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Sample records for reaction pathways leading

  1. A mechanistic study on the reaction pathways leading to benzene and naphthalene in cellulose vapor phase cracking

    International Nuclear Information System (INIS)

    Norinaga, Koyo; Yang, Huamei; Tanaka, Ryota; Appari, Srinivas; Iwanaga, Keita; Takashima, Yuka; Kudo, Shinji; Shoji, Tetsuya; Hayashi, Jun-ichiro

    2014-01-01

    The reaction pathways leading to aromatic hydrocarbons such as benzene and naphthalene in gas-phase reactions of multi-component mixtures derived from cellulose fast pyrolysis were studied both experimentally and numerically. A two-stage tubular reactor was used for evaluating the reaction kinetics of secondary vapor phase cracking of the nascent pyrolysates at temperature ranging from 400 to 900 °C, residence time from 0.2 to 4.3 s, and at 241 kPa. The products of alkyne and diene were identified from the primary pyrolysis of cellulose even at low temperature range 500–600 °C. These products include acetylene, propyne, propadiene, vinylacetylene, and cyclopentadiene. Experiments were also numerically validated by a detailed chemical kinetic model consisting of more than 8000 elementary step-like reactions with over 500 chemical species. Acceptable capabilities of the kinetic model in predicting concentration profiles of the products enabled us to assess reaction pathways leading to benzene and naphthalene via the alkyne and diene from primary pyrolysates of cellulose. C 3 alkyne and diene are primary precursors of benzene at 650 °C, while combination of ethylene and vinylacetylene produces benzene dominantly at 850 °C. Cyclopentadiene is a prominent precursor of naphthalene. Combination of acetylene with propyne or allyl radical leads to the formation of cyclopentadiene. Furan and acrolein are likely important alkyne precursors in cellulose pyrolysis at low temperature, whereas dehydrogenations of olefins are major route to alkyne at high temperatures. - Highlights: • Analytical pyrolysis experiments provided data for kinetic modeling. • Detailed chemical kinetic model was used and evaluated. • Alkyne and diene were important intermediates for aromatic hydrocarbon formation. • Reaction pathways leading to aromatic hydrocarbons were proposed

  2. Computer-assisted study on the reaction between pyruvate and ylide in the pathway leading to lactyl-ThDP.

    Science.gov (United States)

    Alvarado, Omar; Jaña, Gonzalo; Delgado, Eduardo J

    2012-08-01

    In this study the formation of the lactyl-thiamin diphosphate intermediate (L-ThDP) is addressed using density functional theory calculations at X3LYP/6-31++G(d,p) level of theory. The study includes potential energy surface scans, transition state search, and intrinsic reaction coordinate calculations. Reactivity is analyzed in terms of Fukui functions. The results allow to conclude that the reaction leading to the formation of L-ThDP occurs via a concerted mechanism, and during the nucleophilic attack on the pyruvate molecule, the ylide is in its AP form. The calculated activation barrier for the reaction is 19.2 kcal/mol, in agreement with the experimental reported value.

  3. Leading coordinate analysis of reaction pathways in proton chain transfer: Application to a two-proton transfer model for the green fluorescent protein

    International Nuclear Information System (INIS)

    Wang Sufan; Smith, Sean C.

    2006-01-01

    The 'leading coordinate' approach to computing an approximate reaction pathway, with subsequent determination of the true minimum energy profile, is applied to a two-proton chain transfer model based on the chromophore and its surrounding moieties within the green fluorescent protein (GFP). Using an ab initio quantum chemical method, a number of different relaxed energy profiles are found for several plausible guesses at leading coordinates. The results obtained for different trial leading coordinates are rationalized through the calculation of a two-dimensional relaxed potential energy surface (PES) for the system. Analysis of the 2-D relaxed PES reveals that two of the trial pathways are entirely spurious, while two others contain useful information and can be used to furnish starting points for successful saddle-point searches. Implications for selection of trial leading coordinates in this class of proton chain transfer reactions are discussed, and a simple diagnostic function is proposed for revealing whether or not a relaxed pathway based on a trial leading coordinate is likely to furnish useful information

  4. Combustion kinetics and reaction pathways

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-01

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

  5. Minimum Energy Pathways for Chemical Reactions

    Science.gov (United States)

    Walch, S. P.; Langhoff, S. R. (Technical Monitor)

    1995-01-01

    Computed potential energy surfaces are often required for computation of such parameters as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method to obtain accurate energetics, gives useful results for a number of chemically important systems. The talk will focus on a number of applications to reactions leading to NOx and soot formation in hydrocarbon combustion.

  6. Recyclization reactions leading to benzimidazoles

    International Nuclear Information System (INIS)

    Mamedov, Vakhid A; Murtazina, Anna M

    2011-01-01

    The published data on the recyclization reactions that afford benzimidazoles are generalized and systematized. Both classical and new methods of benzimidazole synthesis are considered. Attention is focused on the publications over the recent 10-15 years; of the earlier publications, only those unknown to the wide circle of chemists are analyzed.

  7. Recyclization reactions leading to benzimidazoles

    Science.gov (United States)

    Mamedov, Vakhid A.; Murtazina, Anna M.

    2011-05-01

    The published data on the recyclization reactions that afford benzimidazoles are generalized and systematized. Both classical and new methods of benzimidazole synthesis are considered. Attention is focused on the publications over the recent 10-15 years; of the earlier publications, only those unknown to the wide circle of chemists are analyzed.

  8. Explorations into Chemical Reactions and Biochemical Pathways.

    Science.gov (United States)

    Gasteiger, Johann

    2016-12-01

    A brief overview of the work in the research group of the present author on extracting knowledge from chemical reaction data is presented. Methods have been developed to calculate physicochemical effects at the reaction site. It is shown that these physicochemical effects can quite favourably be used to derive equations for the calculation of data on gas phase reactions and on reactions in solution such as aqueous acidity of alcohols or carboxylic acids or the hydrolysis of amides. Furthermore, it is shown that these physicochemical effects are quite effective for assigning reactions into reaction classes that correspond to chemical knowledge. Biochemical reactions constitute a particularly interesting and challenging task for increasing our understanding of living species. The BioPath.Database is a rich source of information on biochemical reactions and has been used for a variety of applications of chemical, biological, or medicinal interests. Thus, it was shown that biochemical reactions can be assigned by the physicochemical effects into classes that correspond to the classification of enzymes by the EC numbers. Furthermore, 3D models of reaction intermediates can be used for searching for novel enzyme inhibitors. It was shown in a combined application of chemoinformatics and bioinformatics that essential pathways of diseases can be uncovered. Furthermore, a study showed that bacterial flavor-forming pathways can be discovered. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Serpentinization reaction pathways: implications for modeling approach

    Energy Technology Data Exchange (ETDEWEB)

    Janecky, D.R.

    1986-01-01

    Experimental seawater-peridotite reaction pathways to form serpentinites at 300/sup 0/C, 500 bars, can be accurately modeled using the EQ3/6 codes in conjunction with thermodynamic and kinetic data from the literature and unpublished compilations. These models provide both confirmation of experimental interpretations and more detailed insight into hydrothermal reaction processes within the oceanic crust. The accuracy of these models depends on careful evaluation of the aqueous speciation model, use of mineral compositions that closely reproduce compositions in the experiments, and definition of realistic reactive components in terms of composition, thermodynamic data, and reaction rates.

  10. Multistage reaction pathways in detonating high explosives

    International Nuclear Information System (INIS)

    Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Nomura, Ken-ichi; Vashishta, Priya

    2014-01-01

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine crystal. Rapid production of N 2 and H 2 O within ∼10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N 2 and H 2 O productions

  11. Identifying Reaction Pathways and their Environments

    DEFF Research Database (Denmark)

    Maronsson, Jon Bergmann

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

  12. Multistage reaction pathways in detonating high explosives

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kalia, Rajiv K.; Nakano, Aiichiro; Nomura, Ken-ichi; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)

    2014-11-17

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine crystal. Rapid production of N{sub 2} and H{sub 2}O within ∼10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N{sub 2} and H{sub 2}O productions.

  13. Kynurenine pathway metabolites and enzymes involved in redox reactions.

    Science.gov (United States)

    González Esquivel, D; Ramírez-Ortega, D; Pineda, B; Castro, N; Ríos, C; Pérez de la Cruz, V

    2017-01-01

    Oxido-reduction reactions are a fundamental part of the life due to support many vital biological processes as cellular respiration and glucose oxidation. In the redox reactions, one substance transfers one or more electrons to another substance. An important electron carrier is the coenzyme NAD + , which is involved in many metabolic pathways. De novo biosynthesis of NAD + is through the kynurenine pathway, the major route of tryptophan catabolism, which is sensitive to redox environment and produces metabolites with redox capacity, able to alter biological functions that are controlled by redox-responsive signaling pathways. Kynurenine pathway metabolites have been implicated in the physiology process and in the physiopathology of many diseases; processes that also share others factors as dysregulation of calcium homeostasis, mitochondrial dysfunction, oxidative stress, inflammation and cell death, which impact the redox environment. This review examines in detail the available evidence in which kynurenine pathway metabolites participate in redox reactions and their effect on cellular redox homeostasis, since the knowledge of the main factors and mechanisms that lead to cell death in many neurodegenative disorders and other pathologies, such as mitochondrial dysfunction, oxidative stress and kynurenines imbalance, will allow to develop therapies using them as targets. This article is part of the Special Issue entitled 'The Kynurenine Pathway in Health and Disease'. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Proatherogenic pathways leading to vascular calcification

    International Nuclear Information System (INIS)

    Mazzini, Michael J.; Schulze, P. Christian

    2006-01-01

    Cardiovascular disease is the leading cause of morbidity and mortality in the western world and atherosclerosis is the major common underlying disease. The pathogenesis of atherosclerosis involves local vascular injury, inflammation and oxidative stress as well as vascular calcification. Vascular calcification has long been regarded as a degenerative process leading to mineral deposition in the vascular wall characteristic for late stages of atherosclerosis. However, recent studies identified vascular calcification in early stages of atherosclerosis and its occurrence has been linked to clinical events in patients with cardiovascular disease. Its degree correlates with local vascular inflammation and with the overall impact and the progression of atherosclerosis. Over the last decade, diverse and highly regulated molecular signaling cascades controlling vascular calcification have been described. Local and circulating molecules such as osteopontin, osteoprogerin, leptin and matrix Gla protein were identified as critical regulators of vascular calcification. We here review the current knowledge on molecular pathways of vascular calcification and their relevance for the progression of cardiovascular disease

  15. Pathways of the Maillard reaction under physiological conditions.

    Science.gov (United States)

    Henning, Christian; Glomb, Marcus A

    2016-08-01

    Initially investigated as a color formation process in thermally treated foods, nowadays, the relevance of the Maillard reaction in vivo is generally accepted. Many chronic and age-related diseases such as diabetes, uremia, atherosclerosis, cataractogenesis and Alzheimer's disease are associated with Maillard derived advanced glycation endproducts (AGEs) and α-dicarbonyl compounds as their most important precursors in terms of reactivity and abundance. However, the situation in vivo is very challenging, because Maillard chemistry is paralleled by enzymatic reactions which can lead to both, increases and decreases in certain AGEs. In addition, mechanistic findings established under the harsh conditions of food processing might not be valid under physiological conditions. The present review critically discusses the relevant α-dicarbonyl compounds as central intermediates of AGE formation in vivo with a special focus on fragmentation pathways leading to formation of amide-AGEs.

  16. Soil is an important pathway of human lead exposure.

    OpenAIRE

    Mielke, H W; Reagan, P L

    1998-01-01

    This review shows the equal or greater importance of leaded gasoline-contaminated dust compared to lead-based paint to the child lead problem, and that soil lead, resulting from leaded gasoline and pulverized lead-based paint, is at least or more important than lead-based paint (intact and not pulverized) as a pathway of human lead exposure. Because lead-based paint is a high-dose source, the biologically relevant dosage is similar to lead in soil. Both lead-based paint and soil lead are asso...

  17. Aligning Metabolic Pathways Exploiting Binary Relation of Reactions.

    Directory of Open Access Journals (Sweden)

    Yiran Huang

    Full Text Available Metabolic pathway alignment has been widely used to find one-to-one and/or one-to-many reaction mappings to identify the alternative pathways that have similar functions through different sets of reactions, which has important applications in reconstructing phylogeny and understanding metabolic functions. The existing alignment methods exhaustively search reaction sets, which may become infeasible for large pathways. To address this problem, we present an effective alignment method for accurately extracting reaction mappings between two metabolic pathways. We show that connected relation between reactions can be formalized as binary relation of reactions in metabolic pathways, and the multiplications of zero-one matrices for binary relations of reactions can be accomplished in finite steps. By utilizing the multiplications of zero-one matrices for binary relation of reactions, we efficiently obtain reaction sets in a small number of steps without exhaustive search, and accurately uncover biologically relevant reaction mappings. Furthermore, we introduce a measure of topological similarity of nodes (reactions by comparing the structural similarity of the k-neighborhood subgraphs of the nodes in aligning metabolic pathways. We employ this similarity metric to improve the accuracy of the alignments. The experimental results on the KEGG database show that when compared with other state-of-the-art methods, in most cases, our method obtains better performance in the node correctness and edge correctness, and the number of the edges of the largest common connected subgraph for one-to-one reaction mappings, and the number of correct one-to-many reaction mappings. Our method is scalable in finding more reaction mappings with better biological relevance in large metabolic pathways.

  18. Stepwise radical cation Diels-Alder reaction via multiple pathways.

    Science.gov (United States)

    Shimizu, Ryo; Okada, Yohei; Chiba, Kazuhiro

    2018-01-01

    Herein we disclose the radical cation Diels-Alder reaction of aryl vinyl ethers by electrocatalysis, which is triggered by an oxidative SET process. The reaction clearly proceeds in a stepwise fashion, which is a rare mechanism in this class. We also found that two distinctive pathways, including "direct" and "indirect", are possible to construct the Diels-Alder adduct.

  19. Permanganate oxidation of α-amino acids: kinetic correlations for the nonautocatalytic and autocatalytic reaction pathways.

    Science.gov (United States)

    Perez-Benito, Joaquin F

    2011-09-08

    The reactions of permanganate ion with seven α-amino acids in aqueous KH(2)PO(4)/K(2)HPO(4) buffers have been followed spectrophotometrically at two different wavelengths: 526 nm (decay of MnO(4)(-)) and 418 nm (formation of colloidal MnO(2)). All of the reactions studied were autocatalyzed by colloidal MnO(2), with the contribution of the autocatalytic reaction pathway decreasing in the order glycine > l-threonine > l-alanine > l-glutamic acid > l-leucine > l-isoleucine > l-valine. The rate constants corresponding to the nonautocatalytic and autocatalytic pathways were obtained by means of either a differential rate law or an integrated one, the latter requiring the use of an iterative method for its implementation. The activation parameters for the two pathways were determined and analyzed to obtain statistically significant correlations for the series of reactions studied. The activation enthalpy of the nonautocatalytic pathway showed a strong, positive dependence on the standard Gibbs energy for the dissociation of the protonated amino group of the α-amino acid. Linear enthalpy-entropy correlations were found for both pathways, leading to isokinetic temperatures of 370 ± 21 K (nonautocatalytic) and 364 ± 28 K (autocatalytic). Mechanisms in agreement with the experimental data are proposed for the two reaction pathways.

  20. DMPD: Multiple signaling pathways leading to the activation of interferon regulatoryfactor 3. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 12213596 Multiple signaling pathways leading to the activation of interferon regula...(.html) (.csml) Show Multiple signaling pathways leading to the activation of interferon regulatoryfactor 3.... PubmedID 12213596 Title Multiple signaling pathways leading to the activation of

  1. A multi-pathway model for photosynthetic reaction center

    International Nuclear Information System (INIS)

    Qin, M.; Shen, H. Z.; Yi, X. X.

    2016-01-01

    Charge separation occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine. Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem II reaction center (PSII RC) to describe the charge separation. Our model mainly considers two charge-separation pathways which is more than that typically considered in the published literature. We explore how these cross-couplings increase the current and power of the charge separation and discuss the effects of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PSII RC and dephasing induced by environments is also explored, and extension from two pathways to multiple pathways is made. These results suggest that noise-induced quantum coherence helps to suppress the influence of acceptor-to-donor charge recombination, and besides, nature-mimicking architectures with engineered multiple pathways for charge separations might be better for artificial solar energy devices considering the influence of environments.

  2. Reaction pathways of the dissociation of methylal: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Frey, H -M; Beaud, P; Gerber, T; Mischler, B; Radi, P P; Tzannis, A -P [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Schemata for modelling combustion processes do not yet include reaction rates for oxygenated fuels like methylal (DMM) which is considered as an additive or replacement for diesel due to its low sooting propensity. Density functional theory (DFT) studies of the possible reaction pathways for different dissociation steps of methylal are presented. Cleavage of a hydrogen bond to the methoxy group or the central carbon atom were simulated at the BLYP/6-311++G{sup **} level of theory. The results are compared to the experiment when dissociating and/or ionising DMM with femtosecond pulses. (author) 1 fig., 1 tab., 1 ref.

  3. Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions

    Science.gov (United States)

    Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)

    1994-01-01

    Computed potential energy surfaces are often required for computation of such parameters as rate constants as a function of temperature, product branching ratios, and other detailed properties. For some dynamics methods, global potential energy surfaces are required. In this case, it is necessary to obtain the energy at a complete sampling of all the possible arrangements of the nuclei, which are energetically accessible, and then a fitting function must be obtained to interpolate between the computed points. In other cases, characterization of the stationary points and the reaction pathway connecting them is sufficient. These properties may be readily obtained using analytical derivative methods. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method to obtain accurate energetics, gives usefull results for a number of chemically important systems. The talk will focus on a number of applications including global potential energy surfaces, H + O2, H + N2, O(3p) + H2, and reaction pathways for complex reactions, including reactions leading to NO and soot formation in hydrocarbon combustion.

  4. Computed Potential Energy Surfaces and Minimum Energy Pathway for Chemical Reactions

    Science.gov (United States)

    Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)

    1994-01-01

    Computed potential energy surfaces are often required for computation of such observables as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method with the Dunning correlation consistent basis sets to obtain accurate energetics, gives useful results for a number of chemically important systems. Applications to complex reactions leading to NO and soot formation in hydrocarbon combustion are discussed.

  5. Kinetic and reaction pathways of methanol oxidation on platinum

    International Nuclear Information System (INIS)

    McCabe, R.W.; McCready, D.F.

    1986-01-01

    Methanol oxidation kinetics were measured on Pt wires in a flow reactor at pressures between 30 and 130 Pa. The kinetics were measured as a function of oxygen-to-methanol equivalence ratio phi and wire temperature. In methanol-lean feeds (phi 2 CO, CO 2 , and H 2 O were the only products; in methanol-rich feeds (phi > 1), CO, H 2 , H 2 CO, CO 2 , and H 2 O were observed. Experiments with 18 O 2 showed that the principal methanol oxidation pathway does not involve C-O bond dissociation. However, the 18 O 2 experiments, together with other features of the methanol oxidation data, also provided evidence for a minor oxidation pathway (accounting for less than 1% of the product CO 2 ) which proceeds through a carbon intermediate. A mathematical model is presented which describes the principal CH 3 OH oxidation pathway as a series reaction involving adsorbed H 2 CO and CO intermediates. Consistent with experimental results, the model predicts that inhibition by adsorbed CO should be weaker for CH 3 OH and H 2 CO oxidation than for CO oxidation. 34 references, 10 figures, 2 tables

  6. Reaction of H2 with O2 in Excited Electronic States: Reaction Pathways and Rate Constants.

    Science.gov (United States)

    Pelevkin, Alexey V; Loukhovitski, Boris I; Sharipov, Alexander S

    2017-12-21

    Comprehensive quantum chemical analysis with the use of the multireference state-averaged complete active space self-consistent field approach was carried out to study the reactions of H 2 with O 2 in a 1 Δ g , b 1 Σ g + , c 1 Σ u - , and A' 3 Δ u electronically excited states. The energetically favorable reaction pathways and possible intersystem crossings have been revealed. The energy barriers were refined employing the extended multiconfiguration quasi-degenerate second-order perturbation theory. It has been shown that the interaction of O 2 (a 1 Δ g ) and O 2 (A' 3 Δ u ) with H 2 occurs through the H-abstraction process with relatively low activation barriers that resulted in the formation of the HO 2 molecule in A″ and A' electronic states, respectively. Meanwhile, molecular oxygen in singlet sigma states (b 1 Σ g + and c 1 Σ u - ) was proved to be nonreactive with respect to the molecular hydrogen. Appropriate rate constants for revealed reaction and quenching channels have been estimated using variational transition-state theory including corrections for the tunneling effect, possible nonadiabatic transitions, and anharmonicity of vibrations for transition states and reactants. It was demonstrated that the calculated reaction rate constant for the H 2 + O 2 (a 1 Δ g ) process is in reasonable agreement with known experimental data. The Arrhenius approximations for these processes have been proposed for the temperature range T = 300-3000 K.

  7. The role of grain boundaries and transient porosity increase as fluid pathways for reaction front propagation

    Science.gov (United States)

    Jonas, Laura; John, Timm; Geisler, Thorsten; Putnis, Andrew

    2013-04-01

    The pseudomorphic replacement of Carrara marble by calcium phosphates was studied as a model system to examine the influence of different fluid pathways for reaction front propagation induced by fluid-rock interaction. In this model system, the grain boundaries present in the rock and the transient porosity structures developing throughout the replacement reaction enable the reaction front to progress further into the rock as well as to the center of each single grain until complete transformation. Hydrothermal treatment of the marble using phosphate bearing solutions at temperature levels of 150° C and 200° C for different durations lead to the formation of two product phases which were identified as hydroxyapatite [Ca5(PO4)3OH] as well as β-tricalcium phosphate [β-Ca3(PO4)2] (β-TCP). The formation of β-TCP was probably favored by the presence of ~0.6wt.% of Mg in the parent phase. Completely transformed single grains show a distinctive zoning, both in composition and texture. Whereas areas next to the grain boundary consist of nearly pure hydroxyapatite and show a coarse porosity, areas close to the center of the single grains show a high amount of β-TCP and a very fine porous microstructure. If F was added as an additional solution component, the formation of β-TCP was avoided and up to 3wt.% of F were incorporated into the product apatite. The use of the isotope 18O as a chronometer for the replacement reaction makes it possible to reconstruct the chronological development of the calcium phosphate reaction front. Raman analysis revealed that the incorporation of 18O in the PO4 tetrahedron of hydroxyapatite results in the development of distinct profiles in the calcium phosphate reaction front perpendicular to the grain boundaries of the marble. Through the use of the 18O chronometer, it is possible to estimate and compare the time effectiveness of the different fluid pathways in this model system. The results show that the grain boundaries serve as a

  8. Position-specific isotope modeling of organic micropollutants transformation through different reaction pathways

    DEFF Research Database (Denmark)

    Jin, Biao; Rolle, Massimo

    2016-01-01

    The degradation of organic micropollutants occurs via different reaction pathways. Compound specific isotope analysis is a valuable tool to identify such degradation pathways in different environmental systems. We propose a mechanism-based modeling approach that provides a quantitative framework ...

  9. Cellular and Molecular Pathways Leading to External Root Resorption

    Science.gov (United States)

    Iglesias-Linares, A.; Hartsfield, J.K.

    2016-01-01

    External apical root resorption during orthodontic treatment implicates specific molecular pathways that orchestrate nonphysiologic cellular activation. To date, a substantial number of in vitro and in vivo molecular, genomic, and proteomic studies have supplied data that provide new insights into root resorption. Recent mechanisms and developments reviewed here include the role of the cellular component—specifically, the balance of CD68+, iNOS+ M1- and CD68+, CD163+ M2-like macrophages associated with root resorption and root surface repair processes linked to the expression of the M1-associated proinflammatory cytokine tumor necrosis factor, inducible nitric oxide synthase, the M1 activator interferon γ, the M2 activator interleukin 4, and M2-associated anti-inflammatory interleukin 10 and arginase I. Insights into the role of mesenchymal dental pulp cells in attenuating dentin resorption in homeostasis are also reviewed. Data on recently deciphered molecular pathways are reviewed at the level of (1) clastic cell adhesion in the external apical root resorption process and the specific role of α/β integrins, osteopontin, and related extracellular matrix proteins; (2) clastic cell fusion and activation by the RANKL/RANK/OPG and ATP-P2RX7-IL1 pathways; and (3) regulatory mechanisms of root resorption repair by cementum at the proteomic and transcriptomic levels. PMID:27811065

  10. Pyrrolizidine Alkaloids: Metabolic Activation Pathways Leading to Liver Tumor Initiation.

    Science.gov (United States)

    Fu, Peter P

    2017-01-17

    Pyrrolizidine alkaloids (PAs) and PA N-oxides are a class of phytochemical carcinogens contained in over 6000 plant species spread around the world. It has been estimated that approximately half of the 660 PAs and PA N-oxides that have been characterized are cytotoxic, genotoxic, and tumorigenic. It was recently determined that a genotoxic mechanism of liver tumor initiation mediated by PA-derived DNA adducts is a common metabolic activation pathway of a number of PAs. We proposed this set of PA-derived DNA adducts could be a common biological biomarker of PA exposure and a potential biomarker of PA-induced liver tumor formation. We have also found that several reactive secondary pyrrolic metabolites can dissociate and interconvert to other secondary pyrrolic metabolites, resulting in the formation of the same exogenous DNA adducts. This present perspective reports the current progress on these new findings and proposes future research needed for obtaining a greater understanding of the role of this activation pathway and validating the use of this set of PA-derived DNA adducts as a biological biomarker of PA-induced liver tumor initiation.

  11. Reaction-transport simulations of non-oxidative methane conversion with continuous hydrogen removal: Homogeneous-heterogeneous methane reaction pathways

    International Nuclear Information System (INIS)

    Li, Lin; Borry, Richard W.; Iglesia, Enrique

    2000-01-01

    Detailed kinetic-transport models were used to explore thermodynamic and kinetic barriers in the non-oxidative conversion of CH4 via homogeneous and homogeneous-heterogeneous pathways and the effects of continuous hydrogen removal and of catalytic sites on attainable yields of useful C2-C10 products. The homogeneous kinetic model combines separately developed models for low-conversion pyrolysis and for chain growth to form large aromatics and carbon. The H2 formed in the reaction decreases CH4 pyrolysis rates and equilibrium conversions and it favors the formation of lighter products. The removal of H2 along tubular reactors with permeable walls increases reaction rates and equilibrium CH4 conversions. C2-C10 yields reach values greater than 90 percent at intermediate values of dimensionless transport rates (delta=1-10), defined as the ratio hydrogen transport and methane conversion rates. Homogeneous reactions require impractical residence times, even with H2 removal, because of slow initiation and chain transfer rates. The introduction of heterogeneous chain initiation pathways using surface sites that form methyl radicals eliminates the induction period without influencing the homogeneous product distribution. Methane conversion, however, occurs predominately in the chain transfer regime, within which individual transfer steps and the formation of C2 intermediates become limited by thermodynamic constraints. Catalytic sites alone cannot overcome these constraints. Catalytic membrane reactors with continuous H2 removal remove these thermodynamic obstacles and decrease the required residence time. Reaction rates become limited by homogeneous reactions of C2 products to form C6+ aromatics. Higher delta values lead to subsequent conversion of the desired C2-C10 products to larger polynuclear aromatics. We conclude that catalytic methane pyrolysis at the low temperatures required for restricted chain growth and the elimination of thermodynamics constraints via

  12. [Various pathways leading to the progression of chronic liver diseases].

    Science.gov (United States)

    Egresi, Anna; Lengyel, Gabriella; Somogyi, Anikó; Blázovics, Anna; Hagymási, Krisztina

    2016-02-21

    As the result of various effects (viruses, metabolic diseases, nutritional factors, toxic agents, autoimmune processes) abnormal liver function, liver steatosis and connective tissue remodeling may develop. Progression of this process is complex including various pathways and a number of factors. The authors summarize the factors involved in the progression of chronic liver disease. They describe the role of cells and the produced inflammatory mediators and cytokines, as well as the relationship between the disease and the intestinal flora. They emphasize the role of oxidative stress, mitochondrial dysfunction and cell death in disease progression. Insulin resistance and micro-elements (iron, copper) in relation to liver damage are also discussed, and genetic and epigenetic aspects underlying disease progression are summarized. Discovery of novel treatment options, assessment of the effectiveness of treatment, as well as the success and proper timing of liver transplantation may depend on a better understanding of the process of disease progression.

  13. Reaction pathways for reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes

    International Nuclear Information System (INIS)

    Cunha, M.C.P.M. da; De Souza, J.P.I.; Nart, F.C.

    2000-01-01

    The reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes has been investigated using differential electrochemical mass spectrometry and in situ FTIR measurements. For 3 M HNO 3 concentration it has been found that nitrate starts the reduction with partial N-O bond dissociation and N-N bond formation generating NO and N 2 O. At potentials lower than 0.2 V the reaction proceeds forming dissolved NH 4 + . For potentials lower than 0 V the reduction continues via a multiple pathway reaction leading to the nonselective production of N 2 , NH 2 OH, and N 2 H 2 . On the alloyed electrodes, the production of NO and N 2 O has been observed in both cathodic and anodic scans, while on pure platinum and rhodium electrodes the reaction has been observed only during the cathodic scan. Contrasting with the pure platinum and rhodium alloys, where the N-O bond break starts forming NO and N 2 O, on the alloys HNO 2 has been observed as the first reaction step. For alloys with higher rhodium composition, like Pt 75 Rh 25 , no N 2 has been detected for potentials lower than 0 V

  14. Investigations on organolead compounds V. Lead---lead bond cleavage reactions of hexaphenyldilead

    NARCIS (Netherlands)

    Willemsens, L.C.; Kerk, G.J.M. van der

    1968-01-01

    It has been shown that a number of nucleophilic and weakly electrophilic reagents (organolithium and organomagnesium compounds, metallic lithium, potassium permanganate, sodium ethoxide, diaryl disulphides, sulphur, ozone, hypochlorous acid and iodine/iodide) selectively cleave the lead---lead bond

  15. Reactivity of Single-Walled Carbon Nanotubes in the Diels-Alder Cycloaddition Reaction: Distortion-Interaction Analysis along the Reaction Pathway.

    Science.gov (United States)

    Li, Yingzi; Osuna, Sílvia; Garcia-Borràs, Marc; Qi, Xiaotian; Liu, Song; Houk, Kendall N; Lan, Yu

    2016-08-26

    Diels-Alder cycloaddition is one of the most powerful tools for the functionalization of single-walled carbon nanotubes (SWCNTs). Density functional theory at the B3-LYP level of theory has been used to investigate the reactivity of different-diameter SWCNTs (4-9,5) in Diels-Alder reactions with 1,3-butadiene; the reactivity was found to decrease with increasing SWCNT diameter. Distortion/interaction analysis along the whole reaction pathway was found to be a better way to explore the reactivity of this type of reaction. The difference in interaction energy along the reaction pathway is larger than that of the corresponding distortion energy. However, the distortion energy plots for these reactions show the same trend. Therefore, the formation of the transition state can be determined from the interaction energy. A lower interaction energy leads to an earlier transition state, which indicates a lower activation energy. The computational results also indicate that the original distortion of the SWCNTs leads to an increase in the reactivity of the SWCNTs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. MAPK pathway activation by chronic lead-exposure increases vascular reactivity through oxidative stress/cyclooxygenase-2-dependent pathways

    Energy Technology Data Exchange (ETDEWEB)

    Simões, Maylla Ronacher, E-mail: yllars@hotmail.com [Dept. of Physiological Sciences, Federal University of Espirito Santo, Vitória, ES CEP 29040-091 (Brazil); Department of Pharmacology, Universidad Autonoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid (Spain); Aguado, Andrea [Department of Pharmacology, Universidad Autonoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid (Spain); Fiorim, Jonaína; Silveira, Edna Aparecida; Azevedo, Bruna Fernandes; Toscano, Cindy Medice [Dept. of Physiological Sciences, Federal University of Espirito Santo, Vitória, ES CEP 29040-091 (Brazil); Zhenyukh, Olha; Briones, Ana María [Department of Pharmacology, Universidad Autonoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid (Spain); Alonso, María Jesús [Dept. of Biochemistry, Physiology and Molecular Genetics, Universidad Rey Juan Carlos, Alcorcón (Spain); Vassallo, Dalton Valentim [Dept. of Physiological Sciences, Federal University of Espirito Santo, Vitória, ES CEP 29040-091 (Brazil); Health Science Center of Vitória-EMESCAM, Vitória, ES CEP 29045-402 (Brazil); Salaices, Mercedes, E-mail: mercedes.salaices@uam.es [Department of Pharmacology, Universidad Autonoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid (Spain)

    2015-03-01

    Chronic exposure to low lead concentration produces hypertension; however, the underlying mechanisms remain unclear. We analyzed the role of oxidative stress, cyclooxygenase-2-dependent pathways and MAPK in the vascular alterations induced by chronic lead exposure. Aortas from lead-treated Wistar rats (1st dose: 10 μg/100 g; subsequent doses: 0.125 μg/100 g, intramuscular, 30 days) and cultured aortic vascular smooth muscle cells (VSMCs) from Sprague Dawley rats stimulated with lead (20 μg/dL) were used. Lead blood levels of treated rats attained 21.7 ± 2.38 μg/dL. Lead exposure increased systolic blood pressure and aortic ring contractile response to phenylephrine, reduced acetylcholine-induced relaxation and did not affect sodium nitroprusside relaxation. Endothelium removal and L-NAME left-shifted the response to phenylephrine more in untreated than in lead-treated rats. Apocynin and indomethacin decreased more the response to phenylephrine in treated than in untreated rats. Aortic protein expression of gp91(phox), Cu/Zn-SOD, Mn-SOD and COX-2 increased after lead exposure. In cultured VSMCs lead 1) increased superoxide anion production, NADPH oxidase activity and gene and/or protein levels of NOX-1, NOX-4, Mn-SOD, EC-SOD and COX-2 and 2) activated ERK1/2 and p38 MAPK. Both antioxidants and COX-2 inhibitors normalized superoxide anion production, NADPH oxidase activity and mRNA levels of NOX-1, NOX-4 and COX-2. Blockade of the ERK1/2 and p38 signaling pathways abolished lead-induced NOX-1, NOX-4 and COX-2 expression. Results show that lead activation of the MAPK signaling pathways activates inflammatory proteins such as NADPH oxidase and COX-2, suggesting a reciprocal interplay and contribution to vascular dysfunction as an underlying mechanisms for lead-induced hypertension. - Highlights: • Lead-exposure increases oxidative stress, COX-2 expression and vascular reactivity. • Lead exposure activates MAPK signaling pathway. • ROS and COX-2 activation by

  17. Unexpected Reaction Pathway for butyrylcholinesterase-catalyzed inactivation of “hunger hormone” ghrelin

    Science.gov (United States)

    Yao, Jianzhuang; Yuan, Yaxia; Zheng, Fang; Zhan, Chang-Guo

    2016-02-01

    Extensive computational modeling and simulations have been carried out, in the present study, to uncover the fundamental reaction pathway for butyrylcholinesterase (BChE)-catalyzed hydrolysis of ghrelin, demonstrating that the acylation process of BChE-catalyzed hydrolysis of ghrelin follows an unprecedented single-step reaction pathway and the single-step acylation process is rate-determining. The free energy barrier (18.8 kcal/mol) calculated for the rate-determining step is reasonably close to the experimentally-derived free energy barrier (~19.4 kcal/mol), suggesting that the obtained mechanistic insights are reasonable. The single-step reaction pathway for the acylation is remarkably different from the well-known two-step acylation reaction pathway for numerous ester hydrolysis reactions catalyzed by a serine esterase. This is the first time demonstrating that a single-step reaction pathway is possible for an ester hydrolysis reaction catalyzed by a serine esterase and, therefore, one no longer can simply assume that the acylation process must follow the well-known two-step reaction pathway.

  18. Confining Domains Lead to Reaction Bursts: Reaction Kinetics in the Plasma Membrane

    Science.gov (United States)

    Kalay, Ziya; Fujiwara, Takahiro K.; Kusumi, Akihiro

    2012-01-01

    Confinement of molecules in specific small volumes and areas within a cell is likely to be a general strategy that is developed during evolution for regulating the interactions and functions of biomolecules. The cellular plasma membrane, which is the outermost membrane that surrounds the entire cell, was considered to be a continuous two-dimensional liquid, but it is becoming clear that it consists of numerous nano-meso-scale domains with various lifetimes, such as raft domains and cytoskeleton-induced compartments, and membrane molecules are dynamically trapped in these domains. In this article, we give a theoretical account on the effects of molecular confinement on reversible bimolecular reactions in a partitioned surface such as the plasma membrane. By performing simulations based on a lattice-based model of diffusion and reaction, we found that in the presence of membrane partitioning, bimolecular reactions that occur in each compartment proceed in bursts during which the reaction rate is sharply and briefly increased even though the asymptotic reaction rate remains the same. We characterized the time between reaction bursts and the burst amplitude as a function of the model parameters, and discussed the biological significance of the reaction bursts in the presence of strong inhibitor activity. PMID:22479350

  19. Confining domains lead to reaction bursts: reaction kinetics in the plasma membrane.

    Directory of Open Access Journals (Sweden)

    Ziya Kalay

    Full Text Available Confinement of molecules in specific small volumes and areas within a cell is likely to be a general strategy that is developed during evolution for regulating the interactions and functions of biomolecules. The cellular plasma membrane, which is the outermost membrane that surrounds the entire cell, was considered to be a continuous two-dimensional liquid, but it is becoming clear that it consists of numerous nano-meso-scale domains with various lifetimes, such as raft domains and cytoskeleton-induced compartments, and membrane molecules are dynamically trapped in these domains. In this article, we give a theoretical account on the effects of molecular confinement on reversible bimolecular reactions in a partitioned surface such as the plasma membrane. By performing simulations based on a lattice-based model of diffusion and reaction, we found that in the presence of membrane partitioning, bimolecular reactions that occur in each compartment proceed in bursts during which the reaction rate is sharply and briefly increased even though the asymptotic reaction rate remains the same. We characterized the time between reaction bursts and the burst amplitude as a function of the model parameters, and discussed the biological significance of the reaction bursts in the presence of strong inhibitor activity.

  20. Centrality in Hadron-Carbon, Hadron-Lead, and Lead-Lead Reactions at 158 GeV/c

    International Nuclear Information System (INIS)

    Rybicki, A.

    2006-08-01

    A study of centrality in p + C, π + C, p + Pb, π + Pb, and Pb + Pb reactions is made. The analysis is performed by means of a simple geometrical model. The mean number of elementary collisions, , is estimated in minimum bias p + C reactions. For the specific case of the carbon nucleus, estimates on appear to depend strongly on assumed nuclear densities. Most realistic of the presented assumptions result in a value of 1.71 ± 0.05. Additional quantities, like predictions for the total inelastic cross-section in p + C reactions, or the number of participants in minimum bias C + C collisions, are given. The analysis is subsequently extended to minimum bias π + C, π + Pb, and p + Pb reactions. Estimates are given for the mean number of elementary collisions as well as for the contribution of single collisions P(1). A comparison with experimental data is made. Finally, the impact parameter dependence of p + Pb and Pb + Pb collisions is discussed. In view of future studies, various aspects of the analysis are discussed in detail; a bibliography of used references is included. (author)

  1. Drug metabolism by cytochrome p450 enzymes: what distinguishes the pathways leading to substrate hydroxylation over desaturation?

    Science.gov (United States)

    Ji, Li; Faponle, Abayomi S; Quesne, Matthew G; Sainna, Mala A; Zhang, Jing; Franke, Alicja; Kumar, Devesh; van Eldik, Rudi; Liu, Weiping; de Visser, Sam P

    2015-06-15

    Cytochrome P450 enzymes are highly versatile biological catalysts in our body that react with a broad range of substrates. Key functions in the liver include the metabolism of drugs and xenobiotics. One particular metabolic pathway that is poorly understood relates to the P450 activation of aliphatic groups leading to either hydroxylation or desaturation pathways. A DFT and QM/MM study has been carried out on the factors that determine the regioselectivity of aliphatic hydroxylation over desaturation of compounds by P450 isozymes. The calculations establish multistate reactivity patterns, whereby the product distributions differ on each of the spin-state surfaces; hence spin-selective product formation was found. The electronic and thermochemical factors that determine the bifurcation pathways were analysed and a model that predicts the regioselectivity of aliphatic hydroxylation over desaturation pathways was established from valence bond and molecular orbital theories. Thus, the difference in energy of the OH versus the OC bond formed and the π-conjugation energy determines the degree of desaturation products. In addition, environmental effects of the substrate binding pocket that affect the regioselectivities were identified. These studies imply that bioengineering P450 isozymes for desaturation reactions will have to include modifications in the substrate binding pocket to restrict the hydroxylation rebound reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Enzyme sequence similarity improves the reaction alignment method for cross-species pathway comparison

    Energy Technology Data Exchange (ETDEWEB)

    Ovacik, Meric A. [Chemical and Biochemical Engineering Department, Rutgers University, Piscataway, NJ 08854 (United States); Androulakis, Ioannis P., E-mail: yannis@rci.rutgers.edu [Chemical and Biochemical Engineering Department, Rutgers University, Piscataway, NJ 08854 (United States); Biomedical Engineering Department, Rutgers University, Piscataway, NJ 08854 (United States)

    2013-09-15

    Pathway-based information has become an important source of information for both establishing evolutionary relationships and understanding the mode of action of a chemical or pharmaceutical among species. Cross-species comparison of pathways can address two broad questions: comparison in order to inform evolutionary relationships and to extrapolate species differences used in a number of different applications including drug and toxicity testing. Cross-species comparison of metabolic pathways is complex as there are multiple features of a pathway that can be modeled and compared. Among the various methods that have been proposed, reaction alignment has emerged as the most successful at predicting phylogenetic relationships based on NCBI taxonomy. We propose an improvement of the reaction alignment method by accounting for sequence similarity in addition to reaction alignment method. Using nine species, including human and some model organisms and test species, we evaluate the standard and improved comparison methods by analyzing glycolysis and citrate cycle pathways conservation. In addition, we demonstrate how organism comparison can be conducted by accounting for the cumulative information retrieved from nine pathways in central metabolism as well as a more complete study involving 36 pathways common in all nine species. Our results indicate that reaction alignment with enzyme sequence similarity results in a more accurate representation of pathway specific cross-species similarities and differences based on NCBI taxonomy.

  3. Enzyme sequence similarity improves the reaction alignment method for cross-species pathway comparison

    International Nuclear Information System (INIS)

    Ovacik, Meric A.; Androulakis, Ioannis P.

    2013-01-01

    Pathway-based information has become an important source of information for both establishing evolutionary relationships and understanding the mode of action of a chemical or pharmaceutical among species. Cross-species comparison of pathways can address two broad questions: comparison in order to inform evolutionary relationships and to extrapolate species differences used in a number of different applications including drug and toxicity testing. Cross-species comparison of metabolic pathways is complex as there are multiple features of a pathway that can be modeled and compared. Among the various methods that have been proposed, reaction alignment has emerged as the most successful at predicting phylogenetic relationships based on NCBI taxonomy. We propose an improvement of the reaction alignment method by accounting for sequence similarity in addition to reaction alignment method. Using nine species, including human and some model organisms and test species, we evaluate the standard and improved comparison methods by analyzing glycolysis and citrate cycle pathways conservation. In addition, we demonstrate how organism comparison can be conducted by accounting for the cumulative information retrieved from nine pathways in central metabolism as well as a more complete study involving 36 pathways common in all nine species. Our results indicate that reaction alignment with enzyme sequence similarity results in a more accurate representation of pathway specific cross-species similarities and differences based on NCBI taxonomy

  4. Parallel proton transfer pathways in aqueous acid-base reactions

    NARCIS (Netherlands)

    Cox, M.J.; Bakker, H.J.

    2008-01-01

    We study the mechanism of proton transfer (PT) between the photoacid 8-hydroxy-1,3, 6-pyrenetrisulfonic acid (HPTS) and the base chloroacetate in aqueous solution. We investigate both proton and deuteron transfer reactions in solutions with base concentrations ranging from 0.25M to 4M. Using

  5. Subcritical hydrothermal conversion of organic wastes and biomass. Reaction pathways

    Directory of Open Access Journals (Sweden)

    Alejandro Amadeus Castro Vega

    2007-01-01

    Full Text Available Hydrothermal conversion is a procedure which emulates organic matter’s natural conversion into bio-crude having physical and chemical properties analogous to petroleum. The artificial transformation of biomass requi- res previous knowledge of the main reaction routes and product availability. The main component of biomass (depolymerisation by hydrolysis is presented in hydrothermal cellulose conversion, producing oligosaccharides which exhibit dehydration and retro-aldol condensation reactions for transforming into furfurals and carboxylic acids. Other biomass components (such as lignin, proteins, and fat esters present both hydrolysis and pyrolysis reaction routes. As long as biomass mainly contains carbohydrates, subcritical hydrothermal conversion products and their wastes will be fundamentally analogous to those displaying cellulose. These substances have added- value by far surpassing raw material’s acquisition cost. When the main hydrothermal conversion products’ O/C, H/C molar ratios as reported in literature are plotted, an evolutionary tralectory for conversion products appears to be closely or even overlapped with fossil fuels’ geological evolution.

  6. On the deduction of chemical reaction pathways from measurements of time series of concentrations.

    Science.gov (United States)

    Samoilov, Michael; Arkin, Adam; Ross, John

    2001-03-01

    We discuss the deduction of reaction pathways in complex chemical systems from measurements of time series of chemical concentrations of reacting species. First we review a technique called correlation metric construction (CMC) and show the construction of a reaction pathway from measurements on a part of glycolysis. Then we present two new improved methods for the analysis of time series of concentrations, entropy metric construction (EMC), and entropy reduction method (ERM), and illustrate (EMC) with calculations on a model reaction system. (c) 2001 American Institute of Physics.

  7. Molecular extinction coefficients of lead sulfide and polymerized diaminobenzidine as final reaction products of histochemical phosphatase reactions

    NARCIS (Netherlands)

    van Noorden, C. J.; Jonges, G. N.

    1992-01-01

    Molar extinction coefficients of precipitated lead sulfide (PbS) and polymerized diaminobenzidine (polyDAB) have been determined at wavelengths of 450 nm and 480 nm, respectively, for quantitative histochemical analysis of phosphatase reactions. These values are essential for the conversion of

  8. Effects of reaction-kinetic parameters on modeling reaction pathways in GaN MOVPE growth

    Science.gov (United States)

    Zhang, Hong; Zuo, Ran; Zhang, Guoyi

    2017-11-01

    In the modeling of the reaction-transport process in GaN MOVPE growth, the selections of kinetic parameters (activation energy Ea and pre-exponential factor A) for gas reactions are quite uncertain, which cause uncertainties in both gas reaction path and growth rate. In this study, numerical modeling of the reaction-transport process for GaN MOVPE growth in a vertical rotating disk reactor is conducted with varying kinetic parameters for main reaction paths. By comparisons of the molar concentrations of major Ga-containing species and the growth rates, the effects of kinetic parameters on gas reaction paths are determined. The results show that, depending on the values of the kinetic parameters, the gas reaction path may be dominated either by adduct/amide formation path, or by TMG pyrolysis path, or by both. Although the reaction path varies with different kinetic parameters, the predicted growth rates change only slightly because the total transport rate of Ga-containing species to the substrate changes slightly with reaction paths. This explains why previous authors using different chemical models predicted growth rates close to the experiment values. By varying the pre-exponential factor for the amide trimerization, it is found that the more trimers are formed, the lower the growth rates are than the experimental value, which indicates that trimers are poor growth precursors, because of thermal diffusion effect caused by high temperature gradient. The effective order for the contribution of major species to growth rate is found as: pyrolysis species > amides > trimers. The study also shows that radical reactions have little effect on gas reaction path because of the generation and depletion of H radicals in the chain reactions when NH2 is considered as the end species.

  9. A method for integrating and ranking the evidence for biochemical pathways by mining reactions from text

    Science.gov (United States)

    Miwa, Makoto; Ohta, Tomoko; Rak, Rafal; Rowley, Andrew; Kell, Douglas B.; Pyysalo, Sampo; Ananiadou, Sophia

    2013-01-01

    Motivation: To create, verify and maintain pathway models, curators must discover and assess knowledge distributed over the vast body of biological literature. Methods supporting these tasks must understand both the pathway model representations and the natural language in the literature. These methods should identify and order documents by relevance to any given pathway reaction. No existing system has addressed all aspects of this challenge. Method: We present novel methods for associating pathway model reactions with relevant publications. Our approach extracts the reactions directly from the models and then turns them into queries for three text mining-based MEDLINE literature search systems. These queries are executed, and the resulting documents are combined and ranked according to their relevance to the reactions of interest. We manually annotate document-reaction pairs with the relevance of the document to the reaction and use this annotation to study several ranking methods, using various heuristic and machine-learning approaches. Results: Our evaluation shows that the annotated document-reaction pairs can be used to create a rule-based document ranking system, and that machine learning can be used to rank documents by their relevance to pathway reactions. We find that a Support Vector Machine-based system outperforms several baselines and matches the performance of the rule-based system. The success of the query extraction and ranking methods are used to update our existing pathway search system, PathText. Availability: An online demonstration of PathText 2 and the annotated corpus are available for research purposes at http://www.nactem.ac.uk/pathtext2/. Contact: makoto.miwa@manchester.ac.uk Supplementary information: Supplementary data are available at Bioinformatics online. PMID:23813008

  10. The Photoconversion of Phytochrome Includes an Unproductive Shunt Reaction Pathway.

    Science.gov (United States)

    Buhrke, David; Kuhlmann, Uwe; Michael, Norbert; Hildebrandt, Peter

    2018-03-05

    Phytochromes are modular bimodal photoswitches that control gene expression for morphogenetic processes in plants. These functions are triggered by photoinduced conversions between the inactive and active states of the photosensory module, denoted as Pr and Pfr, respectively. In the present time-resolved resonance Raman spectroscopic study of bacterial representatives of this photoreceptor family, we demonstrate that these phototransformations do not represent linear processes but include a branching reaction back to the initial state, prior to (de)activation of the output module. Thus, only a fraction of the photoreceptors undergoing the phototransformations can initiate the downstream signaling process, consistent with phytochrome's function as a sensor for more durable changes of light conditions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Removing antimony from waste lead storage batteries alloy by vacuum displacement reaction technology.

    Science.gov (United States)

    Liu, Tiantian; Qiu, Keqiang

    2018-04-05

    With the wide application of lead acid battery, spent lead acid battery has become a serious problem to environmental protection and human health. Though spent battery can be a contaminant if not handled properly, it is also an important resource to obtain refined lead. Nowadays, the Sb-content in lead storage batteries is about 0.5-3 wt%, which is higher than the Sb-content in the crude lead. However, there are few reports about the process of removing antimony from high-antimony lead bullion. In this study, vacuum displacement reaction technology, a new process for removing antimony from high-antimony lead melts, was investigated. During this process, lead oxide was added to the system and antimony from lead melts was converted into antimony trioxide, which easily was evaporated under vacuum so that antimony was removed from lead melts. The experimental results demonstrated that Sb-content in lead melts decreased from 2.5% to 23 ppm under following conditions: mass ratio of PbO/lead bullion of 0.33, residual gas pressure of 30 Pa, melt temperature of 840 °C, reaction time of 60 min. The distillate gotten can be used as by-product to produce antimony white. Moreover, this study is of importance to recycling of waste lead storage batteries alloy. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Automated pathway and reaction prediction facilitates in silico identification of unknown metabolites in human cohort studies.

    Science.gov (United States)

    Quell, Jan D; Römisch-Margl, Werner; Colombo, Marco; Krumsiek, Jan; Evans, Anne M; Mohney, Robert; Salomaa, Veikko; de Faire, Ulf; Groop, Leif C; Agakov, Felix; Looker, Helen C; McKeigue, Paul; Colhoun, Helen M; Kastenmüller, Gabi

    2017-12-15

    Identification of metabolites in non-targeted metabolomics continues to be a bottleneck in metabolomics studies in large human cohorts. Unidentified metabolites frequently emerge in the results of association studies linking metabolite levels to, for example, clinical phenotypes. For further analyses these unknown metabolites must be identified. Current approaches utilize chemical information, such as spectral details and fragmentation characteristics to determine components of unknown metabolites. Here, we propose a systems biology model exploiting the internal correlation structure of metabolite levels in combination with existing biochemical and genetic information to characterize properties of unknown molecules. Levels of 758 metabolites (439 known, 319 unknown) in human blood samples of 2279 subjects were measured using a non-targeted metabolomics platform (LC-MS and GC-MS). We reconstructed the structure of biochemical pathways that are imprinted in these metabolomics data by building an empirical network model based on 1040 significant partial correlations between metabolites. We further added associations of these metabolites to 134 genes from genome-wide association studies as well as reactions and functional relations to genes from the public database Recon 2 to the network model. From the local neighborhood in the network, we were able to predict the pathway annotation of 180 unknown metabolites. Furthermore, we classified 100 pairs of known and unknown and 45 pairs of unknown metabolites to 21 types of reactions based on their mass differences. As a proof of concept, we then looked further into the special case of predicted dehydrogenation reactions leading us to the selection of 39 candidate molecules for 5 unknown metabolites. Finally, we could verify 2 of those candidates by applying LC-MS analyses of commercially available candidate substances. The formerly unknown metabolites X-13891 and X-13069 were shown to be 2-dodecendioic acid and 9

  13. Reaction pathways of biomass-derived oxygenates on noble metal surfaces

    Science.gov (United States)

    McManus, Jesse R.

    As the global demand for energy continues to rise, the environmental concerns associated with increased fossil fuel consumption have motivated the use of biomass as an alternative, carbon-renewable energy feedstock. Controlling reactive chemistry of the sugars that comprise biomass through the use of catalysis becomes essential in effectively producing green fuels and value-added chemicals. Recent work on biomass conversion catalysts have demonstrated the efficacy of noble metal catalyst systems for the reforming of biomass to hydrogen fuel, and the hydrodeoxygenation of biomass-derived compounds to value-added chemicals. In particular, Pt and Pd surfaces have shown considerable promise as reforming catalysts in preliminary aqueous phase reforming studies. It becomes important to understand the mechanisms by which these molecules react on the catalyst surfaces in order to determine structure-activity relationships and bond scission energetics as to provide a framework for engineering more active and selective catalysts. Fundamental surface science techniques provide the tools to do this; however, work in this field has been so far limited to simple model molecules like ethanol and ethylene glycol. Herein, temperature programmed desorption and high resolution electron energy loss spectroscopy are utilized in an ultra-high vacuum surface science study of the biomass-derived sugar glucose on Pt and Pd single crystal catalysts. Overall, it was determined that the aldehyde function of a ring-open glucose molecule plays an integral part in the initial bonding and reforming reaction pathway, pointing to the use of aldoses glycolaldehyde and glyceraldehyde as the most appropriate model compounds for future studies. Furthermore, the addition of adatom Zn to a Pt(111) surface was found to significantly decrease the C-H and C-C bond scission activity in aldehyde containing compounds, resulting in a preferred deoxygenation pathway in opposition to the decarbonylation pathway

  14. Electrode Reaction Pathway in Oxide Anode for Solid Oxide Fuel Cells

    Science.gov (United States)

    Li, Wenyuan

    the electrolyte to change 3PB kinetics. Compared to Ni, Co doping activates the bulk oxygen more significantly, promoting the reaction at 2PB. The active surface reaction zone is found to be enlarged by the electrolyte with high oxygen activity (SSZ vs. YSZ) when charge transfer is one of the RDS. Due to the larger exchange current for charge transfer in 3PB with SSZ electrolyte, the adsorption gradient zone is broadened, leading to enhanced surface reaction kinetics. The potential application of such finding is demonstrated on SSZ/YSZ/SSZ sandwich, showing largely improved electrode performance, opening a wide door for the utilization of electrolytes that are too expensive, fragile or instable to be used before. The bulk path way in 2PB reaction can be affected by overpotential in terms of local vacancy concentration, built-in electrical field and stability. It is proven that an uneven distribution of lattice oxygen is established under operation conditions with overpotential by both qualitative analysis and analytic solution. An electrostatic field force is present besides the concentration gradient in the anode lattice to control the motion of oxygen ions. Compared to the usual estimation based on chemical diffusion mechanism, the real deviation of ionic defects concentration under polarization from the equilibrium state near electrode/electrolyte interface is smaller with the built-in electrical field. The overpotential is demonstrated to be able to open up or shut down the bulk pathway depending on the ionic defects of electrodes. The analysis on the bulk pathway in terms of local charged species and various potentials provides new insight in anion diffusion and electrode stability.

  15. Metabolic control analysis of biochemical pathways based on a thermokinetic description of reaction rates

    DEFF Research Database (Denmark)

    Nielsen, Jens Bredal

    1997-01-01

    Metabolic control analysis is a powerful technique for the evaluation of flux control within biochemical pathways. Its foundation is the elasticity coefficients and the flux control coefficients (FCCs). On the basis of a thermokinetic description of reaction rates it is here shown...... that the elasticity coefficients can be calculated directly from the pool levels of metabolites at steady state. The only requirement is that one thermodynamic parameter be known, namely the reaction affinity at the intercept of the tangent in the inflection point of the curve of reaction rate against reaction...... of the thermokinetic description of reaction rates to include the influence of effecters. Here the reaction rate is written as a linear function of the logarithm of the metabolite concentrations. With this type of rate function it is shown that the approach of Delgado and Liao [Biochem. J. (1992) 282, 919-927] can...

  16. Relative importance of dissolved and food pathways for lead contamination in shrimp

    International Nuclear Information System (INIS)

    Boisson, F.; Cotret, O.; Teyssie, J.-L.; El-Baradeie, M.; Fowler, S.W.

    2003-01-01

    The relative importance of dissolved and food pathways and the influence of food type in the bioaccumulation and retention of lead in the shrimp Palaemonetes varians were examined using a radiotracer method. Shrimp were exposed to 210 Pb-labelled seawater or fed two types of 210 Pb-labelled food, viz. mussels or worms. The amount of radiotracer accumulated by shrimp was examined over a 7-day period, followed by a 1-month and a 7-day depuration period for the dissolved and food source, respectively. Steady state in the uptake was reached after 2 days exposure to dissolved lead, with a resultant estimated concentration factor of 98 ± 3. Transfer factors following ingestion of contaminated mussels and worms were lower than unity for both food types, with lead transfer from worms being significantly higher than that from mussels. Accumulation of dissolved Pb by shrimp was found to occur mainly through adsorption on the exoskeleton with a minor accumulation in the internal tissues probably resulting from the intake of seawater for osmoregulation. In contrast, lead taken up from contaminated food was readily absorbed and bound in the internal tissues of P. varians. Although the transfer of lead to P. varians through the ingestion of contaminated food was low (TF < 1%), it still represented 4 to 8% of the lead content in the prey which is a significant additional contribution of lead to the shrimp body burden. Independent of food type, following ingestion of contaminated food, approximately 23-27% of total lead accumulated in shrimp was located in the edible parts (e.g. muscle). Therefore, the food pathway is suggested to be a significant contributor to the lead transfer to humans through ingestion of contaminated shrimp. After exposure to contaminated food, lead loss kinetics were described by a two-component model, whereas Pb loss following direct uptake from seawater was best described by a three-component model. The additional compartment representing 64% of total Pb

  17. Relative importance of dissolved and food pathways for lead contamination in shrimp

    Energy Technology Data Exchange (ETDEWEB)

    Boisson, F.; Cotret, O.; Teyssie, J.-L.; El-Baradeie, M.; Fowler, S.W

    2003-12-01

    The relative importance of dissolved and food pathways and the influence of food type in the bioaccumulation and retention of lead in the shrimp Palaemonetes varians were examined using a radiotracer method. Shrimp were exposed to {sup 210}Pb-labelled seawater or fed two types of {sup 210}Pb-labelled food, viz. mussels or worms. The amount of radiotracer accumulated by shrimp was examined over a 7-day period, followed by a 1-month and a 7-day depuration period for the dissolved and food source, respectively. Steady state in the uptake was reached after 2 days exposure to dissolved lead, with a resultant estimated concentration factor of 98 {+-} 3. Transfer factors following ingestion of contaminated mussels and worms were lower than unity for both food types, with lead transfer from worms being significantly higher than that from mussels. Accumulation of dissolved Pb by shrimp was found to occur mainly through adsorption on the exoskeleton with a minor accumulation in the internal tissues probably resulting from the intake of seawater for osmoregulation. In contrast, lead taken up from contaminated food was readily absorbed and bound in the internal tissues of P. varians. Although the transfer of lead to P. varians through the ingestion of contaminated food was low (TF < 1%), it still represented 4 to 8% of the lead content in the prey which is a significant additional contribution of lead to the shrimp body burden. Independent of food type, following ingestion of contaminated food, approximately 23-27% of total lead accumulated in shrimp was located in the edible parts (e.g. muscle). Therefore, the food pathway is suggested to be a significant contributor to the lead transfer to humans through ingestion of contaminated shrimp. After exposure to contaminated food, lead loss kinetics were described by a two-component model, whereas Pb loss following direct uptake from seawater was best described by a three-component model. The additional compartment representing 64

  18. Study of the optimal reaction conditions for assay of the mouse alternative complement pathway

    NARCIS (Netherlands)

    Dijk, H. van; Rademaker, P.M.; Klerx, J.P.A.M.; Willers, J.M.M.

    1985-01-01

    The optimal reaction conditions for hemolytic assay of alternative complement pathway activity in mouse serum were investigated. A microtiter system was used, in which a number of 7.5×106 rabbit erythrocytes per test well appeared to be optimal. Rabbit erythrocytes were superior as target cells over

  19. Catalytic Hydrotreatment of Fast Pyrolysis Oil : Model Studies on Reaction Pathways for the Carbohydrate Fraction

    NARCIS (Netherlands)

    Wildschut, J.; Arentz, J.; Rasrendra, C. B.; Venderbosch, R. H.; Heeres, H. J.

    2009-01-01

    Fast pyrolysis oil can be upgraded by a catalytic hydrotreatment (250-400 degrees C, 100-200 bar) using heterogeneous catalysts such as Ru/C to hydrocarbon-like products that can serve as liquid transportation fuels. Insight into the complex reaction pathways of the various component fractions

  20. Chemical form of selenium differentially influences DNA repair pathways following exposure to lead nitrate.

    Science.gov (United States)

    McKelvey, Shauna M; Horgan, Karina A; Murphy, Richard A

    2015-01-01

    Lead, an environmental toxin is known to induce a broad range of physiological and biochemical dysfunctions in humans through a number of mechanisms including the deactivation of antioxidants thus leading to generation of reactive oxygen species (ROS) and subsequent DNA damage. Selenium on the other hand has been proven to play an important role in the protection of cells from free radical damage and oxidative stress, though its effects are thought to be form and dose dependent. As the liver is the primary organ required for metabolite detoxification, HepG2 cells were chosen to assess the protective effects of various selenium compounds following exposure to the genotoxic agent lead nitrate. Initially DNA damage was quantified using a comet assay, gene expression patterns associated with DNA damage and signalling were also examined using PCR arrays and the biological pathways which were most significantly affected by selenium were identified. Interestingly, the organic type selenium compounds (selenium yeast and selenomethionine) conferred protection against lead induced DNA damage in HepG2 cells; this is evident by reduction in the quantity of DNA present in the comet tail of cells cultured in their presence with lead. This trend also followed through the gene expression changes noted in DNA damage pathways analysed. These results were in contrast with those of inorganic sodium selenite which promoted lead induced DNA damage evident in both the comet assay results and the gene expression analysis. Over all this study provided valuable insights into the effects which various selenium compounds had on the DNA damage and signalling pathway indicating the potential for using organic forms of selenium such as selenium enriched yeast to protect against DNA damaging agents. Copyright © 2014 Elsevier GmbH. All rights reserved.

  1. Academic provenance: Investigation of pathways that lead students into the geosciences

    Science.gov (United States)

    Houlton, Heather R.

    Pathways that lead students into the geosciences as a college major have not been fully explored in the current literature, despite the recent studies on the "geoscience pipeline model." Anecdotal evidence suggests low quality geoscience curriculum in K-12 education, lack of visibility of the discipline and lack of knowledge about geoscience careers contribute to low geoscience enrollments at universities. This study investigated the reasons why college students decided to major in the geosciences. Students' interests, experiences, motivations and desired future careers were examined to develop a pathway model. In addition, self-efficacy was used to inform pathway analyses, as it is an influential factor in academic major and career choice. These results and interpretations have strong implications for recruitment and retention in academia and industry. A semi-structured interview protocol was developed, which was informed by John Flanagan's critical incident theory. The responses to this interview were used to identify common experiences that diverse students shared for reasons they became geoscience majors. Researchers used self-efficacy theory by Alfred Bandura to assess students' pathways. Seventeen undergraduate geoscience majors from two U.S. Midwest research universities were sampled for cross-comparison and analysis. Qualitative analyses led to the development of six categorical steps for the geoscience pathway. The six pathway steps are: innate attributes/interest sources, pre-college critical incidents, college critical incidents, current/near future goals, expected career attributes and desired future careers. Although, how students traversed through each step was unique for individuals, similar patterns were identified between different populations in our participants: Natives, Immigrants and Refugees. In addition, critical incidents were found to act on behavior in two different ways: to support and confirm decision-making behavior (supportive critical

  2. A facile and expedient one-pot three-component reaction leading to ...

    Indian Academy of Sciences (India)

    Sci. Vol. 124, No. 5, September 2012, pp. 1007–1012. c Indian Academy of Sciences. A facile and expedient one-pot three-component reaction leading to multifunctionalized stabilized phosphorus ylides. ZAHRA HASSANI. ∗ and ZEINAB ESFANDIARPOUR. Department of New Materials, International Center for Science, ...

  3. Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

    Energy Technology Data Exchange (ETDEWEB)

    Rojas-Chavez, H., E-mail: uu_gg_oo@yahoo.com.mx [Centro de Investigacion e Innovacion Tecnologica - IPN, Cerrada de CECATI s/n, Col. Santa Catarina, Del. Azcapotzalco (Mexico) and Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada - IPN, Legaria 694, Col. Irrigacion, Del. Miguel Hidalgo (Mexico); Reyes-Carmona, F. [Facultad de Quimica - UNAM, Circuito de la Investigacion Cientifica s/n, C.U. Del. Coyoacan (Mexico); Jaramillo-Vigueras, D. [Centro de Investigacion e Innovacion Tecnologica - IPN, Cerrada de CECATI s/n, Col. Santa Catarina, Del. Azcapotzalco (Mexico)

    2011-10-15

    Highlights: {yields} PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. {yields} During high-energy milling oxygen has to be chemically reduced from the lead oxide. {yields} Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature. Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.

  4. Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

    International Nuclear Information System (INIS)

    Rojas-Chavez, H.; Reyes-Carmona, F.; Jaramillo-Vigueras, D.

    2011-01-01

    Highlights: → PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. → During high-energy milling oxygen has to be chemically reduced from the lead oxide. → Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature. Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.

  5. Method of determining paper-deposited materials, eg. lead, by their reaction with radioactive krypton

    International Nuclear Information System (INIS)

    Tolgyessy, J.; Pruzinec, J.

    1976-01-01

    The invention claims a method of determining substances on a paper carrier based on the substance reaction with 85 Kr gas and the measurement of radioactivity of the kryptonate formed. Lead is shown as an example. Different amounts of lead acetate were deposited on Whatman 2 chromatographic paper as was an unknown sample of Pb salt. The paper was exposed to a 2.5 mCi 85 Kr atmosphere for 48 hours. The activity of the individual spots was then measured, a calibration curve established and the amount of lead in the analyzed sample read-out. (Ha)

  6. RhoA/ROCK Signaling Pathway Mediates Shuanghuanglian Injection-Induced Pseudo-allergic Reactions.

    Science.gov (United States)

    Han, Jiayin; Zhao, Yong; Zhang, Yushi; Li, Chunying; Yi, Yan; Pan, Chen; Tian, Jingzhuo; Yang, Yifei; Cui, Hongyu; Wang, Lianmei; Liu, Suyan; Liu, Jing; Deng, Nuo; Liang, Aihua

    2018-01-01

    Background: Shuanghuanglian injection (SHLI) is a famous Chinese medicine used as an intravenous preparation for the treatment of acute respiratory tract infections. In the recent years, the immediate hypersensitivity reactions induced by SHLI have attracted broad attention. However, the mechanism involved in these reactions has not yet been elucidated. The present study aims to explore the characteristics of the immediate hypersensitivity reactions induced by SHLI and deciphers the role of the RhoA/ROCK signaling pathway in these reactions. Methods: SHLI-immunized mice or naive mice were intravenously injected (i.v.) with SHLI (600 mg/kg) once, and vascular leakage in the ears was evaluated. Passive cutaneous anaphylaxis test was conducted using sera collected from SHLI-immunized mice. Naive mice were administered (i.v.) with a single dose of 150, 300, or 600 mg/kg of SHLI, and vascular leakage, histamine release, and histopathological alterations in the ears, lungs, and intestines were tested. In vitro , human umbilical vein endothelial cell (HUVEC) monolayer was incubated with SHLI (0.05, 0.1, or 0.15 mg/mL), and the changes in endothelial permeability and cytoskeleton were observed. Western blot analysis was performed and ROCK inhibitor was employed to investigate the contribution of the RhoA/ROCK signaling pathway in SHLI-induced hypersensitivity reactions, both in HUVECs and in mice. Results: Our results indicate that SHLI was able to cause immediate dose-dependent vascular leakage, edema, and exudates in the ears, lungs, and intestines, and histamine release in mice. These were pseudo-allergic reactions, as SHLI-specific IgE was not elicited during sensitization. In addition, SHLI induced reorganization of actin cytoskeleton and disrupted the endothelial barrier. The administration of SHLI directly activated the RhoA/ROCK signaling pathway both in HUVECs and in the ears, lungs, and intestines of mice. Fasudil hydrochloride, a ROCK inhibitor, ameliorated the

  7. Density Functional Theory Study of Competitive Reaction Pathways of Ti+ with Fluorinated Acetone in the Gas Phase

    International Nuclear Information System (INIS)

    Hong, Kiryong; Kim, Tae Kyu

    2012-01-01

    We investigate the doublet and quartet potential energy surfaces associated with the gas-phase reaction between Ti + and CF 3 COCH 3 for two plausible reaction pathways, TiF 2 + and TiO + formation pathways by using the density functional theory (DFT) method. The molecular structures of intermediates and transition states involved in these reaction pathways are optimized at the DFT level by using the PBE0 functional. All transition states are identified by using the intrinsic reaction coordinate (IRC) method, and the resulting reaction coordinates describe how Ti + activates CF 3 COCH 3 and produces TiF 2 + and TiO + as products. On the basis of presented results, we propose the most favorable reaction pathway in the reaction between Ti + and CF 3 COCH 3

  8. Evidence for leading mesons in anti p4He reactions at 0.6 GeV/c incident momentum

    International Nuclear Information System (INIS)

    Breivik, F.O.; Haatuft, A.; Halsteinslid, A.

    1990-05-01

    In a previous report, evidence has been shown for leading mesons in anti p Ne - reactions at 0.6 Gev/c incident momentum. In this report evidence is shown for leading mesons in anti p 4 He reactions at the same incident momentum, based on data from the same detector. In anti p Ne - reactions, only kaons are observed as leading mesons in K o s-events, and only pions are observed as leading mesons in Λ o -events. In anti p He - reactions this is not longer true, since also pions behave as leading mesons in K o s-events. 5 refs., 9 figs

  9. Reaction pathways for catalytic gas-phase oxidation of glycerol over mixed metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Suprun, W.; Glaeser, R.; Papp, H. [Leipzig Univ. (Germany). Inst. of Chemical Technology

    2011-07-01

    Glycerol as a main by-product from bio-diesel manufacture is a cheap raw material with large potential for chemical or biochemical transformations to value-added C3-chemicals. One possible way of glycerol utilization involves its catalytic oxidation to acrylic acid as an alternative to petrochemical routes. However, this catalytic conversion exhibits various problems such as harsh reaction conditions, severe catalyst coking and large amounts of undesired by-products. In this study, the reaction pathways for gas-phase conversion of glycerol over transition metal oxides (Mo, V und W) supported on TiO{sub 2} and SiO{sub 2} were investigated by two methods: (i) steady state experiments of glycerol oxidation and possible reactions intermediates, i.e., acrolein, 3-hydroxy propionaldehyde and acetaldehyde, and (ii) temperature-programmed surface reaction (TPSR) studies of glycerol conversion in the presence and in the absence of gas-phase oxygen. It is shown that the supported W-, V and Mo-oxides possess an ability to catalyze the oxidation of glycerol to acrylic acid. These investigations allowed us to gain a deeper insight into the reaction mechanism. Thus, based on the obtained results, three possible reactions pathways for the selective oxidation of glycerol to acrylic acid on the transition metal-containing catalysts are proposed. The major pathways in presence of molecular oxygen are a fast successive destructive oxidation of glycerol to CO{sub x} and the dehydration of glycerol to acrolein which is a rate-limiting step. (orig.)

  10. Exploring the Reaction Pathways of Bioglycerol Hydrodeoxygenation to Propene over Molybdena-Based Catalysts.

    Science.gov (United States)

    Zacharopoulou, Vasiliki; Vasiliadou, Efterpi S; Lemonidou, Angeliki A

    2018-01-10

    The one-step reaction of glycerol with hydrogen to form propene selectively is a particularly challenging catalytic pathway that has not yet been explored thoroughly. Molybdena-based catalysts are active and selective to C-O bond scission; propene is the only product in the gas phase under the standard reaction conditions, and further hydrogenation to propane is impeded. Within this context, this work focuses on the exploration of the reaction pathways and the investigation of various parameters that affect the catalytic performance, such as the role of hydrogen on the product distribution and the effect of the catalyst pretreatment step. Under a hydrogen atmosphere, propene is produced primarily via 2-propenol, whereas under an inert atmosphere propanal and glycerol dissociation products are formed mainly. The reaction most likely proceeds through a reverse Mars-van Krevelen mechanism as partially reduced Mo species drive the reaction to the formation of the desired product. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Products and stability of phosphate reactions with lead under freeze-thaw cycling in simple systems

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-15

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

  12. Products and stability of phosphate reactions with lead under freeze-thaw cycling in simple systems

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  13. Reaction pathways of model compounds of biomass-derived oxygenates on Fe/Ni bimetallic surfaces

    Science.gov (United States)

    Yu, Weiting; Chen, Jingguang G.

    2015-10-01

    Controlling the activity and selectivity of converting biomass-derivatives to fuels and valuable chemicals is critical for the utilization of biomass feedstocks. There are primarily three classes of non-food competing biomass, cellulose, hemicellulose and lignin. In the current work, glycolaldehyde, furfural and acetaldehyde are studied as model compounds of the three classes of biomass-derivatives. Monometallic Ni(111) and monolayer (ML) Fe/Ni(111) bimetallic surfaces are studied for the reaction pathways of the three biomass surrogates. The ML Fe/Ni(111) surface is identified as an efficient surface for the conversion of biomass-derivatives from the combined results of density functional theory (DFT) calculations and temperature programmed desorption (TPD) experiments. A correlation is also established between the optimized adsorption geometry and experimental reaction pathways. These results should provide helpful insights in catalyst design for the upgrading and conversion of biomass.

  14. Catalytic Hydrotreatment of Fast Pyrolysis Oil: Model Studies on Reaction Pathways for the Carbohydrate Fraction

    OpenAIRE

    Wildschut, J.; Arentz, J.; Rasrendra, C. B.; Venderbosch, R. H.; Heeres, H. J.

    2009-01-01

    Fast pyrolysis oil can be upgraded by a catalytic hydrotreatment (250-400 degrees C, 100-200 bar) using heterogeneous catalysts such as Ru/C to hydrocarbon-like products that can serve as liquid transportation fuels. Insight into the complex reaction pathways of the various component fractions during hydrotreatment is desirable to reduce the formation of by-products such as char and gaseous components. This paper deals with the catalytic hydrotreatment of representative model components for t...

  15. Fluid flow pathways through the oceanic crust: reaction permeability and isotopic tracing

    Science.gov (United States)

    McCaig, Andrew; Castelain, Teddy; Klein, Frieder

    2013-04-01

    It is generally assumed that the dominant means of creating permeability in ocean floor hydrothermal systems is fracturing, induced either by cooling or by tectonic stress. Here we show textural evidence that metamorphic reactions can create a hierarchy of permeable pathways through gabbroic rocks similar to a fracture hierarchy. Isotopic microsampling shows that just as with fractures, most flow occurs through the larger channelways, and that even at the microscale, flow can be extremely heterogeneous with alteration affecting only certain minerals in the framework, leaving others untouched. Reaction permeability is created in three ways; dissolution creating open porosity, microcracking due to volume increase reactions involving olivine, and expansion of water due to rapid heating in dyke margins, particularly when intruded into brecciated rocks. Our data comes from IODP Hole U1309D, which was drilled to 1400 mbsf in the footwall of the Atlantis Massif detachment fault at the Mid-Atlantic Ridge 30°N. The core is composed of gabbroic rocks interlayered with olivine rich troctolites, with several basalt/diabase sills in the top 130 m. The dominant alteration occurred in the greenschist facies, at depths at least 1 km below seafloor, and decreases in intensity downhole. Whole rock oxygen isotope values range from +5.5 permil to +1.5 permil, indicating variable degrees of interaction with seawater at temperatures generally > 250 °C. Gabbroic rocks and diabases exhibit a range of Sr isotope ratios from MORB values (0.70261) to intermediate ratios (0.70429). Microsampling shows that amphiboles are often more radiogenic than coexisting plagioclase and can sometimes be isotopically altered in the same rock as completely unaltered primary minerals. Large (10 cm) amphibole-filled vugs show values ranging up to 0.708, close to seawater. In some cases however the secondary minerals are virtually unaltered indicating low fluid fluxes in pervasive alteration. SEM textures in

  16. Lead (Pb) induced ATM-dependent mitophagy via PINK1/Parkin pathway.

    Science.gov (United States)

    Gu, Xueyan; Qi, Yongmei; Feng, Zengxiu; Ma, Lin; Gao, Ke; Zhang, Yingmei

    2018-07-01

    Lead (Pb), a widely distributed environmental pollutant, is known to induce mitochondrial damage as well as autophagy in vitro and in vivo. In this study, we found that Pb could trigger mitophagy in both HEK293 cells and the kidney cortex of male Kunming mice. However, whether ataxia telangiectasis mutated (ATM) which is reported to be linked with PTEN-induced putative kinase 1 (PINK1)/Parkin pathway (a well-characterized mitophagic pathway) participates in the regulation of Pb-induced mitophagy and its exact role remains enigmatic. Our results indicated that Pb activated ATM in vitro and in vivo, and further in vitro studies showed that ATM could co-localize with PINK1 and Parkin in cytosol and interact with PINK1. Knockdown of ATM by siRNA blocked Pb-induced mitophagy even under the circumstance of enhanced accumulation of PINK1 and mitochondrial Parkin. Intriguingly, elevation instead of reduction in phosphorylation level of PINK1 and Parkin was observed in response to ATM knockdown and Pb did not contribute to the further increase of their phosphorylation level, implying that ATM indirectly regulated PINK1/Parkin pathway. These findings reveal a novel mechanism for Pb toxicity and suggest the regulatory importance of ATM in PINK1/Parkin-mediated mitophagy. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Nitric oxide and nitrous oxide turnover in natural and engineered microbial communities: biological pathways, chemical reactions, and novel technologies

    Science.gov (United States)

    Schreiber, Frank; Wunderlin, Pascal; Udert, Kai M.; Wells, George F.

    2012-01-01

    Nitrous oxide (N2O) is an environmentally important atmospheric trace gas because it is an effective greenhouse gas and it leads to ozone depletion through photo-chemical nitric oxide (NO) production in the stratosphere. Mitigating its steady increase in atmospheric concentration requires an understanding of the mechanisms that lead to its formation in natural and engineered microbial communities. N2O is formed biologically from the oxidation of hydroxylamine (NH2OH) or the reduction of nitrite (NO−2) to NO and further to N2O. Our review of the biological pathways for N2O production shows that apparently all organisms and pathways known to be involved in the catabolic branch of microbial N-cycle have the potential to catalyze the reduction of NO−2 to NO and the further reduction of NO to N2O, while N2O formation from NH2OH is only performed by ammonia oxidizing bacteria (AOB). In addition to biological pathways, we review important chemical reactions that can lead to NO and N2O formation due to the reactivity of NO−2, NH2OH, and nitroxyl (HNO). Moreover, biological N2O formation is highly dynamic in response to N-imbalance imposed on a system. Thus, understanding NO formation and capturing the dynamics of NO and N2O build-up are key to understand mechanisms of N2O release. Here, we discuss novel technologies that allow experiments on NO and N2O formation at high temporal resolution, namely NO and N2O microelectrodes and the dynamic analysis of the isotopic signature of N2O with quantum cascade laser absorption spectroscopy (QCLAS). In addition, we introduce other techniques that use the isotopic composition of N2O to distinguish production pathways and findings that were made with emerging molecular techniques in complex environments. Finally, we discuss how a combination of the presented tools might help to address important open questions on pathways and controls of nitrogen flow through complex microbial communities that eventually lead to N2O build

  18. Nitric oxide and nitrous oxide turnover in natural and engineered microbial communities: biological pathways, chemical reactions and novel technologies

    Directory of Open Access Journals (Sweden)

    Frank eSchreiber

    2012-10-01

    Full Text Available Nitrous oxide (N2O is an environmentally important atmospheric trace gas because it is an effective greenhouse gas and it leads to ozone depletion through photo-chemical nitric oxide (NO production in the stratosphere. Mitigating its steady increase in atmospheric concentration requires an understanding of the mechanisms that lead to its formation in natural and engineered microbial communities. N2O is formed biologically from the oxidation of hydroxylamine (NH2OH or the reduction of nitrite (NO2- to NO and further to N2O. Our review of the biological pathways for N2O production shows that apparently all organisms and pathways known to be involved in the catabolic branch of microbial N-cycle have the potential to catalyze the reduction of NO2- to NO and the further reduction of NO to N2O, while N2O formation from NH2OH is only performed by ammonia oxidizing bacteria. In addition to biological pathways, we review important chemical reactions that can lead to NO and N2O formation due to the reactivity of NO2-, NH2OH and nitroxyl (HNO. Moreover, biological N2O formation is highly dynamic in response to N-imbalance imposed on a system. Thus, understanding NO formation and capturing the dynamics of NO and N2O build-up are key to understand mechanisms of N2O release. Here, we discuss novel technologies that allow experiments on NO and N2O formation at high temporal resolution, namely NO and N2O microelectrodes and the dynamic analysis of the isotopic signature of N2O with quantum cascade laser based absorption spectroscopy. In addition, we introduce other techniques that use the isotopic composition of N2O to distinguish production pathways and findings that were made with emerging molecular techniques in complex environments. Finally, we discuss how a combination of the presented tools might help to address important open questions on pathways and controls of nitrogen flow through complex microbial communities that eventually lead to N2O build-up.

  19. Position-specific isotope modeling of organic micropollutants transformation through different reaction pathways

    International Nuclear Information System (INIS)

    Jin, Biao; Rolle, Massimo

    2016-01-01

    The degradation of organic micropollutants occurs via different reaction pathways. Compound specific isotope analysis is a valuable tool to identify such degradation pathways in different environmental systems. We propose a mechanism-based modeling approach that provides a quantitative framework to simultaneously evaluate concentration as well as bulk and position-specific multi-element isotope evolution during the transformation of organic micropollutants. The model explicitly simulates position-specific isotopologues for those atoms that experience isotope effects and, thereby, provides a mechanistic description of isotope fractionation occurring at different molecular positions. To demonstrate specific features of the modeling approach, we simulated the degradation of three selected organic micropollutants: dichlorobenzamide (BAM), isoproturon (IPU) and diclofenac (DCF). The model accurately reproduces the multi-element isotope data observed in previous experimental studies. Furthermore, it precisely captures the dual element isotope trends characteristic of different reaction pathways as well as their range of variation consistent with observed bulk isotope fractionation. It was also possible to directly validate the model capability to predict the evolution of position-specific isotope ratios with available experimental data. Therefore, the approach is useful both for a mechanism-based evaluation of experimental results and as a tool to explore transformation pathways in scenarios for which position-specific isotope data are not yet available. - Highlights: • Mechanism-based, position-specific isotope modeling of micropollutants degradation. • Simultaneous description of concentration and primary and secondary isotope effects. • Key features of the model are demonstrated with three illustrative examples. • Model as a tool to explore reaction mechanisms and to design experiments. - We propose a modeling approach incorporating mechanistic information and

  20. Combustion modeling and kinetic rate calculations for a stoichiometric cyclohexane flame. 1. Major reaction pathways.

    Science.gov (United States)

    Zhang, Hongzhi R; Huynh, Lam K; Kungwan, Nawee; Yang, Zhiwei; Zhang, Shaowen

    2007-05-17

    The Utah Surrogate Mechanism was extended in order to model a stoichiometric premixed cyclohexane flame (P = 30 Torr). Generic rates were assigned to reaction classes of hydrogen abstraction, beta scission, and isomerization, and the resulting mechanism was found to be adequate in describing the combustion chemistry of cyclohexane. Satisfactory results were obtained in comparison with the experimental data of oxygen, major products and important intermediates, which include major soot precursors of C2-C5 unsaturated species. Measured concentrations of immediate products of fuel decomposition were also successfully reproduced. For example, the maximum concentrations of benzene and 1,3-butadiene, two major fuel decomposition products via competing pathways, were predicted within 10% of the measured values. Ring-opening reactions compete with those of cascading dehydrogenation for the decomposition of the conjugate cyclohexyl radical. The major ring-opening pathways produce 1-buten-4-yl radical, molecular ethylene, and 1,3-butadiene. The butadiene species is formed via beta scission after a 1-4 internal hydrogen migration of 1-hexen-6-yl radical. Cascading dehydrogenation also makes an important contribution to the fuel decomposition and provides the exclusive formation pathway of benzene. Benzene formation routes via combination of C2-C4 hydrocarbon fragments were found to be insignificant under current flame conditions, inferred by the later concentration peak of fulvene, in comparison with benzene, because the analogous species series for benzene formation via dehydrogenation was found to be precursors with regard to parent species of fulvene.

  1. Effects of Water Molecule on CO Oxidation by OH: Reaction Pathways, Kinetic Barriers, and Rate Constants.

    Science.gov (United States)

    Zhang, Linyao; Yang, Li; Zhao, Yijun; Zhang, Jiaxu; Feng, Dongdong; Sun, Shaozeng

    2017-07-06

    The water dilute oxy-fuel combustion is a clean combustion technology for near-zero emission power; and the presence of water molecule could have both kinetic and dynamic effects on combustion reactions. The reaction OH + CO → CO 2 + H, one of the most important elementary reactions, has been investigated by extensive electronic structure calculations. And the effects of a single water molecule on CO oxidation have been studied by considering the preformed OH(H 2 O) complex reacts with CO. The results show little change in the reaction pathways, but the additional water molecule actually increases the vibrationally adiabatic energy barriers (V a G ). Further thermal rate constant calculations in the temperature range of 200 to 2000 K demonstrate that the total low-pressure limit rate constant for the water assisted OH(H 2 O) + CO → CO 2 + H 2 O + H reaction is 1-2 orders lower than that of the water unassisted one, which is consistent with the change of V a G . Therefore, the hydrated radical OH(H 2 O) would actually slow down the oxidation of CO. Meanwhile, comparisons show that the M06-2X/aug-cc-pVDZ method gives a much better estimation in energy and thus is recommended to be employed for direct dynamics simulations.

  2. Degradation of ibuprofen by hydrodynamic cavitation: Reaction pathways and effect of operational parameters.

    Science.gov (United States)

    Musmarra, Dino; Prisciandaro, Marina; Capocelli, Mauro; Karatza, Despina; Iovino, Pasquale; Canzano, Silvana; Lancia, Amedeo

    2016-03-01

    Ibuprofen (IBP) is an anti-inflammatory drug whose residues can be found worldwide in natural water bodies resulting in harmful effects to aquatic species even at low concentrations. This paper deals with the degradation of IBP in water by hydrodynamic cavitation in a convergent-divergent nozzle. Over 60% of ibuprofen was degraded in 60 min with an electrical energy per order (EEO) of 10.77 kWh m(-3) at an initial concentration of 200 μg L(-1) and a relative inlet pressure pin=0.35 MPa. Five intermediates generated from different hydroxylation reactions were identified; the potential mechanisms of degradation were sketched and discussed. The reaction pathways recognized are in line with the relevant literature, both experimental and theoretical. By varying the pressure upstream the constriction, different degradation rates were observed. This effect was discussed according to a numerical simulation of the hydroxyl radical production identifying a clear correspondence between the maximum kinetic constant kOH and the maximum calculated OH production. Furthermore, in the investigated experimental conditions, the pH parameter was found not to affect the extent of degradation; this peculiar feature agrees with a recently published kinetic insight and has been explained in the light of the intermediates of the different reaction pathways. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Pathways leading to self-perceived general health and overall quality of life in burned adults.

    Science.gov (United States)

    Moi, Asgjerd L; Nilsen, Roy M

    2012-12-01

    The aim of the study was to explore pathways leading to self-perceived general health and overall quality of life in burn patients. Data on burn-specific health, generic health, overall quality of life, injury characteristics and socio-demographics were obtained from 95 adult burn patients 47.0 (23.8) [mean (SD)] months after injury. A theoretical path model was established based on the concepts of Wilson and Cleary's model on health-related quality of life [1], and the proposed model was examined by structural equation modelling. Two main paths were identified, one leading to general health perception and the other leading to overall quality of life. Together, direct and indirect paths explained 63% of the variance of perceived general health and 43% of the variance in overall quality of life. The total effects of the SF-36 domain Vitality on perceived general health and overall quality of life were 0.62 and 0.66, respectively. No statistically significant path could be revealed between general health perception and overall quality of life. The results indicate that self-perceived general health and overall quality of life are related but distinct constructs. Moreover, vitality seems to be an important factor for the perception of both general health and overall quality of life in burned adults. Copyright © 2012 Elsevier Ltd and ISBI. All rights reserved.

  4. Pacing Lead-Induced Granuloma in the Atrium: A Foreign Body Reaction to Polyurethane

    Directory of Open Access Journals (Sweden)

    Shinagawa Yoko

    2013-01-01

    Full Text Available We described a case of an 82-year-old male who presented with a granuloma entrapping the polyurethane-coated pacing lead at the site of contact on the atrium. He had been paced for 8 years without symptoms or signs suggestive of an allergic reaction to the pacemaker system and died from thrombosis of the superior mesenteric artery and heart failure. A histological examination of the nodule showed an incidental granuloma with multinucleated giant cells. No granuloma was found in the heart or the lung.

  5. Insulin regulates multiple signaling pathways leading to monocyte/macrophage chemotaxis into the wound tissue

    Directory of Open Access Journals (Sweden)

    Yan Liu

    2018-01-01

    Full Text Available Wound healing is a complex process that involves sequential phases that overlap in time and space and affect each other dynamically at the gene and protein levels. We previously showed that insulin accelerates wound healing by stimulating faster and regenerative healing. One of the processes that insulin stimulates is an increase in monocyte/macrophage chemotaxis. In this study, we performed experiments in vivo and in vitro to elucidate the signaling transduction pathways that are involved in insulin-induced monocyte/macrophage chemotaxis. We found that insulin stimulates THP-1 cell chemotaxis in a dose-dependent and insulin receptor-dependent manner. We also show that the kinases PI3K-Akt, SPAK/JNK, and p38 MAPK are key molecules in the insulin-induced signaling pathways that lead to chemoattraction of the THP-1 cell. Furthermore, both PI3K-Akt and SPAK/JNK signaling involve Rac1 activation, an important molecule in regulating cell motility. Indeed, topical application of Rac1 inhibitor at an early stage during the healing process caused delayed and impaired healing even in the presence of insulin. These results delineate cell and molecular mechanisms involved in insulin-induced chemotaxis of monocyte/macrophage, cells that are critical for proper healing.

  6. Competing retention pathways of uranium upon reaction with Fe(II)

    Science.gov (United States)

    Massey, Michael S.; Lezama-Pacheco, Juan S.; Jones, Morris E.; Ilton, Eugene S.; Cerrato, José M.; Bargar, John R.; Fendorf, Scott

    2014-10-01

    Biogeochemical retention processes, including adsorption, reductive precipitation, and incorporation into host minerals, are important in contaminant transport, remediation, and geologic deposition of uranium. Recent work has shown that U can become incorporated into iron (hydr)oxide minerals, with a key pathway arising from Fe(II)-induced transformation of ferrihydrite, (Fe(OH)3·nH2O) to goethite (α-FeO(OH)); this is a possible U retention mechanism in soils and sediments. Several key questions, however, remain unanswered regarding U incorporation into iron (hydr)oxides and this pathway's contribution to U retention, including: (i) the competitiveness of U incorporation versus reduction to U(IV) and subsequent precipitation of UO2; (ii) the oxidation state of incorporated U; (iii) the effects of uranyl aqueous speciation on U incorporation; and, (iv) the mechanism of U incorporation. Here we use a series of batch reactions conducted at pH ∼7, [U(VI)] from 1 to 170 μM, [Fe(II)] from 0 to 3 mM, and [Ca] at 0 or 4 mM coupled with spectroscopic examination of reaction products of Fe(II)-induced ferrihydrite transformation to address these outstanding questions. Uranium retention pathways were identified and quantified using extended X-ray absorption fine structure (EXAFS) spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. Analysis of EXAFS spectra showed that 14-89% of total U was incorporated into goethite, upon reaction with Fe(II) and ferrihydrite. Uranium incorporation was a particularly dominant retention pathway at U concentrations ⩽50 μM when either uranyl-carbonato or calcium-uranyl-carbonato complexes were dominant, accounting for 64-89% of total U. With increasing U(VI) and Fe(II) concentrations, U(VI) reduction to U(IV) became more prevalent, but U incorporation remained a functioning retention pathway. These findings highlight the potential importance of U(V) incorporation within iron

  7. An Alternative Reaction Pathway for Iridium Catalyzed Water Oxidation Driven by CAN

    KAUST Repository

    Bucci, Alberto

    2016-06-10

    The generation of solar fuels by means of a photosynthetic apparatus strongly relies on the development of an efficient water oxidation catalyst (WOC). Cerium ammonium nitrate (CAN) is the most commonly used sacrificial oxidant to explore the potentiality of WOCs. It is usually assumed that CAN has the unique role to oxidatively energize WOCs, making them capable to offer a low energy reaction pathway to transform H2O to O2. Herein we show that CAN might have a much more relevant and direct role in WO, mainly related to the capture and liberation of O–O containing molecular moieties.

  8. An Alternative Reaction Pathway for Iridium Catalyzed Water Oxidation Driven by CAN

    KAUST Repository

    Bucci, Alberto; Menendez Rodriguez, Gabriel; Bellachioma, Gianfranco; Zuccaccia, Cristiano; Poater, Albert; Cavallo, Luigi; Macchioni, Alceo

    2016-01-01

    The generation of solar fuels by means of a photosynthetic apparatus strongly relies on the development of an efficient water oxidation catalyst (WOC). Cerium ammonium nitrate (CAN) is the most commonly used sacrificial oxidant to explore the potentiality of WOCs. It is usually assumed that CAN has the unique role to oxidatively energize WOCs, making them capable to offer a low energy reaction pathway to transform H2O to O2. Herein we show that CAN might have a much more relevant and direct role in WO, mainly related to the capture and liberation of O–O containing molecular moieties.

  9. Heterogeneous reaction of particulate chlorpyrifos with NO3 radicals: Products, pathways, and kinetics

    Science.gov (United States)

    Li, Nana; Zhang, Peng; Yang, Bo; Shu, Jinian; Wang, Youfeng; Sun, Wanqi

    2014-08-01

    Chlorpyrifos is a typical chlorinated organophosphorus pesticide. The heterogeneous reaction of chlorpyrifos particles with NO3 radicals was investigated using a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and a real-time atmospheric gas analysis mass spectrometer. Chlorpyrifos oxon, 3,5,6-trichloro-2-pyridinol, O,O-diethyl O-hydrogen phosphorothioate, O,O-diethyl ester thiophosphoric acid, diethyl hydrogen phosphate and a phosphinyl disulfide compound were identified as the main degradation products. The heterogeneous reaction pathways were proposed and their kinetic processes were investigated via a mixed-phase relative rate method. The observed effective rate constant is 3.4 ± 0.2 × 10-12 cm3 molecule-1 s-1.

  10. Elementary steps and reaction pathways in the aqueous phase alkylation of phenol with ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Eckstein, Sebastian; Hintermeier, Peter H.; Olarte, Mariefel V.; Liu, Yue; Baráth, Eszter; Lercher, Johannes A.

    2017-08-01

    The hydronium ion normalized reaction rate in aqueous phase alkylation of phenol with ethanol on H-MFI zeolites increases with decreasing concentration of acid sites. Higher rates are caused by higher concentrations of phenol in the zeolite pores, as the concentration of hydronium ions generated by zeolite Brønsted acid sites decreases. Considering the different concentrations of reacting species it is shown that the intrinsic rate constant for alkylation is independent of the concentration of hydronium ions in the zeolite pores. Alkylation at the aromatic ring of phenol and of toluene as well as O-alkylation of phenol have the same activation energy, 104 ± 5 kJ/mol. This is energetic barrier to form the ethyl carbenium ion from ethanol associated to the hydronium ion. Thus, in both the reaction pathways the catalyst involves a carbenium ion, which forms a bond to a nucleophilic oxygen (ether formation) or carbon (alkylation).

  11. THE ADVERSE OUTCOME PATHWAY (AOP) FRAMEWORK: A FRAMEWORK FOR ORGANIZING BIOLOGICAL KNOWLEDGE LEADING TO HEALTH RISKS.

    Science.gov (United States)

    An Adverse Outcome Pathway (AOP) represents the organization of current and newly acquired knowledge of biological pathways. These pathways contain a series of nodes (Key Events, KEs) that when sufficiently altered influence the next node on the pathway, beginning from an Molecul...

  12. Reaction Pathways in Catechol/Primary Amine Mixtures: A Window on Crosslinking Chemistry.

    Directory of Open Access Journals (Sweden)

    Juan Yang

    Full Text Available Catechol chemistry is used as a crosslinking tool abundantly in both natural organisms (e.g. mussels, sandcastle worms and synthetic systems to achieve the desired mechanical properties. Despite this abundance and success, the crosslinking chemistry is still poorly understood. In this study, to simplify the system, yet to capture the essential chemistry, model compounds 4-methyl catechol and propylamine are used. The reaction of 4-methyl catechol (2 mM with propylamine (6 mM is carried out in the presence of NaIO4 (2 mM in 10 mM Na2CO3 aqueous solution. A variety of spectroscopic/spectrometric and chromatographic methods such as 1H NMR, LC-MS, and UV-VIS are used to track the reaction and identify the products/intermediates. It is found that the crosslinking chemistry of a catechol and an amine is both fast and complicated. Within five minutes, more than 60 products are formed. These products encompass 19 different masses ranging from molecular weight of 179 to 704. By combining time-dependent data, it is inferred that the dominant reaction pathways: the majority is formed via aryloxyl-phenol coupling and Michael-type addition, whereas a small fraction of products is formed via Schiff base reactions.

  13. Electrophilic properties of patulin. Adduct structures and reaction pathways with 4-bromothiophenol and other model nucleophiles.

    Science.gov (United States)

    Fliege, R; Metzler, M

    2000-05-01

    The mycotoxin patulin (PAT) is believed to exert its cytotoxic and chromosome-damaging effects by forming covalent adducts with essential cellular thiols. Since the chemical structures of such adducts are unknown to date, we have studied the reaction of PAT and its O-acetylated derivative with the monofunctional thiol model compound 4-bromothiophenol (BTP), which was chosen due to analytical advantages. By means of analytical and preparative high-performance liquid chromatography, 16 adducts of PAT and 3 adducts of acetyl-PAT were isolated and their chemical structures elucidated by (1)H and (13)C NMR, IR, and UV spectroscopy. Time course studies and analysis of daughter product formation from isolated intermediate adducts led to a detailed scheme for the reaction of PAT with BTP. The structures of adducts of PAT formed with other model nucleophiles, e. g., the aliphatic thiol 2-mercaptoethanol and the aromatic amine 4-bromoaniline, were also elucidated and found to corroborate the reaction scheme. In addition, one further reaction pathway was observed with 2-mercaptoethanol, which appears to be independent from those found for BTP. Our study with model nucleophiles provides insights into the electrophilic reactivity of PAT and proved to be useful for the structure elucidation of PAT adducts with biological nucleophiles of toxicological relevance, as will be reported by Fliege and Metzler [(2000) Chem. Res. Toxicol. 13, 373-381].

  14. MAPKs are essential upstream signaling pathways in proteolytic cartilage degradation--divergence in pathways leading to aggrecanase and MMP-mediated articular cartilage degradation

    DEFF Research Database (Denmark)

    Sondergaard, B-C; Schultz, N; Madsen, S H

    2010-01-01

    Matrix metalloproteinases (MMPs) and aggrecanases are essential players in cartilage degradation. However, the signaling pathways that results in MMP and/or aggrecanase synthesis and activation are not well understood. We investigated the molecular events leading to MMP- and aggrecanase-mediated ......Matrix metalloproteinases (MMPs) and aggrecanases are essential players in cartilage degradation. However, the signaling pathways that results in MMP and/or aggrecanase synthesis and activation are not well understood. We investigated the molecular events leading to MMP- and aggrecanase......-mediated cartilage degradation....

  15. Integrated GWAS and Pathway profiling for feed efficiency traits in pigs leads to novel genes and their molecular pathways

    DEFF Research Database (Denmark)

    Do, Duy Ngoc; Ostersen, Tage; Strathe, Anders Bjerring

    2013-01-01

    Genome wide association studies (GWAS) are being extensively used in revealing genetic architecture of complex traits. However, GWAS offer limited understanding of the biological role of significant single nucleotide polymorphisms (SNPs) affecting complex traits. Pathway analysis using GWAS results...... is an important step where we firstly detect genes located near GWAS-detected SNPs and subsequently we detect enrichment of these genes in various biological processes and pathways. The objective of this study was to apply these steps to identify relevant pathways involved in residual feed intake (RFI) in pigs....... Residual feed intake is a feed efficiency measure and is highly economically important in animal production. In our study, a total of 596 Yorkshire boars had phenotypic and genotypic records. After quality control, 37,915 SNPs were available for GWAS which was implemented in the DMU software package...

  16. Reaction pathway and oxidation mechanisms of dibutyl phthalate by persulfate activated with zero-valent iron

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huanxuan [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, China, Guangzhou 510640 (China); Wan, Jinquan, E-mail: ppjqwan@scut.edu.cn [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, China, Guangzhou 510640 (China); State Key Lab Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Ma, Yongwen [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, China, Guangzhou 510640 (China); State Key Lab Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Wang, Yan [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, China, Guangzhou 510640 (China)

    2016-08-15

    This study investigated reaction pathway and oxidation mechanisms of dibutyl phthalate (DBP) by persulfate (PS) activated with zero-valent iron (ZVI). The DBP degradation was studied at three pH values (acidic, neutral and basic) in the presence of different organic scavengers. Using a chemical probe method, both sulfate radical (SO{sub 4}·{sup −}) and hydroxyl radical (·OH) were found to be primary oxidants at pH 3.0 and pH 7.0, respectively while ·OH was the major specie to oxidize DBP at pH 11.0. A similar result was found in an experiment of Electron Spin Resonance spin-trapping where in addition to ·OH, superoxide radical (O{sub 2}·{sup −}) was detected at pH 11.0. The transformation of degradation products including dimethyl phthalate (DMP), diethyl phthalate (DEP), phthalic anhydride, and acetophenone exhibited diverse variation during the reaction processes. The phthalic anhydride concentration appeared to be maximum at all pHs. Another eleven intermediate products were also found at pH 3.0 by GC–MS and HPLC analysis, and their degradation mechanisms and pathways were proposed. It was suggested that dealkylation, hydroxylation, decarboxylation and hydrogen extraction were the dominant degradation mechanisms of DBP at pH 3.0. - Highlights: • Both SO{sub 4}{sup −}· and ·OH were found to be the major active species at pH 3.0 and pH 7.0. • ·OH and ·O2– were the primary oxidants pH 11.0. • The intermediate products were investigated as well as the degradation pathway. • Dealkylation, hydroxylation, decarboxylation, H-extraction were the major mechanisms.

  17. Conferring specificity in redox pathways by enzymatic thiol/disulfide exchange reactions.

    Science.gov (United States)

    Netto, Luis Eduardo S; de Oliveira, Marcos Antonio; Tairum, Carlos A; da Silva Neto, José Freire

    2016-01-01

    Thiol-disulfide exchange reactions are highly reversible, displaying nucleophilic substitutions mechanism (S(N)2 type). For aliphatic, low molecular thiols, these reactions are slow, but can attain million times faster rates in enzymatic processes. Thioredoxin (Trx) proteins were the first enzymes described to accelerate thiol-disulfide exchange reactions and their high reactivity is related to the high nucleophilicity of the attacking thiol. Substrate specificity in Trx is achieved by several factors, including polar, hydrophobic, and topological interactions through a groove in the active site. Glutaredoxin (Grx) enzymes also contain the Trx fold, but they do not share amino acid sequence similarity with Trx. A conserved glutathione binding site is a typical feature of Grx that can reduce substrates by two mechanisms (mono and dithiol). The high reactivity of Grx enzymes is related to the very acid pK(a) values of reactive Cys that plays roles as good leaving groups. Therefore, although distinct oxidoreductases catalyze similar thiol–disulfide exchange reactions, their enzymatic mechanisms vary. PDI and DsbA are two other oxidoreductases, but they are involved in disulfide bond formation, instead of disulfide reduction, which is related to the oxidative environment where they are found. PDI enzymes and DsbC are endowed with disulfide isomerase activity, which is related with their tetra-domain architecture. As illustrative description of specificity in thiol-disulfide exchange, redox aspects of transcription activation in bacteria, yeast, and mammals are presented in an evolutionary perspective. Therefore, thiol-disulfide exchange reactions play important roles in conferring specificity to pathways, a required feature for signaling.

  18. NMR studies of stock process water and reaction pathways in hydrothermal carbonization of furfural residue

    Directory of Open Access Journals (Sweden)

    Fen Yue

    2018-04-01

    Full Text Available Hydrothermal carbonization (HTC is a valuable approach to convert furfural residue (FR into carbon material. The prepared biochars are usually characterized comprehensively, while the stock process water still remains to be studied in detail. Herein, a NMR study of the main components in stock process water generated at different HTC reaction conditions was reported. Various qualitative and quantitative NMR techniques (1H and 13C NMR, 1H–1H COSY and 1H13C HSQC etc. especially 1D selective gradient total correlation spectroscopy (TOCSY NMR were strategically applied in the analysis of HTC stock process water. Without separation and purification, it was demonstrated that the main detectable compounds are 5-hydroxymethylfurfural, formic acid, methanol, acetic acid, levulinic acid, glycerol, hydroxyacetone and acetaldehyde in this complicate mixture. Furthermore, the relationship between the concentration of major products and the reaction conditions (180–240 °C at 8 h, and 1–24 h at 240 °C was established. Finally, reasonable reaction pathways for hydrothermal conversion of FR were proposed based on this result and our previously obtained characteristics of biochars. The routine and challenging NMR methods utilized here would be an alternative other than HPLC or GC for biomass conversion research and can be extended to more studies. Keywords: NMR, Hydrothermal carbonization, Furfural residue, Stock process water

  19. Interfacial Reaction of Sn-Ag-Cu Lead-Free Solder Alloy on Cu: A Review

    Directory of Open Access Journals (Sweden)

    Liu Mei Lee

    2013-01-01

    Full Text Available This paper reviews the function and importance of Sn-Ag-Cu solder alloys in electronics industry and the interfacial reaction of Sn-Ag-Cu/Cu solder joint at various solder forms and solder reflow conditions. The Sn-Ag-Cu solder alloys are examined in bulk and in thin film. It then examines the effect of soldering conditions to the formation of intermetallic compounds such as Cu substrate selection, structural phases, morphology evolution, the growth kinetics, temperature and time is also discussed. Sn-Ag-Cu lead-free solder alloys are the most promising candidate for the replacement of Sn-Pb solders in modern microelectronic technology. Sn-Ag-Cu solders could possibly be considered and adapted in miniaturization technologies. Therefore, this paper should be of great interest to a large selection of electronics interconnect materials, reliability, processes, and assembly community.

  20. Study on interfacial reaction between lead-free solders and alternative surface finishes

    International Nuclear Information System (INIS)

    Siti Rabiatul Aisha; Ourdjini, A.; Saliza Osman

    2007-01-01

    This study investigates the interfacial reactions occurring during reflow soldering between Sn-Ag-Cu lead-free solder and two surface finishes: electroless nickel/ immersion gold (ENIG) and immersion silver (IAg). The study focuses on interfacial reactions evolution and growth kinetics of intermetallic compounds (IMC) formed during soldering and isothermal ageing at 150 degree Celsius for up to 2000 hours. Optical and scanning electron microscopy were used to measure IMC thickness and examine the morphology of IMC respectively, whereas the IMC phases were identified by energy dispersive X-ray analysis (EDX). The results showed that the IMC formed on ENIG finish is thinner compared to that formed on IAg finish. For IAg surface finish, Cu 6 Sn 5 IMCs with scallop morphology are formed at the solder/ surface finish interface after reflow while a second IMC, Cu 3 Sn was formed between the copper and Cu 6 Sn 5 IMC after the isothermal ageing treatment. For ENIG surface finish both (Cu,Ni) 6 Sn 5 and (Ni,Cu) 3 Sn 4 are formed after soldering. Isothermal aging of the solder joints formed on ENIG finish was found to have a significant effect on the morphology of the intermetallics by transforming to more spherical and denser morphology in addition to increase i their thickness with increased ageing time. (author)

  1. Reaction pathways of producing and losing particles in atmospheric pressure methane nanosecond pulsed needle-plane discharge plasma

    Science.gov (United States)

    Zhao, Yuefeng; Wang, Chao; Li, Li; Wang, Lijuan; Pan, Jie

    2018-03-01

    In this work, a two-dimensional fluid model is built up to numerically investigate the reaction pathways of producing and losing particles in atmospheric pressure methane nanosecond pulsed needle-plane discharge plasma. The calculation results indicate that the electron collisions with CH4 are the key pathways to produce the neutral particles CH2 and CH as well as the charged particles e and CH3+. CH3, H2, H, C2H2, and C2H4 primarily result from the reactions between the neutral particles and CH4. The charge transfer reactions are the significant pathways to produce CH4+, C2H2+, and C2H4+. As to the neutral species CH and H and the charged species CH3+, the reactions between themselves and CH4 contribute to substantial losses of these particles. The ways responsible for losing CH3, H2, C2H2, and C2H4 are CH3 + H → CH4, H2 + CH → CH2 + H, CH4+ + C2H2 → C2H2+ + CH4, and CH4+ + C2H4 → C2H4+ + CH4, respectively. Both electrons and C2H4+ are consumed by the dissociative electron-ion recombination reactions. The essential reaction pathways of losing CH4+ and C2H2+ are the charge transfer reactions.

  2. The Protective Effect of Gangliosides on Lead (Pb)-Induced Neurotoxicity Is Mediated by Autophagic Pathways.

    Science.gov (United States)

    Meng, Hongtao; Wang, Lan; He, Junhong; Wang, Zhufeng

    2016-03-25

    Lead (Pb) is a ubiquitous environmental and industrial pollutant and can affect intelligence development and the learning ability and memory of children. Therefore, necessary measures should be taken to protect the central nervous system (CNS) from Pb toxicity. Gangliosides are sialic acid-containing glycosphingolipids that are constituents of mammalian cell membranes and are more abundantly expressed in the CNS. Studies have shown that gangliosides constitute a useful tool in the attempt to promote functional recovery of CNS and can reverse Pb-induced impairments of synaptic plasticity in rats. However, the detailed mechanisms have yet to be fully understood. In our present study, we tried to investigate the role of gangliosides in Pb-induced injury in hippocampus neurons and to further confirm the detailed mechanism. Our results show that Pb-induced injuries in the spatial reference memory were associated with a reduction of cell viability and cell apoptosis, and treatment with gangliosides markedly ameliorated the Pb-induced injury by inhibition of apoptosis action. Gangliosides further attenuated Pb-induced the abnormal autophagic process by regulation of mTOR pathways. In summary, our study establishes the efficacy of gangliosides as neuroprotective agents and provides a strong rationale for further studies on the underlying mechanisms of their neuroprotective functions.

  3. The Protective Effect of Gangliosides on Lead (Pb-Induced Neurotoxicity Is Mediated by Autophagic Pathways

    Directory of Open Access Journals (Sweden)

    Hongtao Meng

    2016-03-01

    Full Text Available Lead (Pb is a ubiquitous environmental and industrial pollutant and can affect intelligence development and the learning ability and memory of children. Therefore, necessary measures should be taken to protect the central nervous system (CNS from Pb toxicity. Gangliosides are sialic acid-containing glycosphingolipids that are constituents of mammalian cell membranes and are more abundantly expressed in the CNS. Studies have shown that gangliosides constitute a useful tool in the attempt to promote functional recovery of CNS and can reverse Pb-induced impairments of synaptic plasticity in rats. However, the detailed mechanisms have yet to be fully understood. In our present study, we tried to investigate the role of gangliosides in Pb-induced injury in hippocampus neurons and to further confirm the detailed mechanism. Our results show that Pb-induced injuries in the spatial reference memory were associated with a reduction of cell viability and cell apoptosis, and treatment with gangliosides markedly ameliorated the Pb-induced injury by inhibition of apoptosis action. Gangliosides further attenuated Pb-induced the abnormal autophagic process by regulation of mTOR pathways. In summary, our study establishes the efficacy of gangliosides as neuroprotective agents and provides a strong rationale for further studies on the underlying mechanisms of their neuroprotective functions.

  4. Position-specific isotope modeling of organic micropollutants transformations through different reaction pathways

    Science.gov (United States)

    Jin, Biao; Rolle, Massimo

    2016-04-01

    Organic compounds are produced in vast quantities for industrial and agricultural use, as well as for human and animal healthcare [1]. These chemicals and their metabolites are frequently detected at trace levels in fresh water environments where they undergo degradation via different reaction pathways. Compound specific stable isotope analysis (CSIA) is a valuable tool to identify such degradation pathways in different environmental systems. Recent advances in analytical techniques have promoted the fast development and implementation of multi-element CSIA. However, quantitative frameworks to evaluate multi-element stable isotope data and incorporating mechanistic information on the degradation processes [2,3] are still lacking. In this study we propose a mechanism-based modeling approach to simultaneously evaluate concentration as well as bulk and position-specific multi-element isotope evolution during the transformation of organic micropollutants. The model explicitly simulates position-specific isotopologues for those atoms that experience isotope effects and, thereby, provides a mechanistic description of isotope fractionation occurring at different molecular positions. We validate the proposed approach with the concentration and multi-element isotope data of three selected organic micropollutants: dichlorobenzamide (BAM), isoproturon (IPU) and diclofenac (DCF). The model precisely captures the dual element isotope trends characteristic of different reaction pathways and their range of variation consistent with observed multi-element (C, N) bulk isotope fractionation. The proposed approach can also be used as a tool to explore transformation pathways in scenarios for which position-specific isotope data are not yet available. [1] Schwarzenbach, R.P., Egli, T., Hofstetter, T.B., von Gunten, U., Wehrli, B., 2010. Global Water Pollution and Human Health. Annu. Rev. Environ. Resour. doi:10.1146/annurev-environ-100809-125342. [2] Jin, B., Haderlein, S.B., Rolle, M

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

    Directory of Open Access Journals (Sweden)

    Ruijuan Qu

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

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

    Science.gov (United States)

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

    2015-01-01

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

  7. Hydrogen oxidation mechanisms on Ni/yttria stabilized zirconia anodes: Separation of reaction pathways by geometry variation of pattern electrodes

    Science.gov (United States)

    Doppler, M. C.; Fleig, J.; Bram, M.; Opitz, A. K.

    2018-03-01

    Nickel/yttria stabilized zirconia (YSZ) electrodes are affecting the overall performance of solid oxide fuel cells (SOFCs) in general and strongly contribute to the cell resistance in case of novel metal supported SOFCs in particular. The electrochemical fuel conversion mechanisms in these electrodes are, however, still only partly understood. In this study, micro-structured Ni thin film electrodes on YSZ with 15 different geometries are utilized to investigate reaction pathways for the hydrogen electro-oxidation at Ni/YSZ anodes. From electrodes with constant area but varying triple phase boundary (TPB) length a contribution to the electro-catalytic activity is found that does not depend on the TPB length. This additional activity could clearly be attributed to a yet unknown reaction pathway scaling with the electrode area. It is shown that this area related pathway has significantly different electrochemical behavior compared to the TPB pathway regarding its thermal activation, sulfur poisoning behavior, and H2/H2O partial pressure dependence. Moreover, possible reaction mechanisms of this reaction pathway are discussed, identifying either a pathway based on hydrogen diffusion through Ni with water release at the TPB or a path with oxygen diffusion through Ni to be a very likely explanation for the experimental results.

  8. Food contamination as a pathway for lead exposure in children during the 2010-2013 lead poisoning epidemic in Zamfara, Nigeria.

    Science.gov (United States)

    Tirima, Simba; Bartrem, Casey; von Lindern, Ian; von Braun, Margrit; Lind, Douglas; Anka, Shehu Mohamed; Abdullahi, Aishat

    2018-05-01

    In 2010, an estimated 400 to 500 children died of acute lead poisoning associated with artisanal gold mining in Zamfara, Nigeria. Processing of gold ores containing up to 10% lead within residential compounds put residents, especially children, at the highest risk. Principal routes of exposure were incidental ingestion and inhalation of contaminated soil and dusts. Several Nigerian and international health organizations collaborated to reduce lead exposures through environmental remediation and medical treatment. The contribution of contaminated food to total lead exposure was assessed during the environmental health response. Objectives of this investigation were to assess the influence of cultural/dietary habits on lead exposure pathways and estimate the contribution of contaminated food to children's blood lead levels (BLLs). A survey of village dietary practices and staple food lead content was conducted to determine dietary composition, caloric intakes, and lead intake. Potential blood lead increments were estimated using bio-kinetic modeling techniques. Most dietary lead exposure was associated with contamination of staple cereal grains and legumes during post-harvest processing and preparation in contaminated homes. Average post-harvest and processed cereal grain lead levels were 0.32mg/kg and 0.85mg/kg dry weight, respectively. Age-specific food lead intake ranged from 7 to 78μg/day. Lead ingestion and absorption were likely aggravated by the dusty environment, fasting between meals, and nutritional deficiencies. Contamination of staple cereal grains by highly bioavailable pulverized ores could account for as much as 11%-34% of children's BLLs during the epidemic, and were a continuing source after residential soil remediation until stored grain inventories were exhausted. Copyright © 2017. Published by Elsevier B.V.

  9. Physician scientist research pathway leading to certification by the American Board of Pathology.

    Science.gov (United States)

    Weiss, Sharon W; Johnson, Rebecca L

    2016-06-01

    In 2014, the American Board of Pathology, in response to the pathology community, approved a physician scientist research pathway (PSRP). This brief report summarizes the history of and objectives for creating the physician scientist research pathway and the requirements of the American Board of Pathology for the certification of physician scientist research pathway trainees. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Modeling reaction histories to study chemical pathways in condensed phase detonation

    International Nuclear Information System (INIS)

    Scott Stewart, D.; Hernández, Alberto; Lee, Kibaek

    2016-01-01

    The estimation of pressure and temperature histories, which are required to understand chemical pathways in condensed phase explosives during detonation, is discussed. We argue that estimates made from continuum models, calibrated by macroscopic experiments, are essential to inform modern, atomistic-based reactive chemistry simulations at detonation pressures and temperatures. We present easy to implement methods for general equation of state and arbitrarily complex chemical reaction schemes that can be used to compute reactive flow histories for the constant volume, the energy process, and the expansion process on the Rayleigh line of a steady Chapman-Jouguet detonation. A brief review of state-of-the-art of two-component reactive flow models is given that highlights the Ignition and Growth model of Lee and Tarver [Phys. Fluids 23, 2362 (1980)] and the Wide-Ranging Equation of State model of Wescott, Stewart, and Davis [J. Appl. Phys. 98, 053514 (2005)]. We discuss evidence from experiments and reactive molecular dynamic simulations that motivate models that have several components, instead of the two that have traditionally been used to describe the results of macroscopic detonation experiments. We present simplified examples of a formulation for a hypothetical explosive that uses simple (ideal) equation of state forms and detailed comparisons. Then, we estimate pathways computed from two-component models of real explosive materials that have been calibrated with macroscopic experiments.

  11. Synthetic Control of Kinetic Reaction Pathway and Cationic Ordering in High-Ni Layered Oxide Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dawei [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory Physical Chemistry Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen Fujian 361005 China; Kou, Ronghui [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Ren, Yang [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Sun, Cheng-Jun [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Zhao, Hu [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; Zhang, Ming-Jian [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen Guangdong 518055 P. R. China; Li, Yan [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Huq, Ashifia [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Ko, J. Y. Peter [The Cornell High Energy Synchrotron Source, Cornell University, Ithaca NY 14853 USA; Pan, Feng [School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen Guangdong 518055 P. R. China; Sun, Yang-Kook [Department of Energy Engineering, Hanyang University, Seoul 133-791 South Korea; Yang, Yong [Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory Physical Chemistry Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen Fujian 361005 China; Amine, Khalil [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Bai, Jianming [National Synchrotron Light Source II, Brookhaven National Laboratory, Upton NY 11973 USA; Chen, Zonghai [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Wang, Feng [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA

    2017-08-25

    Nickel-rich layered transition metal oxides, LiNi1-x(MnCo)(x)O-2 (1-x >= 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi0.7Mn0.15Co0.15O2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strong temperature dependence of the kinetics of cationic ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs.

  12. Confirmation of the reaction pathway for obtaining 1-(stearamidoethyl-2-hepta-decyl-2-i midazoline

    Directory of Open Access Journals (Sweden)

    Ružić Nenad Lj.

    2002-01-01

    Full Text Available 2-lmidazolines are components of many products, used in industry and households. 1-(Stearamidoethyl-2-heptadecyl-2-imidazoline is a surface active compound, which after quaternization with dimethyl sulfate, is used in lubricants, detergents, shampoos, softeners and cosmetics products. Due to its importance, it was essential to establish the exact reaction pathway for obtaining this compound. Diethylene triamine and stearic acid were used as the starting components. Using titrimetric analysis, and IR and 1H NMR spectros-copic analysis, as well as UV-Vis spectrophotometry it was established that the main intermediate was the 1,3-diamide bis(stearamidoethylamine. Earlier investigations conducted by some authors, using exclusively titrimetric analysis, showed that the main intermediate was the 1,2-diamide. In this paper it was proved that the assumption of these authors that salicylaldehiyde would react only with the primary and not the secondary amine groups was wrong. 1,2-Diamide is the main product of the hydrolysis of 1-(stearamido-ethyl-2-heptadecyl-2-imidazoline. It was shown, in this paper that the reaction of diethylene triamine with stearic acid in xylene at the reflux temperature, yields the salt of 1-(stearamidoethyl-2-heptadecyl-2-imidazoline and stearic acid.

  13. Study on the properties of leading protons and antiprotons from exclusive anti pp reactions at 32 GeV/c

    International Nuclear Information System (INIS)

    Bogolyubskij, M.Yu.; Borovikov, A.A.; Boos, Eh.G.

    1986-01-01

    The leading properties of protons and antiprotons from the nondiffractive events are studied for p-barp-exclusive reactions at 32 GeV/c. It is found that the relative leading effect of protons and antiprotons does not depend on the final-state multiplicity and that the longitudinal moments of the leading hadrons are uncorrelated, but a significant part of the transverse momentum of a leading hadron is compensated by the transverse momentum of another leading hadron. It is shown that these experimental facts are described well by a statistical jet-independent model but contradict the Lund string-fragmentation model

  14. New MCRs: The first 4-component reaction leading to 2,4-disubstituted thiazoles

    NARCIS (Netherlands)

    Kolb, Jürgen; Beck, Barbara; Almstetter, Michael; Heck, Stefan; Herdtweck, Eberhardt; Dömling, Alexander

    2003-01-01

    New organic reactions allow chemical transformations which were previously not possible. Therefore, new reactions are important contributions to the progress in the field of organic synthesis. In this series we describe the design, scope, and limitations of newly-discovered multi-component reactions

  15. Photonuclear reactions in the GNASH code: Benchmarking model calculations for reactions on lead up to 140 MeV

    International Nuclear Information System (INIS)

    Chadwick, M.B.; Young, P.G.

    1994-08-01

    The authors have developed the GNASH code to include photonuclear reactions for incident energies up to 140 MeV. Photoabsorption is modeled through the giant resonance at the lower energies, and the quasideuteron mechanism at the higher energies, and the angular momentum coupling of the incident photon to the target is properly accounted for. After the initial interaction, primary and multiple preequilibrium emission of fast particles can occur before compound nucleus decay from the equilibrated compound nucleus. The angular distributions from compound nucleus decay are taken as isotropic, and those from preequilibrium emission (which they obtain from a phase-space model which conserves momentum) are forward-peaked. To test the new modeling they apply the code to calculate photonuclear reactions on 208 Pb for incident energies up to 140 MeV

  16. Pump-shaped dump optimal control reveals the nuclear reaction pathway of isomerization of a photoexcited cyanine dye.

    Science.gov (United States)

    Dietzek, Benjamin; Brüggemann, Ben; Pascher, Torbjörn; Yartsev, Arkady

    2007-10-31

    Using optimal control as a spectroscopic tool we decipher the details of the molecular dynamics of the essential multidimensional excited-state photoisomerization - a fundamental chemical reaction of key importance in biology. Two distinct nuclear motions are identified in addition to the overall bond-twisting motion: Initially, the reaction is dominated by motion perpendicular to the torsion coordinate. At later times, a second optically active vibration drives the system along the reaction path to the bottom of the excited-state potential. The time scales of the wavepacket motion on a different part of the excited-state potential are detailed by pump-shaped dump optimal control. This technique offers new means to control a chemical reaction far from the Franck-Condon point of absorption and to map details of excited-state reaction pathways revealing unique insights into the underlying reaction mechanism.

  17. Kinetics of the glucose/glycine Maillard reaction pathways: influences of pH and reactant initial concentrations

    NARCIS (Netherlands)

    Martins, S.I.F.S.; Boekel, van M.A.J.S.

    2005-01-01

    A previously proposed kinetic model for the glucose/glycine Maillard reaction pathways has been validated by changing the initial pH (4.8, 5.5, 6.0, 6.8 and 7.5) of the reaction and reactant initial concentrations (1:2 and 2:1 molar ratios were compared to the 1:1 ratio). The model consists of 10

  18. Diversion of the melanin synthetic pathway by dopamine product scavengers: A quantum chemical modeling of the reaction mechanisms

    Directory of Open Access Journals (Sweden)

    T. B. Demissie

    2017-01-01

    Full Text Available We report the stability and reactivity of the oxidation products as well as L-cysteine and N-acetylcysteine adducts of dopamine studied using quantum chemical calculations. The overall reactions studied were subdivided into four reaction channels. The first reaction channel is the oxidation of dopamine to form dopaminoquinone. The second reaction channel leads to melanin formation through subsequent reactions. The third and fourth reaction channels are reactions leading to the formation of dopaminoquinone adducts which are aimed to divert the synthesis of melanin. The results indicate that L-cysteine and N-acetylcysteine undergo chemical reactions mainly at C5 position of dopaminoquinone. The analyses of the thermodynamic energies indicate that L-cysteine and N-acetylcysteine covalently bind to dopaminoquinone by competing with the internal cyclization reaction of dopaminoquinone which leads to the synthesis of melanin. The analysis of the results, based on the reaction free energies, is also supported by the investigation of the natural bond orbitals of the reactants and products.

  19. Ecdysone receptor agonism leading to lethal molting disruption in arthropods: Review and adverse outcome pathway development

    Science.gov (United States)

    Molting is a key biological process in growth, development, reproduction and survival in arthropods. Complex neuroendocrine pathways are involved in the regulation of molting and may potentially become targets of environmental endocrine disrupting compounds (EDCs). For example, s...

  20. Dealkylation of alkylbenzenes: a significant pathway in the toluene, o-, m-, p-xylene + OH reaction.

    Science.gov (United States)

    Noda, Jun; Volkamer, Rainer; Molina, Mario J

    2009-09-03

    The OH-radical initiated oxidation of a series of monocyclic aromatic hydrocarbons (benzene, toluene, o-, m-, and p-xylene) in the presence of oxygen and NO(x) was investigated in a flowtube coupled with a chemical ionization mass spectrometer (CIMS). OH-radical addition to the aromatic ring--the major reaction pathway--has previously been shown to have a particular sensitivity to experimental conditions. This is the first flowtube study that demonstrates the atmospheric relevance of product yields from the OH-addition channel on the millisecond time scale (35-75 ms); the phenol yield from benzene and cresol yields from toluene are found to be 51.0 +/- 4.3% and 17.7 +/- 2.1%, in excellent agreement with previous studies under close to atmospheric conditions. We further report unambiguous experimental evidence that dealkylation is a novel and significant pathway for toluene and o-, m-, and p-xylene oxidation. At 150 Torr of O2 partial pressure, toluene is found to dealkylate with a yield of 5.4 +/- 1.2% phenol; similarly, m-, o-, and p-xylene dealkylate with yields of 11.2 +/- 3.8%, 4.5 +/- 3.2%, and 4.3 +/- 3.1% cresol, respectively. A dealkylation mechanism via OH-addition in the ipso position is feasible (DeltaH = -9 kcal/mol for phenol formation from toluene) but does not lend itself easily to explain the significant isomer effect observed among xylenes; instead an alternative mechanism is presented that can explain this isomer effect and forms phenol and likely epoxide type products with identical m/z (indistinguishable in our CIMS analysis) via a carbene-type intermediate. Dealkylation adds to the atmospheric production of phenol- and likely epoxide-type products, with aldehydes as expected co-products, and helps improve the carbon balance in the initial stages of aromatic oxidation.

  1. DMPD: Interferon gene regulation: not all roads lead to Tolls. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 16095970 Interferon gene regulation: not all roads lead to Tolls. Jefferies CA, Fit...zgerald KA. Trends Mol Med. 2005 Sep;11(9):403-11. (.png) (.svg) (.html) (.csml) Show Interferon gene regulation: not all roads... lead to Tolls. PubmedID 16095970 Title Interferon gene regulation: not all roads lead to

  2. Nutrient starvation leading to triglyceride accumulation activates the Entner Doudoroff pathway in Rhodococcus jostii RHA1.

    Science.gov (United States)

    Juarez, Antonio; Villa, Juan A; Lanza, Val F; Lázaro, Beatriz; de la Cruz, Fernando; Alvarez, Héctor M; Moncalián, Gabriel

    2017-02-27

    Rhodococcus jostii RHA1 and other actinobacteria accumulate triglycerides (TAG) under nutrient starvation. This property has an important biotechnological potential in the production of sustainable oils. To gain insight into the metabolic pathways involved in TAG accumulation, we analysed the transcriptome of R jostii RHA1 under nutrient-limiting conditions. We correlate these physiological conditions with significant changes in cell physiology. The main consequence was a global switch from catabolic to anabolic pathways. Interestingly, the Entner-Doudoroff (ED) pathway was upregulated in detriment of the glycolysis or pentose phosphate pathways. ED induction was independent of the carbon source (either gluconate or glucose). Some of the diacylglycerol acyltransferase genes involved in the last step of the Kennedy pathway were also upregulated. A common feature of the promoter region of most upregulated genes was the presence of a consensus binding sequence for the cAMP-dependent CRP regulator. This is the first experimental observation of an ED shift under nutrient starvation conditions. Knowledge of this switch could help in the design of metabolomic approaches to optimize carbon derivation for single cell oil production.

  3. Combined quantum mechanical and molecular mechanical reaction pathway calculation for aromatic hydroxylation by p-hydroxybenzoate-3-hydroxylase

    NARCIS (Netherlands)

    Ridder, L.; Mulholland, A.; Rietjens, I.M.C.M.; Vervoort, J.

    1999-01-01

    The reaction pathway for the aromatic 3-hydroxylation of p-hydroxybenzoate by the reactive C4a-hydroperoxyflavin cofactor intermediate in p-hydroxybenzoate hydroxylase (PHBH) has been investigated by a combined quantum mechanical and molecular mechanical (QM/MM) method. A structural model for the

  4. A Pathway to Psychological Difficulty: Perceived Chronic Social Adversity and Its Symptomatic Reactions.

    Science.gov (United States)

    Ding, Cody; Zhang, Jingqiu; Yang, Dong

    2018-01-01

    In this paper, we attempt to predict and explain psychological maladjustment or difficulty. Specifically, we discuss the concept of perceived chronic social adversity, and we expect that such perceived chronic social adversity may potentially lead to chronic stress responses. Accordingly, we propose the symptomatic reactions of perceived chronic social adversity. We put forward a set of hypotheses regarding the relationships between perceived chronic social adversity and those chronic stress responses, and we further hypothesize a mediating role of individualized negative essentialism brought by perceived chronical social adversity. Resilience and individual differences in the ability to cope with perceived adversity are discussed. Future research and prevention need to pay more attention to effects of subjective personal experiences on psychological difficulty, focusing on the importance of exploring daily social experiences in improving cognitive construction processes and developing appropriate preventions.

  5. A Pathway to Psychological Difficulty: Perceived Chronic Social Adversity and Its Symptomatic Reactions

    Directory of Open Access Journals (Sweden)

    Cody Ding

    2018-04-01

    Full Text Available In this paper, we attempt to predict and explain psychological maladjustment or difficulty. Specifically, we discuss the concept of perceived chronic social adversity, and we expect that such perceived chronic social adversity may potentially lead to chronic stress responses. Accordingly, we propose the symptomatic reactions of perceived chronic social adversity. We put forward a set of hypotheses regarding the relationships between perceived chronic social adversity and those chronic stress responses, and we further hypothesize a mediating role of individualized negative essentialism brought by perceived chronical social adversity. Resilience and individual differences in the ability to cope with perceived adversity are discussed. Future research and prevention need to pay more attention to effects of subjective personal experiences on psychological difficulty, focusing on the importance of exploring daily social experiences in improving cognitive construction processes and developing appropriate preventions.

  6. Laccase-catalyzed removal of the antimicrobials chlorophene and dichlorophen from water: Reaction kinetics, pathway and toxicity evaluation.

    Science.gov (United States)

    Shi, Huanhuan; Peng, Jianbiao; Li, Jianhua; Mao, Liang; Wang, Zunyao; Gao, Shixiang

    2016-11-05

    As active agents in cleaning and disinfecting products, antimicrobials have been widely spread in the environment and have drawn extensive attention as potential threats to the ecological system and human health. In this study, the laccase-catalyzed removal of two emerging antimicrobials, chlorophene (CP) and dichlorophen (DCP), was investigated under simulated environmental conditions. Intrinsic reaction kinetics showed that the removal of CP and DCP followed second-order reaction kinetics, first-order with respect to both the enzyme and the substrate concentration. It was also found that fulvic acid could suppress the transformation of CP and DCP by reversing the oxidation reactions through its action as a scavenger of the free radical intermediates produced from reactions between laccase and the substrates. Several reaction products were identified by a quadrupole time-of-flight mass spectrometer, and detailed reaction pathways were proposed. For both CP and DCP, direct polymerization was the principal pathway, and the coupling patterns were further corroborated based on molecular modeling. The nucleophilic substitution of chlorine by the hydroxyl group was observed, and further oxidation products capable of coupling with each other were also found. Additionally, toxicity evaluation tests using Scenedesmus obliquus confirmed that the toxicity of CP and DCP was effectively eliminated during the reaction processes. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Synergy and interactions among biological pathways leading to preterm premature rupture of membranes.

    Science.gov (United States)

    Lannon, Sophia M R; Vanderhoeven, Jeroen P; Eschenbach, David A; Gravett, Michael G; Adams Waldorf, Kristina M

    2014-10-01

    Preterm premature rupture of membranes (PPROM) occurs in 1% to 2% of births. Impact of PPROM is greatest in low- and middle-income countries where prematurity-related deaths are most common. Recent investigations identify cytokine and matrix metalloproteinase activation, oxidative stress, and apoptosis as primary pathways to PPROM. These biological processes are initiated by heterogeneous etiologies including infection/inflammation, placental bleeding, uterine overdistention, and genetic polymorphisms. We hypothesize that pathways to PPROM overlap and act synergistically to weaken membranes. We focus our discussion on membrane composition and strength, pathways linking risk factors to membrane weakening, and future research directions to reduce the global burden of PPROM. © The Author(s) 2014.

  8. Developmentally programmed DNA deletion in Tetrahymena thermophila by a transposition-like reaction pathway.

    Science.gov (United States)

    Saveliev, S V; Cox, M M

    1996-01-01

    We provide a molecular description of key intermediates in the deletion of two internal eliminated sequences (IES elements), the M and R regions, during macronuclear development in Tetrahymena thermophila. Using a variety of PCR-based methods in vivo, double-strand breaks are detected that are generated by hydrolytic cleavage and correspond closely to the observed chromosomal junctions left behind in the macronuclei. The breaks exhibit a temporal and structural relationship to the deletion reaction that provides strong evidence that they are intermediates in the deletion pathway. Breaks in the individual strands are staggered by 4 bp, producing a four nucleotide 5' extension. Evidence is presented that breaks do not occur simultaneously at both ends. The results are most consistent with a deletion mechanism featuring initiation by double-strand cleavage at one end of the deleted element, followed by transesterification to generate the macronuclear junction on one DNA strand. An adenosine residue is found at all the nucleophilic 3' ends used in the postulated transesterification step. Evidence for the transesterification step is provided by detection of a 3' hydroxyl that would be liberated by such a step at a deletion boundary where no other DNA strand ends are detected. Images PMID:8654384

  9. Development and implementation of a critical pathway for prevention of adverse reactions to contrast media for computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Keun Jo [Presbyterian Medical Center, Seoul (Korea, Republic of); Kweon, Dae Cheol; Kim, Myeong Goo [Seoul National University Hospital, Seoul (Korea, Republic of); Yoo, Beong Gyu [Wonkwang Health Science College, Iksan (Korea, Republic of)

    2007-03-15

    The purpose of this study is to develop a critical pathway (CP) for the prevention of adverse reactions to contrast media for computed tomography. The CP was developed and implemented by a multidisciplinary group is Seoul National University Hospital. The CP was applied to CT patients. Patients who underwent CT scanning were included in the CP group from March in 2004. The satisfaction of the patients with CP was compared with non-CP groups. We also investigated the degree of satisfaction among the radiological technologists and nurses. The degree of patient satisfaction with the care process increased patient information (24%), prevention of adverse reactions to contrast media (19%), pre-cognitive effect of adverse reactions to contrast media (39%) and information degree of adverse reactions to contrast media (19%). This CP program can be used as one of the patient care tools for reducing the adverse reactions to contrast media and increasing the efficiency of care process in CT examination settings.

  10. Development and implementation of a critical pathway for prevention of adverse reactions to contrast media for computed tomography

    International Nuclear Information System (INIS)

    Jang, Keun Jo; Kweon, Dae Cheol; Kim, Myeong Goo; Yoo, Beong Gyu

    2007-01-01

    The purpose of this study is to develop a critical pathway (CP) for the prevention of adverse reactions to contrast media for computed tomography. The CP was developed and implemented by a multidisciplinary group is Seoul National University Hospital. The CP was applied to CT patients. Patients who underwent CT scanning were included in the CP group from March in 2004. The satisfaction of the patients with CP was compared with non-CP groups. We also investigated the degree of satisfaction among the radiological technologists and nurses. The degree of patient satisfaction with the care process increased patient information (24%), prevention of adverse reactions to contrast media (19%), pre-cognitive effect of adverse reactions to contrast media (39%) and information degree of adverse reactions to contrast media (19%). This CP program can be used as one of the patient care tools for reducing the adverse reactions to contrast media and increasing the efficiency of care process in CT examination settings

  11. Long-term human exposure to lead from different media and intake pathways.

    Science.gov (United States)

    Pizzol, Massimo; Thomsen, Marianne; Andersen, Mikael Skou

    2010-10-15

    Lead (Pb) is well known as an environmental pollutant: it can accumulate in various media, so actual lead exposure reflects both historical and present contaminations. Two main challenges then emerge: obtaining updated information to gain an overall picture of the sources of exposure, and predicting the resulting internal body exposure levels and effects that occur under long-term exposure conditions. In this paper, a modeling approach is used to meet these challenges with reference to Danish exposure conditions. Levels of lead content in various media have been coupled with data for lead intake and absorption in the human body, for both children and adults. An age-dependent biokinetic model allows then for determination of the blood lead levels resulting from chronic exposure. The study shows that the actual intake of lead is up to 27% of the Provisional Tolerable Daily Intake (PTDI) for children and around 8% for adults. It is confirmed that the critical route of exposure is via ingestion, accounting for 99% of total lead intake, while inhalation contributes only to 1% of total lead intake. The resulting lead levels in the blood after 2 years of exposure to actual contamination conditions have been estimated as up to 2.2μg/dl in children and almost 1μg/dl in adults. Impacts from lead can occur even at such levels. The role of historical and present sources to lead in the environment is discussed, and, for specific child and adult exposure scenarios, external-internal concentration relationships for the direct linkage between lead in environmental media and resulting concentrations of lead in blood are then presented. Copyright © 2010 Elsevier B.V. All rights reserved.

  12. PUTATIVE ADVERSE OUTCOME PATHWAY FOR INHIBITON OF BRAIN AROMATASE IN FISH LEADING TO REPRODUCTIVE IMPAIRMENT

    Science.gov (United States)

    The adverse outcome pathway (AOP) provides a framework for organizing knowledge to define links between a molecular initiating event (MIE) and an adverse outcome (AO) occurring at a higher level of biological organization, such as the individual or population. The AOP framework p...

  13. Long-term human exposure to lead from different media and intake pathways

    DEFF Research Database (Denmark)

    Pizzol, Massimo; Thomsen, Marianne; Andersen, Mikael Skou

    2010-01-01

    , and predicting the resulting internal body exposure levels and effects that occur under long-term exposure conditions. In this paper, a modeling approach is used to meet these challenges with reference to Danish exposure conditions. Levels of lead content in various media have been coupled with data for lead......Lead (Pb) is well known as an environmental pollutant: it can accumulate in various media, so actual lead exposure reflects both historical and present contaminations. Two main challenges then emerge: obtaining updated information to gain an overall picture of the sources of exposure......–internalconcentration relationships for the direct linkage between lead in environmental media and resultingconcentrations of lead in blood are then presented....

  14. Palladium-catalyzed three-component reaction of N-tosyl hydrazones, isonitriles and amines leading to amidines.

    Science.gov (United States)

    Dai, Qiang; Jiang, Yan; Yu, Jin-Tao; Cheng, Jiang

    2015-12-04

    A palladium-catalyzed three-component reaction between N-tosyl hydrazones, aryl isonitriles and amines was developed, leading to amidines in moderate to good yields. This procedure features the rapid construction of amidine frameworks with high diversity and complexity. Ketenimines serve as intermediates, which encounter nucleophilic attack by amines to produce amidines.

  15. Probabilistic Modeling of Childhood Multimedia Lead Exposures: Examining the Soil Ingestion Pathway

    Science.gov (United States)

    BACKGROUND: Drinking water and other sources for lead are the subject of public health concerns around the Flint, Michigan, drinking water and East Chicago, Indiana, lead in soil crises. In 2015, the U.S. Environmental Protection Agency (EPA)’s National Drinking Water Advis...

  16. Reaction 12C(16O,α)24Mg leading to nuclear molecular resonances

    International Nuclear Information System (INIS)

    Nagatani, K.; Shimoda, T.; Tanner, D.; Tribble, R.; Yamaya, T.

    1979-01-01

    The reactions 12 C( 16 O,α) 24 Mg and 13 C( 16 O,α) 25 Mg were investigated at an incident energy of 145 MeV. In the reaction with the 12 C target, broad peaks are observed at forward angles which correspond to the molecular resonance states of the 12 C+ 12 C system, while the spectra with 13 C target show only a smooth continuum

  17. Blaming for a better future: future orientation and associated intolerance of personal uncertainty lead to harsher reactions toward innocent victims.

    Science.gov (United States)

    Bal, Michèlle; van den Bos, Kees

    2012-07-01

    People are often encouraged to focus on the future and strive for long-term goals. This noted, the authors argue that this future orientation is associated with intolerance of personal uncertainty, as people usually cannot be certain that their efforts will pay off. To be able to tolerate personal uncertainty, people adhere strongly to the belief in a just world, paradoxically resulting in harsher reactions toward innocent victims. In three experiments, the authors show that a future orientation indeed leads to more negative evaluations of an innocent victim (Study 1), enhances intolerance of personal uncertainty (Study 2), and that experiencing personal uncertainty leads to more negative evaluations of a victim (Study 3). So, while a future orientation enables people to strive for long-term goals, it also leads them to be harsher toward innocent victims. One underlying mechanism causing these reactions is intolerance of personal uncertainty, associated with a future orientation.

  18. MRE: a web tool to suggest foreign enzymes for the biosynthesis pathway design with competing endogenous reactions in mind

    KAUST Repository

    Kuwahara, Hiroyuki; Alazmi, Meshari; Cui, Xuefeng; Gao, Xin

    2016-01-01

    To rationally design a productive heterologous biosynthesis system, it is essential to consider the suitability of foreign reactions for the specific endogenous metabolic infrastructure of a host. We developed a novel web server, called MRE, which, for a given pair of starting and desired compounds in a given chassis organism, ranks biosynthesis routes from the perspective of the integration of new reactions into the endogenous metabolic system. For each promising heterologous biosynthesis pathway, MRE suggests actual enzymes for foreign metabolic reactions and generates information on competing endogenous reactions for the consumption of metabolites. These unique, chassis-centered features distinguish MRE from existing pathway design tools and allow synthetic biologists to evaluate the design of their biosynthesis systems from a different angle. By using biosynthesis of a range of high-value natural products as a case study, we show that MRE is an effective tool to guide the design and optimization of heterologous biosynthesis pathways. The URL of MRE is http://www.cbrc.kaust.edu.sa/mre/.

  19. MRE: a web tool to suggest foreign enzymes for the biosynthesis pathway design with competing endogenous reactions in mind

    KAUST Repository

    Kuwahara, Hiroyuki

    2016-04-29

    To rationally design a productive heterologous biosynthesis system, it is essential to consider the suitability of foreign reactions for the specific endogenous metabolic infrastructure of a host. We developed a novel web server, called MRE, which, for a given pair of starting and desired compounds in a given chassis organism, ranks biosynthesis routes from the perspective of the integration of new reactions into the endogenous metabolic system. For each promising heterologous biosynthesis pathway, MRE suggests actual enzymes for foreign metabolic reactions and generates information on competing endogenous reactions for the consumption of metabolites. These unique, chassis-centered features distinguish MRE from existing pathway design tools and allow synthetic biologists to evaluate the design of their biosynthesis systems from a different angle. By using biosynthesis of a range of high-value natural products as a case study, we show that MRE is an effective tool to guide the design and optimization of heterologous biosynthesis pathways. The URL of MRE is http://www.cbrc.kaust.edu.sa/mre/.

  20. Pathways for the release of polonium from a lead-bismuth spallation target (thermochemical calculation); Verfluechtigungspfade des Poloniums aus einem Pb-Bi-Spallationstarget (Thermochemische Kalkulation)

    Energy Technology Data Exchange (ETDEWEB)

    Eichler, B.; Neuhausen, J

    2004-06-01

    An analysis of literature data for the thermochemical constants of polonium reveals considerable discrepancies in the relations of these data among each other as well as in their expected trends within the chalcogen group. This fact hinders a reliable assessment of possible reaction paths for the release of polonium from a liquid lead-bismuth spallation target. In this work an attempt is made to construct a coherent data set for the thermochemical properties of polonium and some of its compounds that are of particular importance with respect to the behaviour of polonium in a liquid Pb-Bi target. This data set is based on extrapolations using general trends throughout the periodic table and, in particular, within the chalcogen group. Consequently, no high accuracy should be attributed to the derived data set. However, the data set derived in this work is consistent with definitely known experimental data. Furthermore, it complies with the general trends of physicochemical properties within the chalcogen group. Finally, well known relations between thermochemical quantities are fulfilled by the data derived in this work. Thus, given the lack of accurate experimental data it can be regarded as best available data. Thermochemical constants of polonium hydride, lead polonide and polonium dioxide are derived based on extrapolative procedures. Furthermore, the possibility of formation of the gaseous intermetallic molecule BiPo, which has been omitted from discussion up to now, is investigated. From the derived thermochemical data the equilibrium constants of formation, release and dissociation reactions are calculated for different polonium containing species. Furthermore equilibrium constants are determined for the reaction of lead polonide and polonium dioxide with hydrogen, water vapour and the target components lead and bismuth. The most probable release pathways are discussed. From thermochemical evaluations polonium is expected to be released from liquid lead

  1. Errors in Postural Preparation Lead to Increased Choice Reaction Times for Step Initiation in Older Adults

    Science.gov (United States)

    Nutt, John G.; Horak, Fay B.

    2011-01-01

    Background. This study asked whether older adults were more likely than younger adults to err in the initial direction of their anticipatory postural adjustment (APA) prior to a step (indicating a motor program error), whether initial motor program errors accounted for reaction time differences for step initiation, and whether initial motor program errors were linked to inhibitory failure. Methods. In a stepping task with choice reaction time and simple reaction time conditions, we measured forces under the feet to quantify APA onset and step latency and we used body kinematics to quantify forward movement of center of mass and length of first step. Results. Trials with APA errors were almost three times as common for older adults as for younger adults, and they were nine times more likely in choice reaction time trials than in simple reaction time trials. In trials with APA errors, step latency was delayed, correlation between APA onset and step latency was diminished, and forward motion of the center of mass prior to the step was increased. Participants with more APA errors tended to have worse Stroop interference scores, regardless of age. Conclusions. The results support the hypothesis that findings of slow choice reaction time step initiation in older adults are attributable to inclusion of trials with incorrect initial motor preparation and that these errors are caused by deficits in response inhibition. By extension, the results also suggest that mixing of trials with correct and incorrect initial motor preparation might explain apparent choice reaction time slowing with age in upper limb tasks. PMID:21498431

  2. PHYSIOLOGICAL REACTION OF COMMON OSIER (SALIX VIMINIALIS L. VAR. JORR TO THE PRESENCE OF LEAD IN THE SUBSOIL

    Directory of Open Access Journals (Sweden)

    Katarzyna Malinowska

    2015-02-01

    Full Text Available The effect of lead ions of the concentrations within the range of 15–1000 mg∙dm-3 on the physiological reaction of common osier var. Jorr was examined. The content of assimilation pigments, the rate the CO2 assimilation, transpiration, the indices of relative water content and the deficit of water saturation and the content of lead in the nutrient solution. The studied physiological parameters in common osier var. Jorr were differentiated by the rate of lead ions in the nutrient solution. The Jorr variety of common osier was characterised by good values of the determined physiological parameters under stressful conditions at a large accumulation of lead. This suggests that it shows quite a high tolerance to the stress caused by contamination of the subsoil with lead.

  3. Methane coupling reaction in an oxy-steam stream through an OH radical pathway by using supported alkali metal catalysts

    KAUST Repository

    Liang, Yin

    2014-03-24

    A universal reaction mechanism involved in the oxidative coupling of methane (OCM) is demonstrated under oxy-steam conditions using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from a H 2O-O2 reaction followed by C-H activation in CH 4 with an OH radical. Thus, the presence of water enhances both the CH4 conversion rate and the C2 selectivity. This OH radical pathway that is selective for the OCM was observed for the catalyst without Mn, which suggests clearly that Mn is not the essential component in a selective OCM catalyst. The experiments with different catalyst compositions revealed that the OH.-mediated pathway proceeded in the presence of catalysts with different alkali metals (Na, K) and different oxo anions (W, Mo). This difference in catalytic activity for OH radical generation accounts for the different OCM selectivities. As a result, a high C2 yield is achievable by using Na2WO4/SiO2, which catalyzes the OH.-mediated pathway selectively. Make it methane: A universal reaction mechanism involved in the oxidative coupling of methane is demonstrated under oxy-stream conditions by using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from an H2O-O2 reaction, followed by C-H activation in CH4 with an OH radical. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Gas-Phase Reaction Pathways and Rate Coefficients for the Dichlorosilane-Hydrogen and Trichlorosilane-Hydrogen Systems

    Science.gov (United States)

    Dateo, Christopher E.; Walch, Stephen P.

    2002-01-01

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

  5. Roles of different initial Maillard intermediates and pathways in meat flavor formation for cysteine-xylose-glycine model reaction systems.

    Science.gov (United States)

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

    2017-10-01

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

  6. A facile and expedient one-pot three-component reaction leading to ...

    Indian Academy of Sciences (India)

    A three-component reaction between triphenylphosphine, a dialkyl acetylenedicarboxylate and phthalazin-1(2H)-ones that affords novel organic phosphorane derivatives in good to excellent yields is reported. FTIR, 1H, 13C and 31P NMR and elemental analyses have been utilized to characterize the synthesized ...

  7. Proanthocyanidins Attenuation of Chronic Lead-Induced Liver Oxidative Damage in Kunming Mice via the Nrf2/ARE Pathway

    Directory of Open Access Journals (Sweden)

    Miao Long

    2016-10-01

    Full Text Available Lead is harmful for human health and animals. Proanthocyanidins (PCs, a natural antioxidant, possess a broad spectrum of pharmacological and medicinal properties. However, its protective effects against lead-induced liver damage have not been clarified. This study was aimed to evaluate the protective effect of PCs on the hepatotoxicity of male Kunming mice induced by chronic lead exposure. A total of 70 healthy male Kunming mice were averagely divided into four groups: control group, i.e., the group exposed to lead, the group treated with PCs, and the group co-treated with lead and PCs. The mice exposed to lead were given water containing 0.2% lead acetate. Mice treated in the PCs and PCs lead co-treated groups were given PC (100 mg/kg in 0.9% saline by oral gavage. Lead exposure caused a significant elevation in the liver function parameters, lead level, lipid peroxidation, and inhibition of antioxidant enzyme activities. The induction of oxidative stress and histological alterations in the liver were minimized by co-treatment with PCs. Meanwhile, the number of Transferase-Mediated Deoxyuridine Triphosphate-Biotin Nick End Labeling (TUNEL-positive cells was significantly reduced in the PCs/lead co-treated group compared to the lead group. In addition, the lead group showed an increase in the expression level of Bax, while the expression of Bcl-2 was decreased. Furthermore, the lead group showed an increase in the expression level of endoplasmic reticulum (ER stress-related genes and protein (GRP78 and CHOP. Co-treated with PCs significantly reversed these expressions in the liver. PCs were, therefore, demonstrated to have protective, antioxidant, and anti-ER stress and anti-apoptotic activities in liver damage caused by chronic lead exposure in the Kunming mouse. This may be due to the ability of PCs to enhance the ability of liver tissue to protect against oxidative stress via the Nrf2/ARE signaling pathway, resulting in decreasing ER stress

  8. Degradation of sulfadimethoxine catalyzed by laccase with soybean meal extract as natural mediator: Mechanism and reaction pathway.

    Science.gov (United States)

    Liang, Shangtao; Luo, Qi; Huang, Qingguo

    2017-08-01

    Natural laccase-mediator systems have been well recognized as an eco-friendly and energy-saving approach in environmental remediation, whose further application is however limited by the high cost of natural mediators and relatively long treatment time span. This study evaluated the water extract of soybean meal, a low-cost compound system, in mediating the laccase catalyzed degradation of a model contaminant of emerging concern, sulfadimethoxine (SDM), and demonstrated it as a promising alternative mediator for soil and water remediation. Removal of 73.3% and 65.6% was achieved in 9 h using soybean meal extract (SBE) as the mediating system for laccase-catalyzed degradation of sulfadimethoxine at the concentration of 1 ppm and 10 ppm, respectively. Further degradation of sulfadimethoxine was observed with multiple SBE additions. Using SBE as mediator increased the 9-h removal of SDM at 1 ppm initial concentration by 52.9%, 49.4%, and 36.3% in comparison to the system mediated by 1-Hydroxybenzotriazole (HBT), p-Coumaric acid (COU) and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS), respectively. With the detection of stable coupling products formed with radical scavenger (5,5-Dimethyl-1-pyrroline N-oxide, DMPO), three phenolic compounds (vanillin, apocynin, and daidzein) in SBE were confirmed to serve as mediators for Trametes versicolor laccase. Reaction pathways were proposed based on the results of High Resolution Mass Spectrometry. SO 2 excursion happened during SDM transformation, leading to elimination of antimicrobial activity. Therefore, as a natural, phenol rich, and affordable compound system, the future application of SBE in wastewater and soil remediation is worth exploring. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Dexmedetomidine Inhibits Inflammatory Reaction in Lung Tissues of Septic Rats by Suppressing TLR4/NF-κB Pathway

    Directory of Open Access Journals (Sweden)

    Yuqing Wu

    2013-01-01

    and 20 μg/kg significantly decreased mortality and pulmonary inflammation of septic rats, as well as suppressed CLP-induced elevation of TNF-α and IL-6 and inhibited TLR4/MyD88 expression and NF-κB activation. These results suggest that dexmedetomidine may decrease mortality and inhibit inflammatory reaction in lung tissues of septic rats by suppressing TLR4/MyD88/NF-κB pathway.

  10. Transformation of aminopyrine in the presence of free available chlorine: Kinetics, products, and reaction pathways.

    Science.gov (United States)

    Cai, Mei-Quan; Feng, Li; Zhang, Li-Qiu

    2017-03-01

    Aminopyrine (AMP) has been frequently detected in the aquatic environment. In this study, the transformation mechanism of AMP by free available chlorine (FAC) oxidation was investigated. The results showed that FAC reacted with AMP rapidly, and a 74% elimination was achieved for 1.30 μM AMP after 2 min at 14.08 μM FAC dose. AMP chlorination was strongly pH-dependent, and its reaction included second- and third-order kinetic processes. Three active FAC species, including chlorine monoxide (Cl 2 O), molecular chlorine (Cl 2 ), and hypochlorous acid (HOCl), were observed to contribute to AMP degradation. The intrinsic rate constants of each FAC species with neutral (AMP 0 ) and cation (AMP + ) species were obtained by kinetic fitting. Cl 2 O exhibited the highest reactivity with AMP 0 (k AMP0, Cl2O  = (4.33 ± 1.4) × 10 9  M -1 s -1 ). In addition, Cl 2 showed high reactivity (10 6 -10 7  M -1 s -1 ) in the presence of chloride, compared with HOCl (k AMP+, HOCl  = (5.73 ± 0.23) × 10 2  M -1 s -1 , k AMP0, HOCl  = (9.68 ± 0.96) × 10 2  M -1 s -1 ). At pH 6.15 and 14.08 μM FAC dose without chloride addition, the contribution of Cl 2 O reached to the maximum (33.3%), but in the whole pH range, HOCl was the main contributor (>66.6%) for AMP degradation. The significance of Cl 2 was noticeable in water containing chloride. Moreover, 11 transformation products were identified, and the main transformation pathways included pyrazole ring breakage, hydroxylation, dehydrogenation, and halogenation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Dissipative effects in fission investigated with proton-on-lead reactions

    Directory of Open Access Journals (Sweden)

    Rodríguez-Sánchez J. L.

    2016-01-01

    Full Text Available The complete kinematic measurement of the two fission fragments permitted us to investigate dissipative effects at large deformations, between the saddle-point and the corresponding scission configurations. Up to now, this kind of study has only been performed with fusionfission reactions using a limited number of observables, such as the mass distribution of the fission fragments or the neutron multiplicities. However, the large angular momenta gained by the compound nucleus could affect the conclusions drawn from such experiments. In this work, the use of spallation reactions, where the fissioning systems are produced with low angular momentum, small deformations and high excitation energies, favors the study of dissipation, and allowed us to define new observables, such as postscission neutron multiplicities and the neutron excess of the final fission fragments as a function of the atomic number of the fissioning system. These new observables are used to investigate the dissipation at large deformations.

  12. Rapid Synthesis of Lead Oxide Nanorods by One-step Solid-state Chemical Reaction at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    CAO, Ya-Li(曹亚丽); JIA, Dian-Zeng(贾殿赠); LIU, Lang(刘浪); LUO, Jian-Min(骆建敏)

    2004-01-01

    A simple and facile method was reported to synthesize lead oxide nanorods. Nanorods of lead oxide were obtained directly from grinding solid metal salt and sodium hydroxide in agate mortar with the assistance of a suitable nonionic surfactant in only one step, which is different from the result of hydroxide in solution. The product has been characterized by XRD, TEM and SEM. The formation mechanism of rod-like morphology is discussed and the surfactant plays an important soft-template role in modifying the interface of solid-state reaction and according process of rod-formation.

  13. High spin states excited by the (p, t) reaction on lead isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Kumabe, I.; Hyakutake, M. [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering; Yuasa, K.; Yamagata, T.; Kishimoto, S.; Ikegami, H.; Muraoka, M [eds.

    1980-01-01

    In order to find high spin states the sup(204, 206, 208)Pb (p, t) reactions have been investigated with RCNP isochronous cyclotron and a high resolution magnetic spectrograph ''RAIDEN''. The experimental angular distributions were analyzed by DWBA calculations, and the lowest 10/sup +/, 12/sup +/ (i sub(13/2))/sup 2/ and 11/sup -/ (i sub(13/2), h sub(9/2)) states in /sup 202/Pb, /sup 204/Pb and /sup 206/Pb were established.

  14. Electrocatalysis of anodic oxygen-transfer reactions at modified lead dioxide electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, Yun-Lin.

    1990-09-21

    The electrocatalytic activities were compared for pure and chloride-doped beta-PbO{sub 2} (Cl-PbO{sub 2}) films on gold and platinum substrates. Rate constants were increased significantly for oxidations of Mn{sup 2+}, toluene, benzyl alcohol, dimethylsulphoxide (DMSO) and benzaldehyde in acidic media by the incorporation of Cl{sup {minus}} into the oxide films. These reactions are concluded to occur by the electrocatalytic transfer of oxygen from H{sub 2}O to the reaction products. Results of x-ray diffraction studies indicate the Cl-PbO{sub 2} film continues to have the slightly distorted rutile structure of pure beta-PbO{sub 2}. The observed electrocatalytic phenomena are concluded to be the beneficial consequence of surface defects generated when Cl{sup {minus}} serves for charge compensation within the surface matrix and, thereby, increases the number of surface sites capable of adsorbing hydroxyl radicals which are transferred in the electrocatalytic O-transfer reactions. 91 refs., 44 figs., 10 tabs.

  15. Multiple Pathways of Genome Plasticity Leading to Development of Antibiotic Resistance

    Directory of Open Access Journals (Sweden)

    Didier Mazel

    2013-05-01

    Full Text Available The emergence of multi-resistant bacterial strains is a major source of concern and has been correlated with the widespread use of antibiotics. The origins of resistance are intensively studied and many mechanisms involved in resistance have been identified, such as exogenous gene acquisition by horizontal gene transfer (HGT, mutations in the targeted functions, and more recently, antibiotic tolerance through persistence. In this review, we focus on factors leading to integron rearrangements and gene capture facilitating antibiotic resistance acquisition, maintenance and spread. The role of stress responses, such as the SOS response, is discussed.

  16. Cross sections of (p, xn) reactions in the isotopes of lead and bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Bell, R E [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Skarsgard, H M [Atomic Energy Research Establishment, Reactor Research Div., Harwell (United Kingdom)

    1956-07-01

    Measurements have been made by the activation method of cross sections of (p, xn) reactions in Bi{sup 209}, Pb{sup 206}, Pb{sup 207}, and Pb{sup 208}. The present results cover x = 3 to 7 in Bi{sup 209}, 2 to 6 in Pb{sup 206}, 2 to 4 in Pb{sup 207}, and 3 and 4 in Pb{sup 208}, over a total proton energy range from 12 to 85 Mev. The absolute accuracy is about 15%. Each cross section plotted as a function of proton energy rises above its threshold to a peak whose height is of the order of one barn, and then falls again to a low and fairly constant value. The results from x = 3 to 7 are consistent with a compound nucleus plus prompt nucleon-nucleon cascade model using reasonable nuclear parameters, but the experimental (p, 2n) cross section appears to be almost double the value so predicted. Since (p, xn) reactions are dominant in the energy range 10 to 40 Mev., their sum approximates the total reaction cross section; the experimental sum fluctuates around the smooth curve computed for the compound nucleus model with r{sub 0} = 1.3 X 10{sup -13} cm. The fluctuations are similar to, but more marked than, those in the total neutron cross section of heavy elements in the same energy range. A more detailed theoretical discussion of these results is given by Jackson in the paper immediately following. (author)

  17. The reaction of Lupinus angustifolius L. root meristematic cell nucleoli to lead.

    Science.gov (United States)

    Balcerzak, Lucja; Glińska, Sława; Godlewski, Mirosław

    2011-04-01

    The effect of 2-48 h treatment of Lupinus angustifolius L. roots with lead nitrate at the concentration of 10(-4) M on the nucleoli in meristematic cells was investigated. In the lead presence the number of ring-shaped as well as segregated nucleoli increased especially after 12-48 h of treatment, while spindle-shaped nucleoli appeared after 24 h and 48 h. Lead presence also increased the frequency of cells with silver-stained particles in the nucleus and the number of these particles especially from the 12th hour of treatment. It was accompanied by significant decline of nucleolar area. Analysis of these cells in transmission electron microscope confirmed the presence of ring-shaped and segregated nucleoli. Moreover, electron microscopy revealed compact structure nucleoli without granular component. Additionally, one to three oval-shaped fibrillar structures attached to nucleolus or lying free in the nucleoplasm were visible. The possible mechanism of lead toxicity to the nucleolus is briefly discussed.

  18. Reaction of winter oilseed rape varieties to elevated concentrations of lead

    Directory of Open Access Journals (Sweden)

    Oreščanin Bojana

    2012-01-01

    Full Text Available Remediation methods allow the removal of metals from contaminated soil, and phytoremediation a technology for cleaning contaminated soil and waste material by plants, is becoming increasingly used. Brassica napus L., as one of the main oilcrops and high-biomass producing species, is becoming more and more interesting for the use in phytoextraction as it is proved to be tolerant to higher concentrations of heavy metals. The aim of this study was to examine the specific responses of three commercial winter rapeseed varieties, Banaćanka, Slavica and Kata, to the increased concentrations of lead in vitro. Significant reduction in root length of plants treated with lead was observed only in the variety Slavica, indicating susceptibility of this variety to the increased concentrations of this heavy metal. As in variety Kata a significant reduction in the length of the above-ground part due to the treatment with lead was detected, it could be concluded that the variety Banaćanka is the most tolerant to the applied concentrations of lead since there were no significant changes in the growth and biomass accumulation in all treatments except one, and could be recommended for further use in phytoremediation studies. [Projekat Ministarstva nauke Republike Srbije, br. TR31025 i br. III43007

  19. Modeling position-specific isotope fractionation of organic micropollutants degradation via different reaction pathways

    DEFF Research Database (Denmark)

    Jin, Biao; Rolle, Massimo

    : dichlorobenzamide (BAM), isoproturon (IPU) and diclofenac (DCF). The model successfully reproduces the multi-element isotope data, and precisely captures the dual element isotope trends, characterizing the different degradation pathways. Besides illustrating the model capability of mechanistic evaluation...

  20. Charting an Alternate Pathway to Reaction Orders and Rate Laws in Introductory Chemistry Courses

    Science.gov (United States)

    Rushton, Gregory T.; Criswell, Brett A.; McAllister, Nicole D.; Polizzi, Samuel J.; Moore, Lamesha A.; Pierre, Michelle S.

    2014-01-01

    Reaction kinetics is an axiomatic topic in chemistry that is often addressed as early as the high school course and serves as the foundation for more sophisticated conversations in college-level organic, physical, and biological chemistry courses. Despite the fundamental nature of reaction kinetics, students can struggle with transforming their…

  1. Thermal decomposition of a molecular material {N(n-C4H94[FeIIFeIII(C2O43]}∞ leading to ferrite: A reaction kinetics study

    Directory of Open Access Journals (Sweden)

    Bhattacharjee Ashis

    2013-01-01

    Full Text Available A multi-step thermal decomposition of a molecular precursor, {N(n-C4H94[FeIIFeIII(C2O43}∞ has been studied using non-isothermal thermogravimetry (TG measurements in the temperature range 300 to ~800 K at multiple heating rates (5, 10 and 20 K min-1. The thermal decomposition of the oxalate-based complex proceeds stepwise through a series of intermediate reactions. Two different isoconversional methods, namely, improved iterative method and model-free method are employed to evaluate the kinetic parameters: activation energy and rate of reaction, and the most probable reaction mechanism of thermal decomposition is also determined. The different reaction pathways leading to different steps in the TG profile have also been explored which are supplemented by earlier experimental observations of the present authors.

  2. Production of He-, Ne-, Ar-, Kr-, and Xe-isotopes by proton-induced reactions on lead

    International Nuclear Information System (INIS)

    Leya, I.; Michel, R.

    2003-01-01

    We measured integral thin target cross sections for the proton-induced production of He-, Ne-, Ar-, Kr-, and Xe-isotopes from lead from the respective reaction thresholds up to 2.6 GeV. The production of noble gas isotopes in lead by proton-induced reactions is of special importance for design studies of accelerator driven systems and energy amplifiers. In order to minimise the influences of secondary particles on the production of residual nuclides a new Mini-Stack approach was used instead of the well-known stacked-foil techniques for all experiments with proton energies above 200 MeV. With some exceptions our database for the proton-induced production of noble gas isotopes from lead is consistent and nearly complete. In contradistinction to the production of He from Al and Fe, where the cross sections obtained by thin-target irradiation experiments are up to a factor of 2 higher than the NESSI data, both datasets agree for the He production from lead. (orig.)

  3. Influence of Ligand Architecture in Tuning Reaction Bifurcation Pathways for Chlorite Oxidation by Non-Heme Iron Complexes

    NARCIS (Netherlands)

    Barman, Prasenjit; Faponle, Abayomi S; Vardhaman, Anil Kumar; Angelone, Davide; Löhr, Anna-Maria; Browne, Wesley R; Comba, Peter; Sastri, Chivukula V; de Visser, Sam P

    2016-01-01

    Reaction bifurcation processes are often encountered in the oxidation of substrates by enzymes and generally lead to a mixture of products. One particular bifurcation process that is common in biology relates to electron transfer versus oxygen atom transfer by high-valent iron(IV)-oxo complexes,

  4. Effects of reaction conditions on the emission behaviors of arsenic, cadmium and lead during sewage sludge pyrolysis.

    Science.gov (United States)

    Han, Hengda; Hu, Song; Syed-Hassan, Syed Shatir A; Xiao, Yiming; Wang, Yi; Xu, Jun; Jiang, Long; Su, Sheng; Xiang, Jun

    2017-07-01

    Sewage sludge is an important class of bioresources whose energy content could be exploited using pyrolysis technology. However, some harmful trace elements in sewage sludge can escape easily to the gas phase during pyrolysis, increasing the potential of carcinogenic material emissions to the atmosphere. This study investigates emission characteristics of arsenic, cadmium and lead under different pyrolysis conditions for three different sewage sludge samples. The increased temperature (within 723-1123K) significantly promoted the cadmium and lead emissions, but its influence on arsenic emission was not pronounced. The releasing rate order of the three trace elements is volatile arsenic compounds>cadmium>lead in the beginning of pyrolysis. Fast heating rates promoted the emission of trace elements for the sludge containing the highest amount of ash, but exhibited an opposite effect for other studied samples. Overall, the high ash sludge released the least trace elements almost under all reaction conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Bioactive lysophospholipids generated by hepatic lipase degradation of lipoproteins lead to complement activation via the classical pathway.

    Science.gov (United States)

    Ma, Wanchao; Paik, David C; Barile, Gaetano R

    2014-09-09

    We determined bioactivity of lysophospholipids generated by degradation of the low-density (LDL), very low-density (VLDL), and high-density (HDL) lipoproteins with hepatic lipase (HL), cholesterol esterase (CE), and lipoprotein-associated phospholipase A2 (Lp-PLA2). The LDL, VLDL, and HDL were treated with HL, CE, and Lp-PLA2 after immobilization on plates, and complement activation studies were performed with diluted human serum. Complement component 3 (C3) fixation, a marker for complement activation, was determined with a monoclonal anti-human C3d antibody. Enzymatic properties of HL and CE were assayed with triglyceride and phosphatidylcholine substrates for triglyceride hydrolase and phospholipase A activities. The ARPE-19 cells were used for viability studies. The HL degradation of human lipoproteins LDL, VLDL, or HDL results in the formation of modified lipoproteins that can activate the complement pathway. Complement activation is dose- and time-dependent upon HL and occurs via the classical pathway. Enzymatic studies suggest that the phospholipase A1 activity of HL generates complement-activating lysophospholipids. C-reactive protein (CRP), known to simultaneously interact with complement C1 and complement factor H (CFH), further enhances HL-induced complement activation. The lysophospholipids, 1-Palmitoyl-sn-glycero-3-phosphocholine and 1-Oleoyl-sn-glycero-3-phosphocholine, can be directly cytotoxic to ARPE-19 cells. The HL degradation of lipoproteins, known to accumulate in the outer retina and in drusen, can lead to the formation of bioactive lysophospholipids that can trigger complement activation and induce RPE cellular dysfunction. Given the known risk associations for age-related macular degeneration (AMD) with HL, CRP, and CFH, this study elucidates a possible damage pathway for age-related macular degeneration (AMD) in genetically predisposed individuals, that HL activity may lead to accumulation of lysophospholipids to initiate complement

  6. DFT study of benzyl alcohol/TiO2 interfacial surface complex: reaction pathway and mechanism of visible light absorption.

    Science.gov (United States)

    Zhao, Lei; Gu, Feng Long; Kim, Minjae; Miao, Maosheng; Zhang, Rui-Qin

    2017-09-24

    We propose a new pathway for the adsorption of benzyl alcohol on the surface of TiO 2 and the formation of interfacial surface complex (ISC). The reaction free energies and reaction kinetics were thoroughly investigated by density functional calculations. The TiO 2 surfaces were modeled by clusters consisting of 4 Ti atoms and 18 O atoms passivated by H, OH group and H 2 O molecules. Compared with solid-state calculations utilizing the periodicity of the materials, such cluster modeling allows inclusion of the high-order correlation effects that seem to be essential for the adsorption of organic molecules onto solid surfaces. The effects of both acidity and solvation are included in our calculations, which demonstrate that the new pathway is competitive with a previous pathway. The electronic structure calculations based on the relaxed ISC structures reveal that the chemisorption of benzyl alcohol on the TiO 2 surface greatly alters the nature of the frontier molecular orbitals. The resulted reduced energy gap in ISC matches the energy of visible light, showing how the adsorption of benzyl alcohol sensitizes the TiO 2 surface. Graphical Abstract The chemisorption of benzyl alcohol on TiO 2 surface greatly alters the nature of the frontier molecular orbitals and the formed interfacial surface complex can be sensitized by visible light.

  7. Sleep restriction may lead to disruption in physiological attention and reaction time

    Directory of Open Access Journals (Sweden)

    Arbind Kumar Choudhary

    2016-07-01

    Full Text Available Sleepiness is the condition where for some reason fails to go into a sleep state and will have difficulty in remaining awake even while carrying out activities. Sleep restriction occurs when an individual fails to get enough sleep due to high work demands. The mechanism between sleep restriction and underlying brain physiology deficits is not well assumed. The objective of the present study was to investigate the mental attention (P300 and reaction time [visual (VRT and auditory (ART] among night watchmen, at subsequent; first (1st day, fourth (4th day and seventh (7th day of restricted sleep period. After exclusion and inclusion criteria, the study was performed among 50 watchmen (age=18–35 years (n=50 after providing written informed consent and divided into two group. Group I-(Normal sleep (n=28 working in day time and used to have normal sleep in night (≥8 h; Group II-(Restricted sleep (n=22 - working in night time and used to have less sleep in night (≤3 h. Statistical significance between the different groups was determined by the independent student ʻtʼ test and the significance level was fixed at p≤0.05. We observed that among all normal and restricted sleep watchmen there was not any significant variation in Karolinska Sleepiness Scale (KSS score, VRT and ART, along with latency and amplitude of P300 on 1st day of restricted sleep. However at subsequent on 4th day and 7th day of restricted sleep, there was significant increase in (KSSscore, and prolongation of VRT and ART as well as alteration in latency and amplitude of P300 wave in restricted sleep watchmen when compare to normal sleep watchmen. The present finding concludes that loss of sleep has major impact in dynamic change in mental attention and reaction time among watchmen employed in night shift. Professional regulations and work schedules should integrate sleep schedules before and during the work period as an essential dimension for their healthy life.

  8. Sleep restriction may lead to disruption in physiological attention and reaction time.

    Science.gov (United States)

    Choudhary, Arbind Kumar; Kishanrao, Sadawarte Sahebrao; Dadarao Dhanvijay, Anup Kumar; Alam, Tanwir

    2016-01-01

    Sleepiness is the condition where for some reason fails to go into a sleep state and will have difficulty in remaining awake even while carrying out activities. Sleep restriction occurs when an individual fails to get enough sleep due to high work demands. The mechanism between sleep restriction and underlying brain physiology deficits is not well assumed. The objective of the present study was to investigate the mental attention (P300) and reaction time [visual (VRT) and auditory (ART)] among night watchmen, at subsequent; first (1st) day, fourth (4th) day and seventh (7th) day of restricted sleep period. After exclusion and inclusion criteria, the study was performed among 50 watchmen (age=18-35 years) (n=50) after providing written informed consent and divided into two group. Group I-(Normal sleep) (n=28) working in day time and used to have normal sleep in night (≥8 h); Group II-(Restricted sleep) (n=22) - working in night time and used to have less sleep in night (≤3 h). Statistical significance between the different groups was determined by the independent student ' t ' test and the significance level was fixed at p≤0.05. We observed that among all normal and restricted sleep watchmen there was not any significant variation in Karolinska Sleepiness Scale (KSS) score, VRT and ART, along with latency and amplitude of P300 on 1st day of restricted sleep. However at subsequent on 4th day and 7th day of restricted sleep, there was significant increase in (KSS)score, and prolongation of VRT and ART as well as alteration in latency and amplitude of P300 wave in restricted sleep watchmen when compare to normal sleep watchmen. The present finding concludes that loss of sleep has major impact in dynamic change in mental attention and reaction time among watchmen employed in night shift. Professional regulations and work schedules should integrate sleep schedules before and during the work period as an essential dimension for their healthy life.

  9. A Light-Induced Reaction with Oxygen Leads to Chromophore Decomposition and Irreversible Photobleaching in GFP-Type Proteins.

    Science.gov (United States)

    Grigorenko, Bella L; Nemukhin, Alexander V; Polyakov, Igor V; Khrenova, Maria G; Krylov, Anna I

    2015-04-30

    Photobleaching and photostability of proteins of the green fluorescent protein (GFP) family are crucially important for practical applications of these widely used biomarkers. On the basis of simulations, we propose a mechanism for irreversible bleaching in GFP-type proteins under intense light illumination. The key feature of the mechanism is a photoinduced reaction of the chromophore with molecular oxygen (O2) inside the protein barrel leading to the chromophore's decomposition. Using quantum mechanics/molecular mechanics (QM/MM) modeling we show that a model system comprising the protein-bound Chro(-) and O2 can be excited to an electronic state of the intermolecular charge-transfer (CT) character (Chro(•)···O2(-•)). Once in the CT state, the system undergoes a series of chemical reactions with low activation barriers resulting in the cleavage of the bridging bond between the phenolic and imidazolinone rings and disintegration of the chromophore.

  10. A chemometric method to identify enzymatic reactions leading to the transition from glycolytic oscillations to waves

    Science.gov (United States)

    Zimányi, László; Khoroshyy, Petro; Mair, Thomas

    2010-06-01

    In the present work we demonstrate that FTIR-spectroscopy is a powerful tool for the time resolved and noninvasive measurement of multi-substrate/product interactions in complex metabolic networks as exemplified by the oscillating glycolysis in a yeast extract. Based on a spectral library constructed from the pure glycolytic intermediates, chemometric analysis of the complex spectra allowed us the identification of many of these intermediates. Singular value decomposition and multiple level wavelet decomposition were used to separate drifting substances from oscillating ones. This enabled us to identify slow and fast variables of glycolytic oscillations. Most importantly, we can attribute a qualitative change in the positive feedback regulation of the autocatalytic reaction to the transition from homogeneous oscillations to travelling waves. During the oscillatory phase the enzyme phosphofructokinase is mainly activated by its own product ADP, whereas the transition to waves is accompanied with a shift of the positive feedback from ADP to AMP. This indicates that the overall energetic state of the yeast extract determines the transition between spatially homogeneous oscillations and travelling waves.

  11. Chemical Conversion Pathways and Kinetic Modeling for the OH-Initiated Reaction of Triclosan in Gas-Phase

    Directory of Open Access Journals (Sweden)

    Xue Zhang

    2015-04-01

    Full Text Available As a widely used antimicrobial additive in daily consumption, attention has been paid to the degradation and conversion of triclosan for a long time. The quantum chemistry calculation and the canonical variational transition state theory are employed to investigate the mechanism and kinetic property. Besides addition and abstraction, oxidation pathways and further conversion pathways are also considered. The OH radicals could degrade triclosan to phenols, aldehydes, and other easily degradable substances. The conversion mechanisms of triclosan to the polychlorinated dibenzopdioxin and furan (PCDD/Fs and polychlorinated biphenyls (PCBs are clearly illustrated and the toxicity would be strengthened in such pathways. Single radical and diradical pathways are compared to study the conversion mechanism of dichlorodibenzo dioxin (DCDD. Furthermore, thermochemistry is discussed in detail. Kinetic property is calculated and the consequent ratio of kadd/ktotal and kabs/ktotal at 298.15 K are 0.955 and 0.045, respectively. Thus, the OH radical addition reactions are predominant, the substitute position of OH radical on triclosan is very important to generate PCDD and furan, and biradical is also a vital intermediate to produce dioxin.

  12. Chemical conversion pathways and kinetic modeling for the OH-initiated reaction of triclosan in gas-phase.

    Science.gov (United States)

    Zhang, Xue; Zhang, Chenxi; Sun, Xiaomin; Kang, Lingyan; Zhao, Yan

    2015-04-10

    As a widely used antimicrobial additive in daily consumption, attention has been paid to the degradation and conversion of triclosan for a long time. The quantum chemistry calculation and the canonical variational transition state theory are employed to investigate the mechanism and kinetic property. Besides addition and abstraction, oxidation pathways and further conversion pathways are also considered. The OH radicals could degrade triclosan to phenols, aldehydes, and other easily degradable substances. The conversion mechanisms of triclosan to the polychlorinated dibenzopdioxin and furan (PCDD/Fs) and polychlorinated biphenyls (PCBs) are clearly illustrated and the toxicity would be strengthened in such pathways. Single radical and diradical pathways are compared to study the conversion mechanism of dichlorodibenzo dioxin (DCDD). Furthermore, thermochemistry is discussed in detail. Kinetic property is calculated and the consequent ratio of k add/k total and k abs/k total at 298.15 K are 0.955 and 0.045, respectively. Thus, the OH radical addition reactions are predominant, the substitute position of OH radical on triclosan is very important to generate PCDD and furan, and biradical is also a vital intermediate to produce dioxin.

  13. Radical Rearrangement Chemistry in Ultraviolet Photodissociation of Iodotyrosine Systems: Insights from Metastable Dissociation, Infrared Ion Spectroscopy, and Reaction Pathway Calculations.

    Science.gov (United States)

    Ranka, Karnamohit; Zhao, Ning; Yu, Long; Stanton, John F; Polfer, Nicolas C

    2018-05-29

    We report on the ultraviolet photodissociation (UVPD) chemistry of protonated tyrosine, iodotyrosine, and diiodotyrosine. Distonic loss of the iodine creates a high-energy radical at the aromatic ring that engages in hydrogen/proton rearrangement chemistry. Based on UVPD kinetics measurements, the appearance of this radical is coincident with the UV irradiation pulse (8 ns). Conversely, sequential UVPD product ions exhibit metastable decay on ca. 100 ns timescales. Infrared ion spectroscopy is capable of confirming putative structures of the rearrangement products as proton transfers from the imine and β-carbon hydrogens. Potential energy surfaces for the various reaction pathways indicate that the rearrangement chemistry is highly complex, compatible with a cascade of rearrangements, and that there is no preferred rearrangement pathway even in small molecular systems like these. Graphical Abstract.

  14. Reaction progress pathways for glass and spent fuel under unsaturated conditions

    International Nuclear Information System (INIS)

    Bates, J.; Finn, P.; Bourcier, W.; Stout, R.

    1994-10-01

    The source term for the release of radionuclides from a nuclear waste repository is the waste form. In order to assess the performance of the repository and the engineered barrier system (EBS) compared to regulations established by the Nuclear Regulatory Commission and the Environmental Protection Agency it is necessary (1) to use available data to place bounding limits on release rates from the EBS, and (2) to develop a mechanistic predictive model of the radionuclide release and validate the model against tests done under a variety of different potential reaction conditions. The problem with (1) is that there is little experience to use when evaluating waste form reaction under unsaturated conditions such that errors in applying expert judgment to the problem may be significant. The second approach, to test and model the waste form reaction, is a more defensible means of providing input to the prediction of radionuclide release. In this approach, information related to the source term has a technical basis and provides a starting point to make reasonable assumptions for long-term behavior. Key aspects of this approach are an understanding of the reaction progress mechanism and the ability to model the tests using a geochemical code such as EQ3/6. Current knowledge of glass, UO 2 , and spent fuel reactions under different conditions are described below

  15. Directing Reaction Pathways through Controlled Reactant Binding at Pd-TiO2 Interfaces.

    Science.gov (United States)

    Zhang, Jing; Wang, Bingwen; Nikolla, Eranda; Medlin, J Will

    2017-06-01

    Recent efforts to design selective catalysts for multi-step reactions, such as hydrodeoxygenation (HDO), have emphasized the preparation of active sites at the interface between two materials having different properties. However, achieving precise control over interfacial properties, and thus reaction selectivity, has remained a challenge. Here, we encapsulated Pd nanoparticles (NPs) with TiO 2 films of regulated porosity to gain a new level of control over catalyst performance, resulting in essentially 100 % HDO selectivity for two biomass-derived alcohols. This catalyst also showed exceptional reaction specificity in HDO of furfural and m-cresol. In addition to improving HDO activity by maximizing the interfacial contact between the metal and metal oxide sites, encapsulation by the nanoporous oxide film provided a significant selectivity boost by restricting the accessible conformations of aromatics on the surface. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Directing reaction pathways by catalyst active-site selection using self-assembled monolayers.

    Science.gov (United States)

    Pang, Simon H; Schoenbaum, Carolyn A; Schwartz, Daniel K; Medlin, J Will

    2013-01-01

    One key route for controlling reaction selectivity in heterogeneous catalysis is to prepare catalysts that exhibit only specific types of sites required for desired product formation. Here we show that alkanethiolate self-assembled monolayers with varying surface densities can be used to tune selectivity to desired hydrogenation and hydrodeoxygenation products during the reaction of furfural on supported palladium catalysts. Vibrational spectroscopic studies demonstrate that the selectivity improvement is achieved by controlling the availability of specific sites for the hydrogenation of furfural on supported palladium catalysts through the selection of an appropriate alkanethiolate. Increasing self-assembled monolayer density by controlling the steric bulk of the organic tail ligand restricts adsorption on terrace sites and dramatically increases selectivity to desired products furfuryl alcohol and methylfuran. This technique of active-site selection simultaneously serves both to enhance selectivity and provide insight into the reaction mechanism.

  17. Persistent ER stress induces the spliced leader RNA silencing pathway (SLS, leading to programmed cell death in Trypanosoma brucei.

    Directory of Open Access Journals (Sweden)

    Hanoch Goldshmidt

    2010-01-01

    Full Text Available Trypanosomes are parasites that cycle between the insect host (procyclic form and mammalian host (bloodstream form. These parasites lack conventional transcription regulation, including factors that induce the unfolded protein response (UPR. However, they possess a stress response mechanism, the spliced leader RNA silencing (SLS pathway. SLS elicits shut-off of spliced leader RNA (SL RNA transcription by perturbing the binding of the transcription factor tSNAP42 to its cognate promoter, thus eliminating trans-splicing of all mRNAs. Induction of endoplasmic reticulum (ER stress in procyclic trypanosomes elicits changes in the transcriptome similar to those induced by conventional UPR found in other eukaryotes. The mechanism of up-regulation under ER stress is dependent on differential stabilization of mRNAs. The transcriptome changes are accompanied by ER dilation and elevation in the ER chaperone, BiP. Prolonged ER stress induces SLS pathway. RNAi silencing of SEC63, a factor that participates in protein translocation across the ER membrane, or SEC61, the translocation channel, also induces SLS. Silencing of these genes or prolonged ER stress led to programmed cell death (PCD, evident by exposure of phosphatidyl serine, DNA laddering, increase in reactive oxygen species (ROS production, increase in cytoplasmic Ca(2+, and decrease in mitochondrial membrane potential, as well as typical morphological changes observed by transmission electron microscopy (TEM. ER stress response is also induced in the bloodstream form and if the stress persists it leads to SLS. We propose that prolonged ER stress induces SLS, which serves as a unique death pathway, replacing the conventional caspase-mediated PCD observed in higher eukaryotes.

  18. Partial strands synthesizing leads to inevitable aborting and complicated products in consecutive polymerase chain reactions (PCRs)

    Institute of Scientific and Technical Information of China (English)

    LUO Rui; ZHANG DaMing

    2007-01-01

    Various abnormal phenomena have been observed during PCR so far. The present study performed a series of consecutive PCRs (including many rounds of re-amplification continuously) and found that the abortion of re-amplification was inevitable as long as a variety of complicated product appeared.The aborting stages varied, according to the lengths of targets. Longer targets reached the abortion earlier than the shorter ones, marked by appearance of the complex that was immobile in electrophoresis. Denatured gel-electrophoresis revealed that the complex was mainly made up of shorter or partially synthesized strands, together with small amounts of full-length ones. Able to be digested by S1 nuclease but unable by restriction endonucleases (REs), the complex was proved to consist of both single regions and double-helix regions that kept the complex stable thermodynamically. Simulations gave evidence that partial strands, even at lower concentration, could disturb re-amplification effectively and lead to the abortion of re-amplifications finally. It was pointed out that the partial strands formed chiefly via polymerase's infidelity, and hence the solution to lighten the abnormality was also proposed.

  19. Partial strands synthesizing leads to inevitable aborting and complicated products in consecutive polymerase chain reactions (PCRs)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Various abnormal phenomena have been observed during PCR so far. The present study performed a series of consecutive PCRs (including many rounds of re-amplification continuously) and found that the abortion of re-amplification was inevitable as long as a variety of complicated product appeared. The aborting stages varied, according to the lengths of targets. Longer targets reached the abortion earlier than the shorter ones, marked by appearance of the complex that was immobile in electropho-resis. Denatured gel-electrophoresis revealed that the complex was mainly made up of shorter or partially synthesized strands, together with small amounts of full-length ones. Able to be digested by S1 nuclease but unable by restriction endonucleases (REs), the complex was proved to consist of both single regions and double-helix regions that kept the complex stable thermodynamically. Simulations gave evidence that partial strands, even at lower concentration, could disturb re-amplification effec- tively and lead to the abortion of re-amplifications finally. It was pointed out that the partial strands formed chiefly via polymerase’s infidelity, and hence the solution to lighten the abnormality was also proposed.

  20. Metabolic pathways leading to detoxification of triptolide, a major active component of the herbal medicine Tripterygium wilfordii.

    Science.gov (United States)

    Du, Fuying; Liu, Zhaohua; Li, Xinxiu; Xing, Jie

    2014-08-01

    Triptolide (TP) shows promising anti-inflammatory and antitumor activity but with severe toxicity. TP is a natural reactive electrophile containing three epoxide groups, which are usually linked to hepatotoxicity via their ability to covalently bind to cellular macromolecules. In this study, metabolic pathways leading to detoxification of TP were evaluated in glutathione (GSH)-depleted (treated with L-buthionine-S,R-sulfoxinine, BSO) and aminobenzotriazole (ABT; a non-specific inhibitor for P450s)-treated mice. The toxicity of TP in mice was evaluated in terms of mortality and levels of serum alanine transaminase (ALT). In incubates with NADPH- and GSH-supplemented liver microsomes, seven GSH conjugates derived from TP were detected. In mice, these hydrolytically unstable GSH conjugates underwent γ-glutamyltranspeptidase/dipeptidases-mediated hydrolysis leading to two major cysteinylglycine conjugates, which underwent further hydrolysis by dipeptidases to form two cysteine conjugates of TP. In ABT-treated mice, the hydroxylated metabolites of TP were found at a lower level than normal mice, and their subsequent conjugated metabolites were not found. The level of cysteinylglycine and cysteine conjugates derived from NADPH-independent metabolism increased in mice treated with both TP and BSO (or ABT), which could be the stress response to toxicity of TP. Compared with normal mice, mortality and ALT levels were significantly higher in TP-treated mice, indicating the toxicity of TP. Pretreatment of ABT increased the toxicity caused by TP, whereas the mortality decreased in GSH-depleted mice. Metabolism by cytochrome P450 enzymes to less reactive metabolites implied a high potential for detoxification of TP. The GSH conjugation pathway also contributed to TP's detoxification in mice. Copyright © 2013 John Wiley & Sons, Ltd.

  1. Aspartate aminotransferase: the kinetic barriers facing the covalent intermediates on the reaction pathway

    International Nuclear Information System (INIS)

    Kirsch, J.F.; Julin, D.A.; McLeish, M.; Wiesinger, H.

    1986-01-01

    The intermediates, aldimine (A), quinonoid (Q) and ketimine (K), along the transaminase reaction coordinate were probed by isotope transfer and solvent exchange kinetics. Less than 0.003% of 3 H is transferred from C/sub α/[ 3 H]-aspartate to pyridoxamine phosphate in the cytoplasmic aspartate aminotransferase (cAATase) reaction implying either that Q does not exist as a kinetically competent intermediate or that there is a rapid exchange of isotope with solvent. The ratio of the rate constants for C/sub α/ hydrogen exchange vs keto acid product formation (k/sub exge//k/sub prod/) are 2.5 and 0.5 for the reactions of cAATase with C/sub α/ [ 2 H]-aspartate and mitochondrial (m) AATase with C/sub α/[ 2 H]-glutamate respectively. The latter reaction was also probed from the α-keto-glutarate side with carbonyl 0-18 enriched keto acid. This experiment gave k/sub exge//k/sub prod/ = 1.0 for oxygen-18 exchange in α-ketoglutarate versus amino acid formation. The two exchange experiments with mAATase are interpreted in terms of a model in which the rate constant for diffusion of water from the active site is comparable with those for product forming steps

  2. Activation pathways taking place at molecular copper precatalysts for the oxygen evolution reaction

    NARCIS (Netherlands)

    van der Ham, C.J.M.; Işık, F.; Verhoeven, T.W.G.M.; Niemantsverdriet, J.W.; Hetterscheid, D.G.H.

    2017-01-01

    The activation processes of [CuII(bdmpza)2] in the water oxidation reaction were investigated using cyclic voltammetry and chronoamperometry. Two different paths wherein CuO is formed were distinguished. [CuII(bdmpza)2] can be oxidized at high potentials to form CuO, which was observed by a slight

  3. A kinetic model for the glucose/glycine Maillard reaction pathways

    NARCIS (Netherlands)

    Martins, S.I.F.S.; Boekel, van M.A.J.S.

    2005-01-01

    A comprehensive kinetic model for the glucose/glycine Maillard reaction is proposed based on an approach called multiresponse kinetic modelling. Special attention was paid to reactants, intermediates and end products: -fructose, N-(1-deoxy--fructos-1-yl)-glycine (DFG), 1-deoxy-2,3-hexodiulose and

  4. Measurement of activation reaction rate distributions in a lead assembly bombarded with 500-MeV protons

    CERN Document Server

    Takada, H; Sasa, T; Tsujimoto, K; Yasuda, H

    2000-01-01

    Reaction rate distributions of various activation detectors such as the /sup nat/Ni(n, x)/sup 58/Co, /sup 197/Au(n,2n)/sup 196/Au, and /sup 197/Au(n,4n)/sup 194/Au reactions were measured to study the production and the transport of spallation neutrons in a lead assembly bombarded with protons of 500 MeV. The measured data were analyzed with the nucleon-meson transport code NMTC/JAERI combined with the MCNP4A code using the nuclide production cross sections based on the JENDL Dosimetry File and those calculated with the ALICE-F code. It was found that the NMTC/JAERI-MCNP4A calculations agreed well with the experiments for the low-energy-threshold reaction of /sup nat/Ni(n, x)/sup 58/Co. With the increase of threshold energy, however, the calculation underestimated the experiments, especially above 20 MeV. The reason for the disagreement can be attributed to the underestimation of the neutron yield in the tens of mega-electron-volt regions by the NMTC/JAERI code. (32 refs).

  5. Modeling Ignition of a Heptane Isomer: Improved Thermodynamics, Reaction Pathways, Kinetic, and Rate Rule Optimizations for 2-Methylhexane

    KAUST Repository

    Mohamed, Samah; Cai, Liming; Khaled, Fathi; Banyon, Colin; Wang, Zhandong; Rachidi, Mariam El; Pitsch, Heinz; Curran, Henry J.; Farooq, Aamir; Sarathy, Mani

    2016-01-01

    Accurate chemical kinetic combustion models of lightly branched alkanes (e.g., 2-methylalkanes) are important to investigate the combustion behavior of real fuels. Improving the fidelity of existing kinetic models is a necessity, as new experiments and advanced theories show inaccuracies in certain portions of the models. This study focuses on updating thermodynamic data and the kinetic reaction mechanism for a gasoline surrogate component, 2-methylhexane, based on recently published thermodynamic group values and rate rules derived from quantum calculations and experiments. Alternative pathways for the isomerization of peroxy-alkylhydroperoxide (OOQOOH) radicals are also investigated. The effects of these updates are compared against new high-pressure shock tube and rapid compression machine ignition delay measurements. It is shown that rate constant modifications are required to improve agreement between kinetic modeling simulations and experimental data. We further demonstrate the ability to optimize the kinetic model using both manual and automated techniques for rate parameter tunings to improve agreement with the measured ignition delay time data. Finally, additional low temperature chain branching reaction pathways are shown to improve the model’s performance. The present approach to model development provides better performance across extended operating conditions while also strengthening the fundamental basis of the model.

  6. Modeling Ignition of a Heptane Isomer: Improved Thermodynamics, Reaction Pathways, Kinetic, and Rate Rule Optimizations for 2-Methylhexane

    KAUST Repository

    Mohamed, Samah

    2016-03-21

    Accurate chemical kinetic combustion models of lightly branched alkanes (e.g., 2-methylalkanes) are important to investigate the combustion behavior of real fuels. Improving the fidelity of existing kinetic models is a necessity, as new experiments and advanced theories show inaccuracies in certain portions of the models. This study focuses on updating thermodynamic data and the kinetic reaction mechanism for a gasoline surrogate component, 2-methylhexane, based on recently published thermodynamic group values and rate rules derived from quantum calculations and experiments. Alternative pathways for the isomerization of peroxy-alkylhydroperoxide (OOQOOH) radicals are also investigated. The effects of these updates are compared against new high-pressure shock tube and rapid compression machine ignition delay measurements. It is shown that rate constant modifications are required to improve agreement between kinetic modeling simulations and experimental data. We further demonstrate the ability to optimize the kinetic model using both manual and automated techniques for rate parameter tunings to improve agreement with the measured ignition delay time data. Finally, additional low temperature chain branching reaction pathways are shown to improve the model’s performance. The present approach to model development provides better performance across extended operating conditions while also strengthening the fundamental basis of the model.

  7. Reaction between peroxynitrite and boronates: EPR spin-trapping, HPLC analyses, and quantum mechanical study of the free radical pathway

    Science.gov (United States)

    Sikora, Adam; Zielonka, Jacek; Lopez, Marcos; Dybala-Defratyka, Agnieszka; Joseph, Joy; Marcinek, Andrzej; Kalyanaraman, Balaraman

    2013-01-01

    Recently we showed that peroxynitrite (ONOO−) reacts directly and rapidly with aromatic and aliphatic boronic acids (k ≈ 106 M−1s−1). Product analyses and substrate consumption data indicated that ONOO− reacts stoichiometrically with boronates, yielding the corresponding phenols as the major product (~85–90%), and the remaining products (10–15%) were proposed to originate from free radical intermediates (phenyl and phenoxyl radicals). Here we investigated in detail the minor, free radical pathway of boronate reaction with ONOO−. The electron paramagnetic resonance (EPR) spin-trapping technique was used to characterize the free radical intermediates formed from the reaction between boronates and ONOO−. Using 2-methyl-2-nitrosopropane (MNP) and 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) spin traps, phenyl radicals were trapped and detected. Although phenoxyl radicals were not detected, the positive effects of molecular oxygen, and inhibitory effects of hydrogen atom donors (acetonitrile, and 2-propanol) and general radical scavengers (GSH, NADH, ascorbic acid and tyrosine) on the formation of phenoxyl radical-derived nitrated product, suggest that phenoxyl radical was formed as the secondary species. We propose that the initial step of the reaction involves the addition of ONOO− to the boron atom in boronates. The anionic intermediate undergoes both heterolytic (major pathway) and homolytic (minor pathway) cleavage of the peroxy (O-O) bond to form phenol and nitrite as a major product (via a non-radical mechanism), or a radical pair PhB(OH)2O•−…•NO2 as a minor product. It is conceivable that phenyl radicals are formed by the fragmentation of PhB(OH)2O•− radical anion. According to the DFT quantum mechanical calculations, the energy barrier for the dissociation of PhB(OH)2O•− radical anion to form phenyl radicals is only a few kcal/mol, suggesting rapid and spontaneous fragmentation of PhB(OH)2O•− radical anion

  8. MicroRNA-124-3p expression and its prospective functional pathways in hepatocellular carcinoma: A quantitative polymerase chain reaction, gene expression omnibus and bioinformatics study.

    Science.gov (United States)

    He, Rong-Quan; Yang, Xia; Liang, Liang; Chen, Gang; Ma, Jie

    2018-04-01

    The present study aimed to explore the potential clinical significance of microRNA (miR)-124-3p expression in the hepatocarcinogenesis and development of hepatocellular carcinoma (HCC), as well as the potential target genes of functional HCC pathways. Reverse transcription-quantitative polymerase chain reaction was performed to evaluate the expression of miR-124-3p in 101 HCC and adjacent non-cancerous tissue samples. Additionally, the association between miR-124-3p expression and clinical parameters was also analyzed. Differentially expressed genes identified following miR-124-3p transfection, the prospective target genes predicted in silico and the key genes of HCC obtained from Natural Language Processing (NLP) were integrated to obtain potential target genes of miR-124-3p in HCC. Relevant signaling pathways were assessed with protein-protein interaction (PPI) networks, Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Protein Annotation Through Evolutionary Relationships (PANTHER) pathway enrichment analysis. miR-124-3p expression was significantly reduced in HCC tissues compared with expression in adjacent non-cancerous liver tissues. In HCC, miR-124-3p was demonstrated to be associated with clinical stage. The mean survival time of the low miR-124-3p expression group was reduced compared with that of the high expression group. A total of 132 genes overlapped from differentially expressed genes, miR-124-3p predicted target genes and NLP identified genes. PPI network construction revealed a total of 109 nodes and 386 edges, and 20 key genes were identified. The major enriched terms of three GO categories included regulation of cell proliferation, positive regulation of cellular biosynthetic processes, cell leading edge, cytosol and cell projection, protein kinase activity, transcription activator activity and enzyme binding. KEGG analysis revealed pancreatic cancer, prostate cancer and non-small cell lung cancer as the

  9. Oxidation of β-lactam antibiotics by peracetic acid: Reaction kinetics, product and pathway evaluation.

    Science.gov (United States)

    Zhang, Kejia; Zhou, Xinyan; Du, Penghui; Zhang, Tuqiao; Cai, Meiquan; Sun, Peizhe; Huang, Ching-Hua

    2017-10-15

    Peracetic acid (PAA) is a disinfection oxidant used in many industries including wastewater treatment. β-Lactams, a group of widely prescribed antibiotics, are frequently detected in wastewater effluents and surface waters. The reaction kinetics and transformation of seven β-lactams (cefalexin (CFX), cefadroxil (CFR), cefapirin (CFP), cephalothin (CFT), ampicillin (AMP), amoxicillin (AMX) and penicillin G (PG)) toward PAA were investigated to elucidate the behavior of β-lactams during PAA oxidation processes. The reaction follows second-order kinetics and is much faster at pH 5 and 7 than at pH 9 due to speciation of PAA. Reactivity to PAA follows the order of CFR ∼ CFX > AMP ∼ AMX > CFT ∼ CFP ∼ PG and is related to β-lactam's nucleophilicity. The thioether sulfur of β-lactams is attacked by PAA to generate sulfoxide products. Presence of the phenylglycinyl amino group on β-lactams can significantly influence electron distribution and the highest occupied molecular orbital (HOMO) location and energy in ways that enhance the reactivity to PAA. Reaction rate constants obtained in clean water matrix can be used to accurately model the decay of β-lactams by PAA in surface water matrix and only slightly overestimate the decay in wastewater matrix. Results of this study indicate that the oxidative transformation of β-lactams by PAA can be expected under appropriate wastewater treatment conditions. Copyright © 2017. Published by Elsevier Ltd.

  10. Maternal Chromium Restriction Leads to Glucose Metabolism Imbalance in Mice Offspring through Insulin Signaling and Wnt Signaling Pathways

    Science.gov (United States)

    Zhang, Qian; Sun, Xiaofang; Xiao, Xinhua; Zheng, Jia; Li, Ming; Yu, Miao; Ping, Fan; Wang, Zhixin; Qi, Cuijuan; Wang, Tong; Wang, Xiaojing

    2016-01-01

    An adverse intrauterine environment, induced by a chromium-restricted diet, is a potential cause of metabolic disease in adult life. Up to now, the relative mechanism has not been clear. C57BL female mice were time-mated and fed either a control diet (CD), or a chromium-restricted diet (CR) throughout pregnancy and the lactation period. After weaning, some offspring continued the diet diagram (CD-CD or CR-CR), while other offspring were transferred to another diet diagram (CD-CR or CR-CD). At 32 weeks of age, glucose metabolism parameters were measured, and the liver from CR-CD group and CD-CD group was analyzed using a gene array. Quantitative real-time polymerase chain reaction (qPCR) and Western blot were used to verify the result of the gene array. A maternal chromium-restricted diet resulted in obesity, hyperglycemia, hyperinsulinemia, increased area under the curve (AUC) of glucose in oral glucose tolerance testing and homeostasis model assessment of insulin resistance (HOMA-IR). There were 463 genes that differed significantly (>1.5-fold change, p chromium deficiency influences glucose metabolism in pups through the regulation of insulin signaling and Wnt signaling pathways. PMID:27782077

  11. Cobalt catalyzed peroxymonosulfate oxidation of tetrabromobisphenol A: Kinetics, reaction pathways, and formation of brominated by-products

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yuefei [Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095 (China); Kong, Deyang [Nanjing Institute of Environmental Science, Ministry of Environmental Protection of PRC, Nanjing 210042 (China); Lu, Junhe, E-mail: jhlu@njau.edu.cn [Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095 (China); Jin, Hao; Kang, Fuxing; Yin, Xiaoming; Zhou, Quansuo [Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095 (China)

    2016-08-05

    Highlights: • Cobalt catalyzed peroxymonosulfate oxidation of tetrabromobisphenol A. • Phenolic moiety was the reactive site for sulfate radical attack. • Pathways include β-scission, oxidation, debromination and coupling reactions. • Brominated disinfection by-products were found during TBBPA degradation. • Humic acid inhibited TBBPA degradation but promoted DBPs formation. - Abstract: Degradation of tetrabromobisphenol A (TBBPA), a flame retardant widely spread in the environment, in Co(II) catalyzed peroxymonosulfate (PMS) oxidation process was systematically explored. The second-order-rate constant for reaction of sulfate radical (SO{sub 4}{sup ·−}) with TBBPA was determined to be 5.27 × 10{sup 10} M{sup −1} s{sup −1}. Apparently, degradation of TBBPA showed first-order kinetics to the concentrations of both Co(II) and PMS. The presence of humic acid (HA) and bicarbonate inhibited TBBPA degradation, most likely due to their competition for SO{sub 4}{sup ·−}. Degradation of TBBPA was initiated by an electron abstraction from one of the phenolic rings. Detailed transformation pathways were proposed, including β-scission of isopropyl bridge, phenolic ring oxidation, debromination and coupling reactions. Further oxidative degradation of intermediates in Co(II)/PMS process yielded brominated disinfection by-products (Br-DBPs) such as bromoform and brominated acetic acids. Evolution profile of Br-DBPs showed an initially increasing and then decreasing pattern with maximum concentrations occurring around 6–10 h. The presence of HA enhanced the formation of Br-DBPs significantly. These findings reveal potentially important, but previously unrecognized, formation of Br-DBPs during sulfate radical-based oxidation of bromide-containing organic compounds that may pose toxicological risks to human health.

  12. Reaction

    African Journals Online (AJOL)

    abp

    19 oct. 2017 ... Reaction to Mohamed Said Nakhli et al. concerning the article: "When the axillary block remains the only alternative in a 5 year old child". .... Bertini L1, Savoia G, De Nicola A, Ivani G, Gravino E, Albani A et al ... 2010;7(2):101-.

  13. Investigation of reaction mechanisms during electroreduction of carbon dioxide on lead electrode for the production of organic compounds

    International Nuclear Information System (INIS)

    Innocent, B.

    2008-09-01

    The aim of this work was to promote the reduction of CO 2 through its electrochemical conversion (electro-synthesis) on a lead electrode into high added value products. Depending on the nature of electrolyte, the electro-reduction of carbon dioxide leads to different products. Various electrolytes (aqueous or organic, protic or aprotic) were used to study two mechanisms: hydrogenation (formation of formate) and electro-dimerization (synthesis of oxalate). Cyclic voltammetry studies have been carried out for electrochemically characterizing CO 2 reduction on Pb. The electrochemical investigation of the electrode electrolyte interface has shown that the process of CO 2 electro-reduction is a mass transfer control both in the organic and aqueous media. Electrochemical experiments (cyclic voltammetry, chrono-amperometry) coupled with in situ infrared reflectance spectroscopic techniques (SPAIRS, SNIFTIRS) have also shown that in aqueous medium (7 ≤pH≤9) hydrogeno-carbonate ions were reduced to formate. The modification of solvent (propylene carbonate) leads selectively to oxalate as the main reaction product. Long-term electrolyses were performed in a filter-press cell to deal large volumes. In aqueous medium, the reduction of HCO 3 - to HCOO - (R F = 89% at -2.5 mA cm -2 and 4 C) is always accompanied by the production of H 2 . (author)

  14. Synergistic reaction between SO2 and NO2 on mineral oxides: a potential formation pathway of sulfate aerosol.

    Science.gov (United States)

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

    2012-02-07

    Sulfate is one of the most important aerosols in the atmosphere. A new sulfate formation pathway via synergistic reactions between SO(2) and NO(2) on mineral oxides was proposed. The heterogeneous reactions of SO(2) and NO(2) on CaO, α-Fe(2)O(3), ZnO, MgO, α-Al(2)O(3), TiO(2), and SiO(2) were investigated by in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (in situ DRIFTS) at ambient temperature. Formation of sulfate from adsorbed SO(2) was promoted by the coexisting NO(2), while surface N(2)O(4) was observed as the crucial oxidant for the oxidation of surface sulfite. This process was significantly promoted by the presence of O(2). The synergistic effect between SO(2) and NO(2) was not observed on other mineral particles (such as CaCO(3) and CaSO(4)) probably due to the lack of the surface reactive oxygen sites. The synergistic reaction between SO(2) and NO(2) on mineral oxides resulted in the formation of internal mixtures of sulfate, nitrate, and mineral oxides. The change of mixture state will affect the physicochemical properties of atmospheric particles and therefore further influence their environmental and climate effects.

  15. Progranulin protects vascular endothelium against atherosclerotic inflammatory reaction via Akt/eNOS and nuclear factor-κB pathways.

    Science.gov (United States)

    Hwang, Hwan-Jin; Jung, Tae Woo; Hong, Ho Cheol; Choi, Hae Yoon; Seo, Ji-A; Kim, Sin Gon; Kim, Nan Hee; Choi, Kyung Mook; Choi, Dong Seop; Baik, Sei Hyun; Yoo, Hye Jin

    2013-01-01

    Atherosclerosis is considered a chronic inflammatory disease, initiated by activation and dysfunction of the endothelium. Recently, progranulin has been regarded as an important modulator of inflammatory processes; however, the role for prgranulin in regulating inflammation in vascular endothelial cells has not been described. Signaling pathways mediated by progranulin were analyzed in human umbilical vein endothelial cells (HUVECs) treated with progranulin. Progranulin significantly induced Akt and endothelial nitric oxide synthase (eNOS) phosphorylation in HUVECs, an effect that was blocked with Akt inhibitor. Furthermore, nitric oxide (NO) level, the end product of Akt/eNOS pathway, was significantly upregulated after progranulin treatment. Next, we showed that progranulin efficiently inhibited lipopolysaccharide (LPS)-mediated pro-inflammatory signaling. LPS-induced phosphorylation of IκB and nuclear factor-κB (NF-κB) levels decreased after progranulin treatment. Also, progranulin blocked translocation of NF-κB from the cytosol to the nucleus. In addition, progranulin significantly reduced the expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) by inhibiting binding of NF- κB to their promoter regions and blocked attachment of monocytes to HUVECs. Progranulin also significantly reduced the expression of tumor necrosis factor receptor-α (TNF-α) and monocyte chemo-attractant protein-1 (MCP-1), the crucial inflammatory molecules known to aggravate atherosclerosis. Progranulin efficiently inhibited LPS-mediated pro-inflammatory signaling in endothelial cells through activation of the Akt/eNOS pathway and attenuation of the NF-κB pathway, suggesting its protective roles in vascular endothelium against inflammatory reaction underlying atherosclerosis.

  16. Progranulin protects vascular endothelium against atherosclerotic inflammatory reaction via Akt/eNOS and nuclear factor-κB pathways.

    Directory of Open Access Journals (Sweden)

    Hwan-Jin Hwang

    Full Text Available OBJECTIVE: Atherosclerosis is considered a chronic inflammatory disease, initiated by activation and dysfunction of the endothelium. Recently, progranulin has been regarded as an important modulator of inflammatory processes; however, the role for prgranulin in regulating inflammation in vascular endothelial cells has not been described. METHOD AND RESULTS: Signaling pathways mediated by progranulin were analyzed in human umbilical vein endothelial cells (HUVECs treated with progranulin. Progranulin significantly induced Akt and endothelial nitric oxide synthase (eNOS phosphorylation in HUVECs, an effect that was blocked with Akt inhibitor. Furthermore, nitric oxide (NO level, the end product of Akt/eNOS pathway, was significantly upregulated after progranulin treatment. Next, we showed that progranulin efficiently inhibited lipopolysaccharide (LPS-mediated pro-inflammatory signaling. LPS-induced phosphorylation of IκB and nuclear factor-κB (NF-κB levels decreased after progranulin treatment. Also, progranulin blocked translocation of NF-κB from the cytosol to the nucleus. In addition, progranulin significantly reduced the expression of vascular cell adhesion molecule-1 (VCAM-1 and intercellular adhesion molecule-1 (ICAM-1 by inhibiting binding of NF- κB to their promoter regions and blocked attachment of monocytes to HUVECs. Progranulin also significantly reduced the expression of tumor necrosis factor receptor-α (TNF-α and monocyte chemo-attractant protein-1 (MCP-1, the crucial inflammatory molecules known to aggravate atherosclerosis. CONCLUSION: Progranulin efficiently inhibited LPS-mediated pro-inflammatory signaling in endothelial cells through activation of the Akt/eNOS pathway and attenuation of the NF-κB pathway, suggesting its protective roles in vascular endothelium against inflammatory reaction underlying atherosclerosis.

  17. Impact of organic-mineral matter interactions on thermal reaction pathways for coal model compounds

    Energy Technology Data Exchange (ETDEWEB)

    Buchanan, A.C. III; Britt, P.F.; Struss, J.A. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.

    1995-07-01

    Coal is a complex, heterogeneous solid that includes interdispersed mineral matter. However, knowledge of organic-mineral matter interactions is embryonic, and the impact of these interactions on coal pyrolysis and liquefaction is incomplete. Clay minerals, for example, are known to be effective catalysts for organic reactions. Furthermore, clays such as montmorillonite have been proposed to be key catalysts in the thermal alteration of lignin into vitrinite during the coalification process. Recent studies by Hatcher and coworkers on the evolution of coalified woods using microscopy and NMR have led them to propose selective, acid-catalyzed, solid state reaction chemistry to account for retained structural integrity in the wood. However, the chemical feasibility of such reactions in relevant solids is difficult to demonstrate. The authors have begun a model compound study to gain a better molecular level understanding of the effects in the solid state of organic-mineral matter interactions relevant to both coal formation and processing. To satisfy the need for model compounds that remain nonvolatile solids at temperatures ranging to 450 C, model compounds are employed that are chemically bound to the surface of a fumed silica (Si-O-C{sub aryl}linkage). The organic structures currently under investigation are phenethyl phenyl ether (C{sub 6}H{sub 5}CH{sub 2}CH{sub 2}OC{sub 6}H{sub 5}) derivatives, which serve as models for {beta}-alkyl aryl ether units that are present in lignin and lignitic coals. The solid-state chemistry of these materials at 200--450 C in the presence of interdispersed acid catalysts such as small particle size silica-aluminas and montmorillonite clay will be reported. Initial focus will be on defining the potential impact of these interactions on coal pyrolysis and liquefaction.

  18. The role of reaction pathways and support interactions in the development of high activity hydrotreating catalysts

    DEFF Research Database (Denmark)

    Topsøe, Henrik; Hinnemann, Berit; Nørskov, Jens Kehlet

    2005-01-01

    structures may be present as single sulfide sheets. Thus, stacking is not an essential feature of Type II catalysts. The article illustrates how the new scientific insight has aided the introduction of the new high activity BRIM (TM) type catalysts for FCC pre-treatment and production of ultra low sulfur...... exhibiting a metallic character are observed to be involved in adsorption, hydrogenation and C-S bond cleavage. The insight is seen to provide a new framework for understanding the DDS and HYD pathways and the role of steric hindrance and poisons. Density functional theory (DFT) calculations have illustrated...... how support interactions may influence the activity of sulfided catalysts. The brim sites and the tendency to form vacancies are seen to differ in types I and II Co-Mo-S. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) studies show that the high activity Type II...

  19. Quantifying Fenton reaction pathways driven by self-generated H2O2 on pyrite surfaces

    Science.gov (United States)

    Gil-Lozano, C.; Davila, A. F.; Losa-Adams, E.; Fairén, A. G.; Gago-Duport, L.

    2017-03-01

    Oxidation of pyrite (FeS2) plays a significant role in the redox cycling of iron and sulfur on Earth and is the primary cause of acid mine drainage (AMD). It has been established that this process involves multi-step electron-transfer reactions between surface defects and adsorbed O2 and H2O, releasing sulfoxy species (e.g., S2O32-, SO42-) and ferrous iron (Fe2+) to the solution and also producing intermediate by-products, such as hydrogen peroxide (H2O2) and other reactive oxygen species (ROS), however, our understanding of the kinetics of these transient species is still limited. We investigated the kinetics of H2O2 formation in aqueous suspensions of FeS2 microparticles by monitoring, in real time, the H2O2 and dissolved O2 concentration under oxic and anoxic conditions using amperometric microsensors. Additional spectroscopic and structural analyses were done to track the dependencies between the process of FeS2 dissolution and the degradation of H2O2 through the Fenton reaction. Based on our experimental results, we built a kinetic model which explains the observed trend of H2O2, showing that FeS2 dissolution can act as a natural Fenton reagent, influencing the oxidation of third-party species during the long term evolution of geochemical systems, even in oxygen-limited environments.

  20. Reaction pathway towards formation of cobalt single chain magnets and nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Balaji, G.; Desilva, Rohini M.; Palshin, V. [Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States); Desilva, N. [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Palmer, G. [Department of Biochemistry and Cell Biology, Rice University, MS 140, 6100 Main street, Houston, TX 77251 (United States); Kumar, Challa S.S.R., E-mail: ckumar1@lsu.ed [Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States)

    2010-03-15

    With the advent of molecular magnets the quest for suitable high density magnetic storage materials has fuelled further research in this area. Here in this report, we present a detailed mechanistic investigation of thermal decomposition of cyclopentadienyl cobalt [CoCp(CO){sub 2}] precursor where Cp is the cyclopentadienyl moiety. The reaction revealed the formation of cobalt nanoparticles (Co-NPs) through an isolable reaction intermediate characterized as a Single Chain Magnet (SCM), [Co(Cp){sub 2}]{sub 2}CoCl{sub 4} (1). The SQUID magnetic measurements showed the presence of very strong antiferromagnetic interactions between Co{sup 2+} ions. The zero-field cooled (ZFC) and field cooled (FC) magnetization curves branch out below 5 K and there is evidence for frequency dependent complex susceptibility along with a maximum observed around 2.5 K. The optical studies indicated that the Co{sup 2+} d-d transition is influenced by the polarity of the solvents. The cobalt nanoparticles (Co-NPs) were obtained, either directly from 1 or from its precursor. They are spherical in shape with a mean size 15 nm, have fcc crystal structure and were found to be ferromagnetic at room temperature.

  1. Possible reaction pathways of the lincomycin molecule according to the DFT calculation method

    Directory of Open Access Journals (Sweden)

    Eren Bahar

    2017-01-01

    Full Text Available Human-used antibiotics are eliminated from the body with little or no transformation at all. Traces of eliminated antibiotics enter the receiving environment directly since they cannot be treated in prevalent wastewater treatment facilities. Thus, wastewaters containing traces of antibiotics have to be treated accordingly. Lincomycin is subsequently isolated from Streptomyces lincolnensis. Lincomycin and its derivatives are antibiotics exhibiting biological activity against Gram-positive bacteria, and are natural antibiotics in the environment as pollutants. This study aims to predict the degradation mechanism of lincomycin molecule in the gaseous phase and aqueous media. Probable reaction path of lincomycin molecule with OH radicals was analyzed. Optimized geometry was calculated via Gauss View 5. Subsequently, the lowest energy status was determined through geometric optimization via Gaussian 09 program. Aiming to determine the intermediates in photocatalytic degradation mechanism of lincomycin, geometric optimization of the molecule was realized through DFT method. Activation energy for the probable reaction path was calculated, and their most stable state from the thermodynamic perspective determined for the gaseous phase and aqueous media. Impact of water solvent was investigated using the conductor-like screening solvation model (COSMO. The predicted mechanism was confirmed by comparison with experimental results on simple structures reported in literature.

  2. Bridge mediated two-electron transfer reactions: Analysis of stepwise and concerted pathways

    International Nuclear Information System (INIS)

    Petrov, E.G.; May, V.

    2004-01-01

    A theory of nonadiabatic donor (D)-acceptor (A) two-electron transfer (TET) mediated by a single regular bridge (B) is developed. The presence of different intermediate two-electron states connecting the reactant state D -- BA with the product state DBA -- results in complex multiexponential kinetics. The conditions are discussed at which a reduction to two-exponential as well as single-exponential kinetics becomes possible. For the latter case the rate K TET is calculated, which describes the bridge-mediated reaction as an effective two-electron D-A transfer. In the limit of small populations of the intermediate TET states D - B - A, DB -- A, D - BA - , and DB - A - , K TET is obtained as a sum of the rates K TET (step) and K TET (sup) . The first rate describes stepwise TET originated by transitions of a single electron. It starts at D -- BA and reaches DBA -- via the intermediate state D - BA - . These transitions cover contributions from sequential as well as superexchange reactions all including reduced bridge states. In contrast, a specific two-electron superexchange mechanism from D -- BA to DBA -- defines K TET (sup) . An analytic dependence of K TET (step) and K TET (sup) on the number of bridging units is presented and different regimes of D-A TET are studied

  3. Survivability and Fusibility in Reactions Leading to Heavy Nuclei in the Vicinity of the N=126 Closed Shell

    International Nuclear Information System (INIS)

    Sagaidak, R. N.

    2009-01-01

    Nuclear fission is well suited to study the dynamic properties and dissipative processes in cold and moderately excited nuclei. It is also a unique tool to explore level density and shell effects at an extreme deformation. Despite the significant progress in the fission studies, the isospin dependence of fission properties and, in particular, of fission barrier heights still remains an open problem. Theoretical fission model parameters are tuned by using the experimental nuclear and fission data close to stability [1]. The models provide a reasonable description of the fission barriers close to the stability line. However, large deviations are observed between predictions of different models for the fission barriers of very neutron-deficient and neutron-rich nuclei. These discrepancies (by as much as 20-30 MeV, see, e.g. [2]) become especially important in the r-process calculations for extremely neutron-rich nuclei, whose fission barriers determine the termination of the r-process by fission [3]. Unfortunately, such neutron-rich nuclei will probably not become accessible in the nearest experiments. Therefore, fission properties of exotic nuclei and especially their isospin dependence can be investigated in alternative regions of the Nuclide Chart, which are accessible for such studies now. Fusion-evaporation cross sections for heavy fissile nuclei obtained in heavy ion induced reactions as well as their fission cross sections are mainly determined by statistical properties of decaying compound nuclei (CN) and first of all by the fission-barrier heights of nuclei involved in the de-excitation chains leading to observable evaporation residues (ER). At the same time, the ER production and fission in nearly symmetric projectile-target fusion reactions leading to the most neutron-deficient CN could be strongly suppressed due to the quasi-fission (QF) effect [4], as observed recently in the 4 8C a induced reactions leading to Ra [5] and Pb [6] CN. The production of

  4. Kinetic and Reaction Pathway Analysis in the Application of Botulinum Toxin A for Wound Healing

    Directory of Open Access Journals (Sweden)

    Frank J. Lebeda

    2012-01-01

    Full Text Available A relatively new approach in the treatment of specific wounds in animal models and in patients with type A botulinum toxin is the focus of this paper. The indications or conditions include traumatic wounds (experimental and clinical, surgical (incision wounds, and wounds such as fissures and ulcers that are signs/symptoms of disease or other processes. An objective was to conduct systematic literature searches and take note of the reactions involved in the healing process and identify corresponding pharmacokinetic data. From several case reports, we developed a qualitative model of how botulinum toxin disrupts the vicious cycle of muscle spasm, pain, inflammation, decreased blood flow, and ischemia. We transformed this model into a minimal kinetic scheme for healing chronic wounds. The model helped us to estimate the rate of decline of this toxin's therapeutic effect by calculating the rate of recurrence of clinical symptoms after a wound-healing treatment with this neurotoxin.

  5. Effect of temperature on the reaction pathway of calcium carbonate formation via precursor phases

    Science.gov (United States)

    Purgstaller, Bettina; Mavromatis, Vasileios; Konrad, Florian; Dietzel, Martin

    2016-04-01

    It has been earlier postulated that some biogenic and sedimentary calcium carbonate (CaCO3) minerals (e.g. calcite and aragonite) are secondary in origin and have originally formed via a metastable calcium carbonate precursor phase (e.g. amorphous CaCO3, [1-2]). Such formation pathways are likely affected by various physicochemical parameters including aqueous Mg and temperature. In an effort to improve our understanding on the formation mechanism of CaCO3 minerals, precipitation experiments were carried out by the addition of a 0.6 M (Ca,Mg)Cl2 solution at distinct Mg/Ca ratios (1/4 and 1/8) into a 1 M NaHCO3 solution under constant pH conditions(8.3 ±0.1). The formation of CaCO3 was systematically examined as a function of temperature (6, 12, 18 and 25 ±0.3° C). During the experimental runs mineral precipitation was monitored by in situ Raman spectroscopy as well as by continuous sampling and analyzing of precipitates and reactive solutions. The results revealed two pathways of CaCO3 formation depending on the initial Mg/Ca ratio and temperature: (i) In experiments with a Mg/Ca ratio of 1/4 at ≤ 12° C as well as in experiments with a Mg/Ca ratio of 1/8 at ≤ 18° C, ikaite (CaCO3 6H2O) acts as a precursor phase for aragonite formation. (ii) In contrast higher temperatures induced the formation of Mg-rich amorphous CaCO3 (Mg-ACC) which was subsequently transformed to Mg-rich calcite. In situ Raman spectra showed that the transformation of Mg-ACC to Mg-calcite occurs at a higher rate (˜ 8 min) compared to that of ikaite to aragonite (> 2 h). Thus, the formation of aragonite rather than of Mg-calcite occurs due to the slower release of Ca2+and CO32- ions into the Mg-rich reactive solution during retarded ikaite dissolution. This behavior is generally consistent with the observation that calcite precipitation is inhibited at elevated aqueous Mg/Ca ratios. [1] Addadi L., Raz S. and Weiner S. (2003) Advanced Materials 15, 959-970. [2] Rodriguez-Blanco J. D

  6. Reciprocal subsidies and food web pathways leading to chum salmon fry in a temperate marine-terrestrial ecotone.

    Science.gov (United States)

    Romanuk, Tamara N; Levings, Colin D

    2010-04-08

    Stable isotope analysis was used to determine the relative proportions of terrestrial and marine subsidies of carbon to invertebrates along a tidal gradient (low-intertidal, mid-intertidal, high-intertidal, supralittoral) and to determine the relative importance of terrestrial carbon in food web pathways leading to chum salmon fry Oncorhynchus keta (Walbaum) in Howe Sound, British Columbia. We found a clear gradient in the proportion of terrestrially derived carbon along the tidal gradient ranging from 68% across all invertebrate taxa in the supralittoral to 25% in the high-intertidal, 20% in the mid-intertidal, and 12% in the low-intertidal. Stable isotope values of chum salmon fry indicated carbon contributions from both terrestrial and marine sources, with terrestrially derived carbon ranging from 12.8 to 61.5% in the muscle tissue of chum salmon fry (mean 30%). Our results provide evidence for reciprocal subsidies of marine and terrestrially derived carbon on beaches in the estuary and suggest that the vegetated supralittoral is an important trophic link in supplying terrestrial carbon to nearshore food webs.

  7. A critical assessment of theoretical methods for finding reaction pathways and transition states of surface processes

    International Nuclear Information System (INIS)

    Klimes, JirI; Michaelides, Angelos; Bowler, David R

    2010-01-01

    The performance of a variety of techniques for locating transition states on potential energy surfaces is evaluated within the density functional theory framework. Diffusion of a water molecule across NaCl(001) and HCl bond breaking on the same surface are treated as general test cases; the former is an example of a low barrier diffusion process and the latter an example of a relatively high barrier covalent bond rupture event. The methods considered include the nudged elastic band (NEB), Dewar, Healy and Stewart (DHS), dimer, constrained optimization (CO), activation-relaxation technique (ART) and one-side growing string (OGS) as well as novel combinations of the DHS with growing string (DHS + GS) and DHS plus climbing image (CI-DHS). A key conclusion to come from this study is that the NEB method is relatively fast, especially when just a single (climbing) image is used. Indeed, using more images represents an unnecessary computational burden for our set of processes. The dimer method exhibits variable performance; being poor for the water diffusion processes, which have small activation energies, but much more efficient for the HCl bond breaking process which has a higher barrier. When only a poor initial guess of the transition state geometry is available, the CI-DHS scheme is one of the most efficient techniques considered. And as a means to quickly establish an approximate minimum energy pathway the DHS + GS scheme offers some potential.

  8. Effect of trace elements on the interface reactions between two lead-free solders and copper or nickel substrates

    Directory of Open Access Journals (Sweden)

    Soares D.

    2007-01-01

    Full Text Available Traditional Sn-Pb solder alloys are being replaced, because of environmental and health concerns about lead toxicity. Among some alternative alloy systems, the Sn-Zn and Sn-Cu base alloy systems have been studied and reveal promising properties. The reliability of a solder joint is affected by the solder/substrate interaction and the nature of the layers formed at the interface. The solder/substrate reactions, for Sn-Zn and Sn-Cu base solder alloys, were evaluated in what concerns the morphology and chemical composition of the interface layers. The effect of the addition of P, at low levels, on the chemical composition of the layers present at the interface was studied. The phases formed at the interface between the Cu or Ni substrate and a molten lead-free solder at 250ºC, were studied for different stage times and alloy compositions. The melting temperatures, of the studied alloys, were determined by Differential Scanning Calorimetry (DSC. Identification of equilibrium phases formed at the interface layer, and the evaluation of their chemical composition were performed by Scanning Electron Microscopy (SEM/EDS. Different interface characteristics were obtained, namely for the alloys containing Zn. The obtained IML layer thickness was compared, for both types of alloy systems.

  9. Reaction pathway of the degradation of the p-hydroxybenzoic acid by sulfate radical generated by ionizing radiations

    International Nuclear Information System (INIS)

    Criquet, Justine; Leitner, Nathalie Karpel Vel

    2015-01-01

    The degradation of p-hydroxybenzoic acid (HBA) in aqueous solutions by ionizing radiation was studied. The phenolic pollutant was easily removed by the electron beam irradiation, as more than 80% of the initial 100 µM introduced was degraded for a dose of 600 Gy. It was shown that the addition of persulfate, producing the sulfate radical as additional reactive species, induced a change in the reaction pathway. LC–MS analyses were performed in order to identify the different by-products formed. In the absence of persulfate, the main by-product formed was 3,4-dihydroxybenzoic acid, while in presence of persulfate, 1,4-benzoquinone was detected and the hydroxylated by-products were not present. A reaction pathway of HBA degradation by hydroxyl and sulfate radicals was proposed from the identification of the chemical structure of the different by-products detected. The influences of pH and dissolved oxygen were also studied. A high decline of HBA degradation was observed at pH 11 compared to pH 4.5, this decrease was minimized in the presence of persulfate. The dissolved oxygen concentration was found to be a limiting parameter of HBA degradation, however an excess of dissolved oxygen in solution did not improve the degradation to a large extent. - Highlights: • p-Hydroxybenzoic acid (HBA) is easily removed by e-beam irradiation. • The sulfate radicals formed from persulfate induce loss of the benzoic acid skeleton. • The dissolved oxygen concentration is a limiting parameter of the HBA degradation. • The effect of pH is minimized in presence of persulfate

  10. Formation of nitrogen-containing compounds during microwave pyrolysis of microalgae: Product distribution and reaction pathways.

    Science.gov (United States)

    Huang, Feng; Tahmasebi, Arash; Maliutina, Kristina; Yu, Jianglong

    2017-12-01

    The formation of nitrogen-containing compounds in bio-oil during microwave pyrolysis of Chlorella and Spirulina microalgae has been investigated in this study. Activated carbon (AC) and magnetite (Fe 3 O 4 ) were used as microwave receptors during microwave pyrolysis experiments. It has been found that the use of Fe 3 O 4 increased the total yield of bio-oil. The use of different microwave receptors did not seem to have affected the total yield of nitrogen-containing compounds in the bio-oil. However, Fe 3 O 4 promoted the formation of nitrogen-containing aliphatics, thereby reducing the formation of nitrogen-containing aromatics. The use of AC promoted the dehydration reactions during amino acid decomposition, thereby enhancing the formation of nitrogen-containing aromatics during pyrolysis. From the gas chromatography-mass spectrometry (GC-MS) analysis results, the major high-value nitrogen-containing compounds in the pyrolysis bio-oil of Chlorella and Spirulina were identified as indole and dodecamide. The formation mechanisms of nitrogen-containing compounds were proposed and discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Reaction pathways of photoexcited retinal in proteorhodopsin studied by pump-dump-probe spectroscopy.

    Science.gov (United States)

    Rupenyan, Alisa; van Stokkum, Ivo H M; Arents, Jos C; van Grondelle, Rienk; Hellingwerf, Klaas J; Groot, Marie Louise

    2009-12-17

    Proteorhodopsin (pR) is a membrane-embedded proton pump from the microbial rhodopsin family. Light absorption by its retinal chromophore initiates a photocycle, driven by trans/cis isomerization on the femtosecond to picosecond time scales. Here, we report a study on the photoisomerization dynamics of the retinal chromophore of pR, using dispersed ultrafast pump-dump-probe spectroscopy. The application of a pump pulse initiates the photocycle, and with an appropriately tuned dump pulse applied at a time delay after the dump, the molecules in the initial stages of the photochemical process can be de-excited and driven back to the ground state. In this way, we were able to resolve an intermediate on the electronic ground state that represents chromophores that are unsuccessful in isomerization. In particular, the fractions of molecules that undergo slow isomerization (20 ps) have a high probability to enter this state rather than the isomerized K-state. On the ground state reaction surface, return to the stable ground state conformation via a structural or vibrational relaxation occurs in 2-3 ps. Inclusion of this intermediate in the kinetic scheme led to more consistent spectra of the retinal-excited state, and to a more accurate estimation of the quantum yield of isomerization (Phi = 0.4 at pH 6).

  12. Transformation products and reaction pathways of carbamazepine during photocatalytic and sonophotocatalytic treatment

    International Nuclear Information System (INIS)

    Jelic, A.; Michael, I.; Achilleos, A.; Hapeshi, E.; Lambropoulou, D.; Perez, S.; Petrovic, M.; Fatta-Kassinos, D.; Barcelo, D.

    2013-01-01

    Highlights: • Degradation of CBZ during US, TiO 2 /UV and TiO 2 /UV/US processes has been evaluated. • The combined TiO 2 /UV/US oxidation resulted in significant enhancement of the CBZ degradation rate. • Transformation products were identified and the transformation pathways were proposed. • An acute toxicity test showed an increase in toxicity over the time-course of the studied processes. -- Abstract: This study examines the degradation of the antiepileptic carbamazepine (CBZ) by sonolysis, TiO 2 -based heterogeneous photocatalysis under UV-A and simulated solar irradiation, and by the combined use of UV-A and ultrasound irradiation (i.e. sonophotocatalysis) in demineralized water, ground water and effluent wastewater. The processes were compared with respect to substrate conversion rate and the extent of DOC reduction as a measure of mineralization. CBZ was degraded following a pseudo-first order kinetics. Sonophotocatalysis provided the highest rate of CBZ transformation over the time-course of the experiment while the degree of DOC removal in pure water was similar for all the studied treatments (around 40%), and always lower than CBZ conversion. This indicated that a considerable organic load remained in the treated solutions that could also be attributed to the presence of persistent oxidation products. UPLC–(+ESI)-QToF-MS was employed to determine major CBZ-related transformation products. Several recalcitrant hydroxy- and keto-derivatives of CBZ were tentatively identified. A Daphnia magna bioassay was used to evaluate the potential toxicity of the samples collected at different time points showing that the mixtures were highly toxic to D. magna

  13. Transformation products and reaction pathways of carbamazepine during photocatalytic and sonophotocatalytic treatment

    Energy Technology Data Exchange (ETDEWEB)

    Jelic, A. [Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC), Jordi Girona 18-26, 08034 Barcelona (Spain); Michael, I.; Achilleos, A.; Hapeshi, E. [Department of Civil and Environmental Engineering, University of Cyprus, 1 Panepistimiou Avenue, P.O. Box 20537, 1678 Nicosia (Cyprus); Nireas, International Water Research Centre, University of Cyprus, 1 Panepistimiou Avenue, P.O. Box 20537, 1678 Nicosia (Cyprus); Lambropoulou, D. [Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Perez, S., E-mail: spsqam@idaea.csic.es [Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC), Jordi Girona 18-26, 08034 Barcelona (Spain); Petrovic, M. [Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technological Park of the University of Girona, 101-E-17003 Girona (Spain); Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluis Companys 23, 08010 Barcelona (Spain); Fatta-Kassinos, D. [Department of Civil and Environmental Engineering, University of Cyprus, 1 Panepistimiou Avenue, P.O. Box 20537, 1678 Nicosia (Cyprus); Nireas, International Water Research Centre, University of Cyprus, 1 Panepistimiou Avenue, P.O. Box 20537, 1678 Nicosia (Cyprus); Barcelo, D. [Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technological Park of the University of Girona, 101-E-17003 Girona (Spain); Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluis Companys 23, 08010 Barcelona (Spain)

    2013-12-15

    Highlights: • Degradation of CBZ during US, TiO{sub 2}/UV and TiO{sub 2}/UV/US processes has been evaluated. • The combined TiO{sub 2}/UV/US oxidation resulted in significant enhancement of the CBZ degradation rate. • Transformation products were identified and the transformation pathways were proposed. • An acute toxicity test showed an increase in toxicity over the time-course of the studied processes. -- Abstract: This study examines the degradation of the antiepileptic carbamazepine (CBZ) by sonolysis, TiO{sub 2}-based heterogeneous photocatalysis under UV-A and simulated solar irradiation, and by the combined use of UV-A and ultrasound irradiation (i.e. sonophotocatalysis) in demineralized water, ground water and effluent wastewater. The processes were compared with respect to substrate conversion rate and the extent of DOC reduction as a measure of mineralization. CBZ was degraded following a pseudo-first order kinetics. Sonophotocatalysis provided the highest rate of CBZ transformation over the time-course of the experiment while the degree of DOC removal in pure water was similar for all the studied treatments (around 40%), and always lower than CBZ conversion. This indicated that a considerable organic load remained in the treated solutions that could also be attributed to the presence of persistent oxidation products. UPLC–(+ESI)-QToF-MS was employed to determine major CBZ-related transformation products. Several recalcitrant hydroxy- and keto-derivatives of CBZ were tentatively identified. A Daphnia magna bioassay was used to evaluate the potential toxicity of the samples collected at different time points showing that the mixtures were highly toxic to D. magna.

  14. Investigation of corrosion, water reaction, polonium evaporation and bismuth resource in liquid metal lead-bismuth technology

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Hideki; Takizuka, Takakazu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kitano, Teruaki [Mitsui Shipbuilding and Engineering Co. Ltd., Tokyo (Japan)

    2000-10-01

    Lead-bismuth is the first candidate material for liquid metal target find coolant of fueled blanket system in accelerator-driven system (ADS) studied at JAERI. Advantages of the lead-bismuth utilization are non-active material, very low capture cross section, low melting point of 125degC and high boiling point of 1670degC, and beside coolant void reactivity become negative. But problems are due to the high corrosivity to most of the structural materials and the corrosive data are scarcity. In this report, corrosivity, reaction with water, thermal-hydraulics, chemical toxicity etc. are studied by investigating some facilities utilized and researched really for lead or lead-bismuth. And, furthermore, polonium evaporation rate and bismuth resource are investigated. Main results obtained are as follows: (1) In a refinery, there are enough employment experience for liquid Pb-Bi in period of about 17 years and not corrosion for the thermal conductive materials (1Cr-0.5Mo steel) used under the condition of natural convection with temperature around 400degC. (2) In Russia, extensive experience in the use as Russian submarines and in R and D during about 50 years are available. And as a result, it will be able to lead approximately zero corrosion for Cr-Si materials by adjusting oxygen film with oxygen concentration control between 10{sup -7} to 10{sup -5}% mass. However, the corrosion data are not enough systematically collected involving them in radiation dose field. (3) In liquid-dropping experiment, it is shown that interaction between water and high temperature liquid Pb-Bi is reduced steeply with rising of atmosphere pressure. But, in order to design the second circuit removal model of ADS, the interaction should be evaluated by water continuous injection experiment. (4) Polonium forms PbPo in Pb-Bi, and the evaporation rate become less three factor than that of Po, and furthermore, the rate decreases in the atmosphere. The effects of Po on employee and environment

  15. An unexpected reaction pathway in the synthesis of the ABCE framework of strychnine-type alkaloids - A multidisciplinary study

    Science.gov (United States)

    Šoral, Michal; Markus, Jozef; Doháňošová, Jana; Šoralová, Stanislava; Dvoranová, Dana; Chyba, Andrej; Moncol, Ján; Berkeš, Dušan; Liptaj, Tibor

    2017-01-01

    Acid-catalyzed cyclization of spirocyclic 1‧-benzyl-2‧-(prop-2-en-1-yl)spiro[indole-3,3‧-pyrrolidine]-5‧-one (1) was performed. The pentacyclic product of Povarov-like imino-Diels-Alder reaction was isolated in high yield instead of expected tetracyclic aza-Prins intermediate. The unusual exotic alkaloid-type structure of the resulting molecule 2 was unambiguously confirmed by a detailed NMR analysis using a set of 2D NMR spectra including an INADEQUATE experiment. The relative configuration of 2 was predicted from the synthesis mechanism and DFT geometry calculations and independently confirmed using NOESY and residual dipolar coupling (RDC) assisted NMR analysis in stretched crosslinked polystyrene gels. The reversibility of the cycloaddition in aprotic solvents was observed. A new reaction pathway yielding a rare 6-5-5-5 tetracyclic spiroindoline 3 was suggested. The relative configuration within the tetracyclic framework was ultimately proved using Single-crystal X-ray diffraction analysis of compound 4.

  16. Reaction pathways of furfural, furfuryl alcohol and 2-methylfuran on Cu(111) and NiCu bimetallic surfaces

    Science.gov (United States)

    Xiong, Ke; Wan, Weiming; Chen, Jingguang G.

    2016-10-01

    Hydrodeoxygenation (HDO) is an important reaction for converting biomass-derived furfural to value-added 2-methylfuran, which is a promising fuel additive. In this work, the HDO of furfural to produce 2-methylfuran occurred on the NiCu bimetallic surfaces prepared on either Ni(111) or Cu(111). The reaction pathways of furfural were investigated on Cu(111) and Ni/Cu(111) surfaces using density functional theory (DFT) calculations, temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) experiments. These studies provided mechanistic insights into the effects of bimetallic formation on enhancing the HDO activity. Specifically, furfural weakly adsorbed on Cu(111), while it strongly adsorbed on Ni/Cu(111) through an η2(C,O) configuration, which led to the HDO of furfural on Ni/Cu(111). The ability to dissociate H2 on Ni/Cu(111) is also an important factor for enhancing the HDO activity over Cu(111).

  17. Structural snapshots along the reaction pathway of Yersinia pestis RipA, a putative butyryl-CoA transferase

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Rodrigo; Lan, Benson; Latif, Yama; Chim, Nicholas [UC Irvine, 2212 Natural Sciences I, Irvine, CA 92697 (United States); Goulding, Celia W., E-mail: celia.goulding@uci.edu [UC Irvine, 2212 Natural Sciences I, Irvine, CA 92697 (United States); UC Irvine, 2302 Natural Sciences I, Irvine, CA 92697 (United States)

    2014-04-01

    The crystal structures of Y. pestis RipA mutants were determined to provide insights into the CoA transferase reaction pathway. Yersinia pestis, the causative agent of bubonic plague, is able to survive in both extracellular and intracellular environments within the human host, although its intracellular survival within macrophages is poorly understood. A novel Y. pestis three-gene rip (required for intracellular proliferation) operon, and in particular ripA, has been shown to be essential for survival and replication in interferon γ-induced macrophages. RipA was previously characterized as a putative butyryl-CoA transferase proposed to yield butyrate, a known anti-inflammatory shown to lower macrophage-produced NO levels. RipA belongs to the family I CoA transferases, which share structural homology, a conserved catalytic glutamate which forms a covalent CoA-thioester intermediate and a flexible loop adjacent to the active site known as the G(V/I)G loop. Here, functional and structural analyses of several RipA mutants are presented in an effort to dissect the CoA transferase mechanism of RipA. In particular, E61V, M31G and F60M RipA mutants show increased butyryl-CoA transferase activities when compared with wild-type RipA. Furthermore, the X-ray crystal structures of E61V, M31G and F60M RipA mutants, when compared with the wild-type RipA structure, reveal important conformational changes orchestrated by a conserved acyl-group binding-pocket phenylalanine, Phe85, and the G(V/I)G loop. Binary structures of M31G RipA and F60M RipA with two distinct CoA substrate conformations are also presented. Taken together, these data provide CoA transferase reaction snapshots of an open apo RipA, a closed glutamyl-anhydride intermediate and an open CoA-thioester intermediate. Furthermore, biochemical analyses support essential roles for both the catalytic glutamate and the flexible G(V/I)G loop along the reaction pathway, although further research is required to fully

  18. Structural snapshots along the reaction pathway of Yersinia pestis RipA, a putative butyryl-CoA transferase

    International Nuclear Information System (INIS)

    Torres, Rodrigo; Lan, Benson; Latif, Yama; Chim, Nicholas; Goulding, Celia W.

    2014-01-01

    The crystal structures of Y. pestis RipA mutants were determined to provide insights into the CoA transferase reaction pathway. Yersinia pestis, the causative agent of bubonic plague, is able to survive in both extracellular and intracellular environments within the human host, although its intracellular survival within macrophages is poorly understood. A novel Y. pestis three-gene rip (required for intracellular proliferation) operon, and in particular ripA, has been shown to be essential for survival and replication in interferon γ-induced macrophages. RipA was previously characterized as a putative butyryl-CoA transferase proposed to yield butyrate, a known anti-inflammatory shown to lower macrophage-produced NO levels. RipA belongs to the family I CoA transferases, which share structural homology, a conserved catalytic glutamate which forms a covalent CoA-thioester intermediate and a flexible loop adjacent to the active site known as the G(V/I)G loop. Here, functional and structural analyses of several RipA mutants are presented in an effort to dissect the CoA transferase mechanism of RipA. In particular, E61V, M31G and F60M RipA mutants show increased butyryl-CoA transferase activities when compared with wild-type RipA. Furthermore, the X-ray crystal structures of E61V, M31G and F60M RipA mutants, when compared with the wild-type RipA structure, reveal important conformational changes orchestrated by a conserved acyl-group binding-pocket phenylalanine, Phe85, and the G(V/I)G loop. Binary structures of M31G RipA and F60M RipA with two distinct CoA substrate conformations are also presented. Taken together, these data provide CoA transferase reaction snapshots of an open apo RipA, a closed glutamyl-anhydride intermediate and an open CoA-thioester intermediate. Furthermore, biochemical analyses support essential roles for both the catalytic glutamate and the flexible G(V/I)G loop along the reaction pathway, although further research is required to fully

  19. Pion-transfer (n,d) and (d, 3He) reactions leading to deeply bound pionic atoms

    International Nuclear Information System (INIS)

    Toki, H.; Hirenzaki, S.; Yamazaki, T.

    1990-11-01

    Theoretical studies are given on the (n,d) and (d, 3 He) reactions leading to deeply bound pionic atoms in heavy nuclei of configuration [(nl) π ·j n -1 ]J. The cross sections for various pionic and neutron-hole configurations in the case of a 208 Pb target are calculated at incident energies 300-1000 MeV/u by using the effective number approach and the eikonal approximation for distortion. The effective number with a pion in the 1s or 2p state and a neutron hole in the i 13/2 orbit peaks around the same incident energy (T n =600 MeV) as the elementary cross section n+n→d+π - , where the momentum transfer matches the angular-momentum transfer of L=5∼7. The DWIA cross section for (n,d) producing a pion in the 1s or 2p orbit at T n =600 MeV is found to be around 42 or 75 μb/sr, respectively. At T n =350 MeV, where the momentum transfer is small, quasi-substitutional states of configurations [(2p) π (3p 1/2 ) n -1 ]L=0 and [(2p) π (3p 3/2 ) n -1 ]L=0 are preferentially populated with cross sections of 190 and 380 μb/sr, respectively. The (d, 3 He) cross sections are estimated to be an order of magnitude smaller than the (n,d) cross sections. Thus, the (n,d) and (d, 3 He) reactions are found to be suited for the production of deeply bound pionic atoms. (author)

  20. Leading survey and research report for fiscal 1999. Survey and research on chemical reaction simulator technology; 1999 nendo kagaku hanno simulator gijutsu no chosa kenkyu hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Although various chemical reactions are made use of at scenes of chemical industry for the acquisition of desired chemicals, the control of reaction process governing factors, such as temperature, pressure, catalysts, solutions, etc., is found to be carried out only on the empirical basis. At the present time, rational or optimum reaction designs are not to be prepared in a short period of time in the presence of the widespread shortage of knowledge about chemical reactions and of the shortage of understanding of chemical reactions at the micro level. Leading survey and research are conducted for the development of a 'chemical reaction simulator' technology to enable the acquisition of optimum reaction designing guidelines in a short period of time. Using the simulator, a chemical of his choice is inputted by a researcher engaged in the study of an real chemical reaction and then various techniques of computer science are mobilized for the preparation of a huge number of feasible reaction routes, and high-precision simulations are conducted for the feasible reaction routes. The results achieved this fiscal year are reported. The purpose of this research and its ripple effect on new product industry creation are stated. Then the positioning, mission, and concept of such a chemical reaction simulator are described. Finally, the result of research and survey of knowledge databases and the result of research and survey of computational chemistry are stated. (NEDO)

  1. Leading survey and research report for fiscal 1999. Survey and research on chemical reaction simulator technology; 1999 nendo kagaku hanno simulator gijutsu no chosa kenkyu hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Although various chemical reactions are made use of at scenes of chemical industry for the acquisition of desired chemicals, the control of reaction process governing factors, such as temperature, pressure, catalysts, solutions, etc., is found to be carried out only on the empirical basis. At the present time, rational or optimum reaction designs are not to be prepared in a short period of time in the presence of the widespread shortage of knowledge about chemical reactions and of the shortage of understanding of chemical reactions at the micro level. Leading survey and research are conducted for the development of a 'chemical reaction simulator' technology to enable the acquisition of optimum reaction designing guidelines in a short period of time. Using the simulator, a chemical of his choice is inputted by a researcher engaged in the study of an real chemical reaction and then various techniques of computer science are mobilized for the preparation of a huge number of feasible reaction routes, and high-precision simulations are conducted for the feasible reaction routes. The results achieved this fiscal year are reported. The purpose of this research and its ripple effect on new product industry creation are stated. Then the positioning, mission, and concept of such a chemical reaction simulator are described. Finally, the result of research and survey of knowledge databases and the result of research and survey of computational chemistry are stated. (NEDO)

  2. Iodinated Contrast Media and the Alleged "Iodine Allergy": An Inexact Diagnosis Leading to Inferior Radiologic Management and Adverse Drug Reactions.

    Science.gov (United States)

    Böhm, Ingrid; Nairz, Knud; Morelli, John N; Keller, Patricia Silva Hasembank; Heverhagen, Johannes T

    2017-04-01

    Purpose  To test the hypothesis that the incomplete diagnosis "iodine allergy" is a possibly dangerous concept for patients under routine radiologic conditions. Materials and Methods  300 patients with a history of an "iodine allergy" were retrospectively screened and compared with two age-, sex-, and procedure-matched groups of patients either diagnosed with a nonspecific "iodine contrast medium (ICM) allergy" or an allergy to a specific ICM agent. For all groups, the clinical symptoms of the most recent past adverse drug reaction (ADR), prophylactic actions taken for subsequent imaging, and ultimate outcome were recorded and analyzed. Results  The diagnosis "iodine allergy" was not otherwise specified in 84.3 % patients. For this group, in most cases, the symptoms of the previous ADRs were not documented. In contrast, the type of ADR was undocumented in only a minority of patients in the comparison groups. In the group of patients with an "iodine allergy" the percentage of unenhanced CT scans was greater than within the other two groups (36.7 % vs. 28.7 %/18.6 %). ADRs following prophylactic measures were only observed in the "iodine allergy" group (OR of 9.24 95 % CI 1.16 - 73.45; p contrast media containing covalently bound iodine.. · There is a clear correlation between the exactness of the diagnosis - from the alleged "iodine allergy" to "contrast media allergy" to naming the exact culprit CM - and the quality of documentation of the symptoms.. · Management of patients diagnosed with "iodine allergy" was associated with uncertainty leading to unenhanced scans and sometimes unnecessary prophylactic actions.. · The term "iodine allergy" should be omitted, because it is potentially dangerous and can decrease the quality of radiology exams.. Citation Format · Böhm Ingrid, Nairz Knud, Morelli John N et al. Iodinated Contrast Media and the Alleged "Iodine Allergy": An Inexact Diagnosis Leading to Inferior Radiologic Management and

  3. Leading High School Transformation for College and Career Success: A Guide for Developing a System of Linked Learning Pathways

    Science.gov (United States)

    Stearns, Roman

    2014-01-01

    This ConnectEd Guide for Developing a System of Linked Learning Pathways will introduce school district leaders and their community partners to Linked Learning and a system of quality pathways that can transform high schools, instructional practice, and the student experience. Not intended to be prescriptive, this document can and should be…

  4. One-step simultaneous differential scanning calorimetry-FTIR microspectroscopy to quickly detect continuous pathways in the solid-state glucose/asparagine Maillard reaction.

    Science.gov (United States)

    Hwang, Deng-Fwu; Hsieh, Tzu-Feng; Lin, Shan-Yang

    2013-01-01

    The stepwise reaction pathway of the solid-state Maillard reaction between glucose (Glc) and asparagine (Asn) was investigated using simultaneous differential scanning calorimetry (DSC)-FTIR microspectroscopy. The color change and FTIR spectra of Glc-Asn physical mixtures (molar ratio = 1:1) preheated to different temperatures followed by cooling were also examined. The successive reaction products such as Schiff base intermediate, Amadori product, and decarboxylated Amadori product in the solid-state Glc-Asn Maillard reaction were first simultaneously evidenced by this unique DSC-FTIR microspectroscopy. The color changed from white to yellow-brown to dark brown, and appearance of new IR peaks confirmed the formation of Maillard reaction products. The present study clearly indicates that this unique DSC-FTIR technique not only accelerates but also detects precursors and products of the Maillard reaction in real time.

  5. Evaluation of potential reaction mechanisms leading to the formation of coniferyl alcohol α-linkages in lignin: a density functional theory study.

    Science.gov (United States)

    Watts, Heath D; Mohamed, Mohamed Naseer Ali; Kubicki, James D

    2011-12-21

    Five potential reaction mechanisms, each leading to the formation of an α-O-4-linked coniferyl alcohol dimer, and one scheme leading to the formation of a recently proposed free-radical coniferyl alcohol trimer were assessed using density functional theory (DFT) calculations. These potential reaction mechanisms were evaluated using both the calculated Gibbs free energies, to predict the spontaneity of the constituent reactions, and the electron-density mapped Fukui function, to determine the most reactive sites of each intermediate species. The results indicate that each reaction in one of the six mechanisms is thermodynamically favorable to those in the other mechanisms; what is more, the Fukui function for each free radical intermediate corroborates with the thermochemical results for this mechanism. This mechanism proceeds via the formation of two distinct free-radical intermediates, which then react to produce the four α-O-4 stereoisomers.

  6. Prenatal inhibition of the kynurenine pathway leads to structural changes in the hippocampus of adult rat offspring

    OpenAIRE

    Khalil, Omari S; Pisar, Mazura; Forrest, Caroline M; Vincenten, Maria C J; Darlington, L Gail; Stone, Trevor W

    2014-01-01

    Glutamate receptors for N-methyl-d-aspartate (NMDA) are involved in early brain development. The kynurenine pathway of tryptophan metabolism includes the NMDA receptor agonist quinolinic acid and the antagonist kynurenic acid. We now report that prenatal inhibition of the pathway in rats with 3,4-dimethoxy-N-[4-(3-nitrophenyl)thiazol-2-yl]benzenesulphonamide (Ro61-8048) produces marked changes in hippocampal neuron morphology, spine density and the immunocytochemical localisation of developme...

  7. Oxidation of fluoroquinolone antibiotics and structurally related amines by chlorine dioxide: Reaction kinetics, product and pathway evaluation.

    Science.gov (United States)

    Wang, Pei; He, Yi-Liang; Huang, Ching-Hua

    2010-12-01

    Fluoroquinolones (FQs) are a group of widely prescribed antibiotics and have been frequently detected in the aquatic environment. The reaction kinetics and transformation of seven FQs (ciprofloxacin (CIP), enrofloxacin (ENR), norfloxacin (NOR), ofloxacin (OFL), lomefloxacin (LOM), pipemidic acid (PIP) and flumequine (FLU)) and three structurally related amines (1-phenylpiperazine (PP), N-phenylmorpholine (PM) and 4-phenylpiperidine (PD)) toward chlorine dioxide (ClO(2)) were investigated to elucidate the behavior of FQs during ClO(2) disinfection processes. The reaction kinetics are highly pH-dependent, can be well described by a second-order kinetic model incorporating speciation of FQs, and follow the trend of OFL > ENR > CIP ∼ NOR ∼ LOM > > PIP in reactivity. Comparison among FQs and related amines and product characterization indicate that FQs' piperazine ring is the primary reactive center toward ClO(2). ClO(2) likely attacks FQ's piperazinyl N4 atom followed by concerted fragmentation involving piperazinyl N1 atom, leading to dealkylation, hydroxylation and intramolecular ring closure at the piperazine moiety. While FQs with tertiary N4 react faster with ClO(2) than FQs with secondary N4, the overall reactivity of the piperazine moiety also depends strongly on the quinolone ring through electronic effects. The reaction rate constants obtained in clean water matrix can be used to model the decay of CIP by ClO(2) in surface water samples, but overestimate the decay in wastewater samples. Overall, transformation of FQs, particularly for those with tertiary N4 amines, could be expected under typical ClO(2) disinfection conditions. However, the transformation may not eliminate antibacterial activity because of little destruction at the quinolone ring. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. Study of the properties of leading protons and antiprotons produced in p-barp exclusive reactions at 32 GeV/c

    International Nuclear Information System (INIS)

    Bogolyubskii, M.Y.; Boos, E.G.; Borovikov, A.A.

    1986-01-01

    We study the properties of leading protons and antiprotons from nondiffractive events in p-barp exclusive reactions at 32 GeV/c. It is found that the relative leading of protons and antiprotons does not depend on the final-state multiplicity and that the longitudinal momenta of leading hadrons are not correlated, but a significant part of the transverse momentum of a leading hadron is compensated by the transverse momentum of another hadron. It is shown that these experimental data are well described by the statistical model of independent particle emission but contradict the Lund string-fragmentation model

  9. Determination of the shapes and sizes of the regions in which in hadron-nucleus collisions reactions leading to the nucleon emission, particle production, and fragment evaporation occur

    International Nuclear Information System (INIS)

    Strugalski, Z.

    1985-01-01

    Shapes and sizes of the regions in target-nuclei in which reactions leading to the nucleon emission, particle production and fragment evaporation occur are determined. The region of nucleon emission is of cylindrical shape, with the diameter as large as two nucleon diameters, centered on the incident hadron course. The reactions leading to the particle production happen predominantly along the incident hadron course in nuclear matter. The fragment evaporation goes from the surface layer of the part of the target-nucleus damaged in nucleon emission process

  10. Novel bioassay for the discovery of inhibitors of the 2-C-methyl-D-erythritol 4-phosphate (MEP and terpenoid pathways leading to carotenoid biosynthesis.

    Directory of Open Access Journals (Sweden)

    Natália Corniani

    Full Text Available The 2-C-methyl-D-erythritol 4-phosphate (MEP pathway leads to the synthesis of isopentenyl diphosphate in plastids. It is a major branch point providing precursors for the synthesis of carotenoids, tocopherols, plastoquinone and the phytyl chain of chlorophylls, as well as the hormones abscisic acid and gibberellins. Consequently, disruption of this pathway is harmful to plants. We developed an in vivo bioassay that can measure the carbon flow through the carotenoid pathway. Leaf cuttings are incubated in the presence of a phytoene desaturase inhibitor to induce phytoene accumulation. Any compound reducing the level of phytoene accumulation is likely to interfere with either one of the steps in the MEP pathway or the synthesis of geranylgeranyl diphosphate. This concept was tested with known inhibitors of steps of the MEP pathway. The specificity of this in vivo bioassay was also verified by testing representative herbicides known to target processes outside of the MEP and carotenoid pathways. This assay enables the rapid screen of new inhibitors of enzymes preceding the synthesis of phytoene, though there are some limitations related to the non-specific effect of some inhibitors on this assay.

  11. Transformation of methylparaben during water chlorination: Effects of bromide and dissolved organic matter on reaction kinetics and transformation pathways.

    Science.gov (United States)

    Yoom, Hoonsik; Shin, Jaedon; Ra, Jiwoon; Son, Heejong; Ryu, Dongchoon; Kim, Changwon; Lee, Yunho

    2018-09-01

    The reaction kinetics, products, and pathways of methylparaben (MeP) during water chlorination with and without bromide (Br - ) were investigated to better understand the fate of parabens in chlorinated waters. During the chlorination of MeP-spiked waters without Br - , MeP was transformed into mono-Cl-MeP and di-Cl-MeP with apparent second-order rate constants (k app ) of 64M -1 s -1 and 243M -1 s -1 at pH7, respectively, while further chlorination of di-Cl-MeP was relatively slower (k app =1.3M -1 s -1 at pH7). With increasing Br - concentration, brominated MePs, such as mono-Br-MeP, Br-Cl-MeP, and di-Br-MeP, became major transformation products. The di-halogenated MePs (di-Cl-MeP, Br,Cl-MeP, and di-Br-MeP) showed relatively low reactivity to chlorine at pH7 (k app =1.3-4.6M -1 s -1 ) and bromine (k app =32-71M -1 s -1 ), which explains the observed high stability of di-halogenated MePs in chlorinated waters. With increasing pH from 7 to 8.5, the transformation of di-halogenated MePs was further slowed due to the decreasing reactivity of di-MePs to chlorine. The formation of the di-halogenated MePs and their further transformation become considerably faster at Br - concentrations higher than 0.5μM (40μg/L). Nonetheless, the accelerating effect of Br - diminishes in the presence of dissolved organic matter (DOM) extract (Suwannee River humic acid (SRHA)) due to a more rapid consumption of bromine by DOM than chlorine. The effect of Br - on the fate of MeP was less in the tested real water matrices, possibly due to a more rapid bromine consumption by the real water DOM compared to SRHA. A kinetic model was developed based on the determined species-specific second-order rate constants for chlorination/bromination of MeP and its chlorinated and brominated MePs and the transformation pathway information, which could reasonably simulate the transformation of MePs during the chlorination of water in the presence of Br - and selected DOM. Copyright © 2017 Elsevier B

  12. Dissection of pathways leading to antigen receptor-induced and Fas/CD95-induced apoptosis in human B cells

    NARCIS (Netherlands)

    Lens, S. M.; den Drijver, B. F.; Pötgens, A. J.; Tesselaar, K.; van Oers, M. H.; van Lier, R. A.

    1998-01-01

    To dissect intracellular pathways involved in B cell Ag receptor (BCR)-mediated and Fas-induced human B cell death, we isolated clones of the Burkitt lymphoma cell line Ramos with different apoptosis sensitivities. Selection for sensitivity to Fas-induced apoptosis also selected for clones with

  13. Investigation of the O+allyl addition/elimination reaction pathways from the OCH2CHCH2 radical intermediate

    International Nuclear Information System (INIS)

    FitzPatrick, Benjamin L.; Lau, K.-C.; Butler, Laurie J.; Lee, S.-H.; Lin, Jim Jr-Min

    2008-01-01

    These experiments study the preparation of and product channels resulting from OCH 2 CHCH 2 , a key radical intermediate in the O+allyl bimolecular reaction. The data include velocity map imaging and molecular beam scattering results to probe the photolytic generation of the radical intermediate and the subsequent pathways by which the radicals access the energetically allowed product channels of the bimolecular reaction. The photodissociation of epichlorohydrin at 193.3 nm produces chlorine atoms and c-OCH 2 CHCH 2 radicals; these undergo a facile ring opening to the OCH 2 CHCH 2 radical intermediate. State-selective resonance-enhanced multiphoton ionization (REMPI) detection resolves the velocity distributions of ground and spin-orbit excited state chlorine independently, allowing for a more accurate determination of the internal energy distribution of the nascent radicals. We obtain good agreement detecting the velocity distributions of the Cl atoms with REMPI, vacuum ultraviolet (VUV) photoionization at 13.8 eV, and electron bombardment ionization; all show a bimodal distribution of recoil kinetic energies. The dominant high recoil kinetic energy feature peaks near 33 kcal/mol. To elucidate the product channels resulting from the OCH 2 CHCH 2 radical intermediate, the crossed laser-molecular beam experiment uses VUV photoionization and detects the velocity distribution of the possible products. The data identify the three dominant product channels as C 3 H 4 O (acrolein)+H, C 2 H 4 +HCO (formyl radical), and H 2 CO (formaldehyde)+C 2 H 3 . A small signal from C 2 H 2 O (ketene) product is also detected. The measured velocity distributions and relative signal intensities at m/e=27, 28, and 29 at two photoionization energies show that the most exothermic product channel, C 2 H 5 +CO, does not contribute significantly to the product branching. The higher internal energy onset of the acrolein+H product channel is consistent with the relative barriers en route to

  14. Investigation of the O+allyl addition/elimination reaction pathways from the OCH2CHCH2 radical intermediate

    Science.gov (United States)

    Fitzpatrick, Benjamin L.; Lau, Kai-Chung; Butler, Laurie J.; Lee, Shih-Huang; Lin, Jim-Min, Jr.

    2008-08-01

    These experiments study the preparation of and product channels resulting from OCH2CHCH2, a key radical intermediate in the O+allyl bimolecular reaction. The data include velocity map imaging and molecular beam scattering results to probe the photolytic generation of the radical intermediate and the subsequent pathways by which the radicals access the energetically allowed product channels of the bimolecular reaction. The photodissociation of epichlorohydrin at 193.3 nm produces chlorine atoms and c-OCH2CHCH2 radicals; these undergo a facile ring opening to the OCH2CHCH2 radical intermediate. State-selective resonance-enhanced multiphoton ionization (REMPI) detection resolves the velocity distributions of ground and spin-orbit excited state chlorine independently, allowing for a more accurate determination of the internal energy distribution of the nascent radicals. We obtain good agreement detecting the velocity distributions of the Cl atoms with REMPI, vacuum ultraviolet (VUV) photoionization at 13.8 eV, and electron bombardment ionization; all show a bimodal distribution of recoil kinetic energies. The dominant high recoil kinetic energy feature peaks near 33 kcal/mol. To elucidate the product channels resulting from the OCH2CHCH2 radical intermediate, the crossed laser-molecular beam experiment uses VUV photoionization and detects the velocity distribution of the possible products. The data identify the three dominant product channels as C3H4O (acrolein)+H, C2H4+HCO (formyl radical), and H2CO (formaldehyde)+C2H3. A small signal from C2H2O (ketene) product is also detected. The measured velocity distributions and relative signal intensities at m/e=27, 28, and 29 at two photoionization energies show that the most exothermic product channel, C2H5+CO, does not contribute significantly to the product branching. The higher internal energy onset of the acrolein+H product channel is consistent with the relative barriers en route to each of these product channels

  15. Reaction of Aldehydes/Ketones with Electron-Deficient 1,3,5-Triazines Leading to Functionalized Pyrimidines as Diels-Alder/Retro-Diels-Alder Reaction Products: Reaction Development and Mechanistic Studies.

    Science.gov (United States)

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

    2017-03-03

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

  16. Evidence for leading mesons in anti p sup 4 He reactions at 0. 6 GeV c sup -1 incident momentum

    Energy Technology Data Exchange (ETDEWEB)

    Balestra, F.; Bossolasco, S.; Bussa, M.P.; Busso, L.; Fava, L.; Ferrero, L.; Grasso, A.; Maggiora, A.; Panzieri, D.; Piragino, G.; Piragino, R.; Tosello, F. (Ist. di Fisica Generale ' A. Avogadro' , Univ. of Turin (Italy) INFN, Sezione di Torino (Italy)); Bendiscioli, G.; Filippini, V.; Rotondi, A.; Salvini, P.; Venaglioni, A.; Zenoni, A. (Dipt. di Fisica Nucleare e Teoria, Univ. of Pavia (Italy) INFN, Sezione di Pavia (Italy)); Batusov, Yu.; Bunyatov, S.A.; Falomkin, I.V.; Nichitiu, F.; Pontecorvo, G.B.; Rozhdestvensky, A.M.; Sapozhnikov, M.G.; Tretyak, V.I. (Joint Inst. of Nuclear Research, Dubna (USSR)); Guaraldo, C. (Lab. Nazionali di Frascati dell' INFN (Italy)); Lodi Rizzini, E. (Dipt. di Automazione Industriale, Univ. of Brescia (Italy) INFN, Sezione di Pavia (Italy)); Haatuft, A.; Halsteinslid, A.; Myklebost, K.; Olsen, J.M. (Physics Dept., Univ. of Bergen (Norway)); Breivik, F.O.; Danielsen, K.M.; Jacobsen, T.; Soerensen, S.O. (Inst. of Physics, Univ. of Oslo (Norway))

    1991-01-01

    Leading mesons are seen in anti p {sup 4}He {yields} neutral strange particles at 0.6 GeV c{sup -1} incident momentum. These results differ somewhat from our previous results from anti p Ne-reactions. The concept of an ''effective target'' is useless. (orig.).

  17. An oxidative cross-coupling reaction of 4-hydroxydithiocoumarin and amines/thiols using a combination of I2 and TBHP: access to lead molecules for biomedical applications.

    Science.gov (United States)

    Mahato, Karuna; Arora, Neha; Ray Bagdi, Prasanta; Gattu, Radhakrishna; Ghosh, Siddhartha Sankar; Khan, Abu T

    2018-02-06

    A metal-free I 2 /TBHP induced highly atom economic and operationally simple oxidative cross-coupling reaction has been developed for the direct synthesis of sulfenamides/sulfanes/disulfides from the reaction of 4-hydroxydithiocoumarin and amines/thiols. The novelties of the present protocol are unprecedented S-C bond formation in addition to S-N and S-S bonds, shorter reaction time, mild and environmentally benign reaction conditions, functional group tolerance and moderate to excellent yields. Moreover, the four newly synthesized compounds namely 4q, 6d, 6e and 7a exhibit anti-proliferative activity against the breast cancer cell line MCF7, and may be lead molecules for future drug development.

  18. Lead extraction from waste funnel cathode-ray tubes glasses by reaction with silicon carbide and titanium nitride

    International Nuclear Information System (INIS)

    Yot, Pascal G.; Mear, Francois O.

    2009-01-01

    As a possibility to clean waste CRT glass, treatment of lead-containing glass with a reducing agent, SiC or TiN, leads to a porous material containing metallic lead, Pb(0), located on the surface of the pore, and unreduced lead, Pb(II). The influences of reducing agent content, of the time, and at last of the temperature on lead reduction were analysed. Our investigations have pointed out significant differences as a function of the used reducing agent. CRT glass heat treated with SiC lead to less Pb(0), compared to TiN as shown by X-ray diffraction, and differential scanning calorimetry (DSC). It has been also evidenced that lead reduction occurs on randomized zones inside the sample leading to macroscopic lead beads inside glassy samples. XPS and XAS measurements were also carried out to investigate the local structure of lead and have evidenced a change of role of lead inside the glassy framework in function of the used conditions.

  19. Histopathology and immune histochemistry of red tattoo reactions. Interface dermatitis is the lead pathology, with increase in T-lymphocytes and Langerhans cells suggesting an allergic pathomechanism.

    Science.gov (United States)

    Høgsberg, T; Thomsen, B M; Serup, J

    2015-11-01

    The majority of tattoo reactions are affiliated to red pigmented areas and often suspected to be allergic in nature. A sizeable series of biopsies of such reactions has not previously been performed. The aim of this study was to type and grade epidermal and dermal changes in tattoo reactions to red/red nuances by microscopy and immunochemistry relevant for the assessment of a possible allergic pathomechanism. Skin biopsies were taken from red tattoo reactions, graded by conventional microscopy and stained for T and B-lymphocytes, Langerhans cells, macrophages and tumour necrosis factor (TNF)-α. The study included 19 biopsies from 19 patients. The culprit colours were red/pink (n = 15) and purple/bordeaux (n = 4). Interface dermatitis was clearly the lead pathology found in 78% of samples, overlapped with granulomatous (in 32%) and pseudolymphomatous reaction patterns (in 32%). Epidermal hyperkeratosis (in 89%) was common as was leakage of red pigment across the dermo-epidermal junction, with transepidermal elimination (in 28%). The dermal cellular infiltration was dominated by T-lymphocytes (in 100%), Langerhans cells (in 95%) and macrophages (in 100%). TNF-α was common. The predominant histological pattern of chronic tattoo reactions in red/red nuances is interface dermatitis. T-lymphocytes and Langerhans cells are increased suggesting an allergic pathomechanism. TNF-α may contribute to reactions. In many cases, overlapping reactive patterns were identified. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. On a Generalized Entropy Measure Leading to the Pathway Model with a Preliminary Application to Solar Neutrino Data

    Directory of Open Access Journals (Sweden)

    Hans J. Haubold

    2013-09-01

    Full Text Available An entropy for the scalar variable case, parallel to Havrda-Charvat entropy, was introduced by the first author, and the properties and its connection to Tsallis non-extensive statistical mechanics and the Mathai pathway model were examined by the authors in previous papers. In the current paper, we extend the entropy to cover the scalar case, multivariable case, and matrix variate case. Then, this measure is optimized under different types of restrictions, and a number of models in the multivariable case and matrix variable case are obtained. Connections of these models to problems in statistical and physical sciences are pointed out. An application of the simplest case of the pathway model to the interpretation of solar neutrino data by applying standard deviation analysis and diffusion entropy analysis is provided.

  1. Targeting multiple cannabinoid anti-tumour pathways with a resorcinol derivative leads to inhibition of advanced stages of breast cancer.

    Science.gov (United States)

    Murase, Ryuichi; Kawamura, Rumi; Singer, Eric; Pakdel, Arash; Sarma, Pranamee; Judkins, Jonathon; Elwakeel, Eiman; Dayal, Sonali; Martinez-Martinez, Esther; Amere, Mukkanti; Gujjar, Ramesh; Mahadevan, Anu; Desprez, Pierre-Yves; McAllister, Sean D

    2014-10-01

    The psychoactive cannabinoid Δ(9) -tetrahydrocannabinol (THC) and the non-psychoactive cannabinoid cannabidiol (CBD) can both reduce cancer progression, each through distinct anti-tumour pathways. Our goal was to discover a compound that could efficiently target both cannabinoid anti-tumour pathways. To measure breast cancer cell proliferation/viability and invasion, MTT and Boyden chamber assays were used. Modulation of reactive oxygen species (ROS) and apoptosis was measured using dichlorodihydrofluorescein and annexin/propidium iodide, respectively, in combination with cell flow cytometry. Changes in protein levels were evaluated using Western analysis. Orthotopic and i.v. mouse models of breast cancer metastasis were used to test the activity of cannabinoids in vivo. CBD reduced breast cancer metastasis in advanced stages of the disease as the direct result of down-regulating the transcriptional regulator Id1. However, this was associated with moderate increases in survival. We therefore screened for analogues that could co-target cannabinoid anti-tumour pathways (CBD- and THC-associated) and discovered the compound O-1663. This analogue inhibited Id1, produced a marked stimulation of ROS, up-regulated autophagy and induced apoptosis. Of all the compounds tested, it was the most potent at inhibiting breast cancer cell proliferation and invasion in culture and metastasis in vivo. O-1663 prolonged survival in advanced stages of breast cancer metastasis. Developing compounds that can simultaneously target multiple cannabinoid anti-tumour pathways efficiently may provide a novel approach for the treatment of patients with metastatic breast cancer. © 2014 The British Pharmacological Society.

  2. Missed cleavage opportunities by FEN1 lead to Okazaki fragment maturation via the long-flap pathway

    KAUST Repository

    Zaher, Manal S.

    2018-01-27

    RNA-DNA hybrid primers synthesized by low fidelity DNA polymerase α to initiate eukaryotic lagging strand synthesis must be removed efficiently during Okazaki fragment (OF) maturation to complete DNA replication. In this process, each OF primer is displaced and the resulting 5\\'-single-stranded flap is cleaved by structure-specific 5\\'-nucleases, mainly Flap Endonuclease 1 (FEN1), to generate a ligatable nick. At least two models have been proposed to describe primer removal, namely short- and long-flap pathways that involve FEN1 or FEN1 along with Replication Protein A (RPA) and Dna2 helicase/nuclease, respectively. We addressed the question of pathway choice by studying the kinetic mechanism of FEN1 action on short- and long-flap DNA substrates. Using single molecule FRET and rapid quench-flow bulk cleavage assays, we showed that unlike short-flap substrates, which are bound, bent and cleaved within the first encounter between FEN1 and DNA, long-flap substrates can escape cleavage even after DNA binding and bending. Notably, FEN1 can access both substrates in the presence of RPA, but bending and cleavage of long-flap DNA is specifically inhibited. We propose that FEN1 attempts to process both short and long flaps, but occasional missed cleavage of the latter allows RPA binding and triggers the long-flap OF maturation pathway.

  3. Missed cleavage opportunities by FEN1 lead to Okazaki fragment maturation via the long-flap pathway

    KAUST Repository

    Zaher, Manal S.; Rashid, Fahad; Song, Bo; Joudeh, Luay I; Sobhy, Mohamed Abdelmaboud; Tehseen, Muhammad; Hingorani, Manju M; Hamdan, Samir

    2018-01-01

    RNA-DNA hybrid primers synthesized by low fidelity DNA polymerase α to initiate eukaryotic lagging strand synthesis must be removed efficiently during Okazaki fragment (OF) maturation to complete DNA replication. In this process, each OF primer is displaced and the resulting 5'-single-stranded flap is cleaved by structure-specific 5'-nucleases, mainly Flap Endonuclease 1 (FEN1), to generate a ligatable nick. At least two models have been proposed to describe primer removal, namely short- and long-flap pathways that involve FEN1 or FEN1 along with Replication Protein A (RPA) and Dna2 helicase/nuclease, respectively. We addressed the question of pathway choice by studying the kinetic mechanism of FEN1 action on short- and long-flap DNA substrates. Using single molecule FRET and rapid quench-flow bulk cleavage assays, we showed that unlike short-flap substrates, which are bound, bent and cleaved within the first encounter between FEN1 and DNA, long-flap substrates can escape cleavage even after DNA binding and bending. Notably, FEN1 can access both substrates in the presence of RPA, but bending and cleavage of long-flap DNA is specifically inhibited. We propose that FEN1 attempts to process both short and long flaps, but occasional missed cleavage of the latter allows RPA binding and triggers the long-flap OF maturation pathway.

  4. Methane coupling reaction in an oxy-steam stream through an OH radical pathway by using supported alkali metal catalysts

    KAUST Repository

    Liang, Yin; Li, Zhikao; Nourdine, Mohamed; Shahid, Salman; Takanabe, Kazuhiro

    2014-01-01

    A universal reaction mechanism involved in the oxidative coupling of methane (OCM) is demonstrated under oxy-steam conditions using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH

  5. The root hair assay facilitates the use of genetic and pharmacological tools in order to dissect multiple signalling pathways that lead to programmed cell death.

    Directory of Open Access Journals (Sweden)

    Joanna Kacprzyk

    Full Text Available The activation of programmed cell death (PCD is often a result of complex signalling pathways whose relationship and intersection are not well understood. We recently described a PCD root hair assay and proposed that it could be used to rapidly screen genetic or pharmacological modulators of PCD. To further assess the applicability of the root hair assay for studying multiple signalling pathways leading to PCD activation we have investigated the crosstalk between salicylic acid, autophagy and apoptosis-like PCD (AL-PCD in Arabidopsis thaliana. The root hair assay was used to determine rates of AL-PCD induced by a panel of cell death inducing treatments in wild type plants treated with chemical modulators of salicylic acid synthesis or autophagy, and in genetic lines defective in autophagy or salicylic acid signalling. The assay demonstrated that PCD induced by exogenous salicylic acid or fumonisin B1 displayed a requirement for salicylic acid signalling and was partially dependent on the salicylic acid signal transducer NPR1. Autophagy deficiency resulted in an increase in the rates of AL-PCD induced by salicylic acid and fumonisin B1, but not by gibberellic acid or abiotic stress. The phenylalanine ammonia lyase-dependent salicylic acid synthesis pathway contributed only to death induced by salicylic acid and fumonisin B1. 3-Methyladenine, which is commonly used as an inhibitor of autophagy, appeared to influence PCD induction in all treatments suggesting a possible secondary, non-autophagic, effect on a core component of the plant PCD pathway. The results suggest that salicylic acid signalling is negatively regulated by autophagy during salicylic acid and mycotoxin-induced AL-PCD. However, this crosstalk does not appear to be directly involved in PCD induced by gibberellic acid or abiotic stress. This study demonstrates that the root hair assay is an effective tool for relatively rapid investigation of complex signalling pathways leading to

  6. High-precision Pb isotopic measurements of teeth and environmental samples from Sofia (Bulgaria): insights for regional lead sources and possible pathways to the human body

    Science.gov (United States)

    Kamenov, George D.

    2008-08-01

    High-precision Pb isotopic measurements on teeth and possible sources in a given area can provide important insights for the lead (Pb) sources and pathways in the human body. Pb isotopic analyses on soils from the area of Sofia, Bulgaria show that Pb is contributed by three end-members represented by two natural sources and leaded gasoline. Sequential leaching experiments reveal that the alumosilicate fraction of the soils is mainly controlled by natural Pb derived from two mountain massifs bordering the city. Around 1/3 to a half of the Pb in the soil leachates, however, can be explained by contamination from leaded gasoline. Contemporary teeth from Sofia residents show very similar Pb isotopic compositions to the soil leachates, also indicating that around 1/3 to a half of the Pb can be explained by derivation from leaded gasoline. The remarkable isotopic similarities between the teeth and the most labile fractions of the local soils suggest that the lead can be derived from the latter. Pb incorporation in the human body via soil-plant-human or soil-plant-animal-human chains is unlikely due to the fact that no significant farming occurs in the city area. The isotopic compositions of the local soil labile fractions can be used as approximation of the bioaccessible lead for humans. Considering all possible scenarios it appears that soil and/or soil-born dust inhalation and/or ingestion is the most probable pathway for incorporation of local soil lead in the local population. The high-precision Pb isotope data presented in this work indicate that apparently the local soil is what plays major role in the human Pb exposure.

  7. A zinc enolate of amide: Preparation and application in reformasky-like reaction leading to β-hydroxy amides

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hyun Hee; Kim, Seung Hoi [Dept. of Chemistry, Dankook University, Cheonan (Korea, Republic of)

    2015-04-15

    One of the best known functionalized organic complexes is the β-hydroxy carbonyl compound. This unique functionality has been frequently found in naturally occurring bioactive derivatives. The cross-coupling reaction of A with aldehydes were carried out in the absence of any catalyst and completed in most cases within 1.0 h at room temperature. We have developed an efficient synthetic route for the preparation of β-hydroxy amides. The method involved the preparation of room-temperature-stable organo zinc reagents (A, B, and C) in THF and their subsequent coupling reactions with various carbonyl derivatives under mild conditions. Significantly, this approach using zinc enolate of amides could expand the scope of Reformatsky-like reactions. Further studies to elucidate this synthetic protocol are currently under way in our laboratory.

  8. The concern of emergence of multi-station reaction pathways that might make stepwise the mechanism of the 1,3-dipolar cycloadditions of azides and alkynes

    Science.gov (United States)

    Mohtat, Bita; Siadati, Seyyed Amir; Khalilzadeh, Mohammad Ali; Zareyee, Daryoush

    2018-03-01

    After hot debates on the concerted or stepwise nature of the mechanism of the catalyst-free 1,3-dipolar cycloadditions (DC)s, nowadays, it is being believed that for the reaction of each dipole and dipolarophile, there is a possibility that the reaction mechanism becomes stepwise, intermediates emerge, and the reaction becomes non-stereospecific. Yield of even minimal amounts of unwanted side products or stereoisomers as impurities could bring many troubles like difficult purification steps. In this project, we have made attempts to study all probable reaction channels of the azide cycloadditions with two functionalized alkynes, in order to answer this question: "is there any possibility that intermediates evolve in the catalyst-free click 1,3-DC reaction of azide-alkynes?". During the calculations, several multi-station reaction pathways supporting the stepwise and concerted mechanisms were detected. Also, the born-oppenheimer molecular dynamic (BOMD) simulation was used to find trustable geometries which could be emerged during the reaction coordinate.

  9. In situ X-ray diffraction study of the electrochemical reaction on lead electrodes in sulphate electrolytes

    International Nuclear Information System (INIS)

    Angerer, P.; Mann, R.; Gavrilovic, A.; Nauer, G.E.

    2009-01-01

    The anodic oxidation of pure lead in two acidic sulphate electrolytes with identical ionic strength (pH ∼ 0 and pH ∼ -0.1) was studied by in situ grazing incidence X-ray diffraction method (GIXD). Crystalline products such as lead sulphate (anglesite, PbSO 4 , orthorhombic), α- and β-lead dioxide (α-PbO 2 , orthorhombic, and β-PbO 2 , tetragonal), and tribasic lead sulphate hydrate with the stoichiometric composition 3PbO.PbSO 4 .H 2 O (triclinic) were detected at defined potentials. A method for the semi-quantitative determination of the thickness of the deposited layer from diffraction data is described. After the in situ measurement, the washed and dried working electrodes were additionally characterized ex situ by GIXD measurements at different angles of incidence. The phase litharge (lead oxide, t-PbO, tetragonal) and lead sulphate were observed at the surface of the lead substrate. The quantitative evaluation of the diffraction intensity of this measurement series enables the modelling of a qualitative depth profile of the layer generated during the electrochemical treatment. The anglesite phase is located in the uppermost layer, while the litharge phase was detected closer to the lead substrate

  10. Lead extraction from Cathode Ray Tube (CRT) funnel glass: Reaction mechanisms in thermal reduction with addition of carbon (C).

    Science.gov (United States)

    Lu, Xingwen; Ning, Xun-An; Chen, Da; Chuang, Kui-Hao; Shih, Kaimin; Wang, Fei

    2018-06-01

    This study quantitatively determined the extraction of lead from CRT funnel glass and examined the mechanisms of thermally reducing lead in the products of sintering Pb-glass with carbon in the pre-heated furnace. The experimentally derived results indicate that a 90.3 wt% lead extraction efficiency can be achieved with 20 wt% of C addition at 950 °C for 3 min under air. The formation of viscous semi-liquid glass blocked the oxygen supply between the interaction of C and Pb-glass, and was highly effective for the extraction of metallic Pb. A maximum of 87.3% lead recover was obtained with a C to Na 2 CO 3 ratio of 1/3 at 1200 °C. The decrease of C/Na 2 CO 3 ratio enhanced the metallic lead recovery by increasing the glass viscosity for effective sedimentation of metallic lead in the bottom. However, with the further increase of temperature and treatment time, re-vitrification of lead back to silicate-glass matrix was detected in both Pb-glass/C and Pb-glass/C/Na 2 CO 3 systems. The findings indicated that with proper controls, using C as an inexpensive reagent can effectively reduce treatment time and energy, which is crucial to a waste-to-resource technology for economically recovering lead from the waste CRT glass. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Effects of urban air pollution on the inflammatory reaction: involvement of the chemokine pathways; Impact de la pollution atmospherique urbaine sur la reponse inflammatoire: implication des chimiokines

    Energy Technology Data Exchange (ETDEWEB)

    Fahy, O.

    2000-12-01

    Urban air pollution is both gaseous and particulate, and diesel exhausts are now the main source of particles. Diesel particles consist of a carbon core with multiple adsorbed organic compounds, among witch poly-aromatic hydrocarbons. These diesel particles and associated poly-aromatic hydrocarbons are likely to play a role in the recent increase in allergic diseases. In this study, we evaluated the effects of diesel organic extracts on the initiation and the orientation of the allergen-dependent inflammatory reaction by analyzing the dis-regulation of a family of mediators involved in cellular recruitment: the chemokines. We demonstrated that mononuclear cells and alveolar macrophages from normal subjects displayed a dis-regulation in pro-inflammatory chemokine expression and production (IL-8, MCP-1, RANTES) when exposed to diesel organic extracts. In addition we observed a synergy between the effects of diesel and allergen when cells from allergic patients were exposed to both simultaneously, leading to a strong over-production of chemokines, and to the increased capacity of recruiting effector cells such as neutrophils and eosinophils. The MAP kinase pathways seemed largely involved in the transduction of diesel and allergen stimulus, since a specific inhibition almost abolished the dis-regulation of chemokine production. Diesel and allergen also appeared to favour the establishment of a type 2 immune response (pro-allergenic), by preferentially recruiting Th2 lymphocytes via the dis-regulation of chemokine expression (MDC and IP-10). Finally, the humanized SCID mouse model grafted with autologous human skin allowed the in vivo evaluation of a local over-production of chemokine, by analyzing the cellular recruitment in the skin after intra-dermal injection of recombinant chemokines. This model appears useful for the study of the mechanisms of cellular recruitment by chemokines and the potential therapeutic approaches. In conclusion, our study underlines the

  12. Health risk assessment of various metal(loid)s via multiple exposure pathways on children living near a typical lead-acid battery plant, China

    International Nuclear Information System (INIS)

    Cao, Suzhen; Duan, Xiaoli; Zhao, Xiuge; Wang, Beibei; Ma, Jin; Fan, Delong; Sun, Chengye; He, Bin; Wei, Fusheng; Jiang, Guibin

    2015-01-01

    Manufacture of lead-acid batteries is of widespread interest because of its emissions of heavy metals and metalloids into environment, harming environmental quality and consequently causing detrimental effects on human health. In this study, exposure pathways and health risks of children to heavy metal(loid)s (Pb, Cd, As, etc) were investigated based on field sampling and questionnaire. Pb was one of the most abundant elements in children's blood, with an elevated blood lead level of 12.45 μg dL −1 . Soil/dust and food were heavily polluted by targeted metal(loid)s. Food ingestion accounted for more than 80% of the total exposure for most metal(loid)s. The non-cancer risks to children were 3–10 times higher than the acceptable level of 1, while the cancer risks were 5–200 times higher than the maximum acceptable level of 1.0 × 10 −4 . The study emphasized the significance of effective environmental management, particularly to ensure food security near battery facilities. - Highlights: • The health risks of children living around a typical lead-acid battery was analyzed. • The exposure pathways of children to 12 heavy metal(loid)s were assessed. • Courtyard soil and indoor dust and duplicate food were contaminated by metal(loid)s. • Food ingestion was the major pathway for children's exposure to most metal(loid)s. • Higher potentially non-cancer and cancer risks happened to the local children. - The children living around a typical lead-acid battery plant suffered from serious health risks, which mainly attributed to food ingestion and air inhalation exposure

  13. A Tox21 Approach to Altered Epigenetic Landscapes: Assessing Epigenetic Toxicity Pathways Leading to Altered Gene Expression and Oncogenic Transformation In Vitro

    Directory of Open Access Journals (Sweden)

    Craig L. Parfett

    2017-06-01

    Full Text Available An emerging vision for toxicity testing in the 21st century foresees in vitro assays assuming the leading role in testing for chemical hazards, including testing for carcinogenicity. Toxicity will be determined by monitoring key steps in functionally validated molecular pathways, using tests designed to reveal chemically-induced perturbations that lead to adverse phenotypic endpoints in cultured human cells. Risk assessments would subsequently be derived from the causal in vitro endpoints and concentration vs. effect data extrapolated to human in vivo concentrations. Much direct experimental evidence now shows that disruption of epigenetic processes by chemicals is a carcinogenic mode of action that leads to altered gene functions playing causal roles in cancer initiation and progression. In assessing chemical safety, it would therefore be advantageous to consider an emerging class of carcinogens, the epigenotoxicants, with the ability to change chromatin and/or DNA marks by direct or indirect effects on the activities of enzymes (writers, erasers/editors, remodelers and readers that convey the epigenetic information. Evidence is reviewed supporting a strategy for in vitro hazard identification of carcinogens that induce toxicity through disturbance of functional epigenetic pathways in human somatic cells, leading to inactivated tumour suppressor genes and carcinogenesis. In the context of human cell transformation models, these in vitro pathway measurements ensure high biological relevance to the apical endpoint of cancer. Four causal mechanisms participating in pathways to persistent epigenetic gene silencing were considered: covalent histone modification, nucleosome remodeling, non-coding RNA interaction and DNA methylation. Within these four interacting mechanisms, 25 epigenetic toxicity pathway components (SET1, MLL1, KDM5, G9A, SUV39H1, SETDB1, EZH2, JMJD3, CBX7, CBX8, BMI, SUZ12, HP1, MPP8, DNMT1, DNMT3A, DNMT3B, TET1, MeCP2, SETDB2, BAZ2

  14. Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia.

    Science.gov (United States)

    Broix, Loïc; Jagline, Hélène; Ivanova, Ekaterina; Schmucker, Stéphane; Drouot, Nathalie; Clayton-Smith, Jill; Pagnamenta, Alistair T; Metcalfe, Kay A; Isidor, Bertrand; Louvier, Ulrike Walther; Poduri, Annapurna; Taylor, Jenny C; Tilly, Peggy; Poirier, Karine; Saillour, Yoann; Lebrun, Nicolas; Stemmelen, Tristan; Rudolf, Gabrielle; Muraca, Giuseppe; Saintpierre, Benjamin; Elmorjani, Adrienne; Moïse, Martin; Weirauch, Nathalie Bednarek; Guerrini, Renzo; Boland, Anne; Olaso, Robert; Masson, Cecile; Tripathy, Ratna; Keays, David; Beldjord, Cherif; Nguyen, Laurent; Godin, Juliette; Kini, Usha; Nischké, Patrick; Deleuze, Jean-François; Bahi-Buisson, Nadia; Sumara, Izabela; Hinckelmann, Maria-Victoria; Chelly, Jamel

    2016-11-01

    Neurodevelopmental disorders with periventricular nodular heterotopia (PNH) are etiologically heterogeneous, and their genetic causes remain in many cases unknown. Here we show that missense mutations in NEDD4L mapping to the HECT domain of the encoded E3 ubiquitin ligase lead to PNH associated with toe syndactyly, cleft palate and neurodevelopmental delay. Cellular and expression data showed sensitivity of PNH-associated mutants to proteasome degradation. Moreover, an in utero electroporation approach showed that PNH-related mutants and excess wild-type NEDD4L affect neurogenesis, neuronal positioning and terminal translocation. Further investigations, including rapamycin-based experiments, found differential deregulation of pathways involved. Excess wild-type NEDD4L leads to disruption of Dab1 and mTORC1 pathways, while PNH-related mutations are associated with deregulation of mTORC1 and AKT activities. Altogether, these data provide insights into the critical role of NEDD4L in the regulation of mTOR pathways and their contributions in cortical development.

  15. Osseointegration of Plateau Root Form Implants: Unique Healing Pathway Leading to Haversian-Like Long-Term Morphology.

    Science.gov (United States)

    Coelho, Paulo G; Suzuki, Marcelo; Marin, Charles; Granato, Rodrigo; Gil, Luis F; Tovar, Nick; Jimbo, Ryo; Neiva, Rodrigo; Bonfante, Estevam A

    2015-01-01

    Endosteal dental implants have been utilized as anchors for dental and orthopedic rehabilitations for decades with one of the highest treatment success rates in medicine. Such success is due to the phenomenon of osseointegration where after the implant surgical placement, bone healing results into an intimate contact between bone and implant surface. While osseointegration is an established phenomenon, the route which osseointegration occurs around endosteal implants is related to various implant design factors including surgical instrumentation and implant macro, micro, and nanometer scale geometry. In an implant system where void spaces (healing chambers) are present between the implant and bone immediately after placement, its inherent bone healing pathway results in unique opportunities to accelerate the osseointegration phenomenon at the short-term and its maintenance on the long-term through a haversian-like bone morphology and mechanical properties.

  16. Arene activation by a nonheme iron(III)-hydroperoxo complex: pathways leading to phenol and ketone products.

    Science.gov (United States)

    Faponle, Abayomi S; Banse, Frédéric; de Visser, Sam P

    2016-07-01

    Iron(III)-hydroperoxo complexes are found in various nonheme iron enzymes as catalytic cycle intermediates; however, little is known on their catalytic properties. The recent work of Banse and co-workers on a biomimetic nonheme iron(III)-hydroperoxo complex provided evidence of its involvement in reactivity with arenes. This contrasts the behavior of heme iron(III)-hydroperoxo complexes that are known to be sluggish oxidants. To gain insight into the reaction mechanism of the biomimetic iron(III)-hydroperoxo complex with arenes, we performed a computational (density functional theory) study. The calculations show that iron(III)-hydroperoxo reacts with substrates via low free energies of activation that should be accessible at room temperature. Moreover, a dominant ketone reaction product is observed as primary products rather than the thermodynamically more stable phenols. These product distributions are analyzed and the calculations show that charge interaction between the iron(III)-hydroxo group and the substrate in the intermediate state pushes the transferring proton to the meta-carbon atom of the substrate and guides the selectivity of ketone formation. These studies show that the relative ratio of ketone versus phenol as primary products can be affected by external interactions of the oxidant with the substrate. Moreover, iron(III)-hydroperoxo complexes are shown to selectively give ketone products, whereas iron(IV)-oxo complexes will react with arenes to form phenols instead.

  17. Dynamic pathways to mediate reactions buried in thermal fluctuations. I. Time-dependent normal form theory for multidimensional Langevin equation.

    Science.gov (United States)

    Kawai, Shinnosuke; Komatsuzaki, Tamiki

    2009-12-14

    We present a novel theory which enables us to explore the mechanism of reaction selectivity and robust functions in complex systems persisting under thermal fluctuation. The theory constructs a nonlinear coordinate transformation so that the equation of motion for the new reaction coordinate is independent of the other nonreactive coordinates in the presence of thermal fluctuation. In this article we suppose that reacting systems subject to thermal noise are described by a multidimensional Langevin equation without a priori assumption for the form of potential. The reaction coordinate is composed not only of all the coordinates and velocities associated with the system (solute) but also of the random force exerted by the environment (solvent) with friction constants. The sign of the reaction coordinate at any instantaneous moment in the region of a saddle determines the fate of the reaction, i.e., whether the reaction will proceed through to the products or go back to the reactants. By assuming the statistical properties of the random force, one can know a priori a well-defined boundary of the reaction which separates the full position-velocity space in the saddle region into mainly reactive and mainly nonreactive regions even under thermal fluctuation. The analytical expression of the reaction coordinate provides the firm foundation on the mechanism of how and why reaction proceeds in thermal fluctuating environments.

  18. Prenatal inhibition of the kynurenine pathway leads to structural changes in the hippocampus of adult rat offspring.

    Science.gov (United States)

    Khalil, Omari S; Pisar, Mazura; Forrest, Caroline M; Vincenten, Maria C J; Darlington, L Gail; Stone, Trevor W

    2014-05-01

    Glutamate receptors for N-methyl-d-aspartate (NMDA) are involved in early brain development. The kynurenine pathway of tryptophan metabolism includes the NMDA receptor agonist quinolinic acid and the antagonist kynurenic acid. We now report that prenatal inhibition of the pathway in rats with 3,4-dimethoxy-N-[4-(3-nitrophenyl)thiazol-2-yl]benzenesulphonamide (Ro61-8048) produces marked changes in hippocampal neuron morphology, spine density and the immunocytochemical localisation of developmental proteins in the offspring at postnatal day 60. Golgi-Cox silver staining revealed decreased overall numbers and lengths of CA1 basal dendrites and secondary basal dendrites, together with fewer basal dendritic spines and less overall dendritic complexity in the basal arbour. Fewer dendrites and less complexity were also noted in the dentate gyrus granule cells. More neurons containing the nuclear marker NeuN and the developmental protein sonic hedgehog were detected in the CA1 region and dentate gyrus. Staining for doublecortin revealed fewer newly generated granule cells bearing extended dendritic processes. The number of neuron terminals staining for vesicular glutamate transporter (VGLUT)-1 and VGLUT-2 was increased by Ro61-8048, with no change in expression of vesicular GABA transporter or its co-localisation with vesicle-associated membrane protein-1. These data support the view that constitutive kynurenine metabolism normally plays a role in early embryonic brain development, and that interfering with it has profound consequences for neuronal structure and morphology, lasting into adulthood. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  19. Mechanisms for the inversion of chirality: Global reaction route mapping of stereochemical pathways in a probable chiral extraterrestrial molecule, 2-aminopropionitrile

    International Nuclear Information System (INIS)

    Kaur, Ramanpreet; Vikas

    2015-01-01

    2-Aminopropionitrile (APN), a probable candidate as a chiral astrophysical molecule, is a precursor to amino-acid alanine. Stereochemical pathways in 2-APN are explored using Global Reaction Route Mapping (GRRM) method employing high-level quantum-mechanical computations. Besides predicting the conventional mechanism for chiral inversion that proceeds through an achiral intermediate, a counterintuitive flipping mechanism is revealed for 2-APN through chiral intermediates explored using the GRRM. The feasibility of the proposed stereochemical pathways, in terms of the Gibbs free-energy change, is analyzed at the temperature conditions akin to the interstellar medium. Notably, the stereoinversion in 2-APN is observed to be more feasible than the dissociation of 2-APN and intermediates involved along the stereochemical pathways, and the flipping barrier is observed to be as low as 3.68 kJ/mol along one of the pathways. The pathways proposed for the inversion of chirality in 2-APN may provide significant insight into the extraterrestrial origin of life

  20. Does lead use the intestinal absorptive pathways of iron? Impact of iron status on murine 210Pb and 59Fe absorption in duodenum and ileum in vivo

    International Nuclear Information System (INIS)

    Elsenhans, Bernd; Janser, Heinz; Windisch, Wilhelm; Schuemann, Klaus

    2011-01-01

    Highlights: → Absorption of 210 Pb increases much less than that of 59 Fe in murine duodena. → 210 Pb-absorption is almost equally high in murine duodenal and ileal segments. → 59 Fe absorption is much lower in ileal than in duodenal segments. → There must be an additional DMT1-independet pathway for intestinal Pb absorption. -- Abstract: Background: Human isotope studies and epidemiological trials are controversial as to whether lead absorption shares the absorptive pathways of iron and whether body lead content can be reduced by iron supplementation. Aim: To compare the impact of iron-deficiency on 59 Fe- and 210 Pb-absorption rates in duodenal and ileal segments. Methods: 59 Fe- and 210 Pb-absorption was determined in ligated duodenal and ileal segments from juvenile and adult iron-deficient and iron-adequate C57Bl6 wild-type mice (n = 6) in vivo at luminal concentrations corresponding to human exposure (Fe: 1 and 100 μmol/L; Pb: 1 μmol/L). Results and discussion: 59 Fe-absorption increased 10-15-fold in iron-deficient duodena from adult and adolescent mice. Ileal 59 Fe-absorption was 4-6 times lower than in iron-adequate duodena showing no adaptation to iron-deficiency. This in accordance to expectation as the divalent metal transport 1 (DMT1) shows low ileal expression levels. Juvenile 59 Fe-absorption was about twice as high as in adult mice. In contrast, duodenal 210 Pb-absorption was increased only 1.5-1.8-fold in iron-deficiency in juvenile and adult mice and, again in contrast to 59 Fe, ileal 210 Pb-absorption was as high as in iron-adequate duodena. Conclusions: The findings suggest a DMT1-independent pathway to mediate lead absorption along the entire small intestine in addition to DMT1-mediated duodenal uptake. Ileal lead absorption appears substantial, due the much longer residence of ingesta in the distal small intestine. Differences in lead-solubility and -binding to luminal ligands can, thus, explain the conflicting findings regarding the

  1. Molecular weight growth in Titan's atmosphere: branching pathways for the reaction of 1-propynyl radical (H3CC≡C˙) with small alkenes and alkynes.

    Science.gov (United States)

    Kirk, Benjamin B; Savee, John D; Trevitt, Adam J; Osborn, David L; Wilson, Kevin R

    2015-08-28

    The reaction of small hydrocarbon radicals (i.e.˙CN, ˙C2H) with trace alkenes and alkynes is believed to play an important role in molecular weight growth and ultimately the formation of Titan's characteristic haze. Current photochemical models of Titan's atmosphere largely assume hydrogen atom abstraction or unimolecular hydrogen elimination reactions dominate the mechanism, in contrast to recent experiments that reveal significant alkyl radical loss pathways during reaction of ethynyl radical (˙C2H) with alkenes and alkynes. In this study, the trend is explored for the case of a larger ethynyl radical analogue, the 1-propynyl radical (H3CC[triple bond, length as m-dash]C˙), a likely product from the high-energy photolysis of propyne in Titan's atmosphere. Using synchrotron vacuum ultraviolet photoionization mass spectrometry, product branching ratios are measured for the reactions of 1-propynyl radical with a suite of small alkenes (ethylene and propene) and alkynes (acetylene and d4-propyne) at 4 Torr and 300 K. Reactions of 1-propynyl radical with acetylene and ethylene form single products, identified as penta-1,3-diyne and pent-1-en-3-yne, respectively. These products form by hydrogen atom loss from the radical-adduct intermediates. The reactions of 1-propynyl radical with d4-propyne and propene form products from both hydrogen atom and methyl loss, (-H = 27%, -CH3 = 73%) and (-H = 14%, -CH3 = 86%), respectively. Together, these results indicate that reactions of ethynyl radical analogues with alkenes and alkynes form significant quantities of products by alkyl loss channels, suggesting that current photochemical models of Titan over predict both hydrogen atom production as well as the efficiency of molecular weight growth in these reactions.

  2. Disrupted Signaling through the Fanconi Anemia Pathway Leads to Dysfunctional Hematopoietic Stem Cell Biology: Underlying Mechanisms and Potential Therapeutic Strategies

    Science.gov (United States)

    Geiselhart, Anja; Lier, Amelie; Walter, Dagmar; Milsom, Michael D.

    2012-01-01

    Fanconi anemia (FA) is the most common inherited bone marrow failure syndrome. FA patients suffer to varying degrees from a heterogeneous range of developmental defects and, in addition, have an increased likelihood of developing cancer. Almost all FA patients develop a severe, progressive bone marrow failure syndrome, which impacts upon the production of all hematopoietic lineages and, hence, is thought to be driven by a defect at the level of the hematopoietic stem cell (HSC). This hypothesis would also correlate with the very high incidence of MDS and AML that is observed in FA patients. In this paper, we discuss the evidence that supports the role of dysfunctional HSC biology in driving the etiology of the disease. Furthermore, we consider the different model systems currently available to study the biology of cells defective in the FA signaling pathway and how they are informative in terms of identifying the physiologic mediators of HSC depletion and dissecting their putative mechanism of action. Finally, we ask whether the insights gained using such disease models can be translated into potential novel therapeutic strategies for the treatment of the hematologic disorders in FA patients. PMID:22675615

  3. Improvement of hairy root cultures and plants by changing biosynthetic pathways leading to pharmaceutical metabolites: strategies and applications.

    Science.gov (United States)

    Ludwig-Müller, Jutta; Jahn, Linda; Lippert, Annemarie; Püschel, Joachim; Walter, Antje

    2014-11-01

    A plethora of bioactive plant metabolites has been explored for pharmaceutical, food chemistry and agricultural applications. The chemical synthesis of these structures is often difficult, so plants are favorably used as producers. While whole plants can serve as a source for secondary metabolites and can be also improved by metabolic engineering, more often cell or organ cultures of relevant plant species are of interest. It should be noted that only in few cases the production for commercial application in such cultures has been achieved. Their genetic manipulation is sometimes faster and the production of a specific metabolite is more reliable, because of less environmental influences. In addition, upscaling in bioreactors is nowadays possible for many of these cultures, so some are already used in industry. There are approaches to alter the profile of metabolites not only by using plant genes, but also by using bacterial genes encoding modifying enzymes. Also, strategies to cope with unwanted or even toxic compounds are available. The need for metabolic engineering of plant secondary metabolite pathways is increasing with the rising demand for (novel) compounds with new bioactive properties. Here, we give some examples of recent developments for the metabolic engineering of plants and organ cultures, which can be used in the production of metabolites with interesting properties. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Quantitative evaluation of the biosynthetic pathways leading to δ-aminolevulinic acid from the Shemin precursor glycine via the C5 pathway in Arthrobacter hyalinus by analysis of 13C-labeled coproporphyrinogen III biosynthesized from [2-13C]glycine, [1-13C]acetate, and [2-13C]acetate using 13C NMR spectroscopy

    International Nuclear Information System (INIS)

    Katsumi Iida

    2013-01-01

    The biosynthetic pathways leading to δ-aminolevulinic acid (ALA) from the Shemin precursor glycine via the C5 pathway in Arthrobacter hyalinus were quantitatively evaluated by means of feeding experiments with [2- 13 C]glycine, sodium [1- 13 C]acetate, and sodium [2- 13 C]acetate, followed by analysis of the labeling patterns of coproporphyrinogen III (Copro'gen III) (biosynthesized from ALA) using 13 C NMR spectroscopy. Two biosynthetic pathways leading to ALA from glycine via the C5 pathway were identified: i.e., transformation of glycine to l-serine catalyzed by glycine hydroxymethyltransferase, and glycine synthase-catalyzed catabolism of glycine to N 5 , N 10 -methylene-tetrahydrofolic acid (THF), which reacts with another molecule of glycine to afford l-serine. l-Serine is transformed to acetyl-CoA via pyruvic acid. Acetyl-CoA enters the tricarboxylic acid cycle, affording 2-oxoglutaric acid, which in turn is transformed to l-glutamic acid. The l-glutamic acid enters the C5 pathway, affording ALA in A. hyalinus. A 13 C NMR spectroscopic comparison of the labeling patterns of Copro'gen III obtained after feeding of [2- 13 C]glycine, sodium [1- 13 C]acetate, and sodium [2- 13 C]acetate showed that [2- 13 C]glycine transformation and [2- 13 C]glycine catabolism in A. hyalinus proceed in the ratio of 52 and 48 %. The reaction of [2- 13 C]glycine and N 5 , N 10 -methylene-THF, that of glycine and N 5 , N 10 -[methylene- 13 C]methylene-THF generated from the [2- 13 C]glycine catabolism, and that of [2- 13 C]glycine and N 5 , N 10 -[methylene- 13 C]methylene-THF transformed the fed [2- 13 C]glycine to [1- 13 C]acetyl-CoA, [2- 13 C]acetyl-CoA, and [1,2- 13 C 2 ]acetyl-CoA in the ratios of 42, 37, and 21 %, respectively. These labeled acetyl-CoAs were then incorporated into ALA. Our results provide a quantitative picture of the pathways of biosynthetic transformation to ALA from glycine in A. hyalinus. (author)

  5. The evolutionary pathway from anoxygenic to oxygenic photosynthesis examined by comparison of the properties of photosystem II and bacterial reaction centers.

    Science.gov (United States)

    Allen, J P; Williams, J C

    2011-01-01

    In photosynthetic organisms, such as purple bacteria, cyanobacteria, and plants, light is captured and converted into energy to create energy-rich compounds. The primary process of energy conversion involves the transfer of electrons from an excited donor molecule to a series of electron acceptors in pigment-protein complexes. Two of these complexes, the bacterial reaction center and photosystem II, are evolutionarily related and structurally similar. However, only photosystem II is capable of performing the unique reaction of water oxidation. An understanding of the evolutionary process that lead to the development of oxygenic photosynthesis can be found by comparison of these two complexes. In this review, we summarize how insight is being gained by examination of the differences in critical functional properties of these complexes and by experimental efforts to alter pigment-protein interactions of the bacterial reaction center in order to enable it to perform reactions, such as amino acid and metal oxidation, observable in photosystem II.

  6. Fusability and survivability in reactions leading to heavy nuclei in the vicinity of the N = 126 shell

    International Nuclear Information System (INIS)

    Sagajdak, R.N.

    2008-01-01

    The production of heavy nuclei from Rn to Th around the N = 126 neutron shell in complete fusion reactions of nuclei has been considered in a systematic way in the framework of the conventional barrier-passing fusion model coupled with the Standard Statistical Model (SSM). Available data on the excitation functions for fusion and production of evaporation residues obtained in very asymmetric combinations are described with these models rather well. In the interaction of massive projectiles with heavy target nuclei quasi-fission effects appear in the entrance reaction channel. The quantity of the fusion probability introduced empirically has been used to reproduce excitation functions with the same SSM parameters (fission barriers) as those obtained in the analysis of very asymmetric combinations. A lack of stabilization against fission around N = 126 for Th nuclei was earlier explained with a reduced collective contribution to the level density in spherical nuclei. However, the present analysis shows severe inhibition for fusion, i.e., the drop in production cross sections of Th nuclei in the vicinity of N = 126 is mainly caused by entrance channel effects. The macroscopic component of fission barriers for nuclei involved in a deexcitation cascade has been derived and compared with the theoretical model predictions and available data

  7. Guanine nucleotide exchange factor αPIX leads to activation of the Rac 1 GTPase/glycogen phosphorylase pathway in interleukin (IL)-2-stimulated T cells

    DEFF Research Database (Denmark)

    Llavero, Francisco; Urzelai, Bakarne; Osinalde, Nerea

    2015-01-01

    Recently, we have reported that the active form of Rac 1 GTPase binds to the glycogen phosphorylase muscle isoform (PYGM) and modulates its enzymatic activity leading to T cell proliferation. In the lymphoid system, Rac 1 and in general other small GTPases of the Rho family participate...... in the signaling cascades that are activated after engagement of the T cell antigen receptor. However, little is known about the IL-2-dependent Rac 1 activator molecules. For the first time, a signaling pathway leading to the activation of Rac 1/PYGM in response to IL-2-stimulated T cell proliferation is described....... More specifically, αPIX, a known guanine nucleotide exchange factor for the small GTPases of the Rho family, preferentially Rac 1, mediates PYGM activation in Kit 225 T cells stimulated with IL-2. Using directed mutagenesis, phosphorylation of αPIX Rho-GEF serines 225 and 488 is required for activation...

  8. Reactions of carbonyl compounds with α,β-unsaturated nitriles as a convenient pathway to carbo- and heterocycles

    International Nuclear Information System (INIS)

    Sharanin, Yu A; Goncharenko, M P; Litvinov, Victor P

    1998-01-01

    Published data on the methods for synthesis of carbo- and heterocyclic compounds based on reactions of α,β-unsaturated nitriles with carbonyl compounds and activated phenols are surveyed. It is demonstrated that all these reactions occur via nucleophilic addition of the carbanion generated from a carbonyl compound to the double bond of an unsaturated nitrile (the Michael reaction). The main routes of transformation of the adducts into carbo- and heterocyclic compounds are considered. The methods for regioselective preparation of fused 4H-pyrans or 1,4-dihydropyridines by varying conditions of cyclisation of Michael adducts are discussed. The bibliography includes 249 references.

  9. Inhibition of Inflammation Mediated Through the Tumor Necrosis Factor α Biochemical Pathway Can Lead to Favorable Outcomes in Alzheimer Disease.

    Science.gov (United States)

    Shamim, Daniah; Laskowski, Michael

    2017-01-01

    Tumor necrosis factor α (TNF-α) inhibitors have long been used as disease-modifying agents in immune disorders. Recently, research has shown a role of chronic neuroinflammation in the pathophysiology of neurodegenerative diseases such as Alzheimer disease, and interest has been generated in the use of anti-TNF agents and TNF-modulating agents for prevention and treatment. This article extensively reviewed literature on animal studies testing these agents. The results showed a role for direct and indirect TNF-α inhibition through agents such as thalidomide, 3,6-dithiothalidomide, etanercept, infliximab, exendin-4, sodium hydrosulfide, minocycline, imipramine, and atorvastatin. Studies were performed on mice, rats, and monkeys, with induction of neurodegenerative physiology either through the use of chemical agents or through the use of transgenic animals. Most of these agents showed an improvement in cognitive function as tested with the Morris water maze, and immunohistochemical and histopathological staining studies consistently showed better outcomes with these agents. Brains of treated animals showed significant reduction in pro-inflammatory TNF-α and reduced the burden of neurofibrillary tangles, amyloid precursor protein, and β-amyloid plaques. Also, recruitment of microglial cells in the central nervous system was significantly reduced through these drugs. These studies provide a clearer mechanistic understanding of the role of TNF-α modulation in Alzheimer disease. All studies in this review explored the use of these drugs as prophylactic agents to prevent Alzheimer disease through immune modulation of the TNF inflammatory pathway, and their success highlights the need for further research of these drugs as therapeutic agents.

  10. Vapor-Phase Hydrodeoxygenation of Guaiacol to Aromatics over Pt/HBeta: Identification of the Role of Acid Sites and Metal Sites on the Reaction Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Lei [Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 P.R. China; Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Peng, Bo [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Zhu, Xinli [Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 P.R. China

    2018-02-05

    Hydrodeoxygenation of guaiacol, a phenolic compound derived from lignin fraction of biomass, over a Pt/HBeta catalyst at 350 °C and atmospheric pressure produces benzene, toluene, xylenes, and C9+ aromatics with yield of 42%, 29%, 12%, and 5%, respectively. Reaction pathways for conversion of two functional groups (hydroxyl and methoxyl) over the bifunctional catalyst were studied. Both guaiacol and intermediate products (catechol and cyclopentanone) were fed onto zeolite HBeta and Pt/SiO2 to identify the individual role of acid site and metal site. Acid sites (mainly Brønsted acid site, BAS) catalyze transalkylation and dehydroxylation reactions in sequence, producing phenol, cresols and xylenols as the major products at high conversion. Pt sites catalyze demethylation reaction resulting in catechol as the primary product, which can either be deoxygenated to phenol followed by phenol to benzene, or decarbonylated to cyclopentanone and further to butane. The close proximity of Pt and BAS in bifunctional Pt/HBeta enables both transalkylation and deoxygenation reactions with inhibited demethylation and decarbonylation reactions, producing aromatics as major final products with a total yield > 85%. Both activity and stability of bifunctional Pt/HBeta during hydrodeoxygenation of guaiacol is improved compared to HBeta and Pt/SiO2. The addition of water to the feed further improves the activity and stability via hydrolysis of O-CH3 bond of guaiacol on BAS and removing coke around Pt.

  11. High-pressure vapor-phase hydrodeoxygenation of lignin-derived oxygenates to hydrocarbons by a PtMo bimetallic catalyst: Product selectivity, reaction pathway, and structural characterization

    Energy Technology Data Exchange (ETDEWEB)

    Yohe, Sara L.; Choudhari, Harshavardhan J.; Mehta, Dhairya D.; Dietrich, Paul J.; Detwiler, Michael D.; Akatay, Cem M.; Stach, Eric A.; Miller, Jeffrey T.; Delgass, W. Nicholas; Agrawal, Rakesh; Ribeiro, Fabio H.

    2016-12-01

    High-pressure, vapor-phase, hydrodeoxygenation (HDO) reactions of dihydroeugenol (2-methoxy-4-propylphenol), as well as other phenolic, lignin-derived compounds, were investigated over a bimetallic platinum and molybdenum catalyst supported on multi-walled carbon nanotubes (5%Pt2.5%Mo/MWCNT). Hydrocarbons were obtained in 100% yield from dihydroeugenol, including 98% yield of the hydrocarbon propylcyclohexane. The final hydrocarbon distribution was shown to be a strong function of hydrogen partial pressure. Kinetic analysis showed three main dihydroeugenol reaction pathways: HDO, hydrogenation, and alkylation. The major pathway occurred via Pt catalyzed hydrogenation of the aromatic ring and methoxy group cleavage to form 4-propylcyclohexanol, then Mo catalyzed removal of the hydroxyl group by dehydration to form propylcyclohexene, followed by hydrogenation of propylcyclohexene on either the Pt or Mo to form the propylcyclohexane. Transalkylation by the methoxy group occurred as a minor side reaction. Catalyst characterization techniques including chemisorption, scanning transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy were employed to characterize the catalyst structure. Catalyst components identified were Pt particles, bimetallic PtMo particles, a Mo carbide-like phase, and Mo oxide phases.

  12. Measurements and Evaluation of Nuclear Reaction Cross Sections Leading to Various Practical Applications in Science and Technology

    Energy Technology Data Exchange (ETDEWEB)

    Khandaker, Mayeen Uddin; Lee, Young Ouk; Cho, Young Sik

    2008-07-15

    This report contains the measurements and evaluation of production cross sections of some medically and technologically important radionuclides over the energy range 1-40 MeV by using a conventional stacked-foil activation technique combined with high purity germanium (HPGe) -ray spectrometry. The irradiations were done by using the external beam line of the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). The standard cross sections for monitor reactions were taken from IAEA web site. Integral yields for the investigated radionuclides were deduced using the measured cross-sections. Reported data were compared with the available literature data, theoretical calculations by the codes TALYS and ALICE-IPPE, and a good overall agreement among them was found.

  13. Measurements and Evaluation of Nuclear Reaction Cross Sections Leading to Various Practical Applications in Science and Technology

    International Nuclear Information System (INIS)

    Khandaker, Mayeen Uddin; Lee, Young Ouk; Cho, Young Sik

    2008-07-01

    This report contains the measurements and evaluation of production cross sections of some medically and technologically important radionuclides over the energy range 1-40 MeV by using a conventional stacked-foil activation technique combined with high purity germanium (HPGe) -ray spectrometry. The irradiations were done by using the external beam line of the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). The standard cross sections for monitor reactions were taken from IAEA web site. Integral yields for the investigated radionuclides were deduced using the measured cross-sections. Reported data were compared with the available literature data, theoretical calculations by the codes TALYS and ALICE-IPPE, and a good overall agreement among them was found

  14. Disruption of the Cx43/miR21 pathway leads to osteocyte apoptosis and increased osteoclastogenesis with aging.

    Science.gov (United States)

    Davis, Hannah M; Pacheco-Costa, Rafael; Atkinson, Emily G; Brun, Lucas R; Gortazar, Arancha R; Harris, Julia; Hiasa, Masahiro; Bolarinwa, Surajudeen A; Yoneda, Toshiyuki; Ivan, Mircea; Bruzzaniti, Angela; Bellido, Teresita; Plotkin, Lilian I

    2017-06-01

    Skeletal aging results in apoptosis of osteocytes, cells embedded in bone that control the generation/function of bone forming and resorbing cells. Aging also decreases connexin43 (Cx43) expression in bone; and osteocytic Cx43 deletion partially mimics the skeletal phenotype of old mice. Particularly, aging and Cx43 deletion increase osteocyte apoptosis, and osteoclast number and bone resorption on endocortical bone surfaces. We examined herein the molecular signaling events responsible for osteocyte apoptosis and osteoclast recruitment triggered by aging and Cx43 deficiency. Cx43-silenced MLO-Y4 osteocytic (Cx43 def ) cells undergo spontaneous cell death in culture through caspase-3 activation and exhibit increased levels of apoptosis-related genes, and only transfection of Cx43 constructs able to form gap junction channels reverses Cx43 def cell death. Cx43 def cells and bones from old mice exhibit reduced levels of the pro-survival microRNA miR21 and, consistently, increased levels of the miR21 target phosphatase and tensin homolog (PTEN) and reduced phosphorylated Akt, whereas PTEN inhibition reduces Cx43 def cell apoptosis. miR21 reduction is sufficient to induce apoptosis of Cx43-expressing cells and miR21 deletion in miR21 fl/fl bones increases apoptosis-related gene expression, whereas a miR21 mimic prevents Cx43 def cell apoptosis, demonstrating that miR21 lies downstream of Cx43. Cx43 def cells release more osteoclastogenic cytokines [receptor activator of NFκB ligand (RANKL)/high-mobility group box-1 (HMGB1)], and caspase-3 inhibition prevents RANKL/HMGB1 release and the increased osteoclastogenesis induced by conditioned media from Cx43 def cells, which is blocked by antagonizing HMGB1-RAGE interaction. These findings identify a novel Cx43/miR21/HMGB1/RANKL pathway involved in preventing osteocyte apoptosis that also controls osteoclast formation/recruitment and is impaired with aging. © 2017 The Authors. Aging Cell published by the Anatomical Society

  15. Murine gammaherpesvirus M2 protein induction of IRF4 via the NFAT pathway leads to IL-10 expression in B cells.

    Directory of Open Access Journals (Sweden)

    Udaya S Rangaswamy

    2014-01-01

    Full Text Available Reactivation of the gammaherpesviruses Epstein-Barr virus (EBV, Kaposi's sarcoma-associated herpesvirus (KSHV and murine gammaherpesvirus 68 (MHV68 from latently infected B cells has been linked to plasma cell differentiation. We have previously shown that the MHV68 M2 protein is important for virus reactivation from B cells and, when expressed alone in primary murine B cells, can drive B cell differentiation towards a pre-plasma cell phenotype. In addition, expression of M2 in primary murine B cells leads to secretion of high levels of IL-10 along with enhanced proliferation and survival. Furthermore, the absence of M2 in vivo leads to a defect in the appearance of MHV68 infected plasma cells in the spleen at the peak of MHV68 latency. Here, employing an inducible B cell expression system, we have determined that M2 activates the NFAT pathway in a Src kinase-dependent manner--leading to induction of the plasma cell-associated transcription factor, Interferon Regulatory Factor-4 (IRF4. Furthermore, we show that expression of IRF4 alone in a B cell line up-regulates IL-10 expression in culture supernatants, revealing a novel role for IRF4 in B cell induced IL-10. Consistent with the latter observation, we show that IRF4 can regulate the IL-10 promoter in B cells. In primary murine B cells, addition of cyclosporine (CsA resulted in a significant decrease in M2-induced IL-10 levels as well as IRF4 expression, emphasizing the importance of the NFAT pathway in M2- -mediated induction of IL-10. Together, these studies argue in favor of a model wherein M2 activation of the NFAT pathway initiates events leading to increased levels of IRF4--a key player in plasma cell differentiation--which in turn triggers IL-10 expression. In the context of previous findings, the data presented here provides insights into how M2 facilitates plasma cell differentiation and subsequent virus reactivation.

  16. Theoretical investigation of the oxidation pathways of the Cl-initiated reaction of 2-methyl-3-buten-2-ol

    Science.gov (United States)

    Zhang, Weichao; Zhang, Dongju

    2012-12-01

    The mechanism and products of the reaction of 2-methyl-3-buten-2-ol (MBO232) with Cl atoms in the presence of O2 have been elucidated by performing high-level quantum chemistry calculations. The geometries of the reactants, intermediates, transition states, and products are optimized at the MP2(full)/6-311G(d, p) level, and their single-point energies are refined at the CCSD(T)/6-311 + G(d, p) level. The potential energy surface profiles have been constructed at the CCSD(T)/6-311 + G(d, p)//MP2(full)/6-311G(d, p) + 0.95 × ZPE level of theory, and the possible channels involved in the reaction are also discussed. The calculations indicate that the reaction predominantly proceeds via the addition of Cl atoms to the double bond rather than the direct abstraction of the H atoms in MBO232. The nascent adducts (CH3)2C(OH)CHCH2Cl (IM1) and (CH3)2C(OH)CHClCH2 (IM2) do not undergo subsequent isomerization and dissociation reactions, but rather react with O2. The theoretical results show that the major products are CH2ClCHO and CH3C(O)CH3 for the reaction of MBO232 + Cl in the presence of O2, which is in good agreement with the experimental finding.

  17. Development of the adverse outcome pathway "alkylation of DNA in male premeiotic germ cells leading to heritable mutations" using the OECD's users' handbook supplement.

    Science.gov (United States)

    Yauk, Carole L; Lambert, Iain B; Meek, M E Bette; Douglas, George R; Marchetti, Francesco

    2015-12-01

    The Organisation for Economic Cooperation and Development's (OECD) Adverse Outcome Pathway (AOP) programme aims to develop a knowledgebase of all known pathways of toxicity that lead to adverse effects in humans and ecosystems. A Users' Handbook was recently released to provide supplementary guidance on AOP development. This article describes one AOP-alkylation of DNA in male premeiotic germ cells leading to heritable mutations. This outcome is an important regulatory endpoint. The AOP describes the biological plausibility and empirical evidence supporting that compounds capable of alkylating DNA cause germ cell mutations and subsequent mutations in the offspring of exposed males. Alkyl adducts are subject to DNA repair; however, at high doses the repair machinery becomes saturated. Lack of repair leads to replication of alkylated DNA and ensuing mutations in male premeiotic germ cells. Mutations that do not impair spermatogenesis persist and eventually are present in mature sperm. Thus, the mutations are transmitted to the offspring. Although there are some gaps in empirical support and evidence for essentiality of the key events for certain aspects of this AOP, the overall AOP is generally accepted as dogma and applies broadly to any species that produces sperm. The AOP was developed and used in an iterative process to test and refine the Users' Handbook, and is one of the first publicly available AOPs. It is our hope that this AOP will be leveraged to develop other AOPs in this field to advance method development, computational models to predict germ cell effects, and integrated testing strategies. © 2015 Her Majesty the Queen in Right of Canada.

  18. Theoretical estimates of supernova-neutrino cross sections for the stable even-even lead isotopes: Charged-current reactions

    Science.gov (United States)

    Almosly, W.; Carlsson, B. G.; Suhonen, J.; Toivanen, J.; Ydrefors, E.

    2016-10-01

    A detailed study of the charged-current supernova electron neutrino and electron antineutrino scattering off the stable even-mass lead isotopes A =204 , 206, and 208 is reported in this work. The proton-neutron quasiparticle random-phase approximation (pnQRPA) is adopted to construct the nuclear final and initial states. Three different Skyrme interactions are tested for their isospin and spin-isospin properties and then applied to produce (anti)neutrino-nucleus scattering cross sections for (anti)neutrino energies below 80 MeV. Realistic estimates of the nuclear responses to supernova (anti)neutrinos are computed by folding the computed cross sections with a two-parameter Fermi-Dirac distribution of the electron (anti)neutrino energies. The computed cross sections are compared with earlier calculations and the analyses are extended to take into account the effects coming from the neutrino oscillations.

  19. Pathways for the OH + Br2 → HOBr + Br and HOBr + Br → HBr + BrO Reactions.

    Science.gov (United States)

    Wang, Hongyan; Qiu, Yudong; Schaefer, Henry F

    2016-02-11

    The OH radical reaction with Br2 and the subsequent reaction HOBr + Br are of exceptional importance to atmospheric chemistry and environmental chemistry. The entrance complex, transition state, and exit complex for both reactions have been determined using the coupled-cluster method with single, double, and perturbative triple excitations CCSD(T) with correlation consistent basis sets up to size cc-pV5Z and cc-pV5Z-PP. Coupled cluster effects with full triples (CCSDT) and full quadruples (CCSDTQ) are explicitly investigated. Scalar relativistic effects, spin-orbit coupling, and zero-point vibrational energy corrections are evaluated. The results from the all-electron basis sets are compared with those from the effective core potential (ECP) pseudopotential (PP) basis sets. The results are consistent. The OH + Br2 reaction is predicted to be exothermic 4.1 ± 0.5 kcal/mol, compared to experiment, 3.9 ± 0.2 kcal/mol. The entrance complex HO···BrBr is bound by 2.2 ± 0.2 kcal/mol. The transition state lies similarly well below the reactants OH + Br2. The exit complex HOBr···Br is bound by 2.7 ± 0.6 kcal/mol relative to separated HOBr + Br. The endothermicity of the reaction HOBr + Br → HBr + BrO is 9.6 ± 0.7 kcal/mol, compared with experiment 8.7 ± 0.3 kcal/mol. For the more important reverse (exothermic) HBr + BrO reaction, the entrance complex BrO···HBr is bound by 1.8 ± 0.6 kcal/mol. The barrier for the HBr + BrO reaction is 6.8 ± 0.9 kcal/mol. The exit complex (Br···HOBr) for the HBr + BrO reaction is bound by 1.9 ± 0.2 kcal/mol with respect to the products HOBr + Br.

  20. An Intramolecular Heck reaction that Prefers a 5-endo- to a 6-exo-trig Cyclization Pathway

    DEFF Research Database (Denmark)

    Vital, Paulo; Norrby, Per-Ola; Tanner, David Ackland

    2006-01-01

    A regioselective aromatic Claisen rearrangement was used to prepare 17a, the precursor of triflate 17e. The intramolecular Heck reaction of 17e is promoted only by bidentate phosphine ligands, giving exclusively and in excellent yield 20, the product of a 5-endo-trig cyclization, despite the poss......A regioselective aromatic Claisen rearrangement was used to prepare 17a, the precursor of triflate 17e. The intramolecular Heck reaction of 17e is promoted only by bidentate phosphine ligands, giving exclusively and in excellent yield 20, the product of a 5-endo-trig cyclization, despite...

  1. Reactions of ferrate(VI) with iodide and hypoiodous acid: kinetics, pathways, and implications for the fate of iodine during water treatment.

    Science.gov (United States)

    Shin, Jaedon; von Gunten, Urs; Reckhow, David A; Allard, Sebastien; Lee, Yunho

    2018-06-01

    Oxidative treatment of iodide-containing waters can form iodinated disinfection by-products (I-DBPs) that are more toxic than the regulated DBPs. To better understand the fate of iodine during water treatment with ferrate(VI), kinetics, products, and stoichiometries for the reactions of ferrate(VI) with iodide (I - ) and hypoiodous acid (HOI) were determined. Ferrate(VI) showed considerable reactivities to both I - and HOI with higher reactivities at lower pH. Interestingly, the reaction of ferrate(VI) with HOI ( k = 6.0×10 3 M -1 s -1 at pH 9) was much faster than with I - ( k = 5.6×10 M -1 s -1 at pH 9). The main reaction pathway during treatment of I - -containing waters was the oxidation of I - to HOI and its further oxidation to IO 3 - by ferrate(VI). However, for pH > 9, the HOI disproportionation catalyzed by ferrate(VI) became an additional transformation pathway forming I - and IO 3 - . The reduction of HOI by hydrogen peroxide ( k = 2.0×10 8 M -1 s -1 for the reaction, HOI + HO 2 - → I - + O 2 + 2H + ), the latter being produced from ferrate(VI) decomposition, also contributes to the I - regeneration in the pH range 9 - 11. A kinetic model was developed that could well simulate the fate of iodine in the ferrate(VI)-I - system. Overall, due to a rapid oxidation of I - to IO 3 - with short-lifetimes of HOI, ferrate(VI) oxidation appears to be a promising option for I-DBP mitigation during treatment of I - -containing waters.

  2. Protective Effects of Maillard Reaction Products of Whey Protein Concentrate against Oxidative Stress through an Nrf2-Dependent Pathway in HepG2 Cells.

    Science.gov (United States)

    Pyo, Min Cheol; Yang, Sung-Yong; Chun, Su-Hyun; Oh, Nam Su; Lee, Kwang-Won

    2016-09-01

    Whey protein concentrate (WPC), which contains α-lactalbumin and β-lactoglobulin, is utilized widely in the food industry. The Maillard reaction is a complex reaction that produces Maillard reaction products (MRPs), which are associated with the formation of antioxidant compounds. In this study, the hepatoprotection activity of MRPs of WPC against oxidative stress through the nuclear factor-E2-related factor 2 (Nrf2)-dependent antioxidant pathway in HepG2 cells was examined. Glucose-whey protein concentrate conjugate (Glc-WPC) was obtained from Maillard reaction between WPC and glucose. The fluorescence intensity of Glc-WPC increased after 7 d compared to native WPC, and resulted in loss of 48% of the free amino groups of WPC. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of Glc-WPC showed the presence of a high-molecular-weight portion. Treatment of HepG2 cells with Glc-WPC increased cell viability in the presence of oxidative stress, inhibited the generation of intracellular reactive oxygen species by tert-butyl hydroperoxide (t-BHP), and increased the glutathione level. Nrf2 translocation and Nrf2, reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H)-quinone oxidoreductase 1 (NOQ1), heme oxygenase-1 (HO-1), glutamate-L-cysteine ligase (GCL)M and GCLC mRNA levels were increased by Glc-WPC. Also, Glc-WPC increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK). The results of this study demonstrate that Glc-WPC activates the Nrf2-dependent pathway through the phosphorylation of ERK1/2 and JNK in HepG2 cells, and induces production of antioxidant enzymes and phase II enzymes.

  3. Use of ESI-MS to determine reaction pathway for hydrogen sulphide scavenging with 1,3,5-tri-(2-hydroxyethyl)-hexahydro-s-triazine.

    Science.gov (United States)

    Madsen, Henrik T; Søgaard, Erik G

    2012-01-01

    To study the reaction between hydrogen sulphide and 1,3,5-tri-(2-hydroxyethyl)-hexahydro-s-triazine, which is an often used hydrogen sulphide scavenger, electro spray ionisation mass spectrometry (ESI-MS) was used. The investigation was carried out in positive mode, and tandem mass spectrometry was used to investigate the nature of unknown peaks in the mass spectra. The reaction was found to proceed as expected from theory with the triazine reacting with hydrogen sulphide to form the corresponding thiadiazine. This species subsequently reacted with a second hydrogen sulphide molecule to form the dithiazine species, hereby confirming previously obtained results and showing the ability of the ESI-MS method for studying the scavenging reaction. The final theoretical product s-trithiane was not detected. Furthermore, fragmentation products of thiadiazine and dithiazine were detected in the solution, and possible pathways and structures were suggested to describe the observed fragments. In these, thiadiazine fragmented to 2-(methylidene amino)-ethanol and 2-(1,3-thiazetidin-3-yl)-ethanol and N-(2-hydroxyethyl)-N-(sulfanylmethyl)-ethaniminium, which underwent a further fragmentation to N-methyl-N-(2-oxoethyl)-methaniminium. Dithiazine fragmented to N-methyl-N-(2-oxoethyl)-methaniminium as well. The by-product from this reaction is methanedithiol, which was not detected due to its low polarity.

  4. Boson states in the reaction π-p → π-π-π+p with leading π+ meson at 25 GeV/c

    International Nuclear Information System (INIS)

    Antipov, Yu.M.; Baud, R.

    1975-01-01

    The reaction π - + p → p + π - + π - + π + at 25 GeV/c was studied in the mass region M sub(3π) >>= 1.8 GeV with leading π + in the final state. The mass spectrum of π 1 π - -system evidently shows peaks rho deg, f, g deg resonances and an enhancement in S'-region. It is shown that the g deg and π - mesons are mainly in A4 state J sub(P) = 3 + S-wave g degπ - like A1(sup(rhoπ)) and A3(sup(fπ))

  5. A new pathway for transmembrane electron transfer in photosynthetic reaction centers of Rhodobacter sphaeroides not involving the excited special pair.

    NARCIS (Netherlands)

    van Brederode, M.E.; Jones, M.R.; van Mourik, F.; van Stokkum, I.H.M.; van Grondelle, R.

    1997-01-01

    It is generally accepted that electron transfer in bacterial photosynthesis is driven by the first singlet excited state of a special pair of bacteriochlorophylls (P*). We have examined the first steps of electron transfer in a mutant of the Rhodobacter sphaeroides reaction center in which charge

  6. A new pathway for transmembrane electron transfer in photosyntetic reaction centers of Rhodobacter sphaeroides not involving the excited special pair.

    NARCIS (Netherlands)

    van Brederode, M.E.; Jones, M.R.; van Mourik, F.; van Stokkum, I.H.M.; van Grondelle, R.

    1997-01-01

    It is generally accepted that electron transfer in bacterial photosynthesis is driven by the first singlet excited state of a special pair of bacteriochlorophylls (P*). We have examined the first steps of electron transfer in a mutant of the Rhodobacter sphaeroides reaction center in which charge

  7. WAFs lead molting retardation of naupliar stages with down-regulated expression profiles of chitin metabolic pathway and related genes in the copepod Tigriopus japonicus.

    Science.gov (United States)

    Hwang, Dae-Sik; Lee, Min-Chul; Kyung, Do-Hyun; Kim, Hui-Su; Han, Jeonghoon; Kim, Il-Chan; Puthumana, Jayesh; Lee, Jae-Seong

    2017-03-01

    Oil pollution is considered being disastrous to marine organisms and ecosystems. As molting is critical in the developmental process of arthropods in general and copepods, in particular, the impact will be adverse if the target of spilled oil is on molting. Thus, we investigated the harmful effects of water accommodated fractions (WAFs) of crude oil with an emphasis on inhibition of chitin metabolic pathways related genes and developmental retardation in the copepod Tigriopus japonicus. Also, we analysed the ontology and domain of chitin metabolic pathway genes and mRNA expression patterns of developmental stage-specific genes. Further, the developmental retardation followed by transcriptional modulations in nuclear receptor genes (NR) and chitin metabolic pathway-related genes were observed in the WAFs-exposed T. japonicus. As a result, the developmental time was found significantly (P<0.05) delayed in response to 40% WAFs in comparison with that of control. Moreover, the NR gene, HR3 and chitinases (CHT9 and CHT10) were up-regulated in N4-5 stages, while chitin synthase genes (CHS-1, CHS-2-1, and CHS-2-2) down-regulated in response to WAFs. In brief, a high concentration of WAFs repressed nuclear receptor genes but elicited activation of some of the transcription factors at low concentration of WAFs, resulting in suppression of chitin synthesis. Thus, we suggest that WAF can lead molting retardation of naupliar stages in T. japonicus through down-regulations of chitin metabolism. These findings will provide a better understanding of the mode of action of chitin biosynthesis associated with molting mechanism in WAF-exposed T. japonicus. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. A B Cell-Driven Autoimmune Pathway Leading to Pathological Hallmarks of Progressive Multiple Sclerosis in the Marmoset Experimental Autoimmune Encephalomyelitis Model

    Directory of Open Access Journals (Sweden)

    Bert A. ’t Hart

    2017-07-01

    Full Text Available The absence of pathological hallmarks of progressive multiple sclerosis (MS in commonly used rodent models of experimental autoimmune encephalomyelitis (EAE hinders the development of adequate treatments for progressive disease. Work reviewed here shows that such hallmarks are present in the EAE model in marmoset monkeys (Callithrix jacchus. The minimal requirement for induction of progressive MS pathology is immunization with a synthetic peptide representing residues 34–56 from human myelin oligodendrocyte glycoprotein (MOG formulated with a mineral oil [incomplete Freund’s adjuvant (IFA]. Pathological aspects include demyelination of cortical gray matter with microglia activation, oxidative stress, and redistribution of iron. When the peptide is formulated in complete Freund’s adjuvant, which contains mycobacteria that relay strong activation signals to myeloid cells, oxidative damage pathways are strongly boosted leading to more intensive pathology. The proven absence of immune potentiating danger signals in the MOG34–56/IFA formulation implies that a narrow population of antigen-experienced T cells present in the monkey’s immune repertoire is activated. This novel pathway involves the interplay of lymphocryptovirus-infected B cells with MHC class Ib/Caja-E restricted CD8+ CD56+ cytotoxic T lymphocytes.

  9. How could differences in 'control over destiny' lead to socio-economic inequalities in health? A synthesis of theories and pathways in the living environment.

    Science.gov (United States)

    Whitehead, Margaret; Pennington, Andy; Orton, Lois; Nayak, Shilpa; Petticrew, Mark; Sowden, Amanda; White, Martin

    2016-05-01

    We conducted the first synthesis of theories on causal associations and pathways connecting degree of control in the living environment to socio-economic inequalities in health-related outcomes. We identified the main theories about how differences in 'control over destiny' could lead to socio-economic inequalities in health, and conceptualised these at three distinct explanatory levels: micro/personal; meso/community; and macro/societal. These levels are interrelated but have rarely been considered together in the disparate literatures in which they are located. This synthesis of theories provides new conceptual frameworks to contribute to the design and conduct of theory-led evaluations of actions to tackle inequalities in health. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. Protein kinase A (PKA) phosphorylation of Na+/K+-ATPase opens intracellular C-terminal water pathway leading to third Na+-binding site in molecular dynamics simulations

    DEFF Research Database (Denmark)

    Poulsen, Hanne; Nissen, Poul; Mouritsen, Ole G.

    2012-01-01

    -atom Molecular Dynamics (MD) simulations to investigate the structural consequences of phosphorylating the Na+/K+- ATPase (NKA) residue S936, which is the best characterized phosphorylation site in NKA, targeted in vivo by Protein Kinase A (PKA) (1-3). The MD simulations suggest that S936 phosphorylation opens......Phosphorylation is one of the major mechanisms for posttranscriptional modification of proteins. The addition of a compact, negatively charged moiety to a protein can significantly change its function and localization by affecting its structure and interaction network. We have used all...... a C-terminal hydrated pathway leading to D926, a transmembrane residue proposed to form part of the third sodium ion-binding site (4). Simulations of a S936E mutant form, for which only subtle effects are observed when expressed in Xenopus oocytes and studied with electrophysiology, does not mimic...

  11. Evaluation of a setting reaction pathway in the novel composite TiHA-CSD bone cement by FT-Raman and FT-IR spectroscopy

    Science.gov (United States)

    Paluszkiewicz, Czesława; Czechowska, Joanna; Ślósarczyk, Anna; Paszkiewicz, Zofia

    2013-02-01

    The aim of this study was to determine a setting reaction pathway in a novel, surgically handy implant material, based on calcium sulfate hemihydrate (CSH) and titanium doped hydroxyapatite (TiHA). The previous studies confirmed superior biological properties of TiHA in comparison to the undoped hydroxyapatite (HA) what makes it highly attractive for future medical applications. In this study the three types of titanium modified HA powders: untreated, calcined at 800 °C, sintered at 1250 °C and CSH were used to produce bone cements. The Fourier Transform-InfraRed (FT-IR) spectroscopy and Raman spectroscopy were applied to evaluate processes taking place during the setting of the studied materials. Our results undoubtedly confirmed that the reaction pathways and the phase compositions differed significantly for set cements and were dependent on the initial heat treatment of TiHA powder. Final materials were multiphase composites consisting of calcium sulfate dihydrate, bassanite, tricalcium phosphate, hydroxyapatite and calcium titanate (perovskite). The FT-IR and Scanning Electron Microscopy (SEM) measurements performed after the incubation of the cement samples in the simulated body fluid (SBF), indicate on high bioactive potential of the obtained bone cements.

  12. Theoretical study of the oxidation mechanisms of naphthalene initiated by hydroxyl radicals: the O2 addition reaction pathways.

    Science.gov (United States)

    Shiroudi, A; Deleuze, M S; Canneaux, S

    2015-05-28

    Atmospheric oxidation of the naphthalene-OH adduct [C10H8OH]˙ (R1) by molecular oxygen in its triplet electronic ground state has been studied using density functional theory along with the B3LYP, ωB97XD, UM05-2x and UM06-2x exchange-correlation functionals. From a thermodynamic viewpoint, the most favourable process is O2 addition at the C2 position in syn mode, followed by O2 addition at the C2 position in anti mode, O2 addition at the C4 position in syn mode, and O2 addition at the C4 position in anti mode, as the second, third and fourth most favourable processes. The syn modes of addition at these positions are thermodynamically favoured over the anti ones by the formation of an intramolecular hydrogen bond between the hydroxyl and peroxy substituents. Analysis of the computed structures, bond orders and free energy profiles demonstrate that the reaction steps involved in the oxidation of the naphthalene-OH adduct by O2 satisfy Hammond's principle. Kinetic rate constants and branching ratios under atmospheric pressure and in the fall-off regime have been supplied, using transition state and RRKM theories. By comparison with experiment, these data confirm the relevance of a two-step reaction mechanism. Whatever the addition mode, O2 addition in C4 position is kinetically favoured over O2 addition in C2 position, in contrast with the expectations drawn from thermodynamics and reaction energies. Under a kinetic control of the reaction, and in line with the computed reaction energy barriers, the most efficient process is O2 addition at the C4 position in syn mode, followed by O2 addition at the C2 position in syn mode, O2 addition at the C4 position in anti mode, and O2 addition at the C2 position in anti mode as the second, third and fourth most rapid processes. The computed branching ratios also indicate that the regioselectivity of the reaction decreases with increasing temperatures and decreasing pressures.

  13. Pathways for the reaction of the butadiene radical cation, [C{sub 4}H{sub 6}]{sup {sm{underscore}bullet}+}, with ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, M.; Schaefer, H.F. III

    1999-11-04

    The Diels-Alder (DA) reaction, a [4+2] cycloaddition used to build six membered rings, is one of the most valuable cycloadditions in organic chemistry. In cases where the ene does not add to the diene (even with the help of Lewis acids which may reduce the electron density of one reactant by complexation) one electron oxidation (by an oxidizing agent or by photoinduced electron transfer (PET)) may accelerate the reaction. Reaction pathways for the addition of ethylene, 1, to butadiene radical cation, 2, involving H-shifts have been investigated at the coupled cluster UCCSD(T)/DZP//UMP2(fc)/DZP + ZPE level of theory. Activation energies are relatively low for [1,2]- (10.0 kcal mol{sup {minus}1}, TS-4/20) and [1,5]-hydrogen shifts (7.7 kcal mol{sup {minus}1}, TS-4/26) but are relatively high for [1,4]-(33.8 kcal mol{sup {minus}1}, TS-4/14) and [1,3]-H shifts (e.g., 42.2 kcal mol{sup {minus}1}, TS-12/13; 57.2 kcal mol{sup {minus}1}, TS-16/21). Several rearrangement reactions have been found to occur below the energy limit of separated 1 + 2. The cyclopentenyl cation, [C{sub 5}{sub 7}]{sup +}, 18, experimentally observed as reaction product of the butadiene radical cation, 2, and ethylene, 1, in the gas phase may origin from various reaction pathways. The following reaction sequence has been identified as the lowest in energy path from 1 + 2 to 18 with all relative energies ({Delta}E{degree}) of transition structures below that of 1 + 2: (a) ethylene adds to the butadiene radical cation to form an open-chain distonic intermediate, that undergoes a [1,5]-H shift to the 1,4-hexadiene radical cation; (b) intramolecular [2+1] cycloaddition to methyl-cyclopenta-1,3-diyl intermediates, which can interconvert through a bicyclo[2.1.0]pentane radical cation; (c) [1,2]-H shift to the 3-methyl cyclopentene radical cation; (d) methyl radical loss to give cyclopenten-3-yl cation. Along this reaction pathway, {Delta}H{sup 298} is below that of 1 + 2; max. ({Delta}G{sup 298} by

  14. Kinetic modelling of Amadori N-(1-deoxy-D-fructos-1-yl)-glycine degradation pathways. Part I - Reaction mechanism

    NARCIS (Netherlands)

    Martins, S.I.F.S.; Marcelis, A.T.M.; Boekel, van M.A.J.S.

    2003-01-01

    The fate of the Amadori compound N-(1-deoxy--fructos-1-yl)-glycine (DFG) was studied in aqueous model systems as a function of pH and temperature. The samples were heated at 100 and 120 °C with initial reaction pH of 5.5 and 6.8. Special attention was paid to the formation of the free amino acid,

  15. [Effects and mechanisms of the inflammatory reaction related to NASH and induced by activation of the cholinergic anti-inflammatory pathway].

    Science.gov (United States)

    Zhou, Zhou; Chen, Xiaomei; Li, Fuqiang; Tang, Cuilan

    2015-01-01

    To investigate the effects and mechanisms of the inflammatory reaction related to nonalcoholic steatohepatitis (NASH) and induced by activation of the cholinergic anti-inflammatory pathway. A mouse model of NASH was established by feeding a high-fat and high-sugar diet.Activation of the cholinergic anti-inflammatory pathway was achieved by nicotine administration to the NASH modeled mice and normal controls. Liver biopsies were taken and the concentrations of cytokines were measured. Isolated liver primary Kupffer cells and RAw264.7 cells were cultured, pre-treated or not with lipopolysaccharide (LPS) and exposed to nicotine, after which the supernatant concentrations of IL-6 and TNFa were determined by ELISA. The protein expression levels of phosphorylated (p)-NF-kB and I k B were detected in primary cultured Kupffer cells by western blotting. The mouse model of NASH was successfully established, as evidenced by findings from liver biopsy and serum liver function tests. The degree of liver inflammation in the NASH mice decreased after nicotine administration, and the level of serum TNFa also significantly decreased. The levels of serum TNFa were 21.95+/-0.8 pg/mL in nicotine-treated mice and 38.07+/-1.7 pg/mL in the non-nicotine-treated NASH mice (P less than 0.05). The nicotine treatment also significantly reduced the concentration of TNFa in the culture supernatants of Kupffer cells after LPS stimulation; moreover, the supernatant level of TNFa decreased significantly after the nicotine treatment (Pless than 0.05). LPS stimulation of the RAw264.7 cells led to an increased level ofp-NF-kB and a reduced level ofI-kB, suggesting that the NF-kB pathway had been activated; different doses of nicotine pre-treatment led to down-regulation of the p-NF-kB level and up-regulation of the I-kB level, both in dose-dependent manners. Activating the cholinergic anti-inflammatory pathway inhibits the NASH-related inflammatory reaction, and the mechanism for this inhibition

  16. Dissociation pathways of a single dimethyl disulfide on Cu(111): Reaction induced by simultaneous excitation of two vibrational modes

    Energy Technology Data Exchange (ETDEWEB)

    Motobayashi, Kenta, E-mail: kmotobayashi@cat.hokudai.ac.jp [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan); Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Kim, Yousoo [Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Arafune, Ryuichi [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044 (Japan); Ohara, Michiaki; Ueba, Hiromu; Kawai, Maki, E-mail: maki@k.u-tokyo.ac.jp [Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan)

    2014-05-21

    We present a novel reaction mechanism for a single adsorbed molecule that proceeds via simultaneous excitation of two different vibrational modes excited by inelastic tunneling electrons from a scanning tunneling microscope. Specifically, we analyze the dissociation of a single dimethyl disulfide (DMDS, (CH{sub 3}S){sub 2}) molecule on Cu(111) by using a versatile theoretical method, which permits us to simulate reaction rates as a function of sample bias voltage. The reaction is induced by the excitation of C-H stretch and S-S stretch modes by a two-electron process at low positive bias voltages. However, at increased voltages, the dissociation becomes a single-electron process that excites a combination mode of these stretches, where excitation of the C-H stretch is the energy source and excitation of the S-S stretch mode enhances the anharmonic coupling rate. A much smaller dissociation yield (few orders of magnitude) at negative bias voltages is understood in terms of the projected density of states of a single DMDS on Cu(111), which reflects resonant excitation through the molecular orbitals.

  17. Metabolic pathways leading to hyperhomocysteinemia

    Czech Academy of Sciences Publication Activity Database

    Šenholdová, Z.; Navrátil, Tomáš; Přistoupilová, K.; Přistoupil, T. I.; Heyrovský, Michael; Kohlíková, E.; Petr, M.

    2005-01-01

    Roč. 9, 3-4 (2005), s. 93-96 ISSN 1335-2253 R&D Projects: GA MPO 1H-PK/42; GA MZd NR8107 Grant - others:Univerzita Karlova(CZ) 534 Institutional research plan: CEZ:AV0Z40400503 Keywords : urine * voltammetry * thiodiglycolic acid * TDGA Subject RIV: CF - Physical ; Theoretical Chemistry

  18. [Polyketone Reaction in Biosynthetic Pathways of 2, 3, 5, 4'-Tetrahydroxy Stilhene-2-O-β-D-glucoside in Polygonum multiflorum by Biocatalysis].

    Science.gov (United States)

    Lei, Lei; Xia, Wan-xia; Shao, Li; Zhao, Shu-jin

    2015-10-01

    2, 3, 5, 4'-Tetrahydroxy stilbene-2-O-β-D-glucoside (THSG), the active ingredient of Polygonum multiflorum, its polyketone reaction in the biosynthesis pathways was studied by biocatalysis method. The substrates 4-coumaroyl-CoA and malonyl-CoA were catalyzed in vitro by the crude enzyme extracted from Polygonum multiflorum callus, then the products were verified by HPLC and LC-MS methods. And the crude enzyme was analyzed by ammonium sulfate precipitation method and SDS-PAGE. HPLC chromatogram showed the same retention time of both the product and resveratrol standards; LC-MS spectra showed that the m/z of product was 227, which was consistent with resveratrol standards under the mode of negative ion; Ammonium sulfate (AS) precipitation method showed AS of 40% - 70% had catalytic activity,and 50% - 60% was the optimum; SDS-PAGE showed protein bands were obviously different among different AS concentration between 20% - 80%, the protein band of 42 kDa was found in AS of 50% - 60%, which had the same molecular weight with stilbene synthase. The product of polyketone reaction in the biosynthesis of THSG is resveratrol rather than THSG, so it is speculated that THSG is the conversion product of resveratrol instead of the direct product of the polyketone reaction.

  19. Six-year longitudinal study of pathways leading to explosive anger involving the traumas of recurrent conflict and the cumulative sense of injustice in Timor-Leste.

    Science.gov (United States)

    Silove, Derrick; Mohsin, Mohammed; Tay, Alvin Kuowei; Steel, Zachary; Tam, Natalino; Savio, Elisa; Da Costa, Zelia Maria; Rees, Susan

    2017-10-01

    Cumulative evidence suggests that explosive anger may be a common reaction among survivors of mass conflict. However, little is known about the course of explosive anger in the years following mass conflict, or the psychosocial factors that influence the trajectory of that reaction pattern. We examined these issues in a 6-year longitudinal study (2004-2010) conducted among adult residents of a rural and an urban village in Timor-Leste (n = 1022). We derived a brief, context-specific index of explosive anger using qualitative methods. Widely used measures of post-traumatic stress disorder (PTSD) and severe psychological distress were calibrated to the Timor context. We developed an index of the cumulative sense of injustice related to consecutive historical periods associated with conflict in Timor-Leste. We applied partial structural equation modeling (SEM) to examine pathways from baseline explosive anger, socio-demographic factors, recurrent trauma, mental health indices (PTSD, severe psychological distress) and the sense of injustice, to explosive anger. Half of the sample with explosive anger at baseline continued to report that reaction pattern after 6 years; and a third of those who did not report explosive anger at baseline developed the response by follow-up. A symmetrical pattern of younger age, female gender and the trauma count for the preceding historical period predicted explosive anger at each assessment point. The sense of injustice was related to explosive anger at follow-up. Explosive anger was associated with impairment in functioning and conflict with the intimate partner and wider family. Sampling constraints caution against generalizing our findings to other populations. Nevertheless, our data suggest that explosive anger may persist for a prolonged period of time following mass conflict and that the response pattern is initiated and maintained by recurrent trauma exposure associated with a sense of injustice. Averting recurrence of mass

  20. Structures and reaction pathways of the molybdenum centres of sulfite-oxidizing enzymes by pulsed EPR spectroscopy.

    Science.gov (United States)

    Enemark, John H; Astashkin, Andrei V; Raitsimring, Arnold M

    2008-12-01

    SOEs (sulfite-oxidizing enzymes) are physiologically vital and occur in all forms of life. During the catalytic cycle, the five-co-ordinate square pyramidal oxo-molybdenum active site passes through the Mo(V) state, and intimate details of the structure can be obtained from variable frequency pulsed EPR spectroscopy through the hyperfine and nuclear quadrupole interactions of nearby magnetic nuclei. By employing variable spectrometer operational frequencies, it is possible to optimize the measurement conditions for difficult quadrupolar nuclei of interest (e.g. (17)O, (33)S, (35)Cl and (37)Cl) and to simplify the interpretation of the spectra. Isotopically labelled model Mo(V) compounds provide further insight into the electronic and geometric structures and chemical reactions of the enzymes. Recently, blocked forms of SOEs having co-ordinated sulfate, the reaction product, were detected using (33)S (I=3/2) labelling. This blocking of product release is a possible contributor to fatal human sulfite oxidase deficiency in young children.

  1. Degradation of γ-HCH spiked soil using stabilized Pd/Fe0 bimetallic nanoparticles: Pathways, kinetics and effect of reaction conditions

    International Nuclear Information System (INIS)

    Singh, Ritu; Misra, Virendra; Mudiam, Mohana Krishna Reddy; Chauhan, Lalit Kumar Singh; Singh, Rana Pratap

    2012-01-01

    Highlights: ► This study explores the potential of CMC-Pd/nFe 0 to degrade γ-HCH in spiked soil. ► Sorption–desorption characteristics and partitioning of γ-HCH is investigated. ► Three degradation pathways has been proposed and discussed. ► γ-HCH degradation mechanism and kinetics is elucidated. ► Activation energy reveals that γ-HCH degradation is a surface mediated reaction. - Abstract: This study investigates the degradation pathway of gamma-hexachlorocyclohexane (γ-HCH) in spiked soil using carboxymethyl cellulose stabilized Pd/Fe 0 bimetallic nanoparticles (CMC-Pd/nFe 0 ). GC–MS analysis of γ-HCH degradation products showed the formation of pentachlorocyclohexene, tri- and di-chlorobenzene as intermediate products while benzene was formed as the most stable end product. On the basis of identified intermediates and final products, degradation pathway of γ-HCH has been proposed. Batch studies showed complete γ-HCH degradation at a loading of 0.20 g/L CMC-Pd/nFe 0 within 6 h of incubation. The surface area normalized rate constant (k SA ) was found to be 7.6 × 10 −2 L min −1 m −2 . CMC-Pd/nFe 0 displayed ∼7-fold greater efficiency for γ-HCH degradation in comparison to Fe 0 nanoparticles (nFe 0 ), synthesized without CMC and Pd. Further studies showed that increase in CMC-Pd/nFe 0 loading and reaction temperature facilitates γ-HCH degradation, whereas a declining trend in degradation was noticed with the increase in pH, initial γ-HCH concentration and in the presence of cations. The data on activation energy (33.7 kJ/mol) suggests that γ-HCH degradation is a surface mediated reaction. The significance of the study with respect to remediation of γ-HCH contaminated soil using CMC-Pd/nFe 0 has been discussed.

  2. Allowed energetic pathways for the three-body recombination reaction of nitrogen monoxide with the hydroxyl radical and their potential atmospheric implications

    Directory of Open Access Journals (Sweden)

    Luca D´Ottone

    2010-12-01

    Full Text Available The OH initiated oxidation of nitric oxide (NO is an important atmospheric reaction being, during the day time, the main channel that leads to the formation of HONO a reservoir species for both OH and odd nitrogen. This work reports ab initio study of the Potential Energy Surface (PES of NO + OH using density functional theory calculations conducted at the B3LYP level of theory with a 6-311g (d,p basis set. We confirmed experimental observations pointing out that the main channel for this reaction is the formation the HONO. From the addition of OH to NO both cis and trans isomers of HONO were found to be the formed as stable intermediate, both having a negative enthalpy of formation relative to the reactants, the cis isomer being more stable than the trans one. The ab initio calculations were extended to include the hydrogen extraction mechanism with its respective transition state to investigate the potential existence of a reaction channel leading to the formation of NO2 + H, that was found not to be of significant interest.

  3. Coprecipitation of {sup 14}C and Sr with carbonate precipitates: The importance of reaction kinetics and recrystallization pathways

    Energy Technology Data Exchange (ETDEWEB)

    Hodkin, David J. [School of Earth and Environment, University of Leeds, Leeds LS2 9JT (United Kingdom); Stewart, Douglas I. [School of Civil Engineering, University of Leeds (United Kingdom); Graham, James T. [National Nuclear Laboratory, Sellafield, Cumbria (United Kingdom); Burke, Ian T., E-mail: I.T.Burke@leeds.ac.uk [School of Earth and Environment, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2016-08-15

    This study investigated the simultaneous removal of Sr{sup 2+} and {sup 14}CO{sub 3}{sup 2−} from pH > 12 Ca(OH){sub 2} solution by the precipitation of calcium carbonate. Initial Ca{sup 2+}:CO{sub 3}{sup 2−} ratios ranged from 10:1 to 10:100 (mM:mM). Maximum removal of {sup 14}C and Sr{sup 2+} both occurred in the system containing 10 mM Ca{sup 2+} and 1 mM CO{sub 3}{sup 2−} (99.7% and 98.6% removal respectively). A kinetic model is provided that describes {sup 14}C and Sr removal in terms of mineral dissolution and precipitation reactions. The removal of {sup 14}C was achieved during the depletion of the initial TIC in solution, and was subsequently significantly affected by recrystallization of the calcite precipitate from an elongate to isotropic morphology. This liberated > 46% of the {sup 14}C back to solution. Sr{sup 2+} removal occurred as Ca{sup 2+} became depleted in solution and was not significantly affected by the recrystallization process. The proposed reaction could form the basis for low cost remediation scheme for {sup 90}Sr and {sup 14}C in radioactively contaminated waters (<$0.25 reagent cost per m{sup 3} treated). - Highlights: • 99.7% of {sup 14}C and 98.6% of Sr removed from aqueous solution by CaCO{sub 3} precipitation. • Remobilization of {sup 14}C observed during calcium carbonate recrystallization. • Sr displayed variable distribution coefficient (possibly affected by Ca:Sr ratio). • Reagent cost of $0.22/m{sup 3} of treated groundwater.

  4. Evaluation of the cross-sections of threshold reactions leading to the production of long-lived radionuclides during irradiation of steels by thermonuclear spectrum neutrons

    CERN Document Server

    Blokhin, A I; Manokhin, V N; Mikhajlyukova, M V; Nasyrova, S M; Skripova, M V

    2001-01-01

    The present paper analyses and evaluates the cross-sections of threshold reactions leading to the production of long-lived radionuclides during the irradiation, by thermonuclear spectrum neutrons, of steels containing V, Ti, Cr, Fe and Ni. On the basis of empirical systematics. a new evaluation of the (n,2n), (n,p), (n,np), (n,alpha) and (n,n alpha) excitation functions is made for all isotopes of V, Ti, Cr, Fe and Ni and for intermediate isotopes produced in the chain from irradiated isotopes up to production of the long-lived radionuclides sup 3 sup 9 Ar, sup 4 sup 2 Ar, sup 4 sup 1 Ca, sup 5 sup 3 Mn, sup 6 sup 0 Fe, sup 6 sup 0 Co, sup 5 sup 9 Ni and sup 6 sup 3 Ni. A comparison is made with the experimental and other evaluated data.

  5. Evaluation of the cross-sections of threshold reactions leading to the production of long-lived radionuclides during irradiation of steels by thermonuclear spectrum neutrons

    International Nuclear Information System (INIS)

    Blokhin, A.I.; Buleeva, N.N.; Manokhin, V.N.; Mikhajlyukova, M.V.; Nasyrova, S.M.; Skripova, M.V.

    2002-01-01

    The present paper analyses and evaluates the cross-sections of threshold reactions leading to the production of long-lived radionuclides during the irradiation, by thermonuclear spectrum neutrons, of steels containing V, Ti, Cr, Fe and Ni. On the basis of empirical systematics. a new evaluation of the (n,2n), (n,p), (n,np), (n,α) and (n,nα) excitation functions is made for all isotopes of V, Ti, Cr, Fe and Ni and for intermediate isotopes produced in the chain from irradiated isotopes up to production of the long-lived radionuclides 39 Ar, 42 Ar, 41 Ca, 53 Mn, 60 Fe, 60 Co, 59 Ni and 63 Ni. A comparison is made with the experimental and other evaluated data. (author)

  6. Measurement of activation reaction rate distribution on a mercury target with a lead-reflector and light-water-moderator for high energy proton bombardment using AGS accelerator

    International Nuclear Information System (INIS)

    Kasugai, Yoshimi; Takada, Hiroshi; Meigo, Shin-ichiro

    2001-02-01

    Characteristic of spallation neutrons driven by GeV protons from a mercury target with a lead-reflector and light-water-moderator was studied experimentally using the Alternating Gradient Synchrotron (AGS) facility of Brookhaven National Laboratory in a framework of the ASTE (AGS Spallation Target Experiment) collaboration. Several reaction rates along with the mercury target were measured with the activation method at incident proton energies of 1.94, 12 and 24 GeV. Indium, niobium, aluminum, cobalt, nickel and bismuth were used as activation detectors to cover the threshold energy of between 0.33 and 40.9 MeV. This report summarizes the experimental procedure with all the measured data. (author)

  7. A study of fundamental reaction pathways for transition metal alkyl complexes. I. The reaction of a nickel methyl complex with alkynes. Ii. The mechanism of aldehyde formation in the reaction of a molybdenum hydride with molybdenum alkyls

    Energy Technology Data Exchange (ETDEWEB)

    Huggins, John Mitchell [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)

    1980-06-12

    I. This study reports the rapid reaction under mild conditions of internal or terminal alkynes with methyl (acetyl-acetonato) (triphenylphosphine) nickel (1) in either aromatic or ether solvents. In all cases vinylnickel products 2 are formed by insertion of the alkyne into the nickel=methyl bond. These complexes may be converted into a variety of organic products (e.g. alkenes, esters, vinyl halides) by treatment with appropriate reagents. Unsymmetrical alkynes give selectively the one regioisomer with the sterically largest substituent next to the nickel atom. In order to investigate the stereochemistry of the initial insertion, a x-ray diffraction study of the reaction of 1 with diphenylacetylene was carried out. This showed that the vinylnickel complex formed by overall trans insertion was the product of the reaction. Furthermore, subsequent slow isomerization of this complex, to a mixture of it and the corresponding cis isomer, demonstrated that this trans addition product is the kinetic product of the reaction. In studies with other alkynes, the product of trans addition was not always exclusively (or even predominantly) formed, but the ratio of the stereoisomers formed kinetically was substantially different from the thermodynamic ratio. Isotope labeling, added phosphine, and other experiments have allowed us to conclude that the mechanism of this reaction does involve initial cis addition. However, a coordinatively unsaturated vinylnickel complex is initially formed which can undergo rapid, phosphine-catalyzed cis-trans isomerization in competition with its conversion to the isolable phosphine-substituted kinetic reaction products. II. The reaction of CpMo(CO)3H (1a) with CpMo(CO)3R (2, R= CH3, C2H5) at 50°C in THF gives the aldehyde RCHO and the dimers [CpMo(CO)3]2 (3a) and [CpMo(CO)2]2 (4a). Labeling one of the reactants with a methylcyclopentadienyl ligand

  8. In Situ Solid-State Reactions Monitored by X-ray Absorption Spectroscopy: Temperature-Induced Proton Transfer Leads to Chemical Shifts.

    Science.gov (United States)

    Stevens, Joanna S; Walczak, Monika; Jaye, Cherno; Fischer, Daniel A

    2016-10-24

    The dramatic colour and phase alteration with the solid-state, temperature-dependent reaction between squaric acid and 4,4'-bipyridine has been probed in situ with X-ray absorption spectroscopy. The electronic and chemical sensitivity to the local atomic environment through chemical shifts in the near-edge X-ray absorption fine structure (NEXAFS) revealed proton transfer from the acid to the bipyridine base through the change in nitrogen protonation state in the high-temperature form. Direct detection of proton transfer coupled with structural analysis elucidates the nature of the solid-state process, with intermolecular proton transfer occurring along an acid-base chain followed by a domino effect to the subsequent acid-base chains, leading to the rapid migration along the length of the crystal. NEXAFS thereby conveys the ability to monitor the nature of solid-state chemical reactions in situ, without the need for a priori information or long-range order. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. TLR4-HMGB1 signaling pathway affects the inflammatory reaction of autoimmune myositis by regulating MHC-I.

    Science.gov (United States)

    Wan, Zemin; Zhang, Xiujuan; Peng, Anping; He, Min; Lei, Zhenhua; Wang, Yunxiu

    2016-12-01

    To analyze the effects of TLR4 on the expression of the HMGB1, MHC-I and downstream cytokines IL-6 and TNF-α, and to investigate the biological role of the TLR4-HMGB1 signaling pathway in the development of the autoimmune myositis. We built mice models with experimental autoimmune myositis (EAM) and used the inverted screen experiment to measure their muscle endurance; we also examined inflammatory infiltration of muscle tissues after HE staining; and we assessed the expression of MHC-I using immunohistochemistry. In addition, peripheral blood mononuclear cells (PBMC) were extracted and flow cytometry was utilized to detect the effect of IFN-γ on the expression of MHC-I. Furthermore, PBMCs were treated with IFN-γ, anti-TLR4, anti-HMGB1 and anti-MHC-I. Real-time PCR and western blotting were employed to examine the expressions of TLR4, HMGB1 and MHC-I in different groups. The ELISA method was also utilized to detect the expression of the downstream cytokines TNF-α and IL-6. The expressions of TLR4, HMGB1 and MHC-I in muscle tissues from mice with EAM were significantly higher than those in the control group (all Pmyositis inflammation by regulating the expression of MHC-I and other pro-inflammatory cytokines. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Novel pathway of SO2 oxidation in the atmosphere: reactions with monoterpene ozonolysis intermediates and secondary organic aerosol

    Science.gov (United States)

    Ye, Jianhuai; Abbatt, Jonathan P. D.; Chan, Arthur W. H.

    2018-04-01

    Ozonolysis of monoterpenes is an important source of atmospheric biogenic secondary organic aerosol (BSOA). While enhanced BSOA formation has been associated with sulfate-rich conditions, the underlying mechanisms remain poorly understood. In this work, the interactions between SO2 and reactive intermediates from monoterpene ozonolysis were investigated under different humidity conditions (10 % vs. 50 %). Chamber experiments were conducted with ozonolysis of α-pinene or limonene in the presence of SO2. Limonene SOA formation was enhanced in the presence of SO2, while no significant changes in SOA yields were observed during α-pinene ozonolysis. Under dry conditions, SO2 primarily reacted with stabilized Criegee intermediates (sCIs) produced from ozonolysis, but at 50 % RH heterogeneous uptake of SO2 onto organic aerosol was found to be the dominant sink of SO2, likely owing to reactions between SO2 and organic peroxides. This SO2 loss mechanism to organic peroxides in SOA has not previously been identified in experimental chamber studies. Organosulfates were detected and identified using an electrospray ionization-ion mobility spectrometry-high-resolution time-of-flight mass spectrometer (ESI-IMS-TOF) when SO2 was present in the experiments. Our results demonstrate the synergistic effects between BSOA formation and SO2 oxidation through sCI chemistry and SO2 uptake onto organic aerosol and illustrate the importance of considering the chemistry of organic and sulfur-containing compounds holistically to properly account for their reactive sinks.

  11. Degradation of a cationic dye (Rhodamine 6G) using hydrodynamic cavitation coupled with other oxidative agents: Reaction mechanism and pathway.

    Science.gov (United States)

    Rajoriya, Sunil; Bargole, Swapnil; Saharan, Virendra Kumar

    2017-01-01

    In the present study, decolorization and mineralization of a cationic dye, Rhodamine 6G (Rh6G), has been carried out using hydrodynamic cavitation (HC). Two cavitating devices such as slit and circular venturi were used to generate cavitation in HC reactor. The process parameters such as initial dye concentration, solution pH, operating inlet pressure, and cavitation number were investigated in detail to evaluate their effects on the decolorization efficiency of Rh6G. Decolorization of Rh6G was marginally higher in the case of slit venturi as compared to circular venturi. The kinetic study showed that decolorization and mineralization of the dye fitted first-order kinetics. The loadings of H 2 O 2 and ozone have been optimized to intensify the decolorization and mineralization efficiency of Rh6G using HC. Nearly 54% decolorization of Rh6G was obtained using a combination of HC and H 2 O 2 at a dye to H 2 O 2 molar ratio of 1:30. The combination of HC with ozone resulted in 100% decolorization in almost 5-10min of processing time depending upon the initial dye concentration. To quantify the extent of mineralization, total organic carbon (TOC) analysis was also performed using various processes and almost 84% TOC removal was obtained using HC coupled with 3g/h of ozone. The degradation by-products formed during the complete degradation process were qualitatively identified by liquid chromatography-mass spectrometry (LC-MS) and a detailed degradation pathway has been proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. A-Site Cation Substitutions in Strained Y-Doped BaZrO3 Multilayer Films Leading to Fast Proton Transport Pathways

    Energy Technology Data Exchange (ETDEWEB)

    Aruta, Carmela [Univ. of Roma Tor Vergata, Rome (Italy); Han, Chu [Georgia Inst. of Technology, Atlanta, GA (United States); Zhou, Si [Dalian Univ. of Technology, Dalian (China); Cantoni, Claudia [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yang, Nan [Univ. of Roma Tor Vergata, Rome (Italy); Tebano, Antonello [Univ. of Roma Tor Vergata, Rome (Italy); Lee, Tien -Lin [Diamond Light Source Ltd., Didcot (United Kingdom); Schlueter, Christoph [Diamond Light Source Ltd., Didcot (United Kingdom); Bongiorno, Angelo [College of Staten Island, Staten Island, NY (United States); The Graduate Center of the City Univ. of New York, New York, NY (United States)

    2016-03-31

    Proton-conducting perovskite oxides form a class of solid electrolytes for novel electrochemical devices operating at moderate temperatures. Here, we use hard X-ray photoelectron spectroscopy, scanning transmission electron microscopy, and density functional theory calculations to investigate the structure and elucidate the origin of the fast proton transport properties of strained ultrathin films of Y-doped BaZrO3 grown by pulsed lased deposition on NdGaO3. Our study shows that our BaZr0.8Y0.2O3 films incorporate a significant amount of Y dopants, and to a lesser extent also Zr ions, substituting for Ba2+, and that these substitutional defects agglomerate forming columnar regions crossing vertically from the surface to the interface the entire film. In conclusion, our calculations also show that, in regions rich in Y substitutions for both Zr and Ba, the proton transfer process involves nearly zero-energy barriers, indicating that A-site cation substitutions by Y lead to fast transport pathways and hence are responsible for the previously observed enhanced values of the proton conductivity of these perovskite oxide films.

  13. The Azomethine Ylide Route to Amine C–H Functionalization: Redox-Versions of Classic Reactions and a Pathway to New Transformations

    Science.gov (United States)

    2016-01-01

    Conspectus Redox-neutral methods for the functionalization of amine α-C–H bonds are inherently efficient because they avoid external oxidants and reductants and often do not generate unwanted byproducts. However, most of the current methods for amine α-C–H bond functionalization are oxidative in nature. While the most efficient variants utilize atmospheric oxygen as the terminal oxidant, many such transformations require the use of expensive or toxic oxidants, often coupled with the need for transition metal catalysts. Redox-neutral amine α-functionalizations that involve intramolecular hydride transfer steps provide viable alternatives to certain oxidative reactions. These processes have been known for some time and are particularly well suited for tertiary amine substrates. A mechanistically distinct strategy for secondary amines has emerged only recently, despite sharing common features with a range of classic organic transformations. Among those are such widely used reactions as the Strecker, Mannich, Pictet–Spengler, and Kabachnik–Fields reactions, Friedel–Crafts alkylations, and iminium alkynylations. In these classic processes, condensation of a secondary amine with an aldehyde (or a ketone) typically leads to the formation of an intermediate iminium ion, which is subsequently attacked by a nucleophile. The corresponding redox-versions of these transformations utilize identical starting materials but incorporate an isomerization step that enables α-C–H bond functionalization. Intramolecular versions of these reactions include redox-neutral amine α-amination, α-oxygenation, and α-sulfenylation. In all cases, a reductive N-alkylation is effectively combined with an oxidative α-functionalization, generating water as the only byproduct. Reactions are promoted by simple carboxylic acids and in some cases require no additives. Azomethine ylides, dipolar species whose usage is predominantly in [3 + 2] cycloadditions and other pericyclic

  14. The azomethine ylide route to amine C-H functionalization: redox-versions of classic reactions and a pathway to new transformations.

    Science.gov (United States)

    Seidel, Daniel

    2015-02-17

    Conspectus Redox-neutral methods for the functionalization of amine α-C-H bonds are inherently efficient because they avoid external oxidants and reductants and often do not generate unwanted byproducts. However, most of the current methods for amine α-C-H bond functionalization are oxidative in nature. While the most efficient variants utilize atmospheric oxygen as the terminal oxidant, many such transformations require the use of expensive or toxic oxidants, often coupled with the need for transition metal catalysts. Redox-neutral amine α-functionalizations that involve intramolecular hydride transfer steps provide viable alternatives to certain oxidative reactions. These processes have been known for some time and are particularly well suited for tertiary amine substrates. A mechanistically distinct strategy for secondary amines has emerged only recently, despite sharing common features with a range of classic organic transformations. Among those are such widely used reactions as the Strecker, Mannich, Pictet-Spengler, and Kabachnik-Fields reactions, Friedel-Crafts alkylations, and iminium alkynylations. In these classic processes, condensation of a secondary amine with an aldehyde (or a ketone) typically leads to the formation of an intermediate iminium ion, which is subsequently attacked by a nucleophile. The corresponding redox-versions of these transformations utilize identical starting materials but incorporate an isomerization step that enables α-C-H bond functionalization. Intramolecular versions of these reactions include redox-neutral amine α-amination, α-oxygenation, and α-sulfenylation. In all cases, a reductive N-alkylation is effectively combined with an oxidative α-functionalization, generating water as the only byproduct. Reactions are promoted by simple carboxylic acids and in some cases require no additives. Azomethine ylides, dipolar species whose usage is predominantly in [3 + 2] cycloadditions and other pericyclic processes, have been

  15. Bioelectrocatalytic dechlorination of trichloroacetic acid at gel-immobilized hemoglobin on multiwalled carbon nanotubes modified graphite electrode: Kinetic modeling and reaction pathways

    International Nuclear Information System (INIS)

    Liu, Qi; Yu, Jianming; Xu, Yinghua; Wang, Jiade; Ying, Le; Song, Xinxin; Zhou, Gendi; Chen, Jianmeng

    2013-01-01

    Highlights: ► The electrons transfer from enzyme in the electrode to COCs was the key step. ► The average current efficiency was influenced by pH and temperature of the systems. ► The most favourable degradation conditions for TCA were found to be pH 3 and 310 K. ► The activation energy of 26.2 kJ mol −1 was also calculated by the Arrhenius equation. ► Bioelectrocatalytic mechanism of TCA was verified by kinetic expressions. -- Abstract: In bioelectrochemically reductive dechlorination of chlorinated organic compounds (COCs), the electrons transfer from enzyme in the electrode to COCs was the key step, which determined the average current efficiency (CE) and was influenced by the pH and temperature of the systems. In this work, the effect of temperature (288–318 K) and pH (2–11) of the electrolyte on decholrination of trichloroacetic acid (TCA) was investigated in the sodium alginate/hemoglobin-multiwalled carbon nanotubes-graphite composite electrode (Hb/SA–MWCNT–GE). The results showed that the most favourable degradation conditions for TCA by Hb/SA–MWCNT–GE were found to be pH 3 and 310 K. By varying the pH of the systems, it was found that a proton accompanied with an electron transfer between the electrode and heme Fe(III)/Fe(II) of Hb during the reaction. Additionally, the activation energy of 26.2 kJ mol −1 was also calculated by the Arrhenius equation for the reaction. The total mass balance of the reactant and the products was in the range of 97–105% during the bioelectrochemically reductive reaction. The CE only decreased from 87% to 83% when the Hb/SA–MWCNT–GE was used 5 times. Based on the intermediates detected, a pathway was proposed for TCA degradation in which it underwent dechlorination process. The main degradation mechanism described by a parallel reaction rather than by a sequential reaction for dechlorination of TCA in Hb/SA–MWCNT–GE system was proposed. These data provided relevant information about the

  16. Formation of iodo-trihalomethanes, iodo-acetic acids, and iodo-acetamides during chloramination of iodide-containing waters: Factors influencing formation and reaction pathways

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shaogang [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085 (China); Guangxi Colleges and Universities Key Laboratory of Food Safety and Pharmaceutical Analytical Chemistry, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning, 530006, Guangxi (China); Li, Zhenlin [Guangxi Colleges and Universities Key Laboratory of Food Safety and Pharmaceutical Analytical Chemistry, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning, 530006, Guangxi (China); Dong, Huiyu [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085 (China); Goodman, Bernard A. [College of Physical Science and Engineering, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, 520004, Guangxi (China); Qiang, Zhimin, E-mail: qiangz@rcees.ac.cn [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085 (China)

    2017-01-05

    This study investigated systematically the factors influencing the formation of iodinated disinfection by-products (I-DBPs) during chloramination of I{sup −}-containing waters, including reaction time, NH{sub 2}Cl dose, I{sup −} concentration, pH, natural organic matter (NOM) concentration, Br{sup −}/I{sup −} molar ratio, and water matrix. Among the I-DBPs detected, iodoform (CHI{sub 3}), iodoacetic acid (IAA), diiodoacetic acid (DIAA), triiodoacetic acid (TIAA), and diiodoacetamide (DIAcAm) were the major species produced from reactions between reactive iodine species (HOI/I{sub 2}) and NOM. A kinetic model involving the reactions of NH{sub 2}Cl auto-decomposition, iodine species transformation and NOM consumption was developed, which could well describe NH{sub 2}Cl decay and HOI/I{sub 2} evolution. Higher concentrations of CHI{sub 3}, IAA, DIAA, TIAA, and DIAcAm were observed in chloramination than in chlorination, whereas IO{sub 3}{sup −} was only formed significantly in chlorination. Maximum formation of I-DBPs occurred at pH 8.0, but acidic conditions favored the formation of iodinated haloacetic acids and DIAcAm. Increasing Br{sup −}/I{sup −} molar ratio from 1 to 10 did not increase the total amount of I-DBPs, but produced more bromine-substituting species. In addition, chloramination of 18 model compounds indicated that low-SUVA{sub 254} (specific ultraviolet absorbance at 254 nm) NOM generally favored the formation of I-DBPs compared to high-SUVA{sub 254} NOM. Finally, potential pathways for I-DBPs formation from chloramination of NOM were proposed.

  17. Spectroscopic factors measurement of the five first energy levels of lead 208 nucleus using the 208Pb(e,e'p207Tl* huge pulse transfer reaction

    International Nuclear Information System (INIS)

    Medaglia, R.

    1999-08-01

    In this work, the spectral functions and the spectroscopic factors of the first five energy levels of the lead 208 nucleus have been measured using the 208 Pb(e,e'p) 207 Tl * reaction. The aim is to characterize the effect of the nuclear environment on pulse and energy distributions of protons. In order to minimize the ejected proton-residual nucleus interactions in the final state, the measurement has been performed at 750 and 570 MeV/c pulse transfers, and thus for proton kinetic energies of 263 MeV and 161 MeV, contrarily to a previous measurement performed at 100 MeV. A kinematics with a transverse electromagnetic coupling, instead of a longitudinal one, has been used because of the important coupling dependence observed for medium nuclei. The experiment has been carried out at the NIKHEF electron accelerator and smoothing ring. The pulse distributions of the first five energy levels for a proton pulse range of 0 to 300 MeV/c have been extracted from the (e,e'p) cross sections. An integration of model-dependent distributions gives the spectroscopic factors which indicate the number of protons of each level. These data rae compared to models that include both the proton interactions in the final state and the coulomb distortions. The Pavie model reproduces well the observed distributions and the transfer dependence, while the Ohio model does not. The spectroscopic factors obtained with the Pavie model are the same for both transfers and are 20% higher as an average than the previous experiment performed at 450 MeV/c. However, they are 30% below the shell model. The uncertain estimation of the reaction mechanisms does not allow to consider this reduction as being due exclusively to nuclear structure effects. (J.S.)

  18. Catalytic effects of silver plasmonic nanoparticles on the redox reaction leading to ABTS˙+ formation studied using UV-visible and Raman spectroscopy.

    Science.gov (United States)

    Garcia-Leis, A; Jancura, D; Antalik, M; Garcia-Ramos, J V; Sanchez-Cortes, S; Jurasekova, Z

    2016-09-29

    ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) is a compound extensively employed to evaluate the free radical trapping capacity of antioxidant agents and complex mixtures such as biological fluids or foods. This evaluation is usually performed by using a colourimetric experiment, where preformed ABTS radical cation (ABTS˙ + ) molecules are reduced in the presence of an antioxidant causing an intensity decrease of the specific ABTS˙ + UV-visible absorption bands. In this work we report a strong effect of silver plasmonic nanoparticles (Ag NPs) on ABTS leading to the formation of ABTS˙ + . The reaction of ABTS with Ag NPs has been found to be dependent on the interfacial and plasmonic properties of NPs. Specifically, this reaction is pronounced in the presence of spherical nanoparticles prepared by the reduction of silver nitrate with hydroxylamine (AgH) and in the case of star-shaped silver nanoparticles (AgNS). On the other hand, spherical nanoparticles prepared by the reduction of silver nitrate with citrate apparently do not react with ABTS. Additionally, the formation of ABTS˙ + is investigated by surface-enhanced Raman scattering (SERS) and the assignment of the most intense vibrational bands of this compound is performed. The SERS technique enables us to detect this radical cation at very low concentrations of ABTS (∼2 μM). Altogether, these findings allow us to suggest the use of ABTS/Ag NPs-systems as reliable and easy going substrates to test the antioxidant capacity of various compounds, even at concentrations much lower than those usually used in the spectrophotometric assays. Moreover, we have suggested that ABTS could be employed as a suitable agent to investigate the interfacial and plasmonic properties of the metal nanoparticles and, thus, to characterize the nanoparticle metal systems employed for various purposes.

  19. Quantum chemical investigation of the reaction of O( P2) with certain ...

    Indian Academy of Sciences (India)

    WINTEC

    In the case of methyl radical the minimum energy reaction pathway leads to the products CO + H2 + H. In ... Reactions of atomic oxygen with hydrocarbon radicals play an important role in ..... The reaction between singlet oxygen and propyl ...

  20. A novel miR-371a-5p-mediated pathway, leading to BAG3 upregulation in cardiomyocytes in response to epinephrine, is lost in Takotsubo cardiomyopathy.

    Science.gov (United States)

    d'Avenia, M; Citro, R; De Marco, M; Veronese, A; Rosati, A; Visone, R; Leptidis, S; Philippen, L; Vitale, G; Cavallo, A; Silverio, A; Prota, C; Gravina, P; De Cola, A; Carletti, E; Coppola, G; Gallo, S; Provenza, G; Bossone, E; Piscione, F; Hahne, M; De Windt, L J; Turco, M C; De Laurenzi, V

    2015-10-29

    Molecular mechanisms protecting cardiomyocytes from stress-induced death, including tension stress, are essential for cardiac physiology and defects in these protective mechanisms can result in pathological alterations. Bcl2-associated athanogene 3 (BAG3) is expressed in cardiomyocytes and is a component of the chaperone-assisted autophagy pathway, essential for homeostasis of mechanically altered cells. BAG3 ablation in mice results in a lethal cardiomyopathy soon after birth and mutations of this gene have been associated with different cardiomyopathies including stress-induced Takotsubo cardiomyopathy (TTC). The pathogenic mechanism leading to TTC has not been defined, but it has been suggested that the heart can be damaged by excessive epinephrine (epi) spillover in the absence of a protective mechanism. The aim of this study was to provide more evidence for a role of BAG3 in the pathogenesis of TTC. Therefore, we sequenced BAG3 gene in 70 TTC patients and in 81 healthy donors with the absence of evaluable cardiovascular disease. Mutations and polymorphisms detected in the BAG3 gene included a frequent nucleotide change g2252c in the BAG3 3'-untranslated region (3'-UTR) of Takotsubo patients (PBAG3 upregulation on exposure to epi through an ERK-dependent upregulation of miR-371a-5p. In conclusion, the presence of a g2252c polymorphism in the BAG3 3'-UTR determines loss of miR-371a-5p binding and results in an altered response to epi, potentially representing a new molecular mechanism that contributes to TTC pathogenesis.

  1. Pathways to diagnosis: a qualitative study of the experiences and emotional reactions of parents of children diagnosed with type 1 diabetes.

    Science.gov (United States)

    Rankin, David; Harden, Jeni; Waugh, Norman; Noyes, Kathryn; Barnard, Katharine D; Stephen, John; Robertson, Kenneth J; Bath, Louise; Robertson, Linda; Lawton, Julia

    2014-12-01

    The aim of this study was to explore from parents' perspectives the circumstances and events which led to their child being diagnosed with type 1 diabetes (T1D). The objective was to understand reasons for delays in seeking treatment and parents' emotional reactions to diagnosis so others can be better informed and supported in future. In-depth interviews with 54 parents of children (aged ≤12 yr) with T1D were conducted. Data analysis used an inductive, thematic approach. Parents described a 'prompt' and a 'delayed' pathway to their child being diagnosed. Parents who considered the diagnosis to be 'prompt' reported how they, or other people, had recognized their child had developed symptoms of T1D which resulted in a rapid presentation to health care professionals. In contrast, parents who perceived their child's diagnosis to be 'delayed' did not recognize signs of T1D and attributed their child's deteriorating health to other conditions, being out of routines and/or their stage of development. These parents often only sought medical help when symptoms became extreme. All parents were distressed by their child's diagnosis; however, parents in the 'delayed' pathway expressed unresolved feelings of guilt, particularly when their child was diagnosed with diabetic ketoacidosis. Parents' and other people's knowledge about T1D can affect the duration between onset of their child's symptoms and diagnosis. Campaigns to raise awareness should ensure that parents are made aware of symptoms and that T1D can develop during childhood. Health care professionals could discuss with parents the events preceding their child's diagnosis to better determine their emotional support needs. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Development of a chemical kinetic measurement apparatus and the determination of the reaction rate constants for lithium-lead/water interaction

    International Nuclear Information System (INIS)

    Biney, P.O.

    1993-04-01

    An experimental set-up for accurate measurement of hydrogen generation rate in Lithium-Lead (Li 17 Pb 83 ) Steam or water interactions has been designed. The most important features of the design include a pneumatic actuated quick opening and closing high temperature all stainless steel valve used to control the reaction time and the placement of most measuring devices below a water line to minimize leakage of the hydrogen collected. A PC based data acquisition and control system provides remote process sequencing, acquisition and control of all major components of the set-up. Initial tests indicate that the first design objective of maintaining leakproof gas collection chamber has been achieved. Initial pressure tests indicated that the pressure drop over a time span of 30 minutes was within the tolerance of the pressure transducer used to measure the pressure (within 0.690 kPa) at a nominal system pressure of 685 kPa. The experimental system hardware, data acquisition and control programs and data analysis program have been completed, tested and are currently functional

  3. Oxidation of Tris (2-chloroethyl) phosphate in aqueous solution by UV-activated peroxymonosulfate: Kinetics, water matrix effects, degradation products and reaction pathways.

    Science.gov (United States)

    Xu, Xinxin; Chen, Jing; Qu, Ruijuan; Wang, Zunyao

    2017-10-01

    The feasibility of UV-activated peroxymonosulfate (PMS) technology for the degradation of Tris (2-chloroethyl) phosphate (TCEP) in an aqueous solution was investigated in this study. The conditions of [PMS] 0 : [TCEP] 0  = 20:1, T = 25 ± 2 °C and pH = 5.5 ± 0.5 cause a 94.6% removal of TCEP (1 mg L -1 ) after 30 min of Hg lamp irradiation. The effects of operating parameters (the oxidant doses, pH and presence of typical cations (Fe 3+ , Cu 2+ , Ni 2+ , NH 4 + ), anions (Cl - , HCO 3 - , NO 3 - , HPO 4 2- ) and humic acid (HA)) were evaluated. It was found that an increase of the PMS dose and the presence of Fe 3+ could accelerate the reaction, while the anions and HA inhibited the reaction. Meanwhile, TCEP removal in various water matrices was compared, and the order for TCEP removal was as follows: ultrapure water > tap water > synthetic water > secondary clarifier effluent > Jiuxiang river water. Twenty-two oxidation products were identified using an electrospray time-of-flight mass spectrometer, and the degradation pathways mainly involved radicals' addition and CO bond cleavage. Furthermore, ECOSAR analysis revealed that the intermediate products during the TCEP oxidation process were generally not harmful to three typical aquatic species. Hence, UV/PMS can be used as an efficient technology to treat TCEP-containing water and wastewaters. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Early transcriptional response to aminoglycoside antibiotic suggests alternate pathways leading to apoptosis of sensory hair cells in the mouse inner ear

    Directory of Open Access Journals (Sweden)

    Neil eSegil

    2015-05-01

    Full Text Available Aminoglycoside antibiotics are the drug of choice for treating many bacterial infections, but their administration results in hearing loss in nearly one fourth of the patients who receive them. Several biochemical pathways have been implicated in aminoglycoside antibiotic ototoxicity; however, little is known about how hair cells respond to aminoglycoside antibiotics at the transcriptome level. Here we have investigated the genome-wide response to the aminoglycoside antibiotic gentamicin. Using organotypic cultures of the perinatal organ of Corti, we performed RNA sequencing using cDNA libraries obtained from FACS-purified hair cells. Within 3 hours of gentamicin treatment, the messenger RNA level of more than three thousand genes in hair cells changed significantly. Bioinformatic analysis of these changes highlighted several known signal transduction pathways, including the JNK pathway and the NF-κB pathway, in addition to genes involved in the stress response, apoptosis, cell cycle control, and DNA damage repair. In contrast, only 698 genes, mainly involved in cell cycle and metabolite biosynthetic processes, were significantly affected in the non-hair cell population. The gene expression profiles of hair cells in response to gentamicin share a considerable similarity with those previously observed in gentamicin-induced nephrotoxicity. Our findings suggest that previously observed early responses to gentamicin in hair cells in specific signaling pathways are reflected in changes in gene expression. Additionally, the observed changes in gene expression of cell cycle regulatory genes indicate a disruption of the postmitotic state, which may suggest an alternative pathway regulating gentamicin-induced hair cell death. This work provides a more comprehensive view of aminoglycoside antibiotic ototoxicity, and thus contribute to identifying potential pathways or therapeutic targets to alleviate this important side effect of aminoglycoside

  5. Histopathology and immune histochemistry of red tattoo reactions. Interface dermatitis is the lead pathology, with increase in T-lymphocytes and Langerhans cells suggesting an allergic pathomechanism

    DEFF Research Database (Denmark)

    Høgsberg, T; Thomsen, B M; Serup, J

    2015-01-01

    BACKGROUND: The majority of tattoo reactions are affiliated to red pigmented areas and often suspected to be allergic in nature. A sizeable series of biopsies of such reactions has not previously been performed. The aim of this study was to type and grade epidermal and dermal changes in tattoo re...

  6. Understanding Gender Differences in Children's Risk Taking and Injury: A Comparison of Mothers' and Fathers' Reactions to Sons and Daughters Misbehaving in Ways that Lead to Injury

    Science.gov (United States)

    Morrongiello, Barbara A.; Zdzieborski, Daniel; Normand, Jackie

    2010-01-01

    This study compared reactions of mothers and fathers to the risk taking behavior of sons and daughters. Mother-father pairs (N = 52) imagined their 2-year-old boy or girl behaving in risky ways in common home situations that could, and did, result in injury. Emotional and parenting reactions to the behaviors were assessed before and after injury.…

  7. Comments on leading mesons in anti p Ne - reactions at 607 MeV/c incident momentum in terms of four-momentum transfers in two-vertex diagrams

    International Nuclear Information System (INIS)

    Breivik, F.O.; Haatuft, A.; Halsteinslid, A.

    1990-02-01

    Based on previous observations of anti p Ne - reactions the author discuss, in terms of four-momentum transfers, why only leading pions are seen in events detected by their Λ-decays, and only leading kaons in the events detected by their neutral K-decays. The experimental results are consistent with a two-vertex model with strange or non-strange baryon exchange. 3 refs.; 4 figs.; 1 tab

  8. Interfacial reaction pathways and kinetics during annealing of 111-textured Al/TiN bilayers: A synchrotron x-ray diffraction and transmission electron microscopy study

    International Nuclear Information System (INIS)

    Chun, J.-S.; Desjardins, P.; Lavoie, C.; Petrov, I.; Cabral, C. Jr.; Greene, J. E.

    2001-01-01

    Growth of TiN layers in most diffusion-barrier applications is limited to deposition temperatures T s s =450 deg. C on SiO 2 by ultrahigh vacuum reactive magnetron sputter deposition in pure N 2 . Al overlayers, 160 nm thick with inherited 111 preferred orientation, were then deposited at T s =100 deg. C without breaking vacuum. The as-deposited TiN layer is underdense due to the low deposition temperature (T s /T m ≅0.23 in which T m is the melting point) resulting in kinetically limited adatom mobilities leading to atomic shadowing which, in turn, results in a columnar microstructure with both inter- and intracolumnar voids. The Al overlayer is fully dense. Synchrotron x-ray diffraction was used to follow interfacial reaction kinetics during postdeposition annealing of the 111-textured Al/TiN bilayers as a function of time (t a =12-1200 s) and temperature (T a =440-550 deg. C). Changes in bilayer microstructure and microchemistry were investigated using transmission electron microscopy (TEM) and scanning TEM to obtain compositional maps of plan-view and cross-sectional specimens. Interfacial reaction during annealing is initiated at the Al/TiN interface. Al diffuses rapidly into TiN voids during anneals at temperatures ∼ 3 Ti at the interface. Al 3 Ti exhibits a relatively planar growth front extending toward the Al free surface. Analyses of time-dependent x-ray diffraction peak intensities during isothermal annealing as a function of temperature show that Al 3 Ti growth kinetics are, for the entire temperature range investigated, diffusion limited with an activation energy of 1.5±0.2 eV

  9. Modeling chemical reactions for drug design.

    Science.gov (United States)

    Gasteiger, Johann

    2007-01-01

    Chemical reactions are involved at many stages of the drug design process. This starts with the analysis of biochemical pathways that are controlled by enzymes that might be downregulated in certain diseases. In the lead discovery and lead optimization process compounds have to be synthesized in order to test them for their biological activity. And finally, the metabolism of a drug has to be established. A better understanding of chemical reactions could strongly help in making the drug design process more efficient. We have developed methods for quantifying the concepts an organic chemist is using in rationalizing reaction mechanisms. These methods allow a comprehensive modeling of chemical reactivity and thus are applicable to a wide variety of chemical reactions, from gas phase reactions to biochemical pathways. They are empirical in nature and therefore allow the rapid processing of large sets of structures and reactions. We will show here how methods have been developed for the prediction of acidity values and of the regioselectivity in organic reactions, for designing the synthesis of organic molecules and of combinatorial libraries, and for furthering our understanding of enzyme-catalyzed reactions and of the metabolism of drugs.

  10. Propiconazole-enhanced hepatic cell proliferation is associated with dysregulation of the cholesterol biosynthesis pathway leading to activation of Erk1/2 through Ras farnesylation

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Lynea A.; Moore, Tanya; Nesnow, Stephen, E-mail: nesnow.stephen@epa.gov

    2012-04-15

    Propiconazole is a mouse hepatotumorigenic fungicide designed to inhibit CYP51, a key enzyme in the biosynthesis of ergosterol in fungi and is widely used in agriculture to prevent fungal growth. Metabolomic studies in mice revealed that propiconazole increased levels of hepatic cholesterol metabolites and bile acids, and transcriptomic studies revealed that genes within the cholesterol biosynthesis, cholesterol metabolism and bile acid biosyntheses pathways were up-regulated. Hepatic cell proliferation was also increased by propiconazole. AML12 immortalized hepatocytes were used to study propiconazole's effects on cell proliferation focusing on the dysregulation of cholesterol biosynthesis and resulting effects on Ras farnesylation and Erk1/2 activation as a primary pathway. Mevalonate, a key intermediate in the cholesterol biosynthesis pathway, increases cell proliferation in several cancer cell lines and tumors in vivo and serves as the precursor for isoprenoids (e.g. farnesyl pyrophosphate) which are crucial in the farnesylation of the Ras protein by farnesyl transferase. Farnesylation targets Ras to the cell membrane where it is involved in signal transduction, including the mitogen-activated protein kinase (MAPK) pathway. In our studies, mevalonic acid lactone (MVAL), a source of mevalonic acid, increased cell proliferation in AML12 cells which was reduced by farnesyl transferase inhibitors (L-744,832 or manumycin) or simvastatin, an HMG-CoA reductase inhibitor, indicating that this cell system responded to alterations in the cholesterol biosynthesis pathway. Cell proliferation in AML12 cells was increased by propiconazole which was reversed by co-incubation with L-744,832 or simvastatin. Increasing concentrations of exogenous cholesterol muted the proliferative effects of propiconazole and the inhibitory effects of L-733,832, results ascribed to reduced stimulation of the endogenous cholesterol biosynthesis pathway. Western blot analysis of subcellular

  11. 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

  12. 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.

  13. Chemical kinetics: on the heterogeneous catalysis processes leading to an exchange between two phases. Example: isotopic exchange reactions; Cinetique chimique: sur les processus de catalyse 'heterogene' conduisant a un echange entre deux phases. Exemple: reactions d'echange isotopique

    Energy Technology Data Exchange (ETDEWEB)

    Dirian, G; Grandcollot, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    For an exchange reaction between a gaseous and a liquid phase proceeding by 'heterogeneous' catalysis in the liquid phase, diffusion in the liquid and the chemical reaction are two simultaneous and indivisible processes. We have nevertheless been able to establish criteria making it possible to distinguish between a really homogeneous kinetic process and a pseudo-homogeneous one. (author) [French] Pour une reaction d'echange entre une phase gazeuse et une phase liquide procedant par catalyse 'heterogene' en phase liquide, la diffusion dans le liquide et la reaction chimique sont deux etapes simultanees et indissociables. Nous avons pu neanmoins etablir des criteres permettant de distinguer entre une cinetique homogene vraie et une cinetique pseudo-homogene. (auteur)

  14. 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)

  15. 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).

  16. Mechanism of ({sup 14}N, {sup 12}B) reactions at intermediate energy leading to large spin-polarization of {sup 12}B

    Energy Technology Data Exchange (ETDEWEB)

    Mitsuoka, Shin-ichi [Osaka Univ., Ibaraki (Japan). Research Center for Nuclear Physics; Shimoda, Tadashi; Miyatake, Hiroari [and others

    1996-05-01

    To study mechanisms of the ({sup 14}N, {sup 12}B) reactions at intermediate energies, double differential cross section and nuclear spin-polarization of the {sup 12}B projectile-like fragments have been measured as a function of longitudinal momentum in the angular range of 0deg - 9deg. Large spin-polarization of the reaction products {sup 12}B has been observed in the {sup 9}Be({sup 14}N, {sup 12}B) reaction at 39.3 MeV/u. The momentum distributions at forward angles exhibit characteristic features which can not be understood by the current projectile fragmentation picture. It is shown that by assuming the existence of direct two-proton transfer process in addition to the fragmentation process, both the cross section and polarization of {sup 12}B fragments are successfully explained. The target and incident energy dependence of the momentum distribution are also explained reasonably. (author)

  17. Evaporation residue cross sections and average neutron multiplicities in the /sup 64/Ni+/sup 92/Zr and /sup 12/C+/sup 144/Sm reactions leading to /sup 156/Er

    Energy Technology Data Exchange (ETDEWEB)

    Janssens, R.V.F.; Holzmann, R.; Henning, W.; Khoo, T.L.; Lesko, K.T.; Stephans, G.S.F.; Radford, D.C.; Van den Berg, A.M.; Kuehn, W.; Ronningen, R.M.

    1986-11-27

    Evaporation residue cross sections and neutron multiplicity distributions have been measured for the /sup 12/C+/sup 144/Sm and /sup 64/Ni+/sup 92/Zr reactions leading to the same compound nucleous /sup 156/Er. Statistical model calculations can account for the data in the /sup 12/C-induced reaction. In contrast, the inhibition of neutron emission with respect to statistical model predictions seen in /sup 64/Ni+/sup 92/Zr cannot be explained even with the inclusion of the broad angular momentum distributions required to describe the fusion cross section data.

  18. Disrupting BCR-ABL in combination with secondary leukemia-specific pathways in CML cells leads to enhanced apoptosis and decreased proliferation.

    Science.gov (United States)

    Woessner, David W; Lim, Carol S

    2013-01-07

    Chronic myeloid leukemia (CML) is a myeloproliferative disorder caused by expression of the fusion gene BCR-ABL following a chromosomal translocation in the hematopoietic stem cell. Therapeutic management of CML uses tyrosine kinase inhibitors (TKIs), which block ABL-signaling and effectively kill peripheral cells with BCR-ABL. However, TKIs are not curative, and chronic use is required in order to treat CML. The primary failure for TKIs is through the development of a resistant population due to mutations in the TKI binding regions. This led us to develop the mutant coiled-coil, CC(mut2), an alternative method for BCR-ABL signaling inhibition by targeting the N-terminal oligomerization domain of BCR, necessary for ABL activation. In this article, we explore additional pathways that are important for leukemic stem cell survival in K562 cells. Using a candidate-based approach, we test the combination of CC(mut2) and inhibitors of unique secondary pathways in leukemic cells. Transformative potential was reduced following silencing of the leukemic stem cell factor Alox5 by RNA interference. Furthermore, blockade of the oncogenic protein MUC-1 by the novel peptide GO-201 yielded reductions in proliferation and increased cell death. Finally, we found that inhibiting macroautophagy using chloroquine in addition to blocking BCR-ABL signaling with the CC(mut2) was most effective in limiting cell survival and proliferation. This study has elucidated possible combination therapies for CML using novel blockade of BCR-ABL and secondary leukemia-specific pathways.

  19. Enhanced performance of the methylerythritol phosphate pathway by manipulation of redox reactions relevant to IspC, IspG, and IspH.

    Science.gov (United States)

    Zhou, Jia; Yang, Liyang; Wang, Chonglong; Choi, Eui-Sung; Kim, Seon-Won

    2017-04-20

    The 2C-methyl-D-erythritol 4-phosphate (MEP) pathway is a carbon-efficient route for synthesis of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the building blocks of isoprenoids. However, practical application of a native or recombinant MEP pathway for the mass production of isoprenoids in Escherichia coli has been unsatisfactory. In this study, the entire recombinant MEP pathway was established with plasmids and used for the production of an isoprenoid, protoilludene. E. coli harboring the recombinant MEP pathway plasmid (ME) and a protoilludene synthesis pathway plasmid (AO) produced 10.4mg/L of protoilludene after 48h of culture. To determine the rate-limiting gene on plasmid ME, each constituent gene of the MEP pathway was additionally overexpressed on the plasmid AO. The additional overexpression of IPP isomerase (IDI) enhanced protoilludene production to 67.4mg/L. Overexpression of the Fpr and FldA protein complex, which could mediate electron transfer from NADPH to Fe-S cluster proteins such as IspG and IspH of the MEP pathway, increased protoilludene production to 318.8mg/L. Given that it is required for IspC as well as IspG/H, the MEP pathway has high demand for NADPH. To increase the supply of NADPH, a NADH kinase from Saccharomyces cerevisiae (tPos5p) that converts NADH to NADPH was introduced along with the deletion of a promiscuous NADPH-dependent aldehyde reductase (YjgB) that consumes NADPH. This resulted in a protoilludene production of 512.7mg/L. The results indicate that IDI, Fpr-FldA redox proteins, and NADPH regenerators are key engineering points for boosting the metabolic flux toward a recombinant MEP pathway. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Absence of both Sos-1 and Sos-2 in peripheral CD4+ T cells leads to PI3K pathway activation and defects in migration

    Science.gov (United States)

    Guittard, Geoffrey; Kortum, Robert L; Balagopalan, Lakshmi; Çuburu, Nicolas; Nguyen, Phan; Sommers, Connie L; Samelson, Lawrence E

    2015-01-01

    Sos-1 and Sos-2 are ubiquitously expressed Ras-Guanine Exchange Factors involved in Erk-MAP kinase pathway activation. Using mice lacking genes encoding Sos-1 and Sos-2, we evaluated the role of these proteins in peripheral T-cell signaling and function. Our results confirmed that TCR-mediated Erk activation in peripheral CD4+ T cells does not depend on Sos-1 and Sos-2, although IL-2-mediated Erk activation does. Unexpectedly, however, we show an increase in AKT phosphorylation in Sos-1/2dKO CD4+ T cells upon TCR and IL-2 stimulation. Activation of AKT was likely a consequence of increased recruitment of PI3K to Grb2 upon TCR and/or IL-2 stimulation in Sos-1/2dKO CD4+ T cells. The increased activity of the PI3K/AKT pathway led to downregulation of the surface receptor CD62L in Sos-1/2dKO T cells and a subsequent impairment in T-cell migration. PMID:25973715

  1. Absence of both Sos-1 and Sos-2 in peripheral CD4(+) T cells leads to PI3K pathway activation and defects in migration.

    Science.gov (United States)

    Guittard, Geoffrey; Kortum, Robert L; Balagopalan, Lakshmi; Çuburu, Nicolas; Nguyen, Phan; Sommers, Connie L; Samelson, Lawrence E

    2015-08-01

    Sos-1 and Sos-2 are ubiquitously expressed Ras-guanine exchange factors involved in Erk-MAP kinase pathway activation. Using mice lacking genes encoding Sos-1 and Sos-2, we evaluated the role of these proteins in peripheral T-cell signaling and function. Our results confirmed that TCR-mediated Erk activation in peripheral CD4(+) T cells does not depend on Sos-1 and Sos-2, although IL-2-mediated Erk activation does. Unexpectedly, however, we show an increase in AKT phosphorylation in Sos-1/2dKO CD4(+) T cells upon TCR and IL-2 stimulation. Activation of AKT was likely a consequence of increased recruitment of PI3K to Grb2 upon TCR and/or IL-2 stimulation in Sos-1/2dKO CD4(+) T cells. The increased activity of the PI3K/AKT pathway led to downregulation of the surface receptor CD62L in Sos-1/2dKO T cells and a subsequent impairment in T-cell migration. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  2. Examination of the signal transduction pathways leading to upregulation of tissue type plasminogen activator by Porphyromonas endodontalis in human pulp cells.

    Science.gov (United States)

    Huang, F-M; Chen, Y-J; Chou, M-Y; Chang, Y-C

    2005-12-01

    To investigate the tissue type plasminogen activator (t-PA) activity in human pulp cells stimulated with Porphyromonas endodontalis (P. endodontalis) in the absence or presence of p38 inhibitor SB203580, mitogen-activated protein kinase kinase (MEK) inhibitor U0126 and phosphatidylinositaol 3-kinase (PI3K) inhibitor LY294002. The supernatants of P. endodontalis were used to evaluate t-PA activity in human pulp cells using casein zymography and enzyme-linked immunosorbent assay (ELISA). Furthermore, to search for possible signal transduction pathways, SB203580, U0126 and LY294002 were added to test how they modulated the t-PA activity. The main casein secreted by human pulp cells migrated at 70 kDa and represented t-PA. Secretion of t-PA was found to be stimulated with P. endodontalis during 2-day cultured period (P endodontalis stimulated t-PA production respectively (P endodontalis stimulated t-PA production (P > 0.05). Porphyromonas endodontalis enhances t-PA production in human pulp cells, and the signal transduction pathways p38 and MEK are involved in the inhibition of t-PA.

  3. Program Design Analysis using BEopt Building Energy Optimization Software: Defining a Technology Pathway Leading to New Homes with Zero Peak Cooling Demand; Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R.; Christensen, C.; Horowitz, S.

    2006-08-01

    An optimization method based on the evaluation of a broad range of different combinations of specific energy efficiency and renewable-energy options is used to determine the least-cost pathway to the development of new homes with zero peak cooling demand. The optimization approach conducts a sequential search of a large number of possible option combinations and uses the most cost-effective alternatives to generate a least-cost curve to achieve home-performance levels ranging from a Title 24-compliant home to a home that uses zero net source energy on an annual basis. By evaluating peak cooling load reductions on the least-cost curve, it is then possible to determine the most cost-effective combination of energy efficiency and renewable-energy options that both maximize annual energy savings and minimize peak-cooling demand.

  4. Overexpression of the PP2A regulatory subunit Tap46 leads to enhanced plant growth through stimulation of the TOR signalling pathway

    Science.gov (United States)

    Ahn, Chang Sook; Ahn, Hee-Kyung; Pai, Hyun-Sook

    2015-01-01

    Tap46, a regulatory subunit of protein phosphatase 2A (PP2A), plays an essential role in plant growth and development through a functional link with the Target of Rapamycin (TOR) signalling pathway. Here, we have characterized the molecular mechanisms behind a gain-of-function phenotype of Tap46 and its relationship with TOR to gain further insights into Tap46 function in plants. Constitutive overexpression of Tap46 in Arabidopsis resulted in overall growth stimulation with enlarged organs, such as leaves and siliques. Kinematic analysis of leaf growth revealed that increased cell size was mainly responsible for the leaf enlargement. Tap46 overexpression also enhanced seed size and viability under accelerated ageing conditions. Enhanced plant growth was also observed in dexamethasone (DEX)-inducible Tap46 overexpression Arabidopsis lines, accompanied by increased cellular activities of nitrate-assimilating enzymes. DEX-induced Tap46 overexpression and Tap46 RNAi resulted in increased and decreased phosphorylation of S6 kinase (S6K), respectively, which is a sensitive indicator of endogenous TOR activity, and Tap46 interacted with S6K in planta based on bimolecular fluorescence complementation and co-immunoprecipitation. Furthermore, inactivation of TOR by estradiol-inducible RNAi or rapamycin treatment decreased Tap46 protein levels, but increased PP2A catalytic subunit levels. Real-time quantitative PCR analysis revealed that Tap46 overexpression induced transcriptional modulation of genes involved in nitrogen metabolism, ribosome biogenesis, and lignin biosynthesis. These findings suggest that Tap46 modulates plant growth as a positive effector of the TOR signalling pathway and Tap46/PP2Ac protein abundance is regulated by TOR activity. PMID:25399018

  5. Overexpression of the PP2A regulatory subunit Tap46 leads to enhanced plant growth through stimulation of the TOR signalling pathway.

    Science.gov (United States)

    Ahn, Chang Sook; Ahn, Hee-Kyung; Pai, Hyun-Sook

    2015-02-01

    Tap46, a regulatory subunit of protein phosphatase 2A (PP2A), plays an essential role in plant growth and development through a functional link with the Target of Rapamycin (TOR) signalling pathway. Here, we have characterized the molecular mechanisms behind a gain-of-function phenotype of Tap46 and its relationship with TOR to gain further insights into Tap46 function in plants. Constitutive overexpression of Tap46 in Arabidopsis resulted in overall growth stimulation with enlarged organs, such as leaves and siliques. Kinematic analysis of leaf growth revealed that increased cell size was mainly responsible for the leaf enlargement. Tap46 overexpression also enhanced seed size and viability under accelerated ageing conditions. Enhanced plant growth was also observed in dexamethasone (DEX)-inducible Tap46 overexpression Arabidopsis lines, accompanied by increased cellular activities of nitrate-assimilating enzymes. DEX-induced Tap46 overexpression and Tap46 RNAi resulted in increased and decreased phosphorylation of S6 kinase (S6K), respectively, which is a sensitive indicator of endogenous TOR activity, and Tap46 interacted with S6K in planta based on bimolecular fluorescence complementation and co-immunoprecipitation. Furthermore, inactivation of TOR by estradiol-inducible RNAi or rapamycin treatment decreased Tap46 protein levels, but increased PP2A catalytic subunit levels. Real-time quantitative PCR analysis revealed that Tap46 overexpression induced transcriptional modulation of genes involved in nitrogen metabolism, ribosome biogenesis, and lignin biosynthesis. These findings suggest that Tap46 modulates plant growth as a positive effector of the TOR signalling pathway and Tap46/PP2Ac protein abundance is regulated by TOR activity. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  6. Barley yellow dwarf virus Infection Leads to Higher Chemical Defense Signals and Lower Electrophysiological Reactions in Susceptible Compared to Tolerant Barley Genotypes.

    Science.gov (United States)

    Paulmann, Maria K; Kunert, Grit; Zimmermann, Matthias R; Theis, Nina; Ludwig, Anatoli; Meichsner, Doreen; Oelmüller, Ralf; Gershenzon, Jonathan; Habekuss, Antje; Ordon, Frank; Furch, Alexandra C U; Will, Torsten

    2018-01-01

    Barley yellow dwarf virus (BYDV) is a phloem limited virus that is persistently transmitted by aphids. Due to huge yield losses in agriculture, the virus is of high economic relevance. Since the control of the virus itself is not possible, tolerant barley genotypes are considered as the most effective approach to avoid yield losses. Although several genes and quantitative trait loci are known and used in barley breeding for virus tolerance, little is known about molecular and physiological backgrounds of this trait. Therefore, we compared the anatomy and early defense responses of a virus susceptible to those of a virus-tolerant cultivar. One of the very early defense responses is the transmission of electrophysiological reactions. Electrophysiological reactions to BYDV infection might differ between susceptible and tolerant cultivars, since BYDV causes disintegration of sieve elements in susceptible cultivars. The structure of vascular bundles, xylem vessels and sieve elements was examined using microscopy. All three were significantly decreased in size in infected susceptible plants where the virus causes disintegration of sieve elements. This could be associated with an uncontrolled ion exchange between the sieve-element lumen and apoplast. Further, a reduced electrophysiological isolation would negatively affect the propagation of electrophysiological reactions. To test the influence of BYDV infection on electrophysiological reactions, electropotential waves (EPWs) induced by leaf-tip burning were recorded using aphids as bioelectrodes. EPWs in infected susceptible plants disappeared already after 10 cm in contrast to those in healthy susceptible or infected tolerant or healthy tolerant plants. Another early plant defense reaction is an increase in reactive oxygen species (ROS). Using a fluorescent dye, we found a significant increase in ROS content in infected susceptible plants but not in infected tolerant plants. Similar results were found for the

  7. Quercetin, ascorbic acid, caffeine and ellagic acid are more efficient than rosiglitazone, metformin and glimepiride in interfering with pathways leading to the development of neurological complications associated with diabetes: A comparative in-vitro study

    Directory of Open Access Journals (Sweden)

    Vineet Mehta

    2017-06-01

    Full Text Available Neuropathy is the least understood and most devastating complication associated with diabetes. Diabetic neuropathy develops in patients despite of regular therapy, indicating that marketed drugs has minimal effect on pathways leading to the development and progression of these complications. Present study was aimed to evaluate natural compounds for their ability to interfere with pathways leading to the development of diabetes mediated neurological complications and compare their efficacy with marketed anti-diabetic drugs. Anti-diabetic potential of ascorbic acid, gallic acid, quercetin, ellagic acid, cinnamic acid, caffeine and piperine was predicted by evaluating in-silico interaction energy (kcal/mol of these compounds with insulin receptor, peroxisome proliferator-activated receptor gamma-γ and dipeptidyl peptidase-4 proteins. Ascorbic acid, gallic acid, quercetin and ellagic acid showed excellent in-vitro antioxidant activity in DPPH radical scavenging and inhibition of lipid peroxidation assay, which was 1.5–3 folds better than the marketed drugs. Quercetin, gallic acid, cinnamic acid, piperine and caffeine efficiently prevented H2O2 induced genotoxicity, which commercial drugs failed to prevent. Further, quercetin, ellagic acid, caffeine and ascorbic acid were 3–4.7 folds better than marketed drugs in inhibiting α-amylase activity. Herbal molecules and rosiglitazone showed comparable results for glucose uptake, which may be attributed to enhanced GLUT4 translocation into primary neuronal culture under hyperglycemic conditions. In conclusion, currently available marketed anti-diabetic drugs have minimal effect on the pathways leading to diabetic neuropathy and supplementing diabetic therapeutics with quercetin, ascorbic acid, caffeine and ellagic acid may be better suited to counter diabetic neuropathy through inhibiting oxidative stress, genotoxicity and improving neuronal glucose utilization.

  8. Excitation functions and yields of proton induced reactions at intermediate energies leading to important diagnostics radioisotopes of 52Fe, 77Br, 82Rb, 97Ru, 111In, 123I, 127Xe, 128Cs, 178Ta and 201Tl

    International Nuclear Information System (INIS)

    Rurarz, E.

    1994-01-01

    This report describes investigations of the excitation functions of the proton induced reactions on 14 targets (Mn, Co, Br, Rb, 99 Tc, 113 Cd, 114 Cd, Cd, I, Cs, Ta, 206,207,208 Pb) leading directly or indirectly to the formation of radionuclides 52 Fe, 77 Br, 82 Rb, 97 Ru, 111 In, 123 I, 127 Xe, 128 Cs, 178 Ta and 201 Tl frequently used in diagnostic procedures of nuclear medicine. The measurements of the excitation functions were made over a wide proton energy range from the reaction threshold up to 100 MeV using the stacked foil (or pellet) technique. Small energy steps were used to allow for accurate determination of the structure of excitation functions. For 97 Ru, 111 In and 127 Xe formation with protons, new reaction channels and targets were used and data concerning this method are published for the first time. The data for 52 Fe, 77 Br, 82 Rb, 123 I, 128 Cs and 201 Tl obtained in the present work for the E p =70-100 MeV region are also published for the first time. The measured excitation functions for the formation of desired (and undesired) radionuclides (altogether 28 excitation functions) are compared with the theoretical ones calculated on the basis of a hybrid model of nuclear reactions in the form of the Overlaid Alice computer code. In order to determine the contribution of the competitive reaction channels to the purity of the produced, desired radionuclide, the excitation functions of the accompanying reactions were also calculated. The 122 calculated excitation functions for the possible contaminant are given in the present work. The comparison of experimental excitation functions with the results of model calculations showed satisfactory agreement, especially if one considers, that no parameter adjustment for individual reaction products was undertaken. From the measured excitation functions the production yields for 28 radionuclides mentioned above have been determined (author). 262 refs, 65 figs, 34 tabs

  9. Perinatal Western Diet Consumption Leads to Profound Plasticity and GABAergic Phenotype Changes within Hypothalamus and Reward Pathway from Birth to Sexual Maturity in Rat

    Directory of Open Access Journals (Sweden)

    Julie Paradis

    2017-08-01

    Full Text Available Perinatal maternal consumption of energy dense food increases the risk of obesity in children. This is associated with an overconsumption of palatable food that is consumed for its hedonic property. The underlying mechanism that links perinatal maternal diet and offspring preference for fat is still poorly understood. In this study, we aim at studying the influence of maternal high-fat/high-sugar diet feeding [western diet (WD] during gestation and lactation on the reward pathways controlling feeding in the rat offspring from birth to sexual maturity. We performed a longitudinal follow-up of WD and Control offspring at three critical time periods (childhood, adolescence, and adulthood and focus on investigating the influence of perinatal exposure to palatable diet on (i fat preference, (ii gene expression profile, and (iii neuroanatomical/architectural changes of the mesolimbic dopaminergic networks. We showed that WD feeding restricted to the perinatal period has a clear long-lasting influence on the organization of homeostatic and hedonic brain circuits but not on fat preference. We demonstrated a period specific evolution of the preference for fat that we correlated with specific brain molecular signatures. In offspring from WD fed dams, we observed during childhood the existence of fat preference associated with a higher expression of key gene involved in the dopamine (DA systems; at adolescence, a high-fat preference for both groups, progressively reduced during the 3 days test for the WD group and associated with a reduced expression of key gene involved in the DA systems for the WD group that could suggest a compensatory mechanism to protect them from further high-fat exposure; and finally at adulthood, a preference for fat that was identical to control rats but associated with profound modification in key genes involved in the γ-aminobutyric acid network, serotonin receptors, and polysialic acid–NCAM-dependent remodeling of the

  10. Premeditation and Sensation Seeking Moderate the Reasoned Action and Social Reaction Pathways in the Prototype/Willingness Model of Alcohol Use.

    Science.gov (United States)

    Vaughn, Matthew Gregory; King, Kevin M

    2016-05-11

    Drinking can occur because of expectations to drink (reasoned pathway) or because of willingness to drink under certain circumstances (reactive pathway). These pathways are thought to be influenced by different cognitions such as alcohol-related attitudes, norms, or drinking prototypes (Gerrard et al., 2008). Impulsive traits reflect individual differences in the influence of reasoned or reactive factors, however little research has investigated whether impulsivity moderates the effects of cognitive factors predicting alcohol use. We tested whether differences in three impulsivity traits (premeditation, sensation seeking and negative urgency) moderated associations of reasoned (risk/disapproval attitudes and social norms) and reactive (prototype) pathway variables on expectation/willingness to drink and recent alcohol use. We collected data from n = 409 college students; the sample was 67% female, 43% Asian American, with Mdnage = 19. Hypotheses were tested using multiple regression. Premeditation and sensation seeking moderated reasoned variable effects on expectation and drinking. Among those low on premeditation, risk attitudes were most associated with drinking expectation, with alcohol prototypes most related to recent drinking. These effects declined at higher premeditation levels. Among those high on sensation seeking, risk attitudes were most associated with expectation and drinking, declining at lower sensation seeking levels. There was little evidence of moderation predicting drinking willingness. Findings imply personality differences may explain association strength between reasoned but not reactive risk behavior pathways with alcohol outcomes. They have ramifications for personalized prevention programs to reduce drinking through cognition change, as alcohol-related cognition influence may differ depending on personality characteristics.

  11. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    International Nuclear Information System (INIS)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei

    2017-01-01

    Highlights: • CsPbBr_3 perovskite nanocrystals have been synthesized in the presence of organic amines with different hydrocarbon length. • The photoluminescence of the CsPbBr_3 nanocrystals is affected by the varying the carbon length of the organic amines. • The lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr_3 nanocrystals. - Abstract: All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr_3 nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr_3 NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr_3 NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55–80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr_3 NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr_3 NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the product synthesized in the presence of

  12. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei, E-mail: awtang@bjtu.edu.cn

    2017-05-31

    Highlights: • CsPbBr{sub 3} perovskite nanocrystals have been synthesized in the presence of organic amines with different hydrocarbon length. • The photoluminescence of the CsPbBr{sub 3} nanocrystals is affected by the varying the carbon length of the organic amines. • The lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr{sub 3} nanocrystals. - Abstract: All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr{sub 3} nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr{sub 3} NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr{sub 3} NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55–80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr{sub 3} NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr{sub 3} NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the

  13. Tissue reactions to bacteria-inoculated rat lead samples .2. Effect of local gentamicin release through surface-modified polyurethane tubing

    NARCIS (Netherlands)

    vanWachem, PB; vanLuyn, MJA; deWit, AW; Raatjes, D; Hendriks, M; Verhoeven, MLPM; Cahalan, PT

    A surface modification technique was developed to achieve controlled release of gentamicin from implanted polyurethane (PU) rat lead samples. PU tubing first was provided with an acrylic acid/acrylamide copolymer surface graft and then loaded with gentamicin. This surface modification technique

  14. Two Sets of Piwi Proteins Are Involved in Distinct sRNA Pathways Leading to Elimination of Germline-Specific DNA

    Directory of Open Access Journals (Sweden)

    Dominique I. Furrer

    2017-07-01

    Full Text Available Piwi proteins and piRNAs protect eukaryotic germlines against the spread of transposons. During development in the ciliate Paramecium, two Piwi-dependent sRNA classes are involved in the elimination of transposons and transposon-derived DNA: scan RNAs (scnRNAs, associated with Ptiwi01 and Ptiwi09, and iesRNAs, whose binding partners we now identify as Ptiwi10 and Ptiwi11. scnRNAs derive from the maternal genome and initiate DNA elimination during development, whereas iesRNAs continue DNA targeting until the removal process is complete. Here, we show that scnRNAs and iesRNAs are processed by distinct Dicer-like proteins and bind Piwi proteins in a mutually exclusive manner, suggesting separate biogenesis pathways. We also demonstrate that the PTIWI10 gene is transcribed from the developing nucleus and that its transcription depends on prior DNA excision, suggesting a mechanism of gene expression control triggered by the removal of short DNA segments interrupting the gene.

  15. Protective Effects of Green Tea Polyphenol Against Renal Injury Through ROS-Mediated JNK-MAPK Pathway in Lead Exposed Rats.

    Science.gov (United States)

    Wang, Haidong; Li, Deyuan; Hu, Zhongze; Zhao, Siming; Zheng, Zhejun; Li, Wei

    2016-06-30

    To investigate the potential therapeutic effects of polyphenols in treating Pb induced renal dysfunction and intoxication and to explore the detailed underlying mechanisms. Wistar rats were divided into four groups: control groups (CT), Pb exposure groups (Pb), Pb plus Polyphenols groups (Pb+PP) and Polyphenols groups (PP). Animals were kept for 60 days and sacrificed for tests of urea, serum blood urea nitrogen (BUN) and creatinine. Histological evaluations were then performed. In vitro studies were performed using primary kidney mesangial cells to reveal detailed mechanisms. Cell counting kit-8 (CCK-8) was used to evaluate cell viability. Pb induced cell apoptosis was measured by flow cytometry. Reactive oxygen species (ROS) generation and scavenging were tested by DCFH-DA. Expression level of tumor necrosis factor-α (TNF-α), interleukin-1-β (IL-1-β) and IL-6 were assayed by ELISA. Western blot and qPCR were used to measure the expression of ERK1/2, JNK1/2 and p38. Polyphenols have obvious protective effects on Pb induced renal dysfunction and intoxication both in vivo and in vitro. Polyphenols reduced Pb concentration and accumulation in kidney. Polyphenols also protected kidney mesangial cells from Pb induced apoptosis. Polyphenols scavenged Pb induced ROS generation and suppressed ROS-mediated ERK/JNK/p38 pathway. Downstream pro-inflammatory cytokines were inhibited in consistency. Polyphenol is protective in Pb induced renal intoxication and inflammatory responses. The underlying mechanisms lie on the antioxidant activity and ROS scavenging activity of polyphenols.

  16. A New Pathway to 3-Hetaryl-2-oxo-2H-chromenes: On the Proposed Mechanisms for the Reaction of 3-Carbamoyl-2-iminochromenes with Dinucleophiles

    Directory of Open Access Journals (Sweden)

    Yaroslav V. Bilokin

    2000-10-01

    Full Text Available The present account summarizes the author's studies to elucidate the mechanisms of the recently reported rearrangements resulting from inter- and/or intramolecular reactions of 2-imino-2H-chromene-3-carboxamides with different dinucleophiles.

  17. Atypical McMurry Cross-Coupling Reactions Leading to a New Series of Potent Antiproliferative Compounds Bearing the Key [Ferrocenyl-Ene-Phenol] Motif

    Directory of Open Access Journals (Sweden)

    Pascal Pigeon

    2014-07-01

    Full Text Available In the course of the preparation of a series of ferrocenyl derivatives of diethylstilbestrol (DES, in which one of the 4-hydroxyphenyl moieties was replaced by a ferrocenyl group, the McMurry reaction of chloropropionylferrocene with a number of mono-aryl ketones unexpectedly yielded the hydroxylated ferrocenyl DES derivatives, 5a–c, in poor yields (10%–16%. These compounds showed high activity on the hormone-independent breast cancer cell line MDA-MB-231 with IC50 values ranging from 0.14 to 0.36 µM. Surprisingly, non-hydroxylated ferrocenyl DES, 4, showed only an IC50 value of 1.14 µM, illustrating the importance of the hydroxyethyl function in this promising new series. For comparison, McMurry reactions of the shorter chain analogue chloroacetylferrocene were carried out to see the difference in behaviour with mono-aryl ketones versus a diaryl ketone. The effect of changing the length of the alkyl chain adjacent to the phenolic substituent of the hydroxylated ferrocenyl DES was studied, a mechanistic rationale to account for the unexpected products is proposed, and the antiproliferative activities of all of these compounds on MDA-MB-231 cells lines were measured and compared. X-ray crystal structures of cross-coupled products and of pinacol-pinacolone rearrangements are reported.

  18. Elevated CO2 leads to carbon sequestration by modulating C4 photosynthesis pathway enzyme (PPDK) in Suaeda monoica and S. fruticosa.

    Science.gov (United States)

    Yadav, Sonam; Mishra, Avinash; Jha, Bhavanath

    2018-01-01

    The C 4 halophytic species Suaeda monoica and S. fruticosa, possess the C 4 photosynthesis pathway without Kranz anatomy were grown at ambient (470ppm CO 2 ) and elevated (850ppm CO 2 ) atmospheric CO 2 under control containment facility to study the plant response under CO 2 stress condition. The relative growth of both Suaeda species was enhanced with atmospheric CO 2 enrichment compared to control (ambient) condition. The photosynthesis rate was found 2.5μmolCO 2 m -2 s -1 in both species under stress condition compared to about 1.9μmolCO 2 m -2 s -1 under control conditions. About 0.3molH 2 Om -2 s -1 conductance was detected under an unstressed condition which decreased significantly to ~0.07molH 2 Om -2 s -1 on the 6th day of stress treatment. Similarly, transpiration rate was also decreased significantly from 4.4-5.2mmolH 2 Om -2 s -1 to 1.7-1.9 under stress condition. In contrast, VpdL increased significantly from 1.9kPa to 2.5kPa under stress condition. A higher total chlorophyll content observed in S. monoica (56.36mgg -1 tissue) compared to S. fruticosa (33.12mgg -1 tissue) under unstressed (control) condition. A significant increase was found in the total chlorophyll content of S. fruticosa (45.47mgg -1 tissue) with stress treatment compared to control (33.12mgg -1 tissue). In contrast, the total chlorophyll decreased in S. monoica (51.58mgg -1 tissue) under similar stress condition compared to control plants (56.36mgg -1 tissue). About 6-6.8mg total sugar per gram tissue found under control condition which enhanced further (7.5 to 11mgg -1 tissue) under stress condition. Similarly, total reducing sugar (~2mgg -1 tissue) and total starch content (6.5-11mgg -1 tissue) increased under stress condition. About 6.5- and 3- fold higher expression of PPDK gene was observed for S. monoica and S. fruticosa, respectively under CO 2 stress condition. PPDK (1.2- and 1.5- fold) and antioxidant enzymes; APX (12.7- and two-fold), CAT (2.2- and 6.4- fold) and SOD (4

  19. Differential Expression of Adhesion-Related Proteins and MAPK Pathways Lead to Suitable Osteoblast Differentiation of Human Mesenchymal Stem Cells Subpopulations.

    Science.gov (United States)

    Leyva-Leyva, Margarita; López-Díaz, Annia; Barrera, Lourdes; Camacho-Morales, Alberto; Hernandez-Aguilar, Felipe; Carrillo-Casas, Erika M; Arriaga-Pizano, Lourdes; Calderón-Pérez, Jaime; García-Álvarez, Jorge; Orozco-Hoyuela, Gabriel; Piña-Barba, Cristina; Rojas-Martínez, Augusto; Romero-Díaz, Víktor; Lara-Arias, Jorge; Rivera-Bolaños, Nancy; López-Camarillo, César; Moncada-Saucedo, Nidia; Galván-De los Santos, Alejandra; Meza-Urzúa, Fátima; Villarreal-Gómez, Luis; Fuentes-Mera, Lizeth

    2015-11-01

    Cellular adhesion enables communication between cells and their environment. Adhesion can be achieved throughout focal adhesions and its components influence osteoblast differentiation of human mesenchymal stem cells (hMSCs). Because cell adhesion and osteoblast differentiation are closely related, this article aimed to analyze the expression profiles of adhesion-related proteins during osteoblastic differentiation of two hMSCs subpopulations (CD105(+) and CD105(-)) and propose a strategy for assembling bone grafts based on its adhesion ability. In vitro experiments of osteogenic differentiation in CD105(-) cells showed superior adhesion efficiency and 2-fold increase of α-actinin expression compared with CD105(+) cells at the maturation stage. Interestingly, levels of activated β1-integrin increased in CD105(-) cells during the process. Additionally, the CD105(-) subpopulation showed 3-fold increase of phosphorylated FAK(Y397) compared to CD105(+) cells. Results also indicate that ERK1/2 was activated during CD105(-) bone differentiation and participation of mitogen-activated protein kinase (MAPK)-p38 in CD105(+) differentiation through a focal adhesion kinase (FAK)-independent pathway. In vivo trial demonstrated that grafts containing CD105(-) showed osteocytes embedded in a mineralized matrix, promoted adequate graft integration, increased host vascular infiltration, and efficient intramembranous repairing. In contrast, grafts containing CD105(+) showed deficient endochondral ossification and fibrocartilaginous tissue. Based on the expression of α-actinin, FAKy,(397) and ERK1/2 activation, we define maturation stage as critical for bone graft assembling. By in vitro assays, CD105(-) subpopulation showed superior adhesion efficiency compared to CD105(+) cells. Considering in vitro and in vivo assays, this study suggests that integration of a scaffold with CD105(-) subpopulation at the maturation stage represents an attractive strategy for clinical use in

  20. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    Science.gov (United States)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei

    2017-05-01

    All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr3 nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr3 NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr3 NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55-80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr3 NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr3 NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the product synthesized in the presence of oleylamine (OLAm), but only flat nanoplates are observed in the products in the presence of OTAm at 120 °C. The results indicate that the lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr3 NCs. This work opens up an alternative approach to controllable-synthesis of perovskite NCs through varying the carbon chain length of organic surfactants, and enlightens

  1. On the reaction in the lead-acid battery (as the special review-article by the 2005' Gaston Planté Medal recipient)

    Science.gov (United States)

    Takehara, Zen-ichiro

    It is my great pleasure to be awarded with the 2005' Gaston Planté Medal for significant contribution to the development of lead-acid battery science and technology. I would like to thank most heartily to Prof. D. Pavlov of Chairman, and all members of the Organic Committee of LABAT'2005 for the best treatment to select me as a 2005' Gaston Planté Medallist.

  2. Reaction Coordinate Leading to H2 Production in [FeFe]-Hydrogenase Identified by Nuclear Resonance Vibrational Spectroscopy and Density Functional Theory.

    Science.gov (United States)

    Pelmenschikov, Vladimir; Birrell, James A; Pham, Cindy C; Mishra, Nakul; Wang, Hongxin; Sommer, Constanze; Reijerse, Edward; Richers, Casseday P; Tamasaku, Kenji; Yoda, Yoshitaka; Rauchfuss, Thomas B; Lubitz, Wolfgang; Cramer, Stephen P

    2017-11-22

    [FeFe]-hydrogenases are metalloenzymes that reversibly reduce protons to molecular hydrogen at exceptionally high rates. We have characterized the catalytically competent hydride state (H hyd ) in the [FeFe]-hydrogenases from both Chlamydomonas reinhardtii and Desulfovibrio desulfuricans using 57 Fe nuclear resonance vibrational spectroscopy (NRVS) and density functional theory (DFT). H/D exchange identified two Fe-H bending modes originating from the binuclear iron cofactor. DFT calculations show that these spectral features result from an iron-bound terminal hydride, and the Fe-H vibrational frequencies being highly dependent on interactions between the amine base of the catalytic cofactor with both hydride and the conserved cysteine terminating the proton transfer chain to the active site. The results indicate that H hyd is the catalytic state one step prior to H 2 formation. The observed vibrational spectrum, therefore, provides mechanistic insight into the reaction coordinate for H 2 bond formation by [FeFe]-hydrogenases.

  3. The role of aryl hydrocarbon receptor signaling pathway in cardiotoxicity of acute lead intoxication in vivo and in vitro rat model.

    Science.gov (United States)

    Ansari, Mushtaq A; Maayah, Zaid H; Bakheet, Saleh A; El-Kadi, Ayman O; Korashy, Hesham M

    2013-04-05

    Lead (Pb(2+)) is a naturally occurring systemic toxicant heavy metal that affects several organs in the body including the kidneys, liver, and central nervous system. However, Pb(2+)-induced cardiotoxicity has never been investigated yet and the exact mechanism of Pb(2+) associated cardiotoxicity has not been studied. The current study was designed to investigate the potential effect of Pb(2+) to induce cardiotoxicity in vivo and in vitro rat model and to explore the molecular mechanisms and the role of aryl hydrocarbon receptor (AhR) and regulated gene, cytochrome P4501A1 (CYP1A1), in Pb(2+)-mediated cardiotoxicity. For these purposes, Wistar albino rats were treated with Pb(2+) (25, 50 and 100mg/kg, i.p.) for three days and the effects on physiological and histopathological parameters of cardiotoxicity were determined. At the in vitro level, rat cardiomyocyte H9c2 cell lines were incubated with increasing concentration of Pb(2+) (25, 50, and 100 μM) and the expression of hypertrophic genes, α- and β-myosin heavy chain (α-MHC and β-MHC), brain Natriuretic Peptide (BNP), and CYP1A1 were determined at the mRNA and protein levels using real-time PCR and Western blot analysis, respectively. The results showed that Pb(2+) significantly induced cardiotoxicity and heart failure as evidenced by increase cardiac enzymes, lactate dehydrogenase and creatine kinase and changes in histopathology in vivo. In addition, Pb(2+) treatment induced β-MHC and BNP whereas inhibited α-MHC mRNA and protein levels in vivo in a dose-dependent manner. In contrast, at the in vitro level, Pb(2+) treatment induced both β-MHC and α-MHC mRNA levels in time- and dose-dependent manner. Importantly, these changes were accompanied with a proportional increase in the expression of CYP1A1 mRNA and protein expression levels, suggesting a role for the CYP1A1 in cardiotoxicity. The direct evidence for the involvement of CYP1A1 in the induction of cardiotoxicity by Pb(2+) was evidenced by the

  4. LEADING WITH LEADING INDICATORS

    International Nuclear Information System (INIS)

    PREVETTE, S.S.

    2005-01-01

    This paper documents Fluor Hanford's use of Leading Indicators, management leadership, and statistical methodology in order to improve safe performance of work. By applying these methods, Fluor Hanford achieved a significant reduction in injury rates in 2003 and 2004, and the improvement continues today. The integration of data, leadership, and teamwork pays off with improved safety performance and credibility with the customer. The use of Statistical Process Control, Pareto Charts, and Systems Thinking and their effect on management decisions and employee involvement are discussed. Included are practical examples of choosing leading indicators. A statistically based color coded dashboard presentation system methodology is provided. These tools, management theories and methods, coupled with involved leadership and employee efforts, directly led to significant improvements in worker safety and health, and environmental protection and restoration at one of the nation's largest nuclear cleanup sites

  5. Use of ESI-MS to determine reaction pathway for hydrogen sulphide scavenging with 1,3,5-tri-(2-hydroxyethyl)-hexahydro-s-triazine

    DEFF Research Database (Denmark)

    Madsen, Henrik Tækker; Søgaard, Erik Gydesen

    2012-01-01

    To study the reaction between hydrogen sulphide and 1,3,5-tri-(2-hydroxyethyl)- hexahydro-s-triazine, which is an often used hydrogen sulphide scavenger, electro spray ionisation mass spectrometry (ESI-MS) was used. The investigation was carried out in positive mode, and tandem mass spectrometry...... the dithiazine species, hereby confirming previously obtained results and showing the ability of the ESI-MS method for studying the scavenging reaction. The final theoretical product s-trithiane was not detected. Furthermore, fragmentation products of thiadiazine and dithiazine were detected in the solution...

  6. Theoretical study on keto-enol tautomerisation of glutarimide for exploration of the isomerisation reaction pathway of glutamic acid in proteins using density functional theory

    Science.gov (United States)

    Fukuyoshi, Shuichi; Nakayoshi, Tomoki; Takahashi, Ohgi; Oda, Akifumi

    2017-03-01

    In order to elucidate the reason why glutamic acid residues have lesser racemisation reactivity than asparaginic acid, we investigated the racemisation energy barrier of piperidinedione, which is the presumed intermediate of the isomerisation reaction of L-Glu to D-Glu, by density functional theory calculations. In two-water-molecule-assisted racemisation, the activation barrier for keto-enol isomerisation was 28.1 kcal/mol. The result showed that the activation barrier for the racemisation of glutamic acid residues was not different from that for the racemisation of aspartic acid residues. Thus, glutamic acid residues can possibly cause the racemisation reaction if the cyclic intermediate stably exists.

  7. Neutron production in spallation reactions of 0.9 and 1.5 GeV protons on a thick lead target. Comparison between experimental data and Monte-Carlo simulations

    International Nuclear Information System (INIS)

    Krasa, A.; Krizek, F.; Wagner, V.; Kugler, A.; Henzl, V.; Henzlova, D.; Majerle, M.; Adam, J.; Caloun, P.; Bradnova, V.; Chultem, D.; Kalinnikov, V.G.; Krivopustov, M.I.; Solnyshkin, A.A.; Stegajlov, V.I.; Tsupko-Sitnikov, V.M.; Tumehndehlgehr, Ts.; Vasil'ev, S.I.

    2005-01-01

    This paper reports on two experiments performed at the Synchrophasotron/Nuclotron accelerator complex at JINR. Relativistic protons with energies 885 MeV and 1.5 GeV hit a massive cylindrical lead target. The spatial and energetic distributions of the neutron field produced by the spallation reactions were measured by the activation of Al, Au, Bi, Co, and Cu foils placed on the surface of the target and close to it. The yields of the radioactive nuclei produced by threshold reactions in these foils were determined by the analyses of their γ spectra. The comparison with Monte-Carlo based simulations was performed both with the LAHET+MCNP code and the MCNPX code

  8. Neutron Production in Spallation Reactions of 0.9 and 1.5 GeV Protons on a Thick Lead Target. Comparison between Experimental Data and Monte-Carlo Simulations

    CERN Document Server

    Krasa, A; Bradnova, V; Caloun, P; Chultem, D; Henzl, V; Henzlová, D; Kalinnikov, V G; Krivopustov, M I; Krízek, F; Kugler, A; Majerle, M; Solnyshkin, A A; Stegailov, V I; Tsoupko-Sitnikov, V M; Tumendelger, T; Vasilev, S I; Wagner, V; Nuclear Physics Institute of Academy of Sciences of Czech Republic, Rez, Czech Republic

    2005-01-01

    This paper reports on two experiments performed at the Synchrophasotron/Nuclotron accelerator complex at JINR. Relativistic protons with energies 885 MeV and 1.5 GeV hit a massive cylindrical lead target. The spatial and energetic distributions of the neutron field produced by the spallation reactions were measured by the activation of Al, Au, Bi, Co, and Cu foils placed on the surface of the target and close to it. The yields of the radioactive nuclei produced by threshold reactions in these foils were determined by the analyses of their $\\gamma$ spectra. The comparison with Monte-Carlo based simulations was performed both with the LAHET+MCNP code and the MCNPX code.

  9. 48Ca+249Bk fusion reaction leading to element Z = 117: long-lived α-decaying 270Db and discovery of 266Lr.

    Science.gov (United States)

    Khuyagbaatar, J; Yakushev, A; Düllmann, Ch E; Ackermann, D; Andersson, L-L; Asai, M; Block, M; Boll, R A; Brand, H; Cox, D M; Dasgupta, M; Derkx, X; Di Nitto, A; Eberhardt, K; Even, J; Evers, M; Fahlander, C; Forsberg, U; Gates, J M; Gharibyan, N; Golubev, P; Gregorich, K E; Hamilton, J H; Hartmann, W; Herzberg, R-D; Heßberger, F P; Hinde, D J; Hoffmann, J; Hollinger, R; Hübner, A; Jäger, E; Kindler, B; Kratz, J V; Krier, J; Kurz, N; Laatiaoui, M; Lahiri, S; Lang, R; Lommel, B; Maiti, M; Miernik, K; Minami, S; Mistry, A; Mokry, C; Nitsche, H; Omtvedt, J P; Pang, G K; Papadakis, P; Renisch, D; Roberto, J; Rudolph, D; Runke, J; Rykaczewski, K P; Sarmiento, L G; Schädel, M; Schausten, B; Semchenkov, A; Shaughnessy, D A; Steinegger, P; Steiner, J; Tereshatov, E E; Thörle-Pospiech, P; Tinschert, K; Torres De Heidenreich, T; Trautmann, N; Türler, A; Uusitalo, J; Ward, D E; Wegrzecki, M; Wiehl, N; Van Cleve, S M; Yakusheva, V

    2014-05-02

    The superheavy element with atomic number Z=117 was produced as an evaporation residue in the (48)Ca+(249)Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-μs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope (294)117 and its decay products. A hitherto unknown α-decay branch in (270)Db (Z = 105) was observed, which populated the new isotope (266)Lr (Z = 103). The identification of the long-lived (T(1/2) = 1.0(-0.4)(+1.9) h) α-emitter (270)Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an "island of stability."

  10. Cathodic and anodic simultaneous electrolytic deposition to minimize copper and lead interferences on spectrophotometric determination of cadmium by the Malachite Green-iodide reaction

    International Nuclear Information System (INIS)

    Oliveira, Adriana Paiva de; Freschi, Gian Paulo Giovanni; Dakuzaku, Carolina Sinabucro; Moraes, Mercedes de; Crespi, Marisa Spirandeli; Gomes Neto, Jose de Anchieta

    2001-01-01

    Simultaneous electrolytic deposition is proposed for minimization of Cu 2+ and Pb 2+ interferences on automated determination of Cd 2+ by the Malachite Green-iodide reaction. During electrolysis of sample in a cell with two Pt electrodes and a medium adjusted to 5% (v/v) HNO 3 + 0.1% (v/v) H 2 SO 4 + 0.5 mol L -1 NaCl, Cu 2+ is deposited as Cu on the cathode, Pb 2+ is deposited as PbO 2 on the anode while Cd 2+ is kept in solution. With 60 s electrolysis time and 0.25 A current, Pb 2+ and Cu 2+ levels up to 50 and 250 mg L -1 respectively, can be tolerated without interference. With on-line extraction of Cd 2+ in anionic resin mini column, calibration graph in the 5.00 - 50.0 μg Cd L -1 range is obtained, corresponding to twenty measurements per hour, 0.7 mg Malachite Green and 500 mg Kl and 5 mL sample consumed per determination. Results of the determination of Cd in certified reference materials, vegetables and tap water were in agreement with certified values and with those obtained by GFAAS at 95% confidence level. The detection limit is 0.23 μg Cd L-1 and the RSD for typical samples containing 13.0 μg Cd L -1 was 3.85 % (n= 12). (author)

  11. Roads leading to roam. Role of triple fragmentation and of conical intersections in photochemical reactions: experiments and theory on methyl formate.

    Science.gov (United States)

    Tsai, Po-Yu; Chao, Meng-Hsuan; Kasai, Toshio; Lin, King-Chuen; Lombardi, Andrea; Palazzetti, Federico; Aquilanti, Vincenzo

    2014-02-21

    The exploration of alternative roads that open to molecules with sufficient energy to yield different products permits prediction and eventually control of the outcomes of chemical reactions. Advanced imaging techniques for monitoring laser-induced photodissociation are here combined with dynamical simulations, involving ample sets of classical trajectories generated on a quantum chemical potential energy surface. Methyl formate, HCOOCH3, is photodissociated at energies near the triple fragmentation threshold into H, CO and OCH3. Images of velocity and rotational distributions of CO exhibit signatures of alternative routes, such as those recently designated as transition-state vs. roaming-mediated. Furthermore, a demonstration of the triple fragmentation route is given, and also confirmed by H-atom product imaging and FTIR time-resolved spectra of the intermediate HCO radical. In addition, the relevance of nonadiabatic transitions promoted by a conical intersection is clarified by simulations as the privileged "reactivity funnel" of organic photochemistry, whereby the outcomes of molecular photoexcitation are delivered to electronic ground states.

  12. Free radical reaction pathway, thermohemistry of peracetic acid homolysis and its application for phenol degradation: spectroscopic sti=udy and quantum chemistry calculations

    NARCIS (Netherlands)

    Rokhina, E.V.; Makarova, K.; Golovina, E.A.; As, van H.; Virkutyte, J.

    2010-01-01

    The homolysis of peracetic acid (PAA) as a relevant source of free radicals (e.g., •OH) was studied in detail. Radicals formed as a result of chain radical reactions were detected with electron spin resonance and nuclear magnetic resonance spin trapping techniques and subsequently identified by

  13. Pathways and timescales of primary charge separation in the photosystem II reaction center as revealed by a simultaneous fit of time-resolved fluorescence and transient absorption

    NARCIS (Netherlands)

    Novoderezhkin, V.I.; Andrizhiyevskaya, E.G.; Dekker, J.P.; van Grondelle, R.

    2005-01-01

    We model the dynamics of energy transfer and primary charge separation in isolated photosystem II (PSII) reaction centers. Different exciton models with specific site energies of the six core pigments and two peripheral chlorophylls (Chls) in combination with different charge transfer schemes have

  14. Exploring possible reaction pathways for the o-atom transfer reactions to unsaturated substrates catalyzed by a [Ni-NO2 ] ↔ [Ni-NO] redox couple using DFT methods.

    Science.gov (United States)

    Tsipis, Athanassios C

    2017-07-15

    The (nitro)(N-methyldithiocarbamato)(trimethylphospane)nickel(II), [Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] complex catalyses efficiently the O-atom transfer reactions to CO and acetylene. Energetically feasible sequence of elementary steps involved in the catalytic cycle of the air oxidation of CO and acetylene are proposed promoted by the Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] ↔ Ni(NO 2 )(S 2 CNHMe)(PMe 3 ) redox couple using DFT methods both in vacuum and dichloromethane solutions. The catalytic air oxidation of HC≡CH involves formation of a five-member metallacycle intermediate, via a [3 + 2] cyclo-addition reaction of HC≡CH to the Ni-N = O moiety of the Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] complex, followed by a β H-atom migration toward the C α carbon atom of the coordinated acetylene and release of the oxidation product (ketene). The geometric and energetic reaction profile for the reversible [Ni( κN1-NO 2 )(S 2 CNHMe)(PMe 3 )] ⇌ [Ni( κO,O2-ONO)(S 2 CNHMe)(PMe 3 )] linkage isomerization has also been modeled by DFT calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  15. Avian Reovirus Protein p17 Functions as a Nucleoporin Tpr Suppressor Leading to Activation of p53, p21 and PTEN and Inactivation of PI3K/AKT/mTOR and ERK Signaling Pathways.

    Directory of Open Access Journals (Sweden)

    Wei-Ru Huang

    Full Text Available Avian reovirus (ARV protein p17 has been shown to regulate cell cycle and autophagy by activation of p53/PTEN pathway; nevertheless, it is still unclear how p53 and PTEN are activated by p17. Here, we report for the first time that p17 functions as a nucleoporin Tpr suppressor that leads to p53 nuclear accumulation and consequently activates p53, p21, and PTEN. The nuclear localization signal (119IAAKRGRQLD128 of p17 has been identified for Tpr binding. This study has shown that Tpr suppression occurs by p17 interacting with Tpr and by reducing the transcription level of Tpr, which together inhibit Tpr function. In addition to upregulation of PTEN by activation of p53 pathway, this study also suggests that ARV protein p17 acts as a positive regulator of PTEN. ARV p17 stabilizes PTEN by stimulating phosphorylation of cytoplasmic PTEN and by elevating Rak-PTEN association to prevent it from E3 ligase NEDD4-1 targeting. To activate PTEN, p17 is able to promote β-arrestin-mediated PTEN translocation from the cytoplasm to the plasma membrane via a Rock-1-dependent manner. The accumulation of p53 in the nucleus induces the PTEN- and p21-mediated downregulation of cyclin D1 and CDK4. Furthermore, Tpr and CDK4 knockdown increased virus production in contrast to depletion of p53, PTEN, and LC3 reducing virus yield. Taken together, our data suggest that p17-mediated Tpr suppression positively regulates p53, PTEN, and p21 and negatively regulates PI3K/AKT/mTOR and ERK signaling pathways, both of which are beneficial for virus replication.

  16. U12, a UDCA derivative, acts as an anti-hepatoma drug lead and inhibits the mTOR/S6K1 and cyclin/CDK complex pathways.

    Directory of Open Access Journals (Sweden)

    Yang Xu

    Full Text Available U12, one of 20 derivatives synthesized from ursodeoxycholic acid (UDCA, has been found to have anticancer effects in liver cancer cell lines (SMMC-7721 and HepG2 and to protect normal liver cells from deoxycholic acid (DCA damage (QSG-7701. Its anticancer mechanism was investigated using computer-aided network pharmacology and comparative proteomics. Results showed that its anti-malignancy activities were activated by mTOR/S6K1, cyclinD1/CDK2/4 and caspase-dependent apoptotic signaling pathways in hepatocellular carcinoma cells (HCC. The action of U12 may be similar to that of rapamycin. Animal testing confirmed that U12 exerted better anti-tumor activity than UDCA and had less severe side effects than fluorouracil (5-Fu. These observations indicate that U12 differs from UDCA and other derivatives and may be a suitable lead for the development of compounds useful in the treatment of HCC.

  17. Complete active space second order perturbation theory (CASPT2) study of N({sup 2}D) + H{sub 2}O reaction paths on D{sub 1} and D{sub 0} potential energy surfaces: Direct and roaming pathways

    Energy Technology Data Exchange (ETDEWEB)

    Isegawa, Miho; Liu, Fengyi [Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Kyoto 606-8103 (Japan); Maeda, Satoshi [Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan); Morokuma, Keiji, E-mail: morokuma@fukui.kyoto-u.ac.jp [Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Kyoto 606-8103 (Japan); Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322 (United States)

    2014-10-21

    We report reaction paths starting from N({sup 2}D) + H{sub 2}O for doublet spin states, D{sub 0} and D{sub 1}. The potential energy surfaces are explored in an automated fashion using the global reaction route mapping strategy. The critical points and reaction paths have been fully optimized at the complete active space second order perturbation theory level taking all valence electrons in the active space. In addition to direct dissociation pathways that would be dominant, three roaming processes, two roaming dissociation, and one roaming isomerization: (1) H{sub 2}ON → H–O(H)N → H–HON → NO({sup 2}Π) + H{sub 2}, (2) cis-HNOH → HNO–H → H–HNO → NO + H{sub 2}, (3) H{sub 2}NO → H–HNO → HNO–H → trans-HNOH, are confirmed on the D{sub 0} surface.

  18. 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.

  19. Hypoxia-inducible factor-1α mediates the toll-like receptor 4 signaling pathway leading to anti-tumor effects in human hepatocellular carcinoma cells under hypoxic conditions.

    Science.gov (United States)

    Zhang, Xiaoyu; Li, Shuchen; Li, Mingrong; Huang, Haiying; Li, Jingyuan; Zhou, Changwei

    2016-08-01

    Hypoxia-inducible factor-1α (HIF-1α) and toll-like receptor 4 (TLR4) are involved in numerous mechanisms of cancer biology, including cell proliferation and survival; however the interaction of the two factors under hypoxic conditions remains unclear. The present study investigated the in vitro mechanism that results in the suppression of tumor cell growth and cellular functions when HIF-1α is silenced. In the present study, the human hepatocellular carcinoma HepG2 cell line was transfected with short hairpin RNA (shRNA) against HIF-1α and cultured under hypoxic conditions (1% O 2 for 24 h). The expression of HIF-1α and various growth factors, including epidermal growth factor (EGF), hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2), were examined using quantitative polymerase chain reaction and immunoblotting. Tumor growth was measured using a Cell Counting Kit-8 assay and tumor activity was measured using tumor cell invasion and migration assays. Lipopolysaccharide and TAK-242 were used to activate and inhibit TLR4, respectively, to observe the role of TLR4 in the HIF-1α silenced tumor cells. The expression of TLR4 signaling pathway associates, including myeloid differentiation primary response gene 88 (MyD88), apoptosis signal-regulating kinase 1 (ASK1), p38 mitogen-activated protein kinases and HIF-1α, were analyzed by western blot assay. Under hypoxic conditions, silencing of HIF-1α expression suppressed tumor cell growth and regulated the expression of tumor growth-associated genes, including EGF, HGF, VEGF and FG2. Suppression of tumor cell invasion and migration was also observed in the HIF-1α silenced HepG2 cell line. In addition, TLR4 was identified to be involved in HIF-1α and MyD88 accumulation, and activation of ASK1 and p38 were demonstrated to be critical for TLR4-mediated HIF-1α pathway. In conclusion, silencing of HIF-1α expression may induce anti-tumor effects under hypoxic

  20. A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway.

    Science.gov (United States)

    Liu, Jinyong; Han, Mengwei; Wu, Dimao; Chen, Xi; Choe, Jong Kwon; Werth, Charles J; Strathmann, Timothy J

    2016-06-07

    Rapid reduction of aqueous ClO4(-) to Cl(-) by H2 has been realized by a heterogeneous Re(hoz)2-Pd/C catalyst integrating Re(O)(hoz)2Cl complex (hoz = oxazolinyl-phenolato bidentate ligand) and Pd nanoparticles on carbon support, but ClOx(-) intermediates formed during reactions with concentrated ClO4(-) promote irreversible Re complex decomposition and catalyst deactivation. The original catalyst design mimics the microbial ClO4(-) reductase, which integrates Mo(MGD)2 complex (MGD = molybdopterin guanine dinucleotide) for oxygen atom transfer (OAT). Perchlorate-reducing microorganisms employ a separate enzyme, chlorite dismutase, to prevent accumulation of the destructive ClO2(-) intermediate. The structural intricacy of MGD ligand and the two-enzyme mechanism for microbial ClO4(-) reduction inspired us to improve catalyst stability by rationally tuning Re ligand structure and adding a ClOx(-) scavenger. Two new Re complexes, Re(O)(htz)2Cl and Re(O)(hoz)(htz)Cl (htz = thiazolinyl-phenolato bidentate ligand), significantly mitigate Re complex decomposition by slightly lowering the OAT activity when immobilized in Pd/C. Further stability enhancement is then obtained by switching the nanoparticles from Pd to Rh, which exhibits high reactivity with ClOx(-) intermediates and thus prevents their deactivating reaction with the Re complex. Compared to Re(hoz)2-Pd/C, the new Re(hoz)(htz)-Rh/C catalyst exhibits similar ClO4(-) reduction activity but superior stability, evidenced by a decrease of Re leaching from 37% to 0.25% and stability of surface Re speciation following the treatment of a concentrated "challenge" solution containing 1000 ppm of ClO4(-). This work demonstrates the pivotal roles of coordination chemistry control and tuning of individual catalyst components for achieving both high activity and stability in environmental catalyst applications.

  1. Synthesized TiO{sub 2}/ZSM-5 composites used for the photocatalytic degradation of azo dye: Intermediates, reaction pathway, mechanism and bio-toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Kefu; Hu, Xin-Yan [College of the Environment and Ecology, Xiamen University, Xiamen (China); Chen, Bor-Yann; Hsueh, Chung-Chuan [Department of Chemical and Materials Engineering, National I-Lan University, I-Lan, Taiwan (China); Zhang, Qian [Department of Environmental Engineering, National Taiwan University, Taipei, Taiwan (China); Wang, Jiajie; Lin, Yu-Jung [College of the Environment and Ecology, Xiamen University, Xiamen (China); Chang, Chang-Tang, E-mail: ctchang73222@gmail.com [Department of Environmental Engineering, National I-Lan University, I-Lan, Taiwan (China)

    2016-10-15

    Highlights: • The major photo-catalytic degradation pathway of azo-dye was elaborated according to the identification of by-products from GC–MS and IC analysis. • Comparative assessment on characteristics of abiotic and biotic dye decolorization was analyzed. • EDTA (hole scavengers) and t-BuOH (radical scavengers) were used to determine the main active oxidative species in the system. • The toxicity effects of degradation intermediates of Reactive Black 5 (RB5) on the cellular respiratory activity were assessed. - Abstract: In this study, a one-step solid dispersion method was used to synthesize titanium dioxide (TiO{sub 2})/Zeolite Socony Mobil-5 (ZSM-5) composites with substantially reduced time and energy consumption. A degradation efficiency of more than 95% was achieved within 10 min using 50% PTZ (synthesized TiO{sub 2}/ZSM-5 composites with TiO{sub 2} contents of 50 wt% loaded on ZSM-5) at pH 7 and 25 °C. The possible degradation pathway of azo-dye Reactive Black 5 (RB5) was investigated using gas chromatography–mass spectrometry and ion chromatography (IC). The bonds between the N atoms and naphthalene groups are likely attacked first and cleaved by hydroxyl radicals, ultimately resulting in the decolorization and mineralization of the azo dye. A comparative assessment of the characteristics of abiotic and biotic dye decolorization was completed. In addition, the toxicity effects of the degradation intermediates of azo-dye RB5 on cellular respiratory activity were analyzed. The bio-toxicity results showed that the decay rate constants of CO{sub 2} production from the azo-dye RB5 samples at different degradation times increased initially and subsequently decreased, indicating that intermediates of higher toxicity could adhere to the catalyst surface and gradually destroyed by further photocatalytic oxidation. Additionally, EDTA (hole scavengers) and t-BuOH (radical scavengers) were used to detect the main active oxidative species in the system

  2. A Chemical Activation Study of the Unimolecular Reactions of CD3CD2CHCl2 and CHCl2CHCl2 with Analysis of the 1,1-HCl Elimination Pathway.

    Science.gov (United States)

    Larkin, Allie C; Nestler, Matthew J; Smith, Caleb A; Heard, George L; Setser, Donald W; Holmes, Bert E

    2016-10-03

    Chemically activated C2D5CHCl2 molecules were generated with 88 kcal mol-1 of vibrational energy by the recombination of C2D5 and CHCl2 radicals in a room temperature bath gas. The competing 2,1-DCl and 1,1-HCl unimolecular reactions were identified by the observation of the CD3CD=CHCl and CD3CD=CDCl products. The initial CD3CD2C-Cl carbene product from 1,1-HCl elimination rearranges to CD3CD=CDCl under the conditions of the experiments. The experimental rate constants were 2.7 x107 and 0.47 x107 s-1 for 2,1-DCl and 1,1-HCl elimination reactions, respectively, which corresponds to branching fractions of 0.84 and 0.16. The experimental rate constants were compared to calculated statistical rate constants to assign threshold energies of 54 and ≈ 66 kcal mol-1 for the 1,2-DCl and 1,1-HCl reactions, respectively. The statistical rate constants were obtained from models developed from electronic-structure calculations for the molecule and its transition states. The rate constant (5.3 x 107 s-1) for the unimolecular decomposition of CHCl2CHCl2 molecules formed with 82 kcal mol-1 of vibrational energy by the recombination of CHCl2 radicals also is reported. Based upon the magnitude of the calculated rate constant, 1,1-HCl elimination must contribute less than 15% to the reaction; 1,2-HCl elimination is the major reaction and the threshold energy is 59 kcal mol-1. Calculations also were done to analyze previously published rate constants for chemically activated CD2Cl-CHCl2 molecules with 86 kcal mol-1 of energy in order to obtain a better overall description of the nature of the 1,1-HCl pathway for 1,1-dichloroalkanes. The interplay of the threshold energies for the 2,1-HCl and 1,1-HCl reactions and the available energy determines the product branching fractions for individual molecules. The unusual nature of the transition state for 1,1-HCl elimination is discussed.

  3. Coagulation factor VIIa-mediated protease-activated receptor 2 activation leads to β-catenin accumulation via the AKT/GSK3β pathway and contributes to breast cancer progression.

    Science.gov (United States)

    Roy, Abhishek; Ansari, Shabbir A; Das, Kaushik; Prasad, Ramesh; Bhattacharya, Anindita; Mallik, Suman; Mukherjee, Ashis; Sen, Prosenjit

    2017-08-18

    Cell migration and invasion are very characteristic features of cancer cells that promote metastasis, which is one of the most common causes of mortality among cancer patients. Emerging evidence has shown that coagulation factors can directly mediate cancer-associated complications either by enhancing thrombus formation or by initiating various signaling events leading to metastatic cancer progression. It is well established that, apart from its distinct role in blood coagulation, coagulation factor FVIIa enhances aggressive behaviors of breast cancer cells, but the underlying signaling mechanisms still remain elusive. To this end, we investigated FVIIa's role in the migration and invasiveness of the breast cancer cell line MDA-MB-231. Consistent with previous observations, we observed that FVIIa increased the migratory and invasive potential of these cells. We also provide molecular evidence that protease-activated receptor 2 activation followed by PI3K-AKT activation and GSK3β inactivation is involved in these processes and that β-catenin, a well known tumor-regulatory protein, contributes to this signaling pathway. The pivotal role of β-catenin was further indicated by the up-regulation of its downstream targets cyclin D1, c-Myc, COX-2, MMP-7, MMP-14, and Claudin-1. β-Catenin knockdown almost completely attenuated the FVIIa-induced enhancement of breast cancer migration and invasion. These findings provide a new perspective to counteract the invasive behavior of breast cancer, indicating that blocking PI3K-AKT pathway-dependent β-catenin accumulation may represent a potential therapeutic approach to control breast cancer. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: insights into the major reaction pathways.

    Science.gov (United States)

    Xing, Shiyou; Lv, Pengmei; Wang, Jiayan; Fu, Junying; Fan, Pei; Yang, Lingmei; Yang, Gaixiu; Yuan, Zhenhong; Chen, Yong

    2017-01-25

    For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C 6 -C 8 olefins over the catalysts' Brønsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C 6 -C 8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Brønsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.

  5. Lead poisoning

    Science.gov (United States)

    ... drinking water in homes containing pipes that were connected with lead solder . Although new building codes require ... lead in their bodies when they put lead objects in their mouths, especially if they swallow those ...

  6. Lead Poisoning

    Science.gov (United States)

    Lead is a metal that occurs naturally in the earth's crust. Lead can be found in all parts of our ... from human activities such as mining and manufacturing. Lead used to be in paint; older houses may ...

  7. Reaction pathways of proton transfer in hydrogen-bonded phenol-carboxylate complexes explored by combined UV-vis and NMR spectroscopy.

    Science.gov (United States)

    Koeppe, Benjamin; Tolstoy, Peter M; Limbach, Hans-Heinrich

    2011-05-25

    Combined low-temperature NMR/UV-vis spectroscopy (UVNMR), where optical and NMR spectra are measured in the NMR spectrometer under the same conditions, has been set up and applied to the study of H-bonded anions A··H··X(-) (AH = 1-(13)C-2-chloro-4-nitrophenol, X(-) = 15 carboxylic acid anions, 5 phenolates, Cl(-), Br(-), I(-), and BF(4)(-)). In this series, H is shifted from A to X, modeling the proton-transfer pathway. The (1)H and (13)C chemical shifts and the H/D isotope effects on the latter provide information about averaged H-bond geometries. At the same time, red shifts of the π-π* UV-vis absorption bands are observed which correlate with the averaged H-bond geometries. However, on the UV-vis time scale, different tautomeric states and solvent configurations are in slow exchange. The combined data sets indicate that the proton transfer starts with a H-bond compression and a displacement of the proton toward the H-bond center, involving single-well configurations A-H···X(-). In the strong H-bond regime, coexisting tautomers A··H···X(-) and A(-)···H··X are observed by UV. Their geometries and statistical weights change continuously when the basicity of X(-) is increased. Finally, again a series of single-well structures of the type A(-)···H-X is observed. Interestingly, the UV-vis absorption bands are broadened inhomogeneously because of a distribution of H-bond geometries arising from different solvent configurations.

  8. Pathways and Mechanisms Underlying the Photophysics and Photochemistry of Riboflavin induced cornea crosslinking

    DEFF Research Database (Denmark)

    Breitenbach, Thomas; Ogilby, Peter Remsen

    In this talk, we will describe general pathways involved in the photophysics of a photosensitized process, which can lead to crosslinking due to light excitation of Riboflavin in the cornea. Furthermore, we will elucidate different aspects of reactions that can produce crosslinks, with respect...

  9. Conditions for extinction events in chemical reaction networks with discrete state spaces.

    Science.gov (United States)

    Johnston, Matthew D; Anderson, David F; Craciun, Gheorghe; Brijder, Robert

    2018-05-01

    We study chemical reaction networks with discrete state spaces and present sufficient conditions on the structure of the network that guarantee the system exhibits an extinction event. The conditions we derive involve creating a modified chemical reaction network called a domination-expanded reaction network and then checking properties of this network. Unlike previous results, our analysis allows algorithmic implementation via systems of equalities and inequalities and suggests sequences of reactions which may lead to extinction events. We apply the results to several networks including an EnvZ-OmpR signaling pathway in Escherichia coli.

  10. Lead poisoning

    Energy Technology Data Exchange (ETDEWEB)

    Beijers, J A

    1952-01-01

    Three cases of acute lead poisoning of cattle herds via ingestion are reported, and reference is made to several other incidents of lead in both humans and animals. The quantity of lead which was found in the livers of the dead cows varied from 6.5 to 19 mg/kg, while 1160 mg/kg of lead in the liver was found for a young cow which was poisoned experimentally with 5 gms of lead acetate per day; hence, there appears to be great variability in the amounts deposited that can lead to intoxication and death. No evidence was found for a lead seam around the teeth, prophyrinuria, or basophil granules in the erythrocytes during acute or chronic lead poisoning of cattle or horses examined. Reference is made to attempts of finding the boundary line between increased lead absorption and lead intoxication in humans, and an examination of 60 laborers in an offset-printing office containing a great deal of inhalable lead (0.16 to 1.9 mg/cu m air) is reviewed. Physical deviation, basophylic granulation of erythrocytes, increased lead content of the urine, and porphyrinuria only indicate an increased absorption of lead; the use of the term intoxication is justified if, in addition, there are complaints of lack of appetite, constipation, fatigue, abdominal pain, and emaciation.

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

    Science.gov (United States)

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

    2016-08-01

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

  12. Lead Toxicity

    Science.gov (United States)

    ... o Do not use glazed ceramics, home remedies, cosmetics, or leaded-crystal glassware unless you know that they are lead safe. o If you live near an industry, mine, or waste site that may have contaminated ...

  13. Relational Leading

    DEFF Research Database (Denmark)

    Larsen, Mette Vinther; Rasmussen, Jørgen Gulddahl

    2015-01-01

    This first chapter presents the exploratory and curious approach to leading as relational processes – an approach that pervades the entire book. We explore leading from a perspective that emphasises the unpredictable challenges and triviality of everyday life, which we consider an interesting......, relevant and realistic way to examine leading. The chapter brings up a number of concepts and contexts as formulated by researchers within the field, and in this way seeks to construct a first understanding of relational leading....

  14. Probabilistic pathway construction.

    Science.gov (United States)

    Yousofshahi, Mona; Lee, Kyongbum; Hassoun, Soha

    2011-07-01

    Expression of novel synthesis pathways in host organisms amenable to genetic manipulations has emerged as an attractive metabolic engineering strategy to overproduce natural products, biofuels, biopolymers and other commercially useful metabolites. We present a pathway construction algorithm for identifying viable synthesis pathways compatible with balanced cell growth. Rather than exhaustive exploration, we investigate probabilistic selection of reactions to construct the pathways. Three different selection schemes are investigated for the selection of reactions: high metabolite connectivity, low connectivity and uniformly random. For all case studies, which involved a diverse set of target metabolites, the uniformly random selection scheme resulted in the highest average maximum yield. When compared to an exhaustive search enumerating all possible reaction routes, our probabilistic algorithm returned nearly identical distributions of yields, while requiring far less computing time (minutes vs. years). The pathways identified by our algorithm have previously been confirmed in the literature as viable, high-yield synthesis routes. Prospectively, our algorithm could facilitate the design of novel, non-native synthesis routes by efficiently exploring the diversity of biochemical transformations in nature. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Lead Test

    Science.gov (United States)

    ... to do renovation and repair projects using lead-safe work practices to avoid creating more lead dust or ... in a dangerous area? Yes. If you are working in a potentially harmful environment with exposure to lead dust or fumes: Wash ...

  16. Theoretical investigation of the gas-phase reactions of CrO(+) with ethylene.

    Science.gov (United States)

    Scupp, Thomas M; Dudley, Timothy J

    2010-01-21

    The potential energy surfaces associated with the reactions of chromium oxide cation (CrO(+)) with ethylene have been characterized using density functional, coupled-cluster, and multireference methods. Our calculations show that the most probable reaction involves the formation of acetaldehyde and Cr(+) via a hydride transfer involving the metal center. Our calculations support previous experimental hypotheses that a four-membered ring intermediate plays an important role in the reactivity of the system. We have also characterized a number of viable reaction pathways that lead to other products, including ethylene oxide. Due to the experimental observation that CrO(+) can activate carbon-carbon bonds, a reaction pathway involving C-C bond cleavage has also been characterized. Since many of the reactions involve a change in the spin state in going from reactants to products, locations of these spin surface crossings are presented and discussed. The applicability of methods based on Hartree-Fock orbitals is also discussed.

  17. Impairment of the Ubiquitin-Proteasome Pathway by Methyl N-(6-Phenylsulfanyl-1H-benzimidazol-2-yl)carbamate Leads to a Potent Cytotoxic Effect in Tumor Cells

    Science.gov (United States)

    Dogra, Nilambra; Mukhopadhyay, Tapas

    2012-01-01

    In recent years, there has been a great deal of interest in proteasome inhibitors as a novel class of anticancer drugs. We report that fenbendazole (FZ) (methyl N-(6-phenylsulfanyl-1H-benzimidazol-2-yl)carbamate) exhibits a potent growth-inhibitory activity against cancer cell lines but not normal cells. We show here, using fluorogenic substrates, that FZ treatment leads to the inhibition of proteasomal activity in the cells. Succinyl-Leu-Leu-Val-Tyr-methylcoumarinamide (MCA), benzyloxycarbonyl-Leu-Leu-Glu-7-amido-4-MCA, and t-butoxycarbonyl-Gln-Ala-Arg-7-amido-4-MCA fluorescent derivatives were used to assess chymotrypsin-like, post-glutamyl peptidyl-hydrolyzing, and trypsin-like protease activities, respectively. Non-small cell lung cancer cells transiently transfected with an expression plasmid encoding pd1EGFP and treated with FZ showed an accumulation of the green fluorescent protein in the cells due to an increase in its half-life. A number of apoptosis regulatory proteins that are normally degraded by the ubiquitin-proteasome pathway like cyclins, p53, and IκBα were found to be accumulated in FZ-treated cells. In addition, FZ induced distinct ER stress-associated genes like GRP78, GADD153, ATF3, IRE1α, and NOXA in these cells. Thus, treatment of human NSCLC cells with fenbendazole induced endoplasmic reticulum stress, reactive oxygen species production, decreased mitochondrial membrane potential, and cytochrome c release that eventually led to cancer cell death. This is the first report to demonstrate the inhibition of proteasome function and induction of endoplasmic reticulum stress/reactive oxygen species-dependent apoptosis in human lung cancer cell lines by fenbendazole, which may represent a new class of anticancer agents showing selective toxicity against cancer cells. PMID:22745125

  18. Simulation studies in biochemical signaling and enzyme reactions

    Science.gov (United States)

    Nelatury, Sudarshan R.; Vagula, Mary C.

    2014-06-01

    Biochemical pathways characterize various biochemical reaction schemes that involve a set of species and the manner in which they are connected. Determination of schematics that represent these pathways is an important task in understanding metabolism and signal transduction. Examples of these Pathways are: DNA and protein synthesis, and production of several macro-molecules essential for cell survival. A sustained feedback mechanism arises in gene expression and production of mRNA that lead to protein synthesis if the protein so synthesized serves as a transcription factor and becomes a repressor of the gene expression. The cellular regulations are carried out through biochemical networks consisting of reactions and regulatory proteins. Systems biology is a relatively new area that attempts to describe the biochemical pathways analytically and develop reliable mathematical models for the pathways. A complete understanding of chemical reaction kinetics is prohibitively hard thanks to the nonlinear and highly complex mechanisms that regulate protein formation, but attempting to numerically solve some of the governing differential equations seems to offer significant insight about their biochemical picture. To validate these models, one can perform simple experiments in the lab. This paper introduces fundamental ideas in biochemical signaling and attempts to take first steps into the understanding of biochemical oscillations. Initially, the two-pool model of calcium is used to describe the dynamics behind the oscillations. Later we present some elementary results showing biochemical oscillations arising from solving differential equations of Elowitz and Leibler using MATLAB software.

  19. Overcoming Short-Circuit in Lead-Free CH3NH3SnI3 Perovskite Solar Cells via Kinetically Controlled Gas-Solid Reaction Film Fabrication Process.

    Science.gov (United States)

    Yokoyama, Takamichi; Cao, Duyen H; Stoumpos, Constantinos C; Song, Tze-Bin; Sato, Yoshiharu; Aramaki, Shinji; Kanatzidis, Mercouri G

    2016-03-03

    The development of Sn-based perovskite solar cells has been challenging because devices often show short-circuit behavior due to poor morphologies and undesired electrical properties of the thin films. A low-temperature vapor-assisted solution process (LT-VASP) has been employed as a novel kinetically controlled gas-solid reaction film fabrication method to prepare lead-free CH3NH3SnI3 thin films. We show that the solid SnI2 substrate temperature is the key parameter in achieving perovskite films with high surface coverage and excellent uniformity. The resulting high-quality CH3NH3SnI3 films allow the successful fabrication of solar cells with drastically improved reproducibility, reaching an efficiency of 1.86%. Furthermore, our Kelvin probe studies show the VASP films have a doping level lower than that of films prepared from the conventional one-step method, effectively lowering the film conductivity. Above all, with (LT)-VASP, the short-circuit behavior often obtained from the conventional one-step-fabricated Sn-based perovskite devices has been overcome. This study facilitates the path to more successful Sn-perovskite photovoltaic research.

  20. Crystallization Pathways in Biomineralization

    Science.gov (United States)

    Weiner, Steve; Addadi, Lia

    2011-08-01

    A crystallization pathway describes the movement of ions from their source to the final product. Cells are intimately involved in biological crystallization pathways. In many pathways the cells utilize a unique strategy: They temporarily concentrate ions in intracellular membrane-bound vesicles in the form of a highly disordered solid phase. This phase is then transported to the final mineralization site, where it is destabilized and crystallizes. We present four case studies, each of which demonstrates specific aspects of biological crystallization pathways: seawater uptake by foraminifera, calcite spicule formation by sea urchin larvae, goethite formation in the teeth of limpets, and guanine crystal formation in fish skin and spider cuticles. Three representative crystallization pathways are described, and aspects of the different stages of crystallization are discussed. An in-depth understanding of these complex processes can lead to new ideas for synthetic crystallization processes of interest to materials science.

  1. Chemical burn or reaction

    Science.gov (United States)

    Chemicals that touch skin can lead to a reaction on the skin, throughout the body, or both. ... leave the person alone and watch carefully for reactions affecting the entire body. Note: If a chemical gets into the eyes, the eyes should be ...

  2. Decrypting Cryptochrome: Revealing the Molecular Identity of the Photoactivation Reaction

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Domratcheva, Tatiana; Shahi, Abdul Rehaman Moughal

    2012-01-01

    of cryptochrome must arise from the photoactivation reaction occurring in the protein: exposure to blue light results in electron transfer to a flavin pigment co-factor, leading to formation of an electron spin-entangled pair of radicals. Theoretical and experimental studies established long ago that such radical...... pairs, indeed, can act as a magnetic compass. The photo-reaction pathway in cryptochrome is not fully resolved yet. We employ ab initio quantum chemistry and classical all-atom MD simulations for Arabidopsis thaliana cryptochrome to determine how the radical pair is formed, becomes stabilized through...

  3. Leading Democratically

    Science.gov (United States)

    Brookfield, Stephen

    2010-01-01

    Democracy is the most venerated of American ideas, the one for which wars are fought and people die. So most people would probably agree that leaders should be able to lead well in a democratic society. Yet, genuinely democratic leadership is a relative rarity. Leading democratically means viewing leadership as a function or process, rather than…

  4. Reaction chemistry in rechargeable Li-O2 batteries.

    Science.gov (United States)

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

    2017-05-22

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

  5. Prediction of novel synthetic pathways for the production of desired chemicals

    Directory of Open Access Journals (Sweden)

    Park Jin

    2010-03-01

    Full Text Available Abstract Background There have been several methods developed for the prediction of synthetic metabolic pathways leading to the production of desired chemicals. In these approaches, novel pathways were predicted based on chemical structure changes, enzymatic information, and/or reaction mechanisms, but the approaches generating a huge number of predicted results are difficult to be applied to real experiments. Also, some of these methods focus on specific pathways, and thus are limited to expansion to the whole metabolism. Results In the present study, we propose a system framework employing a retrosynthesis model with a prioritization scoring algorithm. This new strategy allows deducing the novel promising pathways for the synthesis of a desired chemical together with information on enzymes involved based on structural changes and reaction mechanisms present in the system database. The prioritization scoring algorithm employing Tanimoto coefficient and group contribution method allows examination of structurally qualified pathways to recognize which pathway is more appropriate. In addition, new concepts of binding site covalence, estimation of pathway distance and organism specificity were taken into account to identify the best synthetic pathway. Parameters of these factors can be evolutionarily optimized when a newly proven synthetic pathway is registered. As the proofs of concept, the novel synthetic pathways for the production of isobutanol, 3-hydroxypropionate, and butyryl-CoA were predicted. The prediction shows a high reliability, in which experimentally verified synthetic pathways were listed within the top 0.089% of the identified pathway candidates. Conclusions It is expected that the system framework developed in this study would be useful for the in silico design of novel metabolic pathways to be employed for the efficient production of chemicals, fuels and materials.

  6. Leading change.

    Science.gov (United States)

    2017-02-27

    In response to feedback from nursing, midwifery and other care staff who wanted to understand better how the Leading Change, Adding Value framework applies to them, NHS England has updated its webpage to include practice examples.

  7. Surface-Activated Coupling Reactions Confined on a Surface.

    Science.gov (United States)

    Dong, Lei; Liu, Pei Nian; Lin, Nian

    2015-10-20

    -functional theory (DFT) transition-state calculations have been used to shed light on reaction mechanisms and to unravel the trends of different surface materials. In this Account, we discuss recent progress made in two widely studied surface-confined coupling reactions, aryl-aryl (Ullmann-type) coupling and alkyne-alkyne (Glaser-type) coupling, and focus on surface activation effects. Combined experimental and theoretical studies on the same reactions taking place on different metal surfaces have clearly demonstrated that different surfaces not only reduce the reaction barrier differently and render different reaction pathways but also control the morphology of the reaction products and, to some degree, select the reaction products. We end the Account with a list of questions to be addressed in the future. Satisfactorily answering these questions may lead to using the surface-confined coupling reactions to synthesize predefined products with high yield.

  8. Secondary lead production

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, R.G.

    1990-10-16

    This invention is concerned with the efficient recovery of soft lead from the paste component of used automobile lead-acid storage batteries. According to the invention, a scrap which contains lead oxide, lead sulfate, and antimony in an oxidized state is processed in the following steps to recover lead. A refractory lined reaction vessel is continuously charged with the scrap, along with a reductant effective for reducing lead oxide. The charged material is melted and agitated by means of a submerged lance at 900-1150{degree}C whereby some of the lead oxide of the scrap is reduced to form molten lead. A slag layer is then formed above the molten lead, and an amount of lead oxide is maintained in the slag layer. The molten lead, now containing under 0.5 wt % of antimony, is removed, and the antimony oxide in the scrap is concentrated as oxide in the slag layer. Preferred embodiments of the invention result in the production, in a single step, of a soft lead substantially free of antimony. The slag may be subsequently treated to reduce the antimony oxide and produce a valuable antimony-lead product. Further advantages of the process are that a wet battery paste may be used as the feed without prior drying, and the process can be conducted at a temperature 100-150{degree}C lower than in previously known methods. In addition, a smaller reactor can be employed which reduces both capital cost and fuel costs. The process of the invention is illustrated by descriptions of pilot plant tests. 1 fig.

  9. Chemical reactions confined within carbon nanotubes.

    Science.gov (United States)

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N

    2016-08-22

    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors.

  10. A Networks Approach to Modeling Enzymatic Reactions.

    Science.gov (United States)

    Imhof, P

    2016-01-01

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

  11. Pyrite formation and mineral transformation pathways upon sulfidation of ferric hydroxides depend on mineral type and sulfide concentration

    NARCIS (Netherlands)

    Peiffer, Stefan; Behrends, Thilo; Hellige, Katrin; Larese-Casanova, Philip; Wan, Moli; Pollok, Kilian

    2015-01-01

    The reaction of ferric (hydr)oxides with dissolved sulfide does not lead to the instantaneous production of thermodynamically stable products but can induce a variety of mineral transformations including the formation of metastable intermediates. The importance of the various transformation pathways

  12. Wnt-11 signaling leads to down-regulation of the Wnt/β-catenin, JNK/AP-1 and NF-κB pathways and promotes viability in the CHO-K1 cells

    International Nuclear Information System (INIS)

    Railo, Antti; Nagy, Irina I.; Kilpelaeinen, Pekka; Vainio, Seppo

    2008-01-01

    The Wnt family of glycoprotein growth factors controls a number of central cellular processes such as proliferation, differentiation and ageing. All the Wnt proteins analyzed so far either activate or inhibit the canonical β-catenin signaling pathway that regulates transcription of the target genes. In addition, some of them activate noncanonical signaling pathways that involve components such as the JNK, heterotrimeric G proteins, protein kinase C, and calmodulin-dependent protein kinase II, although the precise signaling mechanisms are only just beginning to be revealed. We demonstrate here that Wnt-11 signaling is sufficient to inhibit not only the canonical β-catenin mediated Wnt signaling but also JNK/AP-1 and NF-κB signaling in the CHO cells, thus serving as a noncanonical Wnt ligand in this system. Inhibition of the JNK/AP-1 pathway is mediated in part by the MAPK kinase MKK4 and Akt. Moreover, protein kinase C is involved in the regulation of JNK/AP-1 by Wnt-11, but not of the NF-κB pathway. Consistent with the central role of Akt, JNK and NF-κB in cell survival and stress responses, Wnt-11 signaling promotes cell viability. Hence Wnt-11 is involved in coordination of key signaling pathways

  13. The Reactome pathway knowledgebase.

    Science.gov (United States)

    Croft, David; Mundo, Antonio Fabregat; Haw, Robin; Milacic, Marija; Weiser, Joel; Wu, Guanming; Caudy, Michael; Garapati, Phani; Gillespie, Marc; Kamdar, Maulik R; Jassal, Bijay; Jupe, Steven; Matthews, Lisa; May, Bruce; Palatnik, Stanislav; Rothfels, Karen; Shamovsky, Veronica; Song, Heeyeon; Williams, Mark; Birney, Ewan; Hermjakob, Henning; Stein, Lincoln; D'Eustachio, Peter

    2014-01-01

    Reactome (http://www.reactome.org) is a manually curated open-source open-data resource of human pathways and reactions. The current version 46 describes 7088 human proteins (34% of the predicted human proteome), participating in 6744 reactions based on data extracted from 15 107 research publications with PubMed links. The Reactome Web site and analysis tool set have been completely redesigned to increase speed, flexibility and user friendliness. The data model has been extended to support annotation of disease processes due to infectious agents and to mutation.

  14. Ecotoxicology: Lead

    Science.gov (United States)

    Scheuhammer, A.M.; Beyer, W.N.; Schmitt, C.J.; Jorgensen, Sven Erik; Fath, Brian D.

    2008-01-01

    Lead (Pb) is a naturally occurring metallic element; trace concentrations are found in all environmental media and in all living things. However, certain human activities, especially base metal mining and smelting; combustion of leaded gasoline; the use of Pb in hunting, target shooting, and recreational angling; the use of Pb-based paints; and the uncontrolled disposal of Pb-containing products such as old vehicle batteries and electronic devices have resulted in increased environmental levels of Pb, and have created risks for Pb exposure and toxicity in invertebrates, fish, and wildlife in some ecosystems.

  15. Remediation of lead contaminated soil

    International Nuclear Information System (INIS)

    Urban, W.; Krishnamurthy, S.

    1992-01-01

    Lead contaminated soil in urban area is of major concern because of the potential health risk to children. Many studies have established a direct correlation between lead in soil and elevated blood lead levels in children. In Minneapolis, Minnesota, Mielke et al. (1983) reported that 50% of the Hmong children with lead poisioning were in areas where soil lead levels were between 500 and 1000 micrograms per gram (ug/g), and 40% of the children suffering from lead poisioning lived in areas where soil lead levels exceeded 1000 ug/g. In urban areas, lead pollution in soil has come from many different sources. The sources include lead paint, lead batteries and automobile exhaust. Olson and Skogerbee (1975) found the following lead compounds in soils where the primary source of pollution was from automobiles: lead sulfate, lead oxide, lead dioxide, lead sulfide, and metallic lead. The primary form of lead found was lead sulfate. Lead sulfate, lead tetraoxide, white lead, and other forms of lead have been used in the manufacture of paints for houses. At present, two remediation techniques, solidification and Bureau of Mines fluosilicic acid leaching, are available for lead-contaminated sites. The objective of the present investigation at the Risk Reduction Engineering Laboratory (RREL), Edison, was to try to solubilize the lead species by appropriate reagents and then recover the contaminants by precipitation as lead sulfate, using environmentally acceptable methods. The apparatus used for mixing was a LabMaster mixer, with variable speed and high-shear impeller. Previous work had used nitric acid for dissolving metallic lead. Owing to the environmental concerns, it was decided to use acetic acid in the presence of oxygen. The theoretical justification for this approach is the favorable redox potential for the reaction between metallic lead, acetic acid, and gaseous oxygen

  16. Leading men

    DEFF Research Database (Denmark)

    Bekker-Nielsen, Tønnes

    2016-01-01

    Through a systematic comparison of c. 50 careers leading to the koinarchate or high priesthood of Asia, Bithynia, Galatia, Lycia, Macedonia and coastal Pontus, as described in funeral or honorary inscriptions of individual koinarchs, it is possible to identify common denominators but also disting...

  17. Scoring systems used for the interpretation and reporting of multiparametric MRI for prostate cancer detection, localization, and characterization: Could standardization lead to improved utilization of imaging within the diagnostic pathway?

    NARCIS (Netherlands)

    Dickinson, L.; Ahmed, H.U.; Allen, C.; Barentsz, J.O.; Carey, B.; Futterer, J.J.; Heijmink, S.W.T.P.J.; Hoskin, P.; Kirkham, A.P.; Padhani, A.R.; Persad, R.; Puech, P.; Punwani, S.; Sohaib, A.; Tombal, B.; Villers, A.; Emberton, M.

    2013-01-01

    Multiparametric magnetic resonance imaging (mpMRI) is increasingly being used earlier in the prostate cancer diagnostic pathway in order to detect and localize disease. Its results can be used to help decide on the indication, type, and localization of a prostate biopsy for cancer diagnosis. In

  18. Measurement of double differential cross sections for light charged particles production in neutron induced reaction at 62.7 MeV on lead target; Mesures des sections efficaces doublement differentielles de production de particules chargees legeres lors de reactions induites par neutrons de 62.7 MeV sur cible de plomb

    Energy Technology Data Exchange (ETDEWEB)

    Kerveno, M

    2000-09-27

    In order to develop new options for nuclear waste management, studies are carrying out on the perfecting of hybrid systems (sub-critical reactor driven by accelerator). This thesis work takes place more precisely in the framework of nuclear data linked to hybrid systems development. Increasing the upper limit energy value (from 20 to 150 MeV) of data bases supposes that theoretical codes could have sufficient predictive power in this energy range. Thus it's necessary to measure new cross sections to constrain these codes. The experiment, performed at Louvain-la-Neuve Cyclotron, aims to determine the double differential cross sections for light charged particles production in neutron induced reactions at 62.7 MeV on natural lead target. The detection device consists of 6 NE102-CsI telescopes. Time of flight measurements are used to reconstruct the neutron energy spectra. The general framework (hybrid systems and associated nuclear data problematic) in which this work takes place is presented in a first part. The experimental set up used for our measurements is described in a second part. The three following parts are dedicated to the data analysis and double differential cross sections extraction. The particle discrimination, the energy calibration of detectors as the different corrections applied to the experimental spectra are related in details. And finally a comparative study between our experimental results and some theoretical predictions is presented. (author)

  19. Measurement of double differential cross sections for light charged particles production in neutron induced reaction at 62.7 MeV on lead target; Mesures des sections efficaces doublement differentielles de production de particules chargees legeres lors de reactions induites par neutrons de 62.7 MeV sur cible de plomb

    Energy Technology Data Exchange (ETDEWEB)

    Kerveno, M

    2000-09-27

    In order to develop new options for nuclear waste management, studies are carrying out on the perfecting of hybrid systems (sub-critical reactor driven by accelerator). This thesis work takes place more precisely in the framework of nuclear data linked to hybrid systems development. Increasing the upper limit energy value (from 20 to 150 MeV) of data bases supposes that theoretical codes could have sufficient predictive power in this energy range. Thus it's necessary to measure new cross sections to constrain these codes. The experiment, performed at Louvain-la-Neuve Cyclotron, aims to determine the double differential cross sections for light charged particles production in neutron induced reactions at 62.7 MeV on natural lead target. The detection device consists of 6 NE102-CsI telescopes. Time of flight measurements are used to reconstruct the neutron energy spectra. The general framework (hybrid systems and associated nuclear data problematic) in which this work takes place is presented in a first part. The experimental set up used for our measurements is described in a second part. The three following parts are dedicated to the data analysis and double differential cross sections extraction. The particle discrimination, the energy calibration of detectors as the different corrections applied to the experimental spectra are related in details. And finally a comparative study between our experimental results and some theoretical predictions is presented. (author)

  20. Benzo[a]pyrene affects Jurkat T cells in the activated state via the antioxidant response element dependent Nrf2 pathway leading to decreased IL-2 secretion and redirecting glutamine metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Murugaiyan, Jayaseelan; Rockstroh, Maxie; Wagner, Juliane [Department of Proteomics, Helmholtz-Centre for Environmental Research — UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Baumann, Sven [Department of Metabolomics, Helmholtz-Centre for Environmental Research — UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Schorsch, Katrin [Department of Proteomics, Helmholtz-Centre for Environmental Research — UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Trump, Saskia; Lehmann, Irina [Department of Environmental Immunology, Helmholtz-Centre for Environmental Research — UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Bergen, Martin von [Department of Proteomics, Helmholtz-Centre for Environmental Research — UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Department of Environmental Immunology, Helmholtz-Centre for Environmental Research — UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Aalborg (Denmark); Tomm, Janina M., E-mail: Janina.tomm@ufz.de [Department of Proteomics, Helmholtz-Centre for Environmental Research — UFZ, Permoserstr. 15, 04318 Leipzig (Germany)

    2013-06-15

    There is a clear evidence that environmental pollutants, such as benzo[a]pyrene (B[a]P), can have detrimental effects on the immune system, whereas the underlying mechanisms still remain elusive. Jurkat T cells share many properties with native T lymphocytes and therefore are an appropriate model to analyze the effects of environmental pollutants on T cells and their activation. Since environmental compounds frequently occur at low, not acute toxic concentrations, we analyzed the effects of two subtoxic concentrations, 50 nM and 5 μM, on non- and activated cells. B[a]P interferes directly with the stimulation process as proven by an altered IL-2 secretion. Furthermore, B[a]P exposure results in significant proteomic changes as shown by DIGE analysis. Pathway analysis revealed an involvement of the AhR independent Nrf2 pathway in the altered processes observed in unstimulated and stimulated cells. A participation of the Nrf2 pathway in the change of IL-2 secretion was confirmed by exposing cells to the Nrf2 activator tBHQ. tBHQ and 5 μM B[a]P caused similar alterations of IL-2 secretion and glutamine/glutamate metabolism. Moreover, the proteome changes in unstimulated cells point towards a modified regulation of the cytoskeleton and cellular stress response, which was proven by western blotting. Additionally, there is a strong evidence for alterations in metabolic pathways caused by B[a]P exposure in stimulated cells. Especially the glutamine/glutamate metabolism was indicated by proteome pathway analysis and validated by metabolite measurements. The detrimental effects were slightly enhanced in stimulated cells, suggesting that stimulated cells are more vulnerable to the environmental pollutant model compound B[a]P. - Highlights: • B[a]P affects the proteome of Jurkat T cells also at low concentrations. • Exposure to B[a]P (50 nM, 5 μM) did not change Jurkat T cell viability. • Both B[a]P concentrations altered the IL-2 secretion of stimulated cells.

  1. Iodine-131 treatment of thyroid cancer cells leads to suppression of cell proliferation followed by induction of cell apoptosis and cell cycle arrest by regulation of B-cell translocation gene 2-mediated JNK/NF-κB pathways

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, L.M.; Pang, A.X., E-mail: zhaoliming515@126.com [Department of Nuclear Medicine, Linyi People' s Hospital, Linyi (China); Department of Urology, Linyi People' s Hospital, Linyi (China)

    2017-10-01

    Iodine-131 ({sup 131}I) is widely used for the treatment of thyroid-related diseases. This study aimed to investigate the expression of p53 and BTG2 genes following {sup 131}I therapy in thyroid cancer cell line SW579 and the possible underlying mechanism. SW579 human thyroid squamous carcinoma cells were cultured and treated with {sup 131}I. They were then assessed for {sup 131}I uptake, cell viability, apoptosis, cell cycle arrest, p53 expression, and BTG2 gene expression. SW579 cells were transfected with BTG2 siRNA, p53 siRNA and siNC and were then examined for the same aforementioned parameters. When treated with a JNK inhibitor of SP600125 and {sup 131}I or with a NF-kB inhibitor of BMS-345541 and {sup 131}I, non-transfected SW579 cells were assessed in JNK/NFkB pathways. It was observed that {sup 131}I significantly inhibited cell proliferation, promoted cell apoptosis and cell cycle arrest. Both BTG2 and p53 expression were enhanced in a dose-dependent manner. An increase in cell viability by up-regulation in Bcl2 gene, a decrease in apoptosis by enhanced CDK2 gene expression and a decrease in cell cycle arrest at G{sub 0}/G{sub 1} phase were also observed in SW579 cell lines transfected with silenced BTG2 gene. When treated with SP600125 and {sup 131}I, the non transfected SW579 cell lines significantly inhibited JNK pathway, NF-kB pathway and the expression of BTG2. However, when treated with BMS-345541 and {sup 131}I, only the NF-kB pathway was suppressed. {sup 131}I suppressed cell proliferation, induced cell apoptosis, and promoted cell cycle arrest of thyroid cancer cells by up-regulating B-cell translocation gene 2-mediated activation of JNK/NF--κB pathways. (author)

  2. Primary Metabolic Pathways and Metabolic Flux Analysis

    DEFF Research Database (Denmark)

    Villadsen, John

    2015-01-01

    his chapter introduces the metabolic flux analysis (MFA) or stoichiometry-based MFA, and describes the quantitative basis for MFA. It discusses the catabolic pathways in which free energy is produced to drive the cell-building anabolic pathways. An overview of these primary pathways provides...... the reader who is primarily trained in the engineering sciences with atleast a preliminary introduction to biochemistry and also shows how carbon is drained off the catabolic pathways to provide precursors for cell mass building and sometimes for important industrial products. The primary pathways...... to be examined in the following are: glycolysis, primarily by the EMP pathway, but other glycolytic pathways is also mentioned; fermentative pathways in which the redox generated in the glycolytic reactions are consumed; reactions in the tricarboxylic acid (TCA) cycle, which produce biomass precursors and redox...

  3. Who Leads China's Leading Universities?

    Science.gov (United States)

    Huang, Futao

    2017-01-01

    This study attempts to identify the major characteristics of two different groups of institutional leaders in China's leading universities. The study begins with a review of relevant literature and theory. Then, there is a brief introduction to the selection of party secretaries, deputy secretaries, presidents and vice presidents in leading…

  4. Deubiquitinase inhibitor b-AP15 activates endoplasmic reticulum (ER) stress and inhibits Wnt/Notch1 signaling pathway leading to the reduction of cell survival in hepatocellular carcinoma cells.

    Science.gov (United States)

    Ding, Youming; Chen, Xiaoyan; Wang, Bin; Yu, Bin; Ge, Jianhui

    2018-04-15

    b-AP15, a potent and selective inhibitor of the ubiquitin-specific peptidase 14 (USP14), displays in vitro and in vivo antitumor abilities on some types of cancer cells. However, the mechanism underlying its action is not well elucidated. The purposes of the present study are to observe the potential impacts of b-AP15 on cell survival of hepatocellular carcinoma cells and to investigate whether and how this compound inhibits some survival-promoting signaling pathways. We found that b-AP15 significantly decreased cell viability and increased cell apoptosis in a dose-dependent manner in hepatocellular carcinoma cells, along with the perturbation of cell cycle and the decreased expressions of cell cycle-related proteins. We also demonstrated that the endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) were enhanced by b-AP15 supplementation. The inhibition of ER stress/UPR only partly attenuated the cytotoxicity of b-AP15 on hepatocellular carcinoma cells. In addition, b-AP15 treatment inhibited Wnt/β-catenin and Notch1 signaling pathways, and suppressed phosphorylation of STAT3, Akt, and Erk1/2, which were not restored by the inhibition of ER stress/UPR. Furthermore, the expression levels of signaling molecules in Notch1 were reduced by specific inhibitor of Wnt/β-catenin pathway. Notably, either Wnt or Notch1 signaling inhibitor mitigated phosphorylation of STAT3, Akt, and Erk1/2, and mimicked the cytotoxicity of b-AP15 on hepatocellular carcinoma cells. These results clearly indicate that b-AP15 induced cytotoxic response to hepatocellular carcinoma cells by augmenting ER stress/UPR and inhibiting Wnt/Notch1 signaling pathways. This new finding provides a novel mechanism by which b-AP15 produces its antitumor therapeutic effects. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Reaction Decoder Tool (RDT): extracting features from chemical reactions.

    Science.gov (United States)

    Rahman, Syed Asad; Torrance, Gilliean; Baldacci, Lorenzo; Martínez Cuesta, Sergio; Fenninger, Franz; Gopal, Nimish; Choudhary, Saket; May, John W; Holliday, Gemma L; Steinbeck, Christoph; Thornton, Janet M

    2016-07-01

    Extracting chemical features like Atom-Atom Mapping (AAM), Bond Changes (BCs) and Reaction Centres from biochemical reactions helps us understand the chemical composition of enzymatic reactions. Reaction Decoder is a robust command line tool, which performs this task with high accuracy. It supports standard chemical input/output exchange formats i.e. RXN/SMILES, computes AAM, highlights BCs and creates images of the mapped reaction. This aids in the analysis of metabolic pathways and the ability to perform comparative studies of chemical reactions based on these features. This software is implemented in Java, supported on Windows, Linux and Mac OSX, and freely available at https://github.com/asad/ReactionDecoder : asad@ebi.ac.uk or s9asad@gmail.com. © The Author 2016. Published by Oxford University Press.

  6. Nuclear reactions

    International Nuclear Information System (INIS)

    Lane, A.M.

    1980-01-01

    In reviewing work at Harwell over the past 25 years on nuclear reactions it is stated that a balance has to be struck in both experiment and theory between work on cross-sections of direct practical relevance to reactors and on those relevant to an overall understanding of reaction processes. The compound nucleus and direct process reactions are described. Having listed the contributions from AERE, Harwell to developments in nuclear reaction research in the period, work on the optical model, neutron capture theory, reactions at doorway states with fine structure, and sum-rules for spectroscopic factors are considered in more detail. (UK)

  7. The development of a chemical kinetic measurement apparatus and the determination of the reaction rate constants for lithium-lead/steam interaction. Final report 9-21-90--3-31-95

    International Nuclear Information System (INIS)

    Biney, P.O.

    1995-03-01

    The objective of this research to experimentally determine the hydrogen generation rate during the beginning and subsequent stages of liquid metal (Li 17 Pb 83 ) and water reaction. The experimental set-up has been built. It includes a metal sample preparation apparatus, a reaction system, a measurement system and a PC based data acquisition and control system. The most important feature of the reaction system is a pneumatic actuated quick opening and closing high temperature, all stainless steel valve used the system for reaction time control. The PC system provides remote process sequencing, acquisition and control of all the systems except the metal preparation apparatus. Due to the reactivity of the lithium, all the metal sampling, preparation and loading procedures are executed in a glove box under argon protection. The metal temperature was varied between 350 degrees C-650 degrees C and water temperature fixed at 60 degrees C during the experiments. A set of experimental procedures and two analyses methods: (1) thermodynamics method and (2) heat transfer method are discussed. All the measurements and data collections are executed under the PC system control. A data analysis program is used to calculate both the partial pressure of hydrogen and the hydrogen generation rate. The experiment results indicate that the amount of hydrogen generated is relate to the initial liquid metal temperature when the reaction surface is fixed. The mass of hydrogen generated as a function of initial liquid metal temperature and time of reaction is presented, The hydrogen generation over a time period of 240 seconds and the calculated errors are summarized in Table 1

  8. Experimental Measurement of the Ratio of the Reaction Cross Section (n,2n) for the Natural Mixtures of Lead and Iron Isotopes with 14 MeV Neutrons by the Method of Moderated Neutron-Neutron Coincidences

    International Nuclear Information System (INIS)

    Panteleev, Ts.Ts.; Penchev, O.I.; Trifonov, A.I.; Troshev, T.M.; Christov, V.I.

    1986-01-01

    Neutron data are widely applied in nuclei physics and into practice as well. Data obtained by means of different measurement methods are of interest for increasing the accuracy and reliability of the recommended values for the cross sections of neutron interactions, with substance. The activation analysis method gives a possibility to obtain data about cross section interactions of 14 MeV neutrons with the nuclei σ (n,2n), σ( n,p), σ (n,pn), σ (n,α), etc. A serious shortcoming of this measuring method is the necessity of applying express methods of analysis of induced activities - restrictions connected with the life-times of the reaction products. It is also necessary to comply with the requirements for high accuracy in the data about the decay schemes and the absolute intensities of the γ-transitions in the investigated nuclei. The investigations directly measuring the output of the reaction, products from the targets, placed into the neutron beam, do not possess the shortcomings of the activation method but require serious demands toward the detecting apparatuses (ionization chambers, semiconducting and scintillation detectors, proportional counters, etc.). These demands are connected with the heavy background conditions of work at the beams for measurements of whatever partial cross sections. During the experimental measurements of the reactions by neutron emission for registration, it is necessary to slow them down to thermal energies, since only in this energy interval there exist sufficiently effective without threshold detectors. We have elaborated the experimental set-up allowing to measure the neutron multiplicity in an interaction. In the present work we have also used it for a relative measurement the the reaction cross section σ (n,2n) for Pe and Pb nuclei in their natural isotope mixtures. As it is known, this reaction has an important application for the blanket materials of thermonuclear reactors and for tritium fuel regeneration problem. The

  9. Mechano-chemical pathways to H2O and CO2 splitting

    Science.gov (United States)

    Vedadi, Mohammad H.; Haas, Stephan

    2011-10-01

    The shock-induced collapse of CO2-filled nanobubbles is investigated using molecular dynamics simulations based on a reactive force field. The energetic nanojet and high-pressure water hammer shock formed during and after collapse of the nanobubble trigger mechano-chemical H2O-CO2 reactions, some of which lead to splitting of water and formation of O2 molecules. The dominant pathways through which splitting of water molecules occur are identified.

  10. Measurements of gas and volatile element production rates from an irradiated molten lead and lead-bismuth spallation target with proton beams of 1 and 1.4 GeV; Mesures de taux de production d'elements gazeux et volatiles lors de reactions induites par des protons de 1 et 1,4 GeV sur des cibles epaisses de plomb et plomb-bismuth liquides

    Energy Technology Data Exchange (ETDEWEB)

    Tall, Y

    2008-03-15

    The integrated project EUROTRANS (European Research Programme for the Transmutation of High Level Nuclear Waste in an Accelerator Driven System) of the 6. EURATOM Framework Programme aims to demonstrate the transmutation of radioactive waste in ADS (Accelerator Driven Sub-critical system). It will carry out a first advanced design of an experimental facility to demonstrate the technical feasibility of transmutation, and will produce a conceptual design of an industrial facility dedicated to transmutation. An ADS consists of three fundamental elements: the accelerator of protons, the sub-critical core and the spallation target. SUBATECH (physique Sub-Atomique et des Technologies associees) laboratory is involved to the study of the chosen liquid lead-bismuth as a spallation ADS target. The irradiation of liquid lead-bismuth target with energetic proton beam generates in addition to neutrons, volatile and radioactive residues. In order to determine experimentally the production rates of gas and volatile elements following a spallation reaction in a lead-bismuth target, the experiment IS419 was performed at the ISOLDE facility at CERN (Centre Europeen de la Recherche Nucleaire). This experiment constitutes the frame of the thesis whose main objective is to assess and study the production and release rates of many gas and volatile element from the irradiated lead-bismuth target with an energetic proton beam. The obtained data are compared to Monte Carlo simulation code (MCNPX) results in order to test the intranuclear cascade model of Bertini and of Cugnon, and the evaporation options of Dresner and Schmidt. (author)

  11. Novel key metabolites reveal further branching of the roquefortine/meleagrin biosynthetic pathway.

    Science.gov (United States)

    Ries, Marco I; Ali, Hazrat; Lankhorst, Peter P; Hankemeier, Thomas; Bovenberg, Roel A L; Driessen, Arnold J M; Vreeken, Rob J

    2013-12-27

    Metabolic profiling and structural elucidation of novel secondary metabolites obtained from derived deletion strains of the filamentous fungus Penicillium chrysogenum were used to reassign various previously ascribed synthetase genes of the roquefortine/meleagrin pathway to their corresponding products. Next to the structural characterization of roquefortine F and neoxaline, which are for the first time reported for P. chrysogenum, we identified the novel metabolite roquefortine L, including its degradation products, harboring remarkable chemical structures. Their biosynthesis is discussed, questioning the exclusive role of glandicoline A as key intermediate in the pathway. The results reveal that further enzymes of this pathway are rather unspecific and catalyze more than one reaction, leading to excessive branching in the pathway with meleagrin and neoxaline as end products of two branches.

  12. The fibronectin III-1 domain activates a PI3-Kinase/Akt signaling pathway leading to αvβ5 integrin activation and TRAIL resistance in human lung cancer cells

    International Nuclear Information System (INIS)

    Cho, Christina; Horzempa, Carol; Jones, David; McKeown-Longo, Paula J.

    2016-01-01

    Fibronectin is a mechanically sensitive protein which is organized in the extracellular matrix as a network of interacting fibrils. The lung tumor stroma is enriched for fibronectin which is thought to contribute to metastasis and drug resistance. Fibronectin is an elastic, multi-modular protein made up of individually folded domains, some of which can stretch in response to increased mechanical tension. Very little is known about the relationship of fibronectin’s unfolded domains to lung cancer resistance to chemotherapy. In the present study, we evaluated the impact of unfolding the first Type III domain of fibronectin (FnIII-1c) on TNF-related apoptosis inducing ligand (TRAIL) resistance. NCI-H460 non-small cell lung cancer cells were treated with FnIII-1c then assessed for TRAIL-induced apoptosis. Subsequent analysis of FnIII-1c-mediated signaling pathways was also completed. Human non-small cell lung cancer tissue sections were assessed for the expression of vitronectin by immunohistochemistry. FnIII-1c inhibited TRAIL-induced activation of caspase 8 and subsequent apoptosis in NCI-H460 lung cancer cells. FnIII-1c treatment was associated with the activation of the phosphatidylinositol-3-kinase/alpha serine/threonine kinase (PI3K/Akt) pathway and the αvβ5 integrin receptor for vitronectin, both of which were required for TRAIL resistance. Immunohistochemical staining of sections from non-small cell lung cancers showed that vitronectin was localized around blood vessels and in the tumor-stroma interface. Unfolding of Type III domains within the fibronectin matrix may promote TRAIL resistance through the activation of a PI3K/Akt/αvβ5 signaling axis and point to a novel mechanism by which changes in secondary structure of fibronectin contribute to cancer cell resistance to apoptosis

  13. Allergic reactions in anaesthesia

    DEFF Research Database (Denmark)

    Krøigaard, M; Garvey, L H; Menné, T

    2005-01-01

    a significant number of patients at unnecessary risk. Some patients may be labelled with a wrong allergy, leading to unnecessary warnings against harmless substances, and some patients may be put at risk of subsequent re-exposure to the real allergen. Patients with suspected allergic reactions during...

  14. The Paterno-Buchi reaction

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  15. Radiation therapy and late reactions in normal tissues

    International Nuclear Information System (INIS)

    Aoyama, Takashi; Kuroda, Yasumasa

    1998-01-01

    Recent developments in cancer therapy have made us increasingly aware that the quality of life of a patient is as valuable as other benefits received from therapy. This awareness leads to an emphasis on organ and/or function preservation in the course of therapy. In line with this new thinking, greater consideration is placed on radiation therapy as an appropriate modality of cancer therapy. Possible complications in normal tissues, especially those of late reaction type after the therapy must be overcome. This review, therefore, focuses on recent progress of studies on mechanisms of the complications of the late reaction type. An observation of a clinical case concerning a late reaction of spinal cord (radiation myelopathy) and surveys of experimental studies on the mechanisms of late reactions (including radiation pneumonitis and lung fibrosis, and radiation response of vascular endothelial cells) provide a hypothesis that apoptosis through the pathway starting with radiation-induced sphingomyelin hydrolysis may play an important role in causing a variety of late reactions. This insight is based on the fact that radiation also activates protein kinase C which appears to block apoptosis. The mechanisms of late reactions, therefore, may involve a balance between radiation-induced apoptotic death and its down regulation by suppressor mechanisms through protein kinase C. (author)

  16. Quasielastic reactions

    International Nuclear Information System (INIS)

    Henning, W.

    1979-01-01

    Quasielastic reaction studies, because of their capability to microscopically probe nuclear structure, are still of considerable interest in heavy-ion reactions. The recent progress in understanding various aspects of the reaction mechanism make this aim appear closer. The relation between microscopic and macroscopic behavior, as suggested, for example, by the single proton transfer data to individual final states or averaged excitation energy intervals, needs to be explored. It seems particularly useful to extend measurements to higher incident energies, to explore and understand nuclear structure aspects up to the limit of the energy range where they are important

  17. Stochasticity in the yeast mating pathway

    International Nuclear Information System (INIS)

    Hong-Li, Wang; Zheng-Ping, Fu; Xin-Hang, Xu; Qi, Ouyang

    2009-01-01

    We report stochastic simulations of the yeast mating signal transduction pathway. The effects of intrinsic and external noise, the influence of cell-to-cell difference in the pathway capacity, and noise propagation in the pathway have been examined. The stochastic temporal behaviour of the pathway is found to be robust to the influence of inherent fluctuations, and intrinsic noise propagates in the pathway in a uniform pattern when the yeasts are treated with pheromones of different stimulus strengths and of varied fluctuations. In agreement with recent experimental findings, extrinsic noise is found to play a more prominent role than intrinsic noise in the variability of proteins. The occurrence frequency for the reactions in the pathway are also examined and a more compact network is obtained by dropping most of the reactions of least occurrence

  18. Molecular Pathways

    Science.gov (United States)

    Lok, Benjamin H.; Powell, Simon N.

    2012-01-01

    The Rad52 protein was largely ignored in humans and other mammals when the mouse knockout revealed a largely “no-effect” phenotype. However, using synthetic lethal approaches to investigate context dependent function, new studies have shown that Rad52 plays a key survival role in cells lacking the function of the BRCA1-BRCA2 pathway of homologous recombination. Biochemical studies also showed significant differences between yeast and human Rad52, in which yeast Rad52 can promote strand invasion of RPA-coated single-stranded DNA in the presence of Rad51, but human Rad52 cannot. This results in the paradox of how is human Rad52 providing Rad51 function: presumably there is something missing in the biochemical assays that exists in-vivo, but the nature of this missing factor is currently unknown. Recent studies have suggested that Rad52 provides back-up Rad51 function for all members of the BRCA1-BRCA2 pathway, suggesting that Rad52 may be a target for therapy in BRCA pathway deficient cancers. Screening for ways to inhibit Rad52 would potentially provide a complementary strategy for targeting BRCA-deficient cancers in addition to PARP inhibitors. PMID:23071261

  19. cycloaddition reactions

    Indian Academy of Sciences (India)

    Unknown

    Molecular Modeling Group, Organic Chemical Sciences, Indian Institute of Chemical Technology,. Hyderabad ... thus obtained are helpful to model the regioselectivity ... compromise to model Diels–Alder reactions involving ...... acceptance.

  20. Anodic Cyclization Reactions and the Mechanistic Strategies That Enable Optimization.

    Science.gov (United States)

    Feng, Ruozhu; Smith, Jake A; Moeller, Kevin D

    2017-09-19

    Oxidation reactions are powerful tools for synthesis because they allow us to reverse the polarity of electron-rich functional groups, generate highly reactive intermediates, and increase the functionality of molecules. For this reason, oxidation reactions have been and continue to be the subject of intense study. Central to these efforts is the development of mechanism-based strategies that allow us to think about the reactive intermediates that are frequently central to the success of the reactions and the mechanistic pathways that those intermediates trigger. For example, consider oxidative cyclization reactions that are triggered by the removal of an electron from an electron-rich olefin and lead to cyclic products that are functionalized for further elaboration. For these reactions to be successful, the radical cation intermediate must first be generated using conditions that limit its polymerization and then channeled down a productive desired pathway. Following the cyclization, a second oxidation step is necessary for product formation, after which the resulting cation must be quenched in a controlled fashion to avoid undesired elimination reactions. Problems can arise at any one or all of these steps, a fact that frequently complicates reaction optimization and can discourage the development of new transformations. Fortunately, anodic electrochemistry offers an outstanding opportunity to systematically probe the mechanism of oxidative cyclization reactions. The use of electrochemical methods allows for the generation of radical cations under neutral conditions in an environment that helps prevent polymerization of the intermediate. Once the intermediates have been generated, a series of "telltale indicators" can be used to diagnose which step in an oxidative cyclization is problematic for less successful transformation. A set of potential solutions to address each type of problem encountered has been developed. For example, problems with the initial

  1. Bonding pathways of high-pressure chemical transformations

    International Nuclear Information System (INIS)

    Hu Anguang; Zhang Fan

    2013-01-01

    A three-stage bonding pathway towards high-pressure chemical transformations from molecular precursors or intermediate states has been identified by first-principles simulations. With the evolution of principal stress tensor components in the response of chemical bonding to compressive loading, the three stages can be defined as the van der Waals bonding destruction, a bond breaking and forming reaction, and equilibrium of new bonds. The three-stage bonding pathway leads to the establishment of a fundamental principle of chemical bonding under compression. It reveals that during high-pressure chemical transformation, electrons moving away from functional groups follow anti-addition, collision-free paths to form new bonds in counteracting the local stress confinement. In applying this principle, a large number of molecular precursors were identified for high-pressure chemical transformations, resulting in new materials. (fast track communication)

  2. Interfacial reactions in intermetallic matrix composites

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  3. Direct Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Austern, N. [University of Pittsburgh, Pittsburgh, PA (United States)

    1963-01-15

    In order to give a unified presentation of one point of view, these lectures are devoted only to a detailed development of the standard theories of direct reactions, starting from basic principles. Discussion is given of the present status of the theories, of the techniques used for practical calculation, and of possible future developments. The direct interaction (DI) aspects of a reaction are those which involve only a few of the many degrees of freedom of a nucleus. In fact the minimum number of degrees of freedom which must be involved in a reaction are those required to describe the initial and final channels, and DI studies typically consider these degrees of freedom and no others. Because of this simplicity DI theories may be worked out in painstaking detail. DI processes concern only part of the wave function for a problem. The other part involves complicated excitations of many degrees of freedom, and gives the compound nucleus (CN) effects. While it is extremely interesting to learn how to separate DI and CN effects in an orderly manner, if they are both present in a reaction, no suitable method has yet been found. Instead, current work stresses the kinds of reactions and the kinds of final states in which DI effects dominate and in which CN effects may almost be forgotten. The DI cross-sections which are studied are often extremely large, comparable to elastic scattering cross-sections. (author)

  4. Electrical properties of a novel lead alkoxide precursor: Lead glycolate

    International Nuclear Information System (INIS)

    Tangboriboon, Nuchnapa; Pakdeewanishsukho, Kittikhun; Jamieson, Alexander; Sirivat, Anuvat; Wongkasemjit, Sujitra

    2006-01-01

    The reaction of lead acetate trihydrate Pb(CH 3 COO) 2 .3H 2 O and ethylene glycol, using triethylenetetramine (TETA) as a catalyst, provides in one step access to a polymer-like precursor of lead glycolate [-PbOCH 2 CH 2 O-]. On the basis of high-resolution mass spectroscopy, chemical analysis composition, FTIR, 13 C-solid state NMR and TGA, the lead glycolate precursor can be identified as a trimer structure. The FTIR spectrum demonstrates the characteristics of lead glycolate; the peaks at 1086 and 1042 cm -1 can be assigned to the C-O-Pb stretchings. The 13 C-solid state NMR spectrum gives notably only one peak at 68.639 ppm belonging to the ethylene glycol ligand. The phase transformations of lead glycolate and lead acetate trihydrate to lead oxide, their microstructures, and electrical properties were found to vary with increasing temperature. The lead glycolate precursor has superior electrical properties relative to those of lead acetate trihydrate, suggesting that the lead glycolate precursor can possibly be used as a starting material for producing electrical and semiconducting ceramics, viz. ferroelectric, anti-ferroelectric, and piezoelectric materials

  5. Discharges of copper, zinc and lead to water and soil. Analysis of the emission pathways and possible emission reduction measures; Eintraege von Kuper, Zink und Blei in Gewaesser und Boeden. Analyse der Emissionspfade und moeglicher Emissionsminderungsmassnahmen

    Energy Technology Data Exchange (ETDEWEB)

    Hillenbrand, Thomas; Toussaint, Dominik; Boehm, Eberhard [Fraunhofer-Institut fuer Systemtechnik und Innovationsforschung (ISI), Karlsruhe (Germany); Fuchs, Stephan; Scherer, Ulrike [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Siedlungswasserwirtschaft; Rudolphi, Alexander; Hoffmann, Martin [Gesellschaft fuer Oekologische Bautechnik Berlin mbH (GFOeB) (Germany)

    2005-08-15

    Because of the pollution situation for copper, zinc and lead and due to the significance of non-point sources, there is a basic need for action to reduce the environmental burden due to non-point emissions of these heavy metals. Therefore the aim of the project was first to quantify the application-related discharges of these heavy metals into water and soil. Based on this, specific strategies to reduce the emissions to water were developed. Additionally a guideline for architects and builders for the outdoor use of the substances in the building sector was drawn up with the objective of supplying information and aids on the environmentally-compatible use of these substances. Furthermore, existing life cycle assessment methods were examined for the use of various roofing materials as well as the possibilities to further develop these methods. The results of the emission calculations show the great significancy of the application areas vehicles, building sector, water supply and other specific sources (i.e. galvanized products). The examination of different measures to reduce the emissions gives a review and an assessment of the possibilities, taking into account the relevant boundary conditions. This information can also serve as the basis for elaborating a programme of measures within the scope of a future river basin management. (orig.)

  6. Reaction mechanisms

    International Nuclear Information System (INIS)

    Nguyen Trong Anh

    1988-01-01

    The 1988 progress report of the Reaction Mechanisms laboratory (Polytechnic School, France), is presented. The research topics are: the valence bond methods, the radical chemistry, the modelling of the transition states by applying geometric constraints, the long range interactions (ion - molecule) in gaseous phase, the reaction sites in gaseous phase and the mass spectroscopy applications. The points of convergence between the investigations of the mass spectroscopy and the theoretical chemistry teams, as well as the purposes guiding the research programs, are discussed. The published papers, the conferences, the congress communications and the thesis, are also reported [fr

  7. Skin: Major target organ of allergic reactions to small molecular weight compounds

    International Nuclear Information System (INIS)

    Merk, Hans F.; Baron, Jens M.; Neis, Mark M.; Obrigkeit, Daniela Hoeller; Karlberg, Ann-Therese

    2007-01-01

    Skin is a major target organ for allergic reactions to small molecular weight compounds. Drug allergic reactions may be life-threatening such as in the case of anaphylactic reactions or bullous drug reactions and occur in about 5% of all hospitalized patients. Allergic contact dermatitis has an enormous influence on the social life of the patient because it is the most frequent reason for occupational skin diseases and the treatment and prevention of this disease cost approximately Euro 3 billion per year in Germany. The different proposed pathophysiological pathways leading to a drug eruption are discussed in this paper. All major enzymes which are involved in the metabolism of xenobiotica were shown to be present in skin. Evidence supporting the role of metabolism in the development of drug allergy and allergic contact dermatitis is demonstrated in the example of sulphonamides and fragrances

  8. ReactionPredictor: prediction of complex chemical reactions at the mechanistic level using machine learning.

    Science.gov (United States)

    Kayala, Matthew A; Baldi, Pierre

    2012-10-22

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

  9. Nonclassical nucleation pathways in protein crystallization.

    Science.gov (United States)

    Zhang, Fajun

    2017-11-08

    Classical nucleation theory (CNT), which was established about 90 years ago, has been very successful in many research fields, and continues to be the most commonly used theory in describing the nucleation process. For a fluid-to-solid phase transition, CNT states that the solute molecules in a supersaturated solution reversibly form small clusters. Once the cluster size reaches a critical value, it becomes thermodynamically stable and favored for further growth. One of the most important assumptions of CNT is that the nucleation process is described by one reaction coordinate and all order parameters proceed simultaneously. Recent studies in experiments, computer simulations and theory have revealed nonclassical features in the early stage of nucleation. In particular, the decoupling of order parameters involved during a fluid-to-solid transition leads to the so-called two-step nucleation mechanism, in which a metastable intermediate phase (MIP) exists between the initial supersaturated solution and the final crystals. Depending on the exact free energy landscapes, the MIPs can be a high density liquid phase, mesoscopic clusters, or a pre-ordered state. In this review, we focus on the studies of nonclassical pathways in protein crystallization and discuss the applications of the various scenarios of two-step nucleation theory. In particular, we focus on protein solutions in the presence of multivalent salts, which serve as a model protein system to study the nucleation pathways. We wish to point out the unique features of proteins as model systems for further studies.

  10. Nonclassical nucleation pathways in protein crystallization

    Science.gov (United States)

    Zhang, Fajun

    2017-11-01

    Classical nucleation theory (CNT), which was established about 90 years ago, has been very successful in many research fields, and continues to be the most commonly used theory in describing the nucleation process. For a fluid-to-solid phase transition, CNT states that the solute molecules in a supersaturated solution reversibly form small clusters. Once the cluster size reaches a critical value, it becomes thermodynamically stable and favored for further growth. One of the most important assumptions of CNT is that the nucleation process is described by one reaction coordinate and all order parameters proceed simultaneously. Recent studies in experiments, computer simulations and theory have revealed nonclassical features in the early stage of nucleation. In particular, the decoupling of order parameters involved during a fluid-to-solid transition leads to the so-called two-step nucleation mechanism, in which a metastable intermediate phase (MIP) exists between the initial supersaturated solution and the final crystals. Depending on the exact free energy landscapes, the MIPs can be a high density liquid phase, mesoscopic clusters, or a pre-ordered state. In this review, we focus on the studies of nonclassical pathways in protein crystallization and discuss the applications of the various scenarios of two-step nucleation theory. In particular, we focus on protein solutions in the presence of multivalent salts, which serve as a model protein system to study the nucleation pathways. We wish to point out the unique features of proteins as model systems for further studies.

  11. Theoretical study of the oxidation mechanisms of naphthalene initiated by hydroxyl radicals: the OH-addition pathway.

    Science.gov (United States)

    Shiroudi, Abolfazl; Deleuze, Michael S; Canneaux, Sébastien

    2014-07-03

    The oxidation mechanisms of naphthalene by OH radicals under inert (He) conditions have been studied using density functional theory along with various exchange-correlation functionals. Comparison has been made with benchmark CBS-QB3 theoretical results. Kinetic rate constants were correspondingly estimated by means of transition state theory and statistical Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Comparison with experiment confirms that, on the OH-addition reaction pathway leading to 1-naphthol, the first bimolecular reaction step has an effective negative activation energy around -1.5 kcal mol(-1), whereas this step is characterized by an activation energy around 1 kcal mol(-1) on the OH-addition reaction pathway leading to 2-naphthol. Effective rate constants have been calculated according to a steady state analysis upon a two-step model reaction mechanism. In line with experiment, the correspondingly obtained branching ratios indicate that, at temperatures lower than 410 K, the most abundant product resulting from the oxidation of naphthalene by OH radicals must be 1-naphthol. The regioselectivity of the OH(•)-addition onto naphthalene decreases with increasing temperatures and decreasing pressures. Because of slightly positive or even negative activation energies, the RRKM calculations demonstrate that the transition state approximation breaks down at ambient pressure (1 bar) for the first bimolecular reaction steps. Overwhelmingly high pressures, larger than 10(5) bar, would be required for restoring to some extent (within ∼5% accuracy) the validity of this approximation for all the reaction channels that are involved in the OH-addition pathway. Analysis of the computed structures, bond orders, and free energy profiles demonstrate that all reaction steps involved in the oxidation of naphthalene by OH radicals satisfy Leffler-Hammond's principle. Nucleus independent chemical shift indices and natural bond orbital analysis also show that the computed

  12. Molecular pathways

    DEFF Research Database (Denmark)

    Cox, Thomas R; Erler, Janine Terra

    2014-01-01

    Pathologic organ fibrosis is a condition that can affect all major tissues and is typically ascribed to the excessive accumulation of extracellular matrix components, predominantly collagens. It typically leads to compromise of organ function and subsequent organ failure, and it is estimated...

  13. Allergic reactions

    Science.gov (United States)

    ... that don't bother most people (such as venom from bee stings and certain foods, medicines, and pollens) can ... person. If the allergic reaction is from a bee sting, scrape the ... more venom. If the person has emergency allergy medicine on ...

  14. Concise Synthesis of Macrocycles by Multicomponent Reactions

    NARCIS (Netherlands)

    Abdelraheem, Eman M. M.; Khaksar, Samad; Dömling, Alexander

    2018-01-01

    A short reaction pathway was devised to synthesize a library of artificial 18-27-membered macrocycles. The five-step reaction sequence involves ring opening of a cyclic anhydride with a diamine, esterification, coupling with an amino acid isocyanide, saponification, and, finally, macro-ring closure

  15. Formation of trihalomethanes from the halogenation of 1,3-dihydroxybenzenes in dilute aqueous solution: synthesis of 2-13C-resorcinol and its reaction with chlorine and bromine

    International Nuclear Information System (INIS)

    Boyce, S.D.; Barefoot, A.C.; Britton, D.R.; Hornig, J.F.

    1983-01-01

    As part of this study, the reaction of bromine with resorcinol and structurally related substrates to produce bromoform was examined. Preliminary results suggest that the chlorination and bromination of dihydroxybenzenes proceeded by similar reaction pathways. This chapter describes the successful synthesis of 2- 13 C-1, 3-dihydroxybenzene. Treatment of the isotopically labelled substrate with chlorine and bromine in dilute aqueous solution has elucidated many important details of the sequence of reactions leading to the production of chloroform (CHCl 3 ) and bromoform (CHBr 3 ). The 13 C-enriched products and intermediates formed during these reactions were identified by gas chromatography/mass spectrometry

  16. Method for determining heterologous biosynthesis pathways

    KAUST Repository

    Gao, Xin

    2017-08-10

    The present invention relates to a method and system for dynamically analyzing, determining, predicting and displaying ranked suitable heterologous biosynthesis pathways for a specified host. The present invention addresses the problem of finding suitable pathways for the endogenous metabolism of a host organism because the efficacy of heterologous biosynthesis is affected by competing endogenous pathways. The present invention is called MRE (Metabolic Route Explorer), and it was conceived and developed to systematically and dynamically search for, determine, analyze, and display promising heterologous pathways while considering competing endogenous reactions in a given host organism.

  17. An optimization model for metabolic pathways.

    Science.gov (United States)

    Planes, F J; Beasley, J E

    2009-10-15

    Different mathematical methods have emerged in the post-genomic era to determine metabolic pathways. These methods can be divided into stoichiometric methods and path finding methods. In this paper we detail a novel optimization model, based upon integer linear programming, to determine metabolic pathways. Our model links reaction stoichiometry with path finding in a single approach. We test the ability of our model to determine 40 annotated Escherichia coli metabolic pathways. We show that our model is able to determine 36 of these 40 pathways in a computationally effective manner.

  18. Excitation functions and yields of proton induced reactions at intermediate energies leading to important diagnostics radioisotopes of {sup 52}Fe, {sup 77}Br, {sup 82}Rb, {sup 97}Ru, {sup 111}In, {sup 123}I, {sup 127}Xe, {sup 128}Cs, {sup 178}Ta and {sup 201}Tl

    Energy Technology Data Exchange (ETDEWEB)

    Rurarz, E. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

    1994-12-31

    This report describes investigations of the excitation functions of the proton induced reactions on 14 targets (Mn, Co, Br, Rb, {sup 99}Tc, {sup 113}Cd, {sup 114}Cd, Cd, I, Cs, Ta, {sup 206,207,208}Pb) leading directly or indirectly to the formation of radionuclides {sup 52}Fe, {sup 77}Br, {sup 82}Rb, {sup 97}Ru, {sup 111}In, {sup 123}I, {sup 127}Xe, {sup 128}Cs, {sup 178}Ta and {sup 201}Tl frequently used in diagnostic procedures of nuclear medicine. The measurements of the excitation functions were made over a wide proton energy range from the reaction threshold up to 100 MeV using the stacked foil (or pellet) technique. Small energy steps were used to allow for accurate determination of the structure of excitation functions. For {sup 97}Ru, {sup 111}In and {sup 127}Xe formation with protons, new reaction channels and targets were used and data concerning this method are published for the first time. The data for {sup 52}Fe, {sup 77}Br, {sup 82}Rb, {sup 123}I, {sup 128}Cs and {sup 201}Tl obtained in the present work for the E{sub p}=70-100 MeV region are also published for the first time. The measured excitation functions for the formation of desired (and undesired) radionuclides (altogether 28 excitation functions) are compared with the theoretical ones calculated on the basis of a hybrid model of nuclear reactions in the form of the Overlaid Alice computer code. In order to determine the contribution of the competitive reaction channels to the purity of the produced, desired radionuclide, the excitation functions of the accompanying reactions were also calculated. The 122 calculated excitation functions for the possible contaminant are given. The comparison of experimental excitation functions with the results of model calculations showed satisfactory agreement; no parameter adjustment for individual reaction products was undertaken. Production yields for 28 radionuclides mentioned above were determined (author). 262 refs, 65 figs, 34 tabs.

  19. Atomic Layer Deposition of Al2O3 on H-Passivated GeSi: Initial Surface Reaction Pathways with H/GeSi(100)-2 × 1

    International Nuclear Information System (INIS)

    Yu, Shi; Qing-Qing, Sun; Lin, Dong; Han, Liu; Shi-Jin, Ding; Wei, Zhang

    2009-01-01

    The reaction mechanisms of Al(CH 3 ) 3 (TMA) adsorption on H-passivated GeSi(100)-2 × 1 surface are investigated with density functional theory. The Si–Ge and Ge–Ge one-dimer cluster models are employed to represent the GeSi(100)-2 × 1 surface with different Ge compositions. For a Si-Ge dimer of a H-passivated SiGe surface, TMA adsorption on both Si–H * and Ge–H * sites is considered. The activation barrier of TMA with the Si–H * site (1.2eV) is higher than that of TMA with the Ge-H * site (0.91 eV), which indicates that the reaction proceeds more slowly on the Si-H * site than on the Ge-H * site. In addition, adsorption of TMA is more energetically favorable on the Ge–Ge dimer than on the Si–Ge dimer of H-passivated SiGe. (atomic and molecular physics)

  20. Combining chemoinformatics with bioinformatics: in silico prediction of bacterial flavor-forming pathways by a chemical systems biology approach "reverse pathway engineering".

    Science.gov (United States)

    Liu, Mengjin; Bienfait, Bruno; Sacher, Oliver; Gasteiger, Johann; Siezen, Roland J; Nauta, Arjen; Geurts, Jan M W

    2014-01-01

    The incompleteness of genome-scale metabolic models is a major bottleneck for systems biology approaches, which are based on large numbers of metabolites as identified and quantified by metabolomics. Many of the revealed secondary metabolites and/or their derivatives, such as flavor compounds, are non-essential in metabolism, and many of their synthesis pathways are unknown. In this study, we describe a novel approach, Reverse Pathway Engineering (RPE), which combines chemoinformatics and bioinformatics analyses, to predict the "missing links" between compounds of interest and their possible metabolic precursors by providing plausible chemical and/or enzymatic reactions. We demonstrate the added-value of the approach by using flavor-forming pathways in lactic acid bacteria (LAB) as an example. Established metabolic routes leading to the formation of flavor compounds from leucine were successfully replicated. Novel reactions involved in flavor formation, i.e. the conversion of alpha-hydroxy-isocaproate to 3-methylbutanoic acid and the synthesis of dimethyl sulfide, as well as the involved enzymes were successfully predicted. These new insights into the flavor-formation mechanisms in LAB can have a significant impact on improving the control of aroma formation in fermented food products. Since the input reaction databases and compounds are highly flexible, the RPE approach can be easily extended to a broad spectrum of applications, amongst others health/disease biomarker discovery as well as synthetic biology.

  1. Voltammetry coupled to mass spectrometry in the presence of isotope {sup 18}O labeled water for the prediction of oxidative transformation pathways of activated aromatic ethers: Acebutolol

    Energy Technology Data Exchange (ETDEWEB)

    Bussy, Ugo; Tea, Illa [LUNAM Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse et Modélisation (CEISAM), UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France); Ferchaud-Roucher, Véronique; Krempf, Michel [Université de Nantes, Plateforme Spectrométrie de Masse, CRNH, SFR Santé F. Bonamy, Institut du Thorax, UMR S1087, IRT-UN, BP 70721, 8 Quai Moncousu, 44007 Nantes cedex 1 (France); Silvestre, Virginie; Galland, Nicolas [LUNAM Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse et Modélisation (CEISAM), UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France); Jacquemin, Denis [LUNAM Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse et Modélisation (CEISAM), UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France); Institut Universitaire de France, 103, Boulevard Saint-Michel, 75005 Cedex 5 France (France); Andresen-Bergström, Moa; Jurva, Ulrik [CVGI iMed DMPK, AstraZeneca R and D Mölndal, Mölndal (Sweden); and others

    2013-01-31

    Highlights: ► Voltammetry coupled to mass spectrometry method as a useful tool for on-line predictions of electrochemical transformations. ► Evidence of the O-dealkoxylation reaction pathway of acebutolol in the presence of labeled water. ► New approach for on line EC-MS applications. -- Abstract: The coupling between an electrochemical cell (EC) and a mass spectrometer (MS) is a useful screening tool (EC-MS) to study the oxidative transformation pathways of various electroactive species. For that purpose, we showed that the EC-MS method, carried out in the presence and absence of isotope {sup 18}O labeled water leads not only to a fast identification of oxidation products but also leads to a fast elucidation of the mechanism pathway reaction. We examined herein the case of the electrochemical hydrolysis of activated aromatic ether. Acebutolol (β-blockers) was selected herein as model of activated aromatic ether, and its electrochemical oxidation was examined in both the presence and absence of isotope {sup 18}O labeled water. To elucidate electrochemical hydrolysis pathway reaction: O-dealkylation or O-dealkoxylation, our approach was used to prove its applicability. The electrochemical oxidation mechanism was then elucidated showing an O-dealkoxylation reaction. In addition, density functional theory (DFT) calculations fully support the experimental conclusions.

  2. Quasielastic reactions

    International Nuclear Information System (INIS)

    Hansen, O.

    1983-01-01

    A brief review is presented of the experimental and theoretical situation regarding transfer reactions and inelastic scattering. In the first category there is little (very little) precision data for heavy projectiles and consequently almost no experience with quantitative theoretical analysis. For the inelastic scattering the rather extensive data strongly supports the coupled channels models with collective formfactors. At the most back angles, at intensities about 10 -5 of Rutherford scattering, a second, compound-like mechanism becomes dominant. The description of the interplay of these two opposite mechanisms provides a new challenge for our understanding

  3. Evolution of a flipped pathway creates metabolic innovation in tomato trichomes through BAHD enzyme promiscuity.

    Science.gov (United States)

    Fan, Pengxiang; Miller, Abigail M; Liu, Xiaoxiao; Jones, A Daniel; Last, Robert L

    2017-12-12

    Plants produce hundreds of thousands of structurally diverse specialized metabolites via multistep biosynthetic networks, including compounds of ecological and therapeutic importance. These pathways are restricted to specific plant groups, and are excellent systems for understanding metabolic evolution. Tomato and other plants in the nightshade family synthesize protective acylated sugars in the tip cells of glandular trichomes on stems and leaves. We describe a metabolic innovation in wild tomato species that contributes to acylsucrose structural diversity. A small number of amino acid changes in two acylsucrose acyltransferases alter their acyl acceptor preferences, resulting in reversal of their order of reaction and increased product diversity. This study demonstrates how small numbers of amino acid changes in multiple pathway enzymes can lead to diversification of specialized metabolites in plants. It also highlights the power of a combined genetic, genomic and in vitro biochemical approach to identify the evolutionary mechanisms leading to metabolic novelty.

  4. Redox reactions in food fermentations

    DEFF Research Database (Denmark)

    Hansen, Egon Bech

    2018-01-01

    involves oxidative steps in the early part of the pathways whereas a multitude of different reactions are used as compensating reductions. Much of the diversity seen between food fermentations arise from the different routes and the different electron acceptors used by microorganisms to counterbalance...... and this contributes to the diversity in flavor, color, texture, and shelf life. The review concludes that these reactions are still only incompletely understood and that they represent an interesting area for fundamental research and also represent a fertile field for product development through a more conscious use...... of the redox properties of strains used to compose food cultures....

  5. Nuclear reactions

    International Nuclear Information System (INIS)

    Corner, J.; Richardson, K.; Fenton, N.

    1990-01-01

    Nuclear reactions' marks a new development in the study of television as an agency of public policy debate. During the Eighties, nuclear energy became a major international issue. The disasters at Three-mile Island and Chernobyl created a global anxiety about its risks and a new sensitivity to it among politicians and journalists. This book is a case-study into documentary depictions of nuclear energy in television and video programmes and into the interpretations and responses of viewers drawn from many different occupational groupings. How are the complex and specialist arguments about benefit, risk and proof conveyed through the different conventions of commentary, interview and film sequence? What symbolic associations does the visual language of television bring to portrayals of the issue? And how do viewers make sense of various and conflicting accounts, connecting what they see and hear on the screen with their pre-existing knowledge, experience and 'civic' expectations. The authors examine some of the contrasting forms and themes which have been used by programme makers to explain and persuade, and then give a sustained analysis of the nature and sources of viewers' own accounts. 'Nuclear Reactions' inquires into the public meanings surrounding energy and the environment, spelling out in its conclusion some of the implications for future media treatments of this issue. It is also a key contribution to the international literature on 'television knowledge' and the processes of active viewing. (author)

  6. The evolution of plant virus transmission pathways

    Science.gov (United States)

    Frédéric M. Hamelin; Linda J.S. Allen; Holly R. Prendeville; M. Reza Hajimorad; Michael J. Jeger

    2016-01-01

    The evolution of plant virus transmission pathways is studied through transmission via seed, pollen, oravector. We address the questions: under what circumstances does vector transmission make pollen transmission redundant? Can evolution lead to the coexistence of multiple virus transmission pathways? We restrict the analysis to an annual plant population in which...

  7. Multiple Sensory-Motor Pathways Lead to Coordinated Visual Attention

    Science.gov (United States)

    Yu, Chen; Smith, Linda B.

    2017-01-01

    Joint attention has been extensively studied in the developmental literature because of overwhelming evidence that the ability to socially coordinate visual attention to an object is essential to healthy developmental outcomes, including language learning. The goal of this study was to understand the complex system of sensory-motor behaviors that…

  8. Lead levels - blood

    Science.gov (United States)

    Blood lead levels ... is used to screen people at risk for lead poisoning. This may include industrial workers and children ... also used to measure how well treatment for lead poisoning is working. Lead is common in the ...

  9. Lead Poisoning Prevention Tips

    Science.gov (United States)

    ... or removed safely. How are children exposed to lead? Lead-based paint and lead contaminated dust are ... What can be done to prevent exposure to lead? It is important to determine the construction year ...

  10. Medium effects in direct reactions

    International Nuclear Information System (INIS)

    Karakoc, M; Bertulani, C

    2013-01-01

    We discuss medium corrections of the nucleon-nucleon (NN) cross sections and their influence on direct reactions at intermediate energies ≳50 MeV/nucleon. The results obtained with free NN cross sections are compared with those obtained with a geometrical treatment of Pauli-blocking and Dirac-Bruecker methods. We show that medium corrections may lead to sizable modifications for collisions at intermediate energies and that they are more pronounced in reactions involving weakly bound nuclei.

  11. Spallation reactions; Reactions de spallation

    Energy Technology Data Exchange (ETDEWEB)

    Cugon, J.

    1996-12-31

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

  12. Reconstructing biochemical pathways from time course data.

    Science.gov (United States)

    Srividhya, Jeyaraman; Crampin, Edmund J; McSharry, Patrick E; Schnell, Santiago

    2007-03-01

    Time series data on biochemical reactions reveal transient behavior, away from chemical equilibrium, and contain information on the dynamic interactions among reacting components. However, this information can be difficult to extract using conventional analysis techniques. We present a new method to infer biochemical pathway mechanisms from time course data using a global nonlinear modeling technique to identify the elementary reaction steps which constitute the pathway. The method involves the generation of a complete dictionary of polynomial basis functions based on the law of mass action. Using these basis functions, there are two approaches to model construction, namely the general to specific and the specific to general approach. We demonstrate that our new methodology reconstructs the chemical reaction steps and connectivity of the glycolytic pathway of Lactococcus lactis from time course experimental data.

  13. Pathway Distiller - multisource biological pathway consolidation.

    Science.gov (United States)

    Doderer, Mark S; Anguiano, Zachry; Suresh, Uthra; Dashnamoorthy, Ravi; Bishop, Alexander J R; Chen, Yidong

    2012-01-01

    One method to understand and evaluate an experiment that produces a large set of genes, such as a gene expression microarray analysis, is to identify overrepresentation or enrichment for biological pathways. Because pathways are able to functionally describe the set of genes, much effort has been made to collect curated biological pathways into publicly accessible databases. When combining disparate databases, highly related or redundant pathways exist, making their consolidation into pathway concepts essential. This will facilitate unbiased, comprehensive yet streamlined analysis of experiments that result in large gene sets. After gene set enrichment finds representative pathways for large gene sets, pathways are consolidated into representative pathway concepts. Three complementary, but different methods of pathway consolidation are explored. Enrichment Consolidation combines the set of the pathways enriched for the signature gene list through iterative combining of enriched pathways with other pathways with similar signature gene sets; Weighted Consolidation utilizes a Protein-Protein Interaction network based gene-weighting approach that finds clusters of both enriched and non-enriched pathways limited to the experiments' resultant gene list; and finally the de novo Consolidation method uses several measurements of pathway similarity, that finds static pathway clusters independent of any given experiment. We demonstrate that the three consolidation methods provide unified yet different functional insights of a resultant gene set derived from a genome-wide profiling experiment. Results from the methods are presented, demonstrating their applications in biological studies and comparing with a pathway web-based framework that also combines several pathway databases. Additionally a web-based consolidation framework that encompasses all three methods discussed in this paper, Pathway Distiller (http://cbbiweb.uthscsa.edu/PathwayDistiller), is established to allow

  14. Acute dystonic reaction leading to lingual hematoma mimicking angioedema

    Science.gov (United States)

    Sezer, Özgür; Aydin, Ali Attila; Bilge, Sedat; Arslan, Fatih; Arslan, Hasan

    2017-01-01

    Lingual hematoma is a severe situation, which is rare and endangers the airway. It can develop due to trauma, vascular abnormalities, and coagulopathy. Due to its sudden development, it can be clinically confused with angioedema. In patients who applied to the doctor with complaints of a swollen tongue, lingual hematoma can be confused with angioedema, in particular, at the beginning if the symptoms occurred after drug use. It should especially be considered that dystonia in the jaw can present as drug-induced hyperkinetic movement disorder. Early recognition of this rare clinical condition and taking precautions for providing airway patency are essential. In this case report, we will discuss mimicking angioedema and caused by a bite due to dystonia and separation of the tongue from the base of the mouth developing concurrently with lingual hematoma. PMID:29326495

  15. Rate coefficients for hydrogen abstraction reaction of pinonaldehyde

    Indian Academy of Sciences (India)

    The H abstraction reaction from the –CHO group was found to be the most dominant reaction channelamong all the possible reaction pathways and its corresponding rate coefficient at 300 K is kEckart's unsymmetrical= 3.86 ×10-10 cm3 molecule-1 s-1. Whereas the channel with immediate lower activation energy is the ...

  16. The chemical basis of DNA damage by the direct pathway of ionizing radiation

    International Nuclear Information System (INIS)

    Sharma, Kiran Kumar K.

    2013-01-01

    Free radicals in living system has been implicated as playing a major role in the etiology of variety of diseases. The mechanism of free radicals in vivo involves predominantly the reaction with the DNA, producing different types of damage to the DNA. These lesions induced to the DNA could lead to mutation and even cell death. Radiolysis techniques, which uses ionizing radiation has proven to be one of the most advanced and excellent tool for studying the free radical reaction mechanisms as it can produce a host of well characterized free radicals. The effects of ionizing radiation on DNA have been studied for many years. Ionizing radiation interacts with DNA in vivo by two pathways, direct and indirect. The indirect accounts for 50-60% while the direct effect accounts for 40-50%. The chemical mechanism of the former reaction arising mainly from the reactive species produced by radiolysis of water has been extensively studied, however with respect to the later pathway, which creates holes and electrons to the DNA molecule using DNA films and crystals is an active area of research as both the pathways plays important roles in DNA damage in vivo particularly in chromosomal DNA which are tightly bound with histones and compartmentalized

  17. Targeting Apoptosis Signaling Pathways for Anticancer Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Fulda, Simone, E-mail: simone.fulda@kgu.de [Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt (Germany)

    2011-08-29

    Treatment approaches for cancer, for example chemotherapy, radiotherapy, or immunotherapy, primarily act by inducing cell death in cancer cells. Consequently, the inability to trigger cell death pathways or alternatively, evasion of cancer cells to the induction of cell death pathways can result in resistance of cancers to current treatment protocols. Therefore, in order to overcome treatment resistance a better understanding of the underlying mechanisms that regulate cell death and survival pathways in cancers and in response to cancer therapy is necessary to develop molecular-targeted therapies. This strategy should lead to more effective and individualized treatment strategies that selectively target deregulated signaling pathways in a tumor type- and patient-specific manner.

  18. Targeting Apoptosis Signaling Pathways for Anticancer Therapy

    International Nuclear Information System (INIS)

    Fulda, Simone

    2011-01-01

    Treatment approaches for cancer, for example chemotherapy, radiotherapy, or immunotherapy, primarily act by inducing cell death in cancer cells. Consequently, the inability to trigger cell death pathways or alternatively, evasion of cancer cells to the induction of cell death pathways can result in resistance of cancers to current treatment protocols. Therefore, in order to overcome treatment resistance a better understanding of the underlying mechanisms that regulate cell death and survival pathways in cancers and in response to cancer therapy is necessary to develop molecular-targeted therapies. This strategy should lead to more effective and individualized treatment strategies that selectively target deregulated signaling pathways in a tumor type- and patient-specific manner.

  19. Density functional computational studies on the glucose and glycine Maillard reaction: Formation of the Amadori rearrangement products

    Science.gov (United States)

    Jalbout, Abraham F.; Roy, Amlan K.; Shipar, Abul Haider; Ahmed, M. Samsuddin

    Theoretical energy changes of various intermediates leading to the formation of the Amadori rearrangement products (ARPs) under different mechanistic assumptions have been calculated, by using open chain glucose (O-Glu)/closed chain glucose (A-Glu and B-Glu) and glycine (Gly) as a model for the Maillard reaction. Density functional theory (DFT) computations have been applied on the proposed mechanisms under different pH conditions. Thus, the possibility of the formation of different compounds and electronic energy changes for different steps in the proposed mechanisms has been evaluated. B-Glu has been found to be more efficient than A-Glu, and A-Glu has been found more efficient than O-Glu in the reaction. The reaction under basic condition is the most favorable for the formation of ARPs. Other reaction pathways have been computed and discussed in this work.0

  20. Chain reaction

    International Nuclear Information System (INIS)

    Balogh, Brian.

    1991-01-01

    Chain Reaction is a work of recent American political history. It seeks to explain how and why America came to depend so heavily on its experts after World War II, how those experts translated that authority into political clout, and why that authority and political discretion declined in the 1970s. The author's research into the internal memoranda of the Atomic Energy Commission substantiates his argument in historical detail. It was not the ravages of American anti-intellectualism, as so many scholars have argued, that brought the experts back down to earth. Rather, their decline can be traced to the very roots of their success after World War II. The need to over-state anticipated results in order to garner public support, incessant professional and bureaucratic specialization, and the sheer proliferation of expertise pushed arcane and insulated debates between experts into public forums at the same time that a broad cross section of political participants found it easier to gain access to their own expertise. These tendencies ultimately undermined the political influence of all experts. (author)

  1. Pathways for Learning from 3D Technology

    Science.gov (United States)

    Carrier, L. Mark; Rab, Saira S.; Rosen, Larry D.; Vasquez, Ludivina; Cheever, Nancy A.

    2016-01-01

    The purpose of this study was to find out if 3D stereoscopic presentation of information in a movie format changes a viewer's experience of the movie content. Four possible pathways from 3D presentation to memory and learning were considered: a direct connection based on cognitive neuroscience research; a connection through "immersion" in that 3D presentations could provide additional sensorial cues (e.g., depth cues) that lead to a higher sense of being surrounded by the stimulus; a connection through general interest such that 3D presentation increases a viewer’s interest that leads to greater attention paid to the stimulus (e.g., "involvement"); and a connection through discomfort, with the 3D goggles causing discomfort that interferes with involvement and thus with memory. The memories of 396 participants who viewed two-dimensional (2D) or 3D movies at movie theaters in Southern California were tested. Within three days of viewing a movie, participants filled out an online anonymous questionnaire that queried them about their movie content memories, subjective movie-going experiences (including emotional reactions and "presence") and demographic backgrounds. The responses to the questionnaire were subjected to path analyses in which several different links between 3D presentation to memory (and other variables) were explored. The results showed there were no effects of 3D presentation, either directly or indirectly, upon memory. However, the largest effects of 3D presentation were on emotions and immersion, with 3D presentation leading to reduced positive emotions, increased negative emotions and lowered immersion, compared to 2D presentations. PMID:28078331

  2. Organosulfate Formation through the Heterogeneous Reaction of Sulfur Dioxide with Unsaturated Compounds

    Science.gov (United States)

    George, C.; Passananti, M.; Kong, L.; Shang, J.; Perrier, S.; Jianmin, C.; Donaldson, D. J.

    2016-12-01

    The atmospheric formation of organosulfur derivatives through reaction with SO2 is generally mediated by oxidants such as O3, OH; recently we have proposed a direct reaction between SO2 and unsaturated compounds as another possible pathway for organosulfate formation in the troposphere. For the first time it was shown recently that a heterogeneous reaction between SO2 and oleic acid (OA; an unsaturated fatty acid) takes place and leads efficiently to the formation of organosulfur products. Here, we demonstrate that this reaction proceeds on various unsaturated compounds, and may therefore have a general environmental impact. We used different experimental strategies i.e., a coated flow tube (CFT), an aerosol flow tube (AFT) and a DRIFT (diffuse reflectance infrared Fourier transform) cell. The reaction products were analyzed by means of liquid chromatography coupled to a high resolution mass spectrometer (LC-HR-MS). We report indeed that SO2 reacts with large variety of C=C unsaturations and that even in the presence of ozone, SO2 reacts with OA leading to organosulfur products. A strong enhancement in product formation is observed under actinic illumination, increases the atmospheric significance of this chemical pathway. This is probably due to the chromophoric nature of the SO2 adduct with C=C bonds, and means that the contribution of this direct addition of SO2 could be in excess of 5%. The detection in atmospheric aer