WorldWideScience

Sample records for formation chemical reactivity

  1. Chemical Reactivity Test (CRT)

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-13

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

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

    Directory of Open Access Journals (Sweden)

    Chin Lin eWong

    2016-03-01

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

  3. Distributions of chemical reactive compounds: Effects of different emissions on the formation of ozone

    International Nuclear Information System (INIS)

    Vogel, H.; Fiedler, F.; Vogel, B.

    1993-01-01

    By using the model system the concentration distributions are simulated in accordance to the conditions of the beginning of August 1990. For this situation the influence of the emissions outside of the modelling region and the influence of biogenic emissions of hydrocarbons on the ozone formation in the modeling region was investigated. Comparing the results of the different simulations one can find differences concerning the netto production of the oxidants. For the first simulation day the emissions outside of the modeling region show a strong influence on the ozone production. Integrated over the whole boundary layer the ozone mass increases by 24%. If additionally the biogenic emissions are taken into account one can find only an increase of 7% for the 1. day. In contrast at the 2. simulation day the ozone production increases by 81%. For this case the ozone concentration near the ground is up to 20 ppb higher than for the model rund without biogenic emissions. (orig./BBR) [de

  4. Hot spot formation and chemical reaction initiation in shocked HMX crystals with nanovoids: a large-scale reactive molecular dynamics study.

    Science.gov (United States)

    Zhou, Tingting; Lou, Jianfeng; Zhang, Yangeng; Song, Huajie; Huang, Fenglei

    2016-07-14

    We report million-atom reactive molecular dynamic simulations of shock initiation of β-cyclotetramethylene tetranitramine (β-HMX) single crystals containing nanometer-scale spherical voids. Shock induced void collapse and subsequent hot spot formation as well as chemical reaction initiation are observed which depend on the void size and impact strength. For an impact velocity of 1 km s(-1) and a void radius of 4 nm, the void collapse process includes three stages; the dominant mechanism is the convergence of upstream molecules toward the centerline and the downstream surface of the void forming flowing molecules. Hot spot formation also undergoes three stages, and the principal mechanism is kinetic energy transforming to thermal energy due to the collision of flowing molecules on the downstream surface. The high temperature of the hot spot initiates a local chemical reaction, and the breakage of the N-NO2 bond plays the key role in the initial reaction mechanism. The impact strength and void size have noticeable effects on the shock dynamical process, resulting in a variation of the predominant mechanisms leading to void collapse and hot spot formation. Larger voids or stronger shocks result in more intense hot spots and, thus, more violent chemical reactions, promoting more reaction channels and generating more reaction products in a shorter duration. The reaction products are mainly concentrated in the developed hot spot, indicating that the chemical reactivity of the hmx crystal is greatly enhanced by void collapse. The detailed information derived from this study can aid a thorough understanding of the role of void collapse in hot spot formation and the chemical reaction initiation of explosives.

  5. Reactive chemicals and process hazards

    International Nuclear Information System (INIS)

    Surianarayanan, M.

    2016-01-01

    Exothermic chemical reactions are often accompanied by significant heat release, and therefore, need a thorough investigation before they are taken to a plant scale. Sudden thermal energy releases from exothermic decompositions and runaway reactions have contributed to serious fire and explosions in several chemical process plants. Similarly, thermal runaway had also occurred in storage and transportation of reactive chemicals. The secondary events of thermal runaway reactions can be rupture of process vessel, toxic spills and release of explosive vapor clouds or combination of these also. The explosion hazards are governed by the system thermodynamics and kinetics of the thermal process. Theoretical prediction of limiting temperature is difficult due to process complexities. Further, the kinetic data obtained through classical techniques, at conditions far away from runaway situation, is often not valid for assessing the runaway behavior of exothermic processes. The main focus of this lecture is to discuss the causes and several contributing factors for thermal runaway and instability and present analyses of the methodologies of the new instrumental techniques for assessing the thermal hazards of reactive chemicals during processing, storage and transportation. (author)

  6. Metallorganic routes to nanoscale iron and titanium oxide particles encapsulated in mesoporous alumina: formation, physical properties, and chemical reactivity.

    Science.gov (United States)

    Schneider, J J; Czap, N; Hagen, J; Engstler, J; Ensling, J; Gütlich, P; Reinoehl, U; Bertagnolli, H; Luis, F; de Jongh, L J; Wark, M; Grubert, G; Hornyak, G L; Zanoni, R

    2000-12-01

    towards formation of carbon nanotubes by a CVD process. Depending on the reaction conditions, the formation of smaller carbon nanotubes inside the interior of larger carbon nanotubes within the alumina pores can be achieved. This behavior can be understood by means of selectively turning on and off the iron catalyst by adjusting the flow rate of the gaseous carbon precursor in the CVD process.

  7. Steam-chemical reactivity for irradiated beryllium

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-01-01

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

  8. Chemical reactivity of cation-exchanged zeolites

    OpenAIRE

    Pidko, E.A.

    2008-01-01

    Zeolites modified with metal cations have been extensively studied during the last two decades because of their wide application in different technologically important fields such as catalysis, adsorption and gas separation. Contrary to the well-understood mechanisms of chemical reactions catalyzed by Brønsted acid sites in the hydrogen forms of zeolites, the nature of chemical reactivity, and related, the structure of the metal-containing ions in cation-exchanged zeolites remains the subject...

  9. Rock fracture processes in chemically reactive environments

    Science.gov (United States)

    Eichhubl, P.

    2015-12-01

    Rock fracture is traditionally viewed as a brittle process involving damage nucleation and growth in a zone ahead of a larger fracture, resulting in fracture propagation once a threshold loading stress is exceeded. It is now increasingly recognized that coupled chemical-mechanical processes influence fracture growth in wide range of subsurface conditions that include igneous, metamorphic, and geothermal systems, and diagenetically reactive sedimentary systems with possible applications to hydrocarbon extraction and CO2 sequestration. Fracture processes aided or driven by chemical change can affect the onset of fracture, fracture shape and branching characteristics, and fracture network geometry, thus influencing mechanical strength and flow properties of rock systems. We are investigating two fundamental modes of chemical-mechanical interactions associated with fracture growth: 1. Fracture propagation may be aided by chemical dissolution or hydration reactions at the fracture tip allowing fracture propagation under subcritical stress loading conditions. We are evaluating effects of environmental conditions on critical (fracture toughness KIc) and subcritical (subcritical index) fracture properties using double torsion fracture mechanics tests on shale and sandstone. Depending on rock composition, the presence of reactive aqueous fluids can increase or decrease KIc and/or subcritical index. 2. Fracture may be concurrent with distributed dissolution-precipitation reactions in the hostrock beyond the immediate vicinity of the fracture tip. Reconstructing the fracture opening history recorded in crack-seal fracture cement of deeply buried sandstone we find that fracture length growth and fracture opening can be decoupled, with a phase of initial length growth followed by a phase of dominant fracture opening. This suggests that mechanical crack-tip failure processes, possibly aided by chemical crack-tip weakening, and distributed solution-precipitation creep in the

  10. Phase equilibria in chemical reactive fluid mixtures

    International Nuclear Information System (INIS)

    Maurer, Gerd

    2011-01-01

    Downstream processing is a major part of nearly all processes in the chemical industries. Most separation processes in the chemical (and related) industries for fluid mixtures are based on phase equilibrium phenomena. The majority of separation processes can be modelled assuming that chemical reactions are of no (or very minor) importance, i.e., assuming that the overall speciation remains unchanged during a separation process. However, there are also a large number of industrially important processes where the thermodynamic properties are influenced by chemical reactions. The phase equilibrium of chemical reactive mixtures has been a major research area of the author's group over nearly 40 years. In this contribution, three examples from that research are discussed. The first example deals with the vapour phase dimerisation of carboxylic acids and its consequences on phase equilibrium phenomena and phase equilibrium predictions. The second example deals with the solubility of sour gases (e.g., carbon dioxide and sulfur dioxide) in aqueous solutions of ammonia. That topic has been of interest for many years, e.g., in relation with the gasification and liquefaction of coal and, more recently, with the removal of carbon dioxide from flue gas in the 'chilled ammonia process'. The third example deals with phase equilibrium phenomena in aqueous solutions of polyelectrolytes. It deals with the phenomenon of 'counter ion condensation' and methods to model the Gibbs free energy of such solutions.

  11. On mechanisms of reactive metabolite formation from drugs.

    Science.gov (United States)

    Claesson, Alf; Spjuth, Ola

    2013-04-01

    Idiosyncratic adverse drug reactions (IADRs) cause a broad range of clinically severe conditions of which drug induced liver injury (DILI) in particular is one of the most frequent causes of safety-related drug withdrawals. The underlying cause is almost invariably formation of reactive metabolites (RM) which by attacking macromolecules induc eorgan injuries. Attempts are being made in the pharmaceutical industry to lower the risk of selecting unfit compounds as clinical candidates. Approaches vary but do not seem to be overly successful at the initial design/synthesis stage. We review here the most frequent categories of mechanisms for RM formation and propose that many cases of RMs encountered within early ADME screening can be foreseen by applying chemical and metabolic knowledge. We also mention a web tool, SpotRM, which can be used for efficient look-up and learning about drugs that have recognized IADRs likely caused by RM formation.

  12. An autonomous organic reaction search engine for chemical reactivity

    Science.gov (United States)

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

    2017-06-01

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

  13. Chemical Reactivity as Described by Quantum Chemical Methods

    Directory of Open Access Journals (Sweden)

    F. De Proft

    2002-04-01

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

  14. Chemical reactivities of some interstellar molecules

    Energy Technology Data Exchange (ETDEWEB)

    Chadha, M S

    1980-01-01

    Work in the area of chemical evolution during the last 25 years has revealed the formation of a large number of biologically important molecules produced from simple starting materials under relatively simple experimental conditions. Much of this work has resulted from studies under atmospheres simulating that of the primitive earth or other planets. During the last decade, progress has also been made in the identification of chemical constituents of interstellar medium. A number of these molecules are the same as those identified in laboratory experiments. Even though the conditions of the laboratory experiments are vastly different from those of the cool, low-density interstellar medium, some of the similarities in composition are too obvious to go unnoticed. The present paper highlights some of the similarities in the composition of prebiotic molecules and those discovered in the interstellar medium. Also the chemical reactions which some of the common molecules e.g., NH3, HCN, H2CO, HC(triple bond)-C-CN etc. can undergo are surveyed.

  15. Reactivity of Dual-Use Decontaminants with Chemical Warfare Agents

    Science.gov (United States)

    2016-07-01

    REACTIVITY OF DUAL-USE DECONTAMINANTS WITH CHEMICAL WARFARE AGENTS ECBC-TR-1384... Decontaminants with Chemical Warfare Agents 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Willis, Matthew P...extraction) of chemical warfare agents from materials. 15. SUBJECT TERMS GD HD Decontamination Hazard mitigation VX Chemical warfare agent Liquid-phase

  16. Nondestructive Reactivation of Chemical Protective Garments

    National Research Council Canada - National Science Library

    Chang, Kuo

    1995-01-01

    .... Complete reactivation was achieved when the aqueous/ i-propanol/ iodine displacement method of Manes, which removed all but pure hydrocarbon oil soils from the current overgarment Type III foam...

  17. Investigations of Reactive Carbohydrates in Glycosidic Bond Formation and Degradation

    DEFF Research Database (Denmark)

    Heuckendorff, Mads

    The overall objective of the research described in this thesis was to explore the field of glycosidic bond formation and degradation. In more detail, the objective was to do further research in the field of highly reactive glycosyl donors. New ways of making highly reactive donors were explored...

  18. Fluxes of chemically reactive species inferred from mean concentration measurements

    NARCIS (Netherlands)

    Galmarini, S.; Vilà-Guerau De Arellano, J.; Duyzer, J.H.

    1997-01-01

    A method is presented for the calculation of the fluxes of chemically reactive species on the basis of routine measurements of meteorological variables and chemical species. The method takes explicity into account the influence of chemical reactions on the fluxes of the species. As a demonstration

  19. Formation of reactive oxygen species in rat epithelial cells upon ...

    Indian Academy of Sciences (India)

    In our study, we investigated the influence of fly ash on the promotion of early inflammatory reactions like the formation of reactive oxygen species (ROS) in rat lung epithelial cells (RLE-6TN). Furthermore, we determined the formation of nitric oxide (NO). The cells show a clear dose-response relationship concerning the ...

  20. Chemical reactor modeling multiphase reactive flows

    CERN Document Server

    Jakobsen, Hugo A

    2014-01-01

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

  1. Formation and Reactivity of Biogenic Iron Minerals

    International Nuclear Information System (INIS)

    Ferris, F. Grant

    2002-01-01

    Dissimilatory iron-reducing bacteria (DIRB) play an important role in regulating the aqueous geochemistry of iron and other metals in anaerobic, non-sulfidogenic groundwater environments; however, little work has directly assessed the cell surface electrochemistry of DIRB, or the nature of the interfacial environment around individual cells. The electrochemical properties of particulate solids are often inferred from titrations in which net surface charge is determined, assuming electroneutrality, as the difference between known added amounts of acid and base and measured proton concentration. The resultant titration curve can then be fit to a speciation model for the system to determine pKa values and site densities of reactive surface sites. Moreover, with the development of non-contact electrostatic force microscopy (EFM), it is now possible to directly inspect and quantify charge development on surfaces. A combination of acid-base titrations and EFM are being used to assess the electrochemical surface properties of the groundwater DIRB, Shewanella putrefaciens. The pKa spectra and EFM data show together that a high degree of electrochemical heterogeneity exists within the cell wall and at the cell surface of S. putrefaciens. Recognition of variations in the nature and spatial distribution of reactive sites that contribute to charge development on these bacteria implies further that the cell surface of these Fe(III)-reducing bacteria functions as a highly differentiated interfacial system capable of supporting multiple intermolecular interactions with both solutes and solids. These include surface complexation reactions involving dissolved metals, as well as adherence to mineral substrates such as hydrous ferric oxide through longer-range electrostatic interactions, and surface precipitation of secondary reduced-iron minerals

  2. Communication: Enhanced chemical reactivity of graphene on a Ni(111) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosetti, Alberto; Silvestrelli, Pier Luigi [Dipartimento di Fisica e Astronomia, Università di Padova, via Marzolo 8, I–35131 Padova, Italy and DEMOCRITOS National Simulation Center of the Italian Istituto Officina dei Materiali (IOM) of the Italian National Research Council (CNR), Trieste (Italy)

    2016-03-21

    Due to the unique combination of structural, mechanical, and transport properties, graphene has emerged as an exceptional candidate for catalysis applications. The low chemical reactivity caused by sp{sup 2} hybridization and strongly delocalized π electrons, however, represents a main challenge for straightforward use of graphene in its pristine, free-standing form. Following recent experimental indications, we show that due to charge hybridization, a Ni(111) substrate can enhance the chemical reactivity of graphene, as exemplified by the interaction with the CO molecule. While CO only physisorbs on free-standing graphene, chemisorption of CO involving formation of ethylene dione complexes is predicted in Ni(111)-graphene. Higher chemical reactivity is also suggested in the case of oxidized graphene, opening the way to a simple and efficient control of graphene chemical properties, devoid of complex defect patterning or active metallic structures deposition.

  3. Communication: Enhanced chemical reactivity of graphene on a Ni(111) substrate

    International Nuclear Information System (INIS)

    Ambrosetti, Alberto; Silvestrelli, Pier Luigi

    2016-01-01

    Due to the unique combination of structural, mechanical, and transport properties, graphene has emerged as an exceptional candidate for catalysis applications. The low chemical reactivity caused by sp 2 hybridization and strongly delocalized π electrons, however, represents a main challenge for straightforward use of graphene in its pristine, free-standing form. Following recent experimental indications, we show that due to charge hybridization, a Ni(111) substrate can enhance the chemical reactivity of graphene, as exemplified by the interaction with the CO molecule. While CO only physisorbs on free-standing graphene, chemisorption of CO involving formation of ethylene dione complexes is predicted in Ni(111)-graphene. Higher chemical reactivity is also suggested in the case of oxidized graphene, opening the way to a simple and efficient control of graphene chemical properties, devoid of complex defect patterning or active metallic structures deposition.

  4. Chemical reactivity of cation-exchanged zeolites

    NARCIS (Netherlands)

    Pidko, E.A.

    2008-01-01

    Zeolites modified with metal cations have been extensively studied during the last two decades because of their wide application in different technologically important fields such as catalysis, adsorption and gas separation. Contrary to the well-understood mechanisms of chemical reactions catalyzed

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

    Science.gov (United States)

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

    2017-06-29

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

  6. Slow Invariant Manifolds in Chemically Reactive Systems

    Science.gov (United States)

    Paolucci, Samuel; Powers, Joseph M.

    2006-11-01

    The scientific design of practical gas phase combustion devices has come to rely on the use of mathematical models which include detailed chemical kinetics. Such models intrinsically admit a wide range of scales which renders their accurate numerical approximation difficult. Over the past decade, rational strategies, such as Intrinsic Low Dimensional Manifolds (ILDM) or Computational Singular Perturbations (CSP), for equilibrating fast time scale events have been successfully developed, though their computation can be challenging and their accuracy in most cases uncertain. Both are approximations to the preferable slow invariant manifold which best describes how the system evolves in the long time limit. Strategies for computing the slow invariant manifold are examined, and results are presented for practical combustion systems.

  7. Study on chemical reactivity control of liquid sodium. Research program

    International Nuclear Information System (INIS)

    Saito, Jun-ichi; Ara, Kuniaki; Sugiyama, Ken-ichiro; Kitagawa, Hiroshi; Oka, Nobuki; Yoshioka, Naoki

    2007-01-01

    Liquid sodium has the excellent properties as coolant of the fast breeder reactor (FBR). On the other hand, it reacts high with water and oxygen. So an innovative technology to suppress the reactivity is desired. The purpose of this study is to control the chemical reactivity of liquid sodium by dispersing the nanometer-size metallic particles (we call them Nano-particles) into liquid sodium. We focus on the atomic interaction between Nano-particles and sodium atoms. And we try to apply it to suppress the chemical reactivity of liquid sodium. Liquid sodium dispersing Nano-particles is named 'Nano-fluid'. Research programs of this study are the Nano-particles production, the evaluation of reactivity suppression of liquid sodium and the feasibility study to FBR plant. In this paper, the research programs and status are described. The important factors for particle production were understood. In order to evaluate the chemical reactivity of Nano-fluid the research programs were planned. The feasibility of the application of Nano-fluid to the coolant of FBR plant was evaluated preliminarily from the viewpoint of design and operation. (author)

  8. Attenuation of Chemical Reactivity of Shale Matrixes following Scale Precipitation

    Science.gov (United States)

    Li, Q.; Jew, A. D.; Kohli, A. H.; Alalli, G.; Kiss, A. M.; Kovscek, A. R.; Zoback, M. D.; Brown, G. E.; Maher, K.; Bargar, J.

    2017-12-01

    Introduction of fracture fluids into shales initiates a myriad of fluid-rock reactions that can strongly influence migration of fluid and hydrocarbon through shale/fracture interfaces. Due to the extremely low permeability of shale matrixes, studies on chemical reactivity of shales have mostly focused on shale surfaces. Shale-fluid interactions inside within shale matrixes have not been examined, yet the matrix is the primary conduit through which hydrocarbons and potential contaminants are transmitted. To characterize changes in matrix mineralogy, porosity, diffusivity, and permeability during hydraulic stimulation, we reacted Marcellus (high clay and low carbonate) and Eagle Ford (low clay and high carbonate) shale cores with fracture fluids for 3 weeks at elevated pressure and temperature (80 oC, and 77 bars). In the carbonate-poor Marcellus system, fluid pH increased from 2 to 4, and secondary Fe(OH)3 precipitates were observed in the fluid. Sulfur X-ray fluorescence maps show that fluids had saturated and reacted with the entire 1-cm-diameter core. In the carbonate-rich Eagle Ford system, pH increased from 2 to 6 due to calcite dissolution. When additional Ba2+ and SO42- were present (log10(Q/K)=1.3), extensive barite precipitation was observed in the matrix of the Eagle Ford core (and on the surface). Barite precipitation was also observed on the surface of the Marcellus core, although to a lesser extent. In the Marcellus system, the presence of barite scale attenuated diffusivity in the matrix, as demonstrated by sharply reduced Fe leaching and much less sulfide oxidation. Systematic studies in homogeneous solution show that barite scale precipitation rates are highly sensitive to pH, salinity, and the presence of organic compounds. These findings imply that chemical reactions are not confined to shale/fluid interfaces but can penetrate into shale matrices, and that barite scale formation can clog diffusion pathways for both fluid and hydrocarbon.

  9. Chemical stability of reactive skin decontamination lotion (RSDL®).

    Science.gov (United States)

    Bogan, R; Maas, H J; Zimmermann, T

    2018-09-01

    Reactive Skin Decontamination Lotion (RSDL ® ) is used for the decontamination of Chemical Warfare Agents and Toxic Industrial Compounds after dermal exposure. It has to be stockpiled over a long period and is handled in all climatic zones. Therefore stability is an essential matter of concern. In this work we describe a study to the chemical stability of RSDL ® as basis for an estimation of shelf life. We analysed RSDL ® for the active ingredient 2,3-butandione monoxime (diacetylmonooxime, DAM), the putative degradation product dimethylglyoxime (DMG) and unknown degradation products by means of a reversed phase high pressure liquid chromatography (HPLC). Calculations were done according to the Arrhenius equation. Based on the temperature dependent rate constants, the time span was calculated, until defined threshold values for DAM and DMG subject to specification and valid regulations were exceeded. The calculated data were compared to the ones gathered from stockpiled samples and samples exposed during foreign mission. The decline of DAM followed first order kinetics, while formation of DMG could be described by zero order kinetics. The rate constants were distinctively temperature dependent. Calculated data were in good accordance to the measured ones from stockpile and mission. Based on a specified acceptable DAM-content of 90% and a valid threshold value of 0.1% (w/w) for the degradation product DMG, RSDL ® proved to be stable for at least four years if stored at the recommended conditions of 15°C-30°C. If continuously stored at higher temperatures shelf life will decrease markedly. Therefore RSDL ® is an object for risk orientated quality monitoring during storage. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Local Chemical Reactivity of a Metal Alloy Surface

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Scheffler, Matthias

    1995-01-01

    The chemical reactivity of a metal alloy surface is studied by density functional theory investigating the interaction of H2 with NiAl(110). The energy barrier for H2 dissociation is largely different over the Al and Ni sites without, however, reflecting the barriers over the single component metal...

  11. Galaxy formation with radiative and chemical feedback

    NARCIS (Netherlands)

    Graziani, L.; Salvadori, S.; Schneider, R.; Kawata, D.; de Bennassuti, M.; Maselli, A.

    Here we introduce GAMESH, a novel pipeline that implements self-consistent radiative and chemical feedback in a computational model of galaxy formation. By combining the cosmological chemical-evolution model GAMETE with the radiative transfer code CRASH, GAMESH can post-process realistic outputs of

  12. Biogeochemical processes in a clay formation in situ experiment: Part F - Reactive transport modelling

    Energy Technology Data Exchange (ETDEWEB)

    Tournassat, Christophe, E-mail: c.tournassat@brgm.fr [BRGM, French Geological Survey, Orleans (France); Alt-Epping, Peter [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland); Gaucher, Eric C. [BRGM, French Geological Survey, Orleans (France); Gimmi, Thomas [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland)] [Laboratory for Waste Management, Paul Scherrer Institut, Villigen (Switzerland); Leupin, Olivier X. [NAGRA, CH-5430 Wettingen (Switzerland); Wersin, Paul [Gruner Ltd., CH-4020 Basel (Switzerland)

    2011-06-15

    Highlights: > Reactive transport modelling was used to simulate simultaneously solute transport, thermodynamic reactions, ion exchange and biodegradation during an in-situ experiment in a clay-rock formation. > Opalinus clay formation has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. > Buffering capacity is mainly attributed to the carbonate system and to the reactivity of clay surfaces (cation exchange, pH buffering). - Abstract: Reactive transport modelling was used to simulate solute transport, thermodynamic reactions, ion exchange and biodegradation in the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory. Simulations show that the most important chemical processes controlling the fluid composition within the borehole and the surrounding formation during the experiment are ion exchange, biodegradation and dissolution/precipitation reactions involving pyrite and carbonate minerals. In contrast, thermodynamic mineral dissolution/precipitation reactions involving alumo-silicate minerals have little impact on the fluid composition on the time-scale of the experiment. With the accurate description of the initial chemical condition in the formation in combination with kinetic formulations describing the different stages of bacterial activities, it has been possible to reproduce the evolution of important system parameters, such as the pH, redox potential, total organic C, dissolved inorganic C and SO{sub 4} concentration. Leaching of glycerol from the pH-electrode may be the primary source of organic material that initiated bacterial growth, which caused the chemical perturbation in the borehole. Results from these simulations are consistent with data from the over-coring and demonstrate that the Opalinus Clay has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. This buffering capacity can be attributed to the carbonate system as well as to the reactivity of

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-18

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

  14. Formation of iron nanoparticles and increase in iron reactivity in mineral dust during simulated cloud processing.

    Science.gov (United States)

    Shi, Zongbo; Krom, Michael D; Bonneville, Steeve; Baker, Alex R; Jickells, Timothy D; Benning, Liane G

    2009-09-01

    The formation of iron (Fe) nanoperticles and increase in Fe reactivity in mineral dust during simulated cloud processing was investigated using high-resolution microscopy and chemical extraction methods. Cloud processing of dust was experimentally simulated via an alternation of acidic (pH 2) and circumneutral conditions (pH 5-6) over periods of 24 h each on presieved (formation of Fe-rich nanoparticle aggregates, which were not found initially. Similar Fe-rich nanoparticles were also observed in wet-deposited Saharen dusts from the western Mediterranean but not in dry-deposited dust from the eastern Mediterranean. Sequential Fe extraction of the soil samples indicated an increase in the proportion of chemically reactive Fe extractable by an ascorbate solution after simulated cloud processing. In addition, the sequential extractions on the Mediterranean dust samples revealed a higher content of reactive Fe in the wet-deposited dust compared to that of the dry-deposited dust These results suggestthat large variations of pH commonly reported in aerosol and cloud waters can trigger neo-formation of nanosize Fe particles and an increase in Fe reactivity in the dust

  15. Self-organised synthesis of Rh nanostructures with tunable chemical reactivity

    Directory of Open Access Journals (Sweden)

    Lizzit S

    2007-01-01

    Full Text Available AbstractNonequilibrium periodic nanostructures such as nanoscale ripples, mounds and rhomboidal pyramids formed on Rh(110 are particularly interesting as candidate model systems with enhanced catalytic reactivity, since they are endowed with steep facets running along nonequilibrium low-symmetry directions, exposing a high density of undercoordinated atoms. In this review we report on the formation of these novel nanostructured surfaces, a kinetic process which can be controlled by changing parameters such as temperature, sputtering ion flux and energy. The role of surface morphology with respect to chemical reactivity is investigated by analysing the carbon monoxide dissociation probability on the different nanostructured surfaces.

  16. Fast screening of analytes for chemical reactions by reactive low-temperature plasma ionization mass spectrometry.

    Science.gov (United States)

    Zhang, Wei; Huang, Guangming

    2015-11-15

    Approaches for analyte screening have been used to aid in the fine-tuning of chemical reactions. Herein, we present a simple and straightforward analyte screening method for chemical reactions via reactive low-temperature plasma ionization mass spectrometry (reactive LTP-MS). Solution-phase reagents deposited on sample substrates were desorbed into the vapor phase by action of the LTP and by thermal desorption. Treated with LTP, both reagents reacted through a vapor phase ion/molecule reaction to generate the product. Finally, protonated reagents and products were identified by LTP-MS. Reaction products from imine formation reaction, Eschweiler-Clarke methylation and the Eberlin reaction were detected via reactive LTP-MS. Products from the imine formation reaction with reagents substituted with different functional groups (26 out of 28 trials) were successfully screened in a time of 30 s each. Besides, two short-lived reactive intermediates of Eschweiler-Clarke methylation were also detected. LTP in this study serves both as an ambient ionization source for analyte identification (including reagents, intermediates and products) and as a means to produce reagent ions to assist gas-phase ion/molecule reactions. The present reactive LTP-MS method enables fast screening for several analytes from several chemical reactions, which possesses good reagent compatibility and the potential to perform high-throughput analyte screening. In addition, with the detection of various reactive intermediates (intermediates I and II of Eschweiler-Clarke methylation), the present method would also contribute to revealing and elucidating reaction mechanisms. Copyright © 2015 John Wiley & Sons, Ltd.

  17. Formation of calcium phosphate layer on ceramics with different reactivities

    International Nuclear Information System (INIS)

    Ribeiro, C.; Rigo, E.C.S.; Sepulveda, P.; Bressiani, J.C.; Bressiani, A.H.A.

    2004-01-01

    Biphasic ceramic samples of different biological reactivity are prepared by using hydroxyapatite (HAp) and tricalcium phosphate (TCP) in various ratios. Different parameters for sintering in an air atmosphere furnace were defined after dilatometric studies. An increased densification with decreased TCP content was observed. The sintered bodies were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dissolution kinetics and in vitro reactivity were investigated using simulated body fluid (SBF) at 37 deg. C for a maximum period of 3 weeks. The surfaces of the ceramics were analyzed by Fourier transform infrared spectroscopy (FTIR) and SEM in order to observe the formation of a calcium phosphate layer, which indicates the samples bioactivity. Dissolution in SBF demonstrated that layers with different kinetics on the samples surface were formed during the immersion period. The biphasic ceramics show bioactive behavior, even if the resorbable TCP is incorporated

  18. Galactic chemical evolution in hierarchical formation models

    Science.gov (United States)

    Arrigoni, Matias

    2010-10-01

    The chemical properties and abundance ratios of galaxies provide important information about their formation histories. Galactic chemical evolution has been modelled in detail within the monolithic collapse scenario. These models have successfully described the abundance distributions in our Galaxy and other spiral discs, as well as the trends of metallicity and abundance ratios observed in early-type galaxies. In the last three decades, however, the paradigm of hierarchical assembly in a Cold Dark Matter (CDM) cosmology has revised the picture of how structure in the Universe forms and evolves. In this scenario, galaxies form when gas radiatively cools and condenses inside dark matter haloes, which themselves follow dissipationless gravitational collapse. The CDM picture has been successful at predicting many observed properties of galaxies (for example, the luminosity and stellar mass function of galaxies, color-magnitude or star formation rate vs. stellar mass distributions, relative numbers of early and late-type galaxies, gas fractions and size distributions of spiral galaxies, and the global star formation history), though many potential problems and open questions remain. It is therefore interesting to see whether chemical evolution models, when implemented within this modern cosmological context, are able to correctly predict the observed chemical properties of galaxies. With the advent of more powerfull telescopes and detectors, precise observations of chemical abundances and abundance ratios in various phases (stellar, ISM, ICM) offer the opportunity to obtain strong constraints on galaxy formation histories and the physics that shapes them. However, in order to take advantage of these observations, it is necessary to implement detailed modeling of chemical evolution into a modern cosmological model of hierarchical assembly.

  19. Thermal chemical-mechanical reactive flow model of shock initiation in solid explosives

    International Nuclear Information System (INIS)

    Nicholls, A.L. III; Tarver, C.M.

    1998-01-01

    The three dimensional Arbitrary Lagrange Eulerian hydrodynamic computer code ALE3D with fully coupled thermal-chemical-mechanical material models provides the framework for the development of a physically realistic model of shock initiation and detonation of solid explosives. The processes of hot spot formation during shock compression, subsequent ignition of reaction or failure to react, growth of reaction in individual hot spots, and coalescence of reacting hot spots during the transition to detonation can now be modeled using Arrhenius chemical kinetic rate laws and heat transfer to propagate the reactive flow. This paper discusses the growth rates of reacting hot spots in HMX and TATB and their coalescence during shock to detonation transition. Hot spot deflagration rates are found to be fast enough to consume explosive particles less than 10 mm in diameter during typical shock duration times, but larger particles must fragment and create more reactive surface area in order to be rapidly consumed

  20. Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness

    Energy Technology Data Exchange (ETDEWEB)

    Malek, Ali; Balawender, Robert, E-mail: rbalawender@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw (Poland)

    2015-02-07

    The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor.

  1. Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness

    International Nuclear Information System (INIS)

    Malek, Ali; Balawender, Robert

    2015-01-01

    The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor

  2. CHEMICAL EVOLUTION LIBRARY FOR GALAXY FORMATION SIMULATION

    International Nuclear Information System (INIS)

    Saitoh, Takayuki R.

    2017-01-01

    We have developed a software library for chemical evolution simulations of galaxy formation under the simple stellar population (SSP) approximation. In this library, all of the necessary components concerning chemical evolution, such as initial mass functions, stellar lifetimes, yields from Type II and Type Ia supernovae, asymptotic giant branch stars, and neutron star mergers, are compiled from the literature. Various models are pre-implemented in this library so that users can choose their favorite combination of models. Subroutines of this library return released energy and masses of individual elements depending on a given event type. Since the redistribution manner of these quantities depends on the implementation of users’ simulation codes, this library leaves it up to the simulation code. As demonstrations, we carry out both one-zone, closed-box simulations and 3D simulations of a collapsing gas and dark matter system using this library. In these simulations, we can easily compare the impact of individual models on the chemical evolution of galaxies, just by changing the control flags and parameters of the library. Since this library only deals with the part of chemical evolution under the SSP approximation, any simulation codes that use the SSP approximation—namely, particle-base and mesh codes, as well as semianalytical models—can use it. This library is named “CELib” after the term “Chemical Evolution Library” and is made available to the community.

  3. CHEMICAL EVOLUTION LIBRARY FOR GALAXY FORMATION SIMULATION

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, Takayuki R., E-mail: saitoh@elsi.jp [Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro, Tokyo, 152-8551 (Japan)

    2017-02-01

    We have developed a software library for chemical evolution simulations of galaxy formation under the simple stellar population (SSP) approximation. In this library, all of the necessary components concerning chemical evolution, such as initial mass functions, stellar lifetimes, yields from Type II and Type Ia supernovae, asymptotic giant branch stars, and neutron star mergers, are compiled from the literature. Various models are pre-implemented in this library so that users can choose their favorite combination of models. Subroutines of this library return released energy and masses of individual elements depending on a given event type. Since the redistribution manner of these quantities depends on the implementation of users’ simulation codes, this library leaves it up to the simulation code. As demonstrations, we carry out both one-zone, closed-box simulations and 3D simulations of a collapsing gas and dark matter system using this library. In these simulations, we can easily compare the impact of individual models on the chemical evolution of galaxies, just by changing the control flags and parameters of the library. Since this library only deals with the part of chemical evolution under the SSP approximation, any simulation codes that use the SSP approximation—namely, particle-base and mesh codes, as well as semianalytical models—can use it. This library is named “CELib” after the term “Chemical Evolution Library” and is made available to the community.

  4. To Model Chemical Reactivity in Heterogeneous Emulsions, Think Homogeneous Microemulsions.

    Science.gov (United States)

    Bravo-Díaz, Carlos; Romsted, Laurence Stuart; Liu, Changyao; Losada-Barreiro, Sonia; Pastoriza-Gallego, Maria José; Gao, Xiang; Gu, Qing; Krishnan, Gunaseelan; Sánchez-Paz, Verónica; Zhang, Yongliang; Dar, Aijaz Ahmad

    2015-08-25

    Two important and unsolved problems in the food industry and also fundamental questions in colloid chemistry are how to measure molecular distributions, especially antioxidants (AOs), and how to model chemical reactivity, including AO efficiency in opaque emulsions. The key to understanding reactivity in organized surfactant media is that reaction mechanisms are consistent with a discrete structures-separate continuous regions duality. Aggregate structures in emulsions are determined by highly cooperative but weak organizing forces that allow reactants to diffuse at rates approaching their diffusion-controlled limit. Reactant distributions for slow thermal bimolecular reactions are in dynamic equilibrium, and their distributions are proportional to their relative solubilities in the oil, interfacial, and aqueous regions. Our chemical kinetic method is grounded in thermodynamics and combines a pseudophase model with methods for monitoring the reactions of AOs with a hydrophobic arenediazonium ion probe in opaque emulsions. We introduce (a) the logic and basic assumptions of the pseudophase model used to define the distributions of AOs among the oil, interfacial, and aqueous regions in microemulsions and emulsions and (b) the dye derivatization and linear sweep voltammetry methods for monitoring the rates of reaction in opaque emulsions. Our results show that this approach provides a unique, versatile, and robust method for obtaining quantitative estimates of AO partition coefficients or partition constants and distributions and interfacial rate constants in emulsions. The examples provided illustrate the effects of various emulsion properties on AO distributions such as oil hydrophobicity, emulsifier structure and HLB, temperature, droplet size, surfactant charge, and acidity on reactant distributions. Finally, we show that the chemical kinetic method provides a natural explanation for the cut-off effect, a maximum followed by a sharp reduction in AO efficiency with

  5. Local chemical potential, local hardness, and dual descriptors in temperature dependent chemical reactivity theory.

    Science.gov (United States)

    Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

    2017-05-31

    In this work we establish a new temperature dependent procedure within the grand canonical ensemble, to avoid the Dirac delta function exhibited by some of the second order chemical reactivity descriptors based on density functional theory, at a temperature of 0 K. Through the definition of a local chemical potential designed to integrate to the global temperature dependent electronic chemical potential, the local chemical hardness is expressed in terms of the derivative of this local chemical potential with respect to the average number of electrons. For the three-ground-states ensemble model, this local hardness contains a term that is equal to the one intuitively proposed by Meneses, Tiznado, Contreras and Fuentealba, which integrates to the global hardness given by the difference in the first ionization potential, I, and the electron affinity, A, at any temperature. However, in the present approach one finds an additional temperature-dependent term that introduces changes at the local level and integrates to zero. Additionally, a τ-hard dual descriptor and a τ-soft dual descriptor given in terms of the product of the global hardness and the global softness multiplied by the dual descriptor, respectively, are derived. Since all these reactivity indices are given by expressions composed of terms that correspond to products of the global properties multiplied by the electrophilic or nucleophilic Fukui functions, they may be useful for studying and comparing equivalent sites in different chemical environments.

  6. Automated chemical kinetic modeling via hybrid reactive molecular dynamics and quantum chemistry simulations.

    Science.gov (United States)

    Döntgen, Malte; Schmalz, Felix; Kopp, Wassja A; Kröger, Leif C; Leonhard, Kai

    2018-06-13

    An automated scheme for obtaining chemical kinetic models from scratch using reactive molecular dynamics and quantum chemistry simulations is presented. This methodology combines the phase space sampling of reactive molecular dynamics with the thermochemistry and kinetics prediction capabilities of quantum mechanics. This scheme provides the NASA polynomial and modified Arrhenius equation parameters for all species and reactions that are observed during the simulation and supplies them in the ChemKin format. The ab initio level of theory for predictions is easily exchangeable and the presently used G3MP2 level of theory is found to reliably reproduce hydrogen and methane oxidation thermochemistry and kinetics data. Chemical kinetic models obtained with this approach are ready-to-use for, e.g., ignition delay time simulations, as shown for hydrogen combustion. The presented extension of the ChemTraYzer approach can be used as a basis for methodologically advancing chemical kinetic modeling schemes and as a black-box approach to generate chemical kinetic models.

  7. Reactivity of paraquat with sodium salicylate: Formation of stable complexes

    International Nuclear Information System (INIS)

    Dinis-Oliveira, Ricardo Jorge; Guedes de Pinho, Paula; Ferreira, Antonio Cesar Silva; Silva, Artur M.S.; Afonso, Carlos; Bastos, Maria de Lourdes; Remiao, Fernando; Duarte, Jose Alberto; Carvalho, Felix

    2008-01-01

    Sodium salicylate (NaSAL) has been shown to be a promising antidote for the treatment of paraquat (PQ) poisonings. The modulation of the pro-oxidant and pro-inflammatory pathways, as well as the anti-thrombogenic properties of NaSAL are probably essential features for the healing effects provided by this drug. Nevertheless, a possible direct chemical reactivity between PQ and NaSAL is also a putative pathway to be considered, this hypothesis being the ground of the present study. In accordance, it is shown, for the first time that PQ and NaSAL react immediately in aqueous medium and within 2-3 min in the solid state. Photographs and scanning electron photomicrographs indicated that a new chemical entity is formed when both compounds are mixed. This assumption was corroborated by the evaluation of the melting point, and through several analytical techniques, namely ultraviolet/visible spectroscopy, nuclear magnetic resonance spectroscopy, gas chromatography/mass spectrometry/mass spectrometry (GC/MS/MS), liquid chromatography/electrospray ionization/mass spectrometry/mass spectrometry (LC/ESI/MS/MS) and infrared spectroscopy, which revealed that stable charge-transfer complexes are formed when PQ is mixed with NaSAL. LC/ESI/MS/MS allowed obtaining the stoichiometry of the charge-transfer complexes. In order to increase resolution, single value decomposition, acting as a filter, showed that the charge-transfer complexes with m/z 483, 643 and 803 correspond to the pseudo-molecular ions, respectively 1:2, 1:3 and 1:4 (PQ:NaSAL). In conclusion, these results provided a new and important mechanism of action of NaSAL against the toxicity mediated by PQ

  8. Reactive oxidation products promote secondary organic aerosol formation from green leaf volatiles

    Directory of Open Access Journals (Sweden)

    J. F. Hamilton

    2009-06-01

    Full Text Available Green leaf volatiles (GLVs are an important group of chemicals released by vegetation which have emission fluxes that can be significantly increased when plants are damaged or stressed. A series of simulation chamber experiments has been conducted at the European Photoreactor in Valencia, Spain, to investigate secondary organic aerosol (SOA formation from the atmospheric oxidation of the major GLVs cis-3-hexenylacetate and cis-3-hexen-1-ol. Liquid chromatography-ion trap mass spectrometry was used to identify chemical species present in the SOA. Cis-3-hexen-1-ol proved to be a more efficient SOA precursor due to the high reactivity of its first generation oxidation product, 3-hydroxypropanal, which can hydrate and undergo further reactions with other aldehydes resulting in SOA dominated by higher molecular weight oligomers. The lower SOA yields produced from cis-3-hexenylacetate are attributed to the acetate functionality, which inhibits oligomer formation in the particle phase. Based on observed SOA yields and best estimates of global emissions, these compounds may be calculated to be a substantial unidentified global source of SOA, contributing 1–5 TgC yr−1, equivalent to around a third of that predicted from isoprene. Molecular characterization of the SOA, combined with organic mechanistic information, has provided evidence that the formation of organic aerosols from GLVs is closely related to the reactivity of their first generation atmospheric oxidation products, and indicates that this may be a simple parameter that could be used in assessing the aerosol formation potential for other unstudied organic compounds in the atmosphere.

  9. Atomic-level spatial distributions of dopants on silicon surfaces: toward a microscopic understanding of surface chemical reactivity

    Science.gov (United States)

    Hamers, Robert J.; Wang, Yajun; Shan, Jun

    1996-11-01

    We have investigated the interaction of phosphine (PH 3) and diborane (B 2H 6) with the Si(001) surface using scanning tunneling microscopy, infrared spectroscopy, and ab initio molecular orbital calculations. Experiment and theory show that the formation of PSi heterodimers is energetically favorable compared with formation of PP dimers. The stability of the heterodimers arises from a large strain energy associated with formation of PP dimers. At moderate P coverages, the formation of PSi heterodimers leaves the surface with few locations where there are two adjacent reactive sites. This in turn modifies the chemical reactivity toward species such as PH 3, which require only one site to adsorb but require two adjacent sites to dissociate. Boron on Si(001) strongly segregates into localized regions of high boron concentration, separated by large regions of clean Si. This leads to a spatially-modulated chemical reactivity which during subsequent growth by chemical vapor deposition (CVD) leads to formation of a rough surface. The implications of the atomic-level spatial distribution of dopants on the rates and mechanisms of CVD growth processes are discussed.

  10. Reactive solute transport in physically and chemically heterogeneous porous media with multimodal reactive mineral facies: the Lagrangian approach.

    Science.gov (United States)

    Soltanian, Mohamad Reza; Ritzi, Robert W; Dai, Zhenxue; Huang, Chao Cheng

    2015-03-01

    Physical and chemical heterogeneities have a large impact on reactive transport in porous media. Examples of heterogeneous attributes affecting reactive mass transport are the hydraulic conductivity (K), and the equilibrium sorption distribution coefficient (Kd). This paper uses the Deng et al. (2013) conceptual model for multimodal reactive mineral facies and a Lagrangian-based stochastic theory in order to analyze the reactive solute dispersion in three-dimensional anisotropic heterogeneous porous media with hierarchical organization of reactive minerals. An example based on real field data is used to illustrate the time evolution trends of reactive solute dispersion. The results show that the correlation between the hydraulic conductivity and the equilibrium sorption distribution coefficient does have a significant effect on reactive solute dispersion. The anisotropy ratio does not have a significant effect on reactive solute dispersion. Furthermore, through a sensitivity analysis we investigate the impact of changing the mean, variance, and integral scale of K and Kd on reactive solute dispersion. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Substrate Vibrations as Promoters of Chemical Reactivity on Metal Surfaces.

    Science.gov (United States)

    Campbell, Victoria L; Chen, Nan; Guo, Han; Jackson, Bret; Utz, Arthur L

    2015-12-17

    Studies exploring how vibrational energy (Evib) promotes chemical reactivity most often focus on molecular reagents, leaving the role of substrate atom motion in heterogeneous interfacial chemistry underexplored. This combined theoretical and experimental study of methane dissociation on Ni(111) shows that lattice atom motion modulates the reaction barrier height during each surface atom's vibrational period, which leads to a strong variation in the reaction probability (S0) with surface temperature (Tsurf). State-resolved beam-surface scattering studies at Tsurf = 90 K show a sharp threshold in S0 at translational energy (Etrans) = 42 kJ/mol. When Etrans decreases from 42 kJ/mol to 34 kJ/mol, S0 decreases 1000-fold at Tsurf = 90 K, but only 2-fold at Tsurf = 475 K. Results highlight the mechanism for this effect, provide benchmarks for DFT calculations, and suggest the potential importance of surface atom induced barrier height modulation in heterogeneously catalyzed reactions, particularly on structurally labile nanoscale particles and defect sites.

  12. Chemical fingerprints of hot Jupiter planet formation

    Science.gov (United States)

    Maldonado, J.; Villaver, E.; Eiroa, C.

    2018-05-01

    Context. The current paradigm to explain the presence of Jupiter-like planets with small orbital periods (P involves their formation beyond the snow line following inward migration, has been challenged by recent works that explore the possibility of in situ formation. Aims: We aim to test whether stars harbouring hot Jupiters and stars with more distant gas-giant planets show any chemical peculiarity that could be related to different formation processes. Methods: Our methodology is based on the analysis of high-resolution échelle spectra. Stellar parameters and abundances of C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, and Zn for a sample of 88 planet hosts are derived. The sample is divided into stars hosting hot (a 0.1 au) Jupiter-like planets. The metallicity and abundance trends of the two sub-samples are compared and set in the context of current models of planet formation and migration. Results: Our results show that stars with hot Jupiters have higher metallicities than stars with cool distant gas-giant planets in the metallicity range +0.00/+0.20 dex. The data also shows a tendency of stars with cool Jupiters to show larger abundances of α elements. No abundance differences between stars with cool and hot Jupiters are found when considering iron peak, volatile elements or the C/O, and Mg/Si ratios. The corresponding p-values from the statistical tests comparing the cumulative distributions of cool and hot planet hosts are 0.20, products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 072.C-0033(A), 072.C-0488(E), 074.B-0455(A), 075.C-0202(A), 077.C-0192(A), 077.D-0525(A), 078.C-0378(A), 078.C-0378(B), 080.A-9021(A), 082.C-0312(A) 082.C-0446(A), 083.A-9003(A), 083.A-9011(A), 083.A-9011(B), 083.A-9013(A), 083.C-0794(A), 084.A-9003(A), 084.A-9004(B), 085.A-9027(A), 085.C-0743(A), 087.A-9008(A), 088.C-0892(A), 089.C-0440(A), 089.C-0444(A), 089.C-0732(A), 090.C-0345(A), 092.A-9002(A), 192.C-0852

  13. Chemical Characterization and Reactivity of Fuel-Oxidizer Reaction Product

    Science.gov (United States)

    David, Dennis D.; Dee, Louis A.; Beeson, Harold D.

    1997-01-01

    Fuel-oxidizer reaction product (FORP), the product of incomplete reaction of monomethylhydrazine and nitrogen tetroxide propellants prepared under laboratory conditions and from firings of Shuttle Reaction Control System thrusters, has been characterized by chemical and thermal analysis. The composition of FORP is variable but falls within a limited range of compositions that depend on three factors: the fuel-oxidizer ratio at the time of formation; whether the composition of the post-formation atmosphere is reducing or oxidizing; and the reaction or post-reaction temperature. A typical composition contains methylhydrazinium nitrate, ammonium nitrate, methylammonium nitrate, and trace amounts of hydrazinium nitrate and 1,1-dimethylhydrazinium nitrate. Thermal decomposition reactions of the FORP compositions used in this study were unremarkable. Neither the various compositions of FORP, the pure major components of FORP, nor mixtures of FORP with propellant system corrosion products showed any unusual thermal activity when decomposed under laboratory conditions. Off-limit thruster operations were simulated by rapid mixing of liquid monomethylhydrazine and liquid nitrogen tetroxide in a confined space. These tests demonstrated that monomethylhydrazine, methylhydrazinium nitrate, ammonium nitrate, or Inconel corrosion products can induce a mixture of monomethylhydrazine and nitrogen tetroxide to produce component-damaging energies. Damaging events required FORP or metal salts to be present at the initial mixing of monomethylhydrazine and nitrogen tetroxide.

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

    Science.gov (United States)

    Durairaj, Vijayasarathi; Punnaivanam, Sankar

    2015-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Anita S.; Kitchin, John R.

    2012-10-24

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

  16. Formation for the calculation of reactivity without nuclear power history

    International Nuclear Information System (INIS)

    Suescun Diaz, Daniel; Senra Martinez, Aquilino; Carvalho Da Silva, Fernando

    2007-01-01

    This paper presents a new method for the solution of the inverse point kinetics equation. This method is based on the integration by parts of the integral of the inverse point kinetics equation, which results in a power series in terms of the nuclear power in time dependence. With the imposition of conditions to the nuclear power, the reactivity is represented as first and second derivatives of this nuclear power. This new calculation method for reactivity has very special characteristics, amongst which the possibility of using longer sampling period, and the possibility of restarting the calculation, after its interruption, allowing the calculation of reactivity in a non-continuous way. Beside that, the reactivity can be obtained independent of the nuclear power memory. (author)

  17. Evidences for the Formation of Chromium in the Unusual Oxidation State Cr(IV). I. Chemical Reactivity, Microhomogeneity, and Crystal Structures of the Nonstoichiometric Channel Compounds Tl xCr 5Se 8(0 ≤ x≤ 1)

    Science.gov (United States)

    Bensch, W.; Helmer, O.; Näther, C.

    1996-11-01

    The topotactic redox reaction between TlCr 5Se 8and bromine in acetonitrile leads to the formation of metastable samples with 0 ≤ xtransition metal chalcogenide crystallizing in the TlV 5S 8type structure with a Tl content xtopotactic redox reaction does not follow simple kinetics but is rather explained on the basis of the superposition of at least three different fundamental steps. EDAX investigations conducted on selected single crystals reveal that dependent on the deintercalation temperature, Tl is laterally inhomogeneous distributed along the needle axis which coincides with the crystallographic baxis. A pronounced maximum is observed at the middle of the crystals. In stoichiometric TlCr 5Se 8the detailed analysis of the anisotropic displacement parameters of the Tl atoms reveal that the Tl atoms are displaced from the central position by about 0.26 Å. As a consequence the Tl atoms are coordinated by seven Se atoms in an irregular coordination polyhedron. Since the positions x0 zare related by a center of symmetry they cannot be occupied simultaneously. Hence it must be assumed that TlCr 5Se 8has a domain structure with local symmetry Cm. In the Tl poorer phases the refinement of the Tl atoms at the central position leads to unusual high U22components. The observed microinhomogenity as well as an enhanced mobility and/or static disorder of the Tl atom within the channel may be responsible for this. The value for U11decreases with decreasing Tl content whereas U33is not affected. This observation is indicative for a different displacement of the Tl atoms from the central position. With respect to the possible reaction mechanisms, according to our structural investigations, the oxidation of monovalent Tl to trivalent Tl can be excluded. With decreasing Tl content the lattice parameters exhibit very anisotropic behavior, which is a direct consequence of the large changes of the interatomic Cr-Cr distances. The average as well as the nonbonding Se-Se distances

  18. Theoretical study of some aspects of the nucleo-bases reactivity: definition of new theoretical tools for the study of chemical reactivity

    International Nuclear Information System (INIS)

    Labet, V.

    2009-09-01

    In this work, three kinds of nucleo-base damages were studied from a theoretical point of view with quantum chemistry methods based on the density-functional theory: the spontaneous deamination of cytosine and its derivatives, the formation of tandem lesion induced by hydroxyl radicals in anaerobic medium and the formation of pyrimidic dimers under exposition to an UV radiation. The complementary use of quantitative static methods allowing the exploration of the potential energy surface of a chemical reaction, and of 'conceptual DFT' principles, leads to information concerning the mechanisms involved and to the rationalization of the differences in the nucleo-bases reactivity towards the formation of a same kind of damage. At the same time, a reflexion was undertaken on the asynchronous concerted mechanism concept, in terms of physical meaning of the transition state, respect of the Maximum Hardness Principle, and determination of the number of primitive processes involved. Finally, a new local reactivity index was developed, relevant to understand the reactivity of a molecular system in an excited state. (author)

  19. Shock-induced hotspot formation and chemical reaction initiation in PETN containing a spherical void

    International Nuclear Information System (INIS)

    Shan, Tzu-Ray; Thompson, Aidan P

    2014-01-01

    We present results of reactive molecular dynamics simulations of hotspot formation and chemical reaction initiation in shock-induced compression of pentaerythritol tetranitrate (PETN) with the ReaxFF reactive force field. A supported shockwave is driven through a PETN crystal containing a 20 nm spherical void at a sub-threshold impact velocity of 2 km/s. Formation of a hotspot due to shock-induced void collapse is observed. During void collapse, NO 2 is the dominant species ejected from the upstream void surface. Once the ejecta collide with the downstream void surface and the hotspot develops, formation of final products such as N 2 and H 2 O is observed. The simulation provides a detailed picture of how void collapse and hotspot formation leads to initiation at sub-threshold impact velocities.

  20. Chemical reactivity of alkali lignin modified with laccase

    International Nuclear Information System (INIS)

    Sun, Yong; Qiu, Xueqing; Liu, Yunquan

    2013-01-01

    The modification of alkali lignin with laccase was investigated. The structural change of lignin was analyzed. The sulfonation reactivity was measured by the content of sulfonic group. The results showed the sulfonation reactivity increased to some extent under the condition of atmosphere pressure, but decreased under the condition of 0.3 MPa oxygen pressure. The analysis of Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) showed the cleavage of various ether linkages and demethylation took place in the structure of lignin to certain extent during modification with laccase, which contributed to the improvement of sulfonation reactivity. Under the condition of 0.3 MPa oxygen pressure, the ratio of s/g (guaiacyl/syringyl) increased after modification, which reduced the sulfonation reactivity of lignin. Simultaneously partial polymerization reaction, such as 4-O-5′, β-5, 5-5 and other reaction in the aromatic ring decreased the activity sites of C 2 , C 5 and C 6 . Abundant polymerization reaction of α-O increased steric hindrance of C 2 and C 6 in aromatic ring, resulting in low sulfonation reactivity of lignin. -- Highlights: ► The modification of alkali lignin with laccase was investigated. ► The sulfonation reactivity increased under the condition of atmosphere pressure. ► More content of guaiacyl and hydroxy, the less content of methoxyl, syringyl can enhance the sulfonation reactivity of lignin. ► Partial moieties polymerized each other with α-O linkgages during treatment with laccase under oxygen pressure. ► The steric hindrance on C 2 and C 6 in aromatic ring resulted in low sulfonation reaction reactivity of lignin

  1. Transport and Reactivity of Decontaminants to Provide Hazard Mitigation of Chemical Warfare Agents from Materials

    Science.gov (United States)

    2016-06-01

    2013 4. TITLE AND SUBTITLE Transport and Reactivity of Decontaminants to Provide Hazard Mitigation of Chemical Warfare Agents from Materials 5a...directions for future decontamination formulation approaches. 15. SUBJECT TERMS GD HD Decontamination Hazard mitigation VX Chemical warfare agent... DECONTAMINANTS TO PROVIDE HAZARD MITIGATION OF CHEMICAL WARFARE AGENTS FROM MATERIALS 1. INTRODUCTION Decontamination of materials is the

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

    NARCIS (Netherlands)

    Scheeren, H.A.

    2003-01-01

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

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

    Directory of Open Access Journals (Sweden)

    T. F. Lyon

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

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

    Directory of Open Access Journals (Sweden)

    C. W. Spicer

    1994-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Kai Wang

    2017-08-01

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

  6. Pattern formation in arrays of chemical oscillators

    Indian Academy of Sciences (India)

    Chemical oscillators; phase flip; oscillation death. PACS No. 05.45 .... array oscillate (with varying amplitudes and frequencies), while the others experience oscillation death .... Barring the boundary cells, one observes near phase flip and near ...

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

    Indian Academy of Sciences (India)

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

  8. Formation of reactive oxygen species in rat epithelial cells upon ...

    Indian Academy of Sciences (India)

    Unknown

    clear dose-response relationship concerning the formation of ROS with regard to the .... allowed to attach over night and subsequently washed .... days?; Environ. Res. 64 6–35. Simon R H and Paine R 1995 Participation of pulmonary alveo-.

  9. Modification of chemical reactivity of enzymatic hydrolysis lignin by ultrasound treatment in dilute alkaline solutions.

    Science.gov (United States)

    Ma, Zhuoming; Li, Shujun; Fang, Guizhen; Patil, Nikhil; Yan, Ning

    2016-12-01

    In this study, we have explored various ultrasound treatment conditions for structural modification of enzymatic hydrolysis lignin (EHL) for enhanced chemical reactivity. The key structural modifications were characterized by using a combination of analytical methods, including, Fourier Transform-Infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance ( 1 H NMR), Gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), and Folin-Ciocalteu (F-C) method. Chemical reactivity of the modified EHL samples was determined by both 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and their reactivity towards formaldehyde. It was observed that the modified EHL had a higher phenolic hydroxyl group content, a lower molecular weight, a higher reactivity towards formaldehyde, and a greater antioxidant property. The higher reactivity demonstrated by the samples after treatment suggesting that ultrasound is a promising method for modifying enzymatic hydrolysis lignin for value-added applications. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    NARCIS (Netherlands)

    Freidig, Andreas Peter

    2000-01-01

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

  11. Reactive skin decontamination lotion (RSDL) for the decontamination of chemical warfare agent (CWA) dermal exposure.

    Science.gov (United States)

    Schwartz, M D; Hurst, C G; Kirk, M A; Reedy, S J D; Braue, E H

    2012-08-01

    Rapid decontamination of the skin is the single most important action to prevent dermal absorption of chemical contaminants in persons exposed to chemical warfare agents (CWA) and toxic industrial chemicals (TICs) as a result of accidental or intentional release. Chemicals on the skin may be removed by mechanical means through the use of dry sorbents or water. Recent interest in decontamination systems which both partition contaminants away from the skin and actively neutralize the chemical has led to the development of several reactive decontamination solutions. This article will review the recently FDA-approved Reactive Skin Decontamination Lotion (RSDL) and will summarize the toxicity and efficacy studies conducted to date. Evidence of RSDL's superior performance against vesicant and organophosphorus chemical warfare agents compared to water, bleach, and dry sorbents, suggests that RSDL may have a role in mass human exposure chemical decontamination in both the military and civilian arenas.

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

    Science.gov (United States)

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

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

    Directory of Open Access Journals (Sweden)

    PLATT G. M.

    1999-01-01

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

  14. EFFECTS OF THERMAL TREATMENTS ON THE CHEMICAL REACTIVITY OF TRICHLOROETHYLENE

    Science.gov (United States)

    A series of experiments was completed to investigate abiotic degradation and reaction product formation of trichloroethylene (TCE) when heated. A quartz-tube apparatus was used to study short residence time and high temperature conditions that are thought to occur during thermal ...

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

    Science.gov (United States)

    Scheeren, H. A.

    2003-09-01

    The work presented in this thesis focuses on measurements of chemical reactive C2 C7 non-methane hydrocarbons (NMHC) and C1 C2 chlorocarbons with atmospheric lifetimes of a few hours up to about a year. The group of reactive chlorocarbons includes the most abundant atmospheric species with large natural sources, which are chloromethane (CH3Cl), dichloromethane (CH2Cl2), and trichloromethane (CHCl3), and tetrachloroethylene (C2Cl4) with mainly anthropogenic sources. The NMHC and chlorocarbons are present at relatively low quantities in our atmosphere (10-12 10-9 mol mol-1 of air). Nevertheless, they play a key role in atmospheric photochemistry. For example, the oxidation of NMHC plays a dominant role in the formation of ozone in the troposphere, while the photolysis of chlorocarbons contributes to enhanced ozone depletion in the stratosphere. In spite of their important role, however, their global source and sinks budgets are still poorly understood. Hence, this study aims at improving our understanding of the sources, distribution, and chemical role of reactive NMHC and chlorocarbons in the troposphere and lower stratosphere. To meet this aim, a comprehensive data set of selected C2 C7 NMHC and chlorocarbons has been analyzed, derived from six aircraft measurement campaigns with two different jet aircrafts (the Dutch TUD/NLR Cessna Citation PH-LAB, and the German DLR Falcon) conducted between 1995 and 2001 (STREAM 1995 and 1997 and 1998, LBA-CLAIRE 1998, INDOEX 1999, MINOS 2001). The NMHC and chlorocarbons have been detected by gas-chromatography (GC-FID/ECD) in pre-concentrated whole air samples collected in stainless steel canister on-board the measurement aircrafts. The measurement locations include tropical (Maldives/Indian Ocean and Surinam), midlatitude (Western Europe and Canada) and polar regions (Lapland/northern Sweden) between the equator to about 70ºN, covering different seasons and pollution levels in the troposphere and lower stratosphere. Of

  16. Evaluation of the chemical reactivity in lignin precursors using the Fukui function.

    Science.gov (United States)

    Martinez, Carmen; Rivera, José L; Herrera, Rafael; Rico, José L; Flores, Nelly; Rutiaga, José G; López, Pablo

    2008-02-01

    The hydroxycinnamyl alcohols: p-coumarol, coniferol and sinapol are considered the basic units and precursors of lignins models. In this work, the specific reactivity of these molecules was studied. We investigate their intrinsic chemical reactivity in terms of the Fukui function, applying the principle of hard and soft acids and bases (HSAB) in the framework of the density functional theory (DFT). Comparisons of their nucleophilic, electrophilic and free radical reactivity show their most probably sites to form linkages among them. It is found that the most reactive sites, for reactions involving free radicals, are the carbons at the beta-position in the p-coumarol and sinapol molecules, whilst the regions around the carbon-oxygen bond of the phenoxyl group are the most reactive in coniferol.

  17. Reactive formulations for a neutralization of toxic industrial chemicals

    Science.gov (United States)

    Tucker, Mark D [Albuqueruqe, NM; Betty, Rita G [Rio Rancho, NM

    2006-10-24

    Decontamination formulations for neutralization of toxic industrial chemicals, and methods of making and using same. The formulations are effective for neutralizing malathion, hydrogen cyanide, sodium cyanide, butyl isocyanate, carbon disulfide, phosgene gas, capsaicin in commercial pepper spray, chlorine gas, anhydrous ammonia gas; and may be effective at neutralizing hydrogen sulfide, sulfur dioxide, formaldehyde, ethylene oxide, methyl bromide, boron trichloride, fluorine, tetraethyl pyrophosphate, phosphorous trichloride, arsine, and tungsten hexafluoride.

  18. Chemical and Photochemical Reactivity in Microemulsions and Waterless Microemulsions.

    Science.gov (United States)

    1988-02-10

    virtually the same as that found in the alcohol rich microemulsion A. This value is also close to that found in pure butanol (= 5.0 - table I). It would...formamide or alcohol rich). RESEARCH PATTERN -Supplementing the physical chemical study of the microemulsion medium involving ionic surfactants with density...SAMII (1/02/1988) Ii&N 3 Part II - OXYDATIONS BY HYDROPEROXIDES IN MICROEMULSIONS E. OLIVEROS and M.T. MAURETTE During the past six months, the financial

  19. Large-Eddy Simulation of Chemically Reactive Pollutant Transport from a Point Source in Urban Area

    Science.gov (United States)

    Du, Tangzheng; Liu, Chun-Ho

    2013-04-01

    Most air pollutants are chemically reactive so using inert scalar as the tracer in pollutant dispersion modelling would often overlook their impact on urban inhabitants. In this study, large-eddy simulation (LES) is used to examine the plume dispersion of chemically reactive pollutants in a hypothetical atmospheric boundary layer (ABL) in neutral stratification. The irreversible chemistry mechanism of ozone (O3) titration is integrated into the LES model. Nitric oxide (NO) is emitted from an elevated point source in a rectangular spatial domain doped with O3. The LES results are compared well with the wind tunnel results available in literature. Afterwards, the LES model is applied to idealized two-dimensional (2D) street canyons of unity aspect ratio to study the behaviours of chemically reactive plume over idealized urban roughness. The relation among various time scales of reaction/turbulence and dimensionless number are analysed.

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-31

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

  3. Study of powder formation in reactive coaxial jets

    International Nuclear Information System (INIS)

    Ablitzer, C.

    1999-01-01

    One step of the conversion of gaseous UF 6 to solid UO 2 by dry route is the formation of particles of UO 2 F 2 in a triple coaxial jet UF 6 /N 2 /H 2 O. The characteristics of resulting powder have an influence on the properties of final particles of UO 2 , and then on the quality of pellets of nuclear fuel. So a good control of this step of the process is of interest. This study deals with an experimental investigation and a modelling of the influence of various parameters on particles obtained by reaction in a turbulent coaxial jet. For example, the influence of absolute and relative velocities of gases on particle size distributions has been investigated. Two kinds of experimental studies have been undertaken. First, the development of mixing layers in the near field of the jet has been evaluated with temperature measurements. Then, particle size distributions have been measured with a turbidimetric sensor, for particles obtained by hydrolysis of gaseous metallic chlorides (SnCl 4 , TiCl 4 ) in double and triple coaxial jets. A model has been proposed for mixing of gases and growth of particles. It takes into account the development of mixing layers, meso-mixing, micro-mixing and growth of particles through agglomeration. The influence of operating parameters, especially velocities, on experimental results appear to be different for TiCl 4 /H 2 O jets and SnCl 4 /H 2 O jets. In fact, a comparison of theoretical and experimental results shows that particles obtained by hydrolysis of TiCl 4 seem to grow mainly through agglomeration whereas another growth phenomenon may be involved for particles obtained by hydrolysis of SnCl 4 . (author)

  4. Study of fuel powder formation in reactive coaxial jets

    International Nuclear Information System (INIS)

    Ablitzer, C.

    1999-01-01

    One step of the conversion of gaseous UF 6 to solid UO 2 by dry route is the formation of particles of UO 2 F 2 in a triple coaxial jet UF 6 /N 2 /H 2 O. The characteristics of resulting powder have an influence on the properties of final particles of UO 2 , and then on the quality of pellets of nuclear fuel. So a good control of this step of the process is of interest. This study deals with an experimental investigation and modelling of the influence of various parameters on particles obtained by reaction in a turbulent coaxial jet. For example, the influence of absolute and relative velocities of gases on particle size distributions has been investigated. Two kinds of experimental studies have been undertaken. First, the development of mixing layers in the near field of the jet has been evaluated with temperature measurements. Then, particle size distributions have been measured with e turbidimetric sensor, for particles obtained by hydrolysis of gaseous metallic chlorides (SnCl 4 , TiCl 4 ) in double and triple coaxial jets. A model has been proposed for mixing of gases and growth of particles. It takes into account the development of mixing layers, meso-mixing, micro-mixing and growth of particles through agglomeration. The influence of operating parameters, especially velocities, on experimental results appear to be different for TiCl 4 /H 2 O jets and SnCl 4 /H 2 O jets. In fact, a comparison of theoretical and experimental results shows that particles obtained by hydrolysis of TiCl 4 seem to grow mainly through agglomeration whereas another growth phenomenon may be involved for particles obtained by hydrolysis of SnCl 4 . (authors)

  5. An experimental study of steam explosions involving chemically reactive metal

    International Nuclear Information System (INIS)

    Cho, D.H.; Armstrong, D.R.; Gunther, W.H.; Basu, S.

    1997-01-01

    An experimental study of molten zirconium-water explosions was conducted. A 1-kg mass of zirconium melt was dropped into a column of water. Explosions took place only when an external trigger was used. In the triggered tests, the extent of oxidation of the zirconium melt was very extensive. However, the explosion energetics estimated were found to be very small compared to the potential chemical energy available from the oxidation reaction. Zirconium is of particular interest, since it is a component of the core materials of the current nuclear power reactors. This paper describes the test apparatus and summarizes the results of four tests conducted using pure zirconium melt

  6. Chemical stability and in chemico reactivity of 24 fragrance ingredients of concern for skin sensitization risk assessment.

    Science.gov (United States)

    Avonto, Cristina; Wang, Mei; Chittiboyina, Amar G; Vukmanovic, Stanislav; Khan, Ikhlas A

    2018-02-01

    Twenty-four pure fragrance ingredients have been identified as potential concern for skin sensitization. Several of these compounds are chemically unstable and convert into reactive species upon exposure to air or light. In the present work, a systematic investigation of the correlation between chemical stability and reactivity has been undertaken. The compounds were subjected to forced photodegradation for three months and the chemical changes were studied with GC-MS. At the end of the stability study, two-thirds of the samples were found to be unstable. The generation of chemically reactive species was investigated using the in chemico HTS-DCYA assay. Eleven and fourteen compounds were chemically reactive before and after three months, respectively. A significant increase in reactivity upon degradation was found for isoeugenol, linalool, limonene, lyral, citronellol and geraniol; in the same conditions, the reactivity of hydroxycitronellal decreased. The non-reactive compounds α-isomethyl ionone, benzyl alcohol, amyl cinnamal and farnesol became reactive after photo-oxidative degradation. Overall, forced degradation resulted in four non-reactive fragrance compounds to display in chemico thiol reactivity, while ten out of 24 compounds remained inactive. Chemical degradation does not necessarily occur with generation of reactive species. Non-chemical activation may be involved for the 10 stable unreactive compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Multiphase composition changes and reactive oxygen species formation during limonene oxidation in the new Cambridge Atmospheric Simulation Chamber (CASC)

    Science.gov (United States)

    Gallimore, Peter J.; Mahon, Brendan M.; Wragg, Francis P. H.; Fuller, Stephen J.; Giorio, Chiara; Kourtchev, Ivan; Kalberer, Markus

    2017-08-01

    The chemical composition of organic aerosols influences their impacts on human health and the climate system. Aerosol formation from gas-to-particle conversion and in-particle reaction was studied for the oxidation of limonene in a new facility, the Cambridge Atmospheric Simulation Chamber (CASC). Health-relevant oxidising organic species produced during secondary organic aerosol (SOA) formation were quantified in real time using an Online Particle-bound Reactive Oxygen Species Instrument (OPROSI). Two categories of reactive oxygen species (ROS) were identified based on time series analysis: a short-lived component produced during precursor ozonolysis with a lifetime of the order of minutes, and a stable component that was long-lived on the experiment timescale (˜ 4 h). Individual organic species were monitored continuously over this time using Extractive Electrospray Ionisation (EESI) Mass Spectrometry (MS) for the particle phase and Proton Transfer Reaction (PTR) MS for the gas phase. Many first-generation oxidation products are unsaturated, and we observed multiphase aging via further ozonolysis reactions. Volatile products such as C9H14O (limonaketone) and C10H16O2 (limonaldehyde) were observed in the gas phase early in the experiment, before reacting again with ozone. Loss of C10H16O4 (7-hydroxy limononic acid) from the particle phase was surprisingly slow. A combination of reduced C = C reactivity and viscous particle formation (relative to other SOA systems) may explain this, and both scenarios were tested in the Pretty Good Aerosol Model (PG-AM). A range of characterisation measurements were also carried out to benchmark the chamber against existing facilities. This work demonstrates the utility of CASC, particularly for understanding the reactivity and health-relevant properties of organic aerosols using novel, highly time-resolved techniques.

  8. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    NARCIS (Netherlands)

    Rafieian Boroujeni, Damon; Ogieglo, Wojciech; Savenije, Tom; Lammertink, Rob G.H.

    2015-01-01

    We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to

  9. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    OpenAIRE

    Rafieian Boroujeni, Damon; Ogieglo, Wojciech; Savenije, Tom; Lammertink, Rob G.H.

    2015-01-01

    We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx

  10. Chemical and physical characteristics of phosphate rock materials of varying reactivity

    International Nuclear Information System (INIS)

    Syers, J.K.; Currie, L.D.

    1986-01-01

    Several chemical and physical properties of 10 phosphate rock (PR) materials of varying reactivity were evaluated. The highest concentrations of As and Cd were noted. Because Cd and U can accumulate in biological systems, it may be necessary to direct more attention towards the likely implications of Cd and U concentrations when evaluating a PR for direct application. Three sequential extractions with 2% citric acid may be more useful for comparing the chemical solubility of PR materials, particularly for those containing appreciable CaC0 3 . The poor relationship obtained between surface area and the solubility of the PR materials suggests that surface area plays a secondary role to chemical reactivity in controlling the solubility of a PR in a chemical extractant. A Promesh plot provided an effective method for describing the particle-size characteristics of those PR materials which occurred as sands. Fundamental characteristics, such as mean particle size and uniformity, can readily be determined from a Promesh plot. (author)

  11. Investigation on reactivity of iron nickel oxides in chemical looping dry reforming

    International Nuclear Information System (INIS)

    Huang, Zhen; He, Fang; Chen, Dezhen; Zhao, Kun; Wei, Guoqiang; Zheng, Anqing; Zhao, Zengli; Li, Haibin

    2016-01-01

    Iron nickel oxides as oxygen carriers were investigated to clarify the reaction mechanism of NiFe_2O_4 material during the chemical looping dry reforming (CLDR) process. The thermodynamic analysis showed that metallic Fe can be oxidized into Fe_3O_4 by CO_2, but metallic Ni cannot. The oxidizability of the four oxygen carriers was in the order of NiO > synthetic NiFe_2O_4 spinel > NiO-Fe_2O_3 mixed oxides > Fe_2O_3, and the reducibility sequence of their reduced products was synthetic NiFe_2O_4 spinel > NiO-Fe_2O_3 mixed oxides > Fe_2O_3 > NiO. The NiO showed the best oxidizability but it was easy to cause CH_4 cracking and its reduced product (Ni) did not recover lattice oxygen under CO_2 atmosphere. It only produced 74 mL CO for 1 g Fe_2O_3 during the CO_2 reforming because of its weak oxidizability. The Redox ability of synthetic NiFe_2O_4 was obvious higher than that of NiO-Fe_2O_3 mixed oxides due to the synergistic effect of metallic Fe-Ni in the spinel structure. 1 g synthetic NiFe_2O_4 can produce 238 mL CO, which was twice higher than that of 1 g NiO-Fe_2O_3 mixed oxides (111 mL). A part of Fe element was divorced from the NiFe_2O_4 spinel structure after one cycle, which was the major reason for degradation of reactivity of NiFe_2O_4 oxygen carrier. - Highlights: • A synergistic effect of Fe/Ni can improve the reactivity of oxygen carrier (OC). • The oxidizability sequence of four OCs is NiO > NiFe_2O_4 > mixed NiO + Fe_2O_3 > Fe_2O_3. • The reducibility sequence of four OCs is NiFe_2O_4 > mixed NiO + Fe_2O_3 > Fe_2O_3 > NiO. • The formation of Fe (Ni) alloy phase facilitates more CO_2 reduced into CO. • Part of Fe is divorced from the spinel structure, leading to the degeneration of OC reactivity.

  12. Coal structure and reactivity changes induced by chemical demineralisation

    Energy Technology Data Exchange (ETDEWEB)

    Rubiera, F.; Arenillas, A.; Pevida, C.; Garcia, R.; Pis, J.J. [Department of Energy and Environment, Instituto Nacional del Carbon, CSIC, Apartado 73, 33080 Oviedo (Spain); Steel, K.M.; Patrick, J.W. [Fuel Technology Group, School of Chemical, Environmental and Mining Engineering, Nottingham University, University Park, NG7 2RD Nottingham (United Kingdom)

    2002-12-01

    The aim of this work was to determine the influence that an advanced demineralisation procedure has on the combustion characteristics of coal. A high-volatile bituminous coal with 6.2% ash content was treated in a mixture of hydrofluoric and fluorosilicic acids (HF/H{sub 2}SiF{sub 6}). Nitric acid was used either as a pretreatment, or as a washing stage after HF/H{sub 2}SiF{sub 6} demineralisation, with an ash content as low as 0.3% being attained in the latter case. The structural changes produced by the chemical treatment were evaluated by comparison of the FTIR spectra of the raw and treated coal samples. The devolatilisation and combustibility behaviour of the samples was studied by using a thermobalance coupled to a mass spectrometer (TGA-MS) for evolved gas analysis. The combustibility characteristics of the cleaned samples were clearly improved, there being a decrease in SO{sub 2} emissions.

  13. Chemical Reactive Anchoring Lipids with Different Performance for Cell Surface Re-engineering Application.

    Science.gov (United States)

    Vabbilisetty, Pratima; Boron, Mallorie; Nie, Huan; Ozhegov, Evgeny; Sun, Xue-Long

    2018-02-28

    Introduction of selectively chemical reactive groups at the cell surface enables site-specific cell surface labeling and modification opportunity, thus facilitating the capability to study the cell surface molecular structure and function and the molecular mechanism it underlies. Further, it offers the opportunity to change or improve a cell's functionality for interest of choice. In this study, two chemical reactive anchor lipids, phosphatidylethanolamine-poly(ethylene glycol)-dibenzocyclooctyne (DSPE-PEG 2000 -DBCO) and cholesterol-PEG-dibenzocyclooctyne (CHOL-PEG 2000 -DBCO) were synthesized and their potential application for cell surface re-engineering via lipid fusion were assessed with RAW 264.7 cells as a model cell. Briefly, RAW 264.7 cells were incubated with anchor lipids under various concentrations and at different incubation times. The successful incorporation of the chemical reactive anchor lipids was confirmed by biotinylation via copper-free click chemistry, followed by streptavidin-fluorescein isothiocyanate binding. In comparison, the cholesterol-based anchor lipid afforded a higher cell membrane incorporation efficiency with less internalization than the phospholipid-based anchor lipid. Low cytotoxicity of both anchor lipids upon incorporation into the RAW 264.7 cells was observed. Further, the cell membrane residence time of the cholesterol-based anchor lipid was evaluated with confocal microscopy. This study suggests the potential cell surface re-engineering applications of the chemical reactive anchor lipids.

  14. Deposition of chemically reactive and repellent sites on biosensor chips for reduced non-specific binding.

    Science.gov (United States)

    Gandhiraman, R P; Gubala, V; Le, N C H; Nam, Le Cao Hoai; Volcke, C; Doyle, C; James, B; Daniels, S; Williams, D E

    2010-08-01

    The performances of new polymeric materials with excellent optical properties and good machinability have led the biomedical diagnostics industry to develop cheap disposable biosensor platforms appropriate for point of care applications. Zeonor, a type of cycloolefin polymer (COP), is one such polymer that presents an excellent platform for biosensor chips. These polymer substrates have to be modified to have suitable physico-chemical properties for immobilizing proteins. In this work, we have demonstrated the amine functionalization of COP substrates, by plasma enhanced chemical vapour deposition (PECVD), through codeposition of ethylene diamine and 3-aminopropyltriethoxysilane precursors, for building chemistries on the plastic chip. The elemental composition, adhesion, ageing and reactivity of the plasma polymerized film were examined. The Si-O functionality present in amino silane contributed for a good interfacial adhesion of the coating to COP substrates and also acted as a network building layer for plasma polymerization. Wet chemical modification was then carried out on the amine functionalized chips to create chemically reactive isothiocyanate sites and protein repellent fluorinated sites on the same chip. The density of the reactive and repellent sites was altered by choosing appropriate mixtures of homofunctional phenyldiisothiocyanate (PDITC), pentafluoroisothiocyanate (5FITC) and phenylisothiocyanate (PITC) compounds. By tailoring the density of reactive binding sites and protein repellent sites, the non-specific binding of ssDNA has been decreased to a significant extent. Copyright 2010 Elsevier B.V. All rights reserved.

  15. Unifying principles of irreversibility minimization for efficiency maximization in steady-flow chemically-reactive engines

    International Nuclear Information System (INIS)

    Ramakrishnan, Sankaran; Edwards, Christopher F.

    2014-01-01

    Systems research has led to the conception and development of various steady-flow, chemically-reactive, engine cycles for stationary power generation and propulsion. However, the question that remains unanswered is: What is the maximum-efficiency steady-flow chemically-reactive engine architecture permitted by physics? On the one hand the search for higher-efficiency cycles continues, often involving newer processes and devices (fuel cells, carbon separation, etc.); on the other hand the design parameters for existing cycles are continually optimized in response to improvements in device engineering. In this paper we establish that any variation in engine architecture—parametric change or process-sequence change—contributes to an efficiency increase via one of only two possible ways to minimize total irreversibility. These two principles help us unify our understanding from a large number of parametric analyses and cycle-optimization studies for any steady-flow chemically-reactive engine, and set a framework to systematically identify maximum-efficiency engine architectures. - Highlights: • A unified thermodynamic model to study chemically-reactive engine architectures is developed. • All parametric analyses of efficiency are unified by two irreversibility-minimization principles. • Variations in internal energy transfers yield a net work increase that is greater than engine irreversibility reduced. • Variations in external energy transfers yield a net work increase that is lesser than engine irreversibility reduced

  16. Chemical Reactive Anchoring Lipids with Different Performance for Cell Surface Re-engineering Application

    Science.gov (United States)

    2018-01-01

    Introduction of selectively chemical reactive groups at the cell surface enables site-specific cell surface labeling and modification opportunity, thus facilitating the capability to study the cell surface molecular structure and function and the molecular mechanism it underlies. Further, it offers the opportunity to change or improve a cell’s functionality for interest of choice. In this study, two chemical reactive anchor lipids, phosphatidylethanolamine–poly(ethylene glycol)–dibenzocyclooctyne (DSPE–PEG2000–DBCO) and cholesterol–PEG–dibenzocyclooctyne (CHOL–PEG2000–DBCO) were synthesized and their potential application for cell surface re-engineering via lipid fusion were assessed with RAW 264.7 cells as a model cell. Briefly, RAW 264.7 cells were incubated with anchor lipids under various concentrations and at different incubation times. The successful incorporation of the chemical reactive anchor lipids was confirmed by biotinylation via copper-free click chemistry, followed by streptavidin-fluorescein isothiocyanate binding. In comparison, the cholesterol-based anchor lipid afforded a higher cell membrane incorporation efficiency with less internalization than the phospholipid-based anchor lipid. Low cytotoxicity of both anchor lipids upon incorporation into the RAW 264.7 cells was observed. Further, the cell membrane residence time of the cholesterol-based anchor lipid was evaluated with confocal microscopy. This study suggests the potential cell surface re-engineering applications of the chemical reactive anchor lipids. PMID:29503972

  17. Chemical reactivity of analogous technetium(V) and rhenium(V) dioxo complexes

    International Nuclear Information System (INIS)

    Kremer, C.; Kremer, E.; Leon, A.

    1993-01-01

    All complexes of the series [MO 2 L 2 ] + (M = Tc, Re, L = ethylenediamine (en), 1,3-diaminopropane (1,3-dap)) have been synthesized and their chemical reactivities investigated. The following properties were studied: stability of the aqueous solutions at different pH values, substitution kinetics, lipophilicity and protein binding. The complexes show very similar reactivity in aqueous solution. From a radiopharmaceutical point of view, no significant difference in their in vivo behavior is expected. (author) 12 refs.; 1 fig.; 3 tabs

  18. Chemical reactivity of potential ferrocyanide precipitates in Hanford tanks with nitrates and nitrites

    International Nuclear Information System (INIS)

    Scheele, R.D.; Burger, L.L.; Tingey, J.M.; Hallen, R.T.; Lilga, M.A.

    1992-01-01

    Ferrocyanide-bearing wastes were produced at the Hanford Site during the 1950s. Safe storage of these wastes has recently drawn increased attention. As a result of these concerns, the Pacific Northwest Laboratory was chartered to investigate the chemical reactivity and explosivity of the ferrocyanide-bearing wastes. We have investigated the thermal sensitivity of synthetic wastes and ferrocyanides and observed oxidation at 130 deg. C and explosions down to 295 deg. C. Coupled with thermodynamic calculations, these thermal studies have also shown a dependence of the reactivity on the synthetic waste composition, which is dependent on the solids settling behavior. (author)

  19. Reactivation of chromosomally integrated human herpesvirus-6 by telomeric circle formation.

    Directory of Open Access Journals (Sweden)

    Bhupesh K Prusty

    Full Text Available More than 95% of the human population is infected with human herpesvirus-6 (HHV-6 during early childhood and maintains latent HHV-6 genomes either in an extra-chromosomal form or as a chromosomally integrated HHV-6 (ciHHV-6. In addition, approximately 1% of humans are born with an inheritable form of ciHHV-6 integrated into the telomeres of chromosomes. Immunosuppression and stress conditions can reactivate latent HHV-6 replication, which is associated with clinical complications and even death. We have previously shown that Chlamydia trachomatis infection reactivates ciHHV-6 and induces the formation of extra-chromosomal viral DNA in ciHHV-6 cells. Here, we propose a model and provide experimental evidence for the mechanism of ciHHV-6 reactivation. Infection with Chlamydia induced a transient shortening of telomeric ends, which subsequently led to increased telomeric circle (t-circle formation and incomplete reconstitution of circular viral genomes containing single viral direct repeat (DR. Correspondingly, short t-circles containing parts of the HHV-6 DR were detected in cells from individuals with genetically inherited ciHHV-6. Furthermore, telomere shortening induced in the absence of Chlamydia infection also caused circularization of ciHHV-6, supporting a t-circle based mechanism for ciHHV-6 reactivation.

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

    Science.gov (United States)

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

    2015-07-23

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

  1. RICE: a computer program for multicomponent chemically reactive flows at all speeds

    International Nuclear Information System (INIS)

    Rivard, W.C.; Farmer, O.A.; Butler, T.D.

    1974-11-01

    The fluid dynamics of chemically reactive mixtures are calculated at arbitrary flow speeds with the RICE program. The dynamics are governed by the two-dimensional, time-dependent Navier-Stokes equations together with the species transport equations and the mass-action rate equations for the chemical reactions. The mass and momentum equations for the mixture are solved implicitly by the ICE technique. The equations for total energy and species transport are solved explicitly while the chemical rate equations are solved implicitly with a time step that may be a submultiple of the hydrodynamic time step. Application is made to continuous wave HF chemical lasers to compute the supersonic mixing and chemical reactions that take place in the lasing cavity. (U.S.)

  2. Abiotic pyrite reactivity versus nitrate, selenate and selenite using chemical and electrochemical methods

    International Nuclear Information System (INIS)

    Ignatiadis, I.; Betelu, S.; Gaucher, E.; Tournassat, C.; Chainet, F.

    2010-01-01

    Document available in extended abstract form only. This work is part of ReCosy European project (www.recosy.eu), whose main objectives are the sound understanding of redox phenomena controlling the long-term release/retention of radionuclides in nuclear waste disposal and providing tools to apply the results to performance assessment/safety case. Redox is one of the main factor affecting speciation and mobility of redox-sensitive radionuclides. Thus, it is of a great importance to investigate the redox reactivity of the host radioactive waste formations, particularly when exposed to redox perturbations. Callovo-Oxfordian formation (COx), a clay rock known as an anoxic and reducing system, was selected in France as the most suitable location to store nuclear waste. Iron (II) sulfide, mostly constituted of pyrite (FeS 2 ), iron (II) carbonate, iron(II) bearing clays and organic matter are considered to account almost entirely for the total reducing capacity of the rock. We report here the redox reactivity of pyrite upon exposure to nitrate (N(V)), selenate (Se(VI)) and selenite (Se(IV)) that possibly occur in the nuclear storage. Both, chemical and electrochemical kinetic approaches were simultaneously conducted such as to (i) determine the kinetics parameters of the reactions and (ii) understand the kinetic mechanisms. In order to reach similar conditions that are encountered in the storage system, all experiments were realised in NaCl 0.1 M, near neutral pH solutions, and an abiotic glove box (O 2 less than 10 -8 M). Chemical approach has consisted to set in contact pyrite in grains with solutions containing respectively nitrate, selenate and selenite. Reactants and products chemical analyses, conducted at different contact times, allowed us to assess the kinetics of oxidant reduction. Electrochemical approach has consisted in the continuous or semi-continuous analysis of large surface pyrite electrodes immersed in solutions with or without oxidant (nitrate

  3. Enhancing the design of in situ chemical barriers with multicomponent reactive transport modeling

    International Nuclear Information System (INIS)

    Sevougian, S.D.; Steefel, C.I.; Yabusaki, S.B.

    1994-11-01

    This paper addresses the need for systematic control of field-scale performance in the emplacement and operation of in situ chemical treatment barriers; in particular, it addresses the issue of how the local coupling of reaction kinetics and material heterogeneities at the laboratory or bench scale can be accurately upscaled to the field. The authors have recently developed modeling analysis tools that can explicitly account for all relevant chemical reactions that accompany the transport of reagents and contaminants through a chemically and physically heterogeneous subsurface rock or soil matrix. These tools are incorporated into an enhanced design methodology for in situ chemical treatment technologies, and the new methodology is demonstrated in the ongoing design of a field experiment for the In Situ Redox Manipulation (ISRM) project at the U.S. Department of Energy (DOE) Hanford Site. The ISRM design approach, which systematically integrates bench-scale and site characterization information, provides an ideal test for the new reactive transport techniques. The need for the enhanced chemistry capability is demonstrated by an example that shows how intra-aqueous redox kinetics can affect the transport of reactive solutes. Simulations are carried out on massively parallel computer architectures to resolve the influence of multiscale heterogeneities on multicomponent, multidimensional reactive transport. The technology will soon be available to design larger-scale remediation schemes

  4. Reactive oxygen species formation during tetanic contractions in single isolated Xenopus myofibers

    OpenAIRE

    Zuo, Li; Nogueira, Leonardo; Hogan, Michael C.

    2011-01-01

    Contracting skeletal muscle produces reactive oxygen species (ROS) that have been shown to affect muscle function and adaptation. However, real-time measurement of ROS in contracting myofibers has proven to be difficult. We used amphibian (Xenopus laevis) muscle to test the hypothesis that ROS are formed during contractile activity in isolated single skeletal muscle fibers and that this contraction-induced ROS formation affects fatigue development. Single myofibers were loaded with 5 μM dihyd...

  5. Low Po2 conditions induce reactive oxygen species formation during contractions in single skeletal muscle fibers

    OpenAIRE

    Zuo, Li; Shiah, Amy; Roberts, William J.; Chien, Michael T.; Wagner, Peter D.; Hogan, Michael C.

    2013-01-01

    Contractions in whole skeletal muscle during hypoxia are known to generate reactive oxygen species (ROS); however, identification of real-time ROS formation within isolated single skeletal muscle fibers has been challenging. Consequently, there is no convincing evidence showing increased ROS production in intact contracting fibers under low Po2 conditions. Therefore, we hypothesized that intracellular ROS generation in single contracting skeletal myofibers increases during low Po2 compared wi...

  6. Consolidation of the formation sand by chemical methods

    Directory of Open Access Journals (Sweden)

    Mariana Mihočová

    2006-10-01

    Full Text Available The sand control by consolidation involves the process of injecting chemicals into the naturally unconsolidated formation to provide an in situ grain-to-grain cementation. The sand consolidation chemicals are available for some 30 years. Several types of consolidating material were tried. Presently available systems utilize solidified plastics to provide the cementation. These systems include phenol resin, phenol-formaldehyde, epoxy, furan and phenolic-furfuryl.The sand consolidation with the steam injection is a novel technique. This process provides a highly alkaline liquid phase and temperatures to 300 °C to geochemically create cements by interacting with the dirty sand.While the formation consolidation has widely applied, our experience has proved a high level of success.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-31

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

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

    International Nuclear Information System (INIS)

    Wess, T.J.; Wess, L.; Miller, A.

    1994-01-01

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

  9. Chemical pathways for the formation of ammonia in Hanford wastes

    International Nuclear Information System (INIS)

    Stock, L.M.; Pederson, L.R.

    1997-12-01

    This report reviews chemical reactions leading to the formation of ammonia in Hanford wastes. The general features of the chemistry of the organic compounds in the Hanford wastes are briefly outlined. The radiolytic and thermal free radical reactions that are responsible for the initiation and propagation of the oxidative degradation reactions of the nitrogen-containing complexants, trisodium HEDTA and tetrasodium EDTA, are outlined. In addition, the roles played by three different ionic reaction pathways for the oxidation of the same compounds and their degradation products are described as a prelude to the discussion of the formation of ammonia. The reaction pathways postulated for its formation are based on tank observations, laboratory studies with simulated and actual wastes, and the review of the scientific literature. Ammonia derives from the reduction of nitrite ion (most important), from the conversion of organic nitrogen in the complexants and their degradation products, and from radiolytic reactions of nitrous oxide and nitrogen (least important)

  10. Chemical pathways for the formation of ammonia in Hanford wastes

    Energy Technology Data Exchange (ETDEWEB)

    Stock, L.M.; Pederson, L.R.

    1997-12-01

    This report reviews chemical reactions leading to the formation of ammonia in Hanford wastes. The general features of the chemistry of the organic compounds in the Hanford wastes are briefly outlined. The radiolytic and thermal free radical reactions that are responsible for the initiation and propagation of the oxidative degradation reactions of the nitrogen-containing complexants, trisodium HEDTA and tetrasodium EDTA, are outlined. In addition, the roles played by three different ionic reaction pathways for the oxidation of the same compounds and their degradation products are described as a prelude to the discussion of the formation of ammonia. The reaction pathways postulated for its formation are based on tank observations, laboratory studies with simulated and actual wastes, and the review of the scientific literature. Ammonia derives from the reduction of nitrite ion (most important), from the conversion of organic nitrogen in the complexants and their degradation products, and from radiolytic reactions of nitrous oxide and nitrogen (least important).

  11. In situ formation of magnetite reactive barriers in soil for waste stabilization

    Science.gov (United States)

    Moore, Robert C.

    2003-01-01

    Reactive barriers containing magnetite and methods for making magnetite reactive barriers in situ in soil for sequestering soil contaminants including actinides and heavy metals, organic materials, iodine and technetium are disclosed. According to one embodiment, a two-step reagent introduction into soil takes place. In the first step, free oxygen is removed from the soil by separately injecting into the soil aqueous solutions of iron (II) salt, for example FeCl.sub.2, and base, for example NaOH or NH.sub.3 in about a 1:1 volume ratio. Then, in the second step, similar reagents are injected a second time (however, according to about a 1:2 volume ratio, iron to salt) to form magnetite. The magnetite formation is facilitated, in part, due to slow intrusion of oxygen into the soil from the surface. The invention techniques are suited to injection of reagents into soil in proximity to a contamination plume or source allowing in situ formation of the reactive barrier at the location of waste or hazardous material. Mixing of reagents to form. precipitate is mediated and enhanced through movement of reagents in soil as a result of phenomena including capillary action, movement of groundwater, soil washing and reagent injection pressure.

  12. Density functional theory study on the formation of reactive benzoquinone imines by hydrogen abstraction

    DEFF Research Database (Denmark)

    Leth, Rasmus; Rydberg, Patrik; Jørgensen, Flemming Steen

    2015-01-01

    Many drug compounds are oxidized by cytochrome P450 (CYP) enzymes to form reactive metabolites. This study presents density functional theory calculations of the CYP-mediated metabolism of acetaminophen and a series of related compounds that can form reactive metabolites by hydrogen abstraction....... The substitution pattern affects the activation barrier for hydrogen abstraction by up to 30 kJ/mol. A correlation (R(2) = 0.72) between the transition-state energies and the corresponding substrate radical energies has been established. Using this correlation is significantly less time-demanding than using...... the porphyrin model to determine the activation energies. We have used this correlation on monosubstituted phenols to rationalize the effect of the various substituents in the drug compounds. In addition to facilitating a chemical interpretation, the approach is sufficiently fast and reliable to be used...

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

    Science.gov (United States)

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

    2009-01-01

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

  14. Meteorological and chemical impacts on ozone formation: A case study in Hangzhou, China

    Science.gov (United States)

    Li, Kangwei; Chen, Linghong; Ying, Fang; White, Stephen J.; Jang, Carey; Wu, Xuecheng; Gao, Xiang; Hong, Shengmao; Shen, Jiandong; Azzi, Merched; Cen, Kefa

    2017-11-01

    Regional ozone pollution has become one of the most challenging problems in China, especially in the more economically developed and densely populated regions like Hangzhou. In this study, measurements of O3, CO, NOx and non-methane hydrocarbons (NMHCs), together with meteorological data, were obtained for the period July 1, 2013-August 15, 2013 at three sites in Hangzhou. These sites included an urban site (Zhaohui ;ZH;), a suburban site (Xiasha ;XS;) and a rural site (Qiandaohu ;QDH;). During the observation period, both ZH and XS had a higher ozone level than QDH, with exceeding rates of 41.3% and 47.8%, respectively. Elevated O3 levels in QDH were found at night, which could be explained by less prominent NO titration effect in rural area. Detailed statistical analysis of meteorological and chemical impacts on ozone formation was carried out for ZH, and higher ozone concentration was observed when the wind direction was from the east. This is possibly due to emissions of VOCs from XS, a typical chemical industrial park located in 30 km upwind area of ZH. A comprehensive comparison between three ozone episode periods and one non-episode period were made in ZH. It was concluded that elevated concentrations of precursors and temperatures, low relative humidity and wind speed and easterly-dominated wind direction contribute to urban ozone episodes in Hangzhou. VOCs reactivity analysis indicated that reactive alkenes like isoprene and isobutene contributed most to ozone formation. Three methods were applied to evaluate O3-VOCs-NOx sensitivity in ZH: VOCs/NOx ratio method, Smog Production Model (SPM) and Relative Incremental Reactivity (RIR). The results show that summer ozone in urban Hangzhou mostly presents VOCs-limited and transition region alternately. Our study implies that the increasing automobiles and VOCs emissions from upwind area could result in ozone pollution in urban Hangzhou, and synergistic reduction of VOCs and NOx will be more effective.

  15. Trifluoperazine inhibits acetaminophen-induced hepatotoxicity and hepatic reactive nitrogen formation in mice and in freshly isolated hepatocytes

    Directory of Open Access Journals (Sweden)

    Sudip Banerjee

    Full Text Available The hepatotoxicity of acetaminophen (APAP occurs by initial metabolism to N-acetyl-p-benzoquinone imine which depletes GSH and forms APAP-protein adducts. Subsequently, the reactive nitrogen species peroxynitrite is formed from nitric oxide (NO and superoxide leading to 3-nitrotyrosine in proteins. Toxicity occurs with inhibited mitochondrial function. We previously reported that in hepatocytes the nNOS (NOS1 inhibitor NANT inhibited APAP toxicity, reactive nitrogen and oxygen species formation, and mitochondrial dysfunction. In this work we examined the effect of trifluoperazine (TFP, a calmodulin antagonist that inhibits calcium induced nNOS activation, on APAP hepatotoxicity and reactive nitrogen formation in murine hepatocytes and in vivo. In freshly isolated hepatocytes TFP inhibited APAP induced toxicity, reactive nitrogen formation (NO, GSNO, and 3-nitrotyrosine in protein, reactive oxygen formation (superoxide, loss of mitochondrial membrane potential, decreased ATP production, decreased oxygen consumption rate, and increased NADH accumulation. TFP did not alter APAP induced GSH depletion in the hepatocytes or the formation of APAP protein adducts which indicated that reactive metabolite formation was not inhibited. Since we previously reported that TFP inhibits the hepatotoxicity of APAP in mice without altering hepatic APAP-protein adduct formation, we examined the APAP treated mouse livers for evidence of reactive nitrogen formation. 3-Nitrotyrosine in hepatic proteins and GSNO were significantly increased in APAP treated mouse livers and decreased in the livers of mice treated with APAP plus TFP. These data are consistent with a hypothesis that APAP hepatotoxicity occurs with altered calcium metabolism, activation of nNOS leading to increased reactive nitrogen formation, and mitochondrial dysfunction. Keywords: Acetaminophen, Neuronal nitric oxide, Oxidative stress, Mitochondria

  16. Chemical pathways for the formation of ammonia in Hanford wastes

    International Nuclear Information System (INIS)

    Stock, L.M.; Pederson, L.R.

    1997-09-01

    This report reviews chemical reactions leading to the formation of ammonia in Hanford wastes. The general features of the chemistry of the organic compounds in the Hanford wastes are briefly outlined. The radiolytic and thermal free radical reactions that are responsible for the initiation and propagation of the oxidative degradation reactions of the nitrogen-containing complexants, trisodium HEDTA and tetrasodium EDTA, are outlined. In addition, the roles played by three different ionic reaction pathways for the oxidation of the same compounds and their degradation products are described as a prelude to the discussion of the formation of ammonia. The reaction pathways postulated for its formation are based on tank observations, laboratory studies with simulated and actual wastes, and the review of the scientific literature. Ammonia derives from the reduction of nitrite ion (most important), from the conversion of organic nitrogen in the complexants and their degradation products, and from radiolytic reactions of nitrous oxide and nitrogen (least important). Reduction of nitrite ions is believed to be the most important source of ammonia. Whether by radiolytic or thermal routes, nitrite reduction reactions proceed through nitrogen dioxide, nitric oxide, the nitrosyl anion, and the hyponitrite anion. Nitrite ion is also converted into hydroxylamine, another important intermediate on the pathway to form ammonia. These reaction pathways additionally result in the formation of nitrous oxide and molecular nitrogen, whereas hydrogen formation is produced in a separate reaction sequence

  17. Chemical pathways for the formation of ammonia in Hanford wastes

    Energy Technology Data Exchange (ETDEWEB)

    Stock, L.M.; Pederson, L.R.

    1997-09-01

    This report reviews chemical reactions leading to the formation of ammonia in Hanford wastes. The general features of the chemistry of the organic compounds in the Hanford wastes are briefly outlined. The radiolytic and thermal free radical reactions that are responsible for the initiation and propagation of the oxidative degradation reactions of the nitrogen-containing complexants, trisodium HEDTA and tetrasodium EDTA, are outlined. In addition, the roles played by three different ionic reaction pathways for the oxidation of the same compounds and their degradation products are described as a prelude to the discussion of the formation of ammonia. The reaction pathways postulated for its formation are based on tank observations, laboratory studies with simulated and actual wastes, and the review of the scientific literature. Ammonia derives from the reduction of nitrite ion (most important), from the conversion of organic nitrogen in the complexants and their degradation products, and from radiolytic reactions of nitrous oxide and nitrogen (least important). Reduction of nitrite ions is believed to be the most important source of ammonia. Whether by radiolytic or thermal routes, nitrite reduction reactions proceed through nitrogen dioxide, nitric oxide, the nitrosyl anion, and the hyponitrite anion. Nitrite ion is also converted into hydroxylamine, another important intermediate on the pathway to form ammonia. These reaction pathways additionally result in the formation of nitrous oxide and molecular nitrogen, whereas hydrogen formation is produced in a separate reaction sequence.

  18. Reactive chemically modified piezoelectric crystal detectors: A new class of high-selectivity sensors

    International Nuclear Information System (INIS)

    Fadeev, A.Yu.; Filatov, A.L.; Lisichkin, G.V.

    1994-01-01

    A great number of works have focused on the study of properties of modified piezoelectric quartz crystal detectors (PQCDs) coated with sorbing substrates and on applying sensors based on them for the analysis of diluted gas mixtures and solutions. This work offers a new class of gravemetric sensors characterized by a reversible chemical reaction that occurs on their surface. Silica films are proposed as a sorbing coating of quartz detectors, and a chemical modification of a surface is suggested for covalent fixation of the necessary compounds. PQCDs were chemically modified with reactive diene derivatives that can also act as dienophiles. Hexachlorocyclopentadiene (HCCPD, resonater I) and cyclopentadiene (CPD, resonator II) were fixed on a PQCD surface in several stages. After treatment with the resonaters, the PQCD in a CPD gas phase exhibited time dependent frequency shifts from 20-100 Hz. The results suggest that there is a reversible chemical reaction on the electrode surface of resonators I and II when they interact with CPD vapors. Therefore, PQCDs modified with reactive dienes were prepared for the first time and may be employed as selective sensors for CPD

  19. Extracellular ultrathin fibers sensitive to intracellular reactive oxygen species: Formation of intercellular membrane bridges

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Se-Hui; Park, Jin-Young; Joo, Jung-Hoon; Kim, Young-Myeong; Ha, Kwon-Soo, E-mail: ksha@kangwon.ac.kr

    2011-07-15

    Membrane bridges are key cellular structures involved in intercellular communication; however, dynamics for their formation are not well understood. We demonstrated the formation and regulation of novel extracellular ultrathin fibers in NIH3T3 cells using confocal and atomic force microscopy. At adjacent regions of neighboring cells, phorbol 12-myristate 13-acetate (PMA) and glucose oxidase induced ultrathin fiber formation, which was prevented by Trolox, a reactive oxygen species (ROS) scavenger. The height of ROS-sensitive ultrathin fibers ranged from 2 to 4 nm. PMA-induced formation of ultrathin fibers was inhibited by cytochalasin D, but not by Taxol or colchicine, indicating that ultrathin fibers mainly comprise microfilaments. PMA-induced ultrathin fibers underwent dynamic structural changes, resulting in formation of intercellular membrane bridges. Thus, these fibers are formed by a mechanism(s) involving ROS and involved in formation of intercellular membrane bridges. Furthermore, ultrastructural imaging of ultrathin fibers may contribute to understanding the diverse mechanisms of cell-to-cell communication and the intercellular transfer of biomolecules, including proteins and cell organelles.

  20. (±)-2-Chloropropionic acid elevates reactive oxygen species formation in human neutrophil granulocytes

    International Nuclear Information System (INIS)

    Aam, B.B.; Fonnum, F.

    2006-01-01

    (±)-2-Chloropropionic acid (2-CPA) is a neurotoxic compound which kills cerebellar granule cells in vivo, and makes cerebellar granule cells in vitro produce reactive oxygen species (ROS). We have studied the effect of 2-CPA on ROS formation in human neutrophil granulocytes in vitro. We found an increased formation of ROS after 2-CPA exposure using three different methods; the fluorescent probe DCFH-DA and the chemiluminescent probes lucigenin and luminol. Four different inhibitors of ROS formation were tested on the cells in combination with 2-CPA to characterize the signalling pathways. The spin-trap s-PBN, the ERK1/2 inhibitor U0126 and the antioxidant Vitamin E inhibited the 2-CPA-induced ROS formation completely, while the mitochondrial transition permeability pore blocker cyclosporine A inhibited the ROS formation partly. We also found that 2-CPA induced an increased nitric oxide production in the cells by using the Griess reagent. The level of reduced glutathione, measured with the DTNB assay, was decreased after exposure to high concentrations of 2-CPA. Western blotting analysis showed that 2-CPA exposure led to an elevated phosphorylation of ERK MAP kinase. This phosphorylation was inhibited by U0126. Based on these experiments it seems like the mechanisms for 2-CPA induced toxicity involves ROS formation and is similar in neutrophil granulocytes as earlier shown in cerebellar granule cells. This also implies that 2-CPA may be immunotoxic

  1. From quantum chemical formation free energies to evaporation rates

    Directory of Open Access Journals (Sweden)

    I. K. Ortega

    2012-01-01

    Full Text Available Atmospheric new particle formation is an important source of atmospheric aerosols. Large efforts have been made during the past few years to identify which molecules are behind this phenomenon, but the actual birth mechanism of the particles is not yet well known. Quantum chemical calculations have proven to be a powerful tool to gain new insights into the very first steps of particle formation. In the present study we use formation free energies calculated by quantum chemical methods to estimate the evaporation rates of species from sulfuric acid clusters containing ammonia or dimethylamine. We have found that dimethylamine forms much more stable clusters with sulphuric acid than ammonia does. On the other hand, the existence of a very deep local minimum for clusters with two sulfuric acid molecules and two dimethylamine molecules hinders their growth to larger clusters. These results indicate that other compounds may be needed to make clusters grow to larger sizes (containing more than three sulfuric acid molecules.

  2. Ultraviolet light photobiology of the protozoan Tetrahymena pyriformis and chemical reactivation of DNA damage

    International Nuclear Information System (INIS)

    Wheeler, J.S.

    1988-01-01

    The tunable dye laser was developed in order to perform UV-B and UV-C (254-320 nm) action spectra studies on several different organisms. Using the laser, action spectra studies have been performed for Escherichia coli, Saccharomyces, Chlamydomonas, Caenorhabditis elegans, Paramecium, and Tetrahymena pyriformis. Studies generally indicate increasing LD 50 values with increasing wavelength. Two notable findings were made: (1) The action spectra does not follow the DNA absorption spectra at 280, 290 and 295 nm; (2) The repair competent/repair defective sensitization factor does not remain constant throughout the wavelength region. In addition it was found that the repair defective strain of E. coli, Bs-1, showed an increase in survival with increasing UV irradiation, at certain dose levels. Further experiments were designed to better characterize the reactivation. Tetrahymena were exposed to UV-C and reactivated with methyl methanesulfonate (MMS) and 4-nitro quinoline oxide (4-NQO). In both cases survival was seen to increase after chemical exposure. Likewise, UV-C was found to reactivate chemical damage (MMS)

  3. Properties of amorphous silicon thin films synthesized by reactive particle beam assisted chemical vapor deposition

    International Nuclear Information System (INIS)

    Choi, Sun Gyu; Wang, Seok-Joo; Park, Hyeong-Ho; Jang, Jin-Nyoung; Hong, MunPyo; Kwon, Kwang-Ho; Park, Hyung-Ho

    2010-01-01

    Amorphous silicon thin films were formed by chemical vapor deposition of reactive particle beam assisted inductively coupled plasma type with various reflector bias voltages. During the deposition, the substrate was heated at 150 o C. The effects of reflector bias voltage on the physical and chemical properties of the films were systematically studied. X-ray diffraction and Raman spectroscopy results showed that the deposited films were amorphous and the films under higher reflector voltage had higher internal energy to be easily crystallized. The chemical state of amorphous silicon films was revealed as metallic bonding of Si atoms by using X-ray photoelectron spectroscopy. An increase in reflector voltage induced an increase of surface morphology of films and optical bandgap and a decrease of photoconductivity.

  4. Chemical Characterization and Reactivity Testing of Fuel-Oxidizer Reaction Product (Test Report)

    Science.gov (United States)

    1996-01-01

    The product of incomplete reaction of monomethylhydrazine (MMH) and nitrogen tetroxide (NTO) propellants, or fuel-oxidizer reaction product (FORP), has been hypothesized as a contributory cause of an anomaly which occurred in the chamber pressure (PC) transducer tube on the Reaction Control Subsystem (RCS) aft thruster 467 on flight STS-51. A small hole was found in the titanium-alloy PC tube at the first bend below the pressure transducer. It was surmised that the hole may have been caused by heat and pressure resulting from ignition of FORP. The NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) was requested to define the chemical characteristics of FORP, characterize its reactivity, and simulate the events in a controlled environment which may have lead to the Pc-tube failure. Samples of FORP were obtained from the gas-phase reaction of MMH with NTO under laboratory conditions, the pulsed firings of RCS thrusters with modified PC tubes using varied oxidizer or fuel lead times, and the nominal RCS thruster firings at WSTF and Kaiser-Marquardt. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), accelerating rate calorimetry (ARC), ion chromatography (IC), inductively coupled plasma (ICP) spectrometry, thermogravimetric analysis (TGA) coupled to FTIR (TGA/FTIR), and mechanical impact testing were used to qualitatively and quantitatively characterize the chemical, thermal, and ignition properties of FORP. These studies showed that the composition of FORP is variable but falls within a limited range of compositions that depends on the fuel loxidizer ratio at the time of formation, composition of the post-formation atmosphere (reducing or oxidizing), and reaction or postreaction temperature. A typical composition contains methylhydrazinium nitrate (MMHN), ammonium nitrate (AN), methylammonium nitrate (MAN), and trace amounts of hydrazinium nitrate and 1,1-dimethylhydrazinium nitrate. The thermal decomposition

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

    Science.gov (United States)

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

  6. Physical-chemical model of nanodiamond formation at explosion

    International Nuclear Information System (INIS)

    Chernyshev, A.P.; Lukyanchikov, L.A.; Lyakhov, N.Z.; Pruuel, E.R.; Sheromov, M.A.; Ten, K.A.; Titov, V.M.; Tolochko, B.P.; Zhogin, I.L.; Zubkov, P.I.

    2007-01-01

    This article presents a principally new physical-chemical model of nanodiamond formation at explosion, which describes adequately all the existing experimental data on detonation synthesis of diamonds. According to this model, the detonation wave (DW) performs activation rapidly; then the reaction mixture composition keeps varying. In the diagram C-H-O, this process results in continual motion of the point imaging the reaction mixture composition. The ratio of the diamond phase amount to the condensed carbon (CC) quantity in the explosion products is defined by the width of the section this point passes over in the diamond formation zone. Motion of the point in the area below the line H-CO results in decrease of the CC amount. Diamonds are formed by the free-radical mechanism in the unloading wave, beyond the Chapman-Jouguet plane, in a media close to a liquid state

  7. Physical-chemical model of nanodiamond formation at explosion

    Energy Technology Data Exchange (ETDEWEB)

    Chernyshev, A.P. [Institute of Solid State Chemistry and Mechanochemistry SB RAS, ul. Kutateladze 18, Novosibirsk 630128 (Russian Federation); Novosibirsk State Technical University, Novosibirsk 630092 (Russian Federation); Lukyanchikov, L.A. [Lavrentiev Institute of Hydrodynamics, Novosibirsk 630090 (Russian Federation); Lyakhov, N.Z. [Institute of Solid State Chemistry and Mechanochemistry SB RAS, ul. Kutateladze 18, Novosibirsk 630128 (Russian Federation); Pruuel, E.R. [Lavrentiev Institute of Hydrodynamics, Novosibirsk 630090 (Russian Federation); Sheromov, M.A. [Budker Institute of Nuclear Physics, Novosibirsk 630090 (Russian Federation); Ten, K.A. [Lavrentiev Institute of Hydrodynamics, Novosibirsk 630090 (Russian Federation); Titov, V.M. [Lavrentiev Institute of Hydrodynamics, Novosibirsk 630090 (Russian Federation); Tolochko, B.P. [Institute of Solid State Chemistry and Mechanochemistry SB RAS, ul. Kutateladze 18, Novosibirsk 630128 (Russian Federation)]. E-mail: b.p.tolochko@inp.nsk.su; Zhogin, I.L. [Institute of Solid State Chemistry and Mechanochemistry SB RAS, ul. Kutateladze 18, Novosibirsk 630128 (Russian Federation); Zubkov, P.I. [Lavrentiev Institute of Hydrodynamics, Novosibirsk 630090 (Russian Federation)

    2007-05-21

    This article presents a principally new physical-chemical model of nanodiamond formation at explosion, which describes adequately all the existing experimental data on detonation synthesis of diamonds. According to this model, the detonation wave (DW) performs activation rapidly; then the reaction mixture composition keeps varying. In the diagram C-H-O, this process results in continual motion of the point imaging the reaction mixture composition. The ratio of the diamond phase amount to the condensed carbon (CC) quantity in the explosion products is defined by the width of the section this point passes over in the diamond formation zone. Motion of the point in the area below the line H-CO results in decrease of the CC amount. Diamonds are formed by the free-radical mechanism in the unloading wave, beyond the Chapman-Jouguet plane, in a media close to a liquid state.

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

    Directory of Open Access Journals (Sweden)

    Zhengde Tan

    2013-01-01

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

  9. Feasibility Study for the Use of Green, Bio-Based, Efficient Reactive Sorbent Material to Neutralize Chemical Warfare Agents

    Science.gov (United States)

    2012-08-02

    REPORT Feasibility study for the use of green, bio-based, efficient reactive sorbent material to neutralize chemical warfare agents 14. ABSTRACT 16...way cellulose, lignin and hemicelluloses interact as well as whole wood dissolution occurs in ILs. The present project was conducted to 1. REPORT...Feasibility study for the use of green, bio-based, efficient reactive sorbent material to neutralize chemical warfare agents Report Title ABSTRACT Over the

  10. Re-activation of degraded nickel cermet anodes - Nano-particle formation via reverse current pulses

    Science.gov (United States)

    Hauch, A.; Marchese, M.; Lanzini, A.; Graves, C.

    2018-02-01

    The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode is therefore important. In this work, we report a series of five tests on state-of-the-art Ni/YSZ-YSZ-CGObarrier-LSC/CGO cells. All cells were deliberately degraded via gas stream impurities in CO2/CO or harsh steam electrolysis operation. The cells were re-activated via a variety of reverse current treatments (RCTs). Via electrochemical impedance spectroscopy, we found that the Ni/YSZ electrode performance could be recovered via RCT, but not via constant fuel cell operation. For optimized RCT, we obtained a lower Ni/YSZ electrode resistance than the initial resistance. E.g. at 700 °C we measured fuel electrode resistance of 180 mΩ cm2, 390 mΩ cm2, and 159 mΩ cm2 before degradation, after degradation and after re-activation via RCT, respectively. Post-test SEM revealed that the RCT led to formation of nano-particles in the fuel electrode. Besides the remarkable improvement, the results also showed that RCTs can weaken Ni/YSZ interfaces and the electrode/electrolyte interface. This indicates that finding an optimum RCT profile is crucial for achieving maximum benefit.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-07-01

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

  12. Formation of metal nanoparticles by short-distance sputter deposition in a reactive ion etching chamber

    International Nuclear Information System (INIS)

    Nie Min; Meng, Dennis Desheng; Sun Kai

    2009-01-01

    A new method is reported to form metal nanoparticles by sputter deposition inside a reactive ion etching chamber with a very short target-substrate distance. The distribution and morphology of nanoparticles are found to be affected by the distance, the ion concentration, and the sputtering time. Densely distributed nanoparticles of various compositions were fabricated on the substrates that were kept at a distance of 130 μm or smaller from the target. When the distance was increased to 510 μm, island structures were formed, indicating the tendency to form continuous thin film with longer distance. The observed trend for nanoparticle formation is opposite to the previously reported mechanism for the formation of nanoparticles by sputtering. A new mechanism based on the seeding effect of the substrate is proposed to interpret the experimental results.

  13. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Damon Rafieian

    2015-09-01

    Full Text Available We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx<2, obtained by sputtering at relatively low oxygen concentration, formed rutile upon annealing in air, whereas stoichiometric films formed anatase. This route therefore presents a formation route for rutile films via lower (<500 °C temperature pathways. The dynamics of the annealing process were followed by in situ ellipsometry, showing the optical properties transformation. The final crystal structures were identified by XRD. The anatase film obtained by this deposition method displayed high carriers mobility as measured by time-resolved microwave conductance. This also confirms the high photocatalytic activity of the anatase films.

  14. Secondary organic aerosol formation from a large number of reactive man-made organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Derwent, Richard G., E-mail: r.derwent@btopenworld.com [rdscientific, Newbury, Berkshire (United Kingdom); Jenkin, Michael E. [Atmospheric Chemistry Services, Okehampton, Devon (United Kingdom); Utembe, Steven R.; Shallcross, Dudley E. [School of Chemistry, University of Bristol, Bristol (United Kingdom); Murrells, Tim P.; Passant, Neil R. [AEA Environment and Energy, Harwell International Business Centre, Oxon (United Kingdom)

    2010-07-15

    A photochemical trajectory model has been used to examine the relative propensities of a wide variety of volatile organic compounds (VOCs) emitted by human activities to form secondary organic aerosol (SOA) under one set of highly idealised conditions representing northwest Europe. This study applied a detailed speciated VOC emission inventory and the Master Chemical Mechanism version 3.1 (MCM v3.1) gas phase chemistry, coupled with an optimised representation of gas-aerosol absorptive partitioning of 365 oxygenated chemical reaction product species. In all, SOA formation was estimated from the atmospheric oxidation of 113 emitted VOCs. A number of aromatic compounds, together with some alkanes and terpenes, showed significant propensities to form SOA. When these propensities were folded into a detailed speciated emission inventory, 15 organic compounds together accounted for 97% of the SOA formation potential of UK man made VOC emissions and 30 emission source categories accounted for 87% of this potential. After road transport and the chemical industry, SOA formation was dominated by the solvents sector which accounted for 28% of the SOA formation potential.

  15. Modeling of altered layer formation during reactive ion etching of GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Mutzke, A. [Max-Planck-Institute of Plasmaphysics, EURATOM Association, D-17491 Greifswald (Germany); Rai, A., E-mail: Abha.Rai@ipp.mpg.de [Max-Planck-Institute of Plasmaphysics, EURATOM Association, D-17491 Greifswald (Germany); Schneider, R.; Angelin, E.J.; Hippler, R. [Institute of Physics, Ernst-Moritz-Arndt-University Greifswald, Felix-Hausdorff-Str.6, D-17489 Greifswald (Germany)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Experimental result showing the preferential sputtering of GaAs (150 keV Ar{sup +} and thermal O on GaAs) during reactive ion beam etching (RIBE) has been reported. Black-Right-Pointing-Pointer A model based on binary collisions (SDTrimSP) is presented to simulate RIBE. Black-Right-Pointing-Pointer The model is used to explain the reported experimental data and also the results by Grigonis and co-workers [1]. - Abstract: The binary collision based SDTrimSP model has been used to simulate the reactive ion beam etching (RIBE) of GaAs in the presence of energetic Ar ions and thermal O atoms. It includes the collisional effects, diffusive processes and chemical reactions taking place in the system. The model parameters are fitted using the experimental observations of Grigonis and co-workers [1] and validated with the experimental results obtained during the GaAs ion etching presented in this paper. A detailed analysis is presented to understand the effect of the diffusive processes and the role of O during RIBE of GaAs. It is shown how the presence of damage caused by the energetic Ar coupled with the presence of thermal O opens up chemical reaction channels which eventually leads to the preferential sputtering of Ga observed at the ion etching facility at University of Greifswald.

  16. Formation of Sulfonyl Aromatic Alcohols by Electrolysis of a Bisazo Reactive Dye

    Directory of Open Access Journals (Sweden)

    María P. Elizalde-González

    2012-12-01

    Full Text Available Five sulfonyl aromatic alcohols, namely 4-((2-hydroxyethylsulfonylphenol, 4-((2-(2-((4-hydroxyphenylsulfonylethoxyvinylsulfonylphenol, 4-(ethylsulfonylphenol, 4-(vinylsulfonylphenol and 5-((4-aminophenylsulfonyl-2-penten-1-ol were identified by LC-ESI-Qq-TOF-MS as products formed by electrolysis of the bisazo reactive dye Reactive Black 5 (RB5. Since electrolyses were performed in an undivided cell equipped with Ni electrodes in alkaline medium, amines like 4-(2-methoxyethylsulfonylbenzene-amine (MEBA with m/z 216 were also suspected to be formed due to the plausible chemical reaction in the bulk or the cathodic reduction of RB5 and its oxidation by-products. Aiming to check this hypothesis, a method was used for the preparation of MEBA with 98% purity, via chemical reduction also of the dye RB5. The logP of the synthesized sulfonyl aromatic compounds was calculated and their logkw values were determined chromatographically. These data were discussed in regard to the relationship between hydrophobicity/lipophilicity and toxicity.

  17. Hydrous Ferric Oxides in Sediment Catalyze Formation of Reactive Oxygen Species during Sulfide Oxidation

    Directory of Open Access Journals (Sweden)

    Sarah A. Murphy

    2016-11-01

    Full Text Available Abstract: This article describes the formation of reactive oxygen species as a result of the oxidation of dissolved sulfide by Fe(III-containing sediments suspended in oxygenated seawater over the pH range 7.00 and 8.25. Sediment samples were obtained from across the coastal littoral zone in South Carolina, US, at locations from the beach edge to the forested edge of a Spartina dominated estuarine salt marsh and suspended in aerated seawater. Reactive oxygen species (superoxide and hydrogen peroxide production was initiated in sediment suspensions by the addition of sodium bisulfide. The subsequent loss of HS-, formation of Fe(II (as indicated by Ferrozine, and superoxide and hydrogen peroxide were monitored over time. The concentration of superoxide rose from the baseline and then persisted at an apparent steady state concentration of approximately 500 nanomolar at pH 8.25 and 200 nanomolar at pH 7.00 respectively until >97% hydrogen sulfide was consumed. Measured superoxide was used to predict hydrogen peroxide yield based on superoxide dismutation. Dismutation alone quantitatively predicted hydrogen peroxide formation at pH 8.25 but over predicted hydrogen peroxide formation at pH 7 by a factor of approximately 102. Experiments conducted with episodic spikes of added hydrogen peroxide indicated rapid hydrogen peroxide consumption could account for its apparent low instantaneous yield, presumably the result of its reaction with Fe(II species, polysulfides or bisulfite. All sediment samples were characterized for total Fe, Cu, Mn, Ni, Co and hydrous ferric oxide by acid extraction followed by mass spectrometric or spectroscopic characterization. Sediments with the highest loadings of hydrous ferric oxide were the only sediments that produced significant dissolved Fe(II species or ROS as a result of sulfide exposure.

  18. Chemical Reactivity Testing for the National Spent Nuclear Fuel Program. Quality Assurance Project Plan

    International Nuclear Information System (INIS)

    Newsom, H.C.

    1999-01-01

    This quality assurance project plan (QAPjP) summarizes requirements used by Lockheed Martin Energy Systems, Incorporated (LMES) Development Division at Y-12 for conducting chemical reactivity testing of Department of Energy (DOE) owned spent nuclear fuel, sponsored by the National Spent Nuclear Fuel Program (NSNFP). The requirements are based on the NSNFP Statement of Work PRO-007 (Statement of Work for Laboratory Determination of Uranium Hydride Oxidation Reaction Kinetics.) This QAPjP will utilize the quality assurance program at Y-12, QA-101PD, revision 1, and existing implementing procedures for the most part in meeting the NSNFP Statement of Work PRO-007 requirements, exceptions will be noted

  19. Chemical Reactivity and Spectroscopy Explored From QM/MM Molecular Dynamics Simulations Using the LIO Code

    Directory of Open Access Journals (Sweden)

    Juan P. Marcolongo

    2018-03-01

    Full Text Available In this work we present the current advances in the development and the applications of LIO, a lab-made code designed for density functional theory calculations in graphical processing units (GPU, that can be coupled with different classical molecular dynamics engines. This code has been thoroughly optimized to perform efficient molecular dynamics simulations at the QM/MM DFT level, allowing for an exhaustive sampling of the configurational space. Selected examples are presented for the description of chemical reactivity in terms of free energy profiles, and also for the computation of optical properties, such as vibrational and electronic spectra in solvent and protein environments.

  20. Chemical reactivity and spectroscopy explored from QM/MM molecular dynamics simulations using the LIO code

    Science.gov (United States)

    Marcolongo, Juan P.; Zeida, Ari; Semelak, Jonathan A.; Foglia, Nicolás O.; Morzan, Uriel N.; Estrin, Dario A.; González Lebrero, Mariano C.; Scherlis, Damián A.

    2018-03-01

    In this work we present the current advances in the development and the applications of LIO, a lab-made code designed for density functional theory calculations in graphical processing units (GPU), that can be coupled with different classical molecular dynamics engines. This code has been thoroughly optimized to perform efficient molecular dynamics simulations at the QM/MM DFT level, allowing for an exhaustive sampling of the configurational space. Selected examples are presented for the description of chemical reactivity in terms of free energy profiles, and also for the computation of optical properties, such as vibrational and electronic spectra in solvent and protein environments.

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

    Science.gov (United States)

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

    2011-03-01

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

  2. Young Investigator Proposal, Research Area 7.4 Reactive Chemical Systems: Multifunctional, Bimetallic Nanomaterials Prepared by Atomic Layer Electroless Deposition

    Science.gov (United States)

    2017-09-30

    Report: Young Investigator Proposal, Research Area 7.4 Reactive Chemical Systems: Multifunctional, Bimetallic Nanomaterials Prepared by Atomic Layer ...Chemical Systems: Multifunctional, Bimetallic Nanomaterials Prepared by Atomic Layer Electroless Deposition Report Term: 0-Other Email: pcappillino... Layer Electroless Deposition (ALED, Figure 1) is the ability to tune growth mechanism, hence growth morphology, by altering conditions. In this

  3. Efficient modeling of reactive transport phenomena by a multispecies random walk coupled to chemical equilibrium

    International Nuclear Information System (INIS)

    Pfingsten, W.

    1996-01-01

    Safety assessments for radioactive waste repositories require a detailed knowledge of physical, chemical, hydrological, and geological processes for long time spans. In the past, individual models for hydraulics, transport, or geochemical processes were developed more or less separately to great sophistication for the individual processes. Such processes are especially important in the near field of a waste repository. Attempts have been made to couple at least two individual processes to get a more adequate description of geochemical systems. These models are called coupled codes; they couple predominantly a multicomponent transport model with a chemical reaction model. Here reactive transport is modeled by the sequentially coupled code MCOTAC that couples one-dimensional advective, dispersive, and diffusive transport with chemical equilibrium complexation and precipitation/dissolution reactions in a porous medium. Transport, described by a random walk of multispecies particles, and chemical equilibrium calculations are solved separately, coupled only by an exchange term. The modular-structured code was applied to incongruent dissolution of hydrated silicate gels, to movement of multiple solid front systems, and to an artificial, numerically difficult heterogeneous redox problem. These applications show promising features with respect to applicability to relevant problems and possibilities of extensions

  4. [Formation mechanism and chemical safety of nonintentional chemical substances present in chlorinated drinking water and wastewater].

    Science.gov (United States)

    Onodera, Sukeo

    2010-09-01

    This paper reviews the formation mechanism and chemical safety of nonintentional chemical substances (NICS) present in chlorine-treated water containing organic contaminants. Undesirable compounds, i.e., NICS, may be formed under certain conditions when chlorine reacts with organic matter. The rate and extent of chlorine consumption with organics are strongly dependent on their chemical structures, particularly whether double bonds or sulfur and nitrogen atoms occur in the molecules. Organothiophosphorus pesticides (P=S type) are easily oxidized to their phosphorus compounds (P=O type) in chlorinated water containing HOCl as little as 0.5 mg/l, resulting in an increase in cholinesterase-inhibitory activity. Chlorination of phenols in water also produces a series of highly chlorinated compounds, including chlorophenols, chloroquinones, chlorinated carboxylic acids, and polychlorinated phenoxyphenols (PCPPs). In some of these chloroquinones, 2,6-dichloroalkylsemiquinones exhibit a strong mutagenic response as do positive controls used in the Ames test. 2-phenoxyphenols in these PCPPs are particularly interesting, as they are present in the chlorine-treated phenol solution and they are also precursors (predioxins) of the highly toxic chlorinated dioxins. Polynuclear aromatic hydrocarbons (PAHs) were found to undergo chemical changes due to hypochlorite reactions to give chloro-substituted PAHs, oxygenated (quinones) and hydroxylated (phenols) compounds, but they exhibit a lower mutagenic response. In addition, field work was performed in river water and drinking water to obtain information on chemical distribution and their safety, and the results are compared with those obtained in the model chlorination experiments.

  5. Quantum chemical study of the structure, spectroscopy and reactivity of NO+.(H2O) n=1-5 clusters.

    Science.gov (United States)

    Linton, Kirsty A; Wright, Timothy G; Besley, Nicholas A

    2018-03-13

    Quantum chemical methods including Møller-Plesset perturbation (MP2) theory and density functional theory (DFT) have been used to study the structure, spectroscopy and reactivity of NO + (H 2 O) n =1-5 clusters. MP2/6-311++G** calculations are shown to describe the structure and spectroscopy of the clusters well. DFT calculations with exchange-correlation functionals with a low fraction of Hartree-Fock exchange give a binding energy of NO + (H 2 O) that is too high and incorrectly predict the lowest energy structure of NO + (H 2 O) 2 , and this error may be associated with a delocalization of charge onto the water molecule directly binding to NO + Ab initio molecular dynamics (AIMD) simulations were performed to study the NO + (H 2 O) 5 [Formula: see text] H + (H 2 O) 4 + HONO reaction to investigate the formation of HONO from NO + (H 2 O) 5 Whether an intracluster reaction to form HONO is observed depends on the level of electronic structure theory used. Of note is that methods that accurately describe the relative energies of the product and reactant clusters did not show reactions on the timescales studied. This suggests that in the upper atmosphere the reaction may occur owing to the energy present in the NO + (H 2 O) 5 complex following its formation.This article is part of the theme issue 'Modern theoretical chemistry'. © 2018 The Author(s).

  6. The formation and reactivity of the μ+ molecular ion NeMu+

    International Nuclear Information System (INIS)

    Fleming, D.G.; Mikula, R.J.; Senba, M.; Garner, D.M.; Arseneau, D.J.

    1983-06-01

    Evidence for the formation and reactivity of the positive muon molecular ion NeMu + at room temperature in a low pressure Ne moderator to which trace amounts of Xe, CH 4 , NH 3 or He have been added, is reported. A two component relaxation of the diamagnetic muon spin rotation (μSR) signal is seen upon the addition of trace amounts of Xe to Ne; a fast relaxing component with bimolecular rate constant (3.6+-0.6) x 10 -10 cc atom -1 s -1 is thought to be due to thermal muonium formation in a charge exchange process while the other slow relaxing component is attributed to a muon transfer reaction, as in proton transfer studies. With CH 4 or NH 3 added to Ne there is, at most, only a very slow relaxation seen, even though thermal muonium formation is expected, in analogy with Xe. These latter results may be due to very fast, possibly tunneling-assisted, muon transfer reactions, the first time that such processes have been at all characterized

  7. Anxiety-induced plasma norepinephrine augmentation increases reactive oxygen species formation by monocytes in essential hypertension.

    Science.gov (United States)

    Yasunari, Kenichi; Matsui, Tokuzo; Maeda, Kensaku; Nakamura, Munehiro; Watanabe, Takanori; Kiriike, Nobuo

    2006-06-01

    An association between anxiety and depression and increased blood pressure (BP) and cardiovascular disease risk has not been firmly established. We examined the hypothesis that anxiety and depression lead to increased plasma catecholamines and to production of reactive oxygen species (ROS) by mononuclear cells (MNC) in hypertensive individuals. We also studied the role of BP in this effect. In Protocol 1, a cross-sectional study was performed in 146 hypertensive patients to evaluate whether anxiety and depression affect BP and ROS formation by MNC through increasing plasma catecholamines. In Protocol 2, a 6-month randomized controlled trial using a subtherapeutic dose of the alpha(1)-adrenergic receptor antagonist doxazosin (1 mg/day) versus placebo in 86 patients with essential hypertension was performed to determine whether the increase in ROS formation by MNC was independent of BP. In Protocol 1, a significant relationship was observed between the following: trait anxiety and plasma norepinephrine (r = 0.32, P anxiety may increase plasma norepinephrine and increase ROS formation by MNC independent of BP in hypertensive patients.

  8. Nicorandil prevents sirolimus-induced production of reactive oxygen species, endothelial dysfunction, and thrombus formation

    Directory of Open Access Journals (Sweden)

    Ken Aizawa

    2015-03-01

    Full Text Available Sirolimus (SRL is widely used to prevent restenosis after percutaneous coronary intervention. However, its beneficial effect is hampered by complications of thrombosis. Several studies imply that reactive oxygen species (ROS play a critical role in endothelial dysfunction and thrombus formation. The present study investigated the protective effect of nicorandil (NIC, an anti-angina agent, on SRL-associated thrombosis. In human coronary artery endothelial cells (HCAECs, SRL stimulated ROS production, which was prevented by co-treatment with NIC. The preventive effect of NIC on ROS was abolished by 5-hydroxydecanoate but not by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. NIC also inhibited SRL-induced up-regulation of NADPH oxidase subunit p22phox mRNA. Co-treatment with NIC and SRL significantly up-regulated superoxide dismutase 2. NIC treatment significantly improved SRL-induced decrease in viability of HCAECs. The functional relevance of the preventive effects of NIC on SRL-induced ROS production and impairment of endothelial viability was investigated in a mouse model of thrombosis. Pretreatment with NIC inhibited the SRL-induced acceleration of FeCl3-initiated thrombus formation and ROS production in the testicular arteries of mice. In conclusion, NIC prevented SRL-induced thrombus formation, presumably due to the reduction of ROS and to endothelial protection. The therapeutic efficacy of NIC could represent an additional option in the prevention of SRL-related thrombosis.

  9. Chemically Treated 3D Printed Polymer Scaffolds for Biomineral Formation.

    Science.gov (United States)

    Jackson, Richard J; Patrick, P Stephen; Page, Kristopher; Powell, Michael J; Lythgoe, Mark F; Miodownik, Mark A; Parkin, Ivan P; Carmalt, Claire J; Kalber, Tammy L; Bear, Joseph C

    2018-04-30

    We present the synthesis of nylon-12 scaffolds by 3D printing and demonstrate their versatility as matrices for cell growth, differentiation, and biomineral formation. We demonstrate that the porous nature of the printed parts makes them ideal for the direct incorporation of preformed nanomaterials or material precursors, leading to nanocomposites with very different properties and environments for cell growth. Additives such as those derived from sources such as tetraethyl orthosilicate applied at a low temperature promote successful cell growth, due partly to the high surface area of the porous matrix. The incorporation of presynthesized iron oxide nanoparticles led to a material that showed rapid heating in response to an applied ac magnetic field, an excellent property for use in gene expression and, with further improvement, chemical-free sterilization. These methods also avoid changing polymer feedstocks and contaminating or even damaging commonly used selective laser sintering printers. The chemically treated 3D printed matrices presented herein have great potential for use in addressing current issues surrounding bone grafting, implants, and skeletal repair, and a wide variety of possible incorporated material combinations could impact many other areas.

  10. Fast formation of hydrophilic and reactive polymer micropatterns by photocatalytic lithography method

    International Nuclear Information System (INIS)

    Chang, Chi-Jung; Wang, Chih-Feng; Chen, Jem-Kun; Hsieh, Chih-Chiao; Chen, Po-An

    2013-01-01

    An approach is developed for the fast formation of a hydrophilic pattern on superhydrophobic substrates with good contrast due to the large wettability contrast between superhydrophobic and superhydrophilic areas. It can be used for forming a polymer pattern with reactive functional groups. TiO 2 nanoparticles were grafted with long alkyl chains and then coated on substrates to produce superhydrophobic films. Photocatalytic degradation of the grafted alkyl chains was effected with UV light irradiation and resulted in transition from superhydrophobicity to superhydrophilicity. After UV light irradiation through a mask for 30 s, dyes or polymers were adsorbed on the photoinduced superhydrophilic areas to make micropatterns. The photoinduced superhydrophilic switching properties can be tuned by changing the alkyl chain length. The ninhydrin assay was adapted to identify free amino groups of polymers on the patterned area. Polymer patterns with free amino groups can be achieved.

  11. Conclusive evidence of abrupt coagulation inside the void during cyclic nanoparticle formation in reactive plasma

    International Nuclear Information System (INIS)

    Wetering, F. M. J. H. van de; Nijdam, S.; Beckers, J.

    2016-01-01

    In this letter, we present scanning electron microscopy (SEM) results that confirm in a direct way our earlier explanation of an abrupt coagulation event as the cause for the void hiccup. In a recent paper, we reported on the fast and interrupted expansion of voids in a reactive dusty argon–acetylene plasma. The voids appeared one after the other, each showing a peculiar, though reproducible, behavior of successive periods of fast expansion, abrupt contraction, and continued expansion. The abrupt contraction was termed “hiccup” and was related to collective coagulation of a new generation of nanoparticles growing in the void using relatively indirect methods: electron density measurements and optical emission spectroscopy. In this letter, we present conclusive evidence using SEM of particles collected at different moments in time spanning several growth cycles, which enables us to follow the nanoparticle formation process in great detail.

  12. Formation of novel reactive intermediate by electron-laser dual beam irradiation

    International Nuclear Information System (INIS)

    Ishida, Akito; Takamuku, Setsuo

    1992-01-01

    The pulse radiolysis system of the Institute of Scientific and Industrial Research, Osaka University, (ISIR) has been progressed to observe a highly reactive species, which is produced by successive irradiation of electron and laser or of CW-UV-light and electron. The dual beam irradiation system, which consists of the beam synchronization system, the optical alignment, and the measurement system, is described in detail. Dual beam irradiation studies on 2-methylbenzophenone and some compounds with a C=N bond have been carried out by use of this system. Pulse radiolysis of 2-methylbenzophenone in benzene induced formation of an unstable photoenol via the triplet state, which was irradiated by a visible laser pulse to give dihydroanthrone. Pulse radiolysis of syn-benzalaniline and a nitrileylide in 2-methyltetrahydrofuran, which were produced by steady state photoirradiation at low temperature, enabled us to observe their very unstable radical anions. (author)

  13. Fast formation of hydrophilic and reactive polymer micropatterns by photocatalytic lithography method

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chi-Jung, E-mail: changcj@fcu.edu.tw [Department of Chemical Engineering, Feng Chia University, 100, Wenhwa Road, Seatwen, Taichung 407, Taiwan (China); Wang, Chih-Feng [Department of Materials Science and Engineering, I-Shou University, 1, Syuecheng Road, Dashu District, Kaohsiung 840, Taiwan (China); Chen, Jem-Kun [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Road, Taipei 106, Taiwan (China); Hsieh, Chih-Chiao; Chen, Po-An [Department of Chemical Engineering, Feng Chia University, 100, Wenhwa Road, Seatwen, Taichung 407, Taiwan (China)

    2013-12-01

    An approach is developed for the fast formation of a hydrophilic pattern on superhydrophobic substrates with good contrast due to the large wettability contrast between superhydrophobic and superhydrophilic areas. It can be used for forming a polymer pattern with reactive functional groups. TiO{sub 2} nanoparticles were grafted with long alkyl chains and then coated on substrates to produce superhydrophobic films. Photocatalytic degradation of the grafted alkyl chains was effected with UV light irradiation and resulted in transition from superhydrophobicity to superhydrophilicity. After UV light irradiation through a mask for 30 s, dyes or polymers were adsorbed on the photoinduced superhydrophilic areas to make micropatterns. The photoinduced superhydrophilic switching properties can be tuned by changing the alkyl chain length. The ninhydrin assay was adapted to identify free amino groups of polymers on the patterned area. Polymer patterns with free amino groups can be achieved.

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

    Science.gov (United States)

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

    2017-04-01

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

  15. Adsorption of a reactive dye on chemically modified activated carbons--influence of pH.

    Science.gov (United States)

    Orfão, J J M; Silva, A I M; Pereira, J C V; Barata, S A; Fonseca, I M; Faria, P C C; Pereira, M F R

    2006-04-15

    The surface chemistry of a commercial activated carbon with a slightly basic nature was modified by appropriate treatments in order to obtain two additional samples, respectively with acidic and basic properties, without changing its textural parameters significantly. Different techniques (N2 adsorption at 77 K, temperature programmed desorption, and determination of acidity, basicity, and pH at the point of zero charge) were used to characterize the adsorbents. Kinetic and equilibrium adsorption data of a selected textile reactive dye (Rifafix Red 3BN, C.I. reactive red 241) on the mentioned materials were obtained at the pH values of 2, 7, and 12. The kinetic curves are fitted using the second-order model. The respective rate constants seem to diminish progressively with the initial concentration for the more diluted solutions tested, reaching a constant value at higher concentrations, which depends on the experimental system under consideration (adsorbent and pH). In general, the Langmuir model provides the best fit for the equilibrium data. The different uptakes obtained are discussed in relation to the surface chemical properties of the adsorbents. It is shown that the adsorption of the reactive (anionic) dye on the basic sample (prepared by thermal treatment under H2 flow at 700 degrees C) is favored. This conclusion is explained on the basis of the dispersive and electrostatic interactions involved. Moreover, it is also shown that the optimal adsorption condition for all the activated carbons tested corresponds to solution pH values not higher than the pH(pzc) of the adsorbents, which may be interpreted by taking into account the electrostatic forces present.

  16. The chemical reactivity of the Martian soil and implications for future missions

    Science.gov (United States)

    Zent, Aaron P.; Mckay, Christopher P.

    1994-01-01

    Possible interpretations of the results of the Viking Biology Experiments suggest that greater than 1 ppm of a thermally labile oxidant, perhaps H2O2, and about 10 ppm of a thermally stable oxidant are present in the martian soil. We reexamine these results and discuss implications for future missions, the search for organics on Mars, and the possible health and engineering effects for human exploration. We conclude that further characterization of the reactivity of the martian regolith materials is warrented-although if our present understanding is correct the oxidant does not pose a hazard to humans. There are difficulties in explaining the reactivity of the Martian soil by oxidants. Most bulk phase compounds that are capable of oxidizing H2O to O2 per the Gas Exchange Experiment (GEx) are thermally labile or unstable against reduction by atmospheric CO2. Models invoking trapped O2 or peroxynitrates (NOO2(-)) require an unlikely geologic history for the Viking Lander 2 site. Most suggested oxidants, including H2O2, are expected to decompose rapidly under martian UV. Nonetheless, we conclude that the best model for the martian soil contains oxidants produced by heterogeneous chemical reactions with a photochemically produced atmospheric oxidant. The GEx results may be due to catalytic decomposition of an unstable oxidizing material by H2O. We show that interfacial reaction sites covering less than 1% of the available soil surfaces could explain the Viking Biology Experiments results.

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

    Directory of Open Access Journals (Sweden)

    Valentina V. Utochnikova

    2012-01-01

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

  18. Reactive Ion Etching as Cleaning Method Post Chemical Mechanical Polishing for Phase Change Memory Device

    International Nuclear Information System (INIS)

    Min, Zhong; Zhi-Tang, Song; Bo, Liu; Song-Lin, Feng; Bomy, Chen

    2008-01-01

    In order to improve nano-scale phase change memory performance, a super-clean interface should be obtained after chemical mechanical polishing (CMP) of Ge 2 Sb 2 Te 5 phase change films. We use reactive ion etching (RIE) as the cleaning method. The cleaning effect is analysed by scanning electron microscopy and an energy dispersive spectrometer. The results show that particle residue on the surface has been removed. Meanwhile, Ge 2 Sb 2 Te 5 material stoichiometric content ratios are unchanged. After the top electrode is deposited, current-voltage characteristics test demonstrates that the set threshold voltage is reduced from 13 V to 2.7V and the threshold current from 0.1mA to 0.025mA. Furthermore, we analyse the RIE cleaning principle and compare it with the ultrasonic method

  19. Formation and characterization of titanium nitride and titanium carbide films prepared by reactive sputtering

    International Nuclear Information System (INIS)

    Sundgren, J.-E.

    1982-01-01

    Titanium has been reactively r.f. sputtered in mixed Ar-N 2 and Ar-CH 4 discharges on to substrates held at 775 K. The films obtained have been characterized by scanning electron microscopy, X-ray diffraction and by measurements of hardness and electrical resistivity. The compositions of the films have been determined using Auger electron spectroscopy. The processes occurring both on substrates and target surfaces have been studied and it is shown that the latter is of great importance for the composition and structure of deposited films. Titanium nitride films of full density and with electrical resistivity and hardness values close to those of bulk TiN were only obtained in a narrow range close to the stoichiometric composition. Titanium carbide films grown on non-biased substrates were found to have an open structure and thus a low density. A bias applied to the substrate, however, improved the quality of the films. It is also shown that the heat of formation of the compounds plays an important role in the formation of carbides and nitrides. A large value promotes the development of large grains and dense structures. (Auth.)

  20. Computer tool to evaluate the cue reactivity of chemically dependent individuals.

    Science.gov (United States)

    Silva, Meire Luci da; Frère, Annie France; Oliveira, Henrique Jesus Quintino de; Martucci Neto, Helio; Scardovelli, Terigi Augusto

    2017-03-01

    Anxiety is one of the major influences on the dropout of relapse and treatment of substance abuse treatment. Chemically dependent individuals need (CDI) to be aware of their emotional state in situations of risk during their treatment. Many patients do not agree with the diagnosis of the therapist when considering them vulnerable to environmental stimuli related to drugs. This research presents a cue reactivity detection tool based on a device acquiring physiological signals connected to personal computer. Depending on the variations of the emotional state of the drug addict, alteration of the physiological signals will be detected by the computer tool (CT) which will modify the displayed virtual sets without intervention of the therapist. Developed in 3ds Max® software, the CT is composed of scenarios and objects that are in the habit of marijuana and cocaine dependent individual's daily life. The interaction with the environment is accomplished using a Human-Computer Interface (HCI) that converts incoming physiological signals indicating anxiety state into commands that change the scenes. Anxiety was characterized by the average variability from cardiac and respiratory rate of 30 volunteers submitted stress environment situations. To evaluate the effectiveness of cue reactivity a total of 50 volunteers who were marijuana, cocaine or both dependent were accompanied. Prior to CT, the results demonstrated a poor correlation between the therapists' predictions and those of the chemically dependent individuals. After exposure to the CT, there was a significant increase of 73% in awareness of the risks of relapse. We confirmed the hypothesis that the CT, controlled only by physiological signals, increases the perception of vulnerability to risk situations of individuals with dependence on marijuana, cocaine or both. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  1. Methyl salicylate: a reactive chemical warfare agent surrogate to detect reaction with hypochlorite.

    Science.gov (United States)

    Salter, W Bruce; Owens, Jeffery R; Wander, Joseph D

    2011-11-01

    Methyl salicylate (MeS) has a rich history as an inert physical simulant for the chemical warfare agents sulfur mustard and soman, where it is used extensively for liquid- and vapor-permeation testing. Here we demonstrate possible utility of MeS as a reactivity simulant for chlorine-based decontaminants. In these experiments MeS was reacted with sodium hypochlorite varying stoichiometry, temperature, reaction time, and pH. No colored oxidation products were observed; however, chlorination of the aromatic ring occurred ortho (methyl 3-chlorosalicylate) and para (methyl 5-chlorosalicylate) to the position bearing the -OH group in both the mono- and disubstituted forms. The monosubstituted para product accumulated initially, and the ortho and 3,5-dichloro products formed over the next several hours. Yields from reactions conducted below pH 11 declined rapidly with decreasing pH. Reactions run at 40 °C produced predominantly para substitution, while those run at 0 °C produced lower yields of ortho- and para-substituted products. Reactions were also carried out on textile substrates of cotton, 50/50 nylon-cotton, and a meta aramid. The textile data broadly reproduced reaction times and stoichiometry observed in the liquid phase, but are complicated by physical and possibly chemical interactions with the fabric. These data indicate that, for hypochlorite-containing neutralizing agents operating at strongly alkaline pH, one can expect MeS to react stoichiometrically with the hypochlorite it encounters. This suggests utility of MeS in lieu of such highly hazardous surrogates as monochloroalkyl sulfides as a simulant for threat scenarios involving the stoichiometric decomposition of sulfur mustard. Specifically, the extent of coverage of the simulant on a fabric by the neutralizing agent can be directly measured. Similar reactivity toward other halogen oxidizing agents is likely but remains to be demonstrated.

  2. Experimental investigation of aminoacetonitrile formation through the Strecker synthesis in astrophysical-like conditions: reactivity of methanimine (CH2NH), ammonia (NH3), and hydrogen cyanide (HCN)

    Science.gov (United States)

    Danger, G.; Borget, F.; Chomat, M.; Duvernay, F.; Theulé, P.; Guillemin, J.-C.; Le Sergeant D'Hendecourt, L.; Chiavassa, T.

    2011-11-01

    Context. Studing chemical reactivity in astrophysical environments is an important means for improving our understanding of the origin of the organic matter in molecular clouds, in protoplanetary disks, and possibly, as a final destination, in our solar system. Laboratory simulations of the reactivity of ice analogs provide important insight into the reactivity in these environments. Here, we use these experimental simulations to investigate the Strecker synthesis leading to the formation of aminoacetonitrile in astrophysical-like conditions. The aminoacetonitrile is an interesting compound because it was detected in SgrB2, hence could be a precursor of the smallest amino acid molecule, glycine, in astrophysical environments. Aims: We present the first experimental investigation of the formation of aminoacetonitrile NH2CH2CN from the thermal processing of ices including methanimine (CH2NH), ammonia (NH3), and hydrogen cyanide (HCN) in interstellar-like conditions without VUV photons or particules. Methods: We use Fourier Transform InfraRed (FTIR) spectroscopy to monitor the ice evolution during its warming. Infrared spectroscopy and mass spectroscopy are then used to identify the aminoacetonitrile formation. Results: We demonstrate that methanimine can react with -CN during the warming of ice analogs containing at 20 K methanimine, ammonia, and [NH4+ -CN] salt. During the ice warming, this reaction leads to the formation of poly(methylene-imine) polymers. The polymer length depend on the initial ratio of mass contained in methanimine to that in the [NH4+ -CN] salt. In a methanimine excess, long polymers are formed. As the methanimine is progressively diluted in the [NH4+ -CN] salt, the polymer length decreases until the aminoacetonitrile formation at 135 K. Therefore, these results demonstrate that aminoacetonitrile can be formed through the second step of the Strecker synthesis in astrophysical-like conditions.

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

    Directory of Open Access Journals (Sweden)

    J. Rinne

    2012-06-01

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

  4. Low Po2 conditions induce reactive oxygen species formation during contractions in single skeletal muscle fibers

    Science.gov (United States)

    Shiah, Amy; Roberts, William J.; Chien, Michael T.; Wagner, Peter D.; Hogan, Michael C.

    2013-01-01

    Contractions in whole skeletal muscle during hypoxia are known to generate reactive oxygen species (ROS); however, identification of real-time ROS formation within isolated single skeletal muscle fibers has been challenging. Consequently, there is no convincing evidence showing increased ROS production in intact contracting fibers under low Po2 conditions. Therefore, we hypothesized that intracellular ROS generation in single contracting skeletal myofibers increases during low Po2 compared with a value approximating normal resting Po2. Dihydrofluorescein was loaded into single frog (Xenopus) fibers, and fluorescence was used to monitor ROS using confocal microscopy. Myofibers were exposed to two maximal tetanic contractile periods (1 contraction/3 s for 2 min, separated by a 60-min rest period), each consisting of one of the following treatments: high Po2 (30 Torr), low Po2 (3–5 Torr), high Po2 with ebselen (antioxidant), or low Po2 with ebselen. Ebselen (10 μM) was administered before the designated contractile period. ROS formation during low Po2 treatment was greater than during high Po2 treatment, and ebselen decreased ROS generation in both low- and high-Po2 conditions (P Po2. Force was reduced >30% for each condition except low Po2 with ebselen, which only decreased ∼15%. We concluded that single myofibers under low Po2 conditions develop accelerated and more oxidative stress than at Po2 = 30 Torr (normal human resting Po2). Ebselen decreases ROS formation in both low and high Po2, but only mitigates skeletal muscle fatigue during reduced Po2 conditions. PMID:23576612

  5. In Situ Imaging of Particle Formation and Dynamics in Reactive Material Deflagrations

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Kyle T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-12

    Reactive composites utilizing nanoparticles have been the topic of extensive research in the past two decades. The driver for this is that, as the particle size is decreased, the mixing scale between constituents is greatly reduced, which has long thought to increase the rate of chemical reaction. While a general trend of increased reactivity has been seen for metal / metal oxide, or thermite, reactive materials, some results have demonstrated diminishing returns as the particle size is further decreased. Recent results have shown that nanoparticles, which are typically aggregates of several primary particles, can undergo very rapid coalescence to form micron particles once a critical temperature is reached. Experiments on this topic to date have been performed on very small sample masses, and sometimes under vacuum; conditions which are not representative of the environment during a deflagration. In this feasibility study, a custom burn tube was used to ignite and react 100 mg powdered thermite samples in long acrylic tubes. X-ray imaging at APS Sector 32 was performed to image the particle field as a function of distance and time as the rarefied particle cloud expanded and flowed down the tube. Five different thermite formulations were investigated, Al / CuO, Al / Fe2O3, Al / SnO2, Al / WO3, and Al / Fe2O3, along with Al / CuO formulations with different sizes of Al particles ranging from 80 nm to approximate 10 μm. The results clearly show that the sample powder reacts and unloads into a distribution of larger micron-scale particles (~5-500 μm), which continue to react and propagate as the particle-laden stream flows down the tube. This was the first direct imaging of the particle field during a thermite deflagration, and gives significant insight into the evolution of reactants to products. Analysis of phase is currently being pursued to determine whether this method can be used to extract

  6. Searching for chemical signatures of brown dwarf formation

    Science.gov (United States)

    Maldonado, J.; Villaver, E.

    2017-06-01

    Context. Recent studies have shown that close-in brown dwarfs in the mass range 35-55 MJup are almost depleted as companions to stars, suggesting that objects with masses above and below this gap might have different formation mechanisms. Aims: We aim to test whether stars harbouring massive brown dwarfs and stars with low-mass brown dwarfs show any chemical peculiarity that could be related to different formation processes. Methods: Our methodology is based on the analysis of high-resolution échelle spectra (R 57 000) from 2-3 m class telescopes. We determine the fundamental stellar parameters, as well as individual abundances of C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, and Zn for a large sample of stars known to have a substellar companion in the brown dwarf regime. The sample is divided into stars hosting massive and low-mass brown dwarfs. Following previous works, a threshold of 42.5 MJup was considered. The metallicity and abundance trends of the two subsamples are compared and set in the context of current models of planetary and brown dwarf formation. Results: Our results confirm that stars with brown dwarf companions do not follow the well-established gas-giant planet metallicity correlation seen in main-sequence planet hosts. Stars harbouring massive brown dwarfs show similar metallicity and abundance distribution as stars without known planets or with low-mass planets. We find a tendency of stars harbouring less-massive brown dwarfs of having slightly higher metallicity, [XFe/Fe] values, and abundances of Sc II, Mn I, and Ni I than the stars having the massive brown dwarfs. The data suggest, as previously reported, that massive and low-mass brown dwarfs might present differences in period and eccentricity. Conclusions: We find evidence of a non-metallicity dependent mechanism for the formation of massive brown dwarfs. Our results agree with a scenario in which massive brown dwarfs are formed as stars. At high metallicities, the core

  7. Chemical evolution, stellar nucleosynthesis and a variable star formation rate

    International Nuclear Information System (INIS)

    Olive, K.A.; Thielemann, F.K.; Truran, J.W.

    1986-04-01

    The effects of a decreasing star formation rate (SFR) on the galactic abundances of elements produced in massive stars (M ≥ 10 Msub solar). On the basis of a straightforward model of galactic evolution, a relation between the upper mass limit of type II supernovae (M/sub SN/) contributing to chemical evolution and the decline of the SFR (tau) is derived, when the oxygen abundance is determined only by massive stars. The additional requirement that all intermediate mass elements (Ne-Ti), which are also predominantly due to nucleosynthesis in massive stars, are produced in solar proportions leads to a unique value of M/sub SN/ and tau. The application of this method with abundance yields from Arnett (1978) and Woosley and Weaver (1986) resuults, however, in contradicting solutions: M/sub SN/ ≅ 45 Msub solar, tau = ∞, and M/sub SN/ ≅ 15 Msub solar, tau = 3 x 10 9 y. Thus, in order that this approach provide an effective probe of the SFR over the history of our galaxy it is essential that converging and more accurate predictions of the consequences of stellar and supernova nucleosynthesis will be forthcoming. 54 refs., 2 figs., 2 tabs

  8. Computerized tomography with X-rays: an instrument in the analysis physico-chemical between formations and drilling fluids interactions

    International Nuclear Information System (INIS)

    Coelho, Marcus Vinicius Cavalcante

    1998-01-01

    In this study it is demonstrated the applicability of the Computerized Tomography technique with x-rays to evaluate the reactivity degree between various drilling fluids and argillaceous sediments (Shales and Sandstones). The research has been conducted in the Rock-Fluid Interaction Pressure Simulator (RFIPS), where the possible physico-chemical alterations can be observed through successive tomography images, which are obtained during the flow of the fluid through the samples. In addition, it was noticed the formation of mud cake in Berea Sandstones samples in the RFIPS, though the Computerized Tomography with X-rays, when utilizing drilling fluids weighted with the baryte. (author)

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

    International Nuclear Information System (INIS)

    Franco-Pérez, Marco; Ayers, Paul W.; Gázquez, José L.; Vela, Alberto

    2015-01-01

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

  10. Optimization of integrated chemical-biological degradation of a reactive azo dye using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Sudarjanto, Gatut [Advanced Wastewater Management Centre, The University of Queensland, Qld 4072 (Australia); Keller-Lehmann, Beatrice [Advanced Wastewater Management Centre, The University of Queensland, Qld 4072 (Australia); Keller, Jurg [Advanced Wastewater Management Centre, The University of Queensland, Qld 4072 (Australia)]. E-mail: j.keller@awmc.uq.edu.au

    2006-11-02

    The integrated chemical-biological degradation combining advanced oxidation by UV/H{sub 2}O{sub 2} followed by aerobic biodegradation was used to degrade C.I. Reactive Azo Red 195A, commonly used in the textile industry in Australia. An experimental design based on the response surface method was applied to evaluate the interactive effects of influencing factors (UV irradiation time, initial hydrogen peroxide dosage and recirculation ratio of the system) on decolourisation efficiency and optimizing the operating conditions of the treatment process. The effects were determined by the measurement of dye concentration and soluble chemical oxygen demand (S-COD). The results showed that the dye and S-COD removal were affected by all factors individually and interactively. Maximal colour degradation performance was predicted, and experimentally validated, with no recirculation, 30 min UV irradiation and 500 mg H{sub 2}O{sub 2}/L. The model predictions for colour removal, based on a three-factor/five-level Box-Wilson central composite design and the response surface method analysis, were found to be very close to additional experimental results obtained under near optimal conditions. This demonstrates the benefits of this approach in achieving good predictions while minimising the number of experiments required.

  11. Optimization of integrated chemical-biological degradation of a reactive azo dye using response surface methodology

    International Nuclear Information System (INIS)

    Sudarjanto, Gatut; Keller-Lehmann, Beatrice; Keller, Jurg

    2006-01-01

    The integrated chemical-biological degradation combining advanced oxidation by UV/H 2 O 2 followed by aerobic biodegradation was used to degrade C.I. Reactive Azo Red 195A, commonly used in the textile industry in Australia. An experimental design based on the response surface method was applied to evaluate the interactive effects of influencing factors (UV irradiation time, initial hydrogen peroxide dosage and recirculation ratio of the system) on decolourisation efficiency and optimizing the operating conditions of the treatment process. The effects were determined by the measurement of dye concentration and soluble chemical oxygen demand (S-COD). The results showed that the dye and S-COD removal were affected by all factors individually and interactively. Maximal colour degradation performance was predicted, and experimentally validated, with no recirculation, 30 min UV irradiation and 500 mg H 2 O 2 /L. The model predictions for colour removal, based on a three-factor/five-level Box-Wilson central composite design and the response surface method analysis, were found to be very close to additional experimental results obtained under near optimal conditions. This demonstrates the benefits of this approach in achieving good predictions while minimising the number of experiments required

  12. Comparison of Electrocoagulation and Chemical Coagulation Processes in Removing Reactive red 196 from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Ali Assadi

    2016-06-01

    Full Text Available Background: Conventional chemical coagulation is considered as an old method to dye and COD removal in textile effluent. Electrocoagulation (EC process is a robust method to achieve maximum removal. Methods: This study was designed to compare the result of operational parameters including optimum pH and coagulant concentration for chemical coagulation with ferric chloride and alum also, voltage, electrolysis time, initial pH, and conductivity for EC with iron electrodes to remove reactive red 196 (RR 196. Results: The outcomes show that ferric chloride and alum at optimum concentration were capable of removing dye and COD by 79.63 % and 84.83% and 53% and 55%, respectively. In contrast, EC process removed the dye and COD by 99.98% and 90.4%, respectively. Conclusion: The highest treatment efficiency was obtained by increasing the voltage, electrolysis time, pH and conductivity. Increase initial dye concentration reduces removal efficiency. Ultimately, it could be concluded that EC technology is an efficient procedure for handling of colored industrial wastewaters.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-03-11

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

  14. Chemical environment of iron atoms in iron oxynitride films synthesized by reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Grafoute, M.; Petitjean, C.; Rousselot, C.; Pierson, J.F.; Greneche, J.M.

    2007-01-01

    An iron oxynitride film was deposited on silicon and glass substrates by magnetron sputtering in an Ar-N 2 -O 2 reactive mixture. Rutherford back-scattering spectrometry was used to determine the film composition (Fe 1.06 O 0.35 N 0.65 ). X-ray diffraction revealed the formation of a face-centred cubic (fcc) structure with a lattice parameter close to that of γ'''-FeN. X-ray photoelectron spectroscopy showed the occurrence of Fe-N and Fe-O bonds in the film. The local environment of iron atoms studied by 57 Fe Moessbauer spectrometry at both 300 and 77 K gives clear evidence that the Fe 1.06 O 0.35 N 0.65 is not a mixture of iron oxide and iron nitride phases. Despite a small amount of an iron nitride phase, the main sample consists of an iron oxynitride phase with an NaCl-type structure where oxygen atoms partially substitute for nitrogen atoms, thus indicating the formation of a iron oxynitride with an fcc structure

  15. Microstructure, chemical states, and mechanical properties of V–C–Co coatings prepared by non-reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Zhang, Xiaojuan; Wang, Bo; Zhan, Zhaolin; Huang, Feng

    2013-01-01

    V–C–Co coatings have been prepared by non-reactive magnetron co-sputtering from VC and Co targets. The microstructure, chemical states, and mechanical properties are examined as a function of Co content in the coatings. The coatings are dense, with columnar growth structures. High resolution transmission electron microscopy (HRTEM) studies identify a nanocomposite microstructure for the 12.4 at.% Co coating, in which ligament-like Co-rich regions partially separate the nanocrystalline VC grains. X-ray photoelectron spectroscopy studies reveal a noticeable charge transfer from Co 2p states to C 1s states. This charge transfer, in addition to the ligament-like Co-rich regions as revealed by HRTEM, points to the formation of a strong Co/VC interface. The nanoindentation hardness of the coatings drops steadily with the Co content, from 29 GPa for pure VC to ∼ 21 GPa for the 12.4 at.% Co coating. Meanwhile, the plasticity characteristic increased from 0.42 to 0.53. - Highlights: • Nanocomposite V–C–Co coatings with strong Co/VC interfaces were formed. • Found nanocrystalline VC grains separated by ∼ 1 nm thin Co-rich ligaments. • A noticeable amount of C-Co bonds between VC and Co is identified. • V–C–Co coatings exhibited a higher plasticity characteristic than VC

  16. Microstructure, chemical states, and mechanical properties of V–C–Co coatings prepared by non-reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaojuan [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650000 (China); Wang, Bo [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhan, Zhaolin [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650000 (China); Huang, Feng, E-mail: huangfeng@nimte.ac.cn [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China)

    2013-07-01

    V–C–Co coatings have been prepared by non-reactive magnetron co-sputtering from VC and Co targets. The microstructure, chemical states, and mechanical properties are examined as a function of Co content in the coatings. The coatings are dense, with columnar growth structures. High resolution transmission electron microscopy (HRTEM) studies identify a nanocomposite microstructure for the 12.4 at.% Co coating, in which ligament-like Co-rich regions partially separate the nanocrystalline VC grains. X-ray photoelectron spectroscopy studies reveal a noticeable charge transfer from Co 2p states to C 1s states. This charge transfer, in addition to the ligament-like Co-rich regions as revealed by HRTEM, points to the formation of a strong Co/VC interface. The nanoindentation hardness of the coatings drops steadily with the Co content, from 29 GPa for pure VC to ∼ 21 GPa for the 12.4 at.% Co coating. Meanwhile, the plasticity characteristic increased from 0.42 to 0.53. - Highlights: • Nanocomposite V–C–Co coatings with strong Co/VC interfaces were formed. • Found nanocrystalline VC grains separated by ∼ 1 nm thin Co-rich ligaments. • A noticeable amount of C-Co bonds between VC and Co is identified. • V–C–Co coatings exhibited a higher plasticity characteristic than VC.

  17. Comparative evaluation of particle properties, formation of reactive oxygen species and genotoxic potential of tungsten carbide based nanoparticles in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kuehnel, Dana, E-mail: dana.kuehnel@ufz.de [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Scheffler, Katja [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Department of Cell Techniques and Applied Stem Cell Biology, University of Leipzig, Deutscher Platz 5, 04103 Leipzig (Germany); Wellner, Peggy [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Meissner, Tobias; Potthoff, Annegret [Fraunhofer-Institute for Ceramic Technologies and Systems (IKTS), Winterbergstr. 28, 01277 Dresden (Germany); Busch, Wibke [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Springer, Armin [Centre for Translational Bone, Cartilage and Soft Tissue Research, University Hospital Carl Gustav Carus, Technical University Dresden, Fetscherstrasse 74, 01307 Dresden (Germany); Schirmer, Kristin [Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf (Switzerland); EPF Lausanne, School of Architecture, Civil and Environmental Engineering, 1015 Lausanne (Switzerland); ETH Zuerich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zuerich (Switzerland)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Assessment of toxic potential of tungsten carbide-based nanoparticles. Black-Right-Pointing-Pointer Evaluation of ROS and micronuclei induction of three hard metal nanomaterials. Black-Right-Pointing-Pointer Dependency of observed toxic effects on the materials physical-chemical properties. Black-Right-Pointing-Pointer Differences in several particle properties seem to modulate the biological response. - Abstract: Tungsten carbide (WC) and cobalt (Co) are constituents of hard metals and are used for the production of extremely hard tools. Previous studies have identified greater cytotoxic potential of WC-based nanoparticles if particles contained Co. The aim of this study was to investigate whether the formation of reactive oxygen species (ROS) and micronuclei would help explain the impact on cultured mammalian cells by three different tungsten-based nanoparticles (WC{sub S}, WC{sub L}, WC{sub L}-Co (S: small; L: large)). The selection of particles allowed us to study the influence of particle properties, e.g. surface area, and the presence of Co on the toxicological results. WC{sub S} and WC{sub L}/WC{sub L}-Co differed in their crystalline structure and surface area, whereas WC{sub S}/WC{sub L} and WC{sub L}-Co differed in their cobalt content. WC{sub L} and WC{sub L}-Co showed neither a genotoxic potential nor ROS induction. Contrary to that, WC{sub S} nanoparticles induced the formation of both ROS and micronuclei. CoCl{sub 2} was tested in relevant concentrations and induced no ROS formation, but increased the rate of micronuclei at concentrations exceeding those present in WC{sub L}-Co. In conclusion, ROS and micronuclei formation could not be associated with the presence of Co in the WC-based particles. The contrasting responses elicited by WC{sub S} vs. WC{sub L} appear to be due to large differences in crystalline structure.

  18. The surface chemical reactivity of particles and its impact on human health

    Science.gov (United States)

    Setyan, A.; Sauvain, J. J.; Riediker, M.; Guillemin, M.; Rossi, M. J.

    2017-12-01

    The chemical composition of the particle-air interface is the gateway to chemical reactions of gases with condensed phase particles. It is of prime importance to understand the reactivity of particles and their interaction with surrounding gases, biological membranes, and solid supports. We used a Knudsen flow reactor to quantify functional groups on the surface of a few selected particle types. This technique is based on a heterogeneous titration reaction between a probe gas and a specific functional group on the particle surface. Six probe gases have been selected for the identification and quantification of important functional groups: N(CH3)3 for the titration of acidic sites, NH2OH for the detection of carbonyl functions (aldehydes and ketones) and/or oxidized sites owing to its strong reducing properties, CF3COOH and HCl for basic sites of different strength, O3 and NO2 for oxidizable groups. We also studied the kinetics of the reactions between particles and probe gases (uptake coefficient γ0). We tested the surface chemical composition and oxidation states of laboratory-generated aerosols (3 amorphous carbons, 2 flame soots, 2 Diesel particles, 2 secondary organic aerosols [SOA], 4 multiwall carbon nanotubes [MWCNT], 3 TiO2, and 2 metal salts) and of aerosols sampled in several bus depots. The sampling of particles in the bus depots was accompanied by the collection of urine samples of mechanics working full-time in these bus depots, and the quantification of 8-hydroxy-2'-deoxyguanosine, a biomarker of oxidative stress. The increase in oxidative stress biomarker levels over a working day was correlated (pcellular antioxidants.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

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

    Science.gov (United States)

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

    2007-06-16

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

  1. Initial growth and texture formation during reactive magnetron sputtering of TiN on Si(111)

    CERN Document Server

    Li, T Q; Tsuji, Y; Ohsawa, T; Komiyama, H

    2002-01-01

    The initial growth and texture formation mechanism of titanium nitride (TiN) films were investigated by depositing TiN films on (111) silicon substrates by using reactive magnetron sputtering of a Ti metallic target under a N sub 2 /Ar atmosphere, and then analyzing the films in detail by using transmission electron microscopy (TEM) and x-ray diffraction (XRD). Two power sources for the sputtering, dc and rf, were compared. At the initial growth stage, a continuous amorphous film containing randomly oriented nuclei was observed when the film thickness was about 3 nm. The nuclei grew and formed a polycrystalline layer when the film thickness was about 6 nm. As the film grew further, its orientation changed depending on the deposition conditions. For dc sputtering, the appearance of (111) or (200)-preferred orientations depended on the N sub 2 partial pressure, and the intensity of the preferred orientation increased with increasing film thickness. For rf sputtering, however, when the film thickness was small (...

  2. Pore Formation Process of Porous Ti3SiC2 Fabricated by Reactive Sintering

    Directory of Open Access Journals (Sweden)

    Huibin Zhang

    2017-02-01

    Full Text Available Porous Ti3SiC2 was fabricated with high purity, 99.4 vol %, through reactive sintering of titanium hydride (TiH2, silicon (Si and graphite (C elemental powders. The reaction procedures and the pore structure evolution during the sintering process were systematically studied by X-ray diffraction (XRD and scanning electron microscope (SEM. Our results show that the formation of Ti3SiC2 from TiH2/Si/C powders experienced the following steps: firstly, TiH2 decomposed into Ti; secondly, TiC and Ti5Si3 intermediate phases were generated; finally, Ti3SiC2 was produced through the reaction of TiC, Ti5Si3 and Si. The pores formed in the synthesis procedure of porous Ti3SiC2 ceramics are derived from the following aspects: interstitial pores left during the pressing procedure; pores formed because of the TiH2 decomposition; pores formed through the reactions between Ti and Si and Ti and C powders; and the pores produced accompanying the final phase synthesized during the high temperature sintering process.

  3. The synergistic effect of chemical carcinogens enhances Epstein-Barr virus reactivation and tumor progression of nasopharyngeal carcinoma cells.

    Science.gov (United States)

    Fang, Chih-Yeu; Huang, Sheng-Yen; Wu, Chung-Chun; Hsu, Hui-Yu; Chou, Sheng-Ping; Tsai, Ching-Hwa; Chang, Yao; Takada, Kenzo; Chen, Jen-Yang

    2012-01-01

    Seroepidemiological studies imply a correlation between Epstein-Barr virus (EBV) reactivation and the development of nasopharyngeal carcinoma (NPC). N-nitroso compounds, phorbols, and butyrates are chemicals found in food and herb samples collected from NPC high-risk areas. These chemicals have been reported to be risk factors contributing to the development of NPC, however, the underlying mechanism is not fully understood. We have demonstrated previously that low dose N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 0.1 µg/ml) had a synergistic effect with 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium butyrate (SB) in enhancing EBV reactivation and genome instability in NPC cells harboring EBV. Considering that residents in NPC high-risk areas may contact regularly with these chemical carcinogens, it is vital to elucidate the relation between chemicals and EBV and their contributions to the carcinogenesis of NPC. In this study, we constructed a cell culture model to show that genome instability, alterations of cancer hallmark gene expression, and tumorigenicity were increased after recurrent EBV reactivation in NPC cells following combined treatment of TPA/SB and MNNG. NPC cells latently infected with EBV, NA, and the corresponding EBV-negative cell, NPC-TW01, were periodically treated with MNNG, TPA/SB, or TPA/SB combined with MNNG. With chemically-induced recurrent reactivation of EBV, the degree of genome instability was significantly enhanced in NA cells treated with a combination of TPA/SB and MNNG than those treated individually. The Matrigel invasiveness, as well as the tumorigenicity in mouse, was also enhanced in NA cells after recurrent EBV reactivation. Expression profile analysis by microarray indicates that many carcinogenesis-related genes were altered after recurrent EBV reactivation, and several aberrations observed in cell lines correspond to alterations in NPC lesions. These results indicate that cooperation between chemical carcinogens can

  4. Chemical reactivation of resin-embedded pHuji adds red for simultaneous two-color imaging with EGFP

    Science.gov (United States)

    Guo, Wenyan; Liu, Xiuli; Liu, Yurong; Gang, Yadong; He, Xiaobin; Jia, Yao; Yin, Fangfang; Li, Pei; Huang, Fei; Zhou, Hongfu; Wang, Xiaojun; Gong, Hui; Luo, Qingming; Xu, Fuqiang; Zeng, Shaoqun

    2017-01-01

    The pH-sensitive fluorescent proteins enabling chemical reactivation in resin are useful tools for fluorescence microimaging. EGFP or EYFP is good for such applications. For simultaneous two-color imaging, a suitable red fluorescent protein is an urgent need. Here a pH-sensitive red fluorescent protein, pHuji, is selected and verified to remain pH-sensitive in HM20 resin. We observe 183% fluorescence intensity of pHuji in resin-embeded mouse brain and 29.08-fold fluorescence intensity of reactivated pHuji compared to the quenched state. pHuji and EGFP can be quenched and chemically reactivated simultaneously in resin, thus enabling simultaneous two-color micro-optical sectioning tomography of resin-embedded mouse brain. This method may greatly facilitate the visualization of neuronal morphology and neural circuits to promote understanding of the structure and function of the brain. PMID:28717566

  5. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    Energy Technology Data Exchange (ETDEWEB)

    Hamaguchi, Satoshi [Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2013-07-11

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed.

  6. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    International Nuclear Information System (INIS)

    Hamaguchi, Satoshi

    2013-01-01

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed

  7. Reactive Imprint Lithography: Combined Topographical Patterning and Chemical Surface Functionalization of Polystyrene-block-poly(tert-butyl acrylate) Films

    NARCIS (Netherlands)

    Duvigneau, Joost; Cornelissen, Stijn; Bardajı´Valls, Nuria; Schönherr, Holger; Vancso, Gyula J.

    2009-01-01

    Here, reactive imprint lithography (RIL) is introduced as a new, one-step lithographic tool for the fabrication of large-area topographically patterned, chemically activated polymer platforms. Films of polystyrene-block-poly(tert-butyl acrylate) (PS-b-PtBA) are imprinted with PDMS master stamps at

  8. Radiation-Driven Formation of Reactive Oxygen Species in Oxychlorine-Containing Mars Surface Analogues

    Science.gov (United States)

    Georgiou, Christos D.; Zisimopoulos, Dimitrios; Kalaitzopoulou, Electra; Quinn, Richard C.

    2017-04-01

    The present study demonstrates that γ-radiolyzed perchlorate-containing Mars soil salt analogues (in a CO2 atmosphere) generate upon H2O wetting the reactive oxygen species (ROS) superoxide radical (O2•-), hydrogen peroxide (H2O2), and hydroxyl radicals (•OH). This study also validates that analogue radiolysis forms oxychlorine species that, in turn, can UV-photolyze to •OH upon UV photolysis. This investigation was made possible by the development of a new assay for inorganic-origin O2•- and H2O2 determination and by the modification of a previous assay for soil •OH. Results show that radiolyzed Mg(ClO4)2 generates H2O2 and •OH; and when included as part of a mixture analogous to the salt composition of samples analyzed at the Mars Phoenix site, the analogue generated O2•-, H2O2, and •OH, with •OH levels 150-fold higher than in the radiolyzed Mg(ClO4)2 samples. Radiolyzed Mars Phoenix site salt analogue that did not contain Mg(ClO4)2 generated only •OH also at 150-fold higher concentration than Mg(ClO4)2 alone. Additionally, UV photolysis of the perchlorate γ radiolysis product chlorite (ClO2-) generated the oxychlorine products trihalide (Cl3-), chlorine dioxide (ClO2•), and hypochlorite (ClO-), with the formation of •OH by UV photolysis of ClO-. While the generation of ROS may have contributed in part to 14CO2 production in the Viking Labeled Release (LR) experiment and O2 (g) release in the Viking Gas Exchange (GEx) experiment, our results indicate that they are not likely to be the major contributor to the LR and GEx results. However, due to their highly reactive nature, they are expected to play a significant role in the alteration of organics on Mars. Additionally, experiments with hypochlorite show that the thermal stability of NaClO is in the range of the thermal stability observed for thermally liable oxidant responsible for the Viking LR results.

  9. Quick Look Report for Chemical Reactivity Modeling of Various Multi-Canister Overpack Breaches

    Energy Technology Data Exchange (ETDEWEB)

    Bratton, Robert Lawrence

    2002-04-01

    This report makes observations or shows trends in the response and does not specifically provide conclusions or predict the onset of bulk uranium oxidation safety margins based on hole size. Comprehensive analysis will be provided in the future. The report should animate discussions about the results and what should be analyzed further in the final analysis. This report intends only to show the response of the breached multi-canister overpack (MCO) as a function of event time using the GOTH_SNF computer code. The response will be limited to physical quantities available on the exterior of the MCO. The GOTH_SNF model is approximate, because not all physical phenomenon was included in the model. Error estimates in the response are not possible at this time, because errors in the actual physical data are not known. Sensitivities in the results from variations in the physical data have not been pursued at this time, either. This effort was undertaken by the National Spent Nuclear Fuel Program to evaluate potential chemical reactivity issues of a degraded uranium metal spent nuclear fuel using the MCO fully loaded with Mark IV N-reactor fuel as the evaluation model. This configuration is proposed for handling in the Yucca Mountain Project (YMP) surface facility. Hanford is loading N-reactor fuel elements into the MCO for interim storage at the Hanford site with permanent disposal proposed at YMP. A portion of the N-reactor fuel inventory has suffered corrosion, exposing the uranium metal under the zircaloy cladding. Because of the sealed MCO, the local radiation field, and decay heat of the fuel, hydrogen production cannot be ruled out from the metal hydrates on the surface of the zircaloy cladding and exposed fuel. Because of the much greater surface area, the oxyhydroxide composition, and water of hydration in the uranium metal corrosion product, the corrosion product will be a significant water source that may equal the absorbed water on the zircaloy cladding. A

  10. Quick Look Report for Chemical Reactivity Modeling of Various Multi-Canister Overpack Breaches

    International Nuclear Information System (INIS)

    Bratton, Robert Lawrence

    2002-01-01

    This report makes observations or shows trends in the response and does not specifically provide conclusions or predict the onset of bulk uranium oxidation safety margins based on hole size. Comprehensive analysis will be provided in the future. The report should animate discussions about the results and what should be analyzed further in the final analysis. This report intends only to show the response of the breached multi-canister overpack (MCO) as a function of event time using the GOTH( ) SNF computer code. The response will be limited to physical quantities available on the exterior of the MCO. The GOTH( ) SNF model is approximate, because not all physical phenomenon was included in the model. Error estimates in the response are not possible at this time, because errors in the actual physical data are not known. Sensitivities in the results from variations in the physical data have not been pursued at this time, either. This effort was undertaken by the National Spent Nuclear Fuel Program to evaluate potential chemical reactivity issues of a degraded uranium metal spent nuclear fuel using the MCO fully loaded with Mark IV N-reactor fuel as the evaluation model. This configuration is proposed for handling in the Yucca Mountain Project (YMP) surface facility. Hanford is loading N-reactor fuel elements into the MCO for interim storage at the Hanford site with permanent disposal proposed at YMP. A portion of the N-reactor fuel inventory has suffered corrosion, exposing the uranium metal under the zircaloy cladding. Because of the sealed MCO, the local radiation field, and decay heat of the fuel, hydrogen production cannot be ruled out from the metal hydrates on the surface of the zircaloy cladding and exposed fuel. Because of the much greater surface area, the oxyhydroxide composition, and water of hydration in the uranium metal corrosion product, the corrosion product will be a significant water source that may equal the absorbed water on the zircaloy cladding

  11. Formation of polystyrene/poly(methyl methacrylate) heteroarm star-like nanogels from complementarily reactive well-defined diblock copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Amamoto, Y; Otsuka, H; Takahara, A, E-mail: otsuka@ms.ifoc.kyushu-u.ac.j [Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0385 (Japan)

    2009-08-01

    Formation of star-like nanogels with two different arms via cross-linking reaction of complementarily reactive diblock copolymers was successfully accomplished. The two types of diblock copolymers, consisting of poly(methyl methacrylate) (PMMA) or polystyrene (PSt) block and alkoxyamine-based cross-linkable block, were prepared by atom transfer radical polymerization (ATRP) methods. The cross-linking reactions were carried out by merely heating their mixture, and traced by gel permeation chromatography (GPC) and multi-angle light scattering (MALS) measurements. The diblock copolymers were reacted in complementarily reactive systems, showing that all star-like nanogels have necessarily two types of arms as PMMA and PSt chains.

  12. Persistent local chemical bonds in intermetallic phase formation

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yanwen [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Bian, Xiufang, E-mail: xfbian@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Qin, Xubo [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Zhang, Shuo; Huang, Yuying [Shanghai Synchrotron Radiation Facilities, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China)

    2014-05-01

    We found a direct evidence for the existence of the local chemical Bi–In bonds in the BiIn{sub 2} melt. These bonds are strong and prevail, dominating the structure evolution of the intermetallic clusters. From the local structure of the melt-quenched BiIn{sub 2} ribbon, the chemical Bi–In bonds strengthen compared with those in the equilibrium solidified alloy. The chemical bonds in BiIn{sub 2} melt retain to solid during a rapid quenching process. The results suggest that the intermetallic clusters in the melt evolve into the as-quenched intermetallic phase, and the intermetallic phase originates from the chemical bonds between unlike atoms in the melt. The chemical bonds preserve the chemical ordered clusters and dominate the clusters evolution.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Christelle Pau Ping Wong

    2015-10-01

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

  15. Atomistic-level non-equilibrium model for chemically reactive systems based on steepest-entropy-ascent quantum thermodynamics

    International Nuclear Information System (INIS)

    Li, Guanchen; Al-Abbasi, Omar; Von Spakovsky, Michael R

    2014-01-01

    This paper outlines an atomistic-level framework for modeling the non-equilibrium behavior of chemically reactive systems. The framework called steepest- entropy-ascent quantum thermodynamics (SEA-QT) is based on the paradigm of intrinsic quantum thermodynamic (IQT), which is a theory that unifies quantum mechanics and thermodynamics into a single discipline with wide applications to the study of non-equilibrium phenomena at the atomistic level. SEA-QT is a novel approach for describing the state of chemically reactive systems as well as the kinetic and dynamic features of the reaction process without any assumptions of near-equilibrium states or weak-interactions with a reservoir or bath. Entropy generation is the basis of the dissipation which takes place internal to the system and is, thus, the driving force of the chemical reaction(s). The SEA-QT non-equilibrium model is able to provide detailed information during the reaction process, providing a picture of the changes occurring in key thermodynamic properties (e.g., the instantaneous species concentrations, entropy and entropy generation, reaction coordinate, chemical affinities, reaction rate, etc). As an illustration, the SEA-QT framework is applied to an atomistic-level chemically reactive system governed by the reaction mechanism F + H 2 ↔ FH + H

  16. Le Châtelier's conjecture: Measurement of colloidal eigenstresses in chemically reactive materials

    Science.gov (United States)

    Abuhaikal, Muhannad; Ioannidou, Katerina; Petersen, Thomas; Pellenq, Roland J.-M.; Ulm, Franz-Josef

    2018-03-01

    Volume changes in chemically reactive materials, such as hydrating cement, play a critical role in many engineering applications that require precise estimates of stress and pressure developments. But a means to determine bulk volume changes in the absence of other deformation mechanisms related to thermal, pressure and load variations, is still missing. Herein, we present such a measuring devise, and a hybrid experimental-theoretical technique that permits the determination of colloidal eigenstresses. Applied to cementitious materials, it is found that bulk volume changes in saturated cement pastes at constant pressure and temperature conditions result from a competition of repulsive and attractive phenomena that originate from the relative distance of the solid particles - much as Henry Louis Le Châtelier, the father of modern cement science, had conjectured in the late 19th century. Precipitation of hydration products in confined spaces entails a repulsion, whereas the concurrent reduction in interparticle distance entails activation of attractive forces in charged colloidal particles. This cross-over from repulsion to attraction can be viewed as a phase transition between a liquid state (below the solid percolation) and the limit packing of hard spheres, separated by an energy barrier that defines the temperature-dependent eigenstress magnitude.

  17. Role of Chemical Reactivity and Transition State Modeling for Virtual Screening.

    Science.gov (United States)

    Karthikeyan, Muthukumarasamy; Vyas, Renu; Tambe, Sanjeev S; Radhamohan, Deepthi; Kulkarni, Bhaskar D

    2015-01-01

    Every drug discovery research program involves synthesis of a novel and potential drug molecule utilizing atom efficient, economical and environment friendly synthetic strategies. The current work focuses on the role of the reactivity based fingerprints of compounds as filters for virtual screening using a tool ChemScore. A reactant-like (RLS) and a product- like (PLS) score can be predicted for a given compound using the binary fingerprints derived from the numerous known organic reactions which capture the molecule-molecule interactions in the form of addition, substitution, rearrangement, elimination and isomerization reactions. The reaction fingerprints were applied to large databases in biology and chemistry, namely ChEMBL, KEGG, HMDB, DSSTox, and the Drug Bank database. A large network of 1113 synthetic reactions was constructed to visualize and ascertain the reactant product mappings in the chemical reaction space. The cumulative reaction fingerprints were computed for 4000 molecules belonging to 29 therapeutic classes of compounds, and these were found capable of discriminating between the cognition disorder related and anti-allergy compounds with reasonable accuracy of 75% and AUC 0.8. In this study, the transition state based fingerprints were also developed and used effectively for virtual screening in drug related databases. The methodology presented here provides an efficient handle for the rapid scoring of molecular libraries for virtual screening.

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

    KAUST Repository

    Hu, Pan

    2015-12-30

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

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

    KAUST Repository

    Hu, Pan; Lee, Sangsu; Herng, Tun Seng; Aratani, Naoki; Goncalves, Theo; Qi, Qingbiao; Shi, Xueliang; Yamada, Hiroko; Huang, Kuo-Wei; Ding, Jun; Kim, Dongho; Wu, Jishan

    2015-01-01

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

  20. Simultaneous measurements of reactive scalar and velocity in a planar liquid jet with a second-order chemical reaction

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Tomoaki; Sakai, Yasuhiko; Nagata, Kouji; Terashima, Osamu [Nagoya University, Department of Mechanical Science and Engineering, Nagoya (Japan); Kubo, Takashi [Meijo University, Faculty of Science and Technology, Nagoya (Japan)

    2012-11-15

    This paper presents a new experimental approach for simultaneous measurements of velocity and concentration in a turbulent liquid flow with a chemical reaction. For the simultaneous measurements, we developed a combined probe consisting of an I-type hot-film probe and an optical fiber probe based on the light absorption spectrometric method. In a turbulent planar liquid jet with a second-order chemical reaction (A+B{yields}R), streamwise velocity and concentrations of all reactive species are measured by the combined probe. The turbulent mass fluxes of the reactive species are estimated from the simultaneous measurements. The results show that the influence of the chemical reaction on the turbulent mass flux of the reactant species near the jet exit is different from its influence in other regions, and the turbulent mass flux of the product species has a negative value near the jet exit and a positive value in other regions. (orig.)

  1. Nano-patterning of perpendicular magnetic recording media by low-energy implantation of chemically reactive ions

    International Nuclear Information System (INIS)

    Martin-Gonzalez, M.S.; Briones, F.; Garcia-Martin, J.M.; Montserrat, J.; Vila, L.; Faini, G.; Testa, A.M.; Fiorani, D.; Rohrmann, H.

    2010-01-01

    Magnetic nano-patterning of perpendicular hard disk media with perpendicular anisotropy, but preserving disk surface planarity, is presented here. Reactive ion implantation is used to locally modify the chemical composition (hence the magnetization and magnetic anisotropy) of the Co/Pd multilayer in irradiated areas. The procedure involves low energy, chemically reactive ion irradiation through a resist mask. Among N, P and As ions, P are shown to be most adequate to obtain optimum bit density and topography flatness for industrial Co/Pd multilayer media. The effect of this ion contributes to isolate perpendicular bits by destroying both anisotropy and magnetic exchange in the irradiated areas. Low ion fluences are effective due to the stabilization of atomic displacement levels by the chemical effect of covalent impurities.

  2. Relationships Between Base-Catalyzed Hydrolysis Rates or Glutathione Reactivity for Acrylates and Methacrylates and Their NMR Spectra or Heat of Formation

    Directory of Open Access Journals (Sweden)

    Yoshinori Kadoma

    2012-05-01

    Full Text Available The NMR chemical shift, i.e., the π-electron density of the double bond, of acrylates and methacrylates is related to the reactivity of their monomers. We investigated quantitative structure-property relationships (QSPRs between the base-catalyzed hydrolysis rate constants (k1 or the rate constant with glutathione (GSH (log kGSH for acrylates and methacrylates and the 13C NMR chemical shifts of their α,β-unsaturated carbonyl groups (δCα and δCβ or heat of formation (Hf calculated by the semi-empirical MO method. Reported data for the independent variables were employed. A significant linear relationship between k1 and δCβ, but not δCα, was obtained for methacrylates (r2 = 0.93, but not for acrylates. Also, a significant relationship between k1 and Hf was obtained for both acrylates and methacrylates (r2 = 0.89. By contrast, log kGSH for acrylates and methacrylates was linearly related to their δCβ (r2 = 0.99, but not to Hf. These findings indicate that the 13C NMR chemical shifts and calculated Hf values for acrylates and methacrylates could be valuable for estimating the hydrolysis rate constants and GSH reactivity of these compounds. Also, these data for monomers may be an important tool for examining mechanisms of reactivity.

  3. Formation of nitric acid hydrates - A chemical equilibrium approach

    Science.gov (United States)

    Smith, Roland H.

    1990-01-01

    Published data are used to calculate equilibrium constants for reactions of the formation of nitric acid hydrates over the temperature range 190 to 205 K. Standard enthalpies of formation and standard entropies are calculated for the tri- and mono-hydrates. These are shown to be in reasonable agreement with earlier calorimetric measurements. The formation of nitric acid trihydrate in the polar stratosphere is discussed in terms of these equilibrium constants.

  4. Formation of glutathione conjugates by reactive metabolites of vinylidene chloride in microsomes and isolated hepatocytes

    International Nuclear Information System (INIS)

    Liebler, D.C.; Meredith, M.J.; Guengerich, F.P.

    1985-01-01

    Oxidation of the vinyl halide carcinogen and hepatotoxin vinylidene chloride (VDC) by microsomal cytochrome P-450 yields 2,2-dichloroacetaldehyde, 2-chloroacetyl chloride, 2-chloroacetic acid, and 1,1-dichloroethylene oxide. The roles of these metabolites in covalent modification of proteins and reduced glutathione (GSH) were examined. 2-Chloroacetyl chloride reacted with model thiols at least 10(3)-fold faster than did 1,1-dichloroethylene oxide and at least 10(5)-fold faster than did 2,2-dichloroacetaldehyde or 2-chloroacetic acid. Microsomal covalent binding of [ 14 C]VDC was inhibited by GSH but not by lysine, suggesting that protein thiols, rather than amino groups, are major targets. Liver microsomes catalyzed the formation of three GSH:VDC metabolite conjugates, identified as S-(2,2-dichloro-1-hydroxy)ethylglutathione, 2-(S-glutathionyl)acetate, and S-(2-glutathionyl)acetylglutathione, a novel conjugate containing both stable (thioether) and labile (thioester) linkages. The latter two conjugates also were formed in isolated rat hepatocytes and measurable amounts of 2-(S-glutathionyl)acetate were released into the incubation medium. Both 2-(S-glutathionyl)acetate and S-(2-glutathionyl)acetylglutathione were formed with [ 35 S]GSH added to the hepatic medium, indicating that reactive VDC metabolites are capable of crossing the plasma membrane to react with extracellular targets. Unlabeled S-(2-glutathionyl)-acetylglutathione underwent carbonyl substitution with added [ 35 S]GSH, suggesting that this conjugate may participate in modification of protein thiols. This conjugate also underwent hydrolysis with a half-life of approximately 3 hr. GSH:VDC metabolite conjugates may serve as accessible models for labile covalent adducts formed between VDC metabolites and protein thiols

  5. Role of chlorine in the nanocrystalline silicon film formation by rf plasma-enhanced chemical vapor deposition of chlorinated materials

    International Nuclear Information System (INIS)

    Shirai, Hajime

    2004-01-01

    We demonstrate the disorder-induced low-temperature crystallization in the nanocrystalline silicon film growth by rf plasma-enhanced chemical vapor deposition of H 2 -diluted SiH 2 Cl 2 and SiCl 4 . The combination of the chemical reactivity of SiCld (d: dangling bond) and SiHCl complexes and the release of the disorder-induced stress near the growing surface tightly correlate with the phase transitionity of SiCld and SiHCl complexes near the growing surface with the aid of atomic hydrogen, which induce higher degree of disorder in the a-Si network. These features are most prominent in the SiCl 4 compared with those of SiH 2 Cl 2 and SiH 4 , which preferentially enhance the nanocrystalline Si formation

  6. Effects of fuel properties, temperature, and pressure on fuel reactivity, formation and destruction of nitrogen oxides, and release of alkalis

    International Nuclear Information System (INIS)

    Aho, M.

    1998-01-01

    This study assists in the development of advanced combustion technologies (PFBC, IGCC) with high efficiency of electricity production from solid fuels (η = 47 - 50%) and in minimizing emissions of nitrogen oxides in atmospheric and pressurised FB combustion. In addition to the work done within the LIEKKI 2 programme, research work has been carried out inside the Joule 2 programme of EU. The research work may be divided into three parts: (1) Study of N x O y formation and destruction, (2) Study of fuel reactivity at elevated pressures, and (3) Study on alkali release from different coals. Experimental work was carried out utilizing a novel pressurized entrained flow reactor (PEFR) completed in VTT Energy in the autumn 1992. The device was unique in the world between 1992 and 1995. The effects of fuel properties on the formation of N 2 O and NO at conditions typical to FB combustion were studied for a large number of fuels including different coals, coal-derived char, peat, and bark. This work started before 1993 and was completed in 1995. FTIR technology was utilized for on-line gas analysis of N 2 O, NO, and NO 2 . The ratio fuel-O/fuel-N was found to be the most important fuel factor determining the formation of N 2 O and NO from volatile fuel-N. Only a small part of N 2 O is formed from char-N. The effect of pressure (0.2 - 2.0 MPa) on the formation of N 2 O, NO, and NO 2 , and destruction of NO with ammonia (Thermal DeNO x , experiments at 0.2, 0.5, and 1.5 MPa) and urea (NO x Out, experiments at 0.5 MPa) were studied in cooperation with Aabo Akademi University (AaAU). VTT performed the experimental work and AaAU the kinetic modelling. A part of these results are presented in the report by AaAU. Increase of pressure decreases NO formation and increases NO 2 formation. The behaviour of N 2 O is more complex. Both destruction processes for NO seem to operate well at elevated pressure, although clear effects of pressure on the temperature window of Thermal DeNO x

  7. Calcite Formation in Soft Coral Sclerites Is Determined by a Single Reactive Extracellular Protein*

    Science.gov (United States)

    Rahman, M. Azizur; Oomori, Tamotsu; Wörheide, Gert

    2011-01-01

    Calcium carbonate exists in two main forms, calcite and aragonite, in the skeletons of marine organisms. The primary mineralogy of marine carbonates has changed over the history of the earth depending on the magnesium/calcium ratio in seawater during the periods of the so-called “calcite and aragonite seas.” Organisms that prefer certain mineralogy appear to flourish when their preferred mineralogy is favored by seawater chemistry. However, this rule is not without exceptions. For example, some octocorals produce calcite despite living in an aragonite sea. Here, we address the unresolved question of how organisms such as soft corals are able to form calcitic skeletal elements in an aragonite sea. We show that an extracellular protein called ECMP-67 isolated from soft coral sclerites induces calcite formation in vitro even when the composition of the calcifying solution favors aragonite precipitation. Structural details of both the surface and the interior of single crystals generated upon interaction with ECMP-67 were analyzed with an apertureless-type near-field IR microscope with high spatial resolution. The results show that this protein is the main determining factor for driving the production of calcite instead of aragonite in the biocalcification process and that –OH, secondary structures (e.g. α-helices and amides), and other necessary chemical groups are distributed over the center of the calcite crystals. Using an atomic force microscope, we also explored how this extracellular protein significantly affects the molecular-scale kinetics of crystal formation. We anticipate that a more thorough investigation of the proteinaceous skeleton content of different calcite-producing marine organisms will reveal similar components that determine the mineralogy of the organisms. These findings have significant implications for future models of the crystal structure of calcite in nature. PMID:21768106

  8. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    OpenAIRE

    Rafieian, Damon; Ogieglo, Wojciech; Savenije, T.J.; Lammertink, Rob G H

    2015-01-01

    We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx), obtained by sputtering at relatively low oxygen concentration, formed rutile upon annealing in air, ...

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

    Science.gov (United States)

    2013-01-01

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

  10. Mitochondrion-derived reactive oxygen species lead to enhanced amyloid beta formation

    NARCIS (Netherlands)

    Leuner, K.; Schutt, T.; Kurz, C.; Eckert, S.H.; Schiller, C.; Occhipinti, A.; Mai, S.; Jendrach, M.; Eckert, G.P.; Kruse, S.E.; Palmiter, R.D.; Brandt, U.; Drose, S.; Wittig, I.; Willem, M.; Haass, C.; Reichert, A.S.; Muller, W.E.

    2012-01-01

    AIMS: Intracellular amyloid beta (Abeta) oligomers and extracellular Abeta plaques are key players in the progression of sporadic Alzheimer's disease (AD). Still, the molecular signals triggering Abeta production are largely unclear. We asked whether mitochondrion-derived reactive oxygen species

  11. An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation

    OpenAIRE

    Gorbanev, Yury; Soriano, Robert; O'Connell, Deborah; Chechik, Victor

    2016-01-01

    Non-thermal atmospheric pressure ('cold') plasmas have received increased attention in recent years due to their significant biomedical potential. The reactions of cold plasma with the surrounding atmosphere yield a variety of reactive species, which can define its effectiveness. While efficient development of cold plasma therapy requires kinetic models, model benchmarking needs empirical data. Experimental studies of the source of reactive species detected in aqueous solutions exposed to pla...

  12. Mineralogy, geologic and physico-chemical characteristics of uranotitanate formation

    International Nuclear Information System (INIS)

    Korolev, K.G.; Miguta, A.K.; Polyakova, V.M.; Rumyantseva, G.V.

    1979-01-01

    Results of experimental and field study of varieties of brannerite and davidite are described. Special attention is paid to medium-low temperature variety of brannerite, which is the component of the majority of known uranotitanate ores. Natural concentrations of uranium are characterized: geologic peculiarities of their localization, mineral paragenesis, periore alterations. Syntheses of brannerite and davidite have been realized for the first time under hydrothermal conditions. Complex multiphase products of uranium titanate transformation, decomposition reactions of brannerite into constituent oxides in particular. Peculiarities of uranium and titanium migration in aqueous solutions at high temperatures and pressures are discussed. The processes of brannerite and davidite formation in hydrothermal conditions and from the melts are considered. Application of thermodynamic calculations of equilibria to the reactions of solid phase formation out of diluted ( -6 M) solutions and to the solid dispersoids in general is found to be erroneous as the formation of the latters is connected with kinetic phenomena

  13. Linkages between aggregate formation, porosity and soil chemical properties

    NARCIS (Netherlands)

    Regelink, I.C.; Stoof, C.R.; Rousseva, S.; Weng, L.; Lair, G.J.; Kram, P.; Nikolaidis, N.P.; Kercheva, M.; Banwart, S.; Comans, R.N.J.

    2015-01-01

    Linkages between soil structure and physical–chemical soil properties are still poorly understood due to the wide size-range at which aggregation occurs and the variety of aggregation factors involved. To improve understanding of these processes, we collected data on aggregate fractions, soil

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-05-15

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

  15. Chemical reactivity of α-isosaccharinic acid in heterogeneous alkaline systems

    International Nuclear Information System (INIS)

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

    2008-11-01

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

  16. Chemical reactivity of α-isosaccharinic acid in heterogeneous alkaline systems

    International Nuclear Information System (INIS)

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

    2009-05-01

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

  17. Heterogeneously catalyzed reactive extraction for biomass valorization into chemicals and fuels

    NARCIS (Netherlands)

    Ordomskiy, V.; Khodakov, A.Y.; Nijhuis, T.A.; Schouten, J.C.

    2015-01-01

    This paper focuses on the heterogeneously catalyzed reactive extraction and separation in reaction steps in organic and aqueous phases during the transformation of biomass derived products. Two approaches are demonstrated for decomposing and preserving routes for biomass transformation into valuable

  18. NODC Standard Format Marine Toxic Substances and Pollutants (F144) chemical identification codes (NODC Accession 9200273)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival information package contains a listing of codes and chemical names that were used in NODC Standard Format Marine Toxic Substances and Pollutants (F144)...

  19. Continuous flow chemistry: a discovery tool for new chemical reactivity patterns.

    Science.gov (United States)

    Hartwig, Jan; Metternich, Jan B; Nikbin, Nikzad; Kirschning, Andreas; Ley, Steven V

    2014-06-14

    Continuous flow chemistry as a process intensification tool is well known. However, its ability to enable chemists to perform reactions which are not possible in batch is less well studied or understood. Here we present an example, where a new reactivity pattern and extended reaction scope has been achieved by transferring a reaction from batch mode to flow. This new reactivity can be explained by suppressing back mixing and precise control of temperature in a flow reactor set up.

  20. Continuous flow chemistry: a discovery tool for new chemical reactivity patterns

    OpenAIRE

    Hartwig, Jan; Metternich, Jan B.; Nikbin, Nikzad; Kirschning, Andreas; Ley, Steven V.

    2014-01-01

    Continuous flow chemistry as a process intensification tool is well known. However, its ability to enable chemists to perform reactions which are not possible in batch is less well studied or understood. Here we present an example, where a new reactivity pattern and extended reaction scope has been achieved by transferring a reaction from batch mode to flow. This new reactivity can be explained by suppressing back mixing and precise control of temperature in a flow reactor set up.

  1. The reactivity of natural organic matter to disinfection by-products formation and its relation to specific ultraviolet absorbance.

    Science.gov (United States)

    Kitis, M; Karanfil, T; Kilduff, J E; Wigton, A

    2001-01-01

    Five natural waters with a broad range of DOC concentrations were fractionated using various coal- and wood-based granular activated carbons (GAC) and alum coagulation. Adsorption and alum coagulation fractionated NOM solutions by preferentially removing components having high specific ultraviolet absorbance (SUVA). UV absorbing fractions of NOM were found to be the major contributors to DBP formation. SUVA appears to be an accurate predictor of reactivity with chlorine in terms of DBP yield; however, it was also found that low-SUVA components of NOM have higher bromine incorporation. SUVA has promise as a parameter for on-line monitoring and control of DBP formation in practical applications; however, the effects of bromide concentration may also need to be considered. Understanding how reactivity is correlated to SUVA may allow utilities to optimize the degree of treatment required to comply with DBP regulations. The reactive components that require removal, and the degree of treatment necessary to accomplish this removal, may be directly obtained from the relationship between SUVA removal and the degree of treatment (e.g., alum dose).

  2. Re-activation of degraded nickel cermet anodes - Nano-particle formation via reverse current pulses

    DEFF Research Database (Denmark)

    Hauch, Anne; Marchese, M.; Lanzini, A.

    2018-01-01

    The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode is theref......The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode...

  3. Chemical signal activation of an organocatalyst enables control over soft material formation.

    Science.gov (United States)

    Trausel, Fanny; Maity, Chandan; Poolman, Jos M; Kouwenberg, D S J; Versluis, Frank; van Esch, Jan H; Eelkema, Rienk

    2017-10-12

    Cells can react to their environment by changing the activity of enzymes in response to specific chemical signals. Artificial catalysts capable of being activated by chemical signals are rare, but of interest for creating autonomously responsive materials. We present an organocatalyst that is activated by a chemical signal, enabling temporal control over reaction rates and the formation of materials. Using self-immolative chemistry, we design a deactivated aniline organocatalyst that is activated by the chemical signal hydrogen peroxide and catalyses hydrazone formation. Upon activation of the catalyst, the rate of hydrazone formation increases 10-fold almost instantly. The responsive organocatalyst enables temporal control over the formation of gels featuring hydrazone bonds. The generic design should enable the use of a large range of triggers and organocatalysts, and appears a promising method for the introduction of signal response in materials, constituting a first step towards achieving communication between artificial chemical systems.Enzymes regulated by chemical signals are common in biology, but few such artificial catalysts exist. Here, the authors design an aniline catalyst that, when activated by a chemical trigger, catalyses formation of hydrazone-based gels, demonstrating signal response in a soft material.

  4. Core Flooding Experiments and Reactive Transport Modeling of Seasonal Heat Storage in the Hot Deep Gassum Sandstone Formation

    DEFF Research Database (Denmark)

    Holmslykke, Hanne D.; Kjøller, Claus; Fabricius, Ida Lykke

    2017-01-01

    Seasonal storage of excess heat in hot deep aquifers is considered to optimize the usage of commonly available energy sources. The chemical effects of heating the Gassum Sandstone Formation to up to 150 degrees C is investigated by combining laboratory core flooding experiments with petrographic...... analysis and geochemical modeling. Synthetic formation water is injected into two sets of Gassum Formation samples at 25, 50 (reservoir temperature), 100, and 150 degrees C with a velocity of 0.05 and 0.1 PV/h, respectively. Results show a significant increase in the aqueous concentration of silicium...

  5. Metal-assisted chemical etch porous silicon formation method

    Science.gov (United States)

    Li, Xiuling; Bohn, Paul W.; Sweedler, Jonathan V.

    2004-09-14

    A thin discontinuous layer of metal such as Au, Pt, or Au/Pd is deposited on a silicon surface. The surface is then etched in a solution including HF and an oxidant for a brief period, as little as a couple seconds to one hour. A preferred oxidant is H.sub.2 O.sub.2. Morphology and light emitting properties of porous silicon can be selectively controlled as a function of the type of metal deposited, Si doping type, silicon doping level, and/or etch time. Electrical assistance is unnecessary during the chemical etching of the invention, which may be conducted in the presence or absence of illumination.

  6. Bainite Formation in Medium-Carbon Low-Silicon Spring Steels Accounting for Chemical Segregation

    NARCIS (Netherlands)

    Goulas, C.; Mecozzi, M.G.; Sietsma, J.

    2016-01-01

    In this paper, the effect of chemical inhomogeneity on the isothermal bainite formation is investigated in medium-carbon low-silicon spring steel by dilatometry and microscopy. The analysis of the microstructure at different times during transformation shows that chemical segregation of

  7. Crystal chemical analysis of formation of solid solutions on the basis of compounds with garnet structure

    International Nuclear Information System (INIS)

    Kuz'micheva, G.M.; Kozlikin, S.N.

    1989-01-01

    Crystal chemical formulas permitting to evaluate the character of changes in interatomic distances during isomorphous substitution and, hence, the probability of formation of internal solid solutions and successive isomorphous substitution, are presented. The possibility of formation of introduction solid solutions is considered, using as an example Sc, Y oxides, rare earths with garnet structure

  8. Formation, reactivity and aging of amorphous ferric oxides in the presence of model and membrane bioreactor derived organics.

    Science.gov (United States)

    Bligh, Mark W; Maheshwari, Pradeep; David Waite, T

    2017-11-01

    Iron salts are routinely dosed in wastewater treatment as a means of achieving effluent phosphorous concentration goals. The iron oxides that result from addition of iron salts partake in various reactions, including reductive dissolution and phosphate adsorption. The reactivity of these oxides is controlled by the conditions of formation and the processes, such as aggregation, that lead to a reduction in accessible surface sites following formation. The presence of organic compounds is expected to significantly impact these processes in a number of ways. In this study, amorphous ferric oxide (AFO) reactivity and aging was investigated following the addition of ferric iron (Fe(III)) to three solution systems: two synthetic buffered systems, either containing no organic or containing alginate, and a supernatant system containing soluble microbial products (SMPs) sourced from a membrane bioreactor (MBR). Reactivity of the Fe(III) phases in these systems at various times (1-60 min) following Fe(III) addition was quantified by determining the rate constants for ascorbate-mediated reductive dissolution over short (5 min) and long (60 min) dissolution periods and for a range (0.5-10 mM) of ascorbate concentrations. AFO particle size was monitored using dynamic light scattering during the aging and dissolution periods. In the presence of alginate, AFO particles appeared to be stabilized against aggregation. However, aging in the alginate system was remarkably similar to the inorganic system where aging is associated with aggregation. An aging mechanism involving restructuring within the alginate-AFO assemblage was proposed. In the presence of SMPs, a greater diversity of Fe(III) phases was evident with both a small labile pool of organically complexed Fe(III) and a polydisperse population of stabilized AFO particles present. The prevalence of low molecular weight organic molecules facilitated stabilization of the Fe(III) oxyhydroxides formed but subsequent aging

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

    Science.gov (United States)

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

    2016-10-01

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

  10. Responses of human birch pollen allergen-reactive T cells to chemically modified allergens (allergoids).

    Science.gov (United States)

    Dormann, D; Ebner, C; Jarman, E R; Montermann, E; Kraft, D; Reske-Kunz, A B

    1998-11-01

    Allergoids are widely used in specific immunotherapy for the treatment of IgE-mediated allergic diseases. The aim of this study was to analyse whether a modification of birch pollen allergens with formaldehyde affects the availability of T-cell epitopes. Efficient modification of the allergens was verified by determining IgE and IgG binding activity using ELISA inhibition tests. T-cell responses to birch pollen allergoids were analysed in polyclonal systems, using peripheral blood mononuclear cells (PBMC) of five birch pollen-allergic individuals, as well as birch pollen extract-reactive T-cell lines (TCL), established from the peripheral blood of 14 birch pollen-allergic donors. To determine whether the modification of natural (n)Bet v 1 with formaldehyde or maleic anhydride results in epitope-specific changes in T-cell reactivities, 22 Bet v 1-specific T-cell clones (TCC), established from nine additional birch pollen-allergic individuals, were tested for their reactivity with these products. The majority of PBMC and TCL showed a reduced response to the birch pollen extract allergoid. Bet v 1-specific TCC could be divided into allergoid-reactive and -non-reactive TCC. No simple correlation between possible modification sites of formaldehyde in the respective T-cell epitopes and the stimulatory potential of the allergoid was observed. Mechanisms of suppression or of anergy induction were excluded as an explanation for the non-reactivity of representative TCC. All TCC could be stimulated by maleylated and unmodified nBet v 1 to a similar extent. These results demonstrate differences in the availability of T-cell epitopes between allergoids and unmodified allergens, which are most likely due to structural changes within the allergen molecule.

  11. Simulations of the dispersion of reactive pollutants in a street canyon, considering different chemical mechanisms and micromixing

    Science.gov (United States)

    Garmory, A.; Kim, I. S.; Britter, R. E.; Mastorakos, E.

    The Stochastic Fields (SF) or Field Monte Carlo method has been used to model the dispersion of reactive scalars in a street canyon, using a simple chemistry and the CBM-IV mechanism. SF is a Probability Density Function (PDF) method which allows both means and variances of the scalars to be calculated as well as considering the effect of segregation on reaction rates. It was found that the variance of reactive scalars such as NO 2 was very high in the mixing region at roof-top level with rms values of the order of the mean values. The effect of segregation on major species such as O 3 was found to be very small using either mechanism, however, some radical species in CBM-IV showed a significant difference. These were found to be the seven species with the fastest chemical timescales. The calculated photostationary state defect was also found to be in error when segregation is neglected.

  12. An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation.

    Science.gov (United States)

    Gorbanev, Yury; Soriano, Robert; O'Connell, Deborah; Chechik, Victor

    2016-11-03

    Non-thermal atmospheric pressure ('cold') plasmas have received increased attention in recent years due to their significant biomedical potential. The reactions of cold plasma with the surrounding atmosphere yield a variety of reactive species, which can define its effectiveness. While efficient development of cold plasma therapy requires kinetic models, model benchmarking needs empirical data. Experimental studies of the source of reactive species detected in aqueous solutions exposed to plasma are still scarce. Biomedical plasma is often operated with He or Ar feed gas, and a specific interest lies in investigation of the reactive species generated by plasma with various gas admixtures (O2, N2, air, H2O vapor, etc.) Such investigations are very complex due to difficulties in controlling the ambient atmosphere in contact with the plasma effluent. In this work, we addressed common issues of 'high' voltage kHz frequency driven plasma jet experimental studies. A reactor was developed allowing the exclusion of ambient atmosphere from the plasma-liquid system. The system thus comprised the feed gas with admixtures and the components of the liquid sample. This controlled atmosphere allowed the investigation of the source of the reactive oxygen species induced in aqueous solutions by He-water vapor plasma. The use of isotopically labelled water allowed distinguishing between the species originating in the gas phase and those formed in the liquid. The plasma equipment was contained inside a Faraday cage to eliminate possible influence of any external field. The setup is versatile and can aid in further understanding the cold plasma-liquid interactions chemistry.

  13. A comparative study of changes in immunological reactivity during prolonged introduction of radioactive and chemical substances into the organism with drinking water

    International Nuclear Information System (INIS)

    Shubik, V.M.; Nevstrueva, M.A.; Kalnitskij, S.A.; Livshits, R.E.; Merkushev, G.N.; Pilshchik, E.M.; Ponomareva, T.V.

    1978-01-01

    A comparative study was conducted into the factors of non-specific protection and specific immunity, allergic and autoallergic reactivities during prolonged exposure of experimental animals to 6 different radioactive and 7 harmful chemical substances. Qualitative and quantitative peculiarities were found in the changes in immunological reactivity during the exposure of the organism to radionuclides and stable chemical compounds. Impairment of immunity plays an essential role in the course and the outcome of effects induced by chronic action of the substances examined. (author)

  14. Predicting Formation Damage in Aquifer Thermal Energy Storage Systems Utilizing a Coupled Hydraulic-Thermal-Chemical Reservoir Model

    Science.gov (United States)

    Müller, Daniel; Regenspurg, Simona; Milsch, Harald; Blöcher, Guido; Kranz, Stefan; Saadat, Ali

    2014-05-01

    In aquifer thermal energy storage (ATES) systems, large amounts of energy can be stored by injecting hot water into deep or intermediate aquifers. In a seasonal production-injection cycle, water is circulated through a system comprising the porous aquifer, a production well, a heat exchanger and an injection well. This process involves large temperature and pressure differences, which shift chemical equilibria and introduce or amplify mechanical processes. Rock-fluid interaction such as dissolution and precipitation or migration and deposition of fine particles will affect the hydraulic properties of the porous medium and may lead to irreversible formation damage. In consequence, these processes determine the long-term performance of the ATES system and need to be predicted to ensure the reliability of the system. However, high temperature and pressure gradients and dynamic feedback cycles pose challenges on predicting the influence of the relevant processes. Within this study, a reservoir model comprising a coupled hydraulic-thermal-chemical simulation was developed based on an ATES demonstration project located in the city of Berlin, Germany. The structural model was created with Petrel, based on data available from seismic cross-sections and wellbores. The reservoir simulation was realized by combining the capabilities of multiple simulation tools. For the reactive transport model, COMSOL Multiphysics (hydraulic-thermal) and PHREEQC (chemical) were combined using the novel interface COMSOL_PHREEQC, developed by Wissmeier & Barry (2011). It provides a MATLAB-based coupling interface between both programs. Compared to using COMSOL's built-in reactive transport simulator, PHREEQC additionally calculates adsorption and reaction kinetics and allows the selection of different activity coefficient models in the database. The presented simulation tool will be able to predict the most important aspects of hydraulic, thermal and chemical transport processes relevant to

  15. Model tool to describe chemical structures in XML format utilizing structural fragments and chemical ontology.

    Science.gov (United States)

    Sankar, Punnaivanam; Alain, Krief; Aghila, Gnanasekaran

    2010-05-24

    We have developed a model structure-editing tool, ChemEd, programmed in JAVA, which allows drawing chemical structures on a graphical user interface (GUI) by selecting appropriate structural fragments defined in a fragment library. The terms representing the structural fragments are organized in fragment ontology to provide a conceptual support. ChemEd describes the chemical structure in an XML document (ChemFul) with rich semantics explicitly encoding the details of the chemical bonding, the hybridization status, and the electron environment around each atom. The document can be further processed through suitable algorithms and with the support of external chemical ontologies to generate understandable reports about the functional groups present in the structure and their specific environment.

  16. Physical-chemical mechanisms of pattern formation during gastrulation

    Science.gov (United States)

    Bozorgui, Behnaz; Kolomeisky, Anatoly B.; Teimouri, Hamid

    2018-03-01

    Gastrulation is a fundamental phase during the biological development of most animals when a single layer of identical embryo cells is transformed into a three-layer structure, from which the organs start to develop. Despite a remarkable progress in quantifying the gastrulation processes, molecular mechanisms of these processes remain not well understood. Here we theoretically investigate early spatial patterning in a geometrically confined colony of embryonic stem cells. Using a reaction-diffusion model, a role of Bone-Morphogenetic Protein 4 (BMP4) signaling pathway in gastrulation is specifically analyzed. Our results show that for slow diffusion rates of BMP4 molecules, a new length scale appears, which is independent of the size of the system. This length scale separates the central region of the colony with uniform low concentrations of BMP molecules from the region near the colony edge where the concentration of signaling molecules is elevated. The roles of different components of the signaling pathway are also explained. Theoretical results are consistent with recent in vitro experiments, providing microscopic explanations for some features of early embryonic spatial patterning. Physical-chemical mechanisms of these processes are discussed.

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

    Science.gov (United States)

    Grayson, Scott M.

    2012-01-01

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

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

    Science.gov (United States)

    Irving, Roy M; Pinkerton, Marie E; Elfarra, Adnan A

    2013-02-15

    N-Acetyl-S-(1,2-dichlorovinyl)-L-cysteine (NA-DCVC) has been detected in the urine of humans exposed to trichloroethylene and its related sulfoxide, N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine sulfoxide (NA-DCVCS), has been detected as hemoglobin adducts in blood of rats dosed with S-(1,2-dichlorovinyl)-L-cysteine (DCVC) or S-(1,2-dichlorovinyl)-L-cysteine sulfoxide (DCVCS). Because the in vivo nephrotoxicity of NA-DCVCS was unknown, in this study, male Sprague-Dawley rats were dosed (i.p.) with 230 μmol/kg b.w. NA-DCVCS or its potential precursors, DCVCS or NA-DCVC. At 24 h post treatment, rats given NA-DCVC or NA-DCVCS exhibited kidney lesions and effects on renal function distinct from those caused by DCVCS. NA-DCVC and NA-DCVCS primarily affected the cortico-medullary proximal tubules (S(2)-S(3) segments) while DCVCS primarily affected the outer cortical proximal tubules (S(1)-S(2) segments). When NA-DCVCS or DCVCS was incubated with GSH in phosphate buffer pH 7.4 at 37°C, the corresponding glutathione conjugates were detected, but NA-DCVC was not reactive with GSH. Because NA-DCVCS exhibited a longer half-life than DCVCS and addition of rat liver cytosol enhanced GSH conjugate formation, catalysis of GSH conjugate formation by the liver could explain the lower toxicity of NA-DCVCS in comparison with DCVCS. Collectively, these results provide clear evidence that NA-DCVCS formation could play a significant role in DCVC, NA-DCVC, and trichloroethylene nephrotoxicity. They also suggest a role for hepatic metabolism in the mechanism of NA-DCVC nephrotoxicity. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Single and double carbon vacancies in pyrene as first models for graphene defects: A survey of the chemical reactivity toward hydrogen

    Science.gov (United States)

    Nieman, Reed; Das, Anita; Aquino, Adélia J. A.; Amorim, Rodrigo G.; Machado, Francisco B. C.; Lischka, Hans

    2017-01-01

    Graphene is regarded as one of the most promising materials for nanoelectronics applications. Defects play an important role in modulating its electronic properties and also enhance its chemical reactivity. In this work the reactivity of single vacancies (SV) and double vacancies (DV) in reaction with a hydrogen atom Hr is studied. Because of the complicated open shell electronic structures of these defects due to dangling bonds, multireference configuration interaction (MRCI) methods are being used in combination with a previously developed defect model based on pyrene. Comparison of the stability of products derived from Csbnd Hr bond formation with different carbon atoms of the different polyaromatic hydrocarbons is made. In the single vacancy case the most stable structure is the one where the incoming hydrogen is bound to the carbon atom carrying the dangling bond. However, stable Csbnd Hr bonded structures are also observed in the five-membered ring of the single vacancy. In the double vacancy, most stable bonding of the reactant Hr atom is found in the five-membered rings. In total, Csbnd Hr bonds, corresponding to local energy minimum structures, are formed with all carbon atoms in the different defect systems and the pyrene itself. Reaction profiles for the four lowest electronic states show in the case of a single vacancy a complex picture of curve crossings and avoided crossings which will give rise to a complex nonadiabatic reaction dynamics involving several electronic states.

  20. Formation, aggregation and reactivity of amorphous ferric oxyhydroxides on dissociation of Fe(III)-organic complexes in dilute aqueous suspensions

    Science.gov (United States)

    Bligh, Mark W.; Waite, T. David

    2010-10-01

    While chemical reactions that take place at the surface of amorphous ferric oxides (AFO) are known to be important in aquatic systems, incorporation of these reactions into kinetic models is hindered by a lack of ability to reliably quantify the reactivity of the surface and the changes in reactivity that occur over time. Long term decreases in the reactivity of iron oxides may be considered to result from changes in the molecular structure of the solid, however, over shorter time scales where substantial aggregation may occur, the mechanisms of reactivity loss are less clear. Precipitation of AFO may be described as a combination of homogeneous and heterogeneous reactions, however, despite its potentially significant role, the latter reaction is usually neglected in kinetic models of aquatic processes. Here, we investigate the role of AFO in scavenging dissolved inorganic ferric (Fe(III)) species (Fe') via the heterogeneous precipitation reaction during the net dissociation of organically complexed Fe(III) in seawater. Using sulfosalicylic acid (SSA) as a model ligand, AFO was shown to play a significant role in inducing the net dissociation of the Fe-SSA complexes with equations describing both the heterogeneous precipitation reaction and the aging of AFO being required to adequately describe the experimental data. An aggregation based mechanism provided a good description of AFO aging over the short time scale of the experiments. The behaviour of AFO described here has implications for the bioavailability of iron in natural systems as a result of reactions involving AFO which are recognised to occur over time scales of minutes, including adsorption of Fe' and AFO dissolution, precipitation and ageing.

  1. A theory for bioinorganic chemical reactivity of oxometal complexes and analogous oxidants: the exchange and orbital-selection rules.

    Science.gov (United States)

    Usharani, Dandamudi; Janardanan, Deepa; Li, Chunsen; Shaik, Sason

    2013-02-19

    Over the past decades metalloenzymes and their synthetic models have emerged as an area of increasing research interest. The metalloenzymes and their synthetic models oxidize organic molecules using oxometal complexes (OMCs), especially oxoiron(IV)-based ones. Theoretical studies have helped researchers to characterize the active species and to resolve mechanistic issues. This activity has generated massive amounts of data on the relationship between the reactivity of OMCs and the transition metal's identity, oxidation state, ligand sphere, and spin state. Theoretical studies have also produced information on transition state (TS) structures, reaction intermediates, barriers, and rate-equilibrium relationships. For example, the experimental-theoretical interplay has revealed that nonheme enzymes carry out H-abstraction from strong C-H bonds using high-spin (S = 2) oxoiron(IV) species with four unpaired electrons on the iron center. However, other reagents with higher spin states and more unpaired electrons on the metal are not as reactive. Still other reagents carry out these transformations using lower spin states with fewer unpaired electrons on the metal. The TS structures for these reactions exhibit structural selectivity depending on the reactive spin states. The barriers and thermodynamic driving forces of the reactions also depend on the spin state. H-Abstraction is preferred over the thermodynamically more favorable concerted insertion into C-H bonds. Currently, there is no unified theoretical framework that explains the totality of these fascinating trends. This Account aims to unify this rich chemistry and understand the role of unpaired electrons on chemical reactivity. We show that during an oxidative step the d-orbital block of the transition metal is enriched by one electron through proton-coupled electron transfer (PCET). That single electron elicits variable exchange interactions on the metal, which in turn depend critically on the number of

  2. Investigation of the chemical pathway of gaseous nitrogen dioxide formation during flue gas desulfurization with dry sodium bicarbonate injection

    Science.gov (United States)

    Stein, Antoinette Weil

    The chemical reaction pathway for the viable flue gas desulfurization process, dry sodium bicarbonate injection, was investigated to mitigate undesirable plume discoloration. Based on a foundation of past findings, a simplified three-step reaction pathway was hypothesized for the formation of the plume-discoloring constituent, NO2. As the first step, it was hypothesized that sodium sulfite formed by sodium bicarbonate reaction with flue gas SO 2. As the second step, it was hypothesized that sodium nitrate formed by sodium sulfite reaction with flue gas NO. And as the third step, it was hypothesized that NO2 and sodium sulfate formed by sodium nitrate reaction with SO2. The second and third hypothesized steps were experimentally investigated using an isothermal fixed bed reactor. As reported in the past, technical grade sodium sulfite was found to be un-reactive with NO and O2. Freshly prepared sodium sulfite, maintained unexposed to moist air, was shown to react with NO and O2 resulting in a mixture of sodium nitrite and sodium nitrate together with a significant temperature rise. This reaction was found to proceed only when oxygen was present in the flue gas. As reported in the past, technical grade sodium nitrate was shown to be un-reactive with SO2. But freshly formed sodium nitrate kept unexposed to humidity was found to be reactive with SO2 and O 2 resulting in the formation of NO2 and sodium sulfate polymorphic Form I. The NO2 formation by this reaction was shown to be temperature dependent with maximum formation at 175°C. Plume mitigation methods were studied based on the validated three-step reaction pathway. Mitigation of NO2 was exhibited by limiting oxygen concentration in the flue gas to a level below 5%. It was also shown that significant NO2 mitigation was achieved by operating below 110°C or above 250°C. An innovative NO2 mitigation method was patented as a result of the findings of this study. The patented process incorporated a process step of

  3. Chemical conjugation of cowpea mosaic viruses with reactive HPMA-based polymers

    Czech Academy of Sciences Publication Activity Database

    Laga, Richard; Koňák, Čestmír; Šubr, Vladimír; Ulbrich, Karel; Suthiwangcharoen, N.; Niu, Q.; Wang, Q.

    2010-01-01

    Roč. 21, č. 12 (2010), s. 1669-1685 ISSN 0920-5063 R&D Projects: GA AV ČR KJB400500803; GA ČR GA202/09/2078; GA AV ČR KAN200200651 Institutional research plan: CEZ:AV0Z40500505 Keywords : acylthiazolidine-2-thione reactive groups * bioconjugation * coating Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.842, year: 2010

  4. Transcriptome Sequencing of Chemically Induced Aquilaria sinensis to Identify Genes Related to Agarwood Formation.

    Science.gov (United States)

    Ye, Wei; Wu, Hongqing; He, Xin; Wang, Lei; Zhang, Weimin; Li, Haohua; Fan, Yunfei; Tan, Guohui; Liu, Taomei; Gao, Xiaoxia

    2016-01-01

    Agarwood is a traditional Chinese medicine used as a clinical sedative, carminative, and antiemetic drug. Agarwood is formed in Aquilaria sinensis when A. sinensis trees are threatened by external physical, chemical injury or endophytic fungal irritation. However, the mechanism of agarwood formation via chemical induction remains unclear. In this study, we characterized the transcriptome of different parts of a chemically induced A. sinensis trunk sample with agarwood. The Illumina sequencing platform was used to identify the genes involved in agarwood formation. A five-year-old Aquilaria sinensis treated by formic acid was selected. The white wood part (B1 sample), the transition part between agarwood and white wood (W2 sample), the agarwood part (J3 sample), and the rotten wood part (F5 sample) were collected for transcriptome sequencing. Accordingly, 54,685,634 clean reads, which were assembled into 83,467 unigenes, were obtained with a Q20 value of 97.5%. A total of 50,565 unigenes were annotated using the Nr, Nt, SWISS-PROT, KEGG, COG, and GO databases. In particular, 171,331,352 unigenes were annotated by various pathways, including the sesquiterpenoid (ko00909) and plant-pathogen interaction (ko03040) pathways. These pathways were related to sesquiterpenoid biosynthesis and defensive responses to chemical stimulation. The transcriptome data of the different parts of the chemically induced A. sinensis trunk provide a rich source of materials for discovering and identifying the genes involved in sesquiterpenoid production and in defensive responses to chemical stimulation. This study is the first to use de novo sequencing and transcriptome assembly for different parts of chemically induced A. sinensis. Results demonstrate that the sesquiterpenoid biosynthesis pathway and WRKY transcription factor play important roles in agarwood formation via chemical induction. The comparative analysis of the transcriptome data of agarwood and A. sinensis lays the foundation

  5. Thermogravimetric study on the influence of structural, textural and chemical properties of biomass chars on CO2 gasification reactivity

    International Nuclear Information System (INIS)

    Bouraoui, Zeineb; Jeguirim, Mejdi; Guizani, Chamseddine; Limousy, Lionel; Dupont, Capucine; Gadiou, Roger

    2015-01-01

    The present investigation aims to examine the influence of textural, structural and chemical properties of biomass chars on the CO 2 gasification rate. Various lignocellulosic biomass chars were prepared under the same conditions. Different analytical techniques were used to determine the char properties such as Scanning Electronic Microscopy, nitrogen adsorption manometry, Raman spectroscopy and X Ray Fluorescence. Gasification tests were carried out in a thermobalance under 20% CO 2 in nitrogen at 800 °C. Significant differences of the total average reactivity were observed with a factor of 2 between the prepared chars. Moreover, different behaviors of gasification rate profiles versus conversion were obtained. This difference of behavior appeared to be correlated with the biomass char properties. Hence, up to 70% of conversion, the gasification rate was shown to depend on the char external surface and the potassium content. At higher conversion ratio, a satisfactory correlation between the Catalytic Index and the average gasification rate was identified. The results highlight the importance of knowing both textural and structural properties and mineral contents of biomass chars to predict fuel reactivity during CO 2 gasification processes. Such behavior prediction is highly important in the gasifiers design for char conversion. - Highlights: • CO 2 gasification reactivity of various lignocellulosic chars were examined. • Chars properties affect strongly samples gasification behavior. • Initial gasification rate is affected by external surface, K content and D3/G ratio. • Gasification rate behavior depends on the Alkali index at high conversion

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

    International Nuclear Information System (INIS)

    Irving, Roy M.; Pinkerton, Marie E.; Elfarra, Adnan A.

    2013-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-02-15

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

  8. The Atmospheric Tomography Mission (ATom): Comparing the Chemical Climatology of Reactive Species and Air Parcels from Measurements and Global Models

    Science.gov (United States)

    Prather, M. J.; Flynn, C.; Wennberg, P. O.; Kim, M. J.; Ryerson, T. B.; Hanisco, T. F.; Diskin, G. S.; Daube, B. C.; Commane, R.; McKain, K.; Apel, E. C.; Blake, N. J.; Blake, D. R.; Elkins, J. W.; Hall, S.; Steenrod, S.; Strahan, S. E.; Lamarque, J. F.; Fiore, A. M.; Horowitz, L. W.; Murray, L. T.; Mao, J.; Shindell, D. T.; Wofsy, S. C.

    2017-12-01

    The NASA Atmospheric Tomography Mission (ATom) is building a photochemical climatology of the remote troposphere based on objective sampling and profiling transects over the Pacific and Atlantic Oceans. These statistics provide direct tests of chemistry-climate models. The choice of species focuses on those controlling primary reactivity (a.k.a. oxidative state) of the troposphere, specifically chemical tendencies of O3 and CH4. These key species include, inter alia, O3, CH4, CO, C2H6, other alkanes, alkenes, aromatics, NOx, HNO3, HO2NO2, PAN, other organic nitrates, H2O, HCHO, H2O2, CH3OOH. Three of the four ATom deployments are now complete, and data from the first two (ATom-1 & -2) have been released as of this talk (see espoarchive.nasa.gov/archive/browse/atom). The statistical distributions of key species are presented as 1D and 2D probability densities (PDs) and we focus here on the tropical and mid-latitude regions of the Pacific during ATom-1 (Aug) and -2 (Feb). PDs are computed from ATom observations and 6 global chemistry models over the tropospheric depth (0-12 km) and longitudinal extent of the observations. All data are weighted to achieve equal mass-weighting by latitude regimes to account for spatial sampling biases. The models are used to calculate the reactivity in each ATom air parcel. Reweighting parcels with loss of CH4 or production of O3, for example, allows us to identify which air parcels are most influential, including assessment of the importance of fine pollution layers in the most remote troposphere. Another photochemical climatology developed from ATom, and used to test models, includes the effect of clouds on photolysis rates. The PDs and reactivity-weighted PDs reveal important seasonal differences and similarities between the two campaigns and also show which species may be most important in controlling reactivities. They clearly identify some very specific failings in the modeled climatologies and help us evaluate the chemical

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

    Science.gov (United States)

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

    2015-12-05

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

  10. Formation and detoxification of reactive intermediates in the metabolism of chlorinated ethenes

    NARCIS (Netherlands)

    van Hylckama Vlieg, Johan E.T.; Janssen, DB

    2001-01-01

    Short-chain halogenated aliphatics, such as chlorinated ethenes, constitute a large group of priority pollutants. This paper gives an overview on the chemical and physical properties of chlorinated aliphatics that are critical in determining their toxicological characteristics and recalcitrance to

  11. Reactive transport model of the formation of oxide-type Ni-laterite profiles (Punta Gorda, Moa Bay, Cuba)

    Science.gov (United States)

    Domènech, Cristina; Galí, Salvador; Villanova-de-Benavent, Cristina; Soler, Josep M.; Proenza, Joaquín A.

    2017-10-01

    Oxide-type Ni-laterite deposits are characterized by a dominant limonite zone with goethite as the economically most important Ni ore mineral and a thin zone of hydrous Mg silicate-rich saprolite beneath the magnesium discontinuity. Fe, less soluble, is mainly retained forming goethite, while Ni is redeposited at greater depth in a Fe(III) and Ni-rich serpentine (serpentine II) or in goethite, where it adsorbs or substitutes for Fe in the mineral structure. Here, a 1D reactive transport model, using CrunchFlow, of Punta Gorda oxide-type Ni-laterite deposit (Moa Bay, Cuba) formation is presented. The model reproduces the formation of the different laterite horizons in the profile from an initial, partially serpentinized peridotite, in 106 years, validating the conceptual model of the formation of this kind of deposits in which a narrow saprolite horizon rich in Ni-bearing serpentine is formed above peridotite parent rock and a thick limonite horizon is formed over saprolite. Results also confirm that sorption of Ni onto goethite can explain the weight percent of Ni found in the Moa goethite. Sensitivity analyses accounting for the effect of key parameters (composition, dissolution rate, carbonate concentration, quartz precipitation) on the model results are also presented. It is found that aqueous carbonate concentration and quartz precipitation significantly affects the laterization process rate, while the effect of the composition of secondary serpentine or of mineral dissolution rates is minor. The results of this reactive transport modeling have proven useful to validate the conceptual models derived from field observations.

  12. Acoustic sensors for the control of liquid-solid interface evolution and chemical reactivity

    International Nuclear Information System (INIS)

    Ferrandis, J.Y.; Tingry, S.; Attal, J.; Seta, P.

    2006-01-01

    Less classical than far-field acoustic investigations of solid materials and/or solid-liquid interfaces, near-field acoustic properties of an acoustic solid wave guide (tip), thin enough at its termination to present an external diameter smaller than the excitation acoustic wave wavelength, is shown to be able to probe interface properties. As a result of that, these near-field acoustic probes can play the role of chemical sensors, if chemical modifications or chemical reactions are concerned at their surface. In that context, a chemical sensor was realized by electrochemical deposition of an electron-conducting polymer (polypyrrole-biotin) on a metal tip, followed by enzyme attachment by molecular recognition process involving the biotin-avidin-specific interaction. Results from near-field acoustic showed that the enzyme modification of the polymer layer can be detected by this new acoustic sensor

  13. Study of fuel powder formation in reactive coaxial jets; Etude de la formation de poudre dans des jets coaxiaux reactifs

    Energy Technology Data Exchange (ETDEWEB)

    Ablitzer, C

    1999-11-09

    One step of the conversion of gaseous UF{sub 6} to solid UO{sub 2} by dry route is the formation of particles of UO{sub 2}F{sub 2} in a triple coaxial jet UF{sub 6}/N{sub 2}/H{sub 2}O. The characteristics of resulting powder have an influence on the properties of final particles of UO{sub 2}, and then on the quality of pellets of nuclear fuel. So a good control of this step of the process is of interest. This study deals with an experimental investigation and modelling of the influence of various parameters on particles obtained by reaction in a turbulent coaxial jet. For example, the influence of absolute and relative velocities of gases on particle size distributions has been investigated. Two kinds of experimental studies have been undertaken. First, the development of mixing layers in the near field of the jet has been evaluated with temperature measurements. Then, particle size distributions have been measured with e turbidimetric sensor, for particles obtained by hydrolysis of gaseous metallic chlorides (SnCl{sub 4}, TiCl{sub 4}) in double and triple coaxial jets. A model has been proposed for mixing of gases and growth of particles. It takes into account the development of mixing layers, meso-mixing, micro-mixing and growth of particles through agglomeration. The influence of operating parameters, especially velocities, on experimental results appear to be different for TiCl{sub 4}/H{sub 2}O jets and SnCl{sub 4}/H{sub 2}O jets. In fact, a comparison of theoretical and experimental results shows that particles obtained by hydrolysis of TiCl{sub 4} seem to grow mainly through agglomeration whereas another growth phenomenon may be involved for particles obtained by hydrolysis of SnCl{sub 4}. (authors)

  14. Effects of the oxygenation level on formation of different reactive oxygen species during photodynamic therapy.

    Science.gov (United States)

    Price, Michael; Heilbrun, Lance; Kessel, David

    2013-01-01

    We examined the effect of the oxygenation level on efficacy of two photosensitizing agents, both of which target lysosomes for photodamage, but via different photochemical pathways. Upon irradiation, the chlorin termed NPe6 forms singlet oxygen in high yield while the bacteriopheophorbide WST11 forms only oxygen radicals (in an aqueous environment). Photokilling efficacy by WST11 in cell culture was impaired when the atmospheric oxygen concentration was reduced from 20% to 1%, while photokilling by NPe6 was unaffected. Studies in a cell-free system revealed that the rates of photobleaching of these agents, as a function of the oxygenation level, were correlated with results described above. Moreover, the rate of formation of oxygen radicals by either agent was more sensitive to the level of oxygenation than was singlet oxygen formation by NPe6. These data indicate that the photochemical process that leads to oxygen radical formation is more dependent on the oxygenation level than is the pathway leading to formation of singlet oxygen. © 2013 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2013 The American Society of Photobiology.

  15. The role of chemical admixtures in the formation of the structure of cement stone

    Directory of Open Access Journals (Sweden)

    Sopov Viktor

    2017-01-01

    Full Text Available The influence of sulfates and carbonates of potassium and sodium on the character of the formation of the microstructure of cement stone was studied. The role of cations in the structure formation of cement stone is shown. The efficiency of chemical additives, hardening accelerators, was estimated from the ratio of the volumes of gel and capillary micropores. The ratio of gel and capillary pores allows to determine the efficiency coefficient of the action of chemical additives. It is shown that the potassium carbonate for Portland cement is the most effective additive for hardening in terms of microstructure modification, and potassium sulfate for slag Portland cement.

  16. The mystery of gold's chemical activity: local bonding, morphology and reactivity of atomic oxygen.

    Science.gov (United States)

    Baker, Thomas A; Liu, Xiaoying; Friend, Cynthia M

    2011-01-07

    Recently, gold has been intensely studied as a catalyst for key synthetic reactions. Gold is an attractive catalyst because, surprisingly, it is highly active and very selective for partial oxidation processes suggesting promise for energy-efficient "green" chemistry. The underlying origin of the high activity of Au is a controversial subject since metallic gold is commonly thought to be inert. Herein, we establish that one origin of the high activity for gold catalysis is the extremely reactive nature of atomic oxygen bound in 3-fold coordination sites on metallic gold. This is the predominant form of O at low concentrations on the surface, which is a strong indication that it is most relevant to catalytic conditions. Atomic oxygen bound to metallic Au in 3-fold sites has high activity for CO oxidation, oxidation of olefins, and oxidative transformations of alcohols and amines. Among the factors identified as important in Au-O interaction are the morphology of the surface, the local binding site of oxygen, and the degree of order of the oxygen overlayer. In this Perspective, we present an overview of both theory and experiments that identify the reactive forms of O and their associated charge density distributions and bond strengths. We also analyze and model the release of Au atoms induced by O binding to the surface. This rough surface also has the potential for O(2) dissociation, which is a critical step if Au is to be activated catalytically. We further show the strong parallels between product distributions and reactivity for O-covered Au at low pressure (ultrahigh vacuum) and for nanoporous Au catalysts operating at atmospheric pressure as evidence that atomic O is the active species under working catalytic conditions when metallic Au is present. We briefly discuss the possible contributions of oxidants that may contain intact O-O bonds and of the Au-metal oxide support interface in Au catalysis. Finally, the challenges and future directions for fully

  17. Establishment and intra-/inter-laboratory validation of a standard protocol of reactive oxygen species assay for chemical photosafety evaluation.

    Science.gov (United States)

    Onoue, Satomi; Hosoi, Kazuhiro; Wakuri, Shinobu; Iwase, Yumiko; Yamamoto, Toshinobu; Matsuoka, Naoko; Nakamura, Kazuichi; Toda, Tsuguto; Takagi, Hironori; Osaki, Naoto; Matsumoto, Yasuhiro; Kawakami, Satoru; Seto, Yoshiki; Kato, Masashi; Yamada, Shizuo; Ohno, Yasuo; Kojima, Hajime

    2013-11-01

    A reactive oxygen species (ROS) assay was previously developed for photosafety evaluation of pharmaceuticals, and the present multi-center study aimed to establish and validate a standard protocol for ROS assay. In three participating laboratories, two standards and 42 coded chemicals, including 23 phototoxins and 19 nonphototoxic drugs/chemicals, were assessed by the ROS assay according to the standardized protocol. Most phototoxins tended to generate singlet oxygen and/or superoxide under UV-vis exposure, but nonphototoxic chemicals were less photoreactive. In the ROS assay on quinine (200 µm), a typical phototoxic drug, the intra- and inter-day precisions (coefficient of variation; CV) were found to be 1.5-7.4% and 1.7-9.3%, respectively. The inter-laboratory CV for quinine averaged 15.4% for singlet oxygen and 17.0% for superoxide. The ROS assay on 42 coded chemicals (200 µm) provided no false negative predictions upon previously defined criteria as compared with the in vitro/in vivo phototoxicity, although several false positives appeared. Outcomes from the validation study were indicative of satisfactory transferability, intra- and inter-laboratory variability, and predictive capacity of the ROS assay. Copyright © 2012 John Wiley & Sons, Ltd.

  18. Radiation-chemical formation of acids in polyvinyl butyral films with chlorinated additives

    International Nuclear Information System (INIS)

    Kriminiskaya, Z.K.

    1993-01-01

    Radiochromic indicators are commonly produced by reacting an indicator dye with an acid formed inside a polymer by irradiation. Halogenated and unhalogenated polymers were used, the latter containing halogenated organics. It was therefore of interest to study the formation of acid in polyvinyl butyral (PVD) with addition of a halogenated compound. Yields were measured of radiation-chemical acid formation in PVB films containing chloral hydrate and hexachloroethane. 5 refs., 1 fig., 2 tabs

  19. Quantum chemical study of the structure, spectroscopy and reactivity of NO+.(H2O)n=1-5 clusters

    Science.gov (United States)

    Linton, Kirsty A.; Wright, Timothy G.; Besley, Nicholas A.

    2018-03-01

    Quantum chemical methods including Møller-Plesset perturbation (MP2) theory and density functional theory (DFT) have been used to study the structure, spectroscopy and reactivity of NO+.(H2O)n=1-5 clusters. MP2/6-311++G** calculations are shown to describe the structure and spectroscopy of the clusters well. DFT calculations with exchange-correlation functionals with a low fraction of Hartree-Fock exchange give a binding energy of NO+.(H2O) that is too high and incorrectly predict the lowest energy structure of NO+.(H2O)2, and this error may be associated with a delocalization of charge onto the water molecule directly binding to NO+. Ab initio molecular dynamics (AIMD) simulations were performed to study the NO+.(H2O)5 H+.(H2O)4 + HONO reaction to investigate the formation of HONO from NO+.(H2O)5. Whether an intracluster reaction to form HONO is observed depends on the level of electronic structure theory used. Of note is that methods that accurately describe the relative energies of the product and reactant clusters did not show reactions on the timescales studied. This suggests that in the upper atmosphere the reaction may occur owing to the energy present in the NO+.(H2O)5 complex following its formation. This article is part of the theme issue `Modern theoretical chemistry'.

  20. Modeling the transport of chemical warfare agents and simulants in polymeric substrates for reactive decontamination

    Science.gov (United States)

    Pearl, Thomas; Mantooth, Brent; Varady, Mark; Willis, Matthew

    2014-03-01

    Chemical warfare agent simulants are often used for environmental testing in place of highly toxic agents. This work sets the foundation for modeling decontamination of absorbing polymeric materials with the focus on determining relationships between agents and simulants. The correlations of agents to simulants must consider the three way interactions in the chemical-material-decontaminant system where transport and reaction occur in polymer materials. To this end, diffusion modeling of the subsurface transport of simulants and live chemical warfare agents was conducted for various polymer systems (e.g., paint coatings) with and without reaction pathways with applied decontamination. The models utilized 1D and 2D finite difference diffusion and reaction models to simulate absorption and reaction in the polymers, and subsequent flux of the chemicals out of the polymers. Experimental data including vapor flux measurements and dynamic contact angle measurements were used to determine model input parameters. Through modeling, an understanding of the relationship of simulant to live chemical warfare agent was established, focusing on vapor emission of agents and simulants from materials.

  1. Microwave-induced electrostatic etching: generation of highly reactive magnesium for application in Grignard reagent formation.

    Science.gov (United States)

    van de Kruijs, Bastiaan H P; Dressen, Mark H C L; Meuldijk, Jan; Vekemans, Jef A J M; Hulshof, Lumbertus A

    2010-04-07

    A detailed study regarding the influence of microwave irradiation on the formation of a series of Grignard reagents in terms of rates and selectivities has revealed that these heterogeneous reactions may display a beneficial microwave effect. The interaction between microwaves and magnesium turnings generates violent electrostatic discharges. These discharges on magnesium lead to melting of the magnesium surface, thus generating highly active magnesium particles. As compared to conventional operation the microwave-induced discharges on the magnesium surface lead to considerably shorter initiation times for the insertion of magnesium in selected substrates (i.e. halothiophenes, halopyridines, octyl halides, and halobenzenes). Thermographic imaging and surface characterization by scanning electron microscopy showed that neither selective heating nor a "specific" microwave effect was causing the reduction in initiation times. This novel and straightforward initiation method eliminates the use of toxic and environmentally adverse initiators. Thus, this initiation method limits the formation of by-products. We clearly demonstrated that microwave irradiation enables fast Grignard reagent formation. Therefore, microwave technology is promising for process intensification of Grignard based coupling reactions.

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

    Science.gov (United States)

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

    2018-02-01

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

  3. Cold stress increases reactive oxygen species formation via TRPA1 activation in A549 cells.

    Science.gov (United States)

    Sun, Wenwu; Wang, Zhonghua; Cao, Jianping; Cui, Haiyang; Ma, Zhuang

    2016-03-01

    Reactive oxygen species (ROS) are responsible for lung damage during inhalation of cold air. However, the mechanism of the ROS production induced by cold stress in the lung is still unclear. In this work, we measured the changes of ROS and the cytosolic Ca(2+) concentration ([Ca(2+)]c) in A549 cell. We observed that cold stress (from 20 to 5 °C) exposure of A549 cell resulted in an increase of ROS and [Ca(2+)]c, which was completely attenuated by removing Ca(2+) from medium. Further experiments showed that cold-sensing transient receptor potential subfamily member 1 (TRPA1) agonist (allyl isothiocyanate, AITC) increased the production of ROS and the level of [Ca(2+)]c in A549 cell. Moreover, HC-030031, a TRPA1 selective antagonist, significantly inhibited the enhanced ROS and [Ca(2+)]c induced by AITC or cold stimulation, respectively. Taken together, these data demonstrated that TRPA1 activation played an important role in the enhanced production of ROS induced by cold stress in A549 cell.

  4. The epigenetic landscape related to reactive oxygen species formation in the cardiovascular system.

    Science.gov (United States)

    Kietzmann, Thomas; Petry, Andreas; Shvetsova, Antonina; Gerhold, Joachim M; Görlach, Agnes

    2017-06-01

    Cardiovascular diseases are among the leading causes of death worldwide. Reactive oxygen species (ROS) can act as damaging molecules but also represent central hubs in cellular signalling networks. Increasing evidence indicates that ROS play an important role in the pathogenesis of cardiovascular diseases, although the underlying mechanisms and consequences of pathophysiologically elevated ROS in the cardiovascular system are still not completely resolved. More recently, alterations of the epigenetic landscape, which can affect DNA methylation, post-translational histone modifications, ATP-dependent alterations to chromatin and non-coding RNA transcripts, have been considered to be of increasing importance in the pathogenesis of cardiovascular diseases. While it has long been accepted that epigenetic changes are imprinted during development or even inherited and are not changed after reaching the lineage-specific expression profile, it becomes more and more clear that epigenetic modifications are highly dynamic. Thus, they might provide an important link between the actions of ROS and cardiovascular diseases. This review will provide an overview of the role of ROS in modulating the epigenetic landscape in the context of the cardiovascular system. This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc. © 2017 The British Pharmacological Society.

  5. Typical parameters of the plasma chemical similarity in non-isothermal reactive plasmas

    International Nuclear Information System (INIS)

    Gundermann, S.; Jacobs, H.; Miethke, F.; Rutsher, A.; Wagner, H.E.

    1996-01-01

    The substance of physical similarity principles is contained in parameters which govern the comparison of different realizations of a model device. Because similarity parameters for non-isothermal plasma chemical reactors are unknown to a great extent, an analysis of relevant equations is given together with some experimental results. Modelling of the reactor and experimental results for the ozone synthesis are presented

  6. Electrochemical and Quantum Chemical Study of Reactivity of Orthophthalaldehyde with Aliphatic Primary Amines

    Czech Academy of Sciences Publication Activity Database

    Donkeng Dazie, Joel; Liška, Alan; Ludvík, Jiří

    2016-01-01

    Roč. 163, č. 9 (2016), G127-G132 ISSN 0013-4651 R&D Projects: GA ČR GA13-21704S Institutional support: RVO:61388955 Keywords : electrochemistry * quantum chemical study * amines Subject RIV: CG - Electrochemistry Impact factor: 3.259, year: 2016

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

    NARCIS (Netherlands)

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

    2007-01-01

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

  8. Oxoferryl-Porphyrin Radical Catalytic Intermediate in Cytochrome bd Oxidases Protects Cells from Formation of Reactive Oxygen Species*

    Science.gov (United States)

    Paulus, Angela; Rossius, Sebastiaan Gijsbertus Hendrik; Dijk, Madelon; de Vries, Simon

    2012-01-01

    The quinol-linked cytochrome bd oxidases are terminal oxidases in respiration. These oxidases harbor a low spin heme b558 that donates electrons to a binuclear heme b595/heme d center. The reaction with O2 and subsequent catalytic steps of the Escherichia coli cytochrome bd-I oxidase were investigated by means of ultra-fast freeze-quench trapping followed by EPR and UV-visible spectroscopy. After the initial binding of O2, the O–O bond is heterolytically cleaved to yield a kinetically competent heme d oxoferryl porphyrin π-cation radical intermediate (compound I) magnetically interacting with heme b595. Compound I accumulates to 0.75–0.85 per enzyme in agreement with its much higher rate of formation (∼20,000 s−1) compared with its rate of decay (∼1,900 s−1). Compound I is next converted to a short lived heme d oxoferryl intermediate (compound II) in a phase kinetically matched to the oxidation of heme b558 before completion of the reaction. The results indicate that cytochrome bd oxidases like the heme-copper oxidases break the O–O bond in a single four-electron transfer without a peroxide intermediate. However, in cytochrome bd oxidases, the fourth electron is donated by the porphyrin moiety rather than by a nearby amino acid. The production of reactive oxygen species by the cytochrome bd oxidase was below the detection level of 1 per 1000 turnovers. We propose that the two classes of terminal oxidases have mechanistically converged to enzymes in which the O–O bond is broken in a single four-electron transfer reaction to safeguard the cell from the formation of reactive oxygen species. PMID:22287551

  9. NO oxidation on Zeolite Supported Cu Catalysts: Formation and Reactivity of Surface Nitrates

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hai-Ying; Wei, Zhehao; Kollar, Marton; Gao, Feng; Wang, Yilin; Szanyi, Janos; Peden, Charles HF

    2016-04-18

    The comparative activities of a small-pore Cu-CHA and a large-pore Cu-BEA catalyst for the selective catalytic reduction (SCR) of NOx with NH3, and for the oxidation of NO to NO2 and the subsequent formation of surface nitrates were investigated. Although both catalysts are highly active in SCR reactions, they exhibit very low NO oxidation activity. Furthermore, Cu-CHA is even less active than Cu-BEA in catalyzing NO oxidation but is clearly more active for SCR reactions. Temperature-programed desorption (TPD) experiments following the adsorption of (NO2 + NO + O2) with different NO2:NO ratios reveal that the poor NO oxidation activity of the two catalysts is not due to the formation of stable surface nitrates. On the contrary, NO is found to reduce and decompose the surface nitrates on both catalysts. To monitor the reaction pathways, isotope exchange experiments were conducted by using 15NO to react with 14N-nitrate covered catalyst surfaces. The evolution of FTIR spectra during the isotope exchange process demonstrates that 14N-nitrates are simply displaced with no formation of 15N-nitrates on the Cu-CHA sample, which is clearly different from that observed on the Cu-BEA sample where formation of 15N-nitrates is apparent. The results suggest that the formal oxidation state of N during the NO oxidation on Cu-CHA mainly proceeds from its original +2 to a +3 oxidation state, whereas reaching a higher oxidation state for N, such as +4 or +5, is possible on Cu-BEA. The authors at PNNL gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

  10. Steric control of reactivity: formation of oximes, benzodiazepinone N-oxides and isoxazoloquinolinones

    OpenAIRE

    Heaney, Frances; Bourke, Sharon; Cunningham, Desmond; McArdle, Patrick

    1998-01-01

    Reaction of the alkenyl carbonyl compounds 1 with hydroxylamine can lead to the formation of the oximes 2, the benzodiazepinone N-oxides 3 or the isoxazoloquinolinones 5. The product(s) of reaction are shown to depend on the electronic nature of the terminal olefinic substituent R3 and the space filling capacity of the substituents R1, R2 and R4. When the olefinic centre is electron poor (R3 = CO2Et) ketocarbonyls convert exclusively to bicyclic nitrones 3 whereas aldehydes are more sensitive...

  11. Surface area and chemical reactivity characteristics of uranium metal corrosion products.

    Energy Technology Data Exchange (ETDEWEB)

    Totemeier, T. C.

    1998-02-17

    The results of an initial characterization of hydride-containing corrosion products from uranium metal Zero Power Physics Reactor (ZPPR) fuel plates are presented. Sorption analyses using the BET method with a Kr adsorbate were performed to measure the specific areas of corrosion product samples. The specific surface areas of the corrosion products varied from 0.66 to 1.01 m{sup 2}/g. The reactivity of the products in Ar-9%O{sub 2} and Ar-20%O{sub 2} were measured at temperatures between 35 C and 150 C using a thermo-gravimetric analyzer. Ignition of the products occurred at temperatures of 150 C and above. The oxidation rates below ignition were comparable to rates observed for uranium metal.

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

    International Nuclear Information System (INIS)

    Miller, W.H.

    1989-08-01

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

  13. Surface area and chemical reactivity characteristics of uranium metal corrosion products

    International Nuclear Information System (INIS)

    Totemeier, T. C.

    1998-01-01

    The results of an initial characterization of hydride-containing corrosion products from uranium metal Zero Power Physics Reactor (ZPPR) fuel plates are presented. Sorption analyses using the BET method with a Kr adsorbate were performed to measure the specific areas of corrosion product samples. The specific surface areas of the corrosion products varied from 0.66 to 1.01 m 2 /g. The reactivity of the products in Ar-9%O 2 and Ar-20%O 2 were measured at temperatures between 35 C and 150 C using a thermo-gravimetric analyzer. Ignition of the products occurred at temperatures of 150 C and above. The oxidation rates below ignition were comparable to rates observed for uranium metal

  14. Chemical reactivity of hydrogen, nitrogen, and oxygen atoms at temperatures below 100 k

    Science.gov (United States)

    Mcgee, H. A., Jr.

    1973-01-01

    The synthesis of unusual compounds by techniques employing cryogenic cooling to retard their very extreme reactivity was investigated. Examples of such species that were studied are diimide (N2H2), cyclobutadiene (C4H4), cyclopropanone (C3H4O), oxirene (C2H2O), and many others. Special purpose cryogenically cooled inlet arrangements were designed such that the analyses incurred no warm-up of the cold, and frequently explosively unstable, compounds. Controlled energy electron impact techniques were used to measure critical potentials and to develop the molecular energetics and thermodynamics of these molecules and to gain some insight into their kinetic characteristics as well. Three and four carbon strained ring molecules were studied. Several reactions of oxygen and hydrogen atoms with simple molecules of H, N, C, and O in hard quench configurations were studied. And the quench stabilization of BH3 was explored as a model system in cryochemistry.

  15. Aggregate formation in a freshwater bacterial strain induced by growth state and conspecific chemical cues

    Czech Academy of Sciences Publication Activity Database

    Blom, J. F.; Horňák, Karel; Šimek, Karel; Pernthaler, J.

    2010-01-01

    Roč. 12, č. 9 (2010), s. 2486-2495 ISSN 1462-2912 R&D Projects: GA ČR(CZ) GA206/08/0015 Institutional research plan: CEZ:AV0Z60170517 Keywords : aggregate formation * Sphingobium sp. * chemical cues * growth state Subject RIV: EE - Microbiology, Virology Impact factor: 5.537, year: 2010

  16. Analytical model of chemical phase and formation of DSB in chromosomes by ionizing radiation

    Czech Academy of Sciences Publication Activity Database

    Barilla, J.; Lokajíček, Miloš; Pisaková, Hana; Šimr, P.

    2013-01-01

    Roč. 36, č. 1 (2013), s. 11-17 ISSN 0158-9938 Institutional support: RVO:68378271 Keywords : radiobiological mechanism * chemical phase * DSB formation * oxygen effect Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 0.848, year: 2013

  17. Galactic chemical evolution in hierarchical formation models - I. Early-type galaxies in the local Universe

    NARCIS (Netherlands)

    Arrigoni, Matías; Trager, Scott C.; Somerville, Rachel S.; Gibson, Brad K.

    We study the metallicities and abundance ratios of early-type galaxies in cosmological semi-analytic models (SAMs) within the hierarchical galaxy formation paradigm. To achieve this we implemented a detailed galactic chemical evolution model and can now predict abundances of individual elements for

  18. Galactic chemical evolution in hierarchical formation models : I. Early-type galaxies in the local Universe

    NARCIS (Netherlands)

    Arrigoni, Matias; Trager, Scott C.; Somerville, Rachel S.; Gibson, Brad K.

    2010-01-01

    We study the metallicities and abundance ratios of early-type galaxies in cosmological semi-analytic models (SAMs) within the hierarchical galaxy formation paradigm. To achieve this we implemented a detailed galactic chemical evolution model and can now predict abundances of individual elements for

  19. Attempts to identify a control system for chemical reactivity in the living state using virtual energy.

    Science.gov (United States)

    Reid, B L; Bourke, C

    2001-07-01

    This thesis explores the activation of chemicals in metabolic systems from the viewpoint that this activation is under the control of elements of the space-sea in which the chemicals are immersed. Themselves inert, the chemicals are theorised to exploit a force or action issuing from space (fluctuation) and characterized by the homogeneity (termed symmetry) of this medium. The fluctuation is heterogenized upon collision with matter from the intervention of well recognized fields of gravity and electromagnetism at the instant of its issue to form the near field of radiation. Fractions of original space waves and of their intrinsic spin are produced resulting in the activation of the orbitals (valency) in the chemical itself. The thesis continues: the disturbed fluctuation must return to space, obliging in turn, a prior return to the homogeneous state requiring special restorative wave rearrangements known as resonance. The success of the restorative resonance is signalled by a singularity of the fluctuation now propelled to infinity (space), and the contingent chemical reactions thereby terminated. Compromise to this return can occur from many causes and, in its presence, activation of the orbitals continues. They now effectively constitute autonomous reactions alienated from the system as a whole. The thesis is supported from evidence from diverse fields such as space theory, history of quantum field theory in attempts to derive its meaning, dielectrics and the near field of electromagnetic radiation, electron-space interactions at the Fermi surface during phase transitions and evolution of equilibrium conditions in resonance phenomena. The utility of the hypothesis rests on recognition of the resonance condition at various points in the system sufficiently macroscopic as to be available clinically as an abrupt interface between physiology and pathology. Copyright 2001 Harcourt Publishers Ltd.

  20. Role of Extracellular Polymeric Substances in the Surface Chemical Reactivity of Hymenobacter aerophilus, a Psychrotolerant Bacterium▿

    Science.gov (United States)

    Baker, M. G.; Lalonde, S. V.; Konhauser, K. O.; Foght, J. M.

    2010-01-01

    Bacterial surface layers, such as extracellular polymeric substances (EPS), are known to play an important role in metal sorption and biomineralization; however, there have been very few studies investigating how environmentally induced changes in EPS production affect the cell's surface chemistry and reactivity. Acid-base titrations, cadmium adsorption assays, and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the surface reactivities of Hymenobacter aerophilus cells with intact EPS (WC) or stripped of EPS (SC) and purified EPS alone. Linear programming modeling of titration data showed SC to possess functional groups corresponding to phosphoryl (pKa ∼6.5), phosphoryl/amine (pKa ∼7.9), and amine/hydroxyl (pKa ∼9.9). EPS and WC both possess carboxyl groups (pKa ∼5.1 to 5.8) in addition to phosphoryl and amine groups. FT-IR confirmed the presence of polysaccharides and protein in purified EPS that can account for the additional carboxyl groups. An increased ligand density was observed for WC relative to that for SC, leading to an increase in the amount of Cd adsorbed (0.53 to 1.73 mmol/liter per g [dry weight] and 0.53 to 0.59 mmol/liter per g [dry weight], respectively). Overall, the presence of EPS corresponds to an increase in the number and type of functional groups on the surface of H. aerophilus that is reflected by increased metal adsorption relative to that for EPS-free cells. PMID:19915039

  1. Role of extracellular polymeric substances in the surface chemical reactivity of Hymenobacter aerophilus, a psychrotolerant bacterium.

    Science.gov (United States)

    Baker, M G; Lalonde, S V; Konhauser, K O; Foght, J M

    2010-01-01

    Bacterial surface layers, such as extracellular polymeric substances (EPS), are known to play an important role in metal sorption and biomineralization; however, there have been very few studies investigating how environmentally induced changes in EPS production affect the cell's surface chemistry and reactivity. Acid-base titrations, cadmium adsorption assays, and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the surface reactivities of Hymenobacter aerophilus cells with intact EPS (WC) or stripped of EPS (SC) and purified EPS alone. Linear programming modeling of titration data showed SC to possess functional groups corresponding to phosphoryl (pKa approximately 6.5), phosphoryl/amine (pKa approximately 7.9), and amine/hydroxyl (pKa approximately 9.9). EPS and WC both possess carboxyl groups (pKa approximately 5.1 to 5.8) in addition to phosphoryl and amine groups. FT-IR confirmed the presence of polysaccharides and protein in purified EPS that can account for the additional carboxyl groups. An increased ligand density was observed for WC relative to that for SC, leading to an increase in the amount of Cd adsorbed (0.53 to 1.73 mmol/liter per g [dry weight] and 0.53 to 0.59 mmol/liter per g [dry weight], respectively). Overall, the presence of EPS corresponds to an increase in the number and type of functional groups on the surface of H. aerophilus that is reflected by increased metal adsorption relative to that for EPS-free cells.

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

    Science.gov (United States)

    Wang, XinJie; Wu, YanQing; Huang, FengLei

    2017-01-05

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

  3. Determination of Gibbs energies of formation in aqueous solution using chemical engineering tools.

    Science.gov (United States)

    Toure, Oumar; Dussap, Claude-Gilles

    2016-08-01

    Standard Gibbs energies of formation are of primary importance in the field of biothermodynamics. In the absence of any directly measured values, thermodynamic calculations are required to determine the missing data. For several biochemical species, this study shows that the knowledge of the standard Gibbs energy of formation of the pure compounds (in the gaseous, solid or liquid states) enables to determine the corresponding standard Gibbs energies of formation in aqueous solutions. To do so, using chemical engineering tools (thermodynamic tables and a model enabling to predict activity coefficients, solvation Gibbs energies and pKa data), it becomes possible to determine the partial chemical potential of neutral and charged components in real metabolic conditions, even in concentrated mixtures. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Double stratification effects in chemically reactive squeezed Sutterby fluid flow with thermal radiation and mixed convection

    Science.gov (United States)

    Ahmad, S.; Farooq, M.; Javed, M.; Anjum, Aisha

    2018-03-01

    A current analysis is carried out to study theoretically the mixed convection characteristics in squeezing flow of Sutterby fluid in squeezed channel. The constitutive equation of Sutterby model is utilized to characterize the rheology of squeezing phenomenon. Flow characteristics are explored with dual stratification. In flowing fluid which contains heat and mass transport, the first order chemical reaction and radiative heat flux affect the transport phenomenon. The systems of non-linear governing equations have been modulating which then solved by mean of convergent approach (Homotopy Analysis Method). The graphs are reported and illustrated for emerging parameters. Through graphical explanations, drag force, rate of heat and mass transport are conversed for different pertinent parameters. It is found that heat and mass transport rate decays with dominant double stratified parameters and chemical reaction parameter. The present two-dimensional examination is applicable in some of the engineering processes and industrial fluid mechanics.

  5. Quasi-equilibria and plasma chemical similarity in non-isothermal reactive plasmas

    International Nuclear Information System (INIS)

    Miethke, F.; Rutscher, A.; Wagner, H.E.

    2000-01-01

    With regard to the output of stable products the mode of operation of non-isothermal plasma chemical reactors shows physical and chemical well defined states, which represent limiting cases and may be interpreted as quasi-equilibrium states. The occurrence and the characteristics of these states, meanwhile more than once observed and described, are demonstrated by an instructive model reaction. Within the frame of the so-called Macroscopic Kinetics a central parameter is dominating the reactor operation. This result may be generalized and is linked up to the application of similarity principles for the reactor operation. After the general formulation of such principles, starting from the balance equations of particles and energy, a dimensionless similarity parameter is formulated, characterizing the composition of the effluent gas of the reactor. The applicability of this parameter is demonstrated by experimental examples. (Authors)

  6. Effects of chemical dispersants on oil-brine interfacial tension and droplet formation

    International Nuclear Information System (INIS)

    Khelifa, A.; So, L.L.C.

    2009-01-01

    The dispersion of oil spilled in water is influenced by chemical dispersants via the modification of the interfacial properties of the oil, such as oil-brine interfacial tension (IFT). In this study, the physical properties and dispersion of oil were measured in order to determine the effects of chemical dispersants on IFT and oil viscosity and the effects on oil droplet formation. In theory, the maximum size of oil droplet that forms under turbulent mixing increases with IFT. Therefore, a reduction in IFT reduces the size distribution of oil droplets. This paper presented the results of an ongoing project aimed at providing quantitative understanding the influence that chemical dispersants have on the size distribution of oil droplets and oil dispersion. Findings showed that a valid approach is to separate the direct effects of chemical dispersants on oil properties, specifically oil-brine IFT and the effects of mixing on dispersion of chemically treated oil. Under constant mixing conditions, the reduction of the maximum oil droplet size that overcomes the breakage process is determined by the effects of chemical dispersant on oil properties. This correlates well with the dispersant-to-oil ratio (DOR) up to the critical micelle concentration (CMC). This good agreement can be attributed to the reduction of IFT with DOR. It was concluded that the reduction of IFT with dispersant concentration is an additional signature of oil composition on droplet formation, while mixing energy is an external parameter that is independent of oil properties. 17 refs., 3 tabs., 9 figs

  7. Double stratification effects in chemically reactive squeezed Sutterby fluid flow with thermal radiation and mixed convection

    Directory of Open Access Journals (Sweden)

    S. Ahmad

    2018-03-01

    Full Text Available A current analysis is carried out to study theoretically the mixed convection characteristics in squeezing flow of Sutterby fluid in squeezed channel. The constitutive equation of Sutterby model is utilized to characterize the rheology of squeezing phenomenon. Flow characteristics are explored with dual stratification. In flowing fluid which contains heat and mass transport, the first order chemical reaction and radiative heat flux affect the transport phenomenon. The systems of non-linear governing equations have been modulating which then solved by mean of convergent approach (Homotopy Analysis Method. The graphs are reported and illustrated for emerging parameters. Through graphical explanations, drag force, rate of heat and mass transport are conversed for different pertinent parameters. It is found that heat and mass transport rate decays with dominant double stratified parameters and chemical reaction parameter. The present two-dimensional examination is applicable in some of the engineering processes and industrial fluid mechanics. Keywords: Squeezing flow, Sutterby fluid model, Mixed convection, Double stratification, Thermal radiation, Chemical reaction

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

    KAUST Repository

    Hu, Pan

    2016-03-11

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

  9. A Model to Couple Flow, Thermal and Reactive Chemical Transport, and Geo-mechanics in Variably Saturated Media

    Science.gov (United States)

    Yeh, G. T.; Tsai, C. H.

    2015-12-01

    This paper presents the development of a THMC (thermal-hydrology-mechanics-chemistry) process model in variably saturated media. The governing equations for variably saturated flow and reactive chemical transport are obtained based on the mass conservation principle of species transport supplemented with Darcy's law, constraint of species concentration, equation of states, and constitutive law of K-S-P (Conductivity-Degree of Saturation-Capillary Pressure). The thermal transport equation is obtained based on the conservation of energy. The geo-mechanic displacement is obtained based on the assumption of equilibrium. Conventionally, these equations have been implicitly coupled via the calculations of secondary variables based on primary variables. The mechanisms of coupling have not been obvious. In this paper, governing equations are explicitly coupled for all primary variables. The coupling is accomplished via the storage coefficients, transporting velocities, and conduction-dispersion-diffusion coefficient tensor; one set each for every primary variable. With this new system of equations, the coupling mechanisms become clear. Physical interpretations of every term in the coupled equations will be discussed. Examples will be employed to demonstrate the intuition and superiority of these explicit coupling approaches. Keywords: Variably Saturated Flow, Thermal Transport, Geo-mechanics, Reactive Transport.

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

    KAUST Repository

    Hu, Pan; Lee, Sangsu; Park, Kyu Hyung; Das, Soumyajit; Herng, Tun Seng; Goncalves, Theo; Huang, Kuo-Wei; Ding, Jun; Kim, Dongho; Wu, Jishan

    2016-01-01

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

  11. Prediction of the Chapman-Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics.

    Science.gov (United States)

    Guo, Dezhou; Zybin, Sergey V; An, Qi; Goddard, William A; Huang, Fenglei

    2016-01-21

    The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman-Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ state parameters, providing the means to predict the performance of new materials prior to synthesis and characterization, allowing the simulation based design to be done in silico. Our Rx2CJ method is based on atomistic reactive molecular dynamics (RMD) using the QM-derived ReaxFF force field. We validate this method here by predicting the CJ point and detonation products for three typical energetic materials. We find good agreement between the predicted and experimental detonation velocities, indicating that this method can reliably predict the CJ state using modest levels of computation.

  12. Practical use of chemical probes for reactive oxygen species produced in biological systems by {gamma}-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Hee; Moon, Yu Ran; Chung, Byung Yeoup; Kim, Jae-Sung [Radiation Research Division for Bio-technology, Korea Atomic Energy Research Institute, 1266 Sinjeong-dong, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Lee, Kang-Soo [Crop Production and Technology Major, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Cho, Jae-Young [Bio-environmental Science Major, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Kim, Jin-Hong [Radiation Research Division for Bio-technology, Korea Atomic Energy Research Institute, 1266 Sinjeong-dong, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of)], E-mail: jhongkim@kaeri.re.kr

    2009-05-15

    Application of chemical probes, for detection of reactive oxygen species (ROS), was tested during {gamma}-irradiation. The ethanol/{alpha}-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) and 3,3'-diaminobenzidine (DAB) were structurally stable enough to detect {sup {center_dot}}OH and H{sub 2}O{sub 2}, increasingly generated by {gamma}-irradiation up to 1000 Gy. Interestingly, the production rate of H{sub 2}O{sub 2}, but not {sup {center_dot}}OH, during {gamma}-irradiation, was significantly different between in vitro systems of lettuce and spinach. These results suggest that 4-POBN and DAB could be utilized as a semi-quantitative probe to quantify {sup {center_dot}}OH and H{sub 2}O{sub 2}, produced by {gamma}-irradiation up to 1000 Gy.

  13. Ozone Formation Induced by the Impact of Reactive Bromine and Iodine Species on Photochemistry in a Polluted Marine Environment.

    Science.gov (United States)

    Shechner, M; Tas, E

    2017-12-19

    Reactive iodine and bromine species (RIS and RBS, respectively) are known for altering atmospheric chemistry and causing sharp tropospheric ozone (O 3 ) depletion in polar regions and significant O 3 reduction in the marine boundary layer (MBL). Here we use measurement-based modeling to show that, unexpectedly, both RIS and RBS can lead to enhanced O 3 formation in a polluted marine environment under volatile organic compound (VOC)-limited conditions associated with high nitrogen oxide (NO X = [NO] + [NO 2 ]) concentrations. Under these conditions, the daily average O 3 mixing ratio increased to ∼44 and ∼28% for BrO and IO mixing ratios of up to ∼6.8 and 4.7 ppt, respectively. The increase in the level of O 3 was partially induced by enhanced ClNO 3 formation for higher Br 2 and I 2 emission flux. The increase in the level of O 3 was associated with an increased mixing ratio of hydroperoxyl radical to hydroxyl radical ([HO 2 ]/[OH]) and increased [NO 2 ]/[NO] with higher levels of RBS and/or RIS. NO X -rich conditions are typical of the polluted MBL, near coastlines and ship plumes. Considering that O 3 is toxic to humans, plants, and animals and is a greenhouse gas, our findings call for adequate updating of local and regional air-quality models with the effects of activities of RBS and RIS on O 3 mixing ratios in the polluted MBL.

  14. Key Role of Nitrate in Phase Transitions of Urban Particles: Implications of Important Reactive Surfaces for Secondary Aerosol Formation

    Science.gov (United States)

    Sun, Jiaxing; Liu, Lei; Xu, Liang; Wang, Yuanyuan; Wu, Zhijun; Hu, Min; Shi, Zongbo; Li, Yongjie; Zhang, Xiaoye; Chen, Jianmin; Li, Weijun

    2018-01-01

    Ammonium sulfate (AS) and ammonium nitrate (AN) are key components of urban fine particles. Both field and model studies showed that heterogeneous reactions of SO2, NO2, and NH3 on wet aerosols accelerated the haze formation in northern China. However, little is known on phase transitions of AS-AN containing haze particles. Here hygroscopic properties of laboratory-generated AS-AN particles and individual particles collected during haze events in an urban site were investigated using an individual particle hygroscopicity system. AS-AN particles showed a two-stage deliquescence at mutual deliquescence relative humidity (MDRH) and full deliquescence relative humidity (DRH) and three physical states: solid before MDRH, solid-aqueous between MDRH and DRH, and aqueous after DRH. During hydration, urban haze particles displayed a solid core and aqueous shell at RH = 60-80% and aqueous phase at RH > 80%. Most particles were in aqueous phase at RH > 50% during dehydration. Our results show that AS content in individual particles determines their DRH and AN content determines their MDRH. AN content increase can reduce MDRH, which indicates occurrence of aqueous shell at lower RH. The humidity-dependent phase transitions of nitrate-abundant urban particles are important to provide reactive surfaces of secondary aerosol formation in the polluted air.

  15. Streptococcus sanguinis induces foam cell formation and cell death of macrophages in association with production of reactive oxygen species.

    Science.gov (United States)

    Okahashi, Nobuo; Okinaga, Toshinori; Sakurai, Atsuo; Terao, Yutaka; Nakata, Masanobu; Nakashima, Keisuke; Shintani, Seikou; Kawabata, Shigetada; Ooshima, Takashi; Nishihara, Tatsuji

    2011-10-01

    Streptococcus sanguinis, a normal inhabitant of the human oral cavity, is a common streptococcal species implicated in infective endocarditis. Herein, we investigated the effects of infection with S. sanguinis on foam cell formation and cell death of macrophages. Infection with S. sanguinis stimulated foam cell formation of THP-1, a human macrophage cell line. At a multiplicity of infection >100, S. sanguinis-induced cell death of the macrophages. Viable bacterial infection was required to trigger cell death because heat-inactivated S. sanguinis did not induce cell death. The production of cytokines interleukin-1β and tumor necrosis factor-α from macrophages was also stimulated during bacterial infection. Inhibition of the production of reactive oxygen species (ROS) resulted in reduced cell death, suggesting an association of ROS with cell death. Furthermore, S. sanguinis-induced cell death appeared to be independent of activation of inflammasomes, because cleavage of procaspase-1 was not evident in infected macrophages. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  16. Production of chemically reactive radioactive ion beams through on-line separation

    International Nuclear Information System (INIS)

    Joinet, A.

    2003-10-01

    The ISOL (isotope separation on line) allows the production of secondary radioactive ion beams through spallation or fragmentation or fission reactions that take place in a thick target bombarded by a high intensity primary beam. The challenge is to increase the intensity and purity of the radioactive beam. The optimization of the system target/source requires the right choice of material for the target by taking into account the stability of the material, its reactivity and the ionization method used. The target is an essential part of the system because radioactive elements are generated in it and are released more or less quickly. Tests have been made in order to select the best fitted material for the release of S, Se, Te, Ge and Sn. Materials tested as target filling are: ZrO 2 , Nb, Ti, V,TiO 2 , CeO x , ThO 2 , C, ZrC 4 and VC). Other molecules such as: COSe, COS, SeS, COTe, GeS, SiS, SnS have been studied to ease the extraction of recoil nuclei (Se, S, Te, Ge and Sn) produced inside the target

  17. Core Flooding Experiments and Reactive Transport Modeling of Seasonal Heat Storage in the Hot Deep Gassum Sandstone Formation

    DEFF Research Database (Denmark)

    Holmslykke, Hanne D.; Kjøller, Claus; Fabricius, Ida Lykke

    2017-01-01

    Seasonal storage of excess heat in hot deep aquifers is considered to optimize the usage of commonly available energy sources. The chemical effects of heating the Gassum Sandstone Formation to up to 150 degrees C is investigated by combining laboratory core flooding experiments with petrographic ...... minor effects on the properties of the reservoir and that storage of excess heat in the Gassum Formation in the Stenlille area may be possible provided operational precautions are taken....... analysis and geochemical modeling. Synthetic formation water is injected into two sets of Gassum Formation samples at 25, 50 (reservoir temperature), 100, and 150 degrees C with a velocity of 0.05 and 0.1 PV/h, respectively. Results show a significant increase in the aqueous concentration of silicium...... and iron with increasing temperature due to dissolution of silica and siderite. Increasing the reservoir temperature from 50 to 100 degrees C enhanced the naturally occurring weathering of Na-rich feldspar to kaolinite. Dissolution of quartz increased sharply above 100 degrees C and was the dominating...

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

    Science.gov (United States)

    De Lucia, M.; Pilz, P.

    2014-12-01

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

  19. Flow of chemically reactive magneto Cross nanoliquid with temperature-dependent conductivity

    Science.gov (United States)

    Hayat, Tasawar; Ullah, Ikram; Waqas, Muhammad; Alsaedi, Ahmed

    2018-05-01

    Influence of temperature-dependent thermal conductivity on MHD flow of Cross nanoliquid bounded by a stretched sheet is explored. The combined feature of Brownian motion and thermophoresis in nanoliquid modeling is retained. In addition, the attributes of zero mass flux at sheet are imposed. First-order chemical reaction is retained. The resulting problems are numerically computed. Plots and tabulated values are presented and examined. It is figured out that larger thermophoretic diffusion and thermal conductivity significantly rise the thermal field, whereas opposite situation is seen for heat transfer rate.

  20. Tautomeric transformation of temozolomide, their proton affinities and chemical reactivities: A theoretical approach.

    Science.gov (United States)

    Sang-Aroon, Wichien; Ruangpornvisuti, Vithaya; Amornkitbamrung, Vittaya

    2016-05-01

    The gas-phase geometry optimizations of bare, mono- and dihydrated complexes of temozolomide isomers were carried out using density functional calculation at the M06-2X/6-31+G(d,p) level of the theory. The structures and protonation energies of protonated species of temozolomide are reported. Chemical indices of all isomers and protonated species are also reported. Energies, thermodynamic quantities, rate constants and equilibrium constants of tautomeric and rotameric transformations of all isomers I1↔TZM↔HIa↔HIb↔I2↔I3 in bare and hydrated systems were obtained. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Role of tip chemical reactivity on atom manipulation process in dynamic force microscopy

    Czech Academy of Sciences Publication Activity Database

    Sugimoto, Y.; Yurtsever, A.; Abe, M.; Morita, S.; Ondráček, Martin; Pou, P.; Perez, R.; Jelínek, Pavel

    2013-01-01

    Roč. 7, č. 8 (2013), s. 7370-7376 ISSN 1936-0851 R&D Projects: GA ČR(CZ) GPP204/11/P578 Grant - others:GA AV ČR(CZ) M100101207 Institutional support: RVO:68378271 Keywords : noncontact atomic force microscopy * atomic manipulation * force spectroscopy * chemical interaction force * DFT simulations * nudged elastic band Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 12.033, year: 2013 http://pubs.acs.org/doi/abs/10.1021/nn403097p

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

    International Nuclear Information System (INIS)

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

    1989-02-01

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

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

    Science.gov (United States)

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

    1989-02-01

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

  4. Intra-/inter-laboratory validation study on reactive oxygen species assay for chemical photosafety evaluation using two different solar simulators.

    Science.gov (United States)

    Onoue, Satomi; Hosoi, Kazuhiro; Toda, Tsuguto; Takagi, Hironori; Osaki, Naoto; Matsumoto, Yasuhiro; Kawakami, Satoru; Wakuri, Shinobu; Iwase, Yumiko; Yamamoto, Toshinobu; Nakamura, Kazuichi; Ohno, Yasuo; Kojima, Hajime

    2014-06-01

    A previous multi-center validation study demonstrated high transferability and reliability of reactive oxygen species (ROS) assay for photosafety evaluation. The present validation study was undertaken to verify further the applicability of different solar simulators and assay performance. In 7 participating laboratories, 2 standards and 42 coded chemicals, including 23 phototoxins and 19 non-phototoxic drugs/chemicals, were assessed by the ROS assay using two different solar simulators (Atlas Suntest CPS series, 3 labs; and Seric SXL-2500V2, 4 labs). Irradiation conditions could be optimized using quinine and sulisobenzone as positive and negative standards to offer consistent assay outcomes. In both solar simulators, the intra- and inter-day precisions (coefficient of variation; CV) for quinine were found to be below 10%. The inter-laboratory CV for quinine averaged 15.4% (Atlas Suntest CPS) and 13.2% (Seric SXL-2500V2) for singlet oxygen and 17.0% (Atlas Suntest CPS) and 7.1% (Seric SXL-2500V2) for superoxide, suggesting high inter-laboratory reproducibility even though different solar simulators were employed for the ROS assay. In the ROS assay on 42 coded chemicals, some chemicals (ca. 19-29%) were unevaluable because of limited solubility and spectral interference. Although several false positives appeared with positive predictivity of ca. 76-92% (Atlas Suntest CPS) and ca. 75-84% (Seric SXL-2500V2), there were no false negative predictions in both solar simulators. A multi-center validation study on the ROS assay demonstrated satisfactory transferability, accuracy, precision, and predictivity, as well as the availability of other solar simulators. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Predicting soil formation on the basis of transport-limited chemical weathering

    Science.gov (United States)

    Yu, Fang; Hunt, Allen Gerhard

    2018-01-01

    Soil production is closely related to chemical weathering. It has been shown that, under the assumption that chemical weathering is limited by solute transport, the process of soil production is predictable. However, solute transport in soil cannot be described by Gaussian transport. In this paper, we propose an approach based on percolation theory describing non-Gaussian transport of solute to predict soil formation (the net production of soil) by considering both soil production from chemical weathering and removal of soil from erosion. Our prediction shows agreement with observed soil depths in the field. Theoretical soil formation rates are also compared with published rates predicted using soil age-profile thickness (SAST) method. Our formulation can be incorporated directly into landscape evolution models on a point-to-point basis as long as such models account for surface water routing associated with overland flow. Further, our treatment can be scaled-up to address complications associated with continental-scale applications, including those from climate change, such as changes in vegetation, or surface flow organization. The ability to predict soil formation rates has implications for understanding Earth's climate system on account of the relationship to chemical weathering of silicate minerals with the associated drawdown of atmospheric carbon, but it is also important in geomorphology for understanding landscape evolution, including for example, the shapes of hillslopes, and the net transport of sediments to sedimentary basins.

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

    Science.gov (United States)

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

    2017-12-01

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

  7. Chemical-Reaction-Controlled Phase Separated Drops: Formation, Size Selection, and Coarsening

    Science.gov (United States)

    Wurtz, Jean David; Lee, Chiu Fan

    2018-02-01

    Phase separation under nonequilibrium conditions is exploited by biological cells to organize their cytoplasm but remains poorly understood as a physical phenomenon. Here, we study a ternary fluid model in which phase-separating molecules can be converted into soluble molecules, and vice versa, via chemical reactions. We elucidate using analytical and simulation methods how drop size, formation, and coarsening can be controlled by the chemical reaction rates, and categorize the qualitative behavior of the system into distinct regimes. Ostwald ripening arrest occurs above critical reaction rates, demonstrating that this transition belongs entirely to the nonequilibrium regime. Our model is a minimal representation of the cell cytoplasm.

  8. Chemical of shales belonging to Castellanos and Migues formations (Cretaceous), Santa Lucia basin - Uruguay: Paleoenvironment considerations

    International Nuclear Information System (INIS)

    Peel, E.; Veloslavsky, G.; Fulfaro, J.

    1998-01-01

    In the present work there are analyzed 16 samples of shales belonging to Castellanos and Migues formations (Cretaceous), taken from cores of various boreholes of the Santa Lucia Basin (Uruguay). Chemical analysis of major elements, trace elements (B,V, Sr, Rb, Cr y Ga) and X- ray diffractometry were done to them in order to obtain a geochemical characterization. The characterization shows that their chemical composition is comparable to the world average composition of shales. Besides, the X-ray diffractometry. Based on that, it is clear to deduce that it existed a change in the environment conditions having a shift from a redactor environment which agrees with former micropaleontologic studies. (author)

  9. Modeling of reactive chemical transport of leachates from a utility fly-ash disposal site

    International Nuclear Information System (INIS)

    Apps, J.A.; Zhu, M.; Kitanidis, P.K.; Freyberg, D.L.; Ronan, A.D.; Itakagi, S.

    1991-04-01

    Fly ash from fossil-fuel power plants is commonly slurried and pumped to disposal sites. The utility industry is interested in finding out whether any hazardous constituents might leach from the accumulated fly ash and contaminate ground and surface waters. To evaluate the significance of this problem, a representative site was selected for modeling. FASTCHEM, a computer code developed for the Electric Power Research Institute, was utilized for the simulation of the transport and fate of the fly-ash leachate. The chemical evolution of the leachate was modeled as it migrated along streamtubes defined by the flow model. The modeling predicts that most of the leachate seeps through the dam confining the ash pond. With the exception of ferrous, manganous, sulfate and small amounts of nickel ions, all other dissolved constituents are predicted to discharge at environmentally acceptable concentrations

  10. Coupling Chemical Kinetics and Flashes in Reactive, Thermal and Compositional Reservoir Simulation

    DEFF Research Database (Denmark)

    Kristensen, Morten Rode; Gerritsen, Margot G.; Thomsen, Per Grove

    2007-01-01

    of convergence and error test failures by more than 50% compared to direct integration without the new algorithm. To facilitate the algorithmic development we construct a virtual kinetic cell model. We use implicit one-step ESDIRK (Explicit Singly Diagonal Implicit Runge-Kutta) methods for integration...... of the kinetics. The kinetic cell model serves both as a tool for the development and testing of tailored solvers as well as a testbed for studying the interactions between chemical kinetics and phase behavior. A comparison between a Kvalue correlation based approach and a more rigorous equation of state based......Phase changes are known to cause convergence problems for integration of stiff kinetics in thermal and compositional reservoir simulations. We propose an algorithm for detection and location of phase changes based on discrete event system theory. The algorithm provides a robust way for handling...

  11. Response of the ionosphere to the injection of chemically reactive vapors

    International Nuclear Information System (INIS)

    Bernhardt, P.A.

    1976-05-01

    As a gas released in the ionosphere expands, it is rapidly cooled. When the vapor becomes sufficiently tenuous, it is reheated by collisions with the ambient atmosphere, and its flow is then governed by diffusive expansion. As the injected gas becomes well mixed with the plasma, a hole is created by chemical processes. In the case of diatomic hydrogen release, depression of the electron concentrations is governed by the charge exchange reaction between oxygen ions and hydrogen, producing positive hydroxyl ions. Hydroxyl ions rapidly react with the electron gas to produce excited oxygen and hydrogen atoms. Enhanced airglow emissions result from the transition of the excited atoms to lower energy states. The electron temperature in the depleted region rises sharply and this rise causes a thermal expansion of the plasma and a further reduction in the local plasma concentration

  12. Formation of reactive aldehydes (MDA, HHE, HNE) during the digestion of cod liver oil: comparison of human and porcine in vitro digestion models.

    Science.gov (United States)

    Tullberg, Cecilia; Larsson, Karin; Carlsson, Nils-Gunnar; Comi, Irene; Scheers, Nathalie; Vegarud, Gerd; Undeland, Ingrid

    2016-03-01

    In this work, we investigated lipid oxidation of cod liver oil during gastrointestinal (GI) digestion using two types of in vitro digestion models. In the first type of model, we used human GI juices, while we used digestive enzymes and bile from porcine origin in the second type of model. Human and porcine models were matched with respect to factors important for lipolysis, using a standardized digestion protocol. The digests were analysed for reactive oxidation products: malondialdehyde (MDA), 4-hydroxy-trans-2-nonenal (HNE), and 4-hydroxy-trans-2-hexenal (HHE) by liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (LC/APCI-MS), and for free fatty acids (FFA) obtained during the digestion by gas chromatography-mass spectrometry (GC-MS). The formation of the oxidation products MDA, HHE, and HNE was low during the gastric digestion, however, it increased during the duodenal digestion. The formation of the oxidation products reached higher levels when digestive juices of human origin were used (60 μM of MDA, 0.96 μM of HHE, and 1.6 μM of HNE) compared to when using enzymes and bile of porcine origin (9.8, and 0.36 μM of MDA; 0.16, and 0.026 μM of HHE; 0.23, and 0.005 μM of HNE, respectively, in porcine models I and II). In all models, FFA release was only detected during the intestinal step, and reached up to 31% of total fatty acids (FA). The findings in this work may be of importance when designing oxidation oriented lipid digestion studies.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-01-01

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

  14. Critical Reflections on the Hydrophobic Effect, its Origins and Manifestation: Water Structure, Chemical Reactivity, Micelles and Gels.

    Directory of Open Access Journals (Sweden)

    Sosale Chandrasekhar

    2017-09-01

    Full Text Available The origins of the Hydrophobic Effect (HE, its biological significance and its experimental basis are critically addressed in this brief review. It is argued that the mechanistic work reported on the HE in recent decades needs to be reassessed, as its conclusions are apparently debatable. Essentially, it is highly inaccurate to view the HE as a repulsive interaction, which is rather an attractive one. It appears inevitable that the HE is indeed a manifestation of the perturbation of the structure of water upon the introduction of hydrocarbon molecules into its interior. There appears to be no other satisfactory explanation for the formation of micellar aggregates and the existence of the critical micelle concentration. Also, the practical significance of the HE on the reactivity of organic compounds (e.g. cycloadditions is severely limited by their minuscule solubility levels, itself a manifestation of the HE! Other related phenomena apparently include the formation of gels and the occurrence of certain esterification reactions in water, which are briefly reviewed from a conceptual viewpoint.

  15. Physico-chemical changes of the ground waters related to the 2011 El Hierro magmatic reactivation

    Science.gov (United States)

    Dionis, S.; Melián, G.; Padrón, E.; Padilla, G.; Nolasco, D.; Rodríguez, F.; Hernández, I.; Peraza, D.; Barrancos, J.; Hernández, P.; Calvo, D.; Pérez, N.

    2012-04-01

    The island of El Hierro (278 Km2), is the smallest, the southwesternmost and the youngest island (˜1.12 My) of the Canarian archipelago. The main geological characteristics of El Hierro consist on the presence of three convergent ridges of volcanic cones on a truncated trihedron shape and giant landslides between the three rift zones, being the most recent El Golfo on the northwest flank of the island. On July 2011 an anomalous seismic activity at Hierro Island started and suggested the initial stage of a volcanic unrest in the volcanic system. On October 10, after the occurrence of more than 10,000 earthquakes, a submarine eruption started. Evidences of this submarine volcanic eruption were visible on the sea surface to the south of La Restinga village, at the south of the island, in the form of large light-green coloured area, turbulent gas emission and the appearance of steamy volcanic fragments three days later. As part of its volcanic surveillance activities, the Instituto Volcanologico de Canarias (INVOLCAN) started a hydrogeochemical monitoring program on August 2011 in order to evaluate the temporal evolution of several physico-chemical parameters of the ground water system of El Hierro. Four observation sites were selected: three wells on the north of the island, where the seismic activity was located at the beginning of the volcano-seismic unrest (SIMO, FRON and PADO) and one horizontal well (gallery) in the south (TACO). Ground water sampling is being regularly collected, three times per week, at each observation site, and in-situ measurements of pH, conductivity and temperature measurements are performed. After 6 month of monitoring, no significant changes have been observed on pH and temperature measurements from all the observation sites. However, clear sharp decrease of conductivity was observed at SIMO on October 10 when the seismic tremor started. In addition, the strongest conductivity decrease pattern was observed later on at SIMO and PADO on

  16. Effect of in situ hypothermic perfusion on intrahepatic pO(2) and reactive oxygen species formation after partial hepatectomy under total hepatic vascular exclusion in pigs

    NARCIS (Netherlands)

    Heijnen, Bob H. M.; Straatsburg, Irene H.; Kager, Liesbeth M.; van der Kleij, Ad J.; Gouma, Dirk J.; van Gulik, Thomas M.

    2003-01-01

    Aim: This study examined attenuation of ischemia and reperfusion (I/R) induced liver injury during liver resections by hypothermic perfusion of the liver under total hepatic vascular exclusion (THVE). Method: Reactive oxygen species (ROS) formation, microcirculatory integrity and endothelial cell

  17. Vibrational deactivation on chemically reactive potential surfaces: An exact quantum study of a low barrier collinear model of H + FH, D + FD, H + FD and D + FH

    International Nuclear Information System (INIS)

    Schatz, G.C.; Kuppermann, A.

    1980-01-01

    We study vibrational deactivation processes on chemically reactive potential energy surfaces by examining accurate quantum mechanical transition probabilities and rate constants for the collinear H + FH(v), D + FD(v), H + FD(v), and D + FH(v) reactions. A low barrier (1.7 kcal/mole) potential surface is used in these calculations, and we find that for all four reactions, the reactive inelastic rate constants are larger than the nonreactive ones for the same initial and final vibrational states. However, the ratios of these reactive and nonreactive rate constants depend strongly on the vibrational quantum number v and the isotopic composition of the reagents. Nonreactive and reactive transition probabilities for multiquantum jump transitions are generally comparable to those for single quantum transitions. This vibrationally nonadiabatic behavior is a direct consequence of the severe distortion of the diatomic that occurs in a collision on a low barrier reactive surface, and can make chemically reactive atoms like H or D more efficient deactivators of HF or DF than nonreactive collision partners. Many conclusions are in at least qualitative agreement with those of Wilkin's three dimensional quasiclassical trajectory study on the same systems using a similar surface. We also present results for H + HF(v) collisions which show that for a higher barrier potential surface (33 rather than 1.7 kcal/mole), the deactivation process becomes similar in character to that for nonreactive partners, with v→v-1 processes dominating

  18. Using Star Clusters as Tracers of Star Formation and Chemical Evolution: The Chemical Enrichment History of the Large Magellanic Cloud

    Science.gov (United States)

    Chilingarian, Igor V.; Asa’d, Randa

    2018-05-01

    The star formation (SFH) and chemical enrichment (CEH) histories of Local Group galaxies are traditionally studied by analyzing their resolved stellar populations in a form of color–magnitude diagrams obtained with the Hubble Space Telescope. Star clusters can be studied in integrated light using ground-based telescopes to much larger distances. They represent snapshots of the chemical evolution of their host galaxy at different ages. Here we present a simple theoretical framework for the chemical evolution based on the instantaneous recycling approximation (IRA) model. We infer a CEH from an SFH and vice versa using observational data. We also present a more advanced model for the evolution of individual chemical elements that takes into account the contribution of supernovae type Ia. We demonstrate that ages, iron, and α-element abundances of 15 star clusters derived from the fitting of their integrated optical spectra reliably trace the CEH of the Large Magellanic Cloud obtained from resolved stellar populations in the age range 40 Myr age–metallicity relation. Moreover, the present-day total gas mass of the LMC estimated by the IRA model (6.2× {10}8 {M}ȯ ) matches within uncertainties the observed H I mass corrected for the presence of molecular gas (5.8+/- 0.5× {10}8 {M}ȯ ). We briefly discuss how our approach can be used to study SFHs of galaxies as distant as 10 Mpc at the level of detail that is currently available only in a handful of nearby Milky Way satellites. .

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

    Science.gov (United States)

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

    2017-12-01

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

  20. Chemical reactivity of precursor materials during synthesis of glasses used for conditioning high-level radioactive waste: Experiments and models

    International Nuclear Information System (INIS)

    Monteiro, A.

    2012-01-01

    The glass used to store high-level radioactive waste is produced by reaction of a solid waste residue and a glassy precursor (glass frit). The waste residue is first dried and calcined (to lose water and nitrogen respectively), then mixed with the glass frit to enable vitrification at high temperature. In order to obtain a good quality glass of constant composition upon cooling, the chemical reactions between the solid precursors must be complete while in the liquid state, to enable incorporation of the radioactive elements into the glassy matrix. The physical and chemical conditions during glass synthesis (e.g. temperature, relative proportions of frit and calcine, amount of radioactive charge) are typically empirically adjusted to obtain a satisfactory final product. The aim of this work is to provide new insights into the chemical and physical interactions that take place during vitrification and to provide data for a mathematical model that has been developed to simulate the chemical reactions. The consequences of the different chemical reactions that involve solid, liquid and gaseous phases are described (thermal effects, changes in crystal morphology and composition, variations in melt properties and structure). In a first series of experiments, a simplified analogue of the calcine (NaNO 3 -Al 2 O 3 ± MoO 3 /Nd 2 O 3 ) has been studied. In a second series of experiments, the simplified calcines have been reacted with a simplified glass frit (SiO 2 -Na 2 O-B 2 O 3 -Al 2 O 3 ) at high temperature. The results show that crystallization of the calcine may take place before interaction with the glass frit, but that the reactivity with the glass at high temperature is a function of the nature and stoichiometry of the crystalline phases which form at low temperature. The results also highlight how the mixing of the starting materials, the physical properties of the frit (viscosity, glass transition temperature) and the Na 2 O/Al 2 O 3 of the calcine but also its

  1. Hydroxylated polychlorinated biphenyls increase reactive oxygen species formation and induce cell death in cultured cerebellar granule cells

    International Nuclear Information System (INIS)

    Dreiem, Anne; Rykken, Sidsel; Lehmler, Hans-Joachim; Robertson, Larry W.; Fonnum, Frode

    2009-01-01

    Polychlorinated biphenyls (PCBs) are persistent organic pollutants that bioaccumulate in the body, however, they can be metabolized to more water-soluble products. Although they are more readily excreted than the parent compounds, some of the metabolites are still hydrophobic and may be more available to target tissues, such as the brain. They can also cross the placenta and reach a developing foetus. Much less is known about the toxicity of PCB metabolites than about the parent compounds. In the present study, we have investigated the effects of eight hydroxylated (OH) PCB congeners (2'-OH PCB 3, 4-OH PCB 14, 4-OH PCB 34, 4'-OH PCB 35, 4-OH PCB 36, 4'-OH PCB 36, 4-OH PCB 39, and 4'-OH PCB 68) on reactive oxygen species (ROS) formation and cell viability in rat cerebellar granule cells. We found that, similar to their parent compounds, OH-PCBs are potent ROS inducers with potency 4-OH PCB 14 < 4-OH PCB 36 < 4-OH PCB 34 < 4'-OH PCB 36 < 4'-OH PCB 68 < 4-OH PCB 39 < 4'-OH PCB 35. 4-OH PCB 36 was the most potent cell death inducer, and caused apoptotic or necrotic morphology depending on concentration. Inhibition of ERK1/2 kinase with U0126 reduced both cell death and ROS formation, suggesting that ERK1/2 activation is involved in OH-PCB toxicity. The results indicate that the hydroxylation of PCBs may not constitute a detoxification reaction. Since OH-PCBs like their parent compounds are retained in the body and may be more widely distributed to sensitive tissues, it is important that not only the levels of the parent compounds but also the levels of their metabolites are taken into account during risk assessment of PCBs and related compounds.

  2. Systematic Search for Chemical Reactions in Gas Phase Contributing to Methanol Formation in Interstellar Space.

    Science.gov (United States)

    Gamez-Garcia, Victoria G; Galano, Annia

    2017-10-05

    A massive search for chemical routes leading to methanol formation in gas phase has been conducted using computational chemistry, at the CBS-QB3 level of theory. The calculations were performed at five different temperatures (100, 80, 50, 20, and 10 K) and at three pressures (0.1, 0.01, and 0.001 atm) for each temperature. The search was focused on identifying reactions with the necessary features to be viable in the interstellar medium (ISM). A searching strategy was applied to that purpose, which allowed to reduce an initial set of 678 possible reactions to a subset of 11 chemical routes that are recommended, for the first time, as potential candidates for contributing to methanol formation in the gas phase of the ISM. They are all barrier-less, and thus they are expected to take place at collision rates. Hopefully, including these reactions in the currently available models, for the gas-phase methanol formation in the ISM, would help improving the predicted fractional abundance of this molecule in dark clouds. Further investigations, especially those dealing with grain chemistry and electronic excited states, would be crucial to get a complete picture of the methanol formation in the ISM.

  3. Preventive effect of chemical peeling on ultraviolet induced skin tumor formation.

    Science.gov (United States)

    Abdel-Daim, Mohamed; Funasaka, Yoko; Kamo, Tsuneyoshi; Ooe, Masahiko; Matsunaka, Hiroshi; Yanagita, Emmy; Itoh, Tomoo; Nishigori, Chikako

    2010-10-01

    Chemical peeling is one of the dermatological treatments available for certain cutaneous diseases and conditions or improvement of cosmetic appearance of photoaged skin. We assessed the photochemopreventive effect of several clinically used chemical peeling agents on the ultraviolet (UV)-irradiated skin of hairless mice. Chemical peeling was done using 35% glycolic acid dissolved in distilled water, 30% salicylic acid in ethanol, 10% or 35% trichloroacetic acid (TCA) in distilled water at the right back of UV-irradiated hairless mice every 2 weeks in case of glycolic acid, salicylic acid, and 10% TCA and every 4 weeks in case of 35% TCA for totally 18 weeks after the establishment of photoaged mice by irradiation with UVA+B range light three times a week for 10 weeks at a total dose of 420 J/cm(2) at UVA and 9.6 J/cm(2) at UVB. Tumor formation was assessed every week. Skin specimens were taken from treated and non-treated area for evaluation under microscopy, evaluation of P53 expression, and mRNA expression of cyclooxygenase (COX)-2. Serum level of prostaglandin E(2) was also evaluated. All types of chemical peeling reduced tumor formation in treated mice, mostly in the treated area but also non-treated area. Peeling suppressed clonal retention of p53 positive abnormal cells and reduced mRNA expression of COX-2 in treated skin. Further, serum prostaglandin E(2) level was decreased in chemical peeling treated mice. These results indicate that chemical peeling with glycolic acid, salicylic acid, and TCA could serve tumor prevention by removing photodamaged cells. Copyright © 2010 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

  4. Structural, optical and electrical properties of reactively sputtered CrxNy films: Nitrogen influence on the phase formation

    Directory of Open Access Journals (Sweden)

    Mirjana Novaković

    2017-03-01

    Full Text Available The properties of various CrxNy films grown by direct current (DC reactive sputtering process with different values of nitrogen partial pressures (0, 2×10-4, 3.5×10-4 and 5×10-4 mbar were studied. The structural analysis of the samples was performed by using X-ray diffraction and transmission electron microscopy (TEM, while an elemental analysis was realized by means of Rutherford backscattering spectrometry. By varying nitrogen partial pressure the pure Cr layer, mixture of Cr, Cr2N and CrN phases, or single-phase CrN was produced. TEM analysis showed that at pN2 = 2×10-4 mbar the layer has dense microstructure. On the other hand, the layer deposited at the highest nitrogen partial pressure exhibits pronounced columnar structure. The optical properties of CrxNy films were evaluated from spectroscopic ellipsometry data by the Drude or combined Drude and Tauc-Lorentz model. It was found that both refractive index and extinction coefficient are strongly dependent on the dominant phase formation (Cr, Cr2N, CrN during the deposition process. Finally, the electrical studies indicated the metallic character of Cr2N phase and semiconducting behaviour of CrN.

  5. Technical Note: Reactivity of C1 and C2 organohalogens formation – from plant litter to bacteria

    Directory of Open Access Journals (Sweden)

    J. J. Wang

    2012-10-01

    Full Text Available C1/C2 organohalogens (organohalogens with one or two carbon atoms can have significant environmental toxicity and ecological impact, such as carcinogenesis, ozone depletion and global warming. Natural halogenation processes have been identified for a wide range of natural organic matter, including soils, plant and animal debris, algae, and fungi. Yet, few have considered these organohalogens generated from the ubiquitous bacteria, one of the largest biomass pools on earth. Here, we report and confirm the formation of chloroform (CHCl3 dichloro-acetonitrile (CHCl2CN, chloral hydrate (CCl3CH(OH2 and their brominated analogues by direct halogenation of seven strains of common bacteria and nine cellular monomers. Comparing different major C stocks during litter decomposition stages in terrestrial ecosystems, from plant litter, decomposed litter, to bacteria, we found increasing reactivity for nitrogenous organohalogen yield with decreasing C/N ratio. Our results raise the possibility that natural halogenation of bacteria represents a significant and overlooked contribution to global organohalogen burdens. As bacteria are decomposers that alter the C quality by transforming organic matter pools from high to low C/N ratio and constitute a large organic N pool, the bacterial activity is expected to affect the C, N, and halogen cycling through natural halogenation reactions.

  6. Reactivity of polyester aliphatic amine surfactants as corrosion inhibitors for carbon steel in formation water (deep well water)

    International Nuclear Information System (INIS)

    Alsabagh, A.M.; Migahed, M.A.; Awad, Hayam S.

    2006-01-01

    Effect of different concentrations, 40-200 ppm, of various polyester aliphatic amine surfactants on inhibition of the corrosion of carbon steel in the formation water (deep well water) was investigated. These surfactants exhibit different levels of inhibition particularly at high concentration (200 ppm). Inhibition efficiencies in the range 86-96% were determined by weight loss method. Comparable results were obtained from electrochemical measurements using Tafel extrapolation and polarisation resistance methods. It was shown that all the investigated surfactants act primarily as anodic inhibitors; however, they also affect the rate and mechanism of the cathodic reaction. These compounds function via adsorption on reactive sites on the corroding surface reducing the corrosion rate of the metal. It was revealed that the adsorption of these surfactants obey Langmuir adsorption isotherm. The inhibition effectiveness increases with the length of the aliphatic hydrocarbon chain, being a maximum in the presence of surfactant IV (∼96% efficiency). The corrosion inhibition feature of this compound is attributed to the presence of a long hydrocarbon chain that ensures large surface coverage as well as the presence of multiple active centers for adsorption. Scanning electron microscopy, SEM, has been applied to identify the surface morphology of carbon steel alloy in the absence and presence of the inhibitor molecules

  7. Reactivity of polyester aliphatic amine surfactants as corrosion inhibitors for carbon steel in formation water (deep well water)

    Energy Technology Data Exchange (ETDEWEB)

    Alsabagh, A.M. [Department of Petroleum Applications, Egyptian Petroleum Research Institute (EPRI), Ahmed El-Zomor Street 1, Nasr City, Cairo 11727 (Egypt); Migahed, M.A. [Department of Petroleum Applications, Egyptian Petroleum Research Institute (EPRI), Ahmed El-Zomor Street 1, Nasr City, Cairo 11727 (Egypt)]. E-mail: mohamedatiyya707@hotmail.com; Awad, Hayam S. [Chemistry Department, Faculty of Girls for Science, Art and Education, Ain Shams University, Asmaa Fahmi Street, Helliopolis, Cairo (Egypt)

    2006-04-15

    Effect of different concentrations, 40-200 ppm, of various polyester aliphatic amine surfactants on inhibition of the corrosion of carbon steel in the formation water (deep well water) was investigated. These surfactants exhibit different levels of inhibition particularly at high concentration (200 ppm). Inhibition efficiencies in the range 86-96% were determined by weight loss method. Comparable results were obtained from electrochemical measurements using Tafel extrapolation and polarisation resistance methods. It was shown that all the investigated surfactants act primarily as anodic inhibitors; however, they also affect the rate and mechanism of the cathodic reaction. These compounds function via adsorption on reactive sites on the corroding surface reducing the corrosion rate of the metal. It was revealed that the adsorption of these surfactants obey Langmuir adsorption isotherm. The inhibition effectiveness increases with the length of the aliphatic hydrocarbon chain, being a maximum in the presence of surfactant IV ({approx}96% efficiency). The corrosion inhibition feature of this compound is attributed to the presence of a long hydrocarbon chain that ensures large surface coverage as well as the presence of multiple active centers for adsorption. Scanning electron microscopy, SEM, has been applied to identify the surface morphology of carbon steel alloy in the absence and presence of the inhibitor molecules.

  8. Formation of Reactive Intermediates, Color, and Antioxidant Activity in the Maillard Reaction of Maltose in Comparison to d-Glucose.

    Science.gov (United States)

    Kanzler, Clemens; Schestkowa, Helena; Haase, Paul T; Kroh, Lothar W

    2017-10-11

    In this study, the Maillard reaction of maltose and d-glucose in the presence of l-alanine was investigated in aqueous solution at 130 °C and pH 5. The reactivity of both carbohydrates was compared in regards of their degradation, browning, and antioxidant activity. In order to identify relevant differences in the reaction pathways, the concentrations of selected intermediates such as 1,2-dicarbonyl compounds, furans, furanones, and pyranones were determined. It was found, that the degradation of maltose predominantly yields 1,2-dicarbonyls that still carry a glucosyl moiety and thus subsequent reactions to HMF, furfural, and 2-acetylfuran are favored due to the elimination of d-glucose, which is an excellent leaving group in aqueous solution. Consequently, higher amounts of these heterocycles are formed from maltose. 3-deoxyglucosone and 3-deoxygalactosone represent the only relevant C 6 -1,2-dicarbonyls in maltose incubations and are produced in nearly equimolar amounts during the first 60 min of heating as byproducts of the HMF formation.

  9. Influence of the physicochemical and aromatic properties on the chemical reactivity and its relation with carcinogenic and anticoagulant effect of 17β-aminoestrogens

    Energy Technology Data Exchange (ETDEWEB)

    Soriano-Correa, Catalina, E-mail: socc@puma2.zaragoza.unam.mx [Química Computacional, FES-Zaragoza, Universidad Nacional Autónoma de México (UNAM), Iztapalapa, Mexico City (Mexico); Raya, Angélica [Unidad Profesional Interdisciplinaria de Ingeniería Campus Guanajuato, Instituto Politécnico Nacional (IPN), Silao de la Victoria, Guanajuato (Mexico); Barrientos-Salcedo, Carolina [Laboratorio de Química Médica y Quimiogenómica, Facultad de Bioanálisis Campus Veracruz - Boca del Río, Universidad Veracruzana, Veracruz (Mexico); Esquivel, Rodolfo O. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa (UAM-Iztapalapa), Mexico City (Mexico)

    2014-06-25

    Highlights: • The aromatic A-ring of 17β-aminoestrogens contribute to its anticoagulant effect. • The electron-donor substituent groups favored the basicity of 17β-aminoestrogens. • The physicochemical properties are important in the carcinogenic effect of anticoagulant molecules. - Abstract: Activity of steroid hormones is dependent upon a number of factors, as solubility, transport and metabolism. The functional differences caused by structural modifications could exert an influence on the chemical reactivity and biological effect. The goal of this work is to study the influence of the physicochemical and aromatic properties on the chemical reactivity and its relation with the carcinogenic risk that can associate with the anticoagulant effect of 17β-aminoestrogens using quantum-chemical descriptors at the DFT-B3LYP, BH and HLYP and M06-2X levels. The relative acidity of (H1) of the hydroxyl group increases with electron-withdrawing groups. Electron-donor groups favor the basicity. The steric hindrance of the substituents decreases the aromatic character and consequently diminution the carcinogenic effect. Density descriptors: hardness, electrophilic index, atomic charges, molecular orbitals, electrostatic potential and their geometric parameters permit analyses of the chemical reactivity and physicochemical features and to identify some reactive sites of 17β-aminoestrogens.

  10. Synthesis, characterisation and chemical reactivity of some new binuclear dioxouranium(VI) complexes derived from organic diazo compounds (Preprint No. CT-33)

    International Nuclear Information System (INIS)

    Pujar, M.A.; Pirgonde, B.R.

    1988-02-01

    A new series of binuclear dioxouranium(VI) complexes of polydentatate diazo compounds have been synthesised and characterised adequately by analysis, physio-chemical techniques and reactivity of these complexes. The location of bonding site of ligands, stability of complexes and status of U-O bond and probable structures of these complexes have been discussed. (author). 10 refs

  11. Fuels and chemicals from equine-waste-derived tail gas reactive pyrolysis oil: technoeconomic analysis, environmental and exergetic life cycle assessment

    Science.gov (United States)

    Horse manure, whose improper disposal imposes considerable environmental costs, constitutes an apt feedstock for conversion to renewable fuels and chemicals when tail gas reactive pyrolysis (TGRP) is employed. TGRP is a modification of fast pyrolysis that recycles its non-condensable gases and produ...

  12. THE STAR FORMATION HISTORY AND CHEMICAL EVOLUTION OF STAR-FORMING GALAXIES IN THE NEARBY UNIVERSE

    International Nuclear Information System (INIS)

    Torres-Papaqui, J. P.; Coziol, R.; Ortega-Minakata, R. A.; Neri-Larios, D. M.

    2012-01-01

    We have determined the metallicity (O/H) and nitrogen abundance (N/O) of a sample of 122,751 star-forming galaxies (SFGs) from the Data Release 7 of the Sloan Digital Sky Survey. For all these galaxies we have also determined their morphology and obtained a comprehensive picture of their star formation history (SFH) using the spectral synthesis code STARLIGHT. The comparison of the chemical abundance with the SFH allows us to describe the chemical evolution of the SFGs in the nearby universe (z ≤ 0.25) in a manner consistent with the formation of their stellar populations and morphologies. A high fraction (45%) of the SFGs in our sample show an excess abundance of nitrogen relative to their metallicity. We also find this excess to be accompanied by a deficiency of oxygen, which suggests that this could be the result of effective starburst winds. However, we find no difference in the mode of star formation of the nitrogen-rich and nitrogen-poor SFGs. Our analysis suggests that they all form their stars through a succession of bursts of star formation extended over a period of few Gyr. What produces the chemical differences between these galaxies seems therefore to be the intensity of the bursts: the galaxies with an excess of nitrogen are those that are presently experiencing more intense bursts or have experienced more intense bursts in their past. We also find evidence relating the chemical evolution process to the formation of the galaxies: the galaxies with an excess of nitrogen are more massive, and have more massive bulges and earlier morphologies than those showing no excess. Contrary to expectation, we find no evidence that the starburst wind efficiency decreases with the mass of the galaxies. As a possible explanation we propose that the loss of metals consistent with starburst winds took place during the formation of the galaxies, when their potential wells were still building up, and consequently were weaker than today, making starburst winds more

  13. FORMATION RATES OF POPULATION III STARS AND CHEMICAL ENRICHMENT OF HALOS DURING THE REIONIZATION ERA

    International Nuclear Information System (INIS)

    Trenti, Michele; Stiavelli, Massimo

    2009-01-01

    The first stars in the universe formed out of pristine primordial gas clouds that were radiatively cooled to a few hundreds of degrees kelvin either via molecular or atomic (Lyman-α) hydrogen lines. This primordial mode of star formation was eventually quenched once radiative and/or chemical (metal enrichment) feedbacks marked the transition to Population II stars. In this paper, we present a model for the formation rate of Population III stars based on Press-Schechter modeling coupled with analytical recipes for gas cooling and radiative feedback. Our model also includes a novel treatment for metal pollution based on self-enrichment due to a previous episode of Population III star formation in progenitor halos. With this model, we derive the star formation history of Population III stars, their contribution to the reionization of the universe and the time of the transition from Population III star formation in minihalos (M ∼ 10 6 M sun , cooled via molecular hydrogen) to that in more massive halos (M ∼> 2 x 10 7 M sun , where atomic hydrogen cooling is also possible). We consider a grid of models highlighting the impact of varying the values for the free parameters used, such as star formation and feedback efficiency. The most critical factor is the assumption that only one Population III star is formed in a halo. In this scenario, metal-free stars contribute only to a minor fraction of the total number of photons required to reionize the universe. In addition, metal-free star formation is primarily located in minihalos, and chemically enriched halos become the dominant locus of star formation very early in the life of the universe-at redshift z ∼ 25-even assuming a modest fraction (0.5%) of enriched gas converted in stars. If instead multiple metal-free stars are allowed to form out of a single halo, then there is an overall boost of Population III star formation, with a consequent significant contribution to the reionizing radiation budget. In addition

  14. STAR FORMATION HISTORY AND CHEMICAL EVOLUTION OF THE SEXTANS DWARF SPHEROIDAL GALAXY

    International Nuclear Information System (INIS)

    Lee, Myung Gyoon; Yuk, In-Soo; Park, Hong Soo; Harris, Jason; Zaritsky, Dennis

    2009-01-01

    We present the star formation history (SFH) and chemical evolution of the Sextans dSph galaxy as a function of a galactocentric distance. We derive these from the VI photometry of stars in the 42' x 28' field using the SMART model developed by Yuk and Lee and adopting a closed-box model for chemical evolution. For the adopted age of Sextans 15 Gyr, we find that >84% of the stars formed prior to 11 Gyr ago, significant star formation extends from 15 to 11 Gyr ago (∼ 65% of the stars formed 13-15 Gyr ago, while ∼ 25% formed 11-13 Gyr ago), detectable star formation continued to at least 8 Gyr ago, the SFH is more extended in the central regions than the outskirts, and the difference in star formation rates between the central and outer regions is most marked 11-13 Gyr ago. Whether blue straggler stars are interpreted as intermediate-age main-sequence stars affects conclusions regarding the SFH for times 4-8 Gyr ago, but this is at most only a trace population. We find that the metallicity of the stars increased rapidly up to [Fe/H] = -1.6 in the central region and to [Fe/H] = -1.8 in the outer region within the first Gyr, and has varied slowly since then. The abundance ratios of several elements derived in this study are in good agreement with the observational data based on the high-resolution spectroscopy in the literature. We conclude that the primary driver for the radial gradient of the stellar population in this galaxy is the SFH, which self-consistently drives the chemical enrichment history.

  15. Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites

    International Nuclear Information System (INIS)

    Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

    2013-01-01

    In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called “interphase” between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC–TiC) n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC–TiC) n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

  16. Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites

    Science.gov (United States)

    Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

    2013-06-01

    In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called "interphase" between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC-TiC)n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC-TiC)n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

  17. Quantitative comparison between in vivo DNA adduct formation from exposure to selected DNA-reactive carcinogens, natural background levels of DNA adduct formation and tumour incidende in rodent bioassays

    NARCIS (Netherlands)

    Paini, A.; Scholz, G.; Marin-Kuan, M.; Schilter, B.; O'Brien, J.; Bladeren, van P.J.; Rietjens, I.

    2011-01-01

    This study aimed at quantitatively comparing the occurrence/formation of DNA adducts with the carcinogenicity induced by a selection of DNA-reactive genotoxic carcinogens. Contrary to previous efforts, we used a very uniform set of data, limited to in vivo rat liver studies in order to investigate

  18. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  19. Chemical reactivities of the superconducting oxides, YBa2Cu3Oy and BiSrCaCu2Oy

    International Nuclear Information System (INIS)

    Toyama, Hisashi; Mizuno, Noritaka; Misono, Makoto

    1989-01-01

    The chemical reactivities of YBa 2 Cu 3 O y and BiSrCaCu 2 O y with various gases have been studied. It was found that large quantities of NO, CO, and NO 2 were rapidly absorbed (or intercalated) in the bulk of YBa 2 Cu 3 O y (T c : 90 K) at 573 K. The amount absorbed was in the order NO ∼ CO ∼ NO 2 > O 2 ∼ CO 2 > N 2 O ∼ 0. The amount for NO was more than two times the amount of YBa 2 Cu 3 O y in molar ratio and elongation by about 0.2 angstrom along c-axis was observed. NO absorbed was almost completely recovered as NO by the evacuation at 773 K. This absorption-desorption cycle proceeded reversively. The electronic resistivity at 573 K of YBa 2 Cu 3 O y increased upon the NO absorption and was restored by the evacuation at 773 K. CO was also absorbed rapidly accompanied by evolution of CO 2 . BiSrCaCu 2 O y did not absorb either NO or CO

  20. Influence of crystal defects on the chemical reactivity of recoil atoms in oxygen-containing chromium compounds

    International Nuclear Information System (INIS)

    Costea, T.

    1969-01-01

    The influence of crystal defects on the chemical reactivity of recoil atoms produced by the reaction 50 Cr (n,γ) 51 Cr in oxygen-containing chromium compounds has been studied. Three methods have been used to introduce the defects: doping (K 2 CrO 4 doped with BaCrO 4 ), irradiation by ionizing radiation (K 2 CrO 4 irradiated in the presence of Li 2 CO 3 ) and non-stoichiometry (the semi-conducting oxides of the CrO 3 -Cr 2 O 3 series). The thermal annealing kinetics of the irradiated samples have been determined, and the activation energy has been calculated. In all cases it has been observed that there is a decrease in the activation energy for thermal annealing in the presence of the defects. In order to explain the annealing process, an electronic mechanism has been proposed based on the interaction between the recoil species and the charge-carriers (holes or electrons). (author) [fr

  1. Entropy and chemical change. 1: Characterization of product (and reactant) energy distributions in reactive molecular collisions: Information and enthropy deficiency

    Science.gov (United States)

    Bernstein, R. B.; Levine, R. D.

    1972-01-01

    Optimal means of characterizing the distribution of product energy states resulting from reactive collisions of molecules with restricted distributions of initial states are considered, along with those for characterizing the particular reactant state distribution which yields a given set of product states at a specified total energy. It is suggested to represent the energy-dependence of global-type results in the form of square-faced bar plots, and of data for specific-type experiments as triangular-faced prismatic plots. The essential parameters defining the internal state distribution are isolated, and the information content of such a distribution is put on a quantitative basis. The relationship between the information content, the surprisal, and the entropy of the continuous distribution is established. The concept of an entropy deficiency, which characterizes the specificity of product state formation, is suggested as a useful measure of the deviance from statistical behavior. The degradation of information by experimental averaging is considered, leading to bounds on the entropy deficiency.

  2. Reactivity of the parent amido complexes of iridium with olefins: C-NH2 bond formation versus C-H activation.

    Science.gov (United States)

    Mena, Inmaculada; García-Orduña, Pilar; Polo, Víctor; Lahoz, Fernando J; Casado, Miguel A; Oro, Luis A

    2017-08-29

    Herein we report on the different chemical reactivity displayed by two mononuclear terminal amido compounds depending on the nature of the coordinated diene. Hence, treatment of amido-bridged iridium complexes [{Ir(μ-NH 2 )(tfbb)} 3 ] (1; tfbb = tetrafluorobenzobarrelene) with dppp (dppp = bis(diphenylphosphane)propane) leads to the rupture of the amido bridges forming the mononuclear terminal amido compound [Ir(NH 2 )(dppp)(tfbb)] (3) in the first stage. On changing the reaction conditions, the formation of a C-NH 2 bond between the amido moiety and the coordinated diene is observed and a new dinuclear complex [{Ir(1,2-η 2 -4-κ-C 12 H 8 F 4 N)(dppp)} 2 (μ-dppp)] (4) has been isolated. On the contrary, the diiridium amido-bridged complex [{Ir(μ-NH 2 )(cod)} 2 ] (2; cod = 1,5-cyclooctadiene) in the presence of dppb (dppb = bis(diphenylphosphane)butane) allows the isolation of a mononuclear complex [Ir(1,2,3-η 3 -6-κ-C 8 H 10 )H(dppb)] (5), as a consequence of the extrusion of ammonia. The monitoring of the reaction of 2 with dppb (and dppp) allowed us to detect terminal amido complexes [Ir(NH 2 )(P-P)(cod)] (P-P = dppb (6), dppp (7)) in solution, as confirmed by an X-ray analysis of 7. Complex 7 was observed to evolve into hydrido species 5 at room temperature. DFT studies showed that C-H bond activation occurs through the deprotonation of one methylene fragment of the cod ligand by the highly basic terminal amido moiety instead of C-H oxidative addition to the Ir(i) center.

  3. Tidal and Seasonal River Stage Fluctuations Impact the Formation of Permeable Natural Reactive Barriers in Riverbank Sediments

    Science.gov (United States)

    Shuai, P.; Myers, K.; Knappett, P.; Cardenas, M. B.

    2017-12-01

    River stage fluctuations, induced by ocean tides and rainfall, enhance the exchange between oxic river water and reducing groundwater. When mixing occurs within riverbank aquifers high in dissolved iron (Fe) and arsenic (As), the timing and extent of mixing likely control the accumulation and mobility of arsenic (As) within the hyporheic zone. Here we analyzed the impact of tidal and seasonal water level fluctuations on the formation of a Permeable Natural Reactive Barrier (PNRB) within an aquifer adjacent to the Meghna River, Bangladesh and its impact on As mobility. We found that the periodicity and amplitude of river stage fluctuations strongly control the spatial and temporal distribution of the PNRB, comprised of rapidly precipitated iron oxides, in this riverbank along a relatively straight reach of the Meghna River. The PNRB forms much faster and with higher concentration of Fe-oxide under semi-diurnal (12 hr) tidal fluctuations compared to simulations run assuming only neap-spring tides (14 day). As tidal amplitude increases, a larger contact area between oxic river water and reducing groundwater results which in turn leads to the horizontal expansion of the PNRB into the riverbank. Seasonal fluctuations expand the PNRB up to 60 m horizontally and 5 m vertically. In contrast neap-spring tidal fluctuations result in a smaller PNRB that is 10 and 3 m in the horizontal and vertical dimensions. The predicted changes in the spatial distribution of iron oxides within the riverbank would trap and release As at different times of the year. The PNRB could act as a secondary source of As to drinking water aquifers under sustained groundwater pumping scenarios near the river.

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

    Directory of Open Access Journals (Sweden)

    Luis Humberto Mendoza-Huizar

    2015-01-01

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

  5. Acetoin catabolism and acetylbutanediol formation by Bacillus pumilus in a chemically defined medium.

    Directory of Open Access Journals (Sweden)

    Zijun Xiao

    Full Text Available BACKGROUND: Most low molecular diols are highly water-soluble, hygroscopic, and reactive with many organic compounds. In the past decades, microbial research to produce diols, e.g. 1,3-propanediol and 2,3-butanediol, were considerably expanded due to their versatile usages especially in polymer synthesis and as possible alternatives to fossil based feedstocks from the bioconversion of renewable natural resources. This study aimed to provide a new way for bacterial production of an acetylated diol, i.e. acetylbutanediol (ABD, 3,4-dihydroxy-3-methylpentan-2-one, by acetoin metabolism. METHODOLOGY/PRINCIPAL FINDINGS: When Bacillus pumilus ATCC 14884 was aerobically cultured in a chemically defined medium with acetoin as the sole carbon and energy source, ABD was produced and identified by gas chromatography--chemical ionization mass spectrometry and NMR spectroscopy. CONCLUSIONS/SIGNIFICANCE: Although the key enzyme leading to ABD from acetoin has not been identified yet at this stage, this study proposed a new metabolic pathawy to produce ABD in vivo from using renewable resources--in this case acetoin, which could be reproduced from glucose in this study--making it the first facility in the world to prepare this new bio-based diol product.

  6. Chemical Kinetics for Bridging Molecular Mechanisms and Macroscopic Measurements of Amyloid Fibril Formation.

    Science.gov (United States)

    Michaels, Thomas C T; Šarić, Anđela; Habchi, Johnny; Chia, Sean; Meisl, Georg; Vendruscolo, Michele; Dobson, Christopher M; Knowles, Tuomas P J

    2018-04-20

    Understanding how normally soluble peptides and proteins aggregate to form amyloid fibrils is central to many areas of modern biomolecular science, ranging from the development of functional biomaterials to the design of rational therapeutic strategies against increasingly prevalent medical conditions such as Alzheimer's and Parkinson's diseases. As such, there is a great need to develop models to mechanistically describe how amyloid fibrils are formed from precursor peptides and proteins. Here we review and discuss how ideas and concepts from chemical reaction kinetics can help to achieve this objective. In particular, we show how a combination of theory, experiments, and computer simulations, based on chemical kinetics, provides a general formalism for uncovering, at the molecular level, the mechanistic steps that underlie the phenomenon of amyloid fibril formation.

  7. Calcium phosphate formation from sea urchin - (brissus latecarinatus via modified mechano-chemical (ultrasonic conversion method

    Directory of Open Access Journals (Sweden)

    R. Samur

    2013-07-01

    Full Text Available This study aims to produce apatite structures, such as hydroxyapatite (HA and fluorapatite (FA, from precursor calcium phosphates of biological origin, namely from sea urchin, with mechano-chemical stirring and hot-plating conversion method. The produced materials were heat treated at 800 °C for 4 hours. X-ray diffraction and scanning electron microscopy (SEM studies were conducted. Calcium phosphate phases were developed. The SEM images showed the formation of micro to nano-powders. The experimental results suggest that sea urchin, Brissus latecarinatus skeleton could be an alternative source for the production of various mono or biphasic calcium phosphates with simple and economic mechano-chemical (ultrasonic conversion method.

  8. Chemical Kinetics for Bridging Molecular Mechanisms and Macroscopic Measurements of Amyloid Fibril Formation

    Science.gov (United States)

    Michaels, Thomas C. T.; Šarić, Anđela; Habchi, Johnny; Chia, Sean; Meisl, Georg; Vendruscolo, Michele; Dobson, Christopher M.; Knowles, Tuomas P. J.

    2018-04-01

    Understanding how normally soluble peptides and proteins aggregate to form amyloid fibrils is central to many areas of modern biomolecular science, ranging from the development of functional biomaterials to the design of rational therapeutic strategies against increasingly prevalent medical conditions such as Alzheimer's and Parkinson's diseases. As such, there is a great need to develop models to mechanistically describe how amyloid fibrils are formed from precursor peptides and proteins. Here we review and discuss how ideas and concepts from chemical reaction kinetics can help to achieve this objective. In particular, we show how a combination of theory, experiments, and computer simulations, based on chemical kinetics, provides a general formalism for uncovering, at the molecular level, the mechanistic steps that underlie the phenomenon of amyloid fibril formation.

  9. Pronuclear formation by ICSI using chemically activated ovine oocytes and zona pellucida bound sperm

    Directory of Open Access Journals (Sweden)

    J. E. Hernández-Pichardo

    2016-11-01

    Full Text Available Abstract Background In order to improve ICSI, appropiate sperm selection and oocyte activation is necessary. The objective of the present study was to determine the efficiency of fertilization using ICSI with chemically activated ovine oocytes and sperm selected by swim up (SU or swim up + zona pellucida (SU + ZP binding. Results Experiment 1, 4–20 replicates with total 821 in vitro matured oocytes were chemically activated with ethanol, calcium ionophore or ionomycin, to determine oocyte activation (precense of one PN. Treatments showed similar results (54, 47, 42 %, respectively but statistically differents (P  0.05. Conclusions Chemical activation induces higher ovine oocyte activation than mechanical activation. Ethanol slightly displays higher oocyte activation than calcium ionophore and ionomicine. Sperm selection with SU + ZP increased AR/A and AR/D rates in comparison with SU in fresh and frozen-thawed sperm. According to this, in terms of fertilization rates, chemical activation after ICSI increased oocyte PN formation compared to mechanical activation. Also, fresh sperm treated with SU and SU + ZP were significantly different than frozen-thawed sperm, but between sperm treatments no significant differences were obtained.

  10. Chemical Kinetic Study of Nitrogen Oxides Formation Trends in Biodiesel Combustion

    Directory of Open Access Journals (Sweden)

    Junfeng Yang

    2012-01-01

    Full Text Available The use of biodiesel in conventional diesel engines results in increased NOx emissions; this presents a barrier to the widespread use of biodiesel. The origins of this phenomenon were investigated using the chemical kinetics simulation tool: CHEMKIN-2 and the CFD KIVA3V code, which was modified to account for the physical properties of biodiesel and to incorporate semidetailed mechanisms for its combustion and the formation of emissions. Parametric ϕ-T maps and 3D engine simulations were used to assess the impact of using oxygen-containing fuels on the rate of NO formation. It was found that using oxygen-containing fuels allows more O2 molecules to present in the engine cylinder during the combustion of biodiesel, and this may be the cause of the observed increase in NO emissions.

  11. Quantitative NMR Approach to Optimize the Formation of Chemical Building Blocks from Abundant Carbohydrates.

    Science.gov (United States)

    Elliot, Samuel G; Tolborg, Søren; Sádaba, Irantzu; Taarning, Esben; Meier, Sebastian

    2017-07-21

    The future role of biomass-derived chemicals relies on the formation of diverse functional monomers in high yields from carbohydrates. Recently, it has become clear that a series of α-hydroxy acids, esters, and lactones can be formed from carbohydrates in alcohol and water solvents using tin-containing catalysts such as Sn-Beta. These compounds are potential building blocks for polyesters bearing additional olefin and alcohol functionalities. An NMR approach was used to identify, quantify, and optimize the formation of these building blocks in the Sn-Beta-catalyzed transformation of abundant carbohydrates. Record yields of the target molecules can be achieved by obstructing competing reactions through solvent selection. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. A theoretical quantum chemical study of alanine formation in interstellar medium

    Science.gov (United States)

    Shivani; Pandey, Parmanad; Misra, Alka; Tandon, Poonam

    2017-08-01

    The interstellar medium, the vast space between the stars, is a rich reservoir of molecular material ranging from simple diatomic molecules to more complex, astrobiologically important molecules such as amino acids, nucleobases, and other organic species. Radical-radical and radical-neutral interaction schemes are very important for the formation of comparatively complex molecules in low temperature chemistry. An attempt has been made to explore the possibility of formation of complex organic molecules in interstellar medium, through detected interstellar molecules like CH3CN and HCOOH. The gas phase reactions are theoretically studied using quantum chemical techniques. We used the density functional theory (DFT) at the B3LYP/6-311G( d, p) level. The reaction energies, potential barrier and optimized structures of all the geometries, involved in the reaction path, has been discussed. We report the potential energy surfaces for the reactions considered in this work.

  13. The effect of biologically and chemically synthesized silver nanoparticles (AgNPs) on biofilm formation

    Science.gov (United States)

    Chojniak, Joanna; Biedroń, Izabela; Mendrek, Barbara; Płaza, Grażyna

    2017-11-01

    Bionanotechnology has emerged up as integration between biotechnology and nanotechnology for developing biosynthetic and environmental-friendly technology for synthesis of nanomaterials. Different types of nanomaterials like copper, zinc, titanium, magnesium, gold, and silver have applied in the various industries but silver nanoparticles have proved to be most effective against bacteria, viruses and eukaryotic microorganisms. The antimicrobial property of silver nanoparticles are widely known. Due to strong antibacterial property silver nanoparticles are used, e.g. in clothing, food industry, sunscreens, cosmetics and many household and environmental appliances. The aim of the study was to compare the effect of silver nanoparticles (AgNPs) synthesized biologically and chemically on the biofilm formation. The biofilm was formed by the bacteria isolated from the water supply network. The commonly used crystal violet assay (CV) was applied for biofilm analysis. In this study effect of biologically synthesized Ag-NPs on the biofilm formation was evaluated.

  14. Chemical Evolution and the Formation of Dwarf Galaxies in the Early Universe

    Science.gov (United States)

    Cote, Benoit; JINA-CEE, NuGrid, ChETEC

    2018-06-01

    Stellar abundances in local dwarf galaxies offer a unique window into the nature and nucleosynthesis of the first stars. They also contain clues regarding how galaxies formed and assembled in the early stages of the universe. In this talk, I will present our effort to connect nuclear astrophysics with the field of galaxy formation in order to define what can be learned about galaxy evolution using stellar abundances. In particular, I will describe the current state of our numerical chemical evolution pipeline which accounts for the mass assembly history of galaxies, present how we use high-redshift cosmological hydrodynamic simulations to calibrate our models and to learn about the formation of dwarf galaxies, and address the challenge of identifying the dominant r-process site(s) using stellar abundances.

  15. Chemical stability and defect formation in CaHfO3

    KAUST Repository

    Alay-E-Abbas, Syed Muhammad

    2014-04-01

    Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

  16. Chemical stability and defect formation in CaHfO3

    KAUST Repository

    Alay-E-Abbas, Syed Muhammad; Nazir, Safdar; Mun Wong, Kin; Shaukat, Ali; Schwingenschlö gl, Udo

    2014-01-01

    Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

  17. Improving the chemical compatibility of sealing glass for solid oxide fuel cells: Blocking the reactive species by controlled crystallization

    Science.gov (United States)

    Zhang, Teng; Zou, Qi; Zeng, Fanrong; Wang, Shaorong; Tang, Dian; Yang, Hiswen

    2012-10-01

    The chemical compatibility of sealing glass is of great importance for Solid oxide fuel cell (SOFC). In this work, the interfacial reaction between sealing glass and Cr-containing interconnect alloy is characterized by reacting Cr2O3 powders with a representative SrO-containing glass crystallized by different heat-treatment schedules. The crystalline structure and crystalline content of sealing glass are determined by X-ray diffraction. The results show that the fraction of Cr6+ decreases from 39.8 ± 1.9% for quenched glass to 8.2 ± 0.4% for glass crystallized at 900 °C for 2 h. In addition, the interfacial reaction can be further reduced with increasing crystallization temperature and time as well as the addition of nucleation agent (TiO2). The formation of some Sr-containing crystalline phases, Sr2SiO4 and Sr(TiO3), contributes to the improvement of chemical compatibility of sealing glass, in agreement with the results of thermodynamic calculations.

  18. Percutaneous Biopsy and Radiofrequency Ablation of Osteoid Osteoma with Excess Reactive New Bone Formation and Cortical Thickening Using a Battery-Powered Drill for Access: A Technical Note

    Energy Technology Data Exchange (ETDEWEB)

    Filippiadis, D., E-mail: dfilippiadis@yahoo.gr; Gkizas, C., E-mail: chgkizas@gmail.com; Kostantos, C., E-mail: drkarpen@yahoo.gr; Mazioti, A., E-mail: argyromazioti@yahoo.gr; Reppas, L., E-mail: l.reppas@yahoo.com; Brountzos, E., E-mail: ebrountz@med.uoa.gr; Kelekis, N., E-mail: kelnik@med.uoa.gr; Kelekis, A., E-mail: akelekis@med.uoa.gr [University General Hospital “ATTIKON”, 2nd Radiology Department (Greece)

    2016-10-15

    PurposeTo report our experience with the use of a battery-powered drill in biopsy and radiofrequency ablation of osteoid osteoma with excess reactive new bone formation. The battery-powered drill enables obtaining the sample while drilling.Materials and MethodsDuring the last 18 months, 14 patients suffering from painful osteoid osteoma with excess reactive new bone formation underwent CT-guided biopsy and radiofrequency ablation. In order to assess and sample the nidus of the osteoid osteoma, a battery-powered drill was used. Biopsy was performed in all cases. Then, coaxially, a radiofrequency electrode was inserted and ablation was performed with osteoid osteoma protocol. Procedure time (i.e., drilling including local anesthesia), amount of scans, technical and clinical success, and the results of biopsy are reported.ResultsAccess to the nidus through the excess reactive new bone formation was feasible in all cases. Median procedure time was 50.5 min. Histologic verification of osteoid osteoma was performed in all cases. Radiofrequency electrode was coaxially inserted within the nidus and ablation was successfully performed in all lesions. Median amount CT scans, performed to control correct positioning of the drill and precise electrode placement within the nidus was 11. There were no complications or material failure reported in our study.ConclusionsThe use of battery-powered drill facilitates access to the osteoid osteoma nidus in cases where excess reactive new bone formation is present. Biopsy needle can be used for channel creation during the access offering at the same time the possibility to extract bone samples.

  19. Cross talk between increased intracellular zinc (Zn2+) and accumulation of reactive oxygen species in chemical ischemia.

    Science.gov (United States)

    Slepchenko, Kira G; Lu, Qiping; Li, Yang V

    2017-10-01

    Both zinc (Zn 2+ ) and reactive oxygen species (ROS) have been shown to accumulate during hypoxic-ischemic stress and play important roles in pathological processes. To understand the cross talk between the two of them, here we studied Zn 2+ and ROS accumulation by employing fluorescent probes in HeLa cells to further the understanding of the cause and effect relationship of these two important cellular signaling systems during chemical-ischemia, stimulated by oxygen and glucose deprivation (OGD). We observed two Zn 2+ rises that were divided into four phases in the course of 30 min of OGD. The first Zn 2+ rise was a transient, which was followed by a latent phase during which Zn 2+ levels recovered; however, levels remained above a basal level in most cells. The final phase was the second Zn 2+ rise, which reached a sustained plateau called Zn 2+ overload. Zn 2+ rises were not observed when Zn 2+ was removed by TPEN (a Zn 2+ chelator) or thapsigargin (depleting Zn 2+ from intracellular stores) treatment, indicating that Zn 2+ was from intracellular storage. Damaging mitochondria with FCCP significantly reduced the second Zn 2+ rise, indicating that the mitochondrial Zn 2+ accumulation contributes to Zn 2+ overload. We also detected two OGD-induced ROS rises. Two Zn 2+ rises preceded two ROS rises. Removal of Zn 2+ reduced or delayed OGD- and FCCP-induced ROS generation, indicating that Zn 2+ contributes to mitochondrial ROS generation. There was a Zn 2+ -induced increase in the functional component of NADPH oxidase, p47 phox , thus suggesting that NADPH oxidase may mediate Zn 2+ -induced ROS accumulation. We suggest a new mechanism of cross talk between Zn 2+ and mitochondrial ROS through positive feedback processes that eventually causes excessive free Zn 2+ and ROS accumulations during the course of ischemic stress. Copyright © 2017 the American Physiological Society.

  20. Electrochemical formation of InP porous nanostructures and its application to amperometric chemical sensors

    International Nuclear Information System (INIS)

    Sato, Taketomo; Mizohata, Akinori; Fujino, Toshiyuki; Hashizume, Tamotsu

    2008-01-01

    In this paper, we report the electrochemical formation of the InP porous nanostructures and their feasibility for the application to the amperometric chemical sensors. Our two step electrochemical process consists of the pore formation on a (001) n-type InP substrate and the subsequent etching of pore walls caused by changing the polarity of the InP electrode in a HCl-based electrolyte. By applying the anodic bias to the InP electrode, the high-density array of uniform nanopores was formed on the surface. Next, the cathodic bias was applied to the porous sample to reduce the wall thickness by cathodic decomposition of InP, where the thickness of InP nanowall decreased uniformly along the entire depth of the porous layer. From the amperometric measurements of the porous electrode, it was found that the electrocatalytic activity was much higher than that of the planar electrode. Furthermore, the current sensitivity for the H 2 O 2 detection was much enhanced after the cathodic decomposition process. The InP porous nanostructure formed by the present process is one of the promising structures for the application to the semiconductor-based bio/chemical sensors. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. A coupling alternative to reactive transport simulations for long-term prediction of chemical reactions in heterogeneous CO2 storage systems

    Directory of Open Access Journals (Sweden)

    M. De Lucia

    2015-02-01

    Full Text Available Fully coupled, multi-phase reactive transport simulations of CO2 storage systems can be approximated by a simplified one-way coupling of hydrodynamics and reactive chemistry. The main characteristics of such systems, and hypotheses underlying the proposed alternative coupling, are (i that the presence of CO2 is the only driving force for chemical reactions and (ii that its migration in the reservoir is only marginally affected by immobilisation due to chemical reactions. In the simplified coupling, the exposure time to CO2 of each element of the hydrodynamic grid is estimated by non-reactive simulations and the reaction path of one single batch geochemical model is applied to each grid element during its exposure time. In heterogeneous settings, analytical scaling relationships provide the dependency of velocity and amount of reactions to porosity and gas saturation. The analysis of TOUGHREACT fully coupled reactive transport simulations of CO2 injection in saline aquifer, inspired to the Ketzin pilot site (Germany, both in homogeneous and heterogeneous settings, confirms that the reaction paths predicted by fully coupled simulations in every element of the grid show a high degree of self-similarity. A threshold value for the minimum concentration of dissolved CO2 considered chemically active is shown to mitigate the effects of the discrepancy between dissolved CO2 migration in non-reactive and fully coupled simulations. In real life, the optimal threshold value is unknown and has to be estimated, e.g. by means of 1-D or 2-D simulations, resulting in an uncertainty ultimately due to the process de-coupling. However, such uncertainty is more than acceptable given that the alternative coupling enables using grids of the order of millions of elements, profiting from much better description of heterogeneous reservoirs at a fraction of the calculation time of fully coupled models.

  2. Studies on photofading and stable free radical formation in reactive dyed cellulosic systems under their exposure to light

    International Nuclear Information System (INIS)

    Remi, E.; Horvath, O.; Vig, A.; Aranyosi, P.; Rusznak, I.

    1996-01-01

    In light exposed systems of cotton and C.I. Reactive Red 3, C.I. Reactive Black 5 and C.I. Direct Blue 78 azo dyes respectively, generated stable free radicals could be detected. The observed hyperfine splitting of ESR spectra suggest the free radical are formed in the chromophore. Based upon the calculated g-values the location of the generated unpaired electron could be assumed on one of the C atoms of the dye molecule. (author)

  3. Chemical evolution of formation waters in the Palm Valley gas field, Northern Territory

    International Nuclear Information System (INIS)

    Andrew, A.S.; Giblin, A.M.

    2000-01-01

    The chemical composition and evolution of formation waters associated with gas production in the Palm Valley field, Northern Territory, has important implications for reservoir management, saline water disposal, and gas reserve calculations. Historically, the occurrence of saline formation water in gas fields has been the subject of considerable debate. A better understanding of the origin, chemical evolution and movement of the formation water at Palm Valley has important implications for future reservoir management, disposal of highly saline water and accurate gas reserves estimation. Major and trace element abundance data suggest that a significant component of the highly saline water from Palm Valley has characteristics that may have been derived from a modified evaporated seawater source such as an evaporite horizon. The most dilute waters probably represent condensate and the variation in the chemistry of the intermediate waters suggests they were derived from a mixture of the condensate with the highly saline brine. The chemical and isotopic results raise several interrelated questions; the ultimate source of the high salinity and the distribution of apparently mixed compositions. In this context several key observation are highlighted. Strontium concentrations are extremely high in the brines; although broadly similar in their chemistry, the saline fluids are neither homogeneous nor well mixed; the 87 Sr/ 86 Sr ratios in the brines are higher than the signatures preserved in the evaporitic Bitter Springs Formation, and all other conceivably marine-related evaporites (Strauss, 1993); the 87 Sr/ 86 Sr ratios in the brines are lower than those measured from groundmass carbonates in the host rocks, and that the 87 Sr/ 86 Sr ratios of the brines are similar, but still somewhat higher than those measured in vein carbonates from the reservoir. It is concluded that the high salinity brine entered the reservoir during the Devonian uplift and was subsequently

  4. Chemical risk factors responsible for the formation of wedge-shaped lesions

    Directory of Open Access Journals (Sweden)

    Perić Dejan

    2015-01-01

    Full Text Available Introduction: Non-carious tooth substances loss pose a major health problem of a modern man. The literature often collectively describes all non-carious lesions and is therefore difficult to compare results obtained by different authors. Chemical factors are one of the predisposing factors responsible for the formation of wedge-shaped erosions. Aim: Examination of chemical risk factors as one of the predisposing causes responsible for the formation of wedge-shaped lesions. Method: We examined 62 patients with wedge-shaped erosions (mean age 45.52 ± 12.03 years, 58.1% of men and 60 patients without erosions in the control group (mean age 34.40 ± 9.28 years, 60% men . The entire examination was completed by using a questionnaire at the Dental Clinic of the University of Pristina - Kosovska Mitrovica. salivary pH was measured by the pH meter. Results: The results show that the wedge-shaped lesions often occur equally in both men and women. Considerably often it might appear in older people but can also occur in teenagers. Patients with wedge-shaped erosion have increased acidity of saliva, a heightened sense of acid in the mouth and consume a lot more carbonated drinks compared to patients without erosions. Conclusion: Wedge-shaped lesions are more common in people older than 40 years. Taking into account the results obtained in this study it can be concluded that the chemical risk factors truly fall within the predisposing factors that may be responsible for the creation of wedge-shaped erosions.

  5. The iodine reactivity

    International Nuclear Information System (INIS)

    2003-01-01

    The iodine is an important element because it has long life isotopes (such as iodine 129) and a great mobility in natural media. Iodine presents a complex chemistry because of its volatility and its strong redox reactivity. The S.E.C.R. works to better understand the reactivity of this element in different natural, industrial or biological environments. It plays a part in thermochemical sites as a possible way of hydrogen formation. This seminar gives some aspects relative to the chemical reactivity of iodine, since its thermochemistry in the I/S cycles to produce hydrogen to its reactivity in the natural medium and its potential radiological impact. This document includes 4 presentations transparencies) dealing with: the 129 I cycle rejected in the low radioactive gaseous and liquid effluents of the La Hague reprocessing plant (C. Frechou); a bibliographic review of iodine retention in soils (F. Bazer-Bachi); the hydrogen production and the iodine/sulfur thermochemical cycle (role of iodine in the process); and the direct characterization by electro-spray ionization mass spectroscopy of iodine fixation by fulvic acids (P. Reiller, B. Amekraz, C. Moulin, V. Moulin)

  6. Ultrafaint dwarfs—star formation and chemical evolution in the smallest galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Webster, David; Bland-Hawthorn, Joss [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Sutherland, Ralph, E-mail: d.webster@physics.usyd.edu.au [Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston, ACT 2611 (Australia)

    2014-11-20

    In earlier work, we showed that a dark matter halo with a virial mass of 10{sup 7} M {sub ☉} can retain a major part of its baryons in the face of the pre-ionization phase and supernova (SN) explosion from a 25 M {sub ☉} star. Here, we expand on the results of that work, investigating the star formation and chemical evolution of the system beyond the first SN. In a galaxy with a mass M {sub vir} = 10{sup 7} M {sub ☉}, sufficient gas is retained by the potential for a second period of star formation to occur. The impact of a central explosion is found to be much stronger than that of an off-center explosion both in blowing out the gas and in enriching it, as in the off-center case most of the SN energy and metals escape into the intergalactic medium. We model the star formation and metallicity, given the assumption that stars form for 100, 200, 400, and 600 Myr, and discuss the results in the context of recent observations of very low-mass galaxies. We show that we can account for most features of the observed relationship between [α/Fe] and [Fe/H] in ultra-faint dwarf galaxies with the assumption that the systems formed at a low mass, rather than being remnants of much larger systems.

  7. Assessing Chemical Transformation of Reactive, Interfacial Thin Films Made of End-Tethered Poly(2-vinyl-4,4-dimethyl azlactone) (PVDMA) Chains

    Energy Technology Data Exchange (ETDEWEB)

    Aden, Bethany [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Kite, Camille M. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Hopkins, Benjamin W. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Zetterberg, Anna [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Lokitz, Bradley S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Ankner, John Francis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Kilbey, S. Michael [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical and Biomolecular Engineering

    2017-01-24

    Designing thin films or surface scaffolds with an appropriate display of chemical functionality is useful for biomedical applications, sensing platforms, adhesives, and barrier coatings. Relationships between the structural characteristics of model thin films based on reactive poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) brushes and the amount and distribution of primary amines used to chemically functionalize the layer in situ are quantitatively detailed via neutron reflectometry and compared with results from ellipsometry. After functionalization, the PVDMA brush thickness increases as a result of the primary amines reacting with the azlactone rings. Both techniques show that the extent of functionalization by small-molecule amines depends on the size of the amine, the grafting density of brush chains and their molecular weight. However, constrained analysis of neutron reflectivity data predicated on that technique’s sensitivity to isotopic substitution and its ability to resolve structure at the nanoscale, shows that the extent of functionalization is not accurately represented by the average extent of functionalization determined from ellipsometric thickness: reactive modification is not uniform, even in modestly dense brushes, except when the penetrant is small. Additionally, there appears to be a loss of PVDMA chains during functionalization, attributed to chain scission resulting from additional stretching brought about by functionalization. These findings provide unprecedented insight into the alteration of surface properties by reactive modification and broadly support efforts to produce tailored surfaces in which properties such as friction, colloidal stability, adhesion, wettability, and biocompatibility can be modulated in situ by chemical modification.

  8. Star Formation, Quenching And Chemical Enrichment In Local Galaxies From Integral Field Spectroscopy

    Science.gov (United States)

    Belfiore, Francesco

    2017-08-01

    Within the currently well-established ΛCDM cosmological framework we still lack a satisfactory understanding of the processes that trigger, regulate and eventually quench star formation on galactic scales. Gas flows (including inflows from the cosmic web and supernovae-driven outflows) are considered to act as self-regulatory mechanisms, generating the scaling relations between stellar mass, star formation rate and metallicity observed in the local Universe by large spectroscopic surveys. These surveys, however, have so far been limited by the availability of only one spectrum per galaxy. The aim of this dissertation is to expand the study of star formation and chemical abundances to resolved scales within galaxies by using integral field spectroscopy (IFS) data, mostly from the ongoing SDSS-IV MaNGA survey. In the first part of this thesis I demonstrate the ubiquitous presence of extended low ionisation emission-line regions (LIERs) in both late- and early-type galaxies. By studying the Hα equivalent width and diagnostic line ratios radial profiles, together with tracers of the underlying stellar population, I show that LIERs are not due to a central point source but to hot evolved (post-asymptotic giant branch) stars. In light of this, I suggest a new classification scheme for galaxies based on their line emission. By analysing the colours, star formation rates, morphologies, gas and stellar kinematics and environmental properties of galaxies with substantial LIER emission, I identify two distinct populations. Galaxies where the central regions are LIER-like, but show star formation at larger radii are late types in which star formation is slowly quenched inside-out. This transformation is associated with massive bulges. Galaxies dominated by LIER emission at all radii, on the other hand, are red-sequence galaxies harbouring a residual cold gas component, acquired mostly via external accretion. Quiescent galaxies devoid of line emission reside in denser

  9. Enhanced reactivation of UV-irradiated adenovirus 2 in HeLa cells treated with non-mutagenic chemical agents

    Energy Technology Data Exchange (ETDEWEB)

    Piperakis, S.M.; McLennan, A.G. (Liverpool Univ. (UK). Dept. of Biochemistry)

    1985-03-01

    Treatment of HeLa cells with ethanol and sodium arsenite, compounds which are known to elicit the heat-shock response, before infection with UV-irradiated adenovirus 2 has been found to result in the enhanced reactivation of the damaged virus in a manner similar to that obtained by pre-irradiation or heating of the cells. Enhanced reactivation may be the result of the inhibition of DNA synthesis caused by these agents since hydroxyurea also produced a significant enhancement.

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

    Science.gov (United States)

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

    2017-08-01

    Inhibition of acetylcholinesterase (AChE) with organophosphorus compounds has a detrimental effect on human life. Oxime K203 seems to be one of the promising reactivators for tabun-inhibited AChE than (K027, K127, and K628). These reactivators differ only in the linker units between the two pyridinium rings. The conformational analyses performed with quantum chemical RHF/6-31G* level for K027, K127, K203 and K628 showed that the minimum energy conformers have different orientations of the active and peripheral pyridinium rings for these reactivator molecules. K203 with (-CH 2 -CH=CH-CH 2 -) linker unit possesses more open conformation compared to the other reactivators. Such orientation of K203 experiences favorable interaction with the surrounding residues of catalytic anionic site (CAS) and peripheral anionic site (PAS) of tabun-inhibited AChE. From the steered molecular dynamics simulations, it has been observed that the oxygen atom of the oxime group of K203 reactivator approaches nearest to the P-atom of the SUN203 (3.75 Å) at lower time scales (less than ~1000 ps) as compared to the other reactivators. K203 experiences less number of hydrophobic interaction with the PAS residues which is suggested to be an important factor for the efficient reactivation process. In addition, K203 crates large number of H-bonding with CAS residues SUN203, Phe295, Tyr337, Phe338 and His447. K203 barely changes its conformation during the SMD simulation process and hence the energy penalty to adopt any other conformation is minimal in this case as compared to the other reactivators. The molecular mechanics and Poisson-Boltzmann surface area binding energies obtained for the interaction of K203 inside the gorge of tabun inhibited AChE is substantially higher (-290.2 kcal/mol) than the corresponding K628 reactivator (-260.4 kcal/mol), which also possess unsaturated aromatic linker unit.

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

    Science.gov (United States)

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

    2017-08-01

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

  12. The effect of lipid peroxidation products on reactive oxygen species formation and nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 macrophages.

    Science.gov (United States)

    Ambrozova, Gabriela; Pekarova, Michaela; Lojek, Antonin

    2011-02-01

    Lipid peroxidation induced by oxidants leads to the formation of highly reactive metabolites. These can affect various immune functions, including reactive oxygen species (ROS) and nitric oxide (NO) production. The aim of the present study was to investigate the effects of lipid peroxidation products (LPPs) - acrolein, 4-hydroxynonenal, and malondialdehyde - on ROS and NO production in RAW 264.7 macrophages and to compare these effects with the cytotoxic properties of LPPs. Macrophages were stimulated with lipopolysaccharide (0.1 μg/ml) and treated with selected LPPs (concentration range: 0.1-100 μM). ATP test, luminol-enhanced chemiluminescence, Griess reaction, Western blotting analysis, amperometric and total peroxyl radical-trapping antioxidant parameter assay were used for determining the LPPs cytotoxicity, ROS and NO production, inducible nitric oxide synthase expression, NO scavenging, and antioxidant properties of LPPs, respectively. Our study shows that the cytotoxic action of acrolein and 4-hydroxynonenal works in a dose- and time-dependent manner. Further, our results imply that acrolein, 4-hydroxynonenal, and malondialdehyde can inhibit, to a different degree, ROS and NO production in stimulated macrophages, partially independently of their toxic effect. Also, changes in enzymatic pathways (especially NADPH-oxidase and nitric oxide synthase inhibition) and NO scavenging properties are included in the downregulation of reactive species formation. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. Impact of Microcystis aeruginosa Exudate on the Formation and Reactivity of Iron Oxide Particles Following Fe(II) and Fe(III) Addition.

    Science.gov (United States)

    Garg, Shikha; Wang, Kai; Waite, T David

    2017-05-16

    Impact of the organic exudate secreted by a toxic strain of Microcystis aeruginosa on the formation, aggregation, and reactivity of iron oxides that are formed on addition of Fe(II) and Fe(III) salts to a solution of the exudate is investigated in this study. The exudate has a stabilizing effect on the particles formed with decreased aggregation rate and increased critical coagulant concentration required for diffusion-limited aggregation to occur. These results suggest that the presence of algal exudates from Microcystis aeruginosa may significantly influence particle aggregation both in natural water bodies where Fe(II) oxidation results in oxide formation and in water treatment where Fe(III) salts are commonly added to aid particle growth and contaminant capture. The exudate also affects the reactivity of iron oxide particles formed with exudate coated particles undergoing faster dissolution than bare iron oxide particles. This has implications to iron availability, especially where algae procure iron via dissolution of iron oxide particles as a result of either reaction with reducing moieties, light-mediated ligand to metal charge transfer and/or reaction with siderophores. The increased reactivity of exudate coated particles is attributed, for the most part, to the smaller size of these particles, higher surface area and increased accessibility of surface sites.

  14. Probing the chemical environments of early star formation: A multidisciplinary approach

    Science.gov (United States)

    Hardegree-Ullman, Emily Elizabeth

    Chemical compositions of prestellar and protostellar environments in the dense interstellar medium are best quantified using a multidisciplinary approach. For my dissertation, I completed two projects to measure molecular abundances during the earliest phases of star formation. The first project investigates gas phase CO depletion in molecular cloud cores, the progenitors of star systems, using infrared photometry and molecular line spectroscopy at radio wavelengths. Hydrogenation of CO depleted onto dust is an important first step toward building complex organic molecules. The second project constrains polycyclic aromatic hydrocarbon (PAH) abundances toward young stellar objects (YSO). Band strengths measured from laboratory spectroscopy of pyrene/water ice mixtures were applied to estimate abundances from features attributed to PAHs in observational YSO spectra. PAHs represent a distinct but important component of interstellar organic material that is widely observed but not well quantified in star-forming regions.

  15. Aluminum Oxide Formation On Fecral Catalyst Support By Electro-Chemical Coating

    Directory of Open Access Journals (Sweden)

    Yang H.S.

    2015-06-01

    Full Text Available FeCrAl is comprised essentially of Fe, Cr, Al and generally considered as metallic substrates for catalyst support because of its advantage in the high-temperature corrosion resistance, high mechanical strength, and ductility. Oxidation film and its adhesion on FeCrAl surface with aluminum are important for catalyst life. Therefore various appropriate surface treatments such as thermal oxidation, Sol, PVD, CVD has studied. In this research, PEO (plasma electrolytic oxidation process was applied to form the aluminum oxide on FeCrAl surface, and the formed oxide particle according to process conditions such as electric energy and oxidation time were investigated. Microstructure and aluminum oxide particle on FeCrAl surface after PEO process was observed by FE-SEM and EDS with element mapping analysis. The study presents possibility of aluminum oxide formation by electro-chemical coating process without any pretreatment of FeCrAl.

  16. Glass Formation, Chemical Properties and Surface Analysis of Cu-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Akihisa Inoue

    2011-04-01

    Full Text Available This paper reviews the influence of alloying elements Mo, Nb, Ta and Ni on glass formation and corrosion resistance of Cu-based bulk metallic glasses (BMGs. In order to obtain basic knowledge for application to the industry, corrosion resistance of the Cu–Hf–Ti–(Mo, Nb, Ta, Ni and Cu–Zr–Ag–Al–(Nb bulk glassy alloy systems in various solutions are reported in this work. Moreover, X-ray photoelectron spectroscopy (XPS analysis is performed to clarify the surface-related chemical characteristics of the alloy before and after immersion in the solutions; this has lead to a better understanding of the correlation between the surface composition and the corrosion resistance.

  17. Five Decades with Polyunsaturated Fatty Acids: Chemical Synthesis, Enzymatic Formation, Lipid Peroxidation and Its Biological Effects

    Directory of Open Access Journals (Sweden)

    Angel Catalá

    2013-01-01

    Full Text Available I have been involved in research on polyunsaturated fatty acids since 1964 and this review is intended to cover some of the most important aspects of this work. Polyunsaturated fatty acids have followed me during my whole scientific career and I have published a number of studies concerned with different aspects of them such as chemical synthesis, enzymatic formation, metabolism, transport, physical, chemical, and catalytic properties of a reconstructed desaturase system in liposomes, lipid peroxidation, and their effects. The first project I became involved in was the organic synthesis of [1-14C] eicosa-11,14-dienoic acid, with the aim of demonstrating the participation of that compound as a possible intermediary in the biosynthesis of arachidonic acid “in vivo.” From 1966 to 1982, I was involved in several projects that study the metabolism of polyunsaturated fatty acids. In the eighties, we studied fatty acid binding protein. From 1990 up to now, our laboratory has been interested in the lipid peroxidation of biological membranes from various tissues and different species as well as liposomes prepared with phospholipids rich in PUFAs. We tested the effect of many antioxidants such as alpha tocopherol, vitamin A, melatonin and its structural analogues, and conjugated linoleic acid, among others.

  18. Tidal interaction, star formation and chemical evolution in blue compact dwarf galaxy Mrk 22

    Science.gov (United States)

    Paswan, A.; Omar, A.; Jaiswal, S.

    2018-02-01

    The optical spectroscopic and radio interferometric H I 21 cm-line observations of the blue compact dwarf galaxy Mrk 22 are presented. The Wolf-Rayet (WR) emission-line features corresponding to high ionization lines of He II λ4686 and C IV λ5808 from young massive stars are detected. The ages of two prominent star-forming regions in the galaxy are estimated as ∼10 and ∼ 4 Myr. The galaxy has non-thermal radio deficiency, which also indicates a young starburst and lack of supernovae events from the current star formation activities, consistent with the detection of WR emission-line features. A significant N/O enrichment is seen in the fainter star-forming region. The gas-phase metallicities [12 + log(O/H)] for the bright and faint regions are estimated as 7.98±0.07 and 7.46±0.09, respectively. The galaxy has a large diffuse H I envelop. The H I images reveal disturbed gas kinematics and H I clouds outside the optical extent of the galaxy, indicating recent tidal interaction or merger in the system. The results strongly indicate that Mrk 22 is undergoing a chemical and morphological evolution due to ongoing star formation, most likely triggered by a merger.

  19. Analytical model of chemical phase and formation of DSB in chromosomes by ionizing radiation.

    Science.gov (United States)

    Barilla, Jiří; Lokajíček, Miloš; Pisaková, Hana; Simr, Pavel

    2013-03-01

    Mathematical analytical model of the processes running in individual radical clusters during the chemical phase (under the presence of radiomodifiers) proposed by us earlier has been further developed and improved. It has been applied to the data presented by Blok and Loman characterizing the oxygen effect in SSB and DSB formation (in water solution and at low-LET radiation) also in the region of very small oxygen concentrations, which cannot be studied with the help of experiments done with living cells. In this new analysis the values of all reaction rates and diffusion parameters known from literature have been made use of. The great increase of SSB and DSB at zero oxygen concentration may follow from the fact that at small oxygen concentrations the oxygen absorbs other radicals while at higher concentrations the formation of oxygen radicals prevails. It explains the double oxygen effect found already earlier by Ewing. The model may be easily extended to include also the effects of other radiomodifiers present in medium during irradiation.

  20. Analytical model of chemical phase and formation of DSB in chromosomes by ionizing radiation

    International Nuclear Information System (INIS)

    Barilla, Jiři; Simr, Pavel; Lokajíček, Miloš; Pisaková, Hana

    2013-01-01

    Mathematical analytical model of the processes running in individual radical clusters during the chemical phase (under the presence of radiomodifiers) proposed by us earlier has been further developed and improved. It has been applied to the data presented by Blok and Loman characterizing the oxygen effect in SSB and DSB formation (in water solution and at low-LET radiation) also in the region of very small oxygen concentrations, which cannot be studied with the help of experiments done with living cells. In this new analysis the values of all reaction rates and diffusion parameters known from literature have been made use of. The great increase of SSB and DSB at zero oxygen concentration may follow from the fact that at small oxygen concentrations the oxygen absorbs other radicals while at higher concentrations the formation of oxygen radicals prevails. It explains the double oxygen effect found already earlier by Ewing. The model may be easily extended to include also the effects of other radiomodifiers present in medium during irradiation.

  1. Alloy composition dependence of formation of porous Ni prepared by rapid solidification and chemical dealloying

    Energy Technology Data Exchange (ETDEWEB)

    Qi Zhen [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China); Zhang Zhonghua [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China)], E-mail: zh_zhang@sdu.edu.cn; Jia Haoling [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China); Qu Yingjie [Shandong Labor Occupational Technology College, Jingshi Road 388, Jinan 250022 (China); Liu Guodong; Bian Xiufang [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China)

    2009-03-20

    In this paper, the effect of alloy composition on the formation of porous Ni catalysts prepared by chemical dealloying of rapidly solidified Al-Ni alloys has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and N{sub 2} adsorption experiments. The experimental results show that rapid solidification and alloy composition have a significant effect on the phase constituent and microstructure of Al-Ni alloys. The melt spun Al-20 at.% Ni alloy consists of {alpha}-Al, NiAl{sub 3} and Ni{sub 2}Al{sub 3}, while the melt spun Al-25 and 31.5 at.% Ni alloys comprise NiAl{sub 3} and Ni{sub 2}Al{sub 3}. Moreover, the formation and microstructure of the porous Ni catalysts are dependent upon the composition of the melt spun Al-Ni alloys. The morphology and size of Ni particles in the Ni catalysts inherit from those of grains in the melt spun Al-Ni alloys. Rapid solidification can extend the alloy composition of Al-Ni alloys suitable for preparation of the Ni catalysts, and obviously accelerate the dealloying process of the Al-Ni alloys.

  2. Chemical Evolution and Star Formation History of the Disks of Spirals in Local Group

    Science.gov (United States)

    Yin, J.

    2011-05-01

    Milky Way (MW), M31 and M33 are the only three spiral galaxies in our Local group. MW and M31 have similar mass, luminosity and morphology, while M33 is only about one tenth of MW in terms of its baryonic mass. Detailed theoretical researches on these three spirals will help us to understand the formation and evolution history of both spiral galaxies and Local group. Referring to the phenomenological chemical evolution model adopted in MW disk, a similar model is established to investigate the star formation and chemical enrichment history of these three local spirals. Firstly, the properties of M31 disk are studied by building a similar chemical evolution model which is able to successfully describe the MW disk. It is expected that a simple unified phenomenological chemical evolution model could successfully describe the radial and global properties of both disks. Comparing with the former work, we adopt an extensive data set as model constraints, including the star formation profile of M31 disk derived from the recent UV data of GALEX. The comparison among the observed properties of these two disks displays very interesting similarities in their radial profiles when the distance from the galactic center is expressed in terms of the corresponding scale length. This implies some common processes in their formation and evolution history. Based on the observed data of the gas mass surface density and SFR surface density, the SFR radial profile of MW can be well described by Kennicutt-Schmidt star formation law (K-S law) or modified K-S law (SFR is inversely proportional to the distance from the galactic center), but this is not applicable to the M31 disk. Detailed calculations show that our unified model describes fairly well all the main properties of the MW disk and most properties of M31 disk, provided that the star formation efficiency of M31 disk is adjusted to be twice as large as that of MW disk (as anticipated from the lower gas fraction of M31). However, the

  3. Formation of anodic layers on InAs (111)III. Study of the chemical composition

    Energy Technology Data Exchange (ETDEWEB)

    Valisheva, N. A., E-mail: valisheva@thermo.isp.nsc.ru; Tereshchenko, O. E. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Prosvirin, I. P.; Kalinkin, A. V. [Russian Academy of Sciences, Boreskov Institute of Catalysis, Siberian Branch (Russian Federation); Goljashov, V. A. [Novosibirsk State University (Russian Federation); Levtzova, T. A. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Bukhtiyarov, V. I. [Russian Academy of Sciences, Boreskov Institute of Catalysis, Siberian Branch (Russian Federation)

    2012-04-15

    The chemical composition of {approx}20-nm-thick anodic layers grown on InAs (111)III in alkaline and acid electrolytes containing or not containing NH{sub 4}F is studied by X-ray photoelectron spectroscopy. It is shown that the composition of fluorinated layers is controlled by the relation between the concentrations of fluorine and hydroxide ions in the electrolyte and by diffusion processes in the growing layer. Fluorine accumulates at the (anodic layer)/InAs interface. Oxidation of InAs in an acid electrolyte with a low oxygen content and a high NH{sub 4}F content brings about the formation of anodic layers with a high content of fluorine and elemental arsenic and the formation of an oxygen-free InF{sub x}/InAs interface. Fluorinated layers grown in an alkaline electrolyte with a high content of O{sup 2-} and/or OH{sup -} groups contain approximately three times less fluorine and consist of indium and arsenic oxyfluorides. No distinction between the compositions of the layers grown in both types of fluorine-free electrolytes is established.

  4. Formation and changes of groundwater chemical composition of the western Carpathian carbonate systems

    International Nuclear Information System (INIS)

    Flakova, R.

    1998-01-01

    Karst-fissure water, genetically related to the Mesozoic carbonate complexes, participates in the formation of drinking water supplies in Slovakia. There were evaluated 13 drinking water resources which are built up from originating in the valley of the Starohorsky potok brook and the Harmanecka dolina valley in the Velka Fatra mountain range. These sources represent an important part of the Jergaly branch and the Harmanec branch of the public water supply 'Pohronsky skupinovy vodovod'. As starting data 538 chemical analyses of the checking process for period from 1981 to 1994 and also the results of own groundwater sampling from the April 1992 and October 1995 were used. Basic hydrogeochemical evaluation has shown that observed sources represented typical carbonatogenic water. Evaluation of carbonate equilibria confirmed the assumption supposing that in conditions of karst-fissure and karst circulation the water is non-saturated with carbonate minerals. Based on obtained data the quality regime of groundwater was described. Chemical composition of groundwater shows typical changes in certain time of a year, short-term. seasonal and long-term changes can be observed. The trend analysis of HCO 3 - , SO 4 2+ , NO 3 - , Cl - , ChSK Mn and dissolved O 2 were used to evaluation of stability of chemical composition. Increasing amounts of nitrate concentrations in all sources, sulphate pollution in the sources of Jergaly branch and chloride pollution in groundwater of Harmanec branch confirmed anthropogenic influences. The main problem of water remains often the microbial pollution. Obtained results showed high vulnerability of karst-fissure water and the continuously threatening danger of its pollution. (author)

  5. Particle-bound reactive oxygen species (PB-ROS) emissions and formation pathways in residential wood smoke under different combustion and aging conditions

    Science.gov (United States)

    Zhou, Jun; Zotter, Peter; Bruns, Emily A.; Stefenelli, Giulia; Bhattu, Deepika; Brown, Samuel; Bertrand, Amelie; Marchand, Nicolas; Lamkaddam, Houssni; Slowik, Jay G.; Prévôt, André S. H.; Baltensperger, Urs; Nussbaumer, Thomas; El-Haddad, Imad; Dommen, Josef

    2018-05-01

    Wood combustion emissions can induce oxidative stress in the human respiratory tract by reactive oxygen species (ROS) in the aerosol particles, which are emitted either directly or formed through oxidation in the atmosphere. To improve our understanding of the particle-bound ROS (PB-ROS) generation potential of wood combustion emissions, a suite of smog chamber (SC) and potential aerosol mass (PAM) chamber experiments were conducted under well-determined conditions for different combustion devices and technologies, different fuel types, operation methods, combustion regimes, combustion phases, and aging conditions. The PB-ROS content and the chemical properties of the aerosols were quantified by a novel ROS analyzer using the DCFH (2',7'-dichlorofluorescin) assay and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). For all eight combustion devices tested, primary PB-ROS concentrations substantially increased upon aging. The level of primary and aged PB-ROS emission factors (EFROS) were dominated by the combustion device (within different combustion technologies) and to a greater extent by the combustion regimes: the variability within one device was much higher than the variability of EFROS from different devices. Aged EFROS under bad combustion conditions were ˜ 2-80 times higher than under optimum combustion conditions. EFROS from automatically operated combustion devices were on average 1 order of magnitude lower than those from manually operated devices, which indicates that automatic combustion devices operated at optimum conditions to achieve near-complete combustion should be employed to minimize PB-ROS emissions. The use of an electrostatic precipitator decreased the primary and aged ROS emissions by a factor of ˜ 1.5 which is however still within the burn-to-burn variability. The parameters controlling the PB-ROS formation in secondary organic aerosol were investigated by employing a regression model, including the fractions of

  6. Evaluation of maillard reaction variables and their effect on heterocyclic amine formation in chemical model systems.

    Science.gov (United States)

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

    2015-02-01

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

  7. Aerosolization, Chemical Characterization, Hygroscopicity and Ice Formation of Marine Biogenic Particles

    Science.gov (United States)

    Alpert, P. A.; Radway, J.; Kilthau, W.; Bothe, D.; Knopf, D. A.; Aller, J. Y.

    2013-12-01

    The oceans cover the majority of the earth's surface, host nearly half the total global primary productivity and are a major source of atmospheric aerosol particles. However, effects of biological activity on sea spray generation and composition, and subsequent cloud formation are not well understood. Our goal is to elucidate these effects which will be particularly important over nutrient rich seas, where microorganisms can reach concentrations of 10^9 per mL and along with transparent exopolymer particles (TEP) can become aerosolized. Here we report the results of mesocosm experiments in which bubbles were generated by two methods, either recirculating impinging water jets or glass frits, in natural or artificial seawater containing bacteria and unialgal cultures of three representative phytoplankton species, Thalassiosira pseudonana, Emiliania huxleyi, and Nannochloris atomus. Over time we followed the size distribution of aerosolized particles as well as their hygroscopicity, heterogeneous ice nucleation potential, and individual physical-chemical characteristics. Numbers of cells and the mass of dissolved and particulate organic carbon (DOC, POC), TEP (which includes polysaccharide-containing microgels and nanogels >0.4 μm in diameter) were determined in the bulk water, the surface microlayer, and aerosolized material. Aerosolized particles were also impacted onto substrates for ice nucleation and water uptake experiments, elemental analysis using computer controlled scanning electron microscopy and energy dispersive analysis of X-rays (CCSEM/EDX), and determination of carbon bonding with scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Regardless of bubble generation method, the overall concentration of aerosol particles, TEP, POC and DOC increased as concentrations of bacterial and phytoplankton cells increased, stabilized, and subsequently declined. Particles cloud formation and potential

  8. Iodine-mediated coastal particle formation: an overview of the Reactive Halogens in the Marine Boundary Layer (RHaMBLe Roscoff coastal study

    Directory of Open Access Journals (Sweden)

    G. McFiggans

    2010-03-01

    Full Text Available This paper presents a summary of the measurements made during the heavily-instrumented Reactive Halogens in the Marine Boundary Layer (RHaMBLe coastal study in Roscoff on the North West coast of France throughout September 2006. It was clearly demonstrated that iodine-mediated coastal particle formation occurs, driven by daytime low tide emission of molecular iodine, I2, by macroalgal species fully or partially exposed by the receding waterline. Ultrafine particle concentrations strongly correlate with the rapidly recycled reactive iodine species, IO, produced at high concentrations following photolysis of I2. The heterogeneous macroalgal I2 sources lead to variable relative concentrations of iodine species observed by path-integrated and in situ measurement techniques.

    Apparent particle emission fluxes were associated with an enhanced apparent depositional flux of ozone, consistent with both a direct O3 deposition to macroalgae and involvement of O3 in iodine photochemistry and subsequent particle formation below the measurement height. The magnitude of the particle formation events was observed to be greatest at the lowest tides with the highest concentrations of ultrafine particles growing to the largest sizes, probably by the condensation of anthropogenically-formed condensable material. At such sizes the particles should be able to act as cloud condensation nuclei at reasonable atmospheric supersaturations.

  9. Measurements of reactive trace gases and variable O3 formation rates in some South Carolina biomass burning plumes

    Science.gov (United States)

    Akagi, S. K.; Yokelson, R. J.; Burling, I. R.; Meinardi, S.; Simpson, I.; Blake, D. R.; McMeeking, G. R.; Sullivan, A.; Lee, T.; Kreidenweis, S.; Urbanski, S.; Reardon, J.; Griffith, D. W. T.; Johnson, T. J.; Weise, D. R.

    2013-02-01

    support an earlier finding that C3-C4 alkynes may be of use as biomass burning indicators on the time-scale of hours to a day. It was possible to measure the downwind chemical evolution of the plume on four of the fires and significant O3 formation (ΔO3/ΔCO from 10-90%) occurred in all of these plumes within two hours. The slowest O3 production was observed on a cloudy day with low co-emission of NOx. The fastest O3 production was observed on a sunny day when the downwind plume almost certainly incorporated significant additional NOx by passing over the Columbia, SC metropolitan area. Due to rapid plume dilution, it was only possible to acquire high-quality downwind data for two other trace gas species (formaldehyde and methanol) during two of the fires. In all four of these cases, significant increases in formaldehyde and methanol were observed in <2 h. This is likely the first direct observation of post-emission methanol production in biomass burning plumes. Post-emission production of methanol does not always happen in young biomass burning plumes, and its occurrence in this study could have involved terpene precursors to a significant extent.

  10. Monitoring reactive oxygen species formation and localisation in living cells by use of the fluorescent probe CM-H(2)DCFDA and confocal laser microscopy

    DEFF Research Database (Denmark)

    Kristiansen, Kim Anker; Jensen, Poul Erik; Møller, Ian Max

    2009-01-01

    Reactive oxygen species (ROS) develop as a consequence of wounding, light stress and chemical imbalances but act also as signals in living cells. The integrity of cells is seriously endangered, if ROS cannot be controlled by scavenging molecules and other repair mechanisms of the cell. For studying...... ROS development and signalling under stress, a reliable indicator is needed. We have tested the ROS sensitive dye 5-(and-6) chloromethyl-2',7' dichlorodihydrofluorescein diacetate acetyl ester (CM-H(2)DCFDA) using onion bulb scale and leaf epidermis as well as Arabidopsis leaves and protoplasts. ROS...

  11. Analyzing relationships between surface perturbations and local chemical reactivity of metal sites: Alkali promotion of O2 dissociation on Ag(111)

    Science.gov (United States)

    Xin, Hongliang; Linic, Suljo

    2016-06-01

    Many commercial heterogeneous catalysts are complex structures that contain metal active sites promoted by multiple additives. Developing fundamental understanding about the impact of these perturbations on the local surface reactivity is crucial for catalyst development and optimization. In this contribution, we develop a general framework for identifying underlying mechanisms that control the changes in the surface reactivity of a metal site (more specifically the adsorbate-surface interactions) upon a perturbation in the local environment. This framework allows us to interpret fairly complex interactions on metal surfaces in terms of specific, physically transparent contributions that can be evaluated independently of each other. We use Cs-promoted dissociation of O2 as an example to illustrate our approach. We concluded that the Cs adsorbate affects the outcome of the chemical reaction through a strong alkali-induced electric field interacting with the static dipole moment of the O2/Ag(111) system.

  12. A kinetic model for toluene oxidation comprising benzylperoxy benzoate ester as reactive intermediate in the formation of benzaldehyde

    NARCIS (Netherlands)

    Hoorn, J.A.A.; Alsters, P. L.; Versteeg, G. F.

    During the oxidation of toluene under semibatch conditions, the formation of benzyl alcohol is initially equal to the rate of formation of benzaldehyde. As the overall conversion increases the benzyl alcohol concentration at first decreases much faster than benzaldehyde, but this decrease slows down

  13. A kinetic model for toluene oxidation comprising benzylperoxy benzoate ester as reactive intermediate in the formation of benzaldehyde

    NARCIS (Netherlands)

    Hoorn, J.A.A.; Hoorn, J.A.A.; Alsters, P.L.; Versteeg, Geert

    2005-01-01

    During the oxidation of toluene under semibatch conditions, the formation of benzyl alcohol is initially equal to the rate of formation of benzaldehyde. As the overall conversion increases the benzyl alcohol concentration at first decreases much faster than benzaldehyde, but this decrease slows down

  14. Harmonisation of food consumption data format for dietary exposure assessments of chemicals analysed in raw agricultural commodities

    DEFF Research Database (Denmark)

    Boon, Polly E.; Ruprich, Jiri; Petersen, Annette

    2009-01-01

    In this paper, we present an approach to format national food consumption data at raw agricultural commodity (RAC) level. In this way, the data is both formatted in a harmonised way given the comparability of RACs between countries, and suitable to assess the dietary exposure to chemicals analysed......, and the use of the FAO/WHO Codex Classification system of Foods and Animal Feeds to harmonise the classification. We demonstrate that this approach works well for pesticides and glycoalkaloids, and is an essential step forward in the harmonisation of risk assessment procedures within Europe when addressing...... chemicals analysed in RACs by all national food control systems....

  15. Induction of molecular endpoints by reactive oxygen species in human lung cells predicted by physical chemical properties of engineered nanoparticles

    Science.gov (United States)

    A series of six titanium dioxide and two cerium oxide engineered nanomaterials were assessed for their ability to induce cytotoxicity, reactive oxygen species (ROS), and various types of DNA and protein damage in human respiratory BEAS-2B cells exposed in vitro for 72 hours at se...

  16. How well can global chemistry models calculate the reactivity of short-lived greenhouse gases in the remote troposphere, knowing the chemical composition

    Directory of Open Access Journals (Sweden)

    M. J. Prather

    2018-05-01

    Full Text Available We develop a new protocol for merging in situ measurements with 3-D model simulations of atmospheric chemistry with the goal of integrating these data to identify the most reactive air parcels in terms of tropospheric production and loss of the greenhouse gases ozone and methane. Presupposing that we can accurately measure atmospheric composition, we examine whether models constrained by such measurements agree on the chemical budgets for ozone and methane. In applying our technique to a synthetic data stream of 14 880 parcels along 180° W, we are able to isolate the performance of the photochemical modules operating within their global chemistry-climate and chemistry-transport models, removing the effects of modules controlling tracer transport, emissions, and scavenging. Differences in reactivity across models are driven only by the chemical mechanism and the diurnal cycle of photolysis rates, which are driven in turn by temperature, water vapor, solar zenith angle, clouds, and possibly aerosols and overhead ozone, which are calculated in each model. We evaluate six global models and identify their differences and similarities in simulating the chemistry through a range of innovative diagnostics. All models agree that the more highly reactive parcels dominate the chemistry (e.g., the hottest 10 % of parcels control 25–30 % of the total reactivities, but do not fully agree on which parcels comprise the top 10 %. Distinct differences in specific features occur, including the spatial regions of maximum ozone production and methane loss, as well as in the relationship between photolysis and these reactivities. Unique, possibly aberrant, features are identified for each model, providing a benchmark for photochemical module development. Among the six models tested here, three are almost indistinguishable based on the inherent variability caused by clouds, and thus we identify four, effectively distinct, chemical models. Based on this

  17. Chemical Modeling of the Reactivity of Short-Lived Greenhouse Gases: A Model Inter-Comparison Prescribing a Well-Measured, Remote Troposphere

    Science.gov (United States)

    Prather, Michael J.; Flynn, Clare M.; Zhu, Xin; Steenrod, Stephen D.; Strode, Sarah A.; Fiore, Arlene M.; Correa, Gustavo; Murray, Lee T.; Lamarque, Jean-Francois

    2018-01-01

    We develop a new protocol for merging in situ measurements with 3-D model simulations of atmospheric chemistry with the goal of integrating over the data to identify the most reactive air parcels in terms of tropospheric production and loss of the greenhouse gases ozone and methane. Presupposing that we can accurately measure atmospheric composition, we examine whether models constrained by such measurements agree on the chemical budgets for ozone and methane. In applying our technique to a synthetic data stream of 14,880 parcels along 180W, we are able to isolate the performance of the photochemical modules operating within their global chemistry-climate and chemistry-transport models, removing the effects of modules controlling tracer transport, emissions, and scavenging. Differences in reactivity across models are driven only by the chemical mechanism and the diurnal cycle of photolysis rates, which are driven in turn by temperature, water vapor, solar zenith angle, clouds, and possibly aerosols and overhead ozone, which are calculated in each model. We evaluate six global models and identify their differences and similarities in simulating the chemistry through a range of innovative diagnostics. All models agree that the more highly reactive parcels dominate the chemistry (e.g., the hottest 10% of parcels control 25-30% of the total reactivities), but do not fully agree on which parcels comprise the top 10%. Distinct differences in specific features occur, including the regions of maximum ozone production and methane loss, as well as in the relationship between photolysis and these reactivities. Unique, possibly aberrant, features are identified for each model, providing a benchmark for photochemical module development. Among the 6 models tested here, 3 are almost indistinguishable based on the inherent variability caused by clouds, and thus we identify 4, effectively distinct, chemical models. Based on this work, we suggest that water vapor differences in

  18. How well can global chemistry models calculate the reactivity of short-lived greenhouse gases in the remote troposphere, knowing the chemical composition

    Science.gov (United States)

    Prather, Michael J.; Flynn, Clare M.; Zhu, Xin; Steenrod, Stephen D.; Strode, Sarah A.; Fiore, Arlene M.; Correa, Gustavo; Murray, Lee T.; Lamarque, Jean-Francois

    2018-05-01

    We develop a new protocol for merging in situ measurements with 3-D model simulations of atmospheric chemistry with the goal of integrating these data to identify the most reactive air parcels in terms of tropospheric production and loss of the greenhouse gases ozone and methane. Presupposing that we can accurately measure atmospheric composition, we examine whether models constrained by such measurements agree on the chemical budgets for ozone and methane. In applying our technique to a synthetic data stream of 14 880 parcels along 180° W, we are able to isolate the performance of the photochemical modules operating within their global chemistry-climate and chemistry-transport models, removing the effects of modules controlling tracer transport, emissions, and scavenging. Differences in reactivity across models are driven only by the chemical mechanism and the diurnal cycle of photolysis rates, which are driven in turn by temperature, water vapor, solar zenith angle, clouds, and possibly aerosols and overhead ozone, which are calculated in each model. We evaluate six global models and identify their differences and similarities in simulating the chemistry through a range of innovative diagnostics. All models agree that the more highly reactive parcels dominate the chemistry (e.g., the hottest 10 % of parcels control 25-30 % of the total reactivities), but do not fully agree on which parcels comprise the top 10 %. Distinct differences in specific features occur, including the spatial regions of maximum ozone production and methane loss, as well as in the relationship between photolysis and these reactivities. Unique, possibly aberrant, features are identified for each model, providing a benchmark for photochemical module development. Among the six models tested here, three are almost indistinguishable based on the inherent variability caused by clouds, and thus we identify four, effectively distinct, chemical models. Based on this work, we suggest that water vapor

  19. Study of a new hybrid process combining slurry infiltration and Reactive Chemical Vapour Infiltration for the realisation of Ceramic Matrix Composites

    International Nuclear Information System (INIS)

    Ledain, Olivier

    2014-01-01

    Ceramic matrix composites were originally developed for aerospace,military aeronautics or energy applications thanks to their good properties at high temperature. They are generally made by Chemical Vapor Infiltration (CVI). A new short hybrid process combining fiber preform slurry impregnation of ceramic powders with an innovative Reactive CVI (RCVI) route is proposed to reduce the production time. This route is based on the combination of Reactive Chemical Vapour Deposition (RCVD), which is often used to deposit coatings on fibres, with the Chemical Vapor Infiltration (CVI).In RCVD, the absence of one element of the deposited carbide in the initial gas phase involves the consumption/conversion of the solid substrate. In this work, the RCVD growth and the associated consumption were studied with different parameters in the Ti-H-Cl-C chemical system. The study has been completed with the chemical products analysis, combining XRD, XPS and FTIR. Then, the partial conversion of sub-micrometer carbon powders into titanium carbide and the consolidation of green bodies by RCVI from H 2 /TiCl 4 gaseous infiltration were studied. The residual porosity and the final TiC content were measured in the bulk of the infiltrated powders by image analysis from scanning electron microscopy. Depending on temperature, few hundred micrometers-depth infiltrations are obtained.Finally, the results have been transposed to the RCVI into CMC-type pre-forms. Despite a minimal TiC content of 25% in the overall preform, the results shown a bad homogeneity of the infiltration and a poor cohesion of fibres with RCVI consolidated powder of their environment. (author) [fr

  20. Effect of flavoring chemicals on free radical formation in electronic cigarette aerosols.

    Science.gov (United States)

    Bitzer, Zachary T; Goel, Reema; Reilly, Samantha M; Elias, Ryan J; Silakov, Alexey; Foulds, Jonathan; Muscat, Joshua; Richie, John P

    2018-05-20

    Flavoring chemicals, or flavorants, have been used in electronic cigarettes (e-cigarettes) since their inception; however, little is known about their toxicological effects. Free radicals present in e-cigarette aerosols have been shown to induce oxidative stress resulting in damage to proliferation, survival, and inflammation pathways in the cell. Aerosols generated from e-liquid solvents alone contain high levels of free radicals but few studies have looked at how these toxins are modulated by flavorants. We investigated the effects of different flavorants on free radical production in e-cigarette aerosols. Free radicals generated from 49 commercially available e-liquid flavors were captured and analyzed using electron paramagnetic resonance (EPR). The flavorant composition of each e-liquid was analyzed by gas chromatography mass spectroscopy (GCMS). Radical production was correlated with flavorant abundance. Ten compounds were identified and analyzed for their impact on free radical generation. Nearly half of the flavors modulated free radical generation. Flavorants with strong correlations included β-damascone, δ-tetradecalactone, γ-decalactone, citral, dipentene, ethyl maltol, ethyl vanillin, ethyl vanillin PG acetal, linalool, and piperonal. Dipentene, ethyl maltol, citral, linalool, and piperonal promoted radical formation in a concentration-dependent manner. Ethyl vanillin inhibited the radical formation in a concentration dependent manner. Free radical production was closely linked with the capacity to oxidize biologically-relevant lipids. Our results suggest that flavoring agents play an important role in either enhancing or inhibiting the production of free radicals in flavored e-cigarette aerosols. This information is important for developing regulatory strategies aimed at reducing potential harm from e-cigarettes. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Effect of finite chemical potential on QGP-hadron phase transition in a statistical model of fireball formation

    International Nuclear Information System (INIS)

    Ramanathan, R.; Singh, S.S.; Jha, A.K.; Gupta, K.K.

    2011-01-01

    We study the effect of finite chemical potential for the QGP constituents in the Ramanathan et al. statistical model. While the earlier computations using this model with vanishing chemical potentials indicated a weakly first order phase transition for the system in the vicinity of 170 MeV, the introduction of finite values for the chemical potentials of the constituents makes the transition a smooth roll over of the phases, while allowing fireball formation with radius of a few 'fermi' to take place. This seems to be in conformity with the latest consensus on the nature of the QGP-Hadron phase transition. (author)

  2. Menadione induces the formation of reactive oxygen species and depletion of GSH-mediated apoptosis and inhibits the FAK-mediated cell invasion.

    Science.gov (United States)

    Kim, Yun Jeong; Shin, Yong Kyoo; Sohn, Dong Suep; Lee, Chung Soo

    2014-09-01

    Menadione induces apoptosis in tumor cells. However, the mechanism of apoptosis in ovarian cancer cells exposed to menadione is not clear. In addition, it is unclear whether menadione-induced apoptosis is mediated by the depletion of glutathione (GSH) contents that is associated with the formation of reactive oxygen species. Furthermore, the effect of menadione on the invasion and migration of human epithelial ovarian cancer cells has not been studied. Therefore, we investigated the effects of menadione exposure on apoptosis, cell adhesion, and cell migration using the human epithelial ovarian carcinoma cell lines OVCAR-3 and SK-OV-3. The results suggest that menadione may induce apoptotic cell death in ovarian carcinoma cell lines by activating the mitochondrial pathway and the caspase-8- and Bid-dependent pathways. The apoptotic effect of menadione appears to be mediated by the formation of reactive oxygen species and the depletion of GSH. Menadione inhibited fetal-bovine-serum-induced cell adhesion and migration of OVCAR-3 cells, possibly through the suppression the focal adhesion kinase (FAK)-dependent activation of cytoskeletal-associated components. Therefore, menadione might be beneficial in the treatment of epithelial ovarian adenocarcinoma and combination therapy.

  3. Salinity variations and chemical compositions of waters in the Frio Formation, Texas Gulf Coast. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Morton, R.A.; Garrett, C.M. Jr.; Posey, J.S.; Han, J.H.; Jirik, L.A.

    1981-11-01

    Waters produced from sandstone reservoirs of the deep Frio Formation exhibit spatial variations in chemical composition that roughly coincide with the major tectonic elements (Houston and Rio Grande Embayments, San Marcos Arch) and corresponding depositional systems (Houston and Norias deltas, Greta-Carancahua barrier/strandplain system) that were respectively active along the upper, lower, and middle Texas Coast during Frio deposition. Within an area, salinities are usually depth dependent, and primary trends closely correspond to pore pressure gradients and thermal gradients. Where data are available (mainly in Brazoria County) the increases in TDS and calcium with depth coincide with the zone of albitization, smectite-illite transition, and calcite decrease in shales. Waters have fairly uniform salinities when produced from the same sandstone reservoir within a fault block or adjacent fault blocks with minor displacement. In contrast, stratigraphically equivalent sandstones separated by faults with large displacement usually yield waters with substantially different salinities owing to the markedly different thermal and pressure gradients across the faults that act as barriers to fluid movement.

  4. THE RESEARCH PROJECTS THROUGH UNIVERSITY-BUSINESS RELATIONSHIP IN THE CONTINUOUS FORMATION OF CHEMICAL ENGINEERS

    Directory of Open Access Journals (Sweden)

    Diana Niurka Concepción Toledo

    2015-07-01

    Full Text Available Economic and social development requires the establishment of strategic alliances of society to higher education. The university, based on the benefits of deep multiplier effect, has the ability and the duty to manage knowledge and transferring scientific results obtained in its substantive processes: teaching, scientific research and university extension to the productive context. In this paper the experience developed by Chemical Engineering Department of Central University “Marta Abreu” of Las Villas in which the scientific community in the industry of sugar cane is prepared to manage knowledge through university- business relationship is exposed. For this effort, an innovative process focused on the execution of research projects from scientific and technological demands set by the sugar factory "Antonio Sanchez" Aguada de Pasajeros develops. In the development of the planned actions it will be attended teacher-researchers, specialists and managers of the company and the incorporation of students in the race for the exercise of labor practice, innovative aspect of its formation, which consolidates professional preparation. The experience showed the potential offered by the connection of university science with industry through the establishment of innovative processes in knowledge management to ensure greater relevance of university substantive processes and the immediate incorporation of scientific results to the productive sector as the supreme goal of this activity.

  5. Ferrospheres from fly ashes of Chelyabinsk coals: chemical composition, morphology and formation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sokol, E.V.; Kalugin, V.M.; Nigmatulina, E.N.; Volkova, N.I.; Frenkel, A.E.; Maksimova, N.V. [Geophysics and Mineralogy Sb RAS, Novosibirsk (Russian Federation). United Institute of Geology

    2002-05-01

    Ferrospheres originating during the pulverised fuel firing of brown coals from the Chelyabinsk basin (South Urals, Russia) have been examined for determination of their chemical and phase compositions, morphology and formation conditions. Most of the ferrospheres are close to ideal spheres with dendritic or skeletal structure. The appearance of microsphere inner anatomy is determined by morphology of ferrispinel aggregates, which compose more than 85 vol% of these globules. The analysed ferrispinels are complex solid solutions based on FeFe{sub 2}O{sub 4} with impurities of MgFe{sub 2}O{sub 4}, MnFe{sub 2}O{sub 4} and nCaO x mFe{sub 2}O{sub 3}. The glasses coexisted with ferrispinel crystallites are basic-ultrabasic in composition. Ferrospheres are the quenching products of high-ferrous melts originated from melting of iron-bearing carbonate admixtures in coals. The mass crystallisation of ferrispinels in ferrospheres was a result of iron changes from Fe{sup 2+} to Fe{sup 3+} and following ferritisation of high-ferrous melts during molten drops cooling. The residual melt is quenched to form a low-silicon, high-calcium, high-ferrous glass. the skeletal and dendritic forms of ferrispinel are due to their crystallisation under drastic supercooling conditions. 22 refs., 6 figs., 2 tabs.

  6. Formation of by-products at radiation - chemical treatment of water solutions of chloroform

    International Nuclear Information System (INIS)

    Ahmedov, S.A.; Abdullayev, E.T.; Gurbanov, M.A.; Gurbanov, A.H.; Ibadov, N.A.

    2006-01-01

    Full text: Radiation-chemical treatment is considered as a perspective method of water purification from chloroform. It provides the high level of purification (98 percent) of water solutions from chloroform and other chlorine-containing compounds. Meanwhile, other chlorine-containing products can be formed during the process of chloroform degradation and as a result of it the quality of water can change. This work studies the formation of by-products of γ-radiolysis of water solutions at various initial contents of chloroform. Dichlormethane and tetrachlorethane are identified as by-products. It is shown that at high contents of chloroform after certain adsorbed dose the forming products are reducing till their full disappearing. At small contents of chloroform in the studied interval of doses di-chlor-methane is forming. Differences of dose dependences of by-products at various contents of chloroform can be connected with the transition from radical mechanism to chain reaction at high concentrations of chloroform in solutions saturated by oxygen. pH-solutions also reduces during the radiation till pH=1, although this reduction also depends on initial concentration of chloroform. Essential change of pH occurs only at the radiolysis of water solutions containing chloroform ≥0,2 percent. And at radiating of 0,03 percent solution pH reduces only till 4 - 4,5

  7. Chemical analysis of reactive species and antimicrobial activity of/nwater treated by nanosecond pulsed DBD air plasma

    Czech Academy of Sciences Publication Activity Database

    Laurita, R.; Barbieri, D.; Gherardi, M.; Colombo, V.; Lukeš, Petr

    2015-01-01

    Roč. 3, č. 2 (2015), s. 53-61 ISSN 2212-8166 R&D Projects: GA MŠk(CZ) LD14080 Grant - others:European Cooperation in Science and Technology(XE) COST TD1208 Institutional support: RVO:61389021 Keywords : Dielectric barrier discharge * Plasma activated water * Reactive species * Peroxynitrite * Phenol degradation * Candida albicans * Staphylococcus aureus * Antimicrobial activity * Nosocomial infections Subject RIV: BL - Plasma and Gas Discharge Physics http://www.sciencedirect.com/science/article/pii/S2212816615300081

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

    Science.gov (United States)

    Jha, Nayansi; Ryu, Jae Jun

    2017-01-01

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

  9. Researchers Use NRAO Telescope to Study Formation Of Chemical Precursors to Life

    Science.gov (United States)

    2006-08-01

    percent dust. The GBT discoveries have been made in just two prototypical interstellar clouds. The molecules acetamide (CH3CONH2), cyclopropenone (H2C3O), propenal (CH2CHCHO), propanal (CH3CH2CHO), and ketenimine (CH2CNH) were found in a cloud called Sagittarius B2(N), which is near the center of our Milky Way Galaxy some 26,000 light years from Earth. This star-forming region is the largest repository of complex interstellar molecules known. The molecules methyl-cyano-diacetylene (CH3C5N), methyl-triacetylene (CH3C6H), and cyanoallene (CH2CCHCN) were found in the Taurus Molecular Cloud (TMC-1), which is relatively nearby at a distance of 450 light years. The starless TMC-1 cloud is dark and cold with a temperature of only 10 degrees above absolute zero and may eventually evolve into a star-forming region. "The discovery of these large organic molecules in the coldest regions of the interstellar medium has certainly changed the belief that large organic molecules would only have their origins in hot molecular cores. It has forced us to rethink the paradigms of interstellar chemistry," said Anthony Remijan of the NRAO. These large molecules found with the GBT are built up from smaller ones, the scientists say, by two principal mechanisms. In the first, simple chemical reactions add an atom to a molecular structure residing on the surface of a dust grain. As an example of this process, the researchers cite a molecule called cyclopropenylidene (c-C3H2, where "c-" means cyclic), which contains three carbon atoms in a ring. Cyclopropenylidene was discovered in interstellar space in 1987, and is known to be highly reactive. In 2005, using the GBT, scientists discovered another molecule, cyclopropenone (c-H2C3O), which can be produced by adding an oxygen atom to cyclopropenylidene. The second method for constructing larger molecules from smaller ones involves neutral-radical reactions that can occur within the gas in an interstellar cloud. For example, in 2006, the scientists

  10. Chemical equilibrium of hydrogen and aqueous solutions of 1 : 1 bicarbonate and formate salts with a common cation

    NARCIS (Netherlands)

    Engel, D.C.; Versteeg, G.F.; Swaaij, W.P.M. van

    1997-01-01

    The chemical equilibrium of hydrogen and aqueous solutions of 1:1 bicarbonate and formate salts with a common cation has been investigated in an intensively stirred batch reactor: MHCO3(aq) + H2(aq) ↔ MOOCH(aq) + H2O(l) This was accomplished for the sodium (M = Na), potassium (M = K) and ammonium (M

  11. Host-cell reactivation of UV-irradiated and chemically-treated herpes simplex virus-1 by xeroderma pigmentosum, xp heterozygotes and normal skin fibroblasts

    International Nuclear Information System (INIS)

    Selsky, C.A.

    1978-01-01

    The host-cell reactivation of UV-irradiated and N-acetoxy-2-acetylamino-fluorene-treated herpes simplex virus type 1 strain MP was studied in normal and xeroderma pigmentosum human skin fibroblasts. Virus treated with either agent demonstrated lower survival in XP cells from complementation groups A, B, C and D than in normal fibroblasts. The relative reactivation ability of XP cells from the different genetic complementation groups was found to be the same for both irradiated and chemically treated virus. In addition, the inactivation kinetics for virus treated with either agent in the XP variant were comparable to that seen in normal skin fibroblasts. The addition of 2 or 4 mmoles caffeine to the post-infection assay medium had no effect on the inactivation kinetics of virus treated by either agent in the XP variant or in XP cells from the different genetic complementation groups. Treatment of the virus with nitrogen mustard resulted in equivalent survival in normal and XP genetic complementation group D cells. No apparent defect was observed in the ability of XP heterozygous skin fibroblasts to repair virus damaged with up to 100 μg N-acetoxy-2-acetylaminofluorene per ml. These findings indicate that the repair of UV-irradiated and N-acetoxy-2-acetylaminofluorene-treated virus is accomplished by the same pathway or different pathways sharing a common intermediate step and that the excision defect of XP cells plays little if any role in the reactivation of nitrogen mustard treated virus. (Auth.)

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

    Directory of Open Access Journals (Sweden)

    Yosuke Matsubara

    2017-02-01

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

  13. New conception in the theory of chemical bonding; the role of core and valence atomic orbitals in formation of chemical bonds

    International Nuclear Information System (INIS)

    Kostikova, G.P.; Kostikov, Yu.P.; Korol'kov, D.V.

    1986-01-01

    An analysis of x-ray photoelectron spectra leads to a simple and consistent conception in the theory of chemical bonding, which satisfies (unlike the simple MO-LCAO theory) the virial theorem and defines the roles of the core and valence atomic orbitals in the formation of chemical bonds. Its essence is clear from the foregoing: the exothermic effects of the formation of complexes are caused by the lowering of the energies of the core levels of the central atoms with simultaneous small changes in the energies of the core levels of the ligands despite the significant destabilization of the delocalized valence MO's in comparison to the orbital energies of the corresponding free atoms. In order to confirm these ideas, they recorded the x-ray photoelectron spectra of the valence region and the inner levels of single-crystal silicon carbide, silicon, and graphite

  14. Reactive transport and mass balance modeling of the Stimson sedimentary formation and altered fracture zones constrain diagenetic conditions at Gale crater, Mars

    Science.gov (United States)

    Hausrath, E. M.; Ming, D. W.; Peretyazhko, T. S.; Rampe, E. B.

    2018-06-01

    On a planet as cold and dry as present-day Mars, evidence of multiple aqueous episodes offers an intriguing view into very different past environments. Fluvial, lacustrine, and eolian depositional environments are being investigated by the Mars Science Laboratory Curiosity in Gale crater, Mars. Geochemical and mineralogical observations of these sedimentary rocks suggest diagenetic processes affected the sediments. Here, we analyze diagenesis of the Stimson formation eolian parent material, which caused loss of olivine and formation of magnetite. Additional, later alteration in fracture zones resulted in preferential dissolution of pyroxene and precipitation of secondary amorphous silica and Ca sulfate. The ability to compare the unaltered parent material with the reacted material allows constraints to be placed on the characteristics of the altering solutions. In this work we use a combination of a mass balance approach calculating the fraction of a mobile element lost or gained, τ, with fundamental geochemical kinetics and thermodynamics in the reactive transport code CrunchFlow to examine the characteristics of multiple stages of aqueous alteration at Gale crater, Mars. Our model results indicate that early diagenesis of the Stimson sedimentary formation is consistent with leaching of an eolian deposit by a near-neutral solution, and that formation of the altered fracture zones is consistent with a very acidic, high sulfate solution containing Ca, P and Si. These results indicate a range of past aqueous conditions occurring at Gale crater, Mars, with important implications for past martian climate and environments.

  15. Microbial and Chemical Enhancement of In-Situ Carbon Mineralization in Geological Formation

    Energy Technology Data Exchange (ETDEWEB)

    Matter, J.; Chandran, K.

    2013-05-31

    Predictions of global energy usage suggest a continued increase in carbon emissions and rising concentrations of CO{sub 2} in the atmosphere unless major changes are made to the way energy is produced and used. Various carbon capture and storage (CCS) technologies are currently being developed, but unfortunately little is known regarding the fundamental characteristics of CO{sub 2}-mineral reactions to allow a viable in-situ carbon mineralization that would provide the most permanent and safe storage of geologically-injected CO{sub 2}. The ultimate goal of this research project was to develop a microbial and chemical enhancement scheme for in-situ carbon mineralization in geologic formations in order to achieve long-term stability of injected CO{sub 2}. Thermodynamic and kinetic studies of CO{sub 2}-mineral-brine systems were systematically performed to develop the in-situ mineral carbonation process that utilizes organic acids produced by a microbial reactor. The major participants in the project are three faculty members and their graduate and undergraduate students at the School of Engineering and Applied Science and at the Lamont-Doherty Earth Observatory at Columbia University: Alissa Park in Earth and Environmental Engineering & Chemical Engineering (PI), Juerg Matter in Earth and Environmental Science (Co-PI), and Kartik Chandran in Earth and Environmental Engineering (Co-PI). Two graduate students, Huangjing Zhao and Edris Taher, were trained as a part of this project as well as a number of graduate students and undergraduate students who participated part-time. Edris Taher received his MS degree in 2012 and Huangjing Zhao will defend his PhD on Jan. 15th, 2014. The interdisciplinary training provided by this project was valuable to those students who are entering into the workforce in the United States. Furthermore, the findings from this study were and will be published in referred journals to disseminate the results. The list of the papers is given at

  16. Prooxidant action of furanone compounds: implication of reactive oxygen species in the metal-dependent strand breaks and the formation of 8-hydroxy-2'-deoxyguanosine in DNA.

    Science.gov (United States)

    Murakami, K; Haneda, M; Makino, T; Yoshino, M

    2007-07-01

    Prooxidant properties of furanone compounds including 2,5-furanone (furaneol, 4-hydroxy-2,5-dimethyl-furan-3-one), 4,5-furanone (4,5-dimethyl-3-hydroxy-2(5H)-furanone) (sotolone) and cyclotene (2-hydroxy-3-methyl-2-cyclopenten-1-one) were analyzed in relation to the metal-reducing activity. Only 2.5-furanone known as a "strawberry or pineapple furanone" inactivated aconitase the most sensitive enzyme to active oxygen in the presence of ferrous sulfate, suggesting the furaneol/iron-mediated generation of reactive oxygen species. 2,5-Furanone caused strand scission of pBR322 DNA in the presence of copper. Treatment of calf thymus DNA with 2,5-furanone plus copper produced 8-hydroxy-2'-deoxyguanosine in DNA. 2,5-Furanone showed a potent copper-reducing activity, and thus, DNA strand breaks and the formation of 8-hydroxy-2'-deoxyguanosine by 2,5-furanone can be initiated by the production of superoxide radical through the reduction of cupric ion to cuprous ion, resulting in the conversion to hydrogen peroxide and hydroxyl radical. However, an isomer and analog of 2,5-furanone, 4,5-furanone and cyclotene, respectively, did not show an inactivation of aconitase, DNA injuries including strand breakage and the formation of 8-hydroxy-2'-deoxyguanosine, and copper-reducing activity. Cytotoxic effect of 2,5-furanone with hydroxyketone structure can be explained by its prooxidant properties: furaneol/transition metal complex generates reactive oxygen species causing the inactivation of aconitase and the formation of DNA base damage by hydroxyl radical.

  17. Quantum-chemical analysis of formation reactions of Со2+ complexes

    Directory of Open Access Journals (Sweden)

    Viktor F. Vargalyuk

    2017-11-01

    Full Text Available Based on the analysis of quantum chemical calculations results (GAMESS, density functional theory, B3LYP method as to coordination compounds of Co2+ions with H2O, NH3, OH–, F–, Cl–, Br–, I–, CN–, Ac–, Ak– generally given by [Co(H2O6–nLn]2+nx, it has been demonstrated that within the selected series of ligands, there is no correlation between the amount of energy of monosubstituted cobalt aqua complexes formation(∆Е and pK1,just like between the effective nuclear charge of the central atom (z*Со and pK1. According to the behavior of ∆Е and z*Со,we identified two groups of ligands. The first group (OH–, F–, Ac–, Ak–, CN–, NH3 demonstrates logical ∆Е decrease caused by the growth of z*Со. On the contrary, the second group (Cl–, Br–, I– demonstrates ∆Е increase caused by the growth of z*Со. This phenomenon is explained by the change in electronegativity and polarizability of donor atoms in groups and periods of the periodic table. It is established that linear correlations given by lgK = A + B·z*Со can be actualized only for complexes having ligands with similar donor atoms. Referring to the literature on stepwise complex formation of hydroxide, amine and chloride cobalt complexes in combination with z*Со calculations results, we determined A and B constants of lgK, z*Со-correlations for the atoms of oxygen (30.2, –17.7; nitrogen (125.4, –69.9 and chlorine (–6.3, 5.8. The existence of the detected correlation series enables us to lean on lgK,z*М–dependence parameters for the fixed donor atom and to determine Kn values for various complexes with complex-based ligands using calculations and z*М data. This applies to complexes having central atoms of the same nature as well as simple monodentate ligands. The mentioned approach was used to calculate the stability constants for acrylate cobalt complexes (lgK1 = 1.2 и lgК2 = 4.3, which are not covered in literature.

  18. Phosphorylcholine functionalized dendrimers for the formation of highly stable and reactive gold nanoparticles and their glucose conjugation for biosensing

    International Nuclear Information System (INIS)

    Jia Lan; Lv Liping; Xu Jianping; Ji Jian

    2011-01-01

    Phosphorylcholine (PC)-functionalized poly(amido amine) (PAMAM) dendrimers were prepared and used as both reducing and stabilizing agents for synthesis of highly stable and reactive gold nanoparticles (Au NPs). Biomimetic PC-functionalized PAMAM dendrimers-stabilized gold nanoparticles (Au DSNPs) were formed by simply mixing the PC modified amine-terminated fifth-generation PAMAM dendrimers (G5-PC) with AuCl 4 − ions by controlling the pH, no additional reducing agents or other stabilizers were needed. The obtained Au DSNPs were shown to be spherical, with particle diameters ranging from 5 to 12 nm, the sizes and growth kinetics of Au DSNPs could be tuned by changing the pH and the initial molar ratio of dendrimers to gold as indicated by transmission electron microscopy (TEM) and UV–Vis data. The prepared Au DSNPs showed excellent stability including: (1) stable at wide pH (7–13) values; (2) stable at high salt concentrations up to 2 M NaCl; (3) non-specific protein adsorption resistance. More importantly, surface functionalization could be performed by introducing desired functional groups onto the remained reactive amine groups. This was exemplified by the glucose conjugation. The glucose conjugated Au DSNPs showed bio-specific interaction with Concanavalin A (Con A), which induced aggregation of the Au NPs. Colorimetric detection of Con A based on the plasmon resonance of the glucose conjugated Au DSNPs was realized. A limit of detection (LOD) for Con A was 0.6 μM, based on a signal-to-noise ratio (S/N) of 3. These findings demonstrated that the PC modified Au DSNPs could potentially serve as a versatile nano-platform for the biomedical applications.

  19. Formulation of chemically reactive foams for the dissolution of oxides polluting the secondary circuits of steam generators

    International Nuclear Information System (INIS)

    Provens, Helene

    1999-01-01

    The fouling of the Steam Generators (SG) secondary circuits, due to oxides deposits like magnetite (Fe 3 O 4 ), induces the degradation of the internal SG equipment, the reduction of the plant power, implying to clean these circuits. This operation made in liquid phase generates an important volume of effluents with an expensive cost of treatment. The use of a reactive foam allows the reduction of this volume by ten. Among the reactive tested, oxalic acid is the most efficient to dissolve a magnetite quantity of 10 g.l -1 , at ambient temperature for 24 hours, as imposed by the industrial wishes. The dissolution is not complete in our experimental conditions and is a complex reaction of autocatalytic type, composed of an acid attack, a reductive step, both followed by a slow diffusion. The surfactants generating the foam, which transport the reactive, are adsorbed on the magnetite but this affects weakly the dissolution. Its effectiveness is evaluated varying the experimental conditions. The wetting properties and the stability of the foam induce erosion and undissolved particles transport capacities, during its circulation into the SG. These particles trapped in the inter-bubble liquid films or carried by the piston effect of the foam bed, can be recovered on filters placed out of the SG. To quantify the transport, the influence of different parameters is studied: the more stable the foam is, the more important the transport is. Innocuousness tests showed that oxalic acid was not harmful for constitutive SG materials, either they were isolated or coupled. The cleaning by oxalic acid causes ferrous oxalates precipitation, representing 10 to 15 pc of the total iron quantity depending on the sample. A rinsing out with a foam containing 1 pc oxalic acid and 5 pc hydrogen peroxide allows the dissolution of these precipitates without corrosion problems. (author) [fr

  20. Role of focal adhesion tyrosine kinases in GPVI-dependent platelet activation and reactive oxygen species formation.

    Directory of Open Access Journals (Sweden)

    Naadiya Carrim

    Full Text Available We have previously shown the presence of a TRAF4/p47phox/Hic5/Pyk2 complex associated with the platelet collagen receptor, GPVI, consistent with a potential role of this complex in GPVI-dependent ROS formation. In other cell systems, NOX-dependent ROS formation is facilitated by Pyk2, which along with its closely related homologue FAK are known to be activated and phosphorylated downstream of ligand binding to GPVI.To evaluate the relative roles of Pyk2 and FAK in GPVI-dependent ROS formation and to determine their location within the GPVI signaling pathway.Human and mouse washed platelets (from WT or Pyk2 KO mice were pre-treated with pharmacological inhibitors targeting FAK or Pyk2 (PF-228 and Tyrphostin A9, respectively and stimulated with the GPVI-specific agonist, CRP. FAK, but not Pyk2, was found to be essential for GPVI-dependent ROS production and aggregation. Subsequent human platelet studies with PF-228 confirmed FAK is essential for GPVI-mediated phosphatidylserine exposure, α-granule secretion (P-selectin (CD62P surface expression and integrin αIIbβ3 activation. To determine the precise location of FAK within the GPVI pathway, we analyzed the effect of PF-228 inhibition in CRP-stimulated platelets in conjunction with immunoprecipitation and pulldown analysis to show that FAK is downstream of Lyn, Spleen tyrosine kinase (Syk, PI3-K and Bruton's tyrosine kinase (Btk and upstream of Rac1, PLCγ2, Ca2+ release, PKC, Hic-5, NOX1 and αIIbβ3 activation.Overall, these data suggest a novel role for FAK in GPVI-dependent ROS formation and platelet activation and elucidate a proximal signaling role for FAK within the GPVI pathway.

  1. Characteristics of chemical bond and vacancy formation in chalcopyrite-type CuInSe2 and related compounds

    International Nuclear Information System (INIS)

    Maeda, Tsuyoshi; Wada, Takahiro

    2009-01-01

    We studied characteristics of chemical bond and vacancy formation in chalcopyrite-type CuInSe 2 (CIS) by first principles calculations. The chalcopyrite-type CIS has two kinds of chemical bonds, Cu-Se and In-Se. The Cu-Se bond is a weak covalent bonding because electrons occupy both bonding and antibonding orbitals of Cu 3d and Se 4p and occupy only the bonding orbital (a 1 ) of Cu 4s and Se 4p and do not occupy the antibonding orbital (a 1 * ) of Cu 4s and Se 4p. On the other hand, the In-Se bond has a partially covalent and partially ionic character because the In 5s orbital covalently interacts with Se 4p; the In 5p orbital is higher than Se 4p and so the electron in the In 5p orbital moves to the Se 4p orbital. The average bond order of the Cu-Se and In-Se bonds can be calculated to be 1/4 and 1, respectively. The bond order of Cu-Se is smaller than that of In-Se. The characteristics of these two chemical bonds are related to the formation of Cu and In vacancies in CIS. The formation energy of the Cu vacancy is smaller than that of the In vacancy under both Cu-poor and In-poor conditions. The displacement (Δl) of the surrounding Se atoms after the formation of the Cu vacancy is smaller than the Δl after the formation of the In vacancy. The interesting and unique characteristics of CIS are discussed on the basis of the characteristics of the chemical bond. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Impact of chemical oxidation and water acidification on the mineralogical and physico-chemical properties of the Tournemire argillaceous formation

    International Nuclear Information System (INIS)

    Charpentier, D.

    2001-11-01

    The French Institute for Protection and Nuclear Safety (IPSN) has selected a site near Tournemire (France) for research programmes on deep geological waste disposal in clay-rich rock formation. A railway tunnel was built about 100 years ago through the thick indurated Toarcian argillite of the Tournemire Massif and two galleries were constructed five years ago. They are used to study the evolution of rock mineralogical composition, texture, water content and water-rock interactions in the excavated disturbed zone. Multi-scale and multi-technique investigations were carried out on the evolution of physical and mineralogical rock properties. Experiments and numerical modelling were used to predict changes due to water-rock interactions and subsequent rock mineralogy and water chemistry modifications. The argillite consists of detrital clay-rich layers and carbonate layers. Pyrites are always present in significant amounts (2 to 2.5 %). The rock presents very low porosity and very low water content (around 3 %). Leaching experiments show that the interstitial water is Na and SO 4 -rich and Cl-poor. The tunnel and galleries digging induces fracture formation. In the altered samples, the clay particles show a better orientation in the stratification plan, which increases the porosity. The oxidation effect yields to mineralogical transformation on the surfaces of the argillite: oxidation of pyrite, dissolution of calcite, dissolution of illite layers in interstratified I/S and formation of gypsum, Fe-oxi/hydroxides, celestite and jarosite. During cycles of hydration/dehydration, condensation water interacts with the argillite and quickly becomes Ca and SO 4 -rich. The local dissolution of clay particles leads to an increase of the chloride and potassium water content. These phenomena are important for the consideration of the underground work stability, especially the evolution of the water-rock equilibria during the re-hydration of the excavated disturbed zones. (author)

  3. Formation of reactive oxygen by N2O decomposition over binuclear cationic sites of Fe-ferrierite zeolite: Periodic DFT + U study

    Science.gov (United States)

    Avdeev, Vasilii I.; Bedilo, Alexander F.

    2018-03-01

    The electronic nature of sites over Fe-ferrierite zeolite stabilizing active α-oxygen is analyzed by the periodic DFT + U approach. It is shown that two antiferromagnetically coupled Fe2+ cations with bridging OH-bonds form a stable bi-nuclear site of the [Fe2+Fe2+] doped FER complex. Frontier orbitals of this complex populated by two electrons with minority spins are localized in the bandgap. As a result, [Fe2+Fe2+] unit acquires the properties of a binuclear Lewis acid dipolarophile for 1,3-dipole N2O. First reaction step of N2O decomposition follows the Huisgen‧s concept of the 1,3-dipolar cycloaddition concept followed by the formation of reactive oxygen species Fesbnd O.

  4. Engineering of the chemical reactivity of the Ti/HfO₂ interface for RRAM: experiment and theory.

    Science.gov (United States)

    Calka, Pauline; Sowinska, Malgorzata; Bertaud, Thomas; Walczyk, Damian; Dabrowski, Jarek; Zaumseil, Peter; Walczyk, Christian; Gloskovskii, Andrei; Cartoixà, Xavier; Suñé, Jordi; Schroeder, Thomas

    2014-04-09

    The Ti/HfO2 interface plays a major role for resistance switching performances. However, clear interface engineering strategies to achieve reliable and reproducible switching have been poorly investigated. For this purpose, we present a comprehensive study of the Ti/HfO2 interface by a combined experimental-theoretical approach. Based on the use of oxygen-isotope marked Hf*O2, the oxygen scavenging capability of the Ti layer is clearly proven. More importantly, in line with ab initio theory, the combined HAXPES-Tof-SIMS study of the thin films deposited by MBE clearly establishes a strong impact of the HfO2 thin film morphology on the Ti/HfO2 interface reactivity. Low-temperature deposition is thus seen as a RRAM processing compatible way to establish the critical amount of oxygen vacancies to achieve reproducible and reliable resistance switching performances.

  5. Probing the reactivity of nucleophile residues in human 2,3-diphosphoglycerate/deoxy-hemoglobin complex by aspecific chemical modifications.

    Science.gov (United States)

    Scaloni, A; Ferranti, P; De Simone, G; Mamone, G; Sannolo, N; Malorni, A

    1999-06-11

    The use of aspecific methylation reaction in combination with MS procedures has been employed for the characterization of the nucleophilic residues present on the molecular surface of the human 2,3-diphosphoglycerate/deoxy-hemoglobin complex. In particular, direct molecular weight determinations by ESMS allowed to control the reaction conditions, limiting the number of methyl groups introduced in the modified globin chains. A combined LCESMS-Edman degradation approach for the analysis of the tryptic peptide mixtures yielded to the exact identification of methylation sites together with the quantitative estimation of their degree of modification. The reactivities observed were directly correlated with the pKa and the relative surface accessibility of the nucleophilic residues, calculated from the X-ray crystallographic structure of the protein. The results here described indicate that this methodology can be efficiently used in aspecific modification experiments directed to the molecular characterization of the surface topology in proteins and protein complexes.

  6. Study of the Chemical Mechanism Involved in the Formation of Tungstite in Benzyl Alcohol by the Advanced QEXAFS Technique

    DEFF Research Database (Denmark)

    Olliges‐Stadler, Inga; Stötzel, Jan; Koziej, Dorota

    2012-01-01

    Insight into the complex chemical mechanism for the formation of tungstite nanoparticles obtained by the reaction of tungsten hexachloride with benzyl alcohol is presented herein. The organic and inorganic species involved in the formation of the nanoparticles were studied by time‐dependent gas......‐scanning extended X‐ray absorption fine structure spectroscopy enabled the time‐dependent evolution of the starting compound, the intermediates and the product to be monitored over the full reaction period. The reaction starts with fast chlorine substitution and partial reduction during the dissolution...

  7. Formation, characterization and dynamics of onion like carbon structures from nanodiamonds using reactive force-fields for electrical energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Ganesh, Panchapakesan [ORNL; Kent, Paul R [ORNL; Mochalin, Vadym N [ORNL

    2011-01-01

    We simulate the experimentally observed graphitization of nanodiamonds into multi-shell onion-like carbon nanostructures, also called carbon onions, at different temperatures, using reactive force fields. The simulations include long-range Coulomb and van der Waals interactions. Our results suggest that long-range interactions play a crucial role in the phase-stability and the graphitization process. Graphitization is both enthalpically and entropically driven and can hence be controlled with temperature. The outer layers of the nanodiamond have a lower kinetic barrier toward graphitization irrespective of the size of the nanodiamond and graphitize within a few-hundred picoseconds, with a large volume increase. The inner core of the nanodiamonds displays a large size-dependent kinetic barrier, and graphitizes much more slowly with abrupt jumps in the internal energy. It eventually graphitizes by releasing pressure and expands once the outer shells have graphitized. The degree of transformation at a particular temperature is thereby determined by a delicate balance between the thermal energy, long-range interactions, and the entropic/enthalpic free energy gained by graphitization. Upon full graphitization, a multi-shell carbon nanostructure appears, with a shell-shell spacing of about {approx}3.4 {angstrom} for all sizes. The shells are highly defective with predominantly five- and seven-membered rings to curve space. Larger nanodiamonds with a diameter of 4 nm can graphitize into spiral structures with a large ({approx}29-atom carbon ring) pore opening on the outermost shell. Such a large one-way channel is most attractive for a controlled insertion of molecules/ions such as Li ions, water, or ionic liquids, for increased electrochemical capacitor or battery electrode applications.

  8. Formation, characterization, and dynamics of onion-like carbon structures for electrical energy storage from nanodiamonds using reactive force fields

    Energy Technology Data Exchange (ETDEWEB)

    Ganesh, P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Kent, P. R. C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Mochalin, V. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering

    2011-10-01

    We simulate the experimentally observed graphitization of nanodiamonds into multi-shell onion-like carbonnanostructures, also called carbon onions, at different temperatures, using reactive force fields. The simulations include long-range Coulomb and van der Waals interactions. Our results suggest that long-range interactions play a crucial role in the phase-stability and the graphitization process. Graphitization is both enthalpically and entropically driven and can hence be controlled with temperature. The outer layers of the nanodiamond have a lower kinetic barrier toward graphitization irrespective of the size of the nanodiamond and graphitize within a few-hundred picoseconds, with a large volume increase. The inner core of the nanodiamonds displays a large size-dependent kinetic barrier, and graphitizes much more slowly with abrupt jumps in the internal energy. It eventually graphitizes by releasing pressure and expands once the outer shells have graphitized. The degree of transformation at a particular temperature is thereby determined by a delicate balance between the thermal energy, long-range interactions, and the entropic/enthalpic free energy gained by graphitization. Upon full graphitization, a multi-shell carbonnanostructure appears, with a shell-shell spacing of about ~3.4 Å for all sizes. The shells are highly defective with predominantly five- and seven-membered rings to curve space. Larger nanodiamonds with a diameter of 4 nm can graphitize into spiral structures with a large (~29-atom carbon ring) pore opening on the outermost shell. Such a large one-way channel is most attractive for a controlled insertion of molecules/ions such as Li ions, water, or ionic liquids, for increased electrochemical capacitor or battery electrode applications.

  9. Continental crust formation: Numerical modelling of chemical evolution and geological implications

    Science.gov (United States)

    Walzer, U.; Hendel, R.

    2017-05-01

    Oceanic plateaus develop by decompression melting of mantle plumes and have contributed to the growth of the continental crust throughout Earth's evolution. Occasional large-scale partial melting events of parts of the asthenosphere during the Archean produced large domains of precursor crustal material. The fractionation of arc-related crust during the Proterozoic and Phanerozoic contributed to the growth of continental crust. However, it remains unclear whether the continents or their precursors formed during episodic events or whether the gaps in zircon age records are a function of varying preservation potential. This study demonstrates that the formation of the continental crust was intrinsically tied to the thermoconvective evolution of the Earth's mantle. Our numerical solutions for the full set of physical balance equations of convection in a spherical shell mantle, combined with simplified equations of chemical continent-mantle differentiation, demonstrate that the actual rate of continental growth is not uniform through time. The kinetic energy of solid-state mantle creep (Ekin) slowly decreases with superposed episodic but not periodic maxima. In addition, laterally averaged surface heat flow (qob) behaves similarly but shows peaks that lag by 15-30 Ma compared with the Ekin peaks. Peak values of continental growth are delayed by 75-100 Ma relative to the qob maxima. The calculated present-day qob and total continental mass values agree well with observed values. Each episode of continental growth is separated from the next by an interval of quiescence that is not the result of variations in mantle creep velocity but instead reflects the fact that the peridotite solidus is not only a function of pressure but also of local water abundance. A period of differentiation results in a reduction in regional water concentrations, thereby increasing the temperature of the peridotite solidus and the regional viscosity of the mantle. By plausibly varying the

  10. Redox Reactivity of Cerium Oxide Nanoparticles Induces the Formation of Disulfide Bridges in Thiol-Containing Biomolecules.

    Science.gov (United States)

    Rollin-Genetet, Françoise; Seidel, Caroline; Artells, Ester; Auffan, Mélanie; Thiéry, Alain; Vidaud, Claude

    2015-12-21

    The redox state of disulfide bonds is implicated in many redox control systems, such as the cysteine-cystine couple. Among proteins, ubiquitous cysteine-rich metallothioneins possess thiolate metal binding groups susceptible to metal exchange in detoxification processes. CeO2 NPs are commonly used in various industrial applications due to their redox properties. These redox properties that enable dual oxidation states (Ce(IV)/Ce(III)) to exist at their surface may act as oxidants for biomolecules. The interaction among metallothioneins, cysteine, and CeO2 NPs was investigated through various biophysical approaches to shed light on the potential effects of the Ce(4+)/Ce(3+) redox system on the thiol groups of these biomolecules. The possible reaction mechanisms include the formation of a disulfide bridge/Ce(III) complex resulting from the interaction between Ce(IV) and the thiol groups, leading to metal unloading from the MTs, depending on their metal content and cluster type. The formation of stable Ce(3+) disulfide complexes has been demonstrated via their fluorescence properties. This work provides the first evidence of thiol concentration-dependent catalytic oxidation mechanisms between pristine CeO2 NPs and thiol-containing biomolecules.

  11. Real-time nonlinear feedback control of pattern formation in (bio)chemical reaction-diffusion processes: a model study.

    Science.gov (United States)

    Brandt-Pollmann, U; Lebiedz, D; Diehl, M; Sager, S; Schlöder, J

    2005-09-01

    Theoretical and experimental studies related to manipulation of pattern formation in self-organizing reaction-diffusion processes by appropriate control stimuli become increasingly important both in chemical engineering and cellular biochemistry. In a model study, we demonstrate here exemplarily the application of an efficient nonlinear model predictive control (NMPC) algorithm to real-time optimal feedback control of pattern formation in a bacterial chemotaxis system modeled by nonlinear partial differential equations. The corresponding drift-diffusion model type is representative for many (bio)chemical systems involving nonlinear reaction dynamics and nonlinear diffusion. We show how the computed optimal feedback control strategy exploits the system inherent physical property of wave propagation to achieve desired control aims. We discuss various applications of our approach to optimal control of spatiotemporal dynamics.

  12. Structure, Reactivity and Dynamics

    Indian Academy of Sciences (India)

    Understanding structure, reactivity and dynamics is the core issue in chemical ... functional theory (DFT) calculations, molecular dynamics (MD) simulations, light- ... between water and protein oxygen atoms, the superionic conductors which ...

  13. Supra-molecular structure and chemical reactivity of cellulose I studied using CP/MAS (sup)13 C-NMR

    CSIR Research Space (South Africa)

    Chunilall, Viren

    2013-08-01

    Full Text Available There are a few traditional methods of analysing the chemical properties of cellulose I. Some of these methods include the Permanganate number determination, which is used to obtain the lignin content of the pulp [12]. The acid insoluble lignin content... – Fundamental Aspects 88 [10] Fengel D, Wegener G. Wood Chemistry, Ultrastructure, Reactions, Walter de Gruyter; 1984. [11] Uhlmann T. Ullmann's encyclopedia of industrial chemistry. Paper and Pulp. 1991; 18 (A). [12] Permanganate number of pulp, Tappi T...

  14. Accessing the Impact of Sea-Salt Emissions on Aerosol Chemical Formation and Deposition Over Pearl River Delta, China

    Science.gov (United States)

    Fan, Q.; Wang, X.; Liu, Y.; Wu, D.; Chan, P. W.; Fan, S.; Feng, Y.

    2015-12-01

    Sea-salt aerosol (SSA) emissions have a significant impact on aerosol pollution and haze formation in the coastal areas. In this study, Models-3/CMAQ modeling system was utilized to access the impact of SSA emissions on aerosol chemical formation and deposition over Pearl River Delta (PRD), China in July 2006. More SSAs were transported inland from the open-ocean under the southeast wind in summertime. Two experiments (with and without SSA emissions in the CMAQ model) were set up to compare the modeling results with each other. The results showed that the increase of sulfate concentrations were more attributable to the primary emissions of coarse SO42- particles in SSA, while the increase of nitrate concentrations were more attributable to secondary chemical formations, known as the mechanisms of chloride depletion in SSA. In the coastal areas, 17.62 % of SO42-, 26.6% of NO3- and 38.2% of PM10 were attributed to SSA emissions, while those portions were less than 1% in the inland areas. The increases of PM10 and its components due to SSA emissions resulted in higher deposition fluxes over PRD, particularly in the coastal areas, except for the wet deposition of nitrate. Nitrate was more sensitive to SSA emissions in chemical formations than sulfate and dry deposition of aerosol was also more sensitive than that for wet deposition. Process analysis of sulfate and nitrate was applied to find out the difference of physical and chemical mechanisms between Guangzhou (the inland areas) and Zhuhai (the coastal areas). The negative contributions of dry deposition process to both sulfate and nitrate concentrations increased if SSA emissions were taken into account in the model, especially for Zhuhai. The negative contributions of cloud process also increased due to cloud scavenging and wet deposition process. In the coastal area, the gas-to-particle conversions became more active with high contributions of aerosol process to nitrate concentrations.

  15. Seasonality of New Particle Formation in Vienna, Austria - Influence of Air Mass Origin and Aerosol Chemical Composition

    Czech Academy of Sciences Publication Activity Database

    Wonaschütz, A.; Demattio, A.; Wagner, R.; Burkart, J.; Zíková, Naděžda; Vodička, Petr; Ludwig, W.; Steiner, G.; Schwarz, Jaroslav; Hitzenberger, R.

    2015-01-01

    Roč. 118, OCT 2015 (2015), s. 118-126 ISSN 1352-2310 R&D Projects: GA MŠk 7AMB12AT021; GA ČR(CZ) GBP503/12/G147 Grant - others:FWF(AT) P19515-N20 Institutional support: RVO:67985858 Keywords : urban aerosol * aerosol chemical composition * new particle formation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.459, year: 2015

  16. Achieving Chemical Equilibrium: The Role of Imposed Conditions in the Ammonia Formation Reaction

    Science.gov (United States)

    Tellinghuisen, Joel

    2006-01-01

    Under conditions of constant temperature T and pressure P, chemical equilibrium occurs in a closed system (fixed mass) when the Gibbs free energy G of the reaction mixture is minimized. However, when chemical reactions occur under other conditions, other thermodynamic functions are minimized or maximized. For processes at constant T and volume V,…

  17. Atmospheric photochemical reactivity and ozone production at two sites in Hong Kong: Application of a Master Chemical Mechanism-photochemical box model

    Science.gov (United States)

    Ling, Z. H.; Guo, H.; Lam, S. H. M.; Saunders, S. M.; Wang, T.

    2014-09-01

    A photochemical box model incorporating the Master Chemical Mechanism (v3.2), constrained with a full suite of measurements, was developed to investigate the photochemical reactivity of volatile organic compounds at a semirural site (Mount Tai Mo Shan (TMS)) and an urban site (Tsuen Wan (TW)) in Hong Kong. The levels of ozone (O3) and its precursors, and the magnitudes of the reactivity of O3 precursors, revealed significant differences in the photochemistry at the two sites. Simulated peak hydroperoxyl radical (HO2) mixing ratios were similar at TW and TMS (p = 0.05), while the simulated hydroxyl radical (OH) mixing ratios were much higher at TW (p TMS, but at TW, both HCHO and O3 photolyses were found to be major contributors. By contrast, radical-radical reactions governed HOx radical losses at TMS, while at TW, the OH + NO2 reaction was found to dominate in the morning and the radical-radical reactions at noon. Overall, the conversion of NO to NO2 by HO2 dictated the O3 production at the two sites, while O3 destruction was dominated by the OH + NO2 reaction at TW, and at TMS, O3 photolysis and the O3 + HO2 reaction were the major mechanisms. The longer OH chain length at TMS indicated that more O3 was produced for each radical that was generated at this site.

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

    DEFF Research Database (Denmark)

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

    . Degradation and transport processes of chlorinated ethenes are not well understood in such geological settings, therefore risk assessment and remediation at these sites are particularly challenging. In this work, a combined approach of chemical and isotope analysis on core samples, and reactive transport...... the source zone (between 6 and 12 mbs). Concentrations and stable isotope ratios of the mother compounds and their daughter products, as well as redox parameters, fatty acids and microbial data, were analyzed with discrete sub-sampling along the cores. More samples (each 5 mm) were collected around...... of dechlorination and degradation pathways (biotic reductive dechlorination or abiotic β-elimination with iron minerals) in three core profiles. The model includes diffusion in the matrix, sequential reductive dechlorination, abiotic degradation, isotope fractionation due to degradation and due to diffusion...

  19. Formation and reactivity of free radicals in 5-hydroxymethyl-2-furaldehyde--the effect on isoprenaline photostability.

    Science.gov (United States)

    Brustugun, Jørgen; Tønnesen, Hanne H; Edge, Ruth; Navaratnam, Suppiah

    2005-05-13

    Solutions of glucose are used as diluents for drugs in various drug infusions. When sterilized by heat small amounts of the substance 5-hydroxymethyl-2-furaldehyde (5-HMF) is produced from glucose. At a hospital ward such infusions may be exposed to irradiation; including UV-light. The photoreactivity of the furaldehyde is investigated. It is shown to photodestabilize the catecholamine isoprenaline. It is shown to be a producer, but also a consumer, of singlet oxygen. The excited triplet, cation and anion radical have been produced by pulse radiolysis and flash photolysis and their absorbance characteristics have been determined. The triplet absorption spectrum showed absorption bands at 320 and 430 nm with molar absorption coefficients of 4700 and 2600 M-1 cm-1, respectively. The anion radical showed absorption bands at 330 and 420 nm with molar absorption coefficients of 2000 and 300 M-1 cm-1, respectively. The cation radical had an absorption band at 320 nm with a molar absorption coefficient of 5000 M-1 cm-1. The quantum yield for the production of singlet oxygen, sensitized by the 5-HMF triplet, was determined to be 0.6, whilst the quantum yield for the triplet formation was 1.0. Aqueous solutions of 5-HMF were found to photoionize to yield the hydrated electron and the cation radical of 5-HMF in a biphotonic process. The influences of pH, buffer and glucose on the formation of transients were evaluated. The reactions between 5-HMF and the solvated electron, the hydroxyl radical and the superoxide were also studied.

  20. Chemical composition of essential oil in Mosla chinensis Maxim cv. Jiangxiangru and its inhibitory effect on Staphylococcus aureus biofilm formation

    Directory of Open Access Journals (Sweden)

    Peng Liang

    2018-03-01

    Full Text Available The essential oil of Mosla chinensis Maxim cv. Jiangxiangru is known for its antibacterial ability. This study aimed to investigate the chemical composition of Jiangxiangru essential oil and its inhibitory effect on Staphylococcus aureus biofilm formation. Gas chromatography/mass spectrometry (GC–MS was used to determine the chemical composition of Jiangxiangru essential oil. Subsequently, the eight major chemical components were quantitatively analyzed using GC– MS, and their minimum inhibitory concentration (MIC values against S. aureus were tested. Biofilm formation was detected by crystal violet semi-quantitative method and silver staining. Of the 59 peaks detected, 29 were identified by GC–MS. Of these peaks, thymol, carvacrol, p-cymene, γ-terpinene, thymol acetate, α-caryophyllene, 3-carene, and carvacryl acetate were present at a relatively higher concentration. The results of the quantitative test showed that thymol, carvacrol, p-cymene, and γ-terpinene were the major components of the essential oil. Among the eight reference substances, only thymol, carvacrol, and thymol acetate had lower MICs compared with the essential oil. Essential oil, carvacrol, carvacryl acetate, α-caryophyllene, and 3-carene showed the better inhibition of S. aureus biofilm formation. When one fourth of the MIC concentrations were used for these substances (0.0625 mg/mL for essential oil, 0.0305 mg/mL for carvacrol, 1.458 mg/mL for carvacryl acetate, 0.1268 mg/mL for α-caryophyllene, and 2.5975 mg/mL for 3-carene, the inhibition rates were over 80%. However, thymol, γ-terpinene, thymol acetate, and p-cymene showed a relatively poor inhibition of S. aureus biofilm formation. When 1× MIC concentrations of these substances were used, the inhibition rates were less than 50%. In conclusion, Jiangxiangru essential oil and its major components, carvacrol, carvacryl acetate, α-caryophyllene, and 3-carene, strongly inhibited biofilm formation in S. aureus.

  1. Optimizing the dual elemental thermal reactive deposition time in carbide layer formation on SUJ2 tool steel

    Science.gov (United States)

    Mochtar, Myrna Ariati; Putra, Wahyuaji Narottama; Mahardika, Bayu

    2018-05-01

    This paper presents developments contributing to the improvement of thermo-reactive deposition (TRD) process in producing hard carbide layers, on automotive components application. The problem in using FeV powder as a coating material that has been applied in the industries is it is high cost. In this study, FeCr powder coating material was mixed into FeV powder with a ratio of 35:65 weight percent. The SUJ2 steel pins components are processed at 980° C, with varying TRD time was 4,6,8 and 10 hours. Scanning Electron microscope (SEM), Electron Probe Micro Analyzer (EPMA) and X-ray diffraction (XRD) were applied to analyze the coating layers. The thickness of the carbide layer formed will increase with the longer processing time, which thickness at 4-10 hours is increase from 22.7 to 29.7 micron. The gained thickness tends to be homogeneous. Increasing the TRD process holding time results in a higher hardness of the carbide layerwith hardness at 4, 6, 8 and 10 hours is 2049, 2184, 2175 and 2343 HV. The wear rate at TRD holding time of 4-10 hours with the Ogoshi method was reduced from 5.1 × 10-4 mm3/m to 2.5 × 10-4 mm3/m. Optical microscope observations shows that substrate phases consisting of pearlite and cementite and grains that tend to enlarge with the addition of time. Carbide compounds that are formed are vanadium carbide (V8C7, V6C5, V2C) and chromium carbide (Cr3C2, Cr23C7, Cr3C7). While EDS-Linescan results show complex phase (Fe, V, Cr) xC formed. The research shows that addition of FeCr into FeV powder in TRD process in 980°C with optimum time of 10 hours processing meet the mechanical properties requirement of automotive components.

  2. chemical kinetic study of nitrogen oxides formation in methane flameless combustion

    International Nuclear Information System (INIS)

    Alvarado T, Pedro N; Cadavid S, Francisco; Mondragon, P Fanor; Ruiz, Wilson

    2009-01-01

    The present paper deals with the nitrogen oxides formation in a flameless combustion process characterized for using air highly diluted and preheated at high temperatures. The combustion model used in this study was the one dimensional counterflow methane air diffusion flame. The NOx production rate analysis showed that the thermal and prompt mechanisms are the most important for the formation and consumption of NO under dilution conditions for the oxidant in N 2 and combustion products. These mechanisms are related since the starting reaction for NO formation (N2 molecular dissociation) belongs to the prompt mechanism while the NO formation is reported mainly for the thermal mechanism reactions. On the other hand, the NO - NO 2 equilibrium showed that the reaction rates are comparable to that obtained by the thermal and prompt mechanisms, but its global contribution to NO formation are almost insignificant due to the oxidation reaction with radicals HO 2 .

  3. Sun-drying diminishes the antioxidative potentials of leaves of Eugenia uniflora against formation of thiobarbituric acid reactive substances induced in homogenates of rat brain and liver.

    Science.gov (United States)

    Kade, Ige Joseph; Ibukun, Emmanuel Oluwafemi; Nogueira, Cristina Wayne; da Rocha, Joao Batista Teixeira

    2008-08-01

    Extracts from leaves of Pitanga cherry (Eugenia uniflora) are considered to be effective against many diseases, and are therefore used in popular traditional medicines. In the present study, the antioxidative effect of sun-dried (PCS) and air-dried (PCA) ethanolic extracts of Pitanga cherry leaves were investigated. The antioxidant effects were tested by measuring the ability of both PCS and PCA to inhibit the formation of thiobarbituric acid reactive species (TBARS) induced by prooxidant agents such as iron (II) and sodium nitroprusside (SNP) in rat brain and liver tissues. The results showed that while PCA significantly (P<0.0001) inhibited the formation of TBARS in both liver and brain tissues homogenates, PCS did not. Further investigation reveals that the phenolic content of the PCS was significantly (P<0.0001) lower compared to PCA. Since phenolics in plants largely contributed to the antioxidative potency of plants, we conclude that air-drying should be employed in the preparation of extracts of Pitanga cherry leaves before it is administered empirically as a traditional medicament, and hence this study serves a public awareness to traditional medical practitioners.

  4. Modeling Chemically Reactive Flow of Sutterby Nanofluid by a Rotating Disk in Presence of Heat Generation/Absorption

    Science.gov (United States)

    Hayat, T.; Ahmad, Salman; Ijaz Khan, M.; Alsaedi, A.

    2018-05-01

    In this article we investigate the flow of Sutterby liquid due to rotating stretchable disk. Mass and heat transport are analyzed through Brownian diffusion and thermophoresis. Further the effects of magnetic field, chemical reaction and heat source are also accounted. We employ transformation procedure to obtain a system of nonlinear ODE’s. This system is numerically solved by Built-in-Shooting method. Impacts of different involved parameter on velocity, temperature and concentration are described. Velocity, concentration and temperature gradients are numerically computed. Obtained results show that velocity is reduced through material parameter. Temperature and concentration are enhanced with thermophoresis parameter.

  5. Surface reactivity and hydroxyapatite formation on Ca5MgSi3O12 ceramics in simulated body fluid

    Science.gov (United States)

    Xu, Jian; Wang, Yaorong; Huang, Yanlin; Cheng, Han; Seo, Hyo Jin

    2017-11-01

    In this work, the new calcium-magnesium-silicate Ca5MgSi3O12 ceramic was made via traditional solid-state reaction. The bioactivities were investigated by immerging the as-made ceramics in simulated body fluid (SBF) for different time at body temperature (37 °C). Then the samples were taken to measure X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), X-ray energy-dispersive spectra (EDS), and Fourier transform infrared spectroscopy (FT-IR) measurements. The bone-like hydroxyapatite nanoparticles formation was observed on the ceramic surfaces after the immersion in SBF solutions. Ca5MgSi3O12 ceramics possess the Young's modulus and the bending strength and of 96.3 ± 1.2 GPa and 98.7 ± 2.3 MPa, respectively. The data suggest that Ca5MgSi3O12 ceramics can quickly induce HA new layers after soaking in SBF. Ca5MgSi3O12 ceramics are potential to be used as biomaterials for bone-tissue repair. The cell adherence and proliferation experiments are conducted confirming the reliability of the ceramics as a potential candidate.

  6. Nature and reactivity of organic matter in argillaceous formations: example of the Callovo-Oxfordian of Bure (France)

    International Nuclear Information System (INIS)

    Michels, R.; Elie, M.; Faure, P.; Huault, V.; Martinez, L.; Bartier, D.; Fleck, S.; Hautevelle, Y.

    2004-01-01

    In carbon cycle models, it is admitted that less than 1% of produced organic carbon is transferred to the geological cycle as sedimentary organic matter (Tissot and Welte, 1984). Although, coal or petroleum source rocks are most well known, sedimentary organic matter also occurs in various concentrations throughout many different rock facies. Organic matter is therefore a witness of the record of environmental changes as well as biomass evolution through time. It is also a reliable tracer of diagenetic conditions, from sediment deposition to metamorphism and subsurface alteration. Especially in the case of argillaceous sediments, known for their potential proneness of organic matter, the study of fossil organic matter is able to unravel a large amount of information concerning the geological past (depositional conditions and preservation, paleo-environment, burial, thermal history) as well as the future (effects of induced thermal perturbation, oxidative alteration, biodegradation). We are presenting here data obtained on the Callovo-Oxfordian argillaceous formations of Bure (France), which are the target layers for the installation of a future laboratory. (authors)

  7. BIOCOMPATIBILITY OF MEDICAL DEVICES BASED ON METALS, CAUSES FORMATION OF PATHOLOGICAL REACTIVITY (A REVIEW OF FOREIGN LITERATURE

    Directory of Open Access Journals (Sweden)

    O. M. Rozhnova

    2015-01-01

    Full Text Available The objective of the research is a review of approaches to the evaluation of biocompatibility of medical devices on the basis of metals and alloys, and to find ways of overcoming the low engraftment of implanted structures. Implantation by artificial materials allows us to regain the use of human organs and tissues and to date has no rivals. The advantage of using metals and alloys for implanted structures is their high reliability in operation, long servicelife, and high functionality. The nature of the interaction between the human body and the implant has an impact on resource use and the durability of the structures. Manufacturers of scientific research into medical implants at the present stage are directed to obtain materials that will not adversely affect the human body, and to ensure the maximum survival rate when using them. At the same time, the data presented in the article suggests that attempts to make higher biocompatible material properties tend to reduce the development of new methods for the surface treatment and the chemical composition modulation implants. World literature demonstrates the lack of a systematic approach to the problem of increased sensitivity of patients to different metals and alloys (metal sensitization, resulting in the development of complications such as the development of aseptic inflammation and infectious complications of unstable structures, and loss of functionality. Consequently, there is a need to search for ways to improve the biocompatibility of materials used in medicine, based on an assessment of immune defense mechanisms, and the development of algorithms preoperative tactics. 

  8. Metabolism of isoniazid by neutrophil myeloperoxidase leads to isoniazid-NAD(+) adduct formation: A comparison of the reactivity of isoniazid with its known human metabolites.

    Science.gov (United States)

    Khan, Saifur R; Morgan, Andrew G M; Michail, Karim; Srivastava, Nutan; Whittal, Randy M; Aljuhani, Naif; Siraki, Arno G

    2016-04-15

    The formation of isonicotinyl-nicotinamide adenine dinucleotide (INH-NAD(+)) via the mycobacterial catalase-peroxidase enzyme, KatG, has been described as the major component of the mode of action of isoniazid (INH). However, there are numerous human peroxidases that may catalyze this reaction. The role of neutrophil myeloperoxidase (MPO) in INH-NAD(+) adduct formation has never been explored; this is important, as neutrophils are recruited at the site of tuberculosis infection (granuloma) through infected macrophages' cell death signals. In our studies, we showed that neutrophil MPO is capable of INH metabolism using electron paramagnetic resonance (EPR) spin-trapping and UV-Vis spectroscopy. MPO or activated human neutrophils (by phorbol myristate acetate) catalyzed the oxidation of INH and formed several free radical intermediates; the inclusion of superoxide dismutase revealed a carbon-centered radical which is considered to be the reactive metabolite that binds with NAD(+). Other human metabolites, including N-acetyl-INH, N-acetylhydrazine, and hydrazine did not show formation of carbon-centered radicals, and either produced no detectable free radicals, N-centered free radicals, or superoxide, respectively. A comparison of these free radical products indicated that only the carbon-centered radical from INH is reducing in nature, based on UV-Vis measurement of nitroblue tetrazolium reduction. Furthermore, only INH oxidation by MPO led to a new product (λmax=326nm) in the presence of NAD(+). This adduct was confirmed to be isonicotinyl-NAD(+) using LC-MS analysis where the intact adduct was detected (m/z=769). The findings of this study suggest that neutrophil MPO may also play a role in INH pharmacological activity. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. An integrated fluid-chemical model toward modeling the formation of intra-luminal thrombus in abdominal aortic aneurysms.

    Science.gov (United States)

    Biasetti, Jacopo; Spazzini, Pier Giorgio; Swedenborg, Jesper; Gasser, T Christian

    2012-01-01

    Abdominal Aortic Aneurysms (AAAs) are frequently characterized by the presence of an Intra-Luminal Thrombus (ILT) known to influence their evolution biochemically and biomechanically. The ILT progression mechanism is still unclear and little is known regarding the impact of the chemical species transported by blood flow on this mechanism. Chemical agonists and antagonists of platelets activation, aggregation, and adhesion and the proteins involved in the coagulation cascade (CC) may play an important role in ILT development. Starting from this assumption, the evolution of chemical species involved in the CC, their relation to coherent vortical structures (VSs) and their possible effect on ILT evolution have been studied. To this end a fluid-chemical model that simulates the CC through a series of convection-diffusion-reaction (CDR) equations has been developed. The model involves plasma-phase and surface-bound enzymes and zymogens, and includes both plasma-phase and membrane-phase reactions. Blood is modeled as a non-Newtonian incompressible fluid. VSs convect thrombin in the domain and lead to the high concentration observed in the distal portion of the AAA. This finding is in line with the clinical observations showing that the thickest ILT is usually seen in the distal AAA region. The proposed model, due to its ability to couple the fluid and chemical domains, provides an integrated mechanochemical picture that potentially could help unveil mechanisms of ILT formation and development.

  10. Theoretical study of coupling mechanisms between oxygen diffusion, chemical reaction, mechanical stresses in a solid-gas reactive system

    International Nuclear Information System (INIS)

    Creton, N.; Optasanu, V.; Montesin, T.; Garruchet, S.

    2008-01-01

    This paper offers a study of oxygen dissolution into a solid, and its consequences on the mechanical behaviour of the material. In fact, mechanical strains strongly influence the oxidation processes and may be, in some materials, responsible for cracking. To realize this study, mechanical considerations are introduced into the classical diffusion laws. Simulations were made for the particular case of uranium dioxide, which undergoes the chemical fragmentation. According to our simulations, the hypothesis of a compression stress field into the oxidised UO 2 compound near the internal interface is consistent with some oxidation mechanisms of oxidation experimentally observed. More generally, this work will be extended to the simulation to an oxide layer growth on a metallic substrate. (authors)

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

    Directory of Open Access Journals (Sweden)

    Khalid Imran

    2009-11-01

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

  12. The pro-atherogenic effects of macrophages are reduced upon formation of a complex between C-reactive protein and lysophosphatidylcholine

    Directory of Open Access Journals (Sweden)

    Chang Mi-Kyung

    2012-10-01

    Full Text Available Abstract Rationale C-reactive protein (CRP and lysophosphatidylcholine (LPC are phosphorylcholine-(PC-containing oxidized phospholipids (oxPLs found in oxidized LDL (oxLDL, which trigger pro-atherogenic activities of macrophages during the process of atherosclerosis. It has been previously reported that CRP binds to the PC head group of oxLDL in a calcium-dependent manner. The aim of this study was to investigate the importance of binding between CRP and LPC to the pro-atherogenic activities of macrophages. Objectives and findings A chemiluminescent immunoassay and HPLC showed that human recombinant CRP formed a stable complex with LPC in the presence of calcium. The Kd value of the binding of the CRP-LPC complex to the receptors FcγRIA or FcγRIIA was 3–5 fold lower than that of CRP alone. The CRP-LPC complex triggered less potent generation of reactive oxygen species and less activation of the transcription factors AP-1 and NF-kB by human monocyte-derived macrophages in comparison to CRP or LPC alone. However, CRP did not affect activities driven by components of oxLDL lacking PC, such as upregulation of PPRE, ABCA1, CD36 and PPARγ and the enhancement of cholesterol efflux by human macrophages. The presence of CRP inhibited the association of Dil-labelled oxLDL to human macrophages. Conclusions The formation of complexes between CRP and PC-containing oxPLs, such as LPC, suppresses the pro-atherogenic effects of CRP and LPC on macrophages. This effect may in part retard the progression of atherosclerosis.

  13. Enhancement of chemically induced reactive oxygen species production and DNA damage in human SH-SY5Y neuroblastoma cells by 872 MHz radiofrequency radiation

    Energy Technology Data Exchange (ETDEWEB)

    Luukkonen, Jukka [Department of Environmental Science, University of Kuopio, Bioteknia 2, P.O. Box 1627, FI-70211 Kuopio (Finland)], E-mail: Jukka.Luukkonen@uku.fi; Hakulinen, Pasi; Maeki-Paakkanen, Jorma [Department of Environmental Health, National Public Health Institute, P.O. Box 95, FI-70701 Kuopio (Finland); Juutilainen, Jukka; Naarala, Jonne [Department of Environmental Science, University of Kuopio, Bioteknia 2, P.O. Box 1627, FI-70211 Kuopio (Finland)

    2009-03-09

    The objective of the study was to investigate effects of 872 MHz radiofrequency (RF) radiation on intracellular reactive oxygen species (ROS) production and DNA damage at a relatively high SAR value (5 W/kg). The experiments also involved combined exposure to RF radiation and menadione, a chemical inducing intracellular ROS production and DNA damage. The production of ROS was measured using the fluorescent probe dichlorofluorescein and DNA damage was evaluated by the Comet assay. Human SH-SY5Y neuroblastoma cells were exposed to RF radiation for 1 h with or without menadione. Control cultures were sham exposed. Both continuous waves (CW) and a pulsed signal similar to that used in global system for mobile communications (GSM) mobile phones were used. Exposure to the CW RF radiation increased DNA breakage (p < 0.01) in comparison to the cells exposed only to menadione. Comparison of the same groups also showed that ROS level was higher in cells exposed to CW RF radiation at 30 and 60 min after the end of exposure (p < 0.05 and p < 0.01, respectively). No effects of the GSM signal were seen on either ROS production or DNA damage. The results of the present study suggest that 872 MHz CW RF radiation at 5 W/kg might enhance chemically induced ROS production and thus cause secondary DNA damage. However, there is no known mechanism that would explain such effects from CW RF radiation but not from GSM modulated RF radiation at identical SAR.

  14. Enhancement of chemically induced reactive oxygen species production and DNA damage in human SH-SY5Y neuroblastoma cells by 872 MHz radiofrequency radiation

    International Nuclear Information System (INIS)

    Luukkonen, Jukka; Hakulinen, Pasi; Maeki-Paakkanen, Jorma; Juutilainen, Jukka; Naarala, Jonne

    2009-01-01

    The objective of the study was to investigate effects of 872 MHz radiofrequency (RF) radiation on intracellular reactive oxygen species (ROS) production and DNA damage at a relatively high SAR value (5 W/kg). The experiments also involved combined exposure to RF radiation and menadione, a chemical inducing intracellular ROS production and DNA damage. The production of ROS was measured using the fluorescent probe dichlorofluorescein and DNA damage was evaluated by the Comet assay. Human SH-SY5Y neuroblastoma cells were exposed to RF radiation for 1 h with or without menadione. Control cultures were sham exposed. Both continuous waves (CW) and a pulsed signal similar to that used in global system for mobile communications (GSM) mobile phones were used. Exposure to the CW RF radiation increased DNA breakage (p < 0.01) in comparison to the cells exposed only to menadione. Comparison of the same groups also showed that ROS level was higher in cells exposed to CW RF radiation at 30 and 60 min after the end of exposure (p < 0.05 and p < 0.01, respectively). No effects of the GSM signal were seen on either ROS production or DNA damage. The results of the present study suggest that 872 MHz CW RF radiation at 5 W/kg might enhance chemically induced ROS production and thus cause secondary DNA damage. However, there is no known mechanism that would explain such effects from CW RF radiation but not from GSM modulated RF radiation at identical SAR

  15. Quantum chemical and thermodynamic calculations of fulvic and humic copper complexes in reactions of malachite and azurite formation

    International Nuclear Information System (INIS)

    Fomin, Vitaliy N.; Gogol, Daniil B.; Rozhkovoy, Ivan E.; Ponomarev, Dmitriy L.

    2017-01-01

    This article provides a thermodynamic evaluation of the reactions of humic and fulvic acids in the process of malachite and azurite mineralogenesis. Semi-empirical methods AM/1, MNDO, PM3, PM5, PM6 and PM7 were used to compute the heat of formation, enthalpy and entropy for thermodynamic calculations of the reactions performed on the basis of Hess's law. It is shown that methods PM6 and PM7 in the MOPAC software package provide good compliance with experimental and calculated heats of formation for copper complexes and alkaline earth metal complexes with organic acids. It is found that the malachite and azurite formation processes involving humus complexing substances are thermodynamically possible. - Highlights: • Copper and alkali-earth metal complexes with humic and fulvic acids are considered. • Quantum chemical calculation of thermodynamics for the structures was performed. • Semi-empirical methods PM6 and PM7 provide best correlation for the properties. • Parameters of basic copper carbonate formation reactions were obtained by Hess's law. • Processes of malachite and azurite formation from humus complexes are possible.

  16. Chemically mediated group formation in soil-dwelling larvae and pupae of the beetle Trypoxylus dichotomus

    Science.gov (United States)

    Kojima, Wataru; Ishikawa, Yukio; Takanashi, Takuma

    2014-09-01

    Many insects form groups through interactions among individuals, and these are often mediated by chemical, acoustic, or visual cues and signals. In spite of the diversity of soil-dwelling insects, their aggregation behaviour has not been examined as extensively as that of aboveground species. We investigated the aggregation mechanisms of larvae of the Japanese rhinoceros beetle Trypoxylus dichotomus, which live in groups in humus soil. In two-choice laboratory tests, 2nd- and 3rd-instar larvae gathered at conspecific larvae irrespective of the kinship. The ablation of maxillae, which bear chemosensilla, abolished aggregation behaviour. Intact larvae also exhibited aggregation behaviour towards a larval homogenate. These results suggest that larval aggregation is mediated by chemical cues. We also demonstrated that the mature larvae of T. dichotomus built their pupal cells close to a mesh bag containing a conspecific pupal cell, which indicated that larvae utilize chemical cues emanating from these cells to select the pupation site. Thus, the larvae of T. dichotomus may use chemical cues from the conspecifics in two different contexts, i.e. larval aggregation and pupation site selection. Using conspecific cues, larvae may be able to choose suitable locations for foraging or building pupal cells. The results of the present study highlight the importance of chemical information in belowground ecology.

  17. Measurements of total OH reactivity during PROPHET-AMOS 2016

    Science.gov (United States)

    Rickly, P.; Sakowski, J.; Bottorff, B.; Lew, M.; Stevens, P. S.; Sklaveniti, S.; Locoge, N.; Dusanter, S.

    2017-12-01

    As one of the main oxidant in the atmosphere, the hydroxyl radical (OH) initiates the oxidation of volatile organic compounds that can lead to the formation of ozone and secondary organic aerosols. Understanding both the sources and sinks of OH is therefore important to address issues related to air quality and climate change. Measurements of total OH reactivity can provide an important test of our understanding of the OH radical budget. Recent measurements of total reactivity in many environments have been greater than calculated based on the measured concentration of VOCs, suggesting that important OH sinks in these environments are not well characterized. Measurements of total OH reactivity were performed in a forested environment during the PROPHET - AMOS field campaign (Program for Research on Oxidants: PHotochemisty, Emissions, and Transport - Atmospheric Measurements of Oxidants in Summer) using the Comparative Reactivity Method (CRM) and the Total OH Loss Rate Method (TOHLM). The site is characterized by large emissions of isoprene and monoterpenes and low anthropogenic influence. Measurements of total OH reactivity using these two techniques agree to within their respective uncertainties, giving confidence in the measured OH reactivity. In addition, measurements of trace gases (VOCs, NOx, O3) were used to perform a comprehensive apportionment of OH sinks. These measurements are used in a chemical model using the Master Chemical Mechanism to calculate the expected OH reactivity. The results will be compared to previous measurements of total OH reactivity at this site.

  18. Introduction to astrochemistry chemical evolution from interstellar clouds to star and planet formation

    CERN Document Server

    Yamamoto, Satoshi

    2017-01-01

    This important book describes the basic principles of astrochemistry—an interdisciplinary field combining astronomy, physics, and chemistry—with particular emphasis on its physical and chemical background. Chemical processes in diffuse clouds, dense quiescent molecular clouds, star-forming regions, and protoplanetary disks are discussed. A brief introduction to molecular spectroscopy and observational techniques is also presented. These contents provide astronomers with a comprehensive understanding of how interstellar matter is evolved and brought into stars and planets, which is ultimately related to the origin of the solar system. The subject matter will also be understandable and useful for physical chemists who are interested in exotic chemical processes occurring in extreme physical conditions. The book is a valuable resource for all researchers beginning at the graduate level.

  19. Evidence for a chemical clock in oscillatory formation of UiO-66

    Science.gov (United States)

    Goesten, M. G.; de Lange, M. F.; Olivos-Suarez, A. I.; Bavykina, A. V.; Serra-Crespo, P.; Krywka, C.; Bickelhaupt, F. M.; Kapteijn, F.; Gascon, Jorge

    2016-06-01

    Chemical clocks are often used as exciting classroom experiments, where an induction time is followed by rapidly changing colours that expose oscillating concentration patterns. This type of reaction belongs to a class of nonlinear chemical kinetics also linked to chaos, wave propagation and Turing patterns. Despite its vastness in occurrence and applicability, the clock reaction is only well understood for liquid-state processes. Here we report a chemical clock reaction, in which a solidifying entity, metal-organic framework UiO-66, displays oscillations in crystal dimension and number, as shown by X-ray scattering. In rationalizing this result, we introduce a computational approach, the metal-organic molecular orbital methodology, to pinpoint interaction between the tectonic building blocks that construct the metal-organic framework material. In this way, we show that hydrochloric acid plays the role of autocatalyst, bridging separate processes of condensation and crystallization.

  20. Room temperature chemical synthesis of highly oriented PbSe nanotubes based on negative free energy of formation

    Energy Technology Data Exchange (ETDEWEB)

    Sankapal, B.R., E-mail: brsankapal@rediffmail.com [Thin Film and Nano Science Laboratory, Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425 001 (MS) (India); Ladhe, R.D.; Salunkhe, D.B.; Baviskar, P.K. [Thin Film and Nano Science Laboratory, Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425 001 (MS) (India); Gupta, V.; Chand, S. [Organic and Hybrid Solar Cell, Physics of Energy Harvesting Division, Dr. K.S. Krishnan Marg, National Physical Laboratory, New Delhi 110012 (India)

    2011-10-13

    Highlights: > Simple, inexpensive and room temperature chemical synthesis route. > Highly oriented PbSe nanotubes from Cd(OH){sub 2} nanowires through lead hydroxination. > The process was template free without the use of any capping agent. > Reaction kinetics was accomplished due to more negative free energy of formation. > The ion exchange mechanism due to difference in the solubility products. - Abstract: The sacrificial template free chemical synthesis of PbSe nanotubes at room temperature has been performed by lead hydroxination from cadmium hydroxide nanowires. This process was based on the ion exchange reaction to replace Cd{sup 2+} with Pb{sup 2+} ions from hydroxyl group followed by replacement of hydroxyl group with selenium ions. The reaction kinetics was accomplished due to more negative free energy of formation and thus the difference in the solubility products. The formed nanotubes were inclusive of Pb and Se with proper inter-chemical bonds with preferred orientations having diameter in tens of nanometer. These nanotubes can have future applications in electronic, optoelectronics and photovoltaic's as well.

  1. Room temperature chemical synthesis of highly oriented PbSe nanotubes based on negative free energy of formation

    International Nuclear Information System (INIS)

    Sankapal, B.R.; Ladhe, R.D.; Salunkhe, D.B.; Baviskar, P.K.; Gupta, V.; Chand, S.

    2011-01-01

    Highlights: → Simple, inexpensive and room temperature chemical synthesis route. → Highly oriented PbSe nanotubes from Cd(OH) 2 nanowires through lead hydroxination. → The process was template free without the use of any capping agent. → Reaction kinetics was accomplished due to more negative free energy of formation. → The ion exchange mechanism due to difference in the solubility products. - Abstract: The sacrificial template free chemical synthesis of PbSe nanotubes at room temperature has been performed by lead hydroxination from cadmium hydroxide nanowires. This process was based on the ion exchange reaction to replace Cd 2+ with Pb 2+ ions from hydroxyl group followed by replacement of hydroxyl group with selenium ions. The reaction kinetics was accomplished due to more negative free energy of formation and thus the difference in the solubility products. The formed nanotubes were inclusive of Pb and Se with proper inter-chemical bonds with preferred orientations having diameter in tens of nanometer. These nanotubes can have future applications in electronic, optoelectronics and photovoltaic's as well.

  2. Chemically reactive and naturally convective high speed MHD fluid flow through an oscillatory vertical porous plate with heat and radiation absorption effect

    Directory of Open Access Journals (Sweden)

    S.M. Arifuzzaman

    2018-04-01

    Full Text Available This paper concerns with the modelling of an unsteady natural convective and higher order chemically reactive magnetohydrodynamics (MHD fluid flow with the effect of heat and radiation absorption. The flow is generated through a vertical oscillating porous plate. Boundary layer approximations is carried out to establish a flow model which represents the time dependent momentum, energy and diffusion balance equations. Before being solved numerically, the governing partial differential equations (PDEs were transformed into a set of nonlinear ordinary differential equation (ODEs by using non-similar technique. A very efficient numerical approach solves the obtained nonlinear coupled ODEs so called Explicit Finite Difference Method (EFDM. An algorithm is implemented in Compaq Visual Fortran 6.6a as a solving tool. In addition, the stability and convergence analysis (SCA is examined and shown explicitly. The advantages of SCA is its optimizes the accuracy of system parameters such as Prandtl number (Pr and Schmidt number (Sc.The velocity, temperature and concentration fields in the boundary layer region are studied in detail and the outcomes are shown in graphically with the influence of various pertinent parameters such as Grashof number (Gr, modified Grashof number (Gr, magnetic parameter (M, Darcy number (Da,Prandtl number (Pr, Schmidt number (Sc, radiation (R, heat sink (Q,radiation absorption (Q1, Eckert number (Ec, Dufour number (Du,Soret number (Sr, Schmidt number (Sc, reaction index (P and chemical reaction (Kr. Furthermore, the effect of skin friction coefficient (Cf, Nusselt number (Nu and Sherwood number (Sh are also examined graphically. Keywords: MHD, Oscillating porous plate, Radiation absorption, High order chemical reaction, EFDM

  3. Radiation-chemical yields of molecular hydrogen formation in cyclohexane based alcohols

    International Nuclear Information System (INIS)

    Val'ter, A.I.; Kovalev, G.V.

    1988-01-01

    Molecular hydrogen radiation-chemical yields in γ-irradiated cyclohexanol, 1.2-cis- and 1.2-trans-cyclohexandiols and inositol are determined within the general problem frameworks of radiolysis mechanism for cyclohexanering-base alcohols. Irradiation was conducted at 77 and 293 K, dose rate - 4 Gy/s. Hydrogen concentration in all irradiated alcohols depends linearly on the dose. Radiation-chemical yields of H 2 and of stabilized radicals, as well, in the irradiated crystalline alcohols are analyzed depending on the irradiation temperature, alcohol molecular structure

  4. Fixation of some chemically modified reactive dye during gamma irradiation of cotton fabrics in presence of vinyl and acrylic monomers

    International Nuclear Information System (INIS)

    Zohdy, M.H.; El-Naggar, A.M.; Abdallah, W.A.

    1999-01-01

    The radiation grafting of vinyl sulfone dye having an activated double bond in presence of styrene monomer or its mixtures with ethyl acrylate onto cotton fabric has been investigated. The chemical reaction of the vinyl sulfone form with peroxy radicals on cotton fabric through covalent bonding is tested by extracting the dyed samples in 50% aqueous DMF solution. It was found that the presence of styene monomer in the dyeing solution is essential for the reaction or grafting of the vinyl sulfone dye. However, when a constant styrene concentration of 5% was used in the dye bath, the color strength expressed as K/S was found to increase by increasing the dye concentration. The results showed that the color strength obtained in case of using 10% ethyl acrylate is much lower than in the case of using the same concentration of styrene monomer. A solvent composition of equal ratios of methanol and water has been proven to be suitable to produce the highest improvement in the color strength. The irradiation dose was found to play an important role in initiating the reaction of the vinyl sulfone dye

  5. Hybrid graphene oxide/DAB-Am-16 dendrimer: Preparation, characterization chemical reactivity and their electrocatalytic detection of L-Dopamine

    Science.gov (United States)

    Do Carmo, Devaney Ribeiro; Fernandes, Daniela Silvestrini

    2017-09-01

    Graphene oxide (GO) was chemically modified with a poly(propylene)imine Generation 3.0 dendrimer (DAB-Am-16). The characterization, structure and properties of hybrid graphene oxide/DAB-Am-16 dendrimer was studied by Raman spectroscopy, Fourier-Transforming Infrared Spectroscopy (FT-IR), X-Ray Photoelectron Spectroscopic (XPS), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Thermogravimetric analysis. After functionalized the hybrid material (GOD) can interact with copper and subsequently with hexacyanoferrate (III) ions (GODHCu). The GODHCu incorporated into a graphite paste electrode (20% w/w) was applied to an electrocatalytic detection of neurotransmitter L-dopamine using differential pulse voltammetry. The analytical curve showed a linear response in the concentration range from 1.0 × 10-7 to 1.0 × 10-5 mol L-1 with a corresponding equation Y(A) = 1.706 × 10-5 + 0.862 [L-dopamine] and a correlation coefficient r2 = 0.998. The detection limit was 6.36 × 10-7 mol L-1 with a relative standard deviation of ±4% (n = 3) and an amperometric sensitivity of 0.862 A/mol L-1.

  6. A numerical analysis for non-linear radiation in MHD flow around a cylindrical surface with chemically reactive species

    Directory of Open Access Journals (Sweden)

    Junaid Ahmad Khan

    2018-03-01

    Full Text Available Boundary layer flow around a stretchable rough cylinder is modeled by taking into account boundary slip and transverse magnetic field effects. The main concern is to resolve heat/mass transfer problem considering non-linear radiative heat transfer and temperature/concentration jump aspects. Using conventional similarity approach, the equations of motion and heat transfer are converted into a boundary value problem whose solution is computed by shooting method for broad range of slip coefficients. The proposed numerical scheme appears to improve as the strengths of magnetic field and slip coefficients are enhanced. Axial velocity and temperature are considerably influenced by a parameter M which is inversely proportional to the radius of cylinder. A significant change in temperature profile is depicted for growing wall to ambient temperature ratio. Relevant physical quantities such as wall shear stress, local Nusselt number and local Sherwood number are elucidated in detail. Keywords: Stretchable boundary, Thermal radiation, Chemical reaction, Mathematical modeling, Non-linear differential system, Mass transfer

  7. Chemical dynamics between wells across a time-dependent barrier: Self-similarity in the Lagrangian descriptor and reactive basins.

    Science.gov (United States)

    Junginger, Andrej; Duvenbeck, Lennart; Feldmaier, Matthias; Main, Jörg; Wunner, Günter; Hernandez, Rigoberto

    2017-08-14

    In chemical or physical reaction dynamics, it is essential to distinguish precisely between reactants and products for all times. This task is especially demanding in time-dependent or driven systems because therein the dividing surface (DS) between these states often exhibits a nontrivial time-dependence. The so-called transition state (TS) trajectory has been seen to define a DS which is free of recrossings in a large number of one-dimensional reactions across time-dependent barriers and thus, allows one to determine exact reaction rates. A fundamental challenge to applying this method is the construction of the TS trajectory itself. The minimization of Lagrangian descriptors (LDs) provides a general and powerful scheme to obtain that trajectory even when perturbation theory fails. Both approaches encounter possible breakdowns when the overall potential is bounded, admitting the possibility of returns to the barrier long after the trajectories have reached the product or reactant wells. Such global dynamics cannot be captured by perturbation theory. Meanwhile, in the LD-DS approach, it leads to the emergence of additional local minima which make it difficult to extract the optimal branch associated with the desired TS trajectory. In this work, we illustrate this behavior for a time-dependent double-well potential revealing a self-similar structure of the LD, and we demonstrate how the reflections and side-minima can be addressed by an appropriate modification of the LD associated with the direct rate across the barrier.

  8. Evolution of the chemical bonding nature and electrode activity of indium selenide upon the composite formation with graphene nanosheets

    International Nuclear Information System (INIS)

    Oh, Seung Mi; Lee, Eunsil; Adpakpang, Kanyaporn; Patil, Sharad B.; Park, Mi Jin; Lim, Young Soo; Lee, Kyu Hyoung; Kim, Jong-Young; Hwang, Seong-Ju

    2015-01-01

    Graphical abstract: Display Omitted -- Highlights: • In 4 Se 2.85 @graphene nanocomposite is easily prepared by high energy mechanical milling process. • The bond covalency of In 4 Se 2.85 is notably changed upon the composite formation with graphene. • In 4 Se 2.85 @graphene nanocomposite shows promising anode performance for lithium ion battery. -- Abstract: Evolution of the chemical bonding nature and electrochemical activity of indium selenide upon the composite formation with carbon species is systematically investigated. Nanocomposites of In 4 Se 2.85 @graphene and In 4 Se 2.85 @carbon-black are synthesized via a solid state reaction between In and Se elements, and the following high energy mechanical milling of In 4 Se 2.85 with graphene and carbon-black, respectively. The high energy mechanical milling (HEMM) of In 4 Se 2.85 with carbon species gives rise to a decrease of particle size with a significant depression of the crystallinity of In 4 Se 2.85 phase. In contrast to the composite formation with carbon-black, that with graphene induces a notable decrease of (In−Se) bond covalency, underscoring significant chemical interaction between graphene and In 4 Se 2.85 . Both the nanocomposites of In 4 Se 2.85 @graphene and In 4 Se 2.85 @carbon-black show much better anode performance for lithium ion batteries with larger discharge capacity and better cyclability than does the pristine In 4 Se 2.85 material, indicating the beneficial effect of composite formation on the electrochemical activity of indium selenide. Between the present nanocomposites, the electrode performance of the In 4 Se 2.85 @graphene nanocomposite is superior to that of the In 4 Se 2.85 @carbon-black nanocomposite, which is attributable to the weakening of (In−Se) bonds upon the composite formation with graphene as well as to the better mixing between In 4 Se 2.85 and graphene. The present study clearly demonstrates that the composite formation with graphene has strong influence

  9. Integration of On-Column Chemical Reactions in Protein Characterization by Liquid Chromatography/Mass Spectrometry: Cross-Path Reactive Chromatography.

    Science.gov (United States)

    Pawlowski, Jake W; Carrick, Ian; Kaltashov, Igor A

    2018-01-16

    Profiling of complex proteins by means of mass spectrometry (MS) frequently requires that certain chemical modifications of their covalent structure (e.g., reduction of disulfide bonds), be carried out prior to the MS or MS/MS analysis. Traditionally, these chemical reactions take place in the off-line mode to allow the excess reagents (the majority of which interfere with the MS measurements and degrade the analytical signal) to be removed from the protein solution prior to MS measurements. In addition to a significant increase in the analysis time, chemical reactions may result in a partial or full loss of the protein if the modifications adversely affect its stability, e.g,, making it prone to aggregation. In this work we present a new approach to solving this problem by carrying out the chemical reactions online using the reactive chromatography scheme on a size exclusion chromatography (SEC) platform with MS detection. This is achieved by using a cross-path reaction scheme, i.e., by delaying the protein injection onto the SEC column (with respect to the injection of the reagent plug containing a disulfide-reducing agent), which allows the chemical reactions to be carried out inside the column for a limited (and precisely controlled) period of time, while the two plugs overlap inside the column. The reduced protein elutes separately from the unconsumed reagents, allowing the signal suppression in ESI to be avoided and enabling sensitive MS detection. The new method is used to measure fucosylation levels of a plasma protein haptoglobin at the whole protein level following online reduction of disulfide-linked tetrameric species to monomeric units. The feasibility of top-down fragmentation of disulfide-containing proteins is also demonstrated using β 2 -microglobulin and a monoclonal antibody (mAb). The new online technique is both robust and versatile, as the cross-path scheme can be readily expanded to include multiple reactions in a single experiment (as

  10. Chemical grafting of the superhydrophobic surface on copper with hierarchical microstructure and its formation mechanism

    Science.gov (United States)

    Cai, Junyan; Wang, Shuhui; Zhang, Junhong; Liu, Yang; Hang, Tao; Ling, Huiqin; Li, Ming

    2018-04-01

    In this paper, a superhydrophobic surface with hierarchical structure was fabricated by chemical deposition of Cu micro-cones array, followed by chemical grafting of poly(methyl methacrylate) (PMMA). Water contact measurements give contact angle of 131.0° on these surfaces after PMMA grafting of 2 min and 165.2° after 6 min. The superhydrophobicity results from two factors: (1) the hierarchical structure due to Cu micro-cones array and the second level structure caused by intergranular corrosion during grafting of PMMA (confirmed by the scanning electron microscopy) and (2) the chemical modification of a low surface energy PMMA layer (confirmed by Fourier transform infrared spectrometer and X-ray photoelectron spectroscopy). In the chemical grafting process, the spontaneous reduction of nitrobenzene diazonium (NBD) tetrafluoroborate not only causes the corrosion of the Cu surface that leads to a hierarchical structure, but also initiates the polymerization of methyl methacrylate (MMA) monomers and thus the low free energy surface. Such a robust approach to fabricate the hierarchical structured surface with superhydrophobicity is expected to have practical application in anti-corrosion industry.

  11. A CHEMICAL VIEW OF PROTOSTELLAR-DISK FORMATION IN L1527

    International Nuclear Information System (INIS)

    Sakai, Nami; Oya, Yoko; Watanabe, Yoshimasa; Yamamoto, Satoshi; Sakai, Takeshi; Hirota, Tomoya; Ceccarelli, Cecilia; Kahane, Claudine; Lopez-Sepulcre, Ana; Lefloch, Bertrand; Vastel, Charlotte; Bottinelli, Sandrine; Caux, Emmanuel; Coutens, Audrey; Aikawa, Yuri; Takakuwa, Shigehisa; Yen, Hsi-Wei; Ohashi, Nagayoshi

    2014-01-01

    Subarcsecond images of the rotational line emissions of CCH, CS, H 2 CO, and CH 3 OH have been obtained toward the low-mass protostar IRAS 04368+2557 in L1527 as one of the early science projects of the Atacama Large Millimeter/submillimeter Array. The intensity distributions of CCH and CS show a double-peaked structure along the edge-on envelope with a dip toward the protostar position, whereas those of H 2 CO and CH 3 OH are centrally peaked. By analyzing the position-velocity diagrams along the envelope, CCH and CS are found to reside mainly in the envelope, where the gas is infalling with conservation of its angular momentum. They are almost absent inward of the centrifugal barrier (a half of the centrifugal radius). Although H 2 CO exists in the infalling rotating envelope, it also resides in the disk component inside the centrifugal barrier to some extent. On the other hand, CH 3 OH seems to exist around the centrifugal barrier and in the disk component. Hence, the drastic chemical change occurs at the centrifugal barrier. A discontinuous infalling motion as well as the gas-grain interaction would be responsible for the chemical change. This result will put an important constraint on initial chemical compositions for chemical evolution of protostellar disks

  12. Host-guest complex of N-(2-chloroethyl), N-nitroso, N‧, N‧ -dicyclohexylsulfamid with β-cyclodextrin: Fluorescence, QTAIM analysis and structure-chemical reactivity

    Science.gov (United States)

    Bensouilah, Nadjia; Fisli, Hassina; Bensouilah, Hamza; Zaater, Sihem; Abdaoui, Mohamed; Boutemeur-Kheddis, Baya

    2017-10-01

    In this work, the inclusion complex of DCY/CENS: N-(2-chloroethyl), N-nitroso, N‧, N‧-dicyclohexylsulfamid and β-cyclodextrin (β-CD) is investigated using the fluorescence spectroscopy, PM3, ONIOM2 and DFT methods. The experimental part reveals that DCY/CENS forms a 1:1 stoichiometric ratio inclusion complex with β-CD. The constant of stability is evaluated using the Benesi-Hildebrand equation. The results of the theoretical optimization showed that the lipophilic fraction of molecule (cyclohexyl group) is inside of β-CD. Accordingly, the Nitroso-Chloroethyl moiety is situated outside the cavity of the macromolecule host. The favorable structure of the optimized complex indicates the existence of weak intermolecular hydrogen bonds and the most important van der Waals (vdW) interactions which are studied on the basis of Natural Bonding Orbital (NBO) analysis. The NBO is employed to compute the electronic donor-acceptor exchanges between drug and β-CD. Furthermore, a detailed topological charge density analysis based on the quantum theory of atoms in molecules (QTAIM), has been accomplished on the most favorable complex using B3LYP/6-31G(d) method. The presence of stabilizing intermolecular hydrogen bonds and van der Waals interactions in the most favorable complex is predicted. Also, the energies of these interactions are estimated with Espinosa's formula. The findings of this investigation reveal that the correlation between the structural parameters and the electronic density is good. Finally, and based on DFT calculations, the reactivity of the interesting molecule in free state was studied and compared with that in the complexed state using chemical potential, global hardness, global softness, electronegativity, electrophilicity and local reactivity descriptors.

  13. Assessing the occurrence of the dibromide radical (Br₂⁻•) in natural waters: measures of triplet-sensitised formation, reactivity, and modelling.

    Science.gov (United States)

    De Laurentiis, Elisa; Minella, Marco; Maurino, Valter; Minero, Claudio; Mailhot, Gilles; Sarakha, Mohamed; Brigante, Marcello; Vione, Davide

    2012-11-15

    The triplet state of anthraquinone-2-sulphonate (AQ2S) is able to oxidise bromide to Br(•)/Br(2)(-•), with rate constant (2-4)⋅10(9)M(-1)s(-1) that depends on the pH. Similar processes are expected to take place between bromide and the triplet states of naturally occurring chromophoric dissolved organic matter ((3)CDOM*). The brominating agent Br(2)(-•) could thus be formed in natural waters upon oxidation of bromide by both (•)OH and (3)CDOM*. Br(2)(-•) would be consumed by disproportionation into bromide and bromine, as well as upon reaction with nitrite and most notably with dissolved organic matter (DOM). By using the laser flash photolysis technique, and phenol as model organic molecule, a second-order reaction rate constant of ~3⋅10(2)L(mg C)(-1)s(-1) was measured between Br(2)(-•) and DOM. It was thus possible to model the formation and reactivity of Br(2)(-•) in natural waters, assessing the steady-state [Br(2)(-•)]≈10(-13)-10(-12)M. It is concluded that bromide oxidation by (3)CDOM* would be significant compared to oxidation by (•)OH. The (3)CDOM*-mediated process would prevail in DOM-rich and bromide-rich environments, the latter because elevated bromide would completely scavenge (•)OH. Under such conditions, (•)OH-assisted formation of Br(2)(-•) would be limited by the formation rate of the hydroxyl radical. In contrast, the formation rate of (3)CDOM* is much higher compared to that of (•)OH in most surface waters and would provide a large (3)CDOM* reservoir for bromide to react with. A further issue is that nitrite oxidation by Br(2)(-•) could be an important source of the nitrating agent (•)NO(2) in bromide-rich, nitrite-rich and DOM-poor environments. Such a process could possibly account for significant aromatic photonitration observed in irradiated seawater and in sunlit brackish lagoons. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Assessing the occurrence of the dibromide radical (Br2−·) in natural waters: Measures of triplet-sensitised formation, reactivity, and modelling

    International Nuclear Information System (INIS)

    De Laurentiis, Elisa; Minella, Marco; Maurino, Valter; Minero, Claudio; Mailhot, Gilles; Sarakha, Mohamed; Brigante, Marcello; Vione, Davide

    2012-01-01

    The triplet state of anthraquinone-2-sulphonate (AQ2S) is able to oxidise bromide to Br · /Br 2 −· , with rate constant (2–4) ⋅ 10 9 M −1 s −1 that depends on the pH. Similar processes are expected to take place between bromide and the triplet states of naturally occurring chromophoric dissolved organic matter ( 3 CDOM*). The brominating agent Br 2 −· could thus be formed in natural waters upon oxidation of bromide by both · OH and 3 CDOM*. Br 2 −· would be consumed by disproportionation into bromide and bromine, as well as upon reaction with nitrite and most notably with dissolved organic matter (DOM). By using the laser flash photolysis technique, and phenol as model organic molecule, a second-order reaction rate constant of ∼ 3 ⋅ 10 2 L (mg C) −1 s −1 was measured between Br 2 −· and DOM. It was thus possible to model the formation and reactivity of Br 2 −· in natural waters, assessing the steady-state [Br 2 −· ] ≈ 10 −13 –10 −12 M. It is concluded that bromide oxidation by 3 CDOM* would be significant compared to oxidation by · OH. The 3 CDOM*-mediated process would prevail in DOM-rich and bromide-rich environments, the latter because elevated bromide would completely scavenge · OH. Under such conditions, · OH-assisted formation of Br 2 −· would be limited by the formation rate of the hydroxyl radical. In contrast, the formation rate of 3 CDOM* is much higher compared to that of · OH in most surface waters and would provide a large 3 CDOM* reservoir for bromide to react with. A further issue is that nitrite oxidation by Br 2 −· could be an important source of the nitrating agent · NO 2 in bromide-rich, nitrite-rich and DOM-poor environments. Such a process could possibly account for significant aromatic photonitration observed in irradiated seawater and in sunlit brackish lagoons. Highlights: ► The triplet state of anthraquinone-2-sulphonate oxidises bromide to Br 2 −· . ► Dissolved organic matter is

  15. Chemical Dynamics and Critical Phenomena: Electrical Conductivity and Reactivity of Benzyl Bromide in Triethylamine+Water Near its Consolute Point

    Science.gov (United States)

    Specker, Christopher D.; Ellis, Joel M.; Baird, James K.

    2007-06-01

    The binary liquid mixture of triethylamine+water has a lower consolute point at a critical composition of 32.27mass% triethylamine. Starting at a temperature within the one-phase region, the electrical conductivity of a sample of this mixture was measured and found to increase smoothly with increasing temperature before falling sharply at 291.24K (18.09°C). Since opalescence was visible at this temperature, it was identified with the critical solution temperature of the binary mixture. A solution of 90 μL of benzyl bromide dissolved in 90mL of 32.27mass% triethylamine+water was prepared, and the resulting Menschutkin reaction between benzyl bromide and triethylamine was allowed to come to equilibrium. The electrical conductivity of this equilibrium mixture was measured in the one-phase region and was found to increase smoothly with increasing temperature before rising sharply at 291.55K (18.40°C). This temperature was identified as the critical temperature of the ternary. The rate of approach of the ternary mixture to chemical equilibrium was also measured and shown to be governed by a first-order rate law. The temperature dependence of the rate coefficient followed the Arrhenius equation up to a temperature of about 290.74K (17.59°C). Above this temperature, the rate coefficient fell by as much as 22% below the value predicted by extrapolation of the Arrhenius equation. This suppression in the rate reaction in the vicinity of the critical temperature can be interpreted as evidence for the existence of critical slowing down.

  16. Chemical properties and reactive oxygen and nitrogen species quenching activities of dry sugar-amino acid maillard reaction mixtures exposed to baking temperatures.

    Science.gov (United States)

    Chen, Xiu-Min; Liang, Ningjian; Kitts, David D

    2015-10-01

    Maillard reaction products (MRPs) derived from 10 different, dry sugar-amino acid reaction model systems were examined for changes in color index (E), sugar loss, and formation of α-dicarbonyl compounds; the changes were correlated with relative activities to quench both reactive oxygen (ROS) and reactive nitrogen (RNS) species. Reducing sugars, xylose, ribose, fructose, glucose, and non-reducing sucrose were reacted with glycine (Xyl-Gly, Rib-Gly, Fru-Gly, Glc-Gly, and Suc-Gly), or lysine (Xyl-Lys, Rib-Lys, Fru-Lys, Glc-Lys, and Suc-Lys), respectively, at temperatures of 150°C and 180°C for time periods ranging from 5 to 60min. ROS quenching capacity was negatively correlated with color index (E) (r=-0.604, P<0.001), and positively correlated with sugar loss (r=0.567, P<0.001). MRPs also exhibited activity to quench RNS as assessed by nitric oxide (NO) inhibition in differentiated Caco-2 cells that were induced with interferon-γ (IFN-γ) and phorbol ester (PMA) cocktail. We also showed a correlation between RNS and color index, sugar loss, and ROS quenching activities for MR mixtures that were heated for a short time (e.g. 10min) at 150°C. MRP quenching of ROS was largely influenced by sugar type, whereas, RNS quenching was dependent more so on the interaction between reactants and reaction conditions used to generate MRPs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. On-Road Chemical Transformation as an Important Mechanism of NO2 Formation

    Science.gov (United States)

    Nitrogen dioxide (NO2) not only is linked with a number of adverse effects on the respiratory system, but also contributes to the formation of ground-level ozone (O3) and fine particulate matter (PM2.5) pollution. NO2 levels near major roads have been monitored as part of the one...

  18. Investigation of Chemical Kinetics on Soot Formation Event of n-Heptane Spray Combustion

    DEFF Research Database (Denmark)

    Pang, Kar Mun; Jangi, Mehdi; Bai, Xue-Song

    2014-01-01

    . Numerical computation is performed using OpenFOAM and chemistry coordinate mapping (CCM) approach is used to expedite the calculation. Three n-heptane kinetic mechanisms with different chemistry sizes and comprehensiveness in oxidation pathways and soot precursor formation are adopted. The three examined...

  19. Quantitative NMR Approach to Optimize the Formation of Chemical Building Blocks from Abundant Carbohydrates

    DEFF Research Database (Denmark)

    Elliot, Samuel Gilbert; Tolborg, Søren; Sádaba, Irantzu

    2017-01-01

    -containing catalysts such as Sn-Beta. These compounds are potential building blocks for polyesters with additional olefin and alcohol functionalities. We employ an NMR approach to identify, quantify and optimize the formation these building blocks in the chemocatalytic transformation of abundant carbohydrates by Sn...

  20. Effects of de-icing chemicals sodium chloride and potassium formate on cadmium solubility in a coarse mineral soil

    Energy Technology Data Exchange (ETDEWEB)

    Rasa, Kimmo [Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 27, FIN-00014, University of Helsinki (Finland)]. E-mail: kimmo.rasa@helsinki.fi; Peltovuori, Tommi [Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 27, FIN-00014, University of Helsinki (Finland); Hartikainen, Helinae [Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 27, FIN-00014, University of Helsinki (Finland)

    2006-08-01

    Excessive use of sodium chloride (NaCl) as de-icing chemical causes environmental problems, such as elevated chloride concentrations in groundwater. On vulnerable sites, this can be avoided by using alternative organic de-icing chemicals, such as potassium formate (KHCOO). The environmental impacts of KCHOO are, however, not well known. This study reports the potential effects of NaCl and KCHOO on mechanisms controlling the mobility of cadmium (Cd) in roadside soils as a result of vehicular traffic. Changes in the solubility of Cd in a coarse mineral soil treated with these two de-icing chemicals were studied in a 50-day incubation experiment under four different moisture and temperature combinations and an initial soil Cd concentration of 3 mg kg{sup -1}. After incubation, the distribution of soil Cd into different fractions was analyzed using a sequential extraction method. Soil pH and soil redox potential were recorded and the occurrence of Cd-Cl complexes in the soil was estimated using published stability constants. During incubation, KCHOO lowered the soil redox potential, but this was not accompanied by a decrease in the sorption capacity of oxides and the release of oxide-bound Cd into soil solution. On the other hand, elevated pH (from 4.3 to 6.7-8.5) in the formate treatments increased the sorption of Cd onto the oxide surfaces (up to 80% of total sorbed Cd). In the NaCl treatments, cation competition and formation of Cd-Cl complexes increased the water-soluble Cd fraction. Consequently, the amount of bioavailable