WorldWideScience

Sample records for chemistry phase relations

  1. Gas phase ion chemistry

    CERN Document Server

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation

  2. Gas phase ion chemistry

    CERN Document Server

    Bowers, Michael T

    1979-01-01

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

  3. The gas-phase thermal chemistry of tetralin and related model systems

    Energy Technology Data Exchange (ETDEWEB)

    Malandra, J.

    1993-05-01

    The thesis is divided into 5 papers: gas-phase thermal decomposition of tetralin; flash vacuum pyrolysis of 3-benzocycloheptenone and 1,3, 4,5-tetrahydro-2-benzothiepin-2,2-dioxide (model systems for gas-phase pyrolysis of tetralin); high-temperature gas-phase reactions of o-allylbenzyl radicals generated by flash vacuum pyrolysis of is(o-allylbenzyl) oxalate; flash vacuum pyrolysis of 1,4-diphenylbutane; and flash vacuum pyrolysis of o-allyltoluene, o-(3-butenyl)toluene and o-(pentenyl)toluene were also used.

  4. Introducing Relativity into Quantum Chemistry

    Science.gov (United States)

    Li, Wai-Kee; Blinder, S. M.

    2011-01-01

    It is not often realized by chemists that the special theory of relativity is behind several aspects of quantum chemistry. The Schrdinger equation itself is based on relations between space-time and energy-momentum four vectors. Electron spin is, of course, the most obvious manifestation of relativity. The chemistry of some heavy elements is…

  5. Type-I clathrate Ba8Ni(x)Si(46-x): phase relations, crystal chemistry and thermoelectric properties.

    Science.gov (United States)

    Falmbigl, M; Chen, M X; Grytsiv, A; Rogl, P; Royanian, E; Michor, H; Bauer, E; Podloucky, R; Giester, G

    2012-08-07

    The phase relations, crystal structure and thermoelectric properties of the type-I solid solution Ba(8)Ni(x)Si(46-x) were investigated. Based on X-ray diffraction, differential thermal analysis and electron probe microanalysis data, a partial phase diagram was constructed for the Si-rich part of ternary system Ba-Ni-Si at 800 °C. The solubility range of Ni in the clathrate-I phase at 800 °C was determined (2.9 ≤x≤ 3.8) and thermoelectric properties, namely electrical resistivity, Seebeck-coefficient and thermal conductivity, were measured in the temperature range from 300 to 850 K. A shift of the thermoelectric properties from a predominantly metallic to a more semiconducting behavior was observed for an increasing Ni-content. Density functional calculations revealed a significant decrease of the gap width in the density of states induced by the incorporation of Ni. Electrical resistivity and Seebeck coefficients for Ba(8)Ni(x)Si(46-x) with 3.3 ≤x≤ 3.8 have been modeled within the rigid band approximation.

  6. In-situ ambient quantification of monoterpenes, sesquiterpenes, and related oxygenated compounds during BEARPEX 2007 – implications for gas- and particle-phase chemistry

    Directory of Open Access Journals (Sweden)

    N. C. Bouvier-Brown

    2009-04-01

    Full Text Available We quantified ambient mixing ratios of 9 monoterpenes, 6 sesquiterpenes, methyl chavicol, the oxygenated terpene linalool, and nopinone using an in-situ gas chromatograph with a quadrupole mass spectrometer (GC-MS. These measurements were a part of the 2007 Biosphere Effects on AeRosols and Photochemistry EXperiment (BEARPEX at Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. To our knowledge, these observations represent the first direct in-situ ambient quantification of the sesquiterpenes α-bergamotene, longifolene, α-farnesene, and β-farnesene. From average diurnal mixing ratio profiles, we show that α-farnesene emissions are dependent mainly on temperature whereas α-bergamotene and β-farnesene emissions are temperature- and light-dependent. The amount of sesquiterpene mass quantified above the canopy was small (averaging a total of 3.3 ppt during the day, but nevertheless these compounds contributed 8.5% to the overall ozone reactivity above the canopy. Assuming that the monoterpene-to-sesquiterpene emission rate in the canopy is similar to that observed in branch enclosure studies at the site during comparable weather conditions, and the average yield of aerosol mass from these sesquiterpenes is 10–50%, the amount of sesquiterpene mass reacted within the Blodgett Forest canopy alone accounts for 8–38% of the total organic aerosol mass measured during BEARPEX. The oxygenated monoterpene linalool was also quantified for the first time at Blodgett Forest. The linalool mass contribution was small (9.9 ppt and 0.74 ppt within and above the canopy, respectively, but it contributed 1.2% to the total ozone reactivity above the canopy. Reactive and semi-volatile compounds, especially sesquiterpenes, significantly impact the gas- and particle-phase chemistry of the atmosphere at Blodgett Forest and should be included in both biogenic volatile organic carbon emission and atmospheric chemistry models.

  7. In-situ ambient quantification of monoterpenes, sesquiterpenes, and related oxygenated compounds during BEARPEX 2007: implications for gas- and particle-phase chemistry

    Directory of Open Access Journals (Sweden)

    N. C. Bouvier-Brown

    2009-08-01

    Full Text Available We quantified ambient mixing ratios of 9 monoterpenes, 6 sesquiterpenes, methyl chavicol, the oxygenated terpene linalool, and nopinone using an in-situ gas chromatograph with a quadrupole mass spectrometer (GC-MS. These measurements were a part of the 2007 Biosphere Effects on AeRosols and Photochemistry EXperiment (BEARPEX at Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. To our knowledge, these observations represent the first direct in-situ ambient quantification of the sesquiterpenes α-bergamotene, longifolene, α-farnesene, and β-farnesene. From average diurnal mixing ratio profiles, we show that α-farnesene emissions are dependent mainly on temperature whereas α-bergamotene and β-farnesene emissions are temperature- and light-dependent. The amount of sesquiterpene mass quantified above the canopy was small (averaging a total of 3.3 ppt during the day, but nevertheless these compounds contributed 7.6% to the overall ozone-olefin loss rate above the canopy. Assuming that the monoterpene-to-sesquiterpene emission rate in the canopy is similar to that observed in branch enclosure studies at the site during comparable weather conditions, and the average yield of aerosol mass from these sesquiterpenes is 10–50%, the amount of sesquiterpene mass reacted within the Blodgett Forest canopy alone accounts for 6–32% of the total organic aerosol mass measured during BEARPEX. The oxygenated monoterpene linalool was also quantified for the first time at Blodgett Forest. The linalool mass contribution was small (9.9 ppt and 0.74 ppt within and above the canopy, respectively, but it contributed 1.1% to the total ozone-olefin loss rate above the canopy. Reactive and semi-volatile compounds, especially sesquiterpenes, significantly impact the gas- and particle-phase chemistry of the atmosphere at Blodgett Forest and should be included in both biogenic volatile organic carbon emission and atmospheric chemistry

  8. Hydrocarbon radical thermochemistry: Gas-phase ion chemistry techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ervin, Kent M. [Univ. of Nevada, Reno, NV (United States)

    2014-03-21

    Final Scientific/Technical Report for the project "Hydrocarbon Radical Thermochemistry: Gas-Phase Ion Chemistry Techniques." The objective of this project is to exploit gas-phase ion chemistry techniques for determination of thermochemical values for neutral hydrocarbon radicals of importance in combustion kinetics.

  9. Cationized Carbohydrate Gas-Phase Fragmentation Chemistry

    Science.gov (United States)

    Bythell, Benjamin J.; Abutokaikah, Maha T.; Wagoner, Ashley R.; Guan, Shanshan; Rabus, Jordan M.

    2016-11-01

    We investigate the fragmentation chemistry of cationized carbohydrates using a combination of tandem mass spectrometry, regioselective labeling, and computational methods. Our model system is D-lactose. Barriers to the fundamental glyosidic bond cleavage reactions, neutral loss pathways, and structurally informative cross-ring cleavages are investigated. The most energetically favorable conformations of cationized D-lactose were found to be similar. In agreement with the literature, larger group I cations result in structures with increased cation coordination number which require greater collision energy to dissociate. In contrast with earlier proposals, the B n -Y m fragmentation pathways of both protonated and sodium-cationized analytes proceed via protonation of the glycosidic oxygen with concerted glycosidic bond cleavage. Additionally, for the sodiated congeners our calculations support sodiated 1,6-anhydrogalactose B n ion structures, unlike the preceding literature. This affects the subsequent propensity of formation and prediction of B n /Y m branching ratio. The nature of the anomeric center (α/β) affects the relative energies of these processes, but not the overall ranking. Low-energy cross-ring cleavages are observed for the metal-cationized analytes with a retro-aldol mechanism producing the 0,2 A 2 ion from the sodiated forms. Theory and experiment support the importance of consecutive fragmentation processes, particularly for the protonated congeners at higher collision energies.

  10. Negative ion gas-phase chemistry of arenes.

    Science.gov (United States)

    Danikiewicz, Witold; Zimnicka, Magdalena

    2016-01-01

    Reactions of aromatic and heteroaromatic compounds involving anions are of great importance in organic synthesis. Some of these reactions have been studied in the gas phase and are occasionally mentioned in reviews devoted to gas-phase negative ion chemistry, but no reviews exist that collect all existing information about these reactions. This work is intended to fill this gap. In the first part of this review, methods for generating arene anions in the gas phase and studying their physicochemical properties and fragmentation reactions are presented. The main topics in this part are as follows: processes in which gas-phase arene anions are formed, measurements and calculations of the proton affinities of arene anions, proton exchange reactions, and fragmentation processes of substituted arene anions, especially phenide ions. The second part is devoted to gas-phase reactions of arene anions. The most important of these are reactions with electrophiles such as carbonyl compounds and α,β-unsaturated carbonyl and related compounds (Michael acceptors). Other reactions including oxidation of arene anions and halogenophilic reactions are also presented. In the last part of the review, reactions of electrophilic arenes with nucleophiles are discussed. The best known of these is the aromatic nucleophilic substitution (SN Ar) reaction; however, other processes that lead to the substitution of a hydrogen atom in the aromatic ring are also very important. Aromatic substrates in these reactions are usually but not always nitroarenes bearing other substituents in the ring. The first step in these reactions is the formation of an anionic σ-adduct, which, depending on the substituents in the aromatic ring and the structure of the attacking nucleophile, is either an intermediate or a transition state in the reaction path. In the present review, we attempted to collect the results of both experimental and computational studies of the aforementioned reactions conducted since the

  11. Gas-Phase Covalent And Non-Covalent Ion/ion Chemistry Of Biological Macromolecules

    OpenAIRE

    Stutzman, John Robert

    2013-01-01

    Gas-phase ion/ion chemistry involves the interaction of oppositely charged ions inside of the mass spectrometer. During this gas-phase chemistry, particle transfer (i.e., proton and electron) or synthesis can occur at rapid reaction rates. Particle transfer represents a mature area of ion/ion chemistry, while selective covalent modification represents a fairly new area of gas-phase chemistry. Gas-phase covalent chemistry is based on traditional solution phase organic chemistry. The work de...

  12. METHODOLOGICAL NOTES: Metastable phases, phase transformations, and phase diagrams in physics and chemistry

    Science.gov (United States)

    Brazhkin, Vadim V.

    2006-07-01

    Concepts of a 'phase' and a 'phase transition' are discussed for stable and metastable states of matter. While condensed matter physics primarily considers equilibrium states and treats metastable phases as exceptions, organic chemistry overwhelmingly deals with metastable states. It is emphasized that many simple light-element compounds — including most hydrocarbons; nitrogen oxides, hydrides, and carbides; carbon monoxide CO; alcohols and glycerin — are also metastable at normal pressure in the sense that they do not correspond to a minimum Gibbs free energy for a given chemical composition. At moderate temperatures and pressures, the phase transformations for these metastable phases are reversible with the fulfilment of all laws of equilibrium thermodynamics over the entire range of experimentally accessible times. At sufficiently high pressures (> 1-10 GPa), most of the metastable molecular phases irreversibly transform to lower-energy polymer phases, stable or metastable. These transitions do not correspond to the equality of the Gibbs free energy for the involved phases before and after the transition and so they are not first-order in the 'classical' sense. At normal pressure, the resulting polymer phases can exist at temperatures above the melting point of the original metastable molecular phase, as the examples of polyethylene and polymerized CO dramatically illustrate. As pressure is increased further to 20-50 GPa, the PV contribution to Gibbs free energy gives rise to stable high-density atomic phases. Many of the intermediate-energy polymer phases can likely be synthesized by methods of 'classical' chemistry at normal pressure.

  13. An overview of peat related chemistry

    OpenAIRE

    Guan, Ting

    2015-01-01

    Peat is a type of renewable resource that has usually been ignored. Nowadays, people mainly apply peat as the heating energy resource instead of other purposes. This thesis elaborates many studies such as peat used in chemistry, which were utilized by researchers, and the product has been made according to special characteristics of peat. The aim of thesis is to give a summary of the achievement of research, which had been studied of peat that applied in chemistry. Eight studies of peat- r...

  14. A Closer Look at Phase Diagrams for the General Chemistry Course.

    Science.gov (United States)

    Gramsch, Stephen A.

    2000-01-01

    Information concerning structural chemistry and phase equilibria contained in the full phase diagrams of common substances is a great deal richer than the general chemistry students are given to believe. Discusses ways of enriching the traditional presentation of phase diagrams in general chemistry courses. (Contains over 20 references.) (WRM)

  15. Gas Phase Sulfur, Chlorine and Potassium Chemistry in Biomass Combustion

    DEFF Research Database (Denmark)

    Løj, Lusi Hindiyarti

    2007-01-01

    conditions. These trace species contained in the biomass structure will be released to the gas phase during combustion and contribute to the problems generated during the process. The investigation during this PhD project is done to stepwise improve the understanding in the chemistry and reduce...... between K-containing species and radical pool under combustion conditions has been improved. The available K/O/H/Cl chemistry has been updated by using both experimental work and detailed kinetic modeling. The experimental work was done by introducing gaseous KCl to CO oxidation system under reducing...... conditions. The experiments were performed using a laboratory flow reactor at atmospheric pressure and temperatures in the range of 773-1373 K, varying the CO inlet concentration and the KCl level. The addition of KCl results in a strong inhibition of the CO oxidation. The inhibition increases with the KCl...

  16. Chemistry in a forming protoplanetary disk: main accretion phase

    CERN Document Server

    Yoneda, Haruaki; Furuya, Kenji; Aikawa, Yuri

    2016-01-01

    We investigate the chemistry in a radiation-hydrodynamics model of star-forming core which evolves from a cold ($\\sim 10$ K) prestellar core to the main accretion phase in $\\sim 10^5$ yr. A rotationally-supported gravitationally unstable disk is formed around a protostar. We extract the temporal variation of physical parameters in $\\sim 1.5 \\times 10^3$ SPH particles which end up in the disk, and perform post-processing calculations of the gas-grain chemistry adopting a three-phase model. Inside the disk, the SPH particles migrate both inward and outward. Since a significant fraction of volatiles such as CO can be trapped in the water-dominant ice in the three-phase model, the ice mantle composition depends not only on the current position in the disk but also on whether the dust grain has ever experienced higher temperatures than the water sublimation temperature. Stable molecules such as H$_2$O, CH$_4$, NH$_3$ and CH$_3$OH are already abundant at the onset of gravitational collapse and simply sublimated as ...

  17. Phase equilibria and crystal chemistry of rubidium niobates and rubidium tantalates

    Science.gov (United States)

    Minor, D. B.; Roth, R. S.; Parker, H. S.; Brower, W. S.

    1977-01-01

    The phase equilibria relations and crystal chemistry of portions of the Rb2O-Nb2O5 and Rb2O-Ta2O5 systems were investigated for structures potentially useful as ionic conductors. A hexagonal tungsten bronze-type (HTB) structure was found in both systems as well as three hexagonal phases with mixed HTB-pyrochlore type structures. Ion exchange experiments between various alkali ions are described for several phases. Unit cell dimensions and X-ray diffraction powder patterns are reported.

  18. Chemistry in a Forming Protoplanetary Disk: Main Accretion Phase

    Science.gov (United States)

    Yoneda, Haruaki; Tsukamoto, Yusuke; Furuya, Kenji; Aikawa, Yuri

    2016-12-01

    We investigate the chemistry in a radiation-hydrodynamics model of a star-forming core that evolves from a cold (∼10 K) prestellar core to the main accretion phase in ∼105 years. A rotationally supported gravitationally unstable disk is formed around a protostar. We extract the temporal variation of physical parameters in ∼1.5 × 103 SPH particles that end up in the disk, and perform post-processing calculations of the gas-grain chemistry adopting a three-phase model. Inside the disk, the SPH particles migrate both inward and outward. Since a significant fraction of volatiles such as CO can be trapped in the water-dominant ice in the three-phase model, the ice mantle composition depends not only on the current position in the disk, but also on whether the dust grain has ever experienced higher temperatures than the water sublimation temperature. Stable molecules such as H2O, CH4, NH3, and CH3OH are already abundant at the onset of gravitational collapse and are simply sublimated as the fluid parcels migrate inside the water snow line. On the other hand, various molecules such as carbon chains and complex organic molecules (COMs) are formed in the disk. The COMs abundance sensitively depends on the outcomes of photodissociation and diffusion rates of photofragments in bulk ice mantle. As for S-bearing species, H2S ice is abundant in the collapse phase. In the warm regions in the disk, H2S is sublimated to be destroyed, while SO, H2CS, OCS, and SO2 become abundant.

  19. REACTION CHEMISTRY RELATED TO FCC GASOLINE QUALITY

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    About 80% of the gasoline pool as a whole in China for supplying the domestic market at current stage directly originates from FCC units. Obviously, FCC gasoline quality is critical for refiners to meet the nations more and more stringent gasoline specifications. FCC process is expected to produce gasoline with reduced contents of olefins, aromatics, benzene, sulfur, and, contradictorily, still with high octane number.   Catalytic cracking process involves a series of acid catalyzed reactions. Bronsted acid sites dominate the surface of the catalyst used for FCC process. All the reactions of hydrocarbons in FCC process are based on carbonium ions of penta-coordinated, or carbenium ions of tri-coordinated. The monomolecular beta scission mechanism for alkane cracking explains that the cracking of carbon-carbon bonding occurs at the beta position to the carbon atom bearing positive charge, and hence forms two small hydrocarbon molecules: one alkane molecule and one olefin molecule. The molar ratio of alkane to olefin for the primary cracking product will be 1 and it will be less than 1 if the cracking reaction proceeds.   However, it is proved that bimolecular reaction pathways exist between surface carbenium ions and the feed molecules. The products of this bimolecular disproportionation reaction could be an alkane molecule and a newly formed carbenium ion. The better understanding of the reaction chemistry of FCC process based on monomolecular pathways and bimolecular pathways should be the basis for searching approaches to the improvement of FCC gasoline quality. In the complicated reaction scheme of the FCC process, the isomerization reaction leading to the formation of iso-alkanes is obviously a target reaction, which favors both olefin reduction and octane enhancement.   The cracking of small paraffin molecules, due to its limited number of reaction pathways and products, has been used to investigate cracking mechanism. In the present work the

  20. The Iron-Iron Carbide Phase Diagram: A Practical Guide to Some Descriptive Solid State Chemistry.

    Science.gov (United States)

    Long, Gary J.; Leighly, H. P., Jr.

    1982-01-01

    Discusses the solid state chemistry of iron and steel in terms of the iron-iron carbide phase diagram. Suggests that this is an excellent way of introducing the phase diagram (equilibrium diagram) to undergraduate students while at the same time introducing the descriptive solid state chemistry of iron and steel. (Author/JN)

  1. CuAAC: An Efficient Click Chemistry Reaction on Solid Phase.

    Science.gov (United States)

    Castro, Vida; Rodríguez, Hortensia; Albericio, Fernando

    2016-01-11

    Click chemistry is an approach that uses efficient and reliable reactions, such as Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC), to bind two molecular building blocks. CuAAC has broad applications in medicinal chemistry and other fields of chemistry. This review describes the general features and applications of CuAAC in solid-phase synthesis (CuAAC-SP), highlighting the suitability of this kind of reaction for peptides, nucleotides, small molecules, supramolecular structures, and polymers, among others. This versatile reaction is expected to become pivotal for meeting future challenges in solid-phase chemistry.

  2. Crystal chemistry of sartorite homologues and related sulfosalts

    DEFF Research Database (Denmark)

    Berlepsch, Peter; Makovicky, Emil; Balic-Zunic, Tonci

    2001-01-01

    sartorite homologues, sulfosalt, crystal chemistry, coordination polyhedra, bond-pairs, crankshaft chains......sartorite homologues, sulfosalt, crystal chemistry, coordination polyhedra, bond-pairs, crankshaft chains...

  3. Ion chemistry and gas-phase basicity of nickelocene by ion cyclotron resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Corderman, R.R.; Beauchamp, J.L.

    1976-01-01

    The gas-phase ion chemistry of bis(eta/sup 5/-cyclopentadienyl)nickel(nickelocene) is studied using the techniques of ion cyclotron resonance spectroscopy. Total rate constants for the reactions of the primary fragment ions at 70 eV are determined using trapped-ion methods. The long-lived nickelocene anion, Ni(C/sub 5/H/sub 5/)/sub 2//sup -/, is formed directly by electron attachment and is unreactive with a variety of simple molecules. Nickelocene is observed to be an exceptionally strong base in the gas phase. Equilibrium proton-transfer reactions are observed in mixtures of nickelocene with (CH/sub 3/)/sub 3/N and (C/sub 2/H/sub 5/)/sub 2/NH, from which the gas-phase basicity or proton affinity (PA) is determined to be 218.9 +- 1.0 kcal/mol relative to PA(NH/sub 3/) = 201 +- 1 kcal/mol. Attempts to determine the site of protonation were inconclusive. The ion chemistry and base strength of nickelocene and ferrocene are compared. 39 references, 2 figures, 3 tables.

  4. Ion chemistry and gas-phase basicity of nickelocene by ion cyclotron resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Corderman, R.D.; Beauchamp, J.L.

    1976-03-01

    The gas-phase ion chemistry of bis(eta/sup 5/-cyclopentadienyl)nickel (nickelocene) is studied using the techniques of ion cyclotron resonance spectroscopy. Total rate constants for the reactions of the primary fragment ions at 70 eV are determined using trapped-ion methods. The long-lived nickelocene anion, Ni(C/sub 5/H/sub 5/)/sub 2//sup -/, is formed directly by electron attachment and is unreactive with a variety of simple molecules. Nickelocene is observed to be an exceptionally strong base in the gas phase. Equilibrium proton-transfer reactions are observed in mixtures of nickelocene with (CH/sub 3/)/sub 3/N and (C/sub 2/H/sub 5/)/sub 2/NH, from which the gas-phase basicity or proton affinity (PA) is determined to be 218.9 +- 1.0 kcal/mol relative to PA(NH/sub 3/) = 201 +- 1 kcal/mol. Attempts to determine the site of protonation were inconclusive. The ion chemistry and base strength of nickelocene and ferrocene are compared. (auth)

  5. Nonclassicality in phase-number uncertainty relations

    Energy Technology Data Exchange (ETDEWEB)

    Matia-Hernando, Paloma; Luis, Alfredo [Departamento de Optica, Facultad de Ciencias Fisicas, Universidad Complutense, 28040 Madrid (Spain)

    2011-12-15

    We show that there are nonclassical states with lesser joint fluctuations of phase and number than any classical state. This is rather paradoxical since one would expect classical coherent states to be always of minimum uncertainty. The same result is obtained when we replace phase by a phase-dependent field quadrature. Number and phase uncertainties are assessed using variance and Holevo relation.

  6. Recent developments and future trends in solid phase microextraction techniques towards green analytical chemistry.

    Science.gov (United States)

    Spietelun, Agata; Marcinkowski, Łukasz; de la Guardia, Miguel; Namieśnik, Jacek

    2013-12-20

    Solid phase microextraction find increasing applications in the sample preparation step before chromatographic determination of analytes in samples with a complex composition. These techniques allow for integrating several operations, such as sample collection, extraction, analyte enrichment above the detection limit of a given measuring instrument and the isolation of analytes from sample matrix. In this work the information about novel methodological and instrumental solutions in relation to different variants of solid phase extraction techniques, solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE) and magnetic solid phase extraction (MSPE) is presented, including practical applications of these techniques and a critical discussion about their advantages and disadvantages. The proposed solutions fulfill the requirements resulting from the concept of sustainable development, and specifically from the implementation of green chemistry principles in analytical laboratories. Therefore, particular attention was paid to the description of possible uses of novel, selective stationary phases in extraction techniques, inter alia, polymeric ionic liquids, carbon nanotubes, and silica- and carbon-based sorbents. The methodological solutions, together with properly matched sampling devices for collecting analytes from samples with varying matrix composition, enable us to reduce the number of errors during the sample preparation prior to chromatographic analysis as well as to limit the negative impact of this analytical step on the natural environment and the health of laboratory employees.

  7. Characterization of five chemistries and three particle sizes of stationary phases used in supercritical fluid chromatography.

    Science.gov (United States)

    Khater, S; West, C; Lesellier, E

    2013-12-06

    Sub-2-microns particles employed as supporting phases are known to favor column efficiency. Recently a set of columns based on sub-2-microns particles for use with supercritical fluid mobile phases have been introduced by Waters. Five different stationary phase chemistries are available: BEH silica, BEHEthyl-pyridine, X Select CSH Fluorophenyl, HSS C18 SB and BEH Shield RP18. This paper describes the characterization of 15 stationary phases, the five different chemistries, and three particle sizes, 1.7 (or 1.8), 3.5 and 5 microns, with the same carbon dioxide–methanol mobile phase and a set of more than a hundred compounds. The interactions established in the 15 different chromatographic systems used in supercritical fluid chromatography (SFC) are assessed with linear solvation energy relationships (LSERs).The results show the good complementarity of the five column chemistries, and their comparative location inside a classification map containing today around 70 different commercial phases. Among the five different chemistries, the HSS C18 SB phase displays a rather unusual behavior in regards of classical C18 phases, as it displays significant hydrogen–bonding interactions. Besides, it appears, as expected, that the BEH Ethyl–pyridine phase has weak interactions with basic compounds. The effect of particle size was studied because smaller particles induce increased inlet and internal pressure. For compressible fluids,this pressure change modifies the fluid density, i.e. the apparent void volume and the eluting strength.These changes could modify the retention and the selectivity of compounds in the case of method trans-fer, by using different particle sizes, from 5 down to 1.7 m. A hierarchical cluster analysis shows that stationary phase clusters were based on the phase chemistry rather than on the particle size, meaning that method transfer from 5 to 1.7 microns can be achieved in the subcritical domain i.e. by using a weakly compressible fluid.

  8. Generation of naphthoquinone radical anions by electrospray ionization: solution, gas-phase, and computational chemistry studies.

    Science.gov (United States)

    Vessecchi, Ricardo; Naal, Zeki; Lopes, José N C; Galembeck, Sérgio E; Lopes, Norberto P

    2011-06-02

    Radical anions are present in several chemical processes, and understanding the reactivity of these species may be described by their thermodynamic properties. Over the last years, the formation of radical ions in the gas phase has been an important issue concerning electrospray ionization mass spectrometry studies. In this work, we report on the generation of radical anions of quinonoid compounds (Q) by electrospray ionization mass spectrometry. The balance between radical anion formation and the deprotonated molecule is also analyzed by influence of the experimental parameters (gas-phase acidity, electron affinity, and reduction potential) and solvent system employed. The gas-phase parameters for formation of radical species and deprotonated species were achieved on the basis of computational thermochemistry. The solution effects on the formation of radical anion (Q(•-)) and dianion (Q(2-)) were evaluated on the basis of cyclic voltammetry analysis and the reduction potentials compared with calculated electron affinities. The occurrence of unexpected ions [Q+15](-) was described as being a reaction between the solvent system and the radical anion, Q(•-). The gas-phase chemistry of the electrosprayed radical anions was obtained by collisional-induced dissociation and compared to the relative energy calculations. These results are important for understanding the formation and reactivity of radical anions and to establish their correlation with the reducing properties by electrospray ionization analyses.

  9. Development and evaluation of the aerosol dynamic and gas phase chemistry model ADCHEM

    Directory of Open Access Journals (Sweden)

    P. Roldin

    2010-08-01

    Full Text Available The aim of this work was to develop a model ideally suited for detailed studies on aerosol dynamics, gas and particle phase chemistry within urban plumes, from local scale (1×1 km2 to regional or global scale. This article describes and evaluates the trajectory model for Aerosol Dynamics, gas and particle phase CHEMistry and radiative transfer (ADCHEM, which has been developed and used at Lund University since 2007. The model treats both vertical and horizontal dispersion perpendicular to an air mass trajectory (2-space dimensions, which is not treated in Lagrangian box-models (0-space dimensions. The Lagrangian approach enables a more detailed representation of the aerosol dynamics, gas and particle phase chemistry and a finer spatial and temporal resolution compared to that of available regional 3D-CTMs. These features make it among others ideally suited for urban plume studies. The aerosol dynamics model includes Brownian coagulation, dry deposition, wet deposition, in-cloud processing, condensation, evaporation, primary particle emissions and homogeneous nucleation. The gas phase chemistry model calculates the gas phase concentrations of 63 different species, using 119 different chemical reactions. Daily isoprene and monoterpene emissions from European forests were simulated separately with the vegetation model LPJ-GUESS, and included as input to ADCHEM. ADCHEM was used to simulate the ageing of the urban plumes from the city of Malmö in Southern Sweden (280 000 inhabitants. Several sensitivity tests were performed concerning the number of size bins, size structure method, coupled or uncoupled condensation, the volatility basis set (VBS or traditional 2-product model for secondary organic aerosol formation, different aerosol dynamic processes and vertical and horizontal mixing. The simulations show that the full-stationary size structure gives accurate results with little numerical diffusion when more than 50 size bins are used

  10. General Chemistry Students' Understanding of Climate Change and the Chemistry Related to Climate Change

    Science.gov (United States)

    Versprille, Ashley N.; Towns, Marcy H.

    2015-01-01

    While much is known about secondary students' perspectives of climate change, rather less is known about undergraduate students' perspectives. The purpose of this study is to investigate general chemistry students' understanding of the chemistry underlying climate change. Findings that emerged from the analysis of the 24 interviews indicate that…

  11. Nucleic acid chemistry in the organic phase: from functionalized oligonucleotides to DNA side chain polymers.

    Science.gov (United States)

    Liu, Kai; Zheng, Lifei; Liu, Qing; de Vries, Jan Willem; Gerasimov, Jennifer Y; Herrmann, Andreas

    2014-10-08

    DNA-incorporating hydrophobic moieties can be synthesized by either solid-phase or solution-phase coupling. On a solid support the DNA is protected, and hydrophobic units are usually attached employing phosphoramidite chemistry involving a DNA synthesizer. On the other hand, solution coupling in aqueous medium results in low yields due to the solvent incompatibility of DNA and hydrophobic compounds. Hence, the development of a general coupling method for producing amphiphilic DNA conjugates with high yield in solution remains a major challenge. Here, we report an organic-phase coupling strategy for nucleic acid modification and polymerization by introducing a hydrophobic DNA-surfactant complex as a reactive scaffold. A remarkable range of amphiphile-DNA structures (DNA-pyrene, DNA-triphenylphosphine, DNA-hydrocarbon, and DNA block copolymers) and a series of new brush-type DNA side-chain homopolymers with high DNA grafting density are produced efficiently. We believe that this method is an important breakthrough in developing a generalized approach to synthesizing functional DNA molecules for self-assembly and related technological applications.

  12. Gas-phase chemistry of element 114, flerovium

    Directory of Open Access Journals (Sweden)

    Yakushev Alexander

    2016-01-01

    Full Text Available Element 114 was discovered in 2000 by the Dubna-Livermore collaboration, and in 2012 it was named flerovium. It belongs to the group 14 of the periodic table of elements. A strong relativistic stabilisation of the valence shell 7s27p21/2 is expected due to the orbital splitting and the contraction not only of the 7s2 but also of the spherical 7p21/2 closed subshell, resulting in the enhanced volatility and inertness. Flerovium was studied chemically by gas-solid chromatography upon its adsorption on a gold surface. Two experimental results on Fl chemistry have been published so far. Based on observation of three atoms, a weak interaction of flerovium with gold was suggested in the first study. Authors of the second study concluded on the metallic character after the observation of two Fl atoms deposited on gold at room temperature.

  13. Gas-phase chemistry of element 114, flerovium

    Science.gov (United States)

    Yakushev, Alexander; Eichler, Robert

    2016-12-01

    Element 114 was discovered in 2000 by the Dubna-Livermore collaboration, and in 2012 it was named flerovium. It belongs to the group 14 of the periodic table of elements. A strong relativistic stabilisation of the valence shell 7s27p is expected due to the orbital splitting and the contraction not only of the 7s2 but also of the spherical 7p closed subshell, resulting in the enhanced volatility and inertness. Flerovium was studied chemically by gas-solid chromatography upon its adsorption on a gold surface. Two experimental results on Fl chemistry have been published so far. Based on observation of three atoms, a weak interaction of flerovium with gold was suggested in the first study. Authors of the second study concluded on the metallic character after the observation of two Fl atoms deposited on gold at room temperature.

  14. Preparation of novel chiral stationary phase based on click chemistry for ligand exchange chromatography

    Institute of Scientific and Technical Information of China (English)

    Chun Mei Fu; Hong Yu Shi; Guang Sheng Qian; Zhang Wan Li

    2009-01-01

    Click chemistry was applied to immobilize L-proline derivative onto azide-modified silica gel to give a novel chiral stationary phase (denoted as click-CSP) for ligand exchange chromatography. The developed protocol combines the benefits of operational simplicity, exceptionally mild conditions and high surface loadings. The enantioselectivity α of some DE-amino acids on the click-CSP were found to be in the range from 1.13 to 3.46. The chromatographic resolutions of some DL-amino acids and the stability study firmly illustrate the potential of click chemistry for preparation chiral stationary phase for ligand exchange chromatography.

  15. Pre-analytical phase in clinical chemistry laboratory

    Directory of Open Access Journals (Sweden)

    Neogi SS

    2016-07-01

    Full Text Available The laboratory testing process is divided into the pre-analytical, analytical and post-analytical phases. For obtaining reliable test results, the prevention and detection of errors at all steps is required. While analytical standards have been developed by recognized quality control criteria, there is a scarcity in the development of standards for the preanalytical phase. This phase is most prone to errors as the steps involved are directly dependent on humans and are out of direct control of the laboratory. Such errors in preanalytical stage often only become apparent in the analytical or post-analytical phase. The development of a pre-analytical quality manual is essential in achieving total quality control. Correct practices and strategies of error prevention can reduce preanalytical errors. This review focuses on prevention of pre-analytical errors that occur while collecting a specimen of blood, urine and cerebrospinal fluid. Most of these can be easily prevented with understanding and education of the personnel involved in and responsible for executing this crucial pre-analytical phase.

  16. Understanding Gas-Phase Ammonia Chemistry in Protoplanetary Disks

    Science.gov (United States)

    Chambers, Lauren; Oberg, Karin I.; Cleeves, Lauren Ilsedore

    2017-01-01

    Protoplanetary disks are dynamic regions of gas and dust around young stars, the remnants of star formation, that evolve and coagulate over millions of years in order to ultimately form planets. The chemical composition of protoplanetary disks is affected by both the chemical and physical conditions in which they develop, including the initial molecular abundances in the birth cloud, the spectrum and intensity of radiation from the host star and nearby systems, and mixing and turbulence within the disk. A more complete understanding of the chemical evolution of disks enables a more complete understanding of the chemical composition of planets that may form within them, and of their capability to support life. One element known to be essential for life on Earth is nitrogen, which often is present in the form of ammonia (NH3). Recent observations by Salinas et al. (2016) reveal a theoretical discrepancy in the gas-phase and ice-phase ammonia abundances in protoplanetary disks; while observations of comets and protostars estimate the ice-phase NH3/H2O ratio in disks to be 5%, Salinas reports a gas-phase NH3/H2O ratio of ~7-84% in the disk surrounding TW Hydra, a young nearby star. Through computational chemical modeling of the TW Hydra disk using a reaction network of over 5000 chemical reactions, I am investigating the possible sources of excess gas-phase NH3 by determining the primary reaction pathways of NH3 production; the downstream chemical effects of ionization by ultraviolet photons, X-rays, and cosmic rays; and the effects of altering the initial abundances of key molecules such as N and N2. Beyond providing a theoretical explanation for the NH3 ice/gas discrepancy, this new model may lead to fuller understanding of the gas-phase formation processes of all nitrogen hydrides (NHx), and thus fuller understanding of the nitrogen-bearing molecules that are fundamental for life as we know it.

  17. Application of acute phase protein measurements in veterinary clinical chemistry

    DEFF Research Database (Denmark)

    Petersen, Henning; Nielsen, J. P.; Heegaard, Peter M. H.

    2004-01-01

    The body's early defence in response to trauma, inflammation or infection, the acute phase response, is a complex set of systemic reactions seen shortly after exposure to a triggering event. One of the many components is an acute phase protein response in which increased hepatic synthesis leads t...... A and their possible use as non-specific indicators of health in large animal veterinary medicine such as in the health status surveillance of pigs at the herd level, for the detection of mastitis in dairy cattle and for the prognosis of respiratory diseases in horses....

  18. Phase Chemistry of the Complexes of RE Amino Acids

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Forty-three phase diagrams of ternary system concerning rare earth salts, α-amino acids and water, which were constructed by phase equilibrium methods, were expounded. The influences of the factors such as cations, anions, the structure of amino acids, temperature on the phase diagrams were discussed. Under the guidance of phase equilibrium results, over 150 new solid complexes were prepared. IR, reflecting, UV, FS, and Raman spectra for these complexes were investigated and the regularity of “tripartite effect”, “tetrad effect”, “Nephelanxetic effect”, “Oddo-Harkins” was observed. Thermal decomposition processes of the complexes were confirmed. Based on the comparison with the known crystal structures of rare earth-amino acid-complexes, an estimation method for predicting the crystal structure data of series complexes was founded. The constant volume combustion energies of the complexes were determined by RBC-1 type rotating bomb calorimeter. The standard enthalpies of combustion and standard enthalpies of formation were calculated for these complexes.

  19. Gender Differences in Cognitive and Noncognitive Factors Related to Achievement in Organic Chemistry

    Science.gov (United States)

    Turner, Ronna C.; Lindsay, Harriet A.

    2003-05-01

    For many college students in the sciences, organic chemistry poses a difficult challenge. Indeed, success in organic chemistry has proven pivotal in the careers of a vast number of students in a variety of science disciplines. A better understanding of the factors that contribute to achievement in this course should contribute to efforts to increase the number of students in the science disciplines. Further, an awareness of gender differences in factors associated with achievement should aid efforts to bolster the participation of women in chemistry and related disciplines. Using a correlation research design, the individual relationships between organic chemistry achievement and each of several cognitive variables and noncognitive variables were assessed. In addition, the relationships between organic chemistry achievement and combinations of these independent variables were explored. Finally, gender- and instructor-related differences in the relationships between organic chemistry achievement and the independent variables were investigated. Cognitive variables included the second-semester general chemistry grade, the ACT English, math, reading, and science-reasoning scores, and scores from a spatial visualization test. Noncognitive variables included anxiety, confidence, effectance motivation, and usefulness. The second-semester general chemistry grade was found to be the best indicator of performance in organic chemistry, while the effectiveness of other predictors varied between instructors. In addition, gender differences were found in the explanations of organic chemistry achievement variance provided by this study. In general, males exhibited stronger correlations between predictor variables and organic chemistry achievement than females.

  20. Evolution of Jupiter's auroral-related stratospheric heating and chemistry

    Science.gov (United States)

    Sinclair, James; Orton, Glenn S.; Greathouse, Thomas K.; Fletcher, Leigh N.; Moses, Julianne I.; Hue, Vincent; Irwin, Patrick Gerard Joseph; Melin, Henrik; Giles, Rohini Sara

    2016-10-01

    Auroral processes on Jupiter are evident over a large range of wavelengths. Emission at X-ray, UV and near-infrared wavelengths highlights the precipitation of charged particles in Jupiter's ionosphere. Jupiter's auroral regions also exhibit enhanced mid-infrared emission of CH4 (7.8-μm), C2H2 (13-μm), C2H4 (10.5-μm) and C2H6 (12.2-μm), which indicates auroral processes modify the thermal structure and chemistry of the neutral stratosphere at pressures from 10 mbar to 10 μbar. In Sinclair et al., 2016a (submitted), 2016b (in preparation), we investigated these processes further by performing a retrieval analysis of Voyager-IRIS (Infrared Interferometer Spectrometer) observations measured in November 1979, Cassini-CIRS (Composite Infrared Spectrometer) observations measured in January 2001 and IRTF-TEXES (Texas Echelon Cross Echelle Spectrograph on NASA's Infrared Telescope Facility) spectra measured in December 2014. These datasets however captured Jupiter at significantly different epochs and thus the overall global evolution of atmospheric conditions as well as differences in spatial sampling, spectral resolution (and therefore vertical resolution in the atmosphere) have made inferences of the temporal evolution in auroral regions a challenge. However, in April 2016, we acquired IRTF-TEXES observations of Jupiter's high latitudes, using observing parameters very similar to those in December 2014. By performing a similar analysis of these observations and comparing results between December 2014 and April 2016, we can investigate the evolution of the thermal structure and chemistry in Jupiter's auroral regions over a 15 month timescale. The magnitude of temperature/composition changes and the altitudes at which they occur will provide insights into how auroral processes in the ionosphere propagate to the stratosphere. In particular, we can assess whether the evolution of stratospheric conditions in auroral regions is related to the decrease in solar activity

  1. An advanced scheme for wet scavenging and liquid-phase chemistry in a regional online-coupled chemistry transport model

    Science.gov (United States)

    Knote, C.; Brunner, D.

    2012-10-01

    Clouds are reaction chambers for atmospheric trace gases and aerosols, and the associated precipitation is a major sink for atmospheric constituents. The regional chemistry-climate model COSMO-ART has been lacking a description of wet scavenging of gases and aqueous-phase chemistry. In this work we present a coupling of COSMO-ART with a wet scavenging and aqueous-phase chemistry scheme. The coupling is made consistent with the cloud microphysics scheme of the underlying meteorological model COSMO. While the choice of the aqueous-chemistry mechanism is flexible, the effects of a simple sulfur oxidation scheme are shown in the application of the coupled system in this work. We give details explaining the coupling and extensions made, then present results from idealized flow-over-hill experiments in a 2-D model setup and finally results from a full 3-D simulation. Comparison against measurement data shows that the scheme efficiently reduces SO2 trace gas concentrations by 0.3 ppbv (-30%) on average, while leaving O3 and NOx unchanged. PM10 aerosol mass, which has been overestimated previously, is now in much better agreement with measured values due to a stronger scavenging of coarse particles. While total PM2.5 changes only little, chemical composition is improved notably. Overestimations of nitrate aerosols are reduced by typically 0.5-1 μg m-3 (up to -2 μg m-3 in the Po Valley) while sulfate mass is increased by 1-1.5 μg m-3 on average (up to 2.5 μg m-3 in Eastern Europe). The effect of cloud processing of aerosols on its size distribution, i. e. a shift towards larger diameters, is observed. Compared against wet deposition measurements the system underestimates the total wet deposited mass for the simulated case study. We find that while evaporation of cloud droplets dominates in higher altitudes, evaporation of precipitation can contribute up to 50% of total evaporated mass near the surface.

  2. An advanced scheme for wet scavenging and liquid-phase chemistry in a regional online-coupled chemistry transport model

    Directory of Open Access Journals (Sweden)

    C. Knote

    2012-10-01

    Full Text Available Clouds are reaction chambers for atmospheric trace gases and aerosols, and the associated precipitation is a major sink for atmospheric constituents. The regional chemistry-climate model COSMO-ART has been lacking a description of wet scavenging of gases and aqueous-phase chemistry. In this work we present a coupling of COSMO-ART with a wet scavenging and aqueous-phase chemistry scheme. The coupling is made consistent with the cloud microphysics scheme of the underlying meteorological model COSMO. While the choice of the aqueous-chemistry mechanism is flexible, the effects of a simple sulfur oxidation scheme are shown in the application of the coupled system in this work. We give details explaining the coupling and extensions made, then present results from idealized flow-over-hill experiments in a 2-D model setup and finally results from a full 3-D simulation. Comparison against measurement data shows that the scheme efficiently reduces SO2 trace gas concentrations by 0.3 ppbv (−30% on average, while leaving O3 and NOx unchanged. PM10 aerosol mass, which has been overestimated previously, is now in much better agreement with measured values due to a stronger scavenging of coarse particles. While total PM2.5 changes only little, chemical composition is improved notably. Overestimations of nitrate aerosols are reduced by typically 0.5–1 μg m−3 (up to −2 μg m−3 in the Po Valley while sulfate mass is increased by 1–1.5 μg m−3 on average (up to 2.5 μg m−3 in Eastern Europe. The effect of cloud processing of aerosols on its size distribution, i. e. a shift towards larger diameters, is observed. Compared against wet deposition measurements the system underestimates the total wet deposited mass for the simulated case study. We find that while evaporation of cloud droplets dominates in higher altitudes, evaporation of precipitation can

  3. Combination of organotrifluoroborates with photoredox catalysis marking a new phase in organic radical chemistry.

    Science.gov (United States)

    Koike, Takashi; Akita, Munetaka

    2016-08-01

    Combination of organotrifluoroborates and visible-light-driven photoredox catalysis, both of which have attracted the attention of synthetic chemists, marks a new phase in the field of organic radical chemistry. We have developed photoredox-catalyzed radical reactions with organotrifluoroborates, which turn out to serve not only as a source of organic radicals but also as radical acceptors. The first part of this Perspective deals with the generation of organic radicals from organotrifluoroborates, and the latter part describes addition of the CF3 radical to alkenyltrifluoroborates. The good chemistry between organoborates and photoredox catalysis and its future will be discussed.

  4. Positive phase space distributions and uncertainty relations

    Science.gov (United States)

    Kruger, Jan

    1993-01-01

    In contrast to a widespread belief, Wigner's theorem allows the construction of true joint probabilities in phase space for distributions describing the object system as well as for distributions depending on the measurement apparatus. The fundamental role of Heisenberg's uncertainty relations in Schroedinger form (including correlations) is pointed out for these two possible interpretations of joint probability distributions. Hence, in order that a multivariate normal probability distribution in phase space may correspond to a Wigner distribution of a pure or a mixed state, it is necessary and sufficient that Heisenberg's uncertainty relation in Schroedinger form should be satisfied.

  5. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation.

    Science.gov (United States)

    Shiraiwa, Manabu; Yee, Lindsay D; Schilling, Katherine A; Loza, Christine L; Craven, Jill S; Zuend, Andreas; Ziemann, Paul J; Seinfeld, John H

    2013-07-16

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality, and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosols (SOAs). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multigeneration gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface, and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a midexperiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. Although experiments need to be conducted with other SOA precursor hydrocarbons, current results demonstrate coupling between particle-phase chemistry and size distribution dynamics in the formation of SOAs, thereby opening up an avenue for analysis of the SOA formation process.

  6. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume III ? gas phase reactions of inorganic halogens

    OpenAIRE

    Atkinson, R.; Baulch, D. L.; Cox, R A; J. N. Crowley; Hampson, R. F.; Hynes, R. G.; Jenkin, M. E.; M. J. Rossi; Troe, J.

    2007-01-01

    International audience; This article, the third in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of inorganic halogen species, which were last published in J. Phys. Chem. Ref. Data, in 2000 (Atkinson et al., 2000), were updated on the IUPAC website in 2003 and are updated again in the present evaluation. The article consists of a summary sheet...

  7. Is coccolithophore distribution in the Mediterranean Sea related to seawater carbonate chemistry?

    Science.gov (United States)

    Oviedo, A.; Ziveri, P.; Álvarez, M.; Tanhua, T.

    2015-01-01

    The Mediterranean Sea is considered a "hot spot" for climate change, being characterized by oligotrophic to ultra-oligotrophic waters and rapidly increasing seasurface temperature and changing carbonate chemistry. Coccolithophores are considered a dominant phytoplankton group in these waters. As marine calcifying organisms they are expected to respond to the ongoing changes in seawater carbonate chemistry. We provide here a description of the springtime coccolithophore distribution in the Mediterranean Sea and relate this to a broad set of in situ-measured environmental variables. Samples were taken during the R/V Meteor (M84/3) oceanographic cruise in April 2011, between 0 and 100 m water depth from 28 stations. Total diatom and silicoflagellate cell concentrations are also presented. Our results highlight the importance of seawater carbonate chemistry, especially [CO32-] but also [PO43-] in unraveling the distribution of heterococcolithophores, the most abundant coccolithophore life phase. Holo- and heterococcolithophores respond differently to environmental factors. For instance, changes in heterococcolithophore assemblages were best linked to the combination of [CO32-], pH, and salinity (ρ = 0.57), although salinity might be not functionally related to coccolithophore assemblage distribution. Holococcolithophores, on the other hand, showed higher abundances and species diversity in oligotrophic areas (best fit, ρ = 0.32 for nutrients), thriving in nutrient-depleted waters. Clustering of heterococcolithophores revealed three groups of species sharing more than 65% similarities. These clusters could be assigned to the eastern and western basins and deeper layers (below 50 m), respectively. In addition, the species Gephyrocapsa oceanica, G. muellerae, and Emiliania huxleyi morphotype B/C are spatially distributed together and trace the influx of Atlantic waters into the Mediterranean Sea. The results of the present work emphasize the importance of considering

  8. Factors related to achievement in sophomore organic chemistry at the University of Arkansas

    Science.gov (United States)

    Lindsay, Harriet Arlene

    The purpose of this study was to identify the significant cognitive and non-cognitive variables that related to achievement in the first semester of organic chemistry at the University of Arkansas. Cognitive variables included second semester general chemistry grade, ACT composite score, ACT English, mathematics, reading, and science reasoning subscores, and spatial ability. Non-cognitive variables included anxiety, confidence, effectance motivation, and usefulness. Using a correlation research design, the individual relationships between organic chemistry achievement and each of the cognitive variables and non-cognitive variables were assessed. In addition, the relationships between organic chemistry achievement and combinations of these independent variables were explored. Finally, gender- and instructor-related differences in the relationships between organic chemistry achievement and the independent variables were investigated. The samples consisted of volunteers from the Fall 1999 and Fall 2000 sections of Organic Chemistry I at the University of Arkansas. All students in each section were asked to participate. Data for spatial ability and non-cognitive independent variables were collected using the Purdue Visualization of Rotations test and the modified Fennema-Sherman Attitude Scales. Data for other independent variables, including ACT scores and second semester general chemistry grades, were obtained from the Office of Institutional Research. The dependent variable, organic chemistry achievement, was measured by each student's accumulated points in the course and consisted of scores on quizzes and exams in the lecture section only. These totals were obtained from the lecture instructor at the end of each semester. Pearson correlation and stepwise multiple regression analyses were used to measure the relationships between organic chemistry achievement and the independent variables. Prior performance in chemistry as measured by second semester general

  9. Extending atomistic scale chemistry to mesoscale model of condensed-phase deflagration

    Science.gov (United States)

    Joshi, Kaushik; Chaudhuri, Santanu

    2017-01-01

    Predictive simulations connecting chemistry that follow the shock or thermal initiation of energetic materials to subsequent deflagration or detonation events is currently outside the realm of possibilities. Molecular dynamics and first-principles based dynamics have made progress in understanding reactions in picosecond to nanosecond time scale. Results from thermal ignition of different phases of RDX show a complex reaction network and emergence of a deterministic behavior for critical temperature before ignition and hot spot growth rates. The kinetics observed is dependent on the hot spot temperature, system size and thermal conductivity. For cases where ignition is observed, the incubation period is dominated by intermolecular and intramolecular hydrogen transfer reactions. The gradual temperature and pressure increase in the incubation period is accompanied by accumulation of heavier polyradicals. The challenge of connecting such chemistry in mesoscale simulations remain in reducing the complexity of chemistry. The hot spot growth kinetics in RDX grains and interfaces is an important challenge for reactive simulations aiming to fill in the gaps in our knowledge in the nanoseconds to microseconds time scale. The results discussed indicate that the mesoscale chemistry may include large polyradical molecules in dense reactive mix reaching an instability point at certain temperatures and pressures.

  10. Using Graphs of Gibbs Energy versus Temperature in General Chemistry Discussions of Phase Changes and Colligative Properties

    Science.gov (United States)

    Hanson, Robert M.; Riley, Patrick; Schwinefus, Jeff; Fischer, Paul J.

    2008-01-01

    The use of qualitative graphs of Gibbs energy versus temperature is described in the context of chemical demonstrations involving phase changes and colligative properties at the general chemistry level. (Contains 5 figures and 1 note.)

  11. Binary Solid-Liquid Phase Diagram of Phenol and t-Butanol: An Undergraduate Physical Chemistry Experiment

    Science.gov (United States)

    Xu, Xinhua; Wang, Xiaogang; Wu, Meifen

    2014-01-01

    The determination of the solid-liquid phase diagram of a binary system is always used as an experiment in the undergraduate physical chemistry laboratory courses. However, most phase diagrams investigated in the lab are simple eutectic ones, despite the fact that complex binary solid-liquid phase diagrams are more common. In this article, the…

  12. Discovering Factors that Influence the Decision to Pursue a Chemistry-Related Career: A Comparative Analysis of the Experiences of Non Scientist Adults and Chemistry Teachers in Greece

    Science.gov (United States)

    Salta, Katerina; Gekos, Michael; Petsimeri, Irene; Koulougliotis, Dionysios

    2012-01-01

    This study aims at identifying factors that influence students' choice not to pursue a chemistry-related career by analyzing the experiences of secondary education chemistry teachers in Greece and of Greek adults who have not pursued studies related to science. Data collection was done with the method of individual structured interviews. The…

  13. Nanoparticles-chemistry, new synthetic approaches, gas phase clustering and novel applications

    Indian Academy of Sciences (India)

    A Sreekumaran Nair; Chandramouli Subramaniam; M J Rosemary; Renjis T Tom; V R Rajeev Kumar; D M David Jeba Singh; Jobin Cyriac; Prashant Jain; K A Kalesh; Shreya Bhattacharya; T Pradeep

    2005-10-01

    In this paper, an overview of the synthesis, chemistry and applications of nanosystems carried out in our laboratory is presented. The discussion is divided into four sections, namely (a) chemistry of nanoparticles, (b) development of new synthetic approaches, (c) gas phase clusters and (d) device structures and applications. In `chemistry of nanoparticles' we describe a novel reaction between nanoparticles of Ag and Au with halocarbons. The reactions lead to the formation of various carbonaceous materials and metal halides. In `development of new synthetic approaches' our one-pot methodologies for the synthesis of core-shell nanosystems of Au, Ag and Cu protected with TiO2 and ZrO2 as well as various polymers are discussed. Some results on the interaction of nanoparticles with biomolecules are also detailed in this section. The third section covers the formation of gas phase aggregates/clusters of thiol-protected sub-nanoparticles. Laser desorption of H2MoO4, H2WO4, MoS2, and WS2 giving novel clusters is discussed. The fourth section deals with the development of simple devices and technologies using nanomaterials described above.

  14. Evolution of Instrumentation for the Study of Gas-Phase Ion/Ion Chemistry via Mass Spectrometry

    OpenAIRE

    Xia, Yu; McLuckey, Scott A.

    2007-01-01

    The scope of gas phase ion/ion chemistry accessible to mass spectrometry is largely defined by the available tools. Due to the development of novel instrumentation, a wide range of reaction phenomenologies have been noted, many of which have been studied extensively and exploited for analytical applications. This perspective presents the development of mass spectrometry-based instrumentation for the study of the gas phase ion/ion chemistry in which at least one of the reactants is multiply-ch...

  15. Phase transition of a symmetric diblock copolymer induced by nanorods with different surface chemistry

    Science.gov (United States)

    Guo, Yu-qi; Pan, Jun-xing; Sun, Min-na; Zhang, Jin-jun

    2017-01-01

    We investigate the phase transition of a symmetric diblock copolymer induced by nanorods with different surface chemistry. The results demonstrate that the system occurs the phase transition from a disordered structure to ordered parallel lamellae and then to the tilted layered structure as the number of rods increases. The dynamic evolution of the domain size and the order parameter of the microstructure are also examined. Furthermore, the influence of rod property, rod-phase interaction, rod-rod interaction, rod length, and polymerization degree on the behavior of the polymer system is also investigated systematically. Moreover, longer amphiphilic nanorods tend to make the polymer system form the hexagonal structure. It transforms into a perpendicular lamellar structure as the polymerization degree increases. Our simulations provide an efficient method for determining how to obtain the ordered structure on the nanometer scales and design the functional materials with optical, electronic, and magnetic properties.

  16. New Dioxaborolane Chemistry Enables [(18)F]-Positron-Emitting, Fluorescent [(18)F]-Multimodality Biomolecule Generation from the Solid Phase.

    Science.gov (United States)

    Rodriguez, Erik A; Wang, Ye; Crisp, Jessica L; Vera, David R; Tsien, Roger Y; Ting, Richard

    2016-05-18

    New protecting group chemistry is used to greatly simplify imaging probe production. Temperature and organic solvent-sensitive biomolecules are covalently attached to a biotin-bearing dioxaborolane, which facilitates antibody immobilization on a streptavidin-agarose solid-phase support. Treatment with aqueous fluoride triggers fluoride-labeled antibody release from the solid phase, separated from unlabeled antibody, and creates [(18)F]-trifluoroborate-antibody for positron emission tomography and near-infrared fluorescent (PET/NIRF) multimodality imaging. This dioxaborolane-fluoride reaction is bioorthogonal, does not inhibit antigen binding, and increases [(18)F]-specific activity relative to solution-based radiosyntheses. Two applications are investigated: an anti-epithelial cell adhesion molecule (EpCAM) monoclonal antibody (mAb) that labels prostate tumors and Cetuximab, an anti-epidermal growth factor receptor (EGFR) mAb (FDA approved) that labels lung adenocarcinoma tumors. Colocalized, tumor-specific NIRF and PET imaging confirm utility of the new technology. The described chemistry should allow labeling of many commercial systems, diabodies, nanoparticles, and small molecules for dual modality imaging of many diseases.

  17. Random-phase approximation and its applications in computational chemistry and materials science

    Science.gov (United States)

    Ren, Xinguo; Rinke, Patrick; Joas, Christian; Scheffler, Matthias

    2012-11-01

    The random-phase approximation (RPA) as an approach for computing the electronic correlation energy is reviewed. After a brief account of its basic concept and historical development, the paper is devoted to the theoretical formulations of RPA, and its applications to realistic systems. With several illustrating applications, we discuss the implications of RPA for computational chemistry and materials science. The computational cost of RPA is also addressed which is critical for its widespread use in future applications. In addition, current correction schemes going beyond RPA and directions of further development will be discussed.

  18. Review: gas-phase ion chemistry of the noble gases: recent advances and future perspectives.

    Science.gov (United States)

    Grandinetti, Felice

    2011-01-01

    This review article surveys recent experimental and theoretical advances in the gas-phase ion chemistry of the noble gases. Covered issues include the interaction of the noble gases with metal and non-metal cations, the conceivable existence of covalent noble-gas anions, the occurrence of ion-molecule reactions involving singly-charged xenon cations, and the occurrence of bond-forming reactions involving doubly-charged cations. Research themes are also highlighted, that are expected to attract further interest in the future.

  19. Solid-phase enolate chemistry investigated using HR-MAS NMR spectroscopy.

    Science.gov (United States)

    Fruchart, Jean-Sébastien; Lippens, Guy; Kuhn, Cyrille; Gras-Masse, Hélène; Melnyk, Oleg

    2002-01-25

    Supported P4-t-Bu enolate chemistry of phenylacetyloxymethyl polystyrene (PS) resin was investigated using high-resolution magic angle spinning (HR-MAS) NMR spectroscopy. Direct analysis of the crude reaction suspensions through the use of a diffusion filter (DF) allowed a rapid selection of the optimal experimental conditions, but also the characterization of the enolate on the solid phase. Comparison with solution experiments and literature data allowed us to address partially the structure of the enolate. HR-MAS NMR spectra of the enolate revealed also a tight interaction of P4-t-Bu base with the polymer matrix.

  20. A Convergent Solid-Phase Synthesis of Actinomycin Analogues - Towards Implementation of Double-Combinatorial Chemistry

    DEFF Research Database (Denmark)

    Tong, Glenn; Nielsen, John

    1996-01-01

    The actinomycin antibiotics bind to nucleic acids via both intercalation and hydrogen bonding. We found this 'double-action attack' mechanism very attractive in our search for a novel class of nucleic acid binders. A highly convergent, solid-phase synthetic strategy has been developed for a class...... with the requirements for combinatorial synthesis and furthermore, the final segment condensation allows, for the first time, double-combinatorial chemistry to be performed where two combinatorial libraries can be reacted with each other. Copyright (C) 1996 Elsevier Science Ltd....

  1. The nucleation rate surfaces design over diagram of phase equilibria and their applications for computational chemistry

    Science.gov (United States)

    Anisimov, M. P.

    2016-12-01

    One can find in scientific literature a pretty fresh idea of the nucleation rate surfaces design over the diagrams of phase equilibria. That idea looks like profitable for the nucleation theory development and for various practical applications where predictions of theory have no high enough accuracy for today. The common thermodynamics has no real ability to predict parameters of the first order phase transition. Nucleation experiment can be provided in very local nucleation conditions even the nucleation takes place from the critical line (in two-component case) down to the absolute zero temperature limit and from zero nucleation rates at phase equilibria up to the spinodal conditions. Theory predictions have low reliability as a rule. The computational chemistry has chance to make solution of that problem easier when a set of the used axiomatic statements will adapt enough progressive assumptions [1]. Semiempirical design of the nucleation rate surfaces over diagrams of phase equilibria have a potential ability to provide a reasonable quality information on nucleation rate for each channel of nucleation. Consideration and using of the nucleation rate surface topologies to optimize synthesis of a given phase of the target material can be available when data base on nucleation rates over diagrams of phase equilibria will be created.

  2. Structural Isomerization of the Gas Phase 2-NORBORNYL Cation Revealed with Infrared Spectroscopy and Computational Chemistry

    Science.gov (United States)

    Mauney, Daniel; Mosley, Jonathan; Duncan, Michael A.

    2014-06-01

    The non-classical structure of the 2-norborny cation (C_7H11+) which was at the center of "the most heated chemical controversy of our time" has been observed in the condensed phase and recently using X-ray crystallography. However, no gas phase vibrational spectrum has been collected. The C_7H11+ cation is produced via H_3+ protonation of norbornene by pulsed discharge in a supersonic expansion of H_2/Ar. Ions are mass-selected and probed using infrared photodissociation spectroscopy. Due to high exothermicity, protonation via H_3+ leads to a structural isomerization to the global minimum structure 1,3-dimethylcyclopentenyl (DMCP+). Experiments are currently being conducted to find softer protonation techniques that could lead to the authentic 2-norbornyl cation. Schleyer,P.v.R. et. al.; Stable Carbocation Chemistry, John Wiley & Sons,Inc.; New York, 1997, Chapter 2

  3. Applications of monolithic solid-phase extraction in chromatography-based clinical chemistry assays.

    Science.gov (United States)

    Bunch, Dustin R; Wang, Sihe

    2013-04-01

    Complex matrices, for example urine, serum, plasma, and whole blood, which are common in clinical chemistry testing, contain many non-analyte compounds that can interfere with either detection or in-source ionization in chromatography-based assays. To overcome this problem, analytes are extracted by protein precipitation, solid-phase extraction (SPE), and liquid-liquid extraction. With correct chemistry and well controlled material SPE may furnish clean specimens with consistent performance. Traditionally, SPE has been performed with particle-based adsorbents, but monolithic SPE is attracting increasing interest of clinical laboratories. Monoliths, solid pieces of stationary phase, have bimodal structures consisting of macropores, which enable passage of solvent, and mesopores, in which analytes are separated. This structure results in low back-pressure with separation capabilities similar to those of particle-based adsorbents. Monoliths also enable increased sample throughput, reduced solvent use, varied support formats, and/or automation. However, many of these monoliths are not commercially available. In this review, application of monoliths to purification of samples from humans before chromatography-based assays will be critically reviewed.

  4. YBCO SQUIDs with unconventional current phase relation

    Energy Technology Data Exchange (ETDEWEB)

    Bauch, T. [Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Goeteborg (Sweden)], E-mail: Thilo.bauch@mc2.chalmers.se; Johansson, J.; Cedergren, K. [Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Goeteborg (Sweden); Lindstroem, T. [National Physical Laboratory, Teddington, Middlesex TW11 0LW (United Kingdom); Lombardi, F. [Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Goeteborg (Sweden)

    2007-10-01

    We have studied the dynamics of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) dc sperconducting quantum interference devices (SQUIDs) characterized by an unconventional Josephson current phase relation (CPR). We have focused on SQUID configurations with Josephson junctions where the lobe of the order parameter in one electrode is facing a node in the other electrode. This order parameter arrangement should enhance the appearance of a sin(2{phi}) term in the CPR. The response of the critical current of the dc SQUID, under the effect of an external magnetic field, has been measured in temperature, down to 20 mK. Our experimental data have been compared with numerical simulations of the SQUIDs dynamics by considering a CPR of a single junction of the form I({phi}) = I{sup I} sin({phi}) - I{sup II} sin(2{phi}) where I{sup I} and I{sup II} are, respectively, the first and second harmonic component. In our devices the values of the sin(2{phi}) term are such that the fundamental state of the SQUID is naturally double degenerate. This is of great relevance for applications of d-wave SQUIDs in quantum information processing.

  5. The oxidation of hydrogen cyanide and related chemistry

    DEFF Research Database (Denmark)

    Dagaut, Philippe; Glarborg, Peter; Alzueta, Maria U.

    2008-01-01

    For modeling the formation of nitrogen oxides in combustion via both the prompt-NO and the fuel-NO mechanisms, as well as for modeling the reduction of nitrogen oxides via reburning, a good knowledge of the kinetics of oxidation of hydrogen cyanide (HCN) is required. The formation routes to HCN a...... and the thermochemistry of HCN-related species are reviewed. The available kinetic data for the oxidation of HCN are presented and a comprehensive detailed chemical kinetic reaction mechanism for the oxidation of HCN is proposed and discussed....

  6. Substrate Activity Screening (SAS) and Related Approaches in Medicinal Chemistry.

    Science.gov (United States)

    Gladysz, Rafaela; Lambeir, Anne-Marie; Joossens, Jurgen; Augustyns, Koen; Van der Veken, Pieter

    2016-03-04

    Substrate activity screening (SAS) was presented a decade ago by Ellman and co-workers as a straightforward methodology for the identification of fragment-sized building blocks for enzyme inhibitors. Ever since, SAS and variations derived from it have been successfully applied to the discovery of inhibitors of various families of enzymatically active drug targets. This review covers key achievements and challenges of SAS and related methodologies, including the modified substrate activity screening (MSAS) approach. Special attention is given to the kinetic and thermodynamic aspects of these methodologies, as a thorough understanding thereof is crucial for successfully transforming the identified fragment-sized hits into potent inhibitors.

  7. Fuzzy electron density fragments in macromolecular quantum chemistry, combinatorial quantum chemistry, functional group analysis, and shape-activity relations.

    Science.gov (United States)

    Mezey, Paul G

    2014-09-16

    Conspectus Just as complete molecules have no boundaries and have "fuzzy" electron density clouds approaching zero density exponentially at large distances from the nearest nucleus, a physically justified choice for electron density fragments exhibits similar behavior. Whereas fuzzy electron densities, just as any fuzzy object, such as a thicker cloud on a foggy day, do not lend themselves to easy visualization, one may partially overcome this by using isocontours. Whereas a faithful representation of the complete fuzzy density would need infinitely many such isocontours, nevertheless, by choosing a selected few, one can still obtain a limited pictorial representation. Clearly, such images are of limited value, and one better relies on more complete mathematical representations, using, for example, density matrices of fuzzy fragment densities. A fuzzy density fragmentation can be obtained in an exactly additive way, using the output from any of the common quantum chemical computational techniques, such as Hartree-Fock, MP2, and various density functional approaches. Such "fuzzy" electron density fragments properly represented have proven to be useful in a rather wide range of applications, for example, (a) using them as additive building blocks leading to efficient linear scaling macromolecular quantum chemistry computational techniques, (b) the study of quantum chemical functional groups, (c) using approximate fuzzy fragment information as allowed by the holographic electron density theorem, (d) the study of correlations between local shape and activity, including through-bond and through-space components of interactions between parts of molecules and relations between local molecular shape and substituent effects, (e) using them as tools of density matrix extrapolation in conformational changes, (f) physically valid averaging and statistical distribution of several local electron densities of common stoichiometry, useful in electron density databank mining, for

  8. The coupling effect of gas-phase chemistry and surface reactions on oxygen permeation and fuel conversion in ITM reactors

    KAUST Repository

    Hong, Jongsup

    2015-08-01

    © 2015 Elsevier B.V. The effect of the coupling between heterogeneous catalytic reactions supported by an ion transport membrane (ITM) and gas-phase chemistry on fuel conversion and oxygen permeation in ITM reactors is examined. In ITM reactors, thermochemical reactions take place in the gas-phase and on the membrane surface, both of which interact with oxygen permeation. However, this coupling between gas-phase and surface chemistry has not been examined in detail. In this study, a parametric analysis using numerical simulations is conducted to investigate this coupling and its impact on fuel conversion and oxygen permeation rates. A thermochemical model that incorporates heterogeneous chemistry on the membrane surface and detailed chemical kinetics in the gas-phase is used. Results show that fuel conversion and oxygen permeation are strongly influenced by the simultaneous action of both chemistries. It is shown that the coupling somewhat suppresses the gas-phase kinetics and reduces fuel conversion, both attributed to extensive thermal energy transfer towards the membrane which conducts it to the air side and radiates to the reactor walls. The reaction pathway and products, in the form of syngas and C2 hydrocarbons, are also affected. In addition, the operating regimes of ITM reactors in which heterogeneous- or/and homogeneous-phase reactions predominantly contribute to fuel conversion and oxygen permeation are elucidated.

  9. Lunar carbon chemistry - Relations to and implications for terrestrial organic geochemistry.

    Science.gov (United States)

    Eglinton, G.; Maxwell, J. R.; Pillinger, C. T.

    1972-01-01

    Survey of the various ways in which studies of lunar carbon chemistry have beneficially affected terrestrial organic geochemistry. A lunar organic gas-analysis operating system is cited as the most important instrumental development in relation to terrestrial organic geochemistry. Improved methods of analysis and handling of organic samples are cited as another benefit derived from studies of lunar carbon chemistry. The problem of controlling contamination and minimizing organic vapors is considered, as well as the possibility of analyzing terrestrial samples by the techniques developed for lunar samples. A need for new methods of analyzing carbonaceous material which is insoluble in organic solvents is indicated.

  10. Application of click chemistry conditions for 5-bromo-2'-deoxyuridine determination through Fenton and related reactions.

    Science.gov (United States)

    Cappella, Paolo; Pulici, Maurizio; Gasparri, Fabio

    2015-01-05

    Mixtures of ascorbate and copper used in certain click chemistry experimental conditions act as oxidizing agents, catalyzing the formation of reactive oxygen species through Fenton and related reactions. Hydroxyl radicals act as chemical nucleases, introducing DNA strand breaks that can be exploited for BrdU immunostaining in place of acid denaturation. This procedure is readily applicable to high content analysis and flow cytometry assays, and provides results comparable to click chemistry EdU cycloaddition and classical BrdU immunodetection. Importantly, this approach allows preservation of labile epitopes such as phosphoproteins. This unit describes an optimized method that successfully employs Fenton chemistry for simultaneous detection of phosphoproteins and BrdU in intact cells.

  11. The relative role of "A" level chemistry, physics and biology in the medical course.

    Science.gov (United States)

    Tomilson, R W; Clack, G B; Pettingale, K W; Anderson, J; Ryan, K C

    1977-03-01

    The performance of 209 students in the 2nd MBBS, first clinical year and final MBBS examinations has been compared retrospectively with their grades in chemistry, physics and biology at "A" level. The mean grade has also been determined for students from different social classes and secondary education. Significant differences in marks for biology were found between successful and not so successful students, especially in the pre-clinical part of the course. Significnat differences in marks and significant correlations were also found for physics but not to any great extent for chemistry. The relative role of these three basic sciences in the medical course is discussed. The suggestion is made that there is a need for a re-appraisal of the privleged position of chemistry and an unquestioned science requirement for entry to medical school.

  12. Improved machine learning method for analysis of gas phase chemistry of peptides

    Directory of Open Access Journals (Sweden)

    Ahn Natalie

    2008-12-01

    Full Text Available Abstract Background Accurate peptide identification is important to high-throughput proteomics analyses that use mass spectrometry. Search programs compare fragmentation spectra (MS/MS of peptides from complex digests with theoretically derived spectra from a database of protein sequences. Improved discrimination is achieved with theoretical spectra that are based on simulating gas phase chemistry of the peptides, but the limited understanding of those processes affects the accuracy of predictions from theoretical spectra. Results We employed a robust data mining strategy using new feature annotation functions of MAE software, which revealed under-prediction of the frequency of occurrence in fragmentation of the second peptide bond. We applied methods of exploratory data analysis to pre-process the information in the MS/MS spectra, including data normalization and attribute selection, to reduce the attributes to a smaller, less correlated set for machine learning studies. We then compared our rule building machine learning program, DataSqueezer, with commonly used association rules and decision tree algorithms. All used machine learning algorithms produced similar results that were consistent with expected properties for a second gas phase mechanism at the second peptide bond. Conclusion The results provide compelling evidence that we have identified underlying chemical properties in the data that suggest the existence of an additional gas phase mechanism for the second peptide bond. Thus, the methods described in this study provide a valuable approach for analyses of this kind in the future.

  13. Phases and relativity in atomic gravimetry

    CERN Document Server

    Jaekel, Marc-Thierry; Reynaud, Serge

    2012-01-01

    The phase observable measured by an atomic gravimeter built up on stimulated Raman transitions is discussed in a fully relativistic context. It is written in terms of laser phases which are invariant under relativistic gauge transformations. The dephasing is the sum of light and atomic contributions which are connected to one another through their interplay with conservation laws at the interaction vertices. In the case of a closed geometry, a compact form of the dephasing is written in terms of a Legendre transform of the laser phases. These general expressions are illustrated by discussing two techniques used for compensating the Doppler shift, one corresponding to chirped frequencies and the other one to ramped variations.

  14. From Polymer to Small Organic Molecules: A Tight Relationship between Radical Chemistry and Solid-Phase Organic Synthesis

    Directory of Open Access Journals (Sweden)

    Danilo Mirizzi

    2011-04-01

    Full Text Available Since Gomberg’s discovery of radicals as chemical entities, the interest around them has increased through the years. Nowadays, radical chemistry is used in the synthesis of 75% of all polymers, inevitably establishing a close relationship with Solid-Phase Organic Synthesis. More recently, the interest of organic chemists has shifted towards the application of usual “in-solution” radical chemistry to the solid-phase, ranging from the use of supported reagents for radical reactions, to the development of methodologies for the synthesis of small molecules or potential libraries. The aim of this review is to put in perspective radical chemistry, moving it away from its origin as a synthetic means for solid supports, to becoming a useful tool for the synthesis of small molecules.

  15. Computer vision-based recognition of liquid surfaces and phase boundaries in transparent vessels, with emphasis on chemistry applications

    OpenAIRE

    Eppel, Sagi; Kachman, Tal

    2014-01-01

    The ability to recognize the liquid surface and the liquid level in transparent containers is perhaps the most commonly used evaluation method when dealing with fluids. Such recognition is essential in determining the liquid volume, fill level, phase boundaries and phase separation in various fluid systems. The recognition of liquid surfaces is particularly important in solution chemistry, where it is essential to many laboratory techniques (e.g., extraction, distillation, titration). A gener...

  16. Description and evaluation of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (NMMB-MONARCH) version 1.0: gas-phase chemistry at global scale

    Science.gov (United States)

    Badia, Alba; Jorba, Oriol; Voulgarakis, Apostolos; Dabdub, Donald; Pérez García-Pando, Carlos; Hilboll, Andreas; Gonçalves, María; Janjic, Zavisa

    2017-02-01

    This paper presents a comprehensive description and benchmark evaluation of the tropospheric gas-phase chemistry component of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (NMMB-MONARCH), formerly known as NMMB/BSC-CTM, that can be run on both regional and global domains. Here, we provide an extensive evaluation of a global annual cycle simulation using a variety of background surface stations (EMEP, WDCGG and CASTNET), ozonesondes (WOUDC, CMD and SHADOZ), aircraft data (MOZAIC and several campaigns), and satellite observations (SCIAMACHY and MOPITT). We also include an extensive discussion of our results in comparison to other state-of-the-art models. We note that in this study, we omitted aerosol processes and some natural emissions (lightning and volcano emissions). The model shows a realistic oxidative capacity across the globe. The seasonal cycle for CO is fairly well represented at different locations (correlations around 0.3-0.7 in surface concentrations), although concentrations are underestimated in spring and winter in the Northern Hemisphere, and are overestimated throughout the year at 800 and 500 hPa in the Southern Hemisphere. Nitrogen species are well represented in almost all locations, particularly NO2 in Europe (root mean square error - RMSE - below 5 ppb). The modeled vertical distributions of NOx and HNO3 are in excellent agreement with the observed values and the spatial and seasonal trends of tropospheric NO2 columns correspond well to observations from SCIAMACHY, capturing the highly polluted areas and the biomass burning cycle throughout the year. Over Asia, the model underestimates NOx from March to August, probably due to an underestimation of NOx emissions in the region. Overall, the comparison of the modeled CO and NO2 with MOPITT and SCIAMACHY observations emphasizes the need for more accurate emission rates from anthropogenic and biomass burning sources (i.e., specification of temporal variability). The resulting

  17. Transforming Trauma: The Relational Unconscious and "Chemistry" in the Treatment of a Paraplegic Patient.

    Science.gov (United States)

    Steinberger, Claire Beth

    2014-06-01

    Therapeutic action with a traumatized paraplegic patient highlights the evocative-and transformative-influence of the relational unconscious. The patient's triumphant resolution suggests that formative bipersonal dynamics (including transference, countertransference, and mutual projective identifications) create an ongoing intersubjective enactment and relational chemistry pivotal to psychic shift. A broad systems perspective highlights contextual communication and the interweaving of the analyst's etiological contributions and subjective experience of trauma. Ultimately, an unconscious, co-created dynamic challenges traumatic fixations, supporting a reintegration of narcissistic, gender, and erotic representations and ego capacities. An eclectic perspective that illuminates the analyst's role-receptivity encompasses classical, object relations, relational, systems, and self psychological paradigms.

  18. Evaluation of phase chemistry and petrochemical aspects of Samchampi–Samteran differentiated alkaline complex of Mikir Hills, northeastern India

    Indian Academy of Sciences (India)

    Abhishek Saha; Sohini Ganguly; Jyotisankar Ray; Nilanjan Chaterjee

    2010-10-01

    The Samchampi –Samteran alkaline complex occurs as a plug-like pluton within the Precambrian granite gneisses of Mikir Hills,Assam,northeastern India and it is genetically related to Sylhet Traps.The intrusive complex is marked by dominant development of syenite within which ijolite – melteigite suite of rocks is emplaced with an arcuate outcrop pattern.Inliers of alkali pyroxenite and alkali gabbro occur within this ijolite –melteigite suite of rocks.The pluton is also traversed by younger intrusives of nepheline syenite and carbonatite.Development of sporadic,lumpy magnetite ore bodies is also recorded within the pluton.Petrographic details of the constituent lithomembers of the pluton have been presented following standard nomenclatorial rules.Overall pyroxene compositions range from diopside to aegirine augite while alkali feldspars are typically orthoclase and plagioclase in syenite corresponds to oligoclase species.Phase chemistry of nepheline is suggestive of Na-rich alkaline character of the complex.Biotite compositions are typically restricted to a uniform compositional range and they belong to ‘biotite ’field in the relevant classification scheme.Garnets (developed in syenite and melteigite)typically tend to be Ti-rich andradite,which on a closer scan can be further designated as melanites.Opaque minerals mostly correspond to magnetite.Use of Lindsley ’s pyroxene thermometric method suggests an equilibration temperature from ∼450°–600°C for melteigite/alkali gabbro and ∼400° C for syenite.Critical assessment of other thermometric methods reveals a temperature of equilibration of ∼700°–1350°C for ijolite –melteigite suite of rocks in contrast to a relatively lower equilibration temperature of ∼600° C for syenite. Geobarometric data based on pyroxene chemistry yield an equilibration pressure of 5.32 –7.72 kb for ijolite,melteigite,alkali pyroxenite,alkali gabbro and nepheline syenite.The dominant syenite member of the

  19. Age-related plasma chemistry findings in the buff-crested bustard (Eupodotis ruficrista gindiana).

    Science.gov (United States)

    Bailey, T A; Wernery, U; Howlett, J; Naldo, J; Samour, J H

    1998-12-01

    Blood samples were obtained from adult (> 1.5 years) and juvenile (2-8 weeks, 9-16 weeks and 17-24 weeks) captive buff-crested bustards (Eupodotis ruficrista gindiana) to study age-related changes. A total of twelve different tests were conducted using a Hitachi 90011 wet chemistry analyzer. A comparison of the values obtained was made between adult and juvenile buff-crested bustards and from the literature with other bustard species. Significant differences between adult and juvenile buff-crested bustards were found for glucose, uric acid, total protein, alkaline phosphatase, asparatate amino transferase and calcium. The results obtained from this study provide blood chemistry values for this species and demonstrate age-related differences between adult and juvenile birds.

  20. Phase Relation of Harmonics in Nonlinear Focused Ultrasound

    Institute of Scientific and Technical Information of China (English)

    Zhe-Fan Peng; Wei-Jun Lin; Shi-Lei Liu; Chang Su; Hai-Lan Zhang; Xiu-Ming Wang

    2016-01-01

    The phase relation of harmonics in high-intensity focused ultrasound is investigated numerically and experimentally.The nonlinear Westervelt equation is solved to model nonlinear focused sound field by using the finite difference time domain method.Experimental waveforms are measured by a robust needle hydrophone.Then the relative phase quantity is introduced and obtained by using the zero-phase filter.The results show that the nth harmonic relative phase quantity is approximately (n-1)π/3 at geometric center and increases along the axial direction.Moreover,the relative phase quantity decreases with the increase of source amplitude.This phase relation gives an explanation of some nonlinear phenomena such as the discrepancy of positive and negative pressure.

  1. The current-phase relation in HTS Josephson junctions

    Science.gov (United States)

    Il'ichev, E.; Zakosarenko, V.; Ijsselsteijn, R. P. J.; Schultze, V.; Meyer, H.-G.; Hoenig, H. E.

    The current-phase relation of YBa2Cu3O7-x step-edge as well as 24° and 45° grain boundary Josephson junctions has been investigated experimentally. The junctions were incorporated into a washer-shaped superconducting ring with inductance L≈80-300 pH. The ring was inductively coupled to a tank circuit with a resonance frequency 9…40 MHz. The current-phase relation was obtained from the measurement of the impedance of the phase-biased junction. It is shown, that experimentally observed deviations from harmonic behavior of the apparent current-phase relation for step-edge and 24° grain boundary junctions can be explained by the influence of thermal noise. The current-phase relation of 45° grain boundary junctions was found to be extremely non-harmonic. The reasons of this unusual behavior are discussed.

  2. The contribution of solid-state chemistry in the determination of multicomponent phase diagrams

    Institute of Scientific and Technical Information of China (English)

    Jean Claude Tedenac; Franck Gascoin; Didier Ravot

    2006-01-01

    For a long period of time, the determination of phase diagrams was only supported by experiments related to thermal effects or thermodynamic measurements: thermal analysis, calorimetric measurements, vapor pressures, and EMF measurements. As a matter of fact, solid-solid transformations were not so accurately determined and could not be taken into account in the system's analysis. First, X-ray diffraction methods were used as a support for the thermal analysis. Sec ond, the implementation of novel tools in structural analysis (for example, the Rietveld method) has permitted to increase the knowledge of phase stability. Finally, modeling the phases using a Calphad method needed increasingly more structural results to determine and better understand the phase diagrams. On the other hand, the Calphad method has been widely developed for metallic systems, for oxide systems, and in the past 10 years, for some semi-conductor systems, for example,gallium arsenide, cadmium telluride, and lead telluride systems. In such applications, it is very important to bring point defects in the modeling of the phases to map the defects as a function of the chemical composition. Owing to its complexity,this characteristic, the knowledge of which is crucial for the understanding and the control of potential physical applications, was ignored in the previous assessment of semi-conductor systems.

  3. Thiol click chemistry on gold-decorated MoS2: elastomer composites and structural phase transitions

    Science.gov (United States)

    Topolovsek, Peter; Cmok, Luka; Gadermaier, Christoph; Borovsak, Milos; Kovac, J.; Mrzel, Ales

    2016-05-01

    We show that gold decorated MoS2 flakes are amenable to thiol chemistry by blending them with a cross-linkable thiolated polysiloxane (PMMS). PMMS prevents restacking of dispersed MoS2 when transforming the metallic to the semiconducting phase. Cross-linking PMMS yields an elastomer of good optical quality, containing individual, mostly single-layer MoS2 flakes.We show that gold decorated MoS2 flakes are amenable to thiol chemistry by blending them with a cross-linkable thiolated polysiloxane (PMMS). PMMS prevents restacking of dispersed MoS2 when transforming the metallic to the semiconducting phase. Cross-linking PMMS yields an elastomer of good optical quality, containing individual, mostly single-layer MoS2 flakes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01490a

  4. Analysis of chemistry textbook content and national science education standards in terms of air quality-related learning goals

    Science.gov (United States)

    Naughton, Wendy

    In this study's Phase One, representatives of nine municipal agencies involved in air quality education were interviewed and interview transcripts were analyzed for themes related to what citizens need to know or be able to do regarding air quality concerns. Based on these themes, eight air quality Learning Goal Sets were generated and validated via peer and member checks. In Phase Two, six college-level, liberal-arts chemistry textbooks and the National Science Education Standards (NSES) were analyzed for congruence with Phase One learning goals. Major categories of desired citizen understandings highlighted in agency interviews concerned air pollution sources, impact, detection, and transport. Identified cognitive skills focused on information-gathering and -evaluating skills, enabling informed decision-making. A content match was found between textbooks and air quality learning goals, but most textbooks fail to address learning goals that remediate citizen misconceptions and inabilities---particularly those with a "personal experience" focus. A partial match between NSES and air quality learning goals was attributed to differing foci: Researcher-derived learning goals deal specifically with air quality, while NSES focus is on "fundamental science concepts," not "many science topics." Analysis of findings within a situated cognition framework suggests implications for instruction and NSES revision.

  5. Preparation of a novel carboxyl stationary phase by "thiol-ene" click chemistry for hydrophilic interaction chromatography.

    Science.gov (United States)

    Peng, Xi-Tian; Liu, Tao; Ji, Shu-Xian; Feng, Yu-Qi

    2013-08-01

    A novel carboxyl-bonded silica stationary phase was prepared by "thiol-ene" click chemistry. The resultant Thiol-Click-COOH phase was evaluated under hydrophilic interaction liquid chromatography (HILIC) mobile phase conditions. A comparison of the chromatographic performance of Thiol-Click-COOH and pure silica columns was performed according to the retention behaviors of analytes and the charged state of the stationary phases. The results indicated that the newly developed Thiol-Click-COOH column has a higher surface charge and stronger hydrophilicity than the pure silica column. Furthermore, the chromatographic behaviors of five nucleosides on the Thiol-Click-COOH phase were investigated in detail. Finally, a good separation of 13 nucleosides and bases, and four water-soluble vitamins was achieved.

  6. Fabrication of cross-linked hydrazone covalent organic frameworks by click chemistry and application to solid phase microextraction.

    Science.gov (United States)

    Wu, Mingxue; Chen, Gang; Ma, Jiutong; Liu, Ping; Jia, Qiong

    2016-12-01

    Covalent organic frameworks (COFs) are an emerging class of porous organic frameworks with diverse promising applications. Herein, we presented the first example of cross-linked hydrazone COFs (cross-linked COFs) coating via thiol-ene click chemistry for solid phase microextraction (SPME). Strong covalent bonds and interlayer of the prepared networks ensured the adsorption capacity and durability of the novel SPME fiber. π-π conjugated structure existed because of abundant phenyl rings and -C=N groups in the cross-lined COFs. A series of characterizations indicated that the cross-linked COFs possessed large surface areas, high porosities and stabilities as well as hydrophobicities. The fiber was applied to SPME of pesticide residues coupled with gas chromatography with an electron capture detector (GC-ECD). Under the optimum experimental conditions, enhancement factors in the range of 2190-10,998 were obtained, illustrating that the cross-linked COFs possessed remarkable preconcentration ability. The low detection limits of 0.0003-0.0023ngkg(-1) were achieved with relative standard deviations (RSDs) in the range of 3.4-7.6% (intra-batch) and 5.7-11.6% (inter-batch), respectively. Recovery values in the range of 78.2-107.0% were obtained when the SPME-GC method was applied to the analysis of pesticides in cucumber samples.

  7. Effects of phase transformation of steam-water relative permeabilities

    Energy Technology Data Exchange (ETDEWEB)

    Verma, A.K.

    1986-03-01

    A combined theoretical and experimental study of steam-water relative permeabilities (RPs) was carried out. First, an experimental study of two-phase concurrent flow of steam and water was conducted and a set of RP curves was obtained. These curves were compared with semi-empirical and experimental results obtained by other investigators for two-phase, two-component flow (oil/gas; gas/water; gas/oil). It was found that while the wetting phase RPs were in good agreement, RPs for the steam phase were considerably higher than the non-wetting phase RPs in two-component systems. This enhancement of steam RP is attributed to phase transformation effects at the pore level in flow channels. The effects of phase transformation were studied theoretically. This study indicates that there are two separate mechanisms by which phase transformation affects RP curves: (1) Phase transformation is converging-diverging flow channels can cause an enhancement of steam phase RP. In a channel dominated by steam a fraction of the flowing steam condenses upstream from the constriction, depositing its latent heat of condensation. This heat is conducted through the solid grains around the pore throat, and evaporation takes place downstream from it. Therefore, for a given bulk flow quality; a smaller fraction of steam actually flows through the throat segments. This pore-level effect manifests itself as relative permeability enhancement on a macroscopic level; and (2) phase transformation along the interface of a stagnant phase and the phase flowing around it controls the irreducible phase saturation. Therefore, the irreducible phase saturation in steam-water flow will depend, among other factors, on the boundary conditions of the flow.

  8. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume IV ? gas phase reactions of organic halogen species

    OpenAIRE

    2007-01-01

    International audience; This article, the fourth in the series, presents kinetic and photochemical data sheets evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of organic halogen species, which were last published in 1997, and were updated on the IUPAC website in 2006. The article consists of a summary sheet, containing the recommended kinetic parameters for the evaluated reactions, and four appen...

  9. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species

    OpenAIRE

    2006-01-01

    This article, the second in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of Organic species, which were last published in 1999, and were updated on the IUPAC website in late 2002, and subsequently during the preparation of this article. The article consists of a summary table of the recommended rate coefficients, containing the...

  10. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume I - gas phase reactions of Ox, HOx, NOx and SOx species

    OpenAIRE

    2004-01-01

    This article, the first in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on GasKinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of Ox, HOx, NOx and SOx species, which were last published in 1997, and were updated on the IUPAC website in late 2001. The article consists of a summary sheet, containing the recommended kinetic parameters for the evaluated reactions, and five appendi...

  11. Time-slice last millennium experiments with interactive gas-phase chemistry and aerosols

    Science.gov (United States)

    Tsigaridis, K.; Legrande, A. N.; Koch, D. M.

    2010-12-01

    Preliminary results from coupled atmosphere-ocean simulations with interactive gas-phase chemistry and aerosols are presented. These experiments are decadal scale time-slices within millennial-length simulations performed with the GISS GCM (ModelE), using two different ocean models. The boundary conditions for the transient simulations follow the last millennium coordinated PMIP3 experiment protocol. This experiment directly links in with other pre-Industrial experiments being completed as part of IPCC AR5, using the same model and resolution as in GISS IPCC AR5. Preliminary time-slice results from the early medieval and Maunder Minimum periods will be presented. The impact of the presence of short-lived gases and aerosols on the simulated climate is studied. An initial attempt to identify previously omitted additional forcing mechanisms will be performed during these contrasting climate periods, in short duration experiments driven by ocean conditions from the transient experiments. The results presented are the initial runs from a larger set of experiments that will assess the climate impact of changes to dust, sea-salt, and ocean-derived sulfate, biomass burning ozone-precursors and aerosols, organic carbon, wetland methane emissions, and a final set with all components. These species are standard components in the GISS model’s 20th century simulations, so that we may compare millennial variability characteristics with those better constrained from more recent climate periods. Dust and sea-salt are wind-driven aerosols from deserts and oceans, sulfate comes from oxidation of volcanic and oceanic precursors, while organic carbon comes from biomass burning, secondary plant sources and primary oceanic emissions. Comparison of model and proxy records will test model-simulated mechanisms while the model provides insight into factors contributing to proxy variability. The addition of potentially important forcing mechanisms will enable a more comprehensive

  12. Hot wire chemical vapor deposition chemistry in the gas phase and on the catalyst surface with organosilicon compounds.

    Science.gov (United States)

    Shi, Yujun

    2015-02-17

    CONSPECTUS: Hot wire chemical vapor deposition (HWCVD), also referred to as catalytic CVD (Cat-CVD), has been used to produce Si-containing thin films, nanomaterials, and functional polymer coatings that have found wide applications in microelectronic and photovoltaic devices, in automobiles, and in biotechnology. The success of HWCVD is largely due to its various advantages, including high deposition rate, low substrate temperatures, lack of plasma-induced damage, and large-area uniformity. Film growth in HWCVD is induced by reactive species generated from primary decomposition on the metal wire or from secondary reactions in the gas phase. In order to achieve a rational and efficient optimization of the process, it is essential to identify the reactive species and to understand the chemical kinetics that govern the production of these precursor species for film growth. In this Account, we report recent progress in unraveling the complex gas-phase reaction chemistry in the HWCVD growth of silicon carbide thin films using organosilicon compounds as single-source precursors. We have demonstrated that laser ionization mass spectrometry is a powerful diagnostic tool for studying the gas-phase reaction chemistry when combined with the methods of isotope labeling and chemical trapping. The four methyl-substituted silane molecules, belonging to open-chain alkylsilanes, dissociatively adsorb on W and Ta filaments to produce methyl radical and H2 molecule. Under the typical deposition pressures, with increasing number of methyl substitution, the dominant chemistry occurring in the gas phase switches from silylene/silene reactions to free-radical short chain reactions. This change in dominant reaction intermediates from silylene/silene to methyl radicals explains the observation from thin film deposition that silicon carbide films become more C-rich with a decreasing number of Si-H bonds in the four precursor molecules. In the case of cyclic monosilacyclobutanes, we have

  13. Partitioning of metals in different binding phases of tropical estuarine sediments: importance of metal chemistry

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Chakraborty, S.; Vudamala, K.; Sarkar, Arindam; Nath, B.N.

    with copper, nickel, and zinc. Environmental Chemistry, 3(4), 276-285. Florence, T. M., Morrison, G. M., & Stauber, J. L. (1992). Determination of trace element speciation and the role of speciation in aquatic toxicity. Science of the Total environment, 125.... Chemistry and Ecology 23: 337–343. doi:10.1080/02757540701497154. Revichandran, C., K. Srinivas, K. R. Muraleedharan, M. Rafeeq, Shivaprasad Amaravayal, K. Vijayakumar, and K. V. Jayalakshmy. 2011. Environmental set-up and tidal propagation in a tropical...

  14. Normal and Inverse Ferrite Spinels: A Set of Solid State Chemistry Related Experiments.

    Science.gov (United States)

    Chaumont, C.; Burgard, M.

    1979-01-01

    Presents one of the themes of a French chemistry college laboratory course, which concerns the field of solid state chemistry and is focused on the study of the cation distribution in the case of certain spinel ferrites. (HM)

  15. Unified phase variables of relative degree two for human locomotion.

    Science.gov (United States)

    Villarreal, Dario J; Gregg, Robert D; Villarreal, Dario J; Gregg, Robert D; Gregg, Robert D; Villarreal, Dario J

    2016-08-01

    A starting point to achieve stable locomotion is synchronizing the leg joint kinematics during the gait cycle. Some biped robots parameterize a nonlinear controller (e.g., input-output feedback linearization) whose main objective is to track specific kinematic trajectories as a function of a single mechanical variable (i.e., a phase variable) in order to allow the robot to walk. A phase variable capable of parameterizing the entire gait cycle, the hip phase angle, has been used to control wearable robots and was recently shown to provide a robust representation of the phase of human gait. However, this unified phase variable relies on hip velocity, which is difficult to measure in real-time and prevents the use of derivative corrections in phase-based controllers for wearable robots. One derivative of this phase variable yields accelerations (i.e., the equations of motion), so the system is said to be relative degree-one. This means that there are states of the system that cannot be controlled. The goal of this paper is to offer relative degree-two alternatives to the hip phase angle and examine their robustness for parameterizing human gait.

  16. WORKSHOP ON NEW DEVELOPMENTS IN CHEMICAL SEPARATIONS FROM COMBINATORIAL CHEMISTRY AND RELATED SYNTHETIC STRATEGIES

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Stephen G. [University of Pittsburgh, Pittsburgh, Pennsylvania

    1998-08-22

    The power of combinatorial chemistry and related high throughput synthetic strategies is currently being pursued as a fruitful way to develop molecules and materials with new properties. The strategy is motivated, for example in the pharmaceutical industry, by the difficulty of designing molecules to bind to specific sites on target biomolecules. By synthesizing a variety of similar structures, and then finding the one that has the most potent activity, new so-called lead structures will be found rapidly. Existing lead structures can be optimized. This relatively new approach has many implications for separation science. The most obvious is the call for more separations power: higher resolution, lower concentrations, higher speed. This pressure butresses the traditional directions of research into the development of more useful separations. The advent of chip-based, electroosmotically pumped systems1 will certainly accelerate progress in this traditional direction. The progress in combinatorial chemistry and related synthetic strategies gives rise to two other, broadly significant possibilities for large changes in separation science. One possibility results from the unique requirements of the synthesis of a huge number of products simultaneously. Can syntheses and separations be designed to work together to create strategies that lead to mixtures containing only desired products but without side products? The other possibility results from the need for molecular selectivity in separations. Can combinatorial syntheses and related strategies be used in the development of better separations media? A workshop in two parts was held. In one half-day session, pedagogical presentations educated across the barriers of discipline and scale. In the second half-day session, the participants broke into small groups to flesh out new ideas. A panel summarized the breakout discussions.

  17. Phase analysis of circadian-related genes in two tissues

    Directory of Open Access Journals (Sweden)

    Li Leping

    2006-02-01

    Full Text Available Abstract Background Recent circadian clock studies using gene expression microarray in two different tissues of mouse have revealed not all circadian-related genes are synchronized in phase or peak expression times across tissues in vivo. Instead, some circadian-related genes may be delayed by 4–8 hrs in peak expression in one tissue relative to the other. These interesting biological observations prompt a statistical question regarding how to distinguish the synchronized genes from genes that are systematically lagged in phase/peak expression time across two tissues. Results We propose a set of techniques from circular statistics to analyze phase angles of circadian-related genes in two tissues. We first estimate the phases of a cycling gene separately in each tissue, which are then used to estimate the paired angular difference of the phase angles of the gene in the two tissues. These differences are modeled as a mixture of two von Mises distributions which enables us to cluster genes into two groups; one group having synchronized transcripts with the same phase in the two tissues, the other containing transcripts with a discrepancy in phase between the two tissues. For each cluster of genes we assess the association of phases across the tissue types using circular-circular regression. We also develop a bootstrap methodology based on a circular-circular regression model to evaluate the improvement in fit provided by allowing two components versus a one-component von-Mises model. Conclusion We applied our proposed methodologies to the circadian-related genes common to heart and liver tissues in Storch et al. 2, and found that an estimated 80% of circadian-related transcripts common to heart and liver tissues were synchronized in phase, and the other 20% of transcripts were lagged about 8 hours in liver relative to heart. The bootstrap p-value for being one cluster is 0.063, which suggests the possibility of two clusters. Our methodologies can

  18. Description and Evaluation of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry Model (NMMB-MONARCH) Version 1.0: Gas-Phase Chemistry at Global Scale

    Science.gov (United States)

    Badia, Alba; Jorba, Oriol; Voulgarakis, Apostolos; Dabdub, Donald; Garcia-Pando, Carlos Perez; Hilboll, Andreas; Goncalves, Maria; Janjic, Zavisa

    2017-01-01

    This paper presents a comprehensive description and benchmark evaluation of the tropospheric gas-phase chemistry component of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (NMMBMONARCH), formerly known as NMMB/BSC-CTM, that can be run on both regional and global domains. Here, we provide an extensive evaluation of a global annual cycle simulation using a variety of background surface stations (EMEP, WDCGG and CASTNET), ozonesondes (WOUDC, CMD and SHADOZ), aircraft data (MOZAIC and several campaigns), and satellite observations (SCIAMACHY and MOPITT).We also include an extensive discussion of our results in comparison to other state-of-the-art models. We note that in this study, we omitted aerosol processes and some natural emissions (lightning and volcano emissions). The model shows a realistic oxidative capacity across the globe. The seasonal cycle for CO is fairly well represented at different locations (correlations around 0.3-0.7 in surface concentrations), although concentrations are underestimated in spring and winter in the Northern Hemisphere, and are overestimated throughout the year at 800 and 500 hPa in the Southern Hemisphere. Nitrogen species are well represented in almost all locations, particularly NO2 in Europe (root mean square error - RMSE - below 5 ppb). The modeled vertical distributions of NOx and HNO3 are in excellent agreement with the observed values and the spatial and seasonal trends of tropospheric NO2 columns correspond well to observations from SCIAMACHY, capturing the highly polluted areas and the biomass burning cycle throughout the year. Over Asia, the model underestimates NOx from March to August, probably due to an underestimation of NOx emissions in the region. Overall, the comparison of the modeled CO and NO2 with MOPITT and SCIAMACHY observations emphasizes the need for more accurate emission rates from anthropogenic and biomass burning sources (i.e., specification of temporal variability).

  19. Solid-Phase Synthesis of Small Molecule Libraries using Double Combinatorial Chemistry

    DEFF Research Database (Denmark)

    Nielsen, John; Jensen, Flemming R.

    1997-01-01

    The first synthesis of a combinatorial library using double combinatorial chemistry is presented. Coupling of unprotected Fmoc-tyrosine to the solid support was followed by Mitsunobu O-alkylation. Introduction of a diacid linker yields a system in which the double combinatorial step can...

  20. Relative effect of solder flux chemistry on the humidity related failures in electronics

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    was visualized by the ex situ analysis using a gel with tin ion indicator. Findings - The results showed that the solder flux residues are characterized by different threshold RH, above which a sudden increase in direct current leakage by 2-4 orders of magnitude and a significant reduction in surface resistance...... was studied by quartz crystal microbalance, while corrosive effects were studied by leakage current and impedance measurements on standard test boards. The measurements were performed as a function of relative humidity (RH) in the range from 60 to ~99 per cent at 25°C. The corrosiveness of solder flux systems...... of printed circuit boards under humid conditions. Originality/value - The classification of solder flux systems according to IPC J-STD-004 standard does not specify the WOAs in the flux; however, ranking of the flux systems based on the hygroscopic property of activators would be useful information when...

  1. Relative effect of solder flux chemistry on the humidity related failures in electronics

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    was studied by quartz crystal microbalance, while corrosive effects were studied by leakage current and impedance measurements on standard test boards. The measurements were performed as a function of relative humidity (RH) in the range from 60 to ~99 per cent at 25°C. The corrosiveness of solder flux systems...... of printed circuit boards under humid conditions. Originality/value - The classification of solder flux systems according to IPC J-STD-004 standard does not specify the WOAs in the flux; however, ranking of the flux systems based on the hygroscopic property of activators would be useful information when...... selecting no-clean flux systems for electronics with applications in humid conditions....

  2. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume IV – gas phase reactions of organic halogen species

    Directory of Open Access Journals (Sweden)

    R. Atkinson

    2008-08-01

    Full Text Available This article, the fourth in the series, presents kinetic and photochemical data sheets evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of organic halogen species, which were last published in 1997, and were updated on the IUPAC website in 2006/07. The article consists of a summary sheet, containing the recommended kinetic parameters for the evaluated reactions, and four appendices containing the data sheets, which provide information upon which the recommendations are made.

  3. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species

    Directory of Open Access Journals (Sweden)

    R. Atkinson

    2006-01-01

    Full Text Available This article, the second in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of Organic species, which were last published in 1999, and were updated on the IUPAC website in late 2002, and subsequently during the preparation of this article. The article consists of a summary table of the recommended rate coefficients, containing the recommended kinetic parameters for the evaluated reactions, and eight appendices containing the data sheets, which provide information upon which the recommendations are made.

  4. Solution-phase-peptide synthesis via the group-assisted purification (GAP) chemistry without using chromatography and recrystallization.

    Science.gov (United States)

    Wu, Jianbin; An, Guanghui; Lin, Siqi; Xie, Jianbo; Zhou, Wei; Sun, Hao; Pan, Yi; Li, Guigen

    2014-02-01

    The solution phase synthesis of N-protected amino acids and peptides has been achieved through the Group-Assisted Purification (GAP) chemistry by avoiding disadvantages of other methods in regard to the difficult scale-up, expenses of solid and soluble polymers, etc. The GAP synthesis can reduce the use of solvents, silica gels, energy and manpower. In addition, the GAP auxiliary can be conveniently recovered for re-use and is environmentally friendly and benign, and substantially reduces waste production in academic labs and industry.

  5. Literature survey of the aqueous chemistry of technetium related to photolysis. [115 references

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, H.A.

    1981-07-01

    A literature survey was made to accumulate information about the chemistry of technetium as it relates to photolysis. The electrochemical potentials and the reactions of the various technetium compounds and complexes are discussed, along with the various absorption spectra of the different species. The TcCl/sub 6//sup 2 -/ ion has been shown to be photochemically active in HCl solutions. Hexachlorotechnetate(IV) is oxidized when exposed to sunlight in concentrated HCl. A ligand change occurs when it is exposed to either 254- or 34-nm radiation in more dilute HCl. No other photolysis reactions were found in the literature. It is possible that, under appropriate conditions, other valence states of technetium would be photochemically active, resulting in either redox or ligand exchange reactions. Proposals for investigating the photochemical reduction of the pertechnetate in HNO/sub 3/ and other media are discussed.

  6. Content-related interactions and methods of reasoning within self-initiated organic chemistry study groups

    Science.gov (United States)

    Christian, Karen Jeanne

    2011-12-01

    Students often use study groups to prepare for class or exams; yet to date, we know very little about how these groups actually function. This study looked at the ways in which undergraduate organic chemistry students prepared for exams through self-initiated study groups. We sought to characterize the methods of social regulation, levels of content processing, and types of reasoning processes used by students within their groups. Our analysis showed that groups engaged in predominantly three types of interactions when discussing chemistry content: co-construction, teaching, and tutoring. Although each group engaged in each of these types of interactions at some point, their prevalence varied between groups and group members. Our analysis suggests that the types of interactions that were most common depended on the relative content knowledge of the group members as well as on the difficulty of the tasks in which they were engaged. Additionally, we were interested in characterizing the reasoning methods used by students within their study groups. We found that students used a combination of three content-relevant methods of reasoning: model-based reasoning, case-based reasoning, or rule-based reasoning, in conjunction with one chemically-irrelevant method of reasoning: symbol-based reasoning. The most common way for groups to reason was to use rules, whereas the least common way was for students to work from a model. In general, student reasoning correlated strongly to the subject matter to which students were paying attention, and was only weakly related to student interactions. Overall, results from this study may help instructors to construct appropriate tasks to guide what and how students study outside of the classroom. We found that students had a decidedly strategic approach in their study groups, relying heavily on material provided by their instructors, and using the reasoning strategies that resulted in the lowest levels of content processing. We suggest

  7. Implementation and evaluation of online gas-phase chemistry within a regional climate model (RegCM-CHEM4)

    Energy Technology Data Exchange (ETDEWEB)

    Shalaby, A. K.; Zakey, A. S.; Tawfik, A. B.; Solmon, F.; Giorgi, Filippo; Stordal, F.; Sillman, S.; Zaveri, Rahul A.; Steiner, A. L.

    2012-05-22

    The RegCM-CHEM4 is a new online climate-chemistry model based on the International Centre for Theoretical Physics (ICTP) regional climate model (RegCM4). Tropospheric gas-phase chemistry is integrated into the climate model using the condensed version of the Carbon Bond Mechanism (CBM-Z; Zaveri and Peters, 1999) with a fast solver based on radical balances. We evaluate the model over Continental Europe for two different time scales: (1) an event-based analysis of the ozone episode associated with the heat wave of August 2003 and (2) a climatological analysis of a sixyear simulation (2000-2005). For the episode analysis, model simulations show good agreement with European Monitoring and Evaluation Program (EMEP) observations of hourly ozone over different regions in Europe and capture ozone concentrations during and after the August 2003 heat wave event. For long-term climate simulations, the model captures the seasonal cycle of ozone concentrations with some over prediction of ozone concentrations in non-heat wave summers. Overall, the ozone and ozone precursor evaluation shows the feasibility of using RegCM-CHEM4 for decadal-length simulations of chemistry-climate interactions.

  8. Review of the global models used within phase 1 of the Chemistry-Climate Model Initiative (CCMI)

    Science.gov (United States)

    Morgenstern, Olaf; Hegglin, Michaela I.; Rozanov, Eugene; O'Connor, Fiona M.; Abraham, N. Luke; Akiyoshi, Hideharu; Archibald, Alexander T.; Bekki, Slimane; Butchart, Neal; Chipperfield, Martyn P.; Deushi, Makoto; Dhomse, Sandip S.; Garcia, Rolando R.; Hardiman, Steven C.; Horowitz, Larry W.; Jöckel, Patrick; Josse, Beatrice; Kinnison, Douglas; Lin, Meiyun; Mancini, Eva; Manyin, Michael E.; Marchand, Marion; Marécal, Virginie; Michou, Martine; Oman, Luke D.; Pitari, Giovanni; Plummer, David A.; Revell, Laura E.; Saint-Martin, David; Schofield, Robyn; Stenke, Andrea; Stone, Kane; Sudo, Kengo; Tanaka, Taichu Y.; Tilmes, Simone; Yamashita, Yousuke; Yoshida, Kohei; Zeng, Guang

    2017-02-01

    We present an overview of state-of-the-art chemistry-climate and chemistry transport models that are used within phase 1 of the Chemistry-Climate Model Initiative (CCMI-1). The CCMI aims to conduct a detailed evaluation of participating models using process-oriented diagnostics derived from observations in order to gain confidence in the models' projections of the stratospheric ozone layer, tropospheric composition, air quality, where applicable global climate change, and the interactions between them. Interpretation of these diagnostics requires detailed knowledge of the radiative, chemical, dynamical, and physical processes incorporated in the models. Also an understanding of the degree to which CCMI-1 recommendations for simulations have been followed is necessary to understand model responses to anthropogenic and natural forcing and also to explain inter-model differences. This becomes even more important given the ongoing development and the ever-growing complexity of these models. This paper also provides an overview of the available CCMI-1 simulations with the aim of informing CCMI data users.

  9. Implementation and evaluation of online gas-phase chemistry within a regional climate model (RegCM-CHEM4

    Directory of Open Access Journals (Sweden)

    A. K. Shalaby

    2012-01-01

    Full Text Available The RegCM-CHEM4 is a new online climate-chemistry model based on the International Centre for Theoretical Physics (ICTP regional climate model (RegCM4. Tropospheric gas-phase chemistry is integrated into the climate model using the condensed version of the Carbon Bond Mechanism (CBM-Z; Zaveri and Peters, 1999 with a fast solver based on radical balances. We evaluate the model over Continental Europe for two different time scales: (1 an event-based analysis of the ozone episode associated with the heat wave of August 2003 and (2 a climatological analysis of a six-year simulation (2000–2005. For the episode analysis, model simulations show good agreement with European Monitoring and Evaluation Program (EMEP observations of hourly ozone over different regions in Europe and capture ozone concentrations during and after the August 2003 heat wave event. For long-term climate simulations, the model captures the seasonal cycle of ozone concentrations with some over prediction of ozone concentrations in non-heat wave summers. Overall, the ozone and ozone precursor evaluation shows the feasibility of using RegCM-CHEM4 for decadal-length simulations of chemistry-climate interactions.

  10. Fundamental Heterogeneous Reaction Chemistry Related to Secondary Organic Aerosols (SOA) in the Atmosphere

    Science.gov (United States)

    Akimoto, H.

    2016-11-01

    Typical reaction pathways of formation of dicarboxylic acids, larger multifunctional compounds, oligomers, and organosulfur and organonitrogen compounds in secondary organic aerosols (SOA), revealed by laboratory experimental studies are reviewed with a short introduction to field observations. In most of the reactions forming these compounds, glyoxal, methyl glyoxal and related difunctional carbonyl compounds play an important role as precursors, and so their formation pathways in the gas phase are discussed first. A substantial discussion is then presented for the OH-initiated aqueous phase radical oxidation reactions of glyoxal and other carbonyls which form dicarboxylic acids, larger multifunctional compounds and oligomers, and aqueous-phase non-radical reactions which form oligomers, organosulfates and organonitrogen compounds. Finally, the heterogeneous oxidation reaction of gaseous O3, OH and NO3 with liquid and solid organic aerosols at the air-particle interface is discussed relating to the aging of SOA in the atmosphere.

  11. CRYSTAL CHEMISTRY OF THREE-COMPONENT WHITE DWARFS AND NEUTRON STAR CRUSTS: PHASE STABILITY, PHASE STRATIFICATION, AND PHYSICAL PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Engstrom, T. A.; Yoder, N. C.; Crespi, V. H., E-mail: tae146@psu.edu, E-mail: ncy5007@psu.edu, E-mail: vhc2@psu.edu [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2016-02-20

    A systematic search for multicomponent crystal structures is carried out for five different ternary systems of nuclei in a polarizable background of electrons, representative of accreted neutron star crusts and some white dwarfs. Candidate structures are “bred” by a genetic algorithm and optimized at constant pressure under the assumption of linear response (Thomas–Fermi) charge screening. Subsequent phase equilibria calculations reveal eight distinct crystal structures in the T = 0 bulk phase diagrams, five of which are complicated multinary structures not previously predicted in the context of compact object astrophysics. Frequent instances of geometrically similar but compositionally distinct phases give insight into structural preferences of systems with pairwise Yukawa interactions, including and extending to the regime of low-density colloidal suspensions made in a laboratory. As an application of these main results, we self-consistently couple the phase stability problem to the equations for a self-gravitating, hydrostatically stable white dwarf, with fixed overall composition. To our knowledge, this is the first attempt to incorporate complex multinary phases into the equilibrium phase-layering diagram and mass–radius-composition dependence, both of which are reported for He–C–O and C–O–Ne white dwarfs. Finite thickness interfacial phases (“interphases”) show up at the boundaries between single-component body-centered cubic (bcc) crystalline regions, some of which have lower lattice symmetry than cubic. A second application—quasi-static settling of heavy nuclei in white dwarfs—builds on our equilibrium phase-layering method. Tests of this nonequilibrium method reveal extra phases that play the role of transient host phases for the settling species.

  12. Effect of spreading coefficient on three-phase relative permeability of nonaqueous phase liquids

    Science.gov (United States)

    Keller, Arturo A.; Chen, Mingjie

    2003-10-01

    Three-phase flow conditions are encountered regularly, for example, during migration of released NAPL through the vadose zone, certain stages of soil vapor extraction, bioslurping, or generation of gases by microbes. To model three-phase flow, a common approach is to construct three-phase relative permeabilities based on a combination of two-phase relative permeabilities. Although this circumvents a lack of experimental data, it can lead to serious underprediction or overprediction of residual NAPL saturation. This can mislead decision makers that need to predict whether a particular spill will reach the water table or predict the speed of a NAPL front or conduct an assessment of the performance of remediation actions. Experimental data to estimate three-phase relative permeabilities is sparse. A study by [2000a] generated significant experimental information. Their analysis focused on the high NAPL saturation region, given their emphasis on oil reservoir engineering. For environmental applications the low saturation region is of more interest. Using this data set, we derived a set of empirical relations that relate NAPL three-phase relative permeability krn to NAPL saturation Sn and spreading coefficient Cs for Sn less than about 0.1, such that krn = ? where A1 = 0.012 exp (-1.3Cs) and A2 = 2.1 - 0.60Cs + 0.036Cs2. At higher Sn, krn ≈ Sn4, independent of Cs. We present a pore-scale conceptual model that provides a phenomenological basis for the use of Cs as a predictor of krn at low Sn. We then present a number of simulated case studies that highlight the effect of these three-phase relative permeabilities on risk assessment or remediation design.

  13. Using Mean Absolute Relative Phase, Deviation Phase and Point-Estimation Relative Phase to Measure Postural Coordination in a Serial Reaching Task

    Directory of Open Access Journals (Sweden)

    Anne K. Galgon, Patricia A. Shewokis

    2016-03-01

    Full Text Available The objectives of this communication are to present the methods used to calculate mean absolute relative phase (MARP, deviation phase (DP and point estimate relative phase (PRP and compare their utility in measuring postural coordination during the performance of a serial reaching task. MARP and DP are derived from continuous relative phase time series representing the relationship between two body segments or joints during movements. MARP is a single measure used to quantify the coordination pattern and DP measures the stability of the coordination pattern. PRP also quantifies coordination patterns by measuring the relationship between the timing of maximal or minimal angular displacements of two segments within cycles of movement. Seven young adults practiced a bilateral serial reaching task 300 times over 3 days. Relative phase measures were used to evaluate inter-joint relationships for shoulder-hip (proximal and hip-ankle (distal postural coordination at early and late learning. MARP, PRP and DP distinguished between proximal and distal postural coordination. There was no effect of practice on any of the relative phase measures for the group, but individual differences were seen over practice. Combined, MARP and DP estimated stability of in-phase and anti-phase postural coordination patterns, however additional qualitative movement analyses may be needed to interpret findings in a serial task. We discuss the strengths and limitations of using MARP and DP and compare MARP and DP to PRP measures in assessing coordination patterns in the context of various types of skillful tasks.

  14. The role of European Federation of Clinical Chemistry and Laboratory Medicine Working Group for Preanalytical Phase in standardization and harmonization of the preanalytical phase in Europe

    DEFF Research Database (Denmark)

    Cornes, Michael P; Church, Stephen; van Dongen-Lases, Edmée;

    2016-01-01

    and Laboratory Medicine Working Group for Preanalytical Phase (EFLM WG-PRE) was established to lead in standardization and harmonization of preanalytical policies and practices at a European level. One of the key activities of the WG-PRE is the organization of the biennial EFLM-BD conference on the preanalytical......Patient safety is a leading challenge in healthcare and from the laboratory perspective it is now well established that preanalytical errors are the major contributor to the overall rate of diagnostic and therapeutic errors. To address this, the European Federation of Clinical Chemistry...... summarises the work that has and will be done in these areas. The goal of this initiative is to ensure the EFLM WG-PRE produces work that meets the needs of the European laboratory medicine community. Progress made in the identified areas will be updated at the next preanalytical phase conference and show...

  15. The current-phase relation in Josephson junctions

    NARCIS (Netherlands)

    Golubov, A.A.; Kupriyanov, M. Yu.; Il'ichev, E.

    2004-01-01

    This review provides a theoretical basis for understanding the current-phase relation (CPhiR) for the stationary (dc) Josephson effect in various types of superconducting junctions. The authors summarize recent theoretical developments with an emphasis on the fundamental physical mechanisms of the d

  16. Relation of water chemistry of the Edwards aquifer to hydrogeology and land use, San Antonio Region, Texas

    Science.gov (United States)

    Buszka, Paul M.

    1987-01-01

    Water-chemistry data from the Edwards aquifer for 1976-85, consisting of nearly 1,500 chemical analyses from 280 wells and 3 springs, were used to statistically evaluate relations among ground-water chemistry, hydrogeology, and land use. Five land uses associated with sampled wells were classified on the basis of published information and field surveys. Four major subareas of the aquifer were defined to reflect the relative susceptibility of ground water to contamination originating from human activities using hydrogeologic and tritium data.

  17. Crystal chemistry of three-component white dwarfs and neutron star crusts: phase stability, phase stratification, and physical properties

    CERN Document Server

    Engstrom, T A; Crespi, V H

    2015-01-01

    A systematic search for multicomponent crystal structures is carried out for five different ternary systems of nuclei in a polarizable background of electrons, representative of accreted neutron star crusts and some white dwarfs. Candidate structures are "bred" by a genetic algorithm, and optimized at constant pressure under the assumption of linear response (Thomas-Fermi) charge screening. Subsequent phase equilibria calculations reveal eight distinct crystal structures in the $T=0$ bulk phase diagrams, five of which are complicated multinary structures not before predicted in the context of compact object astrophysics. Frequent instances of geometrically similar but compositionally distinct phases give insight into structural preferences of systems with pairwise Yukawa interactions, including and extending to the regime of low density colloidal suspensions made in a laboratory. As an application of these main results, we self-consistently couple the phase stability problem to the equations for a self-gravit...

  18. Behavioral and physiological correlates of stress related to examination performance in college chemistry students.

    Science.gov (United States)

    Bardi, M; Koone, T; Mewaldt, S; O'Connor, K

    2011-09-01

    This study was designed to assess physiological and behavioral correlates of academic stress during a college course in organic chemistry in the USA. Participants (45 females, 46 males, mean age 19.88 years) were screened for their basal hypothalamic-pituitary-adrenocortical activity using saliva samples collected at the beginning of the course and after each major test. Displacement activities (DAs) were observed during each test by videotaping students' behavior when they were taking the tests. These variables were then used as predictors of the students' achievement as measured by their grade point average (GPA) scores, American College Testing (ACT) scores, and their final grade in the class. Ninety-one students, enrolled in Organic Chemistry I at Marshall University during the summer of 2009, were recruited for this study. It was found that individual differences in the physiological stress responses are a factor in predicting the students' ability to pass a challenging class. A logistic model built on GPA, DAs during stress, and salivary hormone (cortisol and dehydroepiandrosterone) concentrations was able to correctly classify almost 90% of the students passing the class. The same model was not nearly as successful in determining the possible factors behind failing the class, because the classification success was just 52%, a figure close to chance. We conclude that a clear set of characteristics related to the students' ability and resilience to psychological stress are necessary to succeed in a challenging class. The reason behind dropping or failing a class could be less defined. These data indicated that investigating the physiological and behavioral propensities associated with psychological stress can help us better understand an individual's coping responses to a long-term challenging situation.

  19. The Relative Phase Asynchronization between Sunspot Numbers and Polar Faculae

    Indian Academy of Sciences (India)

    L. H. Deng; J. Y. Song; Y. Y. Xiang; Y. K. Tang

    2011-09-01

    The monthly sunspot numbers compiled by Temmer et al. and the monthly polar faculae from observations of the National Astronomical Observatory of Japan, for the interval of March 1954 to March 1996, are used to investigate the phase relationship between polar faculae and sunspot activity for total solar disk and for both hemispheres in solar cycles 19, 20, 21 and 22. We found that (1) the polar faculae begin earlier than sunspot activity, and the phase difference exhibits a consistent behaviour for different hemispheres in each of the solar cycles, implying that this phenomenon should not be regarded as a stochastic fluctuation; (2) the inverse correlation between polar faculae and sunspot numbers is not only a long-term behaviour, but also exists in short time range; (3) the polar faculae show leads of about 50–71 months relative to sunspot numbers, and the phase difference between them varies with solar cycle; (4) the phase difference value in the northern hemisphere differs from that in the southern hemisphere in a solar cycle, which means that phase difference also existed between the two hemispheres. Moreover, the phase difference between the two hemispheres exhibits a periodical behaviour. Our results seem to support the finding of Hiremath (2010).

  20. Evaluation of innovative stationary phase ligand chemistries and analytical conditions for the analysis of basic drugs by supercritical fluid chromatography.

    Science.gov (United States)

    Desfontaine, Vincent; Veuthey, Jean-Luc; Guillarme, Davy

    2016-03-18

    Similar to reversed phase liquid chromatography, basic compounds can be highly challenging to analyze by supercritical fluid chromatography (SFC), as they tend to exhibit poor peak shape, especially those with high pKa values. In this study, three new stationary phase ligand chemistries available in sub -2 μm particle sizes, namely 2-picolylamine (2-PIC), 1-aminoanthracene (1-AA) and diethylamine (DEA), were tested in SFC conditions for the analysis of basic drugs. Due to the basic properties of these ligands, it is expected that the repulsive forces may improve peak shape of basic substances, similarly to the widely used 2-ethypyridine (2-EP) phase. However, among the 38 tested basic drugs, less of 10% displayed Gaussian peaks (asymmetry between 0.8 and 1.4) using pure CO2/methanol on these phases. The addition of 10mM ammonium formate as mobile phase additive, drastically improved peak shapes and increased this proportion to 67% on 2-PIC. Introducing the additive in the injection solvent rather than in the organic modifier, gave acceptable results for 2-PIC only, with 31% of Gaussian peaks with an average asymmetry of 1.89 for the 38 selected basic drugs. These columns were also compared to hybrid silica (BEH), DIOL and 2-EP stationary phases, commonly employed in SFC. These phases commonly exhibit alternative retention and selectivity. In the end, the two most interesting ligands used as complementary columns were 2-PIC and BEH, as they provided suitable peak shapes for the basic drugs and almost orthogonal selectivities.

  1. Application of Radiation Chemistry to Some Selected Technological Issues Related to the Development of Nuclear Energy.

    Science.gov (United States)

    Bobrowski, Krzysztof; Skotnicki, Konrad; Szreder, Tomasz

    2016-10-01

    The most important contributions of radiation chemistry to some selected technological issues related to water-cooled reactors, reprocessing of spent nuclear fuel and high-level radioactive wastes, and fuel evolution during final radioactive waste disposal are highlighted. Chemical reactions occurring at the operating temperatures and pressures of reactors and involving primary transients and stable products from water radiolysis are presented and discussed in terms of the kinetic parameters and radiation chemical yields. The knowledge of these parameters is essential since they serve as input data to the models of water radiolysis in the primary loop of light water reactors and super critical water reactors. Selected features of water radiolysis in heterogeneous systems, such as aqueous nanoparticle suspensions and slurries, ceramic oxides surfaces, nanoporous, and cement-based materials, are discussed. They are of particular concern in the primary cooling loops in nuclear reactors and long-term storage of nuclear waste in geological repositories. This also includes radiation-induced processes related to corrosion of cladding materials and copper-coated iron canisters, dissolution of spent nuclear fuel, and changes of bentonite clays properties. Radiation-induced processes affecting stability of solvents and solvent extraction ligands as well oxidation states of actinide metal ions during recycling of the spent nuclear fuel are also briefly summarized.

  2. Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multilayer model ADCHAM

    Energy Technology Data Exchange (ETDEWEB)

    Roldin, P.; Eriksson, A. C.; Nordin, E. Z.; Hermansson, E.; Mogensen, Ditte; Rusanen, A.; Boy, Michael; Swietlicki, E.; Svenningsson, Birgitta; Zelenyuk, Alla; Pagels, J.

    2014-08-11

    We have developed the novel Aerosol Dynamics, gas- and particle- phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas phase Master Chemical Mechanism version 3.2, an aerosol dynamics and particle phase chemistry module (which considers acid catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study: 1) the mass transfer limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), 2) the slow and almost particle size independent evaporation of α-pinene secondary organic aerosol (SOA) particles, and 3) the influence of chamber wall effects on the observed SOA formation in smog chambers.

  3. Theoretical Hammett Plot for the Gas-Phase Ionization of Benzoic Acid versus Phenol: A Computational Chemistry Lab Exercise

    Science.gov (United States)

    Ziegler, Blake E.

    2013-01-01

    Computational chemistry undergraduate laboratory courses are now part of the chemistry curriculum at many universities. However, there remains a lack of computational chemistry exercises available to instructors. This exercise is presented for students to develop skills using computational chemistry software while supplementing their knowledge of…

  4. Structure-property relations in bismuth-based Aurivillius phases

    CERN Document Server

    Sandoval, D Y S

    2001-01-01

    ferroelectric phase transition in Aurivillius phases. Orientational and translational domains arising from a change in crystal class and a doubling of the unit cell were detected. At the (PE) tetragonal - (PE) orthorhombic phase transition 90 deg ferroelastic domains are formed. Finally, at the (PE) orthorhombic to the (FE) orthorhombic phase transition centro-symmetry is lost, the ferroelastic orientation domain boundaries (ODBs) become ferroelectric and anti phase boundaries (APBs) are coupled with inversion domain boundaries (IDBs). The aim of this work was to relate the onset temperature and amplitude (qualitatively) of rotations of the octahedra to the onset of ferroelectricity in a range of Aurivillius compounds. Several stoichiometries were tested, including MBi sub 2 Nb sub 2 O sub 9 , MBi sub 4 Ti sub 4 O sub 1 sub 5 , M sub 2 Bi sub 4 Ti sub 5 O sub 1 sub 8 and MBi sub 8 Ti sub 7 O sub 2 sub 7 with the substitution of divalent (Ca sup 2 sup + , Sr sup 2 sup + , Pb sup 2 sup + and Ba sup 2 sup +) and...

  5. Spectroscopic and modeling investigations of the gas-phase chemistry and composition in microwave plasma activated B2H6/Ar/H2 mixtures.

    Science.gov (United States)

    Ma, Jie; Richley, James C; Davies, David R W; Cheesman, Andrew; Ashfold, Michael N R; Mankelevich, Yuri A

    2010-02-25

    This paper describes a three-pronged study of microwave (MW) activated B(2)H(6)/Ar/H(2) plasmas as a precursor to diagnosis of the B(2)H(6)/CH(4)/Ar/H(2) plasmas used for the chemical vapor deposition of B-doped diamond. Absolute column densities of B atoms and BH radicals have been determined by cavity ring-down spectroscopy as a function of height (z) above a molybdenum substrate and of the plasma process conditions (B(2)H(6) and Ar partial pressures, total pressure, and supplied MW power). Optical emission spectroscopy has been used to explore variations in the relative densities of electronically excited BH, H, and H(2) species as a function of the same process conditions and of time after introducing B(2)H(6) into a pre-existing Ar/H(2) plasma. The experimental measurements are complemented by extensive 2-D(r, z) modeling of the plasma chemistry, which results in refinements to the existing B/H chemistry and thermochemistry and demonstrates the potentially substantial loss of gas-phase BH(x) species through reaction with trace quantities of air/O(2) in the process gas mixture and heterogeneous processes occurring at the reactor wall.

  6. Partitioning of metals in different binding phases of tropical estuarine sediments: importance of metal chemistry.

    Science.gov (United States)

    Chakraborty, Parthasarathi; Chakraborty, Sucharita; Vudamala, Krushna; Sarkar, Arindam; Nath, B Nagender

    2016-02-01

    Distribution of metals in different binding phases of estuarine sediments provides chemically significant description of metal-sediment interactions. This study describes the influences of ligand field stabilization energy (LFSE), Jahn-Teller effect, and water exchange rate (k-w) on metal distribution in different binding phases of estuarine sediments. It was found that Cu had highest affinity for organic binding phases in the studied sediments followed by Ni and Pb. However, Pb showed strong association with Fe/Mn oxide phases followed by Ni and Cu. Faster k-w of Cu (II) (1 × 10(9) s(-1)) increased the rate of complex formation of Cu(2+) ion with ligand in the organic phases. The Cu-ligand (from organic phase) complexes gained extra stability by the Jahn-Teller effect. The combined effects of these two phenomena and high ionic potential increased the association of Cu with the organic phases of the sediments than Ni and Pb. The smaller ionic radii of Ni(2+) (0.72 Å) than Pb(2+) (1.20 Å) increase the stability of Ni-ligand complexes in the organic phase of the sediments. High LFSE of Ni(II) (compared with Pb(2+) ions) also make Ni-organic complexes increasingly stable than Pb. High k-w (7 × 10(9) s(-1)) of Pb did not help it to associate with organic phases in the sediments. The high concentration of Pb in the Fe/Mn oxyhydroxide binding phase was probably due to co-precipitation of Pb(2+) and Fe(3+). High surface area or site availability for Pb(2+) ion on Fe oxyhydroxide phase was probably responsible for the high concentration of Pb in Fe/Mn oxyhydroxide phase. Increasing concentrations of Cu in organic phases with the increasing Cu loading suggest that enough binding sites were available for Cu in the organic binding phases of the sediments. This study also describes the influence of nature of sedimentary organic carbon (terrestrial and marine derived OC) in controlling these metal distribution and speciation in marine sediment.

  7. Phase relations in the U-Mo-Al ternary system

    Science.gov (United States)

    Noël, H.; Tougait, O.; Dubois, S.

    2009-06-01

    The phase relations in the U-Mo-Al system of quenched samples annealed at 800 °C for 2 weeks and at 400 °C for 2 months have been established using X-ray powder diffraction, scanning electron microscopy and energy dispersive spectroscopic analysis performed at room temperature. Two ternary Al-rich phases, UMo 2-xAl 20+x and U 6Mo 4+xAl 43-x are found stable at 800 °C and 400 °C. They show significant homogeneity ranges resulting from Mo/Al substitution mechanism on various mixed crystallographic sites, as evidenced by single-crystal structure refinements. Substitution of up to 25 at.% of Al by Mo atoms is also observed for UAl 2 (cubic MgCu 2-type) giving a quite large extension (UAl 2-xMo x, 0 nuclear fuel plates can be successively estimated as composed of the two- and three-phase fields equilibrium indicated on the assessment of the phase relations drawn for samples heat-treated at 400 °C.

  8. Development and Assessment of a Diagnostic Tool to Identify Organic Chemistry Students' Alternative Conceptions Related to Acid Strength

    Science.gov (United States)

    McClary, LaKeisha M.; Bretz, Stacey Lowery

    2012-01-01

    The central goal of this study was to create a new diagnostic tool to identify organic chemistry students' alternative conceptions related to acid strength. Twenty years of research on secondary and college students' conceptions about acids and bases has shown that these important concepts are difficult for students to apply to qualitative problem…

  9. Using Mean Absolute Relative Phase, Deviation Phase and Point-Estimation Relative Phase to Measure Postural Coordination in a Serial Reaching Task.

    Science.gov (United States)

    Galgon, Anne K; Shewokis, Patricia A

    2016-03-01

    The objectives of this communication are to present the methods used to calculate mean absolute relative phase (MARP), deviation phase (DP) and point estimate relative phase (PRP) and compare their utility in measuring postural coordination during the performance of a serial reaching task. MARP and DP are derived from continuous relative phase time series representing the relationship between two body segments or joints during movements. MARP is a single measure used to quantify the coordination pattern and DP measures the stability of the coordination pattern. PRP also quantifies coordination patterns by measuring the relationship between the timing of maximal or minimal angular displacements of two segments within cycles of movement. Seven young adults practiced a bilateral serial reaching task 300 times over 3 days. Relative phase measures were used to evaluate inter-joint relationships for shoulder-hip (proximal) and hip-ankle (distal) postural coordination at early and late learning. MARP, PRP and DP distinguished between proximal and distal postural coordination. There was no effect of practice on any of the relative phase measures for the group, but individual differences were seen over practice. Combined, MARP and DP estimated stability of in-phase and anti-phase postural coordination patterns, however additional qualitative movement analyses may be needed to interpret findings in a serial task. We discuss the strengths and limitations of using MARP and DP and compare MARP and DP to PRP measures in assessing coordination patterns in the context of various types of skillful tasks. Key pointsMARP, DP and PRP measures coordination between segments or joint anglesAdvantages and disadvantages of each measure should be considered in relationship to the performance taskMARP and DP may capture coordination patterns and stability of the patterns during discrete tasks or phases of movements within a taskPRP and SD or PRP may capture coordination patterns and

  10. Glycol-Water Interactions and co-existing phases and Temperature Dependent Solubility. An Example Of Carbon-Hydrogen Chemistry In Water

    CERN Document Server

    Michael, Fredrick

    2010-01-01

    Recently there has been great interest in Glycol-Water chemistry and solubility and temperature dependent phase dynamics. The Glycol-Water biochemistry of interactions is present in plant biology and chemistry, is of great interest to chemical engineers and biochemists as it is a paradigm of Carbon-Hydrogen Water organic chemistry. There is an interest moreover in formulating a simpler theory and computation model for the Glycol-Water interaction and phase dynamics, that is not fully quantum mechanical yet has the high accuracy available from a fully quantum mechanical theory of phase transitions of fluids and Fermi systems. Along these lines of research interest we have derived a Lennard-Jones -like theory of interacting molecules-Water in a dissolved adducts of Glycol-Water system interacting by Hydrogen bonds whose validity is supported at the scale of interactions by other independent molecular dynamics investigations that utilize force fields dependent on their experimental fittings to the Lennard-Jones ...

  11. Maximal-acceleration phase space relativity from Clifford algebras

    CERN Document Server

    Castro, C

    2002-01-01

    We present a new physical model that links the maximum speed of light with the minimal Planck scale into a maximal-acceleration Relativity principle in the spacetime tangent bundle and in phase spaces (cotangent bundle). Crucial in order to establish this link is the use of Clifford algebras in phase spaces. The maximal proper-acceleration bound is a = c^2/ \\Lambda in full agreement with the old predictions of Caianiello, the Finslerian geometry point of view of Brandt and more recent results in the literature. We present the reasons why an Extended Scale Relativity based on Clifford spaces is physically more appealing than those based on kappa-deformed Poincare algebras and the inhomogeneous quantum groups operating in quantum Minkowski spacetimes. The main reason being that the Planck scale should not be taken as a deformation parameter to construct quantum algebras but should exist already as the minimum scale in Clifford spaces.

  12. The role of European Federation of Clinical Chemistry and Laboratory Medicine Working Group for Preanalytical Phase in standardization and harmonization of the preanalytical phase in Europe.

    Science.gov (United States)

    Cornes, Michael P; Church, Stephen; van Dongen-Lases, Edmée; Grankvist, Kjell; Guimarães, João T; Ibarz, Mercedes; Kovalevskaya, Svetlana; Kristensen, Gunn Bb; Lippi, Giuseppe; Nybo, Mads; Sprongl, Ludek; Sumarac, Zorica; Simundic, Ana-Maria

    2016-09-01

    Patient safety is a leading challenge in healthcare and from the laboratory perspective it is now well established that preanalytical errors are the major contributor to the overall rate of diagnostic and therapeutic errors. To address this, the European Federation of Clinical Chemistry and Laboratory Medicine Working Group for Preanalytical Phase (EFLM WG-PRE) was established to lead in standardization and harmonization of preanalytical policies and practices at a European level. One of the key activities of the WG-PRE is the organization of the biennial EFLM-BD conference on the preanalytical phase to provide a forum for National Societies (NS) to discuss their issues. Since 2012, a year after the first Preanalytical phase conference, there has been a rapid growth in the number of NS with a working group engaged in preanalytical phase activities and there are now at least 19 countries that have one. As a result of discussions with NS at the third conference held in March 2015 five key areas were identified as requiring harmonisation. These were test ordering, sample transport and storage, patient preparation, sampling procedures and management of unsuitable specimens. The article below summarises the work that has and will be done in these areas. The goal of this initiative is to ensure the EFLM WG-PRE produces work that meets the needs of the European laboratory medicine community. Progress made in the identified areas will be updated at the next preanalytical phase conference and show that we have produced guidance that has enhanced standardisation in the preanalytical phase and improved patient safety throughout Europe.

  13. Experimental constraints on phase relations in subducted continental crust

    Science.gov (United States)

    Hermann, Jörg

    2002-01-01

    Synthesis piston cylinder experiments were carried out in the range 2.0-4.5 GPa and 680-1,050 °C to investigate phase relations in subducted continental crust. A model composition (KCMASH) has been used because all major ultrahigh-pressure (UHP) minerals of the whole range of rock types typical for continental crust can be reproduced within this system. The combination of experimental results with phase petrologic constraints permits construction of a UHP petrogenetic grid. The phase relations demonstrate that the most important UHP paragenesis consists of coesite, kyanite, phengite, clinopyroxene, and garnet in subducted continental crust. Below 700 °C talc is stable instead of garnet. As most of these minerals are also stable at much lower pressure and temperature conditions it is thus not easy to recognize UHP metamorphism in subducted crust. A general feature, however, is the absence of feldspars at H2O-saturated conditions. Plagioclase is never stable at UHP conditions, but K-feldspar can occur in H2O-undersaturated rocks. Mineral compositions in the experiments are fully buffered by coexisting phases. The Si content of phengite and biotite increase with increasing pressure. At 4.0 GPa, 780 °C, biotite contains 3.28 Si per formula unit, which is most probably caused by solid solution of biotite with talc. Above 800 °C, the CaAl2SiO6 component in clinopyroxene buffered with kyanite, coesite and a Mg-phase increases with increasing temperature, providing a tool to distinguish between 'cold' and 'hot' eclogites. Up to 10% Ca-eskolaite (Ca0.5[]0.5AlSi2O6) in clinopyroxene has been found at the highest temperature and pressure investigated (>900 °C, 4.5 GPa). Garnet buffered with coesite, kyanite and clinopyroxene displays an increase of grossular component with increasing pressure for a given temperature. Although the investigated system represents a simplification with respect to natural rocks, it helps to constrain general features of subducted continental

  14. Peer-review process in journals dealing with chemistry and related subjects published in Serbia

    Directory of Open Access Journals (Sweden)

    Dekanski Aleksandar

    2016-01-01

    Full Text Available A survey was conducted among editors of journals publishing in the field of chemistry, chemical technology and related topics in Serbia, aiming to collect information on their experience, problems and difficulties during peer-review process. Editors from 22 journals out of 27 which regularly published during 2015 replied. General data on journals were collected from responses obtained from editors-in-chief, whereas all editors (including sub-editors and section editors participated in a questionnaire concerning peer-review procedure. Additionally, they were asked to evaluate quality of reports and attitude of reviewers, discuss present situation and suggest measures to improve peer-review process. Greatest problems encountered by editors in peer-review process can be summarized as follows: low rate of acceptance to review, low quality of reports, sometimes due to reviewer’s bias or his/her inability to properly understand review process. A method used to search for reviewers does not substantially influence quality of reports. Editors agree that introduction of On-Line process and creation of precise instructions for reviewers, education of potential reviewers, as well as social, public and professional recognition and appreciation of reviewers’ work, are the most important measures to improve quality of peer-review process and, consecutively, quality of published articles and journals.

  15. Carbon nanotube inner phase chemistry: the Cl- exchange SN2 reaction.

    Science.gov (United States)

    Halls, Mathew D; Raghavachari, Krishnan

    2005-10-01

    Density functional calculations have been carried out to investigate the nature of the inner phase of a (6,6) carbon nanotube, using the Cl(-) exchange S(N)2 reaction as an indicator. Inside the carbon nanotube the classical barrier height increases by 6.6 kcal/mol due to the nanotube polarizability. This suggests that the inner phase environment can be considered a form of solid solvation, offering the possibility of obtaining altered guest properties and reactivity through dielectric stabilization.

  16. Hamilton geometry: Phase space geometry from modified dispersion relations

    CERN Document Server

    Barcaroli, Leonardo; Gubitosi, Giulia; Loret, Niccoló; Pfeifer, Christian

    2015-01-01

    We describe the Hamilton geometry of the phase space of particles whose motion is characterised by general dispersion relations. In this framework spacetime and momentum space are naturally curved and intertwined, allowing for a simultaneous description of both spacetime curvature and non-trivial momentum space geometry. We consider as explicit examples two models for Planck-scale modified dispersion relations, inspired from the $q$-de Sitter and $\\kappa$-Poincar\\'e quantum groups. In the first case we find the expressions for the momentum and position dependent curvature of spacetime and momentum space, while for the second case the manifold is flat and only the momentum space possesses a nonzero, momentum dependent curvature. In contrast, for a dispersion relation that is induced by a spacetime metric, as in General Relativity, the Hamilton geometry yields a flat momentum space and the usual curved spacetime geometry with only position dependent geometric objects.

  17. Structural isomerization of the gas-phase 2-norbornyl cation revealed with infrared spectroscopy and computational chemistry.

    Science.gov (United States)

    Mosley, Jonathan D; Young, Justin W; Agarwal, Jay; Schaefer, Henry F; Schleyer, Paul v R; Duncan, Michael A

    2014-06-02

    In an attempt to produce the 2-norbornyl cation (2NB(+)) in the gas phase, protonation of norbornene was accomplished in a pulsed discharge ion source coupled with a supersonic molecular beam. The C7H11(+) cation was size-selected in a time-of-flight mass spectrometer and investigated with infrared laser photodissociation spectroscopy using the method of "tagging" with argon. The resulting vibrational spectrum, containing sharp bands in the C-H stretching and fingerprint regions, was compared to that predicted by computational chemistry. However, the measured spectrum did not match that of 2NB(+), prompting a detailed computational study of other possible isomers of C7H11(+). This study finds five isomers more stable than 2NB(+). The spectrum obtained corresponds to the 1,3-dimethylcyclopentenyl cation, the global minimum-energy structure for C7H11(+), which is produced through an unanticipated ring-opening rearrangement path.

  18. The effect of interactive gas-phase chemistry and aerosols on climate simulations over the last millennium

    Science.gov (United States)

    Tsigaridis, K.; LeGrande, A. N.; Healy, R. J.; Schmidt, G. A.

    2013-12-01

    Significant computational resources are required for long transient simulations using coupled atmosphere-ocean general circulation models. Individual simulations from the NINT version of GISS ModelE-R (part of the CMIP5 archive) of the last millennium, from year 850 to 2005, enabled with only 3 water isotopologue tracers, required ~9 months of computational time on the state-of-the-art parallel computing cluster of NCCS. The additional requirements of the full chemistry module would increase this by a factor of ~3. And yet, it is well known that chemistry and aerosols are very important on climate, both regional and global. Therefore, we have designed a set of experiments where the ocean and sea ice boundary conditions of the coupled model, paired with the land surface, greenhouse gases, insolation, and total solar irradiance (TSI) forcing from the PMIP3 protocol are applied to a series of full-chemistry GISS ModelE snap-shots each 50-years through the last millennium. We will present results from atmosphere-only model simulations with the GISS ModelE, which includes interactive gas-phase chemistry and aerosols at decadal-scale time slices, driven by millennial-length simulations performed with the same model when coupled with an ocean model. The boundary conditions for the transient simulations follow the last millennium coordinated PMIP3 experiment protocol. This experiment directly links in with other pre-industrial experiments being completed as part of IPCC AR5, using the same model and resolution as in GISS IPCC AR5. The impact of the presence of short-lived gases and aerosols on the simulated climate is studied. The role of previously omitted forcing mechanisms will be performed during the whole simulated period. The results presented are the initial runs from a larger set of experiments that will assess the climate impact of changes to dust, sea-salt, and ocean-derived sulfate, biomass burning ozone-precursors and aerosols, organic carbon, wetland methane

  19. Critical Test of Some Computational Chemistry Methods for Prediction of Gas-Phase Acidities and Basicities.

    Science.gov (United States)

    Toomsalu, Eve; Koppel, Ilmar A; Burk, Peeter

    2013-09-10

    Gas-phase acidities and basicities were calculated for 64 neutral bases (covering the scale from 139.9 kcal/mol to 251.9 kcal/mol) and 53 neutral acids (covering the scale from 299.5 kcal/mol to 411.7 kcal/mol). The following methods were used: AM1, PM3, PM6, PDDG, G2, G2MP2, G3, G3MP2, G4, G4MP2, CBS-QB3, B1B95, B2PLYP, B2PLYPD, B3LYP, B3PW91, B97D, B98, BLYP, BMK, BP86, CAM-B3LYP, HSEh1PBE, M06, M062X, M06HF, M06L, mPW2PLYP, mPW2PLYPD, O3LYP, OLYP, PBE1PBE, PBEPBE, tHCTHhyb, TPSSh, VSXC, X3LYP. The addition of the Grimmes empirical dispersion correction (D) to B2PLYP and mPW2PLYP was evaluated, and it was found that adding this correction gave more-accurate results when considering acidities. Calculations with B3LYP, B97D, BLYP, B2PLYPD, and PBE1PBE methods were carried out with five basis sets (6-311G**, 6-311+G**, TZVP, cc-pVTZ, and aug-cc-pVTZ) to evaluate the effect of basis sets on the accuracy of calculations. It was found that the best basis sets when considering accuracy of results and needed time were 6-311+G** and TZVP. Among semiempirical methods AM1 had the best ability to reproduce experimental acidities and basicities (the mean absolute error (mae) was 7.3 kcal/mol). Among DFT methods the best method considering accuracy, robustness, and computation time was PBE1PBE/6-311+G** (mae = 2.7 kcal/mol). Four Gaussian-type methods (G2, G2MP2, G4, and G4MP2) gave similar results to each other (mae = 2.3 kcal/mol). Gaussian-type methods are quite accurate, but their downside is the relatively long computational time.

  20. Structure of olefin-imidacloprid and gas-phase fragmentation chemistry of its protonated form.

    Science.gov (United States)

    Fusetto, Roberto; White, Jonathan M; Hutton, Craig A; O'Hair, Richard A J

    2016-02-01

    One of the major insect metabolites of the widely used neonicotinoid insecticide imidacloprid, 1 (1-[(6-chloro-3-pyridinyl)methyl]-N-nitro-1H-imidazol-2-amine), is the olefin 2. To better understand how the structure of olefin 2 relates to the gas-phase fragmentation of its protonated form, 2H(+), X-ray crystallography, tandem mass spectrometry experiments and DFT calculations were carried out. Olefin 2 was found to be in a tautomeric form where the proton is on the N(1) position of the imidazole ring and forms a hydrogen bond to one of the oxygen atoms of the coplanar nitroamine group. Under conditions of low-energy collision-induced dissociation (CID) in a linear ion trap, 2H(+), formed via electrospray ionization (ESI), fragments via a major loss of water, together with minor competing losses of HNO2 and NO2•.This contrasts with 1H+, which mainly undergoes bond homolysis via NO2• loss. Thus, installation of the double bond in 2 plays a key role in facilitating the loss of water. DFT calculations, carried out using the B3LYP/6-311G++(d,p) level of theory, revealed that loss of water was energetically more favourable compared to HNO2 and NO2• loss. Three multistep, energetically accessible mechanisms were identified for loss of water from 2H(+), and these have the following barriers: (I) direct proton transfer from N(5) of the pyridine to O(1) on the NO2 group (119 kJ mol(-1)); (II) rotation of the N(2)-N(4) bond (117 kJ mol(-1)); (III) 1,3-intramolecular proton transfer between the two oxygen atoms of the NO2 group (145 kJ mol(-1)). Given that the lowest barrier for the losses of HNO2 and NO2• is 156 kJ mol(-1), it is likely that all three water loss mechanisms occur concurrently.

  1. PhasePlot: A Software Program for Visualizing Phase Relations Computed Using Thermochemical Models and Databases

    Science.gov (United States)

    Ghiorso, M. S.

    2011-12-01

    A new software program has been developed for Macintosh computers that permits the visualization of phase relations calculated from thermodynamic data-model collections. The data-model collections of MELTS (Ghiorso and Sack, 1995, CMP 119, 197-212), pMELTS (Ghiorso et al., 2002, G-cubed 3, 10.1029/2001GC000217) and the deep mantle database of Stixrude and Lithgow-Bertelloni (2011, GJI 184, 1180-1213) are currently implemented. The software allows users to enter a system bulk composition and a range of reference conditions and then calculate a grid of phase relations. These relations may be visualized in a variety of ways including phase diagrams, phase proportion plots, and contour diagrams of phase compositions and abundances. Results may be exported into Excel or similar spreadsheet applications. Flexibility in stipulating reference conditions permit the construction of temperature-pressure, temperature-volume, entropy-pressure, or entropy-volume display grids. Calculations on the grid are performed for fixed bulk composition or in open systems governed by user specified constraints on component chemical potentials (e.g., specified oxygen fugacity buffers). The calculation engine for the software is optimized for multi-core compute architectures and is very fast, allowing a typical grid of 64 points to be calculated in under 10 seconds on a dual-core laptop/iMac. The underlying computational thermodynamic algorithms have been optimized for speed and robust behavior. Taken together, both of these advances facilitate in classroom demonstrations and permit novice users to work with the program effectively, focusing on problem specification and interpretation of results rather than on manipulation and mechanics of computation - a key feature of an effective instructional tool. The emphasis in this software package is graphical visualization, which aids in better comprehension of complex phase relations in multicomponent systems. Anecdotal experience in using Phase

  2. Comparative assessment of three-phase oil relative permeability models

    Science.gov (United States)

    Ranaee, Ehsan; Riva, Monica; Porta, Giovanni M.; Guadagnini, Alberto

    2016-07-01

    We assess the ability of 11 models to reproduce three-phase oil relative permeability (kro) laboratory data obtained in a water-wet sandstone sample. We do so by considering model performance when (i) solely two-phase data are employed to render predictions of kro and (ii) two and three-phase data are jointly used for model calibration. In the latter case, a Maximum Likelihood (ML) approach is used to estimate model parameters. The tested models are selected among (i) classical models routinely employed in practical applications and implemented in commercial reservoir software and (ii) relatively recent models which are considered to allow overcoming some drawbacks of the classical formulations. Among others, the latter set of models includes the formulation recently proposed by Ranaee et al., which has been shown to embed the critical effects of hysteresis, including the reproduction of oil remobilization induced by gas injection in water-wet media. We employ formal model discrimination criteria to rank models according to their skill to reproduce the observed data and use ML Bayesian model averaging to provide model-averaged estimates (and associated uncertainty bounds) of kro by taking advantage of the diverse interpretive abilities of all models analyzed. The occurrence of elliptic regions is also analyzed for selected models in the framework of the classical fractional flow theory of displacement. Our study confirms that model outcomes based on channel flow theory and classical saturation-weighted interpolation models do not generally yield accurate reproduction of kro data, especially in the regime associated with low oil saturations, where water alternating gas injection (WAG) techniques are usually employed for enhanced oil recovery. This negative feature is not observed in the model of Ranaee et al. (2015) due to its ability to embed key effects of pore-scale phase distributions, such as hysteresis effects and cycle dependency, for modeling kro observed

  3. Factors related to the economic sustainability of two-year chemistry-based technology training programs

    Science.gov (United States)

    Backus, Bridgid A.

    Two-year chemistry-based technology training (CBTT) programs in the U.S. are important in the preparation of the professional technical workforce. The purpose of this study was to identify, examine, and analyze factors related to the economic sustainability of CBTT programs. A review of literature identified four clustered categories of 31 sub-factors related to program sustainability. Three research questions relating to program sustainability were: (1) What is the relative importance of the identified factors?, (2) What differences exist between the opinions of administrators and faculty?, and (3) What are the interrelationships among the factors? In order to answer these questions, survey data gathered from CBTT programs throughout the United States were analyzed statistically. Conclusions included the following: (1) Rank order of the importance to sustainability of the clustered categories was: (1) Partnerships, (2) Employer and Student Educational Goals, (3) Faculty and Their Resources, and (4) Community Perceptions and Marketing Strategies. (2) Significant correlations between ratings of sustainability and the sub-factors included: degree of partnering, college responsiveness, administration involvement in partnerships, experiential learning opportunities, employer input in curriculum development, use of skill standards, number of program graduates, student job placement, professional development opportunities, administrator support, presence of a champion, flexible scheduling, program visibility, perception of chemical technicians, marketing plans, and promotion to secondary students. (3) Faculty and administrators differed significantly on only two sub-factor ratings: employer assisted curriculum development, and faculty workloads. (4) Significant differences in ratings by small program faculty and administrators and large program faculty and administrators were indicated, with most between small program faculty and large program administrators. The study

  4. Chromatographic retention behaviour, modelling and separation optimisation of the quaternary ammonium salt isometamidium chloride and related compounds on a range of reversed-phase liquid chromatographic stationary phases.

    Science.gov (United States)

    Schad, Gesa J; Euerby, Melvin R; Skellern, Graham G; Tettey, Justice N A

    2012-07-01

    This paper describes the reversed-phase liquid chromatographic behaviour of the trypanocidal quaternary ammonium salt isometamidium chloride and its related compounds on a range of liquid chromatographic phases possessing alkyl and phenyl ligands on the same inert silica. In a parallel study with various extended polar selectivity phases which possessed different hydrophobic/silanophilic (hydrogen bonding) activity ratios, the chromatographic retention/selectivities of the quaternary ammonium salts was shown to be due to a co-operative mechanism between hydrophobic and silanophilic interactions. The highly aromatic and planar isometamidium compounds were found to be substantially retained on stationary phases containing aromatic functionality via strong π-π interactions. The chemometric approach of principal component analysis was used to characterise the chromatographic behaviour of the isometamidium compounds on the differing phases and to help identify the dominant retention mechanism(s). Two-dimensional (temperature/gradient) retention modelling was employed to develop and optimise a rapid liquid chromatography method for the separation of the six quaternary ammonium salts within 2.5 min which would be suitable for bioanalysis using liquid chromatography-mass spectrometry. This is the first reported systematic study of the relationship between stationary phase chemistries and retention/selectivity for a group of quaternary ammonium salts.

  5. The Pictet-Spengler reaction in solid-phase combinatorial chemistry

    DEFF Research Database (Denmark)

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

    2003-01-01

    The Pictet-Spengler reaction is an important reaction for the generation of tetrahydro-beta-carbolines and tetrahydroisoquinoline ring systems, which exhibit a range of biological and pharmacological properties. This review covers the solid-phase Pictet-Spengler reaction, as employed in solid-pha...

  6. Ambiguity of mapping the relative phase of blood pulsations

    Science.gov (United States)

    Teplov, Victor; Nippolainen, Ervin; Makarenko, Alexander A.; Giniatullin, Rashid; Kamshilin, Alexei A.

    2014-01-01

    Blood pulsation imaging (BPI) is a non-invasive optical method based on photoplethysmography (PPG). It is used for the visualization of changes in the spatial distribution of blood in the microvascular bed. BPI specifically allows measurements of the relative phase of blood pulsations and using it we detected a novel type of PPG fast waveforms, which were observable in limited areas with asynchronous regional blood supply. In all subjects studied, these fast waveforms coexisted with traditional slow waveforms of PPG. We are therefore presenting a novel lock-in image processing technique of blood pulsation imaging, which can be used for detailed temporal characterization of peripheral microcirculation. PMID:25401026

  7. Ambiguity of mapping the relative phase of blood pulsations.

    Science.gov (United States)

    Teplov, Victor; Nippolainen, Ervin; Makarenko, Alexander A; Giniatullin, Rashid; Kamshilin, Alexei A

    2014-09-01

    Blood pulsation imaging (BPI) is a non-invasive optical method based on photoplethysmography (PPG). It is used for the visualization of changes in the spatial distribution of blood in the microvascular bed. BPI specifically allows measurements of the relative phase of blood pulsations and using it we detected a novel type of PPG fast waveforms, which were observable in limited areas with asynchronous regional blood supply. In all subjects studied, these fast waveforms coexisted with traditional slow waveforms of PPG. We are therefore presenting a novel lock-in image processing technique of blood pulsation imaging, which can be used for detailed temporal characterization of peripheral microcirculation.

  8. Novel chemistry of alpha-tosyloxy ketones: applications to the solution- and solid-phase synthesis of privileged heterocycle and enediyne libraries

    DEFF Research Database (Denmark)

    Nicolaou, K C; Montagnon, T; Ulven, T

    2002-01-01

    -tosyloxy ketones are engaged by "hard" versus "soft" nucleophiles. The accessibility and site-selectivity of the chemistry demonstrated herein offer the promise of an expanded use for this moiety in solid-phase library construction, in particular, and in the field of organic synthesis, in general....

  9. Phase chemistry in process models for cement clinker and lime production

    OpenAIRE

    2014-01-01

    The goal of the thesis is to evaluate if developed phase chemical process models for cement clinker and lime production processes are reliable to use as predictive tools in understanding the changes when introducing sustainability measures. The thesis describes the development of process simulation models in the application of sustainability measures as well as the evaluation of these models. The motivation for developing these types of models arises from the need to predict the chemical and ...

  10. Environmental mobility of cobalt-Influence of solid phase characteristics and groundwater chemistry.

    Science.gov (United States)

    Payne, T E; Itakura, T; Comarmond, M J; Harrison, J J

    2009-01-01

    The adsorption of cobalt on samples from a potential waste repository site in an arid region was investigated in batch experiments, as a function of various solution phase parameters including the pH and ionic strength. The samples were characterized using a range of techniques, including BET surface area measurements, total clay content and quantitative X-ray diffraction. The statistical relationships between the measured cobalt distribution coefficients (K(d) values) and the solid and liquid phase characteristics were assessed. The sorption of cobalt increased with the pH of the aqueous phase. In experiments with a fixed pH value, the measured K(d) values were strongly correlated to the BET surface area, but not to the amount of individual clay minerals (illite, kaolinite or smectite). A further set of sorption experiments was undertaken with two samples of distinctive mineralogy and surface area, and consequently different sorption properties. A simple surface complexation model (SCM) that conceptualized the surface sites as having equivalent sorption properties to amorphous Fe-oxide was moderately successful in explaining the pH dependence of the sorption data on these samples. Two different methods of quantifying the input parameters for the SCM were assessed. While a full SCM for cobalt sorption on these complex environmental substrates is not yet possible, the basic applicability and predictive capability of this type of modeling is demonstrated. A principal requirement to further develop the modeling approach is adequate models for cobalt sorption on component mineral phases of complex environmental sorbents.

  11. Oxidation of methionine residues in polypeptide ions via gas-phase ion/ion chemistry.

    Science.gov (United States)

    Pilo, Alice L; McLuckey, Scott A

    2014-06-01

    The gas-phase oxidation of methionine residues is demonstrated here using ion/ion reactions with periodate anions. Periodate anions are observed to attach in varying degrees to all polypeptide ions irrespective of amino acid composition. Direct proton transfer yielding a charge-reduced peptide ion is also observed. In the case of methionine and, to a much lesser degree, tryptophan-containing peptide ions, collisional activation of the complex ion generated by periodate attachment yields an oxidized peptide product (i.e., [M + H + O](+)), in addition to periodic acid detachment. Detachment of periodic acid takes place exclusively for peptides that do not contain either a methionine or tryptophan side chain. In the case of methionine-containing peptides, the [M + H + O](+) product is observed at a much greater abundance than the proton transfer product (viz., [M + H](+)). Collisional activation of oxidized Met-containing peptides yields a signature loss of 64 Da from the precursor and/or product ions. This unique loss corresponds to the ejection of methanesulfenic acid from the oxidized methionine side chain and is commonly used in solution-phase proteomics studies to determine the presence of oxidized methionine residues. The present work shows that periodate anions can be used to 'label' methionine residues in polypeptides in the gas phase. The selectivity of the periodate anion for the methionine side chain suggests several applications including identification and location of methionine residues in sequencing applications.

  12. Chemistry, phase formation, and catalytic activity of thin palladium-containing oxide films synthesized by plasma-assisted physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2010-11-26

    The chemistry, microstructure, and catalytic activity of thin films incorporating palladium were studied using scanning and transmission electron microscopies, X-ray diffraction, spectrophotometry, 4-point probe and catalytic tests. The films were synthesized using pulsed filtered cathodic arc and magnetron sputter deposition, i.e. techniques far from thermodynamic equilibrium. Catalytic particles were formed by thermally cycling thin films of the Pd-Pt-O system. The evolution and phase formation in such films as a function of temperature were discussed in terms of the stability of PdO and PtO2 in air. The catalytic efficiency was found to be strongly affected by the chemical composition, with oxidized palladium definitely playing a major role in the combustion of methane. Reactive sputter deposition of thin films in the Pd-Zr-Y-O system allowed us forming microstructures ranging from nanocrystalline zirconia to palladium nanoparticles embedded in a (Zr,Y)4Pd2O matrix. The sequence of phase formation is put in relation to simple thermodynamic considerations.

  13. Phase Chemistry and Thermochemstry on Coordination Behavior of Zinc Chloride with Leucine

    Institute of Scientific and Technical Information of China (English)

    高胜利; 陈三平; 等

    2003-01-01

    The solubility property of the ZnCl2-Leu-H2O(Leu=L-a-leucine) system at 298.15K in the whole concentration range was investigatey by the semimicro-phase equilibrium method.The corresponding solubility diagram and refractive index diagram were constructed.The results indicated that there was one complex formed in this system.namely,Zn(Leu)Cl2.The complex is congruently soluble in water.Based on Phase equilibrium data,the complex was prepared.Its composition and properties were characterized by chemical analysis,elemental analysis,IR spectra,and TG-DTG.The thermochemical properties of coordination reaction of zinc chloride with L-a-leucine were investigated by a microcalorimeter.The enthalpies of solution of L-a-leucine in water and its zinc complex at infinite dilution and the enthalpy change of solid-liquid reaction wrer determined at 298.15K.The enthalpy change of soild phase reaction and the standard enthalpy of formation of zinc complex were claculated.On the basis of experimental and calculated results,three thermodynamic parameters(the activation enthalpy,the activation entropy and the activation free energy),the rate constant and three kinetic parameters(the activation energy,the preexponential constant and the reaction order) of the reaction,and the standard enthalpy of formation of Zn(Leu)2+(aq) were obtained.The results showed that the title reaction took place easily at studied temperature.

  14. Relations between topography, wetlands, vegetation cover and stream water chemistry in boreal headwater catchments in Sweden

    Directory of Open Access Journals (Sweden)

    J.-O. Andersson

    2008-05-01

    Full Text Available A large part of the spatial variation of stream water chemistry is found in headwater streams and small catchments. To understand the dominant processes, taking place in small and heterogeneous catchments, spatial and temporal data with high resolution is needed. In most cases available map data has too low quality and resolution to successfully be used in environmental assessments and modelling. In this study 18 forested catchments (1–4 km2 were selected within a 120×50 km area in the county of Värmland in western Sweden. The aim was to test if topographic and vegetation variables derived from official datasets were correlated to stream water chemistry, represented by DOC, Al, Fe and Si content. A GIS was used to analyse the elevation characteristics, generate topographic indices and calculate the percentage of wetlands and a number of vegetation classes. The results clearly show that the topography has a major influence on the occurrence of wetlands, which has a major influence on stream water chemistry. There were very strong correlations between mean slope and percentage wetland, percentage wetland and DOC, mean slope and DOC and mean topographic wetness index and DOC. The conclusion was that official topographic data, despite uncertain or low quality and resolution, could be useful in the prediction of headwater chemistry in boreal forested catchments.

  15. Study of Heterogeneouse Processes Related to the Chemistry of Tropospheric Oxidants and Aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Davidovits, Paul; Worsnop, D R; Jayne, J T; Colb, C E

    2013-02-13

    The objective of the studies was to elucidate the heterogeneous chemistry of tropospheric aerosols. Experiments were designed to measure both specifically needed parameters, and to obtain systematic data required to build a fundamental understanding of the nature of gas-surface physical and chemical interactions

  16. Content-Related Interactions and Methods of Reasoning within Self-Initiated Organic Chemistry Study Groups

    Science.gov (United States)

    Christian, Karen Jeanne

    2011-01-01

    Students often use study groups to prepare for class or exams; yet to date, we know very little about how these groups actually function. This study looked at the ways in which undergraduate organic chemistry students prepared for exams through self-initiated study groups. We sought to characterize the methods of social regulation, levels of…

  17. How Science/Technology/Society relations are approached in the contents of organic functions in high school chemistry

    Directory of Open Access Journals (Sweden)

    Carmem Lúcia Costa Amaral

    2009-03-01

    Full Text Available This paper aimed to verify how the relation between Science/Technology/Society (STS is present in Chemistry textbooks recommended by the Brazilian Ministry of Education. The interest in textbooks is due to the fact that they constitute important resources used by teachers to prepare their classes. Thus, researches in this area are necessary to indicate how the authors could improve the quality of their books. We believe that one way to do this is the introduction of the STS relation, which took place because of the necessity in establishing new ways of teaching, specially the teaching of science. One of the goals of STS education is to create conditions to develop abilities and competences that qualify the students for discussions concerning scientific and technologic questions of everyday life. The analysis of testbooks used the descriptors and indicators developed by Fracalanza and Megid-Neto (2006 as reference. In order to carry out the study, we chose the area of Organic Chemistry, more specifically contents referring to organic functions, with great use in society. In general, the results showed that STS relations are not totally observed in the investigated contents, contributing to the development of Chemistry classes through activities apart from the students social context.

  18. Depression-Related Brain Connectivity Analyzed by EEG Event-Related Phase Synchrony Measure

    Science.gov (United States)

    Li, Yuezhi; Kang, Cheng; Qu, Xingda; Zhou, Yunfei; Wang, Wuyi; Hu, Yong

    2016-01-01

    This study is to examine changes of functional connectivity in patients with depressive disorder using synchronous brain activity. Event-related potentials (ERPs) were acquired during a visual oddball task in 14 patients with depressive disorder and 19 healthy controls. Electroencephalogram (EEG) recordings were analyzed using event-related phase coherence (ERPCOH) to obtain the functional network. Alteration of the phase synchronization index (PSI) of the functional network was investigated. Patients with depression showed a decreased number of significant electrode pairs in delta phase synchronization, and an increased number of significant electrode pairs in theta, alpha and beta phase synchronization, compared with controls. Patients with depression showed lower target-dependent PSI increment in the frontal-parietal/temporal/occipital electrode pairs in delta-phase synchronization than healthy participants. However, patients with depression showed higher target-dependent PSI increments in theta band in the prefrontal/frontal and frontal-temporal electrode pairs, higher PSI increments in alpha band in the prefrontal pairs and higher increments of beta PSI in the central and right frontal-parietal pairs than controls. It implied that the decrease in delta PSI activity in major depression may indicate impairment of the connection between the frontal and parietal/temporal/occipital regions. The increase in theta, alpha and beta PSI in the frontal/prefrontal sites might reflect the compensatory mechanism to maintain normal cognitive performance. These findings may provide a foundation for a new approach to evaluate the effectiveness of therapeutic strategies for depression. PMID:27725797

  19. Roles of Bulk and Surface Chemistry in the Oxygen Exchange Kinetics and Related Properties of Mixed Conducting Perovskite Oxide Electrodes

    Directory of Open Access Journals (Sweden)

    Nicola H. Perry

    2016-10-01

    Full Text Available Mixed conducting perovskite oxides and related structures serving as electrodes for electrochemical oxygen incorporation and evolution in solid oxide fuel and electrolysis cells, respectively, play a significant role in determining the cell efficiency and lifetime. Desired improvements in catalytic activity for rapid surface oxygen exchange, fast bulk transport (electronic and ionic, and thermo-chemo-mechanical stability of oxygen electrodes will require increased understanding of the impact of both bulk and surface chemistry on these properties. This review highlights selected work at the International Institute for Carbon-Neutral Energy Research (I2CNER, Kyushu University, set in the context of work in the broader community, aiming to characterize and understand relationships between bulk and surface composition and oxygen electrode performance. Insights into aspects of bulk point defect chemistry, electronic structure, crystal structure, and cation choice that impact carrier concentrations and mobilities, surface exchange kinetics, and chemical expansion coefficients are emerging. At the same time, an understanding of the relationship between bulk and surface chemistry is being developed that may assist design of electrodes with more robust surface chemistries, e.g., impurity tolerance or limited surface segregation. Ion scattering techniques (e.g., secondary ion mass spectrometry, SIMS, or low energy ion scattering spectroscopy, LEIS with high surface sensitivity and increasing lateral resolution are proving useful for measuring surface exchange kinetics, diffusivity, and corresponding outer monolayer chemistry of electrodes exposed to typical operating conditions. Beyond consideration of chemical composition, the use of strain and/or a high density of active interfaces also show promise for enhancing performance.

  20. The effect of multilayer ice chemistry on gas-phase deuteration in starless cores

    CERN Document Server

    Sipilä, O; Taquet, V

    2016-01-01

    Aims. We aim to investigate whether a multilayer ice model can be as successful as a bulk ice model in reproducing the observed abundances of various deuterated gas-phase species toward starless cores. Methods. We calculate abundances for various deuterated species as functions of time adopting fixed physical conditions. We also estimate abundance gradients by adopting a modified Bonnor-Ebert sphere as a core model. In the multilayer ice scenario, we consider desorption from one or several monolayers on the surface. Results. We find that the multilayer model predicts abundances of $\\rm DCO^+$ and $\\rm N_2D^+$ that are about an order of magnitude lower than observed, caused by the trapping of CO and $\\rm N_2$ into the grain mantle. As a result of the mantle trapping, deuteration efficiency in the gas phase increases and we find stronger deuterium fractionation in ammonia than what has been observed. Another distinguishing feature of the multilayer model is that $\\rm D_3^+$ becomes the main deuterated ion at hi...

  1. Domain-Specific Expertise of Chemistry Teachers on Context-Based Education about Macro-Micro Thinking in Structure-Property Relations

    Science.gov (United States)

    Dolfing, Ria; Bulte, Astrid M. W.; Pilot, Albert; Vermunt, Jan D.

    2012-01-01

    This study aims to determine and describe the new domain-specific expertise of experienced chemistry teachers in teaching an innovative context-based unit about macro-micro thinking in structure-property relations. The construct of "teachers' domain-specific expertise" was used to analyse the new repertoire chemistry teachers need to acquire to…

  2. Cluster Chemistry

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ Cansisting of eight scientists from the State Key Laboratory of Physical Chemistry of Solid Surfaces and Xiamen University, this creative research group is devoted to the research of cluster chemistry and creation of nanomaterials.After three-year hard work, the group scored a series of encouraging progresses in synthesis of clusters with special structures, including novel fullerenes, fullerene-like metal cluster compounds as well as other related nanomaterials, and their properties study.

  3. Gas Phase Chemistry and Molecular Complexity: How Far Do They Go?

    Science.gov (United States)

    Balucani, Nadia

    2016-07-01

    The accumulation of organic molecules of increasing complexity is believed to be an important step toward the emergence of life. But how massive organic synthesis could occur in primitive Earth, i.e. a water-dominated environment, is a matter of debate. Two alternative theories have been suggested so far: endogenous and exogenous synthesis. In the first theory, the synthesis of simple organic molecules having a strong prebiotic potential (simple prebiotic molecules SPMs, such as H2CO, HCN, HC3N, NH2CHO) occurred directly on our planet starting from simple parent molecules of the atmosphere, liquid water and various energy sources. Miller's experiment was a milestone in this theory, but it was later recognized that the complexity of a planet cannot be reproduced in a single laboratory experiment. Some SPMs have been identified in the N2-dominated atmosphere of Titan (a massive moon of Saturn), which is believed to be reminiscent of the primitive terrestrial atmosphere. As such, the atmosphere of Titan represents a planetary scale laboratory for the comprehension of SPM formation in an environment close enough to primitive Earth and is the current frontier in the endogenous theory exploration. In the exogenous theory, SPMs came from space, the carriers being comets, asteroids and meteorites. The rationale behind this suggestion is that plenty of SPMs have been observed in interstellar clouds (ISCs), including star-forming regions, and in small bodies like comets, asteroids and meteorites. Therefore, the basic idea is that SPMs were formed in the solar nebula, preserved during the early phases of the Solar System formation in the body of comets/asteroids/meteorites and finally delivered to Earth by cometary and meteoritic falls. In this contribution, the status of our knowledge on how SPMs can be formed in the gas phase, either in the primitive terrestrial atmosphere or in the cold nebula from which the Solar System originated, will be presented. Particular attention

  4. The Interaction Between Dynamics and Chemistry of Ozone in the Set-up Phase of the Northern Hemisphere Polar Vortex

    Science.gov (United States)

    Kawa, S. R.; Bevilacqua, R.; Margitan, J. J.; Douglass, A. R.; Schoeberl, M. R.; Hoppel, K.; Sen, B.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    The morphology and evolution of the stratospheric ozone (O3) distribution at high latitudes in the Northern Hemisphere (NH) are examined for the late summer and fall seasons of 1999. This time period sets the O3 initial condition for the SOLVE/THESEO field mission performed during winter 1999-2000. In situ and satellite data are used along with a three-dimensional model of chemistry and transport (CTM) to determine the key processes that control the distribution of O3 in the lower-to-middle stratosphere. O3 in the vortex at the beginning of the winter season is found to be nearly constant from 500 to above 800 K with a value at 3 ppmv +/- approx. 10%. Values outside the vortex are up to a factor of 2 higher and increase significantly with potential temperature. The seasonal time series of data from POAM shows that relatively low O3 mixing ratios, which characterize the vortex in late fall, are already present at high latitudes at the end of summer before the vortex circulation sets up. Analysis of the CTM output shows that the minimum O3 and increase in variance in late summer are the result of: 1) stirring of polar concentric O3 gradients by nascent wave-driven transport, and 2) an acceleration of net photochemical loss with decreasing solar illumination. The segregation of low O3 mixing ratios into the vortex as the circulation strengthens through the fall suggests a possible feedback role between O3 chemistry and the vortex formation dynamics. Trajectory calculations from O3 sample points early in the fall, however, show only a weak correlation between initial O3 mixing ratio and potential vorticity later in the season consistent with order-of-magnitude calculations for the relative importance of O3 in the fall radiative balance at high latitudes. The possible connection between O3 chemistry and the dynamics of vortex formation does suggest that these feedbacks and sensitivities need to be better understood in order to make confident predictions of the recovery

  5. Water chemistry in 179 randomly selected Swedish headwater streams related to forest production, clear-felling and climate.

    Science.gov (United States)

    Löfgren, Stefan; Fröberg, Mats; Yu, Jun; Nisell, Jakob; Ranneby, Bo

    2014-12-01

    From a policy perspective, it is important to understand forestry effects on surface waters from a landscape perspective. The EU Water Framework Directive demands remedial actions if not achieving good ecological status. In Sweden, 44 % of the surface water bodies have moderate ecological status or worse. Many of these drain catchments with a mosaic of managed forests. It is important for the forestry sector and water authorities to be able to identify where, in the forested landscape, special precautions are necessary. The aim of this study was to quantify the relations between forestry parameters and headwater stream concentrations of nutrients, organic matter and acid-base chemistry. The results are put into the context of regional climate, sulphur and nitrogen deposition, as well as marine influences. Water chemistry was measured in 179 randomly selected headwater streams from two regions in southwest and central Sweden, corresponding to 10 % of the Swedish land area. Forest status was determined from satellite images and Swedish National Forest Inventory data using the probabilistic classifier method, which was used to model stream water chemistry with Bayesian model averaging. The results indicate that concentrations of e.g. nitrogen, phosphorus and organic matter are related to factors associated with forest production but that it is not forestry per se that causes the excess losses. Instead, factors simultaneously affecting forest production and stream water chemistry, such as climate, extensive soil pools and nitrogen deposition, are the most likely candidates The relationships with clear-felled and wetland areas are likely to be direct effects.

  6. Toxicity of TiO2 nanoparticles to Escherichia coli: effects of particle size, crystal phase and water chemistry.

    Science.gov (United States)

    Lin, Xiuchun; Li, Jingyi; Ma, Si; Liu, Gesheng; Yang, Kun; Tong, Meiping; Lin, Daohui

    2014-01-01

    Controversial and inconsistent results on the eco-toxicity of TiO2 nanoparticles (NPs) are commonly found in recorded studies and more experimental works are therefore warranted to elucidate the nanotoxicity and its underlying precise mechanisms. Toxicities of five types of TiO2 NPs with different particle sizes (10∼50 nm) and crystal phases were investigated using Escherichia coli as a test organism. The effect of water chemistry on the nanotoxicity was also examined. The antibacterial effects of TiO2 NPs as revealed by dose-effect experiments decreased with increasing particle size and rutile content of the TiO2 NPs. More bacteria could survive at higher solution pH (5.0-10.0) and ionic strength (50-200 mg L(-1) NaCl) as affected by the anatase TiO2 NPs. The TiO2 NPs with anatase crystal structure and smaller particle size produced higher content of intracellular reactive oxygen species and malondialdehyde, in line with their greater antibacterial effect. Transmission electron microscopic observations showed the concentration buildup of the anatase TiO2 NPs especially those with smaller particle sizes on the cell surfaces, leading to membrane damage and internalization. These research results will shed new light on the understanding of ecological effects of TiO2 NPs.

  7. On the Ionisation Fraction in Protoplanetary Disks II: The Effect of Turbulent Mixing on Gas--phase Chemistry

    CERN Document Server

    Ilgner, M; Ilgner, Martin; Richard P. Nelson

    2005-01-01

    We calculate the ionisation fraction in protostellar disk models using two different gas-phase chemical networks, and examine the effect of turbulent mixing by modelling the diffusion of chemical species vertically through the disk. The aim is to determine in which regions of the disk gas can couple to a magnetic field and sustain MHD turbulence. We find that the effect of diffusion depends crucially on the elemental abundance of heavy metals (magnesium) included in the chemical model. In the absence of heavy metals, diffusion has essentially no effect on the ionisation structure of the disks, as the recombination time scale is much shorter than the turbulent diffusion time scale. When metals are included with an elemental abundance above a threshold value, the diffusion can dramatically reduce the size of the magnetically decoupled region, or even remove it altogther. For a complex chemistry the elemental abundance of magnesium required to remove the dead zone is 10(-10) - 10(-8). We also find that diffusion...

  8. Toxicity of TiO2 nanoparticles to Escherichia coli: effects of particle size, crystal phase and water chemistry.

    Directory of Open Access Journals (Sweden)

    Xiuchun Lin

    Full Text Available Controversial and inconsistent results on the eco-toxicity of TiO2 nanoparticles (NPs are commonly found in recorded studies and more experimental works are therefore warranted to elucidate the nanotoxicity and its underlying precise mechanisms. Toxicities of five types of TiO2 NPs with different particle sizes (10∼50 nm and crystal phases were investigated using Escherichia coli as a test organism. The effect of water chemistry on the nanotoxicity was also examined. The antibacterial effects of TiO2 NPs as revealed by dose-effect experiments decreased with increasing particle size and rutile content of the TiO2 NPs. More bacteria could survive at higher solution pH (5.0-10.0 and ionic strength (50-200 mg L(-1 NaCl as affected by the anatase TiO2 NPs. The TiO2 NPs with anatase crystal structure and smaller particle size produced higher content of intracellular reactive oxygen species and malondialdehyde, in line with their greater antibacterial effect. Transmission electron microscopic observations showed the concentration buildup of the anatase TiO2 NPs especially those with smaller particle sizes on the cell surfaces, leading to membrane damage and internalization. These research results will shed new light on the understanding of ecological effects of TiO2 NPs.

  9. Experimental validation of the use of Kramers-Kronig relations to eliminate the phase sheet ambiguity in broadband phase spectroscopy.

    Science.gov (United States)

    Trousil, R L; Waters, K R; Miller, J G

    2001-05-01

    The technique of broadband phase spectroscopy proposed in 1978 by Sachse and Pao [J. Appl. Phys. 49, 4320-4327 (1978)] determines the phase velocity as a function of frequency from the Fourier transforms of a received reference and through-sample signal. Although quite successful, this approach can be influenced by an ambiguity in the phase velocity calculation which stems from the boundedness of the inverse tangent operation used to calculate phase. Several empirical approaches to resolve the phase ambiguity have been reported. An alternative approach that has not previously been considered appeals to the causal nature of the measurements. This article experimentally validates a method which uses the causally consistent Kramers-Kronig relations to eliminate the ambiguity in phase spectroscopy-derived phase velocity calculations. Broadband pulse and narrow-band tone burst measurements were performed on three gelatin-based phantoms containing different concentrations of graphite particles (0%, 10%, and 20% by volume). The phantoms were constructed to have attenuation coefficients which vary approximately linear-with-frequency, a dependence exhibited by many soft tissues. The narrow-band phase velocity measurements do not suffer from a phase ambiguity, and thus they serve as a "gold standard" against which the broadband phase velocity measurements are compared. The experimental results illustrate that using the Kramers-Kronig dispersion relations in conjunction with phase spectroscopy-derived phase velocity measurements is an effective means by which to resolve the phase sheet ambiguity in broadband phase spectroscopy.

  10. Phase relations in the forsterite-diopside-jadeite system.

    Science.gov (United States)

    Butvina, V.; Litvin, Yu.

    2009-04-01

    solidus in this system). Due to this fact forsterite vanishes in subsolidus in the region of compositions rather enriched by jadeite component. The performed experimental investigations testify to complex topological relations of phases in this system at close solidus temperatures what needs further studies. The experimental investigations done earlier and referring to this system (Gasparik & Litvin, 1997) testify to the appearance of a new phase of the composition Na2Mg2Si2O7, which role in the formation of subliquidus and subsolidus assemblages must be more studied. Nevertheless, the obtained preliminary experimental data contain constructive data that make it possible to consider the basic problem of this work and start experimental investigations of liquidus phase relations of the system forsterite-diopside-jadeite. The system forsterite-diopside. The experiments in this section are given at pressure of 7 GPa in the range of temperatures 1600-17000C. The system is pseudobinary due to the appearance of orthopyroxene component that forms an independent phase. According to the preliminary data liquidus assemblages of this system at 7 GPa are Fo + L и DiSS + L, but the type of melting is eutectic. It agrees with the above investigations at pressure of 3 GP (Davis, 1963) where some pseudobinarity of the system forsterite-diopside caused by the appearance of orthopyroxene minal in clinopyroxene solid solution can be also seen. The system forsterite-jadeite-diopside. The experimental data and conclusions obtained for the boundary systems make it possible to start investigating liquidus surface for fusibility diagram of the ternary system forsterite-jadeite-diopside at P 7 GPa. For the experimental study polythermic sections of forsterite-(jadeite50diopside50) and forsterite-(jadeite25diopside75) have been chosen. The obtained data testify to the fact that olivine vanishing and garnet formation are realized in both sections. The problem of further investigations is to search

  11. Preliminary assessment of water chemistry related to groundwater flooding in Wawarsing, New York, 2009-11

    Science.gov (United States)

    Brown, Craig J.; Eckhardt, David A.; Stumm, Frederick; Chu, Anthony

    2012-01-01

    Water-quality samples collected in an area prone to groundwater flooding in Wawarsing, New York, were analyzed and assessed to better understand the hydrologic system and to aid in the assessment of contributing water sources. Above average rainfall over the past decade, and the presence of a pressurized water tunnel that passes about 700 feet beneath Wawarsing, could both contribute to groundwater flooding. Water samples were collected from surface-water bodies, springs, and wells and analyzed for major and trace inorganic constituents, dissolved gases, age tracers, and stable isotopes. Distinct differences in chemistry exist between tunnel water and groundwater in unconsolidated deposits and in bedrock, and among groundwater samples collected from some bedrock wells during high head pressure and low head pressure of the Rondout-West Branch Tunnel. Samples from bedrock wells generally had relatively higher concentrations of sulfate (SO42-), strontium (Sr), barium (Ba), and lower concentrations of calcium (Ca) and bicarbonate (HCO3-), as compared to unconsolidated wells. Differences in stable-isotope ratios among oxygen-18 to oxygen-16 (δ18O), hydrogen-2 to hydrogen-1 (δ2H), sulfur-34 to sulfur-32(δ34S) of SO42-, Sr-87 to Sr-86 (87Sr/86Sr), and C-13 to C-12 (δ13C) of dissolved inorganic carbon (DIC) indicate a potential for distinguishing water in the Delaware-West Branch Tunnel from native groundwater. For example, 87Sr/86Sr ratios were more depleted in groundwater samples from most bedrock wells, as compared to samples from surface-water sources, springs, and wells screened in unconsolidated deposits in the study area. Age-tracer data provided useful information on pathways of the groundwater-flow system, but were limited by inherent problems with dissolved gases in bedrock wells. The sulfur hexafluoride (SF6) and (or) chlorofluorocarbons (CFCs) apparent recharge years of most water samples from wells screened in unconsolidated deposits and springs ranged

  12. Serum chemistry reference values in adult Japanese quail (Coturnix coturnix japonica) including sex-related differences.

    Science.gov (United States)

    Scholtz, N; Halle, I; Flachowsky, G; Sauerwein, H

    2009-06-01

    Serum chemistry reference values may provide useful information about the physical condition of individuals, making them a useful tool in differentiating normal and healthy animals from abnormal or diseased states. For Japanese quail that are used for producing eggs and meat for human consumption and also as laboratory animals, we aimed to extend the available array of reference values and to compare 16-wk-old adult male versus female birds. In the present study, clinical chemistry data (albumin, total protein, glucose, uric acid, cholesterol, bilirubin, cholinesterase, creatinine, triglycerides, alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyltransferase) in blood serum from up to 125 male and 151 female Japanese quail were established. Statistical comparisons were made between male and female birds. Aspartate aminotransferase, alanine aminotransferase, glucose, cholinesterase, and bilirubin values were higher (P sex-based differences were observed for creatinine and uric acid. The reference values provided are relevant in particular for the use of quail as laboratory animals when responses to specific treatments have to be monitored and appraised.

  13. The crystal chemistry of inorganic metal borohydrides and their relation to metal oxides.

    Science.gov (United States)

    Černý, Radovan; Schouwink, Pascal

    2015-12-01

    The crystal structures of inorganic homoleptic metal borohydrides are analysed with respect to their structural prototypes found amongst metal oxides in the inorganic databases such as Pearson's Crystal Data [Villars & Cenzual (2015). Pearson's Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2014/2015, ASM International, Materials Park, Ohio, USA]. The coordination polyhedra around the cations and the borohydride anion are determined, and constitute the basis of the structural systematics underlying metal borohydride chemistry in various frameworks and variants of ionic packing, including complex anions and the packing of neutral molecules in the crystal. Underlying nets are determined by topology analysis using the program TOPOS [Blatov (2006). IUCr CompComm. Newsl. 7, 4-38]. It is found that the Pauling rules for ionic crystals apply to all non-molecular borohydride crystal structures, and that the latter can often be derived by simple deformation of the close-packed anionic lattices c.c.p. and h.c.p., by partially removing anions and filling tetrahedral or octahedral sites. The deviation from an ideal close packing is facilitated in metal borohydrides with respect to the oxide due to geometrical and electronic considerations of the BH4(-) anion (tetrahedral shape, polarizability). This review on crystal chemistry of borohydrides and their similarity to oxides is a contribution which should serve materials engineers as a roadmap to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials.

  14. Interfacial Chemistry and the Design of Solid-Phase Nucleic Acid Hybridization Assays Using Immobilized Quantum Dots as Donors in Fluorescence Resonance Energy Transfer

    OpenAIRE

    Krull, Ulrich J.; W. Russ Algar

    2011-01-01

    The use of quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET) offer several advantages for the development of multiplexed solid-phase QD-FRET nucleic acid hybridization assays. Designs for multiplexing have been demonstrated, but important challenges remain in the optimization of these systems. In this work, we identify several strategies based on the design of interfacial chemistry for improving sensitivity, obtaining lower limits of detection (LOD) and enabling th...

  15. Chemistry for Potters.

    Science.gov (United States)

    Denio, Allen A.

    1980-01-01

    Relates pottery making to chemistry by providing chemical information about clay, its origin, composition, properties, and changes that occur during firing; also describes glaze compositions, examples of redox chemistry, salt glazing, crystalline glazes, and problems in toxicity. (CS)

  16. Review and needs in actinide chemistry in relation with biological purposes

    Energy Technology Data Exchange (ETDEWEB)

    Ansoborlo, E.; Moulin, V.; Bion, L.; Doizi, D.; Moulin, C.; Cote, G.; Madic, C.; Van der Lee, J

    2004-07-01

    In case of accidental release of radionuclides in the environment, actinides could occur and may present an healthy risk for human beings. In order to study their behavior in human organism (metabolism, retention, excretion), it is of prime importance to know solution actinide chemistry, and more particularly thermodynamic constants, which will allow to determine their speciation: speciation governs biological availability and toxicity of elements and is also of great interest for decorporation purposes. In this framework, a CEA working group on speciation has been created in order to share data both on thermodynamic constants and on speciation analytical methods, interesting chemists, environmentalists and biologists. It has been focused, in a first time, on actinides. The purpose of this paper is to present the state of the art on actinide speciation within biological media and to focus on the lack of information in order to orientate future research. (authors)

  17. Acid-base chemistry in the formation of Mackay-type icosahedral clusters: μ3-acidity analysis of Sc-rich phases of the Sc-Ir system.

    Science.gov (United States)

    Guo, Yiming; Stacey, Timothy E; Fredrickson, Daniel C

    2014-05-19

    The crystal structures of intermetallic phases offer a wealth of geometrical features (helices, multishelled clusters, and host-guest motifs) whose formation has yet to be explained or predicted by chemical theory. A recently developed extension of the acid-base concept to metallic systems, the μ3-acidity model, provides an avenue for developing this understanding for intermetallics formed from transition metals. In this Article, we illustrate how this approach can be used to understand one of the most striking geometrical entities to emerge in intermetallic chemistry, the Mackay cluster of icosahedral quasicrystals. We present μ3-acidity analyses, based on DFT-calibrated Hückel calculations, for a series of Sc-Ir intermetallics: ScIr (CsCl-type), Sc2Ir (Ti2Ni-type), Sc11Ir4, and the Mackay cluster containing phases Sc57Ir13 and Sc44Ir7. We begin by illustrating that a μ3-acidity model correctly predicts that each of these phases is stable relative to disproportionation into their neighboring compounds when a common set of Hückel parameters and d-orbital occupancies is used. Next, we explain these results by developing a relationship between the distance distribution of homoatomic contacts within an atom's coordination sphere and the μ3-neutralization it experiences. For a given average homoatomic distance, the role of heteroatomic contacts is higher when the distribution of homoatomic contacts is narrower. This effect is key to the strength of the acid-base neutralization of the Sc-rich phases, where the Sc atoms find a scarcity of Ir atoms from which to obtain neutralization. Under these circumstances, Sc-Ir contacts should be maximized, whereas the number and distance variations of the Sc-Sc contacts should be minimized. These expectations are borne out by the observed crystal structures. In particular, the Mackay clusters of Sc57Ir13 and Sc44Ir7, in which a central Ir atom is icosahedrally coordinated by a pentagonal dodecahedral array of face-sharing Sc

  18. Introducing Organic Chemistry Students to Natural Product Isolation Using Steam Distillation and Liquid Phase Extraction of Thymol, Camphor, and Citral, Monoterpenes Sharing a Unified Biosynthetic Precursor

    Science.gov (United States)

    McLain, Katherine A.; Miller, Kenneth A.; Collins, William R.

    2015-01-01

    Plants have provided and continue to provide the inspiration and foundation for modern medicines. Natural product isolation is a key component of the process of drug discovery from plants. The purpose of this experiment is to introduce first semester undergraduate organic chemistry students, who have relatively few lab techniques at their…

  19. Phase behavior, formation, and rheology of cubic phase and related gel emulsion in Tween 80/water/oil systems.

    Science.gov (United States)

    Alam, Mohammad Mydul; Ushiyama, Kousuke; Aramaki, Kenji

    2009-01-01

    We investigated the phase behavior, formation, and rheology of the cubic phase (I(1)) and related O/I(1) gel emulsion in water/Tween 80/oil systems using squalane, liquid paraffin (LP), and decane as oil components. In the phase behavior study, the phase sequences were similar for squalane and LP systems, while a lamellar liquid crystal (L(alpha)) was observed for decane system. In all the systems the addition of oil to W(m) or H(1) phase induced the I(1) phase, which can solubilize some amounts of oil followed by the appearance of I(1)+O phase. The formation of the O/I(1) gel emulsion has been studied at a fixed w/s (50/50) and we found that 30 wt% decane, 70 wt% squalane, and 60 wt% LP can form the gel emulsion. The water/Tween 80/squalane system has been taken as a model system to study viscoelastic properties of the I(1) phase and O/I(1) gel emulsion. The I(1) phase shows a typical hard gel cubic structure under the frequency and the values of the complex viscosity, /eta*/ and the elastic modulus, G ' increase with the addition of squalane, which could be due to the neighboring micellar interaction. On the other hand, the decreasing values of the viscoelastic parameters in the O/I(1) gel emulsion simply relate to the volume fraction of the I(1) phase in the system.

  20. Predicting and Mitigating Corrosion Related Damage in Geothermal Facilities, Phase-I

    Energy Technology Data Exchange (ETDEWEB)

    M. Shirmohamadi; S. Bratt; J. Ridgely

    2000-08-25

    Corrosion related damage (CRD) is probably the most important and costly damage mechanism for components operating in geothermal fields. This problem is further complicated as steam chemistry in such fields changes continuously with season, time, and load. Unfortunately, such changes are not predictable. The problem is further complicated in the area where early condensate (first moisture) forms. The chemistry of these first droplets is significantly different from that of built steam and this, again, cannot be predicted with reasonable accuracy. Therefore, a formidable challenge facing the geothermal field operators remains in knowing the chemistry of the condensate and, more importantly, how it affects specific field equipment such as rotor, piping, valves, etc. This project showed that testing in such an environment is feasible and concluded that continuous monitoring of steam conditions is needed to detect and prevent conditions leading to CRD of components. This project also developed tools and techniques for continuous monitoring of corrosion potential and detection of pitting events.

  1. Investigation of Attitudes of Students in The Programs of Class Teaching, and Science Teaching Towards Chemistry Lesson, and The Relation Between Their Multiple Intelligence Fields and Their Success in Chemistry and Language Lessons

    Directory of Open Access Journals (Sweden)

    Hasan ÖZYILDIRIM

    2005-06-01

    Full Text Available The basis of Multiple Intelligence Theory contains development and learning during life time. According to this theory all human have different intelligences which are verbal-linguistic, logical-mathematical, visual-spatial, bodily-kinesthetic, musical, interpersonal, intrapersonal and naturalist intelligences in varying amounts.In this study, the attitude toward Chemistry Lesson, the Multiple Intelligence Fields of the 1st class students in the program of Class Teaching and Science Teaching at Trakya University, Faculty of Education, and the relation between their attitudes, their multiple intelligence fields and their success in Chemistry and Turkish Language Lessons were investigated.In order to find out the intelligence fields of students the inventory of multiple intelligence taken from Saban (2002 was used. And the chemistry lesson attitude scale developed by Morgil etc. (2000 was utilized to establish their attitudes toward chemistry lesson.The data obtained were evaluated in SPSS 11.0 package program, and variation analysis, t-test and correlation analyses for all data were applied.As a result of research it was found that students were positive in their attitude toward chemistry lesson and their intelligence fields were expanded through developed medium-level as homogenous to all intelligence fields.The significant differences were found out between students’ intelligence fields regarding their main branches., and a relationship existed between students’ attitude toward chemistry lesson and their logical/mathematical and verbal/linguistic of intelligence fields, and between students’ success in chemistry lesson and logical/ mathematical field of intelligence.

  2. Design considerations and computer modeling related to the development of molecular scaffolds and peptide mimetics for combinatorial chemistry.

    Science.gov (United States)

    Hruby, V J; Shenderovich, M; Lam, K S; Lebl, M

    1996-10-01

    A critical issue in drug discovery utilizing combinatorial chemistry as part of the discovery process is the choice of scaffolds to be used for a proper presentation, in a three-dimensional space, of the critical elements of structure necessary for molecular recognition (binding) and information transfer (agonist/ antagonist). In the case of polypeptide ligands, considerations related to the properties of various backbone structures (alpha-helix, beta-sheets, etc.; phi, psi space) and those related to three-dimensional presentation of side-chain moieties (topography; chi (chi) space) must be addressed, although they often present quite different elements in the molecular recognition puzzle. We have addressed aspects of this problem by examining the three-dimensional structures of chemically different scaffolds at various distances from the scaffold to evaluate their putative diversity. We find that chemically diverse scaffolds can readily become topographically similar. We suggest a topographical approach involving design in chi space to deal with these problems.

  3. Ternary Phase Diagrams that Relate to the Plutonium Immobilization Ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Ebbinghaus, B b; Krikorian, O H; Vance, E R; Stewart, M W

    2001-01-01

    The plutonium immobilization ceramic consists primarily of a pyrochlore titanate phase of the approximate composition Ca{sub 0.97}Hf{sub 0.17}Pu{sub 0.22}U{sub 0.39}Gd{sub 0.24} Ti{sub 2}O{sub 7}. In this study, a series of ternary phase diagrams was constructed to evaluate the relationship of various titanate phases (e.g., brannerite, zirconolite-2M, zirconolite-4M, and perovskite) to pyrochlore titanates, usually in the presence of excess TiO{sub 2} (rutile), and at temperatures in the vicinity of 1350 C. To facilitate the studies, U, Th, and Ce were used as surrogates for Pu in a number of the phase diagrams in addition to the use of Pu itself. The effects of impurity oxides, Al{sub 2}O{sub 3} and MgO, were also studied on pyrochlore (Gd{sub 2}Ti{sub 2}O{sub 7}) and zirconolite (CaHfTi{sub 2}O{sub 7}) mixtures. Either electron microprobe (at Lawrence Livermore National Laboratory) or quantitative SEM-EDS (at Australian Nuclear Science and Technology Organization) were used to evaluate the compositions of the phases.

  4. The control of stoichiometry in Epitaxial semiconductor structures. Interfacial Chemistry: Property relations. A workshop review

    Science.gov (United States)

    Bachmann, Klaus J.

    1995-01-01

    A workshop on the control of stoichiometry in epitaxial semiconductor structures was held on August 21-26, 1995 in the hotel Stutenhaus at Vesser in Germany. The secluded location of the workshop in the forest of Thuringia and its informal style stimulated extensive private discussions among the participants and promoted new contacts between young scientists from Eastern and Western Europe and the USA. Topics addressed by the presentations were interactions of precursors to heteroepitaxy and doping with the substrate surface, the control of interfacial properties under the conditions of heteroepitaxy for selected materials systems, methods of characterization of interfaces and native point defects in semiconductor heterostructures and an in depth evaluation of the present status of the control and characterization of the point defect chemistry for one specific semiconductor (ZnGeP2), including studies of both heterostructures and bulk single crystals. The selected examples of presentations and comments given here represent individual choices - made by the author to highlight major points of the discussions.

  5. A causal analysis relating previous achievement, attitudes, discourse, and intervention to achievement in biology and chemistry

    Science.gov (United States)

    Gooding, C. Thomas; Swift, J. Nathan; Schell, Robert E.; Swift, Patricia R.; McCroskery, James H.

    This study described the relationship of 38 variates to achievement in high school biology and chemistry classes. Forty-four teachers prepared audio tape recordings of discussions throughout a nine-month period. Equal-sized groups received treatment consisting of wait time feedback and/or supportive intervention, a form of peer coaching. Other variables were initial measures, which included the variates of class size and previous science grade, pre- and posttest scores on student attitudes and perceptions, and prediscourse and discourse analyses, which included the variates of wait times, actions, and response durations. While previous research has shown that wait time feedback and supportive intervention are effective means of changing teacher behavior, the results of the present study revealed that previous student achievement and the attitudes of students accounted for 70% of the variation in the final examination scores (New York State Regents) on the basis of only the first three weeks of data collection on the variables assessed. Generally, little emphasis on higher-level thinking, wait time, or problem solving was found at the beginning of the school year, and only minimal changes resulted from the application of the treatment variables. Pressures for content coverage and preparation for externally imposed statewide examinations that emphasize memory-level learning augured against the changes that the independent variables were designed to produce.

  6. Experimentos didáticos em química analítica envolvendo separação de fases e pré-concentração Didactic experiments in analytical chemistry involving phase separations and preconcentration

    Directory of Open Access Journals (Sweden)

    Clésia C. Nascentes

    2002-05-01

    Full Text Available The aim of this work was to propose two different didactic experiments, which can be used in practical classes of analytical chemistry courses. More flexible experiments related to the theme, giving some options to the instructor are proposed. In this way, the Experiment 1 was divided in two parts. In the first one, the visualization of two distinct phases separation is emphasized: the rich and the poor phases in surfactant. In the second part, the metal pre-concentration (Co as example is emphasized. The Experiment 2 has three different parts. In the first one, the complex formation is pointed out, in the second one, the pH influence is shown and in the last one, the influence of the complexation time is demonstrated.

  7. Phase relation between global temperature and atmospheric carbon dioxide

    CERN Document Server

    Stallinga, Peter

    2013-01-01

    The primary ingredient of Anthropogenic Global Warming hypothesis is the assumption that atmospheric carbon dioxide variations are the cause for temperature variations. In this paper we discuss this assumption and analyze it on basis of bi-centenary measurements and using a relaxation model which causes phase shifts and delays.

  8. Relation between surface topography and sea-salt snow chemistry from Princess Elizabeth Land, East Antarctica

    Directory of Open Access Journals (Sweden)

    K. Mahalinganathan

    2012-04-01

    Full Text Available Previous studies on Antarctic snow have established an unambiguous correlation between variability of sea-salt records and site specific features like elevation and proximity to the sea. On the other hand, variations of Cl/Na+ ratios in snow have been attributed to the reaction mechanisms involving atmospheric acids. In the present study, the annual records of Na+, Cl and SO42− were investigated using snow cores along a 180 km coast to inland transect in Princess Elizabeth Land, East Antarctica. Exceptionally high Na+ concentrations and large variations in Cl/Na+ ratios were observed up to 50 km (∼1100 m elevation of the transect. The steepest slope in the entire transect (49.3 m km−1 was between 20 and 30 km and the sea-salt records in snow from this area revealed extensive modifications, with Cl/Na+ ratios as low as 0.2. Statistical analysis showed a strong association between the slope and variations in Cl/Na+ ratios along the transect (r = −0.676, 99% confidence level. While distance from the coast accounted for some variability, the altitude by itself has no significant control over the sea-salt ion variability. However, the steep slopes influence the deposition of sea-salt aerosols in snow. The wind redistribution of snow due to the steep slopes on the coastal escarpment increases the concentration of Na+, resulting in a low Cl/Na+ ratios. We propose that the slope variations in the coastal regions of Antarctica could significantly influence the sea-salt chemistry of snow.

  9. Preanalytical quality improvement. In pursuit of harmony, on behalf of European Federation for Clinical Chemistry and Laboratory Medicine (EFLM) Working group for Preanalytical Phase (WG-PRE)

    DEFF Research Database (Denmark)

    Lippi, G.; Banfi, G.; Church, S.;

    2015-01-01

    , is aimed to provide further contributions for pursuing quality and harmony in the preanalytical phase, and is a synopsis of lectures of the third European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)-Becton Dickinson (BD) European Conference on Preanalytical Phase meeting entitled...... requirements for blood sampling, influence of physical activity and medical contrast media on in vitro diagnostic testing, recent evidence about the possible lack of necessity of the order of draw, the best practice for monitoring conditions of time and temperature during sample transportation, along...... with description of problems emerging from inappropriate sample centrifugation. In the final part, the article includes recent updates about preanalytical quality indicators, the feasibility of an External Quality Assessment Scheme (EQAS) for the preanalytical phase, the results of the 2nd EFLM WG-PRE survey...

  10. Relating polarization phase difference of SAR signals to scene properties

    Science.gov (United States)

    Ulaby, Fawwaz T.; Dobson, Myron C.; Mcdonald, Kyle C.; Senior, Thomas B. A.; Held, Daniel

    1987-01-01

    This paper examines the statistical behavior of the phase difference Delta-phi between the HH-polarized and VV-polarized backscattered signals recorded by an L-band SAR over an agricultural test site in Illinois. Polarization-phase difference distributions were generated for about 200 agricultural fields for which ground information had been acquired in conjunction with the SAR mission. For the overwhelming majority of cases, the Delta-phi distribution is symmetric and has a single major lobe centered at the mean value of the distribution Delta-phi. Whereas the mean Delta-phi was found to be close to zero degrees for bare soil, cut vegetation, alfalfa, soybeans, and clover, a different pattern was observed for the corn fields; the mean Delta-phi increased with increasing incidence angle Theta = 35 deg. The explanation proposed for this variation is that the corn canopy, most of whose mass is contained in its vertical stalks, acts like a uniaxial crystal characterized by different velocities of propagation for waves with horizontal and vertical polarization. Thus, it is hypothesized that the observed backscatter is contributed by a combination of propagation delay, forward scatter by the soil surface, and specular bistatic reflection by the stalks. Model calculations based on this assumption were found to be in general agreement with the phase observations.

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

    Science.gov (United States)

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

    1975-01-01

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

  12. The Modification of high-$p_{T}$ hadro-chemistry in Au+Au collisions relative to p+p

    CERN Document Server

    Timmins, Anthony R

    2009-01-01

    We present high transverse momentum, $p_{T}$, pion ($\\pi$), proton ($p$), kaon ($K$), and rho ($\\rho$) spectra measured with the STAR experiment from p+p and Au+Au collisions with \\sNN{200}. We find the $K/\\pi$ ratio to be enhanced in Au+Au \\sNN{200} collisions relative to p+p \\sNN{200} collisions at $p_{T} > 5$ GeV/c. The enhancement persists until $p_{T} \\sim 12$ GeV/c for central Au+Au 200 GeV collisions. We also show the nuclear modification factor, $R_{AA}$, measured at the same center of mass energy, and find $R_{AA}(K)$ and $R_{AA}(p)$ to be higher than $R_{AA}(\\pi)$ at $p_T > 5$ GeV/c. Implications for medium induced modifications of jet chemistry is discussed.

  13. Preanalytical quality improvement. In pursuit of harmony, on behalf of European Federation for Clinical Chemistry and Laboratory Medicine (EFLM) Working group for Preanalytical Phase (WG-PRE).

    Science.gov (United States)

    Lippi, Giuseppe; Banfi, Giuseppe; Church, Stephen; Cornes, Michael; De Carli, Gabriella; Grankvist, Kjell; Kristensen, Gunn B; Ibarz, Mercedes; Panteghini, Mauro; Plebani, Mario; Nybo, Mads; Smellie, Stuart; Zaninotto, Martina; Simundic, Ana-Maria

    2015-02-01

    Laboratory diagnostics develop through different phases that span from test ordering (pre-preanalytical phase), collection of diagnostic specimens (preanalytical phase), sample analysis (analytical phase), results reporting (postanalytical phase) and interpretation (post-postanalytical phase). Although laboratory medicine seems less vulnerable than other clinical and diagnostic areas, the chance of errors is not negligible and may adversely impact on quality of testing and patient safety. This article, which continues a biennial tradition of collective papers on preanalytical quality improvement, is aimed to provide further contributions for pursuing quality and harmony in the preanalytical phase, and is a synopsis of lectures of the third European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)-Becton Dickinson (BD) European Conference on Preanalytical Phase meeting entitled 'Preanalytical quality improvement. In pursuit of harmony' (Porto, 20-21 March 2015). The leading topics that will be discussed include unnecessary laboratory testing, management of test request, implementation of the European Union (EU) Directive on needlestick injury prevention, harmonization of fasting requirements for blood sampling, influence of physical activity and medical contrast media on in vitro diagnostic testing, recent evidence about the possible lack of necessity of the order of draw, the best practice for monitoring conditions of time and temperature during sample transportation, along with description of problems emerging from inappropriate sample centrifugation. In the final part, the article includes recent updates about preanalytical quality indicators, the feasibility of an External Quality Assessment Scheme (EQAS) for the preanalytical phase, the results of the 2nd EFLM WG-PRE survey, as well as specific notions about the evidence-based quality management of the preanalytical phase.

  14. Novel chemistry of alpha-tosyloxy ketones: applications to the solution- and solid-phase synthesis of privileged heterocycle and enediyne libraries

    DEFF Research Database (Denmark)

    Nicolaou, K C; Montagnon, T; Ulven, T;

    2002-01-01

    -tosyloxy ketones are engaged by "hard" versus "soft" nucleophiles. The accessibility and site-selectivity of the chemistry demonstrated herein offer the promise of an expanded use for this moiety in solid-phase library construction, in particular, and in the field of organic synthesis, in general......., and oxidation sequence, and ketones by direct exposure to arylsulfonic acids in the presence of diacetoxy iodobenzene. Reaction of these substrates with O-, S-, or N-centered nucleophiles leads to incorporation of the nucleophile with concomitant expulsion of the sulfonate, while exposure to bis-functional...

  15. Phase relations of triadic scale interactions in turbulent flows

    Science.gov (United States)

    Duvvuri, Subrahmanyam; McKeon, Beverley

    2014-11-01

    The quadratic nature of non-linearity in the Navier-Stokes (NS) equations dictates the coupling between scales in a turbulent flow to be of triadic form. An understanding of the triadic coupling affords good insights into the dynamics of turbulence, as demonstrated by Sharma & McKeon (J. Fluid Mech., 2013) through analysis of the NS resolvent operator; a set of three triadically consistent spatio-temporal modes was shown to produce complex structures such as modulating packets of hairpin vortices observed in wall-bounded turbulent flows. Here we interpret Skewness (Sk) of velocity fluctuations and the Amplitude Modulation coefficient (Ram), proposed by Mathis, Hutchins & Marusic (J. Fluid Mech., 2009), to be a measure of the large- and small-scale phase relationship. Through a simple decomposition of scales, both Sk and Ram are shown to be amplitude weighted (and normalized) measures of phase between scales that have direct triadic coupling. An analytical relationship is established between the two quantities and the result is demonstrated using experimental data from canonical and dynamically forced turbulent boundary layers presented in Duvvuri and McKeon (AIAA 2014-2883). The support of AFOSR (Grant No. FA 9550-12-1-0469) and Resnick Institute Graduate Research Fellowship (S.D.) is gratefully acknowledged.

  16. Relative hydrophobicity between the phases and partition of cytochrome-c in glycine ionic liquids aqueous two-phase systems.

    Science.gov (United States)

    Wu, Changzeng; Wang, Jianji; Li, Zhiyong; Jing, Jun; Wang, Huiyong

    2013-08-30

    In this work, glycine ionic liquids tetramethylammonium glycine ([N1111][Gly]), tetraethylammonium glycine ([N2222][Gly]), tetra-n-butylammonium glycine ([N4444][Gly]), tetra-n-butylphosphonium glycine ([P4444][Gly]) and tetra-n-pentylammonium glycine ([N5555][Gly]) were synthesized and used to prepare aqueous two-phase systems (ATPSs) in the presence of K2HPO4. Binodal curves of such ATPSs and partition coefficients of a series of dinitrophenylated (DNP) amino acids in these ATPSs were determined at 298.15K to understand the effect of cationic structure of the ionic liquids on the phase-forming ability of glycine ionic liquids, relative hydrophobicity between the phases in the ionic liquids ATPSs, and polarity of the ionic liquids-rich phases. With the attempt to correlate the relative hydrophobicity of the phases in the ATPSs with their extraction capability for proteins, partition coefficients of cytochrome-c in the ATPSs were also determined. It was shown that partition coefficients of cytochrome-c were in the range from 2.83 to 20.7 under the studied pH conditions. Then, hydrophobic interactions between cytochrome-c and the ionic liquid are suggested to be the main driving force for the preferential partition of cytochrome-c in the glycine ionic liquid-rich phases of the ATPSs. Result derived from polarity of the ionic liquids-rich phases supports this mechanism.

  17. Student-generated questions during chemistry lectures: Patterns, self-appraisals, and relations with motivational beliefs and achievement

    Science.gov (United States)

    Bergey, Bradley W.

    Self-generated questions are a central mechanism for learning, yet students' questions are often infrequent during classroom instruction. As a result, little is known about the nature of student questioning during typical instructional contexts such as listening to a lecture, including the extent and nature of student-generated questions, how students evaluate their questions, and the relations among questions, motivations, and achievement. This study examined the questions undergraduate students (N = 103) generated during 8 lectures in an introductory chemistry course. Students recorded and appraised their question in daily question logs and reported lecture-specific self-efficacy beliefs. Self-efficacy, personal interest, goal orientations, and other motivational self-beliefs were measured before and after the unit. Primary analyses included testing path models, multiple regressions, and latent class analyses. Overall, results indicated that several characteristics of student questioning during lectures were significantly related to various motivations and achievement. Higher end-of-class self-efficacy was associated with fewer procedural questions and more questions that reflected smaller knowledge deficits. Lower exam scores were associated with questions reflecting broader knowledge deficits and students' appraisals that their questions had less value for others than for themselves. Individual goal orientations collectively and positively predicted question appraisals. The questions students generated and their relations with motivational variables and achievement are discussed in light of the learning task and academic context.

  18. Privileged scaffolds or promiscuous binders: a comparative study on rhodanines and related heterocycles in medicinal chemistry.

    Science.gov (United States)

    Mendgen, Thomas; Steuer, Christian; Klein, Christian D

    2012-01-26

    Rhodanines and related five-membered heterocycles with multiple heteroatoms have recently gained a reputation of being unselective compounds that appear as "frequent hitters" in screening campaigns and therefore have little value in drug discovery. However, this judgment appears to be based mostly on anecdotal evidence. Having identified various rhodanines and related compounds in screening campaigns, we decided to perform a systematic study on their promiscuity. An amount of 163 rhodanines, hydantoins, thiohydantoins, and thiazolidinediones were synthesized and tested against several targets. The compounds were also characterized with respect to aggregation and electrophilic reactivity, and the binding modes of rhodanines and related compounds in published X-ray cocrystal structures were analyzed. The results indicate that the exocyclic, double bonded sulfur atom in rhodanines and thiohydantoins, in addition to other structural features, offers a particularly high density of interaction sites for polar interactions and hydrogen bonds. This causes a promiscuous behavior at concentrations in the "screening range" but should not be regarded as a general knockout criterion that excludes such screening hits from further development. It is suggested that special criteria for target affinity and selectivity are applied to these classes of compounds and that their exceptional and potentially valuable biomolecular binding properties are consequently exploited in a useful way.

  19. Controlling Nonspecific Protein Adsorption in a Plug-Based Microfluidic System by Controlling Interfacial Chemistry Using Fluorous-Phase Surfactants

    OpenAIRE

    Roach, L. Spencer; Song, Helen; Ismagilov, Rustem F.

    2005-01-01

    Control of surface chemistry and protein adsorption is important for using microfluidic devices for biochemical analysis and high-throughput screening assays. This paper describes the control of protein adsorption at the liquid-liquid interface in a plug-based microfluidic system. The microfluidic system uses multiphase flows of immiscible fluorous and aqueous fluids to form plugs, which are aqueous droplets that are completely surrounded by fluorocarbon oil and do not come into direct contac...

  20. Disentangling the Effects of Attentional and Amplitude Asymmetries on Relative Phase Dynamics

    Science.gov (United States)

    de Poel, Harjo J.; Peper, C. E.; Beek, Peter J.

    2009-01-01

    Attentional asymmetry in rhythmic interlimb coordination induces an asymmetry in relative phase dynamics, allegedly reflecting an asymmetry in coupling strength. However, relative phase asymmetries may also be engendered by an attention-induced difference between the amplitudes (and hence the preferred frequencies) of the limb movements. The…

  1. Chemical insights, explicit chemistry, and yields of secondary organic aerosol from OH radical oxidation of methylglyoxal and glyoxal in the aqueous phase

    Directory of Open Access Journals (Sweden)

    Y. B. Lim

    2013-09-01

    Full Text Available Atmospherically abundant, volatile water-soluble organic compounds formed through gas-phase chemistry (e.g., glyoxal (C2, methylglyoxal (C3, and acetic acid have great potential to form secondary organic aerosol (SOA via aqueous chemistry in clouds, fogs, and wet aerosols. This paper (1 provides chemical insights into aqueous-phase OH-radical-initiated reactions leading to SOA formation from methylglyoxal and (2 uses this and a previously published glyoxal mechanism (Lim et al., 2010 to provide SOA yields for use in chemical transport models. Detailed reaction mechanisms including peroxy radical chemistry and a full kinetic model for aqueous photochemistry of acetic acid and methylglyoxal are developed and validated by comparing simulations with the experimental results from previous studies (Tan et al., 2010, 2012. This new methylglyoxal model is then combined with the previous glyoxal model (Lim et al., 2010, and is used to simulate the profiles of products and to estimate SOA yields. At cloud-relevant concentrations (~ 10−6 − ~ 10−3 M; Munger et al., 1995 of glyoxal and methylglyoxal, the major photooxidation products are oxalic acid and pyruvic acid, and simulated SOA yields (by mass are ~ 120% for glyoxal and ~ 80% for methylglyoxal. During droplet evaporation oligomerization of unreacted methylglyoxal/glyoxal that did not undergo aqueous photooxidation could enhance yields. In wet aerosols, where total dissolved organics are present at much higher concentrations (~ 10 M, the major oxidation products are oligomers formed via organic radical–radical reactions, and simulated SOA yields (by mass are ~ 90% for both glyoxal and methylglyoxal. Non-radical reactions (e.g., with ammonium could enhance yields.

  2. Chemical insights, explicit chemistry, and yields of secondary organic aerosol from OH radical oxidation of methylglyoxal and glyoxal in the aqueous phase

    Science.gov (United States)

    Lim, Y. B.; Tan, Y.; Turpin, B. J.

    2013-09-01

    Atmospherically abundant, volatile water-soluble organic compounds formed through gas-phase chemistry (e.g., glyoxal (C2), methylglyoxal (C3), and acetic acid) have great potential to form secondary organic aerosol (SOA) via aqueous chemistry in clouds, fogs, and wet aerosols. This paper (1) provides chemical insights into aqueous-phase OH-radical-initiated reactions leading to SOA formation from methylglyoxal and (2) uses this and a previously published glyoxal mechanism (Lim et al., 2010) to provide SOA yields for use in chemical transport models. Detailed reaction mechanisms including peroxy radical chemistry and a full kinetic model for aqueous photochemistry of acetic acid and methylglyoxal are developed and validated by comparing simulations with the experimental results from previous studies (Tan et al., 2010, 2012). This new methylglyoxal model is then combined with the previous glyoxal model (Lim et al., 2010), and is used to simulate the profiles of products and to estimate SOA yields. At cloud-relevant concentrations (~ 10-6 - ~ 10-3 M; Munger et al., 1995) of glyoxal and methylglyoxal, the major photooxidation products are oxalic acid and pyruvic acid, and simulated SOA yields (by mass) are ~ 120% for glyoxal and ~ 80% for methylglyoxal. During droplet evaporation oligomerization of unreacted methylglyoxal/glyoxal that did not undergo aqueous photooxidation could enhance yields. In wet aerosols, where total dissolved organics are present at much higher concentrations (~ 10 M), the major oxidation products are oligomers formed via organic radical-radical reactions, and simulated SOA yields (by mass) are ~ 90% for both glyoxal and methylglyoxal. Non-radical reactions (e.g., with ammonium) could enhance yields.

  3. Interfacial chemistry and the design of solid-phase nucleic acid hybridization assays using immobilized quantum dots as donors in fluorescence resonance energy transfer.

    Science.gov (United States)

    Algar, W Russ; Krull, Ulrich J

    2011-01-01

    The use of quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET) offer several advantages for the development of multiplexed solid-phase QD-FRET nucleic acid hybridization assays. Designs for multiplexing have been demonstrated, but important challenges remain in the optimization of these systems. In this work, we identify several strategies based on the design of interfacial chemistry for improving sensitivity, obtaining lower limits of detection (LOD) and enabling the regeneration and reuse of solid-phase QD-FRET hybridization assays. FRET-sensitized emission from acceptor dyes associated with hybridization events at immobilized QD donors provides the analytical signal in these assays. The minimization of active sensing area reduces background from QD donor PL and allows the resolution of smaller amounts of acceptor emission, thus lowering the LOD. The association of multiple acceptor dyes with each hybridization event can enhance FRET efficiency, thereby improving sensitivity. Many previous studies have used interfacial protein layers to generate selectivity; however, transient destabilization of these layers is shown to prevent efficient regeneration. To this end, we report a protein-free interfacial chemistry and demonstrate the specific detection of as little as 2 pmol of target, as well as an improved capacity for regeneration.

  4. Tree foliar chemistry in an African savanna and its relation to life history strategies and environmental filters.

    Directory of Open Access Journals (Sweden)

    Matthew S Colgan

    Full Text Available Understanding the relative importance of environment and life history strategies in determining leaf chemical traits remains a key objective of plant ecology. We assessed 20 foliar chemical properties among 12 African savanna woody plant species and their relation to environmental variables (hillslope position, precipitation, geology and two functional traits (thorn type and seed dispersal mechanism. We found that combinations of six leaf chemical traits (lignin, hemi-cellulose, zinc, boron, magnesium, and manganese predicted the species with 91% accuracy. Hillslope position, precipitation, and geology accounted for only 12% of the total variance in these six chemical traits. However, thorn type and seed dispersal mechanism accounted for 46% of variance in these chemical traits. The physically defended species had the highest concentrations of hemi-cellulose and boron. Species without physical defense had the highest lignin content if dispersed by vertebrates, but threefold lower lignin content if dispersed by wind. One of the most abundant woody species in southern Africa, Colophospermum mopane, was found to have the highest foliar concentrations of zinc, phosphorus, and δ(13C, suggesting that zinc chelation may be used by this species to bind metallic toxins and increase uptake of soil phosphorus. Across all studied species, taxonomy and physical traits accounted for the majority of variability in leaf chemistry.

  5. Tree foliar chemistry in an African savanna and its relation to life history strategies and environmental filters.

    Science.gov (United States)

    Colgan, Matthew S; Martin, Roberta E; Baldeck, Claire A; Asner, Gregory P

    2015-01-01

    Understanding the relative importance of environment and life history strategies in determining leaf chemical traits remains a key objective of plant ecology. We assessed 20 foliar chemical properties among 12 African savanna woody plant species and their relation to environmental variables (hillslope position, precipitation, geology) and two functional traits (thorn type and seed dispersal mechanism). We found that combinations of six leaf chemical traits (lignin, hemi-cellulose, zinc, boron, magnesium, and manganese) predicted the species with 91% accuracy. Hillslope position, precipitation, and geology accounted for only 12% of the total variance in these six chemical traits. However, thorn type and seed dispersal mechanism accounted for 46% of variance in these chemical traits. The physically defended species had the highest concentrations of hemi-cellulose and boron. Species without physical defense had the highest lignin content if dispersed by vertebrates, but threefold lower lignin content if dispersed by wind. One of the most abundant woody species in southern Africa, Colophospermum mopane, was found to have the highest foliar concentrations of zinc, phosphorus, and δ(13)C, suggesting that zinc chelation may be used by this species to bind metallic toxins and increase uptake of soil phosphorus. Across all studied species, taxonomy and physical traits accounted for the majority of variability in leaf chemistry.

  6. How subtle is the "terroir" effect? Chemistry-related signatures of two "climats de Bourgogne".

    Directory of Open Access Journals (Sweden)

    Chloé Roullier-Gall

    Full Text Available The chemical composition of grape berries is influenced by various environmental conditions often considered to be representative of a "terroir". If grapes from a given terroir are assumed to reflect this origin in their chemical compositions, the corresponding wine should also reflect it. The aim of this work was therefore to reveal the "terroir" expression within the chemodiversity of grapes and related wines, using ultrahigh-resolution mass spectrometry. Grapes and corresponding wines, from two distinct - though very proximate - terroirs of Burgundy were analyzed over three vintages (2010, 2011 and 2012. Ultrahigh-resolution mass spectrometry and ultra-high performance liquid chromatography were used as untargeted and targeted approaches to discriminate complex chemical fingerprints for vintages, classes (wines, skins or musts, and terroirs. Statistical analyses revealed that even if vintages have the most significant impact on fingerprints, the most significant terroir differences are seen in the grapes of a given vintage.

  7. The chemistry of nicotinamide adenine dinucleotide (NAD) analogues containing C-nucleosides related to nicotinamide riboside.

    Science.gov (United States)

    Pankiewicz, Krzysztof W; Watanabe, Kyoichi A; Lesiak-Watanabe, Krystyna; Goldstein, Barry M; Jayaram, Hiremagalur N

    2002-04-01

    Oncolytic C-nucleosides, tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide) and benzamide riboside (3-beta-D-ribofuranosylbenzamide) are converted in cell into active metabolites thiazole-4-carboxamide- and benzamide adenine dinucleotide, TAD and BAD, respectively. TAD and BAD as NAD analogues were found to bind at the nicotinamide adenine dinucleotide (cofactor NAD) site of inosine monophosphate dehydrogenase (IMPDH), an important target in cancer treatment. The synthesis and evaluation of anticancer activity of a number of C-nucleosides related to tiazofurin and nicotinamide riboside then followed and are reviewed herein. Interestingly, pyridine C-nucleosides (such as C-nicotinamide riboside) are not metabolized into the corresponding NAD analogues in cell. Their conversion by chemical methods is described. As dinucleotides these compounds show inhibition of IMPDH in low micromolar level. Also, the synthesis of BAD in metabolically stable bis(phosphonate) form is discussed indicating the usefulness of such preformed inhibitors in drug development. Among tiazofurin analogues, Franchetti and Grifantini found, that the replacement of the sulfur by oxygen (as in oxazafurin) but not the removal of nitrogen (tiophenfurin) of the thiazole ring resulted in inactive compounds. The anti cancer activity of their synthetic dinucleotide analogues indicate that inactive compounds are not only poorly metabolized in cell but also are weak inhibitors of IMPDH as dinucleotides.

  8. Food selection in relation to nutritional chemistry of Cao Vit gibbons in Jingxi, China.

    Science.gov (United States)

    Ma, Changyong; Liao, Jiancun; Fan, Pengfei

    2017-01-01

    The Cao Vit gibbon (Nomascus nasutus) has only one population with about 110 individuals living in a degraded karst forest along the China-Vietnam border. Investigation of food choice in relation to chemical nutrition will offer important insights into its conservation. We studied the food choice of two groups of Cao Vit gibbons using instantaneous scan sampling in Bangliang National Nature Reserve, Guangxi, China, over 4 years, and analyzed the chemical components (total nitrogen, TN; water-soluble sugar, WSS; crude fat, CF; neutral detergent fiber, NDF; acid detergent fiber, ADF; acid detergent lignin, ADL; condensed tannin, CT; and ash) of 48 food plant parts and 22 non-food plant parts. Fruits and figs that are rich in sugar are important food resources for gibbons. For other food types, flowers are a good source of total nitrogen and carbohydrates, and leaves and buds provide sources of protein and minerals. Cao Vit gibbons selected fruits that contain less total nitrogen, less acid detergent fiber and more water-soluble sugar than non-food fruits. Several food species that were heavily consumed by Cao Vit gibbons are suggested as potential tree species for ongoing habitat restoration.

  9. Domain-specific expertise of chemistry teachers on context-based education about macro-micro thinking in structure-property relations

    NARCIS (Netherlands)

    Dolfing, R.; Bulte, A.M.W.; Pilot, A.; Vermunt, J. D.

    2012-01-01

    This study aims to determine and describe the new domain-specific expertise of experienced chemistry teachers in teaching an innovative context-based unit about macro– micro thinking in structure–property relations. The construct of ‘teachers’ domain-specific expertise’ was used to analyse the new r

  10. Selenol Protecting Groups in Organic Chemistry: Special Emphasis on Selenocysteine Se-Protection in Solid Phase Peptide Synthesis

    Directory of Open Access Journals (Sweden)

    Stevenson Flemer Jr.

    2011-04-01

    Full Text Available The appearance of selenium in organic synthesis is relatively rare, and thus examples in the literature pertaining to the masking of its considerable reactivity are similarly uncommon. Greene's Protecting Groups in Organic Synthesis, the standard reference for the state of the art in this arena, offers no entries for selenium protective methodology, in stark comparison to its mention of the great variety of protecting groups germane to its chalcogen cousin sulfur. This scarcity of Se-protection methods makes it no less interesting and pertinent toward the construction of selenium-containing organic systems which do indeed require the iterative blocking and de-blocking of selenol functionalities. A selenium-containing system which is especially relevant is selenocysteine, as its use in Solid Phase Peptide Synthesis requires extensive protection of its selenol side chain. This review will attempt to summarize the current state of understanding with regard to selenium protection protocol in organic synthesis. Moreover, it will provide a special emphasis on selenocysteine side chain protection, comprising both the breadth of functionality used for this purpose as well as methods of deprotection.

  11. Selenol protecting groups in organic chemistry: special emphasis on selenocysteine Se-protection in solid phase peptide synthesis.

    Science.gov (United States)

    Flemer, Stevenson

    2011-04-18

    The appearance of selenium in organic synthesis is relatively rare, and thus examples in the literature pertaining to the masking of its considerable reactivity are similarly uncommon. Greene's Protecting Groups in Organic Synthesis, the standard reference for the state of the art in this arena, offers no entries for selenium protective methodology, in stark comparison to its mention of the great variety of protecting groups germane to its chalcogen cousin sulfur. This scarcity of Se-protection methods makes it no less interesting and pertinent toward the construction of selenium-containing organic systems which do indeed require the iterative blocking and de-blocking of selenol functionalities. A selenium-containing system which is especially relevant is selenocysteine, as its use in Solid Phase Peptide Synthesis requires extensive protection of its selenol side chain. This review will attempt to summarize the current state of understanding with regard to selenium protection protocol in organic synthesis. Moreover, it will provide a special emphasis on selenocysteine side chain protection, comprising both the breadth of functionality used for this purpose as well as methods of deprotection.

  12. Numerical analysis of relative phase and amplitude at the interaction two solitons in optical fibers

    Directory of Open Access Journals (Sweden)

    Jakšić Branimir

    2011-01-01

    Full Text Available In this paper presented the analysis propagation solitons pair in optical fiber from the standpoint of relative amplitude and relative phase. Consider the influence of changes relative phase and amplitude in the interaction of two solitons in optical fibers. Shows the simulation (in the space-time domain of movement solitons pairs in optical fiber with the change of these two parameters.

  13. Relative roles of endolithic algae and carbonate chemistry variability in the skeletal dissolution of crustose coralline algae

    Science.gov (United States)

    Reyes-Nivia, C.; Diaz-Pulido, G.; Dove, S.

    2014-09-01

    The susceptibility of crustose coralline algae (CCA) skeletons to dissolution is predicted to increase as oceans warm and acidify. Skeletal dissolution is caused by bioerosion from endolithic microorganisms and by chemical processes associated with undersaturation of carbonate minerals in seawater. Yet, the relative contribution of algal microborers and seawater carbonate chemistry to the dissolution of organisms that cement reefs under projected pCO2 and temperature (pCO2-T) scenarios have not been quantified. We exposed CCA skeletons (Porolithon onkodes) to four pCO2-T treatments (pre-industrial, present-day, SRES-B1 "reduced" pCO2, and SRES-A1FI "business-as-usual" pCO2 emission scenarios) under natural light cycles vs. constant dark conditions for 8 weeks. Dissolution rates of skeletons without photo-endoliths were dramatically higher (200%) than those colonized by endolithic algae across all pCO2-T scenarios. This suggests that daytime photosynthesis by microborers counteract dissolution by reduced saturation states resulting in lower net erosion rates over day-night cycles. Regardless of the presence or absence of phototrophic microborers, skeletal dissolution increased significantly under the spring A1FI "business-as-usual" scenario, confirming the CCA sensitivity to future oceans. Projected ocean acidity and temperature may significantly disturb the stability of reef frameworks cemented by CCA, but surficial substrates harbouring photosynthetic microborers will be less impacted than those without algal endoliths.

  14. Relative roles of endolithic algae and carbonate chemistry variability in the skeletal dissolution of crustose coralline algae

    Directory of Open Access Journals (Sweden)

    C. Reyes-Nivia

    2014-02-01

    Full Text Available The susceptibility of crustose coralline algae (CCA skeletons to dissolution is predicted to increase as oceans warm and acidify. Skeletal dissolution is caused by bioerosion from endolithic microorganisms and by chemical processes associated with undersaturation of carbonate minerals in seawater. Yet, the relative contribution of algal microborers and seawater carbonate chemistry to the dissolution of organisms that cement reefs under projected CO2 and temperature (CO2-T scenarios have not been quantified. We exposed CCA skeletons (Porolithon onkodes to four CO2-T treatments (pre-industrial, present-day, SRES-B1 reduced CO2 emission scenario, SRES-A1FI business-as-usual CO2 emission scenario under natural light cycles vs. constant dark conditions for 8 weeks. Dissolution rates of skeletons without photo-endoliths were dramatically higher (200% than those colonized by endolithic algae across all CO2-T scenarios. This suggests that daytime photosynthesis by microborers counteract dissolution by reduced saturation states resulting in lower net erosion rates over day-night cycles. Regardless of the presence or absence of phototrophic microborers, skeletal dissolution increased significantly under the spring A1FI "business-as-usual" scenario, confirming the CCA sensitivity to future oceans. Projected ocean acidity and temperature may significantly disturb the stability of reef frameworks cemented by CCA, but surficial substrates harboring photosynthetic microborers will be less impacted than those without algal endoliths.

  15. Identifying biotic integrity and water chemistry relations in nonwadeable rivers of Wisconsin: Toward the development of nutrient criteria

    Science.gov (United States)

    Weigel, B.M.; Robertson, D.M.

    2007-01-01

    We sampled 41 sites on 34 nonwadeable rivers that represent the types of rivers in Wisconsin, and the kinds and intensities of nutrient and other anthropogenic stressors upon each river type. Sites covered much of United States Environmental Protection Agency national nutrient ecoregions VII-Mostly Glaciated Dairy Region, and VIII-Nutrient Poor, Largely Glaciated upper Midwest. Fish, macroinvertebrates, and three categories of environmental variables including nutrients, other water chemistry, and watershed features were collected using standard protocols. We summarized fish assemblages by index of biotic integrity (IBI) and its 10 component measures, and macroinvertebrates by 2 organic pollution tolerance and 12 proportional richness measures. All biotic and environmental variables represented a wide range of conditions, with biotic measures ranging from poor to excellent status, despite nutrient concentrations being consistently higher than reference concentrations reported for the regions. Regression tree analyses of nutrients on a suite of biotic measures identified breakpoints in total phosphorus (~0.06 mg/l) and total nitrogen (~0.64 mg/l) concentrations at which biotic assemblages were consistently impaired. Redundancy analyses (RDA) were used to identify the most important variables within each of the three environmental variable categories, which were then used to determine the relative influence of each variable category on the biota. Nutrient measures, suspended chlorophyll a, water clarity, and watershed land cover type (forest or row-crop agriculture) were the most important variables and they explained significant amounts of variation within the macroinvertebrate (R 2 = 60.6%) and fish (R 2 = 43.6%) assemblages. The environmental variables selected in the macroinvertebrate model were correlated to such an extent that partial RDA analyses could not attribute variation explained to individual environmental categories, assigning 89% of the explained

  16. Salt effect on the (polyethylene glycol 8000 + sodium sulfate) aqueous two-phase system: Relative hydrophobicity of the equilibrium phases

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Luisa A., E-mail: laferreira@deb.uminho.pt [IBB - Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Teixeira, Jose A. [IBB - Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2011-08-15

    Highlights: > Gibbs free energy of transfer of a methylene group on PEG 8000 - Na{sub 2}SO{sub 4} ATPS. > Influence of salt additive on the hydrophobic character of the coexisting phases. > Partitioning behavior of a series of five sodium salts of DNP-amino acids. > A relationship between {Delta}G(CH{sub 2}), TLL and I of the salt additive was established. - Abstract: The relative hydrophobicity of the phases of several {l_brace}polyethylene glycol (PEG) 8000 + sodium sulfate (Na{sub 2}SO{sub 4}){r_brace} aqueous two-phase systems (ATPSs), all containing 0.01 mol . L{sup -1} sodium phosphate buffer (NaPB, pH 7.4) and increasing concentration of a salt additive, NaCl or KCl, up to 1.0 mol . L{sup -1}, was measured by the free energy of transfer of a methylene group between the phases, {Delta}G(CH{sub 2}). The {Delta}G(CH{sub 2}) of the systems was determined by partitioning of a homologous series of five sodium salts of dinitrophenylated (DNP) - amino acids with aliphatic side chains in three different tie-lines of each biphasic system. The relative hydrophobicity of the phases ranged from -0.125 to -0.183 kcal . mol{sup -1}, being the NaCl salt the one to provide the more effective changes. The results show that, within each system, there is a linear relationship between the {Delta}G(CH{sub 2}) and the tie-line length (TLL), and biphasic systems with high salt additive concentration present the most negative {Delta}G(CH{sub 2}) values. Therefore, the feasibility of establishing a relationship between the relative hydrophobicity of the phases in a given TLL and the ionic strength of the salt additive was investigated and a satisfactory correlation was found for each salt.

  17. Teaching skiing at the fundamental and sports-related movement phase

    OpenAIRE

    Berus, Eva

    2013-01-01

    In the undergraduate thesis we focused on the differences in teaching skiing during different movement phases. The methods we use in the teaching process have to be adapted to the developmental level of the individuals that we teach. Gallahue and Ozmun (2006) followed the developmental characteristics and created phases that are divided into: reflexive, rudimentary, fundamental and sports-related movement phase. In this thesis we discuss the differences in teaching during the fundamental and ...

  18. Gas Hydrate Stability and Sampling: The Future as Related to the Phase Diagram

    Directory of Open Access Journals (Sweden)

    E. Dendy Sloan

    2010-12-01

    Full Text Available The phase diagram for methane + water is explained, in relation to hydrate applications, such as in flow assurance and in nature. For natural applications, the phase diagram determines the regions for hydrate formation for two- and three-phase conditions. Impacts are presented for sample preparation and recovery. We discuss an international study for “Round Robin” hydrate sample preparation protocols and testing.

  19. A plant-wide aqueous phase chemistry module describing pH variations and ion speciation/pairing in wastewater treatment process models.

    Science.gov (United States)

    Flores-Alsina, Xavier; Kazadi Mbamba, Christian; Solon, Kimberly; Vrecko, Darko; Tait, Stephan; Batstone, Damien J; Jeppsson, Ulf; Gernaey, Krist V

    2015-11-15

    There is a growing interest within the Wastewater Treatment Plant (WWTP) modelling community to correctly describe physico-chemical processes after many years of mainly focusing on biokinetics. Indeed, future modelling needs, such as a plant-wide phosphorus (P) description, require a major, but unavoidable, additional degree of complexity when representing cationic/anionic behaviour in Activated Sludge (AS)/Anaerobic Digestion (AD) systems. In this paper, a plant-wide aqueous phase chemistry module describing pH variations plus ion speciation/pairing is presented and interfaced with industry standard models. The module accounts for extensive consideration of non-ideality, including ion activities instead of molar concentrations and complex ion pairing. The general equilibria are formulated as a set of Differential Algebraic Equations (DAEs) instead of Ordinary Differential Equations (ODEs) in order to reduce the overall stiffness of the system, thereby enhancing simulation speed. Additionally, a multi-dimensional version of the Newton-Raphson algorithm is applied to handle the existing multiple algebraic inter-dependencies. The latter is reinforced with the Simulated Annealing method to increase the robustness of the solver making the system not so dependent of the initial conditions. Simulation results show pH predictions when describing Biological Nutrient Removal (BNR) by the activated sludge models (ASM) 1, 2d and 3 comparing the performance of a nitrogen removal (WWTP1) and a combined nitrogen and phosphorus removal (WWTP2) treatment plant configuration under different anaerobic/anoxic/aerobic conditions. The same framework is implemented in the Benchmark Simulation Model No. 2 (BSM2) version of the Anaerobic Digestion Model No. 1 (ADM1) (WWTP3) as well, predicting pH values at different cationic/anionic loads. In this way, the general applicability/flexibility of the proposed approach is demonstrated, by implementing the aqueous phase chemistry module in some

  20. Computational chemistry

    Science.gov (United States)

    Arnold, J. O.

    1987-01-01

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

  1. A RECENT ACCRETION BURST IN THE LOW-MASS PROTOSTAR IRAS 15398-3359: ALMA IMAGING OF ITS RELATED CHEMISTRY

    Energy Technology Data Exchange (ETDEWEB)

    Jørgensen, Jes K.; Brinch, Christian; Lindberg, Johan E.; Bisschop, Suzanne E. [Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø. (Denmark); Visser, Ruud; Bergin, Edwin A. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Sakai, Nami; Yamamoto, Satoshi [Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Harsono, Daniel; Van Dishoeck, Ewine F.; Persson, Magnus V., E-mail: jeskj@nbi.dk [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

    2013-12-20

    Low-mass protostars have been suggested to show highly variable accretion rates throughout their evolution. Such changes in accretion, and related heating of their ambient envelopes, may trigger significant chemical variations on different spatial scales and from source-to-source. We present images of emission from C{sup 17}O, H{sup 13}CO{sup +}, CH{sub 3}OH, C{sup 34}S and C{sub 2}H toward the low-mass protostar IRAS 15398-3359 on 0.''5 (75 AU diameter) scales with the Atacama Large Millimeter/submillimeter Array at 340 GHz. The resolved images show that the emission from H{sup 13}CO{sup +} is only present in a ring-like structure with a radius of about 1-1.''5 (150-200 AU) whereas the CO and other high dipole moment molecules are centrally condensed toward the location of the central protostar. We propose that HCO{sup +} is destroyed by water vapor present on small scales. The origin of this water vapor is likely an accretion burst during the last 100-1000 yr increasing the luminosity of IRAS 15398-3359 by a factor of 100 above its current luminosity. Such a burst in luminosity can also explain the centrally condensed CH{sub 3}OH and extended warm carbon-chain chemistry observed in this source and furthermore be reflected in the relative faintness of its compact continuum emission compared to other protostars.

  2. 76 FR 55947 - Industrial Relations Promotion Project, Phase II in Vietnam

    Science.gov (United States)

    2011-09-09

    ... of the Secretary Industrial Relations Promotion Project, Phase II in Vietnam AGENCY: Bureau of... implementing a program to strengthen compliance with international labor standards in Vietnam, focusing... has the recognized authority and capacity to fulfill the intent of the IRRP Phase II in Vietnam....

  3. Dynamical effects of an unconventional current-phase relation in YBCO dc SQUIDs.

    Science.gov (United States)

    Lindström, T; Charlebois, S A; Tzalenchuk, A Ya; Ivanov, Z; Amin, M H S; Zagoskin, A M

    2003-03-21

    The predominant d-wave pairing symmetry in high-temperature superconductors allows for a variety of current-phase relations in Josephson junctions, which is to a certain degree fabrication controlled. In this Letter, we report on direct experimental observations of the effects of a nonsinusoidal current-phase dependence in YBCO dc SQUIDs, which agree with the theoretical description of the system.

  4. C1-Continuous relative permeability and hybrid upwind discretization of three phase flow in porous media

    Science.gov (United States)

    Lee, S. H.; Efendiev, Y.

    2016-10-01

    Three-phase flow in a reservoir model has been a major challenge in simulation studies due to slowly convergent iterations in Newton solution of nonlinear transport equations. In this paper, we examine the numerical characteristics of three-phase flow and propose a consistent, "C1-continuous discretization" (to be clarified later) of transport equations that ensures a convergent solution in finite difference approximation. First, we examine three-phase relative permeabilities that are critical in solving nonlinear transport equations. Three-phase relative permeabilities are difficult to measure in the laboratory, and they are often correlated with two-phase relative permeabilities (e.g., oil-gas and water-oil systems). Numerical convergence of non-linear transport equations entails that three-phase relative permeability correlations are a monotonically increasing function of the phase saturation and the consistency conditions of phase transitions are satisfied. The Modified Stone's Method II and the Linear Interpolation Method for three-phase relative permeability are closely examined for their mathematical properties. We show that the Linear Interpolation Method yields C1-continuous three-phase relative permeabilities for smooth solutions if the two phase relative permeabilities are monotonic and continuously differentiable. In the second part of the paper, we extend a Hybrid-Upwinding (HU) method of two-phase flow (Lee, Efendiev and Tchelepi, ADWR 82 (2015) 27-38) to three phase flow. In the HU method, the phase flux is divided into two parts based on the driving forces (in general, it can be divided into several parts): viscous and buoyancy. The viscous-driven and buoyancy-driven fluxes are upwinded differently. Specifically, the viscous flux, which is always co-current, is upwinded based on the direction of the total velocity. The pure buoyancy-induced flux is shown to be only dependent on saturation distributions and counter-current. In three-phase flow, the

  5. Comparative analysis of meteorological performance of coupled chemistry-meteorology models in the context of AQMEII phase 2

    Science.gov (United States)

    Air pollution simulations critically depend on the quality of the underlying meteorology. In phase 2 of the Air Quality Model Evaluation International Initiative (AQMEII-2), thirteen modeling groups from Europe and four groups from North America operating eight different regional...

  6. Organometallics meet colloid chemistry: a case study in three phases based on molecular carbonyl precursors containing zinc and manganese.

    Science.gov (United States)

    Orlov, A; Roy, A; Lehmann, M; Driess, M; Polarz, S

    2007-01-17

    Two organometallic compounds containing zinc and manganese in different ratios are used as single-source precursors for the preparation of various new, bimetallic oxide materials with nanoscaled dimensions. It is shown that the materials synthesis can be performed in the solid-state, the liquid-phase, and even in the gas-phase. The molecular composition of the precursors determines the composition of the resulting materials. In addition, two novel methods for the preparation of highly crystalline metal oxide colloids are presented: The coupling between a gas-phase process and a colloidal approach, and the application of ozone as an oxidant for the transformation of metal carbonyls into oxides in the liquid phase.

  7. A plant wide aqueous phase chemistry model describing pH variations and ion speciation/pairing in wastewater treatment process models

    DEFF Research Database (Denmark)

    Flores-Alsina, X.; Mbamba, C. Kazadi; Solon, K.;

    There is a growing interest within the Wastewater Treatment Plant (WWTP) modelling community to correctly describe physico-chemical processes after many years of mainly focusing on biokinetics (Batstone et al., 2012). Indeed, future modelling needs, such as a plant-wide phosphorus (P) description......, require a major, but unavoidable, additional degree of complexity when representing cationic/anionic behaviour in Activated Sludge (AS)/Anaerobic Digestion (AD) systems (Ikumi et al., 2014). In this paper, a plant-wide aqueous phase chemistry module describing pH variations plus ion speciation......). Simulation results show pH predictions when describing Biological Nutrient Removal (BNR) by the activated sludge models (ASM) 1, 2d and 3 (Henze et al., 2000) comparing the performance of a nitrogen removal (WWTP1) and a combined nitrogen and phosphorus removal (WWTP2) treatment plant configuration under...

  8. Electroweak phase transition and some related phenomena – a brief review

    Indian Academy of Sciences (India)

    BUDDHADEB GHOSH

    2016-09-01

    In this article, we give a bird’s eye view of the research on electroweak phase transition and some related phenomena, viz., cosmological baryogenesis, electroweak bubble dynamics and generation of gravitationalwaves. Our presentation revolves around the observation that a strong first-order electroweak phase transition cannot be obtained in the Standard Model for experimentally favoured Higgs mass and hence the cosmologicalevents associated with this kind of phase transition cannot be explained in this model. However, this phase transition can be achieved in a number of beyond Standard Models. As a prototype case, we consider the littlest Higgs model with T parity and show the results of some calculations within this model.

  9. On the Relation between Phase-Type Distributions and Positive Systems

    Directory of Open Access Journals (Sweden)

    Kyungsup Kim

    2015-01-01

    Full Text Available The relation between phase-type representation and positive system realization in both the discrete and continuous time is discussed. Using the Perron-Frobenius theorem of nonnegative matrix theory, a transformation from positive realization to phase-type realization is derived under the excitability condition. In order to explain the connection, some useful properties and characteristics such as irreducibility, excitability, transparency, and order reduction for positive realization and phase-type representation are discussed. In addition, the connection between the phase-type renewal process and the feedback positive system is discussed in the stabilization concept.

  10. Detection of S-phase cell cycle progression using 5-ethynyl-2'-deoxyuridine incorporation with click chemistry, an alternative to using 5-bromo-2'-deoxyuridine antibodies.

    Science.gov (United States)

    Buck, Suzanne B; Bradford, Jolene; Gee, Kyle R; Agnew, Brian J; Clarke, Scott T; Salic, Adrian

    2008-06-01

    The 5-bromo-2'-deoxyuridine (BrdU) labeling of cells followed by antibody staining has been the standard method for direct measurement of cells in the S-phase. Described is an improved method for the detection of S-phase cell cycle progression based upon the application of click chemistry, the copper(I)-catalyzed variant of the Huisgen [3+2] cycloaddition between a terminal alkyne and an azide. 5-ethynyl-2'-deoxyuridine (EdU) is a nucleoside analog of thymidine that is incorporated into DNA during active DNA synthesis, just like BrdU. While the BrdU assay requires harsh chemical or enzymatic disruption of helical DNA structure to allow for direct measurement of cells in the S-phase by the anti-BrdU antibody, the EdU method does not. Elimination of this requirement results in the preservation of helical DNA structure and other cell surface epitopes, decreased assay time, and increased reproducibility.

  11. Relative Phase Dependence of Double Ionization in a Synthesized Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    WANG Yuan-Sheng; XIA Chang-Long; GUO Jing; LIU Xue-Shen

    2011-01-01

    @@ We investigate the double ionization process of a three-dimensional model atom interacting with a synthesized laser pulse and explore the mechanism of non-sequential double ionization varying with the value of relative phase.The result shows that the recollision probability decreases when the value of the relative phase increases.The momentum spectra of electrons in the sequential ionization region are also illustrated.

  12. Polymer Chemistry in High School.

    Science.gov (United States)

    Stucki, Roger

    1984-01-01

    Discusses why polymer chemistry should be added to the general chemistry curriculum and what topics are appropriate (listing traditional with related polymer topics). Also discusses when and how these topics should be taught. (JN)

  13. Lightcurves and phase relations of the asteroids 82 Alkmene and 444 Gyptis

    Science.gov (United States)

    Harris, A. W.; Young, J. W.; Scaltriti, F.; Zappala, V.

    1984-01-01

    The asteroids 82 Alkmene and 444 Gyptis were observed photoelectrically at Table Mountain Observatory and at Torino Observatory during their 1979 opposition in order to determine their rotation periods and phase relations. The observations of 82 Alkmene yielded a rotation period of 12.999 h + or 0.002 h and an amplitude of variation of 0.55. The measured and corrected absolute magnitudes, when plotted against phase angle, is the best fit Lumme and Bowell (1981) theoretical phase function. The rotation period and amplitude of variation for 444 Gyptis are 6.214 h and 0.15, respectively. The phase relation of this asteroid is poorly fit by the Lumme and Bowell theory when only the multiple scattering parameter and the zero phase angle are treated as variables. A good fit can be obtained by adjusting some of the other parameters of their theory, but the physical interpretation is ambiguous.

  14. Remarks on nonlinear relation among phases and frequencies in modulational instabilities of parallel propagating Alfven waves

    CERN Document Server

    Nariyuki, Y; Nariyuki, Yasuhiro; Hada, Tohru

    2006-01-01

    Nonlinear relations among frequencies and phases in modulational instability of circularly polarized Alfven waves are discussed, within the context of one dimensional, dissipation-less, unforced fluid system. We show that generation of phase coherence is a natural consequence of the modulational instability of Alfven waves. Furthermore, we quantitatively evaluate intensity of wave-wave interaction by using bi-coherence, and also by computing energy flow among wave modes, and demonstrate that the energy flow is directly related to the phase coherence generation.

  15. Strategies of Learning Graduate Level Experiments and Its Application for the Removal of Toxic Waste Related To Mutual Solubility of Liquids and Phase Coexistence

    Directory of Open Access Journals (Sweden)

    *H. Tahir

    2012-06-01

    Full Text Available This paper describes graduate chemistry practical related to mutual solubility of liquids and phase coexistence. The diversity of the phase transition shows that heating produces mixing and separation. The practical consists of short experiment on the general theme of miscibility of aqueous and organic phases by varying the temperature. The phases were selected as phenol - water and nicotine- water system. The experiment was preceded by the interaction of equal quantities of phenol-water and nicotine-water at room temperature and higher temperature about 80°C. There was a change in miscibility of phases at higher temperature. At about 80°C the phenol-water mixture becomes monophasic while it is heterogeneous at room temperature. The water – phenol phase show limited miscibility below 70 °C. While the nicotine -water phases become heterogenous at higher temperature and at room temperature they were monophasic. The temperature at which these phases were merges is known as clearing temperature or cloud temperature. It lies on the liquid-liquid coexistence line. The experiment required careful observations by students at various temperatures ranges from 20oC to 100oC at the step of 20 0C and followed by result and discussions. Analysis of the data predicted that students were enjoying by working out the practical and it would be bestowing tremendously beneficial learning experience. The aim of this study was to explore the concept of the phenomenon of phase changes by varying the temperatures and can interpret macroscopic and microscopic properties of the system by relating to the thermodynamic properties. These experiments were beneficial for the isolation and separation of toxic compounds like nicotine and phenol from the waste stream. It is effective and low cost method to save the environment and ecosystem.

  16. Preparation of a novel weak cation exchange/hydrophobic interaction chromatography dual-function polymer-based stationary phase for protein separation using "thiol-ene click chemistry".

    Science.gov (United States)

    Yang, Fan; Bai, Quan; Zhao, Kailou; Gao, Dong; Tian, Lei

    2015-02-01

    A novel dual-function mixed-mode stationary phase based on poly(glycidyl methacrylate-co-ethylene dimethacrylate) microspheres was synthesized by thiol-ene click chemistry and characterized by infrared spectroscopy and elemental analysis. The new system displays both hydrophobic interaction chromatography (HIC) character in a high salt concentration mobile phase, and weak cation exchange (WCX) chromatography character in a low salt concentration mobile phase. It can be used to separate proteins in both ion-exchange chromatography (IEC) mode and HIC mode. The resolution and selectivity of the stationary phase were evaluated in both HIC mode and IEC mode using protein standards. In comparison with the conventional WCX and HIC columns, the results were satisfactory and acceptable. Protein mass and bioactivity recoveries of more than 96% can be achieved in both HIC mode and IEC mode using this column. The results indicate that the novel dual-function mixed-mode column in many cases can replace the use of two individual WCX and HIC columns. In addition, the effects on protein separation of different ligand structures in the dual-function stationary phase and the pH of the mobile phase used were also investigated in detail. The results show that electrostatic interaction of the ligand with proteins must match the hydrophobicity of the ligand, which is an important factor to prepare the dual-function stationary phase. On the basis of this dual-function mixed-mode chromatography column, a new two-dimensional liquid chromatography technology with a single column system was also developed in this study, and was used to renature and purify recombinant human interferon-γ from inclusion bodies. The mass recovery, purity, and specific bioactivity obtained for the purified recombinant human interferon-γ were 87.2%, 92.4%, and 2.8 × 10(7) IU/mg, respectively, in IEC mode, and 83.4%, 95.2%, and 4.3 × 10(7) IU/mg, respectively, in HIC mode. The results indicate that the

  17. Relative phase noise induced impairment in M-ary phase-shift-keying coherent optical communication system using distributed fiber Raman amplifier.

    Science.gov (United States)

    Cheng, Jingchi; Tang, Ming; Fu, Songnian; Shum, Perry Ping; Liu, Deming

    2013-04-01

    We show for the first time, to the best of our knowledge, that, in a coherent communication system that employs a phase-shift-keying signal and Raman amplification, besides the pump relative intensity noise (RIN) transfer to the amplitude, the signal's phase will also be affected by pump RIN through the pump-signal cross-phase modulation. Although the average pump power induced linear phase change can be compensated for by the phase-correction algorithm, a relative phase noise (RPN) parameter has been found to characterize pump RIN induced stochastic phase noise. This extra phase noise brings non-negligible system impairments in terms of the Q-factor penalty. The calculation shows that copumping leads to much more stringent requirements to pump RIN, and relatively larger fiber dispersion helps to suppress the RPN induced impairment. A higher-order phase-shift keying (PSK) signal is less tolerant to noise than a lower-order PSK.

  18. Triblock polyphiles through click chemistry: self-assembled thermotropic cubic phases formed by micellar and monolayer vesicular aggregates.

    Science.gov (United States)

    Tan, Xiaoping; Kong, Leiyang; Dai, Heng; Cheng, Xiaohong; Liu, Feng; Tschierske, Carsten

    2013-11-25

    Three series of triblock polyphiles consisting of a rigid 4-phenyl-1,2,3-triazole or 1,4-diphenyl-1,2,3-triazole core with three lipophilic and flexible alkoxyl chains at one end and a polar glycerol group at the opposite end were synthesized by copper-catalyzed azide-alkyne click reactions. Their mesophase behavior was studied by polarizing optical microscopy, differential scanning calorimetry, and XRD. Depending on alkyl chain length and core length, a transition from hexagonal columnar to Pm3n-type cubic phases was observed. In the cubic phases, the molecules are organized as spherical objects. Remarkably, compounds with a longer core unit have a higher tendency to form these cubic phases, and their stability is strongly enhanced over those of the compounds with a shorter core, despite longer cores having a smaller cone angle and therefore being expected to disfavor the formation of spherical objects. There is a large difference in the number of molecules involved in the spherical aggregates formed by compounds with long and short cores. Whereas the aggregates in the cubic phases of the compounds with short rod units are small and could be regarded as micellar, the long-core compounds form much larger aggregates which are regarded as a kind of monolayer vesicular aggregate.

  19. Solid-Phase Organic Chemistry: Synthesis of 2β-(HeterocyclylthiomethylPenam Derivatives on Solid Support

    Directory of Open Access Journals (Sweden)

    Ernesto G. Mata

    2000-03-01

    Full Text Available The synthesis of 2β-(heterocyclylthiomethylpenam derivatives on solid support has been developed. Compounds are obtained in good to high yields (based on loading of the original resin. The key step is the solid-phase double rearrangement of the corresponding penicillin sulfoxide.

  20. Combinatorial Solid-Phase Synthesis of Aromatic Oligoamides: A Research-Based Laboratory Module for Undergraduate Organic Chemistry

    Science.gov (United States)

    Fuller, Amelia A.

    2016-01-01

    A five-week, research-based experiment suitable for second-semester introductory organic laboratory students is described. Each student designs, prepares, and analyzes a combinatorial array of six aromatic oligoamides. Molecules are prepared on solid phase via a six-step synthetic sequence, and purities and identities are determined by analysis of…

  1. The Chemistry and Pharmacology of Anatoxin-a and Related Homotropanes with respect to Nicotinic Acetylcholine Receptors

    Directory of Open Access Journals (Sweden)

    Timothy Gallagher

    2006-04-01

    Full Text Available Abstract: This chapter covers the chemistry and nicotinic pharmacology of naturally occurring homotropane alkaloids, with an emphasis of anatoxin-a. In addition to anatoxin-a, homoanatoxin and pinnamine, as well as the major classes of synthetic derivatives of anatoxin-a including UB-165, are discussed.

  2. Using Animations in Identifying General Chemistry Students' Misconceptions and Evaluating Their Knowledge Transfer Relating to Particle Position in Physical Changes

    Science.gov (United States)

    Smith, K. Christopher; Villarreal, Savannah

    2015-01-01

    This article reports on the types of views and misconceptions uncovered after assessing 155 freshman general chemistry students on the concept of particle position during the reversible physical change of melting, using the Melting Cycle Instrument, which illustrates particulate-level representations of a melting-freezing cycle. Animations…

  3. Glycerol effects on the formation and rheology of hexagonal phase and related gel emulsion.

    Science.gov (United States)

    Alam, Mohammad Mydul; Aramaki, Kenji

    2009-08-15

    We have investigated the effects of glycerol on the formation and rheology of hexagonal phase (H(1)) and related O/H(1) gel emulsion in the water/C(12)EO(8)/dodecane system at 25 degrees C. It has been found that the aqueous solution of C(12)EO(8) forms H(1) phase, which could solubilize some amounts of dodecane. Beyond the solubilization limit, oil is separated and a two-phase region or H(1)+O phase appeared. Due to high viscosity of the H(1) phase, allows forming O/H(1) gel emulsion at the H(1)+O region. Rheological measurements (without glycerol) have shown that the rheogram of the H(1) phase does not change drastically with the addition of oil but the system is shifted to longer relaxation time. Simultaneously, the values of the absolute value(eta(*)) are found to increase with the addition of oil, which has been described with the neighboring micellar interaction. The rheogram of the O/H(1) gel emulsion shows gel type nature (G'>G'') but the viscosity monotonically decreases with increasing oil content, which could be due to the lower volume fraction of the continuous phase (H(1) phase). Addition of glycerol has brought an order-order transition or the microstructural transition from H(1)-lamellar (L(alpha)) phase, which is manifested from rheology and SAXS measurements. Viscosity of the O/H(1) gel emulsion also decreases with increasing glycerol content. Digital images show the physical appearance of the gel emulsion changes from turbid to transparent, which is depended on the glycerol concentration (since glycerol matches the refractive index of the H(1) phase and dodecane). Structural parameters of the H(1) phase have been evaluated with the help of Bohlin's model and found that the coordination number of the H(1) phase depends not only the oil and glycerol concentrations but also temperature.

  4. On the relationship between Bloch modes and phase-related refractive index of photonic crystals.

    Science.gov (United States)

    Sun, Guilin; Kirk, Andrew G

    2007-10-01

    It has previously been shown that the phase-related refractive index is positive in photonic crystals that display negative refraction at higher bands. We hypothesize that the phase velocity is governed by a wave that can be related to the dominant Bloch mode. This dominant wave can be identified from an approximate solution of Maxwell Equations using a homogeneously averaged dielectric constant and the dominant wavevector is related to the fundamental wavevector and the reciprocal lattice vectors. We validate this hypothesis by numerical Fourier decomposition of the field in the entire simulation domain. It confirms that for negative refraction at higher bands, the phase-related refractive index is indeed positive and differs significantly from the negative value of effective refractive index calculated from the band structure.

  5. Colour Chemistry

    Science.gov (United States)

    Griffiths, J.; Rattee, I. D.

    1973-01-01

    Discusses the course offerings in pure color chemistry at two universities and the three main aspects of study: dyestuff chemistry, color measurement, and color application. Indicates that there exists a constant challenge to ingenuity in the subject discipline. (CC)

  6. Chemistry Dashboard

    Science.gov (United States)

    The Chemistry Dashboard is part of a suite of dashboards developed by EPA to help evaluate the safety of chemicals. The Chemistry Dashboard provides access to a variety of information on over 700,000 chemicals currently in use.

  7. Chemistry Notes

    Science.gov (United States)

    School Science Review, 1976

    1976-01-01

    Described are eight chemistry experiments and demonstrations applicable to introductory chemistry courses. Activities include: measure of lattice enthalpy, Le Chatelier's principle, decarboxylation of soap, use of pocket calculators in pH measurement, and making nylon. (SL)

  8. Biophysical chemistry.

    Science.gov (United States)

    Häussinger, Daniel; Pfohl, Thomas

    2010-01-01

    Biophysical chemistry at the Department of Chemistry, University of Basel, covers the NMR analysis of protein-protein interaction using paramagnetic tags and sophisticated microscopy techniques investigating the dynamics of biological matter.

  9. Heterocyclic chemistry

    OpenAIRE

    Hemming, Karl

    2011-01-01

    Recent progress in the synthesis of heterocyclic compounds is presented\\ud 2010 offered highlights in pericyclic chemistry, particularly 1,3-dipolar cycloaddition chemistry, asymmetric synthesis, gold catalysis, organocatalysis, hydroamination, C–H activation and multicomponent reactions.

  10. Effect of Si-H bond on the gas-phase chemistry of trimethylsilane in the hot wire chemical vapor deposition process.

    Science.gov (United States)

    Shi, Y J; Li, X M; Toukabri, R; Tong, L

    2011-09-22

    The effect of the Si-H bond on the gas-phase reaction chemistry of trimethylsilane in the hot-wire chemical vapor deposition (HWCVD) process has been studied by examining its decomposition on a hot tungsten filament and the secondary gas-phase reactions in a reactor using a soft laser ionization source coupled with mass spectrometry. Trimethylsilane decomposes on the hot filament via Si-H and Si-CH(3) bond cleavages. A short-chain mechanism is found to dominate in the secondary reactions in the reactor. It has been shown that the hydrogen abstractions of both Si-H and C-H occur simultaneously, with the abstraction of Si-H being favored. Tetramethylsilane and hexamethyldisilane are the two major products formed from the radical recombination reactions in the termination steps. Three methyl-substituted disilacyclobutane molecules, i.e., 1,3-dimethyl-1,3-disilacyclobutane, 1,1,3-trimethyl-1,3-disilacyclobutane, and 1,1,3,3-tetramethyl-1,3-disilacyclobutane are also produced in reactor from the cycloaddition reactions of methyl-substituted silene species. Compared to tetramethylsilane and hexamethyldisilane, a common feature with trimethylsilane is that the short-chain mechanism still dominates. However, a more active involvement of the reactive silene intermediates has been found with trimethylsilane.

  11. Combinatorial chemistry

    DEFF Research Database (Denmark)

    Nielsen, John

    1994-01-01

    An overview of combinatorial chemistry is presented. Combinatorial chemistry, sometimes referred to as `irrational drug design,' involves the generation of molecular diversity. The resulting chemical library is then screened for biologically active compounds.......An overview of combinatorial chemistry is presented. Combinatorial chemistry, sometimes referred to as `irrational drug design,' involves the generation of molecular diversity. The resulting chemical library is then screened for biologically active compounds....

  12. Positronium chemistry

    CERN Document Server

    Green, James

    1964-01-01

    Positronium Chemistry focuses on the methodologies, reactions, processes, and transformations involved in positronium chemistry. The publication first offers information on positrons and positronium and experimental methods, including mesonic atoms, angular correlation measurements, annihilation spectra, and statistical errors in delayed coincidence measurements. The text then ponders on positrons in gases and solids. The manuscript takes a look at the theoretical chemistry of positronium and positronium chemistry in gases. Topics include quenching, annihilation spectrum, delayed coincidence

  13. On Riemann Solvers and Kinetic Relations for Isothermal Two-Phase Flows with Surface Tension

    CERN Document Server

    Rohde, Christian

    2016-01-01

    We consider a sharp-interface approach for the inviscid isothermal dynamics of compressible two-phase flow, that accounts for phase transition and surface tension effects. To fix the mass exchange and entropy dissipation rate across the interface kinetic relations are frequently used. The complete uni-directional dynamics can then be understood by solving generalized two-phase Riemann problems. We present new well-posedness theorems for the Riemann problem and corresponding computable Riemann solvers, that cover quite general equations of state, metastable input data and curvature effects. The new Riemann solver is used to validate different kinetic relations on physically relevant problems including a comparison with experimental data. Riemann solvers are building blocks for many numerical schemes that are used to track interfaces in two-phase flow. It is shown that the new Riemann solver enables reliable and efficient computations for physical situations that could not be treated before.

  14. STOMP Subsurface Transport Over Multiple Phases Version 1.0 Addendum: ECKEChem Equilibrium-Conservation-Kinetic Equation Chemistry and Reactive Transport

    Energy Technology Data Exchange (ETDEWEB)

    White, Mark D.; McGrail, B. Peter

    2005-12-01

    flow and transport simulator, STOMP (Subsurface Transport Over Multiple Phases). Prior to these code development activities, the STOMP simulator included sequential and scalable implementations for numerically simulating the injection of supercritical CO2 into deep saline aquifers. Additionally, the sequential implementations included operational modes that considered nonisothermal conditions and kinetic dissolution of CO2 into the saline aqueous phase. This addendum documents the advancement of these numerical simulation capabilities to include reactive transport in the STOMP simulator through the inclusion of the recently PNNL developed batch geochemistry solution module ECKEChem (Equilibrium-Conservation-Kinetic Equation Chemistry). Potential geologic reservoirs for sequestering CO2 include deep saline aquifers, hydrate-bearing formations, depleted or partially depleted natural gas and petroleum reservoirs, and coal beds. The mechanisms for sequestering carbon dioxide in geologic reservoirs include physical trapping, dissolution in the reservoir fluids, hydraulic trapping (hysteretic entrapment of nonwetting fluids), and chemical reaction. This document and the associated code development and verification work are concerned with the chemistry of injecting CO2 into geologic reservoirs. As geologic sequestration of CO2 via chemical reaction, namely precipitation reactions, are most dominate in deep saline aquifers, the principal focus of this document is the numerical simulation of CO2 injection, migration, and geochemical reaction in deep saline aquifers. The ECKEChem batch chemistry module was developed in a fashion that would allow its implementation into all operational modes of the STOMP simulator, making it a more versatile chemistry component. Additionally, this approach allows for verification of the ECKEChem module against more classical reactive transport problems involving aqueous systems.

  15. Implications of three phase bone scintigraphy for the diagnosis of bisphosphonate related osteonecrosis of the jaw

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Chae Moon; Ahn, Byeong Cheol; Choi, So Young; Kim, Do Hoon; Lee, Sang Woo; Kwon, Tae Geon; Lee, Jaetae [Kyungpook National Univ., Daegu (Korea, Republic of)

    2012-09-15

    Bisphosphonate (BP) related osteonecrosis of the jaw (BRONJ) is a well known serious complication of BP treatment. This study was undertaken to evaluate the diagnostic usefulness of three phase bone scintigraphy in patients with BRONJ. Forty one patients (48 lesions)with clinically proven BRONJ (2 males, 39 females, age 74.3{+-}6.7 years)under went Tc 99m HDP bone scintigraphy. Visual interpretation and semiquantitative analysis of uptakes using lesion to contralateral uptake ratios during the blood pool phase (BUR)and during the osseous phase (OUR)were performed, and relations were sought between these and various clinical parameters. Three phase bone scintigraphy showed increased perfusion and blood pooling in 21 (63.6%)and 27 (81.8%)of 33 lesions, respectively. The osseous phase was positive for 45 (93.8%)of the 48 lesions. Of the four inflammatory clinical parameters of BRONJ [pus discharge, pain, swelling, and erythrocyte sedimentation rate (ESR)], patients with three or more parameters had more positive findings in vascular and blood pool phase images (p=0.033, p=0.027). By semiquantitative analysis, patients with a positive ESR had statistically higher BUR and OUR (both p<0.001). Higher stage BRONJ lesions had higher OUR than lower stage lesions (p=0.003). In addition, bone scintigraphy revealed three clinically covert BRONJ lesions without bone exposure, and four patients were up staged based on bone scintigraphy. Bone scintigraphy provides a relatively sensitive means of detecting BRONJ, so it was helpful for accurate BRONJ staging. Furthermore, Increased uptakes in vascular and blood pool phases of three phase bone scintigraphy were related to the inflammatory activity of BRONJ.

  16. Preparation of {sup 183,184}Re samples for modelling a rapid gas phase chemistry of Nielsbohrium (Ns), element 107

    Energy Technology Data Exchange (ETDEWEB)

    Eichler, R.; Gaeggeler, H.W.; Eichler, B.; Tuerler, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Chemical gas phase reactions of the heavier group 7 elements in the system O{sub 2}/H{sub 2}O are presumably best suited for a separation of Nielsbohrium from the lighter transactinides. We expect a higher reaction velocity using the more reactive gas system O{sub 3}/H{sub 2}O{sub 2}. For the experimental verification of this idea we prepared {sup 183}Re/{sup 184}Re samples for thermochromatography experiments with both gas systems. (author) 8 refs.

  17. In-Situ Investigation of Gas Phase Radical Chemistry in the Catalytic Partial Oxidation of Methane on Pt

    OpenAIRE

    Geske, M.; Pelzer, K.; Horn, R.; Jentoft, F.; R. Schlögl

    2009-01-01

    The catalytic partial oxidation of methane on platinum was studied in situ under atmospheric pressure and temperatures between 1000 and 1300 °C. By combining radical measurements using a molecular beam mass spectrometer and threshold ionization with GC, GC-MS and temperature profile measurements it was demonstrated that a homogeneous reaction pathway is opened at temperatures above 1100 °C, in parallel to hetero-geneous reactions which start already at 600 °C. Before ignition of gas phase che...

  18. Asymmetric current-phase relation due to spin-orbit interaction in semiconductor nanowire Josephson junction

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Tomohiro; Eto, Mikio [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Nazarov, Yuli V. [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands (Netherlands)

    2013-12-04

    We theoretically study the current-phase relation in semiconductor nanowire Josephson junction in the presence of spin-orbit interaction. In the nanowire, the impurity scattering with strong SO interaction is taken into account using the random matrix theory. In the absence of magnetic field, the Josephson current I and phase difference φ between the superconductors satisfy the relation of I(φ) = –I(–φ). In the presence of magnetic field along the nanowire, the interplay between the SO interaction and Zeeman effect breaks the current-phase relation of I(φ) = –I(–φ). In this case, we show that the critical current depends on the current direction, which qualitatively agrees with recent experimental findings.

  19. Forensic chemistry.

    Science.gov (United States)

    Bell, Suzanne

    2009-01-01

    Forensic chemistry is unique among chemical sciences in that its research, practice, and presentation must meet the needs of both the scientific and the legal communities. As such, forensic chemistry research is applied and derivative by nature and design, and it emphasizes metrology (the science of measurement) and validation. Forensic chemistry has moved away from its analytical roots and is incorporating a broader spectrum of chemical sciences. Existing forensic practices are being revisited as the purview of forensic chemistry extends outward from drug analysis and toxicology into such diverse areas as combustion chemistry, materials science, and pattern evidence.

  20. Effects of relative phase on transient evolution in an open resonant ladder-type atomic system

    Institute of Scientific and Technical Information of China (English)

    Yang Yan-Ling; Liu Zhong-Bo; Wang Lei; Tong Dian-Min; Fan Xi-Jun

    2009-01-01

    In an open ladder-type resonant atomic system, variation in relative phase between probe and driving fields does not affect the transient evolution of populations, but it has remarkable effects on gain and dispersion of the probe field. No matter whether an incoherent pump is present or absent, transient and stationary gains without inversion (GWI) always can be obtained by choosing an appropriate value of the relative phase. When the incoherent pump is absent, the values of transient and stationary GWIs are much larger and the time interval required to reach the stationary value is longer than those when the incoherent pump is present. Varying the exit rate and the ratio between injection rates can obviously change the phase-dependent GWI. In addition, in the transient evolution process, the phenomenon of high dispersion (refractive index) without absorption occurs at some values of relative phase. In the corresponding closed system, the stationary GWI can be obtained by choosing an appropriate value of relative phase only when incoherent pump exists, moreover the gain is smaller than that in the open system.

  1. Mathematical problems for chemistry students

    CERN Document Server

    Pota, Gyorgy

    2011-01-01

    Mathematical Problems for Chemistry Students has been compiled and written (a) to help chemistrystudents in their mathematical studies by providing them with mathematical problems really occurring in chemistry (b) to help practising chemists to activate their applied mathematical skills and (c) to introduce students and specialistsof the chemistry-related fields (physicists, mathematicians, biologists, etc.) intothe world of the chemical applications.Some problems of the collection are mathematical reformulations of those in the standard textbooks of chemistry, others we

  2. The atmospheric circulation of a nine-hot Jupiter sample: Probing circulation and chemistry over a wide phase space

    CERN Document Server

    Kataria, Tiffany; Lewis, Nikole K; Visscher, Channon; Showman, Adam P; Fortney, Jonathan J; Marley, Mark S

    2016-01-01

    We present results from an atmospheric circulation study of nine hot Jupiters that comprise a large transmission spectral survey using the Hubble and Spitzer Space Telescopes. These observations exhibit a range of spectral behavior over optical and infrared wavelengths which suggest diverse cloud and haze properties in their atmospheres. By utilizing the specific system parameters for each planet, we naturally probe a wide phase space in planet radius, gravity, orbital period, and equilibrium temperature. First, we show that our model "grid" recovers trends shown in traditional parametric studies of hot Jupiters, particularly equatorial superrotation and increased day-night temperature contrast with increasing equilibrium temperature. We show how spatial temperature variations, particularly between the dayside and nightside and west and east terminators, can vary by hundreds of K, which could imply large variations in Na, K, CO and CH4 abundances in those regions. These chemical variations can be large enough...

  3. PLUG: A FORTRAN program for the analysis of PLUG flow reactors with gas-phase and surface chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Larson, R.S.

    1996-01-01

    This manual describes the structure and usage of the computer program PLUG, which simulates the behavior of plug flow chemical reactors. More specifically, the code is designed to model the non-dispersive one-dimensional flow of a chemically reacting ideal gas mixture in a conduit of essentially arbitrary geometry. The code makes use of the CHEMKIN and SURFACE CHEMKIN software packages to handle gas-phase and heterogeneous kinetics as well as thermodynamic properties. In addition, the standard implicit code DASSL is used to solve the set of differential/algebraic equations describing the reactor. These equations are briefly discussed here, after which the procedures for running PLUG are described in some detail. Input and output files for a sample problem involving chemical vapor deposition are given.

  4. Stability of gas-phase tartaric acid anions investigated by quantum chemistry, mass spectrometry, and infrared spectroscopy.

    Science.gov (United States)

    Tonner, Ralf; Schwerdtfeger, Peter; May, Amanda L; Steill, Jeffrey D; Berden, Giel; Oomens, Jos; Campagna, Shawn R; Compton, Robert N

    2012-05-17

    In an effort to understand the chemical factors that stabilize dianions, experimental and theoretical studies on the stability of the tartrate dianion were performed. Quantum chemical calculations at the coupled cluster level reveal only a metastable state with a possible decomposition pathway (O(2)C-CH(OH)-CH(OH)-CO(2))(2-) → (O(2)C-CH(OH)-CH(OH))(•-) + CO(2) + e(-) explaining the observed gas-phase instability of this dianion. Further theoretical data were collected for the bare dianion, this molecule complexed to water, sodium, and a proton, in both the meso and l forms as well as for the uncomplexed radical anion and neutral diradical. The calculations suggest that the l-tartrate dianion is more thermodynamically stable than the dianion of the meso stereoisomer and that either dianion can be further stabilized by association with a separate species that can help to balance the charge of the molecular complex. Mass spectrometry was then used to measure the energy needed to initiate collisionally induced dissociation of the racemic tartrate dianion and for the proton and sodium adducts of both the racemic and meso form of this molecule. Infrared action spectra of the dianion stereoisomers complexed with sodium were also acquired to determine the influence of the metal ion on the vibrations of the dianions and validate the computationally predicted structures. These experimental data support the theoretical conclusions and highlight the instability of the bare tartrate dianion. From the experimental work, it could also be concluded that the pathway leading to dissociation is under kinetic control because the sodium adduct of the racemic stereoisomer dissociated at lower collisional energy, although it was calculated to be more stable, and that decomposition proceeded via C-C bond dissociation as computationally predicted. Taken together, these data provide insight into the gas-phase stability of the tartrate dianion and highlight the role of adducts in

  5. Development of a Polarizable Force Field For Proteins via Ab Initio Quantum Chemistry: First Generation Model and Gas Phase Tests

    Science.gov (United States)

    KAMINSKI, GEORGE A.; STERN, HARRY A.; BERNE, B. J.; FRIESNER, RICHARD A.; CAO, YIXIANG X.; MURPHY, ROBERT B.; ZHOU, RUHONG; HALGREN, THOMAS A.

    2014-01-01

    We present results of developing a methodology suitable for producing molecular mechanics force fields with explicit treatment of electrostatic polarization for proteins and other molecular system of biological interest. The technique allows simulation of realistic-size systems. Employing high-level ab initio data as a target for fitting allows us to avoid the problem of the lack of detailed experimental data. Using the fast and reliable quantum mechanical methods supplies robust fitting data for the resulting parameter sets. As a result, gas-phase many-body effects for dipeptides are captured within the average RMSD of 0.22 kcal/mol from their ab initio values, and conformational energies for the di- and tetrapeptides are reproduced within the average RMSD of 0.43 kcal/mol from their quantum mechanical counterparts. The latter is achieved in part because of application of a novel torsional fitting technique recently developed in our group, which has already been used to greatly improve accuracy of the peptide conformational equilibrium prediction with the OPLS-AA force field.1 Finally, we have employed the newly developed first-generation model in computing gas-phase conformations of real proteins, as well as in molecular dynamics studies of the systems. The results show that, although the overall accuracy is no better than what can be achieved with a fixed-charges model, the methodology produces robust results, permits reasonably low computational cost, and avoids other computational problems typical for polarizable force fields. It can be considered as a solid basis for building a more accurate and complete second-generation model. PMID:12395421

  6. Role of Fe substitution and quenching rate on the formation of various quasicrystalline and related phases

    Indian Academy of Sciences (India)

    Varsha Khare; R S Tiwari; O N Srivastava

    2001-06-01

    We have investigated Fe substituted versions of the quasicrystalline (qc) alloy corresponding to Al65Cu20(Cr, Fe)15 with special reference to the possible occurrence of various quasicrystalline and related phases. Based on the explorations of various compositions it has been found that alloy compositions Al65Cu20Cr12Fe3 and Al65Cu20Cr9Fe6 exhibit interesting structural phases and features at different quenching rates. At higher quenching rates (wheel speed ∼ 25 m/sec) all the alloys exhibit icosahedral phase. For Al65Cu20Cr12Fe3 alloy, however, both the icosahedral and even the decagonal phases get formed at higher quenching rates. At higher quenching rate, alloy having Fe 3 at% exhibits two bcc phases, bccI ( = 8.9 Å) and bccII ( = 15.45 Å). The orientation relationships between icosahedral and crystalline phases are: Mirror plane ∥[001]bcc I and [351]bcc II, 5-fold ∥ [113]bcc II and 3-fold ∥ [110]bcc II. At lower quenching rate, the alloy having Fe 6 at% exhibits orthorhombic phase ( = 23.6 Å, = 12.4 Å, = 20.1 Å). Some prominent orientation relationships of the orthorhombic phase with decagonal phase have also been reported. At lower quenching rate (∼ 10 m/sec), the alloy (Al65Cu22Cr9Fe6) shows the presence of diffuse scattering of intensities along quasiperiodic direction of the decagonal phase. For making the occurrence of the sheets of intensities intelligible, a model based on the rotation and shift of icosahedra has been put forward.

  7. Anomalous partitioning of water in coexisting liquid phases of lipid multilayers near 100% relative humidity

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yicong; Ghosh, Sajal K.; Bera, Sambhunath; Jiang, Zhang; Schleputz, Christian M.; Karapetrova, Evguenia; Lurio, L. B.; Sinha, Sunil K.

    2015-11-30

    X-ray diffraction is used to determine the hydration dependence of a ternary mixture lipid multilayer structure which has phase separated into liquid-ordered (Lo) and liquid-disordered (Ld) phases. An anomaly is observed in the swelling behavior of the Ld phase at a relative humidity (RH) close to 100%, which is different from the anomalous swelling happens close to the main lipid gel-fluid transition. The lamellar repeat distance of the Ld phase swells by an extra 4 Å, well beyond the equilibrium spacing predicted by the inter-bilayer forces. This anomalous swelling is caused by the hydrophobic mismatch energy at the domain boundaries, which produces surprisingly long range effect.

  8. Crystal chemistry and application development of uranyl extended structure and nanoscale materials and actinyl ion-substituted mineral phases

    Science.gov (United States)

    Wylie, Ernest M.

    The worldwide use of nuclear energy presents both significant advantages and challenges for society. Actinide research seeks to address these challenges and drive advancement in the fields of nuclear science and engineering. Here, key aspects of the fuel cycle are examined from both a fundamental and an applications-based perspective. Hydrothermal, ionothermal, room-temperature evaporation, and liquid diffusion synthesis techniques and single-crystal X-ray diffraction were used to study the structures of 18 uranyl compounds and six actinyl-doped mineral phases. These compounds represent a diverse group ranging from unique molecular clusters to novel and known extended structures isolated from aqueous and ionic liquid media. Ultrafiltration techniques were utilized to separate uranyl peroxide nanoclusters from complex aqueous solutions. Inductively coupled plasma optical emission spectroscopy and mass spectrometry were used to quantify elemental distributions in the feed and permeate solutions while Raman spectroscopy, small-angle X-ray scattering, and electrospray ionization mass spectrometry were used to define the characteristics of the cluster species across a range different solution conditions.

  9. Selective Gas-Phase Oxidation and Localization of Alkylated Cysteine Residues in Polypeptide Ions via Ion/Ion Chemistry.

    Science.gov (United States)

    Pilo, Alice L; Zhao, Feifei; McLuckey, Scott A

    2016-09-01

    The thiol group in cysteine residues is susceptible to several post-translational modifications (PTMs), including prenylation, nitrosylation, palmitoylation, and the formation of disulfide bonds. Additionally, cysteine residues involved in disulfide bonds are commonly reduced and alkylated prior to mass spectrometric analysis. Several of these cysteine modifications, specifically S-alkyl modifications, are susceptible to gas-phase oxidation via selective ion/ion reactions with periodate anions. Multiply protonated peptides containing modified cysteine residues undergo complex formation upon ion/ion reaction with periodate anions. Activation of the ion/ion complexes results in oxygen transfer from the reagent to the modified sulfur residue to create a sulfoxide functionality. Further activation of the sulfoxide derivative yields abundant losses of the modification with the oxidized sulfur as a sulfenic acid (namely, XSOH) to generate a dehydroalanine residue. This loss immediately indicates the presence of an S-alkyl cysteine residue, and the mass of the loss can be used to easily deduce the type of modification. An additional step of activation can be used to localize the modification to a specific residue within the peptide. Selective cleavage to create c- and z-ions N-terminal to the dehydroalanine residue is often noted. As these types of ions are not typically observed upon collision-induced dissociation (CID), they can be used to immediately indicate where in the peptide the PTM was originally located.

  10. Solar forced Dansgaard-Oeschger events and their phase relation with solar proxies

    CERN Document Server

    Braun, H; Chialvo, D R

    2008-01-01

    North Atlantic climate during glacial times was characterized by large-amplitude switchings, the Dansgaard-Oeschger (DO) events, with an apparent tendency to recur preferably in multiples of about 1470 years. Recent work interpreted these intervals as resulting from a subharmonic response of a highly nonlinear system to quasi-periodic solar forcing plus noise. This hypothesis was challenged as inconsistent with the observed variability in the phase relation between proxies of solar activity and Greenland climate. Here we reject the claim of inconsistency by showing that this phase variability is a robust, generic feature of the nonlinear dynamics of DO events, as described by a model. This variability is expected from the fact that the events are threshold crossing events, resulting from a cooperative process between the periodic forcing and the noise. This process produces a fluctuating phase relation with the periodic forcing, consistent with proxies of solar activity and Greenland climate.

  11. Gas-phase chemistry of diphosphate anions as a tool to investigate the intrinsic requirements of phosphate ester enzymatic reactions: the [M1M2HP2O7]- ions.

    Science.gov (United States)

    Pepi, Federico; Barone, Vincenzo; Cimino, Paola; Ricci, Andreina

    2007-01-01

    Experimental studies on gaseous inorganic phosphate ions are practically nonexistent, yet they can prove helpful for a better understanding of the mechanisms of phosphate ester enzymatic processes. The present contribution extends our previous investigations on the gas-phase ion chemistry of diphosphate species to the [M(1)M(2)HP(2)O(7)](-) ions where M(1) and M(2) are the same or different and correspond to the Li, Na, K, Cs, and Rb cations. The diphosphate ions are formed by electrospray ionization of 10(-4) M solutions of Na(5)P(3)O(10) in CH(3)CN/H(2)O (1/1) and MOH bases or M salts as a source of M(+) cations. The joint application of mass spectrometric techniques and quantum-mechanical calculations makes it possible to characterize the gaseous [M(1)M(2)HP(2)O(7)](-) ions as a mixed ionic population formed by two isomeric species: linear diphosphate anion coordinated to two M(+) cations (group I) and [PO(3)M(1)M(2)HPO(4)](-) clusters (group II). The relative gas-phase stabilities and activation barriers for the isomerization I-->II, which depend on the nature of the M(+) cations, highlight the electronic susceptibility of P-O-P bond breaking in the active site of enzymes. The previously unexplored gas-phase reactivity of [M(1)M(2)HP(2)O(7)](-) ions towards alcohols of different acidity was investigated by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS). The reaction proceeds by addition of the alcohol molecule followed by elimination of a water molecule.

  12. Selenol Protecting Groups in Organic Chemistry: Special Emphasis on Selenocysteine Se-Protection in Solid Phase Peptide Synthesis

    OpenAIRE

    Stevenson Flemer Jr.

    2011-01-01

    The appearance of selenium in organic synthesis is relatively rare, and thus examples in the literature pertaining to the masking of its considerable reactivity are similarly uncommon. Greene's Protecting Groups in Organic Synthesis, the standard reference for the state of the art in this arena, offers no entries for selenium protective methodology, in stark comparison to its mention of the great variety of protecting groups germane to its chalcogen cousin sulfur. This scarcity of Se-protecti...

  13. Relative Phase with the Overlap Region of Two Bose-Einstein Condensates

    Institute of Scientific and Technical Information of China (English)

    周小计; 李卫东; 陈徐宗; 王义遒

    2002-01-01

    We present an expression of the relative phase for two interacting Bose-Einstein condensates released from an isotropic trapping potential. We discuss the interference condition between condensates and the visibility of the interference pattern reflecting the interaction between the condensates.

  14. Geometric Phases for Photons in an Optical Fibre and Some Related Predictions

    Institute of Scientific and Technical Information of China (English)

    高孝纯

    2002-01-01

    We propose a quantum electrodynamic model for the description of the time evolution of the quantum states of the photons in an optical fibre. By means of this model, we are able to make three interesting predicticons related to the geometric phases for photons.

  15. Site-Targeted Interfacial Solid-Phase Chemistry: Surface Functionalization of Organic Monolayers via Chemical Transformations Locally Induced at the Boundary between Two Solids.

    Science.gov (United States)

    Maoz, Rivka; Burshtain, Doron; Cohen, Hagai; Nelson, Peter; Berson, Jonathan; Yoffe, Alexander; Sagiv, Jacob

    2016-09-26

    Effective control of chemistry at interfaces is of fundamental importance for the advancement of methods of surface functionalization and patterning that are at the basis of many scientific and technological applications. A conceptually new type of interfacial chemical transformations has been discovered, confined to the contact surface between two solid materials, which may be induced by exposure to X-rays, electrons or UV light, or by the application of electrical bias. One of the reacting solids is a removable thin film coating that acts as a reagent/catalyst in the chemical modification of the solid surface on which it is applied. Given the diversity of thin film coatings that may be used as solid reagents/catalysts and the lateral confinement options provided by the use of irradiation masks, conductive AFM probes or stamps, and electron beams in such solid-phase reactions, this approach is suitable for precise targeting of different desired chemical modifications to predefined surface sites spanning the macro- to nanoscale.

  16. Warm gas phase chemistry as possible origin of high HDO/H2O ratios in hot and dense gases: application to inner protoplanetary discs

    CERN Document Server

    Thi, Wing-Fai; Kamp, Inga

    2009-01-01

    The origin of Earth oceans is controversial. Earth could have acquired its water either from hydrated silicates (wet Earth scenario) or from comets (dry Earth scenario). [HDO]/[H2O] ratios are used to discriminate between the scenarios. High [HDO]/[H2O] ratios are found in Earth oceans. These high ratios are often attributed to the release of deuterium enriched cometary water ice, which was formed at low gas and dust temperatures. Observations do not show high [HDO]/[H2O] in interstellar ices. We investigate the possible formation of high [HDO]/[H2O] ratios in dense (nH> 1E6 cm^{-3}) and warm gas (T=100-1000 K) by gas-phase photochemistry in the absence of grain surface chemistry. We derive analytical solutions, taking into account the major neutral-neutral reactions for gases at T>100 K. The chemical network is dominated by photodissociation and neutral-neutral reactions. Despite the high gas temperature, deuterium fractionation occurs because of the difference in activation energy between deuteration enrich...

  17. Atmospheric gas phase chemistry of CH2═NH and HNC. A first-principles approach.

    Science.gov (United States)

    Bunkan, Arne Joakim C; Tang, Yizhen; Sellevåg, Stig R; Nielsen, Claus J

    2014-07-17

    Quantum chemical methods were used to investigate the OH initiated atmospheric degradation of methanimine, CH2═NH, the major primary product in the atmospheric photo-oxidation of methylamine, CH3NH2. Energies of stationary points on potential energy surfaces of reaction were calculated using multireference perturbation theory and coupled cluster theory. The results show that hydrogen abstraction dominates over the addition route in the CH2═NH + OH reaction, and that the major primary product is HCN, while HNC and CHONH2 are minor primary products. HNC is found to react with OH exclusively via addition to the carbon atom followed by O-H scission leading to HNCO; N2O is not a product in the atmospheric photo-oxidation of HNC. Additional G4 calculations of the CH2═NH + O3 reaction show that this is too slow to be of importance at atmospheric conditions. Rate coefficients for the CH2═NH + OH and HNC + OH reactions were calculated as a function of temperature and pressure using a master equation model based on the coupled cluster theory results. The rate coefficients for OH reaction with CH2═NH and HNC at 1000 mbar and room temperature are calculated to be 3.0 × 10(-12) and 1.3 × 10(-11) cm(3) molecule(-1) s(-1), respectively. The atmospheric fate of CH2═NH is discussed and a gas phase photo-oxidation mechanism is presented.

  18. Luminosity-peak energy relation in the decay phases of gamma-ray burst pulses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Using time-resolved spectral data for a sample of 30 pulses in 27 bright GRBs detected with CGRO/BATSE, we investigate the luminosity-peak energy relation (L-E p relation) in the decay phases of these pulses. A tight L-E p relation is found for most of the pulses, but its power law index is various among pulses, which is normally distributed at 1.84±0.60(1σ) for the pulses in our sample, roughly consistent with the L-E p relation within a GRB and the isotropic gamma-ray energy-E p relation among GRBs. The large scatter of the power law index cannot be explained with both the statistical or observational effects and it may be an intrinsic feature, indicating that no universal L-E p relation would be expected among GRBs/pulses. This may strongly weaken the cosmological use of this relation.

  19. Role of precursors and coating polymers in sol-gel chemistry toward enhanced selectivity and efficiency in solid phase microextraction.

    Science.gov (United States)

    Bagheri, Habib; Piri-Moghadam, Hamed; Ahdi, Tayebeh

    2012-09-12

    To evaluate the selectivity and efficiency of solid phase microextraction (SPME) fiber coatings, synthesized by sol-gel technology, roles of precursors and coating polymers were extensively investigated. An on-line combination of capillary microextraction (CME) technique and high performance liquid chromatography (HPLC) was set up to perform the investigation. Ten different fiber coatings were synthesized in which five of them contained only the precursor and the rests were prepared using both the precursor and coating polymer. All the coatings were chemically bonded to the inner surface of copper tubes, intended to be used as the CME device and already functionalized by self-assembly monolayers of 3-(mercaptopropyl)trimethoxysilane (3MPTMOS). The selected precursors included tetramethoxysilane (TMOS), 3-(trimethoxysilyl)propylmethacrylate (TMSPMA), 3-(triethoxysilyl)-propylamine (TMSPA), 3MPTMOS, [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane (EPPTMOS) while poly(ethyleneglycol) (PEG) was chosen as the coating polymer. The effects of different precursors on the extraction efficiency and selectivity, was studied by selecting a list of compounds ranging from non-polar to polar ones, i.e. polycyclic aromatic hydrocarbon, herbicides, estrogens and triazines. The results from CME-HPLC analysis revealed that there is no significant difference between precursors, except TMOS, in which has the lowest extraction efficiency. Most of the selected precursors have rather similar interactions toward the selected analytes which include Van der Walls, dipole-dipole and hydrogen bond while TMOS has only dipole-dipole interaction and therefore the least efficiency. TMOS is silica but the other sorbents are organically modified silica (ORMOSIL). Our investigation revealed that it is rather impossible to prepare a selective coating using conventional sol-gel methodologies. The comparison study performed among the fiber coatings contained only a precursor and those synthesized by a

  20. Quantized Brans-Dicke theory: Phase transition, strong coupling limit, and general relativity

    Science.gov (United States)

    Pal, Sridip

    2016-10-01

    We show that Friedmann-Robertson-Walker geometry with a flat spatial section in quantized (Wheeler deWitt quantization) Brans-Dicke (BD) theory reveals a rich phase structure owing to anomalous breaking of a classical symmetry, which maps the scale factor a ↦λ a for some constant λ . In the weak coupling (ω ) limit, the theory goes from a symmetry preserving phase to a broken phase. The existence of a phase boundary is an obstruction to another classical symmetry [see V. Faraoni, Phys. Rev. D 59, 084021 (1999).] (which relates two BD theories with different couplings) admitted by BD theory with scale invariant matter content, i.e., Tμμ=0 . Classically, this prohibits the BD theory from reducing to general relativity (GR) for scale invariant matter content. We show that a strong coupling limit of both BD and GR preserves the symmetry involving the scale factor. We also show that with scale invariant matter content (radiation, i.e., P =1/3 ρ ), the quantized BD theory does reduce to GR as ω →∞ , which is in sharp contrast to classical behavior. This is a first known illustration of a scenario where quantized BD theory provides an example of anomalous symmetry breaking and resulting binary phase structure. We make a conjecture regarding the strong coupling limit of the BD theory in a generic scenario.

  1. Cluster-based composition rule for Laves phase-related BCC solid solution hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Qing; CHEN Feng; WU Jiang; QIANG Jianbing; DONG Chuang; ZHANG Yao; XU Fen; SUN Lixian

    2006-01-01

    A new cluster line approach for the composition rule of Laves phase-related BCC solid solution hydrogen-storage alloys was presented. The cluster line in a ternary phase diagram refers to a straight composition line linking a specific binary cluster to the third element. In the Laves phase-related BCC solid solution alloy system such as Ti-Cr-V, Ti-Cr tends to form binary Cr2Ti Laves phase while Ti-V and Cr-V to form solid solutions. This Laves phase is characterized by a close-packing icosahedral cluster Cr7Ti6. A cluster line Cr7Ti6-V is then constructed in this system. Alloy rods with a diameter of 3 mm of compositions along this line were prepared by copper-mould suction method. The alloy structure is found to vary with the V contents. Furthermore, the P-C-T measurements indicate that the cluster-line (Cr7Ti6)1-xVx alloys have large hydrogen storage capacities.

  2. Computational chemistry

    OpenAIRE

    2000-01-01

    Computational chemistry has come of age. With significant strides in computer hardware and software over the last few decades, computational chemistry has achieved full partnership with theory and experiment as a tool for understanding and predicting the behavior of a broad range of chemical, physical, and biological phenomena. The Nobel Prize award to John Pople and Walter Kohn in 1998 highlighted the importance of these advances in computational chemistry. With massively parallel computers ...

  3. Organic chemistry

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-08-15

    This book with sixteen chapter explains organic chemistry on linkage isomerism such as alkane, cycloalkane, alkene, aromatic compounds, stereo selective isomerization, aromatic compounds, stereo selective isomerization, organic compounds, stereo selective isomerization, organic halogen compound, alcohol, ether, aldehyde and ketone, carboxylic acid, dicarboxylic acid, fat and detergent, amino, carbohydrate, amino acid and protein, nucleotide and nucleic acid and spectroscopy, a polymer and medical chemistry. Each chapter has introduction structure and characteristic and using of organic chemistry.

  4. Bioinorganic Chemistry

    OpenAIRE

    Bertini, Ivano; Gray, Harry B.; Lippard, Stephen J.; Valentine, Joan Selverstone

    1994-01-01

    This book covers material that could be included in a one-quarter or one-semester course in bioinorganic chemistry for graduate students and advanced undergraduate students in chemistry or biochemistry. We believe that such a course should provide students with the background required to follow the research literature in the field. The topics were chosen to represent those areas of bioinorganic chemistry that are mature enough for textbook presentation. Although each chapter presents material...

  5. Chemistry Technology

    Data.gov (United States)

    Federal Laboratory Consortium — Chemistry technology experts at NCATS engage in a variety of innovative translational research activities, including:Design of bioactive small molecules.Development...

  6. MODELLING THE INTERACTION IN GAME SPORTS - RELATIVE PHASE AND MOVING CORRELATIONS

    Directory of Open Access Journals (Sweden)

    Martin Lames

    2006-12-01

    Full Text Available Model building in game sports should maintain the constitutive feature of this group of sports, the dynamic interaction process between the two parties. For single net/wall games relative phase is suggested to describe the positional interaction between the two players. 30 baseline rallies in tennis were examined and relative phase was calculated by Hilbert transform from the two time-series of lateral displacement and trajectory in the court respectively. Results showed that relative phase indicates some aspects of the tactical interaction in tennis. At a more abstract level the interaction between two teams in handball was studied by examining the relationship of the two scoring processes. Each process can be conceived as a random walk. Moving averages of the scoring probabilities indicate something like a momentary strength. A moving correlation (length = 20 ball possessions describes the momentary relationship between the teams' strength. Evidence was found that this correlation is heavily time-dependent, in almost every single game among the 40 examined ones we found phases with a significant positive as well as significant negative relationship. This underlines the importance of a dynamic view on the interaction in these games.

  7. Phase relations near ternary eutectic point in the Ag-In-Sb system

    Directory of Open Access Journals (Sweden)

    Jendrzejczyk-Handzlik D.

    2007-01-01

    Full Text Available The results of the phase relations near ternary eutectic point in the Ag-In-Sb system are investigated in this paper. Phase equilibrium calculation was done using Thermocalc software and experimental DTA results for the chosen alloys in the isopleths with molar ration of In:Sb = 7:3; 9:1 and 1:1. The structural characteristics of these alloys have been investigated using light optic microscopy and scanning electron microscopy, while hardness measurements have also been done. Solidification path for three ternary alloys located on three different investigated isopleths was calculated using Pandat software.

  8. Quantum State Reduction by Matter-Phase-Related Measurements in Optical Lattices

    CERN Document Server

    Kozlowski, Wojciech; Mekhov, Igor B

    2016-01-01

    A many-body atomic system coupled to quantized light is subject to weak measurement. Instead of coupling light to the on-site density, we consider the quantum backaction due to the measurement of matter-phase-related variables such as global phase coherence. We show how this unconventional approach opens up new opportunities to affect system evolution and demonstrate how this can lead to a new class of measurement projections, thus extending the measurement postulate for the case of strong competition with the system's own evolution.

  9. Effects of a Cooperative Learning Strategy on Teaching and Learning Phases of Matter and One-Component Phase Diagrams

    Science.gov (United States)

    Doymus, Kemal

    2007-01-01

    This study aims to determine the effects of cooperative learning (using the jigsaw method) on students' achievement in a general chemistry course. The Chemistry Achievement Test (CAT) and Phase Achievement Test (PAT) were used. The questions on the CAT relate to solids, liquids, gases, bonding, matter, and matter states. This test was given to…

  10. APPLICATION OF INFRARED SPECTROSCOPY TO THE ANALYSIS OF INORGANIC NITRATES. PHASE 1. SPECTRA OF INORGANIC NITRATES IN ACETONE AND THE USE OF SUCH SPECTRA IN ANALYTICAL CHEMISTRY

    Science.gov (United States)

    A study was made of the spectra of soluble inorganic nitrates in acetone solution and the use of such spectra in analytical chemistry . The spectra of...solubilities of anhydrous inorganic nitrates in acetone. The applications of the spectra of inorganic nitrates in acetone to analytical chemistry is

  11. Relation between proton decay and PMNS phase in the minimal SUSY $SO(10)$ GUT

    CERN Document Server

    Fukuyama, Takeshi; Mimura, Yukihiro

    2016-01-01

    Proton decay is one of the most important predictions of the grand unified theory (GUT). In the supersymmetric (SUSY) GUT, proton decays via the dimension-five operators need to be suppressed. In the $SO(10)$ model where ${\\bf 10}+\\overline{\\bf 126}$ Higgs fields couple to fermions, neutrino oscillation parameters including the CP-violating Pontecorvo-Maki-Nakagawa-Sakata (PMNS) phase can be related to the Yukawa couplings to generate the dimension-five operators in the unified framework. We show how the suppressed proton decay depends on the PMNS phase, and stress the importance of the precise measurements of the PMNS phase as well as the neutrino 23-mixing angle. These become especially important if the SUSY particles are found around less than a few TeV at LHC and proton decays are observed at Hyper-Kamiokande and DUNE experiments in the near future.

  12. Relation between proton decay and PMNS phase in the minimal SUSY SO(10) GUT

    Science.gov (United States)

    Fukuyama, Takeshi; Ichikawa, Koji; Mimura, Yukihiro

    2017-01-01

    Proton decay is one of the most important predictions of the grand unified theory (GUT). In the supersymmetric (SUSY) GUT, proton decays via the dimension-five operators need to be suppressed. In the SO (10) model where 10 + 126 ‾ Higgs fields couple to fermions, neutrino oscillation parameters including the CP-violating Pontecorvo-Maki-Nakagawa-Sakata (PMNS) phase can be related to the Yukawa couplings to generate the dimension-five operators in the unified framework. We show how the suppressed proton decay depends on the PMNS phase, and stress the importance of the precise measurements of the PMNS phase as well as the neutrino 23-mixing angle. These become especially important if the SUSY particles are found around less than a few TeV at LHC and proton decays are observed at Hyper-Kamiokande and DUNE experiments in the near future.

  13. Measurement of average density and relative volumes in a dispersed two-phase fluid

    Science.gov (United States)

    Sreepada, Sastry R.; Rippel, Robert R.

    1992-01-01

    An apparatus and a method are disclosed for measuring the average density and relative volumes in an essentially transparent, dispersed two-phase fluid. A laser beam with a diameter no greater than 1% of the diameter of the bubbles, droplets, or particles of the dispersed phase is directed onto a diffraction grating. A single-order component of the diffracted beam is directed through the two-phase fluid and its refraction is measured. Preferably, the refracted beam exiting the fluid is incident upon a optical filter with linearly varing optical density and the intensity of the filtered beam is measured. The invention can be combined with other laser-based measurement systems, e.g., laser doppler anemometry.

  14. Phase transitions in systems of self-propelled agents and related network models.

    Science.gov (United States)

    Aldana, M; Dossetti, V; Huepe, C; Kenkre, V M; Larralde, H

    2007-03-02

    An important characteristic of flocks of birds, schools of fish, and many similar assemblies of self-propelled particles is the emergence of states of collective order in which the particles move in the same direction. When noise is added into the system, the onset of such collective order occurs through a dynamical phase transition controlled by the noise intensity. While originally thought to be continuous, the phase transition has been claimed to be discontinuous on the basis of recently reported numerical evidence. We address this issue by analyzing two representative network models closely related to systems of self-propelled particles. We present analytical as well as numerical results showing that the nature of the phase transition depends crucially on the way in which noise is introduced into the system.

  15. Study of Phase Relations of ZnO-Containing Fayalite Slag Under Fe Saturation

    Science.gov (United States)

    Shi, Huayue; Chen, Liugang; Malfliet, Annelies; Jones, Peter Tom; Blanpain, Bart; Guo, Muxing

    2016-10-01

    A ZnO-containing fayalite-based slag can be formed in copper smelting from secondary raw materials and its high viscosity is a common issue that hinders slag tapping. In this work, the crystallization behavior of the industrial slag was observed in situ by confocal laser scanning microscopy. Solid precipitation was found to be the major cause of the poor slag fluidity. The phase relations in the industrial slag system ZnO-"FeO"-SiO2-Al2O3-CaO (CaO/SiO2 = 0.05, Al2O3/SiO2 = 0.15) were investigated by quenching the samples after reaching equilibrium at 1423 K (1150 °C) under iron saturation. The equilibrium composition of the phases was determined with electron probe micro-analysis. The effect of individual components, such as FeO, ZnO, and CaO on the phase equilibrium of the slag system has been quantitatively studied. The relation between the solid-phase fraction and the chemical composition of the slag has been revealed. Suggestions to modify the slag composition toward low viscosity are provided.

  16. THE ADVANCED CHEMISTRY BASINS PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    William Goddard; Peter Meulbroek; Yongchun Tang; Lawrence Cathles III

    2004-04-05

    In the next decades, oil exploration by majors and independents will increasingly be in remote, inaccessible areas, or in areas where there has been extensive shallow exploration but deeper exploration potential may remain; areas where the collection of data is expensive, difficult, or even impossible, and where the most efficient use of existing data can drive the economics of the target. The ability to read hydrocarbon chemistry in terms of subsurface migration processes by relating it to the evolution of the basin and fluid migration is perhaps the single technological capability that could most improve our ability to explore effectively because it would allow us to use a vast store of existing or easily collected chemical data to determine the major migration pathways in a basin and to determine if there is deep exploration potential. To this end a the DOE funded a joint effort between California Institute of Technology, Cornell University, and GeoGroup Inc. to assemble a representative set of maturity and maturation kinetic models and develop an advanced basin model able to predict the chemistry of hydrocarbons in a basin from this input data. The four year project is now completed and has produced set of public domain maturity indicator and maturation kinetic data set, an oil chemistry and flash calculation tool operable under Excel, and a user friendly, graphically intuitive basin model that uses this data and flash tool, operates on a PC, and simulates hydrocarbon generation and migration and the chemical changes that can occur during migration (such as phase separation and gas washing). The DOE Advanced Chemistry Basin Model includes a number of new methods that represent advances over current technology. The model is built around the concept of handling arbitrarily detailed chemical composition of fluids in a robust finite-element 2-D grid. There are three themes on which the model focuses: chemical kinetic and equilibrium reaction parameters, chemical

  17. Issues relating to the subtraction phase in EOG artefact correction of the EEG.

    Science.gov (United States)

    Croft, Rodney J; Barry, Robert J

    2002-06-01

    An important method for removing the effect of ocular artefact from the EEG is 'EOG correction'. This method estimates the proportion of ocular artefact that is in the EEG, and removes it by subtraction. To date, EOG correction research has focused on problems relating to the estimation of the correction coefficients. Using both mathematical rationale and empirical data, this paper addresses issues relating to the subtraction phase, such as the magnitude of error that can be expected due to EOG correction. Using ERP methodology, principal component and regression analyses, it is shown that the N1P2 complex propagates forward to the horizontal and radial (but not vertical) electrooculograms (EOG), and it is shown mathematically that this will result in EOG-correction error. Assuming an accurate estimate of ocular contamination of the EEG, maximal subtraction-phase error of the N1P2 complex was found to be a prefrontal attenuation of 15-22%, decreasing to central and occipital enhancements of 3-4% and 13-14%, respectively. The magnitude of this subtraction-phase error is compared to between-subject ERP variability and to error associated with EOG rejection (omitting data contaminated by ocular artefact). It is argued that such EOG correction error is small relative to both artefact rejection procedures and to normal variability found in ERP studies, and that it is less pernicious than artefact rejection procedures.

  18. Phase retrieval of reflection and transmission coefficients from Kramers-Kronig relations

    CERN Document Server

    Gralak, Boris; Zerrad, Myriam; Amra, Claude

    2014-01-01

    Analytic and passivity properties of reflection and transmission coefficients of thin-film multilayered stacks are investigated. Using a rigorous formalism based on the inverse Helmholtz operator, properties associated to causality principle and passivity are established when both temporal frequency and spatial wavevector are continued in the complex plane. This result extends the range of situations where the Kramers-Kronig relations can be used to deduce the phase from the intensity. In particular, it is rigorously shown that Kramers-Kronig relations for reflection and transmission coefficients remain valid at a fixed angle of incidence. Possibilities to exploit the new relationships are discussed.

  19. Phase retrieval of reflection and transmission coefficients from Kramers-Kronig relations.

    Science.gov (United States)

    Gralak, Boris; Lequime, Michel; Zerrad, Myriam; Amra, Claude

    2015-03-01

    Analytic and passivity properties of reflection and transmission coefficients of thin-film multilayered stacks are investigated. Using a rigorous formalism based on the inverse Helmholtz operator, properties associated with the causality principle and passivity are established when both the temporal frequency and spatial wave vector are continued in the complex plane. This result extends the range of situations where the Kramers-Kronig relations can be used to deduce the phase from the intensity. In particular, it is rigorously shown that the Kramers-Kronig relations for reflection and transmission coefficients remain valid for all fixed angles of incidence. Possibilities for exploiting the new relationships are discussed and numerically tested.

  20. Exploring Systematic Effects in the Relation Between Stellar Mass, Gas Phase Metallicity, and Star Formation Rate

    CERN Document Server

    Telford, O Grace; Skillman, Evan D; Conroy, Charlie

    2016-01-01

    There is evidence that the well-established mass-metallicity relation in galaxies is correlated with a third parameter: star formation rate (SFR). The strength of this correlation may be used to disentangle the relative importance of different physical processes (e.g., infall of pristine gas, metal-enriched outflows) in governing chemical evolution. However, all three parameters are susceptible to biases that might affect the observed strength of the relation between them. We analyze possible sources of systematic error, including sample bias, application of S/N cuts on emission lines, choice of metallicity calibration, uncertainty in stellar mass determination, aperture effects, and dust. We present the first analysis of the relation between stellar mass, gas phase metallicity, and SFR using strong line abundance diagnostics from Dopita et al. (2013) for ~130,000 star-forming galaxies in the Sloan Digital Sky Survey and provide a detailed comparison of these diagnostics in an appendix. Using these abundance ...

  1. Diffuse Interstellar Bands: How Are They Related to Known Gas-Phase Constituents of the ISM?

    CERN Document Server

    Welty, Daniel E

    2013-01-01

    In this brief review of recent work relating the DIBs to other gas-phase constituents of the ISM, we explore correlations between DIB equivalent widths and the column densities of various atomic and molecular species, drawn from a large database constructed for that purpose. The tightness and slopes of the correlations can provide information on how the DIBs might be related to those species (physically, chemically, spatially) and on various properties of the DIB carriers. Deviations from the mean relationships can reveal dependences of DIB strengths on other parameters, regional variations in DIB behavior, and individual sight lines where unusual environmental conditions affect the DIBs. Variations in DIB profiles (e.g., wings, substructure) and relative strengths may be related to differences in physical conditions inferred from atomic and/or molecular absorption lines.

  2. Diffuse Interstellar Bands: How are they related to known Gas-Phase Constituents of the ISM?

    Science.gov (United States)

    Welty, D. E.

    2014-02-01

    In this brief review of recent work relating the DIBs to other gas-phase constituents of the ISM, we explore correlations between DIB equivalent widths and the column densities of various atomic and molecular species, drawn from a large database constructed for that purpose. The tightness and slopes of the correlations can provide information on how the DIBs might be related to those species (physically, chemically, spatially) and on various properties of the DIB carriers. Deviations from the mean relationships can reveal dependences of DIB strengths on other parameters, regional variations in DIB behavior, and individual sight lines where unusual environmental conditions affect the DIBs. Variations in DIB profiles (e.g., wings, substructure) and relative strengths may be related to differences in physical conditions inferred from atomic and/or molecular absorption lines.

  3. Quantum chemistry

    CERN Document Server

    Lowe, John P

    1993-01-01

    Praised for its appealing writing style and clear pedagogy, Lowe's Quantum Chemistry is now available in its Second Edition as a text for senior undergraduate- and graduate-level chemistry students. The book assumes little mathematical or physical sophistication and emphasizes an understanding of the techniques and results of quantum chemistry, thus enabling students to comprehend much of the current chemical literature in which quantum chemical methods or concepts are used as tools. The book begins with a six-chapter introduction of standard one-dimensional systems, the hydrogen atom,

  4. An Examination of the Chemistry of Peroxycarboxylic Nitric Anhydrides and Related Volatile Organic Compounds During Texas Air Quality Study 2000 Using Ground-Based Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, James M.; Jobson, B Tom T.; Kuster, W. C.; Goldan, P. D.; Murphy, Paul; Williams, Eric; Frost, G. J.; Riemer, D.; Apel, Eric; Stroud, C.; Wiedinmyer, Christine; Fehsenfeld, Fred C.

    2003-08-19

    Measurements of peroxycarboxylic nitric anhydrides (PANs) along with related volatile organic compounds (VOCs) were made at the La Porte super site during the TexAQS 2000 Houston study. The PAN mixing ratios ranged up to 6.5 ppbv and were broadly correlated with O3, characteristic of a highly polluted urban environment. The anthropogenic PAN homologue concentrations were generally consistent with those found in other urban environments; peroxypropionic nitric anhydride (PPN) averaged 15%, and peroxyisobutyric nitric anhydride (PiBN) averaged 3% of PAN,. Some periods were noted where local petrochemical sources resulted in anomalous PANs chemistry. This effect was especially noticeable in the case of peroxyacrylic nitric anhydride (APAN) where local sources of 1,3-butadiene and acrolein resulted in APAN as high as 30% of PAN. Peroxymethacrylic nitric anhydride (MPAN) was a fairly minor constituent of the PANs except for two periods on 4 and 5 September when air masses from high biogenic hydrocarbons (BHC) areas were observed. BHC chemistry was not a factor in the highest ozone pollution episodes in Houston but may have an impact on daily average ozone levels in some circumstances.

  5. Teacher Didactic Content Knowledge and its relation with the utilization of practical activities in chemistry classes: A study with expert teachers of the Angolan educational system

    Directory of Open Access Journals (Sweden)

    Laurinda Baca

    2014-03-01

    Full Text Available This study was developed within the Angolan educational system, with chemistry expert teachers who teach the 7th grade (12 years old. Aiming to characterize the didactic content knowledge and relate it with the quality of teaching and with the development of practical activities that ensure the active participation of students in the construction of knowledge, we observed and analyzed the classes of a group of expert teachers, specifically in the content of chemical reactions and chemical equations. In a quasi-experimental design methodology, the used technique was the observation from the capture of images in the classes. An element we paid particular attention in the analysis of the classes was the implementation of strategies that involve practical activities, since the didactic research has amply demonstrated that they are likely to generate active learning in science education, with particular emphasis in chemistry. The results revealed that the expert teachers often use practical activities in their classrooms, using group work procedures, work front and questions oral and written.

  6. Introductory Chemistry

    OpenAIRE

    Baron, Mark; Gonzalez-Rodriguez, Jose; Stevens, Gary; Gray, Nathan; Atherton, Thomas; Winn, Joss

    2010-01-01

    Teaching and Learning resources for the 1st Year Introductory Chemistry course (Forensic Science). 30 credits. These are Open Educational Resources (OER), made available for re-use under a Creative Commons license.

  7. Nuclear Chemistry.

    Science.gov (United States)

    Chemical and Engineering News, 1979

    1979-01-01

    Provides a brief review of the latest developments in nuclear chemistry. Nuclear research today is directed toward increased activity in radiopharmaceuticals and formation of new isotopes by high-energy, heavy-ion collisions. (Author/BB)

  8. Materials Chemistry

    CERN Document Server

    Fahlman, Bradley D

    2011-01-01

    The 2nd edition of Materials Chemistry builds on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field. The 2nd edition continues to offer innovative coverage and practical perspective throughout. After briefly defining materials chemistry and its history, seven chapters discuss solid-state chemistry, metals, semiconducting materials, organic "soft" materials, nanomaterials, and materials characterization. All chapters have been thoroughly updated and expanded with, for example, new sections on ‘soft lithographic’ patterning, ‘click chemistry’ polymerization, nanotoxicity, graphene, as well as many biomaterials applications. The polymer and ‘soft’ materials chapter represents the largest expansion for the 2nd edition. Each ch...

  9. A multi-harmonic amplitude and relative-phase controller for active sound quality control

    Science.gov (United States)

    Mosquera-Sánchez, Jaime A.; de Oliveira, Leopoldo P. R.

    2014-04-01

    Current active sound quality control systems aim at dealing with the amplitude level of the primary disturbance, e.g. sound pressure, forces, velocities and/or accelerations, which implicitly leads to Loudness control, regardless of the spectral structure of the disturbance. As far as multi-harmonic disturbances are concerned, auditory Roughness, arguably the most related psychoacoustic metric with rumbling perception in passenger cars, can be tackled not merely by dealing with magnitudes but also with the relative-phase of the narrowband components. This paper presents an adaptive control scheme conceived for dealing with multi-harmonic disturbances, which features the independent amplitude and/or relative-phase control of the input periodic components and an improved robustness to impulsive events. The adaptive control scheme is based on a frequency-domain delayless implementation of the complex-domain, least mean squares algorithm, whereof its convergence process is improved by using a forgetting factor. The control capabilities are evaluated numerically for single- and multiple-harmonic disturbances, including realistic internal combustion engine sound contaminated with noise and by impulsive events. By using long transfer paths obtained from a real vehicle mock-up, sound pressure level reductions of 39 dBSPL and the ability to displacing the relative-phase of a number of narrowband components between [-π,π] are accomplished by the proposed control scheme. The assessment of the results by using Zwicker-Loudness and auditory Roughness models shows that the proposed adaptive algorithm is able to accomplish and stably preserve various sound quality targets, after completion of the robust convergence procedure, regardless of impulsive events that can occur during the system operation.

  10. The Relation between Students' Math and Reading Ability and Their Mathematics, Physics, and Chemistry Examination Grades in Secondary Education

    Science.gov (United States)

    Korpershoek, Hanke; Kuyper, Hans; van der Werf, Greetje

    2015-01-01

    Word problems are math- or science-related problems presented in the context of a story or real-life scenario. Literature suggests that, to solve these problems, advanced reading skills are required, in addition to content-related skills in, for example, mathematics. In the present study, we investigated the relation between students' reading…

  11. Quantum State Reduction by Matter-Phase-Related Measurements in Optical Lattices

    Science.gov (United States)

    Kozlowski, Wojciech; Caballero-Benitez, Santiago F.; Mekhov, Igor B.

    2017-01-01

    A many-body atomic system coupled to quantized light is subject to weak measurement. Instead of coupling light to the on-site density, we consider the quantum backaction due to the measurement of matter-phase-related variables such as global phase coherence. We show how this unconventional approach opens up new opportunities to affect system evolution. We demonstrate how this can lead to a new class of final states different from those possible with dissipative state preparation or conventional projective measurements. These states are characterised by a combination of Hamiltonian and measurement properties thus extending the measurement postulate for the case of strong competition with the system’s own evolution. PMID:28225012

  12. Action scales for decoherence and their relation to structures in phase space

    CERN Document Server

    Alonso, D; Palao, J P; Mayato, R S; Alonso, Daniel; Palao, Jose P.

    2003-01-01

    A characteristic action $\\Delta S$ is defined whose magnitude determines the basic properties of the mean expectation value of a general displacement in phase space. These properties are related to the capability of a given environmental `monitoring' system to induce decoherence in arbitrary quantum systems coupled to it by a broad kind of interactions. We show that according to this quantity the scale for effective decoherence is given by $\\Delta S \\gtrsim\\hbar$. This characteristic action is compared with another previously defined quantity \\cite{zurek2001}, and its connection with the main features of the pattern of structures developed by the different phase space representations of the environmental state is analyzed. The relevance of $\\Delta S$ is illustrated both numerically and by analyzing a set of model quantum systems whose classical analog is chaotic, for which the Berry-Voros conjecture is valid, and where analytical expressions for the mean expectation value of the displacement are obtained expl...

  13. Green Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Collison, Melanie

    2011-05-15

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

  14. Phase relations in the Fe-FeSi system at high pressures and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Rebecca A.; Campbell, Andrew J.; Reaman, Daniel M.; Miller, Noah A.; Heinz, Dion L.; Dera, Przymyslaw; Prakapenka, Vitali B. (UC); (Maryland)

    2016-07-29

    The Earth's core is comprised mostly of iron and nickel, but it also contains several weight percent of one or more unknown light elements, which may include silicon. Therefore it is important to understand the high pressure, high temperature properties and behavior of alloys in the Fe–FeSi system, such as their phase diagrams. We determined melting temperatures and subsolidus phase relations of Fe–9 wt% Si and stoichiometric FeSi using synchrotron X-ray diffraction at high pressures and temperatures, up to ~200 GPa and ~145 GPa, respectively. Combining this data with that of previous studies, we generated phase diagrams in pressure–temperature, temperature–composition, and pressure–composition space. We find the B2 crystal structure in Fe–9Si where previous studies reported the less ordered bcc structure, and a shallower slope for the hcp+B2 to fcc+B2 boundary than previously reported. In stoichiometric FeSi, we report a wide B2+B20 two-phase field, with complete conversion to the B2 structure at ~42 GPa. The minimum temperature of an Fe–Si outer core is 4380 K, based on the eutectic melting point of Fe–9Si, and silicon is shown to be less efficient at depressing the melting point of iron at core conditions than oxygen or sulfur. At the highest pressures reached, only the hcp and B2 structures are seen in the Fe–FeSi system. We predict that alloys containing more than ~4–8 wt% silicon will convert to an hcp+B2 mixture and later to the hcp structure with increasing pressure, and that an iron–silicon alloy in the Earth's inner core would most likely be a mixture of hcp and B2 phases.

  15. Phase transitions in the common brainstem and related systems investigated by nonstationary time series analysis.

    Science.gov (United States)

    Lambertz, M; Vandenhouten, R; Grebe, R; Langhorst, P

    2000-01-14

    Neuronal activities of the reticular formation (RF) of the lower brainstem and the nucleus tractus solitarii (NTS, first relay station of baroreceptor afferents) were recorded together in the anesthized dog with related parameters of EEG, respiration and cardiovascular system. The RF neurons are part of the common brainstem system (CBS) which participates in regulation and coordination of cardiovascular, respiratory, somatomotor systems, and vigilance. Multiple time series of these physiological subsystems yield useful information about internal dynamic coordination of the organism. Essential problems are nonlinearity and instationarity of the signals, due to the dynamic complexity of the systems. Several time-resolving methods are presented to describe nonlinear dynamic couplings in the time course, particularly during phase transitions. The methods are applied to the recorded signals representing the complex couplings of the physiological subsystems. Phase transitions in these systems are detected by recurrence plots of the instationary signals. The pointwise transinformation and the pointwise conditional coupling divergence are measures of the mutual interaction of the subsystems in the state space. If the signals show marked rhythms, instantaneous frequencies and their shiftings are demonstrated by time frequency distributions, and instantaneous phase differences show couplings of oscillating subsystems. Transient signal components are reconstructed by wavelet packet time selective transient reconstruction. These methods are useful means for analyzing coupling characteristics of the complex physiological system, and detailed analyses of internal dynamic coordination of subsystems become possible. During phase transitions of the functional organization (a) the rhythms of the central neuronal activities and the peripheral systems are altered, (b) changes in the coupling between CBS neurons and cardiovascular signals, respiration and the EEG, and (c) between NTS

  16. Dissociation of diglycolamide complexes of Ln3+ (Ln = La-Lu) and An3+ (An = Pu, Am, Cm): redox chemistry of 4f and 5f elements in the gas phase parallels solution behavior.

    Science.gov (United States)

    Gong, Yu; Tian, Guoxin; Rao, Linfeng; Gibson, John K

    2014-11-17

    Tripositive lanthanide and actinide ions, Ln(3+) (Ln = La-Lu) and An(3+) (An = Pu, Am, Cm), were transferred from solution to gas by electrospray ionization as Ln(L)3(3+) and An(L)3(3+) complexes, where L = tetramethyl-3-oxa-glutaramide (TMOGA). The fragmentation chemistry of the complexes was examined by collision-induced and electron transfer dissociation (CID and ETD). Protonated TMOGA, HL(+), and Ln(L)(L-H)(2+) are the major products upon CID of La(L)3(3+), Ce(L)3(3+), and Pr(L)3(3+), while Ln(L)2(3+) is increasingly pronounced beyond Pr. A C-Oether bond cleavage product appears upon CID of all Ln(L)3(3+); only for Eu(L)3(3+) is the divalent complex, Eu(L)2(2+), dominant. The CID patterns of Pu(L)3(3+), Am(L)3(3+), and Cm(L)3(3+) are similar to those of the Ln(L)3(3+) for the late Ln. A striking exception is the appearance of Pu(IV) products upon CID of Pu(L)3(3+), in accord with the relatively low Pu(IV)/Pu(III) reduction potential in solution. Minor divalent Ln(L)2(2+) and An(L)2(2+) were produced for all Ln and An; with the exception of Eu(L)2(2+) these complexes form adducts with O2, presumably producing superoxides in which the trivalent oxidation state is recovered. ETD of Ln(L)3(3+) and An(L)3(3+) reveals behavior which parallels that of the Ln(3+) and An(3+) ions in solution. A C-Oether bond cleavage product, in which the trivalent oxidation state is preserved, appeared for all complexes; charge reduction products, Ln(L)2(2+) and Ln(L)3(2+), appear only for Sm, Eu, and Yb, which have stable divalent oxidation states. Both CID and ETD reveal chemistry that reflects the condensed-phase redox behavior of the 4f and 5f elements.

  17. Combinatorial Solid-Phase Synthesis of Balanol Analogues

    DEFF Research Database (Denmark)

    Nielsen, John; Lyngsø, Lars Ole

    1996-01-01

    The natural product balanol has served as a template for the design and synthesis of a combinatorial library using solid-phase chemistry. Using a retrosynthetic analysis, the structural analogues have been assembled from three relatively accessible building blocks. The solid-phase chemistry inclu...... including MSNT-mediated esterification of both support-bound alcohols and carboxylic acids has been implemented successfully. Copyright (C) 1996 Elsevier Science Ltd....

  18. Shape change as entropic phase transition: A study using Jarzynski relation

    Indian Academy of Sciences (India)

    Moupriya Das; Debasish Mondal; Deb Shankar Ray

    2012-01-01

    A Brownian particle in a confined space with varying cross-section, experiences an effective entropic potential in reduced dimension. We modulate the shape of the confinement and examine the nature of dynamical transition between two distinct thermalized entropic states corresponding to different shapes of the enclosure, using Jarzynski relation on the basis of work-distribution over non-equilibrium paths. Our analysis reveals that modulating the shape of the boundaries of the enclosure makes the resident Brownian particles feel an entropic phase transition.

  19. From organic chemistry to fat and oil chemistry*

    OpenAIRE

    Deffense Etienne

    2009-01-01

    With his work on animal fat and identification of fatty acids, Chevreul was a pioneer in organic chemistry. As Chevreul, I had a passion for organic chemistry too. It was then, an honour and a pleasure to present in 2008 at EFL in Athens this presentation entitled “From organic chemistry to fat and oil chemistry” because my background in organic chemistry helped me all along my professional career to understand and implement new developments related to oil and fat technology and processing. A...

  20. Phase relations and ionic transport behaviour in new mixed oxides of ceria–zirconia–gadolinia

    Energy Technology Data Exchange (ETDEWEB)

    Anithakumari, P.; Grover, V., E-mail: vinita@barc.gov.in; Tyagi, A.K.

    2015-10-25

    The present study investigates structure and the phase relations observed in complex oxide systems obtained by substituting Gd{sub 2}O{sub 3} in the mixed oxide (Ce{sub 0.8}Zr{sub 0.2})O{sub 2}. The X-ray diffraction studies performed on this system revealed two single-phasic phase-fields; fluorite-type (F-type) and C-type. The transformation from F-type to C-type structure was observed at 60 mol% Gd{sup 3+} substitution. The Raman spectroscopic studies, however, reveal further fine structural insights wherein the F-type region was observed only up to 30 mol% of Gd{sup 3+} which was followed by the co-existence of C-type ordered region and F-type region. The single-phasic C-type phase-field was observed only beyond 80 mol% Gd{sup 3+}-substitution. The AC impedance analysis revealed minimum in the activation energy and maximum in ionic conductivity values as a function of Gd{sup 3+}-content. An antagonistic interplay of activation energy and pre-exponential factor is explained as the major factor behind this behaviour. The determination of migration and association energies supported the trend observed in the ionic conductivity values as a function of Gd{sup 3+}-content. The activation energies for hopping are in good agreement with migration activation energies thus establishing that the conduction mechanism involved hopping of oxygen ions. - Highlights: • Presence of single-phasic F- and C-type phases was revealed by XRD studies. • Both, inter-anionic repulsions and ionic sizes governed the lattice parameters. • C-type micro domains in F-type region and vice versa observed by Raman spectra. • High conductivity of 30% Gd{sup 3+} doped sample agrees with low association energy. • Similar migration and hopping energies reveal the hopping mechanism for conduction.

  1. Phase noise reveals early category-specific modulation of the event-related potentials.

    Science.gov (United States)

    Németh, Kornél; Kovács, Petra; Vakli, Pál; Kovács, Gyula; Zimmer, Márta

    2014-01-01

    Previous studies have found that the amplitude of the early event-related potential (ERP) components evoked by faces, such as N170 and P2, changes systematically as a function of noise added to the stimuli. This change has been linked to an increased perceptual processing demand and to enhanced difficulty in perceptual decision making about faces. However, to date it has not yet been tested whether noise manipulation affects the neural correlates of decisions about face and non-face stimuli similarly. To this end, we measured the ERPs for faces and cars at three different phase noise levels. Subjects performed the same two-alternative age-discrimination task on stimuli chosen from young-old morphing continua that were created from faces as well as cars and were calibrated to lead to similar performances at each noise-level. Adding phase noise to the stimuli reduced performance and enhanced response latency for the two categories to the same extent. Parallel to that, phase noise reduced the amplitude and prolonged the latency of the face-specific N170 component. The amplitude of the P1 showed category-specific noise dependence: it was enhanced over the right hemisphere for cars and over the left hemisphere for faces as a result of adding phase noise to the stimuli, but remained stable across noise levels for cars over the left and for faces over the right hemisphere. Moreover, noise modulation altered the category-selectivity of the N170, while the P2 ERP component, typically associated with task decision difficulty, was larger for the more noisy stimuli regardless of stimulus category. Our results suggest that the category-specificity of noise-induced modulations of ERP responses starts at around 100 ms post-stimulus.

  2. PhasePlot: An Interactive Software Tool for Visualizing Phase Relations, Performing Virtual Experiments, and for Teaching Thermodynamic Concepts in Petrology

    Science.gov (United States)

    Ghiorso, M. S.

    2012-12-01

    The computer program PhasePlot was developed for Macintosh computers and released via the Mac App Store in December 2011. It permits the visualization of phase relations calculated from internally consistent thermodynamic data-model collections, including those from MELTS (Ghiorso and Sack, 1995, CMP 119, 197-212), pMELTS (Ghiorso et al., 2002, G-cubed 3, 10.1029/2001GC000217) and the deep mantle database of Stixrude and Lithgow-Bertelloni (2011, GJI 184, 1180-1213). The software allows users to enter a system bulk composition and a range of reference conditions, and then calculate a grid of phase relations. These relations may be visualized in a variety of ways including pseudosections, phase diagrams, phase proportion plots, and contour diagrams of phase compositions and abundances. The program interface is user friendly and the computations are fast on laptop-scale machines, which makes PhasePlot amenable to in-class demonstrations, as a tool in instructional laboratories, and as an aid in support of out-of-class exercises and research. Users focus on problem specification and interpretation of results rather than on manipulation and mechanics of computation. The software has been developed with NSF support and is free. The PhasePlot web site is at phaseplot.org where extensive user documentation, video tutorials and examples of use may be found. The original release of phase plot permitted calculations to be performed on pressure-, temperature-grids (P-T), by direct minimization of the Gibbs free energy of the system at each grid point. A revision of PhasePlot (scheduled for release to the Mac App Store in December 2012) extends capabilities to include pressure-, entropy-grids (P-S) by system enthalpy minimization, volume-, temperature-grids (V-T) by system Helmholtz energy minimization, and volume-,entropy-grids (V-S) by minimization of the Internal Energy of the system. P-S gridded results may be utilized to visualize phase relations as a function of heat

  3. Tunable current-phase relation in double-dot Josephson junctions

    Science.gov (United States)

    Koch, Jens; Le Hur, Karyn

    2008-03-01

    The current-phase relation I() for a Josephson junction contains information about the microscopic nature of the Cooper pair transfer. In particular, junctions more complicated than the single tunnel junction exhibit characteristic non-sinusoidal forms. Here, we investigate the Josephson effect in a superconducting double dot device, similar to the devices studied experimentally by Y. A. Pashkin et al. [1] and E. Bibow et al. [2]. In the vicinity of a charge degeneracy line, the system reduces to a two-level system equivalent to a charge qubit. In this regime, we find that the interplay between sequential tunneling and cotunneling of Cooper pairs leads to a strongly non-sinusoidal current- phase relation, tunable via gate electrodes. We propose the measurement of I() in a SQUID configuration, analyze the implications of flux noise, and compare our results to different types of Josephson junctions such as single-dot systems and microbridges. [1] Y. A. Pashkin et al., Nature (London) 421 (2003), 823 [2] E. Bibow, P. Lafarge, L. L'evy, Phys. Rev. Lett. 88 (2002), 017003

  4. Green chemistry: principles and practice.

    Science.gov (United States)

    Anastas, Paul; Eghbali, Nicolas

    2010-01-01

    Green Chemistry is a relatively new emerging field that strives to work at the molecular level to achieve sustainability. The field has received widespread interest in the past decade due to its ability to harness chemical innovation to meet environmental and economic goals simultaneously. Green Chemistry has a framework of a cohesive set of Twelve Principles, which have been systematically surveyed in this critical review. This article covers the concepts of design and the scientific philosophy of Green Chemistry with a set of illustrative examples. Future trends in Green Chemistry are discussed with the challenge of using the Principles as a cohesive design system (93 references).

  5. Kinetics of nitrosamine and amine reactions with NO3 radical and ozone related to aqueous particle and cloud droplet chemistry

    Science.gov (United States)

    Weller, Christian; Herrmann, Hartmut

    2015-01-01

    Aqueous phase reactivity experiments with the amines dimethylamine (DMA), diethanolamine (DEA) and pyrrolidine (PYL) and their corresponding nitrosamines nitrosodimethylamine (NDMA), nitrosodiethanolamine (NDEA) and nitrosopyrrolidine (NPYL) have been performed. NO3 radical reaction rate coefficients for DMA, DEA and PYL were measured for the first time and are 3.7 × 105, 8.2 × 105 and 8.7 × 105 M-1 s-1, respectively. Rate coefficients for NO3 + NDMA, NDEA and NPYL are 1.2 × 108, 2.3 × 108 and 2.4 × 108 M-1 s-1. Compared to OH radical rate coefficients for reactions with amines, the NO3 radical will most likely not be an important oxidant but it is a potential nighttime oxidant for nitrosamines in cloud droplets or deliquescent particles. Ozone is unreactive towards amines and nitrosamines and upper limits of rate coefficients suggest that aqueous ozone reactions are not important in atmospheric waters.

  6. Fundamental studies of fuel chemistry as related to internal combustion engine phenomena. Technical progress report, July 1, 1988--June 30, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Dryer, F.L.; Brezinsky, K.

    1989-07-01

    The present research effort was initiated with the intent of providing substantially improved insights (through homogeneous gas phase kinetic studies at different constant pressures) to the fuel chemistry issues important to autoignition in engines. The conditions of the proposed experiments were chosen to represent those similar to the engine parameters under knocking conditions: temperatures in the range of 700--1,100K, pressures from one to approximately 20 atmospheres and stoichiometries around one. A major part of the proposed research has been to design and construct a variable pressure flow reactor facility in which a range of reaction pressures, and in fact, lower reaction temperatures could be accessed. The reactor facility design and construction are nearly complete, and initial testing has begun to compare the overall experimental operating characteristics of the reactor with the design parameters. Experiments on Isobutene/oxygen mixtures have also been conducted in the existing atmospheric pressure flow reactor at about 1,150 K and in an equivalence ratio range of pyrolysis with about 100 ppm oxygen background to 0.42. A detailed kinetic model has been developed to interpret the pyrolysis and oxidation characteristics. 89 refs.

  7. News from Online: Green Chemistry

    Science.gov (United States)

    Uffelman, Erich S.

    2004-01-01

    Green chemistry closely relates to energy and environmental problems, and includes the promotion of environmental friendly products and systems within the framework of renewable resources. Various websites on green chemistry are reviewed, one of which lists the 12 commandments of this particular subject.

  8. Fundamentals of Aqueous Microwave Chemistry

    Science.gov (United States)

    The first chemical revolution changed modern life with a host of excellent amenities and services, but created serious problems related to environmental pollution. After 150 years of current chemistry principles and practices, we need a radical change to a new type of chemistry k...

  9. Quantum chemistry and relativity: exploring the physical and chemical properties of the complexes of heavy elements; Chimie quantique et relativite. Exploration des proprietes physiques et chimiques des complexes d'atomes lourds

    Energy Technology Data Exchange (ETDEWEB)

    Vallet, V. [Munich Univ., Institute for Theoretical Chemistry, Technical (Germany)

    2003-01-01

    Molecular and nano-molecular systems containing rare earth and actinides elements have extraordinary chemical and physical properties. Computer simulations using quantum chemistry methods can play an important role in many investigative procedures and provide help in understanding the microscopic nature of the interactions governing these macroscopic properties. The recent theoretical efforts have been devoted to the development of accurate and efficient methods that take into account all important interactions influencing the electronic structures, such as electron correlation and relativity. In particular, we illustrate the importance of relativity on chemical and spectroscopic properties. We will then focus on the modelling aspects of solution chemistry. (author)

  10. Polymer Chemistry

    Science.gov (United States)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  11. From Physical Chemistry to Quantum Chemistry: How Chemists Dealt with Mathematics

    OpenAIRE

    Kostas Gavroglu; Ana Simões

    2012-01-01

    Discussing the relationship of mathematics to chemistry is closely related to the emergence of physical chemistry and of quantum chemistry. We argue that, perhaps, the most significant issue that the 'mathematization of chemistry' has historically raised is not so much methodological, as it is philosophical: the discussion over the ontological status of theoretical entities which were introduced in the process. A systematic study of such an approach to the mathematization of chemistry may, pe...

  12. Advances in electron transfer chemistry

    CERN Document Server

    Mariano, Patrick S

    1993-01-01

    Advances in Electron Transfer Chemistry, Volume 3 presents studies that discuss findings in the various aspects of electron chemistry. The book is comprised of four chapters; each chapter reviews a work that tackles an issue in electron transfer chemistry. Chapter 1 discusses the photoinduced electron transfer in flexible biaryl donor-acceptor molecules. Chapter 2 tackles light-induced electron transfer in inorganic systems in homogeneous and heterogeneous phases. The book also covers internal geometry relaxation effects on electron transfer rates of amino-centered systems. The sequential elec

  13. Parallel chemistry in the 21st century.

    Science.gov (United States)

    Long, Alan

    2012-09-01

    The tool chest of techniques, methodologies, and equipment for conducting parallel chemistry is larger than ever before. Improvements in the laboratory and developments in computational chemistry have enabled compound library design at the desks of medicinal chemists. This unit includes a brief background in combinatorial/parallel synthesis chemistry, along with a discussion of evolving technologies for both solid- and solution-phase chemistry. In addition, there are discussions on designing compound libraries, acquisition/procurement of compounds and/or reagents, the chemistry and equipment used for chemical production, purification, sample handling, and data analysis.

  14. Fault instability on a finite and planar fault related to early phase of nucleation

    Science.gov (United States)

    Mitsui, Yuta; Hirahara, Kazuro

    2011-06-01

    We numerically investigate the early phase of nucleation on a planar fault with the rate- and state-dependent friction law, loaded externally by steady slip, to clarify its relation to fault instability. We define Rn as the invasion distance of the inward creep to characterize that phase. For a circular fault, the dependence of Rn on the dimensionless parameters lb, lb-a, and lRA (all of these are proportional to the rigidity and the characteristic distance of the state evolution L and inversely proportional to the normal stress and the fault radius) can be compiled. We found that Rn is proportional to lb (both aging law and slip law of the state evolution) and lb-a (aging law). In the case of the aging law only, there are two regimes (ordinary events and slow events) separated by the value of lRA. The regimes have different trend lines, although we could not measure Rn for the case of lRA < 0.35 because of breaking of the mirror symmetry of instability along the loading direction. Rn in the slow event regime is smaller. Moreover, we investigated the effect of fault shape and found that a model with a long radius along the mode 2 direction has similar parameter dependence to circular faults, but a model with a long radius along the mode 3 direction has different ones. Our results imply that we can qualitatively estimate the fault instability parameters from the early phase of nucleation, although further research is necessary to enable application to actual faults.

  15. Chemistry in Protoplanetary Disks

    CERN Document Server

    Henning, Thomas

    2013-01-01

    This comprehensive review summarizes our current understanding of the evolution of gas, solids and molecular ices in protoplanetary disks. Key findings related to disk physics and chemistry, both observationally and theoretically, are highlighted. We discuss which molecular probes are used to derive gas temperature, density, ionization state, kinematics, deuterium fractionation, and study organic matter in protoplanetary disks.

  16. A new titanium-bearing calcium aluminosilicate phase. 2: Crystallography and crystal chemistry of grains formed in slowly cooled melts with bulk compositions of calcium-aluminium-rich inclusions

    Science.gov (United States)

    Barber, David J.; Beckett, John R.; Paque, Julie M.; Stolper, Edward

    1994-01-01

    The crystallography and crystal chemistry of a new calcium- titanium-aluminosilicate mineral (UNK) observed in synthetic analogs to calcium-aluminum-rich inclusions (CAIs) from carbonaceous chondrites was studied by electron diffraction techniques. The unit cell is primitive hexagonal or trigonal, with a = 0.790 +/- 0.02 nm and c = 0.492 +/- 0.002 nm, similar to the lattice parameters of melilite and consistent with cell dimensions for crystals in a mixer furnace slag described by Barber and Agrell (1994). The phase frequently displays an epitactic relationship in which melilite acts as the host, with (0001)(sub UNK) parallel (001)(sub mel) and zone axis group 1 0 -1 0(sub UNK) parallel zone axis group 1 0 0(sub mel). If one of the two space groups determined by Barber and Agrell (1994) for their sample of UNK is applicable (P3m1 or P31m), then the structure is probably characterized by puckered sheets of octahedra and tetrahedra perpendicular to the c-axis with successive sheets coordinated by planar arrays of Ca. In this likely structure, each unit cell contains three Ca sites located in mirror planes, one octahedrally coordinated cation located along a three-fold axis and five tetrahedrally coordinated cations, three in mirrors and two along triads. The octahedron contains Ti but, because there are 1.3-1.9 cations of Ti/formula unit, some of the Ti must also be in tetrahedral coordination, an unusual but not unprecedented situation for a silicate. Tetrahedral sites in mirror planes would contain mostly Si, with lesser amounts of Al while those along the triads correspondingly contain mostly Al with subordinate Ti. The structural formula, therefore, can be expressed as Ca(sub 3)(sup VIII)(Ti,Al)(sup VI)(Al,Ti,Si)(sub 2)(sup IV)(Si,Al)(sub 3)(sup IV)O14 with Si + Ti = 4. Compositions of meteoritic and synthetic Ti-bearing samples of the phase can be described in terms of a binary solid solution between the end-members Ca3TiAl2Si3O14 and Ca3Ti(AlTi)(AlSi2)O14. A Ti

  17. Progress in physical chemistry

    CERN Document Server

    Hempelmann, Rolf

    2008-01-01

    Progress in Physical Chemistry is a collection of recent ""Review Articles"" published in the ""Zeitschrift für Physikalische Chemie"". The second volume of Progress in Physical Chemistry is a collection of thematically closely related minireview articles written by the members of the Collaborative Research Centre (SFB) 277 of the German Research Foundation (DFG). These articles are based on twelve years of intense coordinated research efforts. Central topics are the synthesis and the characterization of interface-dominated, i.e. nanostructured materials, mainly in the solid state but also as

  18. Variation of solar acoustic emission and its relation to phase of the solar cycle

    Science.gov (United States)

    Chen, Ruizhu; Zhao, Junwei

    2016-05-01

    Solar acoustic emission is closely related to solar convection and photospheric magnetic field. Variation of acoustic emission and its relation to the phase of solar cycles are important to understand dynamics of solar cycles and excitation of acoustic waves. In this work we use 6 years of SDO/HMI Dopplergram data to study acoustic emissions of the whole sun and of the quiet-sun regions, respectively, in multiple acoustic frequency bands. We show the variation of acoustic emission from May 2010 to April 2016, covering half of the solar cycle 24, and analyze its correlation with the solar activity level indexed by daily sunspot number and total magnetic flux. Results show that the correlation between the whole-Sun acoustic emission and the solar activity level is strongly negative for low frequencies between 2.5 and 4.5 mHz, but strongly positive for high frequencies between 4.5 and 6.0 mHz. For high frequencies, the acoustic emission excess in sunspot halos overwhelms the emission deficiency in sunspot umbrae and penumbrae. The correlation between the acoustic emission in quiet regions and the solar activity level is negative for 2.5-4.0 mHz and positive for 4.0-5.5 mHz. This shows that the solar background acoustic power, with active regions excluded, also varies during a solar cycle, implying the excitation frequencies or depths are highly related to the solar magnetic field.

  19. Age-related effects on circadian phase in the sleep of patients with depression and insomnia.

    Science.gov (United States)

    Xian, Hong; Gonzalez, Carlos; Deych, Elena; Farris, Suzan; Ding, Jimin; Shannon, William; McCall, W Vaughn

    2015-01-01

    We examined whether an age-related phase advance was present in 60 patients with depression and insomnia (mean age 41.5 [12.5] years) using diaries and 5 weekdays of actigraphy. Actigraphy was analyzed with functional data analysis. The low point of activity (bathyphase) for each subject was fitted by cosine function with 24-hr cycle time. Linear regression analysis revealed that increasing age was associated with earlier bedtimes (p insomnia may require prescription of earlier bedtimes and earlier rise times than would be employed in younger persons with insomnia. Further, we demonstrate that aging of the sleep system, at least as reflected in actigraphy, occurs as early as the third decade.

  20. Identification of Phase and Sex-related ISSR Markers of Red Alga Gracilaria lemaneiformis

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Six ISSR primers are employed to display the polymorphism of different phases and sexes of red alga Gracilaria lemaneiformis, and two of them, P1 and P3, amplified distinct band patterns. The ISSR pattern amplified by primer P1 of the female gametophyte is identical to that of tetrasporophyte, but distinct from that of male gametophyte. Of the bands produced by primer P3, one is specific to female gametophyte. Three morphologically similar fronds can be easily identified using ISSR technique. Two specific markers, SM1 and SF3,related to male gametophyte and female gametophyte, are cloned and sequenced. The homologous sequences of SM1 are found to encode a hypothetical protein. There is no homologous sequence of SF3 that can be found in GenBank.

  1. Enantiomer Separation of α-Dimethyl Dicarboxylate Biphenyl and Related Biphenyl Compounds by Normal Phase HPLC on Polysaccharide Based Chiral Stationary Phases

    Institute of Scientific and Technical Information of China (English)

    LIU,Yue-Qi(刘月启); HAN,Xiao-Qian(韩小茜); Qi,Bang-Feng(齐邦峰); LIU,Chun-Hui(柳春辉); LI,Yong-Min(李永民); CHEN,Li-Ren(陈立仁)

    2002-01-01

    Cellulose tris(4-methylphenylcarbamate), amylose tris(3,5-dimethylpphenylcarbamate) and amylose tris (phenylcarbamate)were prepared by the method reported by Okamoto and were coated onto an aminopropylated mesoporous spherical silica gel. These final products were used as chiral stationary phases of high performance liquid chromatography for the eighteen structurally related biphenyl conmpounds. The resolution was made using normal-phase methodology with a mobile phase consisting of n-hexane-alcohol (ethanol, 1-propanol, 2-propanol or 1-butanol). The effects of various aliphatic alcohols in the mobile phase were studied. The structural features of the solutes that influence their k'were discussed. A dominant effect of trifluoroaetic acid on chiral separation of aacidicdic solutes was noted.

  2. Element concentrations in mosses and surface waters of western Canadian mires relative to precipitation chemistry and hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Malmer, N. (Dept. of Ecology, Plant Ecology, Lund Univ., Lund (SE)); Horton, D.G. (Dept. of Botany, the Univ. of Iowa, Iowa City (US)); Vitt, D.H. (Dept. of Botany, the Univ. of Alberta, Edmonton, Alberta (CA))

    1992-01-01

    Concentrations of N, P, S, Na, K, Mg, Ca, Mn, Fe, Cu, Cd, Zn, Pb, Al, and AIA (acid insoluble ash) in mosses (three Sphagnum species and Tomenthypnum nitens, all hummock species) from a variety of mires, both ombrotrophic and minerotrophic, in the coastal western and central parts of Canada are considered in relation to surface water pH and concentrations of Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and SO{sub 4}{sup 2-}. Distinct west-east concentration gradients were present for most elements in both mosses and water, but there were correlations between surface water and moss concentrations only for Ca and Mg. On ombrotrophic sites and sites characterized by poor fen vegetation, wet deposition is the main source of elements in the surface water. On rich fen sites, additional Ca and Mg from surrounding soils change the elemental proportions. We conclude that hydrochemically the limit between poor and rich fen sites is more decisive than between bog and fen. The increase in Ca may give brown mosses a competitive advantage over Sphagnum. Moss concentrations of Na and Mg are the only ones decreasing inland. The constancy or inland increase of moss elemental concentrations may depend on either an increasing atmospheric supply (e.g. Pb), differences in moss growth rates (Especially N, P, and K) or site conditions related to the water regime (e.g. Fe and Al). (au).

  3. Planetary nebulae: the universal mass-metallicity relation for Local Group dwarf galaxies and the chemistry of NGC 205

    CERN Document Server

    Gonçalves, D R; Teodorescu, Ana M; Carneiro, Carolina M

    2014-01-01

    Here we study 16 planetary nebulae (PNe) in the dwarf irregular galaxy NGC 205 by using GMOS@Gemini spectra to derive their physical and chemical parameters. The chemical patterns and evolutionary tracks for 14 of our PNe suggest that there are no type I PNe among them. These PNe have an average oxygen abundance of 12+log(O/H)=8.08$\\pm$0.28, progenitor masses of 2-2.5M$_{\\odot}$ and thus were born ~1.0-1.7Gyr ago. Our results are in good agreement with previous PN studies in NGC 205. The present 12+log(O/H) is combined with our previous works and with the literature to study the PN metallicity trends of the Local Group (LG) dwarf galaxies, in an effort to establish the PN luminosity- and mass-metallicity relations (LZR and MZR) for the LG dwarf irregulars (dIrrs) and dwarf spheroidals (dSphs). Previous attempts to obtain such relations failed to provide correct conclusions because were based on limited samples (Richer & McCall 1995; Gon\\c{c}calves et al. 2007). As far as we are able to compare stellar wit...

  4. Podcasts in the Chemistry Teaching

    Directory of Open Access Journals (Sweden)

    Bruno Silva Leite

    2016-12-01

    Full Text Available Information and Communication Technologies (ICT provide facilities in teaching through education. There are many new tools and methodologies that use ICT as a knowledge-building support, but that are not always related to pedagogical practice. The Podcast is an important technology that can be used in the classroom. Using this tool, it can make the most interactive chemistry class, fleeing the classroom routine. However, it is necessary to point out that the podcast is just one feature that should be incorporated into education and not a substitute. This paper describes the development of Chemistry Podcasts by teachers and chemistry students in three disciplines in 2015. This study took place over a one-year period in a public University, in Pernambuco, Brazil. In the discipline of "Computer applied to the teaching of chemistry" participated 21 Chemistry teachers. In the disciplines of "Information and Communication Technologies in the teaching of chemistry" and "Informatics, Chemistry and Education" was composed of 54 undergraduate students in chemistry. Twelve podcasts were elaborated by students and five by teachers in this paper we present only nine. The results showed the contribution of podcasts produced by teachers and students in teaching and learning process chemistry. DOI: http://dx.doi.org/10.17807/orbital.v0i0.898

  5. Climate-related Changes in Tropical-fruit Flowering Phases in Songkhla Province, Southern Thailand

    Directory of Open Access Journals (Sweden)

    Supakracha Apiratikorn

    2014-04-01

    Full Text Available Changes in the timing of plant phenological phases in response to anomalous climate variability and the ongoing anthropogenic climate change have recently been studied in southern Thailand. In this study, we showed the evidence of climate-related changes in flowering phases of 2 tropical-fruit species: mangosteen (Garcinia mangostana and longkong (Lansium domesticum Corr. during 2003-2012. The flowering dates of these tropical fruits recorded at Hat Yai district, Songkhla province and daily climate data were used to assess phenophase response to variations in rainfall and evaporation. With the observed changes in local climate conditions which are defining factors for phenological development of tropical fruits particularly in southern Thailand, the flowering dates of both tropical fruits during 2003-2012 have significantly delayed comparing with the regular pattern in the past. Paradoxically, below-than-normal rainfall was also found in the El Niño years, while La Niña years were found in opposite. In summary, rainfall variations in Hat Yai district, Songkhla province are associated with ENSO. It was evident that the flowering period of tropical fruits tended to shift to the second-half of the year instead of the first-half of the year as usual. The results revealed that, during 33 years (1980-2012, annual rainfall totals, the annual number of rainy days, relative humidity, maximum and minimum temperatures from the Thai Meteorological Department significantly increased by 29.5 mm/year, 0.83 day/year, 0.116 %/year, 0.033 and 0.035C/year, respectively. These findings suggest that anthropogenically warm climate and its associated inter-annual variations in local weather patterns may to the great extent influence on tropical-fruit phenology and their responses to recent climate change seem to be complex and nonlinear. Therefore, further study is needed to shed more light on such causal-effect linkages and plausible underlying mechanisms.

  6. Calculation of the relative chemical stabilities of proteins as a function of temperature and redox chemistry in a hot spring.

    Directory of Open Access Journals (Sweden)

    Jeffrey M Dick

    Full Text Available Uncovering the chemical and physical links between natural environments and microbial communities is becoming increasingly amenable owing to geochemical observations and metagenomic sequencing. At the hot spring known as Bison Pool in Yellowstone National Park, the cooling of the water in the outflow channel is associated with an increase in oxidation potential estimated from multiple field-based measurements. Representative groups of proteins whose sequences were derived from metagenomic data also exhibit an increase in average oxidation state of carbon in the protein molecules with distance from the hot-spring source. The energetic requirements of reactions to form selected proteins used in the model were computed using amino-acid group additivity for the standard molal thermodynamic properties of the proteins, and the relative chemical stabilities of the proteins were investigated by varying temperature, pH and oxidation state, expressed as activity of dissolved hydrogen. The relative stabilities of the proteins were found to track the locations of the sampling sites when the calculations included a function for hydrogen activity that increases with temperature and is higher, or more reducing, than values consistent with measurements of dissolved oxygen, sulfide and oxidation-reduction potential in the field. These findings imply that spatial patterns in the amino acid compositions of proteins can be linked, through energetics of overall chemical reactions representing the formation of the proteins, to the environmental conditions at this hot spring, even if microbial cells maintain considerably different internal conditions. Further applications of the thermodynamic calculations are possible for other natural microbial ecosystems.

  7. Impact Of Three-Phase Relative Permeability and Hysteresis Models On Forecasts of Storage Associated with CO2-EOR

    Science.gov (United States)

    Jia, W.; Pan, F.; McPherson, B. J. O. L.

    2015-12-01

    Due to the presence of multiple phases in a given system, CO2 sequestration with enhanced oil recovery (CO2-EOR) includes complex multiphase flow processes compared to CO2 sequestration in deep saline aquifers (no hydrocarbons). Two of the most important factors are three-phase relative permeability and hysteresis effects, both of which are difficult to measure and are usually represented by numerical interpolation models. The purposes of this study included quantification of impacts of different three-phase relative permeability models and hysteresis models on CO2 sequestration simulation results, and associated quantitative estimation of uncertainty. Four three-phase relative permeability models and three hysteresis models were applied to a model of an active CO2-EOR site, the SACROC unit located in western Texas. To eliminate possible bias of deterministic parameters on the evaluation, a sequential Gaussian simulation technique was utilized to generate 50 realizations to describe heterogeneity of porosity and permeability, initially obtained from well logs and seismic survey data. Simulation results of forecasted pressure distributions and CO2 storage suggest that (1) the choice of three-phase relative permeability model and hysteresis model have noticeable impacts on CO2 sequestration simulation results; (2) influences of both factors are observed in all 50 realizations; and (3) the specific choice of hysteresis model appears to be somewhat more important relative to the choice of three-phase relative permeability model in terms of model uncertainty.

  8. Chemistry for whom? Gender awareness in teaching and learning chemistry

    Science.gov (United States)

    Andersson, Kristina

    2016-11-01

    Marie Ståhl and Anita Hussénius have defined what discourses dominate national tests in chemistry for Grade 9 in Sweden by using feminist, critical didactic perspectives. This response seeks to expand the results in Ståhl and Hussénius's article Chemistry inside an epistemological community box!—Discursive exclusions and inclusions in the Swedish national tests in chemistry, by using different facets of gender awareness. The first facet—Gender awareness in relations to the test designers' own conceptions—highlighted how the gender order where women are subordinated men becomes visible in the national tests as a consequence of the test designers internalized conceptions. The second facet—Gender awareness in relation to chemistry—discussed the hierarchy between discourses within chemistry. The third facet—Gender awareness in relation to students—problematized chemistry in relation to the students' identity formation. In summary, I suggest that the different discourses can open up new ways to interpret chemistry and perhaps dismantle the hegemonic chemistry discourse.

  9. Research on structure of Cu2ZnSn(S, Se)4 thin films with high Sn-related phases

    Science.gov (United States)

    Li, Peng-yu; Xue, Yu-ming; Liu, Hao; Xia, Dan; Song, Dian-you; Feng, Shao-jun; Sun, Hai-tao; Yu, Bing-bing; Qiao, Zai-xiang

    2016-11-01

    Cu2ZnSn(S, Se)4 (CZTSSe) thin films were deposited on flexible substrates by three evaporation processes at high temperature. The chemical compositions, microstructures and crystal phases of the CZTSSe thin films were respectively characterized by inductively coupled plasma optical emission spectrometer (ICP-OES), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman scattering spectrum. The results show that the single-step evaporation method at high temperature yields CZTSSe thin films with nearly pure phase and high Sn-related phases. The elemental ratios of Cu/(Zn+Sn)=1.00 and Zn/Sn=1.03 are close to the characteristics of stoichiometric CZTSSe. There is the smooth and uniform crystalline at the surface and large grain size at the cross section for the films, and no other phases exist in the film by XRD and Raman shift measurement. The films are no more with the Sn-related phase deficiency.

  10. A recent accretion burst in the low-mass protostar IRAS 15398-3359: ALMA imaging of its related chemistry

    CERN Document Server

    Jorgensen, Jes K; Sakai, Nami; Bergin, Edwin A; Brinch, Christian; Harsono, Daniel; Lindberg, Johan E; van Dishoeck, Ewine F; Yamamoto, Satoshi; Bisschop, Suzanne E; Persson, Magnus V

    2013-01-01

    Low-mass protostars have been suggested to show highly variable accretion rates through-out their evolution. Such changes in accretion, and related heating of their ambient envelopes, may trigger significant chemical variations on different spatial scales and from source-to-source. We present images of emission from C17O, H13CO+, CH3OH, C34S and C2H toward the low-mass protostar IRAS 15398-3359 on 0.5" (75 AU diameter) scales with the Atacama Large Millimeter/submillimeter Array (ALMA) at 340 GHz. The resolved images show that the emission from H13CO+ is only present in a ring-like structure with a radius of about 1-1.5" (150-200 AU) whereas the CO and other high dipole moment molecules are centrally condensed toward the location of the central protostar. We propose that HCO+ is destroyed by water vapor present on small scales. The origin of this water vapor is likely an accretion burst during the last 100-1000 years increasing the luminosity of IRAS 15398-3359 by a factor of 100 above its current luminosity....

  11. Chemistry, photophysics, and ultrafast kinetics of two structurally related Schiff bases containing the naphthalene or quinoline ring

    Science.gov (United States)

    Fita, P.; Luzina, E.; Dziembowska, T.; Radzewicz, Cz.; Grabowska, A.

    2006-11-01

    The two structurally related Schiff bases, 2-hydroxynaphthylidene-(8-aminoquinoline) (HNAQ) and 2-hydroxynaphthylidene-1'-naphthylamine (HNAN), were studied by means of steady-state and time resolved optical spectroscopies as well as time-dependent density functional theory (TDDFT) calculations. The first one, HNAQ, is stable as a keto tautomer in the ground state and in the excited state in solutions, therefore it was used as a model of a keto tautomer of HNAN which exists mainly in its enol form in the ground state at room temperature. Excited state intramolecular proton transfer in the HNAN molecule leads to a very weak (quantum yield of the order of 10-4) strongly Stokes-shifted fluorescence. The characteristic time of the proton transfer (about 30fs) was estimated from femtosecond transient absorption data supported by global analysis and deconvolution techniques. Approximately 35% of excited molecules create a photochromic form whose lifetime was beyond the time window of the experiment (2ns). The remaining ones reach the relaxed S1 state (of a lifetime of approximately 4ps), whose emission is present in the decay associated difference spectra. Some evidence for the back proton transfer from the ground state of the keto form with the characteristic time of approximately 13ps was also found. The energies and orbital characteristics of main electronic transitions in both molecules calculated by TDDFT method are also discussed.

  12. Highly regioselective hydride transfer, oxidative dehydrogenation, and hydrogen-atom abstraction in the thermal gas-phase chemistry of [Zn(OH)](+)/C3H8.

    Science.gov (United States)

    Wu, Xiao-Nan; Zhao, Hai-Tao; Li, Jilai; Schlangen, Maria; Schwarz, Helmut

    2014-12-28

    The thermal reactions of [Zn(OH)](+) with C3H8 have been studied by means of gas-phase experiments and computational investigation. Two types of C-H bond activation are observed in the experiment, and pertinent mechanistic features include inter alia: (i) the metal center of [Zn(OH)](+) serves as active site in the hydride transfer to generate [i-C3H7](+) as major product, (ii) generally, a high regioselectivity is accompanied by remarkable chemoselectivity: for example, the activation of a methyl C-H bond results mainly in the formation of water and [Zn(C3,H7)](+). According to computational work, this ionic product corresponds to [HZn(CH3CH=CH2)](+). Attack of the zinc center at a secondary C-H bond leads preferentially to hydride transfer, thus giving rise to the generation of [i-C3H7](+); (iii) upon oxidative dehydrogenation (ODH), liberation of CH3CH2=CH2 occurs to produce [HZn(H2O)](+). Both, ODH as well as H2O loss proceed through the same intermediate which is characterized by the fact that a methylene hydrogen atom from the substrate is transferred to the zinc and one hydrogen atom from the methyl group to the OH group of [Zn(OH)](+). The combined experimental/computational gas-phase study of C-H bond activation by zinc hydroxide provides mechanistic insight into related zinc-catalyzed large-scale processes and identifies the crucial role that the Lewis-acid character of zinc plays.

  13. Determination of Mesalamine Related Impurities from Drug Product by Reversed Phase Validated UPLC Method

    Directory of Open Access Journals (Sweden)

    Trivedi Rakshit Kanubhai

    2011-01-01

    Full Text Available In the present study gradient reversed-phase UPLC method was developed for simultaneous determination and separation of impurities and degradation products from drug product. The chromatographic separation was performed on acquity UPLC BEH C18 column (50 mm×2.1 mm, 1.7 µm using gradient elution. Other UPLC parameters which were optimised are flow rate, 0.7 mL/min; detection wavelength, 220 nm; column oven temperature, 40 °C and injection volume 7 µL. Stability indicating capability was established by forced degradation experiments and separation of known degradation products. The method was validated as per International Conference on Harmonization (ICH guideline. For all impurities and mesalamine, LOQ (limit of quantification value was found precise with RSD (related standard daviation of less than 2.0%. In essence, the present study provides an improved low detection limit and lower run time for evaluation of pharmaceutical quality of mesalamine delayed-release formulation. Moreover, the developed method was successfully applied for quantification of impurities and degradation products in mesalamine delayed-release formulation. The same method can also be used for determination of related substances from mesalamine drug substance.

  14. Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study

    Directory of Open Access Journals (Sweden)

    J. A. de Gouw

    2009-05-01

    Full Text Available Volatile organic compounds (VOCs and carbonaceous aerosol were measured at a sub-urban site near Mexico City in March of 2006 during the MILAGRO study (Megacity Initiative: Local and Global Research Objectives. Diurnal variations of hydrocarbons, elemental carbon (EC and hydrocarbon-like organic aerosol (HOA were dominated by a high peak in the early morning when local emissions accumulated in a shallow boundary layer, and a minimum in the afternoon when the emissions were diluted in a significantly expanded boundary layer and, in case of the reactive gases, removed by OH. In comparison, diurnal variations of species with secondary sources such as the aldehydes, ketones, oxygenated organic aerosol (OOA and water-soluble organic carbon (WSOC stayed relatively high in the afternoon indicating strong photochemical formation. Emission ratios of many hydrocarbon species relative to CO were higher in Mexico City than in the U.S., but we found similar emission ratios for most oxygenated VOCs and organic aerosol. Secondary formation of acetone may be more efficient in Mexico City than in the U.S., due to higher emissions of alkane precursors from the use of liquefied petroleum gas. Secondary formation of organic aerosol was similar between Mexico City and the U.S. Combining the data for all measured gas and aerosol species, we describe the budget of total observed organic carbon (TOOC, and find that the enhancement ratio of TOOC relative to CO is conserved between the early morning and mid afternoon despite large compositional changes. Finally, the influence of biomass burning is investigated using the measurements of acetonitrile, which was found to correlate with levoglucosan in the particle phase. Diurnal variations of acetonitrile indicate a contribution from local burning sources. Scatter plots of acetonitrile versus CO suggest that the contribution of biomass burning to the enhancement of most gas and aerosol species was not dominant and perhaps

  15. Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study

    Directory of Open Access Journals (Sweden)

    J. A. de Gouw

    2008-12-01

    Full Text Available Volatile organic compounds (VOCs and carbonaceous aerosol were measured at a sub-urban site near Mexico City in March of 2006 during the MILAGRO study (Megacity Initiative: Local and Global Research Objectives. Diurnal variations of hydrocarbons, elemental carbon (EC and hydrocarbon-like organic aerosol (HOA were dominated by a high peak in the early morning when local emissions accumulated in a shallow boundary layer, and a minimum in the afternoon when the emissions were diluted in a significantly expanded boundary layer and, in case of the reactive gases, removed by OH. In comparison, diurnal variations of species with secondary sources such as the aldehydes, ketones, oxygenated organic aerosol (OOA and water-soluble organic carbon (WSOC stayed relatively high in the afternoon indicating strong photochemical formation. Emission ratios of many hydrocarbon species relative to CO were higher in Mexico City than in the US, but we found similar emission ratios for most oxygenated VOCs and organic aerosol. Secondary formation of acetone may be more efficient in Mexico City than in the US, due to higher emissions of alkane precursors from the use of liquefied petroleum gas. Secondary formation of organic aerosol was similar between Mexico City and the US. Combining the data for all measured gas and aerosol species, we describe the budget of total observed organic carbon (TOOC, and find that the enhancement ratio of TOOC relative to CO is conserved between the early morning and mid afternoon despite large compositional changes. Finally, the influence of biomass burning is investigated using the measurements of acetonitrile, which was found to correlate with levoglucosan in the particle phase. Diurnal variations of acetonitrile indicate a contribution from local burning sources. Scatter plots of acetonitrile versus CO suggest that the contribution of biomass burning to the enhancement of most gas and aerosol species was not dominant and perhaps not

  16. Emission and Chemistry of Organic Carbon in the Gas and Aerosol Phase at a Sub-Urban Site Near Mexico City in March 2006 During the MILAGRO Study

    Energy Technology Data Exchange (ETDEWEB)

    de Gouw, Joost A.; Welsh-Bon, Daniel; Warneke, Carsten; Kuster, W. C.; Alexander, M. L.; Baker, Angela K.; Beyersdorf, Andreas J.; Blake, D. R.; Canagaratna, Manjula R.; Celada, A. T.; Huey, L. G.; Junkermann, W.; Onasch, Timothy B.; Salcido, A.; Sjostedt, S. J.; Sullivan, Amy; Tanner, David J.; Vargas-Ortiz, Leroy; Weber, R. J.; Worsnop, Douglas R.; Yu, Xiao-Ying; Zaveri, Rahul A.

    2009-05-28

    Volatile organic compounds (VOCs) and carbonaceous aerosol were measured at a sub-urban site near Mexico City in March of 2006 during the MILAGRO study (Megacity Initiative: Local and Global Research Objectives). Diurnal variations of hydrocarbons, elemental carbon (EC) and hydrocarbon-like organic aerosol (HOA) were dominated by a high peak in the early morning when local emissions accumulated in a shallow boundary layer, and a minimum in the afternoon when the emissions were diluted in a significantly expanded boundary layer and, in case of the reactive gases, removed by OH. In comparison, diurnal variations of species with secondary sources such as the aldehydes, ketones, oxygenated organic aerosol (OOA) and water-soluble organic carbon (WSOC) stayed relatively high in the afternoon indicating strong photochemical formation. Emission ratios of many hydrocarbon species relative to CO were higher in Mexico City than in the U.S., but we found similar emission ratios for most oxygenated VOCs and organic aerosol. Secondary formation of acetone may be more efficient in Mexico City than in the U.S., due to higher emissions of alkane precursors from the use of liquefied petroleum gas. Secondary formation of organic aerosol was similar between Mexico City and the U.S. Combining the data for all measured gas and aerosol species, we describe the budget of total observed organic carbon (TOOC), and find that the enhancement ratio of TOOC relative to CO is conserved between the early morning and mid afternoon despite large compositional changes. Finally, the influence of biomass burning is investigated using the measurements of acetonitrile, which was found to correlate with levoglucosan in the particle phase. Diurnal variations of acetonitrile indicate a contribution from local burning sources. Scatter plots of acetonitrile versus CO suggest that the contribution of biomass burning to the enhancement of most gas and aerosol species was not dominant and perhaps not dissimilar

  17. From organic chemistry to fat and oil chemistry*

    Directory of Open Access Journals (Sweden)

    Deffense Etienne

    2009-01-01

    Full Text Available With his work on animal fat and identification of fatty acids, Chevreul was a pioneer in organic chemistry. As Chevreul, I had a passion for organic chemistry too. It was then, an honour and a pleasure to present in 2008 at EFL in Athens this presentation entitled “From organic chemistry to fat and oil chemistry” because my background in organic chemistry helped me all along my professional career to understand and implement new developments related to oil and fat technology and processing. Among the topics which I worked out, I highlighted more particularly the following subjects: the degumming chemistry of oil and fat; the improvement of physical refining; a new chemical analytical tool for the dry fractionation; new development in the dry fractionation

  18. Phase Relations and Properties of Salty ices VI and VII: Implications for Solar System Ices

    Science.gov (United States)

    Daniel, I.; Manning, C. E.

    2008-12-01

    Ice VI and ice VII may be important in the interiors of Europa, Ganymede, Callisto and Titan. Oceans and interior pore waters in these bodies likely contain dissolved salts. To address the role of salt on ice VI and ice VII, we investigated phase equilibria in the system H2O -NaCl at 1 molal (5.5 wt%) NaCl in an externally heated diamond-anvil cell. Phase identifications were made by optical microscopy combined with Raman spectroscopy. Experiments were conducted at 22-150°C and up to 5 GPa by allowing the cell to thermally equilibrate at a given temperature and then varying pressure isothermally while observing phase changes. The liquidus curves of ice VI and ice VII in a 5.5 wt% NaCl solution were determined. Melting was observed from 22 to 80°C (ice VI) and from 35 to 150°C (ice VII). Both melting curves are steeper than the respective NaCl-free curves, indicating that the freezing-point depression at this bulk composition increases with pressure. The intersection of the two liquidus curves indicates that VI-VII-liquid triple point is shifted toward lower T and higher P relative to pure H2O. The 5.5 wt% NaCl bulk composition crystallizes into a single solid phase of NaCl-bearing ice VI or ice VII solid solution over the investigated T range (the subscript 'ss' indicates solid solution). Large single crystals of ice VIss or ice VIIss can also be grown by slow compression of the cell from near-liquidus conditions to the solidus. Raman spectra of these crystals clearly show zoning in these crystals. The zoning persists for days at 22°C, indicating relatively slow Na+ and Cl- diffusivity. The large depression of the freezing point in a 1 molal NaCl solution has important implications for the oceans and interiors of the icy satellites of Jupiter and Saturn. Salty fluids may remain stable to much greater depth than expected. This would promote extensive hydrothermal metamorphism of the silicate interiors. If not limited to ice VI and VII, this behavior may suppress

  19. Foods eaten by the Sichuan snub-nosed monkey (Rhinopithecus roxellana) in Shennongjia National Nature Reserve, China, in relation to nutritional chemistry.

    Science.gov (United States)

    Liu, Xuecong; Stanford, Craig B; Yang, Jingyuan; Yao, Hui; Li, Yiming

    2013-08-01

    The diet of Rhinopithecus roxellana is characterized by lichens, which are available year-round and an uncommon food source for nonhuman primates, supplemented by seasonal plant foods. We present the first study of foods eaten by R. roxellana in relation to nutritional chemistry in Shennongjia National Nature Reserve, Hubei Province, China. We analyzed the nutrients (crude protein, crude fat, and water soluble carbohydrate [WSC]) and feeding deterrents (crude fiber, condensed tannin [CT], and total phenolic [TP]) of 111 parts from 53 plant species and of 6 lichen species. Results showed that lichens were a good choice for R. roxellana living in habitats with limited and seasonally available plant foods. They contained higher concentrations of WSC than foliage, fat concentrations equivalent to those in plant parts (except fruits/seeds), and lower concentrations of fiber than mature leaves, flowers, and fruits. Although lichens were lower in protein than plant parts (except fruits), the monkeys could likely meet their protein requirement by eating seasonal plant foods rich in protein, including foliage, flowers, buds, and seeds. The monkeys were not observed to select foliage higher in protein, but appeared to select mature leaves higher in WSC and lower in fiber. Fruits were a good source of WSC and fat, and seeds were a good source of fat. Neither CT nor TP content showed negative effects on the selection of mature leaves or lichens.

  20. Simultaneous estimation of absolute and relative permeability by automatic history matching of three-phase flow production data

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, A.C.; Li, R.; Oliver, D.S. [Tulsa Univ., Tulsa, OK (United States)

    2001-06-01

    A study was conducted in petroleum engineering to determine the feasibility of estimating absolute permeability fields and parameters that define relative permeability functions by automatic history matching of production data obtained under multiphase flow conditions. A prior model is used to assume irreducible water saturation, critical gas saturation and residual oil saturations. The three-phase oil relative permeability curve was calculated from the two sets of two-phase curves using Stone's Model II. The study considered data regarding pressure, gas-oil-ratio or water-oil ratio. It was concluded that when the parameters that characterize the relative permeability functions of a reservoir are known, then it is possible to estimate the relative permeability curves and log-permeability fields by history matching production data derived under three-phase flow conditions. 30 refs., 5 tabs., 14 figs.

  1. GEM-AQ, an on-line global multiscale chemical weather system: model description and evaluation of gas phase chemistry processes

    Directory of Open Access Journals (Sweden)

    J. W. Kaminski

    2007-10-01

    Full Text Available Tropospheric chemistry and air quality processes were implemented on-line in the Global Environmental Multiscale model. The integrated model, GEM-AQ, has been developed as a platform to investigate chemical weather at scales from global to urban. The model was exercised for five years (2001–2005 to evaluate its ability to simulate seasonal variations and regional distributions of trace gases such as ozone, nitrogen dioxide and carbon monoxide on the global scale. The model results presented are compared with observations from satellites, aircraft measurement campaigns and balloon sondes.

  2. Theoretical chemistry periodicities in chemistry and biology

    CERN Document Server

    Eyring, Henry

    1978-01-01

    Theoretical Chemistry: Periodicities in Chemistry and Biology, Volume 4 covers the aspects of theoretical chemistry. The book discusses the stably rotating patterns of reaction and diffusion; the chemistry of inorganic systems exhibiting nonmonotonic behavior; and population cycles. The text also describes the mathematical modeling of excitable media in neurobiology and chemistry; oscillating enzyme reactions; and oscillatory properties and excitability of the heart cell membrane. Selected topics from the theory of physico-chemical instabilities are also encompassed. Chemists, mechanical engin

  3. A trans-phase granular continuum relation and its use in simulation

    Science.gov (United States)

    Kamrin, Ken; Dunatunga, Sachith; Askari, Hesam

    The ability to model a large granular system as a continuum would offer tremendous benefits in computation time compared to discrete particle methods. However, two infamous problems arise in the pursuit of this vision: (i) the constitutive relation for granular materials is still unclear and hotly debated, and (ii) a model and corresponding numerical method must wear ``many hats'' as, in general circumstances, it must be able to capture and accurately represent the material as it crosses through its collisional, dense-flowing, and solid-like states. Here we present a minimal trans-phase model, merging an elastic response beneath a fictional yield criterion, a mu(I) rheology for liquid-like flow above the static yield criterion, and a disconnection rule to model separation of the grains into a low-temperature gas. We simulate our model with a meshless method (in high strain/mixing cases) and the finite-element method. It is able to match experimental data in many geometries, including collapsing columns, impact on granular beds, draining silos, and granular drag problems.

  4. Phase relations and chemical vapor transport of hexagonal indium tungsten bronze In{sub x}WO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, Udo, E-mail: steiner@mw.htw-dresden.de

    2014-08-25

    Highlights: • Phase relations of hexagonal bronze In{sub x}WO{sub 3} with neighboring phases. • Chemical vapor transport experiments using NH{sub 4}Cl as transport agent. • Single crystals of In{sub x}WO{sub 3} up to a few mm in size were prepared. • Selective synthesis of crystals of the indium poor and indium rich phase boundary. - Abstract: Phase pure powder samples of hexagonal indium tungsten bronze In{sub x}WO{sub 3} (x = 0.25–0.35) were synthesized by solid state reaction at 1173 K. The phase relations of In{sub x}WO{sub 3} with neighboring binary and ternary phases were determined in the phase diagram In–W–O. Systematic chemical vapor transport experiments were carried out on source materials with compositions corresponding to miscellaneous two-phase and three-phase regions using NH{sub 4}X (X = Cl, Br, I) as transport agent. Crystals of hexagonal indium tungsten bronze were deposited beside In{sub 2}W{sub 3}O{sub 12} with composition corresponding to the indium poor phase boundary and dimensions up to a few mm in a temperature gradient 1173 K → 1073 K starting from ternary mixtures In{sub x}WO{sub 3}/In{sub 2}W{sub 3}O{sub 12}/In{sub 0.02}WO{sub 3}. Sole deposition of In{sub x}WO{sub 3} single crystals with composition x ≈ 0.33 was observed from ternary mixtures In{sub x}WO{sub 3}/W{sub 18}O{sub 49}/WO{sub 2} with a migration rate of about 0.5 mg/h (transport agent NH{sub 4}Cl)

  5. Plug Pulled on Chemistry Computer Center.

    Science.gov (United States)

    Robinson, Arthur L.

    1980-01-01

    Discusses the controversy surrounding the initial decision to establish, and the current decision to phase out, the National Resource for Computation in Chemistry (NRCC), a computational chemistry center jointly sponsored by the National Science Foundation and the Department of Energy. (CS)

  6. Review about the manganese speciation project related to neurodegeneration: An analytical chemistry approach to increase the knowledge about manganese related parkinsonian symptoms.

    Science.gov (United States)

    Michalke, Bernhard

    2016-09-01

    Neurodegenerative diseases get a growing relevance for societies. But yet the complex multi-factorial mechanisms of these diseases are not fully understood, although it is well accepted that metal ions may play a crucial role. Manganese (Mn) is a transition metal which has essential biochemical functions but from occupational exposure scenarios it appeared that Mn can cause severe neurological damage. This "two-faces"-nature of manganese initiated us to start a project on Mn-speciation, since different element species are known to exhibit different impacts on health. A summary about the step-wise developments and findings from our working group was presented during the annual conference of the German trace element society in 2015. This paper summarizes now the contribution to this conference. It is intended to provide a complete picture of the so far evolved puzzle from our studies regarding manganese, manganese speciation and metabolomics as well as Mn-related mechanisms of neural damage. Doing so, the results of the single studies are now summarized in a connected way and thus their interrelationships are demonstrated. In short terms, we found that Mn-exposure leads to an increase of low molecular weight Mn compounds, above all Mn-citrate complex, which gets even enriched across neural barriers (NB). At a Mn serum concentration between 1.5 and 1.9μg/L a carrier switch from Mn-transferrin to Mn-citrate was observed. We concluded that the Mn-citrate complex is that important Mn-carrier to NB which can be found also beyond NB in human cerebrospinal fluid (CSF) or brain of exposed rats. In brain of Mn-exposed rats manganese leads to a decreased iron (Fe) concentration, to a shift from Fe(III) to Fe(II) after long term exposure and thus to a shift toward oxidative stress. This was additionally supported by an increase of markers for oxidative stress, inflammation or lipid peroxidation at increased Mn concentration in brain extracts. Furthermore, glutamate and

  7. Early-Phase 11C-PiB PET in Amyloid Angiopathy-Related Symptomatic Cerebral Hemorrhage: Potential Diagnostic Value?

    Science.gov (United States)

    Farid, Karim; Hong, Young T; Aigbirhio, Franklin I; Fryer, Tim D; Menon, David K; Warburton, Elizabeth A; Baron, Jean-Claude

    2015-01-01

    Although late-phase (>35min post-administration) 11C-PiB-PET has good sensitivity in cerebral amyloid angiopathy (CAA), its specificity is poor due to frequently high uptake in healthy aged subjects. By detecting perfusion-like abnormalities, early-phase 11C-PiB-PET might add diagnostic value. Early-frame (1-6min) 11C-PiB-PET was obtained in 11 non-demented patients with probable CAA-related symptomatic lobar intracerebral haemorrhage (70±7yrs), 9 age-matched healthy controls (HCs) and 10 HCs PiB data did not change the sensitivity and specificity of late-phase PiB, but combined early- and late-phase positivity entails a very high suspicion of underlying Aβ-related clinical disorder, i.e., CAA or Alzheimer disease (AD). In order to clarify this ambiguity, we then show that the occipital/posterior cingulate ratio is markedly lower in CAA than in AD (N = 7). These pilot data suggest that early-phase 11C-PiB-PET may not only add to late-phase PiB-PET with respect to the unclear situation of late-phase positivity, but also help differentiate CAA from AD.

  8. Mass spectrometry. [in organic chemistry

    Science.gov (United States)

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

    1978-01-01

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

  9. Possible existence of two amorphous phases of D-mannitol related by a first-order transition

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Men; Yu, Lian, E-mail: lian.yu@wisc.edu [Department of Chemistry and School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States); Wang, Jun-Qiang; Perepezko, John H. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-06-28

    We report that the common polyalcohol D-mannitol may have two amorphous phases related by a first-order transition. Slightly above its glass transition temperature T{sub g} (284 K), the supercooled liquid (SCL) of D-mannitol transforms to a low-energy, apparently amorphous phase with stronger hydrogen bonds. The enthalpy of this so-called Phase X is approximately halfway between those of the known amorphous and crystalline phases, a position low for glass aging and high for crystal polymorphs. Similar to the SCL, Phase X is transparent with broad X-ray diffraction and Raman scattering; upon temperature cycling, it exhibits a glass-transition-like change of heat capacity. On fast heating, Phase X transforms back to the SCL near T{sub g} + 50 K, enabling a determination of their equilibrium temperature. The presence of D-sorbitol as a plasticizer enables observation of a first-order transition from the SCL to Phase X entirely in the liquid state (liquid-liquid transition). The transition from D-mannitol’s SCL to Phase X has intriguing similarities with the formation of the glacial phase of triphenyl phosphite (TPP) and the conversion from high-density to low-density amorphous ice, both studied intensely in the context of polyamorphism. All three processes occur near T{sub g} with substantial enthalpy decrease toward the crystalline phases; the processes in water and D-mannitol both strengthen the hydrogen bonds. In contrast to TPP, D-mannitol’s Phase X forms more rapidly and can transform back to the SCL. These features make D-mannitol a valuable new model for understanding polyamorphism.

  10. Surface chemistry

    CERN Document Server

    Desai, KR

    2008-01-01

    The surface Chemistry of a material as a whole is crucially dependent upon the Nature and type of surfaces exposed on crystallites. It is therefore vitally important to independently Study different, well - defined surfaces through surface analytical techniques. In addition to composition and structure of surface, the subject also provides information on dynamic light scattering, micro emulsions, colloid Stability control and nanostructures. The present book endeavour to bring before the reader that the understanding and exploitation of Solid state phenomena depended largely on the ability to

  11. Thermal relations leading to the formation of gaseous phase within the ice covering lakes and ponds

    Science.gov (United States)

    Hruba, J.; Kletetschka, G.

    2013-12-01

    When cutting the ice from the lakes and ponds gaseous phase displays often ubiquitous bubble textures along the ice thickness. The occurrence of bubbles (enclosures filled with the gas) in ice relates to a content of the dissolved gas in the lake/pond water prior to freezing over the surface. When water freezes, dissolved gases are rejected and redistributed at the ice-water interface, depending on the saturation ratio between the gas and water. If the concentration of dissolved gases surpasses a critical value (as freezing progresses), the water at the interface becomes supersaturated, and gas bubbles nucleate and grow to a visible size along the interface. The bubbles generated at the ice-water interface are either incorporated into the ice crystal as the water-ice interface advances, thus forming gas pores in the ice, or released from the interface. If there is incorporation or release is determined by several factors. The bubbles nucleated at the advancing ice-water interface may be characterized by concentration, shape, and size, which depend on growth rate of ice, the amount of gases dissolved in water, and the particulate content of water. Our work focused on the relation between growth rates of the ice and the occurrence of bubbles in the pond ice. We monitored the temperature of the ice formed under natural conditions over the pond Dolní Tušimy in Mokrovraty, Czech Republic. Distinct layers of gas bubbles were observed when the ice samples have been retrieved. These layers may relate to fast growth rates of ice. In this case the maximum growth rates were about 1 μm/s. The results were compared with similar work done (Bari and Hallett, 1974; Carte 1961; Yoshimura et al., 2008). This comparison showed distinction that may be due to different methods of ice formation (laboratory condition vs. natural conditions). References: Bari, S.A., Hallett, J. (1974): Nucleation and Growth of Bubbles at an Ice-Water Interface. Journal of Glaciology, Vol. 13, No. 69, p

  12. Chemistry and Heritage

    Science.gov (United States)

    Vittoria Barbarulo, Maria

    2014-05-01

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

  13. Phased-Array Antenna Beam Squinting Related to Frequency Dependency of Delay Circuits

    NARCIS (Netherlands)

    Garakoui, S.K.; Klumperink, E.A.M.; Nauta, B.; Vliet, F.E. van

    2011-01-01

    Practical time delay circuits do not have a perfectly linear phase-frequency characteristic. When these delay circuits are applied in a phased-array system, this frequency dependency shows up as a frequency dependent beam direction (“beam squinting”). This paper quantifies beam squinting for a linea

  14. Orofacial muscular activity and related skin movement during the preparatory and sustained phases of tone production on the French horn.

    Science.gov (United States)

    Hirano, Takeshi; Kudo, Kazutoshi; Ohtsuki, Tatsuyuki; Kinoshita, Hiroshi

    2013-07-01

    This study investigated activity of the embouchure-related orofacial muscles during pre- and postattack phases of sound production by 10 trained French-horn players. Surface electromyogram (EMG) from five selected facial muscles, and related facial skin kinematics were examined in relation to pitch and intensity of a tone produced. No difference in EMGs and facial kinematics between the two phases was found, indicating importance of appropriate formation of preattack embouchure. EMGs in all muscles during the postattack phase increased linearly with an increase in pitch, and they also increased with tone intensity without interacting with the pitch effect. Orofacial skin movement remained constant across all pitches and intensities except for lateral retraction of the lips during high-pitch tone production. Contraction of the orofacial muscles is fundamentally isometric by which tension on the lips and the cheeks is regulated for flexible sound parameter control.

  15. The clonic phase of seizures in patients treated with electroconvulsive therapy is related to age and stimulus intensity

    Directory of Open Access Journals (Sweden)

    Chih-Chieh eTseng

    2013-12-01

    Full Text Available Background: Electroconvulsive therapy (ECT is effective in the treatment of major depressive disorder and schizophrenia in patients who are drug-naïve or less-receptive to antipsychotic drugs. Several studies have discussed the correlation between patient characteristics, input current volume and seizure duration. According to the present principle of ECT guidelines, the therapeutic effect of ECT mostly correlates with seizure duration. As the tonic phase is different from the clonic phase with respect to brain function and activity, it is informative to analyse both the tonic and clonic phases. Thus, this study sought to clarify the relationship between the features of the two phases, and to re-examine and refine guidelines regarding ECT treatment.Method: ECT-course data from 44 schizophrenia patients were recollected, including the number of treatments that they had received, their gender, age, and the association of these characteristics with motor seizure duration was analysed. A two-factor correlation was employed to test the relationship between each of the two factors.Result: The meta-analysis results indicate that seizure duration and age are significantly correlated. Older patients had relatively short seizure durations after ECT-treatment. Notably, a negative correlation was only found between age and the clonic phase of the seizure, not between age and the tonic phase. Furthermore, this study also found an inverse relationship between ECT-intensity and the clonic phase, but not between ECT-intensity and the tonic phase.Conclusion: This study demonstrated that age and ECT-intensity are negatively correlated with seizure duration, particularly in the clonic phase. The present observations are not fully consistent with the basic guidelines of the APA-ECT practical manual. Accordingly, the predictions regarding the therapeutic effect of ECT can be based on both the seizure duration and the clonic phase.

  16. Atmospheric chemistry of dimethyl sulfide. Kinetics of the CH3SCH2O2 + NO2 reaction in the gas phase at 296 K

    DEFF Research Database (Denmark)

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

    1995-01-01

    The pulse radiolysis of SF6/CH3SCH3/O-2/NO2 gas mixtures was used to generate CH3SCH2O2 radicals in the presence of NO2. By monitoring the rate of NO2 decay using its absorption at 400 nm, rate constants for the reaction of CH3SCH2O2 radicals with NO2 were measured to be (9.2 +/- 0.9) x 10......(-12) and (7.1 +/- 0.9) X 10(-12) cm(3) molecule(-1) s(-1) at room temperature in 1000 and 300 mbar of SF6 diluent, respectively. Results are discussed with respect to the atmospheric chemistry of dimethyl sulfide....

  17. Cocrystal Controlled Solid-State Synthesis: A Green Chemistry Experiment for Undergraduate Organic Chemistry

    Science.gov (United States)

    Cheney, Miranda L.; Zaworotko, Michael J.; Beaton, Steve; Singer, Robert D.

    2008-01-01

    Green chemistry has become an important area of concern for all chemists from practitioners in the pharmaceutical industry to professors and the students they teach and is now being incorporated into lectures of general and organic chemistry courses. However, there are relatively few green chemistry experiments that are easily incorporated into…

  18. Phase relation of CaSO4 at high pressure and temperature up to 90 GPa and 2300 K

    Science.gov (United States)

    Fujii, Taku; Ohfuji, Hiroaki; Inoue, Toru

    2016-05-01

    Calcium sulfate (CaSO4), one of the major sulfate minerals in the Earth's crust, is expected to play a major role in sulfur recycling into the deep mantle. Here, we investigated the crystal structure and phase relation of CaSO4 up to ~90 GPa and 2300 K through a series of high-pressure experiments combined with in situ X-ray diffraction. CaSO4 forms three thermodynamically stable polymorphs: anhydrite (stable below 3 GPa), monazite-type phase (stable between 3 and ~13 GPa) and barite-type phase (stable up to at least 93 GPa). Anhydrite to monazite-type phase transition is induced by pressure even at room temperature, while monazite- to barite-type transition requires heating at least to 1500 K at ~20 GPa. The barite-type phase cannot always be quenched from high temperature and is distorted to metastable AgMnO4-type structure or another modified barite structure depending on pressure. We obtained the pressure-volume data and density of anhydrite, monazite- and barite-type phases and found that their densities are lower than those calculated from the PREM model in the studied P-T conditions. This suggests that CaSO4 is gravitationally unstable in the mantle and fluid/melt phase into which sulfur dissolves and/or sulfate-sulfide speciation may play a major role in the sulfur recycling into the deep Earth.

  19. On the relative stability of orthorhombic and hcp phases of beryllium at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Palanivel, B.; Rao, R.S.; Godwal, B.K.; Sikka, S.K. [High Pressure Physics Division, Bhabha Atomic Research Center, Mumbai (India)

    2000-10-16

    High-pressure electronic properties of Be have been investigated theoretically by means of ab initio electronic structure calculations. The calculations have been carried out by the semi-relativistic full-potential, linear muffin-tin orbital (FPLMTO) method, within the local density approximation. The crystal structure stability among the hcp, bcc and orthorhombic (distorted hcp) phases has been studied as a function of compression. The bcc structure is found to be energetically stable at pressures above 180 GPa. From the results of our calculations, the orthorhombic phase cannot occur as an intermediate phase between the ambient pressure hcp phase and the high-pressure bcc structure. Our work thus suggests the need for more accurate high-pressure x-ray data. (author)

  20. Sexual behavior in lesbian and heterosexual women: relations with menstrual cycle phase and partner availability.

    Science.gov (United States)

    Burleson, Mary H; Trevathan, Wenda R; Gregory, W Larry

    2002-05-01

    Using a prospective design over three complete menstrual cycles, 147 heterosexual and 89 lesbian women made daily recordings of their basal body temperature (BBT), cervical mucus status, menses, and completed a daily checklist of various sexual behaviors (including sexual self-stimulation and sexual activity with a partner). They also gave their age, height, weight, age at menarche, number of pregnancies, duration of sleep, tobacco, caffeine, and alcohol use, and whether they had a live-in sexual partner. Using BBT, cervical mucus status, and menses information, cycle days were grouped into five discrete phases: menses, follicular, ovulatory, early luteal, and premenstrual. Daily frequencies of sexual behavior with a partner and autosexual behavior were computed for each phase. Mixed ANOVAs on the resultant proportional data revealed similar patterns for autosexual behavior across the phases for both heterosexuals and lesbians who did not have a live-in partner, in which autosexual behavior was highest during the follicular and ovulatory phases. For those with live-in partners, autosexual behavior did not vary across the phases. Lesbians engaged in more autosexual behavior overall. Allosexual behavior peaked during the follicular phase for both heterosexuals and lesbians, and the phasic pattern was unrelated to live-in partner status. Additional analyses suggest that the observed patterns were unrelated to anticipated changes in sexual activity due to menses. Results are discussed in terms of social variables and hormonal fluctuations associated with the menstrual cycle.

  1. Relative phase of oscillations of cerebral oxy-hemoglobin and deoxy-hemoglobin concentrations during sleep

    Science.gov (United States)

    Pierro, Michele L.; Sassaroli, Angelo; Bergethon, Peter R.; Fantini, Sergio

    2012-02-01

    We present a near-infrared spectroscopy study of the instantaneous phase difference between spontaneous oscillations of cerebral deoxy-hemoglobin and oxy-hemoglobin concentrations ([Hb] and [HbO], respectively) in the low-frequency range, namely 0.04-0.12 Hz. We report phase measurements during the transitions between different sleep stages in a whole-night study of a human subject. We have found that the phase difference between [Hb] and [HbO] low-frequency oscillations tends to be greater in deep sleep (by ~96° on average) and REM sleep (by ~77° on average) compared to the awake state. In particular, we have observed progressive phase increases as the subject transitions from awake conditions into non-REM sleep stages N1, N2, and N3. Corresponding phase decreases were recorded in the reversed transitions from sleep stages N3 to N2, and N2 to awake. These results illustrate the physiological information content of phase measurements of [Hb] and [HbO] oscillations that reflect the different cerebral hemodynamic conditions of the different sleep stages, and that can find broader applicability in a wide range of near-infrared spectroscopy brain studies.

  2. Reversed-phase thin-layer chromatography of homologs of Antimycin-A and related derivatives

    Science.gov (United States)

    Abidi, Sharon L.

    1989-01-01

    Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, Ala, Alb, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins Al, A2, A3, and A4 was readily achieved with mobile phases containing acetate buffers, the separation of the new antibiotic subcomponents was highly sensitive to variation in mobile phase conditions. The type and composition of organic modifiers, the nature of buffer salts, and the concentration of added electrolytes had profound effects on capacity factors, separation factors, and peak resolution values. Of the numerous chromatographic systems examined, a mobile phase consisting of methanol-water (70:30) and 0.005 M tetrabutylammonium phosphate at pH 3.0 yielded the most satisfactory results for the separation of the subcomponents. Reversed-phase gradient HPLC separation of the dansylated or methylated antibiotic compounds produced superior chromatographic characteristics and the presence of added electrolytes was not a critical factor for achieving separation. Differences in the chromatographic outcome between homologous and structural isomers were interpretated based on a differential solvophobic interaction rationale. Preparative reversed-phase HPLC under optimal conditions enabled isolation of pure samples of the methylated antimycin subcomponents for use in structural studies.

  3. Science Update: Inorganic Chemistry

    Science.gov (United States)

    Rawls, Rebecca

    1978-01-01

    This first in a series of articles describing the state of the art of various branches of chemistry reviews inorganic chemistry, including bioinorganic, photochemistry, organometallic, and solid state chemistries. (SL)

  4. Ga, Ca, and 3d transition element (Cr through Zn) partitioning among spinel-lherzolite phases from the Lanzo massif, Italy: Analytical results and crystal chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Wogelius, R.A. [Argonne National Lab., IL (United States); Fraser, D.G. [Oxford Univ. (United Kingdom). Dept. of Earth Sciences

    1994-06-01

    Ultramafic rocks exposed in Lanzo massif, Italy is a record of mantle geochemistry, melting, sub-solidus re-equilibration. Plagioclase(+ spinel)-lherzolite samples were analyzed by Scanning Proton Microscopy, other techniques. Previous work postulated partial melting events and a two-stage sub-solidus cooling history; this paper notes Ga enrichment on spinel-clinopyroxene grain boundaries, high Ga and transition element content of spinel, and pyroxene zonation in Ca and Al. Trace element levels in olivine and orthopyroxene are also presented. Zoning trends are interpreted as due to diffusion during cooling. Olivine-clinopyroxene Cr and Ca exchange as well as clinopyroxene and spinel zonation trends indicate that the massif experienced at least two sub-solidus cooling episodes, one at 20 kbar to 1000 C and one at 8 kbar <750C. Ga levels in cores of Lanzo high-Cr spinels are high (82-66 ppM) relative to other mantle spinels (66-40 ppM), indicating enrichment. Ga content of ultramafic spinels apparently increases with Cr content; this may be due to: increased Ga solubility stemming from crystal chemical effects and/or higher Ga activities in associated silicate melts. Thus, during melting, high-Cr residual spinel may tend to buffer solid-phase Ga level. These spinels are not only rich in Ga and Cr (max 26.37 el. wt %), but also in Fe (max 21.07 el. wt %), Mn (max 3400 ppM), and Zn (max 2430 ppM). These enrichments are again due to melt extraction and partitioning into spinel structure. Low Ni (min 1050 ppM) levels are due to unsuccessful competition of Ni with Cr for octahedral structural sites caused by crystal field. Comparisons of change in partitioning vs Cr content among several 3d transition elements for spinels from Lanzo, other localities allow us to separate crystal field effects from bulk chemical effects and to show that in typical assemblages, inversion of olivine-spinel partition coefficient for Ni from <1 to >1 should occur at 11% el. wt. Cr in spinel.

  5. Astronomical chemistry.

    Science.gov (United States)

    Klemperer, William

    2011-01-01

    The discovery of polar polyatomic molecules in higher-density regions of the interstellar medium by means of their rotational emission detected by radioastronomy has changed our conception of the universe from essentially atomic to highly molecular. We discuss models for molecule formation, emphasizing the general lack of thermodynamic equilibrium. Detailed chemical kinetics is needed to understand molecule formation as well as destruction. Ion molecule reactions appear to be an important class for the generally low temperatures of the interstellar medium. The need for the intrinsically high-quality factor of rotational transitions to definitively pin down molecular emitters has been well established by radioastronomy. The observation of abundant molecular ions both positive and, as recently observed, negative provides benchmarks for chemical kinetic schemes. Of considerable importance in guiding our understanding of astronomical chemistry is the fact that the larger molecules (with more than five atoms) are all organic.

  6. Combustion chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Brown, N.J. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

  7. Proteomic analysis of Clostridium thermocellum core metabolism: relative protein expression profiles and growth phase-dependent changes in protein expression

    Directory of Open Access Journals (Sweden)

    Rydzak Thomas

    2012-09-01

    Full Text Available Abstract Background Clostridium thermocellum produces H2 and ethanol, as well as CO2, acetate, formate, and lactate, directly from cellulosic biomass. It is therefore an attractive model for biofuel production via consolidated bioprocessing. Optimization of end-product yields and titres is crucial for making biofuel production economically feasible. Relative protein expression profiles may provide targets for metabolic engineering, while understanding changes in protein expression and metabolism in response to carbon limitation, pH, and growth phase may aid in reactor optimization. We performed shotgun 2D-HPLC-MS/MS on closed-batch cellobiose-grown exponential phase C. thermocellum cell-free extracts to determine relative protein expression profiles of core metabolic proteins involved carbohydrate utilization, energy conservation, and end-product synthesis. iTRAQ (isobaric tag for relative and absolute quantitation based protein quantitation was used to determine changes in core metabolic proteins in response to growth phase. Results Relative abundance profiles revealed differential levels of putative enzymes capable of catalyzing parallel pathways. The majority of proteins involved in pyruvate catabolism and end-product synthesis were detected with high abundance, with the exception of aldehyde dehydrogenase, ferredoxin-dependent Ech-type [NiFe]-hydrogenase, and RNF-type NADH:ferredoxin oxidoreductase. Using 4-plex 2D-HPLC-MS/MS, 24% of the 144 core metabolism proteins detected demonstrated moderate changes in expression during transition from exponential to stationary phase. Notably, proteins involved in pyruvate synthesis decreased in stationary phase, whereas proteins involved in glycogen metabolism, pyruvate catabolism, and end-product synthesis increased in stationary phase. Several proteins that may directly dictate end-product synthesis patterns, including pyruvate:ferredoxin oxidoreductases, alcohol dehydrogenases, and a putative

  8. Environmental chemistry. Seventh edition

    Energy Technology Data Exchange (ETDEWEB)

    Manahan, S.E. [Univ. of Missouri, Columbia, MO (United States)

    1999-11-01

    This book presents a basic understanding of environmental chemistry and its applications. In addition to providing updated materials in this field, the book emphasizes the major concepts essential to the practice of environmental chemistry. Topics of discussion include the following: toxicological chemistry; toxicological chemistry of chemical substances; chemical analysis of water and wastewater; chemical analysis of wastes and solids; air and gas analysis; chemical analysis of biological materials and xenobiotics; fundamentals of chemistry; and fundamentals of organic chemistry.

  9. Preparation of a weak anion exchange/hydrophobic interaction dual-function mixed-mode chromatography stationary phase for protein separation using click chemistry.

    Science.gov (United States)

    Zhao, Kailou; Yang, Fan; Xia, Hongjun; Wang, Fei; Song, Qingguo; Bai, Quan

    2015-03-01

    In this study, 3-diethylamino-1-propyne was covalently bonded to the azide-silica by a click reaction to obtain a novel dual-function mixed-mode chromatography stationary phase for protein separation with a ligand containing tertiary amine and two ethyl groups capable of electrostatic and hydrophobic interaction functionalities, which can display hydrophobic interaction chromatography character in a high-salt-concentration mobile phase and weak anion exchange character in a low-salt-concentration mobile phase employed for protein separation. As a result, it can be employed to separate proteins with weak anion exchange and hydrophobic interaction modes, respectively. The resolution and selectivity of the stationary phase were evaluated in both hydrophobic interaction and ion exchange modes with standard proteins, respectively, which can be comparable to that of conventional weak anion exchange and hydrophobic interaction chromatography columns. Therefore, the synthesized weak anion exchange/hydrophobic interaction dual-function mixed-mode chromatography column can be used to replace two corresponding conventional weak anion exchange and hydrophobic interaction chromatography columns to separate proteins. Based on this mixed-mode chromatography stationary phase, a new off-line two-dimensional liquid chromatography technology using only a single dual-function mixed-mode chromatography column was developed. Nine kinds of tested proteins can be separated completely using the developed method within 2.0 h.

  10. Rhythmic neuronal synchronization in visual cortex entails spatial phase relation diversity that is modulated by stimulation and attention

    NARCIS (Netherlands)

    Maris, E.G.G.; Womelsdorf, T.; Desimone, R.; Fries, P.

    2013-01-01

    Groups of neurons tend to synchronize in distinct frequency bands. Within a given frequency band, synchronization is defined as the consistency of phase relations between site pairs, over time. This synchronization has been investigated in numerous studies and has been found to be modulated by senso

  11. Relative phase stability of bimanual and visuomanual rhythmic coordination patterns in children with a Developmental Coordination Disorder

    NARCIS (Netherlands)

    Volman, M.J.M.; Geuze, R.H.

    1998-01-01

    A dynamic pattern approach is used to examine the relative phase stability of rhythmic coordination in 24 children with a Developmental Coordination Disorder (DCD) and 24 matched controls in two functionally different tasks - a within-subject task (bimanual coordination) and a subject-environment ta

  12. Advanced Chemistry Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Description/History: Chemistry laboratory The Advanced Chemistry Laboratory (ACL) is a unique facility designed for working with the most super toxic compounds known...

  13. Science Update: Inorganic Chemistry.

    Science.gov (United States)

    Rawls, Rebecca

    1981-01-01

    Describes areas of inorganic chemistry which have changed dramatically in the past year or two, including photochemistry, electrochemistry, organometallic complexes, inorganic reaction theory, and solid state chemistry. (DS)

  14. [The analysis of the articles related to toxicological (forensic) chemistry published in the journal "Sudebno-meditsinskaya ekspertiza (Forensic Medical Expertise)" in 2004-2013. Part 1. The structure and quality of the publications].

    Science.gov (United States)

    Orlova, A M

    2015-01-01

    The elements of the scientometric survey were applied for the analysis of the character, structure, and subject-matter of the articles related to toxicological (forensic) chemistry that had been published in the journal during the period from 2004 to 2013. The data on the number of publications and their authors are presented. The emphasis is laid on the merits and demerits of the papers submitted for publications.

  15. High-Latitude Stratospheric Sensitivity to QBO Width in a Chemistry-Climate Model with Parameterized Ozone Chemistry

    Science.gov (United States)

    Hurwitz, M. M.; Braesicke, P.; Pyle, J. A.

    2010-01-01

    In a pair of idealized simulations with a simplified chemistry-climate model, the sensitivity of the wintertime Arctic stratosphere to variability in the width of the quasi-biennial oscillation (QBO) is assessed. The width of the QBO appears to have equal influence on the Arctic stratosphere as does the phase (i.e. the Holton-Tan mechanism). In the model, a wider QBO acts like a preferential shift toward the easterly phase of the QBO, where zonal winds at 60 N tend to be relatively weaker, while 50 hPa geopotential heights and polar ozone values tend to be higher.

  16. Introducing NMR to a General Chemistry Audience: A Structural-Based Instrumental Laboratory Relating Lewis Structures, Molecular Models, and [superscript 13]C NMR Data

    Science.gov (United States)

    Pulliam, Curtis R.; Pfeiffer, William F.; Thomas, Alyssa C.

    2015-01-01

    This paper describes a first-year general chemistry laboratory that uses NMR spectroscopy and model building to emphasize molecular shape and structure. It is appropriate for either a traditional or an atoms-first curriculum. Students learn the basis of structure and the use of NMR data through a cooperative learning hands-on laboratory…

  17. Chemistry space–time

    Directory of Open Access Journals (Sweden)

    David A. Winkler

    2015-12-01

    Full Text Available As Einstein identified so clearly, space and time are intimately related. We discuss the relationship between time and Euclidean space using spectroscopic and radioastronomical studies of interstellar chemistry as an example. Given the finite speed of light, we are clearly studying chemical reactions occurring tens of thousands of years ago that may elucidate the primordial chemistry of this planet several billion years ago. We also explore space of a different kind – chemical space, with many more dimensions than the four we associate as space–time. Vast chemical spaces also need very efficient (computational methods for their exploration to overcome this ‘curse of dimensionality’. We discuss methods by which the time to explore these new spaces can be very substantially reduced, opening the discovery useful new materials that are the key to our future.

  18. Tropical Soil Chemistry

    DEFF Research Database (Denmark)

    Borggaard, Ole K.

    and environmental protection. Tropical Soil Chemistry by Ole K. Borggaard provides an overview of the composition, occurrence, properties, processes, formation, and environmental vulnerability of various tropical soil types (using American Soil Taxonomy for classification). The processes and the external factors......A new book that is particularly relevant as tropical countries experience increased pressure on land resources to improve agricultural production. To ensure sustainable land use, the potentials and limitations of different kinds of tropical soils must be known in relation to crop production...... soil chemical issues are also presented to assess when, why, and how tropical soils differ from soils in other regions. This knowledge can help agricultural specialists in the tropics establish sustainable crop production. Readers are assumed to be familiar with basic chemistry, physics...

  19. Storylines in intercalation chemistry.

    Science.gov (United States)

    Lerf, A

    2014-07-21

    Intercalation chemistry will soon be a hundred years old. The period of greatest activity in this field of solid state chemistry and physics was from about 1970 to 1990. The intercalation reactions are defined as topotactic solid state reactions and the products--the intercalation compounds--are clearly distinguished from inclusion and interstitial compounds. After a short historical introduction emphasizing the pioneering work of Ulrich Hofmann, the central topics and concepts will be reviewed and commented on. The most important ones, in my view, are: dichalcogenide intercalation compounds, the electrochemical intercalation and the search for new battery electrodes, the physics of graphite intercalation compounds, and the staging and interstratification phenomena. The relation to other fields of actual research and the demands for forthcoming research will also be addressed.

  20. An atmospheric pressure high-temperature laminar flow reactor for investigation of combustion and related gas phase reaction systems

    Energy Technology Data Exchange (ETDEWEB)

    Oßwald, Patrick; Köhler, Markus [Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, D-70569 Stuttgart (Germany)

    2015-10-15

    A new high-temperature flow reactor experiment utilizing the powerful molecular beam mass spectrometry (MBMS) technique for detailed observation of gas phase kinetics in reacting flows is presented. The reactor design provides a consequent extension of the experimental portfolio of validation experiments for combustion reaction kinetics. Temperatures up to 1800 K are applicable by three individually controlled temperature zones with this atmospheric pressure flow reactor. Detailed speciation data are obtained using the sensitive MBMS technique, providing in situ access to almost all chemical species involved in the combustion process, including highly reactive species such as radicals. Strategies for quantifying the experimental data are presented alongside a careful analysis of the characterization of the experimental boundary conditions to enable precise numeric reproduction of the experimental results. The general capabilities of this new analytical tool for the investigation of reacting flows are demonstrated for a selected range of conditions, fuels, and applications. A detailed dataset for the well-known gaseous fuels, methane and ethylene, is provided and used to verify the experimental approach. Furthermore, application for liquid fuels and fuel components important for technical combustors like gas turbines and engines is demonstrated. Besides the detailed investigation of novel fuels and fuel components, the wide range of operation conditions gives access to extended combustion topics, such as super rich conditions at high temperature important for gasification processes, or the peroxy chemistry governing the low temperature oxidation regime. These demonstrations are accompanied by a first kinetic modeling approach, examining the opportunities for model validation purposes.

  1. Relation between flash point of a emulsfied fuel and its internal phase ratio

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Yasuhide; Hirai, Eiji; Kawara, Nobuhiro; Nakagawa, Yoshihiro

    1988-04-15

    Flash points of emulsified fuels (O/W type) were measured changing volume blending ratio of oil (internal phase ratio). As a result the following facts were revealed. (1) The testing method for flash point of petroleum products by tag closed tester regulated by JIS is inadequate for a sample of poor thermal convection such as a creamy emulsified fuel. (2) Emulsified fuel becomes creamy, when its internal phase ratio becomes more than 60 to 70 %, Such a creamy emulsified fuel is possible to catch fire at lower temperature as a whole, for it tends to get high temperature locally by flame approaching etc. This fact is important from a standpoint of safety engineering. (3) Flash point of emulsified fuel does not depend on its internal phase ratio provided that it is measured at uniform temperature, it seems to be constant. And its constant flash point is higher than of the corresponding pure fuel by a little. (8 figs, 5 refs)

  2. Ca2+-induced phase separation in the membrane of palmitate-containing liposomes and its possible relation to membrane permeabilization.

    Science.gov (United States)

    Agafonov, Alexey V; Gritsenko, Elena N; Shlyapnikova, Elena A; Kharakoz, Dmitry P; Belosludtseva, Natalia V; Lezhnev, Enrik I; Saris, Nils-Erik L; Mironova, Galina D

    2007-01-01

    A Ca(2+)-induced phase separation of palmitic acid (PA) in the membrane of azolectin unilamellar liposomes has been demonstrated with the fluorescent membrane probe nonyl acridine orange (NAO). It has been shown that NAO, whose fluorescence in liposomal membranes is quenched in a concentration-dependent way, can be used to monitor changes in the volume of lipid phase. The incorporation of PA into NAO-labeled liposomes increased fluorescence corresponding to the expansion of membrane. After subsequent addition of Ca(2+), fluorescence decreased, which indicated separation of PA/Ca(2+) complexes into distinct membrane domains. The Ca(2+)-induced phase separation of PA was further studied in relation to membrane permeabilization caused by Ca(2+) in the PA-containing liposomes. A supposition was made that the mechanism of PA/Ca(2+)-induced membrane permeabilization relates to the initial stage of Ca(2+)-induced phase separation of PA and can be considered as formation of fast-tightening lipid pores due to chemotropic phase transition in the lipid bilayer.

  3. Relative effects of enthalpy and entropy on the phase stability of equiatomic high-entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Otto, Frederik [ORNL; Yang, Ying [ORNL; Bei, Hongbin [ORNL; George, Easo P [ORNL

    2013-01-01

    High configurational entropies have been hypothesized to stabilize solid solutions in equiatomic, multi-element alloys which have attracted much attention recently as high-entropy alloys with potentially interesting properties. To evaluate the usefulness of configurational entropy as a predictor of single-phase (solid solution) stability, we prepared five new equiatomic, quinary alloys by replacing individual elements one at a time in a CoCrFeMnNi alloy that was previously shown to be single-phase [1]. An implicit assumption here is that, if any one element is replaced by another, while keeping the total number of elements constant, the configurational entropy of the alloy is unchanged; therefore, the new alloys should also be single-phase. Additionally, the substitute elements that we chose, Ti for Co, Mo or V for Cr, V for Fe, and Cu for Ni, had the same room-temperature crystal structure and comparable size/electronegativity as the elements being replaced to maximize solid solubility consistent with the Hume-Rothery rules. For comparison, the base CoCrFeMnNi alloy was also prepared. After three-day anneals at elevated temperatures, multiple phases were observed in all but the base CoCrFeMnNi alloy suggesting that, by itself, configurational entropy is generally not able to override competing driving forces that also govern phase stability. Thermodynamic analyses were carried out for each of the constituent binaries in the investigated alloys (Co-Cr, Fe-Ni, Mo-Mn, etc,). Experimental results combined with the thermodynamic analyses suggest that, in general, enthalpy and non-configurational entropy have bigger influences on phase stability in equiatomic, multi-component alloys. Only when the alloy microstructure is a single-phase, approximately ideal solid solution does the contribution of configurational entropy to the total Gibbs free energy become dominant. Thus, high configurational entropy provides a way to rationalize, after the fact, why a solid solution

  4. Columnar phases exhibited by some polycatenar ligands and a few related metal complexes

    Indian Academy of Sciences (India)

    B K Sadashiva; V A Raghunathan

    2003-08-01

    The synthesis and characterization of some polycatenar ligands which exhibit hexagonal columnar and cubic phases are reported. A pentacatenar with only four phenyl rings in the core and exhibiting a mesophase is also reported. A few copper (II) and palladium (II) complexes have been synthesized using these ligands and the mesomorphic properties exhibited by them are described. The hexagonal columnar phase exhibited by some of the complexes can be cooled down to room temperature. The mesophases have been characterized using a combination of polarized light microscopy, differential scanning calorimetry and X-ray diffraction methods.

  5. On the use of functional calculus for phase-type and related distributions

    DEFF Research Database (Denmark)

    Bladt, Mogens; Navarro, Azucena Campillo; Nielsen, Bo Friis

    2016-01-01

    of matrices. Functional calculus, which is a branch of operator theory frequently associated with complex analysis, can be applied to phase-type and matrix-exponential distributions in a rather straightforward way. In this article we provide a number of examples of how to execute the formal arguments.......The area of phase-type distributions is renowned for its ability to obtain closed form formulas or algorithmically exact solutions to many complex stochastic models. The method of functional calculus will provide an additional tool along these lines for establishing results in terms of functions...

  6. On the use of functional calculus for phase-type and related distributions

    DEFF Research Database (Denmark)

    Bladt, Mogens; Campillo Navarro, Azucena; Nielsen, Bo Friis

    of matrices. Functional calculus, which is a branch of operator theory frequently associated with complex analysis, can be applied to phase-type and matrix-exponential distributions in a rather straightforward way. In this paper we provide a number of examples on how to execute the formal arguments.......The area of phase-type distributions is renowned for its ability to obtain closed form formulas or algorithmically exact solutions to many complex stochastic models. The method of functional calculus will provide an additional tool along these lines for establishing results in terms of functions...

  7. One century of aryne chemistry.

    Science.gov (United States)

    Wenk, Hans Henning; Winkler, Michael; Sander, Wolfram

    2003-02-03

    Arynes, which are formally derived from aromatic rings by abstraction of two hydrogen atoms, have been a focus of organic chemistry for 100 years. In contrast to ortho-benzyne, which is mentioned in almost every introductory textbook on organic reaction mechanisms as a reactive intermediate of nucleophilic aromatic substitution, the meta and para isomers were regarded as rather exotic until recently. This situation has changed dramatically with the discovery of the enediyne antibiotics, a promising new class of antitumor drugs, and has aroused the interest of research groups from all branches of chemistry. Nowadays, arynes and related compounds are among the most intensively studied systems in chemistry. However, many aspects of the chemistry of these reactive intermediates are not well understood yet. In this review we outline the historical developement with an emphasis on recent progress in this challenging field of research.

  8. Effect of vanadium on structure-property relations of dual phase fe/mn/si/0.1c steels

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Alvin; Koo, J. Y.; Thomas, G.

    1981-11-01

    The role of vanadium on the structure-property relations of dual phase Fe/Mn/Si/0.1C steels has been investigated. After intercritical annealing at 800°C, the steels with and without V were either iced brine quenched or air cooled. The steels were also solution treated at 900°C and subsequently air cooled. Although V modified the resultant microstructure, especially the morphology of carbides, the corresponding mechanical properties are not significantly affected by the modified microstructures. It is concluded that V is not beneficial to such dual phase low carbon steels.

  9. Accurate relative-phase and time-delay maps all over the emission cone of hyperentangled photon source

    CERN Document Server

    Hegazy, Salem F; Badr, Yehia A; Obayya, Salah S A

    2016-01-01

    High flux of hyperentangled photons entails collecting the two-photon emission over relatively wide extent in frequency and transverse space within which the photon pairs are simultaneously entangled in multiple degrees of freedom. In this paper, we present a numerical approach to determining the spatial-spectral relative-phase and time-delay maps of hyperentangled photons all over the spontaneous parametric down conversion (SPDC) emission cone. We consider the hyperentangled-photons produced by superimposing noncollinear SPDC emissions of two crossed and coherently-pumped nonlinear crystals. We adopt a vectorial representation for all parameters of concern. This enables us to study special settings such as the self-compensation via oblique pump incidence. While rigorous quantum treatment of SPDC emission requires Gaussian state representation, in low-gain regime (like the case of the study), it is well approximated to the first order to superposition of vacuum and two-photon states. The relative phase and ti...

  10. Phase relations study on the melting and crystallization regions of the Bi-2223 high temperature superconductor

    Directory of Open Access Journals (Sweden)

    Polasek Alexander

    2004-01-01

    Full Text Available The melting and solidification behavior of Bi2Sr2Ca2Cu3 O10 (Bi-2223 precursors has been studied. Nominal compositions corresponding to excess of liquid, Ca2CuO3 and CuO have been investigated. Each sample was made by packing a precursor powder into a silver crucible, in order to approximately simulate the situation found in 2223 silver-sheathed tapes. The samples were partially melted and then slow-cooled, being quenched from different temperatures and analyzed through X-ray diffraction (XRD and scanning electron microscopy (SEM/EDS. The precursors decomposed peritectically during melting, forming liquid and solid phases. Very long plates with compositions falling in the vicinity of the 2223 primary phase field formed upon slow-cooling. The 2223 phase may have been formed and the results suggest that long grains of this phase might be obtained by melting and crystallization if the exact peritectic region and the optimum processing conditions are found.

  11. 77 FR 73586 - Further Inquiry Into Issues Related to Mobility Fund Phase II

    Science.gov (United States)

    2012-12-11

    ... requirements pertaining to oral and written presentations are set forth in 47 CFR 1.1206(b). Federal... commenters for feedback on the centroid method in light of their experience in Phase I. Should the Commission... treated as a permit-but-disclose proceeding in accordance with the ex parte rules. Persons making oral...

  12. Phase relations and hydrogenation behavior of (La1-xMgx)3Al alloys

    Institute of Scientific and Technical Information of China (English)

    LIU Yujie; ZHANG Qing'an

    2007-01-01

    The crystal structures and hydrogenation behavior of (La1-xMgx)3Al (x = 0.1, 0.2, 0.3, and 0.4) alloys were investigated.It was found that the alloys with x = 0.1 and 0.2 consist of La(Mg,Al),La,and a novel phase. The novel phase was determined as La2Al.It is shown that the amount of La2Al decreases as the Mg content increases. When x increases to 0.3,only La(Mg,Al) and a small amount of La2Al exist.When x is 0.4, La2Al phase disappears and the alloy contains both La(Mg,Al) and La(Al,Mg)2 Laves phase.The (La0.9Mg0.1)3Al and (La0.7Mg0.3)3Al alloys can be decomposed into LaH3,MgH2,and La2Al5 by the absorption of hydrogen at 473 K.

  13. Transition of COM-COP relative phase in a dynamic balance task.

    Science.gov (United States)

    Ko, Ji-Hyun; Challis, John H; Newell, Karl M

    2014-12-01

    The purpose of this study was to investigate whether the coordination between center of mass (COM) and center of pressure (COP) could be a candidate collective variable of a dynamical system that captures the organization of the multi-segmental whole body postural control system. We examined the transition of the COM-COP coordination pattern in a moving platform balance control paradigm. 10 young healthy adults stood on a moving surface of support that within a trial was sinusoidally translated in the anterior-posterior direction continuously scaling up and then down its frequency within the range from 0Hz to 3.0Hz. The COP was derived from a single force platform mounted on the moving surface of support. 4 angular joint motions (ankle, knee, hip, and neck) were measured by a 3D motion analysis system that also allowed COM to be derived. The COM-COP coordination changed from in-phase/anti-phase to anti-phase/in-phase at a certain frequency of the support surface, showed hysteresis as a function of the direction of frequency change and higher variability at the transition region. Conversely, the transition of the ankle-hip coordination consistently occurred at 0.3Hz across subjects with little between or within subject variability as a function of transition frequency and before the COM-COP transition. The findings provide evidence that: (1) the transition of the COM-COP coordination pattern is that of a non-equilibrium phase transition with critical fluctuations and hysteresis; and (2) that COM-COP coupling is a candidate collective variable of the multi-segmental whole body postural control system acting on a redundant postural task.

  14. A model of the gas-phase chemistry of boron nitride CVC from BCl{sub 3} and NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, M.D.; Melius, C.F.; Osterheld, T.H.

    1995-12-01

    The kinetics of gas-phase reactions occurring during the CVD of boron nitride (BN) from BCl{sub 3} and NH{sub 3} are investigated using an elementary reaction mechanism whose rate constants were obtained from theoretical predictions and literature sources. Plug-flow calculations using this mechanism predict that unimolecular decomposition of BCl{sub 3} is not significant under typical CVD conditions, but that some NH{sub 3} decomposition may occur, especially for deposition occurring at atmospheric pressure. Reaction of BCl{sub 3} with NH{sub 3} is rapid under CVD conditions and yields species containing both boron and nitrogen. One of these compounds, Cl{sub 2}BNH{sub 2}, is predicted to be a key gas-phase precursor to BN.

  15. Application of WRF/Chem over the Continental U.S. under the AQMEII Phase II: Part 2. Evaluation of 2010 Application and Responses of Air Quality and Meteorology-Chemistry Interactions to Changes in Emissions and Meteorology from 2006 to 2010

    Science.gov (United States)

    The Weather Research and Forecasting model with Chemistry (WRF/Chem) simulation with the 2005 Carbon Bond (CB05) gas-phase mechanism coupled to the Modal for Aerosol Dynamics for Europe (MADE) and the Volatility Basis Set (VBS) approach for secondary organic aerosol (SOA) (MADE/V...

  16. Atmospheric chemistry of trans-CF3CH=CHCl: Kinetics of the gas-phase reactions with Cl atoms, OH radicals, and O3

    DEFF Research Database (Denmark)

    Andersen, Mads Peter Sulbaek; Nilsson, Elna Johanna Kristina; Nielsen, Ole John;

    2008-01-01

    Long path length Fourier transform infrared (FTIR)–smog chamber techniques were used to study the kinetics of the gas-phase reactions of Cl atoms, OH radicals and O3 with trans-3,3,3-trifluoro-1-chloropropene, t-CF3CH CHCl, in 700 Torr total pressure at 295±2K. Values of k(Cl + t-CF3CH CHCl) = (5...

  17. 3.6 and 4.5 Micron Phase Curves and Evidence for Non-Equilibrium Chemistry in the Atmosphere of Extrasolar Planet HD 189733b

    CERN Document Server

    Knutson, Heather A; Fortney, Jonathan J; Burrows, Adam; Showman, Adam P; Cowan, Nicolas B; Agol, Eric; Aigrain, Suzanne; Charbonneau, David; Deming, Drake; Desert, Jean-Michel; Henry, Gregory W; Langton, Jonathan; Laughlin, Gregory

    2012-01-01

    We present new, full-orbit observations of the infrared phase variations of the canonical hot Jupiter HD 189733b obtained in the 3.6 and 4.5 micron bands using the Spitzer Space Telescope. When combined with previous phase curve observations at 8.0 and 24 micron, these data allow us to characterize the exoplanet's emission spectrum as a function of planetary longitude. We utilize improved methods for removing the effects of intrapixel sensitivity variations and accounting for the presence of time-correlated noise in our data. We measure a phase curve amplitude of 0.1242% +/- 0.0061% in the 3.6 micron band and 0.0982% +/- 0.0089% in the 4.5 micron band. We find that the times of minimum and maximum flux occur several hours earlier than predicted for an atmosphere in radiative equilibrium, consistent with the eastward advection of gas by an equatorial super-rotating jet. The locations of the flux minima in our new data differ from our previous observations at 8 micron, and we present new evidence indicating tha...

  18. Beneficial Effects of Delayed Opening the Infarct -related Artery on Late Phase Left Ventricular Function in Acute Anterior Myocardial Infarction

    Institute of Scientific and Technical Information of China (English)

    Ma Likun; Yu Hua; Huang Xiangyang; Chu Jun; Feng Kefu; Ding Xiaomei; Yan Ji; Gu Tongyuan

    2004-01-01

    Objectives To assess the effect of delayed opening the infarct - related artery(IRA) by percutanous coronary intervention (PCI) on the late phase left ventricular function after acute anterior myocardial infarction. Methods 64 patients with initial Q -wave anterior myocardial infarction and the infarct- related arteries were total occluded conformed by angiogram at 2 to 14 days after onset were divided into successful PCI group and control group (not receiving PCI or the IRA not re - opened). 2 - DE was performed at early phase ( about 3 weeks) , 2 and 6months after onset of AMI respectively to detect the left ventricular function and left ventricular wall motion abnormality (VWMA). The total congestive heart failure events were recorded during 6 months follow-up. Results VWMA scores, left ventricular ejection fraction (LVEF), left ventricular end - diastolic and end-systolic volume indices (LVEDVI and LVDSVI)were similar in 2 groups at early phase and 2 months.There were no differences between early phase and 2months in each group too. VWMA scores and LVEF did not changed at 6 months in each group compared with the early phase and 2 months (P > 0.05 ). But LVEDVI and LVESVI were significantly smaller in the successful PCI group than in the control group (P <0.01,P < 0. 05 ). The congestive heart failure events were taken place in 19% of patients in control group compared with 2% in successful PCI group ( P > 0.05 ).Conclusions Although the infarct size does not changed, delayed opening the IRA has beneficial effect to the late phase left ventricular dilatation after acute anterior myocardial infarction.

  19. Rheology and phase behavior of aggregating emulsions related to droplet-droplet interactions

    Directory of Open Access Journals (Sweden)

    C. L. A. Berli

    2007-06-01

    Full Text Available The present work deals with the relationship between colloidal interactions and physical properties of emulsions, in particular rheology and gel transition. Experimental data on protein-stabilized oil-in-water emulsions are considered. In this system, the excess of protein in the aqueous phase yields reversible droplet aggregation by the mechanism of depletion. Thus both phase and flow behaviors can be controlled by changing protein concentration, ionic strength and temperature. Calculations of the potential of interaction between droplets are carried out in the framework of colloid science. Particular emphasis is placed on the role that droplet-droplet interaction plays in defining the morphology of the aggregates, hence the microstructure and finally, the bulk physical properties. This understanding offers new perspectives in the study of complex food systems.

  20. Chemistry with methane: concepts rather than recipes.

    Science.gov (United States)

    Schwarz, Helmut

    2011-10-17

    Four seemingly simple transformations related to the chemistry of methane will be addressed from mechanistic and conceptual points of view: 1) metal-mediated dehydrogenation to form metal carbene complexes, 2) the hydrogen-atom abstraction step in the oxidative dimerization of methane, 3) the mechanisms of the CH(4)→CH(3)OH conversion, and 4) the initial bond scission (C-H vs. O-H) as well as the rate-limiting step in the selective CH(3)OH→CH(2)O oxidation. State-of-the-art gas-phase experiments, in conjunction with electronic-structure calculations, permit identification of the elementary reactions at a molecular level and thus allow us to unravel detailed mechanistic aspects. Where appropriate, these results are compared with findings from related studies in solution or on surfaces.

  1. Two-Dimensional Variational Analysis of Near-Surface Moisture from Simulated Radar Refractivity-Related Phase Change Observations

    Institute of Scientific and Technical Information of China (English)

    Ken-ichi SHIMOSE; Ming XUE; Robert D.PALMER; Jidong GAO; Boon Leng CHEONG; David J.BODINE

    2013-01-01

    Because they are most sensitive to atmospheric moisture content,radar refractivity observations can provide high-resolution information about the highly variable low-level moisture field.In this study,simulated radar refractivity-related phase-change data were created using a radar simulator from realistic high-resolution model simulation data for a dryline case.These data were analyzed using the 2DVAR system developed specifically for the phase-change data.Two sets of experiments with the simulated observations were performed,one assuming a uniform target spacing of 250 m and one assuming nonuniform spacing between 250 m to 4 km.Several sources of observation error were considered,and their impacts were examined.They included errors due to ground target position uncertainty,typical random errors associated with radar measurements,and gross error due to phase wrapping.Without any additional information,the 2DVAR system was incapable of dealing with phase-wrapped data directly.When there was no phase wrapping in the data,the 2DVAR produced excellent analyses,even in the presence of both position uncertainty and random radar measurement errors.When a separate pre-processing step was applied to unwrap the phase-wrapped data,quality moisture analyses were again obtained,although the analyses were smoother due to the reduced effective resolution of the observations by interpolation and smoothing involved in the unwrapping procedure.The unwrapping procedure was effective even when significant differences existed between the analyzed state and the state at a reference time.The results affirm the promise of using radar refractivity phase-change measurements for near-surface moisture analysis.

  2. A Demonstration of the Continuous Phase (Second-Order) Transition of a Binary Liquid System in the Region around Its Critical Point

    Science.gov (United States)

    Johnson, Michael R.

    2006-01-01

    In most general chemistry and introductory physical chemistry classes, critical point is defined as that temperature-pressure point on a phase diagram where the liquid-gas interface disappears, a phenomenon that generally occurs at relatively high temperatures or high pressures. Two examples are: water, with a critical point at 647 K (critical…

  3. Water quality in the vicinity of Mosquito Creek Lake, Trumbull County, Ohio, in relation to the chemistry of locally occurring oil, natural gas, and brine

    Science.gov (United States)

    Barton, G.J.; Burruss, R.C.; Ryder, R.T.

    1998-01-01

    Environmental samples collected in the Mosquito Creek Lake area were used to characterize water quality in relation to the chemistry of locally occurring oil, natural gas, and brine and to establish baseline water quality. Mosquito Creek Lake (a manmade reservoir) and the shallow bedrock aquifers near the lake are major sources of potable water in central Trumbull County. The city of Warren relies on the lake as a sole source of potable water. Some of the lake bottom may be in direct hydraulic connection with the underlying aquifers. The city of Cortland, along the southeastern shore of the lake, relies on the Cussewago Sandstone aquifer as a sole source of potable water. This aquifer subcrops beneath the glacio-fluvial sediments that underlie the lake. Nearly all residential homes around the lake, with the exception of homes in the city of Cortland, rely on domestic supply wells as a source of potable water. Oil and natural gas exploration and production have been ongoing in the Mosquito Creek Lakearea since the discovery of the historic Mecca Oil Pool in the Mississippian Berea and Cussewago Sandstones in 1860. Since the late 1970' s, the major drilling objective and zone of production is the Lower Silurian Clinton sandstone. The oil and natural gas resources of the Mosquito Creek Lake area, including reservoir pressure, production history, and engineering and abandonment practices are described in this report. The chemical and isotopic characteristics of the historic Mecca oil and natural gas are very different than those of the Clinton sandstone oil and natural gas. Gas chromatograms show that Mecca oil samples are extensively altered by biodegradation, whereas Clinton sandstone oils are not. Extensive alteration of Mecca oil is consistent with their occurrence at very shallow depths (less than 100 ft below land surface) where microbial activity can affect their composition. Also, the carbon-isotope composition of dissolved methane gas from Berea and Cussewago

  4. Teaching social responsibility in analytical chemistry.

    Science.gov (United States)

    Valcárcel, M; Christian, G D; Lucena, R

    2013-07-02

    Analytical chemistry is key to the functioning of a modern society. From early days, ethics in measurements have been a concern and that remains today, especially as we have come to rely more on the application of analytical science in many aspects of our lives. The main aim of this Feature is to suggest ways of introducing the topic of social responsibility and its relation to analytical chemistry in undergraduate or graduate chemistry courses.

  5. Characterization of TATP gas phase product ion chemistry via isotope labeling experiments using ion mobility spectrometry interfaced with a triple quadrupole mass spectrometer.

    Science.gov (United States)

    Tomlinson-Phillips, Jill; Wooten, Alfred; Kozole, Joseph; Deline, James; Beresford, Pamela; Stairs, Jason

    2014-09-01

    Identification of the fragment ion species associated with the ion reaction mechanism of triacetone triperoxide (TATP), a homemade peroxide-based explosive, is presented. Ion mobility spectrometry (IMS) has proven to be a key analytical technique in the detection of trace explosive material. Unfortunately, IMS alone does not provide chemical identification of the ions detected; therefore, it is unknown what ion species are actually formed and separated by the IMS. In IMS, ions are primarily characterized by their drift time, which is dependent on the ion׳s mass and molecular cross-section; thus, IMS as a standalone technique does not provide structural signatures, which is in sharp contrast to the chemical and molecular information that is generally obtained from other customary analytical techniques, such as NMR, Raman and IR spectroscopy and mass spectrometry. To help study the ion chemistry that gives rise to the peaks observed in IMS, the hardware of two different commercial IMS instruments has been directly coupled to triple quadrupole (QQQ) mass spectrometers, in order to ascertain each ion׳s corresponding mass/charge (m/z) ratios with different dopants at two temperatures. Isotope labeling was then used to help identify and confirm the molecular identity of the explosive fragment and adduct ions of TATP. The m/z values and isotope labeling experiments were used to help propose probable molecular formulas for the ion fragments. In this report, the fragment and adduct ions m/z 58 and 240 of TATP have been confirmed to be [C3H6NH·H](+) and [TATP·NH4](+), respectively; while the fragment ions m/z 73 and 89 of TATP are identified as having the molecular formulas [C4H9NH2](+) and [C4H9O2](+), respectively. It is anticipated that the work in this area will not only help to facilitate improvements in mobility-based detection (IMS and MS), but also aid in the development and optimization of MS-based detection algorithms for TATP.

  6. Structural properties and relative stability of (meta)stable ordered, partially ordered, and disordered Al-Li alloy phases

    Science.gov (United States)

    Alam, Aftab; Johnson, D. D.

    2012-04-01

    We resolve issues that have plagued reliable prediction of relative phase stability for solid solutions and compounds. Due to its commercially important phase diagram, we showcase the Al-Li system because historically density-functional theory (DFT) results show large scatter and limited success in predicting the structural properties and stability of solid solutions relative to ordered compounds. Using recent advances in an optimal basis-set representation of the topology of electronic charge density (and, hence, atomic size), we present DFT results that agree reasonably well with all known experimental data for the structural properties and formation energies of ordered, off-stoichiometric partially ordered, and disordered alloys, opening the way for reliable study in complex alloys.

  7. [Separation of zoledronic acid and its related substances by ion-pair reversed-phase high performance liquid chromatography].

    Science.gov (United States)

    Zhang, Xiaoqing; Jiang, Ye; Xu, Zhiru

    2004-07-01

    A rapid and simple ion-pair reversed-phase high performance liquid chromatographic method (HPLC) has been established for the routine analysis of zoledronic acid and its related substances. The chromatographic conditions were optimized based on the satisfactory separation of zoledronic acid from imidazol-1-ylacetic acid, their retention times and peak shape. The excellent separation of zoledronic acid from its related substances, including the remaining imidazol-1-ylacetic acid used in the synthesis of zoledronic acid and other impurities of oxidation and decomposition, was achieved within 9 min on a Hypersil C8 column with UV detection at 220 nm. The mobile phase was a mixture of methanol (20%) and 5 mmo/L phosphate buffer (80%) that contains 6 mmol/L tetrabutylammonium bromide. The resolution factor of zoledronic acid from its adjacent peak was more than 2.5. This is a simple and rapid method for the routine assay of zoledronic acid.

  8. Theme-Based Bidisciplinary Chemistry Laboratory Modules

    Science.gov (United States)

    Leber, Phyllis A.; Szczerbicki, Sandra K.

    1996-12-01

    A thematic approach to each of the two introductory chemistry laboratory sequences, general and organic chemistry, not only provides an element of cohesion but also stresses the role that chemistry plays as the "central science" and emphasizes the intimate link between chemistry and other science disciplines. Thus, in general chemistry the rubric "Environmental Chemistry" affords connections to the geosciences, whereas experiments on the topic of "Plant Assays" bridge organic chemistry and biology. By establishing links with other science departments, the theme-based laboratory experiments will satisfy the following multidisciplinary criteria: (i) to demonstrate the general applicability of core methodologies to the sciences, (ii) to help students relate concepts to a broader multidisciplinary context, (iii) to foster an attitude of both independence and cooperation that can transcend the teaching laboratory to the research arena, and (iv) to promote greater cooperation and interaction between the science departments. Fundamentally, this approach has the potential to impact the chemistry curriculum significantly by including student decision-making in the experimental process. Furthermore, the incorporation of GC-MS, a powerful tool for separation and identification as well as a state-of-the-art analytical technique, in the modules will enhance the introductory general and organic chemistry laboratory sequences by making them more instrument-intensive and by providing a reliable and reproducible means of obtaining quantitative analyses. Each multifaceted module has been designed to meet the following criteria: (i) a synthetic protocol including full spectral characterization of products, (ii) quantitative and statistical analyses of data, and (iii) construction of a database of results. The database will provide several concrete functions. It will foster the idea that science is a continuous incremental process building on the results of earlier experimentalists

  9. Structure and chemistry of the heteronuclear oxo-cluster [VPO4]•+: a model system for the gas-phase oxidation of small hydrocarbons.

    Science.gov (United States)

    Dietl, Nicolas; Wende, Torsten; Chen, Kai; Jiang, Ling; Schlangen, Maria; Zhang, Xinhao; Asmis, Knut R; Schwarz, Helmut

    2013-03-06

    The heteronuclear oxo-cluster [VPO4](•+) is generated via electrospray ionization and investigated with respect to both its electronic structure as well as its gas-phase reactivity toward small hydrocarbons, thus permitting a comparison to the well-known vanadium-oxide cation [V2O4](•+). As described in previous studies, the latter oxide exhibits no or just minor reactivity toward small hydrocarbons, such as CH4, C2H6, C3H8, n-C4H10, and C2H4, while substitution of one vanadium by a phosphorus atom yields the reactive [VPO4](•+) ion; the latter brings about oxidative dehydrogenation (ODH) of saturated hydrocarbons, e.g., propane and butane as well as oxygen-atom transfer (OAT) to unsaturated hydrocarbons, e.g. ethene, at thermal conditions. Further, the gas-phase structure of [VPO4](•+) is determined by IR photodissociation spectroscopy and compared to that of [V2O4](•+). DFT calculations help to elucidate the reaction mechanism. The results underline the crucial role of phosphorus in terms of C-H bond activation of hydrocarbons by mixed VPO clusters.

  10. Progress in Theories and Applications on the Chemistry of Photoacoustic Phase%光声位相理论及其在化学中的应用研究进展

    Institute of Scientific and Technical Information of China (English)

    伍荣护; 苏庆德

    2001-01-01

    Photoacoustic phase is an important part of the photoacoustic spectroscopy (PAS).It contains valuable information. A study on it may acquire information that can not be obtained from other spectroscopy even from the photoacoustic amplitude. Photoacoustic phase shows the special ability of measuring the optical and thermal properties, studying the nonradiative relaxation processes and analyzing the depth profile of the sample and so on. In this paper, combined with the recent research at our lab and based on the theories of photoacoustic spectroscopy, the application of the theories of the photoacoustic phase to the chemistry is reviewed systematically.%光声位相作为光声光谱重要的一部分,包含着很多有价值的信息,对它的研究可以获得其它光谱甚至光声振幅谱都不能得到的信息。光声位相在测定样品的光学和热学性质、样品无辐射弛豫过程的研究以及深度剖面分析等方面显示了特有的能力。本文结合本实验室近几年的工作,在光声光谱理论的基础上,对光声位相理论及其在化学中的应用作一综述。

  11. The phase relations in the Gd-Fe-Ga ternary system at 500 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Liu, D.C. [College of Materials Science and Engineering, Shenzhen University and Shenzhen Key Laboratory of Special Functional Materials, Shenzhen 518060 (China); Li, J.Q. [College of Materials Science and Engineering, Shenzhen University and Shenzhen Key Laboratory of Special Functional Materials, Shenzhen 518060 (China)], E-mail: junqinli@szu.edu.cn; Ouyang, M.; Liu, F.S.; Ao, W.Q. [College of Materials Science and Engineering, Shenzhen University and Shenzhen Key Laboratory of Special Functional Materials, Shenzhen 518060 (China)

    2009-06-24

    The isothermal section (500 deg. C) of the phase diagram of the Gd-Fe-Ga ternary system was investigated by X-ray powder diffraction analysis. Eleven binary compounds, GdGa{sub 2}, GdGa, Gd{sub 3}Ga{sub 2}, Gd{sub 5}Ga{sub 3}, GdFe{sub 2}, GdFe{sub 3}, Gd{sub 2}Fe{sub 17}, Fe{sub 3}Ga, Fe{sub 6}Ga{sub 5}, Fe{sub 3}Ga{sub 4} and FeGa{sub 3}, have been confirmed. Two ternary compounds, GdFe{sub 5.3}Ga{sub 6.7} and GdFe{sub 5}Ga{sub 7}, were found in this ternary system at 500 deg. C. The compound GdFe{sub 5.3}Ga{sub 6.7} is orthorhombic ScFe{sub 6}Ga{sub 6}-type structure (space group Immm) with a = 0.8567 (9), b = 0.86960 (9) and c = 0.50782 (5) nm, while the compound GdFe{sub 5}Ga{sub 7} is tetragonal ThMn{sub 12}-type structure (space group I4/mmm) with a = 0.8651(1) and c = 0.50934 (6) nm. The isothermal section at 500 deg. C consists of 16 single-phase regions, 31 two-phase regions and 16 three-phase regions. The maximum solid solubilities of Ga in GdFe{sub 2}, GdFe{sub 3}, Gd{sub 2}Fe{sub 17} are 9.2, 9.0, and 44.3 at.% respectively. The homogeneity range of GdGa{sub 2} is from 22 to 33.3 at.% Ga in Gd-Ga side but the solid solubility of Fe in this compound is very small. The homogeneity range of GdFe{sub 5}Ga{sub 7} is from 53.8 to 59.2 at.% Ga. Very limited solid solutions were measured in the other compounds.

  12. Bismuthates: BaBiO{sub 3} and related superconducting phases

    Energy Technology Data Exchange (ETDEWEB)

    Sleight, Arthur W., E-mail: arthur.sleight@oregonstate.edu

    2015-07-15

    Highlights: • BaBiO{sub 3} has the perovskite structure, but tilting of the BiO{sub 6} octahedra destroy the ideal cubic symmetry except at temperatures above 820 K. BaBiO{sub 3} is a diamagnetic semiconductor due to a CDW, which is equivalent to a Ba{sub 2}Bi{sup 3+}Bi{sup 5+}O{sub 6} representation. • Recent calculations and experimental results confirm that there is no significant deviation from the oxidation states of 3+ and 5+. • Superconductivity with a T{sub c} as high as 13 K occurs for BaPb{sub 1−x}Bi{sub x}O{sub 3} phases where the 6s band is about 25% filled, and superconductivity with a T{sub c} as high as 34 K occurs for Ba{sub 1−x}K{sub x}BiO{sub 3} phases where the 6s band is about 35% filled. • These two solid solutions can have cubic, tetragonal, or orthorhombic symmetry. • However, superconductivity has only been observed when the symmetry is tetragonal. - Abstract: BaBiO{sub 3} has the perovskite structure, but tilting of the BiO{sub 6} octahedra destroy the ideal cubic symmetry except at temperatures above 820 K. BaBiO{sub 3} is a diamagnetic semiconductor due to a charge density wave (CDW), which is equivalent to a Ba{sub 2}Bi{sup 3+}Bi{sup 5+}O{sub 6} representation. Recent calculations and experimental results confirm that there is no significant deviation from the oxidation states of 3+ and 5+. Superconductivity with a T{sub c} as high as 13 K occurs for BaPb{sub 1−x}Bi{sub x}O{sub 3} phases where the 6s band is about 25% filled, and superconductivity with a T{sub c} as high as 34 K occurs for Ba{sub 1−x}K{sub x}BiO{sub 3} phases where the 6s band is about 35% filled. Structures in these two solid solutions can have cubic, tetragonal, orthorhombic, or monoclinic symmetry. However, superconductivity has only been observed when the symmetry is tetragonal.

  13. Current ADC Linker Chemistry.

    Science.gov (United States)

    Jain, Nareshkumar; Smith, Sean W; Ghone, Sanjeevani; Tomczuk, Bruce

    2015-11-01

    The list of ADCs in the clinic continues to grow, bolstered by the success of first two marketed ADCs: ADCETRIS® and Kadcyla®. Currently, there are 40 ADCs in various phases of clinical development. However, only 34 of these have published their structures. Of the 34 disclosed structures, 24 of them use a linkage to the thiol of cysteines on the monoclonal antibody. The remaining 10 candidates utilize chemistry to surface lysines of the antibody. Due to the inherent heterogeneity of conjugation to the multiple lysines or cysteines found in mAbs, significant research efforts are now being directed toward the production of discrete, homogeneous ADC products, via site-specific conjugation. These site-specific conjugations may involve genetic engineering of the mAb to introduce discrete, available cysteines or non-natural amino acids with an orthogonally-reactive functional group handle such as an aldehyde, ketone, azido, or alkynyl tag. These site-specific approaches not only increase the homogeneity of ADCs but also enable novel bio-orthogonal chemistries that utilize reactive moieties other than thiol or amine. This broadens the diversity of linkers that can be utilized which will lead to better linker design in future generations of ADCs.

  14. Productivity of japanese quails in relation to body weight at the end of the rearing phase

    Directory of Open Access Journals (Sweden)

    Javer Alves Vieira Filho

    2016-05-01

    Full Text Available Two experiments were conducted at different times with the objective of investigating how the body weight of Japanese quails at the end of the rearing period may alter the performance during the laying phase. In both experiments, the birds were distributed in five treatments according to their body weights, which were obtained at 42 and 35 days of age for the first and second experiments respectively, and the following categories were considered for said experiments: very light, light, average, heavy and very heavy. For both experiments, the treatments were distributed in a randomized block design, at eight repetitions per treatment for the first one and six for the second one, both at 18 birds per repetition. During the first experiment, sexual maturity, laying percentage, marketable egg percentage, average egg weight and egg mass, in second experiment, feed consumption, final body weight, eggs per bird present, laying percentage, average egg weight, egg mass and alimentary conversion were evaluated. The results obtained show that Japanese quails whose body weight is lower than 140 grams at 42 days of age, or lower than 120 grams at 35 days of age show significantly worse productive results during the laying phase.

  15. Phase relations and conductivity of Sr-zirconates and La-zirconates

    DEFF Research Database (Denmark)

    Poulsen, F.W.; Vanderpuil, N.

    1992-01-01

    The formation of the strontium zirconates SrZrO3, Sr4Zr3O10, Sr3Zr2O7 and Sr2ZrO4, and of the lanthanum zirconates La2Zr2O7 and La2-xYZr2O7 at 1450-degrees-C was investigated by x-ray powder diffraction and DTA. Three different routes of synthesis were tested. In the Sr-zirconate system, single...... phase orthorhombic SrZrO3 and somewhat impure, tetragonal Sr2ZrO4 were observed, whereas the formation of ordered Ruddlesden-Popper phases, SrnZrn-1O3n-2, where n = 4 and 3, could not be verified. The conductivity of La2Zr2O7 was 3.7 X 10(-6) S/cm at 750-degrees-C and 3.8 x 10(-5) S/cm at 1000-degrees......-C. The conductivity of the Sr-zirconates increases with increasing Sr/Zr ratio. Samples with a nominal composition corresponding to Sr2ZrO4 have a conductivity of 7.5 x 10(-5) and 5.9 x 10(-4) S/cm at 750 and 1000-degrees-C, respectively. For all samples one observes low activation energies for ionic conduction (0...

  16. Sustainable chemistry metrics.

    Science.gov (United States)

    Calvo-Flores, Francisco García

    2009-01-01

    Green chemistry has developed mathematical parameters to describe the sustainability of chemical reactions and processes, in order to quantify their environmental impact. These parameters are related to mass and energy magnitudes, and enable analyses and numerical diagnoses of chemical reactions. The environmental impact factor (E factor), atom economy, and reaction mass efficiency have been the most influential metrics, and they are interconnected by mathematical equations. The ecodesign concept must also be considered for complex industrial syntheses, as a part of the sustainability of manufacturing processes. The aim of this Concept article is to identify the main parameters for evaluating undesirable environmental consequences.

  17. Gas-phase structures of Pb(2+)-cationized phenylalanine and glutamic acid determined by infrared multiple photon dissociation spectroscopy and computational chemistry.

    Science.gov (United States)

    Burt, Michael B; Fridgen, Travis D

    2013-02-14

    Infrared multiple photon dissociation (IRMPD) spectroscopy in the 3200-3800 cm(-1) region was used to determine the gas-phase structures of bare and monohydrated [Pb(Phe-H)](+) and [Pb(Glu-H)](+). These experiments were supported by infrared spectra calculated at the B3LYP/6-31+G(d,p) level of theory as well as 298 K enthalpies and Gibbs energies determined using the MP2(full)/6-311++G(2d,2p)//B3LYP/6-31+G(d,p) method. The gas-phase structure of [Pb(Phe-H)](+) has Pb(2+) bound in a tridentate fashion between Phe's amine nitrogen, one oxygen of the deprotonated carboxyl group, and the aromatic ring. The IRMPD spectrum of [Pb(Glu-H)](+) can be assigned to a structure where the side chain carboxyl group is deprotonated. The structure of [Pb(Phe-H)H(2)O](+) is simply the hydrated analogue of [Pb(Phe-H)](+) where water attaches to Pb(2+) in the same hemisphere as the ligated amino acid. The spectrum of [Pb(Glu-H)H(2)O](+) could not be assigned a unique structure. The IRMPD spectrum shows features attributed to symmetric and antisymmetric O-H stretching of water and a broad band characteristic of a hydrogen bonded O-H stretching vibration. These features can only be explained by the presence of at least two isomers and agree with the computational results that predict the four lowest energy structures to be within 6 kJ mol(-1) of one another.

  18. The heterogeneous OH oxidation of palmitic acid in single component and internally mixed aerosol particles: vaporization, secondary chemistry, and the role of particle phase

    Directory of Open Access Journals (Sweden)

    V. F. McNeill

    2008-03-01

    Full Text Available We studied the OH oxidation of submicron aerosol particles consisting of pure palmitic acid (PA or thin (near monolayer coatings of PA on aqueous and effloresced inorganic salt particles. Experiments were performed as a function of particle size and OH exposure using a continuous-flow photochemical reaction chamber coupled to a chemical ionization mass spectrometer (CIMS system, for detection of gas and particle-bound organics, and a DMA/CPC for monitoring particle size distributions. The loss rate of PA observed for pure PA aerosols and PA on crystalline NaCl aerosols indicates that the OH oxidation of PA at the gas-aerosol interface is efficient. The pure PA oxidation data are well represented by a model consisting of four main processes: 1 surface-only reactions between OH and palmitic acid, 2 secondary reactions between palmitic acid and OH oxidation products, 3 volatilization of condensed-phase mass, and 4 a surface renewal process. Using this model we infer a value of γOH between 0.8 and 1. The oxidation of palmitic acid in thin film coatings of salt particles is also efficient, though the inferred γOH is lower, ranging from ~0.3 (+0.1/−0.05 for coatings on solid NaCl and ~0.05 (±0.01 on aqueous NaCl particles. These results, together with simultaneous data on particle size change and volatilized oxidation products, provide support for the ideas that oxidative aging of aliphatic organic aerosol is a source of small oxidized volatile organic compounds (OVOCs, and that OH oxidation may initiate secondary condensed-phase reactions.

  19. Crystal chemistry and phase equilibria of the CaO-½Eu2O3-CoOz system at 885 °C

    Science.gov (United States)

    Wong-Ng, W.; Laws, W.; Kaduk, J. A.

    2016-08-01

    The CaO-½Eu2O3-CoOz system prepared at 885 °C in air consists of two calcium cobaltate compounds, namely, the 2D thermoelectric oxide solid solution, (Ca3-xEux)Co4O9-z (0 ≤ x ≤ 0.5) which has a misfit layered structure, and the 1D Ca3Co2O6 compound which consists of chains of alternating CoO6 trigonal prisms and CoO6 octahedra. Ca3Co2O6 was found to be a point compound without the substitution of Eu on the Ca site when prepared at 885 °C. A solid solution region of distorted perovskite, (Eu1-xCax)CoO3-z (0 ≤ x ≤ 0.22, space group Pnma) was established. The (Eu0.91(1)Ca0.09(1))CoO3-z perovskite member has a distorted structure with tilt angles θ (17.37°), ϕ (8.20°), and ω (19.16°) which represent rotations of an octahedron about the pseudo-cubic perovskite [110]p, [001]p and [111]p axes. The reported Eu2CoO4 phase was not observed at 885 °C, but a ternary Ca-doped oxide, (Eu1+xCa1-x)CoO4-z (Bmab) where 0 ≤ x ≤ 0.10 was found to be stable at this temperature. In the peripheral binary systems, Eu was not present in the Ca site of CaO, while a small solid solution region was identified for (Eu1-xCax)O(3-z)/2 (0 ≤ x ≤ 0.05). Seven solid solution tie-line regions and six three-phase regions were determined in the CaO-½Eu2O3-CoOz system in air.

  20. Chemistry Division: Annual progress report for period ending March 31, 1987

    Energy Technology Data Exchange (ETDEWEB)

    1987-08-01

    This report is divided into the following sections: coal chemistry; aqueous chemistry at high temperatures and pressures; geochemistry of crustal processes to high temperatures and pressures; chemistry of advanced inorganic materials; structure and dynamics of advanced polymeric materials; chemistry of transuranium elements and compounds; separations chemistry; reactions and catalysis in molten salts; surface science related to heterogeneous catalysis; electron spectroscopy; chemistry related to nuclear waste disposal; computational modeling of security document printing; and special topics. (DLC)

  1. Green chemistry: A tool in Pharmaceutical Chemistry

    OpenAIRE

    Smita Talaviya; Falguni Majumdar

    2012-01-01

    Green chemistry expresses an area of research developing from scientific discoveries about pollution awareness and it utilizes a set of principles that reduces or eliminates the use or generation of hazardous substances in all steps of particular synthesis or process. Chemists and medicinal scientists can greatly reduce the risk to human health and the environment by following all the valuable principles of green chemistry. The most simple and direct way to apply green chemistry in pharmaceut...

  2. From Matter to Life:Chemistry?Chemistry!

    Institute of Scientific and Technical Information of China (English)

    Jean-Marie; LEHN

    2007-01-01

    1 Results Animate as well as inanimate matter,living organisms as well as materials,are formed of molecules and of the organized entities resulting from the interaction of molecules with each other.Chemistry provides the bridge between the molecules of inanimate matter and the highly complex molecular architectures and systems which make up living organisms. Synthetic chemistry has developed a very powerful set of methods for constructing ever more complex molecules.Supramolecular chemistry seeks to con...

  3. A non-orthogonal SVD-based decomposition for phase invariant error-related potential estimation.

    Science.gov (United States)

    Phlypo, Ronald; Jrad, Nisrine; Rousseau, Sandra; Congedo, Marco

    2011-01-01

    The estimation of the Error Related Potential from a set of trials is a challenging problem. Indeed, the Error Related Potential is of low amplitude compared to the ongoing electroencephalographic activity. In addition, simple summing over the different trials is prone to errors, since the waveform does not appear at an exact latency with respect to the trigger. In this work, we propose a method to cope with the discrepancy of these latencies of the Error Related Potential waveform and offer a framework in which the estimation of the Error Related Potential waveform reduces to a simple Singular Value Decomposition of an analytic waveform representation of the observed signal. The followed approach is promising, since we are able to explain a higher portion of the variance of the observed signal with fewer components in the expansion.

  4. The carbon chemistry of the moon.

    Science.gov (United States)

    Eglinton, G.; Maxwell, J. R.; Pillinger, C. T.

    1972-01-01

    The analysis of lunar samples has shown that the carbon chemistry of the moon is entirely different from the carbon chemistry of the earth. Lunar carbon chemistry is more closely related to cosmic physics than to conventional organic chemistry. Sources of carbon on the moon are considered, giving attention to meteorites and the solar wind. The approaches used in the analysis of the samples are discussed, taking into account the method of gas chromatography employed and procedures used by bioscience investigators in the study of the lunar fines. The presence of indigenous methane and carbide in the lunar fines was established. Reactions and processes taking place on the lunar surface are discussed.

  5. Super-stable ultrafine beta-tungsten nanocrystals with metastable phase and related magnetism.

    Science.gov (United States)

    Xiao, J; Liu, P; Liang, Y; Li, H B; Yang, G W

    2013-02-07

    Ultrafine tungsten nanocrystals (average size of 3 nm) with a metastable phase (beta-tungsten with A15 structure, β-W) have been prepared by laser ablation of tungsten in liquid nitrogen. The as-prepared metastable nanocrystals exhibited super-stablity, and can keep the same metastable structure over a period of 6 months at room temperature. This super-stability is attributed to the nanosized confinement effect of ultrafine nanocrystals. The magnetism measurements showed that the β-W nanocrystals have weak ferromagnetic properties at 2 K, which may arise from surface defects and unpaired electrons on the surface of the ultrafine nanocrystals. These findings provided useful information for the application of ultrafine β-W nanocrystals in microelectronics and spintronics.

  6. Task-and phase-related changes in cortico-muscular coherence

    DEFF Research Database (Denmark)

    Masakado, Yoshihisa; Nielsen, Jens Bo

    2008-01-01

    Cortico-muscular coherence was compared during ramp-and-hold isometric and quasi-isotonic contraction of the ankle joint in human subjects. EEG was recorded from the leg area of the motor cortex. EMG was recorded from the tibialis anterior (TA) muscle. The subjects were requested to maintain...... reappeared quickly and had the same size as at the low level of contraction. However, a significantly larger level of coherence was found during quasi-isotonic than during the isometric contraction. This demonstrates that cortico-muscular coherence in the 15-35 Hz frequency band is phase- and task...... a steady low level of dorsiflexion and at intervals of 10 s to increase the contraction level within 1 s, maintain this level for 4 s and then decrease the level of contraction again within another 1 s. In seven subjects coherence in the 15-35 Hz frequency band was seen between EEG and TA EMG during low...

  7. Combinatorial chemistry in the agrosciences.

    Science.gov (United States)

    Lindell, Stephen D; Pattenden, Lisa C; Shannon, Jonathan

    2009-06-15

    Combinatorial chemistry and high throughput screening have had a profound effect upon the way in which agrochemical companies conduct their lead discovery research. The article reviews recent applications of combinatorial synthesis in the lead discovery process for new fungicides, herbicides and insecticides. The role and importance of bioavailability guidelines, natural products, privileged structures, virtual screening and X-ray crystallographic protein structures on the design of solid- and solution-phase compound libraries is discussed and illustrated.

  8. Reversed-phase systems for the analysis of catecholamines and related compounds by high-performance liquid chromatography.

    Science.gov (United States)

    Crombeen, J P; Kraak, J C; Poppe, H

    1978-12-21

    Phase systems using alkyl-modified silica as an absorbent, used as much and as a support for dynamically coated ion exchangers, were investigated for their capability in separating catecholamines and related compounds. Simple reversed-phase adsorption chromatography with C8-bonded silica is not able to separate these compounds very well because of (i) the very small retention of the more basic compounds in circumstances where the acidic compounds are well separated, (ii) bad peak shapes and (iii) low column efficiences, although the last drawback can be circumvented by the addition of inorganic anions to the eluent. The addition of a dynamically coated cation exchanger, sodium dodecylsulphate (SDS), to the eluent not only brings about drastic changes in the selectivity, but also makes available an additional degree of freedom for influencing the selectivity. The retention of the basic solutes increases upon addition of SDS and the retention becomes inversely proportional to the counter ion (Na+) concentration. Further, it was found that columns previously loaded with SDS can be used with SDS-free eluents when a pre-column, loaded with SDS, is used or with eluents containing a very small amount of SDS (less than 0.001%, w/v). These SDS-coated phase systems behave similarly to phase systems containing SDS in the eluent and show a better column stability and UV background.

  9. Industrial ecology: Environmental chemistry and hazardous waste

    Energy Technology Data Exchange (ETDEWEB)

    Manahan, S.E. [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemistry

    1999-01-01

    Industrial ecology may be a relatively new concept -- yet it`s already proven instrumental for solving a wide variety of problems involving pollution and hazardous waste, especially where available material resources have been limited. By treating industrial systems in a manner that parallels ecological systems in nature, industrial ecology provides a substantial addition to the technologies of environmental chemistry. Stanley E. Manahan, bestselling author of many environmental chemistry books for Lewis Publishers, now examines Industrial Ecology: Environmental Chemistry and Hazardous Waste. His study of this innovative technology uses an overall framework of industrial ecology to cover hazardous wastes from an environmental chemistry perspective. Chapters one to seven focus on how industrial ecology relates to environmental science and technology, with consideration of the anthrosphere as one of five major environmental spheres. Subsequent chapters deal specifically with hazardous substances and hazardous waste, as they relate to industrial ecology and environmental chemistry.

  10. Development and validation of a reversed phase liquid chromatographic method for analysis of oxytetracycline and related impurities.

    Science.gov (United States)

    Kahsay, Getu; Shraim, Fairouz; Villatte, Philippe; Rotger, Jacques; Cassus-Coussère, Céline; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

    2013-03-05

    A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities.

  11. Coupling mechanisms in inductive discharges with RF substrate bias driven at consecutive harmonics with adjustable relative phase

    Science.gov (United States)

    Steinberger, Thomas; Berger, Birk; Schulze, Julian; Schuengel, Edmund; Koepke, Mark

    2016-09-01

    Hybrid combinations of inductive and capacitive RF discharges are commonly used for plasma etching because the inductive coupling ensures a high plasma density, while the capacitive coupling allows the control of the ion bombardment energy at the substrate. We experimentally study the coupling mechanisms between the two driving-voltage sources in such a plasma driven inductively at 13.56 MHz and capacitively at 27.12 MHz in argon and neon at low pressure. We find that the resulting DC self-bias can be controlled via the Electrical Asymmetry Effect by adjusting the relative phase between the two driving harmonics in the E-mode. Langmuir probe measurements and Phase Resolved Optical Emission Spectroscopy (PROES) reveal that the addition of the applied RF-bias in the plasma acts as a catalyst for the transition between E- and H-mode. PROES measurements generally show that the electron power absorption dynamics are affected by the relative phase between the two driving voltage waveforms and by the ratio of the inductive to the capacitive driving powers. Finally, the ion flux-energy distribution function is measured at the RF-powered electrode and found also to be affected by coupling effects.

  12. Particle-Phase Chemistry of Secondary Organic Material: Modeled Compared to Measured O:C and H:C Elemental Ratios Provide Constraints

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qi; Liu, Yingjun; Donahue, N. M.; Shilling, John E.; Martin, Scot T.

    2011-05-11

    Chemical mechanisms for the production of secondary organic material (SOM) are developed in focused laboratory studies but widely used in the complex modeling context of the atmosphere. Given this extrapolation, a stringent testing of the mechanisms is important. In addition to particle mass yield as a typical standard for model-measurement comparison, particle composition expressed as O:C and H:C elemental ratios can serve as a higher dimensional constraint. A paradigm for doing so is developed herein for SOM production from a C5 C10 C15 terpene sequence, namely isoprene, R-pinene, and β-caryopyhllene. The model MCM-SIMPOL is introduced based on the Master Chemical Mechanism (MCM v3.2) and a group contribution method for vapor pressures (SIMPOL). The O:C and H:C ratios of the SOM are measured using an Aerosol Mass Spectrometer (AMS). Detailed SOM-specific AMS calibrations for the organic contribution to the H2Oþ and COþ ions indicate that published O:C and H:C ratios for SOM are systematically too low. Overall, the measurement-model gap was small for particle mass yield but significant for particle-average elemental composition. The implication is that a key chemical pathway is missing from the chemical mechanism. The data can be explained by the particle-phase homolytic decomposition of organic hydroperoxides and subsequent alkyl-radical-promoted oligomerization.

  13. Integrating Computational Chemistry into the Physical Chemistry Curriculum

    Science.gov (United States)

    Johnson, Lewis E.; Engel, Thomas

    2011-01-01

    Relatively few undergraduate physical chemistry programs integrate molecular modeling into their quantum mechanics curriculum owing to concerns about limited access to computational facilities, the cost of software, and concerns about increasing the course material. However, modeling exercises can be integrated into an undergraduate course at a…

  14. Optical and Electronic Analysis of the Two Fluorite-Related Phases in the Ga-In-Sn-O System

    Science.gov (United States)

    Dolgonos, Alex

    Optical transparency and electrical conductivity, traditionally mutually-exclusive materials properties, are both critical for the performance of electrode materials in applications such as flat-panel displays and organic photovoltaics (OPVs). Owing to their wide band gaps which are amenable to degenerate doping, transparent conducting oxides (TCOs) are widely utilized for organic optoelectronic applications. The two fluorite-related phases in the Ga-In-Sn-O (GITO) pseudo-ternary system---Ga,Sn co-substituted bixbyite 2O3 and the so-called "T-phase" Ga3--xIn5+xSn2O 16---have the potential to overcome the issues associated with Sn-doped 2O3 (ITO) by reducing the indium content, utilizing compositions that are more stable in acidic conditions, and offering work function levels that are in better alignment with adjacent layers in organic optoelectronic devices. In this work, the composition and processing effects on the optical and electronic properties of the bixbyite phase and the T-phase in the GITO system were determined. Electronic properties were analyzed by conductivity and Seebeck coefficient measurements, and the combination of these two properties revealed carrier characteristics for these two phases. The optical band gaps of the phases were determined from absorption data by methods developed in this work, which account for the band-altering effects of doping in TCOs. The optical characterization methods were experimentally confirmed through a combination of diffuse-reflectance and photoluminescence measurements of un-doped and Sn-doped In2O3. The bixbyite phase's conductivity, Seebeck coefficient, and optical band gap are dominated by the concentration of Sn-on-In substitution defects, as expected. Remarkably, Ga substition was found to have a negligible effect on the electronic properties. A conductivity of 3000 S/cm was achieved in bulk specimens containing a relatively small Sn content of 1 atomic percent and 4.5 atomic percent Ga. Ga behaves as an

  15. Constitutional dynamic chemistry: bridge from supramolecular chemistry to adaptive chemistry.

    Science.gov (United States)

    Lehn, Jean-Marie

    2012-01-01

    Supramolecular chemistry aims at implementing highly complex chemical systems from molecular components held together by non-covalent intermolecular forces and effecting molecular recognition, catalysis and transport processes. A further step consists in the investigation of chemical systems undergoing self-organization, i.e. systems capable of spontaneously generating well-defined functional supramolecular architectures by self-assembly from their components, thus behaving as programmed chemical systems. Supramolecular chemistry is intrinsically a dynamic chemistry in view of the lability of the interactions connecting the molecular components of a supramolecular entity and the resulting ability of supramolecular species to exchange their constituents. The same holds for molecular chemistry when the molecular entity contains covalent bonds that may form and break reversibility, so as to allow a continuous change in constitution by reorganization and exchange of building blocks. These features define a Constitutional Dynamic Chemistry (CDC) on both the molecular and supramolecular levels.CDC introduces a paradigm shift with respect to constitutionally static chemistry. The latter relies on design for the generation of a target entity, whereas CDC takes advantage of dynamic diversity to allow variation and selection. The implementation of selection in chemistry introduces a fundamental change in outlook. Whereas self-organization by design strives to achieve full control over the output molecular or supramolecular entity by explicit programming, self-organization with selection operates on dynamic constitutional diversity in response to either internal or external factors to achieve adaptation.The merging of the features: -information and programmability, -dynamics and reversibility, -constitution and structural diversity, points to the emergence of adaptive and evolutive chemistry, towards a chemistry of complex matter.

  16. Rotorcraft Ditchings and Water-Related Impacts that Occurred from 1982 - 1989. Phase 2

    Science.gov (United States)

    1993-10-01

    identified. The injuries discussed are those related to survivable and significant survivable water crashes. Recall that in only a few cases was it evident...two gas generators are fired which inflate the airbags . The IBAHRS is currently being developed and fielded for U.S. Army and Marine Corps Cobra

  17. Changes in the chemical profile of cephalic salivary glands of Scaptotrigona postica (Hymenoptera, Meliponini) workers are phase related.

    Science.gov (United States)

    Poiani, Silvana B; Morgan, E David; Drijfhout, Falko P; da Cruz-Landim, Carminda

    2015-09-01

    Most advanced eusocial bees recruit their nest mates to food resources. Recent studies in Meliponini species have revealed that the cephalic salivary (labial) glands (CSGs) are responsible for the production of scent trail pheromones. Studies on CSGs have shown that changes occur in worker glandular cell morphology from emergence from brood combs until forager phase, which may be correlated to changes in the composition of the CSG secretion. However, the composition of the CSG secretion and the chemical changes that occur in it according to the worker's life phase or tasks performed are unknown for many species, including Scaptotrigona postica. In this study, the chemical profile of CSG secretion in S. postica workers was studied. Glands were taken from specimens that were newly emerged (NE), working in the brood comb area (CA) and foraging (FO), and were analyzed by gas chromatography-mass spectrometry. The results showed that the glandular secretion consists of oxygenated compounds of middle volatility (acids, alcohols, aldehydes, ketones, esters and ether), and their quantity varies among the different life phases, increasing as the individual moves from intra- to extra-colonial activities. The NE phase contained the smallest variety and quantity of compounds. Because of the variability of compounds, the CA workers were separated into three subgroups according to the chemical constitution of their secretion. Forager workers showed the largest quantity and variety of chemical compounds. The major compounds in forager gland secretion were 7-hexadecen-1-yl acetate and 5-tetradecen-1-yl acetate. Statistical analysis indicates that the chemical composition of glandular secretion is phase related.

  18. Ultrafast Synthesis and Related Phase Evolution of Mg2Si and Mg2Sn Compounds

    Science.gov (United States)

    Zhang, Qiang; Lu, Qiangbing; Yan, Yonggao; Su, Xianli; Tang, Xinfeng

    2017-02-01

    Both Mg2Si and Mg2Sn compounds were synthesized by an ultra-fast self-propagating high-temperature synthesis (SHS) method. The data regarding SHS were obtained via theoretical calculation combined with experiments, showing that the adiabatic temperature T ad and ignition temperature T ig of Mg2Si are a little higher than those of Mg2Sn. The mechanism of phase evolution and the concomitant microstructure evolution during the synthesis process of Mg2Si and Mg2Sn compounds were investigated by adopting SHS technique coupled with a sudden quenching treatment. Differential scanning calorimetry (DSC), field emission scanning electron microscopy (FESEM), and x-ray powder diffraction (XRD) results indicate that Mg2Si compound can be directly synthesized through the reaction of Mg and Si elements at around 850 K. Correspondingly, the formation of Mg2Sn needs to undergo melting of Sn and the subsequent feeble reaction between Mg and Sn elements before the large scale transformation at 730 K. As the groundwork, this research embodies great significance for future study on the ultrafast SHS process of the ternary Mg2Si1-x Sn x solid solutions.

  19. Solid Phase Microextraction and Related Techniques for Drugs in Biological Samples

    Directory of Open Access Journals (Sweden)

    Mohammad Mahdi Moein

    2014-01-01

    Full Text Available In drug discovery and development, the quantification of drugs in biological samples is an important task for the determination of the physiological performance of the investigated drugs. After sampling, the next step in the analytical process is sample preparation. Because of the low concentration levels of drug in plasma and the variety of the metabolites, the selected extraction technique should be virtually exhaustive. Recent developments of sample handling techniques are directed, from one side, toward automatization and online coupling of sample preparation units. The primary objective of this review is to present the recent developments in microextraction sample preparation methods for analysis of drugs in biological fluids. Microextraction techniques allow for less consumption of solvent, reagents, and packing materials, and small sample volumes can be used. In this review the use of solid phase microextraction (SPME, microextraction in packed sorbent (MEPS, and stir-bar sorbtive extraction (SBSE in drug analysis will be discussed. In addition, the use of new sorbents such as monoliths and molecularly imprinted polymers will be presented.

  20. Gas phase chemistry in gallium nitride CVD: Theoretical determination of the Arrhenius parameters for the first Ga-C bond homolysis of trimethylgallium.

    Science.gov (United States)

    Schmid, Rochus; Basting, Daniel

    2005-03-24

    Experimental evidence suggests that the energy of activation for the first homolytic Ga-C bond fission of GaMe3 of Ea = 249 kJ/mol, measured by Jacko and Price in a hot-wall tube reactor, is affected by surface catalytic effects. In this contribution, the rate constant for this crucial step in the gas-phase pyrolysis of GaMe3 has been calculated by variational transition state theory. By a basis set extrapolation on the MP2/cc-pVXZ level and a correlation correction from CCSD(T)/cc-pVDZ level, a theoretical "best estimate" for the bond energy of Delta H(289K) = 327.2 kJ/mol was derived. For the VTST calculation on the B3LYP/cc-pVDZ level, the energies were corrected to reproduce this bond energy. Partition functions of the transitional modes were approximated by a hindered rotor approximation to be valid along the whole reaction coordinate defined by the Ga-C bond length. On the basis of the canonical transition state theory, reaction rates were determined using the maxima of the free energy Delta G++. An Arrhenius-type rate law was fitted to these rate constants, yielding an apparent energy of activation of Ea = 316.7 kJ/mol. The preexponential factor A = 3.13 x 10(16) 1/s is an order of magnitude larger than the experimental results because of a larger release of entropy at the transition state as compared to that of the unknown surface catalyzed mechanism.

  1. Event-related EEG power modulations and phase connectivity indicate the focus of attention in an auditory own name paradigm.

    Science.gov (United States)

    Lechinger, Julia; Wielek, Tomasz; Blume, Christine; Pichler, Gerald; Michitsch, Gabriele; Donis, Johann; Gruber, Walter; Schabus, Manuel

    2016-08-01

    Estimating cognitive abilities in patients suffering from Disorders of Consciousness remains challenging. One cognitive task to address this issue is the so-called own name paradigm, in which subjects are presented with first names including the own name. In the active condition, a specific target name has to be silently counted. We recorded EEG during this task in 24 healthy controls, 8 patients suffering from Unresponsive Wakefulness Syndrome (UWS) and 7 minimally conscious (MCS) patients. EEG was analysed with respect to amplitude as well as phase modulations and connectivity. Results showed that general reactivity in the delta, theta and alpha frequency (event-related de-synchronisation, ERS/ERD, and phase locking between trials and electrodes) toward auditory stimulation was higher in controls than in patients. In controls, delta ERS and lower alpha ERD indexed the focus of attention in both conditions, late theta ERS only in the active condition. Additionally, phase locking between trials and delta phase connectivity was highest for own names in the passive and targets in the active condition. In patients, clear stimulus-specific differences could not be detected. However, MCS patients could reliably be differentiated from UWS patients based on their general event-related delta and theta increase independent of the type of stimulus. In conclusion, the EEG signature of the active own name paradigm revealed instruction-following in healthy participants. On the other hand, DOC patients did not show clear stimulus-specific processing. General reactivity toward any auditory input, however, allowed for a reliable differentiation between MCS and UWS patients.

  2. Medicinal electrochemistry: integration of electrochemistry, medicinal chemistry and computational chemistry.

    Science.gov (United States)

    Almeida, M O; Maltarollo, V G; de Toledo, R A; Shim, H; Santos, M C; Honorio, K M

    2014-01-01

    Over the last centuries, there were many important discoveries in medicine that were crucial for gaining a better understanding of several physiological processes. Molecular modelling techniques are powerful tools that have been successfully used to analyse and interface medicinal chemistry studies with electrochemical experimental results. This special combination can help to comprehend medicinal chemistry problems, such as predicting biological activity and understanding drug action mechanisms. Electrochemistry has provided better comprehension of biological reactions and, as a result of many technological improvements, the combination of electrochemical techniques and biosensors has become an appealing choice for pharmaceutical and biomedical analyses. Therefore, this review will briefly outline the present scope and future advances related to the integration of electrochemical and medicinal chemistry approaches based on various applications from recent studies.

  3. Phase Equilibria Constraints on Relations of Ore-bearing Intrusionswith Flood Basalts in the Panxi Region, Southwestern China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhaochong; HAO Yanli; AI Yu; LI Ying; ZHAO Li

    2009-01-01

    There are two types of temporally and spatially associated intrusions within the Emeishan large igneous province (LIP); namely, small uitramafic subvolcanic sills that host magmatic Cu-Ni-Platinum Group Element (PGE)-bearing sulfide deposits and large mafic layered intrusions that host giant Ti-V magnetite deposits in the Panxi region. However, except for their coeval ages, the genetic relations between the ore-bearing intrusions and extrusive rocks are poorly understood. Phase equilibria analysis (Q-PI-OI-Opx-Cpx system) has been carried out to elucidate whether ore-bearing Panzhihua, Xinjie and Limahe intrusions are co-magmatic with the picrites and flood basalts (including high-Ti, low-Ti and alkali basalts), respectively. In this system, the parental magma can be classified as silica-undersaturated olivine basalt and silica-saturated tholeiite. The equivalents of the parental magma of the Xinjie and Limahe peridotites and picrites and iow-Ti basalts are silica-undersaturated, whereas the Limahe gabbro-diorites and high-Ti basalts are silica-saturated. In contrast, the Panzhihua intrusion appears to be alkali character. Phase equilibria relations clearly show that the magmas that formed the Panzhihua intrusion and high-Ti basalts cannot be co-magmatic as there is no way to derive one liquid from another by fractional crystallization. On the other hand, the Panzhihua intrusion appears to be related to Permian alkali intrusions in the region, but does not appear to be related to the alkali basalts recognized in the Longzhoushan lava stratigraphy. Comparably, the Limabe intrusion appears to be a genetic relation to the picrites, whereas the Xinjie intrusion may be genetically related to be low-Ti basaits. Additionally, the gabbro-diorites and peridotites of the Limahe intrusion are not co-magmatic, and the former appears to be derived liquid from high-Ti basalts.

  4. Surveys of research in the Chemistry Division, Argonne National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Grazis, B.M. (ed.)

    1992-01-01

    Research reports are presented on reactive intermediates in condensed phase (radiation chemistry, photochemistry), electron transfer and energy conversion, photosynthesis and solar energy conversion, metal cluster chemistry, chemical dynamics in gas phase, photoionization-photoelectrons, characterization and reactivity of coal and coal macerals, premium coal sample program, chemical separations, heavy elements coordination chemistry, heavy elements photophysics/photochemistry, f-electron interactions, radiation chemistry of high-level wastes (gas generation in waste tanks), ultrafast molecular electronic devices, and nuclear medicine. Separate abstracts have been prepared. Accelerator activites and computer system/network services are also reported.

  5. Surveys of research in the Chemistry Division, Argonne National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Grazis, B.M. [ed.

    1992-11-01

    Research reports are presented on reactive intermediates in condensed phase (radiation chemistry, photochemistry), electron transfer and energy conversion, photosynthesis and solar energy conversion, metal cluster chemistry, chemical dynamics in gas phase, photoionization-photoelectrons, characterization and reactivity of coal and coal macerals, premium coal sample program, chemical separations, heavy elements coordination chemistry, heavy elements photophysics/photochemistry, f-electron interactions, radiation chemistry of high-level wastes (gas generation in waste tanks), ultrafast molecular electronic devices, and nuclear medicine. Separate abstracts have been prepared. Accelerator activites and computer system/network services are also reported.

  6. Global cloud and precipitation chemistry and wet deposition: tropospheric model simulations with ECHAM5/MESSy1

    Directory of Open Access Journals (Sweden)

    J. Lelieveld

    2007-05-01

    Full Text Available The representation of cloud and precipitation chemistry and subsequent wet deposition of trace constituents in global atmospheric chemistry models is associated with large uncertainties. To improve the simulated trace gas distributions we apply the new submodel SCAV, which includes detailed cloud and precipitation chemistry and present results of the atmospheric chemistry general circulation model ECHAM5/MESSy1. A good agreement with observed wet deposition fluxes for species causing acid rain is obtained. The new scheme enables prognostic calculations of the pH of clouds and precipitation, and these results are also in accordance with observations. We address the influence of detailed cloud and precipitation chemistry on trace constituents based on sensitivity simulations. The results confirm previous results from regional scale and box models, and we extend the analysis to the role of aqueous phase chemistry on the global scale. Some species are directly affected through multiphase removal processes, and many also indirectly through changes in oxidant concentrations, which in turn have an impact on the species lifetime. While the overall effect on tropospheric ozone is relatively small (3 can reach ≈20%, and several important compounds (e.g., H2O2, HCHO are substantially depleted by clouds and precipitation.

  7. Global cloud and precipitation chemistry and wet deposition: tropospheric model simulations with ECHAM5/MESSy1

    Directory of Open Access Journals (Sweden)

    H. Tost

    2007-01-01

    Full Text Available The representation of cloud and precipitation chemistry and subsequent wet deposition of trace constituents in global atmospheric chemistry models is associated with large uncertainties. To improve the simulated trace gas distributions we apply the new submodel SCAV, which includes detailed cloud and precipitation chemistry and present results of the atmospheric chemistry general circulation model ECHAM5/MESSy1. A good agreement with observed wet deposition fluxes for species causing acid rain is obtained. The new scheme enables prognostic calculations of the pH of clouds and precipitation, and these results are also in accordance with observations. We address the influence of detailed cloud and precipitation chemistry on trace constituents based on sensitivity simulations. The results confirm previous results from regional scale and box models, and we extend the analysis to the role of aqueous phase chemistry on the global scale. Some species are directly affected through multiphase removal processes, and many also indirectly through changes in oxidant concentrations, which in turn have an impact on the species lifetime. While the overall effect on tropospheric ozone is relatively small (<10%, regional effects on O3 can reach ~20%, and several important compounds (e.g., H2O2, HCHO are substantially depleted by clouds and precipitation.

  8. Green chemistry: A tool in Pharmaceutical Chemistry

    Directory of Open Access Journals (Sweden)

    Smita Talaviya

    2012-07-01

    Full Text Available Green chemistry expresses an area of research developing from scientific discoveries about pollution awareness and it utilizes a set of principles that reduces or eliminates the use or generation of hazardous substances in all steps of particular synthesis or process. Chemists and medicinal scientists can greatly reduce the risk to human health and the environment by following all the valuable principles of green chemistry. The most simple and direct way to apply green chemistry in pharmaceuticals is to utilize eco-friendly, non-hazardous, reproducible and efficient solvents and catalysts in synthesis of drug molecules, drug intermediates and in researches involving synthetic chemistry. Microwave synthesis is also an important tool of green chemistry by being an energy efficient process.

  9. Environmental chemistry: Volume A

    Energy Technology Data Exchange (ETDEWEB)

    Yen, T.F.

    1999-08-01

    This is an extensive introduction to environmental chemistry for engineering and chemical professionals. The contents of Volume A include a brief review of basic chemistry prior to coverage of litho, atmo, hydro, pedo, and biospheres.

  10. Advanced Chemistry Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Description/History: Chemistry laboratoryThe Advanced Chemistry Laboratory (ACL) is a unique facility designed for working with the most super toxic compounds known...

  11. Organometallic Chemistry of Molybdenum.

    Science.gov (United States)

    Lucas, C. Robert; Walsh, Kelly A.

    1987-01-01

    Suggests ways to avoid some of the problems students have learning the principles of organometallic chemistry. Provides a description of an experiment used in a third-year college chemistry laboratory on molybdenum. (TW)

  12. CHINESE JOURNAL OF CHEMISTRY

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@Chinese Journal of Chemistry is an international journal published in English by the Chinese Chemical Society with its editorial office hosted by Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.

  13. Auditory streaming by phase relations between components of harmonic complexes: a comparative study of human subjects and bird forebrain neurons.

    Science.gov (United States)

    Dolležal, Lena-Vanessa; Itatani, Naoya; Günther, Stefanie; Klump, Georg M

    2012-12-01

    Auditory streaming describes a percept in which a sequential series of sounds either is segregated into different streams or is integrated into one stream based on differences in their spectral or temporal characteristics. This phenomenon has been analyzed in human subjects (psychophysics) and European starlings (neurophysiology), presenting harmonic complex (HC) stimuli with different phase relations between their frequency components. Such stimuli allow evaluating streaming by temporal cues, as these stimuli only vary in the temporal waveform but have identical amplitude spectra. The present study applied the commonly used ABA- paradigm (van Noorden, 1975) and matched stimulus sets in psychophysics and neurophysiology to evaluate the effects of fundamental frequency (f₀), frequency range (f(LowCutoff)), tone duration (TD), and tone repetition time (TRT) on streaming by phase relations of the HC stimuli. By comparing the percept of humans with rate or temporal responses of avian forebrain neurons, a neuronal correlate of perceptual streaming of HC stimuli is described. The differences in the pattern of the neurons' spike rate responses provide for a better explanation for the percept observed in humans than the differences in the temporal responses (i.e., the representation of the periodicity in the timing of the action potentials). Especially for HC stimuli with a short 40-ms duration, the differences in the pattern of the neurons' temporal responses failed to represent the patterns of human perception, whereas the neurons' rate responses showed a good match. These results suggest that differential rate responses are a better predictor for auditory streaming by phase relations than temporal responses.

  14. Knot theory in modern chemistry.

    Science.gov (United States)

    Horner, Kate E; Miller, Mark A; Steed, Jonathan W; Sutcliffe, Paul M

    2016-11-21

    Knot theory is a branch of pure mathematics, but it is increasingly being applied in a variety of sciences. Knots appear in chemistry, not only in synthetic molecular design, but also in an array of materials and media, including some not traditionally associated with knots. Mathematics and chemistry can now be used synergistically to identify, characterise and create knots, as well as to understand and predict their physical properties. This tutorial review provides a brief introduction to the mathematics of knots and related topological concepts in the context of the chemical sciences. We then survey the broad range of applications of the theory to contemporary research in the field.

  15. Organic chemistry experiment

    Energy Technology Data Exchange (ETDEWEB)

    Mun, Seok Sik

    2005-02-15

    This book deals with organic chemistry experiments, it is divided five chapters, which have introduction, the way to write the experiment report and safety in the laboratory, basic experiment technic like recrystallization and extraction, a lot of organic chemistry experiments such as fischer esterification, ester hydrolysis, electrophilic aromatic substitution, aldol reaction, benzoin condensation, wittig reaction grignard reaction, epoxidation reaction and selective reduction. The last chapter introduces chemistry site on the internet and way to find out reference on chemistry.

  16. GPS phase scintillation during the geomagnetic storm of March 17, 2015: The relation to auroral electrojet currents

    DEFF Research Database (Denmark)

    Prikryl, Paul; Ghoddousi-Fard, Reza; Connors, Martin

    and magnetometers. GPS phase scintillation index is computed for L1 signal sampled at the rate of 50 Hz by specialized GPS scintillation receivers of the Expanded Canadian High Arctic Ionospheric Network (ECHAIN). To further extend the geographic coverage, the phasescintillation proxy index is obtained from......-enhanced plasma density (SED) and in the auroral oval during energetic particle precipitation events, substorms and pseudo-breakups in particular. In this paper we examine the relation to auroral electrojet currents observed by arrays of ground-based magnetometers and energetic particle precipitation observed...

  17. Quantum correlation with sandwiched relative entropies: Advantageous as order parameter in quantum phase transitions.

    Science.gov (United States)

    Misra, Avijit; Biswas, Anindya; Pati, Arun K; Sen De, Aditi; Sen, Ujjwal

    2015-05-01

    Quantum discord is a measure of quantum correlations beyond the entanglement-separability paradigm. It is conceptualized by using the von Neumann entropy as a measure of disorder. We introduce a class of quantum correlation measures as differences between total and classical correlations, in a shared quantum state, in terms of the sandwiched relative Rényi and Tsallis entropies. We compare our results with those obtained by using the traditional relative entropies. We find that the measures satisfy all the plausible axioms for quantum correlations. We evaluate the measures for shared pure as well as paradigmatic classes of mixed states. We show that the measures can faithfully detect the quantum critical point in the transverse quantum Ising model and find that they can be used to remove an unquieting feature of nearest-neighbor quantum discord in this respect. Furthermore, the measures provide better finite-size scaling exponents of the quantum critical point than the ones for other known order parameters, including entanglement and information-theoretic measures of quantum correlations.

  18. Organic chemistry on solid surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhen; Zaera, Francisco [Department of Chemistry, University of California, Riverside, CA 92521 (United States)

    2006-07-15

    Chemistry on solid surfaces is central to many areas of practical interest such as heterogeneous catalysis, tribology, electrochemistry, and materials processing. With the development of many surface-sensitive analytical techniques in the past decades, great advances have been possible in our understanding of such surface chemistry at the molecular level. Earlier studies with model systems, single crystals in particular, have provided rich information about the adsorption and reaction kinetics of simple inorganic molecules. More recently, the same approach has been expanded to the study of the surface chemistry of relatively complex organic molecules, in large measure in connection with the selective synthesis of fine chemicals and pharmaceuticals. In this report, the chemical reactions of organic molecules and fragments on solid surfaces, mainly on single crystals of metals but also on crystals of metal oxides, carbides, nitrides, phosphides, sulfides and semiconductors as well as on more complex models such as bimetallics, alloys, and supported particles, are reviewed. A scheme borrowed from the organometallic and organic chemistry literature is followed in which key examples of representative reactions are cited first, and general reactivity trends in terms of both the reactants and the nature of the surface are then identified to highlight important mechanistic details. An attempt has been made to emphasize recent advances, but key earlier examples are cited as needed. Finally, correlations between surface and organometallic and organic chemistry, the relevance of surface reactions to applied catalysis and materials functionalization, and some promising future directions in this area are briefly discussed. (author)

  19. Student academic achievement in college chemistry

    Science.gov (United States)

    Tabibzadeh, Kiana S.

    General Chemistry is required for variety of baccalaureate degrees, including all medical related fields, engineering, and science majors. Depending on the institution, the prerequisite requirement for college level General Chemistry varies. The success rate for this course is low. The purpose of this study is to examine the factors influencing student academic achievement and retention in General Chemistry at the college level. In this study student achievement is defined by those students who earned grades of "C" or better. The dissertation contains in-depth studies on influence of Intermediate Algebra as a prerequisite compared to Fundamental Chemistry for student academic achievement and student retention in college General Chemistry. In addition the study examined the extent and manner in which student self-efficacy influences student academic achievement in college level General Chemistry. The sample for this part of the study is 144 students enrolled in first semester college level General Chemistry. Student surveys determined student self-efficacy level. The statistical analyses of study demonstrated that Fundamental Chemistry is a better prerequisite for student academic achievement and student retention. The study also found that student self-efficacy has no influence on student academic achievement. The significance of this study will be to provide data for the purpose of establishing a uniform and most suitable prerequisite for college level General Chemistry. Finally the variables identified to influence student academic achievement and enhance student retention will support educators' mission to maximize the students' ability to complete their educational goal at institutions of higher education.

  20. Aqueous-phase chemistry and bactericidal effects from an air discharge plasma in contact with water: evidence for the formation of peroxynitrite through a pseudo-second-order post-discharge reaction of H2O2 and HNO2

    Science.gov (United States)

    Lukes, P.; Dolezalova, E.; Sisrova, I.; Clupek, M.

    2014-02-01

    The formation of transient species (OH·, NO2·, NO radicals) and long-lived chemical products (O3, H2O2, NO_{3}^{-} , NO_{2}^{-} ) produced by a gas discharge plasma at the gas-liquid interface and directly in the liquid was measured in dependence on the gas atmosphere (20% oxygen mixtures with nitrogen or with argon) and pH of plasma-treated water (controlled by buffers at pH 3.3, 6.9 or 10.1). The aqueous-phase chemistry and specific contributions of these species to the chemical and biocidal effects of air discharge plasma in water were evaluated using phenol as a chemical probe and bacteria Escherichia coli. The nitrated and nitrosylated products of phenol (4-nitrophenol, 2-nitrophenol, 4-nitrocatechol, 4-nitrosophenol) in addition to the hydroxylated products (catechol, hydroquinone, 1,4-benzoquinone, hydroxy-1,4-benzoquinone) evidenced formation of NO2·, NO· and OH· radicals and NO+ ions directly by the air plasma at the gas-liquid interface and through post-discharge processes in plasma-activated water (PAW) mediated by peroxynitrite (ONOOH). Kinetic study of post-discharge evolution of H2O2 and NO_{2}^{-} in PAW has demonstrated excellent fit with the pseudo-second-order reaction between H2O2 and NO_{2}^{-} . The third-order rate constant k = 1.1 × 103 M-2 s-1 for the reaction NO_{2}^{-} +H_{2}O_{2}+H^{+}\\to ONOOH+H_{2}O was determined in PAW at pH 3.3 with the rate of ONOOH formation in the range 10-8-10-9 M s-1. Peroxynitrite chemistry was shown to significantly participate in the antibacterial properties of PAW. Ozone presence in PAW was proved indirectly by pH-dependent degradation of phenol and detection of cis,cis-muconic acid, but contribution of ozone to the inactivation of bacteria by the air plasma was negligible.

  1. Green Chemistry and Education.

    Science.gov (United States)

    Hjeresen, Dennis L.; Schutt, David L.; Boese, Janet M.

    2000-01-01

    Many students today are profoundly interested in the sustainability of their world. Introduces Green Chemistry and its principles with teaching materials. Green Chemistry is the use of chemistry for pollution prevention and the design of chemical products and processes that are environmentally benign. (ASK)

  2. Stabilization and relative phase effects in a dichromatically driven diatomic Morse molecule: interpretation based on nonlinear classical dynamics.

    Science.gov (United States)

    Constantoudis, Vassilios; Nicolaides, Cleanthes A

    2005-02-22

    The dissociation dynamics of a dichromatically laser-driven diatomic Morse molecule vibrating in the ground state is investigated by applying tools of the nonlinear theory of classical Hamiltonian systems. Emphasis is placed on the role of the relative phase of the two fields, phi. First, it is found that, just like in quantum mechanics, there is dependence of the dissociation probability on phi. Then, it is demonstrated that addition of the second laser leads to suppression of probability (stabilization), when the intensity of the first laser is kept constant just above or below the single laser dissociation threshold. This "chemical bond hardening" diminishes as phi increases. These effects are investigated and interpreted in terms of modifications in phase space topology. Variations of phi as well as of the intensity of the second laser may cause (i) appearance/disappearance of the stability island corresponding to the common resonance with the lowest energy and (ii) deformation and movement of the region of Kolmogorov-Arnold-Moser tori that survive from the undriven system. The latter is the main origin in phase space of stabilization and phi dependence. Finally, it is shown that the use of short laser pulses enhances both effects.

  3. Dinitrogen and Related Chemistry of the Lanthanides: A Review of the Reductive Capture of Dinitrogen, As Well As Mono- and Di-aza Containing Ligand Chemistry of Relevance to Known and Postulated Metal Mediated Dinitrogen Derivatives

    Directory of Open Access Journals (Sweden)

    Damien N. Stringer

    2010-02-01

    Full Text Available This paper reviews the current array of complexes of relevance to achieving lanthanide mediated nitrogen fixation. A brief history of nitrogen fixation is described, including a limited discussion of successful transition metal facilitated nitrogen fixation systems. A detailed discussion of the numerous lanthanide-nitrogen species relevant to nitrogen fixation are discussed and are related to the Chatt cycle for nitrogen fixation.

  4. Modelling of phase equilibria and related properties of mixtures involving lipids

    DEFF Research Database (Denmark)

    Cunico, Larissa

    Many challenges involving physical and thermodynamic properties in the production of edible oils and biodiesel are observed, such as availability of experimental data and realiable prediction. In the case of lipids, a lack of experimental data for pure components and also for their mixtures in open...... literature was observed, what makes it necessary to development reliable predictive models from limited data. One of the first steps of this project was the creation of a database containing properties of mixtures involved in tasks related to process design, simulation, and optimization as well as design...... of chemicals based products. This database was combined with the existing lipids database of pure component properties. To contribute to the missing data, measurements of isobaric vapour-liquid equilibrium (VLE) data of two binary mixtures at two different pressures were performed using Differential Scanning...

  5. Improving Conceptions in Analytical Chemistry: The Central Limit Theorem

    Science.gov (United States)

    Rodriguez-Lopez, Margarita; Carrasquillo, Arnaldo, Jr.

    2006-01-01

    This article describes the central limit theorem (CLT) and its relation to analytical chemistry. The pedagogic rational, which argues for teaching the CLT in the analytical chemistry classroom, is discussed. Some analytical chemistry concepts that could be improved through an understanding of the CLT are also described. (Contains 2 figures.)

  6. Lifeblood : Chemistry of Blood in Eighteenth-Century Medicine

    NARCIS (Netherlands)

    Verwaal, Ruben

    2015-01-01

    Was early eighteenth-century chemistry merely a handmaid to medicine? This paper aims to reassess assumptions about the relation between chemistry and medicine in the early modern period and argues that chemistry played a central role in medicine. The fluid and flow of blood can serve as a starting

  7. Integrating Computational Chemistry into a Course in Classical Thermodynamics

    Science.gov (United States)

    Martini, Sheridan R.; Hartzell, Cynthia J.

    2015-01-01

    Computational chemistry is commonly addressed in the quantum mechanics course of undergraduate physical chemistry curricula. Since quantum mechanics traditionally follows the thermodynamics course, there is a lack of curricula relating computational chemistry to thermodynamics. A method integrating molecular modeling software into a semester long…

  8. Introduction to Physics and Chemistry of Combustion Explosion, Flame, Detonation

    CERN Document Server

    Liberman, Michael A

    2008-01-01

    Most of the material covered in this book deals with the fundamentals of chemistry and physics of key processes and fundamental mechanisms for various combustion and combustion related phenomena in gaseous combustible mixture. It provides the reader with basic knowledge of burning processes and mechanisms of reaction wave propagation. The combustion of a gas mixture (flame, explosion, detonation) is necessarily accompanied by motion of the gas. The process of combustion is therefore not only a chemical phenomenon but also one of gas dynamics. The material selection focuses on the gas phase and

  9. Thermal mass and dispersion relations of quarks in the deconfined phase of quenched QCD

    CERN Document Server

    Kaczmarek, Olaf; Kitazawa, Masakiyo; Soeldner, Wolfgang

    2012-01-01

    Temporal quark correlation functions are analyzed in quenched lattice QCD for two values of temperature above the critical temperature (Tc) for deconfinement, T=1.5Tc and 3Tc. A two-pole ansatz for the quark spectral function is used to determine the bare quark mass and the momentum dependence of excitation spectra on large lattices of size up to 128^3x16. The dependence of the quark correlator on these parameters as well as the finite volume dependence of the excitation energies are analyzed in detail in order to examine the reliability of our analysis. Our results suggest the existence of quasi-particle peaks in the quark spectrum. We furthermore find evidence that the dispersion relation of the plasmino mode has a minimum at non-zero momentum even in the non-perturbative region near Tc. We also elaborate on the enhancement of the quark correlator near the chiral limit which is observed at T=1.5Tc on about half of the gauge configurations. We attribute this to the presence of near zero-modes of the fermion ...

  10. Complex Protostellar Chemistry

    Science.gov (United States)

    Nuth, Joseph A., III; Johnson, Natasha M.

    2012-01-01

    Two decades ago, our understanding of the chemistry in protostars was simple-matter either fell into the central star or was trapped in planetary-scale objects. Some minor chemical changes might occur as the dust and gas fell inward, but such effects were overwhelmed by the much larger scale processes that occurred even in bodies as small as asteroids. The chemistry that did occur in the nebula was relatively easy to model because the fall from the cold molecular cloud into the growing star was a one-way trip down a well-known temperature-pressure gradient; the only free variable was time. However, just over 10 years ago it was suggested that some material could be processed in the inner nebula, flow outward, and become incorporated into comets (1, 2). This outward flow was confirmed when the Stardust mission returned crystalline mineral fragments (3) from Comet Wild 2 that must have been processed close to the Sun before they were incorporated into the comet. In this week's Science Express, Ciesla and Sandford (4) demonstrate that even the outermost regions of the solar nebula can be a chemically active environment. Their finding could have consequences for the rest of the nebula.

  11. Multidimensional separations of ubiquitin conformers in the gas phase: relating ion cross sections to H/D exchange measurements.

    Science.gov (United States)

    Robinson, Errol W; Williams, Evan R

    2005-09-01

    Investigating gas-phase structures of protein ions can lead to an improved understanding of intramolecular forces that play an important role in protein folding. Both hydrogen/deuterium (H/D) exchange and ion mobility spectrometry provide insight into the structures and stabilities of different gas-phase conformers, but how best to relate the results from these two methods has been hotly debated. Here, high-field asymmetric waveform ion mobility spectrometry (FAIMS) is combined with Fourier-transform ion cyclotron resonance mass spectrometry (FT/ICR MS) and is used to directly relate ubiquitin ion cross sections and H/D exchange extents. Multiple conformers can be identified using both methods. For the 9+ charge state of ubiquitin, two conformers (or unresolved populations of conformers) that have cross sections differing by 10% are resolved by FAIMS, but only one conformer is apparent using H/D exchange at short times. For the 12+ charge state, two conformers (or conformer populations) have cross sections differing by ion collisional cross sections and H/D exchange distributions are not strongly correlated and that factors other than surface accessibility appear to play a significant role in determining rates and extents of H/D exchange. Conformers that are not resolved by one method could be resolved by the other, indicating that these two methods are highly complementary and that more conformations can be resolved with this combination of methods than by either method alone.

  12. Surface chemistry essentials

    CERN Document Server

    Birdi, K S

    2013-01-01

    Surface chemistry plays an important role in everyday life, as the basis for many phenomena as well as technological applications. Common examples range from soap bubbles, foam, and raindrops to cosmetics, paint, adhesives, and pharmaceuticals. Additional areas that rely on surface chemistry include modern nanotechnology, medical diagnostics, and drug delivery. There is extensive literature on this subject, but most chemistry books only devote one or two chapters to it. Surface Chemistry Essentials fills a need for a reference that brings together the fundamental aspects of surface chemistry w

  13. The New Color of Chemistry: Green Chemistry

    Directory of Open Access Journals (Sweden)

    Zuhal GERÇEK

    2012-01-01

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

  14. Phase relations in the system Ca–Ta–O and thermodynamics of calcium tantalates in relation to calciothermic reduction of Ta{sub 2}O{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, K.T., E-mail: katob@materials.iisc.ernet.in; Rajput, Arneet

    2015-01-25

    Highlights: • Established at 1200 K are phase relations in the system Ca–Ta–O. • Four calcium tantalates have been identified. • Cells based on single crystal CaF{sub 2} are used for thermodynamic measurements. • Gibbs energies of formation of ternary oxides obtained in the range 975–1275 K. • Calciothermic and electrochemical reduction of Ta{sub 2}O{sub 5} are discussed. - Abstract: Phase equilibria of the system Ca–Ta–O is established by equilibrating eleven samples at 1200 K for prolonged periods and phase identification in quenched samples by optical and scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Four ternary oxides are identified: CaTa{sub 4}O{sub 11}, CaTa{sub 2}O{sub 6}, Ca{sub 2}Ta{sub 2}O{sub 7} and Ca{sub 4}Ta{sub 2}O{sub 9}. Isothermal section of the phase diagram is composed using the results. Thermodynamic properties of the ternary oxides are measured in the temperature range from 975 to 1275 K employing solid–state galvanic cells incorporating single crystal CaF{sub 2} as the solid electrolyte. The cells essentially measure the chemical potentials of CaO in two-phase fields (Ta{sub 2}O{sub 5} + CaTa{sub 4}O{sub 11}), (CaTa{sub 4}O{sub 11} + CaTa{sub 2}O{sub 6}), (CaTa{sub 2}O{sub 6} + Ca{sub 2}Ta{sub 2}O{sub 7}), and (Ca{sub 2}Ta{sub 2}O{sub 7} + Ca{sub 4}Ta{sub 2}O{sub 9}) of the pseudo-binary system CaO–Ta{sub 2}O{sub 5}. The standard Gibbs energies of formation of the four ternary oxides from their component binary oxides Ta{sub 2}O{sub 5} and CaO are given by: ΔG{sub f(ox)}{sup o}(CaTa{sub 4}O{sub 11})(±482)/Jmol{sup -1}=-58644+21.497(T/K) ΔG{sub f(ox)}{sup o}(CaTa{sub 2}O{sub 6})(±618)/Jmol{sup -1})=-55122+21.893(T/K) ΔG{sub f(ox)}{sup o}(Ca{sub 2}Ta{sub 2}O{sub 7})(±729)/Jmol{sup -1}=-82562+31.843(T/K) ΔG{sub f(ox)}{sup o}(Ca{sub 4}Ta{sub 2}O{sub 9})(±955)/Jmol{sup -1}=-126598+48.859(T/K) The Gibbs energy of formation of the four ternary compounds obtained in this study

  15. Structure, chemistry, and properties of mineral nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Waychunas, G.A.; Zhang, H.; Gilbert, B.

    2008-12-02

    Nanoparticle properties can depart markedly from their bulk analog materials, including large differences in chemical reactivity, molecular and electronic structure, and mechanical behavior. The greatest changes are expected at the smallest sizes, e.g. 10 nm and below, where surface effects are expected to dominate bonding, shape and energy considerations. The precise chemistry at nanoparticle interfaces can have a profound effect on structure, phase transformations, strain, and reactivity. Certain phases may exist only as nanoparticles, requiring transformations in chemistry, stoichiometry and structure with evolution to larger sizes. In general, mineralogical nanoparticles have been little studied.

  16. Sediment Thicknesses and Qs vs. Qp Relations in the Kachchh Rift Basin, Gujarat, India Using Sp Converted Phases

    Science.gov (United States)

    Mandal, Prantik

    2007-01-01

    Delineation of the top sedimentary structure and its Qs vs. Qp relationship using the travel-time difference of direct S and converted Sp phase is key to understanding the seismic hazard of any sedimentary basin area. We constructed filtered displacement waveforms from local ETNA Episensor acceleration recordings as well as local velocity recordings of aftershocks of the 2001 Bhuj earthquake recorded by the Kachchh seismological network of the National Geophysical Research Institute (NGRI), Hyderabad, India during 2001 2004. Stations are within 15 70km of epicenters, and the resulting displacement waveforms are generally simple, displaying prominent P, Sp, and S wave pulses. Particle motion of P and S waves suggest near-vertical raypaths consistent with preliminary depth estimates. The direct S wave on the horizontal component is characterized by lower frequency content than the converted Sp phase on the vertical component. This difference in frequency content between S and Sp phases can be explained in terms of different attenuation effects for P and S waves in the unconsolidated sediments. The Sp phase is generated by S-to-P phase conversion at the base of Mesozoic sediments of the Kachchh basin. Travel-time inversion (VELEST) of 2565 P and 2380 S arrivals from 658 well located aftershocks recorded at 8 14 three-component local seismic stations led to 1 D velocity models indicated very slow sediments in the upper 0 2 km depth range (Vp: 2.92 km/s and Vs: 0.90 km/s) and an increasing trend of velocities with depth at 2 40 km depth. The estimated sediment thicknesses beneath 12 accelerograph and 6 seismograph sites from the estimated velocity model and the travel-time difference between S and converted Sp phases reaches a maximum of (1.534 ± 0.117) km beneath Bandri (near the location of 2001 Bhuj mainshock) and attains a minimum sediment thickness of (0.858 ± 0.104) km beneath Ramvav and Burudia. The spectral ratios between Sp and S from 159 three

  17. A Chemistry Lesson at Three Mile Island.

    Science.gov (United States)

    Mammano, Nicholas J.

    1980-01-01

    Details the procedures used in utilizing the hydrogen bubble incident at Three Mile Island to relate these basic chemical principles to nuclear chemistry: gas laws, Le Chatelier's principle and equilibrium, and stoichiometry. (CS)

  18. Plate Tectonics Constrained by Evidence-Based Magmatic Temperatures and Phase Relations of Fertile Lherzolite (Invited)

    Science.gov (United States)

    Green, D. H.; Falloon, T.

    2010-12-01

    In order to understand Earth’s plate tectonics we must interpret the most direct probes for mantle composition and temperature distribution i.e. the primitive basaltic magmas and peridotites representing partial melts and mantle residues. An evidence-based approach to identification of parental magmas and determination of their temperatures requires glass and phenocryst compositions and experimentally calibrated Fe/Mg partitioning between olivine and melt. We have compared magmatic crystallization temperatures between ‘hot-spot’(proposed to be plume-related) and normal mid-ocean ridge basalt (MORB) parental liquids, by examining three representative magmatic suites from both ocean island (Hawaii, Iceland, and Réunion) and mid-ocean ridge settings (Cocos-Nazca, East Pacific Rise, and Mid-Atlantic Ridge). We have glass and olivine phenocryst compositions, including volatile (H2O) contents, and have calculated parental liquid compositions at 0.2GPa by incrementally adding olivine back into the glass compositions until a liquid in equilibrium with the most-magnesian olivine phenocryst composition is obtained. The results of these calculations demonstrate that there is very little difference (maximum of ~20°C) between the ranges of crystallization temperatures of the parental liquids (MORB:1243-1351°C versus OIB:1286-1372°C) when volatile contents are taken into account. However while lacking temperature contrast, the source regions for ‘hot-spot’ parental magmas contain geochemical signatures of old subducted crust/lithosphere. The mantle depths of origin determined for both the MORB and OIB suites are similar (MORB:1-2 GPa; OIB:1-2.5 GPa). Calculations of mantle potential temperatures (Tp) are model dependent, particularly to melt fraction from an inferred source. Assuming similar fertile lherzolite sources, the differences in Tp values between the hottest MORB and the hottest ocean island tholeiite sources are ~80°C. These differences disappear if the

  19. Comparison of Relative Activation Energies Obtained by Density Functional Theory and the Random Phase Approximation for Several Claisen Rearrangements.

    Science.gov (United States)

    Hartley, Madeline K; Vine, Seanna; Walsh, Elizabeth; Avrantinis, Sara; Daub, G William; Cave, Robert J

    2016-03-03

    We investigate several representative density functional theory approaches for the calculation of relative activation energies and free energies of a set of model pericyclic reactions, some of which have been studied experimentally. In particular, we use a standard hybrid functional (B3LYP), the same hybrid functional augmented with a basis set superposition error and dispersion correction, a meta-hybrid functional developed to treat transition states and weak interactions (M06-2X), and the recently implemented random phase approximation (RPA) based on Kohn-Sham orbitals from conventional density functional theory by Furche and co-workers. We apply these methods to calculate relative activation energies and estimated free energies for the amide acetal Claisen rearrangement. We focus on relative activation energies to assess the effects of steric and weak interactions in the various methods and compare with experiment where possible. We also discuss the advantages of using this set of reactions as a test bed for the comparison of treatments of weak interactions. We conclude that all methods yield similar trends in relative reactivity, but the RPA yields results in best agreement with the experimental values.

  20. The New Color of Chemistry: Green Chemistry

    OpenAIRE

    Zuhal GERÇEK

    2012-01-01

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