Method for improved decomposition of metal nitrate solutions

Science.gov (United States)

Haas, Paul A.; Stines, William B.

1983-10-11

A method for co-conversion of aqueous solutions of one or more heavy metal nitrates wherein thermal decomposition within a temperature range of about 300.degree. to 800.degree. C. is carried out in the presence of about 50 to 500% molar concentration of ammonium nitrate to total metal.

Radiation chemistry of aqueous solutions of acetonitrile and propionitrile

International Nuclear Information System (INIS)

Shushtarian, M.J.

1975-01-01

The radiation chemistry of water and aqueous solutions is a branch of radiation chemistry dealing with chemical changes in water and aqueous solutions induced by high energy radiations. High energy radiations of interest in radiation chemistry are short-wave electromagnetic radiations (X- and γ-rays) and fast charged particles (α- and β-particles, electrons, deuterons and fission fragments). The energy of the particles and photons bringing about chemical reactions in the field of modern radiation chemistry is much higher than that of photons causing photochemical reactions

Decomposition studies of no-clean solder flux systems in connection with corrosion reliability of electronics

DEFF Research Database (Denmark)

Conseil, Helene; Jellesen, Morten Stendahl; Verdingovas, Vadimas

2013-01-01

with specific soldering process and parameters, while most important factors are the flux chemistry and its decomposition characteristics. Active parts of the flux residue can cause increased water absorption due to their hygroscopic nature and in solution they will increase leakage current and corrosion...... the contaminated PCBA parts to varying humidity and measuring the resulting leakage current. Results revealed a significant influence of flux chemistry including the amount of WOAs, while aggressiveness of the residue seems to vary with content and type of WOAs, and their nature of decomposition....

Effect of Ultrasound on the Decomposition of Sodium Dodecylbenzene Sulfonate in Aqueous Solution

International Nuclear Information System (INIS)

Yim, Bong Been

2004-01-01

The influence of ultrasound frequency, dissolved gases, and initial concentration on the decomposition of sodium dodecylbenzene sulfonate(DBS) aqueous solution was investigated using ultrasound generator with 200 W ultrasound power. The decomposition rates at three frequencies(50, 200, and 600 kHz) examined under argon atmosphere were highest at 200 kHz. The highest observed decomposition rate at 200 kHz occurred in the presence of oxygen followed by air and argon, helium, and nitrogen. The effect of initial concentration of DBS on the ultrasonic decomposition was decreased with increasing initial concentration and would depend upon the formation of micelle in aqueous solution. It appears that the ultrasound frequency, dissolved gases, and initial concentration play an important role on the sonolysis of DBS. Sonolysis of DBS mainly take place at the interfacial region of cavitation bubbles by both OH radical attack and pyrolysis to alkyl chain, aromatic ring, and headgroup

Y2O3-MgO Nano-Composite Synthesized by Plasma Spraying and Thermal Decomposition of Solution Precursors

Science.gov (United States)

Muoto, Chigozie Kenechukwu

This research aims to identify the key feedstock characteristics and processing conditions to produce Y2O3-MgO composite coatings with high density and hardness using solution precursor plasma spray (SPPS) and suspension plasma spray (SPS) processes, and also, to explore the phenomena involved in the production of homogenized nano-composite powders of this material system by thermal decomposition of solution precursor mixtures. The material system would find potential application in the fabrication of components for optical applications such as transparent windows. It was shown that a lack of major endothermic events during precursor decomposition and the resultant formation of highly dense particles upon pyrolysis are critical precursor characteristics for the deposition of dense and hard Y2O3-MgO coatings by SPPS. Using these principles, a new Y2O3-MgO precursor solution was developed, which yielded a coating with Vickers hardness of 560 Hv. This was a considerable improvement over the hardness of the coatings obtained using conventional solution precursors, which was as low as 110 Hv. In the thermal decomposition synthesis process, binary solution precursor mixtures of: yttrium nitrate (Y[n]) or yttrium acetate (Y[a]), with magnesium nitrate (Mg[n]) or magnesium acetate (Mg[a]) were used in order to study the effects of precursor chemistry on the structural characteristics of the resultant Y2O3-MgO powders. The phase domains were coarse and distributed rather inhomogeneously in the materials obtained from the Y[n]Mg[n] and Y[a]Mg[a] mixtures; finer and more homogeneously-distributed phase domains were obtained for ceramics produced from the Y[a]Mg[n] and Y[n]Mg[a] mixtures. It was established that these phenomena were related to the thermal characteristics for the decomposition of the precursors and their effect on phase separation during oxide crystallization. Addition of ammonium acetate to the Y[n[Mg[n] mixture changed the endothermic process to exothermic

Molybdenum: the element and aqueous solution chemistry

International Nuclear Information System (INIS)

Sykes, A.G.

1987-01-01

This chapter on the chemistry of the coordination compounds of molybdenum concentrates on the element itself, its recovery from ores and its use in the manufacture of steels. Most of the chapter is devoted to the aqueous solution chemistry of molybdenum in oxidation states II, III and IV. (UK)

Thermal decomposition studies of aqueous and nitric solutions of hydroxyurea

International Nuclear Information System (INIS)

Shekhar Kumar; Pranay Kumar Sinha; Kamachi Mudali, U.; Natarajan, R.

2012-01-01

Hydroxyurea and its derivatives are important nonsalt forming reductants in partitioning of uranium and plutonium in the nuclear fuel reprocessing operations. There is no experimental data available in open literature describing pressurization due to the thermal decomposition of aqueous and nitric solutions of hydroxyurea at elevated temperatures. Authors studied thermal decomposition of hydroxyurea-nitric acid system and resultant pressurization at various concentrations of nitric acid in an adiabatic calorimeter in closed-vent conditions. During these experiments, pressurization was observed. In this paper, results of these experiments have been discussed. (author)

Synthesis of vanadium oxide powders by evaporative decomposition of solutions

International Nuclear Information System (INIS)

Lawton, S.A.; Theby, E.A.

1995-01-01

Powders of the vanadium oxides V 2 O 4 , V 6 O 13 , and V 2 O 5 were produced by thermal decomposition of aqueous solutions of vanadyl sulfate hydrate in atmospheres of N 2 , H 2 mixed with N 2 , or air. The composition of the oxide powder was determined by the reactor temperature and gas composition. Residual sulfur concentrations in powders produced by decomposition at 740 C were less than 1 at.%, and these powders consisted of hollow, roughly spherical aggregates of particles less than 1 microm in diameter

Complex chemistry of Np(V) in aqueous solutions

International Nuclear Information System (INIS)

Inoue, Yasushi

1989-01-01

Despite the importance of Np(V) in both the nuclear chemical engineering and the actinoid chemistry, little work has been performed on the complex chemistry of Np(V) in aqueous solutions, since Np(V) reacts less readily with various ligands. The author has directed his effort to understand the chemical behavior of Np(V) in aqueous solutions, especially the determination of the stability constants of Np(V) complexes with various ligands. A part of the results obtained so far is presented in the following order. (1) The synergistic extraction of Np(V) as a method for studying the complex chemistry of Np(V): TTA-MTOA(methyltrioctylammonium chloride), TTA-phen and TTA-TOPO. (2) The determination of the stability constants of Np(V) complexes with 22 organic- and 5 inorganic ligands by means of the solvent extraction. (3) The distribution of the chemical species of Np(V) in solutions under various conditions

Analysis of benzoquinone decomposition in solution plasma process

International Nuclear Information System (INIS)

Bratescu, M.A.; Saito, N.

2016-01-01

The decomposition of p-benzoquinone (p-BQ) in Solution Plasma Processing (SPP) was analyzed by Coherent Anti-Stokes Raman Spectroscopy (CARS) by monitoring the change of the anti-Stokes signal intensity of the vibrational transitions of the molecule, during and after SPP. Just in the beginning of the SPP treatment, the CARS signal intensities of the ring vibrational molecular transitions increased under the influence of the electric field of plasma. The results show that plasma influences the p-BQ molecules in two ways: (i) plasma produces a polarization and an orientation of the molecules in the local electric field of plasma and (ii) the gas phase plasma supplies, in the liquid phase, hydrogen and hydroxyl radicals, which reduce or oxidize the molecules, respectively, generating different carboxylic acids. The decomposition of p-BQ after SPP was confirmed by UV-visible absorption spectroscopy and liquid chromatography

Analysis of benzoquinone decomposition in solution plasma process

Science.gov (United States)

Bratescu, M. A.; Saito, N.

2016-01-01

The decomposition of p-benzoquinone (p-BQ) in Solution Plasma Processing (SPP) was analyzed by Coherent Anti-Stokes Raman Spectroscopy (CARS) by monitoring the change of the anti-Stokes signal intensity of the vibrational transitions of the molecule, during and after SPP. Just in the beginning of the SPP treatment, the CARS signal intensities of the ring vibrational molecular transitions increased under the influence of the electric field of plasma. The results show that plasma influences the p-BQ molecules in two ways: (i) plasma produces a polarization and an orientation of the molecules in the local electric field of plasma and (ii) the gas phase plasma supplies, in the liquid phase, hydrogen and hydroxyl radicals, which reduce or oxidize the molecules, respectively, generating different carboxylic acids. The decomposition of p-BQ after SPP was confirmed by UV-visible absorption spectroscopy and liquid chromatography.

The influence of temperature on the decomposition kinetics of peracetic acid in solutions

OpenAIRE

Kunigk, L.; Gomes, D.R.; Forte, F.; Vidal, K.P.; Gomes, L.F.; Sousa, P.F.

2001-01-01

Peracetic acid is a powerful sanitizer that has only recently been introduced in the Brazilian food industry. The main disadvantage of this sanitizer is its decomposition rate. The main purpose of this paper is to present results obtained in experiments carried out to study the decomposition kinetics of peracetic acid in aqueous solutions at 25, 35, 40 and 45 °C. The decompositon of peracetic acid is a first-order reaction. The decomposition rate constants are between 1.71x10-3 h -1 for 25 °C...

Influence of concentration on the radiolytic decomposition of thiamine, riboflavin, and pyridoxine in aqueous solution

Directory of Open Access Journals (Sweden)

Guadalupe Albarrán

2014-10-01

Full Text Available Vitamin loss during irradiation has been claimed as a critical area in food irradiation technology, especially that of thiamine (B1, which has been considered as the most sensitive to radiation. Although it has been suggested that no vitamin deficiency could result from consuming irradiated food, a long debate on the loss of vitamins and other nutrients during food irradiation has been maintained by the lack of experimental studies monitoring decomposition rates at different concentrations and doses. Since thiamine, riboflavin, and pyridoxine are labile vitamins, this study has focused on their radiolytic decomposition in dilute aqueous solutions in the presence of air. The decomposition process was followed by HPLC and UV-spectroscopy. The results obtained in aqueous solutions showed a dependence of the decomposition as a nonlinear function of the dose. Of these three compounds, the decomposition was higher for thiamine than for riboflavin and even less in pyridoxine.

Application of Homotopy-Perturbation Method to Nonlinear Ozone Decomposition of the Second Order in Aqueous Solutions Equations

DEFF Research Database (Denmark)

Ganji, D.D; Miansari, Mo; B, Ganjavi

2008-01-01

In this paper, homotopy-perturbation method (HPM) is introduced to solve nonlinear equations of ozone decomposition in aqueous solutions. HPM deforms a di¢ cult problem into a simple problem which can be easily solved. The effects of some parameters such as temperature to the solutions are consid......In this paper, homotopy-perturbation method (HPM) is introduced to solve nonlinear equations of ozone decomposition in aqueous solutions. HPM deforms a di¢ cult problem into a simple problem which can be easily solved. The effects of some parameters such as temperature to the solutions...

Kinetics of the decomposition and the estimation of the stability of 10% aqueous and non-aqueous hydrogen peroxide solutions

Directory of Open Access Journals (Sweden)

Zun Maria

2014-12-01

Full Text Available In this study, the stability of 10% hydrogen peroxide aqueous and non-aqueous solutions with the addition of 6% (w/w of urea was evaluated. The solutions were stored at 20°C, 30°C and 40°C, and the decomposition of hydrogen peroxide proceeded according to first-order kinetics. With the addition of the urea in the solutions, the decomposition rate constant increased and the activation energy decreased. The temperature of storage also affected the decomposition of substance, however, 10% hydrogen peroxide solutions prepared in PEG-300, and stabilized with the addition of 6% (w/w of urea had the best constancy.

Solutions to selected exercise problems in quantum chemistry and spectroscopy

DEFF Research Database (Denmark)

Spanget-Larsen, Jens

2016-01-01

Suggested solutions to a number of problems from the collection "Exercise Problems in Quantum Chemistry and Spectroscopy", previously published on ResearchGate (DOI: 10.13140/RG.2.1.4024.8162).......Suggested solutions to a number of problems from the collection "Exercise Problems in Quantum Chemistry and Spectroscopy", previously published on ResearchGate (DOI: 10.13140/RG.2.1.4024.8162)....

Decomposition features of a supersaturated solid solution in the Mg-3.3 wt. % Yb alloy

International Nuclear Information System (INIS)

Dobromyslov, A.V.; Kajgorodova, L.I.; Sukhanov, V.D.; Dobatkina, T.V.

2007-01-01

Methods of electron microscopy, hardness measuring and X-ray diffraction analysis are applied to study decomposition kinetics for a supersaturated solid solution in a Mg-3.3 mas. % alloy on aging within a temperature range of 150-225 deg C. The mechanism of supersaturation solid solution decomposition is revealed along with the nature of phases precipitated at various stages of aging: on incomplete and extended aging as well as at maximum hardness. The types of structural constituents responsible for changes of hardness on aging are determined [ru

Solution chemistry techniques in SYNROC preparation

International Nuclear Information System (INIS)

Dosch, R.G.; Lynch, A.W.

1981-07-01

Investigations of titanate-based ceramic forms for radioactive waste immobilization are underway at Sandia National Laboratories (SNLA) and at Lawrence Livermore National Laboratory (LLNL). Although the waste forms differ as to overall product composition, the waste-containing phases in both ceramic products have similar crystalline structure types. These include metallic phases along with oxides with structure types of the mineral analogues perovskite, zirconolite, and hollandite. Significant differences also exist in the area of processing. More conventional ceramic processing methods are used at LLNL to produce SYNROC while solution chemistry techniques involving metal alkoxide chemistry and ion exchange have been developed at SNLA to prepare calcium titanate-based waste ceramics. The SNLA techniques were recently modified and applied to producing SYNROC (compositions C and D) as part of an interlaboratory information exchange between SNLA and LLNL. This report describes the methods used in preparing SYNROC including the solution interaction, and hot-pressing methods used to obtain fully dense SYNROC monoliths

Chemistry of decomposition of freshwater wetland sedimentary organic material during ramped pyrolysis

Science.gov (United States)

Williams, E. K.; Rosenheim, B. E.

2011-12-01

Ramped pyrolysis methodology, such as that used in the programmed-temperature pyrolysis/combustion system (PTP/CS), improves radiocarbon analysis of geologic materials devoid of authigenic carbonate compounds and with low concentrations of extractable authochthonous organic molecules. The approach has improved sediment chronology in organic-rich sediments proximal to Antarctic ice shelves (Rosenheim et al., 2008) and constrained the carbon sequestration potential of suspended sediments in the lower Mississippi River (Roe et al., in review). Although ramped pyrolysis allows for separation of sedimentary organic material based upon relative reactivity, chemical information (i.e. chemical composition of pyrolysis products) is lost during the in-line combustion of pyrolysis products. A first order approximation of ramped pyrolysis/combustion system CO2 evolution, employing a simple Gaussian decomposition routine, has been useful (Rosenheim et al., 2008), but improvements may be possible. First, without prior compound-specific extractions, the molecular composition of sedimentary organic matter is unknown and/or unidentifiable. Second, even if determined as constituents of sedimentary organic material, many organic compounds have unknown or variable decomposition temperatures. Third, mixtures of organic compounds may result in significant chemistry within the pyrolysis reactor, prior to introduction of oxygen along the flow path. Gaussian decomposition of the reaction rate may be too simple to fully explain the combination of these factors. To relate both the radiocarbon age over different temperature intervals and the pyrolysis reaction thermograph (temperature (°C) vs. CO2 evolved (μmol)) obtained from PTP/CS to chemical composition of sedimentary organic material, we present a modeling framework developed based upon the ramped pyrolysis decomposition of simple mixtures of organic compounds (i.e. cellulose, lignin, plant fatty acids, etc.) often found in sedimentary

Correlation of foliage and litter chemistry of sugar maple, Acer saccharum, as affected by elevated CO2 and varying N availability, and effects on decomposition

Science.gov (United States)

J. S. King; K. S. Pregitzer; D. R. Zak; M. E. Kubiske; W. E. Holmes

2001-01-01

Rising atmospheric carbon dioxide has the potential to alter leaf litter chemistry, potentially affecting decomposition and rates of carbon and nitrogen cycling in forest ecosystems. This study was conducted to determine whether growth under elevated atmospheric CO2 altered the quality and microbial decomposition of leaf litter of a widely...

Radiation chemistry of amino acids and peptides in aqueous solutions

International Nuclear Information System (INIS)

Simic, M.G.

1978-01-01

Radiation chemistry relevant to radiation preservation of high protein foods is reviewed. Some conclusions concerning the chemistry of irradiated amino acids, peptides, and proteins have been derived from product analysis of γ-irradiated solutions while the main mechanistic considerations result from the chemistry and kinetics of free radical intermediates observed by pulse radiolysis. The precursors of chemistry in not too concentrated solutions ( - , OH, and H. Their reactivity with molecules and their preference for characteristic groups within the molecule are discussed. The reviewed reactions of the model systems are accountable for a variety of radiolytic products found in irradiated foods. From detailed understanding of radiation chemistry in aqueous and frozen systems formation of many classes of compounds can be predicted or entirely eliminated in order to corroborate and extend the conclusions reached from the animal feeding experiments concerning the formation of toxic, mutagenic, and carcinogenic compounds and/or reduction of the nutritional value of foods

Thermal decomposition and spectroscopic investigation of a new aqueous glycolato(-peroxo) Ti(IV) solution-gel precursor

International Nuclear Information System (INIS)

De Dobbelaere, Christopher; Mullens, Jules; Hardy, An; Van Bael, Marlies K.

2011-01-01

Highlights: → A totally water based glycolato-Ti(IV) precursor is presented and characterized. → The precursors' thermal decomposition profile depends on the ligand to metal ratio. → Titanium is coordinated in an unidentate fashion by the glycolate anion. → Smooth and uniform TiO 2 films can be prepared from the precursor solution. - Abstract: A new aqueous solution-gel precursor based on water soluble glycolato(-peroxo)-Ti(IV) complexes is developed for the preparation of TiO 2 films. With regard to the decomposition of complexes towards oxide formation, it is important to gain insight in the chemical transformations inside the precursor during thermal treatment. Therefore, the thermo-oxidative decomposition pathway of a gel obtained by slow evaporation of the precursor solution is described based on hyphenated thermogravimetric analysis with Fourier transform infrared spectroscopy (TGA-FTIR) and mass spectrometry (TGA-MS). Pure glycolic acid is used as a reference system for this study. By varying the molar glycolic acid to Ti(IV) ratio, the thermal decomposition of the gel can be drastically shortened and the profile's course changed. Gel structure and chemical changes in the gel upon heating are also studied by means of off-line FTIR. A unidentate coordination of the titanium(IV) ion by the carboxylate group of the glycolato ligands and the involvement of the hydroxyl group is confirmed. Phase formation at certain points in the thermal decomposition is studied by X-ray diffraction and Raman spectroscopy. Finally, it is proven that the new precursor is a valuable candidate for the deposition of low carbon containing solution-gel films which can ultimately be converted into smooth and uniform TiO 2 films.

A handbook of decomposition methods in analytical chemistry

International Nuclear Information System (INIS)

Bok, R.

1984-01-01

Decomposition methods of metals, alloys, fluxes, slags, calcine, inorganic salts, oxides, nitrides, carbides, borides, sulfides, ores, minerals, rocks, concentrates, glasses, ceramics, organic substances, polymers, phyto- and biological materials from the viewpoint of sample preparation for analysis have been described. The methods are systemitized according to decomposition principle: thermal with the use of electricity, irradiation, dissolution with participation of chemical reactions and without it. Special equipment for different decomposition methods is described. Bibliography contains 3420 references

Numerical soliton-like solutions of the potential Kadomtsev-Petviashvili equation by the decomposition method

International Nuclear Information System (INIS)

Kaya, Dogan; El-Sayed, Salah M.

2003-01-01

In this Letter we present an Adomian's decomposition method (shortly ADM) for obtaining the numerical soliton-like solutions of the potential Kadomtsev-Petviashvili (shortly PKP) equation. We will prove the convergence of the ADM. We obtain the exact and numerical solitary-wave solutions of the PKP equation for certain initial conditions. Then ADM yields the analytic approximate solution with fast convergence rate and high accuracy through previous works. The numerical solutions are compared with the known analytical solutions

Organoactinide chemistry: synthesis, structure, and solution dynamics

International Nuclear Information System (INIS)

Brennan, J.G.

1985-12-01

This thesis considers three aspects of organoactinide chemistry. In chapter one, a bidentate phosphine ligand was used to kinetically stabilize complexes of the type Cp 2 MX 2 . Ligand redistribution processes are present throughout the synthetic work, as has often been observed in uranium cyclopentadienyl chemistry. The effects of covalent M-L bonding on the solution and solid state properties of U(III) coordination complexes are considered. In particular, the nature of the more subtle interaction between the metal and the neutral ligand are examined. Using relative basicity data obtained in solution, and solid state structural data (and supplemented by gas phase photoelectron measurements), it is demonstrated that the more electron rich U(III) centers engage in significant U → L π-donation. Trivalent uranium is shown to be capable of acting either as a one- or two-electron reducing agent toward a wide variety of unsaturated organic and inorganic molecules, generating molecular classes unobtainable via traditional synthetic approaches, as well as offering an alternative synthetic approach to molecules accessible via metathesis reactions. Ligand redistribution processes are again observed, but given the information concerning ligand lability, this reactivity pattern is applied to the synthesis of pure materials inaccessible from redox chemistry. 214 refs., 33 figs., 10 tabs

Thermal decomposition and spectroscopic investigation of a new aqueous glycolato(-peroxo) Ti(IV) solution-gel precursor

Energy Technology Data Exchange (ETDEWEB)

De Dobbelaere, Christopher, E-mail: christopher.dedobbelaere@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Mullens, Jules, E-mail: jules.mullens@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Hardy, An, E-mail: an.hardy@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Van Bael, Marlies K., E-mail: marlies.vanbael@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium)

2011-06-10

Highlights: {yields} A totally water based glycolato-Ti(IV) precursor is presented and characterized. {yields} The precursors' thermal decomposition profile depends on the ligand to metal ratio. {yields} Titanium is coordinated in an unidentate fashion by the glycolate anion. {yields} Smooth and uniform TiO{sub 2} films can be prepared from the precursor solution. - Abstract: A new aqueous solution-gel precursor based on water soluble glycolato(-peroxo)-Ti(IV) complexes is developed for the preparation of TiO{sub 2} films. With regard to the decomposition of complexes towards oxide formation, it is important to gain insight in the chemical transformations inside the precursor during thermal treatment. Therefore, the thermo-oxidative decomposition pathway of a gel obtained by slow evaporation of the precursor solution is described based on hyphenated thermogravimetric analysis with Fourier transform infrared spectroscopy (TGA-FTIR) and mass spectrometry (TGA-MS). Pure glycolic acid is used as a reference system for this study. By varying the molar glycolic acid to Ti(IV) ratio, the thermal decomposition of the gel can be drastically shortened and the profile's course changed. Gel structure and chemical changes in the gel upon heating are also studied by means of off-line FTIR. A unidentate coordination of the titanium(IV) ion by the carboxylate group of the glycolato ligands and the involvement of the hydroxyl group is confirmed. Phase formation at certain points in the thermal decomposition is studied by X-ray diffraction and Raman spectroscopy. Finally, it is proven that the new precursor is a valuable candidate for the deposition of low carbon containing solution-gel films which can ultimately be converted into smooth and uniform TiO{sub 2} films.

Approximate rational Jacobi elliptic function solutions of the fractional differential equations via the enhanced Adomian decomposition method

International Nuclear Information System (INIS)

Song Lina; Wang Weiguo

2010-01-01

In this Letter, an enhanced Adomian decomposition method which introduces the h-curve of the homotopy analysis method into the standard Adomian decomposition method is proposed. Some examples prove that this method can derive successfully approximate rational Jacobi elliptic function solutions of the fractional differential equations.

Dense interstellar cloud chemistry: Basic issues and possible dynamical solution

International Nuclear Information System (INIS)

Prasad, S.S.; Heere, K.R.; Tarafdar, S.P.

1989-01-01

Standing at crossroad of enthusiasm and frustration, dense intertellar cloud chemistry has a squarely posed fundamental problem: Why do the grains appear to play at best a minor role in the chemistry? Grain surface chemistry creates considerable difficulties when the authors treat dense clouds as static objects and ignore the implications of the processes by which the clouds became dense in the first place. A new generation of models which treat chemical and dynamical evolutions concurrently are therefore presented as possible solution to the current frustrations. The proposed modeling philosophy and agenda could make the next decade quite exciting for interstellar chemistry

Decomposition of Sodium Tetraphenylborate

International Nuclear Information System (INIS)

Barnes, M.J.

1998-01-01

The chemical decomposition of aqueous alkaline solutions of sodium tetraphenylborate (NaTPB) has been investigated. The focus of the investigation is on the determination of additives and/or variables which influence NaTBP decomposition. This document describes work aimed at providing better understanding into the relationship of copper (II), solution temperature, and solution pH to NaTPB stability

Progress report 1981-1982. Reactor Chemistry Department

International Nuclear Information System (INIS)

1983-08-01

Review of the activities performed by the Reactor Chemistry Department of the National Atomic Energy Commission of Argentina during 1981-1982. This Department provides services and assistance in all matters related to water chemistry and nuclear reactors chemistry, in all their phases: design, construction, commissioning and decommissioning. During this period, the following tasks were performed: study of the metallic oxide-water interphases; determination of the goethite and magnetite surficial charges; synthesis of the monodispersed nickel ferrites; study of the iron oxides dissolution mechanism in presence of different complexing agents; chemical decontamination of structural metals; thermodynamics of the water-nitrogen system; physico-chemical studies of aqueous solutions at high temperatures; hydrothermal decomposition of ionic exchange resines and study of the equilibria of the anionic exchange for the chemistry of pressurized reactor's primary loops. The appendix includes information on the Reactor Chemistry Department staff, its publications, services, seminars, courses and conferences performed during 1981-1982. (R.J.S.) [es

Solution of the linearly anisotropic neutron transport problem in a infinite cylinder combining the decomposition and HTSN methods

International Nuclear Information System (INIS)

Goncalves, Glenio A.; Bodmann, Bardo; Bogado, Sergio; Vilhena, Marco T.

2008-01-01

Analytical solutions for neutron transport in cylindrical geometry is available for isotropic problems, but to the best of our knowledge for anisotropic problems are not available, yet. In this work, an analytical solution for the neutron transport equation in an infinite cylinder assuming anisotropic scattering is reported. Here we specialize the solution, without loss of generality, for the linearly anisotropic problem using the combined decomposition and HTS N methods. The key feature of this method consists in the application of the decomposition method to the anisotropic problem by virtue of the fact that the inverse of the operator associated to isotropic problem is well know and determined by the HTS N approach. So far, following the idea of the decomposition method, we apply this operator to the integral term, assuming that the angular flux appearing in the integrand is considered to be equal to the HTS N solution interpolated by polynomial considering only even powers. This leads to the first approximation for an anisotropic solution. Proceeding further, we replace this solution for the angular flux in the integral and apply again the inverse operator for the isotropic problem in the integral term and obtain a new approximation for the angular flux. This iterative procedure yields a closed form solution for the angular flux. This methodology can be generalized, in a straightforward manner, for transport problems with any degree of anisotropy. For the sake of illustration, we report numerical simulations for linearly anisotropic transport problems. (author)

Photochemical decomposition of catecholamines

International Nuclear Information System (INIS)

Mol, N.J. de; Henegouwen, G.M.J.B. van; Gerritsma, K.W.

1979-01-01

During photochemical decomposition (lambda=254 nm) adrenaline, isoprenaline and noradrenaline in aqueous solution were converted to the corresponding aminochrome for 65, 56 and 35% respectively. In determining this conversion, photochemical instability of the aminochromes was taken into account. Irradiations were performed in such dilute solutions that the neglect of the inner filter effect is permissible. Furthermore, quantum yields for the decomposition of the aminochromes in aqueous solution are given. (Author)

The aluminum chemistry and corrosion in alkaline solutions

International Nuclear Information System (INIS)

Zhang Jinsuo; Klasky, Marc; Letellier, Bruce C.

2009-01-01

Aluminum-alkaline solution systems are very common in engineering applications including nuclear engineering. Consequently, a thorough knowledge of the chemistry of aluminum and susceptibility to corrosion in alkaline solutions is reviewed. The aluminum corrosion mechanism and corrosion rate are examined based on current experimental data. A review of the phase transitions with aging time and change of environment is also performed. Particular attention is given to effect of organic and inorganic ions. As an example, the effect of boron is examined in detail because of the application in nuclear reactor power systems. Methods on how to reduce the corrosion rate of aluminum in alkaline solutions are also highlighted

Influence of drainage status on soil and water chemistry, litter decomposition and soil respiration in central Amazonian forests on sandy soils

Directory of Open Access Journals (Sweden)

Antônio Ocimar Manzi

2011-04-01

Full Text Available Central Amazonian rainforest landscape supports a mosaic of tall terra firme rainforest and ecotone campinarana, riparian and campina forests, reflecting topography-induced variations in soil, nutrient and drainage conditions. Spatial and temporal variations in litter decomposition, soil and groundwater chemistry and soil CO2 respiration were studied in forests on sandy soils, whereas drought sensitivity of poorly-drained valley soils was investigated in an artificial drainage experiment. Slightly changes in litter decomposition or water chemistry were observed as a consequence of artificial drainage. Riparian plots did experience higher litter decomposition rates than campina forest. In response to a permanent lowering of the groundwater level from 0.1 m to 0.3 m depth in the drainage plot, topsoil carbon and nitrogen contents decreased substantially. Soil CO2 respiration decreased from 3.7±0.6 µmol m-2 s-1 before drainage to 2.5±0.2 and 0.8±0.1 µmol m-2 s-1 eight and 11 months after drainage, respectively. Soil respiration in the control plot remained constant at 3.7±0.6 µmol m-2 s-1. The above suggests that more frequent droughts may affect topsoil carbon and nitrogen content and soil respiration rates in the riparian ecosystem, and may induce a transition to less diverse campinarana or short-statured campina forest that covers areas with strongly-leached sandy soil.

Periodic oscillatory solution in delayed competitive-cooperative neural networks: A decomposition approach

International Nuclear Information System (INIS)

Yuan Kun; Cao Jinde

2006-01-01

In this paper, the problems of exponential convergence and the exponential stability of the periodic solution for a general class of non-autonomous competitive-cooperative neural networks are analyzed via the decomposition approach. The idea is to divide the connection weights into inhibitory or excitatory types and thereby to embed a competitive-cooperative delayed neural network into an augmented cooperative delay system through a symmetric transformation. Some simple necessary and sufficient conditions are derived to ensure the componentwise exponential convergence and the exponential stability of the periodic solution of the considered neural networks. These results generalize and improve the previous works, and they are easy to check and apply in practice

Desorption of 1,3,5-Trichlorobenzene from Multi-Walled Carbon Nanotubes: Impact of Solution Chemistry and Surface Chemistry

Directory of Open Access Journals (Sweden)

Sheikh Uddin

2013-05-01

Full Text Available The strong affinity of carbon nanotubes (CNTs to environmental contaminants has raised serious concern that CNTs may function as a carrier of environmental pollutants and lead to contamination in places where the environmental pollutants are not expected. However, this concern will not be realized until the contaminants are desorbed from CNTs. It is well recognized that the desorption of environmental pollutants from pre-laden CNTs varies with the environmental conditions, such as the solution pH and ionic strength. However, comprehensive investigation on the influence of solution chemistry on the desorption process has not been carried out, even though numerous investigations have been conducted to investigate the impact of solution chemistry on the adsorption of environmental pollutants on CNTs. The main objective of this study was to determine the influence of solution chemistry (e.g., pH, ionic strength and surface functionalization on the desorption of preloaded 1,3,5-trichlorobenzene (1,3,5-TCB from multi-walled carbon nanotubes (MWNTs. The results suggested that higher pH, ionic strength and natural organic matter in solution generally led to higher desorption of 1,3,5-TCB from MWNTs. However, the extent of change varied at different values of the tested parameters (e.g., pH 7. In addition, the impact of these parameters varied with MWNTs possessing different surface functional groups, suggesting that surface functionalization could considerably alter the environmental behaviors and impact of MWNTs.

The chemistry of nonaqueous solvents v.4 solution phenomena and aprotic solvents

CERN Document Server

Lagowski, J J

1976-01-01

The Chemistry of Nonaqueous Solvents, Volume IV: Solution Phenomena and Aprotic Solvents focuses on the chemistry of nonaqueous solvents, with emphasis on solution phenomena and aprotic solvents such as tetramethylurea, inorganic acid chlorides, cyclic carbonates, and sulfolane. This book is organized into seven chapters and begins with an overview of the theory of electrical conductivity and elementary experimental considerations, along with some of the interesting research on nonaqueous solvents. It then turns to a discussion on hydrogen bonding phenomena in nonaqueous systems as probed

Approximate Analytical Solutions for Mathematical Model of Tumour Invasion and Metastasis Using Modified Adomian Decomposition and Homotopy Perturbation Methods

Directory of Open Access Journals (Sweden)

Norhasimah Mahiddin

2014-01-01

Full Text Available The modified decomposition method (MDM and homotopy perturbation method (HPM are applied to obtain the approximate solution of the nonlinear model of tumour invasion and metastasis. The study highlights the significant features of the employed methods and their ability to handle nonlinear partial differential equations. The methods do not need linearization and weak nonlinearity assumptions. Although the main difference between MDM and Adomian decomposition method (ADM is a slight variation in the definition of the initial condition, modification eliminates massive computation work. The approximate analytical solution obtained by MDM logically contains the solution obtained by HPM. It shows that HPM does not involve the Adomian polynomials when dealing with nonlinear problems.

Dechlorination and decomposition of chloroform induced by glow discharge plasma in an aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Liu, Yongjun, E-mail: lyjglow@sohu.com [College of Environmental Science & Engineering, Dalian Maritime University, Dalian 116026 (China); Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta 30332 (United States); Crittenden, John C. [Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta 30332 (United States); Wang, Lei [College of Environmental Science & Engineering, Xiamen University of Technology, Xiamen 361024 (China); Liu, Panliang [Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta 30332 (United States)

2016-05-05

Highlights: • Hydrated electrons played an important role for chloroform decomposition. • Oxygen enhanced hydrolyses are critical for the chloroform mineralization. • Energy efficiency of GDP is higher than those of the typical competitive processes. - Abstract: In this study, efficient dechlorination and decomposition of chloroform (CF) induced by glow discharge plasma (GDP) in contact with a sodium sulfate solution was investigated. Intermediate byproducts were determined by ionic chromatography and headspace gas chromatography, respectively. Results showed that CF can be effectively dechlorinated and decomposed under the action of GDP. Both removal and dechlorination of CF increased with increasing pH and with addition of hydroxyl radical scavengers to the solution. Addition of H{sub 2}O{sub 2} to the solution slightly decreased the CF removal. Formic acid, oxalic acid and dichloromethane were determined as the major intermediate byproducts. Final products were carbon dioxide and hydrochloric acid. Hydrated electrons were the most likely active species responsible for initiation of the dechlorination, and hydroxyl radicals may be the ones for the oxidation of the organic intermediate byproducts. Hydrolyses of the chloromethyl radicals contributed much in the mineralization of the organic chlorine. Reaction mechanism was proposed based on the dechlorination kinetics and the distribution of intermediate byproducts.

Dechlorination and decomposition of chloroform induced by glow discharge plasma in an aqueous solution

International Nuclear Information System (INIS)

Liu, Yongjun; Crittenden, John C.; Wang, Lei; Liu, Panliang

2016-01-01

Highlights: • Hydrated electrons played an important role for chloroform decomposition. • Oxygen enhanced hydrolyses are critical for the chloroform mineralization. • Energy efficiency of GDP is higher than those of the typical competitive processes. - Abstract: In this study, efficient dechlorination and decomposition of chloroform (CF) induced by glow discharge plasma (GDP) in contact with a sodium sulfate solution was investigated. Intermediate byproducts were determined by ionic chromatography and headspace gas chromatography, respectively. Results showed that CF can be effectively dechlorinated and decomposed under the action of GDP. Both removal and dechlorination of CF increased with increasing pH and with addition of hydroxyl radical scavengers to the solution. Addition of H_2O_2 to the solution slightly decreased the CF removal. Formic acid, oxalic acid and dichloromethane were determined as the major intermediate byproducts. Final products were carbon dioxide and hydrochloric acid. Hydrated electrons were the most likely active species responsible for initiation of the dechlorination, and hydroxyl radicals may be the ones for the oxidation of the organic intermediate byproducts. Hydrolyses of the chloromethyl radicals contributed much in the mineralization of the organic chlorine. Reaction mechanism was proposed based on the dechlorination kinetics and the distribution of intermediate byproducts.

Specific features of concentrated phase under decomposition of weak solid /sup 3/He-/sup 4/He solution

Energy Technology Data Exchange (ETDEWEB)

Mikheev, V A; Majdamov, V A; Kal' noj, S E; Omelaenko, N I

1988-06-01

The decomposition of solid /sup 3/He-/sup 4/He solutuions is studied on the samples 0.54% /sup 3/He(V=20.55 cm/sup 3//mole) and 0.60% /sup 4/He (V=24.04-24.93 cm/sup 3//mole) using pulse NMR method. At T=100 mK the decomposition of a weak solution proceeds more than for 30 h, the decomposition rate and temperature being dependent on the sample prehistory. In the concentrated phase of the decomposed weak solution the spin diffraction of /sup 3/He is of the quasi-one-dimensional character with the diffusion coefficient D /similar to/ 10/sup -5/ cm/sup 2//sec typical of liquid /sup 3/He and exceeding that bulk solid /sup 3/He by two orders of magnitude. The longitudinal relaxation time in the quasi-one-dimensional phase (/similar to/ 1 sec) is characteristic of the solid state and coinsides with data for bulk /sup 3/He. The temperature behaviour of magnetization in the quasi-one-dimensional phase is well described by the Curie law.

Photochemical decomposition of Formaldehyde in solution.; Descomposicion fotoquimica de formaldehido en solucion.

Energy Technology Data Exchange (ETDEWEB)

Garrido Z, G

1995-10-01

In this work was studied the effect of ultraviolet radiation produced by a mercury low pressure lamp in solutions of formaldehyde. These solutions were exposed to ultraviolet rays at different times. In some of these series of solutions was added a photosensibilizer in order to obtain a high photodecomposition of formaldehyde. The techniques used for determine the products of the decomposition were the following: 1. In order to measure the residual formaldehyde and glioxal, the Hantzsch and 2,4-dinitrophenylhydrazine methods were used. 2. pH`s measurements of the solutions, before and after exposition. 3. Paper`s chromatography for determine presence of formed acids. 4. Acid-base tritiations for measure total acidification. We observed that when the time of exposition to UV rays was increased, a high photodecomposition of formaldehyde was formed and, besides, a greater quantity of another products. Of the reagents used like photosensibilizers, with the ruthenium reagent, the best results were obtained. (Author).

Pre-Service Chemistry Teachers' Competencies in the Laboratory: A Cross-Grade Study in Solution Preparation

Science.gov (United States)

Karatas, F. O.

2016-01-01

One of the prerequisites for chemistry teacher candidates is to demonstrate certain laboratory skills. This article aims to determine and discuss the competencies of pre-service chemistry teachers in a chemistry laboratory context working with solution chemistry content. The participants in this study consisted of a group of pre-service chemistry…

A review of plutonium oxalate decomposition reactions and effects of decomposition temperature on the surface area of the plutonium dioxide product

International Nuclear Information System (INIS)

Orr, R.M.; Sims, H.E.; Taylor, R.J.

2015-01-01

Plutonium (IV) and (III) ions in nitric acid solution readily form insoluble precipitates with oxalic acid. The plutonium oxalates are then easily thermally decomposed to form plutonium dioxide powder. This simple process forms the basis of current industrial conversion or ‘finishing’ processes that are used in commercial scale reprocessing plants. It is also widely used in analytical or laboratory scale operations and for waste residues treatment. However, the mechanisms of the thermal decompositions in both air and inert atmospheres have been the subject of various studies over several decades. The nature of intermediate phases is of fundamental interest whilst understanding the evolution of gases at different temperatures is relevant to process control. The thermal decomposition is also used to control a number of powder properties of the PuO_2 product that are important to either long term storage or mixed oxide fuel manufacturing. These properties are the surface area, residual carbon impurities and adsorbed volatile species whereas the morphology and particle size distribution are functions of the precipitation process. Available data and experience regarding the thermal and radiation-induced decompositions of plutonium oxalate to oxide are reviewed. The mechanisms of the thermal decompositions are considered with a particular focus on the likely redox chemistry involved. Also, whilst it is well known that the surface area is dependent on calcination temperature, there is a wide variation in the published data and so new correlations have been derived. Better understanding of plutonium (III) and (IV) oxalate decompositions will assist the development of more proliferation resistant actinide co-conversion processes that are needed for advanced reprocessing in future closed nuclear fuel cycles. - Highlights: • Critical review of plutonium oxalate decomposition reactions. • New analysis of relationship between SSA and calcination temperature. • New SEM

Effects of stream water chemistry and tree species on release and methylation of mercury during litter decomposition.

Science.gov (United States)

Tsui, Martin Tsz Ki; Finlay, Jacques C; Nater, Edward A

2008-12-01

Foliage of terrestrial plants provides an important energy and nutrient source to aquatic ecosystems but also represents a potential source of contaminants, such as mercury (Hg). In this study, we examined how different stream water types and terrestrial tree species influenced the release of Hg from senesced litter to the water and its subsequent methylation during hypoxic litter decomposition. After laboratory incubations of maple leaf litter for 66 days, we observed 10-fold differences in dissolved Hg (DHg, tree species collected at the same site and incubated with the same source water, litter from slower decomposing species (e.g., cedar and pine) yielded higher DHg concentrations than those with more labile carbon (e.g., maple and birch). Percent MeHg, however, was relatively similar among different leaf species (i.e., 61-86%). Our study is the first to demonstrate that stream water chemistry and terrestrial plant litter characteristics are important factors determining Hg release and methylation during hypoxic litter decomposition. These results suggest that certain watershed and aquatic ecosystem properties can determine the levels of MeHg inputs during litterfall events.

Fluctuation theory of solutions applications in chemistry, chemical engineering, and biophysics

CERN Document Server

Smith, Paul E

2013-01-01

There are essentially two theories of solutions that can be considered exact: the McMillan-Mayer theory and Fluctuation Solution Theory (FST). The first is mostly limited to solutes at low concentrations, while FST has no such issue. It is an exact theory that can be applied to any stable solution regardless of the number of components and their concentrations, and the types of molecules and their sizes. Fluctuation Theory of Solutions: Applications in Chemistry, Chemical Engineering, and Biophysics outlines the general concepts and theoretical basis of FST and provides a range of applications

Semi-exact solution of elastic non-uniform thickness and density rotating disks by homotopy perturbation and Adomian's decomposition methods. Part I: Elastic solution

International Nuclear Information System (INIS)

Hojjati, M.H.; Jafari, S.

2008-01-01

In this work, two powerful analytical methods, namely homotopy perturbation method (HPM) and Adomian's decomposition method (ADM), are introduced to obtain distributions of stresses and displacements in rotating annular elastic disks with uniform and variable thicknesses and densities. The results obtained by these methods are then compared with the verified variational iteration method (VIM) solution. He's homotopy perturbation method which does not require a 'small parameter' has been used and a homotopy with an imbedding parameter p element of [0,1] is constructed. The method takes the full advantage of the traditional perturbation methods and the homotopy techniques and yields a very rapid convergence of the solution. Adomian's decomposition method is an iterative method which provides analytical approximate solutions in the form of an infinite power series for nonlinear equations without linearization, perturbation or discretization. Variational iteration method, on the other hand, is based on the incorporation of a general Lagrange multiplier in the construction of correction functional for the equation. This study demonstrates the ability of the methods for the solution of those complicated rotating disk cases with either no or difficult to find fairly exact solutions without the need to use commercial finite element analysis software. The comparison among these methods shows that although the numerical results are almost the same, HPM is much easier, more convenient and efficient than ADM and VIM

The Enthalpy of Decomposition of Hydrogen Peroxide: A General Chemistry Calorimetry Experiment

Science.gov (United States)

Marzzacco, Charles J.

1999-11-01

A calorimetry experiment involving the catalytic decomposition of aqueous hydrogen peroxide is presented. The experiment is simple, inexpensive, and colorful. In its simplest form, it can be performed in less than one hour; therefore, it is quite suitable for high school labs, which often have time restrictions. The chemicals required are household or commercial 3% H2O2(aq) and 0.50 M Fe(NO3)3(aq). Styrofoam cup calorimeters and thermometers with a range from 20 to 50 oC are also required. Ideally, the thermometers should be precise to 0.01 oC. The temperature of the H2O2 solution is monitored before and after the Fe(NO3)3 catalyst is added. The addition of the catalyst results in a color change and the evolution of heat and bubbles of oxygen. At the conclusion of the reaction, the color of the reaction mixture returns to that of the original Fe(NO3)3 solution. The heat change for the reaction is determined from the temperature change, the specific heat of the solution, and the calorimeter constant. The experimental enthalpy change for the reaction is in excellent agreement with the literature value.

FURFURAL YIELD AND DECOMPOSITION IN SODIUM 2,4DIMETHYLBENZENESULFONATE--SULFURIC ACID--WATER SOLUTIONS.

Science.gov (United States)

Batch-type microreactors (about 1/40 milliliter of reactants) were used to measure furfural yields from acidified xylose solutions containing sodium...It was found that presence of the salt did not affect the quantity of furfural produced, but greatly increased the rate of formation. The regular...increase in rate of furfural formation was directly related to the increase in the rate xylose decomposition, and furfural yields for all salt and acid

Solution of the neutron transport problem with anisotropic scattering in cylindrical geometry by the decomposition method

International Nuclear Information System (INIS)

Goncalves, G.A.; Bogado Leite, S.Q.; Vilhena, M.T. de

2009-01-01

An analytical solution has been obtained for the one-speed stationary neutron transport problem, in an infinitely long cylinder with anisotropic scattering by the decomposition method. Series expansions of the angular flux distribution are proposed in terms of suitably constructed functions, recursively obtainable from the isotropic solution, to take into account anisotropy. As for the isotropic problem, an accurate closed-form solution was chosen for the problem with internal source and constant incident radiation, obtained from an integral transformation technique and the F N method

Solution of the isotopic depletion equation using decomposition method and analytical solution

Energy Technology Data Exchange (ETDEWEB)

Prata, Fabiano S.; Silva, Fernando C.; Martinez, Aquilino S., E-mail: fprata@con.ufrj.br, E-mail: fernando@con.ufrj.br, E-mail: aquilino@lmp.ufrj.br [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear

2011-07-01

In this paper an analytical calculation of the isotopic depletion equations is proposed, featuring a chain of major isotopes found in a typical PWR reactor. Part of this chain allows feedback reactions of (n,2n) type. The method is based on decoupling the equations describing feedback from the rest of the chain by using the decomposition method, with analytical solutions for the other isotopes present in the chain. The method was implemented in a PWR reactor simulation code, that makes use of the nodal expansion method (NEM) to solve the neutron diffusion equation, describing the spatial distribution of neutron flux inside the reactor core. Because isotopic depletion calculation module is the most computationally intensive process within simulation systems of nuclear reactor core, it is justified to look for a method that is both efficient and fast, with the objective of evaluating a larger number of core configurations in a short amount of time. (author)

Solution of the isotopic depletion equation using decomposition method and analytical solution

International Nuclear Information System (INIS)

Prata, Fabiano S.; Silva, Fernando C.; Martinez, Aquilino S.

2011-01-01

In this paper an analytical calculation of the isotopic depletion equations is proposed, featuring a chain of major isotopes found in a typical PWR reactor. Part of this chain allows feedback reactions of (n,2n) type. The method is based on decoupling the equations describing feedback from the rest of the chain by using the decomposition method, with analytical solutions for the other isotopes present in the chain. The method was implemented in a PWR reactor simulation code, that makes use of the nodal expansion method (NEM) to solve the neutron diffusion equation, describing the spatial distribution of neutron flux inside the reactor core. Because isotopic depletion calculation module is the most computationally intensive process within simulation systems of nuclear reactor core, it is justified to look for a method that is both efficient and fast, with the objective of evaluating a larger number of core configurations in a short amount of time. (author)

Detailed Chemical Kinetic Modeling of Hydrazine Decomposition

Science.gov (United States)

Meagher, Nancy E.; Bates, Kami R.

2000-01-01

The purpose of this research project is to develop and validate a detailed chemical kinetic mechanism for gas-phase hydrazine decomposition. Hydrazine is used extensively in aerospace propulsion, and although liquid hydrazine is not considered detonable, many fuel handling systems create multiphase mixtures of fuels and fuel vapors during their operation. Therefore, a thorough knowledge of the decomposition chemistry of hydrazine under a variety of conditions can be of value in assessing potential operational hazards in hydrazine fuel systems. To gain such knowledge, a reasonable starting point is the development and validation of a detailed chemical kinetic mechanism for gas-phase hydrazine decomposition. A reasonably complete mechanism was published in 1996, however, many of the elementary steps included had outdated rate expressions and a thorough investigation of the behavior of the mechanism under a variety of conditions was not presented. The current work has included substantial revision of the previously published mechanism, along with a more extensive examination of the decomposition behavior of hydrazine. An attempt to validate the mechanism against the limited experimental data available has been made and was moderately successful. Further computational and experimental research into the chemistry of this fuel needs to be completed.

Decoupling the direct and indirect effects of climate on plant litter decomposition: Accounting for stress-induced modifications in plant chemistry.

Science.gov (United States)

Suseela, Vidya; Tharayil, Nishanth

2018-04-01

with temperate ecosystems, the indirect effects of climate on litter decomposition in the tropics are not well understood, which underscores the need to conduct additional studies in tropical biomes. We also emphasize the need to focus on how climatic stress affects the root chemistry as roots contribute significantly to biogeochemical cycling, and on utilizing more robust analytical approaches to capture the molecular composition of tissue matrix that fuel microbial metabolism. © 2017 John Wiley & Sons Ltd.

Systems-based decomposition schemes for the approximate solution of multi-term fractional differential equations

Science.gov (United States)

Ford, Neville J.; Connolly, Joseph A.

2009-07-01

We give a comparison of the efficiency of three alternative decomposition schemes for the approximate solution of multi-term fractional differential equations using the Caputo form of the fractional derivative. The schemes we compare are based on conversion of the original problem into a system of equations. We review alternative approaches and consider how the most appropriate numerical scheme may be chosen to solve a particular equation.

Advanced studies in chemistry control with morpholine

International Nuclear Information System (INIS)

Riddle, J.M.

1992-07-01

Prior studies at Beaver Valley Unit 1 and at Prairie Island found that the substitution of morpholine for ammonia reduced corrosion and iron transport in the feedtrain of pressurized water reactors. The benefits of using morpholine encouraged other utilities to consider morpholine water chemistry. Calvert Cliffs Unit 1 was the first domestic PWR with deep-bed condensate polishers to use morpholine water chemistry. Typically a bed is operated in the hydrogen cycle for eight to ten days, followed by an additional 25 days in the morpholine cycle. Morpholine reduced feedwater iron levels by 28 percent. With morpholine treatment at Calvert Cliffs Unit 1, corrosion product transport in feedwater was reduced by a factor of 1.3 -- 1.4. Morpholine treatment at higher levels at Prairie Island Unit 2 provided a factor of 2.3 reduction in feedwater iron transport, in agreement with data from Electricity de France. EdF data show that the factor increases as the pH for ammonia chemistry is reduced from 9.5. When possible, the factors were compared at a pH of 9.2 for morpholine at room temperature. Aqueous solutions of morpholine thermally decompose at increasing rates with temperature above about 288 degree C (550 degree F). Oxygen and several metal oxides appear to increase the rate of decomposition to a small extent. Acetate, formate, and various amines, including ammonia, are the principal decomposition products

A review of plutonium oxalate decomposition reactions and effects of decomposition temperature on the surface area of the plutonium dioxide product

Science.gov (United States)

Orr, R. M.; Sims, H. E.; Taylor, R. J.

2015-10-01

Plutonium (IV) and (III) ions in nitric acid solution readily form insoluble precipitates with oxalic acid. The plutonium oxalates are then easily thermally decomposed to form plutonium dioxide powder. This simple process forms the basis of current industrial conversion or 'finishing' processes that are used in commercial scale reprocessing plants. It is also widely used in analytical or laboratory scale operations and for waste residues treatment. However, the mechanisms of the thermal decompositions in both air and inert atmospheres have been the subject of various studies over several decades. The nature of intermediate phases is of fundamental interest whilst understanding the evolution of gases at different temperatures is relevant to process control. The thermal decomposition is also used to control a number of powder properties of the PuO2 product that are important to either long term storage or mixed oxide fuel manufacturing. These properties are the surface area, residual carbon impurities and adsorbed volatile species whereas the morphology and particle size distribution are functions of the precipitation process. Available data and experience regarding the thermal and radiation-induced decompositions of plutonium oxalate to oxide are reviewed. The mechanisms of the thermal decompositions are considered with a particular focus on the likely redox chemistry involved. Also, whilst it is well known that the surface area is dependent on calcination temperature, there is a wide variation in the published data and so new correlations have been derived. Better understanding of plutonium (III) and (IV) oxalate decompositions will assist the development of more proliferation resistant actinide co-conversion processes that are needed for advanced reprocessing in future closed nuclear fuel cycles.

Chemistry in high temperature aqueous solutions application to the power industry

International Nuclear Information System (INIS)

Cohen, P.

1990-01-01

The power industry utilizes water (aqueous solutions) for two main functions: as a medium for heat transfer and transport and as a thermodynamic working fluid. These functions are performed in systems fabricated from a wide variety of materials, over a wide range of thermal and hydraulic conditions, and at medium temperatures and densities which determine the significant chemical properties. The major chemical interest is in the concentrated solutions derived from the dilute working fluid at selected sites defined by the physical arrangement and temperature and in their consequential effects on heat transfer and corrosion. Examples of these sites for typical fossil fired and nuclear steam generating equipment are described, as well as the extent and limit of the concentration process. The history of steam power plant water chemistry is discussed from the point of view of the chemical processes involved. The period covered is from the 1920s to the present state of the art, which is a major application of the subject of this symposium--chemistry in high temperature aqueous solution

A review of plutonium oxalate decomposition reactions and effects of decomposition temperature on the surface area of the plutonium dioxide product

Energy Technology Data Exchange (ETDEWEB)

Orr, R.M.; Sims, H.E.; Taylor, R.J., E-mail: robin.j.taylor@nnl.co.uk

2015-10-15

Plutonium (IV) and (III) ions in nitric acid solution readily form insoluble precipitates with oxalic acid. The plutonium oxalates are then easily thermally decomposed to form plutonium dioxide powder. This simple process forms the basis of current industrial conversion or ‘finishing’ processes that are used in commercial scale reprocessing plants. It is also widely used in analytical or laboratory scale operations and for waste residues treatment. However, the mechanisms of the thermal decompositions in both air and inert atmospheres have been the subject of various studies over several decades. The nature of intermediate phases is of fundamental interest whilst understanding the evolution of gases at different temperatures is relevant to process control. The thermal decomposition is also used to control a number of powder properties of the PuO{sub 2} product that are important to either long term storage or mixed oxide fuel manufacturing. These properties are the surface area, residual carbon impurities and adsorbed volatile species whereas the morphology and particle size distribution are functions of the precipitation process. Available data and experience regarding the thermal and radiation-induced decompositions of plutonium oxalate to oxide are reviewed. The mechanisms of the thermal decompositions are considered with a particular focus on the likely redox chemistry involved. Also, whilst it is well known that the surface area is dependent on calcination temperature, there is a wide variation in the published data and so new correlations have been derived. Better understanding of plutonium (III) and (IV) oxalate decompositions will assist the development of more proliferation resistant actinide co-conversion processes that are needed for advanced reprocessing in future closed nuclear fuel cycles. - Highlights: • Critical review of plutonium oxalate decomposition reactions. • New analysis of relationship between SSA and calcination temperature. �

Approximate Analytic Solutions for the Two-Phase Stefan Problem Using the Adomian Decomposition Method

Directory of Open Access Journals (Sweden)

Xiao-Ying Qin

2014-01-01

Full Text Available An Adomian decomposition method (ADM is applied to solve a two-phase Stefan problem that describes the pure metal solidification process. In contrast to traditional analytical methods, ADM avoids complex mathematical derivations and does not require coordinate transformation for elimination of the unknown moving boundary. Based on polynomial approximations for some known and unknown boundary functions, approximate analytic solutions for the model with undetermined coefficients are obtained using ADM. Substitution of these expressions into other equations and boundary conditions of the model generates some function identities with the undetermined coefficients. By determining these coefficients, approximate analytic solutions for the model are obtained. A concrete example of the solution shows that this method can easily be implemented in MATLAB and has a fast convergence rate. This is an efficient method for finding approximate analytic solutions for the Stefan and the inverse Stefan problems.

Singular solution of the Feller diffusion equation via a spectral decomposition

Science.gov (United States)

Gan, Xinjun; Waxman, David

2015-01-01

Feller studied a branching process and found that the distribution for this process approximately obeys a diffusion equation [W. Feller, in Proceedings of the Second Berkeley Symposium on Mathematical Statistics and Probability (University of California Press, Berkeley and Los Angeles, 1951), pp. 227-246]. This diffusion equation and its generalizations play an important role in many scientific problems, including, physics, biology, finance, and probability theory. We work under the assumption that the fundamental solution represents a probability density and should account for all of the probability in the problem. Thus, under the circumstances where the random process can be irreversibly absorbed at the boundary, this should lead to the presence of a Dirac delta function in the fundamental solution at the boundary. However, such a feature is not present in the standard approach (Laplace transformation). Here we require that the total integrated probability is conserved. This yields a fundamental solution which, when appropriate, contains a term proportional to a Dirac delta function at the boundary. We determine the fundamental solution directly from the diffusion equation via spectral decomposition. We obtain exact expressions for the eigenfunctions, and when the fundamental solution contains a Dirac delta function at the boundary, every eigenfunction of the forward diffusion operator contains a delta function. We show how these combine to produce a weight of the delta function at the boundary which ensures the total integrated probability is conserved. The solution we present covers cases where parameters are time dependent, thereby greatly extending its applicability.

Kinetics of Platinum-Catalyzed Decomposition of Hydrogen Peroxide

Science.gov (United States)

Vetter, Tiffany A.; Colombo, D. Philip, Jr.

2003-07-01

CIBA Vision Corporation markets a contact lens cleaning system that consists of an AOSEPT disinfectant solution and an AOSEPT lens cup. The disinfectant is a buffered 3.0% m/v hydrogen peroxide solution and the cup includes a platinum-coated AOSEPT disc. The hydrogen peroxide disinfects by killing bacteria, fungi, and viruses found on the contact lenses. Because the concentration of hydrogen peroxide needed to disinfect is irritating to eyes, the hydrogen peroxide needs to be neutralized, or decomposed, before the contact lenses can be used again. A general chemistry experiment is described where the kinetics of the catalyzed decomposition of the hydrogen peroxide are studied by measuring the amount of oxygen generated as a function of time. The order of the reaction with respect to the hydrogen peroxide, the rate constant, and the energy of activation are determined. The integrated rate law is used to determine the time required to decompose the hydrogen peroxide to a concentration that is safe for eyes.

Total Decomposition of Environmental Radionuclide Samples with a Microwave Oven

International Nuclear Information System (INIS)

Ramon Garcia, Bernd Kahn

1998-01-01

Closed-vessel microwave assisted acid decomposition was investigated as an alternative to traditional methods of sample dissolution/decomposition. This technique, used in analytical chemistry, has some potential advantages over other procedures. It requires less reagents, it is faster, and it has the potential of achieving total dissolution because of higher temperatures and pressures

The radiation chemistry of aqueous sodium terephthalate solutions

International Nuclear Information System (INIS)

Matthews, R.W.

1980-04-01

The radiation chemistry of cobalt-60 gamma-irradiated aqueous sodium terephthalate solutions has been studied. In aerated 4 x 10 -4 M sodium hydroxide solutions, the main products are hydroxyterephthalate (HTA) (G = 0.99 +- 0.01), carbonate (G = 1.31 +- 0.08), and peroxides (G = 2.84 +- 0.04). The HTA and carbonate species are both formed as a result of hydroxyl radical attack and account for approximately 90 per cent of hydroxyl radical reactions. Oxygen needs to be present for efficient conversion of the terephthalate-OH radical adduct to HTA and oxygenation increases G(HTA) above the aerated solution value. G(HTA) is unaffected by changes in terephthalate concentration between 1 x 10 -4 M and 1 x 10 -2 M in sodium hydroxide solutions at pH 10. Decreasing the solution pH does however affect G(HTA). In phosphate buffered solutions pH 6.85, G(HTA) is 0.93 +- 0.01 and lower values are obtained with further decrease in solution pH. The lowering of the G(HTA) value is attributed to recombination reactions between the terephthalate-OH radical products and reducing radical products. Experimental evidence supporting the recombination postulate was obtained from the measurement of a parallel decrease in the peroxide yield and the observation of a dose rate effect on G(HTA). Competition kinetic studies with the added solutes carbonate and bicarbonate gave the rate ratios k (OH + TA 2- ) : k(OH + CO 3 2- ) : k(OH + HCO 3 - ) = 1 : 0.105 : 0.0036

Infrared multiphoton absorption and decomposition

International Nuclear Information System (INIS)

Evans, D.K.; McAlpine, R.D.

1984-01-01

The discovery of infrared laser induced multiphoton absorption (IRMPA) and decomposition (IRMPD) by Isenor and Richardson in 1971 generated a great deal of interest in these phenomena. This interest was increased with the discovery by Ambartzumian, Letokhov, Ryadbov and Chekalin that isotopically selective IRMPD was possible. One of the first speculations about these phenomena was that it might be possible to excite a particular mode of a molecule with the intense infrared laser beam and cause decomposition or chemical reaction by channels which do not predominate thermally, thus providing new synthetic routes for complex chemicals. The potential applications to isotope separation and novel chemistry stimulated efforts to understand the underlying physics and chemistry of these processes. At ICOMP I, in 1977 and at ICOMP II in 1980, several authors reviewed the current understandings of IRMPA and IRMPD as well as the particular aspect of isotope separation. There continues to be a great deal of effort into understanding IRMPA and IRMPD and we will briefly review some aspects of these efforts with particular emphasis on progress since ICOMP II. 31 references

Impacts of operating conditions and solution chemistry on osmotic membrane structure and performance

KAUST Repository

Wong, Mavis C.Y.; Martinez, Kristina; Ramon, Guy Z.; Hoek, Eric M.V.

2012-01-01

Herein, we report on changes in the performance of a commercial cellulose triacetate (CTA) membrane, imparted by varied operating conditions and solution chemistries. Changes to feed and draw solution flow rate did not significantly alter the CTA membrane's water permeability, salt permeability, or membrane structural parameter when operated with the membrane skin layer facing the draw solution (PRO-mode). However, water and salt permeability increased with increasing feed or draw solution temperature, while the membrane structural parameter decreased with increasing draw solution, possibly due to changes in polymer intermolecular interactions. High ionic strength draw solutions may de-swell the CTA membrane via charge neutralization, which resulted in lower water permeability, higher salt permeability, and lower structural parameter. This observed trend was further exacerbated by the presence of divalent cations which tends to swell the polymer to a greater extent. Finally, the calculated CTA membrane's structural parameter was lower and less sensitive to external factors when operated in PRO-mode, but highly sensitive to the same factors when the skin layer faced the feed solution (FO-mode), presumably due to swelling/de-swelling of the saturated porous substructure by the draw solution. This is a first attempt aimed at systematically evaluating the changes in performance of the CTA membrane due to operating conditions and solution chemistry, shedding new insight into the possible advantages and disadvantages of this material in certain applications. © 2011 Elsevier B.V.

Impacts of operating conditions and solution chemistry on osmotic membrane structure and performance

KAUST Repository

Wong, Mavis C.Y.

2012-02-01

Herein, we report on changes in the performance of a commercial cellulose triacetate (CTA) membrane, imparted by varied operating conditions and solution chemistries. Changes to feed and draw solution flow rate did not significantly alter the CTA membrane\\'s water permeability, salt permeability, or membrane structural parameter when operated with the membrane skin layer facing the draw solution (PRO-mode). However, water and salt permeability increased with increasing feed or draw solution temperature, while the membrane structural parameter decreased with increasing draw solution, possibly due to changes in polymer intermolecular interactions. High ionic strength draw solutions may de-swell the CTA membrane via charge neutralization, which resulted in lower water permeability, higher salt permeability, and lower structural parameter. This observed trend was further exacerbated by the presence of divalent cations which tends to swell the polymer to a greater extent. Finally, the calculated CTA membrane\\'s structural parameter was lower and less sensitive to external factors when operated in PRO-mode, but highly sensitive to the same factors when the skin layer faced the feed solution (FO-mode), presumably due to swelling/de-swelling of the saturated porous substructure by the draw solution. This is a first attempt aimed at systematically evaluating the changes in performance of the CTA membrane due to operating conditions and solution chemistry, shedding new insight into the possible advantages and disadvantages of this material in certain applications. © 2011 Elsevier B.V.

Radiolytic decomposition of 4-bromodiphenyl ether

International Nuclear Information System (INIS)

Tang Liang; Xu Gang; Wu Wenjing; Shi Wenyan; Liu Ning; Bai Yulei; Wu Minghong

2010-01-01

Polybrominated diphenyl ethers (PBDEs) spread widely in the environment are mainly removed by photochemical and anaerobic microbial degradation. In this paper, the decomposition of 4-bromodiphenyl ether (BDE -3), the PBDEs homologues, is investigated by electron beam irradiation of its ethanol/water solution (reduction system) and acetonitrile/water solution (oxidation system). The radiolytic products were determined by GC coupled with electron capture detector, and the reaction rate constant of e sol - in the reduction system was measured at 2.7 x 10 10 L · mol -1 · s -1 by pulsed radiolysis. The results show that the BDE-3 concentration affects strongly the decomposition ratio in the alkali solution, and the reduction system has a higher BDE-3 decomposition rate than the oxidation system. This indicates that the BDE-3 was reduced by effectively capturing e sol - in radiolytic process. (authors)

Debromination and decomposition of bromoform by contact glow discharge electrolysis in an aqueous solution

International Nuclear Information System (INIS)

Wang, Lei; Liu, Panliang; Zhang, Songlin

2015-01-01

Bromoform (BF) is a stable and carcinogenic contaminant in water. In this study, efficient debromination and decomposition of BF induced by contact glow discharge electrolysis (CGDE) in a sodium sulfate solution were investigated. Intermediate byproducts were determined by ionic chromatography and gas chromatography, respectively. Experimental results showed that alkaline conditions and additions of organic additives to the solution were favorable for both the removal and the debromination of BF. Oxalic acid, formic acid, dibromomethane and bromate ion were determined as the major intermediate byproducts. Final products were inorganic carbon and bromide ion. Hydrated electrons may be the most likely active species responsible for the initiation of the debromination, and hydroxyl radicals may be the ones for the oxidation of the intermediate byproducts

Physical chemistry of the interface between oxide and aqueous solution

International Nuclear Information System (INIS)

Jolivet, J.P.

1997-01-01

The behavior and properties of small oxide particles in aqueous suspension are dominated by the physico-chemistry of their surface. It is electrostatically charged and strongly solvated. The origin of the surface charge is discussed through the MUSIC model [Hiemstra 1996], allowing to estimate the acid-base behavior of surface oxygen atoms. The stability of aqueous dispersions of particles is analysed following the DLVO model, with a special attention on the hydration layers allowing the peptization of flocs. Different adsorption mechanisms of metal cations are presented in terms of coordination chemistry (outer- and inner-sphere complexes) emphasizing the coordinating ability of the surface towards metal complexes in solution. The anion adsorption is also studied in relation with some interesting consequences on spinel iron oxide nano-particles. (author)

Molecular Twister: A Game for Exploring Solution Chemistry †

OpenAIRE

Masonjones, Sawyer R.; Masonjones, Heather D.; Malone, Megan C.; Williams, Ann H.; Beemer, Margaret M.; Waggett, Rebecca J.

2014-01-01

pH is an essential biological concept with critical importance at various scales, from the molecular level, dealing with blood buffers, homeostasis, and proton gradients, all the way up to the ecosystem level, with soil chemistry and acid rain. However, pH is also a concept that spawns student misconceptions and misunderstanding in terms of what is happening in a solution on the atomic level. The Molecular Twister game, created for a Florida Department of Education funded professional develop...

Molecular Twister: A Game for Exploring Solution Chemistry

Directory of Open Access Journals (Sweden)

Sawyer R. Masonjones

2014-02-01

Full Text Available pH is an essential biological concept with critical importance at various scales, from the molecular level, dealing with blood buffers, homeostasis, and proton gradients, all the way up to the ecosystem level, with soil chemistry and acid rain. However, pH is also a concept that spawns student misconceptions and misunderstanding in terms of what is happening in a solution on the atomic level. The Molecular Twister game, created for a Florida Department of Education funded professional development workshop for Florida high school teachers hosted at the University of Tampa  (Science Math Masters, seeks to model pH in such a way that students can visually and kinesthetically learn the concept in a few minutes. In addition, the basic design of the game pieces allow for teaching extensions to include more complex acid-base reactions. Challenge questions are provided to allow teachers to bring relevancy to the game, using examples of acid-base chemistry pulled from cases in human health and the environment.

Gas phase ion chemistry

CERN Document Server

Bowers, Michael T

1979-01-01

Gas Phase Ion Chemistry, Volume 1 covers papers on the advances of gas phase ion chemistry. The book discusses the advances in flow tubes and the measurement of ion-molecule rate coefficients and product distributions; the ion chemistry of the earth's atmosphere; and the classical ion-molecule collision theory. The text also describes statistical methods in reaction dynamics; the state selection by photoion-photoelectron coincidence; and the effects of temperature and pressure in the kinetics of ion-molecule reactions. The energy distribution in the unimolecular decomposition of ions, as well

Green synthesis of silver nanoparticles and silver colloidal solutions

International Nuclear Information System (INIS)

Nguyen Thi Phuong Phong; Ngo Hoang Minh; Ngo Vo Ke Thanh; Dang Mau Chien

2009-01-01

In this paper, silver colloidal solutions have been synthesized rapidly in green conditions by using microwave irradiation and non-toxic chemistry substances (acid oxalic, silver nitrate, polyvinyl pyrolidone (PVP; Mw = 55 000)). The particle size and morphology of these solutions can be controlled by altering several factors like the time, the power of microwave exposure, and the ratio of silver oxalate and PVP etc. The silver nanoparticles were fabricated by thermal decomposition of silver oxalate. The synthesized silver colloidal solutions and silver nanoparticles were characterized by several analytical techniques like UV- VIS, XRD, TEM, FESEM/EDS and ICP-AAS studies. Finally, we used the synthesized silver colloidal solutions for antibacterial purpose. The obtained results showed that the synthesized silver colloidal solutions, even at very low concentrations, have highly efficient anti-bacterial property.

Rates of Decomposition of N-Chloramine Disinfectant Compounds in Aqueous Solutions

International Nuclear Information System (INIS)

EI-Bellihi, E.E.

2009-01-01

The effect of temperature, ph, and salt effects on the decomposition kinetics of hydrolysis of N-chloramine disinfectant compounds [chloramine-B, chloramine-T, N-chlorosuccinimide (NCS), and 1,3-dichloro-5,5-dimethyl hydantoin (DCDMH or Halane)] in aqueous solutions was studied. The results should that the hydrolytic stability of CB and CT is greater than that of NCS and halane. Using CT, which is practical in use for its long contact times, reduced its initial concentration in aqueous solution from 100 ppm to about 20 ppm after a period of 6 months. The study also showed that the rate of hydrolysis of NCS is almost independent on the H + ions concentration. On the other hand, the rates of hydrolysis of CB and CT depend strongly on the hydrogen ion (H + ) concentration where the kinetic of the reaction changes from zero-order to a first order. The thermodynamic parameters of activation were calculated and showed that the entropies of activation have large negative values due to the increase in electrostriction and in a loss of freedom of the solvent water molecules associated with the separation of ions in the transition state. A linear compensation between ΔH and ΔS suggests that in the pure aqueous solutions, the reaction mechanism is almost the same for all the chloramine compounds under investigation

A solution of nonlinear equation for the gravity wave spectra from Adomian decomposition method: a first approach

Directory of Open Access Journals (Sweden)

Antonio Gledson Goulart

2013-12-01

Full Text Available In this paper, the equation for the gravity wave spectra in mean atmosphere is analytically solved without linearization by the Adomian decomposition method. As a consequence, the nonlinear nature of problem is preserved and the errors found in the results are only due to the parameterization. The results, with the parameterization applied in the simulations, indicate that the linear solution of the equation is a good approximation only for heights shorter than ten kilometers, because the linearization the equation leads to a solution that does not correctly describe the kinetic energy spectra.

Physico-chemistry of actinides and other radioelements in solutions and at the interfaces

International Nuclear Information System (INIS)

2000-01-01

This document provides the 61 papers (transparencies used during the presentations and posters) presented at the 1999 PRACTIS days, held February 17-18, 2000 in Villeneuve-les-Avignon. The content comprises 9 conferences dealing with 1)simulation of solvation, coordination and liquid-liquid extraction of rare earth and uranyl cations 2)overview on the complexation selectivity of actinides(III) and rare earths(III) by aromatic poly-nitrogenous ligands 3)detection, characterization and interaction between supramolecular aggregates of extractants: macroscopic consequences on the stability and on the macroscopic behaviour 4)chemistry of technetium in reducing medium: application to researches on radioactive waste management 5) separations by pyro-chemistry (CEA program) 6)overview on the Goethite operation 7)use of time-resolved luminescence spectroscopy to the determination of sorption sites at the interfaces 8)dissolution of uranium dioxide in an argillaceous water: results in oxidizing and reducing conditions 9)treatment and storage of radioactive wastes from weapon-grade plutonium production in Russia and other countries. A large part of the conference was devoted to poster sessions on the following topics: physico-chemistry in homogeneous solutions (22 posters), transfer kinetics of actinides and rare earths between liquid phases and separations (9 posters), physico-chemistry of the solid-solution interface (9 posters), simulation and molecular dynamics (5 posters), uranium dioxide and other oxides (1 poster), long-lived fission products (6 posters). (O.M.)

Thermal Decomposition of Aluminium Chloride Hexahydrate

Czech Academy of Sciences Publication Activity Database

Hartman, Miloslav; Trnka, Otakar; Šolcová, Olga

2005-01-01

Roč. 44, č. 17 (2005), s. 6591-6598 ISSN 0888-5885 R&D Projects: GA ČR(CZ) GA203/02/0002 Institutional research plan: CEZ:AV0Z40720504 Keywords : aluminum chloride hexahydrate * thermal decomposition * reaction kinetics Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.504, year: 2005

Solution chemistry

Energy Technology Data Exchange (ETDEWEB)

None

1973-07-01

Research progress is reported on studies in heavy element chemistry. Topics considered are: synergistic complexes of plutonyl ion; water uptake in synergistic systems; formation constants of some uranyl BETA -diketone complexes; thermodynamic acid dissociation constants of BETA -diketones; thermodynamic formation constants of uranyl BETA -diketonates; thiocyanate complexes of some trivalent lanthanides and actinides; stability constants of actinide complexes using dinonyl naphthalenesulfonic acid extraction; TBP extraction of actinides; stability constants of complexes of Pu(III) with 5- sulfosalicycllc acid; and solvent extraction behavior of Pu( VII). (DHM)

Studies on the radiation chemistry of biomolecules in aqueous solution with specific objective of minimizing their radiolytic degradation. Coordinated programme for Asia and the Pacific Region on radiation sterilization practices significant to local medical supplies and conditions

International Nuclear Information System (INIS)

Narayana Rao, K.

1979-01-01

As part of a study of radiolytic degradation of pharmaceuticals during radiosterilization, the basic radiation chemistry of the B-group vitamins, nicotinamide, pyridoxin, riboflavin and thiamine, and the reaction of hydrogen peroxide with these same materials has been investigated. The various aspects studied were - radiolysis under controlled conditions, effects of phase, temperature, pH and nature and concentration of additives. Some of the conclusions are: 1) with oxygen saturated aqueous solutions containing glucose, the radiolytic degradation of the vitamins is reduced: 2) results a similar for N 2 O saturated aqueous solutions; 3) in glucose-containing solutions, the protective effect is considerably modified at higher temperatures; and 4) irradiation of air-saturated aqueous solutions in the frozen state leads to reduced decomposition. It is concluded that in the presence of oxygen, in frozen matrices at low temperature, it appears possible to reduce the radiolytic breakdown of vitamins to low levels

Generalized decompositions of dynamic systems and vector Lyapunov functions

Science.gov (United States)

Ikeda, M.; Siljak, D. D.

1981-10-01

The notion of decomposition is generalized to provide more freedom in constructing vector Lyapunov functions for stability analysis of nonlinear dynamic systems. A generalized decomposition is defined as a disjoint decomposition of a system which is obtained by expanding the state-space of a given system. An inclusion principle is formulated for the solutions of the expansion to include the solutions of the original system, so that stability of the expansion implies stability of the original system. Stability of the expansion can then be established by standard disjoint decompositions and vector Lyapunov functions. The applicability of the new approach is demonstrated using the Lotka-Volterra equations.

Mass transfer in fuel cells. [electron microscopy of components, thermal decomposition of Teflon, water transport, and surface tension of KOH solutions

Science.gov (United States)

Walker, R. D., Jr.

1973-01-01

Results of experiments on electron microscopy of fuel cell components, thermal decomposition of Teflon by thermogravimetry, surface area and pore size distribution measurements, water transport in fuel cells, and surface tension of KOH solutions are described.

Radiation chemistry

Energy Technology Data Exchange (ETDEWEB)

None

1973-07-01

Research progress is reported on radiation chemistry of heavy elements that includes the following topics: radiation chemistry of plutonium in nitric acid solutions (spectrophotometric analysis and gamma radiolysis of Pu(IV) and Pu(VI) in nitric acid solution); EPR studies of intermediates formed in radiolytic reactions with aqueous medium; two-phase radiolysis and its effect on the distribution coefficient of plutonium; and radiation chemistry of nitric acid. (DHM)

Transport of titanium dioxide nanoparticles in saturated porous media under various solution chemistry conditions

International Nuclear Information System (INIS)

Wang Yu; Gao Bin; Morales, Verónica L.; Tian Yuan; Wu Lei; Gao Jie; Bai Wei; Yang Liuyan

2012-01-01

Because of its wide applications, nanosized titanium dioxide may become a potential environmental risk to soil and groundwater system. It is therefore important to improve current understanding of the environmental fate and transport of titanium oxides nanoparticles (TONPs). In this work, the effect of solution chemistry (i.e., pH, ionic strength, and natural organic matter (NOM) concentration) on the deposition and transport of TONPs in saturated porous media was examined in detail. Laboratory columns packed with acid-cleaned quartz sand were used in the experiment as porous media. Transport experiments were conducted with various chemistry combinations, including four ionic strengths, three pH levels, and two NOM concentrations. The results showed that TONP mobility increased with increasing solution pH, but decreased with increasing solution ionic strength. It is also found that the presence of NOM in the system enhanced the mobility of TONPs in the saturated porous media. The Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was used to justify the mobility trends observed in the experimental data. Predictions from the theory agreed excellently with the experimental data.

Studies in useful hard x-ray induced chemistry

Science.gov (United States)

Pravica, Michael; Bai, Ligang; Sneed, Daniel; Park, Changyong

2013-06-01

The observed rapid decomposition of potassium chlorate (via 2KClO3 + h ν --> 2KCl +3O2) via synchrotron hard x-ray irradiation (>10 keV) has enabled experiments that are developing novel and useful hard x-ray chemistry. We have observed a number of radiation-induced in situ decomposition reactions in various substances which release O2, H2, N2, NH3, and H2O in a diamond anvil cell (DAC) at ambient and high pressures. These novel acatalytic and isothermal reactions represent a highly controllable, penetrating, and focused method to initiate chemistry (including x-ray induced combustion) in sealed and/or isolated chambers which maintain matter under extreme conditions. During our studies, we have typically observed a slowing of decomposition with pressure including phase dependent decomposition of KClO3. Energy dependent studies have observed an apparent resonance near 15 keV at which the decomposition rate is maximized. This may enable use of much lower flux and portable x-ray sources (e.g. x-ray tubes) in larger scale experiments. These developments support novel means to load DACs and control chemical reactions providing novel routes of synthesis of novel materials under extreme conditions.

Achievement report on research and development in the Sunshine Project in fiscal 1977. Research and development of water decomposition using mixture cycles composed by thermo-chemistry, photo-chemistry and electrochemistry; 1977 nendo netsukagaku, hikari kagaku, denki kagaku konsei cycle ni yoru suibunkai no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1978-03-01

Discussions are being made on manufacture of hydrogen and oxygen from water decomposition using mixture cycles composed by thermo-chemistry, photo-chemistry and electrochemistry using ferrous sulfate and iodine. Photo-chemical reaction produces Fe(OH)SO{sub 4} and HI, but due to difficulty of isolating Fe(OH)SO{sub 4}, photo-chemical reaction that can obtain the compound as Fe{sub 2}(SO{sub 4}){sub 3} was introduced. A method was introduced that can perform HI isolation simultaneously while performing reaction to reduce Fe{sup 3+} and turn it into Fe{sup 2+} (generating oxygen) by means of electrolysing the liquid after the former reaction. The electrolytic process decomposes HI into hydrogen and iodine (discussions on thermo-chemical decomposition is also continued). Since the photo-chemical reaction can cause reverse reaction, discussions were given on the reaction process in order to suppress the reverse reaction and enhance the conversion efficiency. This paper describes the achievements during fiscal 1977. A quantification method was elucidated on individual iodine components so that it can be used for computerized control (measurement of absorbance of I{sub 3}{sup -}) . An electrolytic tank was discussed that decomposes and isolates photo-chemical reaction products before the reverse reaction occurs. Heat diffusion method was also discussed that isolates hydrogen from HI decomposition products. (NEDO)

Effects of solution chemistry and aging time on prion protein adsorption and replication of soil-bound prions.

Directory of Open Access Journals (Sweden)

Samuel E Saunders

2011-04-01

Full Text Available Prion interactions with soil may play an important role in the transmission of chronic wasting disease (CWD and scrapie. Prions are known to bind to a wide range of soil surfaces, but the effects of adsorption solution chemistry and long-term soil binding on prion fate and transmission risk are unknown. We investigated HY TME prion protein (PrP(Sc adsorption to soil minerals in aqueous solutions of phosphate buffered saline (PBS, sodium chloride, calcium chloride, and deionized water using western blotting. The replication efficiency of bound prions following adsorption in these solutions was also evaluated by protein misfolding cyclic amplification (PMCA. Aging studies investigated PrP(Sc desorption and replication efficiency up to one year following adsorption in PBS or DI water. Results indicate that adsorption solution chemistry can affect subsequent prion replication or desorption ability, especially after incubation periods of 30 d or longer. Observed effects were minor over the short-term (7 d or less. Results of long-term aging experiments demonstrate that unbound prions or prions bound to a diverse range of soil surfaces can readily replicate after one year. Our results suggest that while prion-soil interactions can vary with solution chemistry, prions bound to soil could remain a risk for transmitting prion diseases after months in the environment.

The platinum catalysed decomposition of hydrazine in acidic media

International Nuclear Information System (INIS)

Ananiev, A.V.; Tananaev, I.G.; Brossard, Ph.; Broudic, J.C.

2000-01-01

Kinetic study of the hydrazine decomposition in the solutions of HClO 4 , H 2 SO 4 and HNO 3 in the presence of Pt/SiO 2 catalyst has been undertaken. It was shown that the kinetics of the hydrazine catalytic decomposition in HClO 4 and H 2 SO 4 are identical. The process is determined by the heterogeneous catalytic auto-decomposition of N 2 H 4 on the catalyst's surface. The platinum catalysed hydrazine decomposition in the nitric acid solutions is a complex process, including heterogeneous catalytic auto-decomposition of N 2 H 4 , reaction of hydrazine with catalytically generated nitrous acid and the catalytic oxidation of hydrazine by nitric acid. The kinetic parameters of these reactions have been determined. The contribution of each reaction in the total process is determined by the liquid phase composition and by the temperature. (authors)

Achievement report on research and development in the Sunshine Project in fiscal 1976. Research and development of water decomposition by using a hybrid cycle composed of thermo-chemistry and photo-chemistry; 1976 nendo netsukagaku oyobi hikari kagaku hybrid cycle ni yoru mizu bunkai no kenkyu kahatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1977-03-01

This paper describes water decomposition by using a hybrid cycle composed of thermo-chemistry and photo-chemistry. Ferric sulfate and HI are obtained from ferrous sulfate and iodine via photo-chemical reaction. This is an endothermic reaction of 10.8 kcal. Then, the photo-chemically reacted aqueous solution is electrolysed to separate HI, while Fe{sup 3+} (ferric ion) is reduced and converted into Fe{sup 2+} (ferrous ion). Oxygen is generated at this time. Since mixed potential is made from iron oxidation and reduction potential and iodine potential, the electrolytic efficiency is greatly influenced by electrode materials. Ideally, an electrode material that causes only the reduction of Fe{sup 3+}, but not other reactions is preferable. The HI is decomposed into hydrogen and iodine by electrolysis. Research is continuing to acquire hydrogen from HI thermo-chemically. Endothermic reaction heat of 7 to 8 kcal has been obtained in photo-chemical reaction, the heat quantity being close to the theoretical value of 10.8. A result close to the theoretical value may be expected if the electrode material problem is solved. The basic research will be continued for a high possibility of linking the research to a pilot plant in the future. (NEDO)

Radiation-induced decomposition of aqueous trichloroethylene solutions

International Nuclear Information System (INIS)

Gehringer, P.; Proksch, E.; Szinovatz, W.; Eschweiler, H.

1988-01-01

In air-saturated reagent grade water, 10 ppm trichloroethylene are decomposed by γ radiation in a roughly first-order reaction; the initial G-value being 5.4 molecules/100 eV. At sub-ppm concentrations the kinetics remain roughly first-order; the initial G-values decrease with decreasing concentration. The main decomposition products are Cl - , CO 2 and HCOOH. A tentative reaction scheme in accordance with these results is presented. (author)

Implicit upwind schemes for computational fluid dynamics. Solution by domain decomposition

International Nuclear Information System (INIS)

Clerc, S.

1998-01-01

In this work, the numerical simulation of fluid dynamics equations is addressed. Implicit upwind schemes of finite volume type are used for this purpose. The first part of the dissertation deals with the improvement of the computational precision in unfavourable situations. A non-conservative treatment of some source terms is studied in order to correct some shortcomings of the usual operator-splitting method. Besides, finite volume schemes based on Godunov's approach are unsuited to compute low Mach number flows. A modification of the up-winding by preconditioning is introduced to correct this defect. The second part deals with the solution of steady-state problems arising from an implicit discretization of the equations. A well-posed linearized boundary value problem is formulated. We prove the convergence of a domain decomposition algorithm of Schwartz type for this problem. This algorithm is implemented either directly, or in a Schur complement framework. Finally, another approach is proposed, which consists in decomposing the non-linear steady state problem. (author)

The New Color of Chemistry: Green Chemistry

Directory of Open Access Journals (Sweden)

Zuhal GERÇEK

2012-01-01

Full Text Available Green chemistry which is the new application of chemistry rules provides solutions to problems that mankind is faced with climate changes, sustainable agriculture, energy, toxics, depletion of natural sources e.g. designing new chemicals and processes that production and utilization of hazardous matters. So, it is the indispensible tool for sustainable development. Current and future chemists should consider the human health and ecological issues in their professional life. In order to provide a solution for this requirement, green chemistry rules and under standings should be primarily taken in the university curriculum and at all educational levels.

Photocatalytic decomposition of cortisone acetate in aqueous solution

NARCIS (Netherlands)

Sobral Romao, J.I.; Saad, M.H.; Mul, Guido; Baltrusaitis, Jonas

2015-01-01

The photocatalytic decomposition of cortisone 21-acetate (CA), a model compound for the commonly used steroid, cortisone, was studied. CA was photocatalytically decomposed in a slurry reactor with the initial rates between 0.11 and 0.46 mg L−1 min−1 at 10 mg L−1 concentration, using the following

Radiolytic decomposition of pesticide carbendazim in waters and wastes for environmental protection

International Nuclear Information System (INIS)

Bojanowska-Czajka, A.; Drzewicz, P.; Meczynska, S.; Kruszewski, M.; Zimek, Z.; Nichipor, H.; Galezowska, A.; Nalecz-Jawecki, G.; Trojanowicz, M.; Warsaw University, Warsaw

2011-01-01

The radiolytic degradation of widely used fungicide, carbendazim, in synthetic aqueous solutions and industrial wastewater was investigated employing γ-irradiation. The effect of the absorbed dose, initial concentration and pH of irradiated solution on the effectiveness of carbendazim decomposition were investigated. Decomposition of carbendazim in 100 μM concentration in synthetic aqueous solutions required irradiation with 600 Gy dose. The aqueous solutions of carbendazim have been irradiated in different conditions, where particular active radical species from water radiolysis predominate. The obtained data have been compared with the kinetic modeling. The reversed-phase high-performance liquid chromatography was used for the determination of carbendazim and its radiolytic decomposition products in irradiated solutions. The changes of toxicity of irradiated solutions were examined with different test organisms and human leukemia cells. (author)

Complex chemistry

International Nuclear Information System (INIS)

Kim, Bong Gon; Kim, Jae Sang; Kim, Jin Eun; Lee, Boo Yeon

2006-06-01

This book introduces complex chemistry with ten chapters, which include development of complex chemistry on history coordination theory and Warner's coordination theory and new development of complex chemistry, nomenclature on complex with conception and define, chemical formula on coordination compound, symbol of stereochemistry, stereo structure and isomerism, electron structure and bond theory on complex, structure of complex like NMR and XAFS, balance and reaction on solution, an organo-metallic chemistry, biology inorganic chemistry, material chemistry of complex, design of complex and calculation chemistry.

Thermal decomposition of dilute aqueous formic acid solutions

DEFF Research Database (Denmark)

Bjerre, A.B.; Sørensen, E.

1992-01-01

or a decarboxylation. In particular the second one is dependent on the reactor vessel used. It is shown to be catalyzed by a mixture of oxides of stainless steel components. The presence of CH3COOH or CH3CHO promotes the decomposition of HCOOH by way of both decarboxylation and oxidation. In any case formic acid...

Dual role of lignin in plant litter decomposition in terrestrial ecosystems.

Science.gov (United States)

Austin, Amy T; Ballaré, Carlos L

2010-03-09

Plant litter decomposition is a critical step in the formation of soil organic matter, the mineralization of organic nutrients, and the carbon balance in terrestrial ecosystems. Biotic decomposition in mesic ecosystems is generally negatively correlated with the concentration of lignin, a group of complex aromatic polymers present in plant cell walls that is recalcitrant to enzymatic degradation and serves as a structural barrier impeding microbial access to labile carbon compounds. Although photochemical mineralization of carbon has recently been shown to be important in semiarid ecosystems, litter chemistry controls on photodegradative losses are not understood. We evaluated the importance of litter chemistry on photodegradation of grass litter and cellulose substrates with varying levels of lignin [cellulose-lignin (CL) substrates] under field conditions. Using wavelength-specific light attenuation filters, we found that light-driven mass loss was promoted by both UV and visible radiation. The spectral dependence of photodegradation correlated with the absorption spectrum of lignin but not of cellulose. Field incubations demonstrated that increasing lignin concentration reduced biotic decomposition, as expected, but linearly increased photodegradation. In addition, lignin content in CL substrates consistently decreased in photodegradative incubations. We conclude that lignin has a dual role affecting litter decomposition, depending on the dominant driver (biotic or abiotic) controlling carbon turnover. Under photodegradative conditions, lignin is preferentially degraded because it acts as an effective light-absorbing compound over a wide range of wavelengths. This mechanistic understanding of the role of lignin in plant litter decomposition will allow for more accurate predictions of carbon dynamics in terrestrial ecosystems.

Molecular Structure of Salt Solutions: A New View of the Interface with Implications for Heterogeneous Atmospheric Chemistry

Czech Academy of Sciences Publication Activity Database

Jungwirth, Pavel; Tobias, D. J.

2001-01-01

Roč. 105, č. 43 (2001), s. 10468-10472 ISSN 1089-5647 R&D Projects: GA MŠk LN00A032 Institutional research plan: CEZ:AV0Z4040901 Keywords : air-solution interface * salt solutions * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.379, year: 2001

High temperature performance and stability of Fe-FER catalyst for N2O decomposition

Czech Academy of Sciences Publication Activity Database

Sádovská, Galina; Tabor, Edyta; Sazama, Petr; Lhotka, M.; Bernauer, M.; Sobalík, Zdeněk

2017-01-01

Roč. 89, JAN 2017 (2017), s. 133-137 ISSN 1566-7367 R&D Projects: GA ČR(CZ) GA14-10251S; GA MŠk(CZ) LM2015073 Institutional support: RVO:61388955 Keywords : High temperature N2O decomposition * FER * Iron Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.330, year: 2016

Thermal unimolecular decomposition of bicyclopropyl and deuterated analogues: infrared photoactivation as a diagnostic tool in mechanistic organic chemistry

International Nuclear Information System (INIS)

Farneth, W.E.; Thomsen, M.W.

1982-01-01

The infrared photochemistry of bicyclopropyl yields product mixtures that are not easily rationalized on the basis of the mechanistic scheme suggested by previous pyrolysis work. As a result of this inconsistency the thermal chemistry of bicyclopropyl and analogues deuterated specifically on one ring has been reexamined. A significant new reaction channel involving the chemically activated decomposition of cyclohexene to ethylene and butadiene has been demonstrated. Evidence for the involvement of chemically activated cyclohexene is as follows: (1) isotopic labeling studies implying a symmetric intermediate, (2) a pressure-dependent ratio of cyclohexene to butadiene and ethylene, (3) good agreement between experimental and calculated values for the unimolecular rate constant for retro-Diels-Alder decay of ''hot'' cyclohexene. A comprehensive mechanism for the unimolecular decay of bicyclopropyl is proposed. The important elements of this mechanism are a single first-formed 1,3 biradical common to all products and the intervention of chemical activation in the generation of several of the secondary products

Mass spectrometry. [in organic chemistry

Science.gov (United States)

Burlingame, A. L.; Shackleton, C. H. L.; Howe, I.; Chizhov, O. S.

1978-01-01

A review of mass spectrometry in organic chemistry is given, dealing with advances in instrumentation and computer techniques, selected topics in gas-phase ion chemistry, and applications in such fields as biomedicine, natural-product studies, and environmental pollution analysis. Innovative techniques and instrumentation are discussed, along with chromatographic-mass spectrometric on-line computer techniques, mass spectral interpretation and management techniques, and such topics in gas-phase ion chemistry as electron-impact ionization and decomposition, photoionization, field ionization and desorption, high-pressure mass spectrometry, ion cyclotron resonance, and isomerization reactions of organic ions. Applications of mass spectrometry are examined with respect to bio-oligomers and their constituents, biomedically important substances, microbiology, environmental organic analysis, and organic geochemistry.

Accuracy of the Adomian decomposition method applied to the Lorenz system

International Nuclear Information System (INIS)

Hashim, I.; Noorani, M.S.M.; Ahmad, R.; Bakar, S.A.; Ismail, E.S.; Zakaria, A.M.

2006-01-01

In this paper, the Adomian decomposition method (ADM) is applied to the famous Lorenz system. The ADM yields an analytical solution in terms of a rapidly convergent infinite power series with easily computable terms. Comparisons between the decomposition solutions and the fourth-order Runge-Kutta (RK4) numerical solutions are made for various time steps. In particular we look at the accuracy of the ADM as the Lorenz system changes from a non-chaotic system to a chaotic one

Reactivity continuum modeling of leaf, root, and wood decomposition across biomes

Science.gov (United States)

Koehler, Birgit; Tranvik, Lars J.

2015-07-01

Large carbon dioxide amounts are released to the atmosphere during organic matter decomposition. Yet the large-scale and long-term regulation of this critical process in global carbon cycling by litter chemistry and climate remains poorly understood. We used reactivity continuum (RC) modeling to analyze the decadal data set of the "Long-term Intersite Decomposition Experiment," in which fine litter and wood decomposition was studied in eight biome types (224 time series). In 32 and 46% of all sites the litter content of the acid-unhydrolyzable residue (AUR, formerly referred to as lignin) and the AUR/nitrogen ratio, respectively, retarded initial decomposition rates. This initial rate-retarding effect generally disappeared within the first year of decomposition, and rate-stimulating effects of nutrients and a rate-retarding effect of the carbon/nitrogen ratio became more prevalent. For needles and leaves/grasses, the influence of climate on decomposition decreased over time. For fine roots, the climatic influence was initially smaller but increased toward later-stage decomposition. The climate decomposition index was the strongest climatic predictor of decomposition. The similar variability in initial decomposition rates across litter categories as across biome types suggested that future changes in decomposition may be dominated by warming-induced changes in plant community composition. In general, the RC model parameters successfully predicted independent decomposition data for the different litter-biome combinations (196 time series). We argue that parameterization of large-scale decomposition models with RC model parameters, as opposed to the currently common discrete multiexponential models, could significantly improve their mechanistic foundation and predictive accuracy across climate zones and litter categories.

Achievement report on research and development in the Sunshine Project in fiscal 1979. Research and development on water decomposition by using mixed cycle of thermo-chemistry, photo-chemistry and electrochemistry; 1979 nendo netsukagaku, hikari kagaku, denki kagaku konsei cycle ni yoru mizu bunkai no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1980-03-01

This paper describes achievements in research and development in the Sunshine Project in fiscal 1979 on water decomposition by using mixed cycle of thermo-chemistry, photo-chemistry and electrochemistry. In research on the light irradiation electrolytic process, with an objective of improving the reaction efficiency, discussions were given by raising light intensity on the irradiated surface as high as 13 times that of the sunlight. The subsequent process is electrolysis of products from photo-chemical reaction, and the product concentration should be high enough to have HI decomposition (hydrogen acquisition) proceed with high efficiency. Experiments were carried out at 0.03 to 0.1M as iodine concentrations (product HI concentration at 3%). A photo-chemical reaction rate of 80% was obtained at light intensity as high as 12 times that of the sunlight, and iodine concentration of 0.07 mM. The efficiency was 15%. Raising temperature causes the reaction rate to decrease, but it can be supplemented by raising the light intensity, where high concentration HI content was obtained. Rate controlling process in the reaction was elucidated from activation energies in the reaction process of each element on the iodine concentrations from 3 to 30 mM used in the photo-chemical reaction. Experiments were performed on HI decomposition (hydrogen acquisition) by using a heat diffusion column. Separation performance in a filled type column was worse than that in an empty type column, which requires future discussions. (NEDO)

Formation of metastable and equilibrium phases in the decomposition of the β solid solution in Zr alloys

International Nuclear Information System (INIS)

Zakharova, M.I.; Kirov, S.A.; Khundzhua, A.G.

1978-01-01

The decomposition of the β solid solution is studied in Zr-Nb alloys with adding Mo, Al, V, Fe by the methods of electron microscopy and X-ray diffraction on single crystals. The intermetallic compounds forming during crystallization of the alloys do not influence the precipitation of the ω- and α-phases during ageing. In the local regions of foils prepared by electropolishing after ageing the formation of the metastable f.c.c. phase and in some cases the inverse transformation of two phase state to the parent phase is observed. (author)

Can radiation chemistry supply a highly efficient AO(R)P process for organics removal from drinking and waste water? A review.

Science.gov (United States)

Trojanowicz, Marek; Bojanowska-Czajka, Anna; Capodaglio, Andrea G

2017-09-01

The increasing role of chemistry in industrial production and its direct and indirect impacts in everyday life create the need for continuous search and efficiency improvement of new methods for decomposition/removal of different classes of waterborne anthropogenic pollutants. This review paper addresses a highly promising class of water treatment solutions, aimed at tackling the pressing problem of emerging contaminants in natural and drinking waters and wastewater discharges. Radiation processing, a technology originating from radiation chemistry studies, has shown encouraging results in the treatment of (mainly) organic water pollution. Radiation ("high energy") processing is an additive-free technology using short-lived reactive species formed by the radiolysis of water, both oxidative and reducing, to carry out decomposition of organic pollutants. The paper illustrates the basic principles of radiolytic treatment of organic pollutants in water and wastewaters and specifically of one of its most practical implementations (electron beam processing). Application examples, highlighting the technology's strong points and operational conditions are described, and a discussion on the possible future of this technology follows.

Analytical chemistry

Energy Technology Data Exchange (ETDEWEB)

Chae, Myeong Hu; Lee, Hu Jun; Kim, Ha Seok

1989-02-15

This book give explanations on analytical chemistry with ten chapters, which deal with development of analytical chemistry, the theory of error with definition and classification, sample and treatment gravimetry on general process of gravimetry in aqueous solution and non-aqueous solution, precipitation titration about precipitation reaction and types, complexometry with summary and complex compound, oxidation-reduction equilibrium on electrode potential and potentiometric titration, solvent extraction and chromatograph and experiment with basic operation for chemical experiment.

Analytical chemistry

International Nuclear Information System (INIS)

Chae, Myeong Hu; Lee, Hu Jun; Kim, Ha Seok

1989-02-01

This book give explanations on analytical chemistry with ten chapters, which deal with development of analytical chemistry, the theory of error with definition and classification, sample and treatment gravimetry on general process of gravimetry in aqueous solution and non-aqueous solution, precipitation titration about precipitation reaction and types, complexometry with summary and complex compound, oxidation-reduction equilibrium on electrode potential and potentiometric titration, solvent extraction and chromatograph and experiment with basic operation for chemical experiment.

Decomposition of size-exclusion chromatography elution curves of complex branched polymers

Czech Academy of Sciences Publication Activity Database

Netopilík, Miloš; Janata, Miroslav

2014-01-01

Roč. 1330, 21 February (2014), s. 14-19 ISSN 0021-9673 R&D Projects: GA ČR GCP205/11/J043 Institutional support: RVO:61389013 Keywords : size-exclusion chromatography * triple detection * curve decomposition Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.169, year: 2014

General chemistry

International Nuclear Information System (INIS)

Kwon, Yeong Sik; Lee, Dong Seop; Ryu, Haung Ryong; Jang, Cheol Hyeon; Choi, Bong Jong; Choi, Sang Won

1993-07-01

The book concentrates on the latest general chemistry, which is divided int twenty-three chapters. It deals with basic conception and stoichiometry, nature of gas, structure of atoms, quantum mechanics, symbol and structure of an electron of ion and molecule, chemical thermodynamics, nature of solid, change of state and liquid, properties of solution, chemical equilibrium, solution and acid-base, equilibrium of aqueous solution, electrochemistry, chemical reaction speed, molecule spectroscopy, hydrogen, oxygen and water, metallic atom; 1A, IIA, IIIA, carbon and atom IVA, nonmetal atom and an inert gas, transition metals, lanthanons, and actinoids, nuclear properties and radioactivity, biochemistry and environment chemistry.

Estimation of Hydrazine Decomposition on Measuring the High-Temperature pH in Hydrazine/ETA Solutions at 553 K

International Nuclear Information System (INIS)

Hwang, Jae Sik; Yeon, Jei Won; Yun, Myung Hee; Song, Kyu Seok; Lee, Sang Ill

2010-01-01

Hydrazine is one of the most excellent oxygen scavengers used in the secondary circuit of nuclear power plants. Furthermore, in some pants, the hydrazine is used as a source of hydrogen required to suppress radiolysis of the coolant water in the primary loop. When hydrazine was exposed in the high temperature and high pressure water, it can be decomposed into the various products such as NH 3 , N 2 , H 2 , and NO 3 ions. As the result, the pH of solution containing hydrazine in the condition of the high temperature and high pressure can be changed by those decomposed products. In the present work, we investigated the decomposition behavior of hydrazine in ETA (ethanol amine) solution. In addition, we measured the high temperature pH at 553 K on the various hydrazine/ETA solutions for confirming the applicability of the yttria stabilized zirconia (YSZ)- based pH electrode in secondary circuit of the nuclear power plants

Hydrothermal treatment of municipal solid waste incineration fly ash for dioxin decomposition

International Nuclear Information System (INIS)

Hu, Yuyan; Zhang, Pengfei; Chen, Dezhen; Zhou, Bin; Li, Jianyi; Li, Xian-wei

2012-01-01

Highlights: ► The first study to apply Fe-sulfate in hydrothermal treatment of municipal solid waste incineration fly ash for dioxin decomposition. ► The first study to comprehensively evaluate the effect of hydrothermal treatment on dioxin decomposition and heavy metal stabilization in municipal solid waste incineration fly ash. ► Gaussian software chemical computational simulation was performed to investigate the mechanism of dioxin decomposition based on quantum chemistry calculation, and to support the experimental data by the calculation results. - Abstract: Hydrothermal treatment of MSWI fly ash was performed in this paper with a purpose to reduce its dioxin content. First a hydrothermal reactor was set up with a mixture of ferric sulphate and ferrous sulphate serviced as the reactant, then the effects caused by reaction conditions such as reaction temperature, pre-treatment by water-washing and reactant dosage were checked; the results showed that as a promising technology, hydrothermal treatment exhibited considerable high efficiencies in decomposition of PCDDs/PCDFs and good stabilization of heavy metals as well. Experimental results also showed that for dioxin destruction, higher reaction temperature is the most important influencing factor followed by Fe addition, and pre-treatment of raw fly ash by water-washing increased the destruction efficiencies of dioxins only very slightly. Finally with help of Gaussian software chemical computational simulation was performed to investigate the mechanism of dioxin decomposition based on quantum chemistry calculation. The calculation results were supported by the experimental data. The leaching toxicities of hydrothermal products were higher than upper limits defined in the latest Chinese standard GB 16889-2008 for sanitary landfill disposal, thus an auxiliary process is suggested after the hydrothermal treatment for heavy metal stabilization.

Titania and zirconia binary oxides as catalysts for total oxidation of ethyl acetate and methanol decomposition

Czech Academy of Sciences Publication Activity Database

Tsoncheva, T.; Mileva, A.; Issa, G.; Dimitrov, M.; Kovacheva, D.; Henych, Jiří; Kormunda, M.; Scotti, N.; Slušná, Michaela; Tolasz, Jakub; Štengl, Václav

2018-01-01

Roč. 6, č. 2 (2018), s. 2540-2550 ISSN 2213-3437 Grant - others:AV ČR(CZ) BAS-17-13 Program:Bilaterální spolupráce Institutional support: RVO:61388980 Keywords : Effect of preparation procedure * Ethyl acetate oxidation * Methanol decomposition * Titania-zirconia binary oxides Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry

A posteriori error analysis of multiscale operator decomposition methods for multiphysics models

International Nuclear Information System (INIS)

Estep, D; Carey, V; Tavener, S; Ginting, V; Wildey, T

2008-01-01

Multiphysics, multiscale models present significant challenges in computing accurate solutions and for estimating the error in information computed from numerical solutions. In this paper, we describe recent advances in extending the techniques of a posteriori error analysis to multiscale operator decomposition solution methods. While the particulars of the analysis vary considerably with the problem, several key ideas underlie a general approach being developed to treat operator decomposition multiscale methods. We explain these ideas in the context of three specific examples

Biological decomposition of aqueous solutions from soil cleaning

International Nuclear Information System (INIS)

Kniebusch, M.M.; Sekoulov, I.

1993-01-01

The biological cleaning of process water from soil cleaning and from contaminated groundwater required the development of new types of reaction systems. With the introduced membrane biofilm reactor, even substances difficult to decompose can be removed from contaminated water. Previous investigations of the elimination of pyrene in the presence of n-hexadecane show an optimum temperature at 30 C. An increase of scale is possible based on the invesstigations carried out on the aerobic biological decomposition of polycyclic aromatic hydrocarbons. (orig.) [de

Solute-specific patterns and drivers of urban stream chemistry revealed by long-term monitoring in Baltimore, Maryland

Science.gov (United States)

Reisinger, A. J.; Woytowitz, E.; Majcher, E.; Rosi, E. J.; Groffman, P.

2017-12-01

Urban streams receive a myriad of chemical inputs from the surrounding landscape due to altered lithology (asphalt, concrete), leaky sewage infrastructure, and other human activities (road salt, fertilizer, industrial wastes, wastewater effluent), potentially leading to multiple chemical stressors occurring simultaneously. To evaluate potential drivers of water chemistry change, we used approximately 20 years of weekly water chemistry monitoring data from streams in the Baltimore Ecosystem Study (BES) to quantify trends of annual loads and flow-weighted concentrations for multiple solutes of interest, including nitrate (NO3-), phosphate (PO43-), total nitrogen (TN), total phosphorus (TP), chloride (Cl-), and sulfate (SO42-) and subsequently examined various gray and green infrastructure characteristics at the watershed scale. For example, we quantified annual volume and duration of reported sanitary sewer overflows (SSO) and cumulative storage volume and area of various best management practices (BMPs). Site- and solute-specific trends differed, but across our monitoring network we found evidence for decreasing annual export for multiple solutes. Additionally, we found that changes in gray- and green-infrastructure characteristics were related to changes in water quality at our most downstream (most urban) monitoring site. For example, annual NO3- loads increased with longer cumulative SSO duration, whereas annual PO43- and TP loads decreased with a cumulative BMP area in the watershed. Further, we used same long-term water chemistry data and multivariate analyses to investigate whether urban streams have unique water chemistry fingerprints representing the multiple chemical stressors at a given site, which could provide insight into sources and impacts of water-quality impairment. These analyses and results illustrate the major role gray and green infrastructure play in influencing water quality in urban environments, and illustrate that focusing on a variety of

XI International conference Problems of solvation and complex formation in solutions, and VI Conference of young scientists Theoretical and experimental chemistry of liquid-phase systems (Krestovsky readings). Summary of reports

International Nuclear Information System (INIS)

2011-01-01

The collection contains materials of plenary, sectional and poster sessions, presented at the XI International conference Problems of solvation and complex formation in solutions, and VI Conference of young scientists Theoretical and experimental chemistry of liquid-phase systems (Krestovsky readings). Theoretical questions and new experimental methods of chemistry of solutions, structure and dynamics of molecular and ion-molecular systems in solution and at the phase boundary; modern aspects of applied chemistry of solutions are discussed [ru

Species and tissue type regulate long-term decomposition of brackish marsh plants grown under elevated CO2 conditions

Science.gov (United States)

Jones, Joshua A; Cherry, Julia A; Mckee, Karen L.

2016-01-01

Organic matter accumulation, the net effect of plant production and decomposition, contributes to vertical soil accretion in coastal wetlands, thereby playing a key role in whether they keep pace with sea-level rise. Any factor that affects decomposition may affect wetland accretion, including atmospheric CO2 concentrations. Higher CO2 can influence decomposition rates by altering plant tissue chemistry or by causing shifts in plant species composition or biomass partitioning. A combined greenhouse-field experiment examined how elevated CO2 affected plant tissue chemistry and subsequent decomposition of above- and belowground tissues of two common brackish marsh species, Schoenoplectus americanus (C3) and Spartina patens (C4). Both species were grown in monoculture and in mixture under ambient (350-385 μL L-1) or elevated (ambient + 300 μL L-1) atmospheric CO2 conditions, with all other growth conditions held constant, for one growing season. Above- and belowground tissues produced under these treatments were decomposed under ambient field conditions in a brackish marsh in the Mississippi River Delta, USA. Elevated CO2 significantly reduced nitrogen content of S. americanus, but not sufficiently to affect subsequent decomposition. Instead, long-term decomposition (percent mass remaining after 280 d) was controlled by species composition and tissue type. Shoots of S. patens had more mass remaining (41 ± 2%) than those of S. americanus (12 ± 2 %). Belowground material decomposed more slowly than that placed aboveground (62 ± 1% vs. 23 ± 3% mass remaining), but rates belowground did not differ between species. Increases in atmospheric CO2concentration will likely have a greater effect on overall decomposition in this brackish marsh community through shifts in species dominance or biomass allocation than through effects on tissue chemistry. Consequent changes in organic matter accumulation may alter marsh capacity to accommodate sea-level rise

Solution chemistry of carbonate minerals and its effects on the flotation of hematite with sodium oleate

Science.gov (United States)

Li, Dong; Yin, Wan-zhong; Xue, Ji-wei; Yao, Jin; Fu, Ya-feng; Liu, Qi

2017-07-01

The effects of carbonate minerals (dolomite and siderite) on the flotation of hematite using sodium oleate as a collector were investigated through flotation tests, supplemented by dissolution measurements, solution chemistry calculations, zeta-potential measurements, Fourier transform infrared (FTIR) spectroscopic studies, and X-ray photoelectron spectroscopy (XPS) analyses. The results of flotation tests show that the presence of siderite or dolomite reduced the recovery of hematite and that the inhibiting effects of dolomite were stronger. Dissolution measurements, solution chemistry calculations, and flotation tests confirmed that both the cations (Ca2+ and Mg2+) and CO3 2- ions dissolved from dolomite depressed hematite flotation, whereas only the CO3 2- ions dissolved from siderite were responsible for hematite depression. The zeta-potential, FTIR spectroscopic, and XPS analyses indicated that Ca2+, Mg2+, and CO3 2- (HCO3 -) could adsorb onto the hematite surface, thereby hindering the adsorption of sodium oleate, which was the main reason for the inhibiting effects of carbonate minerals on hematite flotation.

Thermal decomposition of the Fe17 Sm2 N3 phase

International Nuclear Information System (INIS)

Cabral, F.A.O.; Gama, S.; Morais, E. de; Sanjurjo, N.L.; Ribeiro, C.A.

1996-01-01

We studied the high temperature decomposition mechanism for the Fe 17 Sm 2 N 3 phase using several different experimental techniques, as thermomagnetic and thermogravimetric analyses. Our results slow that the decomposition occurs in a two step scheme. In the first reaction we have the formation of Sm N and a solid solution of nitrogen in iron. In the second step, this solid solution degases, and we observe the evolution of nitrogen over a broad temperature range. (author)

N2O Catalytic Decomposition – from Laboratory Experiment to Industry Reactor

Czech Academy of Sciences Publication Activity Database

Obalová, L.; Jirátová, Květa; Karásková, K.; Chromčáková, Ž.

2012-01-01

Roč. 191, č. 1 (2012), s. 116-120 ISSN 0920-5861 R&D Projects: GA TA ČR TA01020336 Institutional support: RVO:67985858 Keywords : N2O * catalytic decomposition * fixed bed reactor Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.980, year: 2012

Spectral decomposition in advection-diffusion analysis by finite element methods

International Nuclear Information System (INIS)

Nickell, R.E.; Gartling, D.K.; Strang, G.

1978-01-01

In a recent study of the convergence properties of finite element methods in nonlinear fluid mechanics, an indirect approach was taken. A two-dimensional example with a known exact solution was chosen as the vehicle for the study, and various mesh refinements were tested in an attempt to extract information on the effect of the local Reynolds number. However, more direct approaches are usually preferred. In this study one such direct approach is followed, based upon the spectral decomposition of the solution operator. Spectral decomposition is widely employed as a solution technique for linear structural dynamics problems and can be applied readily to linear, transient heat transfer analysis; in this case, the extension to nonlinear problems is of interest. It was shown previously that spectral techniques were applicable to stiff systems of rate equations, while recent studies of geometrically and materially nonlinear structural dynamics have demonstrated the increased information content of the numerical results. The use of spectral decomposition in nonlinear problems of heat and mass transfer would be expected to yield equally increased flow of information to the analyst, and this information could include a quantitative comparison of various solution strategies, meshes, and element hierarchies

Radiation chemistry

International Nuclear Information System (INIS)

Swallow, A.J.

1983-01-01

The subject is covered in chapters, entitled: introduction (defines scope of article as dealing with the chemistry of reactive species, (e.g. excess electrons, excited states, free radicals and inorganic ions in unusual valency states) as studied using radiation with radiation chemistry in its traditional sense and with biological and industrial applications); gases; water and simple inorganic systems; aqueous metallo-organic compounds and metalloproteins; small organic molecules in aqueous solution; microheterogeneous systems; non-aqueous liquids and solutions; solids; biological macromolecules; synthetic polymers. (U.K.)

Foreword - Acid decomposition of borosilicate ores

International Nuclear Information System (INIS)

Mirsaidov, U.M.; Kurbonov, A.S.; Mamatov, E.D.

2015-01-01

The elaboration and development of technology of processing of mineral raw materials have an important role for the industry of Tajikistan. The results of researches of the staff of Institute of Chemistry and Nuclear and Radiation Safety Agency of the Republic of Tajikistan were considered in present monograph. The physicochemical and technological aspects of processing of borosilicate raw materials of Ak-Arkhar Deposit of Tajikistan were considered. The necessary conditions of acid decomposition of raw materials were defined. The flowsheets for the processing of boron raw materials were proposed.

Vector domain decomposition schemes for parabolic equations

Science.gov (United States)

Vabishchevich, P. N.

2017-09-01

A new class of domain decomposition schemes for finding approximate solutions of timedependent problems for partial differential equations is proposed and studied. A boundary value problem for a second-order parabolic equation is used as a model problem. The general approach to the construction of domain decomposition schemes is based on partition of unity. Specifically, a vector problem is set up for solving problems in individual subdomains. Stability conditions for vector regionally additive schemes of first- and second-order accuracy are obtained.

Protective effects of vitamin glycosides on γ-radiation and H2O2-induced decomposition of thymine in aqueous solutions

International Nuclear Information System (INIS)

Shadyro, O.; Lagutin, P.; Edimecheva, I.; Brinkevich, S.; Kagiya, Tsutomu

2008-01-01

Effects of ascorbic acid (AA), ascorbic acid glycoside (AAG) and α-tocopherol monoglycoside (TMG) on radiation- and H 2 O 2 -induced decomposition of thymine in aqueous solutions were investigated. Of the three compounds studied, AAG was found to possess the most marked protector properties. An explanation of this phenomenon has been given in terms of differences in molecular structures of AA and AAG, as well as properties of radical adducts formed during their interaction with OH radicals. (author)

The chemistry of high temperature phosphate solutions in relation to steam generation

International Nuclear Information System (INIS)

Broadbent, D.; Lewis, G.G.; Wetton, E.A.M.

1978-01-01

The problems associated with the use of phosphate for chemical treatment of the P.W.R. secondary circuit have prompted renewed interest in the physical chemistry of these solutions. Solubility and phase studies have been carried out at 250, 300 and 350 0 C with solutions having sodium to phosphate ratios from 1.0 to above 3.0. A solid phase of ratio about 2.8 exists in equilibrium with a wide range of saturated solution compositions at each temperature. Invariant points at which three phases are in equilibrium have been identified and at the two higher temperatures a region of liquid-liquid immiscibility occurs. Phase diagrams have been constructed for each temperature from which it is possible to predict the compositional changes occurring during the isothermal evaporation process. The corrosivity of these phosphate solutions to a range of steel alloys is being studied, the results reported in the present work, however, are confined to mild steel in the temperature and phosphate composition ranges of the phase studies. The corrosion of mild steel is generally considerably less than in sodium hydroxide solutions of equivalent concentration. The dependence of corrosion rate on sodium and phosphate concentrations in not readily explicable in terms of the solubility and phase studies and it is thought that the solubility of iron in the phosphate solutions is an important rate-determining factor since several complex compounds containing sodium, phosphorus and ferrous iron are present in the corrosion films. (author)

Soil solution chemistry and element fluxes in three European heathlands and their responses to warming and drought

DEFF Research Database (Denmark)

Schmidt, I.K.; Tietema, A.; Williams, D.

2004-01-01

Soil water chemistry and element budgets were studied at three northwestern European Calluna vulgaris heathland sites in Denmark (DK), The Netherlands (NL), and Wales (UK). Responses to experimental nighttime warming and early summer drought were followed during a two-year period. Soil solution...

The response of soil solution chemistry in European forests to decreasing acid deposition

DEFF Research Database (Denmark)

Johnson, James; Pannatier, Elisabeth Graf; Carnicelli, Stefano

2018-01-01

to emissions controls. In this study, we assessed the response of soil solution chemistry in mineral horizons of European forests to these changes. Trends in pH, acid neutralizing capacity (ANC), major ions, total aluminium (Altot) and dissolved organic carbon were determined for the period 1995–2012. Plots...... with at least 10 years of observations from the ICP Forests monitoring network were used. Trends were assessed for the upper mineral soil (10–20 cm, 104 plots) and subsoil (40–80 cm, 162 plots). There was a large decrease in the concentration of sulphate () in soil solution; over a 10‐year period (2000...... over the entire dataset. The response of soil solution acidity was nonuniform. At 10–20 cm, ANC increased in acid‐sensitive soils (base saturation ≤10%) indicating a recovery, but ANC decreased in soils with base saturation >10%. At 40–80 cm, ANC remained unchanged in acid‐sensitive soils (base...

Measurement of the energy dependence of X-ray-induced decomposition of potassium chlorate.

Science.gov (United States)

Pravica, Michael; Bai, Ligang; Sneed, Daniel; Park, Changyong

2013-03-21

We report the first measurements of the X-ray induced decomposition of KClO3 as a function of energy in two experiments. KClO3 was pressurized to 3.5 GPa and irradiated with monochromatic synchrotron X-rays ranging in energy from 15 to 35 keV in 5 keV increments. A systematic increase in the decomposition rate as the energy was decreased was observed, which agrees with the 1/E(3) trend for the photoelectric process, except at the lowest energy studied. A second experiment was performed to access lower energies (10 and 12 keV) using a beryllium gasket; suggesting an apparent resonance near 15 keV or 0.83 Ǻ maximizing the chemical decomposition rate. A third experiment was performed using KIO3 to ascertain the anionic dependence of the decomposition rate, which was observed to be far slower than in KClO3, suggesting that the O-O distance is the critical factor in chemical reactions. These results will be important for more efficiently initiating chemical decomposition in materials using selected X-ray wavelengths that maximize decomposition to aid useful hard X-ray-induced chemistry and contribute understanding of the mechanism of X-ray-induced decomposition of the chlorates.

NOx Direct Decomposition: Potentially Enhanced Thermodynamics and Kinetics on Chemically Modified Ferroelectric Surfaces

Science.gov (United States)

Kakekhani, Arvin; Ismail-Beigi, Sohrab

2014-03-01

NOx are regulated pollutants produced during automotive combustion. As part of an effort to design catalysts for NOx decomposition that operate in oxygen rich environment and permit greater fuel efficiency, we study chemistry of NOx on (001) ferroelectric surfaces. Changing the polarization at such surfaces modifies electronic properties and leads to switchable surface chemistry. Using first principles theory, our previous work has shown that addition of catalytic RuO2 monolayer on ferroelectric PbTiO3 surface makes direct decomposition of NO thermodynamically favorable for one polarization. Furthermore, the usual problem of blockage of catalytic sites by strong oxygen binding is overcome by flipping polarization that helps desorb the oxygen. We describe a thermodynamic cycle for direct NO decomposition followed by desorption of N2 and O2. We provide energy barriers and transition states for key steps of the cycle as well as describing their dependence on polarization direction. We end by pointing out how a switchable order parameter of substrate,in this case ferroelectric polarization, allows us to break away from some standard compromises for catalyst design(e.g. the Sabatier principle). This enlarges the set of potentially catalytic metals. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

Decomposition of ammonium nitrate in homogeneous and catalytic denitration

International Nuclear Information System (INIS)

Anan'ev, A. V.; Tananaev, I. G.; Shilov, V. P.

2005-01-01

Ammonium nitrate is one of potentially explosive by-products of spent fuel reprocessing. Decomposition of ammonium nitrate in the HNO 3 -HCOOH system was studied in the presence or absence of Pt/SiO 2 catalyst. It was found that decomposition of ammonium nitrate is due to homogeneous noncatalytic oxidation of ammonium ion with nitrous acid generated in the HNO 3 -HCOOH system during denitration. The platinum catalyst initiates the reaction of HNO 3 with HCOOH to form HNO 2 . The regular trends were revealed and the optimal conditions of decomposition of ammonium nitrate in nitric acid solutions were found [ru

Thermal decomposition pathways of hydroxylamine: theoretical investigation on the initial steps.

Science.gov (United States)

Wang, Qingsheng; Wei, Chunyang; Pérez, Lisa M; Rogers, William J; Hall, Michael B; Mannan, M Sam

2010-09-02

Hydroxylamine (NH(2)OH) is an unstable compound at room temperature, and it has been involved in two tragic industrial incidents. Although experimental studies have been carried out to study the thermal stability of hydroxylamine, the detailed decomposition mechanism is still in debate. In this work, several density functional and ab initio methods were used in conjunction with several basis sets to investigate the initial thermal decomposition steps of hydroxylamine, including both unimolecular and bimolecular reaction pathways. The theoretical investigation shows that simple bond dissociations and unimolecular reactions are unlikely to occur. The energetically favorable initial step of decomposition pathways was determined as a bimolecular isomerization of hydroxylamine into ammonia oxide with an activation barrier of approximately 25 kcal/mol at the MPW1K level of theory. Because hydroxylamine is available only in aqueous solutions, solvent effects on the initial decomposition pathways were also studied using water cluster methods and the polarizable continuum model (PCM). In water, the activation barrier of the bimolecular isomerization reaction decreases to approximately 16 kcal/mol. The results indicate that the bimolecular isomerization pathway of hydroxylamine is more favorable in aqueous solutions. However, the bimolecular nature of this reaction means that more dilute aqueous solution will be more stable.

Molecular Chemistry and Engineering of Boron-Modified Polyorganosilazanes as New Processable and Functional SiBCN Precursors.

Science.gov (United States)

Viard, Antoine; Fonblanc, Diane; Schmidt, Marion; Lale, Abhijeet; Salameh, Chrystelle; Soleilhavoup, Anne; Wynn, Mélanie; Champagne, Philippe; Cerneaux, Sophie; Babonneau, Florence; Chollon, Georges; Rossignol, Fabrice; Gervais, Christel; Bernard, Samuel

2017-07-06

A series of boron-modified polyorganosilazanes was synthesized from a poly(vinylmethyl-co-methyl)silazane and controlled amounts of borane dimethyl sulfide. The role of the chemistry behind their synthesis has been studied in detail by using solid-state NMR spectroscopy, FTIR spectroscopy, and elemental analysis. The intimate relationship between the chemistry and the processability of these polymers is discussed. Polymers with low boron contents displayed appropriate requirements for facile processing in solution, such as impregnation of host carbon materials, which resulted in the design of mesoporous monoliths with a high specific surface area after pyrolysis. Polymers with high boron content are more appropriate for solid-state processing to design mechanically robust monolith-type macroporous and dense structures after pyrolysis. Boron acts as a crosslinking element, which offers the possibility to extend the processability of polyorganosilazanes and suppress the distillation of oligomeric fragments in the low-temperature region of their thermal decomposition (i.e., pyrolysis) at 1000 °C under nitrogen. Polymers with controlled and high ceramic yields were generated. We provide a comprehensive mechanistic study of the two-step thermal decomposition based on a combination of thermogravimetric experiments coupled with elemental analysis, solid-state NMR spectroscopy, and FTIR spectroscopy. Selected characterization tools allowed the investigation of specific properties of the monolith-type SiBCN materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cho decomposition of electrically charged one-half monopole

Energy Technology Data Exchange (ETDEWEB)

Ng, Ban-Loong; Teh, Rosy; Wong, Khai-Ming [School of Physics, Universiti Sains Malaysia, 11800 USM Penang (Malaysia)

2014-03-05

Recently we have carried out some work on the Cho decomposition of the electrically neutral, finite energy one-half monopole solution of the SU(2) Yang-Mills-Higgs field theory. In this paper, we performed the decomposition of the electrically charged solution using the same numerical procedure. The gauge potential of the one-half dyon solution is decomposed into Abelian and non-Abelian components. The semi-infinite string singularity in the gauge potential is a contribution of the Higgs field and hence topological in nature. The string singularity cannot be cancelled by the non-Abelian components of the gauge potential. However, the string singularity is integrable and the energy of the solution is finite. By decomposing the magnetic fields and covariant derivatives of the Higgs field into three isospin space directions, we are able to provide conclusive evidence that the constructed one-half dyon is certainly a non-BPS solution even in the limit of vanishing Higgs self-coupling constant and electric charge. Furthermore, we found that the time component of gauge function is parallel to the Higgs field in isospace only at large distances, elsewhere they are non-parallel.

Effects of simulated acid rain on soil and soil solution chemistry in a monsoon evergreen broad-leaved forest in southern China.

Science.gov (United States)

Qiu, Qingyan; Wu, Jianping; Liang, Guohua; Liu, Juxiu; Chu, Guowei; Zhou, Guoyi; Zhang, Deqiang

2015-05-01

Acid rain is an environmental problem of increasing concern in China. In this study, a laboratory leaching column experiment with acid forest soil was set up to investigate the responses of soil and soil solution chemistry to simulated acid rain (SAR). Five pH levels of SAR were set: 2.5, 3.0, 3.5, 4.0, and 4.5 (as a control, CK). The results showed that soil acidification would occur when the pH of SAR was ≤3.5. The concentrations of NO₃(-)and Ca(2+) in the soil increased significantly when the pH of SAR fell 3.5. The concentration of SO₄(2-) in the soil increased significantly when the pH of SAR was soil solution chemistry became increasingly apparent as the experiment proceeded (except for Na(+) and dissolved organic carbon (DOC)). The net exports of NO₃(-), SO₄(2-), Mg(2+), and Ca(2+) increased about 42-86% under pH 2.5 treatment as compared to CK. The Ca(2+) was sensitive to SAR, and the soil could release Ca(2+) through mineral weathering to mitigate soil acidification. The concentration of exchangeable Al(3+) in the soil increased with increasing the acidity of SAR. The releases of soluble Al and Fe were SAR pH dependent, and their net exports under pH 2.5 treatment were 19.6 and 5.5 times, respectively, higher than that under CK. The net export of DOC was reduced by 12-29% under SAR treatments as compared to CK. Our results indicate the chemical constituents in the soil are more sensitive to SAR than those in the soil solution, and the effects of SAR on soil solution chemistry depend not only on the intensity of SAR but also on the duration of SAR addition. The soil and soil solution chemistry in this region may not be affected by current precipitation (pH≈4.5) in short term, but the soil and soil leachate chemistry may change dramatically if the pH of precipitation were below 3.5 and 3.0, respectively.

Atmospheric chemistry of CF3C(O)O2 radicals. Kinetics of their reaction with NO2 and kinetics of the thermal decomposition of the product CF3C(O)O2NO2

DEFF Research Database (Denmark)

Wallington, T.J.; Sehested, J.; Nielsen, O.J.

1994-01-01

A pulse radiolysis technique has been used to measure a rate constant of (6.6 +/- 1.3) x 10(-12) cm3 molecule-1 s-1 for the association reaction between CF3C(O)O2 radicals and NO2 at 295 K and one atmosphere total pressure of SF6 diluent. A FTIR/smog chamber system was used to study the thermal...... decomposition CF3C(O)O2NO2. The rate of decomposition of CF3C(O)O2NO2 was independent of the total pressure of N2 diluent over the range 100-700 Torr and was fit by the expression k-1 = (1.9(-1.5)+7.6) x 10(16) exp[(-14000 +/- 480)/T] s-1. Implications for the atmospheric chemistry of CFC replacements...

Multiple Shooting and Time Domain Decomposition Methods

CERN Document Server

Geiger, Michael; Körkel, Stefan; Rannacher, Rolf

2015-01-01

This book offers a comprehensive collection of the most advanced numerical techniques for the efficient and effective solution of simulation and optimization problems governed by systems of time-dependent differential equations. The contributions present various approaches to time domain decomposition, focusing on multiple shooting and parareal algorithms.  The range of topics covers theoretical analysis of the methods, as well as their algorithmic formulation and guidelines for practical implementation. Selected examples show that the discussed approaches are mandatory for the solution of challenging practical problems. The practicability and efficiency of the presented methods is illustrated by several case studies from fluid dynamics, data compression, image processing and computational biology, giving rise to possible new research topics.  This volume, resulting from the workshop Multiple Shooting and Time Domain Decomposition Methods, held in Heidelberg in May 2013, will be of great interest to applied...

Chemistry of americium

Energy Technology Data Exchange (ETDEWEB)

Schulz, W.W.

1976-01-01

Essential features of the descriptive chemistry of americium are reviewed. Chapter titles are: discovery, atomic and nuclear properties, collateral reading, production and uses, chemistry in aqueous solution, metal, alloys, and compounds, and, recovery, separation, purification. Author and subject indexes are included. (JCB)

Adomian decomposition method for solving the telegraph equation in charged particle transport

International Nuclear Information System (INIS)

Abdou, M.A.

2005-01-01

In this paper, the analysis for the telegraph equation in case of isotropic small angle scattering from the Boltzmann transport equation for charged particle is presented. The Adomian decomposition is used to solve the telegraph equation. By means of MAPLE the Adomian polynomials of obtained series (ADM) solution have been calculated. The behaviour of the distribution function are shown graphically. The results reported in this article provide further evidence of the usefulness of Adomain decomposition for obtaining solution of linear and nonlinear problems

Thermoanalytical study of the decomposition of yttrium trifluoroacetate thin films

International Nuclear Information System (INIS)

Eloussifi, H.; Farjas, J.; Roura, P.; Ricart, S.; Puig, T.; Obradors, X.; Dammak, M.

2013-01-01

We present the use of the thermal analysis techniques to study yttrium trifluoroacetate thin films decomposition. In situ analysis was done by means of thermogravimetry, differential thermal analysis, and evolved gas analysis. Solid residues at different stages and the final product have been characterized by X-ray diffraction and scanning electron microscopy. The thermal decomposition of yttrium trifluoroacetate thin films results in the formation of yttria and presents the same succession of intermediates than powder's decomposition, however, yttria and all intermediates but YF 3 appear at significantly lower temperatures. We also observe a dependence on the water partial pressure that was not observed in the decomposition of yttrium trifluoroacetate powders. Finally, a dependence on the substrate chemical composition is discerned. - Highlights: • Thermal decomposition of yttrium trifluoroacetate films. • Very different behavior of films with respect to powders. • Decomposition is enhanced in films. • Application of thermal analysis to chemical solution deposition synthesis of films

The latest general chemistry

International Nuclear Information System (INIS)

Ryu, Geun Bae; Choi, Se Yeong; Kim, Chin Yeong; Yoon, Gil Jung; Lee, Eun Seok; Seo, Moon Gyu

1995-02-01

This book deals with the latest general chemistry, which is comprised of twenty-three chapters, the contents of this book are introduction, theory of atoms and molecule, chemical formula and a chemical reaction formula, structure of atoms, nature of atoms and the periodic table, structure of molecule and spectrum, gas, solution, solid, chemical combination, chemical reaction speed, chemical equilibrium, thermal chemistry, oxidation-reduction, electrochemistry, acid-base, complex, aquatic chemistry, air chemistry, nuclear chemistry, metal and nonmetal, organic chemistry and biochemistry. It has exercise in the end of each chapter.

Ultrasound in polymer chemistry : revival of an established technique

NARCIS (Netherlands)

Paulusse, J.M.J.; Sijbesma, R.P.

2006-01-01

The history of ultrasound in polymer chemistry goes back a long way. Initially, its uses were limited to being an alternative method of initiating radical polymerizations through the decomposition of solvents to form radicals or through the breakage of polymers leading to macroradicals. Recently,

Thermal Decomposition of Sodium Hydrogen Carbonate and Textural Features of Its Calcines

Czech Academy of Sciences Publication Activity Database

Hartman, Miloslav; Svoboda, Karel; Pohořelý, Michael; Šyc, Michal

2013-01-01

Roč. 52, č. 31 (2013), s. 10619-10626 ISSN 0888-5885 R&D Projects: GA MŠk(CZ) 7C11009 Grant - others:RFCS(XE) RFCR-CT-2010-00009 Institutional support: RVO:67985858 Keywords : thermal decomposition * sodium hydrogen carbonate * sodium bicarbonate Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.235, year: 2013

Simulation of radiation-induced ozone decomposition in water in the presence of organic compounds

International Nuclear Information System (INIS)

Arai, H.; Namba, H.; Miyata, T.; Arai, M.; Sakumoto, A.; Sunaga, H.

1995-01-01

Ozone decomposition in water by electron beam irradiation in the presence of acetic acid and t-butanol was studied by the direct measurement of ozone concentration using a spectroscopy equipped with optical fiber light guides and the computer simulation based on 80 reactions. The calculated data were in fair agreement with the observed data for acetic acid aq. solution. For t-butanol high concentration aq. solution, the calculated data became closer to the observed data when the decomposition of peroxide were assumed to occur to produce HO 2 or O 2 - . At low concentration of the organic solutes, the presence of HCO 3 - or CO 3 2- disturbs the ozone decomposition substantially. The concentrations of active species such as OH radicals during the irradiation were also estimated from the simulation. (author)

Photocatalytic Decomposition of N2O on Ag-TiO2

Czech Academy of Sciences Publication Activity Database

Kočí, K.; Krejčíková, Simona; Šolcová, Olga; Obalová, L.

2012-01-01

Roč. 191, č. 1 (2012), s. 134-137 ISSN 0920-5861. [International Symposium on Nitrogen Oxides Emission Abatement. Zakopane, 04.09.2011-07.09.2011] R&D Projects: GA ČR GA104/09/0694 Institutional support: RVO:67985858 Keywords : photocatalytic decomposition * N2O * Ag doping * TiO2 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.980, year: 2012

The New Color of Chemistry: Green Chemistry

OpenAIRE

Zuhal GERÇEK

2012-01-01

Green chemistry which is the new application of chemistry rules provides solutions to problems that mankind is faced with climate changes, sustainable agriculture, energy, toxics, depletion of natural sources e.g. designing new chemicals and processes that production and utilization of hazardous matters. So, it is the indispensible tool for sustainable development. Current and future chemists should consider the human health and ecological issues in their professional life. In order to provid...

Variational methods for direct/inverse problems of atmospheric dynamics and chemistry

Science.gov (United States)

Penenko, Vladimir; Penenko, Alexey; Tsvetova, Elena

2013-04-01

We present a variational approach for solving direct and inverse problems of atmospheric hydrodynamics and chemistry. It is important that the accurate matching of numerical schemes has to be provided in the chain of objects: direct/adjoint problems - sensitivity relations - inverse problems, including assimilation of all available measurement data. To solve the problems we have developed a new enhanced set of cost-effective algorithms. The matched description of the multi-scale processes is provided by a specific choice of the variational principle functionals for the whole set of integrated models. Then all functionals of variational principle are approximated in space and time by splitting and decomposition methods. Such approach allows us to separately consider, for example, the space-time problems of atmospheric chemistry in the frames of decomposition schemes for the integral identity sum analogs of the variational principle at each time step and in each of 3D finite-volumes. To enhance the realization efficiency, the set of chemical reactions is divided on the subsets related to the operators of production and destruction. Then the idea of the Euler's integrating factors is applied in the frames of the local adjoint problem technique [1]-[3]. The analytical solutions of such adjoint problems play the role of integrating factors for differential equations describing atmospheric chemistry. With their help, the system of differential equations is transformed to the equivalent system of integral equations. As a result we avoid the construction and inversion of preconditioning operators containing the Jacobi matrixes which arise in traditional implicit schemes for ODE solution. This is the main advantage of our schemes. At the same time step but on the different stages of the "global" splitting scheme, the system of atmospheric dynamic equations is solved. For convection - diffusion equations for all state functions in the integrated models we have developed the

A time-domain decomposition iterative method for the solution of distributed linear quadratic optimal control problems

Science.gov (United States)

Heinkenschloss, Matthias

2005-01-01

We study a class of time-domain decomposition-based methods for the numerical solution of large-scale linear quadratic optimal control problems. Our methods are based on a multiple shooting reformulation of the linear quadratic optimal control problem as a discrete-time optimal control (DTOC) problem. The optimality conditions for this DTOC problem lead to a linear block tridiagonal system. The diagonal blocks are invertible and are related to the original linear quadratic optimal control problem restricted to smaller time-subintervals. This motivates the application of block Gauss-Seidel (GS)-type methods for the solution of the block tridiagonal systems. Numerical experiments show that the spectral radii of the block GS iteration matrices are larger than one for typical applications, but that the eigenvalues of the iteration matrices decay to zero fast. Hence, while the GS method is not expected to convergence for typical applications, it can be effective as a preconditioner for Krylov-subspace methods. This is confirmed by our numerical tests.A byproduct of this research is the insight that certain instantaneous control techniques can be viewed as the application of one step of the forward block GS method applied to the DTOC optimality system.

Chemistry That Applies. What Works Clearinghouse Intervention Report

Science.gov (United States)

What Works Clearinghouse, 2012

2012-01-01

"Chemistry That Applies" is an instructional unit designed to help students in grades 8-10 understand the law of conservation of matter. It consists of 24 lessons organized in four clusters. Working in groups, students explore four chemical reactions: burning, rusting, the decomposition of water, and the reaction of baking soda and…

Physical Properties and Thermal Decomposition of Aqueous Solutions of 2-Amino-2-hydroxymethyl-1, 3-propanediol (AHPD)

Science.gov (United States)

Murshid, Ghulam; Shariff, Azmi Mohd; Lau, K. K.; Bustam, Mohammad Azmi; Ahmad, Faizan

2011-10-01

Physical properties such as density, viscosity, refractive index, surface tension, and thermal stability of 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD) were experimentally measured. All the experimental measurements were made over a wide range of temperatures from (298.15 to 333.15) K and AHPD concentrations of (1, 7, 13, 19, and 25) mass%. An overall decrease in all the measured physical properties was observed with increasing temperature. The experimental results are presented as a function of temperature and AHPD mass fraction. All the measured physical properties were correlated as a function of temperature. Thermal decomposition of pure and aqueous solutions of AHPD was investigated using a thermo-gravimetric analyzer (TGA) at a heating rate of 10 K · min-1.

Modelling of nitric and nitrous acid chemistry for solvent extraction purposes

Energy Technology Data Exchange (ETDEWEB)

McKenzie, H.; McLachlan, F. [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); MacDonald-Taylor, J. [National Nuclear Laboratory, 5th Floor, Chadwick House, Warrington Road, Birchwood Park, Warrington, WA3 6AE (United Kingdom); Orr, R.; Woodhead, D. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom)

2016-07-01

Nitric acid plays an integral role in the reprocessing of irradiated fuel. It is well known that nitric acid degrades; its often yellow hue signifies the presence of decomposition products. The decomposition of nitric acid is accelerated by temperature and radiolysis; therefore it is an important consideration in the reprocessing of nuclear fuels. Thermal and radiolytic reactions of nitric acid result in the formation of redox active nitrogen species, of which nitrous acid is of particular concern, largely due to its redox reactions with plutonium and neptunium. Such reactions are important to understand as plutonium and neptunium can exist in a number of oxidation states; the oxidation state has a direct effect on the species extractability. The effect of nitrous acid is exacerbated as it catalyzes its own production and its reactions with actinides are typically autocatalytic; thus even micromolar quantities can have a large effect. A full understanding of solvent extraction requires us to understand actinide valence states which in turn require us to understand what nitrogen species are present and their concentrations. As a first step in the overall objective of enhancing process models, the kinetic data for nitric acid decomposition reactions has been investigated in order to produce an initial dynamic model of decomposition under aqueous conditions. The identification of a set of kinetic reactions suitable for modelling has been the primary focus of this work. A model of nitric acid thermal decomposition will help develop a better understanding of nitric acid decomposition chemistry and enable better prediction of the oxidation states of species in solution. It is intended to later extend the model to include radiolytic reactions and then further to incorporate an organic phase in order to have a model which covers all decomposition routes for nitric acid within a nuclear fuel reprocessing scheme. The model will be used as a sub model for process models

An evaluation of selection criteria on primary water chemistry parameters for SMART

International Nuclear Information System (INIS)

Choi, B. S.; Kim, S. H.; Yun, J. H.; Bae, Y. Y.; Gee, S. G.

2003-01-01

The selection criteria on the primary water chemistry of SMART by comparing the chemical design features with those of the current operating PWRs is analyzed. The most essential differences in water chemistry between the PWRs and SMART reactor is characterized by the presence of boron in water. SMART is boron free reactor, and the ammonia is used as a pH reagent. In SMART reactor hydrogen gas is not added to the primary coolant, but is normally generated from the radiolysis of ammonia of the coolant passes through the core. Ammonia is added once per shift because SMART reactor has no letdown and charging system during power operation. Because of these competing processes, the concentrations of hydrogen, nitrogen and ammonia in the primary coolant are steady state concentrations, which depend on the decomposition/combination rate of ammonia. Ammonia chemistry in SMART reactor has many advantages in that no hydrogen gas injection is needed to control the dissolved oxygen in primary coolant because of spontaneous generation of hydrogen and nitrogen produced by the reaction of ammonia decomposition

AECL research programs in chemistry

International Nuclear Information System (INIS)

Crocker, I.H.; Eastwood, T.A.; Smith, D.R.; Stewart, R.B.; Tomlinson, M.; Torgerson, D.F.

1980-09-01

Fundamental or underlying research in chemistry is being done in AECL laboratories to further the understanding of processes involved in current nuclear energy systems and maintain an awareness of progress at the frontiers of chemical research so that new advances can be turned to advantage in future AECL endeavours. The report introduces the current research topics and describes them briefly under the following headings: radiation chemistry, isotope separation, high temperature solution chemistry, fuel reprocessing chemistry, and analytical chemistry. (auth)

The Adomian decomposition method for solving partial differential equations of fractal order in finite domains

Energy Technology Data Exchange (ETDEWEB)

El-Sayed, A.M.A. [Faculty of Science University of Alexandria (Egypt)]. E-mail: amasyed@hotmail.com; Gaber, M. [Faculty of Education Al-Arish, Suez Canal University (Egypt)]. E-mail: mghf408@hotmail.com

2006-11-20

The Adomian decomposition method has been successively used to find the explicit and numerical solutions of the time fractional partial differential equations. A different examples of special interest with fractional time and space derivatives of order {alpha}, 0<{alpha}=<1 are considered and solved by means of Adomian decomposition method. The behaviour of Adomian solutions and the effects of different values of {alpha} are shown graphically for some examples.

Newton-Raphson based modified Laplace Adomian decomposition method for solving quadratic Riccati differential equations

Directory of Open Access Journals (Sweden)

Mishra Vinod

2016-01-01

Full Text Available Numerical Laplace transform method is applied to approximate the solution of nonlinear (quadratic Riccati differential equations mingled with Adomian decomposition method. A new technique is proposed in this work by reintroducing the unknown function in Adomian polynomial with that of well known Newton-Raphson formula. The solutions obtained by the iterative algorithm are exhibited in an infinite series. The simplicity and efficacy of method is manifested with some examples in which comparisons are made among the exact solutions, ADM (Adomian decomposition method, HPM (Homotopy perturbation method, Taylor series method and the proposed scheme.

Transport of E. coli D21g with runoff water under different solution chemistry conditions and surface slopes

Science.gov (United States)

Tracer and indicator microbe runoff experiments were conducted to investigate the influence of solution chemistry on the transport, retention, and release of Escherichia coli D21g. Experiments were conducted in a chamber (2.25 m long, 0.15 m wide, and 0.16 m high) packed with ultrapure quartz sand (...

Effect of noble metals in the decomposition of nitrous oxide over Fe-ferrierites

Czech Academy of Sciences Publication Activity Database

Sobalík, Zdeněk; Jíša, Kamil; Kaucký, Dalibor; Vondrová, Alena; Tvarůžková, Zdenka; Nováková, Jana

2007-01-01

Roč. 113, 3-4 (2007), s. 124-129 ISSN 1011-372X R&D Projects: GA AV ČR 1ET400400413 Institutional research plan: CEZ:AV0Z40400503 Keywords : Fe, Pt, Rh, Ru-ferrierite * synergy effects in Fe/Me-ferrierites * N2O decomposition Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.883, year: 2007

Computational chemistry

Science.gov (United States)

Arnold, J. O.

1987-01-01

With the advent of supercomputers, modern computational chemistry algorithms and codes, a powerful tool was created to help fill NASA's continuing need for information on the properties of matter in hostile or unusual environments. Computational resources provided under the National Aerodynamics Simulator (NAS) program were a cornerstone for recent advancements in this field. Properties of gases, materials, and their interactions can be determined from solutions of the governing equations. In the case of gases, for example, radiative transition probabilites per particle, bond-dissociation energies, and rates of simple chemical reactions can be determined computationally as reliably as from experiment. The data are proving to be quite valuable in providing inputs to real-gas flow simulation codes used to compute aerothermodynamic loads on NASA's aeroassist orbital transfer vehicles and a host of problems related to the National Aerospace Plane Program. Although more approximate, similar solutions can be obtained for ensembles of atoms simulating small particles of materials with and without the presence of gases. Computational chemistry has application in studying catalysis, properties of polymers, all of interest to various NASA missions, including those previously mentioned. In addition to discussing these applications of computational chemistry within NASA, the governing equations and the need for supercomputers for their solution is outlined.

Green Chemistry

Energy Technology Data Exchange (ETDEWEB)

Collison, Melanie

2011-05-15

Green chemistry is the science of chemistry used in a way that will not use or create hazardous substances. Dr. Rui Resendes is working in this field at GreenCentre Canada, an offshoot of PARTEQ Innovations in Kingston, Ontario. GreenCentre's preliminary findings suggest their licensed product {sup S}witchable Solutions{sup ,} featuring 3 classes of solvents and a surfactant, may be useful in bitumen oil sands extraction.

Chemistry of plutonium revealed

International Nuclear Information System (INIS)

Connick, R.E.

1992-01-01

In 1941 one goal of the Manhattan Project was to unravel the chemistry of the synthetic element plutonium as rapidly as possible. In this paper the work carried out at Berkeley from the spring of 1942 to the summer of 1945 is described briefly. The aqueous chemistry of plutonium is quite remarkable. Important insights were obtained from tracer experiments, but the full complexity was not revealed until macroscopic amounts (milligrams) became available. Because processes for separation from fission products were based on aqueous solutions, such solution chemistry was emphasized, particularly precipitation and oxidation-reduction behavior. The latter turned out to be unusually intricate when it was discovered that two more oxidation states existed in aqueous solution than had previously been suspected. Further, an equilibrium was rapidly established among the four aqueous oxidation states, while at the same time any three were not in equilibrium. These and other observations made while doing a crash study of a previously unknown element are reported

Water chemistry at RBMK plants: Problems and solutions

International Nuclear Information System (INIS)

Mamet, V.; Yurmanov, V.

2002-01-01

After around 15 years of operation RBMK-1000 units undergo a major refit, which includes safety system upgrading, fuel tube replacement, etc. The above upgrading has created problems for water chemistry. In particular, in late 80's in-core insertion time of the portion of control rods was reduced 10-fold thanks to a transfer from water to filming cooling of scram channels. Scram channels are cooled with inner surface water film cooling and nitrogen is injected into heads via special pipelines. Such cooling system modernization ensures fast insertion of absorber rods. The above upgrade intensified nitric acid radiolytic generation in water coolant and pH 25 value shift to acid conditions (up to 4.5). The results of corrosion tests in such conditions proved the necessity to improve water chemistry to ensure corrosion protection of scram/control rod and circuit components, especially those made out of aluminium alloy. Since 1990 the new revision of the RBMK-1000 water chemistry standard specified the new normal operational limit and action levels for possible temporary deviations of pH 25 value. RBMK plant specific measures were implemented at RBMK plants to meet the above requirements of the 1990 revision of the RBMK-1000 water chemistry standard. Clean-up systems of the above circuit were upgraded to ensure intensive absorption of nitric acid from water and pH 25 maintenance in a slightly acid area. (authors)

Water chemistry at RBMK plants: Problems and solutions

Energy Technology Data Exchange (ETDEWEB)

Mamet, V.; Yurmanov, V. [VNIIAES (Russian Federation)

2002-07-01

After around 15 years of operation RBMK-1000 units undergo a major refit, which includes safety system upgrading, fuel tube replacement, etc. The above upgrading has created problems for water chemistry. In particular, in late 80's in-core insertion time of the portion of control rods was reduced 10-fold thanks to a transfer from water to filming cooling of scram channels. Scram channels are cooled with inner surface water film cooling and nitrogen is injected into heads via special pipelines. Such cooling system modernization ensures fast insertion of absorber rods. The above upgrade intensified nitric acid radiolytic generation in water coolant and pH{sub 25} value shift to acid conditions (up to 4.5). The results of corrosion tests in such conditions proved the necessity to improve water chemistry to ensure corrosion protection of scram/control rod and circuit components, especially those made out of aluminium alloy. Since 1990 the new revision of the RBMK-1000 water chemistry standard specified the new normal operational limit and action levels for possible temporary deviations of pH{sub 25} value. RBMK plant specific measures were implemented at RBMK plants to meet the above requirements of the 1990 revision of the RBMK-1000 water chemistry standard. Clean-up systems of the above circuit were upgraded to ensure intensive absorption of nitric acid from water and pH{sub 25} maintenance in a slightly acid area. (authors)

Effect of β-phase decomposition on the superconducting properties of Ti-27 at percent Nb solid solution

International Nuclear Information System (INIS)

Hariharan, Y.; Valsakumar, M.C.; Radhakrishnan, T.S.

1980-01-01

The effect of β-phase decomposition on the superconducting transition temperature (Tsub(c)) of a Ti-27 at % Nb solid solution has been studied by the resistive technique. The samples were β-quenched from 900deg C and cold rolled to 30%. Annealing at 400deg C for various times upto 15 hours causes Ti-rich phases to precipitate out of the matrix. This decomposition of the β-phase is seen to lead to a progressive enhancement in Tsub(c) from 7.7 K in the β-quenched state to 8.8 K in the sample annealed for 15 hours; further, the width Δ Tsub(c) of the superconducting transition (=90 mK in the β-quenched state) reaches a maximum value (360 mK) for a 10-hour anneal. The conjecture that the enhancement in Tsub(c) occurs as a result of precipitation and the consequent enrichment of the Nb content of the matrix is examined. It is estimated that to account for the large observed enhancement of Tsub(c), the Nb enrichment would have to be of the order of 5-6%; whereas a TEM study has revealed the enrichment to be of the order of 0.2% only. Analysis of the X-ray diffractograms is also not in favour of this hypothesis. Hence alternative mechanisms to account for the Tsub(c) enhancement are currently under investigation. Also discussed is the calculation of Tsub(c) using McMillan's formula for strongly coupled superconductors. (author)

Approaches to understanding the semi-stable phase of litter decomposition

Science.gov (United States)

Preston, C. M.; Trofymow, J. A.

2012-12-01

The slowing or even apparent cessation of litter decomposition with time has been widely observed, but causes remain poorly understood. We examine the question in part through data from CIDET (the Canadian Intersite Decomposition Experiment) for 10 foliar litters at one site with MAT 6.7 degrees C. The initial rapid C loss in the first year for some litters is followed by a second phase (1-7y) with decay rates from 0.21-0.79/y, influenced by initial litter chemistry especially the ratio AUR/N (acid-unhydrolyzable residue, negative). By contrast, 10-23% of the initial litter C mass entered the semi-stable decay phase (>7 y) with modeled decay rates of 0.0021-0.0035/y. The slowing and convergence of k values was similar to trends in chemical composition. From 7-12 y, concentrations of Ca, Mg, K, P, Mn and Zn generally declined and became more similar among litters, and total N converged around 20 mg/g. Non-polar and water-soluble extractables and acid solubles continued to decrease slowly and AUR to increase. Solid-state C-13 NMR showed continuing slight declines in O- and di-O-alkyl C and increases in alkyl, methoxyl, aryl and carboxyl C. CIDET and other studies now clearly show that lignin is not selectively preserved, and that AUR is not a measure of foliar lignin as it includes components from condensed tannins and long-chain alkyl C. Interaction with soil minerals strongly enhances soil C stabilization, but what slows decomposition so much in organic horizons? The role of inherent "chemical recalcitrance" or possible formation of new covalent bonds is hotly debated in soil science, but increasingly complex or random molecular structures no doubt present greater challenges to enzymes. A relevant observation from soils and geochemistry is that decomposition results in a decline in individual compounds that can be identified from chemical analysis and a corresponding increase in the "molecularly uncharacterizable component" (MUC). Long-term declines in Ca, Mg, K

Rayleigh-Schrödinger series and Birkhoff decomposition

Science.gov (United States)

Novelli, Jean-Christophe; Paul, Thierry; Sauzin, David; Thibon, Jean-Yves

2018-01-01

We derive new expressions for the Rayleigh-Schrödinger series describing the perturbation of eigenvalues of quantum Hamiltonians. The method, somehow close to the so-called dimensional renormalization in quantum field theory, involves the Birkhoff decomposition of some Laurent series built up out of explicit fully non-resonant terms present in the usual expression of the Rayleigh-Schrödinger series. Our results provide new combinatorial formulae and a new way of deriving perturbation series in quantum mechanics. More generally we prove that such a decomposition provides solutions of general normal form problems in Lie algebras.

The chemistry of plutonium revealed

International Nuclear Information System (INIS)

Connick, R.E.

1990-01-01

In 1941 one goal of the Manhattan Project was to unravel the chemistry of the synthetic element plutonium as rapidly as possible. Important insights were obtained from tracer experiments, but the full complexity of plutonium chemistry was not revealed until macroscopic amounts (milligrams) became available. Because processes for separation from fission products were aqueous solution based, such solution chemistry was emphasized, particularly precipitation and oxidation-reduction behavior. The latter turned out to be unusually intricate when it was discovered that two more oxidation states existed in aqueous solution than had previously been suspected. Further, it was found that an equilibrium was rapidly established among the four aqueous oxidation states while at the same time any three were not in equilibrium. These and other observations made while doing a crash study of a previously unknown element will be reported

Ammonia chemistry in a flameless jet

Energy Technology Data Exchange (ETDEWEB)

Zieba, Mariusz; Schuster, Anja; Scheffknecht, Guenter [Institute of Process Engineering and Power Plant Technology, University of Stuttgart, Pfaffenwaldring 23, D-70569 Stuttgart (Germany); Brink, Anders; Hupa, Mikko [Process Chemistry Centre, Aabo Akademi University, Biskopsgatan 8, 20500 Aabo (Finland)

2009-10-15

In this paper, the nitrogen chemistry in an ammonia (NH{sub 3}) doped flameless jet is investigated using a kinetic reactor network model. The reactor network model is used to explain the main differences in ammonia chemistry for methane (CH{sub 4})-containing fuels and methane-free fuels. The chemical pathways of nitrogen oxides (NO{sub x}) formation and destruction are identified using rate-of-production analysis. The results show that in the case of natural gas, ammonia reacts relatively late at fuel lean condition leading to high NO{sub x} emissions. In the pre-ignition zone, the ammonia chemistry is blocked due to the absence of free radicals which are consumed by methane-methyl radical (CH{sub 3}) conversion. In the case of methane-free gas, the ammonia reacted very rapidly and complete decomposition was reached in the fuel rich region of the jet. In this case the necessary radicals for the ammonia conversion are generated from hydrogen (H{sub 2}) oxidation. (author)

Chemistry and Heritage

Science.gov (United States)

Vittoria Barbarulo, Maria

2014-05-01

Chemistry is the central science, as it touches every aspect of the society we live in and it is intertwined with many aspects of our culture; in particular, the strong link between Chemistry and Archaeology and Art History is being explored, offering a penetrating insight into an area of growing interest from an educational point of view. A series of vital and vibrant examples (i.e., ancient bronzes composition, colour changes due to natural pigment decomposition, marble degradation) has been proposed, on one hand, to improve student understanding of the relationship between cultural and scientific issues arising from the examination, the conservation, and the maintenance of cultural Heritage, on the other, to illustrate the role of the underlying Chemistry. In some case studies, a survey of the most relevant atmospheric factors, which are involved in the deterioration mechanisms, has also been presented to the students. First-hand laboratory experiences have been providing an invaluable means of discovering the full and varied world of Chemistry. Furthermore, the promotion of an interdisciplinary investigation of a famous painting or fresco, involving the study of its nature and significance, the definition of its historical context, any related literature, the chemical knowledge of the materials used, may be an excellent occasion to experiment the Content and Language Integrated Learning (CLIL). The aim of this approach is to convey the important message that everyone has the responsibility to care for and preserve Heritage for the benefit of present and future generations.

Effect of Promoters in Co-Mn-Al Mixed Oxide Catalyst on N2O Decomposition

Czech Academy of Sciences Publication Activity Database

Karásková, K.; Obalová, L.; Jirátová, Květa; Kovanda, F.

2010-01-01

Roč. 160, č. 2 (2010), s. 480-487 ISSN 1385-8947 R&D Projects: GA ČR GA106/09/1664 Institutional research plan: CEZ:AV0Z40720504 Keywords : nitrous oxide * catalytic decomposition * promoter effect Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.074, year: 2010

Investigation of decomposition of solid solution of Ni-Cr-Fe 77/16/7 over-saturated in carbon during tempering at various temperatures

International Nuclear Information System (INIS)

Duffaut, Francois

1966-01-01

In its first part, this research thesis reports the investigation of the structure of the tempered Ni-Cr-Fe 77/16/7 alloy by using optical and electronic microscopy. The second part addresses the relationship between the structural status of the alloy and its electrochemical behaviour. The third part reports the investigation of the Portevin - Le Chatelier phenomenon in relationship with the decomposition of the solid solution. A last part addresses the investigation of a possible microstructure ordering of the Ni-Cr-Fe 77/16/7 alloy

Bregmanized Domain Decomposition for Image Restoration

KAUST Repository

Langer, Andreas

2012-05-22

Computational problems of large-scale data are gaining attention recently due to better hardware and hence, higher dimensionality of images and data sets acquired in applications. In the last couple of years non-smooth minimization problems such as total variation minimization became increasingly important for the solution of these tasks. While being favorable due to the improved enhancement of images compared to smooth imaging approaches, non-smooth minimization problems typically scale badly with the dimension of the data. Hence, for large imaging problems solved by total variation minimization domain decomposition algorithms have been proposed, aiming to split one large problem into N > 1 smaller problems which can be solved on parallel CPUs. The N subproblems constitute constrained minimization problems, where the constraint enforces the support of the minimizer to be the respective subdomain. In this paper we discuss a fast computational algorithm to solve domain decomposition for total variation minimization. In particular, we accelerate the computation of the subproblems by nested Bregman iterations. We propose a Bregmanized Operator Splitting-Split Bregman (BOS-SB) algorithm, which enforces the restriction onto the respective subdomain by a Bregman iteration that is subsequently solved by a Split Bregman strategy. The computational performance of this new approach is discussed for its application to image inpainting and image deblurring. It turns out that the proposed new solution technique is up to three times faster than the iterative algorithm currently used in domain decomposition methods for total variation minimization. © Springer Science+Business Media, LLC 2012.

Effect of neutron irradiation on the cellular stage of Ni-Be alloy decomposition

International Nuclear Information System (INIS)

Larikov, L.N.; Borimskaya, S.T.

1981-01-01

Effects of neutron irradiation on the cellular stage of decomposition are investigated in deformed supersaturated solid solution Ni-1.92%Be by the X-ray structural and metallographic analyses. Radiation-initiated stimulation of the recovery properties in the deformed alloy and a lower rate of the cellular decomposition in irradiated samples are discovered [ru

Root chemistry and soil fauna, but not soil abiotic conditions explain the effects of plant diversity on root decomposition

NARCIS (Netherlands)

Chen, Hongmei; Oram, Natalie J.; Barry, Kathryn E.; Mommer, Liesje; Ruijven, van Jasper; Kroon, de Hans; Ebeling, Anne; Eisenhauer, Nico; Fischer, Christine; Gleixner, Gerd; Gessler, Arthur; González Macé, Odette; Hacker, Nina; Hildebrandt, Anke; Lange, Markus; Scherer-lorenzen, Michael; Scheu, Stefan; Oelmann, Yvonne; Wagg, Cameron; Wilcke, Wolfgang; Wirth, Christian; Weigelt, Alexandra

2017-01-01

Plant diversity influences many ecosystem functions including root decomposition. However, due to the presence of multiple pathways via which plant diversity may affect root decomposition, our mechanistic understanding of their relationships is limited. In a grassland biodiversity experiment, we

Introduction - Acid decomposition of borosilicate ores

International Nuclear Information System (INIS)

Mirsaidov, U.M.; Kurbonov, A.S.; Mamatov, E.D.

2015-01-01

The complex processing of mineral raw materials is an effective way for the extraction of valuable components. One of these raw materials are borosilicate ores from which the boric acid, aluminium and iron salts and building materials can be obtained. In the Institute of Chemistry of the Academy of Sciences of the Republic of Tajikistan the flowsheets of the processing of borosilicate raw materials by acid and chloric methods were elaborated. The acid methods of decomposition of borosilicate ores of Ak-Arkhar Deposit were considered in present monograph. The carried out researches on elaboration of physicochemical aspects and technological acid methods allowed to define the optimal ways of extraction of valuable products from borosilicate raw materials of Tajikistan.

Plant Species Rather Than Climate Greatly Alters the Temporal Pattern of Litter Chemical Composition During Long-Term Decomposition

Science.gov (United States)

Li, Yongfu; Chen, Na; Harmon, Mark E.; Li, Yuan; Cao, Xiaoyan; Chappell, Mark A.; Mao, Jingdong

2015-10-01

A feedback between decomposition and litter chemical composition occurs with decomposition altering composition that in turn influences the decomposition rate. Elucidating the temporal pattern of chemical composition is vital to understand this feedback, but the effects of plant species and climate on chemical changes remain poorly understood, especially over multiple years. In a 10-year decomposition experiment with litter of four species (Acer saccharum, Drypetes glauca, Pinus resinosa, and Thuja plicata) from four sites that range from the arctic to tropics, we determined the abundance of 11 litter chemical constituents that were grouped into waxes, carbohydrates, lignin/tannins, and proteins/peptides using advanced 13C solid-state NMR techniques. Decomposition generally led to an enrichment of waxes and a depletion of carbohydrates, whereas the changes of other chemical constituents were inconsistent. Inconsistent convergence in chemical compositions during decomposition was observed among different litter species across a range of site conditions, whereas one litter species converged under different climate conditions. Our data clearly demonstrate that plant species rather than climate greatly alters the temporal pattern of litter chemical composition, suggesting the decomposition-chemistry feedback varies among different plant species.

Coupled effects of solution chemistry and hydrodynamics on the mobility and transport of quantum dot nanomaterials in the Vadose Zone

Science.gov (United States)

To investigate the coupled effects of solution chemistry and vadose zone processes on the mobility of quantum dot (QD) nanoparticles, laboratory scale transport experiments were performed. The complex coupled effects of ionic strength, size of QD aggregates, surface tension, contact angle, infiltrat...

Achievement report on research and development in the Sunshine Project in fiscal 1978. Research and development of water decomposition by using the thermo, photo and electro-chemistry mixed cycle; 1978 nendo netsukagaku, hikari kagaku, denki kagaku konsei cycle ni yoru suibunkai no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1979-03-01

This paper describes research achievements in fiscal 1978 on water decomposition by using the thermo, photo and electro-chemistry mixed cycle. Fundamental experiments were carried out in a photo-chemical and electrolytic reaction tank to electrolyse as quickly as possible HI and iron (III) produced by photo-chemical reaction in the iodine-iron (II) system, and separate the products therefrom. The photo-chemical reaction was analyzed by using the spectro-photometry, and the degree of reaction progress was quantified by using the change in absorbance of I{sub 3}{sup -}. Since temperature rise due to sun beam irradiation accelerates reverse reaction, the apparent equilibrium position under the beam irradiation was moved from the product system to the original system as the temperature rises. An expression showing the reaction efficiency was introduced to indicate that beam collection enhances the efficiency. There is no electrolytic electrode material that reduces only iron (III) preferably, and electrolysing the aqueous product solution as it is results in low energy efficiency. In addition, as a result of discussing factors affecting the effect of HI decomposition (to acquire hydrogen) by using a heat diffusion column, it was revealed that maximum separation effect can be derived if the material is fed from the center of the column. Discussions were given also on other factors. (NEDO)

Selected ion flow tube mass spectrometry analyses of laser decomposition products of a range of explosives and ballistic propellants

Czech Academy of Sciences Publication Activity Database

Civiš, Svatopluk; Civiš, Martin; Sovová, Kristýna; Dryahina, Kseniya; Kubišta, Jiří; Skřehot, P.; Španěl, Patrik; Kyncl, M.

2016-01-01

Roč. 8, č. 5 (2016), s. 1145-1150 ISSN 1759-9660 Institutional support: RVO:61388955 Keywords : FT-MS * laser-induced breakdown * laser decomposition products Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.900, year: 2016

Spectral Tensor-Train Decomposition

DEFF Research Database (Denmark)

Bigoni, Daniele; Engsig-Karup, Allan Peter; Marzouk, Youssef M.

2016-01-01

The accurate approximation of high-dimensional functions is an essential task in uncertainty quantification and many other fields. We propose a new function approximation scheme based on a spectral extension of the tensor-train (TT) decomposition. We first define a functional version of the TT...... adaptive Smolyak approach. The method is also used to approximate the solution of an elliptic PDE with random input data. The open source software and examples presented in this work are available online (http://pypi.python.org/pypi/TensorToolbox/)....

Effect of wood ash application on soil solution chemistry of tropical acid soils: incubation study.

Science.gov (United States)

Nkana, J C Voundi; Demeyer, A; Verloo, M G

2002-12-01

The objective of this study was to determine the effect of wood ash application on soil solution composition of three tropical acid soils. Calcium carbonate was used as a reference amendment. Amended soils and control were incubated for 60 days. To assess soluble nutrients, saturation extracts were analysed at 15 days intervals. Wood ash application affects the soil solution chemistry in two ways, as a liming agent and as a supplier of nutrients. As a liming agent, wood ash application induced increases in soil solution pH, Ca, Mg, inorganic C, SO4 and DOC. As a supplier of elements, the increase in the soil solution pH was partly due to ligand exchange between wood ash SO4 and OH- ions. Large increases in concentrations of inorganic C, SO4, Ca and Mg with wood ash relative to lime and especially increases in K reflected the supply of these elements by wood ash. Wood ash application could represent increased availability of nutrients for the plant. However, large concentrations of basic cations, SO4 and NO3 obtained with higher application rates could be a concern because of potential solute transport to surface waters and groundwater. Wood ash must be applied at reasonable rates to avoid any risk for the environment.

Decomposition and Mineralization of Dimethyl Phthalate in an Aqueous Solution by Wet Oxidation

Directory of Open Access Journals (Sweden)

Dar-Ren Ji

2015-01-01

Full Text Available Dimethyl phthalate (DMP was treated via wet oxygen oxidation process (WOP. The decomposition efficiency ηDMP of DMP and mineralization efficiency ηTOC of total organic carbons were measured to evaluate the effects of operation parameters on the performance of WOP. The results revealed that reaction temperature T is the most affecting factor, with a higher T offering higher ηDMP and ηTOC as expected. The ηDMP increases as rotating speed increases from 300 to 500 rpm with stirring enhancement of gas liquid mass transfer. However, it exhibits reduction effect at 700 rpm due to purging of dissolved oxygen by overstirring. Regarding the effects of pressure PT, a higher PT provides more oxygen for the forward reaction with DMP, while overhigh PT increases the absorption of gaseous products such as CO2 and decomposes short-chain hydrocarbon fragments back into the solution thus hindering the forward reaction. For the tested PT of 2.41 to 3.45 MPa, the results indicated that 2.41 MPa is appropriate. A longer reaction time of course gives better performance. At 500 rpm, 483 K, 2.41 MPa, and 180 min, the ηDMP and ηTOC are 93 and 36%, respectively.

Surface spinodal decomposition in coherent metal-hydrogen and other alloys

International Nuclear Information System (INIS)

Kappus, W.; Horner, H.

1977-01-01

Spinodal decomposition in metal hydrides and alloys near a surface under the influence of elastic interactions is investigated. As long as the crystals remain coherent this process sets in prior to spinodal decomposition in the bulk. A statistical theory containing thermal fluctuations and nonlinear effects is developed and solutions are found in a mean field approximation. The theory is applied to niobium-hydride and a possible explanation for the appearance of quasiperiodic β-phase precipitates in quenched probes is given. (orig.) [de

Chemistry in Microfluidic Channels

Science.gov (United States)

Chia, Matthew C.; Sweeney, Christina M.; Odom, Teri W.

2011-01-01

General chemistry introduces principles such as acid-base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of…

The effects of Α-tocopherol and ascorbic acid glucosides on radiation- and H2O2-induced decomposition of thymine in aqueous solution

International Nuclear Information System (INIS)

Brinkevich, S.D.; Lagutin, P.Yu.; Shadyro, O.I.

2008-01-01

The effects of ascorbic acid, ascorbic acid glycoside and α-tocopherol monoglycoside on radiation- and H 2 O 2 -induced decomposition of thymine in aqueous solutions were investigated. Of the three compounds studied, ascorbic acid glycoside was found to possess the most marked protecting properties. An explanation of this phenomenon has been given in terms of differences in molecular structures of ascorbic acid and ascorbic acid glycoside, as well as properties of radical adducts formed during their interaction with OH radicals. (authors)

Effect of Potassium in Calcined Co-Mn-Al Layered Double Hydroxide on the Catalytic Decomposition of N2O

Czech Academy of Sciences Publication Activity Database

Obalová, L.; Karásková, K.; Jirátová, Květa; Kovanda, F.

2009-01-01

Roč. 90, 1-2 (2009), s. 132-140 ISSN 0926-3373 Institutional research plan: CEZ:AV0Z40720504 Keywords : nitrous oxide * catalytic decomposition * potassium promoter Subject RIV: CC - Organic Chemistry Impact factor: 5.252, year: 2009

Formation of TiO/Al2O3/C Composite in Thermal Co-decomposition of Aluminium(III) Acetylacetonate and Titanium(IV) Oxyacetylacetonate.

Czech Academy of Sciences Publication Activity Database

Kovářík, T.; Pokorná, Dana; Urbanová, Markéta; Bezdička, Petr; Bastl, Zdeněk; Kupčík, Jaroslav; Křenek, T.; Pola, M.; Kullová, L.; Pola, Josef

2016-01-01

Roč. 117, JAN 2016 (2016), s. 182-190 ISSN 0165-2370 R&D Projects: GA TA ČR TA04020860 Institutional support: RVO:67985858 ; RVO:61388980 ; RVO:61388955 Keywords : thermal co-decomposition * aluminium(III) acetylacetonate * titanium(IV) oxyacetylacetonate * titanium monoxide * alumina * Carbona Subject RIV: CF - Physical ; Theoretical Chemistry; CA - Inorganic Chemistry (UACH-T) Impact factor: 3.471, year: 2016

Structure, morphology and electrochemical behaviour of manganese oxides prepared by controlled decomposition of permanganate

Energy Technology Data Exchange (ETDEWEB)

Donne, S.W.; Jones, B.C. [Discipline of Chemistry, University of Newcastle, Callaghan, NSW 2308 (Australia); Hollenkamp, A.F. [CSIRO Energy Technology, Box 312, Clayton South, Vic. 3169 (Australia)

2010-01-01

Hydrothermal decomposition of permanganate, conducted in a range of pH-controlled solutions (from strongly acidic to strongly basic), is used to prepare manganese dioxides that are well-suited for use as supercapacitor electrode materials. While permanganate is thermodynamically unstable, the kinetics of its decomposition in an aqueous environment are very slow, until the temperature is raised to {proportional_to}200 C. Although the resultant materials are relatively crystalline and have low total pore volume, their prominent meso-porosity leads to good electrochemical performance. Best behaviour is obtained for material from permanganate decomposition in 0.01 M H{sub 2}SO{sub 4} solution, for which composite electrodes (150 {mu}m thick) yield {proportional_to}150 F g{sup -1} at 5 mV s{sup -1} in a 9 M KOH electrolyte. (author)

Radiation decomposition of alcohols and chloro phenols in micellar systems

International Nuclear Information System (INIS)

Moreno A, J.

1998-01-01

The effect of surfactants on the radiation decomposition yield of alcohols and chloro phenols has been studied with gamma doses of 2, 3, and 5 KGy. These compounds were used as typical pollutants in waste water, and the effect of the water solubility, chemical structure, and the nature of the surfactant, anionic or cationic, was studied. The results show that anionic surfactant like sodium dodecylsulfate (SDS), improve the radiation decomposition yield of ortho-chloro phenol, while cationic surfactant like cetyl trimethylammonium chloride (CTAC), improve the radiation decomposition yield of butyl alcohol. A similar behavior is expected for those alcohols with water solubility close to the studied ones. Surfactant concentrations below critical micellar concentration (CMC), inhibited radiation decomposition for both types of alcohols. However radiation decomposition yield increased when surfactant concentrations were bigger than the CMC. Aromatic alcohols decomposition was more marked than for linear alcohols decomposition. On a mixture of alcohols and chloro phenols in aqueous solution the radiation decomposition yield decreased with increasing surfactant concentration. Nevertheless, there were competitive reactions between the alcohols, surfactants dimers, hydroxyl radical and other reactive species formed on water radiolysis, producing a catalytic positive effect in the decomposition of alcohols. Chemical structure and the number of carbons were not important factors in the radiation decomposition. When an alcohol like ortho-chloro phenol contained an additional chlorine atom, the decomposition of this compound was almost constant. In conclusion the micellar effect depend on both, the nature of the surfactant (anionic or cationic) and the chemical structure of the alcohols. The results of this study are useful for wastewater treatment plants based on the oxidant effect of the hydroxyl radical, like in advanced oxidation processes, or in combined treatment such as

N.sub.2./sub.O decomposition and formation of NO.sub.x./sub. species on Fe-ferrierite. Effect of NO and CO addition on the decomposition and the role of surface species

Czech Academy of Sciences Publication Activity Database

Nováková, Jana; Sobalík, Zdeněk

2005-01-01

Roč. 105, 3-4 (2005), s. 169-177 ISSN 1011-372X R&D Projects: GA AV ČR 1ET400400413 Institutional research plan: CEZ:AV0Z40400503 Keywords : decomposition of N 2 O * surface species desorbed * low- and high-temperature pretreated samples * isotope labeling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.088, year: 2005

Ozone decomposition

Directory of Open Access Journals (Sweden)

Batakliev Todor

2014-06-01

Full Text Available Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers. Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates

Proper generalized decompositions an introduction to computer implementation with Matlab

CERN Document Server

Cueto, Elías; Alfaro, Icíar

2016-01-01

This book is intended to help researchers overcome the entrance barrier to Proper Generalized Decomposition (PGD), by providing a valuable tool to begin the programming task. Detailed Matlab Codes are included for every chapter in the book, in which the theory previously described is translated into practice. Examples include parametric problems, non-linear model order reduction and real-time simulation, among others. Proper Generalized Decomposition (PGD) is a method for numerical simulation in many fields of applied science and engineering. As a generalization of Proper Orthogonal Decomposition or Principal Component Analysis to an arbitrary number of dimensions, PGD is able to provide the analyst with very accurate solutions for problems defined in high dimensional spaces, parametric problems and even real-time simulation. .

NO-oxygen scavenger or reaction intermediate in the decomposition of N2O?

Czech Academy of Sciences Publication Activity Database

Nováková, Jana; Sobalík, Zdeněk

2006-01-01

Roč. 111, 3-4 (2006), s. 195-202 ISSN 1011-372X R&D Projects: GA AV ČR 1ET400400413 Institutional research plan: CEZ:AV0Z40400503 Keywords : 15N2 18O and 15N2 18 O + 14N 16O decomposition * role of NOx intermediates * Fe-zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.772, year: 2006

Underlying chemistry research for the nuclear fuel waste management program

International Nuclear Information System (INIS)

Torgerson, D.F.; Sagert, N.H.; Shoesmith, D.W.; Taylor, P.

1984-04-01

This document reviews the underlying chemistry research part of the Canadian Nuclear Fuel Waste Management Program, carried out in the Research Chemistry Branch. This research is concerned with developing the basic chemical knowledge and under-standing required in other parts of the Program. There are four areas of underlying research: Waste Form Chemistry, Solute and Solution Chemistry, Rock-Water-Waste Interactions, and Abatement and Monitoring of Gas-Phase Radionuclides

Homotopy decomposition method for solving one-dimensional time-fractional diffusion equation

Science.gov (United States)

Abuasad, Salah; Hashim, Ishak

2018-04-01

In this paper, we present the homotopy decomposition method with a modified definition of beta fractional derivative for the first time to find exact solution of one-dimensional time-fractional diffusion equation. In this method, the solution takes the form of a convergent series with easily computable terms. The exact solution obtained by the proposed method is compared with the exact solution obtained by using fractional variational homotopy perturbation iteration method via a modified Riemann-Liouville derivative.

Ferroelectric based catalysis: Switchable surface chemistry

Science.gov (United States)

Kakekhani, Arvin; Ismail-Beigi, Sohrab

2015-03-01

We describe a new class of catalysts that uses an epitaxial monolayer of a transition metal oxide on a ferroelectric substrate. The ferroelectric polarization switches the surface chemistry between strongly adsorptive and strongly desorptive regimes, circumventing difficulties encountered on non-switchable catalytic surfaces where the Sabatier principle dictates a moderate surface-molecule interaction strength. This method is general and can, in principle, be applied to many reactions, and for each case the choice of the transition oxide monolayer can be optimized. Here, as a specific example, we show how simultaneous NOx direct decomposition (into N2 and O2) and CO oxidation can be achieved efficiently on CrO2 terminated PbTiO3, while circumventing oxygen (and sulfur) poisoning issues. One should note that NOx direct decomposition has been an open challenge in automotive emission control industry. Our method can expand the range of catalytically active elements to those which are not conventionally considered for catalysis and which are more economical, e.g., Cr (for NOx direct decomposition and CO oxidation) instead of canonical precious metal catalysts. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

Cobalt Oxide Catalysts on Commercial Supports for N2O Decomposition.

Czech Academy of Sciences Publication Activity Database

Klegová, A.; Pacultová, K.; Fridrichová, D.; Volodarskaja, A.; Kovanda, J.; Jirátová, Květa

2017-01-01

Roč. 40, č. 5 (2017), s. 981-990 ISSN 0930-7516. [International Congress of Chemical and Process Engineering CHISA 2016 /22./ and the 19th Conference PRES 2016. Prague, 27.08.2016-31.08.2016] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : N2O decomposition * cobalt oxide * shaped catalyst Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 2.051, year: 2016

N2O Decomposition over Fe-Ferrierite: Primary and Secondary Reactions with Reducing Agents

Czech Academy of Sciences Publication Activity Database

Nováková, Jana; Sobalík, Zdeněk

2009-01-01

Roč. 127, 1-2 (2009), s. 95-100 ISSN 1011-372X R&D Projects: GA AV ČR 1ET400400413; GA AV ČR 1QS400400560 Institutional research plan: CEZ:AV0Z40400503 Keywords : N2O decomposition * reactivity of surface species * Fe-ferrierite Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.021, year: 2009

Cell-wall polysaccharides play an important role in decay resistance of Sphagnum and actively depressed decomposition in vitro

NARCIS (Netherlands)

Hajek, T.; Ballance, S.; Limpens, J.; Verhoeven, J.T.A.; Zijlstra, M.J.

2011-01-01

Sphagnum-dominated peatlands head the list of ecosystems with the largest known reservoirs of organic carbon (C). The bulk of this C is stored in decomposition-resistant litter of one bryophyte genus: Sphagnum. Understanding how Sphagnum litter chemistry controls C mineralization is essential for

Life's Biological Chemistry: A Destiny or Destination Starting from Prebiotic Chemistry?

Science.gov (United States)

Krishnamurthy, Ramanarayanan

2018-06-05

Research into understanding the origins -and evolution- of life has long been dominated by the concept of taking clues from extant biology and extrapolating its molecules and pathways backwards in time. This approach has also guided the search for solutions to the problem of how contemporary biomolecules would have arisen directly from prebiotic chemistry on early earth. However, the continuing difficulties in finding universally convincing solutions in connecting prebiotic chemistry to biological chemistry should give us pause, and prompt us to rethink this concept of treating extant life's chemical processes as the sole end goal and, therefore, focusing only -and implicitly- on the respective extant chemical building blocks. Rather, it may be worthwhile "to set aside the goal" and begin with what would have been plausible prebiotic reaction mixtures (which may have no obvious or direct connection to life's chemical building blocks and processes) - and allow their chemistries and interactions, under different geochemical constraints, to guide and illuminate as to what processes and systems can emerge. Such a conceptual approach gives rise to the prospect that chemistry of life-as-we-know-it is not the only result (not a "destiny"), but one that has emerged among many potential possibilities (a "destination"). This postulate, in turn, could impact the way we think about chemical signatures and criteria used in the search for alternative and extraterrestrial "life". As a bonus, we may discover the chemistries and pathways naturally that led to the emergence of life as we know it. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemistry Division : Annual progress report of 1974

International Nuclear Information System (INIS)

1974-01-01

Research and development activities (during 1974) of the Chemistry Division of the Bhabha Atomic Research Centre, Bombay, are described. Some of the activities of particular interest to nuclear science and technology are: (1) chemistry-based problems of the operating power reactors such as development of a decontaminating solution for power reactors, correlation of iodine-131 levels in the primary heat transport system of a reactor with its operation (2) release of fission gases like xenon from ceramic fuels and (3) radiation chemistry of nitrate solutions (M.G.B.)

Novel bi-metallic uranyl complexes - Redox chemistry in aqueous solutions

International Nuclear Information System (INIS)

Yardeni, A.; Mizrahi, E.; Maimon, I.; Zilbermann, G.; Meyerstein, D.; Zehavi-cohen, A.Z.

2014-01-01

The synthesis of organic ligands which can accommodate two uranium atoms at different oxidation states, mixed valency being then achieved by redox chemistry at room temperature is definitely a challenge in coordination chemistry. The following complexes were synthesized and characterized by elemental analysis, NMR, MS, IR and UV-vis

SLAP, Large Sparse Linear System Solution Package

International Nuclear Information System (INIS)

Greenbaum, A.

1987-01-01

1 - Description of program or function: SLAP is a set of routines for solving large sparse systems of linear equations. One need not store the entire matrix - only the nonzero elements and their row and column numbers. Any nonzero structure is acceptable, so the linear system solver need not be modified when the structure of the matrix changes. Auxiliary storage space is acquired and released within the routines themselves by use of the LRLTRAN POINTER statement. 2 - Method of solution: SLAP contains one direct solver, a band matrix factorization and solution routine, BAND, and several interactive solvers. The iterative routines are as follows: JACOBI, Jacobi iteration; GS, Gauss-Seidel Iteration; ILUIR, incomplete LU decomposition with iterative refinement; DSCG and ICCG, diagonal scaling and incomplete Cholesky decomposition with conjugate gradient iteration (for symmetric positive definite matrices only); DSCGN and ILUGGN, diagonal scaling and incomplete LU decomposition with conjugate gradient interaction on the normal equations; DSBCG and ILUBCG, diagonal scaling and incomplete LU decomposition with bi-conjugate gradient iteration; and DSOMN and ILUOMN, diagonal scaling and incomplete LU decomposition with ORTHOMIN iteration

Comparison of Two-Block Decomposition Method and Chebyshev Rational Approximation Method for Depletion Calculation

International Nuclear Information System (INIS)

Lee, Yoon Hee; Cho, Nam Zin

2016-01-01

The code gives inaccurate results of nuclides for evaluation of source term analysis, e.g., Sr- 90, Ba-137m, Cs-137, etc. A Krylov Subspace method was suggested by Yamamoto et al. The method is based on the projection of solution space of Bateman equation to a lower dimension of Krylov subspace. It showed good accuracy in the detailed burnup chain calculation if dimension of the Krylov subspace is high enough. In this paper, we will compare the two methods in terms of accuracy and computing time. In this paper, two-block decomposition (TBD) method and Chebyshev rational approximation method (CRAM) are compared in the depletion calculations. In the two-block decomposition method, according to the magnitude of effective decay constant, the system of Bateman equation is decomposed into short- and longlived blocks. The short-lived block is calculated by the general Bateman solution and the importance concept. Matrix exponential with smaller norm is used in the long-lived block. In the Chebyshev rational approximation, there is no decomposition of the Bateman equation system, and the accuracy of the calculation is determined by the order of expansion in the partial fraction decomposition of the rational form. The coefficients in the partial fraction decomposition are determined by a Remez-type algorithm.

Comparison of Two-Block Decomposition Method and Chebyshev Rational Approximation Method for Depletion Calculation

Energy Technology Data Exchange (ETDEWEB)

Lee, Yoon Hee; Cho, Nam Zin [KAERI, Daejeon (Korea, Republic of)

2016-05-15

The code gives inaccurate results of nuclides for evaluation of source term analysis, e.g., Sr- 90, Ba-137m, Cs-137, etc. A Krylov Subspace method was suggested by Yamamoto et al. The method is based on the projection of solution space of Bateman equation to a lower dimension of Krylov subspace. It showed good accuracy in the detailed burnup chain calculation if dimension of the Krylov subspace is high enough. In this paper, we will compare the two methods in terms of accuracy and computing time. In this paper, two-block decomposition (TBD) method and Chebyshev rational approximation method (CRAM) are compared in the depletion calculations. In the two-block decomposition method, according to the magnitude of effective decay constant, the system of Bateman equation is decomposed into short- and longlived blocks. The short-lived block is calculated by the general Bateman solution and the importance concept. Matrix exponential with smaller norm is used in the long-lived block. In the Chebyshev rational approximation, there is no decomposition of the Bateman equation system, and the accuracy of the calculation is determined by the order of expansion in the partial fraction decomposition of the rational form. The coefficients in the partial fraction decomposition are determined by a Remez-type algorithm.

Variance decomposition in stochastic simulators.

Science.gov (United States)

Le Maître, O P; Knio, O M; Moraes, A

2015-06-28

This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

Variance decomposition in stochastic simulators

Science.gov (United States)

Le Maître, O. P.; Knio, O. M.; Moraes, A.

2015-06-01

This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

Variance decomposition in stochastic simulators

Energy Technology Data Exchange (ETDEWEB)

Le Maître, O. P., E-mail: olm@limsi.fr [LIMSI-CNRS, UPR 3251, Orsay (France); Knio, O. M., E-mail: knio@duke.edu [Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708 (United States); Moraes, A., E-mail: alvaro.moraesgutierrez@kaust.edu.sa [King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

2015-06-28

This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

Variance decomposition in stochastic simulators

KAUST Repository

Le Maî tre, O. P.; Knio, O. M.; Moraes, Alvaro

2015-01-01

This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

Decomposition and nutrient release of leguminous plants in coffee agroforestry systems

Directory of Open Access Journals (Sweden)

Eduardo da Silva Matos

2011-02-01

Full Text Available Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and Stylosanthes guianensis in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and (lignin+polyphenol/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD, the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA, there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1. Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants.

Catalytic Activity of Cobalt Grafted on Ordered Mesoporous Silica Materials in N2O Decomposition and CO Oxidation.

Czech Academy of Sciences Publication Activity Database

Kuboňová, L.; Peikertová, P.; Mamulová Kutláková, K.; Jirátová, Květa; Słowik, G.; Obalová, L.; Cool, P.

2017-01-01

Roč. 437, AUG 2017 (2017), s. 57-72 ISSN 2468-8231 R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : mesoporous ordered silica * cobalt * N2O decomposition Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering

An abstraction layer for efficient memory management of tabulated chemistry and flamelet solutions

Science.gov (United States)

Weise, Steffen; Messig, Danny; Meyer, Bernd; Hasse, Christian

2013-06-01

A large number of methods for simulating reactive flows exist, some of them, for example, directly use detailed chemical kinetics or use precomputed and tabulated flame solutions. Both approaches couple the research fields computational fluid dynamics and chemistry tightly together using either an online or offline approach to solve the chemistry domain. The offline approach usually involves a method of generating databases or so-called Lookup-Tables (LUTs). As these LUTs are extended to not only contain material properties but interactions between chemistry and turbulent flow, the number of parameters and thus dimensions increases. Given a reasonable discretisation, file sizes can increase drastically. The main goal of this work is to provide methods that handle large database files efficiently. A Memory Abstraction Layer (MAL) has been developed that handles requested LUT entries efficiently by splitting the database file into several smaller blocks. It keeps the total memory usage at a minimum using thin allocation methods and compression to minimise filesystem operations. The MAL has been evaluated using three different test cases. The first rather generic one is a sequential reading operation on an LUT to evaluate the runtime behaviour as well as the memory consumption of the MAL. The second test case is a simulation of a non-premixed turbulent flame, the so-called HM1 flame, which is a well-known test case in the turbulent combustion community. The third test case is a simulation of a non-premixed laminar flame as described by McEnally in 1996 and Bennett in 2000. Using the previously developed solver 'flameletFoam' in conjunction with the MAL, memory consumption and the performance penalty introduced were studied. The total memory used while running a parallel simulation was reduced significantly while the CPU time overhead associated with the MAL remained low.

Behavior of Active Oxygen During the Decomposition of Nitrous Oxide Over Fe-FER

Czech Academy of Sciences Publication Activity Database

Nováková, Jana; Sobalík, Zdeněk

2009-01-01

Roč. 131, 3-4 (2009), s. 530-537 ISSN 1011-372X R&D Projects: GA ČR GA104/06/1254; GA AV ČR KAN100400702; GA MPO FT-TA3/064 Institutional research plan: CEZ:AV0Z40400503 Keywords : 18O exchange * N2O decomposition * NOx species * Fe- fer rierite Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.021, year: 2009

Design Features of the SMART Water Chemistry

International Nuclear Information System (INIS)

Byung Seon Choi; Seong Hoon Kim; Juhyeon Yoon; Doo Jeong Lee; Yoon Yeong Bae; Sung Kyun Zee

2004-01-01

The design features for the primary water chemistry for the SMART are introduced from the viewpoint of the system characteristics and the chemical design concept. The most essential differences in water chemistry between the commercially operating PWRs and SMART are characterized by the presence of boron in the water and the operating mode of the purification system. SMART is a soluble boron free reactor, and the ammonia is used as a pH reagent. The material for SMART steam generator is also different from the standard material of the commercially operating PWRs: titanium alloy for the steam generator tubes. In SMART hydrogen gas which suppresses a generation of oxidizing species by the radiolysis processes in the reactors is not added to the primary coolant, but is normally generated from the radiolysis of the ammonia as the coolant passes through the core. Ammonia is added once per shift because SMART reactor has no letdown and charging system during power operation. Because of these competing processes, the concentrations of hydrogen, nitrogen and ammonia in the primary coolant are in equilibrium, which depend on the decomposition and/or combination rate of the ammonia. The level of permissible oxygen concentration in the primary coolant can be ensured by both suppression of the water radiolysis through maintaining a high enough hydrogen concentration in the primary coolant and by a restriction of the oxygen ingress into the primary coolant with the makeup water. The ammonia chemistry in SMART reactor eliminates the need for hydrogen injection for the control of the dissolved oxygen in the primary coolant because of spontaneous generation of hydrogen and nitrogen produced by the reaction of the ammonia decomposition. (authors)

SDE decomposition and A-type stochastic interpretation in nonequilibrium processes

Science.gov (United States)

Yuan, Ruoshi; Tang, Ying; Ao, Ping

2017-12-01

An innovative theoretical framework for stochastic dynamics based on the decomposition of a stochastic differential equation (SDE) into a dissipative component, a detailed-balance-breaking component, and a dual-role potential landscape has been developed, which has fruitful applications in physics, engineering, chemistry, and biology. It introduces the A-type stochastic interpretation of the SDE beyond the traditional Ito or Stratonovich interpretation or even the α-type interpretation for multidimensional systems. The potential landscape serves as a Hamiltonian-like function in nonequilibrium processes without detailed balance, which extends this important concept from equilibrium statistical physics to the nonequilibrium region. A question on the uniqueness of the SDE decomposition was recently raised. Our review of both the mathematical and physical aspects shows that uniqueness is guaranteed. The demonstration leads to a better understanding of the robustness of the novel framework. In addition, we discuss related issues including the limitations of an approach to obtaining the potential function from a steady-state distribution.

Insights into the decomposition of olefin metathesis precatalysts

KAUST Repository

Manzini, Simone; Poater, Albert; Nelson, David J.; Cavallo, Luigi; Slawin, Alexandra M. Z.; Nolan, Steven P.

2014-01-01

The decomposition of a series of benzylidene, methylidene, and 3-phenylindenylidene complexes has been probed in alcohol solution in the presence of base. Tricyclohexylphosphane-containing precatalysts are shown to yield [RuCl(H)(H2)(PCy3)2] in isopropyl alcohol solutions, while 3-phenylindenylidene complexes lead to η5-(3- phenyl)indenyl products. The potential-energy surfaces for the formation of the latter species have been probed using density functional theory studies. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Insights into the decomposition of olefin metathesis precatalysts

KAUST Repository

Manzini, Simone

2014-06-02

The decomposition of a series of benzylidene, methylidene, and 3-phenylindenylidene complexes has been probed in alcohol solution in the presence of base. Tricyclohexylphosphane-containing precatalysts are shown to yield [RuCl(H)(H2)(PCy3)2] in isopropyl alcohol solutions, while 3-phenylindenylidene complexes lead to η5-(3- phenyl)indenyl products. The potential-energy surfaces for the formation of the latter species have been probed using density functional theory studies. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solving network design problems via decomposition, aggregation and approximation

CERN Document Server

Bärmann, Andreas

2016-01-01

Andreas Bärmann develops novel approaches for the solution of network design problems as they arise in various contexts of applied optimization. At the example of an optimal expansion of the German railway network until 2030, the author derives a tailor-made decomposition technique for multi-period network design problems. Next, he develops a general framework for the solution of network design problems via aggregation of the underlying graph structure. This approach is shown to save much computation time as compared to standard techniques. Finally, the author devises a modelling framework for the approximation of the robust counterpart under ellipsoidal uncertainty, an often-studied case in the literature. Each of these three approaches opens up a fascinating branch of research which promises a better theoretical understanding of the problem and an increasing range of solvable application settings at the same time. Contents Decomposition for Multi-Period Network Design Solving Network Design Problems via Ag...

Decomposition techniques

Science.gov (United States)

Chao, T.T.; Sanzolone, R.F.

1992-01-01

Sample decomposition is a fundamental and integral step in the procedure of geochemical analysis. It is often the limiting factor to sample throughput, especially with the recent application of the fast and modern multi-element measurement instrumentation. The complexity of geological materials makes it necessary to choose the sample decomposition technique that is compatible with the specific objective of the analysis. When selecting a decomposition technique, consideration should be given to the chemical and mineralogical characteristics of the sample, elements to be determined, precision and accuracy requirements, sample throughput, technical capability of personnel, and time constraints. This paper addresses these concerns and discusses the attributes and limitations of many techniques of sample decomposition along with examples of their application to geochemical analysis. The chemical properties of reagents as to their function as decomposition agents are also reviewed. The section on acid dissolution techniques addresses the various inorganic acids that are used individually or in combination in both open and closed systems. Fluxes used in sample fusion are discussed. The promising microwave-oven technology and the emerging field of automation are also examined. A section on applications highlights the use of decomposition techniques for the determination of Au, platinum group elements (PGEs), Hg, U, hydride-forming elements, rare earth elements (REEs), and multi-elements in geological materials. Partial dissolution techniques used for geochemical exploration which have been treated in detail elsewhere are not discussed here; nor are fire-assaying for noble metals and decomposition techniques for X-ray fluorescence or nuclear methods be discussed. ?? 1992.

Domain decomposition multigrid for unstructured grids

Energy Technology Data Exchange (ETDEWEB)

Shapira, Yair

1997-01-01

A two-level preconditioning method for the solution of elliptic boundary value problems using finite element schemes on possibly unstructured meshes is introduced. It is based on a domain decomposition and a Galerkin scheme for the coarse level vertex unknowns. For both the implementation and the analysis, it is not required that the curves of discontinuity in the coefficients of the PDE match the interfaces between subdomains. Generalizations to nonmatching or overlapping grids are made.

Solution chemistry of Mo(III) and Mo(IV): Thermodynamic foundation for modeling localized corrosion

International Nuclear Information System (INIS)

Wang Peiming; Wilson, Leslie L.; Wesolowski, David J.; Rosenqvist, Joergen; Anderko, Andrzej

2010-01-01

To investigate the behavior of molybdenum dissolution products in systems that approximate localized corrosion environments, solubility of Mo(III) in equilibrium with solid MoO 2 has been determined at 80 deg. C as a function of solution acidity, chloride concentration and partial pressure of hydrogen. The measurements indicate a strong increase in solubility with acidity and chloride concentration and a weak effect of hydrogen partial pressure. The obtained results have been combined with literature data for systems containing Mo(III), Mo(IV), and Mo(VI) in solutions to develop a comprehensive thermodynamic model of aqueous molybdenum chemistry. The model is based on a previously developed framework for simulating the properties of electrolyte systems ranging from infinite dilution to solid saturation or fused salt limit. To reproduce the measurements, the model assumes the presence of a chloride complex of Mo(III) (i.e., MoCl 2+ ) and hydrolyzed species (MoOH 2+ , Mo(OH) 2 + , and Mo(OH) 3 0 ) in addition to the Mo 3+ ion. The model generally reproduces the experimental data within experimental scattering and provides a tool for predicting the phase behavior and speciation in complex, concentrated aqueous solutions. Thus, it provides a foundation for simulating the behavior of molybdenum species in localized corrosion environments.

Decomposition of soil organic matter from boreal black spruce forest: Environmental and chemical controls

Science.gov (United States)

Wickland, K.P.; Neff, J.C.

2008-01-01

Black spruce forests are a dominant covertype in the boreal forest region, and they inhabit landscapes that span a wide range of hydrologic and thermal conditions. These forests often have large stores of soil organic carbon. Recent increases in temperature at northern latitudes may be stimulating decomposition rates of this soil carbon. It is unclear, however, how changes in environmental conditions influence decomposition in these systems, and if substrate controls of decomposition vary with hydrologic and thermal regime. We addressed these issues by investigating the effects of temperature, moisture, and organic matter chemical characteristics on decomposition of fibric soil horizons from three black spruce forest sites. The sites varied in drainage and permafrost, and included a "Well Drained" site where permafrost was absent, and "Moderately well Drained" and "Poorly Drained" sites where permafrost was present at about 0.5 m depth. Samples collected from each site were incubated at five different moisture contents (2, 25, 50, 75, and 100% saturation) and two different temperatures (10??C and 20??C) in a full factorial design for two months. Organic matter chemistry was analyzed using pyrolysis gas chromatography-mass spectrometry prior to incubation, and after incubation on soils held at 20??C, 50% saturation. Mean cumulative mineralization, normalized to initial carbon content, ranged from 0.2% to 4.7%, and was dependent on temperature, moisture, and site. The effect of temperature on mineralization was significantly influenced by moisture content, as mineralization was greatest at 20??C and 50-75% saturation. While the relative effects of temperature and moisture were similar for all soils, mineralization rates were significantly greater for samples from the "Well Drained" site compared to the other sites. Variations in the relative abundances of polysaccharide-derivatives and compounds of undetermined source (such as toluene, phenol, 4-methyl phenol, and

Chemistry of the actinide elements. Second edition

International Nuclear Information System (INIS)

Katz, J.J.; Seaborg, G.T.; Morss, L.R.

1987-01-01

This is an exhaustive, updated discourse on the chemistry of Actinides, Volume 1 contains a systematic coverage of the elements Ac, Th, Pa, U, Np, and Pu, which constitutes Part 1 of the work. The characterization of each element is discussed in terms of its nuclear properties, occurrence, preparation, atomic and metallic properties, chemistry of specific compounds, and solution chemistry. The first part of Volume 2 follows the same format as Volume 1 but is confined to the elements Am, Cm, Bk, Cf, and Es, plus a more condensed coverage of the Transeinsteinium elements (Fm, Md, No, Lw, and 104-109). Part 2 of this volume is devoted to a discussion of the actinide elements in general, with a specific focus on electronic spectra, thermodynamic and magnetic properties, the metallic state, structural chemistry, solution kinetics, organometallic chemistry for σ- and π-bonded compounds, and some concluding remarks on the superheavy elements

Radiation chemistry of the liquid state

International Nuclear Information System (INIS)

Buxton, G.V.

1987-01-01

More is known about the radiation chemistry of water than any other liquid. From a practical viewpoint out knowledge is virtually complete, and water radiolysis now provides a very convenient way of generating an enormous variety of unstable species under well-defined conditions. This facility, coupled with the techniques of pulse radiolysis, has opened up new areas in aqueous inorganic, organic, and biochemistry that cannot be readily studied by thermal or photochemical methods. This chapter is aimed, therefore, at those who wish to use radiolytic methods to generate and study unstable species in aqueous solution. The basic features of the radiation chemistry of water are described first to show how the primary radical and molecular products evolve with time and to delineate the bounds of useful experimental conditions. Next, the properties of the primary radicals are summarized, and examples are given to show how the primary radicals can be converted into secondary radicals, often of a single kind. This is an important aspect of the radiation chemistry of aqueous solutions. Lastly, the impact of our knowledge of the radiation chemistry of water on advances in general chemistry is illustrated by examples from the fields of inorganic and organic chemistry

Solution chemistry of lanthanide complexes

International Nuclear Information System (INIS)

Brittain, H.G.

1979-01-01

Intermolecular energy transfer from Tb 3+ to Eu 3+ , luminescence intensity measurements, potentiometric titrations, differential absorption spectroscopy, and spectroscopic titrations were all used to study the binding of lanthanide ions by serine and threonine. At low pH (3.0 to 6.0) the complexes are mononuclear and ligand is only weakly bound. In the pH interval of 6.0 to 8.5 stronger interaction takes place between the ligand and the metal (with possible coordination of the undissociated hydroxyl group), and self-association of complexes becomes important. Above pH 8.5, base hydrolysis of the complexes leads to highly associated species in solution and shortly above this pH an insoluble precipitate is formed. It was found that energy could be transferred from Tb 3+ to Eu 3+ more efficiently among complexes prepared from racemic ligands than in complexes made from resolved ligand, but this stereoselectivity was only observed at pH values greater than 6.5 and in solutions having a 1:10 ratio of metal-to-ligand. No stereoselectivity was found in solutions having 1:5 ratios, and this observation was explained by the existence of 1:2 metal-ligand complexes existing in solutions having the higher ratio of metal-to-ligand (only 1:1 complexes are then found at lower ratios of metal-to-ligand). (author)

The chemistry of the actinide elements. Volume I

International Nuclear Information System (INIS)

Katz, J.J.; Seaborg, G.T.; Morss, L.R.

1986-01-01

The Chemistry of the Actinide Elements is a comprehensive, contemporary and authoritative exposition of the chemistry and related properties of the 5f series of elements: actinium, thorium, protactinium, uranium and the first eleven. This second edition has been completely restructured and rewritten to incorporate current research in all areas of actinide chemistry and chemical physics. The descriptions of each element include accounts of their history, separation, metallurgy, solid-state chemistry, solution chemistry, thermo-dynamics and kinetics. Additionally, separate chapters on spectroscopy, magnetochemistry, thermodynamics, solids, the metallic state, complex ions and organometallic compounds emphasize the comparative chemistry and unique properties of the actinide series of elements. Comprehensive lists of properties of all actinide compounds and ions in solution are given, and there are special sections on such topics as biochemistry, superconductivity, radioisotope safety, and waste management, as well as discussion of the transactinides and future elements

Solving and Interpreting Large-scale Harvest Scheduling Problems by Duality and Decomposition

OpenAIRE

Berck, Peter; Bible, Thomas

1982-01-01

This paper presents a solution to the forest planning problem that takes advantage of both the duality of linear programming formulations currently being used for harvest scheduling and the characteristics of decomposition inherent in the forest land class-relationship. The subproblems of decomposition, defined as the dual, can be solved in a simple, recursive fashion. In effect, such a technique reduces the computational burden in terms of time and computer storage as compared to the traditi...

Irrigation, fertilization and initial substrate quality effects on decomposing Loblolly pine litter chemistry

Science.gov (United States)

Felipe G. Sanchez

2004-01-01

Changes in carbon chemistry (i.e., carbon compound classes such as aromatics, phenolics, etc.) of loblolly pine (Pinus taeda L.) litter were examined during three years of decomposition under factorial combinations of irrigation and fertilization treatments. Cross polarization magic angle spinning 13C nuclear magnetic resonance...

On a hierarchical construction of the anisotropic LTSN solution from the isotropic LTSN solution

International Nuclear Information System (INIS)

Foletto, Taline; Segatto, Cynthia F.; Bodmann, Bardo E.; Vilhena, Marco T.

2015-01-01

In this work, we present a recursive scheme targeting the hierarchical construction of anisotropic LTS N solution from the isotropic LTS N solution. The main idea relies in the decomposition of the associated LTS N anisotropic matrix as a sum of two matrices in which one matrix contains the isotropic and the other anisotropic part of the problem. The matrix containing the anisotropic part is considered as the source of the isotropic problem. The solution of this problem is made by the decomposition of the angular flux as a truncated series of intermediate functions and replace in the isotropic equation. After the replacement of these into the split isotropic equation, we construct a set of isotropic recursive problems, that are readily solved by the classic LTS N isotropic method. We apply this methodology to solve problems considering homogeneous and heterogeneous anisotropic regions. Numerical results are presented and compared with the classical LTS N anisotropic solution. (author)

Decomposition and decoloration of a direct dye by electron beam radiation

International Nuclear Information System (INIS)

Vahdat, Ali; Bahrami, S.H.; Arami, M.; Motahari, A.

2010-01-01

The wastewaters released by textile industries to the environment contain hazardous compounds like toxic refractory dye stuff at high concentration. In this study, electron beam irradiation-induced decoloration and decomposition of C.I. Direct Black 22 aqueous solutions were investigated. The influences of absorbed doses and initial dye concentration on the percent of decoloration, COD and pH of the solutions are described. The results show that the direct dye solutions can be effectively degraded by electron beam irradiation.

Chemistry, sun, energy and environment; Chimie, soleil, energie et environnement

Energy Technology Data Exchange (ETDEWEB)

Bouchy, M. [Ecole Nationale Superieure des Industries Chimiques (ENSIC), 54 - Villers-les-Nancy (France); Enea, O. [Poitiers Univ., 86 (France); Flamant, G. [IMP-Odeillo-CNRS (France)] (and others)

2000-07-01

This document provides the 35 papers presented at the 'Chemistry, Sun, Energy and Environment' meeting, held February 3-4, 2000 in Saint-Avold, France. The main studied topic was the use of solar radiation for water treatment, volatile organic compounds decomposition and in some thermochemical processes. These research subjects are tackled in a fundamental and practical point of view. (O.M.)

A Comparative Study of TiO2-supported and Bulk Co-Mn-Al Catalysts for N2O Decomposition

Czech Academy of Sciences Publication Activity Database

Karásková, K.; Chromčáková, Ž.; Študentová, S.; Matějka, V.; Jirátová, Květa; Obalová, L.

2012-01-01

Roč. 191, č. 1 (2012), s. 112-115 ISSN 0920-5861 R&D Projects: GA ČR GA106/09/1664 Institutional support: RVO:67985858 Keywords : nitrous oxide * catalytic decomposition * layered double hydroxides Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.980, year: 2012

Surface Chemistry of CWAs for Decon Enabling Sciences

Science.gov (United States)

2014-11-04

This work was followed by investigations of organophosphate CWA decomposition on alumina.37 In addition, Wagner and colleagues have employed solid...is coupled to a 1,500 cfm Venturi blower (McMaster- Carr ). This design provides a constant negative pressure inside the vacuum chamber and is...G. W.; Koper, O. B.; Lucas, E.; Decker, S.; Klabunde, K. J. Journal of Physical Chemistry B 2000 , 104, 5118. (41) Wagner, G. W.; Procell, L. R

The slow birth of green chemistry

Energy Technology Data Exchange (ETDEWEB)

Amato, I.

1993-03-12

Mainstream chemistry is beginning to look at environmental chemistry as an important solution to environmental problems. This can include research into developing cleaner-burning liquid fuels, cleaning up oil spills, or developing better process methods which engender less pollution, as opposed to previous practices of detecting pollutants without preventing their release to begin with. This article discusses the progress of this chemistry discipline, describes some of the ongoing research, and describes the future for environmental chemistry. An impetus for future growth will be generational change, as young scientists in training are beginning to push faculities into creating programs for environmental chemistry.

Thermal decomposition of hydroxylamine: Isoperibolic calorimetric measurements at different conditions

International Nuclear Information System (INIS)

Adamopoulou, Theodora; Papadaki, Maria I.; Kounalakis, Manolis; Vazquez-Carreto, Victor; Pineda-Solano, Alba; Wang, Qingsheng; Mannan, M.Sam

2013-01-01

Highlights: • Hydroxylamine thermal decomposition enthalpy was measured using larger quantities. • The rate at which heat is evolved depends on hydroxylamine concentration. • Decomposition heat is strongly affected by the conditions and the selected baseline. • The need for enthalpy measurements using a larger reactant mass is pinpointed. • Hydroxylamine decomposition in the presence of argon is much faster than in air. -- Abstract: Thermal decomposition of hydroxylamine, NH 2 OH, was responsible for two serious accidents. However, its reactive behavior and the synergy of factors affecting its decomposition are not being understood. In this work, the global enthalpy of hydroxylamine decomposition has been measured in the temperature range of 130–150 °C employing isoperibolic calorimetry. Measurements were performed in a metal reactor, employing 30–80 ml solutions containing 1.4–20 g of pure hydroxylamine (2.8–40 g of the supplied reagent). The measurements showed that increased concentration or temperature, results in higher global enthalpies of reaction per unit mass of reactant. At 150 °C, specific enthalpies as high as 8 kJ per gram of hydroxylamine were measured, although in general they were in the range of 3−5 kJ g −1 . The accurate measurement of the generated heat was proven to be a cumbersome task as (a) it is difficult to identify the end of decomposition, which after a fast initial stage, proceeds very slowly, especially at lower temperatures and (b) the environment of gases affects the reaction rate

Thermal decomposition of hydroxylamine: Isoperibolic calorimetric measurements at different conditions

Energy Technology Data Exchange (ETDEWEB)

Adamopoulou, Theodora [Department of Environmental and Natural Resources Management, University of Western Greece (formerly of University of Ioannina), Seferi 2, Agrinio GR30100 (Greece); Papadaki, Maria I., E-mail: mpapadak@cc.uoi.gr [Department of Environmental and Natural Resources Management, University of Western Greece (formerly of University of Ioannina), Seferi 2, Agrinio GR30100 (Greece); Kounalakis, Manolis [Department of Environmental and Natural Resources Management, University of Western Greece (formerly of University of Ioannina), Seferi 2, Agrinio GR30100 (Greece); Vazquez-Carreto, Victor; Pineda-Solano, Alba [Mary Kay O’Connor Process Safety Center, Artie McFerrin Department of Chemical Engineering, Texas A and M University, College Station, TX 77843 (United States); Wang, Qingsheng [Department of Fire Protection and Safety and Department of Chemical Engineering, Oklahoma State University, 494 Cordell South, Stillwater, OK 74078 (United States); Mannan, M.Sam [Mary Kay O’Connor Process Safety Center, Artie McFerrin Department of Chemical Engineering, Texas A and M University, College Station, TX 77843 (United States)

2013-06-15

Highlights: • Hydroxylamine thermal decomposition enthalpy was measured using larger quantities. • The rate at which heat is evolved depends on hydroxylamine concentration. • Decomposition heat is strongly affected by the conditions and the selected baseline. • The need for enthalpy measurements using a larger reactant mass is pinpointed. • Hydroxylamine decomposition in the presence of argon is much faster than in air. -- Abstract: Thermal decomposition of hydroxylamine, NH{sub 2}OH, was responsible for two serious accidents. However, its reactive behavior and the synergy of factors affecting its decomposition are not being understood. In this work, the global enthalpy of hydroxylamine decomposition has been measured in the temperature range of 130–150 °C employing isoperibolic calorimetry. Measurements were performed in a metal reactor, employing 30–80 ml solutions containing 1.4–20 g of pure hydroxylamine (2.8–40 g of the supplied reagent). The measurements showed that increased concentration or temperature, results in higher global enthalpies of reaction per unit mass of reactant. At 150 °C, specific enthalpies as high as 8 kJ per gram of hydroxylamine were measured, although in general they were in the range of 3−5 kJ g{sup −1}. The accurate measurement of the generated heat was proven to be a cumbersome task as (a) it is difficult to identify the end of decomposition, which after a fast initial stage, proceeds very slowly, especially at lower temperatures and (b) the environment of gases affects the reaction rate.

Exploiting Locality in Quantum Computation for Quantum Chemistry.

Science.gov (United States)

McClean, Jarrod R; Babbush, Ryan; Love, Peter J; Aspuru-Guzik, Alán

2014-12-18

Accurate prediction of chemical and material properties from first-principles quantum chemistry is a challenging task on traditional computers. Recent developments in quantum computation offer a route toward highly accurate solutions with polynomial cost; however, this solution still carries a large overhead. In this Perspective, we aim to bring together known results about the locality of physical interactions from quantum chemistry with ideas from quantum computation. We show that the utilization of spatial locality combined with the Bravyi-Kitaev transformation offers an improvement in the scaling of known quantum algorithms for quantum chemistry and provides numerical examples to help illustrate this point. We combine these developments to improve the outlook for the future of quantum chemistry on quantum computers.

Effect of Preparation Method on Catalytic Properties of Co-Mn-Al Mixed Oxides for N2O Decomposition.

Czech Academy of Sciences Publication Activity Database

Klyushina, A.; Pacultová, K.; Karásková, K.; Jirátová, Květa; Ritz, M.; Fridrichová, D.; Volodorskaja, A.; Obalová, L.

2016-01-01

Roč. 425, DEC 15 (2016), s. 237-247 ISSN 1381-1169 R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : Co-Mn-Al mixed oxide * N2O decomposition * preparation methods Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 4.211, year: 2016

Spectral decomposition of MR spectroscopy signatures with use of eigenanalysis

International Nuclear Information System (INIS)

Hearshen, D.O.; Windham, J.P.; Roebuck, J.R.; Helpern, J.A.

1989-01-01

Partial-volume contamination and overlapping resonances are common problems in whole-body MR spectroscopy and can affect absolute or relative intensity and chemical-shift measurements. One technique, based on solution of constrained eigenvalue problems, treats spectra as N-dimensional signatures and minimizes contributions of undesired signatures while maximizing contributions of desired signatures in compromised spectra. Computer simulations and both high-resolution (400-MHz) and whole-body (63.8-MHz) phantom studies tested accuracy and reproducibility of spectral decomposition. Results demonstrated excellent decomposition and good reproducibility within certain constraints. The authors conclude that eigenanalysis may improve quantitation of spectra without introducing operator bias

Water Complexes of Cytochrome P450: Insights from Energy Decomposition Analysis

Directory of Open Access Journals (Sweden)

Hajime Hirao

2013-06-01

Full Text Available Water is a small molecule that nevertheless perturbs, sometimes significantly, the electronic properties of an enzyme’s active site. In this study, interactions of a water molecule with the ferric heme and the compound I (Cpd I intermediate of cytochrome P450 are studied. Energy decomposition analysis (EDA schemes are used to investigate the physical origins of these interactions. Localized molecular orbital EDA (LMOEDA implemented in the quantum chemistry software GAMESS and the EDA method implemented in the ADF quantum chemistry program are used. EDA reveals that the electrostatic and polarization effects act as the major driving force in both of these interactions. The hydrogen bonding in the Cpd I•••H2O complex is similar to that in the water dimer; however, the relative importance of the electrostatic effect is somewhat larger in the water dimer.

Effects of hydrogen and propylene presence on decomposition of hydrogen peroxide over palladium catalysts

NARCIS (Netherlands)

Chen, T.; Kertalli, E.; Nijhuis, T.A.; Podkolzin, S.

2016-01-01

Reaction rates for H2O2 decomposition in a methanol solution were measured over Pd/SiO2 catalysts in the presence of gas-phase N2, H2 and propylene. The H2O2 decomposition rates were higher in the presence of H2 and lower in the presence of propylene compared to those under N2, which acted as an

Thermal decomposition and reaction of confined explosives

International Nuclear Information System (INIS)

Catalano, E.; McGuire, R.; Lee, E.; Wrenn, E.; Ornellas, D.; Walton, J.

1976-01-01

Some new experiments designed to accurately determine the time interval required to produce a reactive event in confined explosives subjected to temperatures which will cause decomposition are described. Geometry and boundary conditions were both well defined so that these experiments on the rapid thermal decomposition of HE are amenable to predictive modelling. Experiments have been carried out on TNT, TATB and on two plastic-bonded HMX-based high explosives, LX-04 and LX-10. When the results of these experiments are plotted as the logarithm of the time to explosion versus 1/T K (Arrhenius plot), the curves produced are remarkably linear. This is in contradiction to the results obtained by an iterative solution of the Laplace equation for a system with a first order rate heat source. Such calculations produce plots which display considerable curvature. The experiments have also shown that the time to explosion is strongly influenced by the void volume in the containment vessel. Results of the experiments with calculations based on the heat flow equations coupled with first-order models of chemical decomposition are compared. The comparisons demonstrate the need for a more realistic reaction model

Fe(III)-loaded collagen fiber as a heterogeneous catalyst for the photo-assisted decomposition of Malachite Green

International Nuclear Information System (INIS)

Liu Xiaohu; Tang Rui; He Qiang; Liao Xuepin; Shi Bi

2010-01-01

A heterogeneous catalyst for Fenton reaction was prepared by immobilizing Fe(III) onto collagen fiber and its catalytic activity for the photo-assisted decomposition of Malachite Green (MG) was investigated. The results indicated that this Fe(III)-immobilized collagen fiber (Fe-CF) can effectively catalyse the decoloration and decomposition/mineralization of MG in aqueous solution. Catalysed by Fe-CF, MG solution was completely decolorized in 30 min, while 55.0% of TOC was removed from the dye solution within 120 min in the presence of H 2 O 2 and UVA irradiation (365 nm, 10 W). Fe-CF was recycled for seven times with certain activity loss (32.6% in decoloration, 18.5% in TOC removal), and its catalytic activity can be easily recovered by re-immobilization of Fe(III). Therefore, Fe-CF could act as an efficient and cost-effective catalyst for the photo-assisted decomposition of MG, and shows potential applications in practice.

Isotopic echange of .sup.18./sup.O as a tool in studies of N2O decomposition over Fe-zeolites

Czech Academy of Sciences Publication Activity Database

Nováková, Jana; Sobalík, Zdeněk

2007-01-01

Roč. 6, - (2007), s. 55-68 ISSN 0972-4508 R&D Projects: GA AV ČR 1ET400400413 Institutional research plan: CEZ:AV0Z40400503 Keywords : N2O decomposition * 18O2 * Fe-zeolites Subject RIV: CF - Physical ; Theoretical Chemistry

Chemistry management system for nuclear power plants

International Nuclear Information System (INIS)

Nagasawa, Katsumi; Maeda, Katsuji

1998-01-01

Recently, the chemistry management in the nuclear power plants has been changing from the problem solution to the predictive diagnosis and maintenance. It is important to maintain the integrity of plant operation by an adequate chemistry control. For these reasons, many plant operation data and chemistry analysis data should be collected and treated effectively to evaluate chemistry condition of the nuclear power plants. When some indications of chemistry anomalies occur, quick and effective root cause evaluation and countermeasures should be required. The chemistry management system has been developed as to provide sophisticate chemistry management in the nuclear power plants. This paper introduces the concept and functions of the chemistry management system for the nuclear power plants. (author)

Effects of feed solution chemistry on low pressure reverse osmosis filtration of cesium and strontium

Energy Technology Data Exchange (ETDEWEB)

Ding, Shiyuan, E-mail: dingshiyuan@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Yang, Yu, E-mail: yangyu@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Huang, Haiou, E-mail: huanghaiou@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Liu, Hengchen, E-mail: 799599501@qq.com [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Hou, Li-an, E-mail: houlian678@hotmail.com [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Xi’an High-Tech Institute, No. 2, Tongxin Street, Baqiao District, Xi’an 710025 (China)

2015-08-30

Highlights: • A low pressure spiral wound RO membrane can reject Cs and Sr efficiently. • The rejection of Cs and Sr is dependent on feed pH and co-existing ions. • Donnan exclusion and electrostatic interaction govern the rejection of Cs and Sr. • The differences of filtration mechanism were influenced by the size of ions. • Sr could strengthen the irreversible membrane fouling resistance with HA. - Abstract: The objective of this study was to identify the removal mechanisms of radionuclides by reverse osmosis (RO) membranes under conditions relevant to full-scale water treatment. For this purpose, the effects of feed solution chemistry on the removal of Cs and Sr by a low pressure RO system was investigated by systematically varying membrane surface charge, ionic composition, and organic matter concentrations. The results showed that the effects of solution chemistry on the filtration of Cs and Sr were related to their hydrated ionic radius, resulting in the predominance of the Donnan’s effect and electrostatic interactions, respectively. Consequently, the rejection of Cs increased more pronouncedly than Sr with the increases of feed concentration. Due to the Donnan’s effect, different anions decreased the rejection of Cs to different extents in accordance to the order of anions’ radii as SO{sub 4}{sup 2−} > Cl{sup −} > NO{sub 3}{sup −} > F{sup −}. The variations in Sr rejection were influenced by the electrostatic interactions between Sr{sup 2+} and the membrane. In addition, humic acid (HA) lowered the rejection of Cs and caused significant membrane flux decline, but did not change the rejection of Sr. Sr also aggravated HA fouling of the membrane.

The water chemistry of CANDU PHW reactors

International Nuclear Information System (INIS)

LeSurf, J.E.

1978-01-01

This review will discuss the chemistry of the three major water circuits in a CANDU-PHW reactor, viz., the Primary Heat Transport (PHT) water, the moderator and the boiler water. An important consideration for the PHT chemistry is the control of corrosion and of the transport of corrosion products to minimize the growth of radiation fields. In new reactors the PHT will be allowed to boil, requiring reconsideration of the methods used to radiolytic oxygen and elevate the pH. Separation of the moderator from the PHT in the pressure-tubed CANDU design permits better optimization of the chemistry of each system, avoiding the compromises necessary when the same water serves both functions. Major objectives in moderator chemistry are to control (a) the radiolytic decomposition of D 2 0; (b) the concentration of soluble neutron poisons added to adjust reactivity; and (c) the chemistry of shutdown systems. The boiler water and its feed water are treated to avoid boiler tube corrosion, both during normal operation and when perturbations are caused to the feed by, for example, leaks in the condenser tubes which permit ingress of untreated condenser cooling water. Development of a system for automatic analysis and control of feed water to give rapid, reliable response to abnormal conditions is a novel feature which has been developed for incorporation in future CANDU-PHW reactors. (author)

Role of active oxygen and NOx species in N2O decomposition over Fe-ferrierite

Czech Academy of Sciences Publication Activity Database

Sobalík, Zdeněk; Tabor, Edyta; Nováková, Jana; Sathu, Naveen Kumar; Závěta, K.

2012-01-01

Roč. 289, MAY 2012 (2012), s. 164-170 ISSN 0021-9517 R&D Projects: GA AV ČR KAN100400702; GA ČR GA203/09/1627; GA ČR GAP106/11/0624 Institutional research plan: CEZ:AV0Z40400503 Keywords : N2O decomposition * iron ferrierite * active oxygen Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.787, year: 2012

N2O decomposition over Fe-FER: A Mössbauer study of the active sites

Czech Academy of Sciences Publication Activity Database

Tabor, Edyta; Závěta, K.; Sathu, Naveen Kumar; Vondrová, Alena; Sazama, Petr; Sobalík, Zdeněk

2011-01-01

Roč. 175, č. 1 (2011), s. 238-244 ISSN 0920-5861 R&D Projects: GA AV ČR KAN100400702; GA ČR GA203/09/1627; GA ČR GP203/08/P593 Institutional research plan: CEZ:AV0Z40400503 Keywords : iron fer rierites * N2O decomposition * cationic sites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.407, year: 2011

Applications of tensor (multiway array) factorizations and decompositions in data mining

DEFF Research Database (Denmark)

Mørup, Morten

2011-01-01

Tensor (multiway array) factorization and decomposition has become an important tool for data mining. Fueled by the computational power of modern computer researchers can now analyze large-scale tensorial structured data that only a few years ago would have been impossible. Tensor factorizations...... have several advantages over two-way matrix factorizations including uniqueness of the optimal solution and component identification even when most of the data is missing. Furthermore, multiway decomposition techniques explicitly exploit the multiway structure that is lost when collapsing some...... of the modes of the tensor in order to analyze the data by regular matrix factorization approaches. Multiway decomposition is being applied to new fields every year and there is no doubt that the future will bring many exciting new applications. The aim of this overview is to introduce the basic concepts...

Retention of dead standing plant biomass (marcescence) increases subsequent litter decomposition in the soil organic layer

Czech Academy of Sciences Publication Activity Database

Angst, Šárka; Cajthaml, T.; Angst, Gerrit; Šimáčková, H.; Brus, Jiří; Frouz, Jan

2017-01-01

Roč. 418, 1-2 (2017), s. 571-579 ISSN 0032-079X Institutional support: RVO:60077344 ; RVO:61389013 Keywords : photodegradation * C-13 CP/MAS NMR spectroscopy * litter decomposition * pyrolysis GC-MS * Calamagrostis epigeios * photo-facilitation Subject RIV: DF - Soil Science; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Soil science; Polymer science (UMCH-V) Impact factor: 3.052, year: 2016

Domain decomposition methods for core calculations using the MINOS solver

International Nuclear Information System (INIS)

Guerin, P.; Baudron, A. M.; Lautard, J. J.

2007-01-01

Cell by cell homogenized transport calculations of an entire nuclear reactor core are currently too expensive for industrial applications, even if a simplified transport (SPn) approximation is used. In order to take advantage of parallel computers, we propose here two domain decomposition methods using the mixed dual finite element solver MINOS. The first one is a modal synthesis method on overlapping sub-domains: several Eigenmodes solutions of a local problem on each sub-domain are taken as basis functions used for the resolution of the global problem on the whole domain. The second one is an iterative method based on non-overlapping domain decomposition with Robin interface conditions. At each iteration, we solve the problem on each sub-domain with the interface conditions given by the solutions on the close sub-domains estimated at the previous iteration. For these two methods, we give numerical results which demonstrate their accuracy and their efficiency for the diffusion model on realistic 2D and 3D cores. (authors)

Influence of solution chemistry on the boron content in inorganic calcite grown in artificial seawater

Science.gov (United States)

Uchikawa, Joji; Harper, Dustin T.; Penman, Donald E.; Zachos, James C.; Zeebe, Richard E.

2017-12-01

The ratio of boron to calcium (B/Ca) in marine biogenic carbonates has been proposed as a proxy for properties of seawater carbonate chemistry. Applying this proxy to planktic foraminifera residing in the surface seawater largely in equilibrium with the atmosphere may provide a valuable handle on past atmospheric CO2 concentrations. However, precise controls on B/Ca in planktic foraminifera remain enigmatic because it has been shown to depend on multiple physicochemical seawater properties. To help establish a firm inorganic basis for interpreting the B/Ca records, we examined the effect of a suite of chemical parameters ([Ca2+], pH, [DIC], salinity and [PO43-]) on B/Ca in inorganic calcite precipitated in artificial seawater. These parameters were primarily varied individually while keeping all others constant, but we also tested the influence of pH and [DIC] at a constant calcite precipitation rate (R) by concurrent [Ca2+] adjustments. In the simple [Ca2+], pH and [DIC] experiments, both R and B/Ca increased with these parameters. In the pH-[Ca2+] and [DIC]-[Ca2+] experiments at constant R, on the other hand, B/Ca was invariant at different pH and decreased with [DIC], respectively. These patterns agree with the behavior of solution [BTotal/DIC] ratio such that, at a fixed [BTotal], it is independent of pH but decreases with [DIC]. Based on these results, R and [BTotal/DIC] ratio appear to be the primary controls on B/Ca in inorganic calcite, suggesting that both B(OH)4- and B(OH)3 are possibly involved in B incorporation. Moreover, B/Ca modestly increased with salinity and [PO43-]. Inorganic calcite precipitated at higher R and in the presence of oxyanions such as SO42- and PO43- in growth solutions often undergoes surface roughening due to formation of crystallographic defects, vacancies and, occasionally, amorphous/hydrous CaCO3. These non-lattice sites may provide additional space for B, particularly B(OH)3. Consequently, besides the macroscopic influence of

The impact of solution chemistry of electrolyte on the sorption of pentachlorophenol and phenanthrene by natural hematite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zeng, Fanfeng; He, Yan, E-mail: yhe2006@zju.edu.cn; Lian, Zhenghua; Xu, Jianming, E-mail: jmxu@zju.edu.cn

2014-01-01

Hematite nanoparticles (NPs) were studied as a sorbent for hydrophobic organic contaminants (OCs) under natural ambient conditions through specially designed contrasting solution chemistry of electrolyte. Ionizable pentachlorophenol (PCP) and non-ionizable phenanthrene (PHE) were selected as representative OCs. The sorption capacities of PCP and PHE were pH-dependent, and a larger amount of PCP was sorbed at pH values below its pK{sub a} (4.75). However, the PHE sorption capacity was higher at relatively high or low pHs (e.g. below 4.0 and above 10.0), possibly due to the larger available surface area of the hematite NPs, caused by the higher values of net charges and charge density. Changes in pH might thus affect the sorption of OCs by hematite NPs, through modification of the surface characteristics of the sorbent and the electronic properties of the sorbate molecules. The influence of different ionic strengths indicated that the amounts of PCP and PHE sorbed by hematite NPs decreased as a concentration function of different types of ions (e.g. Na{sup +}, K{sup +}, Mg{sup 2 +} and Ca{sup 2 +}), with the underlying mechanism possibly being due to four interactions i.e. hydrogen-bonding, competitive sorption by ions in the ambient solution, screening effects and aggregation effects. The results confirmed that the surface chemistry of hematite NPs, the chemical properties of PCP and PHE, and solution chemistry (e.g. pH and ionic strength) of the electrolyte all played an important role in PCP and PHE sorption by hematite NPs. By comparison of both sorption capacity and ecologic advantages, our results suggested that natural hematite NPs would be more competitive and efficient for PCP and PHE sorption than engineered NPs. This finding increases our knowledge regarding the environmental function of natural NPs (such as hematite NPs) for OC remediation through manipulating their interfacial behavior. - Highlights: •Hematite NPs was tested for PCP/PHE sorption under

Reactivity of nanoaggregations of platinum on supports of different nature in reactions of catalytic decomposition of hydrazine in acid media

International Nuclear Information System (INIS)

Anan'ev, A.V.; Boltoeva, M.Yu.; Grigor'ev, M.S.; Shilov, V.P.; Sharygin, L.M.

2006-01-01

Platinized catalysts on the basis of supports of different chemical nature are tested in reactions of catalytic hydrazine decomposition in perchloric and nitric acid solutions. In perchloric acid catalytic activity of catalysts on the basis of ceramic materials of Termoksid brand is higher of activity of catalysts on the basis of amorphous silica gel. In nitric acid solutions opposite dependence is observed. Tendency of ceramic supports to peptization in acid solutions is pointed out. Results obtained are interpreted using conceptions of energetic heterogeneity of surface atoms and hydrazine catalytic decomposition mechanisms in different media [ru

Effects of lime and wood ash on soil-solution chemistry, soil chemistry and nutritional status of a pine stand in northern Germany

International Nuclear Information System (INIS)

Ludwig, Bernard; Rumpf, Sabine; Mindrup, Michael; Meiwes, Karl-Josef; Khanna, Partap K.

2002-01-01

Lime and wood ash may be useful to improve acidic forest soils. A field experiment was conducted in a pine stand on a sandy podzol at Fuhrberg, Germany, which involved an application of dolomitic lime (3 t/ha) with three replications or wood ash (4.8 t/ha) without replications on the forest floor. During the 2 yr study period, lime affected the soil solution composition only slightly. Ash had a marked effect on solution chemistry of the mineral soil at 10 cm and the pH values dropped temporarily from 3.7 to 3.1. Nineteen months after the treatments, exchangeable calcium in the organic layer and mineral soil increased by 222 (lime addition) or 411 kg/ha (ash addition) and exchangeable magnesium increased by 101 (lime addition) or 39 kg/ha (ash addition). After ash addition, no marked change in heavy metal content was found below 4 cm of the organic layer. In the ash treatment, the potassium concentration of the 1-yr-old pine needles increased from 5.6 to 5.9 g/kg. This study suggests that ash from untreated wood may be recommended for amelioration of forest soils

Projection decomposition algorithm for dual-energy computed tomography via deep neural network.

Science.gov (United States)

Xu, Yifu; Yan, Bin; Chen, Jian; Zeng, Lei; Li, Lei

2018-03-15

Dual-energy computed tomography (DECT) has been widely used to improve identification of substances from different spectral information. Decomposition of the mixed test samples into two materials relies on a well-calibrated material decomposition function. This work aims to establish and validate a data-driven algorithm for estimation of the decomposition function. A deep neural network (DNN) consisting of two sub-nets is proposed to solve the projection decomposition problem. The compressing sub-net, substantially a stack auto-encoder (SAE), learns a compact representation of energy spectrum. The decomposing sub-net with a two-layer structure fits the nonlinear transform between energy projection and basic material thickness. The proposed DNN not only delivers image with lower standard deviation and higher quality in both simulated and real data, and also yields the best performance in cases mixed with photon noise. Moreover, DNN costs only 0.4 s to generate a decomposition solution of 360 × 512 size scale, which is about 200 times faster than the competing algorithms. The DNN model is applicable to the decomposition tasks with different dual energies. Experimental results demonstrated the strong function fitting ability of DNN. Thus, the Deep learning paradigm provides a promising approach to solve the nonlinear problem in DECT.

Thermal decomposition of organic solvent with nitric acid in nuclear fuel reprocessing plants

Energy Technology Data Exchange (ETDEWEB)

Koike, Tadao; Nishio, Gunji; Takada, Junichi; Tukamoto, Michio; Watanabe, Kouji [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Miyata, Sadaichirou

1995-02-01

Since a thermal decomposition of organic solvent containing TBP (tributyl phosphate) with nitric acid and heavy metal nitrates is an exothermic reaction, it is possible to cause an explosive decomposition of TBP-complex materials formed by a nitration between the solvent and nitric acid, if the solvent involving TBP-complex is heated upto a thermal limit in an evaporator to concentrate a fuel liquid solution from the extraction process in the reprocessing plant. In JAERI, the demonstration test for explosive decomposition of TBP-complex by the nitration was performed to elucidate the safety margin of the evaporator in the event of hypothetical explosion under auspices of the Science and Technology Agency. The demonstration test was carried out by heating TBP/n-dodecane solvent mixed with nitric acid and uranium nitrate. In the test, the thermal decomposition behavior of the solvent was examined, and also a kinematic reaction constant and a heat formation of the TBP-complex decomposition were measured by the test. In the paper, a safety analysis of a model evaporator was conducted during accidental conditions under the explosive decomposition of the solvent. (author).

Basic dye decomposition kinetics in a photocatalytic slurry reactor

International Nuclear Information System (INIS)

Wu, C.-H.; Chang, H.-W.; Chern, J.-M.

2006-01-01

Wastewater effluent from textile plants using various dyes is one of the major water pollutants to the environment. Traditional chemical, physical and biological processes for treating textile dye wastewaters have disadvantages such as high cost, energy waste and generating secondary pollution during the treatment process. The photocatalytic process using TiO 2 semiconductor particles under UV light illumination has been shown to be potentially advantageous and applicable in the treatment of wastewater pollutants. In this study, the dye decomposition kinetics by nano-size TiO 2 suspension at natural solution pH was experimentally studied by varying the agitation speed (50-200 rpm), TiO 2 suspension concentration (0.25-1.71 g/L), initial dye concentration (10-50 ppm), temperature (10-50 deg. C), and UV power intensity (0-96 W). The experimental results show the agitation speed, varying from 50 to 200 rpm, has a slight influence on the dye decomposition rate and the pH history; the dye decomposition rate increases with the TiO 2 suspension concentration up to 0.98 g/L, then decrease with increasing TiO 2 suspension concentration; the initial dye decomposition rate increases with the initial dye concentration up to a certain value depending upon the temperature, then decreases with increasing initial dye concentration; the dye decomposition rate increases with the UV power intensity up to 64 W to reach a plateau. Kinetic models have been developed to fit the experimental kinetic data well

Decomposition of Nitrous Oxide over Fe-Ferrierites. Effect of High-Temperature Pretreatment on the Formation of Deposited Oxygen

Czech Academy of Sciences Publication Activity Database

Nováková, Jana; Schwarze, Michael; Tvarůžková, Zdenka; Sobalík, Zdeněk

2004-01-01

Roč. 98, 2/3 (2004), s. 123-127 ISSN 1011-372X R&D Projects: GA AV ČR IBS4040016 Institutional research plan: CEZ:AV0Z4040901 Keywords : Fe-ferrierite * high-temperature treatment * effect on N2O decomposition Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.904, year: 2004

Rate of litter decomposition and microbial activity in an area of Caatinga

Directory of Open Access Journals (Sweden)

Patrícia Carneiro Souto

2013-12-01

Full Text Available In order to evaluate the decomposition of litter and microbial activity in an area of preserved Caatinga, an experiment was conducted in the Natural Heritage Private Reserve Tamanduá Farm in Santa Terezinha county, State of Paraiba. The decomposition rate was determined by using litter bags containing 30 g of litter, which were arranged on the soil surface in September 2003 and 20 bags were taken each month until September 2005. The collected material was oven dried and weighed to assess weight loss compared to initial weight. Microbial activity was estimated monthly by the quantification of carbon dioxide (CO2 released into the edaphic breathing process from the soil surface, and captured by KOH solution. Weight loss of litter after one year was 41.19% and, after two years, was 48.37%, indicating a faster decomposition in the first year. Data analysis showed the influence of season on litter decomposition and temperature on microbial activity.

Thermoelectric Efficiency Improvement in Vacuum Tubes of Decomposing Liquid Lithium-Ammonia Solutions

International Nuclear Information System (INIS)

Lee, Jungyoon; Kim, Miae; Shim, Kyuchol; Kim, Jibeom; Jeon, Joonhyeon

2013-01-01

Lithium-ammonia (Li-NH 3 ) solutions are possible to be successfully made under the vacuum condition but there still remains a problem of undergoing stable and reliable decomposition in vacuum for high-efficiency thermoelectric power generation. This paper describes a new method for improving the thermoelectric conversion efficiency of Li-NH 3 solutions in vacuum. The proposed method uses a ‘U’-shaped Pyrex vacuum tube for the preparation and decomposition of pure fluid Li-NH 3 solutions. The tube is shaped so that a gas passageway (‘U’) connecting both legs of the ‘U’ helps to balance pressure inside both ends of the tube (due to NH 3 gasification) during decomposition on the hot side. Thermoelectric experimental results show that solution reaction in the ‘U’-shaped tube proceeds more stably and efficiently than in the ‘U’-shaped tube, and consequently, thermoelectric conversion efficiency is improved. It is also proved that the proposed method can provide a reversible reaction, which can rotate between synthesis and decomposition in the tube, for deriving the long-time, high-efficiency thermoelectric power

Accelerating solutions of one-dimensional unsteady PDEs with GPU-based swept time-space decomposition

Science.gov (United States)

Magee, Daniel J.; Niemeyer, Kyle E.

2018-03-01

The expedient design of precision components in aerospace and other high-tech industries requires simulations of physical phenomena often described by partial differential equations (PDEs) without exact solutions. Modern design problems require simulations with a level of resolution difficult to achieve in reasonable amounts of time-even in effectively parallelized solvers. Though the scale of the problem relative to available computing power is the greatest impediment to accelerating these applications, significant performance gains can be achieved through careful attention to the details of memory communication and access. The swept time-space decomposition rule reduces communication between sub-domains by exhausting the domain of influence before communicating boundary values. Here we present a GPU implementation of the swept rule, which modifies the algorithm for improved performance on this processing architecture by prioritizing use of private (shared) memory, avoiding interblock communication, and overwriting unnecessary values. It shows significant improvement in the execution time of finite-difference solvers for one-dimensional unsteady PDEs, producing speedups of 2 - 9 × for a range of problem sizes, respectively, compared with simple GPU versions and 7 - 300 × compared with parallel CPU versions. However, for a more sophisticated one-dimensional system of equations discretized with a second-order finite-volume scheme, the swept rule performs 1.2 - 1.9 × worse than a standard implementation for all problem sizes.

Effect of solution chemistry on the adsorption of perfluorooctane sulfonate onto mineral surfaces.

Science.gov (United States)

Tang, Chuyang Y; Shiang Fu, Q; Gao, Dawen; Criddle, Craig S; Leckie, James O

2010-04-01

Perfluorooctane sulfonate (PFOS) is an emergent contaminant of substantial environmental concerns, yet very limited information has been available on PFOS adsorption onto mineral surfaces. PFOS adsorption onto goethite and silica was investigated by batch adsorption experiments under various solution compositions. Adsorption onto silica was only marginally affected by pH, ionic strength, and calcium concentration, likely due to the dominance of non-electrostatic interactions. In contrast, PFOS uptake by goethite increased significantly at high [H+] and [Ca2+], which was likely due to enhanced electrostatic attraction between the negatively charged PFOS molecules and positively charged goethite surface. The effect of pH was less significant at high ionic strength, likely due to electrical double layer compression. PFOS uptake was reduced at higher ionic strength for a strongly positively charged goethite surface (pH 3), while it increased for a weakly charged surface (pH 7 and 9), which could be attributed to the competition between PFOS-surface electrostatic attraction and PFOS-PFOS electrostatic repulsion. A conceptual model that captures PFOS-surface and PFOS-PFOS electrostatic interactions as well as non-electrostatic interaction was also formulated to understand the effect of solution chemistry on PFOS adsorption onto goethite and silica surfaces. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

PWR secondary water chemistry guidelines

International Nuclear Information System (INIS)

Bell, M.J.; Blomgren, J.C.; Fackelmann, J.M.

1982-10-01

Steam generators in pressurized water reactor (PWR) nuclear power plants have experienced tubing degradation by a variety of corrosion-related mechanisms which depend directly on secondary water chemistry. As a result of this experience, the Steam Generator Owners Group and EPRI have sponsored a major program to provide solutions to PWR steam generator problems. This report, PWR Secondary Water Chemistry Guidelines, in addition to presenting justification for water chemistry control parameters, discusses available analytical methods, data management and surveillance, and the management philosophy required to successfully implement the guidelines

γ-Irradiation-induced radiolysis of inulin in aqueous solutions

International Nuclear Information System (INIS)

Tsyba, I.A.; Revina, A.A.; Shostenko, A.G.

1997-01-01

Radiochemical transformations of inulin in aqueous solutions, in air, in the presence of inert gases, helium, nitrogen and in nitrous oxide exposed to various doses of 60 Co γ-irradiation were investigated. It was shown that interactions in inulin with OH radicals are principally responsible for radiolytic decomposition of inulin. The data on radiolysis of more simple model systems were used to make available decomposition spectra of γ-irradiated aerated aqueous solution of inulin. 9 refs., 6 figs

Thermal decomposition of hydroxylamine: isoperibolic calorimetric measurements at different conditions.

Science.gov (United States)

Adamopoulou, Theodora; Papadaki, Maria I; Kounalakis, Manolis; Vazquez-Carreto, Victor; Pineda-Solano, Alba; Wang, Qingsheng; Mannan, M Sam

2013-06-15

Thermal decomposition of hydroxylamine, NH2OH, was responsible for two serious accidents. However, its reactive behavior and the synergy of factors affecting its decomposition are not being understood. In this work, the global enthalpy of hydroxylamine decomposition has been measured in the temperature range of 130-150 °C employing isoperibolic calorimetry. Measurements were performed in a metal reactor, employing 30-80 ml solutions containing 1.4-20 g of pure hydroxylamine (2.8-40 g of the supplied reagent). The measurements showed that increased concentration or temperature, results in higher global enthalpies of reaction per unit mass of reactant. At 150 °C, specific enthalpies as high as 8 kJ per gram of hydroxylamine were measured, although in general they were in the range of 3-5 kJ g(-1). The accurate measurement of the generated heat was proven to be a cumbersome task as (a) it is difficult to identify the end of decomposition, which after a fast initial stage, proceeds very slowly, especially at lower temperatures and (b) the environment of gases affects the reaction rate. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparison of Chain Conformation of Poly(vinyl alcohol) in Solutions and Melts from Quantum Chemistry Based Molecular Dynamics Simulations

Science.gov (United States)

Jaffe, Richard; Han, Jie; Matsuda, Tsunetoshi; Yoon, Do; Langhoff, Stephen R. (Technical Monitor)

1997-01-01

Confirmations of 2,4-dihydroxypentane (DHP), a model molecule for poly(vinyl alcohol), have been studied by quantum chemistry (QC) calculations and molecular dynamics (MD) simulations. QC calculations at the 6-311G MP2 level show the meso tt conformer to be lowest in energy followed by the racemic tg, due to intramolecular hydrogen bond between the hydroxy groups. The Dreiding force field has been modified to reproduce the QC conformer energies for DHP. MD simulations using this force field have been carried out for DHP molecules in the gas phase, melt, and CHCl3 and water solutions. Extensive intramolecular hydrogen bonding is observed for the gas phase and CHCl3 solution, but not for the melt or aqueous solution, Such a condensed phase effect due to intermolecular interactions results in a drastic change in chain conformations, in agreement with experiments.

Lattice QCD with Domain Decomposition on Intel Xeon Phi Co-Processors

Energy Technology Data Exchange (ETDEWEB)

Heybrock, Simon; Joo, Balint; Kalamkar, Dhiraj D; Smelyanskiy, Mikhail; Vaidyanathan, Karthikeyan; Wettig, Tilo; Dubey, Pradeep

2014-12-01

The gap between the cost of moving data and the cost of computing continues to grow, making it ever harder to design iterative solvers on extreme-scale architectures. This problem can be alleviated by alternative algorithms that reduce the amount of data movement. We investigate this in the context of Lattice Quantum Chromodynamics and implement such an alternative solver algorithm, based on domain decomposition, on Intel Xeon Phi co-processor (KNC) clusters. We demonstrate close-to-linear on-chip scaling to all 60 cores of the KNC. With a mix of single- and half-precision the domain-decomposition method sustains 400-500 Gflop/s per chip. Compared to an optimized KNC implementation of a standard solver [1], our full multi-node domain-decomposition solver strong-scales to more nodes and reduces the time-to-solution by a factor of 5.

Implementation of domain decomposition and data decomposition algorithms in RMC code

International Nuclear Information System (INIS)

Liang, J.G.; Cai, Y.; Wang, K.; She, D.

2013-01-01

The applications of Monte Carlo method in reactor physics analysis is somewhat restricted due to the excessive memory demand in solving large-scale problems. Memory demand in MC simulation is analyzed firstly, it concerns geometry data, data of nuclear cross-sections, data of particles, and data of tallies. It appears that tally data is dominant in memory cost and should be focused on in solving the memory problem. Domain decomposition and tally data decomposition algorithms are separately designed and implemented in the reactor Monte Carlo code RMC. Basically, the domain decomposition algorithm is a strategy of 'divide and rule', which means problems are divided into different sub-domains to be dealt with separately and some rules are established to make sure the whole results are correct. Tally data decomposition consists in 2 parts: data partition and data communication. Two algorithms with differential communication synchronization mechanisms are proposed. Numerical tests have been executed to evaluate performance of the new algorithms. Domain decomposition algorithm shows potentials to speed up MC simulation as a space parallel method. As for tally data decomposition algorithms, memory size is greatly reduced

Decomposition method for analysis of closed queuing networks

Directory of Open Access Journals (Sweden)

Yu. G. Nesterov

2014-01-01

Full Text Available This article deals with the method to estimate the average residence time in nodes of closed queuing networks with priorities and a wide range of conservative disciplines to be served. The method is based on a decomposition of entire closed queuing network into a set of simple basic queuing systems such as M|GI|m|N for each node. The unknown average residence times in the network nodes are interrelated through a system of nonlinear equations. The fact that there is a solution of this system has been proved. An iterative procedure based on Newton-Kantorovich method is proposed for finding the solution of such system. This procedure provides fast convergence to solution. Today possibilities of proposed method are limited by known analytical solutions for simple basic queuing systems of M|GI|m|N type.

Thermal decomposition of biphenyl (1963); Decomposition thermique du biphenyle (1963)

Energy Technology Data Exchange (ETDEWEB)

Clerc, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1962-06-15

The rates of formation of the decomposition products of biphenyl; hydrogen, methane, ethane, ethylene, as well as triphenyl have been measured in the vapour and liquid phases at 460 deg. C. The study of the decomposition products of biphenyl at different temperatures between 400 and 460 deg. C has provided values of the activation energies of the reactions yielding the main products of pyrolysis in the vapour phase. Product and Activation energy: Hydrogen 73 {+-} 2 kCal/Mole; Benzene 76 {+-} 2 kCal/Mole; Meta-triphenyl 53 {+-} 2 kCal/Mole; Biphenyl decomposition 64 {+-} 2 kCal/Mole; The rate of disappearance of biphenyl is only very approximately first order. These results show the major role played at the start of the decomposition by organic impurities which are not detectable by conventional physico-chemical analysis methods and the presence of which accelerates noticeably the decomposition rate. It was possible to eliminate these impurities by zone-melting carried out until the initial gradient of the formation curves for the products became constant. The composition of the high-molecular weight products (over 250) was deduced from the mean molecular weight and the dosage of the aromatic C - H bonds by infrared spectrophotometry. As a result the existence in tars of hydrogenated tetra, penta and hexaphenyl has been demonstrated. (author) [French] Les vitesses de formation des produits de decomposition du biphenyle: hydrogene, methane, ethane, ethylene, ainsi que des triphenyles, ont ete mesurees en phase vapeur et en phase liquide a 460 deg. C. L'etude des produits de decomposition du biphenyle a differentes temperatures comprises entre 400 et 460 deg. C, a fourni les valeurs des energies d'activation des reactions conduisant aux principaux produits de la pyrolyse en phase vapeur. Produit et Energie d'activation: Hydrogene 73 {+-} 2 kcal/Mole; Benzene 76 {+-} 2 kcal/Mole; Metatriphenyle, 53 {+-} 2 kcal/Mole; Decomposition du biphenyle 64 {+-} 2 kcal/Mole; La

Solution chemistry and separation of metal ions in leached solution

International Nuclear Information System (INIS)

Shibata, J.

1991-01-01

The method to presume a dissolved state of metal ions in an aqueous solution and the technology to separate and concentrate metal ions in a leached solution are described in this paper. It is very important for the separation of metal ions to know the dissolved state of metal ions. If we know the composition of an aqueous solution and the stability constants of metal-ligand complexes, we can calculate and estimate the concentration of each species in the solution. Then, we can decide the policy to separate and concentrate metal ions. There are several methods for separation and purification; hydroxide precipitation method, sulfide precipitation method, solvent extraction method and ion exchange resin method. Solvent extraction has been used in purification processes of copper refinery, uranium refinery, platinum metal refinery and rare earth metal refinery. Fundamental process of solvent extraction, a kind of commercial extractants, a way of determining a suitable extractant and an equipment are discussed. Finally, it will be emphasized how the separation of rare earths is improved in solvent extraction. (author) 21 figs., 8 tabs., 8 refs

Effects of Radiosterilization on Sealed Aqueous Solutions

International Nuclear Information System (INIS)

Pandula, E.L.; Farkas, E.; Rácz, I.

1967-01-01

For aqueous solutions sensitive to heat,and in connection with the use of plastic ampoules, the need for applying radiosterilization is growing. Studying the possibilities of radiosterilization, experiments were made with the following: 0.1% atropine, 1.0% morphine, and 2% lidocain in aqueous solutions. The aim of the work was to establish whether the active ingredients of the injections suffer decomposition or not, to study the factors influencing the degradation and, furthermore, to make attempts to prevent decomposition. The samples were irradiated by 420 Ci 60 Co γ-radiation source. The applied doses were 1 to 2.5 Mrad, with a 10 4 to 2.5 x 10 5 rad/h dose intensity. After irradiation the change in colour, pH-value, concentration and UV-spectra were studied. Changes of the last three types were found. Studying the factors influencing decomposition it has been found that the degree of degradation was increased by the increase of radiation dose, increase of concentration, decrease of dose intensity, and increase of oxygen content in the atmosphere over the solution. Attempts were made to prevent degradation. Solutions were prepared with sulphite, ascorbic acid, and AET, and some measure of success was achieved, especially with the sulphite addition. (author)

Pretreatment of lignocellulosic biomass using Fenton chemistry

Science.gov (United States)

Pretreatment is a necessary step in “biomass to biofuel conversion” due to the recalcitrant nature of lignocellulosic biomass. White-rot fungi utilize peroxidases and hydrogen peroxide (in vivo Fenton chemistry) to degrade lignin. In an attempt to mimic this process, solution phase Fenton chemistry ...

Effects of wood ash on soil solution and chemistry of leaves in a beech stand

International Nuclear Information System (INIS)

Tothova, Slavka

2005-01-01

The short-term effects of wood ash fertilization on chemistry of soil solution and leaves were investigated in 4-year-old beech stand (Fagus sylvatica L.) on dystric cambisol in Central Spis. Four plots - the control plot and three plots with different ash treatments (different dose, date and method of application) were established. Plate lysimeters were installed under the upper layer of soil in depth 2 cm and 20 cm on the control plot and plot P1 with addition of wood ash 5 t/ha on the whole surface. Soil solution was collected in May - October 2002 every two weeks. Composite samples, which represent a one - month period, were analysed for pH, K, Ca, Mg, and NO 3 - . The leaves were collected 4 or 10 months after the treatment and analysed on Ca, K, Mg, P, S, N and heavy metals Cd, Pb, Cr and Hg. In the ash treatment the content of macronutrient increased (mainly K, Ca). Addition of ash did not increase of the content heavy metal in leaves

Electrolytic decomposition of N-nitrosodimethylamine in water

Energy Technology Data Exchange (ETDEWEB)

Volchek, K; Ladanowski, C; Somers, A; Whittaker, H [Environment Canada, Edmonton, AB (Canada). Emergencies Science Div.; Anantaraman, A [Ottawa Univ., ON (Canada). Electrochemical Science and Technology Centre

1996-12-31

The feasibility of electrically reducing N-nitrosodimethylamine (NDMA) in aqueous solutions was studied in a series of bench-scale experiments. The presence of nitrosamines in soil and groundwater is largely associated with missile fuels, but also with pesticides and other chemicals. Inexpensive carbon, stainless steel and nickel electrodes were used to perform the experiments. The electrodes, voltage and solution pH were the variables studied. Results showed that a higher rate of decomposition of NDMA occurred in acidic conditions using a relatively high potential applied to the electrodes. Further studies were suggested to optimize treatment conditions and evaluate the technical and economical feasibility of the process. 9 refs., 2 tabs., 2 figs.

Thermodynamic anomaly in magnesium hydroxide decomposition

International Nuclear Information System (INIS)

Reis, T.A.

1983-08-01

The Origin of the discrepancy in the equilibrium water vapor pressure measurements for the reaction Mg(OH) 2 (s) = MgO(s) + H 2 O(g) when determined by Knudsen effusion and static manometry at the same temperature was investigated. For this reaction undergoing continuous thermal decomposition in Knudsen cells, Kay and Gregory observed that by extrapolating the steady-state apparent equilibrium vapor pressure measurements to zero-orifice, the vapor pressure was approx. 10 -4 of that previously established by Giauque and Archibald as the true thermodynamic equilibrium vapor pressure using statistical mechanical entropy calculations for the entropy of water vapor. This large difference in vapor pressures suggests the possibility of the formation in a Knudsen cell of a higher energy MgO that is thermodynamically metastable by about 48 kJ / mole. It has been shown here that experimental results are qualitatively independent of the type of Mg(OH) 2 used as a starting material, which confirms the inferences of Kay and Gregory. Thus, most forms of Mg(OH) 2 are considered to be the stable thermodynamic equilibrium form. X-ray diffraction results show that during the course of the reaction only the equilibrium NaCl-type MgO is formed, and no different phases result from samples prepared in Knudsen cells. Surface area data indicate that the MgO molar surface area remains constant throughout the course of the reaction at low decomposition temperatures, and no significant annealing occurs at less than 400 0 C. Scanning electron microscope photographs show no change in particle size or particle surface morphology. Solution calorimetric measurements indicate no inherent hgher energy content in the MgO from the solid produced in Knudsen cells. The Knudsen cell vapor pressure discrepancy may reflect the formation of a transient metastable MgO or Mg(OH) 2 -MgO solid solution during continuous thermal decomposition in Knudsen cells

Implementation of a PETN failure model using ARIA's general chemistry framework

Energy Technology Data Exchange (ETDEWEB)

Hobbs, Michael L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-01-01

We previously developed a PETN thermal decomposition model that accurately predicts thermal ignition and detonator failure [1]. This model was originally developed for CALORE [2] and required several complex user subroutines. Recently, a simplified version of the PETN decomposition model was implemented into ARIA [3] using a general chemistry framework without need for user subroutines. Detonator failure was also predicted with this new model using ENCORE. The model was simplified by 1) basing the model on moles rather than mass, 2) simplifying the thermal conductivity model, and 3) implementing ARIA’s new phase change model. This memo briefly describes the model, implementation, and validation.

Decomposition of Nitrous Oxide Over Fe-Ferrierites. Effect of Deposited Oxygen on the Framework Oxygens Studied by 18O Isotopic Exchange

Czech Academy of Sciences Publication Activity Database

Nováková, Jana; Lhotka, M.; Tvarůžková, Zdenka; Sobalík, Zdeněk

2002-01-01

Roč. 83, 3/4 (2002), s. 215-220 ISSN 1011-372X R&D Projects: GA AV ČR IBS4040016; GA MŠk OC D15.20 Keywords : zeolite * iron * N2O decomposition Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.559, year: 2002

Climatic effects on decomposing litter and substrate chemistry along climatological gradients.

Science.gov (United States)

Berg, B.

2009-04-01

Climatic effects on decomposing litter and substrate chemistry along climatological gradients. B. Berg, Dipartimento Biologia Strutturale e Funzionale, Complesso Universitario, Monte San Angelo, via Cintia, I-80126 Napoli, Italy and Department of Forest Ecology, P.O. Box 27, University of Helsinki, FIN-00014, Helsinki, Finland. Studies of several processes, using climatic gradients do provide new information as compared with studies at e.g. a single site. Decomposition of plant litter in such gradients give response in decomposition rates to natural climate conditions. Thus Scots pine needle litter incubated in a climate gradient with annual average temperature (AVGT) ranging from -0.5 to 6.8oC had a highly significant increase in initial mass-loss rate with R2 = 0.591 (p<0.001) and a 5o increase in temperature doubled the mass-loss rate. As a contrast - needle litter of Norway spruce incubated in the same transect had no significant response to climate and for initial litter a 5o increase increased mass-loss rate c. 6%. For more decomposed Scots pine litter we could see that the effect of temperature on mass-loss rate gradually decreased until it disappeared. Long-term decomposition studies revealed differences in litter decomposition patterns along a gradient, even for the same type of litter. This could be followed by using an asymptotic function that gave, (i) a measure a maximum level of decomposition, (ii) the initial decomposition rate. Over a gradient the calculated maximum level of decomposition decreased with increasing AVGT. Other gradient studies revealed an effect of AVGT on litter chemical composition. Pine needle litter from stands under different climate conditions had nutrient concentrations related to AVGT. Thus N, P, K, and S were positively related to AVGT and Mn negatively, all of them significantly. This information may be used to explain the changing pattern in decomposition over the gradient.

Radiation chemistry and the environment

International Nuclear Information System (INIS)

Getoff, F.

1998-01-01

The rather strong and many-sided pollution of the environment (atmosphere, water resources, soil) as a consequence of human activities is summarized. The solution of the arised problems by application of radiation chemistry methods and the utilization of modern environmentally ''clean'' and economical technologies, founded on electron beam processing, are mentioned. Some basic environmental problems and their solution are briefly discussed: i) Removal of CO 2 from flue gases and its radiation induced utilization. ii) Principals for degradation of aqueous pollutants by electron beam processing in the presence of ozone (synergistic effect). The radiation chemistry as a modern and manifold discipline with very broad applications can also essentially contribute in the conservation of the environment

Radiation chemistry and the environment

International Nuclear Information System (INIS)

Getoff, Nikola

1999-01-01

The rather strong and many-sided pollution of the environment (atmosphere, water resources, soil) as a consequence of human activity is summarized. The solution of the arised problems by application of radiation chemistry methods and the utilization of modern environmentally 'clean' and economical technologies, founded on electron beam processing, are mentioned. Some basic environmental problems and their solution are briefly discussed. (i) Removal of CO 2 from flue gases and its radiation induced utilization. (ii) Principals for degradation of aqueous pollutants by electron beam processing in the presence of ozone (synergistic effect). The radiation chemistry as a modern and manifold discipline with very broad applications can also essentially contribute in the conservation of the environment

A MODIFIED DECOMPOSITION METHOD FOR SOLVING NONLINEAR PROBLEM OF FLOW IN CONVERGING- DIVERGING CHANNEL

Directory of Open Access Journals (Sweden)

MOHAMED KEZZAR

2015-08-01

Full Text Available In this research, an efficient technique of computation considered as a modified decomposition method was proposed and then successfully applied for solving the nonlinear problem of the two dimensional flow of an incompressible viscous fluid between nonparallel plane walls. In fact this method gives the nonlinear term Nu and the solution of the studied problem as a power series. The proposed iterative procedure gives on the one hand a computationally efficient formulation with an acceleration of convergence rate and on the other hand finds the solution without any discretization, linearization or restrictive assumptions. The comparison of our results with those of numerical treatment and other earlier works shows clearly the higher accuracy and efficiency of the used Modified Decomposition Method.

Oxygen effect in the radiolysis of triton X-100 aqueous solution

International Nuclear Information System (INIS)

Perkowski, J.; Mayer, J.

1994-01-01

Experiments with Triton X-100 as a model surfactant were performed under steady-state conditions, using deoxygenated solutions as well as those saturated with N 2 O, O 2 or N 2 O/O 2 mixtures. The Triton x-100 decomposition yield was dependent on the O 2 content of the irradiated system. Oxygen promoted surfactant decomposition in aqueous solution containing only Triton X-100. (author) 13 refs.; 1 tab

Thermal decomposition of uranylnitrate by the Spray-Dryer process

International Nuclear Information System (INIS)

Wildhagen, G.R.S.; Silva, G.C. da

1988-01-01

The proposal of this work consist in the thermal decomposition of uranyl nitrate solutions by the Spray-Dryer process aiming the production of highly reactive fluidized UO 3 , adequate for the use in posterior of reduction to UO 2 and hydrofluorination to UF 4 , in a fluidized bed for the obtention of UF 6 in the cicle of nuclear fuels. (author) [pt

Hitch code capabilities for modeling AVT chemistry

International Nuclear Information System (INIS)

Leibovitz, J.

1985-01-01

Several types of corrosion have damaged alloy 600 tubing in the secondary side of steam generators. The types of corrosion include wastage, denting, intergranular attack, stress corrosion, erosion-corrosion, etc. The environments which cause attack may originate from leaks of cooling water into the condensate, etc. When the contaminated feedwater is pumped into the generator, the impurities may concentrate first 200 to 400 fold in the bulk water, depending on the blowdown, and then further to saturation and dryness in heated tube support plate crevices. Characterization of local solution chemistries is the first step to predict and correct the type of corrosion that can occur. The pH is of particular importance because it is a major factor governing the rate of corrosion reactions. The pH of a solution at high temperature is not the same as the ambient temperature, since ionic dissociation constants, solubility and solubility products, activity coefficients, etc., all change with temperature. Because the high temperature chemistry of such solutions is not readily characterized experimentally, modeling techniques were developed under EPRI sponsorship to calculate the high temperature chemistry of the relevant solutions. In many cases, the effects of cooling water impurities on steam generator water chemistry with all volatile treatment (AVT), upon concentration by boiling, and in particular the resulting acid or base concentration can be calculated by a simple code, the HITCH code, which is very easy to use. The scope and applicability of the HITCH code are summarized

Catalytic Decomposition of Nitrous Oxide over Catalysts Prepared from Co/Mg-Mn/Al Hydrotalcite-like Compounds

Czech Academy of Sciences Publication Activity Database

Obalová, L.; Jirátová, Květa; Kovanda, F.; Pacultová, K.; Lacný, Z.; Mikulová, Zuzana

2005-01-01

Roč. 60, 3-4 (2005), s. 289-297 ISSN 0926-3373 R&D Projects: GA ČR(CZ) GA106/05/0366; GA ČR(CZ) GA104/04/2116; GA ČR(CZ) GA106/02/0523 Institutional research plan: CEZ:AV0Z40720504 Keywords : decomposition of nitrous oxide * hydrotalcite-like compounds Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.809, year: 2005

Design of supported bi-metallic nanoparticles based on Platinum and Palladium using Surface Organometallic Chemistry (SOMC)

KAUST Repository

Al-Shareef, Reem A.

2017-01-01

Well-defined silica supported bimetallic catalysts Pt100-x Pdx (where x is the molar ratio of Pd) are prepared by Surface Organometallic Chemistry (SOMC) via controlled decomposition of Pd2(allyl)2Cl2 on Pt/SiO2. For comparison purposes, Pt100-x Pdx

The application of the fall-vector method in decomposition schemes for the solution of integer linear programming problems

International Nuclear Information System (INIS)

Sergienko, I.V.; Golodnikov, A.N.

1984-01-01

This article applies the methods of decompositions, which are used to solve continuous linear problems, to integer and partially integer problems. The fall-vector method is used to solve the obtained coordinate problems. An algorithm of the fall-vector is described. The Kornai-Liptak decomposition principle is used to reduce the integer linear programming problem to integer linear programming problems of a smaller dimension and to a discrete coordinate problem with simple constraints

Treatment for hydrazine-containing waste water solution

Science.gov (United States)

Yade, N.

1986-01-01

The treatment for waste solutions containing hydrazine is presented. The invention attempts oxidation and decomposition of hydrazine in waste water in a simple and effective processing. The method adds activated charcoal to waste solutions containing hydrazine while maintaining a pH value higher than 8, and adding iron salts if necessary. Then, the solution is aerated.

Effects of Solution Chemistry on Nano-Bubbles Transport in Saturated Porous Media

Science.gov (United States)

Hamamoto, S.; Takemura, T.; Suzuki, K.; Nihei, N.; Nishimura, T.

2017-12-01

Nano-bubbles (NBs) have a considerable potential for the remediation of soil and groundwater contaminated by organic compounds, especially when used in conjunction with bioremediation technologies. Understanding the transport mechanisms of NBs in soils is essential to optimize NB-based remediation techniques. In this study, one-dimensional column transport experiments using glass beads with 0.1 mm size were conducted, where NBs created by oxygen gas at different pH and ionic strength were injected to the column at the constant flow rate. The NBs concentration in the effluent was quantified using a resonant mass measurement technique. Effects of solution chemistry of the NBs water on NB transport in the porous media were investigated. The results showed that attachment of NBs was enhanced under higher ionic strength and lower pH conditions, caused by the reduced repulsive force between NBs and glass beads. In addition, bubble size distributions in the effluents showed that relatively larger NBs were retained in the column. This trend was more significant at lower pH condition.

Catalytic N 2O decomposition on Pr 0.8Ba 0.2MnO 3 type perovskite catalyst for industrial emission control

Czech Academy of Sciences Publication Activity Database

Kumar, S.; Vinu, A.; Šubrt, Jan; Bakardjieva, Snejana; Rayalu, S.; Teraoka, Y.; Labhsetwar, N.

2012-01-01

Roč. 198, 1-SI (2012), s. 125-132 ISSN 0920-5861 R&D Projects: GA MŠk LC523 Institutional support: RVO:61388980 Keywords : Ba substituted perovskite * catalyst * honeycomb * N 2O decomposition * perovskite * praseodymium manganate Subject RIV: CA - Inorganic Chemistry Impact factor: 2.980, year: 2012

Radiolysis of spray solutions

International Nuclear Information System (INIS)

Habersbergerova, A.; Janovsky, I.

1985-01-01

The factors were studied affecting thiosulfate radiolysis in the so-called spray solution for nuclear power plant containments. The reaction mechanism of primary radiolytic reactions leading to thiosulfate decomposition was studied using pulse radiolysis. Also measured was hydrazine loss in the irradiation of the bubbling solution intended for the capture of volatile chemical forms of radioiodine. Pulse radiolysis was used to study the kinetics of hydrazine reaction with elemental iodine. (author)

NOx Binding and Dissociation: Enhanced Ferroelectric Surface Chemistry by Catalytic Monolayers

Science.gov (United States)

Kakekhani, Arvin; Ismail-Beigi, Sohrab

2013-03-01

NOx molecules are regulated air pollutants produced during automotive combustion. As part of an effort to design viable catalysts for NOx decomposition operating at higher temperatures that would allow for improved fuel efficiency, we examine NOx chemistry on ferroelectric perovskite surfaces. Changing the direction of ferroelectric polarization can modify surface electronic properties and may lead to switchable surface chemistry. Here, we describe our recent work on potentially enhanced surface chemistry using catalytic RuO2 monolayers on perovskite ferroelectric substrates. In addition to thermodynamic stabilization of the RuO2 layer, we present results on the polarization-dependent binding of NO, O2, N2, and atomic O and N. We present results showing that one key problem with current catalysts, involving the difficulty of releasing dissociation products (especially oxygen), can be ameliorated by this method. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

Decomposition techniques in mathematical programming engineering and science applications

CERN Document Server

Conejo, Antonio J; Minguez, Roberto; Garcia-Bertrand, Raquel

2006-01-01

Optimization plainly dominates the design, planning, operation, and c- trol of engineering systems. This is a book on optimization that considers particular cases of optimization problems, those with a decomposable str- ture that can be advantageously exploited. Those decomposable optimization problems are ubiquitous in engineering and science applications. The book considers problems with both complicating constraints and complicating va- ables, and analyzes linear and nonlinear problems, with and without in- ger variables. The decomposition techniques analyzed include Dantzig-Wolfe, Benders, Lagrangian relaxation, Augmented Lagrangian decomposition, and others. Heuristic techniques are also considered. Additionally, a comprehensive sensitivity analysis for characterizing the solution of optimization problems is carried out. This material is particularly novel and of high practical interest. This book is built based on many clarifying, illustrative, and compu- tional examples, which facilitate the learning p...

Template-assisted hydrothermally obtained titania-ceria composites and their application as catalysts in ethyl acetate oxidation and methanol decomposition with a potential for sustainable environment protection

Czech Academy of Sciences Publication Activity Database

Tsoncheva, T.; Mileva, A.; Issa, G.; Dimitrov, M.; Kovacheva, D.; Henych, Jiří; Scotti, N.; Kormunda, M.; Atanasova, G.; Štengl, Václav

2017-01-01

Roč. 396, FEB (2017), s. 1289-1302 ISSN 0169-4332 R&D Projects: GA MŠk(CZ) LM2015073 Grant - others:AV ČR(CZ) BAS-17-13 Program:Bilaterální spolupráce Institutional support: RVO:61388980 Keywords : Ceria-titania binary oxides * Template assisted hydrothermal synthesis * Methanol decomposition * Ethyl acetate oxidation Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 3.387, year: 2016

Polish contribution to radiation chemistry

International Nuclear Information System (INIS)

Kroh, J.

1989-01-01

This article outlines the history of radiation chemistry research in Poland from 1899 to the present day, with particular reference to radiolysis studies of aqueous solutions of radioactive compounds. (UK)

High-Performance Solution-Processed Amorphous InGaZnO Thin Film Transistors with a Metal–Organic Decomposition Method

Directory of Open Access Journals (Sweden)

Yingtao Xie

2018-01-01

Full Text Available A facile solution process was introduced for the preparation of IGZO thin films via a metal–organic decomposition (MOD method. The IGZO ink was synthesized by mixing the solutions of gallium acetylacetonate [Ga(C5H7O23], zinc acetylacetonate hydrate [Zn(C5H7O22·xH2O] dissolved in ethanol, and indium acetylacetonate [In(C5H7O23] dissolved in tetrahydrofuran (THF. The deposited films by spin-coating were annealed at moderate process temperature (≤500°C. The relationship between device performance and postannealing temperature was studied. The result demonstrated that mobility of IGZO TFT increased as the annealing temperature increased. Based on the analysis of O 1s statement, the annealing temperature can influence the number of oxygen vacancy to further affect the carrier centration. In addition, the IGZO TFT devices with various Ga molar ratios were compared to demonstrate the influence of the Ga addition. The result demonstrated that the saturated mobilities (μe decreased and VTH shifted to positive voltage as the Ga molar ratio was increased. It is likely that Ga can offer stronger chemical bonds between metal and oxygen that reduced the concentration of free carriers and thus help reducing VTH. As a result, the optimized performance of IGZO TFT with the mobility of 3.4 cm2V−1s−1 showed the MOD process was a promising approach.

Hydroxylamine Nitrate Decomposition under Non-radiological Conditions

Energy Technology Data Exchange (ETDEWEB)

McFarlane, Joanna [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Delmau, Laetitia Helene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); DePaoli, David W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mattus, Catherine H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Phelps, Clarice E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Roach, Benjamin D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-07-01

Hydroxylamine nitrate (HAN) is used to reduce Pu(IV) to Pu(III) in the separation of plutonium from uranium. HAN becomes unstable under certain conditions and has been known to explode, causing injury to humans including death. Hence, it is necessary to deactivate HAN once the reduction of plutonium is finished. This report reviews what is known about the chemistry of HAN and various methods to achieve a safe decomposition. However, there are areas where more information is needed to make a decision about the handling of HAN in reprocessing of nuclear fuel. Experiments have demonstrated a number of non-radiolytic ways to safely decompose HAN, including heating in HNO3, photolytic oxidation in the presence of H2O2, and the addition of a metal such as Fe(III) that will oxidize the HAN.

Decompositions of manifolds

CERN Document Server

Daverman, Robert J

2007-01-01

Decomposition theory studies decompositions, or partitions, of manifolds into simple pieces, usually cell-like sets. Since its inception in 1929, the subject has become an important tool in geometric topology. The main goal of the book is to help students interested in geometric topology to bridge the gap between entry-level graduate courses and research at the frontier as well as to demonstrate interrelations of decomposition theory with other parts of geometric topology. With numerous exercises and problems, many of them quite challenging, the book continues to be strongly recommended to eve

Radiation-induced decomposition of small amounts of trichloroethylene in drinking water

International Nuclear Information System (INIS)

Proksch, E.; Gehringer, P.; Szinovatz, W.; Eschweiler, H.

1989-01-01

Solutions of 10 ppm trichloroethylene in air-saturated drinking waters are decomposed by γ radiation with initial G-values, G 0 , around 3-5 molecules per 100 eV. At lower concentrations, the G 0 -values decrease with decreasing trichloroethylene concentration and with increasing amounts of inorganic (especially HCO 3 - ) and organic solutes. From the results, a semi-empirical formula is derived which allows an estimation of G 0 -values for the trichloroethylene decomposition in drinking waters of given composition. (author)

Kinetics of acid leaching of ilmenite decomposed by KOH part 1: decomposition by KOH and leaching by HCl

International Nuclear Information System (INIS)

Nayl, A.A; Aly, H.F.

2010-01-01

Decomposition of ilmenite by KOH solutions, to convert titanium to potassium titanate, was first studied . This was followed by leaching titanium from the ilmenite paste using HCl solutions in the temperature range 50-150 degree C for different periods up to 3 hr. The significant factors affecting the leaching process were studied. The experimental data of the decomposition rate of ilmenite by KOH and of the formed KOH paste by HCl under the relevant operating variables were interpreted with the shrinking core model under chemically controlled process. The apparent activation energy for leaching of titanium in both cases bas been evaluated and discussed.

Promoting sustainability through green chemistry

Energy Technology Data Exchange (ETDEWEB)

Kirchhoff, Mary M. [American Chemical Society, 1155 Sixteenth Street, NW, Washington, DC 20036 (United States)

2005-06-15

Green chemistry is an important tool in achieving sustainability. The implementation of green chemistry, the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances, is essential if the expanding global population is to enjoy an increased standard of living without having a negative impact on the health of the planet. Cleaner technologies will allow the chemical enterprise to provide society with the goods and services on which it depends in an environmentally responsible manner. Green chemistry provides solutions to such global challenges as climate change, sustainable agriculture, energy, toxics in the environment, and the depletion of natural resources. A collaborative effort by industry, academia, and government is needed to promote the adoption of the green chemistry technologies necessary to achieve a sustainable society.

Thermal decomposition of pyrite

International Nuclear Information System (INIS)

Music, S.; Ristic, M.; Popovic, S.

1992-01-01

Thermal decomposition of natural pyrite (cubic, FeS 2 ) has been investigated using X-ray diffraction and 57 Fe Moessbauer spectroscopy. X-ray diffraction analysis of pyrite ore from different sources showed the presence of associated minerals, such as quartz, szomolnokite, stilbite or stellerite, micas and hematite. Hematite, maghemite and pyrrhotite were detected as thermal decomposition products of natural pyrite. The phase composition of the thermal decomposition products depends on the terature, time of heating and starting size of pyrite chrystals. Hematite is the end product of the thermal decomposition of natural pyrite. (author) 24 refs.; 6 figs.; 2 tabs

Danburite decomposition by sulfuric acid

International Nuclear Information System (INIS)

Mirsaidov, U.; Mamatov, E.D.; Ashurov, N.A.

2011-01-01

Present article is devoted to decomposition of danburite of Ak-Arkhar Deposit of Tajikistan by sulfuric acid. The process of decomposition of danburite concentrate by sulfuric acid was studied. The chemical nature of decomposition process of boron containing ore was determined. The influence of temperature on the rate of extraction of boron and iron oxides was defined. The dependence of decomposition of boron and iron oxides on process duration, dosage of H 2 SO 4 , acid concentration and size of danburite particles was determined. The kinetics of danburite decomposition by sulfuric acid was studied as well. The apparent activation energy of the process of danburite decomposition by sulfuric acid was calculated. The flowsheet of danburite processing by sulfuric acid was elaborated.

Volatility of ruthenium during vitrification operations on fission products. part 1. nitric solutions distillation concentrates calcination. part 2. fixation on a steel tube. decomposition of the peroxide; Volatilite du ruthenium au cours des operations de vitrification des produits de fission. 1. partie distillation des solutions nitriques calcination des concentrats 2. partie fixation sur un tube d'acier decomposition du peroxyde

Energy Technology Data Exchange (ETDEWEB)

Ortins de Bettencourt, A.; Jouan, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1969-07-01

During vitrification of fission product solutions, a high percentage of the ruthenium initially present in these solutions in the form of nitrosyl-ruthenium nitrates is volatilized with the production of the peroxide which itself is decomposed to ruthenium dioxide. The aim of this work has been to study the volatility of the ruthenium during the vitrification processes. During the distillation of the nitric solutions, we have studied in particular the influence on the volatility of the temperature , of the chemical form in which the ruthenium is introduced, of the bubbling of a gas through the solution, of the nitric concentration and of the nitrate concentration. During the calcination, we have observed the influence of the temperature, of the time, of the flow rate and of the nature of the carrier gas, as well as of the action of the ruthenium bi-oxide and the iron oxide on the volatility of the ruthenium. Part 2. This report deals with the study of the thermal decomposition of ruthenium peroxide, RuO{sub 4}, and its deposition on steel tubing. After a brief bibliographic review of the various properties of this substance, a study is made, in the first part, of its deposition on a steel tube. In order to do this, we pass a gas current containing RuO{sub 4} marked with {sup 106}Ru through a stainless steel tube subjected to a temperature gradient which decreases in the direction of the gas flow. The temperature at which RuO{sub 4} is deposited or is fixed on the tube is determined and the influence of the flow rate on this deposit is studied. In the second part, an attempt has been made to study by a static method the kinetics of the decomposition reaction of ruthenium peroxide to give the dioxide: RuO{sub 4} {yields} RuO{sub 2} + O{sub 2}. To do this, we have tried to introduce gaseous RuO{sub 4} into a container placed in an electric oven, and to follow the reaction by {gamma} counting. (author) [French] Au cours de la vitrification des solutions de produits de

Volatility of ruthenium during vitrification operations on fission products. part 1. nitric solutions distillation concentrates calcination. part 2. fixation on a steel tube. decomposition of the peroxide; Volatilite du ruthenium au cours des operations de vitrification des produits de fission. 1. partie distillation des solutions nitriques calcination des concentrats 2. partie fixation sur un tube d'acier decomposition du peroxyde

Energy Technology Data Exchange (ETDEWEB)

Ortins de Bettencourt, A; Jouan, A [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1969-07-01

During vitrification of fission product solutions, a high percentage of the ruthenium initially present in these solutions in the form of nitrosyl-ruthenium nitrates is volatilized with the production of the peroxide which itself is decomposed to ruthenium dioxide. The aim of this work has been to study the volatility of the ruthenium during the vitrification processes. During the distillation of the nitric solutions, we have studied in particular the influence on the volatility of the temperature , of the chemical form in which the ruthenium is introduced, of the bubbling of a gas through the solution, of the nitric concentration and of the nitrate concentration. During the calcination, we have observed the influence of the temperature, of the time, of the flow rate and of the nature of the carrier gas, as well as of the action of the ruthenium bi-oxide and the iron oxide on the volatility of the ruthenium. Part 2. This report deals with the study of the thermal decomposition of ruthenium peroxide, RuO{sub 4}, and its deposition on steel tubing. After a brief bibliographic review of the various properties of this substance, a study is made, in the first part, of its deposition on a steel tube. In order to do this, we pass a gas current containing RuO{sub 4} marked with {sup 106}Ru through a stainless steel tube subjected to a temperature gradient which decreases in the direction of the gas flow. The temperature at which RuO{sub 4} is deposited or is fixed on the tube is determined and the influence of the flow rate on this deposit is studied. In the second part, an attempt has been made to study by a static method the kinetics of the decomposition reaction of ruthenium peroxide to give the dioxide: RuO{sub 4} {yields} RuO{sub 2} + O{sub 2}. To do this, we have tried to introduce gaseous RuO{sub 4} into a container placed in an electric oven, and to follow the reaction by {gamma} counting. (author) [French] Au cours de la vitrification des solutions de produits de

Comparing numerical methods for the solutions of the Chen system

International Nuclear Information System (INIS)

Noorani, M.S.M.; Hashim, I.; Ahmad, R.; Bakar, S.A.; Ismail, E.S.; Zakaria, A.M.

2007-01-01

In this paper, the Adomian decomposition method (ADM) is applied to the Chen system which is a three-dimensional system of ODEs with quadratic nonlinearities. The ADM yields an analytical solution in terms of a rapidly convergent infinite power series with easily computable terms. Comparisons between the decomposition solutions and the classical fourth-order Runge-Kutta (RK4) numerical solutions are made. In particular we look at the accuracy of the ADM as the Chen system changes from a non-chaotic system to a chaotic one. To highlight some computational difficulties due to a high Lyapunov exponent, a comparison with the Lorenz system is given

Mutual complementation between water chemistry and isotope techniques

International Nuclear Information System (INIS)

Matthess, G.

1976-01-01

In the water chemistry and isotope methods which applied together enable more extensive statements to be made than each on its own, the following regions of cooperation are brought out: 1) Isotopes as conservative indicators a) microbial decomposition of organic substances in the anaerobic and aerobic region; b) precipitation and coprecipitation; c) mechanical filtration, adsorption and coprecipitation; d) gas exchange; e) dilution by infiltration; 2) geochemical observations as additional basis for isotope investigations; 3) the investigation of the water content substances as additional help to isotope hydrology. (HK/LH) [de

Physico-Chemical Study of the Separation of Calcium Isotopes by Chemical Exchange Between Amalgam and Salt Solutions; Etude physico-chimique de la separation des isotopes du calcium par echange chimique entre amalgame et solution saline

Energy Technology Data Exchange (ETDEWEB)

Duie, P; Dirian, G [Commissariat a l' Energie Atomique. Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

1962-07-01

In a preliminary study of the isotopic exchange between Ca amalgam and aqueous or organic solutions of Ca salts, the main parameters governing the feasibility of a separation process based on these systems such as separation factor, exchange kinetics, rate of decomposition of the amalgam were investigated. The separation factor between {sup 40}Ca and {sup 46}Ca was found to be of the order of 1.02. The rate of the exchange reaction is rather low for aqueous solutions, extremely low for organic solutions. The amalgam seems not to be attacked by dimethyl-formamide solutions; but it is rapidly decomposed by aqueous solutions of Ca halides. This decomposition is slow in the case of aqueous solutions of calcium formate and still slower for Ca(OH){sub 2}; however, except in particular conditions, the observed rate is often much higher, owing to interfering reactions between amalgam and water vapor contained in H{sub 2} bubbles. (authors) [French] On a fait une etude preliminaire, pour des systemes amalgame de calcium - solution aqueuse ou organique de sels de calcium, des principaux parametres pouvant intervenir dans l'application d'un procede d'echange a l'enrichissement isotopique du calcium: facteur de separation, cinetique de l'echange, cinetique de la decomposition de l'amalgame. Les facteurs de separation {sup 40}Ca-{sup 46}Ca sont de l'ordre de 1,02. L'echange est assez lent pour les solutions aqueuses, extremement lent pour les solutions organiques. La decomposition de l'amalgame est pratiquement inexistante avec les solutions dans le dimethyl- formamide, appreciable pour les solutions alcooliques, rapide pour les solutions aqueuses d'halogenures; elle est normalement lente pour les solutions aqueuses de formiate et surtout de chaux, mais la decomposition est en general acceleree par une reaction parasite entre l'amalgame et l'eau a l'etat vapeur, reaction que l'on n'evite dans des conditions tres particulieres. (auteurs)

Application of solution-mineral equilibrium chemistry to solution mining of uranium ores

International Nuclear Information System (INIS)

Riese, A.C.; Propp, C.J.

1980-01-01

Modern methods of uranium solution mining are typically accompanied by gains and losses of mass through reagent consumption by rock-forming minerals, with subsequent formation of clay minerals, gypsum, carbonates, and iron oxyhydroxides. A systematic approach to alleviate such problems involves the application of leach solutions that are in equilibrium with the host-rock minerals but in disequilibrium with the ore-forming minerals. This partial equilibrium can be approximated by solution-composition adjustments within the systems K 2 O-Al 2 O 3 SiO 2 -H 2 O and Na 2 O 3 -Al 2 O 3 SiO 2 -H 2 O. Uranium ore containing 0.15 percent U 3 O 8 from the Gulf Mineral Resources Corporation's Mariano Lake mine, the Smith Lake district of the Grants mineral belt, was collected for investigation. Presented are a theoretical evaluation of leachate data and an experimental treatment of the ore, which contained mainly K-feldspar, plagioclase feldspar, and quartz (with lesser amounts of micas, clay minerals, and organic carbonaceous material). Small-scale (less than or equal to 1 kg) column-leaching experiments were conducted to model the results of conventional leaching operations and to provide leachate solutions that could be compared with solutions calculated to be in equilibrium with the matrix minerals. Leach solutions employed include: 1) sulfuric acid, 2) sodium bicarbonate, and 3) sulfuric acid with 1.0 molal potassium chloride. The uranium concentrations in the sodium-bicarbonate leach solution and the acid-leach solution were about a gram per liter at the termination of the tests. However, the permeability of the ore in the acid leach was greatly reduced, owing to the formation of clay minerals. Uranium solubility in the leach column stabilized with the potassium-chloride solution was calculated from leachate compositions to be limited by the solubility of carnotite

Effect of Precursor Synthesis on Catalytic Activity of Co3O4 in N2O Decomposition.

Czech Academy of Sciences Publication Activity Database

Chromčáková, Ž.; Obalová, L.; Kovanda, F.; Legut, D.; Titov, A.; Ritz, M.; Fridrichová, D.; Michalik, S.; Kustrowski, P.; Jirátová, Květa

2015-01-01

Roč. 257, Part 1 (2015), s. 18-25 ISSN 0920-5861. [AWPAC2014 - International Symposium on Air & Water Pollution Abatement Catalysis. Krakow, 01.09.2014-05.09.2014] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : cobalt spinel * Co3O4 * N2O decomposition * precursor synthesis Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 4.312, year: 2015

N2O Catalytic Decomposition - Effect of Pelleting Pressure on Activity of Co-Mn-Al Mixed Oxide Catalyst

Czech Academy of Sciences Publication Activity Database

Galejová, K.; Obalová, L.; Jirátová, Květa; Pacultová, K.; Kovanda, F.

2009-01-01

Roč. 63, č. 2 (2009), s. 172-179 ISSN 0366-6352. [International Conference of the Slovak-Society-of-Chemical-Engineering /35./. Tatranske Matliare, 26.05.2008-30.05.2008] R&D Projects: GA ČR GA104/07/1400 Institutional research plan: CEZ:AV0Z40720504 Keywords : pelleting pressure * nitrous oxide * catalytic decomposition Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.791, year: 2009

Solving Fokker-Planck Equations on Cantor Sets Using Local Fractional Decomposition Method

Directory of Open Access Journals (Sweden)

Shao-Hong Yan

2014-01-01

Full Text Available The local fractional decomposition method is applied to approximate the solutions for Fokker-Planck equations on Cantor sets with local fractional derivative. The obtained results give the present method that is very effective and simple for solving the differential equations on Cantor set.

Representation of discrete Steklov-Poincare operator arising in domain decomposition methods in wavelet basis

Energy Technology Data Exchange (ETDEWEB)

Jemcov, A.; Matovic, M.D. [Queen`s Univ., Kingston, Ontario (Canada)

1996-12-31

This paper examines the sparse representation and preconditioning of a discrete Steklov-Poincare operator which arises in domain decomposition methods. A non-overlapping domain decomposition method is applied to a second order self-adjoint elliptic operator (Poisson equation), with homogeneous boundary conditions, as a model problem. It is shown that the discrete Steklov-Poincare operator allows sparse representation with a bounded condition number in wavelet basis if the transformation is followed by thresholding and resealing. These two steps combined enable the effective use of Krylov subspace methods as an iterative solution procedure for the system of linear equations. Finding the solution of an interface problem in domain decomposition methods, known as a Schur complement problem, has been shown to be equivalent to the discrete form of Steklov-Poincare operator. A common way to obtain Schur complement matrix is by ordering the matrix of discrete differential operator in subdomain node groups then block eliminating interface nodes. The result is a dense matrix which corresponds to the interface problem. This is equivalent to reducing the original problem to several smaller differential problems and one boundary integral equation problem for the subdomain interface.

Application of solution-mineral equilibrium chemistry to solution mining of uranium ores

International Nuclear Information System (INIS)

Riese, A.C.; Popp, C.J.

1979-01-01

The tests described were undertaken to determine the extent to leach solution-rock interactions with uranium-bearing ore obtained from the Mariano Lake mine. Leach solutions of an acidic (H/sub 2/O/sub 4/-sulfuric acid) and basic (NaHCO/sub 3/-sodium bicarbonate) nature were tested, in addition to a leach solution containing potassium chloride and sulfuric acid (KCl/H/sub 2/SO/sub 4/). The latter solution was chosen in an attempt to equilibrate the aqueous phase with the rock-forming silicate minerals and minimize adverse effects such as clay formation, porosity loss, and lixiviant loss. 29 refs

The use of Adomian decomposition method for solving problems in calculus of variations

Directory of Open Access Journals (Sweden)

Mehdi Dehghan

2006-01-01

Full Text Available In this paper, a numerical method is presented for finding the solution of some variational problems. The main objective is to find the solution of an ordinary differential equation which arises from the variational problem. This work is done using Adomian decomposition method which is a powerful tool for solving large amount of problems. In this approach, the solution is found in the form of a convergent power series with easily computed components. To show the efficiency of the method, numerical results are presented.

Solute-matrix and Solute-Solute Interactions during Supercritical Fluid Extraction of Sea Buckthorn Leaves

Czech Academy of Sciences Publication Activity Database

Sajfrtová, Marie; Sovová, Helena

2012-01-01

Roč. 42, SI (2012), s. 1682-1691 E-ISSN 1877-7058. [International Congress of Chemical and Process Engineering CHISA 2012 and 15th Conference PRES 2012 /20./. Prague, 25.08.2012-29.08.2012] R&D Projects: GA TA ČR TA01010578 Institutional support: RVO:67985858 Keywords : supercritical fluid extraction * sea buckthom leaves * solute-solute interaction Subject RIV: CI - Industrial Chemistry, Chemical Engineering

Thermal decomposition of the b.c.c. β-solid solution of titanium alloy containing 6.7 at% Mo, 3 at% Zr, and 1.8 at% Sn. 1

International Nuclear Information System (INIS)

Zakharova, M.I.; Khundzhua, A.K.; Kertesz, L.; Szasz, A.

1981-01-01

Changes in the crystal structure of the titanium alloy, containing 6.7 at% Mo, 3 at% Zr, and 1.8 at% Sn, during thermal decomposition are followed by means of X-ray and electron diffraction methods. Parallel to these tests the alteration in the electron structure and chemical bonds of the alloy are investigated with the help of the soft-x-ray emission (SXES) method. Attention is focussed on the at room temperature not equilibrated b.c.c. β-solid solution, on the metastable transition phase ω, and on the equilibrium phase α. (author)

Azimuthal decomposition of optical modes

CSIR Research Space (South Africa)

Dudley, Angela L

2012-07-01

Full Text Available This presentation analyses the azimuthal decomposition of optical modes. Decomposition of azimuthal modes need two steps, namely generation and decomposition. An azimuthally-varying phase (bounded by a ring-slit) placed in the spatial frequency...

Suppressing propylene carbonate decomposition by coating graphite electrode foil with silver

International Nuclear Information System (INIS)

Gao, J.; Zhang, H.P.; Fu, L.J.; Zhang, T.; Wu, Y.P.; Takamura, T.; Wu, H.Q.; Holze, R.

2007-01-01

A method has been developed to suppress the decomposition of propylene carbonate (PC) by coating graphite electrode foil with a layer of silver. Results from electrochemical impedance measurements show that the Ag-coated graphite electrode presents lower charge transfer resistance and faster diffusion of lithium ions in comparison with the virginal one. Cyclic voltammograms and discharge-charge measurements suggest that the decomposition of propylene carbonate and co-intercalation of solvated lithium ions are prevented, and lithium ions can reversibly intercalate into and deintercalate from the Ag-coated graphite electrode. These results indicate that Ag-coating is a good way to improve the electrochemical performance of graphitic carbon in PC-based electrolyte solutions

Sulfurized limonite as material for fast decomposition of organic compounds by heterogeneous Fenton reaction

International Nuclear Information System (INIS)

Toda, Kei; Tanaka, Toshinori; Tsuda, Yutaka; Ban, Masahiro; Koveke, Edwin P.; Koinuma, Michio; Ohira, Shin-Ichi

2014-01-01

Graphical abstract: - Highlights: • Used limonite degrades organic compounds by heterogeneous Fenton reaction. • Sulfurized limonite removes methylene blue color in seconds. • Recycled limonite can be used for biogas purification and wastewater treatment. - Abstract: Rapid decomposition of wastewater contaminants using sulfurized limonite (S-limonite) was investigated. Limonite is used for desulfurization of biogases, and S-limonite is obtained from desulfurization plants as solid waste. In this work, the profitable use of S-limonite in water treatment was examined. The divalent Fe in S-limonite was expected to produce OH radicals, as Fe 2+ ions and limonite thermally treated with H 2 do. Methylene blue was used for batch-wise monitoring of the decomposition performance. The decomposition rate was fast and the methylene blue solution color disappeared in only 10 s when a small amount of H 2 O 2 was added (1 mM in the sample solution) in the presence of S-limonite. The OH radicals were formed by a heterogeneous reaction on the S-limonite surface and Fenton reaction with dissolved Fe 2+ . The decomposition of pentachlorophenol was also examined; it was successfully decomposed in batch-wise tests. The surfaces of limonite before sulfurization, S-limonite, and S-limonite after use for water treatment were performed using scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that S-limonite reverted to limonite after being used for water treatment

Sulfurized limonite as material for fast decomposition of organic compounds by heterogeneous Fenton reaction

Energy Technology Data Exchange (ETDEWEB)

Toda, Kei, E-mail: todakei@sci.kumamoto-u.ac.jp [Department of Chemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Tanaka, Toshinori; Tsuda, Yutaka; Ban, Masahiro; Koveke, Edwin P. [Department of Chemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Koinuma, Michio [Department of Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Ohira, Shin-Ichi [Department of Chemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan)

2014-08-15

Graphical abstract: - Highlights: • Used limonite degrades organic compounds by heterogeneous Fenton reaction. • Sulfurized limonite removes methylene blue color in seconds. • Recycled limonite can be used for biogas purification and wastewater treatment. - Abstract: Rapid decomposition of wastewater contaminants using sulfurized limonite (S-limonite) was investigated. Limonite is used for desulfurization of biogases, and S-limonite is obtained from desulfurization plants as solid waste. In this work, the profitable use of S-limonite in water treatment was examined. The divalent Fe in S-limonite was expected to produce OH radicals, as Fe{sup 2+} ions and limonite thermally treated with H{sub 2} do. Methylene blue was used for batch-wise monitoring of the decomposition performance. The decomposition rate was fast and the methylene blue solution color disappeared in only 10 s when a small amount of H{sub 2}O{sub 2} was added (1 mM in the sample solution) in the presence of S-limonite. The OH radicals were formed by a heterogeneous reaction on the S-limonite surface and Fenton reaction with dissolved Fe{sup 2+}. The decomposition of pentachlorophenol was also examined; it was successfully decomposed in batch-wise tests. The surfaces of limonite before sulfurization, S-limonite, and S-limonite after use for water treatment were performed using scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that S-limonite reverted to limonite after being used for water treatment.

Chemical physics of decomposition of energetic materials. Problems and prospects

International Nuclear Information System (INIS)

Smirnov, Lev P

2004-01-01

The review is concerned with analysis of the results obtained in the kinetic and mechanistic studies on decomposition of energetic materials (explosives, powders and solid propellants). It is shown that the state-of-the art in this field is inadequate to the potential of modern chemical kinetics and chemical physics. Unsolved problems are outlined and ways of their solution are proposed.

Radiation chemistry and its application

International Nuclear Information System (INIS)

Majima, Tetsuro

2013-01-01

Effects of radiation to human body have been seriously discussed nowadays. These are important issues for the realization of sustainable society. It should be emphasized that various reactive intermediates generated by radiation play important roles in each cases. Radiation chemical studies will provide various reaction-mechanistic aspects on these important issues. Our research group has continuously carried out reaction-mechanistic studies using radiation chemical methods. From these studies, we have obtained a variety of results on basic molecular systems, reactions, materials that are close to practical application, biological systems and so on. Reactive species are generated from the radiation reactions in solution, and can be used as one-electron oxidative and reductive reagent to give selectively radical cation and anion of solute molecules such as various organic and inorganic molecules. Therefore, the radiation chemistry has contributed significantly to chemistry in which one-electron oxidation and reduction play the important role. The kinetics of such redox processes and the following reduction play the important role. The kinetics of such redox processes and the following reactions can be studied in real time with the transition absorption measurement by the pulse radiolysis technique. Even though the target compounds cannot be oxidized and reduced in chemical or electrochemical oxidation and reduction, their one-electron redox can be performed by the electron beam radiation. Therefore, radiation chemistry is very useful technique for basic science. Moreover, application potentials of radiation chemistry are so high for various research subjects. Moreover, application potentials of radiation chemistry are so high for various research subjects

Radiation-chemical degradation of chloroform in water solutions

International Nuclear Information System (INIS)

Ahmadov, S.A; Gurbanov, M.A; Iskenderova, Z.I; Abdullaev, E.T; Ibadov, N.A.

2006-01-01

Full text: Chloroform is the major chlorine-containing compound forming at chlorination of drinking water. As our basic water resources of Kur and Araz rivers are mostly polluted along the territory of the neighbor republics their chlorination for the purpose of biological purification can result in forming of chloroform. Unfortunately, there are only poor data about containing of chloroform in drinking water in the Republic, however the particular problem is to develop new methods of drinking water purification from chloroform, taking into account the high toxicity of this compounds. Appropriate works indicate that radiation-chemical processing can mostly reduce the concentration of chloroform in drinking water. The purification degree can achieve 95-98%. This work studies the tendency of chloroform decomposition at its radiolysis processes in percentage. Taking into account the dissolvability of chloroform in water solutions it can be said that examined water solutions are homogeneous. Following advancements are studied: b Determination of radiation-chemical yield of chloroform decomposition at its various initial concentrations;Impact of adsorbed dose on pH of solutions;Formation of by-products.It is set that radiation-chemical output of chloroform decomposition is equal to 3.10-3-125 mol 100ev.

Thermal decomposition of lutetium propionate

DEFF Research Database (Denmark)

Grivel, Jean-Claude

2010-01-01

The thermal decomposition of lutetium(III) propionate monohydrate (Lu(C2H5CO2)3·H2O) in argon was studied by means of thermogravimetry, differential thermal analysis, IR-spectroscopy and X-ray diffraction. Dehydration takes place around 90 °C. It is followed by the decomposition of the anhydrous...... °C. Full conversion to Lu2O3 is achieved at about 1000 °C. Whereas the temperatures and solid reaction products of the first two decomposition steps are similar to those previously reported for the thermal decomposition of lanthanum(III) propionate monohydrate, the final decomposition...... of the oxycarbonate to the rare-earth oxide proceeds in a different way, which is here reminiscent of the thermal decomposition path of Lu(C3H5O2)·2CO(NH2)2·2H2O...

Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

Science.gov (United States)

Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

2015-01-01

“Clumped-isotope” thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope “clumps”). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals.We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect.Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3− and CO32−. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many

Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

Science.gov (United States)

Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

2015-10-01

;Clumped-isotope; thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope ;clumps;). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals. We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect. Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3- and CO32-. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many natural systems. The two

The complex synthesis and solid state chemistry of ceria-lanthana solid solutions prepared via a hexamethylenetetramine precipitation

International Nuclear Information System (INIS)

Fleming, P.G.; Holmes, J.D.; Otway, D.J.; Morris, M.A.

2011-01-01

Mixed oxide solid solutions are becoming ever more commercially important across a range of applications. However, their synthesis can be problematical. Here, we show that ceria-lanthana solid solutions can be readily prepared via simple precipitation using hexamethylenetetramine. However, the solution chemistry can be complex, which results in the precipitated particles having a complex structure and morphology. Great care must be taken in both the synthesis and characterisation to quantify the complexity of the product. Even very high heat treatments were not able to produce highly homogeneous materials and X-ray diffractions reveals the non-equilibrium form of particles prepared in this way. Unexpected crystal structures are revealed including a new metastable cubic La 2 O 3 phase. - Graphical abstract: The suggested mechanism for the formation of dual fluorite phase particles, where Step 1 corresponds to room temperature aging, Step 2; heating the solution to 90 deg. C, Step 3; cooling of the solution to room temperature, Step 4; calcination to 500 deg. C, Step 5; calcination to 700 deg. C and Step 6; calcination to 1300 deg. C. The terminology of e.g. La 1-x Ce x (OH) 3 is used to indicate the formation of a mixed oxy-hydroxy participate rather than a definitive assignment of stoichiometry. Similarly, La 1-y Ce y O 2 only implies a mixed solid solution. Highlights: → Mol% of prepared Ce-La oxides did not follow that of reactant mol%. → Complex reaction pathway found to be dependent on metal solution concentrations. → At certain concentrations core shell particles were found to form. → A reaction model was produced based on cationic solubility. → Report lanthana solubility higher than previously reported in CeO 2 .

Rolling Element Bearing Performance Degradation Assessment Using Variational Mode Decomposition and Gath-Geva Clustering Time Series Segmentation

Directory of Open Access Journals (Sweden)

Yaolong Li

2017-01-01

Full Text Available By focusing on the issue of rolling element bearing (REB performance degradation assessment (PDA, a solution based on variational mode decomposition (VMD and Gath-Geva clustering time series segmentation (GGCTSS has been proposed. VMD is a new decomposition method. Since it is different from the recursive decomposition method, for example, empirical mode decomposition (EMD, local mean decomposition (LMD, and local characteristic-scale decomposition (LCD, VMD needs a priori parameters. In this paper, we will propose a method to optimize the parameters in VMD, namely, the number of decomposition modes and moderate bandwidth constraint, based on genetic algorithm. Executing VMD with the acquired parameters, the BLIMFs are obtained. By taking the envelope of the BLIMFs, the sensitive BLIMFs are selected. And then we take the amplitude of the defect frequency (ADF as a degradative feature. To get the performance degradation assessment, we are going to use the method called Gath-Geva clustering time series segmentation. Afterwards, the method is carried out by two pieces of run-to-failure data. The results indicate that the extracted feature could depict the process of degradation precisely.

The importance of biotic factors in predicting global change effects on decomposition of temperate forest leaf litter.

Science.gov (United States)

Rouifed, Soraya; Handa, I Tanya; David, Jean-François; Hättenschwiler, Stephan

2010-05-01

Increasing atmospheric CO(2) and temperature are predicted to alter litter decomposition via changes in litter chemistry and environmental conditions. The extent to which these predictions are influenced by biotic factors such as litter species composition or decomposer activity, and in particular how these different factors interact, is not well understood. In a 5-week laboratory experiment we compared the decomposition of leaf litter from four temperate tree species (Fagus sylvatica, Quercus petraea, Carpinus betulus and Tilia platyphyllos) in response to four interacting factors: elevated CO(2)-induced changes in litter quality, a 3 degrees C warmer environment during decomposition, changes in litter species composition, and presence/absence of a litter-feeding millipede (Glomeris marginata). Elevated CO(2) and temperature had much weaker effects on decomposition than litter species composition and the presence of Glomeris. Mass loss of elevated CO(2)-grown leaf litter was reduced in Fagus and increased in Fagus/Tilia mixtures, but was not affected in any other leaf litter treatment. Warming increased litter mass loss in Carpinus and Tilia, but not in the other two litter species and in none of the mixtures. The CO(2)- and temperature-related differences in decomposition disappeared completely when Glomeris was present. Overall, fauna activity stimulated litter mass loss, but to different degrees depending on litter species composition, with a particularly strong effect on Fagus/Tilia mixtures (+58%). Higher fauna-driven mass loss was not followed by higher C mineralization over the relatively short experimental period. Apart from a strong interaction between litter species composition and fauna, the tested factors had little or no interactive effects on decomposition. We conclude that if global change were to result in substantial shifts in plant community composition and macrofauna abundance in forest ecosystems, these interacting biotic factors could have

Hybrid subgroup decomposition method for solving fine-group eigenvalue transport problems

International Nuclear Information System (INIS)

Yasseri, Saam; Rahnema, Farzad

2014-01-01

Highlights: • An acceleration technique for solving fine-group eigenvalue transport problems. • Coarse-group quasi transport theory to solve coarse-group eigenvalue transport problems. • Consistent and inconsistent formulations for coarse-group quasi transport theory. • Computational efficiency amplified by a factor of 2 using hybrid SGD for 1D BWR problem. - Abstract: In this paper, a new hybrid method for solving fine-group eigenvalue transport problems is developed. This method extends the subgroup decomposition method to efficiently couple a new coarse-group quasi transport theory with a set of fixed-source transport decomposition sweeps to obtain the fine-group transport solution. The advantages of the quasi transport theory are its high accuracy, straight-forward implementation and numerical stability. The hybrid method is analyzed for a 1D benchmark problem characteristic of boiling water reactors (BWR). It is shown that the method reproduces the fine-group transport solution with high accuracy while increasing the computational efficiency up to 12 times compared to direct fine-group transport calculations

Chemistry of nepheline syenites interaction with calcium chloride at their joint baking

International Nuclear Information System (INIS)

Amirov, O.Kh.; Ruzieva, D.D.; Nazarov, Sh.B.; Safiev, Kh.; Mirsaidov, U.

2001-01-01

This work dedicated to determination of chemistry of leaking processes at nepheline syenites interaction with calcium chloride on baking stage. The main point of chemical conversion at baking of Turpe deposit nepheline with calcium chloride concluding in decomposition of acid insoluble raw materials minerals with formation of soluble in mineral acid minerals, that is take place the substitution ions of Na +, K +o f initial ore on Ca 2 + .

Power System Decomposition for Practical Implementation of Bulk-Grid Voltage Control Methods

Energy Technology Data Exchange (ETDEWEB)

Vallem, Mallikarjuna R.; Vyakaranam, Bharat GNVSR; Holzer, Jesse T.; Elizondo, Marcelo A.; Samaan, Nader A.

2017-10-19

Power system algorithms such as AC optimal power flow and coordinated volt/var control of the bulk power system are computationally intensive and become difficult to solve in operational time frames. The computational time required to run these algorithms increases exponentially as the size of the power system increases. The solution time for multiple subsystems is less than that for solving the entire system simultaneously, and the local nature of the voltage problem lends itself to such decomposition. This paper describes an algorithm that can be used to perform power system decomposition from the point of view of the voltage control problem. Our approach takes advantage of the dominant localized effect of voltage control and is based on clustering buses according to the electrical distances between them. One of the contributions of the paper is to use multidimensional scaling to compute n-dimensional Euclidean coordinates for each bus based on electrical distance to perform algorithms like K-means clustering. A simple coordinated reactive power control of photovoltaic inverters for voltage regulation is used to demonstrate the effectiveness of the proposed decomposition algorithm and its components. The proposed decomposition method is demonstrated on the IEEE 118-bus system.

Frequency filtering decompositions for unsymmetric matrices and matrices with strongly varying coefficients

Energy Technology Data Exchange (ETDEWEB)

Wagner, C.

1996-12-31

In 1992, Wittum introduced the frequency filtering decompositions (FFD), which yield a fast method for the iterative solution of large systems of linear equations. Based on this method, the tangential frequency filtering decompositions (TFFD) have been developed. The TFFD allow the robust and efficient treatment of matrices with strongly varying coefficients. The existence and the convergence of the TFFD can be shown for symmetric and positive definite matrices. For a large class of matrices, it is possible to prove that the convergence rate of the TFFD and of the FFD is independent of the number of unknowns. For both methods, schemes for the construction of frequency filtering decompositions for unsymmetric matrices have been developed. Since, in contrast to Wittums`s FFD, the TFFD needs only one test vector, an adaptive test vector can be used. The TFFD with respect to the adaptive test vector can be combined with other iterative methods, e.g. multi-grid methods, in order to improve the robustness of these methods. The frequency filtering decompositions have been successfully applied to the problem of the decontamination of a heterogeneous porous medium by flushing.

Decomposition of environmentally persistent perfluorooctanoic acid in water by photochemical approaches.

Science.gov (United States)

Hori, Hisao; Hayakawa, Etsuko; Einaga, Hisahiro; Kutsuna, Shuzo; Koike, Kazuhide; Ibusuki, Takashi; Kiatagawa, Hiroshi; Arakawa, Ryuichi

2004-11-15

The decomposition of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water by UV-visible light irradiation, by H202 with UV-visible light irradiation, and by a tungstic heteropolyacid photocatalyst was examined to develop a technique to counteract stationary sources of PFOA. Direct photolysis proceeded slowly to produce CO2, F-, and short-chain perfluorocarboxylic acids. Compared to the direct photolysis, H2O2 was less effective in PFOA decomposition. On the other hand, the heteropolyacid photocatalyst led to efficient PFOA decomposition and the production of F- ions and CO2. The photocatalyst also suppressed the accumulation of short-chain perfluorocarboxylic acids in the reaction solution. PFOA in the concentrations of 0.34-3.35 mM, typical of those in wastewaters after an emulsifying process in fluoropolymer manufacture, was completely decomposed by the catalyst within 24 h of irradiation from a 200-W xenon-mercury lamp, with no accompanying catalyst degradation, permitting the catalyst to be reused in consecutive runs. Gas chromatography/mass spectrometry (GC/MS) measurements showed no trace of environmentally undesirable species such as CF4, which has a very high global-warming potential. When the (initial PFOA)/(initial catalyst) molar ratio was 10: 1, the turnover number for PFOA decomposition reached 4.33 over 24 h of irradiation.

Differences in soil solution chemistry between soils amended with nanosized CuO or Cu reference materials: implications for nanotoxicity tests.

Science.gov (United States)

McShane, Heather V A; Sunahara, Geoffrey I; Whalen, Joann K; Hendershot, William H

2014-07-15

Soil toxicity tests for metal oxide nanoparticles often include micrometer-sized oxide and metal salt treatments to distinguish between toxicity from nanometer-sized particles, non-nanometer-sized particles, and dissolved ions. Test result will be confounded if each chemical form has different effects on soil solution chemistry. We report on changes in soil solution chemistry over 56 days-the duration of some standard soil toxicity tests-in three soils amended with 500 mg/kg Cu as nanometer-sized CuO (nano), micrometer-sized CuO (micrometer), or Cu(NO3)2 (salt). In the CuO-amended soils, the log Cu2+ activity was initially low (minimum -9.48) and increased with time (maximum -5.20), whereas in the salt-amended soils it was initially high (maximum -4.80) and decreased with time (minimum -6.10). The Cu2+ activity in the nano-amended soils was higher than in the micrometer-amended soils for at least the first 11 days, and lower than in the salt-amended soils for at least 28 d. The pH, and dissolved Ca and Mg concentrations in the CuO-amended soils were similar, but the salt-amended soils had lower pH for at least 14 d, and higher Ca and Mg concentrations throughout the test. Soil pretreatments such as leaching and aging prior to toxicity tests are suggested.

Accelerated decomposition techniques for large discounted Markov decision processes

Science.gov (United States)

Larach, Abdelhadi; Chafik, S.; Daoui, C.

2017-12-01

Many hierarchical techniques to solve large Markov decision processes (MDPs) are based on the partition of the state space into strongly connected components (SCCs) that can be classified into some levels. In each level, smaller problems named restricted MDPs are solved, and then these partial solutions are combined to obtain the global solution. In this paper, we first propose a novel algorithm, which is a variant of Tarjan's algorithm that simultaneously finds the SCCs and their belonging levels. Second, a new definition of the restricted MDPs is presented to ameliorate some hierarchical solutions in discounted MDPs using value iteration (VI) algorithm based on a list of state-action successors. Finally, a robotic motion-planning example and the experiment results are presented to illustrate the benefit of the proposed decomposition algorithms.

Domain decomposition methods for the neutron diffusion problem

International Nuclear Information System (INIS)

Guerin, P.; Baudron, A. M.; Lautard, J. J.

2010-01-01

The neutronic simulation of a nuclear reactor core is performed using the neutron transport equation, and leads to an eigenvalue problem in the steady-state case. Among the deterministic resolution methods, simplified transport (SPN) or diffusion approximations are often used. The MINOS solver developed at CEA Saclay uses a mixed dual finite element method for the resolution of these problems. and has shown his efficiency. In order to take into account the heterogeneities of the geometry, a very fine mesh is generally required, and leads to expensive calculations for industrial applications. In order to take advantage of parallel computers, and to reduce the computing time and the local memory requirement, we propose here two domain decomposition methods based on the MINOS solver. The first approach is a component mode synthesis method on overlapping sub-domains: several Eigenmodes solutions of a local problem on each sub-domain are taken as basis functions used for the resolution of the global problem on the whole domain. The second approach is an iterative method based on a non-overlapping domain decomposition with Robin interface conditions. At each iteration, we solve the problem on each sub-domain with the interface conditions given by the solutions on the adjacent sub-domains estimated at the previous iteration. Numerical results on parallel computers are presented for the diffusion model on realistic 2D and 3D cores. (authors)

Radiolysis of some aqueous solutions of neutron absorbers; Etude des effets de certains absorbeurs de neutrons en solution sur la radiolyse de l'eau

Energy Technology Data Exchange (ETDEWEB)

Rozenberg, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-12-15

The initial yield of molecular hydrogen formed by radiolytic decomposition of water in reactor and {sup 60}Co gamma radiation is decreased by the presence of salts of polyvalent elements possessing only one stable valence, i.e cadmium, zinc, magnesium, gadolinium. This effect is favourable for the use of cadmium and gadolinium as soluble neutron absorber in heavy water reactors. Cations of these salts are not inert toward the primary products of water radiolysis. They have a high degree of reactivity toward the hydrated electron, which is the precursor of molecular hydrogen in neutral or alkaline aqueous media. The value of the rate constant for the reaction between cadmium ion and hydrated electron was shown to be (6.1 {+-} 1.8) 10{sup 10} M{sup -1} s{sup -1}. Boric acid at low concentration has no effect on the radiation chemistry of water. An isotope effect has been found in the radiolysis of heavy water, corresponding to a lowering of initial yield [G{sub 0}(D{sub 2}) < G{sub 0}(H{sub 2})]. additionally it was necessary to determine the influence of organic impurities, remaining after the purification of water, on the mechanism of its radiolytic decomposition. (author) [French] Le rendement initial de la formation d'hydrogene moleculaire dans la decomposition radiolytique de l'eau, sous l'effet du rayonnement des reacteurs nucleaires ou du cobalt 60, est diminue si le solute est un sel d'element polyvalent ne possedant qu'un seul etat stable de valence (cadmium, zinc, magnesium, gadolinium). Cet effet est favorable au choix des elements cadmium et gadolinium pour servir d'absorbeur soluble de neutrons dans un reacteur a eau lourde. Les cations de ces sels ne sont pas inertes vis-a-vis des produits primaires de la radiolyse. Ils ont une affinite notable pour l'electron solvate, precurseur de l'hydrogene moleculaire en milieu neutre ou alcalin. En particulier, la constante de vitesse de la reaction du cadmium ionise avec l'electron solvate a pu etre calculee. Sa

Three-pattern decomposition of global atmospheric circulation: part I—decomposition model and theorems

Science.gov (United States)

Hu, Shujuan; Chou, Jifan; Cheng, Jianbo

2018-04-01

In order to study the interactions between the atmospheric circulations at the middle-high and low latitudes from the global perspective, the authors proposed the mathematical definition of three-pattern circulations, i.e., horizontal, meridional and zonal circulations with which the actual atmospheric circulation is expanded. This novel decomposition method is proved to accurately describe the actual atmospheric circulation dynamics. The authors used the NCEP/NCAR reanalysis data to calculate the climate characteristics of those three-pattern circulations, and found that the decomposition model agreed with the observed results. Further dynamical analysis indicates that the decomposition model is more accurate to capture the major features of global three dimensional atmospheric motions, compared to the traditional definitions of Rossby wave, Hadley circulation and Walker circulation. The decomposition model for the first time realized the decomposition of global atmospheric circulation using three orthogonal circulations within the horizontal, meridional and zonal planes, offering new opportunities to study the large-scale interactions between the middle-high latitudes and low latitudes circulations.

A comparison of amorphous calcium carbonate crystallization in aqueous solutions of MgCl2 and MgSO4: implications for paleo-ocean chemistry

Science.gov (United States)

Han, Mei; Zhao, Yanyang; Zhao, Hui; Han, Zuozhen; Yan, Huaxiao; Sun, Bin; Meng, Ruirui; Zhuang, Dingxiang; Li, Dan; Liu, Binwei

2018-04-01

Based on the terminology of "aragonite seas" and "calcite seas", whether different Mg sources could affect the mineralogy of carbonate sediments at the same Mg/Ca ratio was explored, which was expected to provide a qualitative assessment of the chemistry of the paleo-ocean. In this work, amorphous calcium carbonate (ACC) was prepared by direct precipitation in anhydrous ethanol and used as a precursor to study crystallization processes in MgSO4 and MgCl2 solutions having different concentrations at 60 °C (reaction times 240 and 2880 min). Based on the morphology of the aragonite crystals, as well as mineral saturation indices and kinetic analysis of geochemical processes, it was found that these crystals formed with a spherulitic texture in 4 steps. First, ACC crystallized into columnar Mg calcite by nearly oriented attachment. Second, the Mg calcite changed from columnar shapes into smooth dumbbell forms. Third, the Mg calcite transformed into rough dumbbell or cauliflower-shaped aragonite forms by local dissolution and precipitation. Finally, the aragonite transformed further into spherulitic radial and irregular aggregate forms. The increase in Ca2+ in the MgSO4 solutions compared with the MgCl2 solutions indicates the fast dissolution and slow precipitation of ACC in the former solutions. The phase transition was more complete in the 0.005 M MgCl2 solution, whereas Mg calcite crystallized from the 0.005 M MgSO4 solution, indicating that Mg calcite could be formed more easily in an MgSO4 solution. Based on these findings, aragonite and Mg calcite relative to ACC could be used to provide a qualitative assessment of the chemistry of the paleo-ocean. Therefore, calcite seas relative to high-Mg calcite could reflect a low concentration MgSO4 paleo-ocean, while aragonite seas could be related to an MgCl2 or high concentration of MgSO4 paleo-ocean.

Exact Solutions of the Harry-Dym Equation

International Nuclear Information System (INIS)

Mokhtari, Reza

2011-01-01

The aim of this paper is to generate exact travelling wave solutions of the Harry-Dym equation through the methods of Adomian decomposition, He's variational iteration, direct integration, and power series. We show that the two later methods are more successful than the two former to obtain more solutions of the equation. (general)

Non-uniform Solute Segregation at Semi-Coherent Metal/Oxide Interfaces

Science.gov (United States)

Choudhury, Samrat; Aguiar, Jeffery A.; Fluss, Michael J.; Hsiung, Luke L.; Misra, Amit; Uberuaga, Blas P.

2015-08-01

The properties and performance of metal/oxide nanocomposites are governed by the structure and chemistry of the metal/oxide interfaces. Here we report an integrated theoretical and experimental study examining the role of interfacial structure, particularly misfit dislocations, on solute segregation at a metal/oxide interface. We find that the local oxygen environment, which varies significantly between the misfit dislocations and the coherent terraces, dictates the segregation tendency of solutes to the interface. Depending on the nature of the solute and local oxygen content, segregation to misfit dislocations can change from attraction to repulsion, revealing the complex interplay between chemistry and structure at metal/oxide interfaces. These findings indicate that the solute chemistry at misfit dislocations is controlled by the dislocation density and oxygen content. Fundamental thermodynamic concepts - the Hume-Rothery rules and the Ellingham diagram - qualitatively predict the segregation behavior of solutes to such interfaces, providing design rules for novel interfacial chemistries.

Cell-wall polysaccharides play an important role in decay resistance of Sphagnum and actively depressed decomposition in vitro

OpenAIRE

Hajek, T.; Ballance, S.; Limpens, J.; Verhoeven, J.T.A.; Zijlstra, M.J.

2011-01-01

Sphagnum-dominated peatlands head the list of ecosystems with the largest known reservoirs of organic carbon (C). The bulk of this C is stored in decomposition-resistant litter of one bryophyte genus: Sphagnum. Understanding how Sphagnum litter chemistry controls C mineralization is essential for understanding potential interactions between environmental changes and C mineralization in peatlands. We aimed to separate the effects of phenolics from structural polysaccharides on decay of Sphagnu...

Global sensitivity analysis by polynomial dimensional decomposition

Energy Technology Data Exchange (ETDEWEB)

Rahman, Sharif, E-mail: rahman@engineering.uiowa.ed [College of Engineering, The University of Iowa, Iowa City, IA 52242 (United States)

2011-07-15

This paper presents a polynomial dimensional decomposition (PDD) method for global sensitivity analysis of stochastic systems subject to independent random input following arbitrary probability distributions. The method involves Fourier-polynomial expansions of lower-variate component functions of a stochastic response by measure-consistent orthonormal polynomial bases, analytical formulae for calculating the global sensitivity indices in terms of the expansion coefficients, and dimension-reduction integration for estimating the expansion coefficients. Due to identical dimensional structures of PDD and analysis-of-variance decomposition, the proposed method facilitates simple and direct calculation of the global sensitivity indices. Numerical results of the global sensitivity indices computed for smooth systems reveal significantly higher convergence rates of the PDD approximation than those from existing methods, including polynomial chaos expansion, random balance design, state-dependent parameter, improved Sobol's method, and sampling-based methods. However, for non-smooth functions, the convergence properties of the PDD solution deteriorate to a great extent, warranting further improvements. The computational complexity of the PDD method is polynomial, as opposed to exponential, thereby alleviating the curse of dimensionality to some extent.

A review of the radiation chemistry of iodine compounds in aqueous solution

International Nuclear Information System (INIS)

Sellers, R.M.

1977-06-01

Large amounts of radioactive iodine are formed in the fission of uranium in nuclear reactors. Some of this may be released to the coolant from the fuel either by diffusion through the canning material, or following the failure of a fuel pin. The iodine, which is released mainly as I 2 and methyl iodide, is transported with the coolant and, in direct cycle water cooled reactors, some is carried over with the steam to the turbines, where contamination may build up in the vicinity of steam leaks. Any assessment of the mechanism of the transport of iodine requires a knowledge of the relative amounts of the various oxidation states present, and must consider not only the thermal behaviour of iodine in water, but also the radiation chemical effects. A review is presented of the radiation chemistry of inorganic iodine compounds and methyl iodide in aqueous solutions. A number of unstable intermediates have been identified including species with iodide in valency states II, IV, VI and VIII. A considerable number of discrepancies exist in the literature data, and requirements for further work are identified. (author)

Atmospheric chemistry of HFC-134a. Kinetic and mechanistic study of the CF3CFHO2 + NO2 reaction

DEFF Research Database (Denmark)

Møgelberg, T.E.; Nielsen, O.J.; Sehested, J.

1994-01-01

A pulse radiolysis system was used to study the kinetics of the reaction of CF3CFHO2 with NO2. By monitoring the rate of the decay of NO2 using its absorption at 400 nm the reaction rate constant was determined to be k = (5.0 +/- 0.5) x 10(-12) cm3 molecule-1 s-1. A long path length Fourier......-transform infrared technique was used to investigate the thermal decomposition of the product CF3CFHO2NO2. At 296 K in the presence of 700 Torr of air, decomposition of CF3CFHO2NO2 was rapid (greater than 90% decomposition within 3 min). The results are discussed in the context of atmospheric chemistry of CF3CFH2...

Potential alteration of precipitation chemistry by epiphytic lichens

Energy Technology Data Exchange (ETDEWEB)

Lang, G E; Reiners, W A; Heier, R K

1976-01-01

Epiphytic lichen growth is abundant on the boles and branches of balsam fir trees at high elevations in New Hampshire. These lichens absorb elements needed for growth from solutions flowing over their surfaces and from direct impaction of water droplets. This study describes how epiphytic lichens and fir needles altered the chemistry of simulated rain water solutions under laboratory conditions. Experiments showed: 1) lichens absorbed ammonium and nitrate from solution; the rate of uptake increased with increasing temperature of the solution, 2) lichens lost calcium, magnesium, and hydrogen to the solution, 3) lichen thalli also initially lost potassium, but in time, net movement was reversed back into the thallus, 4) cation movement increased with increasing temperature, and 5) fir needles responded in a manner similar to that of the lichens, but the amount of change was much less. From these results it seems that epiphytic lichens have potential ecological importance in altering the chemistry of throughfall and stemflow.

Radiation induced decomposition of chlorinated phenols in water

International Nuclear Information System (INIS)

Getoff, N.; Solar, S.

1988-01-01

Experiments with 4-Cl-phenol as a model compound for pesticides were performed under steady-state conditions using deoxygenated solutions as well as solutions saturated with air, oxygen or oxygen mixed with ozone. The yield of Cl - ions served as an indicator for the degradation process. As main products of the first step of decomposition were identified: polyhydroxybenzenes, aldehydes and acids. The yield of aldehydes was studied as a function of the absorbed dose and substrate concentration. In the presence of ozone a chain-reaction of the oxidative pollutant degradation takes place. Transient absorption spectra and kinetics obtained by preliminary pulse radiolysis studies of 4-Cl-phenol in the presence of oxygen as well as probable reaction mechanisms are also presented. (author)

The response of soil solution chemistry in European forests to decreasing acid deposition.

Science.gov (United States)

Johnson, James; Graf Pannatier, Elisabeth; Carnicelli, Stefano; Cecchini, Guia; Clarke, Nicholas; Cools, Nathalie; Hansen, Karin; Meesenburg, Henning; Nieminen, Tiina M; Pihl-Karlsson, Gunilla; Titeux, Hugues; Vanguelova, Elena; Verstraeten, Arne; Vesterdal, Lars; Waldner, Peter; Jonard, Mathieu

2018-03-31

Acid deposition arising from sulphur (S) and nitrogen (N) emissions from fossil fuel combustion and agriculture has contributed to the acidification of terrestrial ecosystems in many regions globally. However, in Europe and North America, S deposition has greatly decreased in recent decades due to emissions controls. In this study, we assessed the response of soil solution chemistry in mineral horizons of European forests to these changes. Trends in pH, acid neutralizing capacity (ANC), major ions, total aluminium (Al tot ) and dissolved organic carbon were determined for the period 1995-2012. Plots with at least 10 years of observations from the ICP Forests monitoring network were used. Trends were assessed for the upper mineral soil (10-20 cm, 104 plots) and subsoil (40-80 cm, 162 plots). There was a large decrease in the concentration of sulphate (SO42-) in soil solution; over a 10-year period (2000-2010), SO42- decreased by 52% at 10-20 cm and 40% at 40-80 cm. Nitrate was unchanged at 10-20 cm but decreased at 40-80 cm. The decrease in acid anions was accompanied by a large and significant decrease in the concentration of the nutrient base cations: calcium, magnesium and potassium (Bc = Ca 2+  + Mg 2+  + K + ) and Al tot over the entire dataset. The response of soil solution acidity was nonuniform. At 10-20 cm, ANC increased in acid-sensitive soils (base saturation ≤10%) indicating a recovery, but ANC decreased in soils with base saturation >10%. At 40-80 cm, ANC remained unchanged in acid-sensitive soils (base saturation ≤20%, pHCaCl2 ≤ 4.5) and decreased in better-buffered soils (base saturation >20%, pHCaCl2 > 4.5). In addition, the molar ratio of Bc to Al tot either did not change or decreased. The results suggest a long-time lag between emission abatement and changes in soil solution acidity and underline the importance of long-term monitoring in evaluating ecosystem response to decreases in deposition. © 2018 John Wiley & Sons

A Wet Chemistry Laboratory Cell

Science.gov (United States)

2008-01-01

This picture of NASA's Phoenix Mars Lander's Wet Chemistry Laboratory (WCL) cell is labeled with components responsible for mixing Martian soil with water from Earth, adding chemicals and measuring the solution chemistry. WCL is part of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument suite on board the Phoenix lander. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

Theoretical chemistry advances and perspectives

CERN Document Server

Eyring, Henry

1980-01-01

Theoretical Chemistry: Advances and Perspectives, Volume 5 covers articles concerning all aspects of theoretical chemistry. The book discusses the mean spherical approximation for simple electrolyte solutions; the representation of lattice sums as Mellin-transformed products of theta functions; and the evaluation of two-dimensional lattice sums by number theoretic means. The text also describes an application of contour integration; a lattice model of quantum fluid; as well as the computational aspects of chemical equilibrium in complex systems. Chemists and physicists will find the book usef

Studies on effective decomposition of monazite minerals by variety of phosphate fluxes for simple and direct determination of uranium by LED fluorimeter

International Nuclear Information System (INIS)

Gopal, Leela; Hanuman, V.V.; Chakrapani, G.

2013-01-01

A simple, rapid, effective sample decomposition method is developed for the determination of uranium (U) in monazite minerals by fluorimetric (Light Emitting Diodes (LED) based) technique. The salts of sodium dihydrogen phosphate (NaH 2 PO 4 ), disodium hydrogen phosphate (Na 2 HPO 4 ) and tetrasodium pyrophosphate (Na 4 P 2 O 7 ) were used to conduct studies on effective decomposition and dissolution of monazite minerals. The flux short listed for sample decomposition has several advantages. The fusion is very simple (involve minimal skills), time saving and eco-friendly (no acids were used for sample dissolution), where as in the reported conventional sample decomposition methods involving fusion with sodium peroxide, mixture of KHF 2 and NaF, mineral acids are being used for sample decomposition to get clear solution. Further this solution cannot be used directly for uranium determination by LED fluorimetry; hence separation is required, resulting in low sample throughput. In the present method no such separation is required as the flux itself acts as a fluorescence enhancing reagent and buffer (maintaining the optimum pH of 7.1 ± 0.1). The fused melt of the flux mixture when dissolved in water, gives clear and stable solution. The accuracy and precision of the method was evaluated by analyzing Certified Reference Material, IGS-36 (Institute of Geological Sciences, UK) and monazite samples received from BSOI, Trivandrum. The accuracy of the data was further evaluated by comparing with conventional standard decomposition methods. The results are well within experimental error. RSD of the method is ±2% at 0.30% U 3 O 8 in monazite minerals. (author)

Self-Attractive Hartree Decomposition: Partitioning Electron Density into Smooth Localized Fragments.

Science.gov (United States)

Zhu, Tianyu; de Silva, Piotr; Van Voorhis, Troy

2018-01-09

Chemical bonding plays a central role in the description and understanding of chemistry. Many methods have been proposed to extract information about bonding from quantum chemical calculations, the majority of them resorting to molecular orbitals as basic descriptors. Here, we present a method called self-attractive Hartree (SAH) decomposition to unravel pairs of electrons directly from the electron density, which unlike molecular orbitals is a well-defined observable that can be accessed experimentally. The key idea is to partition the density into a sum of one-electron fragments that simultaneously maximize the self-repulsion and maintain regular shapes. This leads to a set of rather unusual equations in which every electron experiences self-attractive Hartree potential in addition to an external potential common for all the electrons. The resulting symmetry breaking and localization are surprisingly consistent with chemical intuition. SAH decomposition is also shown to be effective in visualization of single/multiple bonds, lone pairs, and unusual bonds due to the smooth nature of fragment densities. Furthermore, we demonstrate that it can be used to identify specific chemical bonds in molecular complexes and provides a simple and accurate electrostatic model of hydrogen bonding.

Radiation-chemical degradation of chloroform in water solutions

International Nuclear Information System (INIS)

Ahmadov, S.A.; Gurbanov, M.A.; Iskenderova, Z.I.; Abdullayev, E.T.; Ibadov, N.A.

2006-01-01

Full text: Chloroform is the major chlorine-containing compound forming at chlorination of drinking water. As our basic water resources of Kur and Araz rivers are mostly polluted along the territory of the neighbour republics their chlorination for the purpose of biological purification can result in forming of chloroform. Unfortunately, there are only poor data about containing of chloroform in drinking water in the Republic, however the particular problem is to develop new methods of drinking water purification from chloroform, taking into account the high toxicity of this compounds. Appropriate works indicate that radiation-chemical processing can mostly reduce the concentration of chloroform in drinking water. The purification degree can achieve 95-98 percent. This work studies the tendency of chloroform decomposition at its radiolysis processes in water solutions. The concentration of chloroform changed in the range of 0,03-1 weight percentage. Taking into account the dissolvability of chloroform in water solutions it can be said that examined water solutions are homogeneous. Following advancements are studied: 1) Determination of radiation-chemical yield of chloroform decomposition at its various initial concentrations; 2) Impact of adsorbed dose on pH of solutions; 3) Formation of by-products. It is set that radiation-chemical output of chloroform decomposition is equal to 3 * 10 - 3 - 125 mol/100 ev. The high yield of chloroform decomposition can be connected with the chain process of oxidation with presence of dissolved oxygen. However, taking into account the fact that at its water radiolysis the yield of active particles of OH, e - aq, H-atoms does not exceed 6-7 particles/100 ev, the observed high yield can be explained only with the chain process with presence of dissolved oxygen

Module theory endomorphism rings and direct sum decompositions in some classes of modules

CERN Document Server

Facchini, Alberto

1998-01-01

The purpose of this expository monograph is three-fold. First, the solution of a problem posed by Wolfgang Krull in 1932 is presented. He asked whether what is now called the "Krull-Schmidt Theorem" holds for artinian modules. A negative answer was published only in 1995 by Facchini, Herbera, Levy and Vámos. Second, the answer to a question posed by Warfield in 1975, namely, whether the Krull-Schmidt-Theorem holds for serial modules, is described. Facchini published a negative answer in 1996. The solution to the Warfield problem shows an interesting behavior; in fact, it is a phenomena so rare in the history of Krull-Schmidt type theorems that its presentation to a wider mathematical audience provides the third incentive for this monograph. Briefly, the Krull-Schmidt-Theorem holds for some, not all, classes of modules. When it does hold, any two indecomposable decompositions are uniquely determined up to one permutation. For serial modules the theorem does not hold, but any two indecomposable decompositions ...

Simulation of N(2)O Abatement in Waste Gases by Its Decomposition over a K-Promoted Co-Mn-Al Mixed Oxide Catalyst

Czech Academy of Sciences Publication Activity Database

Obalová, L.; Jirátová, Květa; Karásková, K.; Kovanda, F.

2011-01-01

Roč. 32, 5/SI/ (2011), s. 816-820 ISSN 0253-9837. [6th International Conference on Environmental Catalysis (6th ICEC). Beijing, 12.09.2010-15.09.2010] Institutional research plan: CEZ:AV0Z40720504 Keywords : nitrous oxide * catalytic decomposition * nitric acid production Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.171, year: 2011

Global decomposition experiment shows soil animal impacts on decomposition are climate-dependent

Czech Academy of Sciences Publication Activity Database

Wall, D.H.; Bradford, M.A.; John, M.G.St.; Trofymow, J.A.; Behan-Pelletier, V.; Bignell, D.E.; Dangerfield, J.M.; Parton, W.J.; Rusek, Josef; Voigt, W.; Wolters, V.; Gardel, H.Z.; Ayuke, F. O.; Bashford, R.; Beljakova, O.I.; Bohlen, P.J.; Brauman, A.; Flemming, S.; Henschel, J.R.; Johnson, D.L.; Jones, T.H.; Kovářová, Marcela; Kranabetter, J.M.; Kutny, L.; Lin, K.-Ch.; Maryati, M.; Masse, D.; Pokarzhevskii, A.; Rahman, H.; Sabará, M.G.; Salamon, J.-A.; Swift, M.J.; Varela, A.; Vasconcelos, H.L.; White, D.; Zou, X.

2008-01-01

Roč. 14, č. 11 (2008), s. 2661-2677 ISSN 1354-1013 Institutional research plan: CEZ:AV0Z60660521; CEZ:AV0Z60050516 Keywords : climate decomposition index * decomposition * litter Subject RIV: EH - Ecology, Behaviour Impact factor: 5.876, year: 2008

Fuel Chemistry Division: progress report for 1985

International Nuclear Information System (INIS)

1988-01-01

Fuel Chemistry Division was formed in May 1985 to give a larger emphasis on the research and development in chemistry of the nuclear fuel cycle. The areas of research in Fuel Chemistry Division are fuel development and its chemical quality control, understanding of the fuel behaviour and post irradiation examinations, chemistry of reprocessing and waste management processes as also the basic aspects of actinide and relevant fission product elements. This report summarises the work by the staff of the Division during 1985 and also some work from the previous periods which was not reported in the progress reports of the Radiochemistry Division. The work related to the FBTR fuel was one of the highlights during this period. In the area of process chemistry useful work has been carried out for processing of plutonium bearing solutions. In the area of mass spectrometry, the determination of trace constituents by spark source mass spectrometry has been a major area of research. Significant progress has also been made in the use of alpha spectromet ry techniques for the determination of plutonium in dissolver solution and other samples. The technology of plutonium utilisation is quite complex and the Division would continue to look into the chemical aspects of this technology and provide the necessary base for future developments in this area. (author)

Decomposition methods for unsupervised learning

DEFF Research Database (Denmark)

Mørup, Morten

2008-01-01

This thesis presents the application and development of decomposition methods for Unsupervised Learning. It covers topics from classical factor analysis based decomposition and its variants such as Independent Component Analysis, Non-negative Matrix Factorization and Sparse Coding...... methods and clustering problems is derived both in terms of classical point clustering but also in terms of community detection in complex networks. A guiding principle throughout this thesis is the principle of parsimony. Hence, the goal of Unsupervised Learning is here posed as striving for simplicity...... in the decompositions. Thus, it is demonstrated how a wide range of decomposition methods explicitly or implicitly strive to attain this goal. Applications of the derived decompositions are given ranging from multi-media analysis of image and sound data, analysis of biomedical data such as electroencephalography...

Effect of FeH-zeolite structure and Al-Lewis sites on N2O decomposition and NO/NO2-assisted reaction

Czech Academy of Sciences Publication Activity Database

Kaucký, Dalibor; Sobalík, Zdeněk; Schwarze, Michael; Vondrová, Alena; Wichterlová, Blanka

2006-01-01

Roč. 238, č. 2 (2006), s. 293-300 ISSN 0021-9517 R&D Projects: GA ČR GP104/02/D124; GA AV ČR 1ET400400413 Institutional research plan: CEZ:AV0Z40400503 Keywords : N2O decomposition * NO/NO2 assistance * Fe-zeolites * Fe-ferrierite Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.533, year: 2006

Dictionary-Based Tensor Canonical Polyadic Decomposition

Science.gov (United States)

Cohen, Jeremy Emile; Gillis, Nicolas

2018-04-01

To ensure interpretability of extracted sources in tensor decomposition, we introduce in this paper a dictionary-based tensor canonical polyadic decomposition which enforces one factor to belong exactly to a known dictionary. A new formulation of sparse coding is proposed which enables high dimensional tensors dictionary-based canonical polyadic decomposition. The benefits of using a dictionary in tensor decomposition models are explored both in terms of parameter identifiability and estimation accuracy. Performances of the proposed algorithms are evaluated on the decomposition of simulated data and the unmixing of hyperspectral images.

Chemistry of Small Organic Molecules on Snow Grains: The Applicability of Artificial Snow for Environmental Studies

Czech Academy of Sciences Publication Activity Database

Kurková, R.; Ray, D.; Nachtigallová, Dana; Klán, P.

2011-01-01

Roč. 45, č. 8 (2011), s. 3430-3436 ISSN 0013-936X R&D Projects: GA MŠk LC512 Grant - others:GA ČR(CZ) GAP503/10/0947 Institutional research plan: CEZ:AV0Z40550506 Keywords : water-ice * photochemical decomposition * dibenzyl- ketones Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.228, year: 2011

A general method for the inclusion of radiation chemistry in astrochemical models.

Science.gov (United States)

Shingledecker, Christopher N; Herbst, Eric

2018-02-21

In this paper, we propose a general formalism that allows for the estimation of radiolysis decomposition pathways and rate coefficients suitable for use in astrochemical models, with a focus on solid phase chemistry. Such a theory can help increase the connection between laboratory astrophysics experiments and astrochemical models by providing a means for modelers to incorporate radiation chemistry into chemical networks. The general method proposed here is targeted particularly at the majority of species now included in chemical networks for which little radiochemical data exist; however, the method can also be used as a starting point for considering better studied species. We here apply our theory to the irradiation of H 2 O ice and compare the results with previous experimental data.

Mass and spin of double dual solutions in Poincare gauge theory

International Nuclear Information System (INIS)

Mielke, E.W.; Wallner, R.P.

1988-01-01

Mass and spin are derived for a class of exact solutions of the Poincare gauge (PG) theory of gravity, provided the curvature fulfills a modified double-duality ansatz. It is executed a (3+1)-decomposition and clarified and semplified the structure of the energy-momentum and spin complexes. In case the quadratic PG Lagrangian contains the curvature-square pieces in the Yang-Mills fashion, the (3+1)-decomposition provides rather detailed information on admissible solutions. The PG energy-momentum complex turns out to be intimately related to the von Freud complex of general relativity

Cellular decomposition in vikalloys

International Nuclear Information System (INIS)

Belyatskaya, I.S.; Vintajkin, E.Z.; Georgieva, I.Ya.; Golikov, V.A.; Udovenko, V.A.

1981-01-01

Austenite decomposition in Fe-Co-V and Fe-Co-V-Ni alloys at 475-600 deg C is investigated. The cellular decomposition in ternary alloys results in the formation of bcc (ordered) and fcc structures, and in quaternary alloys - bcc (ordered) and 12R structures. The cellular 12R structure results from the emergence of stacking faults in the fcc lattice with irregular spacing in four layers. The cellular decomposition results in a high-dispersion structure and magnetic properties approaching the level of well-known vikalloys [ru

Automated quantum chemistry based molecular dynamics simulations of electron ionization induced fragmentations of the nucleobases Uracil, Thymine, Cytosine, and Guanine.

Science.gov (United States)

Grimme, Stefan; Bauer, Christopher Alexander

2015-01-01

The gas-phase decomposition pathways of electron ionization (EI)-induced radical cations of the nucleobases uracil, thymine, cytosine, and guanine are investigated by means of mixed quantum-classical molecular dynamics. No preconceived fragmentation channels are used in the calculations. The results compare well to a plethora of experimental and theoretical data for these important biomolecules. With our combined stochastic and dynamic approach, one can access in an unbiased way the energetically available decomposition mechanisms. Additionally, we are able to separate the EI mass spectra of different tautomers of cytosine and guanine. Our method (previously termed quantum chemistry electron ionization mass spectra) reproduces free nucleobase experimental mass spectra well and provides detailed mechanistic in-sight into high-energy unimolecular decomposition processes.

Size dependent reactivity of metal nanoparticles and alloys supported on HOPG, probed by the H-D exchange and the NH3 decomposition reactions

DEFF Research Database (Denmark)

Fiordaliso, Elisabetta Maria

this investigation have been summarized in a scientific article which has been submitted to the Journal of Physical Chemistry. The second reaction investigated in this thesis is the NH3 decomposition reaction, relevant for hydrogen storage and production in a COx free environment, which has been performed on Ru, Ir......, Rh and Pt thin films, on Ru nanoparticles and on Ir/Ru alloys. Preliminary results indicated that Ru is the most active among the selected metals, but no definitive conclusions can be drawn on the effect of the particle diameter on the decomposition rate. In the case of the Ru/Ir alloys, it is found...

Nitrogen deposition does not enhance Sphagnum decomposition.

Science.gov (United States)

Manninen, S; Kivimäki, S; Leith, I D; Leeson, S R; Sheppard, L J

2016-11-15

Long-term additions of nitrogen (N) to peatlands have altered bryophyte growth, species dominance, N content in peat and peat water, and often resulted in enhanced Sphagnum decomposition rate. However, these results have mainly been derived from experiments in which N was applied as ammonium nitrate (NH4NO3), neglecting the fact that in polluted areas, wet deposition may be dominated either by NO3(-) or NH4(+). We studied effects of elevated wet deposition of NO3(-) vs. NH4(+) alone (8 or 56kgNha(-1)yr(-1) over and above the background of 8kgNha(-1)yr(-1) for 5 to 11years) or combined with phosphorus (P) and potassium (K) on Sphagnum quality for decomposers, mass loss, and associated changes in hummock pore water in an ombrotrophic bog (Whim). Adding N, especially as NH4(+), increased N concentration in Sphagnum, but did not enhance mass loss from Sphagnum. Mass loss seemed to depend mainly on moss species and climatic factors. Only high applications of N affected hummock pore water chemistry, which varied considerably over time. Overall, C and N cycling in this N treated bog appeared to be decoupled. We conclude that moss species, seasonal and annual variation in climatic factors, direct negative effects of N (NH4(+) toxicity) on Sphagnum production, and indirect effects (increase in pH and changes in plant species dominance under elevated NO3(-) alone and with PK) drive Sphagnum decomposition and hummock C and N dynamics at Whim. Copyright © 2016 Elsevier B.V. All rights reserved.

Role of Reactive Mn Complexes in a Litter Decomposition Model System

Science.gov (United States)

Nico, P. S.; Keiluweit, M.; Bougoure, J.; Kleber, M.; Summering, J. A.; Maynard, J. J.; Johnson, M.; Pett-Ridge, J.

2012-12-01

The search for controls on litter decomposition rates and pathways has yet to return definitive characteristics that are both statistically robust and can be understood as part of a mechanistic or numerical model. Herein we focus on Mn, an element present in all litter that is likely an active chemical agent of decomposition. Berg and co-workers (2010) found a strong correlation between Mn concentration in litter and the magnitude of litter degradation in boreal forests, suggesting that litter decomposition proceeds more efficiently in the presence of Mn. Although there is much circumstantial evidence for the potential role of Mn in lignin decomposition, few reports exist on mechanistic details of this process. For the current work, we are guided by the hypothesis that the dependence of decomposition on Mn is due to Mn (III)-oxalate complexes act as a 'pretreatment' for structurally intact ligno-carbohydrate complexes (LCC) in fresh plant cell walls (e.g. in litter, root and wood). Manganese (III)-ligand complexes such as Mn (III)-oxalate are known to be potent oxidizers of many different organic and inorganic compounds. In the litter system, the unique property of these complexes may be that they are much smaller than exo-enzymes and therefore more easily able to penetrate LCC complexes in plant cell walls. By acting as 'diffusible oxidizers' and reacting with the organic matrix of the cell wall, these compounds can increase the porosity of fresh litter thereby facilitating access of more specific lignin- and cellulose decomposing enzymes. This possibility was investigated by reacting cell walls of single Zinnia elegans tracheary elements with Mn (III)-oxalate complexes in a continuous flow reactor. The uniformity of these individual plant cells allowed us to examine Mn (III)-induced changes in cell wall chemistry and ultrastructure on the micro-scale using fluorescence and electron microscopy as well as IR and X-ray spectromicroscopy. This presentation will

ATC calculation with steady-state security constraints using Benders decomposition

International Nuclear Information System (INIS)

Shaaban, M.; Yan, Z.; Ni, Y.; Wu, F.; Li, W.; Liu, H.

2003-01-01

Available transfer capability (ATC) is an important indicator of the usable amount of transmission capacity accessible by assorted parties for commercial trading, ATC calculation is nontrivial when steady-state security constraints are included. In hie paper, Benders decomposition method is proposed to partition the AC problem with steady-state security constraints into a base case master problem and a series of subproblems relevant to various contingencies to include their impacts on ATC. The mathematical model is formulated and the two solution schemes are presented. Computer testing on the 4-bus system and IEEE 30-bus system shows the effectiveness of the proposed method and the solution schemes. (Author)

Regularized generalized eigen-decomposition with applications to sparse supervised feature extraction and sparse discriminant analysis

DEFF Research Database (Denmark)

Han, Xixuan; Clemmensen, Line Katrine Harder

2015-01-01

We propose a general technique for obtaining sparse solutions to generalized eigenvalue problems, and call it Regularized Generalized Eigen-Decomposition (RGED). For decades, Fisher's discriminant criterion has been applied in supervised feature extraction and discriminant analysis, and it is for...

Nitrogen Compounds in Radiation Chemistry

International Nuclear Information System (INIS)

Sims, H.E.; Dey, G.R.; Vaudey, C.E.; Peaucelle, C.; Boucher, J.L.; Toulhoat, N.; Bererd, N.; Koppenol, W.H.; Janata, E.; Dauvois, V.; Durand, D.; Legand, S.; Roujou, J.L.; Doizi, D.; Dannoux, A.; Lamouroux, C.

2009-01-01

Water radiolysis in presence of N 2 is probably the topic the most controversy in the field of water radiolysis. It still exists a strong discrepancy between the different reports of ammonia formation by water radiolysis in presence of N 2 and moreover in absence of oxygen there is no agreement on the formation or not of nitrogen oxide like NO 2 - and NO 3 -. These discrepancies come from multiple sources: - the complexity of the reaction mechanisms where nitrogen is involved - the experimental difficulties - and, the irradiation conditions. The aim of the workshop is to capitalize the knowledge needed to go further in simulations and understanding the problems caused (or not) by the presence of nitrogen / water in the environment of radioactive materials. Implications are evident in terms of corrosion, understanding of biological systems and atmospheric chemistry under radiation. Topics covered include experimental and theoretical approaches, application and fundamental researches: - Nitrate and Ammonia in radiation chemistry in nuclear cycle; - NOx in biological systems and atmospheric chemistry; - Formation of Nitrogen compounds in Nuclear installations; - Nitrogen in future power plant projects (Gen4, ITER...) and large particle accelerators. This document gathers the transparencies available for 7 of the presentations given at this workshop. These are: - H.E SIMS: 'Radiation Chemistry of Nitrogen Compounds in Nuclear Power Plant'; - G.R. DEY: 'Nitrogen Compounds Formation in the Radiolysis of Aqueous Solutions'; - C.E. VAUDEY et al.: 'Radiolytic corrosion of nuclear graphite studied with the dedicated gas irradiation cell of IPNL'; - J.L. BOUCHER: 'Roles and biosynthesis of NO in eukaryotes and prokaryotes'; - W.H. KOPPENOL: 'Chemistry of NOx'; - E. JANATA: 'Yield of OH in N 2 O saturated aqueous solution'; - V. DAUVOIS: 'Analytical strategy for the study of radiolysis gases'

Multiresolution signal decomposition schemes

NARCIS (Netherlands)

J. Goutsias (John); H.J.A.M. Heijmans (Henk)

1998-01-01

textabstract[PNA-R9810] Interest in multiresolution techniques for signal processing and analysis is increasing steadily. An important instance of such a technique is the so-called pyramid decomposition scheme. This report proposes a general axiomatic pyramid decomposition scheme for signal analysis

Integral representations of solutions of the wave equation based on relativistic wavelets

International Nuclear Information System (INIS)

Perel, Maria; Gorodnitskiy, Evgeny

2012-01-01

A representation of solutions of the wave equation with two spatial coordinates in terms of localized elementary ones is presented. Elementary solutions are constructed from four solutions with the help of transformations of the affine Poincaré group, i.e. with the help of translations, dilations in space and time and Lorentz transformations. The representation can be interpreted in terms of the initial-boundary value problem for the wave equation in a half-plane. It gives the solution as an integral representation of two types of solutions: propagating localized solutions running away from the boundary under different angles and packet-like surface waves running along the boundary and exponentially decreasing away from the boundary. Properties of elementary solutions are discussed. A numerical investigation of coefficients of the decomposition is carried out. An example of the decomposition of the field created by sources moving along a line with different speeds is considered, and the dependence of coefficients on speeds of sources is discussed. (paper)

Photochemical fabrication of size-controllable gold nanoparticles on chitosan and their application on catalytic decomposition of acetaldehyde

International Nuclear Information System (INIS)

Yu, Chung-Chin; Yang, Kuang-Hsuan; Liu, Yu-Chuan; Chen, Bo-Chuen

2010-01-01

In this work, we report a new pathway to prepare size-controllable gold nanoparticles (NPs) on chitosan (Ch) in aqueous solutions for improving catalytic decomposition of acetaldehyde by pure gold NPs at room temperature. First, Au substrates were cycled in deoxygenated aqueous solutions containing 0.1N NaCl and 1 g/L Ch from -0.28 to +1.22 V vs Ag/AgCl at 500 mV/s for 200 scans. Then the solutions were irradiated with UV lights of different wavelengths to prepare size-controllable Au NPs on Ch. Experimental results indicate that the particle sizes of prepared NPs are increased when UV lights with longer wavelengths were employed. The particle sizes of resulted Au NPs can be controlled from 10 to 50 nm. Moreover, the decomposition of acetaldehydes in wines can be significantly enhanced by ca. 190% of magnitude due to the contribution of the adsorption of Au NPs on Ch.

Symmetric Tensor Decomposition

DEFF Research Database (Denmark)

Brachat, Jerome; Comon, Pierre; Mourrain, Bernard

2010-01-01

We present an algorithm for decomposing a symmetric tensor, of dimension n and order d, as a sum of rank-1 symmetric tensors, extending the algorithm of Sylvester devised in 1886 for binary forms. We recall the correspondence between the decomposition of a homogeneous polynomial in n variables...... of polynomial equations of small degree in non-generic cases. We propose a new algorithm for symmetric tensor decomposition, based on this characterization and on linear algebra computations with Hankel matrices. The impact of this contribution is two-fold. First it permits an efficient computation...... of the decomposition of any tensor of sub-generic rank, as opposed to widely used iterative algorithms with unproved global convergence (e.g. Alternate Least Squares or gradient descents). Second, it gives tools for understanding uniqueness conditions and for detecting the rank....

Thermal decomposition of beryllium perchlorate tetrahydrate

International Nuclear Information System (INIS)

Berezkina, L.G.; Borisova, S.I.; Tamm, N.S.; Novoselova, A.V.

1975-01-01

Thermal decomposition of Be(ClO 4 ) 2 x4H 2 O was studied by the differential flow technique in the helium stream. The kinetics was followed by an exchange reaction of the perchloric acid appearing by the decomposition with potassium carbonate. The rate of CO 2 liberation in this process was recorded by a heat conductivity detector. The exchange reaction yielding CO 2 is quantitative, it is not the limiting one and it does not distort the kinetics of the process of perchlorate decomposition. The solid products of decomposition were studied by infrared and NMR spectroscopy, roentgenography, thermography and chemical analysis. A mechanism suggested for the decomposition involves intermediate formation of hydroxyperchlorate: Be(ClO 4 ) 2 x4H 2 O → Be(OH)ClO 4 +HClO 4 +3H 2 O; Be(OH)ClO 4 → BeO+HClO 4 . Decomposition is accompained by melting of the sample. The mechanism of decomposition is hydrolytic. At room temperature the hydroxyperchlorate is a thick syrup-like compound crystallizing after long storing

Decomposition of some amines and amino acids in steam generator environments

International Nuclear Information System (INIS)

Jayaweera, P.; Hettiarachchi, S.; Millett, P.J.

1994-01-01

Hydrothermal decomposition rate constants and high temperature pH values of some selected high-molecular weight amines and amino acids were measured under simulated steam generator conditions. These amines and amino acids were evaluated as potential crevice buffering agents for steam generator applications in pressurized water reactors. The study showed that, although the high molecular weight amines undergo hydrothermal decomposition, they have a better buffer capacity than their low molecular weight counterparts at 290 C. The amines provide effective crevice buffering by increasing the pH of the simulated crevice solution by as much as 2.84 to 4.24 units. However, volatility data for the amines and amino acids are needed before in-plant testing to ensure that amines can concentrate sufficiently in steam generator crevices to provide effective buffering

Optimization of reactor coolant shutdown chemistry practices for crud inventory management

International Nuclear Information System (INIS)

Fellers, B.; Barnette, J.; Stevens, J.; Perkins, D.

2002-01-01

This report describes reactor coolant shutdown chemistry control practices at Comanche Peak Steam Electric Station (CPSES, TXU-Generation, USA). The shutdown evolution is managed from a process control perspective to achieve conditions most favorable to crud decomposition and to avoiding re-precipitation of metals. The report discusses the evolution of current industry practices and the necessity for greater emphasis on shutdown chemistry control in response to Axial Offset Anomaly and growth of ex-core radiation fields during outage conditions. Nuclear Industry experience with axial offset anomaly (AOA), radiation field growth and unexpected behavior of crud during reactor shutdowns has encouraged the refinement of chemistry control practices during plant shutdown and startup. The strong implication of nickel rich crud as a cause of AOA and unexpected crud behavior has resulted in a focus on nickel inventory management. The goals for Comanche Peak Steam Electric Station (CPSES) include maintaining solubility of metals and radioisotopes, maximizing nickel removal and effective cleanup with demineralizers. This paper provides results and lessons learned from long term efforts to optimize the shutdown process. (authors)

Domain decomposition methods for the mixed dual formulation of the critical neutron diffusion problem; Methodes de decomposition de domaine pour la formulation mixte duale du probleme critique de la diffusion des neutrons

Energy Technology Data Exchange (ETDEWEB)

Guerin, P

2007-12-15

The neutronic simulation of a nuclear reactor core is performed using the neutron transport equation, and leads to an eigenvalue problem in the steady-state case. Among the deterministic resolution methods, diffusion approximation is often used. For this problem, the MINOS solver based on a mixed dual finite element method has shown his efficiency. In order to take advantage of parallel computers, and to reduce the computing time and the local memory requirement, we propose in this dissertation two domain decomposition methods for the resolution of the mixed dual form of the eigenvalue neutron diffusion problem. The first approach is a component mode synthesis method on overlapping sub-domains. Several Eigenmodes solutions of a local problem solved by MINOS on each sub-domain are taken as basis functions used for the resolution of the global problem on the whole domain. The second approach is a modified iterative Schwarz algorithm based on non-overlapping domain decomposition with Robin interface conditions. At each iteration, the problem is solved on each sub domain by MINOS with the interface conditions deduced from the solutions on the adjacent sub-domains at the previous iteration. The iterations allow the simultaneous convergence of the domain decomposition and the eigenvalue problem. We demonstrate the accuracy and the efficiency in parallel of these two methods with numerical results for the diffusion model on realistic 2- and 3-dimensional cores. (author)

Cobalt Oxide Catalysts Supported on CeO2–TiO2 for Ethanol Oxidation and N2O Decomposition.

Czech Academy of Sciences Publication Activity Database

Jirátová, Květa; Kovanda, F.; Balabánová, Jana; Koloušek, D.; Klegová, A.; Pacultová, K.; Obalová, L.

2017-01-01

Roč. 12, č. 1 (2017), s. 121-139 ISSN 1878-5190. [Pannonian Symposium on Catalysis. Siófok, 19.09.2016-23.09.2016] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : cobalt oxide catalysts * ethanol total oxidation * N2O decomposition Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 1.264, year: 2016

Quantitative Determination of Ala-Ala Conformer Ratios in Solution by Decomposition of Raman Optical Activity Spectra

Czech Academy of Sciences Publication Activity Database

Jungwirth, Jakub; Šebestík, Jaroslav; Šafařík, Martin; Kapitán, J.; Bouř, Petr

2017-01-01

Roč. 121, č. 38 (2017), s. 8956-8964 ISSN 1520-6106 R&D Projects: GA ČR(CZ) GA16-05935S; GA MŠk(CZ) LTC17012 Grant - others:COST(XE) CA15214 Institutional support: RVO:61388963 Keywords : density functional theory * vibrational circular dichroism * ab initio calculation Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.177, year: 2016

Decomposition of thermally unstable substances in film evaporators

Energy Technology Data Exchange (ETDEWEB)

Matz, G

1982-10-01

It is widely known that film evaporators are considered to permit really gentle evaporation of heat-sensitive substances. Nevertheless, decomposition of such substance still occurs to an extent depending upon the design and operation of the evaporator. In the following a distinction is made between evaporators with films not generated mechanically, namely the long tube evaporator (lTE) or climbing film evaporator, the falling film evaporator (FFE) and the multiple phase helical tube (MPT) or helical coil evaporators (TFE). Figs 1 and 2 illustrate the mode of operation. A theory of the decomposition of thermally unstable substances in these evaporators is briefly outlined and compared with measurements. Such a theory cannot be developed without any experimental checks; on the other hand, meausrements urgently need a theoretical basis if only to establish what actually has to be measured. All experiments are made with a system of readily adjustable decomposability, namely with aqueous solutions of saccharose; the thermal inversion of this compound can be controlled by addition of various amounts or concentrations of hydrochloric acid. In the absence of any catalysis by hydrochloric acid, the decomposition rates within in the temperature interval studied (60-130/sup 0/C) are so low that the experiments would take much too long and determination of the concentration differences (generally by polarimetric methods) would be very complicated. Such slight effects would also be very unfavourable for comparison with theory. (orig.)

Decolourisation of dye solutions by oxidation with H2O2 in the presence of modified activated carbons

International Nuclear Information System (INIS)

Santos, V.P.; Pereira, M.F.R.; Faria, P.C.C.; Orfao, J.J.M.

2009-01-01

The decolourisation of dye solutions by oxidation with H 2 O 2 , using activated carbon as catalyst, is studied. For this purpose, three different samples, mainly differing in the respective surface chemistries, were prepared and characterized. Moreover, this work involved three pH levels, corresponding to acid, neutral and alkaline solutions, and six dyes belonging to several classes. The catalytic decolourisation tests were performed in a laboratorial batch reactor. Adsorption on activated carbon and non-catalytic peroxidation kinetic experiments were also carried out in the same reactor, in order to compare the efficiencies of the three processes. The non-catalytic reaction is usually inefficient and, typically, adsorption presents a low level of decolourisation. In these cases, the combination of activated carbon with hydrogen peroxide may significantly enhance the process, since the activated carbon catalyses the decomposition of H 2 O 2 into hydroxyl radicals, which are very reactive. Based on the experiments with the different activated carbon samples, which have similar physical properties, it is proved that the surface chemistry of the catalyst plays a key role, being the basic sample the most active. This is discussed considering the involvement of the free electrons on the graphene basal planes of activated carbon as active centres for the catalytic reaction. Additionally, it is shown that the decolourisation is enhanced at high pH values, and a possible explanation for this observation, based on the proposed mechanism, is given

Laboratory studies of ion-molecule reactions and interstellar chemistry

International Nuclear Information System (INIS)

Koyano, Inosuke

1989-01-01

Several types of laboratory studies have been performed on ion-molecule reactions relevant to the formation of the interstellar molecules. Special emphasis is placed on the formation, structure, and reactivity of the C 3 H 3 + ions, which are believed to play a key role in interstellar chemistry. When these ions are produced by the reaction of C 3 H 4+ with C 3 H 4 in a beam-gas arrangement, their times-of-flight (TOF) show abnormally broad distributions regardless of the sources of the reactant C 3 H 4 + ion (photoionization of allene, propyne, the cyclopropene) and the nature of the neutral reactant, while all other product ions from the same reaction show sharp TOF distributions. On the other hand, all C 3 H 3 + ions produced by unimolecular decomposition of energetic C 3 H 4 + ions show sharp TOF distribution. The peculiarity of the C 3 H 3 + ions manifested in these and other experiments is discussed in conjunction with interstellar chemistry

Some nonlinear space decomposition algorithms

Energy Technology Data Exchange (ETDEWEB)

Tai, Xue-Cheng; Espedal, M. [Univ. of Bergen (Norway)

1996-12-31

Convergence of a space decomposition method is proved for a general convex programming problem. The space decomposition refers to methods that decompose a space into sums of subspaces, which could be a domain decomposition or a multigrid method for partial differential equations. Two algorithms are proposed. Both can be used for linear as well as nonlinear elliptic problems and they reduce to the standard additive and multiplicative Schwarz methods for linear elliptic problems. Two {open_quotes}hybrid{close_quotes} algorithms are also presented. They converge faster than the additive one and have better parallelism than the multiplicative method. Numerical tests with a two level domain decomposition for linear, nonlinear and interface elliptic problems are presented for the proposed algorithms.

Determination of boron in graphite by a wet oxidation decomposition/curcumin photometric method

International Nuclear Information System (INIS)

Watanabe, Kazuo; Toida, Yukio

1995-01-01

The wet oxidation decomposition of graphite materials has been studied for the accurate determination of boron using a curcumin photometric method. A graphite sample of 0.5 g was completely decomposed with a mixture of 5 ml of sulfuric acid, 3 ml of perchloric acid, 0.5 ml of nitric acid and 5 ml of phosphoric acid in a silica 100 ml Erlenmeyer flask fitted with an air condenser at 200degC. Any excess of perchloric and nitric acids in the solution was removed by heating on a hot plate at 150degC. Boron was distilled with methanol, and then recovered in 10 ml of 0.2 M sodium hydroxide. The solution was evaporated to dryness. To the residue were added curcumin-acetic acid and sulfuric-acetic acid. The mixture was diluted with ethanol, and the absorbance at 555 nm was measured. The addition of 5 ml of phosphoric acid proved to be effective to prevent any volatilization loss of boron during decomposition of the graphite sample and evaporation of the resulting solution. The relative standard deviation was 4-8% for samples with 2 μg g -1 levels of boron. The results on CRMs JAERI-G5 and G6 were in good agreement with the certified values. (author)

Ions in solution basic principles of chemical interactions

CERN Document Server

Burgess, J

1999-01-01

This outline of the principles and chemical interactions in inorganic solution chemistry delivers a course module in an area of considerable complexity. Problems with solutions and tutorial hints to test comprehension have been added as a feature to check readers' understanding and assist self-study. Exercises and projects are also provided to help readers deepen and extend their knowledge and understanding. Inorganic solution chemistry is treated thoroughly Emphasis is placed upon NMR, UV-VIS, IR Raman spectroscopy, X-ray diffraction, and such topics as acid-base behaviour, stability constants and kinetics.

G-Doob-Meyer Decomposition and Its Applications in Bid-Ask Pricing for Derivatives under Knightian Uncertainty

Directory of Open Access Journals (Sweden)

Wei Chen

2015-01-01

Full Text Available The target of this paper is to establish the bid-ask pricing framework for the American contingent claims against risky assets with G-asset price systems on the financial market under Knightian uncertainty. First, we prove G-Dooby-Meyer decomposition for G-supermartingale. Furthermore, we consider bid-ask pricing American contingent claims under Knightian uncertainty, by using G-Dooby-Meyer decomposition; we construct dynamic superhedge strategies for the optimal stopping problem and prove that the value functions of the optimal stopping problems are the bid and ask prices of the American contingent claims under Knightian uncertainty. Finally, we consider a free boundary problem, prove the strong solution existence of the free boundary problem, and derive that the value function of the optimal stopping problem is equivalent to the strong solution to the free boundary problem.

Large-scale fluctuations in the diffusive decomposition of solid solutions

International Nuclear Information System (INIS)

Karpov, V.G.; Grimsditch, M.

1995-01-01

The concept of an instability in the classic Ostwald ripening theory with respect to compositional fluctuations is suggested. We show that small statistical fluctuations in the precipitate phase lead to gigantic Coulomb-like fluctuations in the solute concentration which in turn affect the ripening. As a result large-scale fluctuations in both the precipitate and solute concentrations appear. These fluctuations are characterized by amplitudes of the order of the average values of the corresponding quantities and by a space scale L∼(na) -1/2 which is considerably greater than both the average nuclear radius and internuclear distance. The Lifshitz-Slyozov theory of ripening is shown to remain locally applicable, over length scales much less than L. The implications of these findings for elastic light scattering in solid solutions that have undergone Ostwald ripening are considered

Large-scale fluctuations in the diffusive decomposition of solid solutions

Science.gov (United States)

Karpov, V. G.; Grimsditch, M.

1995-04-01

The concept of an instability in the classic Ostwald ripening theory with respect to compositional fluctuations is suggested. We show that small statistical fluctuations in the precipitate phase lead to gigantic Coulomb-like fluctuations in the solute concentration which in turn affect the ripening. As a result large-scale fluctuations in both the precipitate and solute concentrations appear. These fluctuations are characterized by amplitudes of the order of the average values of the corresponding quantities and by a space scale L~(na)-1/2 which is considerably greater than both the average nuclear radius and internuclear distance. The Lifshitz-Slyozov theory of ripening is shown to remain locally applicable, over length scales much less than L. The implications of these findings for elastic light scattering in solid solutions that have undergone Ostwald ripening are considered.

A context based approach using Green Chemistry/Bio-remediation principles to enhance interest and learning of organic chemistry in a high school AP chemistry classroom

Science.gov (United States)

Miller, Tricia

The ability of our planet to sustain life and heal itself is not as predictable as it used to be. Our need for educated future scientists who know what our planet needs, and can passionately apply that knowledge to find solutions should be at the heart of science education today. This study of learning organic chemistry through the lens of the environmental problem "What should be done with our food scraps?" explores student interest, and mastery of certain concepts in organic chemistry. This Green Chemistry/ Bio-remediation context-based teaching approach utilizes the Nature MillRTM, which is an indoor food waste composting machine, to learn about organic chemistry, and how this relates to landfill reduction possibilities, and resource production. During this unit students collected food waste from their cafeteria, and used the Nature MillRTM to convert food waste into compost. The use of these hands on activities, and group discussions in a context-based environment enhanced their interest in organic chemistry, and paper chromatography. According to a one-tailed paired T-test, the result show that this context-based approach is a significant way to increase both student interest and mastery of the content.

Coupling between water chemistry and thermal output at unsaturated repositories

International Nuclear Information System (INIS)

Walton, J.; LeMone, D.; Casey, D.

1995-01-01

This paper summarizes issues in predicting thermohydrology in the near field of a deep geological repository and the implications for performance assessment. Predicted thermohydrology depends on waste package design, and particularly on backfill materials. The coupling between solute concentrations and thermal gradients leads to a prediction of highly variable water chemistry in the near field which is radically different than the initial, undisturbed water chemistry; however, most analyses to date assume that waste package chemistry is approximately the same as initial pore water chemistry. Several alternative, simplified approaches for performance assessment are discussed

Chemistry Division. Quarterly progress report for period ending June 30, 1949

Energy Technology Data Exchange (ETDEWEB)

1949-09-14

Progress reports are presented for the following tasks: (1) nuclear and chemical properties of heavy elements (solution chemistry, phase rule studies); (2) nuclear and chemical properties of elements in the fission product region; (3) general nuclear chemistry; (4) radio-organic chemistry; (5) chemistry of separations processes; (6) physical chemistry and chemical physics; (7) radiation chemistry; (8) physical measurements and instrumentation; and (9) analytical chemistry. The program of the chemistry division is divided into two efforts of approximately equal weight with respect to number of personnel, chemical research, and analytical service for the Laboratory. The various research problems fall into the following classifications: (1) chemical separation processes for isolation and recovery of fissionable material, production of radioisotopes, and military applications; (2) reactor development; and (3) fundamental research.

Domain decomposition methods for the mixed dual formulation of the critical neutron diffusion problem

International Nuclear Information System (INIS)

Guerin, P.

2007-12-01

The neutronic simulation of a nuclear reactor core is performed using the neutron transport equation, and leads to an eigenvalue problem in the steady-state case. Among the deterministic resolution methods, diffusion approximation is often used. For this problem, the MINOS solver based on a mixed dual finite element method has shown his efficiency. In order to take advantage of parallel computers, and to reduce the computing time and the local memory requirement, we propose in this dissertation two domain decomposition methods for the resolution of the mixed dual form of the eigenvalue neutron diffusion problem. The first approach is a component mode synthesis method on overlapping sub-domains. Several Eigenmodes solutions of a local problem solved by MINOS on each sub-domain are taken as basis functions used for the resolution of the global problem on the whole domain. The second approach is a modified iterative Schwarz algorithm based on non-overlapping domain decomposition with Robin interface conditions. At each iteration, the problem is solved on each sub domain by MINOS with the interface conditions deduced from the solutions on the adjacent sub-domains at the previous iteration. The iterations allow the simultaneous convergence of the domain decomposition and the eigenvalue problem. We demonstrate the accuracy and the efficiency in parallel of these two methods with numerical results for the diffusion model on realistic 2- and 3-dimensional cores. (author)

A new approach for the beryl mineral decomposition: elemental characterisation using ICP-AES and FAAS

International Nuclear Information System (INIS)

Nathan, Usha; Premadas, A.

2013-01-01

A new approach for the beryl mineral sample decomposition and solution preparation method suitable for the elemental analysis using ICP-AES and FAAS is described. For the complete sample decomposition four different decomposition procedures are employed such as with (i) ammonium bi-fluoride alone (ii) a mixture of ammonium bi-fluoride and ammonium sulphate (iii) powdered mixture of NaF and KHF 2 in 1: 3 ratio, and (iv) acid digestion treatment using hydrofluoric acid and nitric acid mixture, and the residue fused with a powdered mixture NaF and KHF 2 . Elements like Be, Al, Fe, Mn, Ti, Cr, Ca, Mg, and Nb are determined by ICP-AES and Na, K, Rb and Cs are determined by FAAS method. Fusion with 2g ammonium bifluoride flux alone is sufficient for the complete decomposition of 0.400 gram sample. The values obtained by this decomposition procedure are agreed well with the reported method. Accuracy of the proposed method was checked by analyzing synthetic samples prepared in the laboratory by mixing high purity oxides having a chemical composition similar to natural beryl mineral. It indicates that the accuracy of the method is very good, and the reproducibility is characterized by the RSD 1 to 4% for the elements studied. (author)

Forefront of PUREX system engineering. Chemistry and engineering of ruthenium, technetium and neptunium

International Nuclear Information System (INIS)

2004-07-01

The paper reports the activity of the research committee organized by the Atomic Energy Society of Japan on 'Ruthenium and Technetium Chemistry in the PUREX System', with focusing on basic behaviors of ruthenium, technetium and neptunium in the PUREX process, the principles of plant design, and behaviors during the final waste treatment. The scope of the work includes the following major topics: (1) basic solution and solid-state chemistry; (2) basic solution and solid-state chemistry of minor actinides in particular, Np; (3) partitioning chemistry in the PUREX system and environmental behavior of the components; (4) processes of recovery, purification, and utilization of rare metal fission products; (5) field data on plant design, operation, decontamination, and decommissioning; (6) numerical process simulations and process control technologies; (7) compilation of a data base for process chemistry and plant engineering. (S. Ohno)

Dissolution of oxalate precipitate and destruction of oxalate ion by hydrogen peroxide in nitric acid solution

International Nuclear Information System (INIS)

Kim, Eung-Ho; Chung, Dong-Yong; Park, Jin-Ho; Yoo, Jae-Hyung

2000-01-01

This study aims at developing an oxalate precipitation process, which is applicable to a partitioning of long-lived radionuclides from the high-level radioactive liquid waste. In order to achieve this, a study for decomposition-reaction of oxalic acid by hydrogen peroxide was first carried out. The decomposition rates of H 2 O 2 and oxalic acid increased with an increase of nitric acid concentration, and especially those decomposition rates steeply increased at more than 2 M HNO 3 . Based on this result, the decomposition kinetics of H 2 O 2 and oxalic acid were suggested in this work. Then, the dissolution of oxalate precipitate and the destruction of oxalate ion in the solution were examined. Oxalate precipitates were prepared by adding oxalic acid into a simulated radioactive waste containing 8 metallic elements. The precipitates obtained thereby were dissolved in various nitric acid concentrations and reacted with H 2 O 2 at 90degC. When the oxalates were completely dissolved, most of the oxalates were decomposed by adding H 2 O 2 , but in a slurry state the decomposition yield of the oxalate decreased with an increase of the slurry density in the solution. Such phenomenon was considered to be due to a catalytic decomposition of H 2 O 2 on a solid surface of oxalate and the decomposition mechanism was explained by a charge transfer from a surface of oxalate solid to H 2 O 2 , producing OH radicals which can destruct H 2 O 2 explosively. Accordingly, the experimental condition for the decomposition of the oxalate precipitates was found to be most favorable at 3 M HNO 3 under the initial concentrations of 0.2 M oxalate and 1 M H 2 O 2 . At 3M HNO 3 , oxalate precipitates could be safely and completely dissolved, and almost decomposed. Additionally, it was observed that the presence of ferric ion in the solution largely affects the decomposition rate of H 2 O 2 . This could be explained by a chain reaction of hydrogen peroxide with ferric ion in the solution

Thermal Co-Decomposition of Silver Acetylacetonate and Tin (II) Hexafluoroacetylacetonate: Formation of Carbonaceous Ag/AgxSn(x=4 and 6.7)/SnO2 Composites

Czech Academy of Sciences Publication Activity Database

Křenek, T.; Duchek, P.; Urbanová, Markéta; Pokorná, Dana; Bezdička, Petr; Jakubec, Ivo; Pola, M.; Čerstvý, R.; Kovářík, T.; Galíková, Anna; Pola, Josef

2013-01-01

Roč. 566, AUG 20 (2013), s. 92-99 ISSN 0040-6031 Grant - others:GA MŠK(CZ) CZ1.05/2.1.00/03.0088 Institutional support: RVO:67985858 ; RVO:61388980 Keywords : co-decomposition * thermal gravimetric analysis * Ag-Sn intermetallic compounds Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.105, year: 2013

Spectroscopy and chemistry of uranium IV

International Nuclear Information System (INIS)

Folcher, G.; Rigny, P.

1980-06-01

Different fundamental research papers on uranium IV are presented, some were never edited. Molecular spectroscopy was used for identification and structural study of uranium IV in aqueous or organic solutions. The fields studied are: coordination, stereochemistry, electronic structure and chemical properties. For interpretation of results some studies were made with solid compounds or with thorium compounds or thorium complexes. Knowledge of actinides chemistry is improved, uranium and thorium being models for 5 f ions, extractive chemistry is better understood and new applications are possible [fr

Decomposition of Multi-player Games

Science.gov (United States)

Zhao, Dengji; Schiffel, Stephan; Thielscher, Michael

Research in General Game Playing aims at building systems that learn to play unknown games without human intervention. We contribute to this endeavour by generalising the established technique of decomposition from AI Planning to multi-player games. To this end, we present a method for the automatic decomposition of previously unknown games into independent subgames, and we show how a general game player can exploit a successful decomposition for game tree search.

Appling Laplace Adomian decomposition method for delay differential equations with boundary value problems

Science.gov (United States)

Yousef, Hamood Mohammed; Ismail, Ahmad Izani

2017-11-01

In this paper, Laplace Adomian decomposition method (LADM) was applied to solve Delay differential equations with Boundary Value Problems. The solution is in the form of a convergent series which is easy to compute. This approach is tested on two test problem. The findings obtained exhibit the reliability and efficiency of the proposed method.

Variability in chemistry of surface and soil waters of an ...

African Journals Online (AJOL)

Water chemistry is important for the maintenance of wetland structure and function. Interpreting ecological patterns in a wetland system therefore requires an in-depth understanding of the water chemistry of that system. We investigated the spatial distribution of chemical solutes both in soil pore water and surface water, ...

Use of pulse radiolysis for the study of the chemistry of aqueous ozone and ozonide solutions

DEFF Research Database (Denmark)

Sehested, Knud; Holcman, Jerzy; Bjergbakke, Erling

1986-01-01

The chemistry of aqeous ozone, O3, and ozonide, O3−, is of great interest from a technological, environmental and scientific point of view. The literature about their aqueous chemistry is extensive, the reaction mechanisms are still not well understood. The ozonide anion is a free radical that is...... reactions and provides kinetic data sufficient for computer simulations of aqueous O3/O3− chemistry.......The chemistry of aqeous ozone, O3, and ozonide, O3−, is of great interest from a technological, environmental and scientific point of view. The literature about their aqueous chemistry is extensive, the reaction mechanisms are still not well understood. The ozonide anion is a free radical...

Radiation chemistry in solvent extraction: FY2010 Research

International Nuclear Information System (INIS)

Mincher, Bruce J.; Martin, Leigh R.; Mezyk, Stephen P.

2010-01-01

This report summarizes work accomplished under the Fuel Cycle Research and Development (FCR and D) program in the area of radiation chemistry during FY 2010. The tasks assigned during FY 2010 included: (1) Development of techniques to measure free radical reaction kinetics in the organic phase. (2) Initiation of an alpha-radiolysis program; (3) Initiation of an effort to understand dose rate effects in radiation chemistry; (4) Continued work to characterize TALSPEAK radiation chemistry Progress made on each of these tasks is reported here. Briefly, a method was developed and used to measure the kinetics of the reactions of the NO3 radical with solvent extraction ligands in organic solution, and the method to measure OH radical reactions under the same conditions has been designed. Rate constants for the CMPO and DMDOHEMA reaction with NO3 radical in organic solution are reported. Alpha-radiolysis was initiated on samples of DMDOHEMA in alkane solution using He ion beam irradiation and 211At isotope irradiation. The samples are currently being analyzed for comparison to DMDOHEMA ?-irradiations using a custom-developed mass spectrometric method. Results are also reported for the radiolytic generation of nitrous acid, in ?-irradiated nitric acid. It is shown that the yield of nitrous acid is unaffected by an order-of-magnitude change in dose rate. Finally, recent results for TALSPEAK radiolysis are reported, summarizing the effects on solvent extraction efficiency due to HDEHP irradiation, and the stable products of lactic acid and DTPA irradiation. In addition, results representing increased scope are presented for the radiation chemistry program. These include an investigation of the effect of metal complexation on radical reaction kinetics using DTPA as an example, and the production of a manuscript reporting the mechanism of Cs-7SB radiolysis. The Cs-7SB work takes advantage of recent results from a current LDRD program to understand the fundamental chemistry of

Postradiation destruction of dextran in solutions

International Nuclear Information System (INIS)

Bondarenko, N.T.; Sharpatyj, V.A.

1989-01-01

Methods of pH-metry, UV absorption and ESR spectroscopy were used to study the oxidation destruction of dextran solutions, stored in the air after gamma irradiation ( 60 Co) bydoses of up to 200 kGy. It is shown that polymer destruction under mentioned conditions is initiated by hydroperoxide decomposition with successive radical transformation into peroxides. Experimentally observed periodical change of acidity of irradiated dextran solutions is also explained by transformations of peroxy radicals

Simulating the long-term chemistry of an upland UK catchment: Major solutes and acidification

Energy Technology Data Exchange (ETDEWEB)

Tipping, E. [Centre for Ecology and Hydrology (Lancaster), Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)]. E-mail: et@ceh.ac.uk; Lawlor, A.J. [Centre for Ecology and Hydrology (Lancaster), Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Lofts, S. [Centre for Ecology and Hydrology (Lancaster), Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)

2006-05-15

CHUM-AM was used to investigate changes in soil and water chemical variables in four moorland sub-catchments in Cumbria UK, to which non-marine S deposition has declined by 65% since the 1970s. The principal processes represented in the model comprise N and S uptake and release, water movements, the binding of cations by soil organic matter, chemical interactions in solution, and chemical weathering. CHUM-AM reproduced reasonably well the current soil pH and pools of N and S, and changes in streamwater chemistry over the period 1970-2000, notably decreases in the concentrations of alkaline earth cations and sulphate, and increases in pH. The model also predicts streamwater pH-Al relationships in agreement with observations. Predictive calculations suggest that constant atmospheric deposition of N at present rates will lead to N saturation and re-acidification, whereas a 50% reduction in N would stabilise soil and streamwater pH at about the present levels. - CHUM-AM accounts for recovery from acidification due to sulphur deposition, but predicts re-acidification if nitrogen deposition is not reduced.

IMF-Slices for GPR Data Processing Using Variational Mode Decomposition Method

Directory of Open Access Journals (Sweden)

Xuebing Zhang

2018-03-01

Full Text Available Using traditional time-frequency analysis methods, it is possible to delineate the time-frequency structures of ground-penetrating radar (GPR data. A series of applications based on time-frequency analysis were proposed for the GPR data processing and imaging. With respect to signal processing, GPR data are typically non-stationary, which limits the applications of these methods moving forward. Empirical mode decomposition (EMD provides alternative solutions with a fresh perspective. With EMD, GPR data are decomposed into a set of sub-components, i.e., the intrinsic mode functions (IMFs. However, the mode-mixing effect may also bring some negatives. To utilize the IMFs’ benefits, and avoid the negatives of the EMD, we introduce a new decomposition scheme termed variational mode decomposition (VMD for GPR data processing for imaging. Based on the decomposition results of the VMD, we propose a new method which we refer as “the IMF-slice”. In the proposed method, the IMFs are generated by the VMD trace by trace, and then each IMF is sorted and recorded into different profiles (i.e., the IMF-slices according to its center frequency. Using IMF-slices, the GPR data can be divided into several IMF-slices, each of which delineates a main vibration mode, and some subsurface layers and geophysical events can be identified more clearly. The effectiveness of the proposed method is tested using synthetic benchmark signals, laboratory data and the field dataset.

Solution Calorimetry Experiments for Physical Chemistry.

Science.gov (United States)

Raizen, Deborah A.; And Others

1988-01-01

Presents two experiments: the first one measures the heat of an exothermic reaction by the reduction of permanganate by the ferris ion; the second one measures the heat of an endothermic process, the mixing of ethanol and cyclohexane. Lists tables to aid in the use of the solution calorimeter. (MVL)

Physical chemistry and the environment

International Nuclear Information System (INIS)

Dunning, T.H. Jr.; Garrett, B.C.; Kolb, C.E. Jr.; Shaw, R.W.; Choppin, G.R.; Wagner, A.F.

1994-08-01

From the ozone hole and the greenhouse effect to plastics recycling and hazardous waste disposal, society faces a number of issues, the solutions to which require an unprecedented understanding of the properties of molecules. We are coming to realize that the environment is a coupled set of chemical systems, its dynamics determining the welfare of the biosphere and of humans in particular. These chemical systems are governed by fundamental molecular interactions, and they present chemists with an unparalleled challenge. The application of current concepts of molecular behavior and of up-to-date experimental and computational techniques can provide us with insights into the environment that are needed to mitigate past damage, to anticipate the impact of current human activity, and to avoid future insults to the environment. Environmental chemistry encompasses a number of separate, yet interlocking, areas of research. In all of these areas progress is limited by an inadequate understanding of the underlying chemical processes involved. Participation of all chemical approaches -- experimental, theoretical and computational -- and of all disciplines of chemistry -- organic, inorganic, physical, analytical and biochemistry -- will be required to provide the necessary fundamental understanding. The Symposium on ''Physical Chemistry and the Environment'' was designed to bring the many exciting and challenging physical chemistry problems involved in environmental chemistry to the attention of a larger segment of the physical chemistry community

Effect of charged and excited states on the decomposition of 1,1-diamino-2,2-dinitroethylene molecules

International Nuclear Information System (INIS)

Kimmel, Anna V.; Sushko, Peter V.; Shluger, Alexander L.; Kuklja, Maija M.

2007-01-01

The authors have calculated the electronic structure of individual 1,1-diamino-2,2-dinitroethylene molecules (FOX-7) in the gas phase by means of density functional theory with the hybrid B3LYP functional and 6-31+G(d,p) basis set and considered their dissociation pathways. Positively and negatively charged states as well as the lowest excited states of the molecule were simulated. They found that charging and excitation can not only reduce the activation barriers for decomposition reactions but also change the dominating chemistry from endo- to exothermic type. In particular, they found that there are two competing primary initiation mechanisms of FOX-7 decomposition: C-NO 2 bond fission and C-NO 2 to CONO isomerization. Electronic excitation or charging of FOX-7 disfavors CONO formation and, thus, terminates this channel of decomposition. However, if CONO is formed from the neutral FOX-7 molecule, charge trapping and/or excitation results in spontaneous splitting of an NO group accompanied by the energy release. Intramolecular hydrogen transfer is found to be a rare event in FOX-7 unless free electrons are available in the vicinity of the molecule, in which case HONO formation is a feasible exothermic reaction with a relatively low energy barrier. The effect of charged and excited states on other possible reactions is also studied. Implications of the obtained results to FOX-7 decomposition in condensed state are discussed

Hydrolysis-precipitation studies of aluminum (III) solutions. I. Titration of acidified aluminum nitrate solutions

NARCIS (Netherlands)

Vermeulen, A.C.; Geus, John W.; Stol, R.J.; Bruyn, P.L. de

Acidified aluminum nitrate solutions were titrated with alkali (NaOH or KOH) over a temperature range of 24°C to 90°C. A homogeneous distribution of added base was achieved by: (i) in situ decomposition of urea (90°C); and (ii) a novel method involving injection through a capillary submerged in the

Effect of surface chemistry, solution pH, and ionic strength on the removal of herbicides diuron and amitrole from water by an activated carbon fiber.

Science.gov (United States)

Fontecha-Cámara, M A; López-Ramón, M V; Alvarez-Merino, M A; Moreno-Castilla, C

2007-01-30

A study was conducted on the effects of carbon surface chemistry, solution pH, and ionic strength on the removal of diuron and amitrole from aqueous solutions by adsorption on an as-received and oxidized activated carbon fiber. Results obtained were explained by the surface characteristics of the adsorbents and the characteristics of the herbicide molecules. Under the experimental conditions used, diuron uptake was much higher than that of amitrole, despite its larger molecular dimensions, due to the lesser water solubility, greater hydrophobicity, and larger dipolar moment of diuron compared with amitrole. Uptake variations associated with differences in carbon surface oxidation, solution pH, and ionic strength were explained by corresponding changes in electrostatic, hydrophobic, and van der Waals interactions.

Exact and numerical solutions of generalized Drinfeld-Sokolov equations

International Nuclear Information System (INIS)

Ugurlu, Yavuz; Kaya, Dogan

2008-01-01

In this Letter, we consider a system of generalized Drinfeld-Sokolov (gDS) equations which models one-dimensional nonlinear wave processes in two-component media. We find some exact solutions of gDS by using tanh function method and we also obtain a numerical solution by using the Adomian's Decomposition Method (ADM)

Visualizing Chemistry: Investigations for Teachers.

Science.gov (United States)

Ealy, Julie B.; Ealy, James L., Jr.

This book contains 101 investigations for chemistry classrooms. Topics include: (1) Physical Properties; (2) Reactions of Some Elements; (3) Reactions Involving Gases; (4) Energy Changes; (5) Solutions and Solubility; (6) Transition Metals and Complex Ions; (7) Kinetics and Equilibrium; (8) Acids and Bases; (9) Oxidation-Reduction; (10)…

Multi-material decomposition of spectral CT images

Science.gov (United States)

Mendonça, Paulo R. S.; Bhotika, Rahul; Maddah, Mahnaz; Thomsen, Brian; Dutta, Sandeep; Licato, Paul E.; Joshi, Mukta C.

2010-04-01

Spectral Computed Tomography (Spectral CT), and in particular fast kVp switching dual-energy computed tomography, is an imaging modality that extends the capabilities of conventional computed tomography (CT). Spectral CT enables the estimation of the full linear attenuation curve of the imaged subject at each voxel in the CT volume, instead of a scalar image in Hounsfield units. Because the space of linear attenuation curves in the energy ranges of medical applications can be accurately described through a two-dimensional manifold, this decomposition procedure would be, in principle, limited to two materials. This paper describes an algorithm that overcomes this limitation, allowing for the estimation of N-tuples of material-decomposed images. The algorithm works by assuming that the mixing of substances and tissue types in the human body has the physicochemical properties of an ideal solution, which yields a model for the density of the imaged material mix. Under this model the mass attenuation curve of each voxel in the image can be estimated, immediately resulting in a material-decomposed image triplet. Decomposition into an arbitrary number of pre-selected materials can be achieved by automatically selecting adequate triplets from an application-specific material library. The decomposition is expressed in terms of the volume fractions of each constituent material in the mix; this provides for a straightforward, physically meaningful interpretation of the data. One important application of this technique is in the digital removal of contrast agent from a dual-energy exam, producing a virtual nonenhanced image, as well as in the quantification of the concentration of contrast observed in a targeted region, thus providing an accurate measure of tissue perfusion.

Decomposition of diesel oil by various microorganisms

Energy Technology Data Exchange (ETDEWEB)

Suess, A; Netzsch-Lehner, A

1969-01-01

Previous experiments demonstrated the decomposition of diesel oil in different soils. In this experiment the decomposition of /sup 14/C-n-Hexadecane labelled diesel oil by special microorganisms was studied. The results were as follows: (1) In the experimental soils the microorganisms Mycoccus ruber, Mycobacterium luteum and Trichoderma hamatum are responsible for the diesel oil decomposition. (2) By adding microorganisms to the soil an increase of the decomposition rate was found only in the beginning of the experiments. (3) Maximum decomposition of diesel oil was reached 2-3 weeks after incubation.

A Benders decomposition approach for a combined heat and power economic dispatch

International Nuclear Information System (INIS)

Abdolmohammadi, Hamid Reza; Kazemi, Ahad

2013-01-01

Highlights: • Benders decomposition algorithm to solve combined heat and power economic dispatch. • Decomposing the CHPED problem into master problem and subproblem. • Considering non-convex heat-power feasible region efficiently. • Solving 4 units and 5 units system with 2 and 3 co-generation units, respectively. • Obtaining better or as well results in terms of objective values. - Abstract: Recently, cogeneration units have played an increasingly important role in the utility industry. Therefore the optimal utilization of multiple combined heat and power (CHP) systems is an important optimization task in power system operation. Unlike power economic dispatch, which has a single equality constraint, two equality constraints must be met in combined heat and power economic dispatch (CHPED) problem. Moreover, in the cogeneration units, the power capacity limits are functions of the unit heat productions and the heat capacity limits are functions of the unit power generations. Thus, CHPED is a complicated optimization problem. In this paper, an algorithm based on Benders decomposition (BD) is proposed to solve the economic dispatch (ED) problem for cogeneration systems. In the proposed method, combined heat and power economic dispatch problem is decomposed into a master problem and subproblem. The subproblem generates the Benders cuts and master problem uses them as a new inequality constraint which is added to the previous constraints. The iterative process will continue until upper and lower bounds of the objective function optimal values are close enough and a converged optimal solution is found. Benders decomposition based approach is able to provide a good framework to consider the non-convex feasible operation regions of cogeneration units efficiently. In this paper, a four-unit system with two cogeneration units and a five-unit system with three cogeneration units are analyzed to exhibit the effectiveness of the proposed approach. In all cases, the

Advantages of Stainless Steel Sieves as Support for Catalytic N2O Decomposition over K-doped Co3O4.

Czech Academy of Sciences Publication Activity Database

Klyushina, A.; Pacultová, K.; Krejčová, S.; Slowik, G.; Jirátová, Květa; Kovanda, F.; Ryczkowski, J.; Obalová, L.

2015-01-01

Roč. 257, Part 1 (2015), s. 2-10 ISSN 0920-5861. [AWPAC2014 - International Symposium on Air & Water Pollution Abatement Catalysis. Krakow, 01.09.2014-05.09.2014] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : N2O catalytic decomposition * Co3O4 * stainless steel support * potassium promoter * TiO2 support Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 4.312, year: 2015

Multilinear operators for higher-order decompositions.

Energy Technology Data Exchange (ETDEWEB)

Kolda, Tamara Gibson

2006-04-01

We propose two new multilinear operators for expressing the matrix compositions that are needed in the Tucker and PARAFAC (CANDECOMP) decompositions. The first operator, which we call the Tucker operator, is shorthand for performing an n-mode matrix multiplication for every mode of a given tensor and can be employed to concisely express the Tucker decomposition. The second operator, which we call the Kruskal operator, is shorthand for the sum of the outer-products of the columns of N matrices and allows a divorce from a matricized representation and a very concise expression of the PARAFAC decomposition. We explore the properties of the Tucker and Kruskal operators independently of the related decompositions. Additionally, we provide a review of the matrix and tensor operations that are frequently used in the context of tensor decompositions.

Some Remarks on Space-Time Decompositions, and Degenerate Metrics, in General Relativity

Science.gov (United States)

Bengtsson, Ingemar

Space-time decomposition of the Hilbert-Palatini action, written in a form which admits degenerate metrics, is considered. Simple numerology shows why D = 3 and 4 are singled out as admitting a simple phase space. The canonical structure of the degenerate sector turns out to be awkward. However, the real degenerate metrics obtained as solutions are the same as those that occur in Ashtekar's formulation of complex general relativity. An exact solution of Ashtekar's equations, with degenerate metric, shows that the manifestly four-dimensional form of the action, and its 3 + 1 form, are not quite equivalent.

Faddeev wave function decomposition using bipolar harmonics

International Nuclear Information System (INIS)

Friar, J.L.; Tomusiak, E.L.; Gibson, B.F.; Payne, G.L.

1981-01-01

The standard partial wave (channel) representation for the Faddeev solution to the Schroedinger equation for the ground state of 3 nucleons is written in terms of functions which couple the interacting pair and spectator angular momenta to give S, P, and D waves. For each such coupling there are three terms, one for each of the three cyclic permutations of the nucleon coordinates. A series of spherical harmonic identities is developed which allows writing the Faddeev solution in terms of a basis set of 5 bipolar harmonics: 1 for S waves; 1 for P waves; and 3 for D waves. The choice of a D-wave basis is largely arbitrary, and specific choices correspond to the decomposition schemes of Derrick and Blatt, Sachs, Gibson and Schiff, and Bolsterli and Jezak. The bipolar harmonic form greatly simplifies applications which utilize the wave function, and we specifically discuss the isoscalar charge (or mass) density and the 3 He Coulomb energy

Features of solid solutions composition in magnesium with yttrium alloys

International Nuclear Information System (INIS)

Drits, M.E.; Rokhlin, L.L.; Tarytina, I.E.

1983-01-01

Additional data on features of yttrium solid solutions composition in magnesium in the course of their decomposition investigation in the case of aging are obtianed. The investigation has been carried out on the base of a binary magnesium-yttrium alloy the composition of which has been close to maximum solubility (at eutectic temperature) and magnesium-yttrium alloys additionally doped with zinc. It is shown that higher yttrium solubility in solid magnesium than it has been expected, issueing from the difference in atomic radii of these metals indicates electron yttrium-magnesium atoms interaction. In oversaturated magnesium-yttrium solid solutions at earlier decomposition stages Mg 3 Cd type ordering is observed. At aging temperatures up to 250 deg C and long exposures corresponding to highest strengthening in oversaturated magnesium yttrium solid solutions a rhombic crystal lattice phase with three symmetric orientations is formed

Decomposition of tetrachloroethylene by ionizing radiation

International Nuclear Information System (INIS)

Hakoda, T.; Hirota, K.; Hashimoto, S.

1998-01-01

Decomposition of tetrachloroethylene and other chloroethenes by ionizing radiation were examined to get information on treatment of industrial off-gas. Model gases, airs containing chloroethenes, were confined in batch reactors and irradiated with electron beam and gamma ray. The G-values of decomposition were larger in the order of tetrachloro- > trichloro- > trans-dichloro- > cis-dichloro- > monochloroethylene in electron beam irradiation and tetrachloro-, trichloro-, trans-dichloro- > cis-dichloro- > monochloroethylene in gamma ray irradiation. For tetrachloro-, trichloro- and trans-dichloroethylene, G-values of decomposition in EB irradiation increased with increase of chlorine atom in a molecule, while those in gamma ray irradiation were almost kept constant. The G-value of decomposition for tetrachloroethylene in EB irradiation was the largest of those for all chloroethenes. In order to examine the effect of the initial concentration on G-value of decomposition, airs containing 300 to 1,800 ppm of tetrachloroethylene were irradiated with electron beam and gamma ray. The G-values of decomposition in both irradiation increased with the initial concentration. Those in electron beam irradiation were two times larger than those in gamma ray irradiation

Closed form solution to a second order boundary value problem and its application in fluid mechanics

International Nuclear Information System (INIS)

Eldabe, N.T.; Elghazy, E.M.; Ebaid, A.

2007-01-01

The Adomian decomposition method is used by many researchers to investigate several scientific models. In this Letter, the modified Adomian decomposition method is applied to construct a closed form solution for a second order boundary value problem with singularity

AUTONOMOUS GAUSSIAN DECOMPOSITION

International Nuclear Information System (INIS)

Lindner, Robert R.; Vera-Ciro, Carlos; Murray, Claire E.; Stanimirović, Snežana; Babler, Brian; Heiles, Carl; Hennebelle, Patrick; Goss, W. M.; Dickey, John

2015-01-01

We present a new algorithm, named Autonomous Gaussian Decomposition (AGD), for automatically decomposing spectra into Gaussian components. AGD uses derivative spectroscopy and machine learning to provide optimized guesses for the number of Gaussian components in the data, and also their locations, widths, and amplitudes. We test AGD and find that it produces results comparable to human-derived solutions on 21 cm absorption spectra from the 21 cm SPectral line Observations of Neutral Gas with the EVLA (21-SPONGE) survey. We use AGD with Monte Carlo methods to derive the H i line completeness as a function of peak optical depth and velocity width for the 21-SPONGE data, and also show that the results of AGD are stable against varying observational noise intensity. The autonomy and computational efficiency of the method over traditional manual Gaussian fits allow for truly unbiased comparisons between observations and simulations, and for the ability to scale up and interpret the very large data volumes from the upcoming Square Kilometer Array and pathfinder telescopes

AUTONOMOUS GAUSSIAN DECOMPOSITION

Energy Technology Data Exchange (ETDEWEB)

Lindner, Robert R.; Vera-Ciro, Carlos; Murray, Claire E.; Stanimirović, Snežana; Babler, Brian [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States); Heiles, Carl [Radio Astronomy Lab, UC Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States); Hennebelle, Patrick [Laboratoire AIM, Paris-Saclay, CEA/IRFU/SAp-CNRS-Université Paris Diderot, F-91191 Gif-sur Yvette Cedex (France); Goss, W. M. [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville, Socorro, NM 87801 (United States); Dickey, John, E-mail: rlindner@astro.wisc.edu [University of Tasmania, School of Maths and Physics, Private Bag 37, Hobart, TAS 7001 (Australia)

2015-04-15

We present a new algorithm, named Autonomous Gaussian Decomposition (AGD), for automatically decomposing spectra into Gaussian components. AGD uses derivative spectroscopy and machine learning to provide optimized guesses for the number of Gaussian components in the data, and also their locations, widths, and amplitudes. We test AGD and find that it produces results comparable to human-derived solutions on 21 cm absorption spectra from the 21 cm SPectral line Observations of Neutral Gas with the EVLA (21-SPONGE) survey. We use AGD with Monte Carlo methods to derive the H i line completeness as a function of peak optical depth and velocity width for the 21-SPONGE data, and also show that the results of AGD are stable against varying observational noise intensity. The autonomy and computational efficiency of the method over traditional manual Gaussian fits allow for truly unbiased comparisons between observations and simulations, and for the ability to scale up and interpret the very large data volumes from the upcoming Square Kilometer Array and pathfinder telescopes.

Exact and numerical solutions of generalized Drinfeld-Sokolov equations

Energy Technology Data Exchange (ETDEWEB)

Ugurlu, Yavuz [Firat University, Department of Mathematics, 23119 Elazig (Turkey); Kaya, Dogan [Firat University, Department of Mathematics, 23119 Elazig (Turkey)], E-mail: dkaya36@yahoo.com

2008-04-14

In this Letter, we consider a system of generalized Drinfeld-Sokolov (gDS) equations which models one-dimensional nonlinear wave processes in two-component media. We find some exact solutions of gDS by using tanh function method and we also obtain a numerical solution by using the Adomian's Decomposition Method (ADM)

Analysis of spinodal decomposition in Fe-32 and 40 at.% Cr alloys using phase field method based on linear and nonlinear Cahn-Hilliard equations

Directory of Open Access Journals (Sweden)

Orlando Soriano-Vargas

2016-12-01

Full Text Available Spinodal decomposition was studied during aging of Fe-Cr alloys by means of the numerical solution of the linear and nonlinear Cahn-Hilliard differential partial equations using the explicit finite difference method. Results of the numerical simulation permitted to describe appropriately the mechanism, morphology and kinetics of phase decomposition during the isothermal aging of these alloys. The growth kinetics of phase decomposition was observed to occur very slowly during the early stages of aging and it increased considerably as the aging progressed. The nonlinear equation was observed to be more suitable for describing the early stages of spinodal decomposition than the linear one.

Structure-Activity Relationship in the N2O Decomposition over Ni-(Mg)-Al and Ni-(Mg)-Mn Mixed Oxides Prepared from Hydrotalcite-like Precursors

Czech Academy of Sciences Publication Activity Database

Obalová, L.; Jirátová, Květa; Kovanda, F.; Valášková, M.; Balabánová, Jana; Pacultová, K.

2006-01-01

Roč. 248, 1-2 (2006), s. 210-219 ISSN 1381-1169 R&D Projects: GA ČR(CZ) GA106/05/0366; GA ČR(CZ) GA104/04/2116 Institutional research plan: CEZ:AV0Z40720504 Keywords : N2O decomposition * mixed oxide catalyst * layered double hydroxides Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.511, year: 2006

The aqueous chemistry of oxides

CERN Document Server

Bunker, Bruce C

2016-01-01

The Aqueous Chemistry of Oxides is a comprehensive reference volume and special topics textbook that explores all of the major chemical reactions that take place between oxides and aqueous solutions. The book highlights the enormous impact that oxide-water reactions have in advanced technologies, materials science, geochemistry, and environmental science.

Radioanalytical Chemistry for Automated Nuclear Waste Process Monitoring

International Nuclear Information System (INIS)

Egorov, Oleg B.; Grate, Jay W.; DeVol, Timothy A.

2004-01-01

This research program is directed toward rapid, sensitive, and selective determination of beta and alpha-emitting radionuclides such as 99Tc, 90Sr, and trans-uranium (TRU) elements in low activity waste (LAW) processing streams. The overall technical approach is based on automated radiochemical measurement principles, which entails integration of sample treatment and separation chemistries and radiometric detection within a single functional analytical instrument. Nuclear waste process streams are particularly challenging for rapid analytical methods due to the complex, high-ionic-strength, caustic brine sample matrix, the presence of interfering radionuclides, and the variable and uncertain speciation of the radionuclides of interest. As a result, matrix modification, speciation control, and separation chemistries are required for use in automated process analyzers. Significant knowledge gaps exist relative to the design of chemistries for such analyzers so that radionuclides can be quantitatively and rapidly separated and analyzed in solutions derived from low-activity waste processing operations. This research is addressing these knowledge gaps in the area of separation science, nuclear detection, and analytical chemistry and instrumentation. The outcome of these investigations will be the knowledge necessary to choose appropriate chemistries for sample matrix modification and analyte speciation control and chemistries for rapid and selective separation and preconcentration of target radionuclides from complex sample matrices. In addition, new approaches for quantification of alpha emitters in solution using solid-state diode detectors, as well as improved instrumentation and signal processing techniques for use with solid-state and scintillation detectors, will be developed. New knowledge of the performance of separation materials, matrix modification and speciation control chemistries, instrument configurations, and quantitative analytical approaches will

Thermal decomposition of γ-irradiated lead nitrate

International Nuclear Information System (INIS)

Nair, S.M.K.; Kumar, T.S.S.

1990-01-01

The thermal decomposition of unirradiated and γ-irradiated lead nitrate was studied by the gas evolution method. The decomposition proceeds through initial gas evolution, a short induction period, an acceleratory stage and a decay stage. The acceleratory and decay stages follow the Avrami-Erofeev equation. Irradiation enhances the decomposition but does not affect the shape of the decomposition curve. (author) 10 refs.; 7 figs.; 2 tabs

Effects of atmospheric deposition nitrogen flux and its composition on soil solution chemistry from a red soil farmland, southeast China.

Science.gov (United States)

Cui, Jian; Zhou, Jing; Peng, Ying; Chan, Andrew; Mao, Jingdong

2015-12-01

A detailed study on the solution chemistry of red soil in South China is presented. Data are collected from two simulated column-leaching experiments with an improved setup to evaluate the effects of atmospheric N deposition (ADN) composition and ADN flux on agricultural soil acidification using a (15)N tracer technique and an in situ soil solution sampler. The results show that solution pH values decline regardless of the increase of the NH4(+)/NO3(-) ratio in the ADN composition or ADN flux, while exchangeable Al(3+), Ca(2+), Mg(2+), and K(+) concentrations increase at different soil depths (20, 40, and 60 cm). Compared with the control, ADN (60 kg per ha per year N, NH4(+)/NO3(-) ratio of 2 : 1) decreases solution pH values, increases solution concentrations of NO3(-)-N, Al(3+), Ca(2+) and Mg(2+) at the middle and lower soil depths, and promotes their removal. NH4(+)-N was not detected in red soil solutions of all the three soil layers, which might be attributed to effects of nitrification, absorption and fixation in farmland red soil. Some of the NO3(-)-N concentrations at 40-60 cm soil depth exceed the safe drinking level of 10 mg L(-1), especially when the ADN flux is beyond 60 kg ha(-1) N. These features are critical for understanding the ADN agro-ecological effects, and for future assessment of ecological critical loads of ADN in red soil farmlands.

The solution of linear and nonlinear systems of Volterra functional equations using Adomian-Pade technique

International Nuclear Information System (INIS)

Dehghan, Mehdi; Shakourifar, Mohammad; Hamidi, Asgar

2009-01-01

The purpose of this study is to implement Adomian-Pade (Modified Adomian-Pade) technique, which is a combination of Adomian decomposition method (Modified Adomian decomposition method) and Pade approximation, for solving linear and nonlinear systems of Volterra functional equations. The results obtained by using Adomian-Pade (Modified Adomian-Pade) technique, are compared to those obtained by using Adomian decomposition method (Modified Adomian decomposition method) alone. The numerical results, demonstrate that ADM-PADE (MADM-PADE) technique, gives the approximate solution with faster convergence rate and higher accuracy than using the standard ADM (MADM).

Decomposing Nekrasov decomposition

International Nuclear Information System (INIS)

Morozov, A.; Zenkevich, Y.

2016-01-01

AGT relations imply that the four-point conformal block admits a decomposition into a sum over pairs of Young diagrams of essentially rational Nekrasov functions — this is immediately seen when conformal block is represented in the form of a matrix model. However, the q-deformation of the same block has a deeper decomposition — into a sum over a quadruple of Young diagrams of a product of four topological vertices. We analyze the interplay between these two decompositions, their properties and their generalization to multi-point conformal blocks. In the latter case we explain how Dotsenko-Fateev all-with-all (star) pair “interaction” is reduced to the quiver model nearest-neighbor (chain) one. We give new identities for q-Selberg averages of pairs of generalized Macdonald polynomials. We also translate the slicing invariance of refined topological strings into the language of conformal blocks and interpret it as abelianization of generalized Macdonald polynomials.

Decomposing Nekrasov decomposition

Energy Technology Data Exchange (ETDEWEB)

Morozov, A. [ITEP,25 Bolshaya Cheremushkinskaya, Moscow, 117218 (Russian Federation); Institute for Information Transmission Problems,19-1 Bolshoy Karetniy, Moscow, 127051 (Russian Federation); National Research Nuclear University MEPhI,31 Kashirskoe highway, Moscow, 115409 (Russian Federation); Zenkevich, Y. [ITEP,25 Bolshaya Cheremushkinskaya, Moscow, 117218 (Russian Federation); National Research Nuclear University MEPhI,31 Kashirskoe highway, Moscow, 115409 (Russian Federation); Institute for Nuclear Research of Russian Academy of Sciences,6a Prospekt 60-letiya Oktyabrya, Moscow, 117312 (Russian Federation)

2016-02-16

AGT relations imply that the four-point conformal block admits a decomposition into a sum over pairs of Young diagrams of essentially rational Nekrasov functions — this is immediately seen when conformal block is represented in the form of a matrix model. However, the q-deformation of the same block has a deeper decomposition — into a sum over a quadruple of Young diagrams of a product of four topological vertices. We analyze the interplay between these two decompositions, their properties and their generalization to multi-point conformal blocks. In the latter case we explain how Dotsenko-Fateev all-with-all (star) pair “interaction” is reduced to the quiver model nearest-neighbor (chain) one. We give new identities for q-Selberg averages of pairs of generalized Macdonald polynomials. We also translate the slicing invariance of refined topological strings into the language of conformal blocks and interpret it as abelianization of generalized Macdonald polynomials.

Pinning of phase separation of aqueous solution of hydroxypropylmethylcellulose by gelation

Science.gov (United States)

Kita, Rio; Kaku, Takeshi; Kubota, Kenji; Dobashi, Toshiaki

1999-08-01

Opalescence of the aqueous solution of hydroxypropylmethylcellulose (HPMC) induced by heating has been studied in terms of the phase diagram and the phase separation dynamics. The cloud point curve and the sol-to-gel transition curve intersected with each other at about 55 °C. Just above the cloud-point curve at which the spinodal curve has its minimum, a ring-like scattering pattern appeared corresponding to the spinodal decomposition. Temporal growth of the scattering function in the course of phase separation was studied by a time-resolved light scattering technique. The gelation pinned the phase separation (spinodal decomposition) of the aqueous HPMC solution.

Freeman-Durden Decomposition with Oriented Dihedral Scattering

Directory of Open Access Journals (Sweden)

Yan Jian

2014-10-01

Full Text Available In this paper, when the azimuth direction of polarimetric Synthetic Aperature Radars (SAR differs from the planting direction of crops, the double bounce of the incident electromagnetic waves from the terrain surface to the growing crops is investigated and compared with the normal double bounce. Oriented dihedral scattering model is developed to explain the investigated double bounce and is introduced into the Freeman-Durden decomposition. The decomposition algorithm corresponding to the improved decomposition is then proposed. The airborne polarimetric SAR data for agricultural land covering two flight tracks are chosen to validate the algorithm; the decomposition results show that for agricultural vegetated land, the improved Freeman-Durden decomposition has the advantage of increasing the decomposition coherency among the polarimetric SAR data along the different flight tracks.

Clean thermal decomposition of tertiary-alkyl metal thiolates to metal sulfides: environmentally-benign, non-polar inks for solution-processed chalcopyrite solar cells

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Heo, Jungwoo; Kim, Gi-Hwan; Jeong, Jaeki; Yoon, Yung Jin; Seo, Jung Hwa; Walker, Bright; Kim, Jin Young

2016-11-01

We report the preparation of Cu2S, In2S3, CuInS2 and Cu(In,Ga)S2 semiconducting films via the spin coating and annealing of soluble tertiary-alkyl thiolate complexes. The thiolate compounds are readily prepared via the reaction of metal bases and tertiary-alkyl thiols. The thiolate complexes are soluble in common organic solvents and can be solution processed by spin coating to yield thin films. Upon thermal annealing in the range of 200-400 °C, the tertiary-alkyl thiolates decompose cleanly to yield volatile dialkyl sulfides and metal sulfide films which are free of organic residue. Analysis of the reaction byproducts strongly suggests that the decomposition proceeds via an SN1 mechanism. The composition of the films can be controlled by adjusting the amount of each metal thiolate used in the precursor solution yielding bandgaps in the range of 1.2 to 3.3 eV. The films form functioning p-n junctions when deposited in contact with CdS films prepared by the same method. Functioning solar cells are observed when such p-n junctions are prepared on transparent conducting substrates and finished by depositing electrodes with appropriate work functions. This method enables the fabrication of metal chalcogenide films on a large scale via a simple and chemically clear process.

Molecular C dynamics downstream: the biochemical decomposition sequence and its impact on soil organic matter structure and function.

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Grandy, A Stuart; Neff, Jason C

2008-10-15

Advances in spectroscopic and other chemical methods have greatly enhanced our ability to characterize soil organic matter chemistry. As a result, the molecular characteristics of soil C are now known for a range of ecosystems, soil types, and management intensities. Placing this knowledge into a broader ecological and management context is difficult, however, and remains one of the fundamental challenges of soil organic matter research. Here we present a conceptual model of molecular soil C dynamics to stimulate inter-disciplinary research into the ecological implications of molecular C turnover and its management- and process-level controls. Our model describes three properties of soil C dynamics: 1) soil size fractions have unique molecular patterns that reflect varying degrees of biological and physical control over decomposition; 2) there is a common decomposition sequence independent of plant inputs or other ecosystem properties; and 3) molecular decomposition sequences, although consistent, are not uniform and can be altered by processes that accelerate or slow the microbial transformation of specific molecules. The consequences of this model include several key points. First, lignin presents a constraint to decomposition of plant litter and particulate C (>53 microm) but exerts little influence on more stable mineral-associated soil fractions stabilized onto mineral fractions has a distinct composition related more to microbially processed organic matter than to plant-related compounds. Third, disturbances, such as N fertilization and tillage, which alter decomposition rates, can have "downstream effects"; that is, a disturbance that directly alters the molecular dynamics of particulate C may have a series of indirect effects on C stabilization in silt and clay fractions.

Danburite decomposition by hydrochloric acid

International Nuclear Information System (INIS)

Mamatov, E.D.; Ashurov, N.A.; Mirsaidov, U.

2011-01-01

Present article is devoted to decomposition of danburite of Ak-Arkhar Deposit of Tajikistan by hydrochloric acid. The interaction of boron containing ores of Ak-Arkhar Deposit of Tajikistan with mineral acids, including hydrochloric acid was studied. The optimal conditions of extraction of valuable components from danburite composition were determined. The chemical composition of danburite of Ak-Arkhar Deposit was determined as well. The kinetics of decomposition of calcined danburite by hydrochloric acid was studied. The apparent activation energy of the process of danburite decomposition by hydrochloric acid was calculated.

Recollections of the maturation of radiation chemistry

International Nuclear Information System (INIS)

Dainton, F.S.

1989-01-01

In this paper the background to the study of the identification of primary species in irradiated aqueous solutions is presented. Theoretical aspects are discussed. The radiation chemistry of glossy and crystalline solids is briefly discussed. (UK)

A Comprehensive General Chemistry Demonstration

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Sweeder, Ryan D.; Jeffery, Kathleen A.

2013-01-01

This article describes the use of a comprehensive demonstration suitable for a high school or first-year undergraduate introductory chemistry class. The demonstration involves placing a burning candle in a container adjacent to a beaker containing a basic solution with indicator. After adding a lid, the candle will extinguish and the produced…

Liquid flow along a solid surface reversibly alters interfacial chemistry.

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Lis, Dan; Backus, Ellen H G; Hunger, Johannes; Parekh, Sapun H; Bonn, Mischa

2014-06-06

In nature, aqueous solutions often move collectively along solid surfaces (for example, raindrops falling on the ground and rivers flowing through riverbeds). However, the influence of such motion on water-surface interfacial chemistry is unclear. In this work, we combine surface-specific sum frequency generation spectroscopy and microfluidics to show that at immersed calcium fluoride and fused silica surfaces, flow leads to a reversible modification of the surface charge and subsequent realignment of the interfacial water molecules. Obtaining equivalent effects under static conditions requires a substantial change in bulk solution pH (up to 2 pH units), demonstrating the coupling between flow and chemistry. These marked flow-induced variations in interfacial chemistry should substantially affect our understanding and modeling of chemical processes at immersed surfaces. Copyright © 2014, American Association for the Advancement of Science.

LMDI decomposition approach: A guide for implementation

International Nuclear Information System (INIS)

Ang, B.W.

2015-01-01

Since it was first used by researchers to analyze industrial electricity consumption in the early 1980s, index decomposition analysis (IDA) has been widely adopted in energy and emission studies. Lately its use as the analytical component of accounting frameworks for tracking economy-wide energy efficiency trends has attracted considerable attention and interest among policy makers. The last comprehensive literature review of IDA was reported in 2000 which is some years back. After giving an update and presenting the key trends in the last 15 years, this study focuses on the implementation issues of the logarithmic mean Divisia index (LMDI) decomposition methods in view of their dominance in IDA in recent years. Eight LMDI models are presented and their origin, decomposition formulae, and strengths and weaknesses are summarized. Guidelines on the choice among these models are provided to assist users in implementation. - Highlights: • Guidelines for implementing LMDI decomposition approach are provided. • Eight LMDI decomposition models are summarized and compared. • The development of the LMDI decomposition approach is presented. • The latest developments of index decomposition analysis are briefly reviewed.

Use of high energy radiation in decomposition and removal of organic water pollutants

International Nuclear Information System (INIS)

Toelgyessy, P.

1990-01-01

The present review deals with the radiation chemistry of dilute aqueous solutions of organic substances emphasizing the possibility of use of high energy radiation in waste water treatment. Effects of radiation on biodegradability, toxicity to water organisms and changes in molecules of solutes showing resistance to biochemical degradation and toxicity to water organisms are discussed. (author) 31 refs

Unstructured characteristic method embedded with variational nodal method using domain decomposition techniques

Energy Technology Data Exchange (ETDEWEB)

Girardi, E.; Ruggieri, J.M. [CEA Cadarache (DER/SPRC/LEPH), 13 - Saint-Paul-lez-Durance (France). Dept. d' Etudes des Reacteurs; Santandrea, S. [CEA Saclay, Dept. Modelisation de Systemes et Structures DM2S/SERMA/LENR, 91 - Gif sur Yvette (France)

2005-07-01

This paper describes a recently-developed extension of our 'Multi-methods,multi-domains' (MM-MD) method for the solution of the multigroup transport equation. Based on a domain decomposition technique, our approach allows us to treat the one-group equation by cooperatively employing several numerical methods together. In this work, we describe the coupling between the Method of Characteristics (integro-differential equation, unstructured meshes) with the Variational Nodal Method (even parity equation, cartesian meshes). Then, the coupling method is applied to the benchmark model of the Phebus experimental facility (Cea Cadarache). Our domain decomposition method give us the capability to employ a very fine mesh in describing a particular fuel bundle with an appropriate numerical method (MOC), while using a much large mesh size in the rest of the core, in conjunction with a coarse-mesh method (VNM). This application shows the benefits of our MM-MD approach, in terms of accuracy and computing time: the domain decomposition method allows us to reduce the Cpu time, while preserving a good accuracy of the neutronic indicators: reactivity, core-to-bundle power coupling coefficient and flux error. (authors)

Unstructured characteristic method embedded with variational nodal method using domain decomposition techniques

International Nuclear Information System (INIS)

Girardi, E.; Ruggieri, J.M.

2005-01-01

This paper describes a recently-developed extension of our 'Multi-methods,multi-domains' (MM-MD) method for the solution of the multigroup transport equation. Based on a domain decomposition technique, our approach allows us to treat the one-group equation by cooperatively employing several numerical methods together. In this work, we describe the coupling between the Method of Characteristics (integro-differential equation, unstructured meshes) with the Variational Nodal Method (even parity equation, cartesian meshes). Then, the coupling method is applied to the benchmark model of the Phebus experimental facility (Cea Cadarache). Our domain decomposition method give us the capability to employ a very fine mesh in describing a particular fuel bundle with an appropriate numerical method (MOC), while using a much large mesh size in the rest of the core, in conjunction with a coarse-mesh method (VNM). This application shows the benefits of our MM-MD approach, in terms of accuracy and computing time: the domain decomposition method allows us to reduce the Cpu time, while preserving a good accuracy of the neutronic indicators: reactivity, core-to-bundle power coupling coefficient and flux error. (authors)

Basis adaptation and domain decomposition for steady-state partial differential equations with random coefficients

Energy Technology Data Exchange (ETDEWEB)

Tipireddy, R.; Stinis, P.; Tartakovsky, A. M.

2017-12-01

We present a novel approach for solving steady-state stochastic partial differential equations (PDEs) with high-dimensional random parameter space. The proposed approach combines spatial domain decomposition with basis adaptation for each subdomain. The basis adaptation is used to address the curse of dimensionality by constructing an accurate low-dimensional representation of the stochastic PDE solution (probability density function and/or its leading statistical moments) in each subdomain. Restricting the basis adaptation to a specific subdomain affords finding a locally accurate solution. Then, the solutions from all of the subdomains are stitched together to provide a global solution. We support our construction with numerical experiments for a steady-state diffusion equation with a random spatially dependent coefficient. Our results show that highly accurate global solutions can be obtained with significantly reduced computational costs.

Effects of elevated CO2 on litter chemistry and subsequent invertebrate detritivore feeding responses.