -3.5) in order to match the amount of observed dissolved Fe and thus considered as initial state for the reactive transport modeling. based on a measured composition of formation fluids and the predominant mineralogical assemblage of the host rock, a preliminary 1D Reactive transport modeling (RTM) was run with total time set to 30 years; results obtained for the initial simulation revealed that during this period, no significant change is evident for K-feldspar. Furthermore, the precipitation of calcite along the flow path in the brine results in a drop of pH from 6.2 to a value of 5.2 noticed over the simulated period. The circulation of cooled fluid in the reservoir is predicted to affect the temperature of the reservoir within the first 100 -150m from the injection well. Examination of porosity change in

  17. Influence of Mg doping on the early steps of physico-chemical reactivity of sol-gel derived bioactive glasses in biological medium.

    Science.gov (United States)

    Soulié, J; Nedelec, J M; Jallot, E

    2009-11-28

    The aim of this study is to highlight the influence of magnesium doping on the surface reactivity of binary (SiO(2)-CaO) and ternary (SiO(2)-CaO-P(2)O(5)) bioactive glasses, prepared by sol-gel chemistry, in biological conditions. These materials were produced in powder form, and their compositional and textural properties characterized. They were then soaked in biological fluids for different delays from 0 to 4 days. The surface changes were characterized using Particles Induced X-ray Emission (PIXE) associated with Rutherford Backscattering Spectroscopy (RBS), which are efficient methods for multi-elemental analysis. Elemental maps of major and trace elements were obtained at a micrometer scale and revealed the formation of a calcium phosphate-rich layer after a few days of interaction. We demonstrate that the presence of magnesium in the material has an impact on the development and the formation rate of the bone-like apatite layer.

  18. Synthesis of novel anthraquinones: Molecular structure, molecular chemical reactivity descriptors and interactions with DNA as antibiotic and anti-cancer drugs

    Science.gov (United States)

    Al-Otaibi, Jamelah S.; EL Gogary, Tarek M.

    2017-02-01

    Anthraquinones are well-known anticancer drugs. Anthraquinones anticancer drugs carry out their cytotoxic activities through their interaction with DNA, and inhibition of topoisomerase II activity. Anthraquinones (AQ5 and AQ5H) were synthesized and studied with 1,5-DAAQ by computational and experimental tools. The purpose of this study is to shade more light on mechanism of interaction between anthraquinone DNA affinic agents and different types of DNA. This study will lead to gain of information useful for drug design and development. Molecular structures were optimized using DFT B3LYP/6-31 + G(d). Depending on intramolecular hydrogen bonding interactions four conformers of AQ5 were detected within the range of about 42 kcal/mol. Molecular reactivity of the anthraquinone compounds was explored using global and condensed descriptors (electrophilicity and Fukui functions). NMR and UV-VIS electronic absorption spectra of anthraquinones/DNA were investigated at the physiological pH. The interaction of the anthraquinones (AQ5 and AQ5H) were studied with different DNA namely, calf thymus DNA, (Poly[dA].Poly[dT]) and (Poly[dG].Poly[dC]). UV-VIS electronic absorption spectral data were employed to measure the affinity constants of drug/DNA binding using Scatchard analysis. NMR study confirms qualitatively the drug/DNA interaction in terms of peak shift and broadening.

  19. Increased pattern transfer fidelity ZEP 520A during reactive ion etching through chemical modifications by additional dosing of the electron beam resist.

    Energy Technology Data Exchange (ETDEWEB)

    Czaplewski, D. A.; Ocola, L. E. (Center for Nanoscale Materials)

    2011-03-01

    This article describes a postdevelopment, additional electron exposure to enhance the etch selectivity and improve pattern transfer fidelity of an electron beam resist, ZEP 520A, through chemical changes of the resist. After the critical features were patterned and developed, the resist was exposed at 5 kV accelerating voltage to a second dose of electrons ranging from 300 to 300,000 {micro}C/cm{sup 2}. The etch rate of the resist decreased by approximately 25% in a CHF{sub 3} and O{sub 2} plasma. More critically, the fidelity of the pattern transfer was improved. Infrared and Raman spectroscopies were used to characterize the resist before and after electron beam exposure for doses up to 3000 {micro}C/cm{sup 2}. The carbonyl bonding in the polymer showed significant changes after electron beam exposure that can be associated with improvement in the etch performance of this resist.

  20. Increased pattern transfer fidelity of ZEP 520A during reactive ion etching through chemical modifications by additional dosing of the electron beam resist

    Energy Technology Data Exchange (ETDEWEB)

    Czaplewski, D. A.; Ocola, L. E. (Center for Nanoscale Materials)

    2011-01-01

    This article describes a postdevelopment, additional electron exposure to enhance the etch selectivity and improve pattern transfer fidelity of an electron beam resist, ZEP 520A, through chemical changes of the resist. After the critical features were patterned and developed, the resist was exposed at 5 kV accelerating voltage to a second dose of electrons ranging from 300 to 300,000 {micro}C/cm{sup 2}. The etch rate of the resist decreased by approximately 25% in a CHF{sub 3} and O{sub 2} plasma. More critically, the fidelity of the pattern transfer was improved. Infrared and Raman spectroscopies were used to characterize the resist before and after electron beam exposure for doses up to 3000 {micro}C/cm{sup 2}. The carbonyl bonding in the polymer showed significant changes after electron beam exposure that can be associated with improvement in the etch performance of this resist.

  1. Ignition delay and soot oxidative reactivity of MTBE blended diesel fuel

    KAUST Repository

    Yang, Seung Yeon

    2014-04-01

    Methyl tert-butyl ether (MTBE) was added to diesel fuel to investigate the effect on ignition delay and soot oxidative reactivity. An ignition quality tester (IQT) was used to study the ignition propensity of MTBE blended diesel fuels in a reactive spray environment. The IQT data showed that ignition delay increases linearly as the MTBE fraction increases in the fuel. A four-stroke single cylinder diesel engine was used to generate soot samples for a soot oxidation study. Soot samples were pre-treated using a tube furnace in a nitrogen environment to remove any soluble organic fractions and moisture content. Non-isothermal oxidation of soot samples was conducted using a thermogravimetric analyzer (TGA). It was observed that oxidation of \\'MTBE soot\\' started began at a lower temperature and had higher reaction rate than \\'diesel soot\\' across a range of temperatures. Several kinetic analyses including an isoconversional method and a combined model fitting method were carried out to evaluate kinetic parameters. The results showed that Diesel and MTBE soot samples had similar activation energy but the pre-exponential factor of MTBE soot was much higher than that of the Diesel soot. This may explain why MTBE soot was more reactive than Diesel soot. It is suggested that adding MTBE to diesel fuel is better for DPF regeneration since an MTBE blend can significantly influence the ignition characteristics and, consequently, the oxidative reactivity of soot. Copyright © 2014 SAE International.

  2. Separability of local reactivity descriptors

    Indian Academy of Sciences (India)

    Unknown

    There have been recent studies on the qualitative and quantitative description of these con- cepts and use of these in the selectivity of reactions in catalysis, adsorption and molecular recognition. Global reactivity descriptors (GRD), like softness, hardness and chemical potential along with concept of hard soft acid base ...

  3. Controlling reactive materials by crystallisation and hosting

    OpenAIRE

    Martin, Alan

    2014-01-01

    The research herein presents an approach to stabilising reactive materials by engineering and designing strategies for forming multi-component materials containing the reactive molecules by use of their non-covalent intermolecular interactions. These interactions may be utilised as part of a design approach to create new materials of more beneficial physical and chemical properties for the desired application.The reactive materials focussed on in this research are organic peroxyacids, in part...

  4. [Studies of the formation chemical reactivity and properties of small clusters application to an understanding of aerosol formation and heterogeneous chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Castleman, A.W. Jr.

    1992-01-01

    Chemical reactions that proceed following either a photophysical or ionizing event, are directly influenced by the mechanisms of energy transfer and dissipation away from the primary site of absorption. Neighboring solvent or solute molecules can affect this by collisional deactivation (removal of energy), through effects in which dissociating molecules are kept in relatively close proximity for comparatively long periods of time due to the presence of the solvent, and in other ways where the solvent influences the energetics of the reaction coordinate. Research on clusters offers one of the most viable ways of elucidating the molecular details of these processes. The current program is comprised of three general areas of research. Investigation of the dynamics of ionization and the mechanisms of the early-time reactions following the interaction of ionizing electromagnetic radiation with matter; measurement of the kinetics of ensuing ion reactions with effort focused on the influence of solvation effects and identifying similarities and differences between gas and condensed phase reactions; and determination of the structure of solvated reaction centers via spectroscopy, dynamics and thermochemistry.

  5. [Studies of the formation chemical reactivity and properties of small clusters application to an understanding of aerosol formation and heterogeneous chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Castleman, A.W. Jr.

    1992-12-31

    Chemical reactions that proceed following either a photophysical or ionizing event, are directly influenced by the mechanisms of energy transfer and dissipation away from the primary site of absorption. Neighboring solvent or solute molecules can affect this by collisional deactivation (removal of energy), through effects in which dissociating molecules are kept in relatively close proximity for comparatively long periods of time due to the presence of the solvent, and in other ways where the solvent influences the energetics of the reaction coordinate. Research on clusters offers one of the most viable ways of elucidating the molecular details of these processes. The current program is comprised of three general areas of research. Investigation of the dynamics of ionization and the mechanisms of the early-time reactions following the interaction of ionizing electromagnetic radiation with matter; measurement of the kinetics of ensuing ion reactions with effort focused on the influence of solvation effects and identifying similarities and differences between gas and condensed phase reactions; and determination of the structure of solvated reaction centers via spectroscopy, dynamics and thermochemistry.

  6. Magneto-nanofluid numerical modelling of chemically reactive Eyring-Powell fluid flow towards both flat and cylindrical an inclined surfaces: A comparative study

    Science.gov (United States)

    Rehman, Khalil Ur; Ali Khan, Abid; Malik, M. Y.

    2017-06-01

    An article is made to report the combined effects of both chemical reaction and dual stratification on boundary layer magneto-hydrodynamic Eyring Powell nanofluid flow towards both flat and cylindrical an inclined stretching surfaces under the region of stagnation point along with heat and mass transfer characteristics. The flow situation is carried out by considering physical effects namely, thermal radiation and heat generation. To be more specific, the fluid flow is entertained through no slip condition i-e the velocity of particles is directly related to velocity of surface due to stretching. The physical situation within the real concerned constraints is translated in terms of differential equations as a boundary value problem. To make implementation of computational algorithm possible, firstly the intricate PDE's are transformed into ODE's by using suitable transformation, secondly resulting boundary value problem is converted into an initial value problem. These constructed ordinary differential equations are solved computationally by shooting technique charted with Runge-Kutta scheme. The effect logs of involved physical flow parameters are explored with the aid of graphical outcomes and tabular values. A straight line curve fitting way of communication is executed to inspect the impact of both thermophoresis parameter and Brownian motion parameter on heat and mass transfer rates. It is found that heat transfer normal to the cylindrical surface shows decline attitude towards both thermophoresis and Brownian motion parameters.

  7. Non-isothermal nanocrystallization kinetics study on (Fe{sub 0.8}Ni{sub 0.15}M{sub 0.05}){sub 78}Si{sub 8}B{sub 14} (M = Nb, Ta, W) amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yu [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Shanghai Key Lab. of D and A for Metal-Functional Materials, Shanghai 201804 (China); Yan, Biao, E-mail: yanbiao@vip.sina.com [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Shanghai Key Lab. of D and A for Metal-Functional Materials, Shanghai 201804 (China); Yang, Ying [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Shanghai Key Lab. of D and A for Metal-Functional Materials, Shanghai 201804 (China); Wang, Yuxin [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Shanghai Key Lab. of D and A for Metal-Functional Materials, Shanghai 201804 (China); Dept. of Chemical and Materials Engineering, The University of Auckland, PB 92019, Auckland 1142 (New Zealand)

    2013-10-15

    Highlights: •Nb, Ta and W addition affected nucleation and growth mechanism of FeNiSiB alloys. •The alloy with Ta had the best thermal stability compared to the other two alloys. •A process of Fe2B from metastable Fe3B phase existed in the alloy M = Ta. •Nb and W may inhibit formation of metastable Fe3B phase. -- Abstract: The nanocrystallization kinetics of the (Fe{sub 0.8}Ni{sub 0.15}M{sub 0.05}){sub 78}Si{sub 8}B{sub 14} (M = Nb, Ta, W) amorphous alloy was investigated by differential scanning calorimetry (DSC). Kissinger method, Ozawa method and the expended Friedman method were used to calculate and compare the kinetic parameters of the crystallization processes. The nanocrystallization mechanism for the non-isothermal primary crystallization of the amorphous alloys were discussed using Avrami exponent n. Transmission electron microscopy (TEM) studies verified the influence of nanocrystallization mechanism on the microstructure.

  8. Frustrated Lewis pairs: Design and reactivity

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 127; Issue 2. Frustrated Lewis pairs: Design and reactivity. Sanjoy Mukherjee Pakkirisamy Thilagar. Volume 127 Issue 2 ... main group as well as transition metal chemistry. The design strategies adopted for FLP systems and their unique reactivity are discussed here.

  9. The Maillard reaction of a shrimp by-product protein hydrolysate: chemical changes and inhibiting effects of reactive oxygen species in human HepG2 cells.

    Science.gov (United States)

    Zha, Fengchao; Wei, Binbin; Chen, Shengjun; Dong, Shiyuan; Zeng, Mingyong; Liu, Zunying

    2015-06-01

    Recently, much attention has been given to improving the antioxidant activity of protein hydrolysates via the Maillard reaction, but little is known about the cellular antioxidant activity of Maillard reaction products (MRPs) from protein hydrolysates. We first investigated chemical characterization and the cellular antioxidant activity of MRPs in a shrimp (Litopenaeus vannamei) by-product protein hydrolysate (SBH)-glucose system at 110 °C for up to 10 h of heating. Solutions of SBH and glucose were also heated alone as controls. The Maillard reaction greatly resulted in the increase of hydroxymethylfurfural (HMF) and browning intensity, high molecular weight fraction, and reduction of the total amino acid in SBH with the heating time, which correlated well with the free radical scavenging activity of MRPs. MRPs had stronger inhibiting effects on oxidative stress of human HepG2 cells than the original SBH, and its cellular antioxidant activity strongly correlated with free radical scavenging activity, but less affected by the browning intensity and HMF level. The caramelization of glucose partially affected the HMF level and free radical scavenging activity of MRPs, but it was not related to the cellular antioxidant activity. The cellular antioxidant activity of MRPs for 5 h of heating time appeared to reach a maximum level, which was mainly due to carbonyl ammonia condensation reaction. In conclusion, the Maillard reaction is a potential method to increase the cellular antioxidant activity of a shrimp by-product protein hydrolysate, but the higher HMF levels and the lower amino acid content in MRPs should also be considered.

  10. Numerical simulation of in-situ chemical oxidation (ISCO) and biodegradation of petroleum hydrocarbons using a coupled model for bio-geochemical reactive transport

    Science.gov (United States)

    Marin, I. S.; Molson, J. W.

    2013-05-01

    Petroleum hydrocarbons (PHCs) are a major source of groundwater contamination, being a worldwide and well-known problem. Formed by a complex mixture of hundreds of organic compounds (including BTEX - benzene, toluene, ethylbenzene and xylenes), many of which are toxic and persistent in the subsurface and are capable of creating a serious risk to human health. Several remediation technologies can be used to clean-up PHC contamination. In-situ chemical oxidation (ISCO) and intrinsic bioremediation (IBR) are two promising techniques that can be applied in this case. However, the interaction of these processes with the background aquifer geochemistry and the design of an efficient treatment presents a challenge. Here we show the development and application of BIONAPL/Phreeqc, a modeling tool capable of simulating groundwater flow, contaminant transport with coupled biological and geochemical processes in porous or fractured porous media. BIONAPL/Phreeqc is based on the well-tested BIONAPL/3D model, using a powerful finite element simulation engine, capable of simulating non-aqueous phase liquid (NAPL) dissolution, density-dependent advective-dispersive transport, and solving the geochemical and kinetic processes with the library Phreeqc. To validate the model, we compared BIONAPL/Phreeqc with results from the literature for different biodegradation processes and different geometries, with good agreement. We then used the model to simulate the behavior of sodium persulfate (NaS2O8) as an oxidant for BTEX degradation, coupled with sequential biodegradation in a 2D case and to evaluate the effect of inorganic geochemistry reactions. The results show the advantages of a treatment train remediation scheme based on ISCO and IBR. The numerical performance and stability of the integrated BIONAPL/Phreeqc model was also verified.

  11. Label-free proteomics assisted by affinity enrichment for elucidating the chemical reactivity of the liver mitochondrial proteome toward adduction by the lipid electrophile 4-hydroxy-2-nonenal (HNE)

    Science.gov (United States)

    Maier, Claudia

    2016-03-01

    The analysis of oxidative stress-induced post-translational modifications remains challenging due to the chemical diversity of these modifications, the possibility of the presence of positional isomers and the low stoichiometry of the modified proteins present in a cell or tissue proteome. Alcoholic liver disease (ALD) is a multifactorial disease in which mitochondrial dysfunction and oxidative stress have been identified as being critically involved in the progression of the disease from steatosis to cirrhosis. Ethanol metabolism leads to increased levels of reactive oxygen species (ROS), glutathione depletion and lipid peroxidation. Posttranslational modification of proteins by electrophilic products of lipid peroxidation has been associated with governing redox-associated signaling mechanisms, but also as contributing to protein dysfunction leading to organelle and liver injury. In particular the prototypical α,β-unsaturated aldehyde, 4-hydroxy-2-nonenal (HNE), has been extensively studied as marker of increased oxidative stress in hepatocytes. In this study, we combined a LC-MS label-free quantification method and affinity enrichment to assess the dose-dependent insult by HNE on the proteome of rat liver mitochondria. We used a carbonyl-selective probe, the ARP probe, to label HNE-protein adducts and to perform affinity capture at the protein level. Using LC-MS to obtain protein abundance estimates, a list of protein targets was obtained with increasing concentration of HNE used in the exposure studies. In parallel, we performed affinity capture at the peptide level to acquire site-specific information. Examining the concentration-dependence of the protein modifications, we observed distinct reactivity profiles for HNE-protein adduction. Pathway analysis indicated that proteins associated with metabolic processes, including amino acid, fatty acid and glyoxylate and dicarboxylate metabolism, bile acid synthesis and TCA cycle, showed enhanced reactivity to HNE

  12. Label-free proteomics assisted by affinity enrichment for elucidating the chemical reactivity of the liver mitochondrial proteome toward adduction by the lipid electrophile 4-hydroxy-2-nonenal (HNE

    Directory of Open Access Journals (Sweden)

    Claudia S Maier

    2016-03-01

    Full Text Available The analysis of oxidative stress-induced post-translational modifications remains challenging due to the chemical diversity of these modifications, the possibility of the presence of positional isomers and the low stoichiometry of the modified proteins present in a cell or tissue proteome. Alcoholic liver disease (ALD is a multifactorial disease in which mitochondrial dysfunction and oxidative stress have been identified as being critically involved in the progression of the disease from steatosis to cirrhosis. Ethanol metabolism leads to increased levels of reactive oxygen species (ROS, glutathione depletion and lipid peroxidation. Posttranslational modification of proteins by electrophilic products of lipid peroxidation has been associated with governing redox-associated signaling mechanisms, but also as contributing to protein dysfunction leading to organelle and liver injury. In particular the prototypical α,β-unsaturated aldehyde, 4-hydroxy-2-nonenal (HNE, has been extensively studied as marker of increased oxidative stress in hepatocytes. In this study, we combined a LC-MS label-free quantification method and affinity enrichment to assess the dose-dependent insult by HNE on the proteome of rat liver mitochondria. We used a carbonyl-selective probe, the ARP probe, to label HNE-protein adducts and to perform affinity capture at the protein level. Using LC-MS to obtain protein abundance estimates, a list of protein targets was obtained with increasing concentration of HNE used in the exposure studies. In parallel, we performed affinity capture at the peptide level to acquire site-specific information. Examining the concentration-dependence of the protein modifications, we observed distinct reactivity profiles for HNE-protein adduction. Pathway analysis indicated that proteins associated with metabolic processes, including amino acid, fatty acid and glyoxylate and dicarboxylate metabolism, bile acid synthesis and TCA cycle, showed enhanced

  13. Molecular structure, spectral investigation (1H NMR, 13C NMR, UV-Visible, FT-IR, FT-Raman), NBO, intramolecular hydrogen bonding, chemical reactivity and first hyperpolarizability analysis of formononetin [7-hydroxy-3(4-methoxyphenyl)chromone]: A quantum chemical study

    Science.gov (United States)

    Srivastava, Anubha; Mishra, Rashmi; Kumar, Sudhir; Dev, Kapil; Tandon, Poonam; Maurya, Rakesh

    2015-03-01

    Formononetin [7-hydroxy-3(4-methoxyphenyl)chromone or 4‧-methoxy daidzein] is a soy isoflavonoid that is found abundantly in traditional Chinese medicine Astragalus mongholicus (Bunge) and Trifolium pretense L. (red clover), and in an Indian medicinal plant, Butea (B.) monosperma. Crude extract of B.monosperma is used for rapid healing of fracture in Indian traditional medicine. In this study, a combined theoretical and experimental approach is used to study the properties of formononetin. The optimized geometry was calculated by B3LYP method using 6-311++G(d,p) as a large basis set. The FT-Raman and FT-IR spectra were recorded in the solid phase, and interpreted in terms of potential energy distribution (PED) analysis. Density functional theory (DFT) is applied to explore the nonlinear optical properties of the molecule. Good consistency is found between the calculated results and observed data for the electronic absorption, IR and Raman spectra. The solvent effects have been calculated using time-dependent density functional theory in combination with the integral equation formalism polarized continuum model, and the results are in good agreement with observed measurements. The double well potential energy curve of the molecule about the respective bonds, have been plotted, as obtained from DFT/6-31G basis set. The computational results diagnose the most stable conformer of formononetin. The HOMO-LUMO energy gap of possible conformers has been calculated for comparing their chemical activity. Chemical reactivity has been measured by reactivity descriptors and molecular electrostatic potential surface (MEP). The 1H and 13C NMR chemical shifts of the molecule were calculated by the Gauge including atomic orbital (GIAO) method. Furthermore, the role of CHsbnd O intramolecular hydrogen bond in the stability of molecule is investigated on the basis of the results of topological properties of AIM theory and NBO analysis. The calculated first hyperpolarizability shows

  14. Synthesis, characterisation and non-isothermal degradation kinetics ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 7 ... Synthesis of a novel co-polymer made by the addition polymerisation between MEGDMA and 4-AB by aza-Michael addition (AMA) polymerisation method is a ... Among the modelsused, the Kissinger method yielded the lowest degradation kinetics.

  15. Synthesis, characterisation and non-isothermal degradation kinetics ...

    Indian Academy of Sciences (India)

    terized by Fourier transform infrared spectroscopy, UV–visible reflectance spectroscopy, X-ray diffraction, differ- ential scanning calorimetry .... lytical techniques, such as Fourier transform infrared (FTIR) spectroscopy, UV–visible ..... [15] Kim T I, Seo H J, Baek J H, Park J H and Park J S 2005 Bull. Korean Chem. Soc. 26 175.

  16. Synthesis, non-isothermal crystallization and magnetic properties of ...

    Indian Academy of Sciences (India)

    ing agents in magnetic resonance imaging (MRI) (Arshady. 1993; Wiltshire et al 2001). The impregnation of mag- netic fillers in the polymer matrix imparts the magnetic pro- perties and modifies the physical properties of the matrix considerably. However, mechanical properties of the poly- mer bonded magnets depend ...

  17. Thermographic analysis of turbulent non-isothermal water boundary layer

    CERN Document Server

    Znamenskaya, Irina A

    2015-01-01

    The paper is devoted to the investigation of the turbulent water boundary layer in the jet mixing flows using high-speed infrared (IR) thermography. Two turbulent mixing processes were studied: a submerged water jet impinging on a flat surface and two intersecting jets in a round disc-shaped vessel. An infrared camera (FLIR Systems SC7700) was focused on the window transparent for IR radiation; it provided high-speed recordings of heat fluxes from a thin water layer close to the window. Temperature versus time curves at different points of water boundary layer near the wall surface were acquired using the IR camera with the recording frequency of 100 Hz. The time of recording varied from 3 till 20 min. The power spectra for the temperature fluctuations at different points on the hot-cold water mixing zone were calculated using the Fast Fourier Transform algorithm. The obtained spectral behavior was compared to the Kolmogorov "-5/3 spectrum" (a direct energy cascade) and the dual-cascade scenario predicted for...

  18. Fluid/Solid Boundary Conditions in Non-Isothermal Systems

    Science.gov (United States)

    Rosner, Daniel E.

    1999-01-01

    The existing theoretical research concerned with thermal creep at fluid/solid interfaces is briefly reviewed, and the importance of microgravity-based experimental data is then discussed. It is noted that the ultimate goal of this research is a rational molecular level theory that predicts the dependence of a dimensionless thermal creep coefficient, Ctc, on relevant dimensionless parameters describing the way fluid molecules interact with the solid surface and how they interact among themselves. The discussion covers thermophoresis of isolated solid spheres and aggregates in gases; solid sphere thermophoresis in liquids and dense vapors; thermophoresis of small immiscible liquid droplets; and applications of the direct simulation Monte Carlo method.

  19. Simulation of non-isothermal transient flow in gas pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira Junior, Luis Carlos; Soares, Matheus; Lima, Enrique Luis; Pinto, Jose Carlos [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Quimica; Muniz, Cyro; Pires, Clarissa Cortes; Rochocz, Geraldo [ChemTech, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    Modeling of gas pipeline usually considers that the gas flow is isothermal (or adiabatic) and that pressure changes occur instantaneously (quasi steady state approach). However, these assumptions are not valid in many important transient applications (changes of inlet and outlet flows/pressures, starting and stopping of compressors, changes of controller set points, among others). Besides, the gas properties are likely to depend simultaneously on the pipe position and on the operation time. For this reason, a mathematical model is presented and implemented in this paper in order to describe the gas flow in pipeline when pressure and temperature transients cannot be neglected. The model is used afterwards as a tool for reconciliation of available measured data. (author)

  20. Mathematical modelling of non-isothermal flow in buildings

    Science.gov (United States)

    Lenhard, Richard; Puchor, Tomáš

    Numerical simulations are used in many areas of science and technology. In last time are numerical methods used not only in small scale applications, in fluid mechanics, but are also used in civil engineering for simulation of air flow, for simulation of heat transfer. This paper deals with simulation of air flow in building for municipal use. The core of the paper is the calculation of the input parameters for the creation of numerical model and description of the model itself. The conclusion provides an analysis and comparison of simulation results with calculated values for the building.

  1. Non-isothermal kinetics of thermal degradation of chitosan

    Directory of Open Access Journals (Sweden)

    Georgieva Velyana

    2012-08-01

    Full Text Available Abstract Background Chitosan is the second most abundant nitrogen containing biopolymer in nature, obtained from the shells of crustaceans, particularly crabs, shrimp and lobsters, which are waste products of seafood processing industries. It has great potential application in the areas of biotechnology, biomedicine, food industries, and cosmetics. Chitosan is also capable of adsorbing a number of metal ions as its amino groups can serve as chelation sites. Grafted functional groups such as hydroxyl, carboxyl, sulfate, phosphate, and amino groups on the chitosan have been reported to be responsible for metal binding and sorption of dyes and pigments. The knowledge of their thermal stability and pyrolysis may help to better understand and plan their industrial processing. Results Thermogravimetric studies of chitosan in air atmosphere were carried out at six rates of linear increasing of the temperature. The kinetics and mechanism of the thermal decomposition reaction were evaluated from the TG data using recommended from ICTAC kinetics committee iso-conversional calculation procedure of Kissinger-Akahira-Sunose, as well as 27 mechanism functions. The comparison of the obtained results showed that they strongly depend on the selection of proper mechanism function for the process. Therefore, it is very important to determine the most probable mechanism function. In this respect the iso-conversional calculation procedure turned out to be the most appropriate. Conclusion Chitosan have excellent properties such as hydrophilicity, biocompatibility, biodegradability, antibacterial, non-toxicity, adsorption application. The thermal degradation of chitosan occurs in two stages. The most probable mechanism function for both stages is determined and it was best described by kinetic equations of n-th order (Fn mechanism. For the first stage, it was established that n is equal to 3.0 and for the second stage – to 1.0 respectively. The values of the apparent activation energy E, pre-exponential factor A in Arrhenius equation, as well as the changes of entropy ΔS≠, enthalpy ΔH≠ and free Gibbs energy ΔG≠ for the formation of the activated complex from the reagent are calculated.

  2. A benchmark study on non-isothermal compositional fluid flow

    DEFF Research Database (Denmark)

    Singh, Ashok; Böttcher, Norbert; Görke, U. J.

    2013-01-01

    CO2 capture and storage technology is often hampered by CO2 leakage through natural occurring fractures in the overlying caprock. This work suggests a two-dimensional test case of typical CO2 injection with possible leakage into freshwater resource. By using this test case in combination with a 1...

  3. Calorimetric studies of non-isothermal crystallization in amorphous

    Indian Academy of Sciences (India)

    Administrator

    calorimeter (DSC) technique. The applicability of Meyer–Neldel relation between the ... Amorphous materials; differential scanning calorimetry (DSC); phase transitions. 1. Introduction. There is a significant attention to ... factor K0 of the rate constant K with the activation energy of crystallization Ec by changing the variation of ...

  4. Kinetics of non-isothermal decomposition of cinnamic acid

    Science.gov (United States)

    Zhao, Ming-rui; Qi, Zhen-li; Chen, Fei-xiong; Yue, Xia-xin

    2014-07-01

    The thermal stability and kinetics of decomposition of cinnamic acid were investigated by thermogravimetry and differential scanning calorimetry at four heating rates. The activation energies of this process were calculated from analysis of TG curves by methods of Flynn-Wall-Ozawa, Doyle, Distributed Activation Energy Model, Šatava-Šesták and Kissinger, respectively. There are only one stage of thermal decomposition process in TG and two endothermic peaks in DSC. For this decomposition process of cinnamic acid, E and log A[s-1] were determined to be 81.74 kJ mol-1 and 8.67, respectively. The mechanism was Mampel Power law (the reaction order, n = 1), with integral form G(α) = α (α = 0.1-0.9). Moreover, thermodynamic properties of Δ H ≠, Δ S ≠, Δ G ≠ were 77.96 kJ mol-1, -90.71 J mol-1 K-1, 119.41 kJ mol-1.

  5. Thermal decomposition and non-isothermal decomposition kinetics of carbamazepine

    Science.gov (United States)

    Qi, Zhen-li; Zhang, Duan-feng; Chen, Fei-xiong; Miao, Jun-yan; Ren, Bao-zeng

    2014-12-01

    The thermal stability and kinetics of isothermal decomposition of carbamazepine were studied under isothermal conditions by thermogravimetry (TGA) and differential scanning calorimetry (DSC) at three heating rates. Particularly, transformation of crystal forms occurs at 153.75°C. The activation energy of this thermal decomposition process was calculated from the analysis of TG curves by Flynn-Wall-Ozawa, Doyle, distributed activation energy model, Šatava-Šesták and Kissinger methods. There were two different stages of thermal decomposition process. For the first stage, E and log A [s-1] were determined to be 42.51 kJ mol-1 and 3.45, respectively. In the second stage, E and log A [s-1] were 47.75 kJ mol-1 and 3.80. The mechanism of thermal decomposition was Avrami-Erofeev (the reaction order, n = 1/3), with integral form G(α) = [-ln(1 - α)]1/3 (α = ˜0.1-0.8) in the first stage and Avrami-Erofeev (the reaction order, n = 1) with integral form G(α) = -ln(1 - α) (α = ˜0.9-0.99) in the second stage. Moreover, Δ H ≠, Δ S ≠, Δ G ≠ values were 37.84 kJ mol-1, -192.41 J mol-1 K-1, 146.32 kJ mol-1 and 42.68 kJ mol-1, -186.41 J mol-1 K-1, 156.26 kJ mol-1 for the first and second stage, respectively.

  6. Abareshi Maryam Non-isothermal crystallization kinetics of ...

    Indian Academy of Sciences (India)

    Administrator

    497. Baniani D Dehghan. A study on role of nano sized SiO2 on deformation mecha- nism of vinylester. 1677 .... Synthesis and photoluminescence property of silicon carbide nanowires thin film by HF-PECVD system ..... posite for hardness enhancement of glass ionomer cement. (GIC). 213. Rai Renu see Lawrence Mathias ...

  7. Entropy Production in Chemical Reactors

    Science.gov (United States)

    Kingston, Diego; Razzitte, Adrián C.

    2017-06-01

    We have analyzed entropy production in chemically reacting systems and extended previous results to the two limiting cases of ideal reactors, namely continuous stirred tank reactor (CSTR) and plug flow reactor (PFR). We have found upper and lower bounds for the entropy production in isothermal systems and given expressions for non-isothermal operation and analyzed the influence of pressure and temperature in entropy generation minimization in reactors with a fixed volume and production. We also give a graphical picture of entropy production in chemical reactions subject to constant volume, which allows us to easily assess different options. We show that by dividing a reactor into two smaller ones, operating at different temperatures, the entropy production is lowered, going as near as 48 % less in the case of a CSTR and PFR in series, and reaching 58 % with two CSTR. Finally, we study the optimal pressure and temperature for a single isothermal PFR, taking into account the irreversibility introduced by a compressor and a heat exchanger, decreasing the entropy generation by as much as 30 %.

  8. The influence of included minerals on the reactivity of chars prepared at low temperature in DFT

    Energy Technology Data Exchange (ETDEWEB)

    Hong Zhang; Jiaxing Fan; Wenxiu Pu; Ming Sun [China University of Mining and Technology, Xuzhou (China). School of Chemical Engineering

    2007-07-01

    In this paper four Chinese pulverized coals of different rank were separated into various density fractions with float-sink procedure. Two fractions of each coal, one for organic-rich, the other for organic with included mineral, were devolatized in a drop tube furnace at a temperature of 90{sup o}C and 1 vol% oxygen atmosphere. The reactivities of chars were measured non-isothermally in a thermal gravimetric analyser (TGA) in the range of 20-90{sup o}C. The results indicate that the role of included minerals in chars change with the rank of coals. For anthracites, minerals play catalytic effect during the combustion process, while for bituminous coals the opposite. Gas absorption studies with N{sub 2} at 77K indicate that their reactivity difference correlates with pore structure change. After a discussion about various factors affecting the formation process of chars, it was concluded that included minerals dilute and adsorb the liquid phase during pyrolysis. For anthracites, there is no or little liquid phase, minerals act as pore producer in coal matrix. For bituminous coals, the same effect of minerals cause the escape of the swelling gas inside the particles, leading to the formation of char cenospheres with less void and lower reactivity. 10 refs., 4 figs., 3 tabs.

  9. 40 CFR 721.9717 - Azo monochloro triazine reactive dye.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Azo monochloro triazine reactive dye... Substances § 721.9717 Azo monochloro triazine reactive dye. (a) Chemical substance and significant new uses... reactive dye (PMN P-96-238) is subject to reporting under this section for the significant new uses...

  10. Reactive sites influence in PMMA oligomers reactivity: a DFT study

    Science.gov (United States)

    Paz, C. V.; Vásquez, S. R.; Flores, N.; García, L.; Rico, J. L.

    2018-01-01

    In this work, we present a theoretical study of methyl methacrylate (MMA) living anionic polymerization. The study was addressed to understanding two important experimental observations made for Michael Szwarc in 1956. The unexpected effect of reactive sites concentration in the propagation rate, and the self-killer behavior of MMA (deactivating of living anionic polymerization). The theoretical calculations were performed by density functional theory (DFT) to obtain the frontier molecular orbitals values. These values were used to calculate and analyze the chemical interaction descriptors in DFT-Koopmans’ theorem. As a result, it was observed that the longest chain-length species (related with low concentration of reactive sites) exhibit the highest reactivity (behavior associated with the increase of the propagation rate). The improvement in this reactivity was attributed to the crosslinking produced in the polymethyl methacrylate chains. Meanwhile, the self-killer behavior was associated with the intermolecular forces present in the reactive sites. This behavior was associated to an obstruction in solvation, since the active sites remained active through all propagation species. The theoretical results were in good agreement with the Szwarc experiments.

  11. Modelling of the reactive transport for rock salt-brine in geological repository systems based on improved thermodynamic database (Invited)

    Science.gov (United States)

    Müller, W.; Alkan, H.; Xie, M.; Moog, H.; Sonnenthal, E. L.

    2009-12-01

    The release and migration of toxic contaminants from the disposed wastes is one of the main issues in long-term safety assessment of geological repositories. In the engineered and geological barriers around the nuclear waste emplacements chemical interactions between the components of the system may affect the isolation properties considerably. As the chemical issues change the transport properties in the near and far field of a nuclear repository, modelling of the transport should also take the chemistry into account. The reactive transport modelling consists of two main components: a code that combines the possible chemical reactions with thermo-hydrogeological processes interactively and a thermodynamic databank supporting the required parameters for the calculation of the chemical reactions. In the last decade many thermo-hydrogeological codes were upgraded to include the modelling of the chemical processes. TOUGHREACT is one of these codes. This is an extension of the well known simulator TOUGH2 for modelling geoprocesses. The code is developed by LBNL (Lawrence Berkeley National Laboratory, Univ. of California) for the simulation of the multi-phase transport of gas and liquid in porous media including heat transfer. After the release of its first version in 1998, this code has been applied and improved many times in conjunction with considerations for nuclear waste emplacement. A recent version has been extended to calculate ion activities in concentrated salt solutions applying the Pitzer model. In TOUGHREACT, the incorporated equation of state module ECO2N is applied as the EOS module for non-isothermal multiphase flow in a fluid system of H2O-NaCl-CO2. The partitioning of H2O and CO2 between liquid and gas phases is modelled as a function of temperature, pressure, and salinity. This module is applicable for waste repositories being expected to generate or having originally CO2 in the fluid system. The enhanced TOUGHREACT uses an EQ3/6-formatted database

  12. Reactive polymer fused deposition manufacturing

    Science.gov (United States)

    Kunc, Vlastimil; Rios, Orlando; Love, Lonnie J.; Duty, Chad E.; Johs, Alexander

    2017-05-16

    Methods and compositions for additive manufacturing that include reactive or thermosetting polymers, such as urethanes and epoxies. The polymers are melted, partially cross-linked prior to the depositing, deposited to form a component object, solidified, and fully cross-linked. These polymers form networks of chemical bonds that span the deposited layers. Application of a directional electromagnetic field can be applied to aromatic polymers after deposition to align the polymers for improved bonding between the deposited layers.

  13. A new approach for the immobilization of poly(acrylic) acid as a chemically reactive cross-linker on the surface of poly(lactic) acid-based biomaterials.

    Science.gov (United States)

    Stankevich, Ksenia S; Danilenko, Nadezhda V; Gadirov, Ruslan M; Goreninskii, Semen I; Tverdokhlebov, Sergei I; Filimonov, Victor D

    2017-02-01

    A new approach for the immobilization of poly(acrylic) acid (PAA) as a chemically reactive cross-linker on the surface of poly(lactic) acid-based (PLA) biomaterials is described. The proposed technique includes non-covalent attachment of a PAA layer to the surface of PLA-based biomaterial via biomaterial surface treatment with solvent/non-solvent mixture followed by the entrapment of PAA from its solution. Surface morphology and wettability of the obtained PLA-PAA composite materials were investigated by AFM and the sitting drop method respectively. The amount of the carboxyl groups on the composites surface was determined by using the fluorescent compounds (2-(5-aminobenzo[d]oxazol-2-yl)phenol (ABO) and its acyl derivative N-(2-(2-hydroxyphenyl)benzo[d]oxazol-5-yl)acetamide (AcABO)). It was shown that it is possible to obtain PLA-PAA composites with various surface relief and tunable wettability (57°, 62° and 66°). The capacity of the created PAA layer could be varied from 1.5nmol/cm(2) to 0.1μmol/cm(2) depending on the modification conditions. Additionally, using bovine serum albumin (BSA) it was demonstrated that such composites could be modified with proteins with high binding density (around 0.18nmol/cm(2)). Obtained fluoro-labeled PLA-PAA materials, as well as PLA-PAA composites themselves, are valuable since they can be used for biodegradable polymer implants tracking in living systems and as drug delivery systems. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Mixing, entropy and reactive solute transport

    Science.gov (United States)

    Chiogna, Gabriele; Hochstetler, David L.; Bellin, Alberto; Kitanidis, Peter K.; Rolle, Massimo

    2012-10-01

    Mixing processes significantly affect reactive solute transport in fluids. For example, contaminant degradation in environmental aquatic systems can be limited either by the availability of one or more reactants, brought into contact by physical mixing, or by the kinetics of the (bio)chemical transformations. Appropriate metrics are needed to accurately quantify the interplay between mixing and reactive processes. The exponential of the Shannon entropy of the concentration probability distribution has been proposed and applied to quantify the dilution of conservative solutes either in a given volume (dilution index) or in a given water flux (flux-related dilution index). In this work we derive the transport equation for the entropy of a reactive solute. Adopting a flux-related framework, we show that the degree of uniformity of the solute mass flux distribution for a reactive species and its rate of change are informative measures of physical and (bio)chemical processes and their complex interaction.

  15. Reactive Kripke semantics

    CERN Document Server

    Gabbay, Dov M

    2013-01-01

    This text offers an extension to the traditional Kripke semantics for non-classical logics by adding the notion of reactivity. Reactive Kripke models change their accessibility relation as we progress in the evaluation process of formulas in the model. This feature makes the reactive Kripke semantics strictly stronger and more applicable than the traditional one. Here we investigate the properties and axiomatisations of this new and most effective semantics, and we offer a wide landscape of applications of the idea of reactivity. Applied topics include reactive automata, reactive grammars, rea

  16. Numerical simulation of reactive processes in an experiment with partially saturated bentonite.

    Science.gov (United States)

    Xie, Mingliang; Bauer, Sebastian; Kolditz, Olaf; Nowak, Thomas; Shao, Hua

    2006-02-01

    Bentonites are preferred materials for use as engineered barriers for high-level nuclear waste repositories. Simulation of geochemical processes in bentonite is therefore important for long-term safety assessment of those repositories. In this work, the porewater chemistry of a bentonite sample subject to simultaneous heating and hydration, as studied by Cuevas et al. [Cuevas, J., Villar, M., Fernández, A., Gómez, P., Martín, P., 1997. Porewaters extracted from compacted bentonite subjected to simultaneous heating and hydration. Applied Geochemistry 12, 473-481.], was assessed with a non-isothermal reactive transport model by coupling the geochemical software PHREEQC2 with the object-oriented FEM simulator GeoSys/RockFlow. Reactive transport modelling includes heat transport, two-phase flow, multicomponent transport and geochemical reactions in the liquid phase, i.e. ion exchange, mineral dissolution/precipitation and equilibrium reactions. Simulations show that the easily soluble minerals in bentonite determine the porewater chemistry. Temperature affects both two-phase flow and geochemical reactions. Porosity change due to dissolution/precipitation is low during the experiment. However, changes of the effective porosity caused by bentonite swelling can be very large. The simulated results agree well with the experimental data.

  17. Numerical simulation of reactive processes in an experiment with partially saturated bentonite

    Science.gov (United States)

    Xie, Mingliang; Bauer, Sebastian; Kolditz, Olaf; Nowak, Thomas; Shao, Hua

    2006-02-01

    Bentonites are preferred materials for use as engineered barriers for high-level nuclear waste repositories. Simulation of geochemical processes in bentonite is therefore important for long-term safety assessment of those repositories. In this work, the porewater chemistry of a bentonite sample subject to simultaneous heating and hydration, as studied by Cuevas et al. [Cuevas, J., Villar, M., Fernández, A., Gómez, P., Martín, P., 1997. Porewaters extracted from compacted bentonite subjected to simultaneous heating and hydration. Applied Geochemistry 12, 473-481.], was assessed with a non-isothermal reactive transport model by coupling the geochemical software PHREEQC2 with the object-oriented FEM simulator GeoSys/RockFlow. Reactive transport modelling includes heat transport, two-phase flow, multicomponent transport and geochemical reactions in the liquid phase, i.e. ion exchange, mineral dissolution/precipitation and equilibrium reactions. Simulations show that the easily soluble minerals in bentonite determine the porewater chemistry. Temperature affects both two-phase flow and geochemical reactions. Porosity change due to dissolution/precipitation is low during the experiment. However, changes of the effective porosity caused by bentonite swelling can be very large. The simulated results agree well with the experimental data.

  18. Reactive dispersive contaminant transport in coastal aquifers: Numerical simulation of a reactive Henry problem

    KAUST Repository

    Nick, H.M.

    2013-02-01

    The reactive mixing between seawater and terrestrial water in coastal aquifers influences the water quality of submarine groundwater discharge. While these waters come into contact at the seawater groundwater interface by density driven flow, their chemical components dilute and react through dispersion. A larger interface and wider mixing zone may provide favorable conditions for the natural attenuation of contaminant plumes. It has been claimed that the extent of this mixing is controlled by both, porous media properties and flow conditions. In this study, the interplay between dispersion and reactive processes in coastal aquifers is investigated by means of numerical experiments. Particularly, the impact of dispersion coefficients, the velocity field induced by density driven flow and chemical component reactivities on reactive transport in such aquifers is studied. To do this, a hybrid finite-element finite-volume method and a reactive simulator are coupled, and model accuracy and applicability are assessed. A simple redox reaction is considered to describe the degradation of a contaminant which requires mixing of the contaminated groundwater and the seawater containing the terminal electron acceptor. The resulting degradation is observed for different scenarios considering different magnitudes of dispersion and chemical reactivity. Three reactive transport regimes are found: reaction controlled, reaction-dispersion controlled and dispersion controlled. Computational results suggest that the chemical components\\' reactivity as well as dispersion coefficients play a significant role on controlling reactive mixing zones and extent of contaminant removal in coastal aquifers. Further, our results confirm that the dilution index is a better alternative to the second central spatial moment of a plume to describe the mixing of reactive solutes in coastal aquifers. © 2012 Elsevier B.V.

  19. Reactive multiphase flow simulation workshop summary

    Energy Technology Data Exchange (ETDEWEB)

    VanderHeyden, W.B.

    1995-09-01

    A workshop on computer simulation of reactive multiphase flow was held on May 18 and 19, 1995 in the Computational Testbed for Industry at Los Alamos National Laboratory (LANL), Los Alamos, New Mexico. Approximately 35 to 40 people attended the workshop. This included 21 participants from 12 companies representing the petroleum, chemical, environmental and consumer products industries, two representatives from the DOE Office of Industrial Technologies and several from Los Alamos. The dialog at the meeting suggested that reactive multiphase flow simulation represents an excellent candidate for government/industry/academia collaborative research. A white paper on a potential consortium for reactive multiphase flow with input from workshop participants will be issued separately.

  20. Modeling and simulation of reactive flows

    CERN Document Server

    Bortoli, De AL; Pereira, Felipe

    2015-01-01

    Modelling and Simulation of Reactive Flows presents information on modeling and how to numerically solve reactive flows. The book offers a distinctive approach that combines diffusion flames and geochemical flow problems, providing users with a comprehensive resource that bridges the gap for scientists, engineers, and the industry. Specifically, the book looks at the basic concepts related to reaction rates, chemical kinetics, and the development of reduced kinetic mechanisms. It considers the most common methods used in practical situations, along with equations for reactive flows, and va

  1. Monadic Functional Reactive Programming

    NARCIS (Netherlands)

    A.J. van der Ploeg (Atze); C Shan

    2013-01-01

    htmlabstractFunctional Reactive Programming (FRP) is a way to program reactive systems in functional style, eliminating many of the problems that arise from imperative techniques. In this paper, we present an alternative FRP formulation that is based on the notion of a reactive computation: a

  2. Towards a quantitative understanding of total OH reactivity: A review

    Science.gov (United States)

    Yang, Yudong; Shao, Min; Wang, Xuemei; Nölscher, Anke C.; Kessel, Stephan; Guenther, Alex; Williams, Jonathan

    2016-06-01

    Over the past fifty years, considerable efforts have been devoted to measuring the concentration and chemical speciation of volatile organic compounds (VOCs) in ambient air and emissions. Recently, it has become possible to directly determine the overall effect of atmospheric trace gases on the oxidant hydroxyl radicals (OH), by measuring OH reactivity (OH loss frequency). Quantifying total OH reactivity is one way to characterize the roles of VOCs in formation of ground-level ozone and secondary organic aerosols (SOA). Approaches for measuring total OH reactivity in both emissions and ambient air have been progressing and have been applied in a wide range of studies. Here we evaluate the main techniques used to measure OH reactivity, including two methods directly measuring OH decay and one comparative reactivity method (CRM), and summarize the existing experimental and modeling studies. Total OH reactivity varies significantly on spatial, diurnal, seasonal and vertical bases. Comparison with individually detected OH sinks often reveals a significant missing reactivity, ranging from 20% to over 80% in some environments. Missing reactivity has also been determined in most source emission studies. These source measurements, as well as numerical models, have indicated that both undetected primary emissions and unmeasured secondary products could contribute to missing reactivity. A quantitative understanding of total OH reactivity of various sources and ambient environments will enhance our understanding of the suite of compounds found in emissions as well as chemical processes, and will also provide an opportunity for the improvement of atmospheric chemical mechanisms.

  3. First OH reactivity measurements in Harvard Forest

    Science.gov (United States)

    Herdlinger-Blatt, I. S.; Martin, S. T.; Hansel, A.; McKinney, K. A.

    2013-12-01

    , Rapid Commun. Mass Spectrom., 12, 871-875, (1998). W. Lindinger, A. Hansel, and A. Jordan: Proton-transfer-reaction mass spectrometry (PTR-MS): on-line monitoring of volatile organic compounds at pptv levels. Chemical Society Reviews , 27, 1998. S. Lou, F. Holland, F. Rohrer, K. Lu, B. Bohn, T. Brauers, C. C. Chang, H. Fuchs, R. Häseler, K. Kita, Y. Kondo, X. Li, M. Shao, L. Zeng, A. Wahner, Y. Zhang, W. Wang, and A. Hofzumahaus, Atmospheric OH reactivities in the Pearl River Delta - China in summer 2006: measurement and model results, Atmos. Chem. Phys., 10, 11243-11260, (2010). V. Sinha, J. Williams, J.N. Crowley, and J. Lelieveld., The Comparaptive Reactivity Methode - a new tool to measure total OH Reactivity in ambient air, Atmos. Env., 38, 2511-2522, (2008).

  4. Limiting profiles in reactive solute transport

    NARCIS (Netherlands)

    C.J. van Duijn (Hans); R.E. Grundy; C.N. Dawson

    1996-01-01

    textabstractAbstract: In this paper we consider the large time structure of reactive solute plumes in two dimensional, macroscopically homogeneous, flow domains. The reactions between the dissolved chemicals and the porous matrix are equilibrium adsorption reactions, given by an isotherm of

  5. Relationship between global indices of reactivity, electrodonating ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 5. Relationship between global indices of reactivity, electrodonating and electroaccepting powers, and the hammet constant in isatoic anhydride derivatives. J S Durand-Niconoff L Cruz-Kuri M H Matus J Correa-Basurto J S Cruz-Sánchez F R Ramos- ...

  6. Reactive Programming in Java

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    Reactive Programming in gaining a lot of excitement. Many libraries, tools, and frameworks are beginning to make use of reactive libraries. Besides, applications dealing with big data or high frequency data can benefit from this programming paradigm. Come to this presentation to learn about what reactive programming is, what kind of problems it solves, how it solves them. We will take an example oriented approach to learning the programming model and the abstraction.

  7. Production and Consumption of Reactive Oxygen Species by Fullerenes

    Science.gov (United States)

    Reactive oxygen species (ROS) are one of the most important intermediates in chemical, photochemical, and biological processes. To understand the environmental exposure and toxicity of fullerenes better, the production and consumption of ROS (singlet oxygen, superoxide, hydrogen ...

  8. Effect of pyrolysis conditions on reactivity of clean coals produced from poor quality coals

    Energy Technology Data Exchange (ETDEWEB)

    Skodras, G.; Natas, P.; Basinas, P.; Sakellaropoulos, G.P. [Institute for Solid Fuels Technology and Applications, Ptolemais (Greece)

    2005-07-01

    A preventive fuels pre-treatment technique, based on low temperature carbonization has been tested. Clean coals were produced from two Greek poor quality coals (Ptolemais and Megalopolis) and an Australian coal sample, in a lab-scale fixed bed reactor, under helium atmosphere and ambient pressure. The effects of carbonisation temperature (200-900{sup o}C) and residence time (5-120 min) on the properties of the obtained chars were investigated. Special attention was paid to the polluting compounds (S,N,Hg and Cl) removal. To account for possible mineral matter effects, mainly on sulphur removal, tests were also performed with demineralised coal. The reactivity under combustion conditions of the chars produced was also investigated. It was observed that low temperature carbonisation could contribute to clean coal production by effectively removing the major part of the existing polluting compounds in the coals. Thus, depending on coal type, nitrogen, mercury and chlorine conversion continuously increase with temperature, while sulphur removal seems to reach a plateau above 500-600{sup o}C. Furthermore, the prolongation of carbonisation time above 20 min does not affect the elements conversion of the pollutants. Therefore carbonization at 500-600{sup o}C for about 20 min could be considered sufficient for clean coal production for poor quality coals. The reactivity of the prepared clean coals was evaluated by performing non-isothermal combustion tests in a TA Q600 thermobalance at ambient pressure and 20{sup o}C/min heating rate. At increased pyrolysis temperatures higher initial combustion temperatures were observed, due to the volatile reduction in char production stage. Mineral matter removal leads to increased char reactivity by increasing both the initial combustion temperature and the combustion rate. 13 refs., 18 figs., 1 tab.

  9. Termination of nanoscale zero-valent iron reactivity by addition of bromate as a reducing reactivity competitor

    DEFF Research Database (Denmark)

    Mines, Paul D.; Kaarsholm, Kamilla Marie Speht; Droumpali, Ariadni

    2017-01-01

    an appropriate way to terminate the reactivity of any nZVI-containing material for a practical experimental procedure. In this study, bimetallic Ni/Fe-NPs were prepared to enhance overall reduction kinetics owing to the catalytic reactivity of nickel on the surface of nZVI. We have tested several chemical...

  10. From Chemical Forces to Chemical Rates: A Historical/Philosophical Foundation for the Teaching of Chemical Equilibrium

    Science.gov (United States)

    Quilez, Juan

    2009-01-01

    With this paper, our main aim is to contribute to the realisation of the chemical reactivity concept, tracing the historical evolution of the concept of chemical affinity that eventually supported the concept of chemical equilibrium. We will concentrate on searching for the theoretical grounds of three key chemical equilibrium ideas: "incomplete…

  11. Design and synthesis of reactive separation systems

    Energy Technology Data Exchange (ETDEWEB)

    Doherty, M.F.

    1992-01-01

    During the last decade there has been a rapid upturn in interest in reactive distillation. The chemical process industry recognizes the favorable economics of carrying out reaction simultaneously with distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for reactive distillation systems have only recently begun to emerge. In this report we survey the available design techniques and point out the contributions made by our group at the University of Massachusetts.

  12. Molecular reactivity dynamics in a confined environment.

    Science.gov (United States)

    Khatua, Munmun; Chattaraj, Pratim Kumar

    2013-04-21

    Time evolution of various reactivity parameters viz. hardness, electrophilicity, chemical potential, polarizability, etc. in a confined environment has been studied through quantum fluid density functional theory formalism during time dependent processes such as proton-molecule collisions and molecule-field interaction. A Dirichlet type boundary condition has been incorporated to confine the systems. Responses in the reactivity parameters of the diatomic molecules, in the dynamical context, in ground state as well as in excited state, have been reported. Harmonic spectra are generated in the cases of the external laser field interacting with H2 and N2 molecules.

  13. Two modelling approaches to water-quality simulation in a flooded iron-ore mine (Saizerais, Lorraine, France): a semi-distributed chemical reactor model and a physically based distributed reactive transport pipe network model.

    Science.gov (United States)

    Hamm, V; Collon-Drouaillet, P; Fabriol, R

    2008-02-19

    The flooding of abandoned mines in the Lorraine Iron Basin (LIB) over the past 25 years has degraded the quality of the groundwater tapped for drinking water. High concentrations of dissolved sulphate have made the water unsuitable for human consumption. This problematic issue has led to the development of numerical tools to support water-resource management in mining contexts. Here we examine two modelling approaches using different numerical tools that we tested on the Saizerais flooded iron-ore mine (Lorraine, France). A first approach considers the Saizerais Mine as a network of two chemical reactors (NCR). The second approach is based on a physically distributed pipe network model (PNM) built with EPANET 2 software. This approach considers the mine as a network of pipes defined by their geometric and chemical parameters. Each reactor in the NCR model includes a detailed chemical model built to simulate quality evolution in the flooded mine water. However, in order to obtain a robust PNM, we simplified the detailed chemical model into a specific sulphate dissolution-precipitation model that is included as sulphate source/sink in both a NCR model and a pipe network model. Both the NCR model and the PNM, based on different numerical techniques, give good post-calibration agreement between the simulated and measured sulphate concentrations in the drinking-water well and overflow drift. The NCR model incorporating the detailed chemical model is useful when a detailed chemical behaviour at the overflow is needed. The PNM incorporating the simplified sulphate dissolution-precipitation model provides better information of the physics controlling the effect of flow and low flow zones, and the time of solid sulphate removal whereas the NCR model will underestimate clean-up time due to the complete mixing assumption. In conclusion, the detailed NCR model will give a first assessment of chemical processes at overflow, and in a second time, the PNM model will provide more

  14. Reactive Turing machines

    National Research Council Canada - National Science Library

    Baeten, Jos; Luttik, Bas; Tilburg, P.J.A

    2013-01-01

    textabstractWe propose reactive Turing machines (RTMs), extending classical Turing machines with a process-theoretical notion of interaction, and use it to define a notion of executable transition system...

  15. What Is Reactive Arthritis?

    Science.gov (United States)

    ... Information Artritis reactiva: Esenciales: hojas informativas de fácil lectura View/Download/Order Publications Reactive Arthritis, Easy-to- ... Media Moderation Policy FOIA Privacy Statement Accessibility Disclaimer Digital Strategy Open Source Data Public Data Listing NIH... ...

  16. Reactive Attachment Disorder

    Science.gov (United States)

    ... treatment plan Reactive Attachment Disorder and Disinhibited Social Engagement Disorder are serious clinical conditions. However, close and ongoing ... you find Facts for Families © helpful and would like to make good mental health a reality, consider donating to the ...

  17. Taskable Reactive Agent Communities

    National Research Council Canada - National Science Library

    Myers, Karen

    2002-01-01

    The focus of Taskable Reactive Agent Communities (TRAC) project was to develop mixed-initiative technology to enable humans to supervise and manage teams of agents as they perform tasks in dynamic environments...

  18. Reactive sputter deposition

    CERN Document Server

    Mahieu, Stijn

    2008-01-01

    In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.

  19. Role of reactive metabolites in drug-induced hepatotoxicity.

    Science.gov (United States)

    Srivastava, A; Maggs, J L; Antoine, D J; Williams, D P; Smith, D A; Park, B K

    2010-01-01

    Drugs are generally converted to biologically inactive forms and eliminated from the body, principally by hepatic metabolism. However, certain drugs undergo biotransformation to metabolites that can interfere with cellular functions through their intrinsic chemical reactivity towards glutathione, leading to thiol depletion, and functionally critical macromolecules, resulting in reversible modification, irreversible adduct formation, and irreversible loss of activity. There is now a great deal of evidence which shows that reactive metabolites are formed from drugs known to cause hepatotoxicity, such as acetaminophen, tamoxifen, isoniazid, and amodiaquine. The main theme of this article is to review the evidence for chemically reactive metabolites being initiating factors for the multiple downstream biological events culminating in toxicity. The major objectives are to understand those idiosyncratic hepatotoxicities thought to be caused by chemically reactive metabolites and to define the role of toxic metabolites.

  20. Reactivity of polychlorinated biphenyls in nucleophilic and electrophilic substitutions

    Energy Technology Data Exchange (ETDEWEB)

    Gorbunova, Tatyana I., E-mail: gorbunova@ios.uran.ru [I. Ya. Postovskii Institute of Organic Synthesis, Ural Branch, Russian Academy of Sciences, Kovalevskoy St., 22, Ekaterinburg 620990 (Russian Federation); Subbotina, Julia O. [Ural Federal University named after the first President of Russia B.N. Yeltsin, Mira St., 19, Ekaterinburg 620002 (Russian Federation); Saloutin, Viktor I.; Chupakhin, Oleg N. [I. Ya. Postovskii Institute of Organic Synthesis, Ural Branch, Russian Academy of Sciences, Kovalevskoy St., 22, Ekaterinburg 620990 (Russian Federation)

    2014-08-15

    Graphical abstract: - Highlights: • Quantum chemical calculations were carried out for PCBs congeners. • Calculated descriptors were used to explain the PCBs reactivity in S{sub N} and S{sub E} substitutions. • Obtained data were used to estimate the PCBs reactivity in the S{sub N} reactions. • Calculated descriptors were insufficient to explain the PCBs reactivity in the S{sub E} reactions. • New neutralization methods of the large-capacity PCBs were discussed. - Abstract: To explain the chemical reactivity of polychlorinated biphenyls in nucleophilic (S{sub N}) and electrophilic (S{sub E}) substitutions, quantum chemical calculations were carried out at the B3LYP/6-31G(d) level of the Density Functional Theory in gas phase. Carbon atomic charges in biphenyl structure were calculated by the Atoms-in-Molecules method. Chemical hardness and global electrophilicity index parameters were determined for congeners. A comparison of calculated descriptors and experimental data for congener reactivity in the S{sub N} and S{sub E} reactions was made. It is shown that interactions in the S{sub N} mechanism are reactions of the hard acid–hard base type, these are the most effective in case of highly chlorinated substrates. To explain the congener reactivity in the S{sub E} reactions, correct descriptors were not established. The obtained results can be used to carry out chemical transformations of the polychlorinated biphenyls in order to prepare them for microbiological destruction or preservation.

  1. Effects of chemical composition and mean coordination number on glass transitions in Ge-Sb-Se glasses

    Science.gov (United States)

    Wei, Wen-Hou

    2017-12-01

    Glass transitions in the Ge-Sb-Se glasses were investigated by means of differential scanning calorimetry (DSC) under non-isothermal conditions. The glass transition temperature (Tg), activation energy of glass transition (Et), and fragility index as functions of the mean coordination number (MCN) and atomic percent of Ge were examined. The maximum value of Tg in each group of the glasses occurred at the chemically stoichiometric composition, suggesting a glass transition threshold. The Et and fragility index were calculated from the heating rate dependence of Tg. Both Et and fragility index show the minima at MCN = 2.4 which can be attributed to the structural phase transition of a covalently glassy network at MCN = 2.4. The analysis of the experimental results suggests that both the chemical composition and MCN have significant effects on the glass transitions in Ge-Sb-Se glasses.

  2. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. P K Chattaraj. Articles written in Journal of Chemical Sciences. Volume 115 Issue 3 June 2003 pp 195-218 Physical and Theoretical. Chemical reactivity of the compressed noble gas atoms and their reactivity dynamics during collisions with protons · P K Chattaraj B Maiti U ...

  3. Calculation of a double reactive azeotrope using stochastic optimization approaches

    Science.gov (United States)

    Mendes Platt, Gustavo; Pinheiro Domingos, Roberto; Oliveira de Andrade, Matheus

    2013-02-01

    An homogeneous reactive azeotrope is a thermodynamic coexistence condition of two phases under chemical and phase equilibrium, where compositions of both phases (in the Ung-Doherty sense) are equal. This kind of nonlinear phenomenon arises from real world situations and has applications in chemical and petrochemical industries. The modeling of reactive azeotrope calculation is represented by a nonlinear algebraic system with phase equilibrium, chemical equilibrium and azeotropy equations. This nonlinear system can exhibit more than one solution, corresponding to a double reactive azeotrope. The robust calculation of reactive azeotropes can be conducted by several approaches, such as interval-Newton/generalized bisection algorithms and hybrid stochastic-deterministic frameworks. In this paper, we investigate the numerical aspects of the calculation of reactive azeotropes using two metaheuristics: the Luus-Jaakola adaptive random search and the Firefly algorithm. Moreover, we present results for a system (with industrial interest) with more than one azeotrope, the system isobutene/methanol/methyl-tert-butyl-ether (MTBE). We present convergence patterns for both algorithms, illustrating - in a bidimensional subdomain - the identification of reactive azeotropes. A strategy for calculation of multiple roots in nonlinear systems is also applied. The results indicate that both algorithms are suitable and robust when applied to reactive azeotrope calculations for this "challenging" nonlinear system.

  4. Intercomparison 9711. pH, conductivity, alkalinity, nitrate + nitrite, chloride, sulfate, calcium, magnesium, sodium, potassium, total aluminium, reactive and non-labile aluminium, dissolved organic carbon, and chemical oxygen demand (ICP Waters report)

    OpenAIRE

    Hovind, H.

    1997-01-01

    47 laboratories in 22 countries participated in intercomparison 9711. One sample set for the determination of major ions, organic matter and aluminium fractions, were used. Based on the general target accuracy of + 20%, 78% of the results were acceptable. More than 80% of the result pairs were acceptable for chloride, sulfate, calcium, mangnesium, sodium, dissolved organic carbon and chemical oxygen demand. For pH only 43% of the result pairs were acceptable in relation to the extended target...

  5. Review of existing reactive transport software

    Energy Technology Data Exchange (ETDEWEB)

    Glassley, W., LLNL

    1998-02-03

    Simulations of thermal and hydrological evolution following the potential emplacement of a subterranean nuclear waste repository at Yucca Mountain, NV provide data that suggest the inevitability of dependent, simultaneous chemical evolution in this system. These chemical changes will modify significantly both the magnitude and structure of local porosity and permeability; hence, they will have a dynamic feedback effect on the evolving thermal and hydrological regime. Yet, despite this intimate interdependence of transport and chemical processes, a rigorous quantitative analysis of the post- emplacement environment that incorporates this critical feedback mechanism has not been completed to date. As an initial step in this direction, the present document outlines the fundamental chemical and transport processes that must be accounted for in such an analysis, and reviews the inventory of existing software that encodes these processed in explicitly coupled form. A companion report describes the prioritization of specific capabilities that are needed for modeling post-emplacement reactive transport at Yucca Mountain.

  6. Applications of the Conceptual Density Functional Theory Indices to Organic Chemistry Reactivity.

    Science.gov (United States)

    Domingo, Luis R; Ríos-Gutiérrez, Mar; Pérez, Patricia

    2016-06-09

    Theoretical reactivity indices based on the conceptual Density Functional Theory (DFT) have become a powerful tool for the semiquantitative study of organic reactivity. A large number of reactivity indices have been proposed in the literature. Herein, global quantities like the electronic chemical potential μ, the electrophilicity ω and the nucleophilicity N indices, and local condensed indices like the electrophilic P k + and nucleophilic P k - Parr functions, as the most relevant indices for the study of organic reactivity, are discussed.

  7. Molecular structure, heteronuclear resonance assisted hydrogen bond analysis, chemical reactivity and first hyperpolarizability of a novel ethyl-4-{[(2,4-dinitrophenyl)-hydrazono]-ethyl}-3,5-dimethyl-1H-pyrrole-2-carboxylate: a combined DFT and AIM approach.

    Science.gov (United States)

    Singh, R N; Kumar, Amit; Tiwari, R K; Rawat, Poonam; Baboo, Vikas; Verma, Divya

    2012-06-15

    A new ethyl-4-{[(2,4-dinitrophenyl)-hydrazono]-ethyl}-3,5-dimethyl-1H-pyrrole-2-carboxylate (EDPHEDPC) has been synthesized and characterized by FT-IR, (1)H NMR, UV-vis, DART-Mass spectroscopy and elemental analysis. Quantum chemical calculations have been performed by DFT level of theory using B3LYP functional and 6-31G(d,p) as basis set. The (1)H NMR chemical shifts are calculated using gauge including atomic orbitals (GIAO) approach in DMSO as solvent. The time dependent density functional theory (TD-DFT) is used to find the various electronic transitions and their nature within molecule. A combined theoretical and experimental wavenumber analysis confirms the existence of dimer. Topological parameters such as electron density (ρ(BCP)), Laplacian of electron density (nabla(2)ρ(BCP)), kinetic electron energy density (G(BCP)), potential electron density (V(BCP)) and the total electron energy density (H(BCP)) at bond critical points (BCP) have been analyzed by Bader's 'Atoms in molecules' AIM theory in detail. The intermolecular hydrogen bond energy of dimer is calculated as -12.51 kcal/mol using AIM calculations. AIM ellipticity analysis is carried out to confirm the presence of resonance assisted intra and intermolecular hydrogen bonds in dimer. The calculated thermodynamic parameters show that reaction is exothermic and non-spontaneous at room temperature. The local reactivity descriptors such as Fukui functions (f(k)(+), f(k)(-)), local softnesses (s(k)(-), s(k)(+)) and electrophilicity indices (ω(k)(+), ω(k)(-)) analyses are performed to determine the reactive sites within molecule. Nonlinear optical (NLO) behavior of title compound is investigated by the computed value of first hyperpolarizability (β(0)). Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Simulations of highly reactive fluids

    Energy Technology Data Exchange (ETDEWEB)

    Fried, L E; Manaa, M R; Reed, E J

    2005-07-21

    We report density functional molecular dynamics simulations to determine the early chemical events of hot (T = 3000 K) and dense (1.97 g/cm{sup 3}, V/V{sub 0} = 0.68) nitromethane (CH{sub 3}NO{sub 2}). The first step in the decomposition process is an intermolecular proton abstraction mechanism that leads to the formation of CH{sub 3}NO{sub 2}H and the aci ion H{sub 2}CNO{sub 2}{sup -}, in support of evidence from static high-pressure and shock experiments. An intramolecular hydrogen transfer that transforms nitromethane into the aci acid form, CH{sub 2}NO{sub 2}H, accompanies this event. This is the first confirmation of chemical reactivity with bond selectivity for an energetic material near the condition of fully reacted specimen. We also report the decomposition mechanism followed up to the formation of H{sub 2}O as the first stable product.

  9. Clojure reactive programming

    CERN Document Server

    Borges, Leonardo

    2015-01-01

    If you are a Clojure developer who is interested in using Reactive Programming to build asynchronous and concurrent applications, this book is for you. Knowledge of Clojure and Leiningen is required. Basic understanding of ClojureScript will be helpful for the web chapters, although it is not strictly necessary.

  10. Optimization of reactive mufflers

    Science.gov (United States)

    Komkin, A. I.

    2010-05-01

    A new approach to optimization of reactive mufflers, which is based on use of muffler prototype with nondimensional geometrical parameters and integral criterion of acoustic performance of mufflers, is proposed. Implementation of the approach using the example of chamber mufflers is considered.

  11. Spring 5 & reactive streams

    CERN Document Server

    CERN. Geneva; Clozel, Brian

    2017-01-01

    Spring is a framework widely used by the world-wide Java community, and it is also extensively used at CERN. The accelerator control system is constituted of 10 million lines of Java code, spread across more than 1000 projects (jars) developed by 160 software engineers. Around half of this (all server-side Java code) is based on the Spring framework. Warning: the speakers will assume that people attending the seminar are familiar with Java and Spring’s basic concepts. Spring 5.0 and Spring Boot 2.0 updates (45 min) This talk will cover the big ticket items in the 5.0 release of Spring (including Kotlin support, @Nullable and JDK9) and provide an update on Spring Boot 2.0, which is scheduled for the end of the year. Reactive Spring (1h) Spring Framework 5.0 has been released - and it now supports reactive applications in the Spring ecosystem. During this presentation, we'll talk about the reactive foundations of Spring Framework with the Reactor project and the reactive streams specification. We'll al...

  12. Reactive Turing machines

    NARCIS (Netherlands)

    J.C.M. Baeten (Jos); S.P. Luttik (Bas); P.J.A. van Tilburg

    2013-01-01

    textabstractWe propose reactive Turing machines (RTMs), extending classical Turing machines with a process-theoretical notion of interaction, and use it to define a notion of executable transition system. We show that every computable transition system with a bounded branching degree is simulated

  13. Hydroxyquinones: Synthesis and Reactivity

    Directory of Open Access Journals (Sweden)

    Spyros Spyroudis

    2000-12-01

    Full Text Available Quinones having hydroxy groups directly attached to the quinone ring constitute a very interesting class of quinoid compounds. A great number of hydroxyquinones are found in nature and the majority of them exhibit unique biological activity. Their syntheses and their main reactivity patterns are reviewed in this paper.

  14. Reactive transport modelling to infer changes in soil hydraulic properties induced by non-conventional water irrigation

    Science.gov (United States)

    Valdes-Abellan, Javier; Jiménez-Martínez, Joaquín; Candela, Lucila; Jacques, Diederik; Kohfahl, Claus; Tamoh, Karim

    2017-06-01

    The use of non-conventional water (e.g., treated wastewater, desalinated water) for different purposes is increasing in many water scarce regions of the world. Its use for irrigation may have potential drawbacks, because of mineral dissolution/precipitation processes, such as changes in soil physical and hydraulic properties (e.g., porosity, permeability), modifying infiltration and aquifer recharge processes or blocking root growth. Prediction of soil and groundwater impacts is essential for achieving sustainable agricultural practices. A numerical model to solve unsaturated water flow and non-isothermal multicomponent reactive transport has been modified implementing the spatio-temporal evolution of soil physical and hydraulic properties. A long-term process simulation (30 years) of agricultural irrigation with desalinated water, based on a calibrated/validated 1D numerical model in a semi-arid region, is presented. Different scenarios conditioning reactive transport (i.e., rainwater irrigation, lack of gypsum in the soil profile, and lower partial pressure of CO2 (pCO2)) have also been considered. Results show that although boundary conditions and mineral soil composition highly influence the reactive processes, dissolution/precipitation of carbonate species is triggered mainly by pCO2, closely related to plant roots. Calcite dissolution occurs in the root zone, precipitation takes place under it and at the soil surface, which will lead a root growth blockage and a direct soil evaporation decrease, respectively. For the studied soil, a gypsum dissolution up to 40 cm depth is expected at long-term, with a general increase of porosity and hydraulic conductivity.

  15. In silico prediction of acyl glucuronide reactivity

    Science.gov (United States)

    Potter, Tim; Lewis, Richard; Luker, Tim; Bonnert, Roger; Bernstein, Michael A.; Birkinshaw, Timothy N.; Thom, Stephen; Wenlock, Mark; Paine, Stuart

    2011-11-01

    Drugs and drug candidates containing a carboxylic acid moiety, including many widely used non-steroidal anti-inflammatory drugs (NSAIDs) are often metabolized to form acyl glucuronides (AGs). NSAIDs such as Ibuprofen are amongst the most widely used drugs on the market, whereas similar carboxylic acid drugs such as Suprofen have been withdrawn due to adverse events. Although the link between these AG metabolites and toxicity is not proven, there is circumstantial literature evidence to suggest that more reactive acyl glucuronides may, in some cases, present a greater risk of exhibiting toxic effects. We wished therefore to rank the reactivity of potential new carboxylate-containing drug candidates, and performed kinetic studies on synthetic acyl glucuronides to benchmark our key compounds. Driven by the desire to quickly rank the reactivity of compounds without the need for lengthy synthesis of the acyl glucuronide, a correlation was established between the degradation half-life of the acyl glucuronide and the half life for the hydrolysis of the more readily available methyl ester derivative. This finding enabled a considerable broadening of chemical property space to be investigated. The need for kinetic measurements was subsequently eliminated altogether by correlating the methyl ester hydrolysis half-life with the predicted 13C NMR chemical shift of the carbonyl carbon together with readily available steric descriptors in a PLS model. This completely in silico prediction of acyl glucuronide reactivity is applicable within the earliest stages of drug design with low cost and acceptable accuracy to guide intelligent molecular design. This reactivity data will be useful alongside the more complex additional pharmacokinetic exposure and distribution data that is generated later in the drug discovery process for assessing the overall toxicological risk of acidic drugs.

  16. Reactivity Network: Secondary Sources for Inorganic Reactivity Information.

    Science.gov (United States)

    Mellon, E. K.

    1989-01-01

    Provides an eclectic annotated bibliography of secondary sources for inorganic reactivity information of interest to reactivity network review authors and to anyone seeking information about simple inorganic reactions in order to develop experiments and demonstrations. Gives 119 sources. (MVL)

  17. Nucleophilic Addition of Reactive Dyes on Amidoximated Acrylic Fabrics

    Science.gov (United States)

    El-Shishtawy, Reda M.; El-Zawahry, Manal M.; Abdelghaffar, Fatma; Ahmed, Nahed S. E.

    2014-01-01

    Seven reactive dyes judiciously selected based on chemical structures and fixation mechanisms were applied at 2% owf of shade on amidoximated acrylic fabrics. Amidoximated acrylic fabric has been obtained by a viable amidoximation process. The dyeability of these fabrics was evaluated with respect to the dye exhaustion, fixation, and colour strength under different conditions of temperature and dyeing time. Nucleophilic addition type reactive dyes show higher colour data compared to nucleophilic substitution ones. FTIR studies further implicate the binding of reactive dyes on these fabrics. A tentative mechanism is proposed to rationalize the high fixation yield obtained using nucleophilic addition type reactive dyes. Also, the levelling and fastness properties were evaluated for all dyes used. Excellent to good fastness and levelling properties were obtained for all samples irrespective of the dye used. The result of investigation offers a new method for a viable reactive dyeing of amidoximated acrylic fabrics. PMID:25258720

  18. Nucleophilic addition of reactive dyes on amidoximated acrylic fabrics.

    Science.gov (United States)

    El-Shishtawy, Reda M; El-Zawahry, Manal M; Abdelghaffar, Fatma; Ahmed, Nahed S E

    2014-01-01

    Seven reactive dyes judiciously selected based on chemical structures and fixation mechanisms were applied at 2% of of shade on amidoximated acrylic fabrics. Amidoximated acrylic fabric has been obtained by a viable amidoximation process. The dyeability of these fabrics was evaluated with respect to the dye exhaustion, fixation, and colour strength under different conditions of temperature and dyeing time. Nucleophilic addition type reactive dyes show higher colour data compared to nucleophilic substitution ones. FTIR studies further implicate the binding of reactive dyes on these fabrics. A tentative mechanism is proposed to rationalize the high fixation yield obtained using nucleophilic addition type reactive dyes. Also, the levelling and fastness properties were evaluated for all dyes used. Excellent to good fastness and levelling properties were obtained for all samples irrespective of the dye used. The result of investigation offers a new method for a viable reactive dyeing of amidoximated acrylic fabrics.

  19. Treatment of dyeing wastewater including reactive dyes (Reactive ...

    African Journals Online (AJOL)

    2013-08-15

    Aug 15, 2013 ... Treatment of dyeing wastewater including reactive dyes. (Reactive Red RB, Reactive Black B, ... Keywords: Rhizopus arrhizus, wastewater treatment, decolourisation, textile dye. INTRODUCTION. Dyeing effluents ... as bacteria, yeasts, algae and fungi, are able to remove differ- ent classes of dyes (Fu and ...

  20. Treatment of dyeing wastewater including reactive dyes (Reactive ...

    African Journals Online (AJOL)

    The decolourisation potential of growing Rhizopus arrhizus fungal strain in liquid medium containing thiamine was investigated for the removal of anionic reactive dyes such as Reactive Red RB (RR), Reactive Black B (RBB) and Remazol Blue (RB) and a cationic basic dye Methylene Blue (MB). To determine the optimal ...

  1. Integrated Design and Control of Reactive and Non-Reactive Distillation Processes

    DEFF Research Database (Denmark)

    Mansouri, Seyed Soheil; Sales-Cruz, Mauricio; Huusom, Jakob Kjøbsted

    , an alternative approach is to tackle process design and controllability issues simultaneously, in the early stages of process design. This simultaneous synthesis approach provides optimal/near optimal operation and more efficient control of conventional (non-reactive binary distillation columns) (Hamid et al......., 2010) as well as complex chemical processes; for example, intensified processes such as reactive distillation (Mansouri et al., 2015). Most importantly, it identifies and eliminates potentially promising design alternatives that may have controllability problems later. To date, a number...... of methodologies have been proposed and applied on various problems to address the interactions between process design and control, and they range from optimization-based approaches to model-based methods (Sharifzadeh, 2013). In this work, integrated design and control of non-reactive distillation, ternary...

  2. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  3. Reactivity between PbSO 4 and CaCO 3 particles relevant to the modification of mineral particles and chemical forms of Pb in particles sampled at two remote sites during an Asian dust event

    Science.gov (United States)

    Ishizaka, Takahiro; Tohno, Susumu; Ma, Chang-Jin; Morikawa, Atsushi; Takaoka, Masaki; Nishiyama, Fumitaka; Yamamoto, Kouhei

    During the transboundary transport of anthropogenic heavy metals by mineral particles providing reaction sites, the divalent metal salt PbSO 4 can be converted to PbCO 3 in the presence of water. We carried out laboratory experiments to study the transformation process under various conditions by incorporating test particles comprising CaCO 3 of a particulate mineral component, PbSO 4, and NaCl. After the immersion of PbSO 4 particles in contact with CaCO 3 particles in a water droplet, the conversion of PbSO 4 into PbCO 3 was confirmed by the change in morphology of the original particles to stick or needle form; the percentages of the chemical forms relative to the total Pb were determined by X-ray absorption near edge structure (XANES) analysis. Approximately 60-80% of PbSO 4 was converted to PbCO 3 after 24 h. A small amount of stick particles was detected when NaCl particles attached to PbSO 4/CaCO 3 particles were exposed to air with a relative humidity (RH) of 80-90% for 24 h. XANES measurements of the samples revealed that the molar percentage of PbCO 3 relative to the total Pb content was 4%. Field experiments were also conducted to determine the chemical forms of the Pb particles during the Kosa (Asian dust storm) event. Samples were collected from two remote sites in Japan and Korea. The mass size distribution of Pb aerosols collected in Japan was bimodal with two peaks in the coarse mode; the enrichment factor of Pb suggested that its source was anthropogenic. Pb L3 edge XANES measurements of both samples indicated that they had similar shapes. These measurements also indicated that the major Pb components for the samples collected in Japan were PbO, PbSO 4 PbCl 2, and PbCO 3, with molar percentages of 44%, 30%, 21%, and 5%, respectively. No significant differences were found between the component ratios of the samples collected in Japan and Korea, suggesting that definite transformation did not occur during the transport of the Kosa particles from

  4. A finite-element simulation model for saturated-unsaturated, fluid-density-dependent ground-water flow with energy transport or chemically- reactive single-species solute transport

    Science.gov (United States)

    Voss, C.I.

    1984-01-01

    SUTRA (Saturated-Unsaturated Transport) is a computer program which can be used to simulate the movement of fluid and the transport of either energy or dissolved substances in a subsurface environment. The model employs a two-dimensional hybrid finite-element and integrated-finite-difference method to approximate the governing equations that describe the two interdependent processes that are simulated by SUTRA: (1) fluid density-dependent saturated or unsaturated groundwater flow, and either (2a) transport of a solute in the groundwater, in which the solute may be subject to: equilibrium adsorption on the porous matrix, and both first-order and zero-order production or decay, or, (2b) transport of thermal energy in the groundwater and solid matrix of the aquifer. SUTRA provides, as the primary calculated results, fluid pressures and either solute concentrations or temperatures, as they vary with time, everywhere in the simulated subsurface system. SUTRA may also be used to simulate simpler subsets of the above process. SUTRA may be employed for areal and cross-sectional models of saturated groundwater flow systems, and for cross-sectional models of unsaturated zone flow. Solute transport simulation using SUTRA may be used to simulate natural or man-induced chemical transport, solute sorption, production and decay. SUTRA may be used for simulation of variable density leachate movement, and for cross-sectional simulation of salt-water intrusion in aquifers at near-well or regional scales, with either dispersed or relatively sharp transition zones between fresh water and salt water. SUTRA energy transport simulation may be employed to model thermal regimes in aquifers, subsurface heat conduction, aquifer thermal energy storage systems, geothermal reservoirs, thermal pollution of aquifers, and natural hydrogeologic convection systems. (USGS)

  5. Cumulative Relative Reactivity: A Concept for Modeling Aquifer-Scale Reactive Transport

    Science.gov (United States)

    Loschko, M.; Cirpka, O. A.; Wöhling, T.; Rudolph, D. L.

    2016-12-01

    Quantitative understanding of pollutant fluxes from diffuse input and turnover of pollutants at catchment scale requires process-based numerical models that can explain observed time series of heads, fluxes, and concentrations. To deal with the high level of uncertainty a probabilistic framework is necessary. Due to the high computational effort, such evaluations cannot be done with a spatially explicit reactive-transport model. Conceptual simplifications are needed. The proposed approach is based on travel times and relative reactivity. The latter quantifies the intensity of the chemical reaction relative to a reference reaction rate and can be interpreted as the strength of electron-donor (or electron-acceptor) released by the matrix. In general, the relative reactivity is a spatially variable property reflecting the geology of the formation. In this approach, the paths of individual water parcels are tracked through the aquifer, the age of the water parcels is evaluated, and the relative reactivity is integrated along their trajectories. By switching from space-time discretization to cumulative relative reactivity, advective-reactive transport can be simulated by solving a single system of ordinary differential equations for each combination of concentrations in the inflow. In comparison to solving the advection-dispersion-reaction equation in a spatially explicit way, solving a limited number of ordinary differential equations is computationally significantly less costly. This permits the application of Monte-Carlo methods within a stochastic framework. The validity of the approach was tested in a two-dimensional test case, where the errors introduced by neglecting dispersive mixing were analyzed. The applicability of the approach is demonstrated in a synthetic case study of aerobic respiration and denitrification in the saturated zone using a three-dimensional steady-state groundwater flow model combined with the simplified reactive transport approach.

  6. Programming Reactive Extensions and LINQ

    CERN Document Server

    Liberty, Jesse

    2011-01-01

    Pro Reactive Extensions and LINQ is a deep dive into the next important technology for .NET developers: Reactive Extensions. This in-depth tutorial goes beyond what is available anywhere else to teach how to write WPF, Silverlight, and Windows Phone applications using the Reactive Extensions (Rx) to handle events and asynchronous method calls. Reactive programming allows you to turn those aspects of your code that are currently imperative into something much more event-driven and flexible. For this reason, it's sometimes referred to as LINQ for Events. Reactive programming hinges on the concep

  7. Prediction of the reduced glutathione (GSH) reactivity of dental methacrylate monomers using NMR spectra-Relationship between toxicity and GSH reactivity

    National Research Council Canada - National Science Library

    FUJISAWA, Seiichiro; KADOMA, Yoshinori

    2009-01-01

    ...). With this relationship, the objective of this study was to predict the GSH reactivity of dental methacrylate monomers, and hence their toxicity, using the 13C-NMR chemical shifts of β-carbon (δCβ...

  8. Antimycobacterial, antimicrobial activity, experimental (FT-IR, FT-Raman, NMR, UV-Vis, DSC) and DFT (transition state, chemical reactivity, NBO, NLO) studies on pyrrole-isonicotinyl hydrazine

    Science.gov (United States)

    Rawat, Poonam; Singh, R. N.; Ranjan, Alok; Ahmad, Sartaj; Saxena, Rajat

    2017-05-01

    As part of a study of pyrrole hydrazone, we have investigated quantum chemical calculations, molecular geometry, relative energy, vibrational properties and antimycobacterial/antimicrobial activity of pyrrole-2-carboxaldehyde isonicotinyl hydrazone (PCINH), by applying the density functional theory (DFT) and Hartree Fock (HF). Good reproduction of experimental values is obtained and with small percentage error in majority of the cases in comparison to theoretical result (DFT). The experimental FT-IR and Raman wavenumbers were compared with the respective theoretical values obtained from DFT calculations and found to agree well. In crystal structure studies the hydrated PCINH (syn-syn conformer) shows different conformation than from anhydrous form (syn-anti conformer). The rotational barrier between syn-syn and syn-anti conformers of PCINH is 12.7 kcal/mol in the gas phase. In this work, use of FT-IR, FT-Raman, 1H NMR, 13C NMR and UV-Vis spectroscopies has been made for full characterization of PCINH. A detailed interpretation of the vibrational spectrum was carried out with the aid of normal coordinate analysis using single scaling factor. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. The calculated nature of electronic transitions within molecule found to be π → π*. The electronic descriptors study indicates that PCINH can be used as robust synthon for synthesis of new heterocyclic compounds. The first static hyperpolarizability (β0) of PCINH is calculated as 33.89 × 10- 30 esu, (gas phase); 68.79 × 10- 30 (CHCl3), esu; 76.76 × 10- 30 esu (CH2Cl2), 85.16 × 10- 30 esu (DMSO). The solvent induced effects on the first static hyperpolarizability were studied and found to increase as dielectric constants of the solvents increases. Investigated molecule shows better NLO value than Para nitroaniline (PNA). The compound PCINH shows good antifungal and antibacterial activity against Aspergillus niger and gram

  9. Antimycobacterial, antimicrobial activity, experimental (FT-IR, FT-Raman, NMR, UV-Vis, DSC) and DFT (transition state, chemical reactivity, NBO, NLO) studies on pyrrole-isonicotinyl hydrazine.

    Science.gov (United States)

    Rawat, Poonam; Singh, R N; Ranjan, Alok; Ahmad, Sartaj; Saxena, Rajat

    2017-05-15

    As part of a study of pyrrole hydrazone, we have investigated quantum chemical calculations, molecular geometry, relative energy, vibrational properties and antimycobacterial/antimicrobial activity of pyrrole-2-carboxaldehyde isonicotinyl hydrazone (PCINH), by applying the density functional theory (DFT) and Hartree Fock (HF). Good reproduction of experimental values is obtained and with small percentage error in majority of the cases in comparison to theoretical result (DFT). The experimental FT-IR and Raman wavenumbers were compared with the respective theoretical values obtained from DFT calculations and found to agree well. In crystal structure studies the hydrated PCINH (syn-syn conformer) shows different conformation than from anhydrous form (syn-anti conformer). The rotational barrier between syn-syn and syn-anti conformers of PCINH is 12.7kcal/mol in the gas phase. In this work, use of FT-IR, FT-Raman, (1)H NMR, (13)C NMR and UV-Vis spectroscopies has been made for full characterization of PCINH. A detailed interpretation of the vibrational spectrum was carried out with the aid of normal coordinate analysis using single scaling factor. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. The calculated nature of electronic transitions within molecule found to be π→π*. The electronic descriptors study indicates that PCINH can be used as robust synthon for synthesis of new heterocyclic compounds. The first static hyperpolarizability (β0) of PCINH is calculated as 33.89×10(-30)esu, (gas phase); 68.79×10(-30) (CHCl3), esu; 76.76×10(-30)esu (CH2Cl2), 85.16×10(-30)esu (DMSO). The solvent induced effects on the first static hyperpolarizability were studied and found to increase as dielectric constants of the solvents increases. Investigated molecule shows better NLO value than Para nitroaniline (PNA). The compound PCINH shows good antifungal and antibacterial activity against Aspergillus niger and gram

  10. Applicability of DFT model in reactive distillation

    Science.gov (United States)

    Staszak, Maciej

    2017-11-01

    The density functional theory (DFT) applicability to reactive distillation is discussed. Brief modeling techniques description of distillation and rectification with chemical reaction is provided as a background for quantum method usage description. The equilibrium and nonequilibrium distillation models are described for that purpose. The DFT quantum theory is concisely described. The usage of DFT in the modeling of reactive distillation is described in two parts. One of the fundamental and very important component of distillation modeling is vapor-liquid equilibrium description for which the DFT quantum approach can be used. The representative DFT models, namely COSMO-RS (Conductor like Screening Model for Real Solvents), COSMOSPACE (COSMO Surface Pair Activity Coefficient) and COSMO-SAC (SAC - segment activity coefficient) approaches are described. The second part treats the way in which the chemical reaction is described by means of quantum DFT method. The intrinsic reaction coordinate (IRC) method is described which is used to find minimum energy path of substrates to products transition. The DFT is one of the methods which can be used for that purpose. The literature data examples are provided which proves that IRC method is applicable for chemical reaction kinetics description.

  11. A Universal Reactive Machine

    DEFF Research Database (Denmark)

    Andersen, Henrik Reif; Mørk, Simon; Sørensen, Morten U.

    1997-01-01

    Turing showed the existence of a model universal for the set of Turing machines in the sense that given an encoding of any Turing machine asinput the universal Turing machine simulates it. We introduce the concept of universality for reactive systems and construct a CCS processuniversal...... in the sense that, given an encoding of any CCS process, it behaves like this process up to weak bisimulation. This construction has arather non-constructive use of silent actions and we argue that this would be the case for any universal CCS process....

  12. Inactivation of Escherichia coli on blueberries using cold plasma with chemical augmentation inside a partial vacuum

    Science.gov (United States)

    Justification: The mechanism by which cold plasma inactivates pathogens is through the production of free reactive chemical species. Unfortunately, the most reactive chemical species have the shortest half-life. In a vacuum their half-life is believed to be prolonged. Additionally, these reactive sp...

  13. Gas-Phase Reactivity of Microsolvated Anions

    DEFF Research Database (Denmark)

    Thomsen, Ditte Linde

    the gas-phase α-effect. The experimental studies are performed by means of the flowing after glow selected ion flow tube technique, and these are supplemented by electronic structure calculations. The α-nucleophile employed is the microsolvated hydrogen peroxide anion whose reactivity is compared...... for the microsolvated α-nucleophile, and a significant α-effect was observed in this channel. Quantum chemical calculations reveal that the structure of the microsolvated hydrogen peroxide adduct is distinctly different from the structure of the microsolvated alkoxy nucleophiles, in that it involves transfer a proton...... cannot be expected to catalyze hydrogen abstraction reactions by the hydroxyl radical under atmospherically relevant conditions....

  14. Termination of nanoscale zero-valent iron reactivity by addition of bromate as a reducing reactivity competitor

    Science.gov (United States)

    Mines, Paul D.; Kaarsholm, Kamilla M. S.; Droumpali, Ariadni; Andersen, Henrik R.; Lee, Wontae; Hwang, Yuhoon

    2017-09-01

    Remediation of contaminated groundwater by nanoscale zero-valent iron (nZVI) is widely becoming a leading environmentally friendly solution throughout the globe. Since a wide range of various nZVI-containing materials have been developed for effective remediation, it is necessary to determine an appropriate way to terminate the reactivity of any nZVI-containing material for a practical experimental procedure. In this study, bimetallic Ni/Fe-NPs were prepared to enhance overall reduction kinetics owing to the catalytic reactivity of nickel on the surface of nZVI. We have tested several chemical strategies in order to terminate nZVI reactivity without altering the concentration of volatile compounds in the solution. The strategies include surface passivation in alkaline conditions by addition of carbonate, and consumption of nZVI by a reaction competitor. Four halogenated chemicals, trichloroethylene, 1,1,1-trichloroethane, atrazine, and 4-chlorophenol, were selected and tested as model groundwater contaminants. Addition of carbonate to passivate the nZVI surface was not effective for trichloroethylene. Nitrate and then bromate were applied to competitively consume nZVI by their faster reduction kinetics. Bromate proved to be more effective than nitrate, subsequently terminating nZVI reactivity for all four of the tested halogenated compounds. Furthermore, the suggested termination method using bromate was successfully applied to obtain trichloroethylene reduction kinetics. Herein, we report the simple and effective method to terminate the reactivity of nZVI by addition of a reducing reactivity competitor.

  15. Vibrational spectra, electronic absorption, nonlinear optical properties, evaluation of bonding, chemical reactivity and thermodynamic properties of ethyl 4-(1-(2-(hydrazinecarbonothioyl)hydrazono)ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate molecule by ab initio HF and density functional methods.

    Science.gov (United States)

    Singh, R N; Rawat, Poonam; Sahu, Sangeeta

    2015-01-25

    In this work, detailed vibrational spectral analysis of ethyl 4-(1-(2-(hydrazinecarbonothioyl)hydrazono)ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate (EHCHEDPC) molecule has been carried out using FT-IR spectroscopy and potential energy distribution (PED). Theoretical calculations were performed by ab initio RHF and density functional theory (DFT) method, using 6-31G(d,p) and 6-311+G(d,p) basis sets. The other carried outwork cover: structural, thermodynamic properties, electronic transitions, bonding, multiple interaction, chemical reactivity and hyperpolarizability analysis. The results of the calculation were applied to the simulated spectra of (EHCHEDPC), which show excellent agreement with observed spectra. The vibrational analysis shows red shift in both group, the proton donor (pyrrole N-H) and proton acceptor (C=O of ester) indicating the presence of intermolecular hydrogen bonding. Time dependent density functional theory (TD-DFT) has been used to find electronic excitations and their nature. The results of natural bond orbital (NBOs) analysis show the charges transfer and delocalization in various intra- and intermolecular interactions. The binding energy of intermolecular multiple interactions is calculated to be 12.54 kcal mol(-1) using QTAIM calculation. The electronic descriptors analyses reveal the investigated molecule used as precursor for heterocyclic derivatives synthesis. First hyperpolarizability (β0) has been computed to evaluate non-linear optical (NLO) response. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Fluctuating hydrodynamics of multi-species reactive mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Amit Kumar; Donev, Aleksandar [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012 (United States); Balakrishnan, Kaushik [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Garcia, Alejandro L. [Department of Physics and Astronomy, San Jose State University, 1 Washington Square, San Jose, California 95192 (United States); Bell, John B. [Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2015-06-14

    We formulate and study computationally the fluctuating compressible Navier-Stokes equations for reactive multi-species fluid mixtures. We contrast two different expressions for the covariance of the stochastic chemical production rate in the Langevin formulation of stochastic chemistry, and compare both of them to predictions of the chemical master equation for homogeneous well-mixed systems close to and far from thermodynamic equilibrium. We develop a numerical scheme for inhomogeneous reactive flows, based on our previous methods for non-reactive mixtures [Balakrishnan , Phys. Rev. E 89, 013017 (2014)]. We study the suppression of non-equilibrium long-ranged correlations of concentration fluctuations by chemical reactions, as well as the enhancement of pattern formation by spontaneous fluctuations. Good agreement with available theory demonstrates that the formulation is robust and a useful tool in the study of fluctuations in reactive multi-species fluids. At the same time, several problems with Langevin formulations of stochastic chemistry are identified, suggesting that future work should examine combining Langevin and master equation descriptions of hydrodynamic and chemical fluctuations.

  17. Understanding the extraordinary ionic reactivity of aqueous nanoparticles

    NARCIS (Netherlands)

    Leeuwen, van H.P.; Buffle, J.; Duval, J.F.L.; Town, R.M.

    2013-01-01

    Nanoparticles (NPs) are generally believed to derive their high reactivity from the inherently large specific surface area. Here we show that this is just the trivial part of a more involved picture. Nanoparticles that carry electric charge are able to generate chemical reaction rates that are even

  18. Does oligomerization in fused thiophene affect reactivity and ...

    Indian Academy of Sciences (India)

    Besides, a large number of experimental studies are devoted to the designing of new thiophene materials, a ... Seal and Chakrabarti.77 Therefore, in the present study, apart from the NICS(0) values, NICS(0.2), NICS(0.4),. NICS(0.6) ...... 3 Part I (Singapore: World Scien- tific). 32. Chattaraj P K 2009 In Chemical Reactivity ...

  19. [Schizophrenia and pain reactivity].

    Science.gov (United States)

    Bonnot, Olivier; Tordjman, Sylvie

    2008-11-01

    Medical practitioners do not for a long time pay enough attention to patient's pain. This approach is in the line of society feelings. Pain was long consider to be a contingency to withstand as showed in Christian's bible or Stoicism's principle. Changes in mentality appear in present times. It Seems obvious that for sociological and scientific reasons pain's care in medical and psychiatric disorders is now an important subject. Recent research in autistic disorders suggest that insensitivity observed in autism is not and analgesic phenomenon but a different behavioural reactivity to pain. Prevalence of schizophrenic disorder is from 0.5 to 1%. It is also a complex disorder that has defied decades of concerted efforts to uncover its origins and attenuate its symptoms. The most promising hypotheses suggest that neurodevelopmental impairment increases the risk of later schizophrenia. Most of recent researches in this topic did focus to trait or state markers. According to the vulnerability models of schizophrenia, trait marker are clinical, psychological, physiological, anatomical or cognitive impairments found in patients with schizophrenia during all the course of the illness and even before the onset. Several lines of evidence (case report, epidemiological studies, experimental studies) suggest that patients with schizophrenia shows a relative insensitivity to physical pain. We will review and critic the scientific literature in this specific topic. We will see if datas are relevant with the neurodevelopmental hypothesis and vulnerability models. An OLDMEDLINE/MEDLINE query was performed to identify 50 articles relevant to our subject. 9 were case report or case series, 21 were clinical or epidemiological studies, 15 were experimental studies and we also found 5 previous review. Clinical and experimental data strongly suggest a decrease of Behavioural Reactivity to Pain (BRP) but there is a lack of argument to prove a real analgesia. Because schizophrenia is a

  20. Pembrolizumab reactivates pulmonary granulomatosis

    Directory of Open Access Journals (Sweden)

    Majdi Al-dliw

    2017-01-01

    Full Text Available Sarcoid like reaction is a well-known entity that occurs as a consequence to several malignancies or their therapies. Immunotherapy has gained a lot of interest in the past few years and has recently gained approval as first line therapy in multiple advanced stage malignancies. Pneumonitis has been described as complication of such therapy. Granulomatous inflammation has been only rarely reported subsequent to immunotherapy. We describe a case of granulomatous inflammation reactivation affecting the lungs in a patient previously exposed to Pembrolizumab and have evidence of a distant granulomatous infection. We discuss potential mechanisms of the inflammation and assert the importance of immunosuppression in controlling the dis-inhibited immune system.

  1. Chemical Safety Alert: Safe Storage and Handling of Swimming Pool Chemicals

    Science.gov (United States)

    Hazards of pool water treatment and maintenance chemicals (e.g., chlorine), and the protective measures pool owners should take to prevent fires, toxic vapor releases, and injuries. Triggered by improper wetting, mixing, or self-reactivity over time.

  2. An Open-Source, Low-Cost Robot for Performing Reactive Liquid Handling Experiments

    DEFF Research Database (Denmark)

    Nejatimoharrami, Farzad; Faina, Andres; Støy, Kasper

    We have developed a low-cost, open source robot to automate reactive liquid handling tasks. Specifically, the robot, called EvoBot, targets reactive manipulation of motile droplets, a task prevalent in artificial chemical life research. We address hardware design and software implementation of our...

  3. Investigation of the role of the C-PCM solvent effect in reactivity indices

    Indian Academy of Sciences (India)

    This present work is focused on the analysis of a molecular system, under the influence of C-PCM induced solvent effect. The analysis is based on reactivity indices derived from DFT. The shift of frequency for diatomic molecules has been obtained. It has been identified as chemical force effect. The role of nuclear reactivity ...

  4. Solar light-induced production of reactive oxygen species by single walled carbon nanotubes in water

    Science.gov (United States)

    Photosensitizing processes of engineered nanomaterials (ENMs) which include photo-induced production of reactive oxygen species (ROS) convert light energy into oxidizing chemical energy that mediates transformations of nanomaterials. The oxidative stress associated with ROS may p...

  5. Lysine reactivity and starch gelatinization in extruded and pelleted canine diets

    NARCIS (Netherlands)

    Tran, Q.D.; Lin, van C.G.J.M.; Hendriks, W.H.; Poel, van der A.F.B.

    2007-01-01

    Fifteen dry adult canine diets (i.e., dinners, extrudates, pellets) were collected from retailers in Wageningen, The Netherlands, and chemically and physically characterized. Quality measurements were lysine O-methylisourea (OMIU) reactivity and starch gelatinization degree (SGD). In general,

  6. Oxygen Reactivity of a Carbon Fiber Composite

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Theron Devol; Pawelko, Robert James; Anderl, Robert Andrew; Smolik, Galen Richard

    2002-09-01

    Carbon Fiber Composites (CFCs) are often suggested as armor material for the first wall of a fusion plasma chamber due to carbon's low atomic number, high thermal conductivity, and high melting point. However, carbon is chemically reactive in air and will react with ingress air during a Loss of Vacuum Accident and release tritium fuel that has been retained in the carbon. Tritium mobilization and carbon monoxide generation via CFC oxidation are both safety concerns. This paper discusses chemical reactivity experiments that were performed using the state-of-the-art 3-dimensional NB31 CFC produced by SNECMA and a laminar reaction gas of Ar–21 vol% O2. Oxidation reaction rates were measured for CFC temperatures of 525, 600, 700, 800, 900, and 1000 °C and a 100 standard cubic centimeters per minute (sccm) Ar–O2 flow rate. Experiments were also performed at CFC temperatures of 700 and 1000 °C and a 1000 sccm Ar–O2 flow rate. Mass spectral analyses of the exhaust reaction gas suggested that carbon monoxide was the primary reaction at the CFC surface and carbon dioxide was readily produced in the exiting reaction gas. The measured reaction rates compare well with the literature and were used to produce a CFC oxidation curve that is recommended for use in fusion safety analyses.

  7. Weigle Reactivation in Acinetobacter Calcoaceticus

    DEFF Research Database (Denmark)

    Berenstein, Dvora

    1982-01-01

    Weigle (W)-reactivation was demonstrated in Acinetobacter calcoaceticus for the UV-irra-diated lysogenic phage P78. The reactivation factor (survival of irradiated phage on irradiated bacteria/ survival on unirradiated bacteria) reached a maximum value of 20. This was obtained at UV-doses giving...

  8. Stress Reactivity in Male Undergraduates.

    Science.gov (United States)

    Sharpley, Christopher F.; Fleming, Richard K.

    1989-01-01

    Measured heart rate reactivity of typical sample of male undergraduates. Found cardiac reactivity of undergraduate males in response to a stressor task was not a function of success at or familiarity with task but was more likely an outcome of genetic factors. (Author/ABL)

  9. Cortisol reactivity in young infants

    NARCIS (Netherlands)

    Jansen, J.; Beijers, R.; Riksen-Walraven, J.M.A.; Weerth, C. de

    2010-01-01

    In this systematic review on empirical studies of cortisol reactivity to acute stressors in infants, we specifically focus on the role of infant age in the early development of cortisol reactivity to stressors. Our findings indicate that many psychological stressors do not provoke a cortisol

  10. Chemical Variations on the p53 Reactivation Theme

    Directory of Open Access Journals (Sweden)

    Carlos J. A. Ribeiro

    2016-05-01

    Full Text Available Among the tumor suppressor genes, p53 is one of the most studied. It is widely regarded as the “guardian of the genome”, playing a major role in carcinogenesis. In fact, direct inactivation of the TP53 gene occurs in more than 50% of malignancies, and in tumors that retain wild-type p53 status, its function is usually inactivated by overexpression of negative regulators (e.g., MDM2 and MDMX. Hence, restoring p53 function in cancer cells represents a valuable anticancer approach. In this review, we will present an updated overview of the most relevant small molecules developed to restore p53 function in cancer cells through inhibition of the p53-MDMs interaction, or direct targeting of wild-type p53 or mutated p53. In addition, optimization approaches used for the development of small molecules that have entered clinical trials will be presented.

  11. Chemical reactivity of hypervalent silicon compounds: The local ...

    Indian Academy of Sciences (India)

    Author Affiliations. Francisco Méndez1 María De L Romero1 José L Gazquez1. Departamento de Química, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, A.P. 55-534, México, D.F. 09340, México ...

  12. Spectroscopic and chemical reactivity analysis of D-Myo-Inositol ...

    Indian Academy of Sciences (India)

    Devendra P Mishra

    2017-06-20

    Jun 20, 2017 ... and leguminosae plants, has been reported to pos- sess insulin-like properties. Although the hypoglycemic activity of D-Myo-Inositol was recognized in recent years, the molecular mechanism of D-Myo-Inositol in the treatment of diabetes mellitus remains unclear. Diabetes mellitus is a complex disease that ...

  13. Magic Numbers in Molecular Clusters: A Probe for Chemical Reactivity

    Science.gov (United States)

    1992-05-29

    Manegement and Budget. 98frlawork 014dionion Pt (0704-0 IN). Waigto. C1$ 1. AGENCY USE ONLY (Loave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED...basic piece of information available from the CMS is the mass to charge ratio (m/z) of the cluster ion. Fom this (and a general knowledge of the...mass spectral experiment however lies in the fact that the m/z ratio does not directly provide information concerning the structure of the ions, or

  14. Improved Understanding of In Situ Chemical Oxidation Soil Reactivity

    Science.gov (United States)

    2007-12-01

    hydroxide and sulfate ion, which obeys the first-order redox reaction with respect to oxygen, is also involved in the overall reactions that are...solid bismuthate in acid, ammonium persulfate, lead dioxide, potassium periodate, and ozone) are able to oxidize manganese ions to permanganate...showed that the generation rate of hydroxide radicals was proportionally related to the product of the hydrogen peroxide concentration and the solid

  15. Chemically Reactive Nitrogen Trace Species in the Planetary Boundary Layer

    Science.gov (United States)

    1996-01-01

    State University. While at PCnn State, Paul was involved with the University Student Government ( USO ) as a Fraterity Senator and was a member of the Phi...Lobroue L. and Chassin P., Nitrogen compound emissions from fertilized soils in a maize field pine tree forest agrosystem in the southwest of France...Heidelberg, 1990. Jambert, C., Delmas, R.A., Lobroue, L., and Chassin, P., Nitrogen compound emissions from fertilized soils in a maize field pine tree

  16. Unraveling the Nature of Chemical Reactivity of Complex Systems

    Science.gov (United States)

    2009-01-13

    11, 12). For an exo- thermic A BC reaction, the reaction barrier is usually located in the entrance valley of the reaction, that is, an early...parametrized, for an isolated autoionization state, using the theoretically proposed scaling relationship for the width and the energy shift with...Grzhimailo et al [12] addressed exactly such a question. They showed theoretically that in the region of an isolated autoionizing resonance state, the

  17. Reactivity of Dual-Use Decontaminants with Chemical Warfare Agents

    Science.gov (United States)

    2016-07-01

    potassium bisulfate, potassium sulfate , dipotassium peroxodisulfate, magnesium carbonate Acidic oxidative chemistry, used for VX laboratory waste...For example, the lethal dose of VX for a 70 kg person is 0.1 mg, and the no- observed- adverse - effect level (NOAEL) for a 70 kg person is approximately...chloroethyl) sulfide LC liquid chromatography LD log difference LDR log difference for reactor NOAEL no-observed- adverse - effect level NSN National

  18. Chemical Reactivity as a Probe of Ionic-Liquid Surfaces

    Science.gov (United States)

    2009-04-30

    the reaction dynamics of O(3P) and liquid hydrocarbons.29,30,31,32,33,34 Central to the apparatus is a 5 cm- diameter stainless steel wheel (Fig. 1...M. T. Räisänen, M. L. Costen, and K. G. McKendrick, J. Phys. Chem. A, 2009, 113, 4320 . 37 F. Ausfelder and K. G. McKendrick, Progress in Reaction

  19. Stratospheric Ozone Reactive Chemicals Generated by Space Launches Worldwide.

    Science.gov (United States)

    1994-11-01

    I ODCs). Their carbon - chlorine bond is severed in the stratosphere by solar photolysis or reaction. Once the carbon-chlorine bond is broken, the...include the Russian Proton and Energia , and the Chinese Long March series. Roughly half (seven per year) of the Ariane 4 launches use two solid strap-ons

  20. Influence of LaFeO3 Surface Termination on Water Reactivity

    OpenAIRE

    Stoerzinger, KA; Comes, R.; Spurgeon, SR; Thevuthasan, S; Ihm, K; Crumlin, EJ; Chambers, SA

    2017-01-01

    © 2017 American Chemical Society. The polarity of oxide surfaces can dramatically impact their surface reactivity, in particular, with polar molecules such as water. The surface species that result from this interaction change the oxide electronic structure and chemical reactivity in applications such as photoelectrochemistry but are challenging to probe experimentally. Here, we report a detailed study of the surface chemistry and electronic structure of the perovskite LaFeO 3 in humid condi...

  1. A Tariff for Reactive Power

    Energy Technology Data Exchange (ETDEWEB)

    Kueck, John D [ORNL; Kirby, Brendan J [ORNL; Li, Fangxing [ORNL; Tufon, Christopher [Pacific Gas and Electric Company; Isemonger, Alan [California Independent System Operator

    2008-07-01

    Two kinds of power are required to operate an electric power system: real power, measured in watts, and reactive power, measured in volt-amperes reactive or VARs. Reactive power supply is one of a class of power system reliability services collectively known as ancillary services, and is essential for the reliable operation of the bulk power system. Reactive power flows when current leads or lags behind voltage. Typically, the current in a distribution system lags behind voltage because of inductive loads such as motors. Reactive power flow wastes energy and capacity and causes voltage droop. To correct lagging power flow, leading reactive power (current leading voltage) is supplied to bring the current into phase with voltage. When the current is in phase with voltage, there is a reduction in system losses, an increase in system capacity, and a rise in voltage. Reactive power can be supplied from either static or dynamic VAR sources. Static sources are typically transmission and distribution equipment, such as capacitors at substations, and their cost has historically been included in the revenue requirement of the transmission operator (TO), and recovered through cost-of-service rates. By contrast, dynamic sources are typically generators capable of producing variable levels of reactive power by automatically controlling the generator to regulate voltage. Transmission system devices such as synchronous condensers can also provide dynamic reactive power. A class of solid state devices (called flexible AC transmission system devices or FACTs) can provide dynamic reactive power. One specific device has the unfortunate name of static VAR compensator (SVC), where 'static' refers to the solid state nature of the device (it does not include rotating equipment) and not to the production of static reactive power. Dynamic sources at the distribution level, while more costly would be very useful in helping to regulate local voltage. Local voltage regulation would

  2. Application of a data assimilation method via an ensemble Kalman filter to reactive urea hydrolysis transport modeling

    Energy Technology Data Exchange (ETDEWEB)

    Juxiu Tong; Bill X. Hu; Hai Huang; Luanjin Guo; Jinzhong Yang

    2014-03-01

    With growing importance of water resources in the world, remediations of anthropogenic contaminations due to reactive solute transport become even more important. A good understanding of reactive rate parameters such as kinetic parameters is the key to accurately predicting reactive solute transport processes and designing corresponding remediation schemes. For modeling reactive solute transport, it is very difficult to estimate chemical reaction rate parameters due to complex processes of chemical reactions and limited available data. To find a method to get the reactive rate parameters for the reactive urea hydrolysis transport modeling and obtain more accurate prediction for the chemical concentrations, we developed a data assimilation method based on an ensemble Kalman filter (EnKF) method to calibrate reactive rate parameters for modeling urea hydrolysis transport in a synthetic one-dimensional column at laboratory scale and to update modeling prediction. We applied a constrained EnKF method to pose constraints to the updated reactive rate parameters and the predicted solute concentrations based on their physical meanings after the data assimilation calibration. From the study results we concluded that we could efficiently improve the chemical reactive rate parameters with the data assimilation method via the EnKF, and at the same time we could improve solute concentration prediction. The more data we assimilated, the more accurate the reactive rate parameters and concentration prediction. The filter divergence problem was also solved in this study.

  3. Reatividade animal Confinement reactivity

    Directory of Open Access Journals (Sweden)

    Walsiara Estanislau Maffei

    2009-07-01

    Full Text Available A reatividade é definida como a reação do animal quando contido num ambiente de contenção móvel. Ela é quantificada por meio do teste de reatividade animal em ambiente de contenção móvel - REATEST®. Este teste consiste num dispositivo eletrônico acoplado à balança e num software específico. O dispositivo capta a movimentação que o animal provoca na balança, durante 20 segundos e a envia para o software que a processa determinando a reatividade do animal numa escala contínua de pontos. Pontuações maiores são de animais mais reativos (mais agressivo. A reatividade foi criada com os objetivos de solucionar os problemas até então existentes na seleção para temperamento e de permitir estimação de parâmetros genéticos mais confiáveis. Ela é uma característica objetiva que tem grande variabilidade fenotípica e é de quantificação rápida, fácil e segura, além de poder ser quantificada em qualquer tipo de balança, o que permite maior aplicabilidade. Ela não interfere nas práticas de manejo das fazendas porque é quantificada no momento da pesagem dos animais. Sua herdabilidade na raça Nelore é de 0,39 ao ano e 0,23 ao sobreano e suas correlações genéticas com ganho de peso diário são de -0,28 do nascimento até desmama e de -0,49 do desmame até ano. Já suas correlações genéticas com desenvolvimento do perímetro escrotal do ano ao sobreano variam de -0,25 e -0,41.The confinement reactivity (CR has been used as a measure of temperament in Brazil and it is defined as the animal reaction when contained in the scale. It is quantified through the animal reactivity test - REATEST®. This test consists of an electronic device coupled to the scale and of specific software. The device captures the movement that the animal provokes in the scale, during 20 seconds and sends it for the software that processes this movement and determines the animal CR in a continuous scale of points. Higher punctuations belong to

  4. Synthesis, XRD crystal structure, spectroscopic characterization (FT-IR, 1H and 13C NMR), DFT studies, chemical reactivity and bond dissociation energy studies using molecular dynamics simulations and evaluation of antimicrobial and antioxidant activities of a novel chalcone derivative, (E)-1-(4-bromophenyl)-3-(4-iodophenyl)prop-2-en-1-one

    Science.gov (United States)

    Zainuri, D. Alwani; Arshad, Suhana; Khalib, N. Che; Razak, I. Abdul; Pillai, Renjith Raveendran; Sulaiman, S. Fariza; Hashim, N. Shafiqah; Ooi, K. Leong; Armaković, Stevan; Armaković, Sanja J.; Panicker, C. Yohannan; Van Alsenoy, C.

    2017-01-01

    In the present study, the title compound named as (E)-1-(4-bromophenyl)-3-(4-iodophenyl)prop-2-en-1-one was synthesized and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system with P21/c space group with the unit cell parameters of a = 16.147 (2) Å, b = 14.270 (2) Å, c = 5.9058 (9) Å, β = 92.577 (3)° and Z = 4. The molecular geometry obtained from X-Ray structure determination was optimized by Density Functional Theory (DFT) using B3LYP/6-31G+(d, p)/Lanl2dz(f) method in the ground state. The IR spectrum was recorded and interpreted in details with the aid of Density Functional Theory (DFT) calculations and Potential Energy Distribution (PED) analysis. In order to investigate local reactivity properties of the title molecule, we have conducted DFT calculations of average local ionization energy surface and Fukui functions which were mapped to the electron density surface. In order to predict the open air stability and possible degradation properties, within DFT approach, we have also calculated bond dissociation energies. 1H and 13C NMR spectra were recorded and chemical shifts were calculated theoretically and compared with the experimental values. In addition, in vitro antimicrobial results show that the title compound has great potential of antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis and Micrococcus luteus bacteria and antifungal activity against Candida albicans in comparison to some reported chalcone derivatives. Antioxidant studies revealed the highest metal chelating activity of this compound.

  5. Design and synthesis of reactive separation systems. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Doherty, M.F.

    1992-12-31

    During the last decade there has been a rapid upturn in interest in reactive distillation. The chemical process industry recognizes the favorable economics of carrying out reaction simultaneously with distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for reactive distillation systems have only recently begun to emerge. In this report we survey the available design techniques and point out the contributions made by our group at the University of Massachusetts.

  6. Chemical use

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a summary of research and activities related to chemical use on Neal Smith National Wildlife Refuge between 1992 and 2009. The chemicals used on the Refuge...

  7. The diffusion-active permeable reactive barrier.

    Science.gov (United States)

    Schwarz, Alex O; Rittmann, Bruce E

    2010-03-01

    Using the biogeochemical model CCBATCH, which we expanded to include transport processes, we study a novel approach for the treatment of aquifers contaminated with toxic concentrations of metals, the diffusion-active permeable reactive barrier (DAPRB), which is based on generation of sulfide by Sulfate Reducing Bacteria (SRB) as the groundwater moves through a layered treatment zone. In the DAPRB, layers of low conductivity (low-K) containing reactive materials are intercalated between layers of high conductivity (high-K) that transport the groundwater across the barrier. Because diffusion dominates transport in the reactive layers, microbial communities can take advantage there of the chemical-gradient mechanism for protection from toxicants. The ideal sulfidic DAPRB design includes particulate organic matter (POM) and solid sulfate mineral inside the reactive (low-K) layer. This leads to sulfate reduction and the formation of sulfide ligands that complex with toxic metals, such as Zn(2+) in the high-K layer. We perform a theoretical biogeochemical analysis of the ideal configuration of a DAPRB for treatment of Zn-contaminated groundwater. Our analysis using the expanded CCBATCH confirms the gradient-resistance mechanism for bio-protection, with the ZnS bio-sink forming at the intersection of the Zn and sulfide plumes inside the high-K layers of the DAPRB. The detailed DAPRB analysis also shows that total alkalinity and pH distributions are representative footprints of the two key biogeochemical processes taking place, sulfidogenesis and Zn immobilization as sulfide mineral. This is so because these two reactions consume or produce acidic hydrogen and alkalinity. Additionally, because Zn immobilization is due to ZnS mineral precipitation, the ZnS mineral distribution is a good indicator for the bio-sink. Bio-sinks are located for the most part within the high-K layers, and their exact position depends on the relative magnitude of metal and sulfide fluxes. Finally

  8. Finite element analysis of non-isothermal warm deep drawing of dual phase steel

    Directory of Open Access Journals (Sweden)

    Pepelnjak T.

    2016-01-01

    Full Text Available Improving the formability of the material is an important issue in the deep drawing process. Heating the material above its recrystallization temperature drastically increases formability but in the case of dual phase (DP steels it results in the loss of their mechanical properties. To improve the drawing ratio, only the heating of the flange region in the warm temperature range up to 300°C was studied on DP600 sheet steel by numerical simulation. Thermo-elastic-plastic FEM analysis of deep drawing at several drawing ratios was performed and compared with experimental results.

  9. Implementation of Fuzzy Sets in the Non-Isothermal Pyrolysis of Biomass

    Directory of Open Access Journals (Sweden)

    Alok Dhaundiyal

    2017-04-01

    Full Text Available This paper proposes the study of the application of fuzzy logic on the relevant parameter of biomass pyrolysis. The frequency factor, the upper limit of ‘dE’, and the scale and shape parameters of the fuzzy Gamma distribution were fuzzified in order to estimate randomness and to accommodate realistic values. The distribution function, f (E, of the activation energies was assumed to follow the fuzzy Gamma distribution. Thermo-analytical data was found experimentally with the help of TGA/DTG analysis. The approximated solution of the DAEM was obtained using the asymptotic approach.

  10. Crystallization kinetics of orthorhombic paracetamol from supercooled melts studied by non-isothermal DSC.

    Science.gov (United States)

    Nikolakakis, Ioannis; Kachrimanis, Kyriakos

    2017-02-01

    A simple and highly reproducible procedure was established for the study of orthorhombic paracetamol crystallization kinetics, comprising melting, quench-cooling of the melt and scanning the formed glass by DSC at different heating rates. Results were analyzed on the basis of the mean as well as local values of the Avrami exponent, n, the energy of activation, as well as the Šesták-Berggren two-parameter autocatalytic kinetic model. The mean value of the Avrami kinetic exponent, n, ranged between 3 and 5, indicating deviation from the nucleation and growth mechanism underlying the Johnson-Mehl, Avrami-Kolmogorov (JMAK) model. To verify the extent of the deviation, local values of the Avrami exponent as a function of the volume fraction transformed were calculated. Inspection of the local exponent values indicates that the crystallization mechanism changes over time, possibly reflecting the uncertainty of crystallization onset, instability of nucleation due to an autocatalytic effect of the crystalline phase, and growth anisotropy due to impingement of spherulites in the last stages of crystallization. The apparent energy of activation, E a , has a rather low mean value, close to 81 kJ/mol, which is in agreement with the observed instability of glassy-state paracetamol. Isoconversional methods revealed that E a tends to decrease with the volume fraction transformed, possibly because of the different energy demands of nucleation and growth. The exponents of the Šesták-Berggren two-parameter model showed that the crystallized fraction influences the process, confirming the complexity of the crystallization mechanism.

  11. Non-isothermal crystallization kinetics of eucalyptus lignosulfonate/polyvinyl alcohol composite.

    Science.gov (United States)

    Ye, De-Zhan; Zhang, Xi; Gu, Shaojin; Zhou, Yingshan; Xu, Weilin

    2017-04-01

    The nonisothermal crystallinization kinetic was performed on Polyvinyl alcohol (PVA) mixed with eucalyptus lignosulfonate calcuim (HLS) as the biobased thermal stabilizer, which was systematically analyzed based on Jeziorny model, Ozawa equation and the Mo method. The results indicated that the entire crystallization process took place through two main stages involving the primary and secondary crystallization processes. The Mo method described nonisothermal crystallization behavior well. Based on the results of the half time for completing crystallization, k c value in Jeziorny model, F(T) value in Mo method and crystallization activation energy, it was concluded that low loading of HLS accelerated PVA crystallization process, however, the growth rate of PVA crystallization was impeded at high content of HLS. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Surface tension and buoyancy-driven flow in a non-isothermal liquid bridge

    Science.gov (United States)

    Zhang, Yiqiang; Alexander, J. I. D.

    1992-01-01

    The Navier-Stokes-Boussinesq equations governing the transport of momentum, mass and heat in a nonisothermal liquid bridge with a temperature-dependent surface tension are solved using a vorticity-stream-function formulation together with a nonorthogonal coordinate transformation. The equations are discretized using a pseudo-unsteady semi-implicit finite difference scheme and are solved by the ADI method. A Picard-type iteration is adopted which consists of inner and outer iterative processes. The outer iteration is used to update the shape of the free surface. Two schemes have been used for the outer iteration; both use the force balance normal to the free surface as the distinguished boundary condition. The first scheme involves successive approximation by the direct solution of the distinguished boundary condition. The second scheme uses the artificial force imbalance between the fluid pressure, viscous and capillary forces at the free surface which arises when the boundary condition for force balance normal to the surface is not satisfied. This artificial imbalance is then used to change the surface shape until the distinguished boundary condition is satisfied. These schemes have been used to examine a variety of model liquid bridge situations including purely thermocapillary-driven flow situations and mixed thermocapillary- and bouyancy-driven flow.

  13. A 2+1-Dimensional Non-Isothermal Magnetogasdynamic System. Hamiltonian-Ermakov Integrable Reduction

    Directory of Open Access Journals (Sweden)

    Hongli An

    2012-08-01

    Full Text Available A 2+1-dimensional anisentropic magnetogasdynamic system with a polytropic gas law is shown to admit an integrable elliptic vortex reduction when γ=2 to a nonlinear dynamical subsystem with underlying integrable Hamiltonian-Ermakov structure. Exact solutions of the magnetogasdynamic system are thereby obtained which describe a rotating elliptic plasma cylinder. The semi-axes of the elliptical cross-section, remarkably, satisfy a Ermakov-Ray-Reid system.

  14. 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

  15. Experimental investigation of mixing of non-isothermal water streams at BWR operating conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bergagio, Mattia, E-mail: bergagio@kth.se [AlbaNova University Center, Nuclear Reactor Technology Division, Department of Physics, Royal Institute of Technology, 106 91 Stockholm (Sweden); Anglart, Henryk, E-mail: henryk@kth.se [AlbaNova University Center, Nuclear Reactor Technology Division, Department of Physics, Royal Institute of Technology, 106 91 Stockholm (Sweden); Institute of Heat Engineering, Warsaw University of Technology, 21/25 Nowowiejska Street, 00-665 Warsaw (Poland)

    2017-06-15

    Highlights: • Temperatures are measured in the presence of mixing at BWR operating conditions. • The thermocouple support is moved along a pattern to extend the measurement region. • Uncertainty of 1.58 K for temperatures acquired at 1000 Hz. • Momenta of the hot streams and thermal stratification affect the data examined. • Unconventional spectral analysis is required to further study the data collected. - Abstract: In this experimental investigation, wall surface temperatures have been measured during mixing of three water streams in the annular gap between two coaxial stainless-steel tubes. The inner tube, with an outer diameter of 35 mm and a thickness of 5 mm, holds six K-type, ungrounded thermocouples with a diameter of 0.5 mm, which measured surface temperatures with a sampling rate of either 100 Hz or 1000 Hz. The tube was rotated from 0 to 360° and moved in a range of 387 mm in the axial direction to allow measurements of surface temperatures in the whole mixing region. The outer tube has an inner diameter of 80 mm and a thickness of 10 mm to withstand a water pressure of 9 MPa. A water stream at a temperature of either 333 K or 423 K and a Reynolds number between 1657 and 8410 rose vertically in the annular gap and mixed with two water streams at a temperature of 549 K and a Reynolds number between 3.56 × 10{sup 5} and 7.11 × 10{sup 5}. These two water streams entered the annulus radially on the same axial level, 180° apart. Water pressure was kept at 7.2 MPa. Temperature recordings were performed at five axial and eight azimuthal locations, for each set of boundary conditions. Each recording lasted 120 s to provide reliable data on the variance, intermittency and frequency of the surface temperature time series at hand. Thorough calculations indicate that the uncertainty in the measured temperature is of 1.58 K. The mixing region extends up to 0.2 m downward of the hot inlets. In most cases, measurements indicate non-uniform mixing in the azimuthal direction, because of asymmetries in either geometry or mass flow rates at the hot inlets. Due to the measurement accuracy and a relatively simple geometry, an experimental database has been obtained for validation of computational methods to predict thermal mixing and fatigue. Furthermore, these data can provide new insight into turbulent mixing at BWR operating conditions and, more generally, into mixing coupled to the dynamics, also termed level-2 mixing.

  16. MATHEMATICAL MODEL NON-ISOTHERMAL FLOW HIGHLY VISCOUS MEDIA CHANNELS MATRIX EXTRUDER

    Directory of Open Access Journals (Sweden)

    A. S. Sidorenko

    2015-01-01

    Full Text Available We consider a one-dimensional steady flow of highly viscous medium in a cylindrical channel with Dissipation and dependence of the viscosity on the temperature. It is assumed that a relatively small intervals of temperature variation of the dynamic viscosity with a sufficient degree of accuracy can be assumed to be linear. The model was based on the equations of hydrodynamics and the heat transfer fluid. In the task channel wall temperature is assumed constant. An approximate solution of the problem, according to which the distribution of velocity, pressure and temperature is sought in the form of an expansion in powers of the dimensionless transverse coordinates. A special case, when the ratio of the velocity distribution, pressure and temperature is allowed to restrict the number of terms in the expansion as follows: for speed - the first 3 to the pressure - the first two for the temperature - the first 5. The expressions to determine the temperature profile of the medium in the channel and characterization dissipative heating. To simulate the process of heat transfer highly viscous media developed a program for personal electronic computers. The calculation was performed using experimental research data melt flow grain mixture of buckwheat and soybeans for the load speed of 0.08 mm / s. The method of computer simulation carried out checks on the adequacy of the solutions to the real process of heat transfer. Analysis of the results indicates that for small values of the length of the channel influence dissipation function appears mainly at the wall. By increasing the reduced length of this phenomenon applies to all section of the channel. At high temperature profile along the channel length is determined entirely by dissipation. In the case of heat transfer due to frictional heat only, the form of curves of temperature distribution is a consequence of the interaction effects of heating due to viscous shear effects cooling by conduction. The deviation from the experimental data calculated by the absolute value does not exceed 12%.

  17. Mathematical modelling of moisture transport into an electronic enclosure under non-isothermal conditions

    DEFF Research Database (Denmark)

    Staliulionis, Ž.; Mohanty, S.; Jabbari, Mahmoud

    2017-01-01

    has the capability of combining lumped components and a 1D description. Heat and mass transport is based on a FVM discretization of the heat conduction equation and Fick's second law. Simulation results are compared with corresponding experimental findings and good agreement is found. Since, the paper...

  18. Numerical study to represent non-isothermal melt-crystallization kinetics at laser-powder cladding

    CSIR Research Space (South Africa)

    Niziev, VG

    2013-04-01

    Full Text Available model for direct metal deposition with coaxial powder injection. He et al. [9] used that model for investigation of transport phenomena. Modeling of heat-and-mass transfer during plasma deposition manu- facturing has some similar solutions [10... in plasma torch formation and decreases powder capture efficiency that influences negatively on laser cladding. The effect of fluid motion due to Marangoni forces is modeled by in- troducing an enhanced thermal conductivity factor in the melt pool region...

  19. Non-isothermal axial flow of a rarefied gas between two coaxial cylinders

    Directory of Open Access Journals (Sweden)

    Elvira Barbera

    2017-06-01

    Full Text Available A stationary problem of heat transfer in a rarefied gas confined between two coaxial cylinders is presented. The two cylinders are maintained at two different constant temperatures, so that a radial temperature gradient is created. The external cylinder is at rest, while the internal one moves in the axial direction with a constant velocity. A flow of the gas in the z-direction, orthogonal to the temperature gradient, is created by the motion of the internal boundary. Instead of the classical Navier-Stokes and Fourier theory, the field equations of extended thermodynamics with 13 moments are used in order to describe this physical problem. It turns out that, although only a radial temperature difference is imposed, the heat flux presents also an axial component. Moreover, some components of the stress tensor do not vanish, even though the axial velocity of the gas depends only on the radial coordinate r. The solution here obtained is compared with the classical one. Furthermore, the dependence of the solution on the boundary velocity is investigated.

  20. Does the schock wave in a highly ionized non-isothermal plasma really exist ?

    CERN Document Server

    Rukhadze, A A; Samkharadze, T

    2015-01-01

    Here we study the structure of a highly ionizing shock wave in a gas of high atmospheric pressure. We take into account the gas ionization when the gas temperature reaches few orders of an ionization potential. It is shown that after gasdynamic temperature-raising shock and formation of a highly-ionized nonisothermal plasma $T_e>>T_i$ only the solitary ion-sound wave (soliton) can propagate in this plasma. In such a wave the charge separation occurs: electrons and ions form the double electric layer with the electric field. The shock wave form, its amplitude and front width are obtained.