Note: This page contains sample records for the topic hot atom chemistry from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Hot atom chemistry and radiopharmaceuticals  

NASA Astrophysics Data System (ADS)

The chemical products made in a cyclotron target are a combined result of the chemical effects of the nuclear transformation that made the radioactive atom and the bulk radiolysis in the target. This review uses some well-known examples to understand how hot atom chemistry explains the primary products from a nuclear reaction and then how radiation chemistry is exploited to set up the optimal product for radiosynthesis. It also addresses the chemical effects of nuclear decay. There are important principles that are common to hot atom chemistry and radiopharmaceutical chemistry. Both emphasize short-lived radionuclides and manipulation of high specific activity nuclides. Furthermore, they both rely on radiochromatographic separation for identification of no-carrieradded products.

Krohn, Kenneth A.; Moerlein, Stephen M.; Link, Jeanne M.; Welch, Michael J.

2012-12-01

2

Hot Oxygen Atoms: Their Generation and Chemistry.  

National Technical Information Service (NTIS)

Oxygen atoms with energies between 1 and 10 eV have been produced through ion beam sputtering from metal oxide targets. Argon ion beams were used on Ta sub 2 O sub 5 and V sub 2 O sub 5 . Results show that some control may be exerted over the atom's kinet...

R. A. Ferrieri Y. Y. Chu A. P. Wolf

1987-01-01

3

International Hot Atom Chemistry Symposium (12th) at, Balatonfuered, Hungary, on 23-28 September 1984. Abstracts.  

National Technical Information Service (NTIS)

This proceedings contains the abstracts of 91 papers presented at the symposium. The majority of papers discusses various hot atom reactions and decay processes. A list of previous 11 international hot atom chemistry symposia from 1959 to 1982 is also giv...

1984-01-01

4

Hot oxygen atoms: Their generation and chemistry. [Production by sputtering; reaction with butenes  

SciTech Connect

Oxygen atoms with energies between 1 and 10 eV have been produced through ion beam sputtering from metal oxide targets. Argon ion beams were used on Ta/sub 2/O/sub 5/ and V/sub 2/O/sub 5/. Results show that some control may be exerted over the atom's kinetic energy by changing the target. Reactions of the hot O(/sup 3/P) with cis- and trans-butenes were investigated. (DLC)

Ferrieri, R.A.; Chu, Yung Y.; Wolf, A.P.

1987-01-01

5

HOT-ATOM CHEMISTRY OF HEXAMMINE-CHROMIUM(III) NITRATE IN THE SOLID STATE  

Microsoft Academic Search

A heterogeneous extraction method for enriching Cr⁵¹ recoil atoms ; in neutron-irradiated hexamminechromium(III) nitrate was investigated. The ; mechanisms of the reaction are discussed. The Cr⁵¹ atoms were extracted ; and enriched in the aqueous phase by shaking the target powder with concentrated ; HNO. Chemical forms of the recoil atoms were also studied. (M.C.G.);

Nagao Ikeda; Kenji Yoshihara; Hiroshi Ebihara; Kiyomi Suzuki

1961-01-01

6

Hot-atom incorporation of tritium atoms into fullerenes  

NASA Astrophysics Data System (ADS)

We have used classical hot-atom chemistry to put tritium atoms inside fullerene molecules. The tritium is generated in a nuclear reactor with the reaction Li-6(n, alpha)H-3. The hot tritium atom slows down and can end up being thermalized inside a fullerene where it is trapped. The irradiated sample is dissolved, chromatographed, and counted in a scintillation counter, showing a small tritium activity. After some time, the sample is analyzed with a sensitive mass spectrometer, and He-3 was found on heating above 400 C, showing that the tritium had decayed leaving the He-3 trapped inside the fullerene.

Jimenez-Vazquez, H. A.; Cross, R. J.; Saunders, M.; Poreda, R. J.

1994-10-01

7

Statistical fragmentation of hot atomic metal clusters  

Microsoft Academic Search

Fragmentation processes of highly excited neutral and charged atomic metal clusters are studied in the framework of an equilibrium statistical model. In the particular case of hot (near and above melting) neutral and charged sodium clusters of 100 and 200 atoms, a microcanonical Metropolis sampling is used to compute mass (or charge) correlation functions as a function of the excitation

D. H. E. Gross; P. A. Hervieux

1995-01-01

8

Super Hot Hydrogen Atoms in Microwave Plasmas  

NASA Astrophysics Data System (ADS)

``Super hot'' (with kinetic energy in the range 4 - 8 eV) and ``hot'' (kinetic energy 0.3 eV) hydrogen atoms were detected throughout the volume of a surface wave (500 MHz) generated H2 plasma column, at pressure p = 0.01 mbar, from the analysis of the H?, H?, H?and H? emission line profiles. The profiles were found to evolve from single Gaussian to bi-Gaussian towards the column end. Population inversion between the levels 5->4 and 6->4 was detected from the measured relative intensities of transitions within the Balmer series. The Doppler temperatures corresponding to the H?, H?, H?, H? line broadening are much higher than the rotational temperature, as measured from the hydrogen molecular Fulcher-? band (350 -- 500 K), and than the wall temperature (300 -- 450 K). At pressure p = 0.2 mbar, ``super hot'' atoms were not detected while ``hot'' atoms are present. It has also been found that the kinetic temperature of excited H (n = 4 -7) atoms, as determined from the fitting of the spectral lines with a single Gaussian profile, increases with the upper level principal quantum number. These experimental results are analyzed in the framework of a kinetic model, which accounts for the generation of three groups of atoms.

Felizardo, Edgar; Tatarova, Elena; Dias, Francisco; Lino da Silva, M.; Ferreira, Carlos; Gordiets, Boris

2009-10-01

9

Semiempirical hot atom theory. I - Initialization and application  

NASA Technical Reports Server (NTRS)

A semiempirical approach to the modeling of the kinetics of reaction systems containing both hot and nonhot atoms is proposed. The approach is based on the probabilistic kinetic theory of hot-atom reactions formulated by Wolfgang (1963), with transmission probabilities estimated for a rectangular potential barrier for hot-atom and nonhot-atom reactions. A computational scheme for determining product concentrations following hot and nonhot reactions in a system containing photolytically produced hot atoms is then applied to the DBr + CH4 and HBr + CD4 hot hydrogen atom systems studied by Martin and Willard (1964), and good agreement is obtained between theoretical and experimental results.

Aronowitz, S.; Chang, S.; Scattergood, T.

1981-01-01

10

Sulphur Chemistry and Evolution in Hot Cores  

Microsoft Academic Search

We compare the results of our JCMT spectralline survey of molecular gas towards ultracompact Hii regionswith the predictions of models of sulphur chemistryin hot cores. We investigate the range of evolutionary modelsthat are consistent with the observed physical conditionsand chemical abundances, and see to what extentit is possible to constrain core ages by comparing abundanceswith the predictions of chemical models.

G. H. Macdonald; J. Hatchell; M. A. Thompson; T. J. Millar

11

Cold and Hot Atomic Vapors: a Testbed for Astrophysics?  

NASA Astrophysics Data System (ADS)

Atomic physics experiments, based on hot vapors or laser-cooled atomic samples, may be useful to simulate some astrophysical problems, where radiation pressure, radiative transport or light amplification are involved. We discuss several experiments and proposals, dealing with multiple-scattering of light in hot and cold atomic vapors, random lasing in cold atoms and light-induced long-range forces, which may be relevant in this context.

Baudouin, Q.; Guerin, W.; Kaiser, R.

2014-03-01

12

Liquid-metal atomization for hot working preforms  

NASA Technical Reports Server (NTRS)

Rapid quenching of a liquid metal by atomization or splat cooling overcomes the major limitation of most solidification processes, namely, the segregation of alloying elements, impurities, and constituent phases. The cooling rates of different atomizing processes are related to the dendrite arm spacings and to the microstructure of the atomized powders. The increased solubility limits and the formation of metastable compounds in splat-cooled alloys are discussed. Consolidation of the powders by hot isostatic compaction, hot extrusion, or hot forging and rolling processes yields billets with properties equivalent to or better than those of the wrought alloys. The application of this powder processing technology to high-performance alloys is reviewed.

Grant, N. J.; Pelloux, R. M.

1974-01-01

13

Impurity hot atoms in irradiated metals with different nuclear history  

Microsoft Academic Search

General relationships in the effect of the nuclear history on the forms of stabilization of impurity hot atoms and on the\\u000a diffusion mobility and specific features of the physicochemical behavior of radioactive micro-impurities in the course of\\u000a annealing of radiation-induced perturbations and of structural transformations of irradiated metals were elucidated. The forms\\u000a of stabilization of impurity hot atoms in metals

I. E. Alekseev

2008-01-01

14

Interfacial chemistry of the hot water process for recovering bitumen from the Athabasca oil sands  

SciTech Connect

Results from investigations into the interfacial chemistry of the hot water process for recovering bitumen from the Athabasca oil sands are presented. A discussion of the role of natural surfactants in the hot water process is included.

Schramm, L.L.; Smith, R.G.; Stone, J.A.

1984-01-01

15

Escape of Hot Oxygen Atoms from the Atmosphere of Mars  

NASA Astrophysics Data System (ADS)

The main source of the production of hot oxygen atoms in the Martian atmosphere is the dissociative recombination (DR) reaction of O2+ ions with electrons. In this study, the primary production rate of hot O atoms is found for four energy channels of DR reaction. The one-dimensional energy and altitude dependent up and down flux differential equations are solved using a two-stream transport method, by taking into account the primary, secondary and cascade productions of hot O and also, the interactions with the background atmosphere. The forward and backward scattering probabilities and energy loss coefficients for 12 neutral target species are found using a Monte-Carlo simulation. The neutral target species are H, H2, He, C, N, O, CO, N2, NO, O2, Ar and CO2 for which the density profiles appropriate for Viking landers condition are used. From the up and down fluxes, the energy distribution function of hot O atoms and the escape flux at the exobase of Mars is calculated and by using the Liouville equation, the density profile of hot O is found above the exobase, extending out to several Martian radii. The results are used to study the interaction of escaping hot O atoms with the solar wind and specifically, the fluxes of energetic O+ pickup ions are determined.

Rahmati, A.; Croxell, J. A.; Cravens, T.; Pothapragada, S.; Nagy, A. F.; Ledvina, S. A.

2013-12-01

16

Surface Chemistry in Electrochemical Atomic Layer Processing.  

National Technical Information Service (NTIS)

Atomic layer processing involves the formation and/or etching of materials an atomic layer at a time. Atomic layer epitaxy is the most obvious example, where a thin film of a material is formed an atomic layer at a time. That is, surface limited reactions...

J. L. Stickney

1997-01-01

17

Unveiling the chemistry of hot protostellar cores with ALMA  

NASA Astrophysics Data System (ADS)

High angular resolution mm-wave observations of the Orion-KL region, made with the IRAM Plateau de Bure interferometer (PdBI), reveal the presence of several cores of size 103 AU, which have distinct spectral signatures. Complex molecules such as ethanol, vinyl cyanide and dimethyl ether show different distributions and their relative abundance varies from core to core by orders of magnitude. The molecular column densities derived in the cores also differ widely from the beam-averaged column densities observed with large single-dish telescopes. Obviously, the predictions of hot core chemistry models must be checked against high resolution observations. ALMA, which allies sensitivity and high angular resolution, will be a key instrument for this type of studies. The PdBI observations were part of a search for interstellar glycine, also carried out with the IRAM 30-m telescope and the Green Bank Telescope. We derive a 3 ? upper limit on the column density of glycine of 11015 cm-2 per 2?3? beam in the Orion Hot Core and Compact Ridge.

Gulin, M.; Brouillet, N.; Cernicharo, J.; Combes, F.; Wootten, A.

2008-01-01

18

Evidence for a rotational rainbow in inelastic hot atom experiments  

SciTech Connect

The rotational population of carbon dioxide,after collision with translationally hot hydrogen atoms has been reported recently(ref.1). It is contended that the population distribution can be explained by a rotational rainbow mechanism for the rotational excitation.(AIP) :m

Bowman, J.M.; Gazdy, B.

1987-03-01

19

Bibliography on Atomic Processes in Hot Dense Plasmas.  

National Technical Information Service (NTIS)

Information on atomic processes in hot dense plasmas which are connected with inertial confinement fusion and astrophysics was compiled from 114 records stored in the HIDENS data base. Energy level, f or A value, bound free transition, free-free transitio...

T. Kato T. Kagawa S. Karashima N. Miyanaga H. Tawara

1983-01-01

20

Sounding rocket observation of a hot atomic oxygen geocorona  

NASA Technical Reports Server (NTRS)

A sounding rocket measurement of the ultraviolet, atomic oxygen dayglow reveals an excess of emission compared to standard thermospheric model calculations at exospheric altitudes. We explore two explanations for this discrepancy: a breakdown of the radiative transfer model due to nonlocal thermal equilibrium (non-LTE) conditions above the exobase and a hot atomic oxygen geocorona. In particular, the effects of non-LTE on the 3P2, 1, 0 sublevel populations are modeled, and a hot O component in the upper thermosphere and lower exosphere is added to investigate the effects on the modeled emissions. For both cases, the data are reanalyzed and compared with the results using a standard LTE model. A hot O geocorona having a peak density of 10(exp 6)/cc at 550 km and a temperature of 4000 K is consistent with the data and appears to be the most reasonable explanation of the high-altitude enhanced emissions observed in the data.

Cotton, Daniel M.; Gladstone, G. Randall; Chakrabarti, Supriya

1993-01-01

21

Femtosecond two-photon photoassociation of hot magnesium atoms: A quantum dynamical study using thermal random phase wavefunctions  

SciTech Connect

Two-photon photoassociation of hot magnesium atoms by femtosecond laser pulses, creating electronically excited magnesium dimer molecules, is studied from first principles, combining ab initio quantum chemistry and molecular quantum dynamics. This theoretical framework allows for rationalizing the generation of molecular rovibrational coherence from thermally hot atoms [L. Rybak, S. Amaran, L. Levin, M. Tomza, R. Moszynski, R. Kosloff, C. P. Koch, and Z. Amitay, Phys. Rev. Lett. 107, 273001 (2011)]. Random phase thermal wavefunctions are employed to model the thermal ensemble of hot colliding atoms. Comparing two different choices of basis functions, random phase wavefunctions built from eigenstates are found to have the fastest convergence for the photoassociation yield. The interaction of the colliding atoms with a femtosecond laser pulse is modeled non-perturbatively to account for strong-field effects.

Amaran, Saieswari; Kosloff, Ronnie [Fritz Haber Research Centre and The Department of Physical Chemistry, Hebrew University, Jerusalem 91904 (Israel)] [Fritz Haber Research Centre and The Department of Physical Chemistry, Hebrew University, Jerusalem 91904 (Israel); Tomza, Micha?; Skomorowski, Wojciech; Paw?owski, Filip; Moszynski, Robert [Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland)] [Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland); Rybak, Leonid; Levin, Liat; Amitay, Zohar [The Shirlee Jacobs Femtosecond Laser Research Laboratory, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel)] [The Shirlee Jacobs Femtosecond Laser Research Laboratory, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Berglund, J. Martin; Reich, Daniel M.; Koch, Christiane P. [Theoretische Physik, Universitt Kassel, Heinrich-Plett-Strae 40, 34132 Kassel (Germany)] [Theoretische Physik, Universitt Kassel, Heinrich-Plett-Strae 40, 34132 Kassel (Germany)

2013-10-28

22

Organic chemistry: A tuxedo for iodine atoms  

Microsoft Academic Search

Iodine atoms can be fitted with a chemical jacket to control the conversion of simple carbon chains into complex iodine-containing molecules. Previously, such reactions were only possible with enzymes.

Phil S. Baran; Thomas J. Maimone

2007-01-01

23

Primordial chemistry and enzyme evolution in a hot environment.  

PubMed

Ever since the publication of Darwin's Origin of Species, questions have been raised about whether enough time has elapsed for living organisms to have reached their present level of complexity by mutation and natural selection. More recently, it has become apparent that life originated very early in Earth's history, and there has been controversy as to whether life originated in a hot or cold environment. This review describes evidence that rising temperature accelerates slow reactions disproportionately, and to a much greater extent than has been generally recognized. Thus, the time that would have been required for primordial chemistry to become established would have been abbreviated profoundly at high temperatures. Moreover, if the catalytic effect of a primitive enzyme (like that of modern enzymes) were to reduce a reaction's heat of activation, then the rate enhancement that it produced would have increased as the surroundings cooled, quite aside from changes arising from mutation (which is itself highly sensitive to temperature). Some nonenzymatic catalysts of slow reactions, including PLP as a catalyst of amino acid decarboxylation, and the Ce(IV) ion as a catalyst of phosphate ester hydrolysis, have been shown to meet that criterion. The work reviewed here suggests that elevated temperatures collapsed the time required for early evolution on Earth, furnishing an appropriate setting for exploring the vast range of chemical possibilities and for the rapid evolution of enzymes from primitive catalysts. PMID:24623557

Wolfenden, Richard

2014-08-01

24

Nanoscale atoms in solid-state chemistry.  

PubMed

We describe a solid-state material formed from binary assembly of atomically precise molecular clusters. [Co6Se8(PEt3)6][C60]2 and [Cr6Te8(PEt3)6][C60]2 assembled into a superatomic relative of the cadmium iodide (CdI2) structure type. These solid-state materials showed activated electronic transport with activation energies of 100 to 150 millielectron volts. The more reducing cluster Ni9Te6(PEt3)8 transferred more charge to the fullerene and formed a rock-salt-related structure. In this material, the constituent clusters are able to interact electronically to produce a magnetically ordered phase at low temperature, akin to atoms in a solid-state compound. PMID:23744780

Roy, Xavier; Lee, Chul-Ho; Crowther, Andrew C; Schenck, Christine L; Besara, Tiglet; Lalancette, Roger A; Siegrist, Theo; Stephens, Peter W; Brus, Louis E; Kim, Philip; Steigerwald, Michael L; Nuckolls, Colin

2013-07-12

25

Hot hydrogen atom reactions moderated by H2 and He.  

PubMed

Photolysis experiments were performed on the H2-CD4-NH3 and the He-CD4-NH3 systems. The photolysis (1849 angstoms) involved only NH3. Mixtures of H2:CD4:NH3 included all combinations of the ratios (200,400,800):(10,20,40):4. Two He:CD4:NH3 mixtures were examined where the ratios equalled the combinations 100:(10,20):4. Abstraction of a D from CD4 by the photolytically produced hot hydrogen from ammonia was monitored by mass spectrometric determination of HD. Both experiment and semiempirical hot-atom theory show that H2 is a very poor thermalizer of hot hydrogens with excess kinetic energy of about 2 eV. Applications of the hard-sphere collision model to the H2-CD4-NH3 system results in predicted ratios of net HD production to NH3 decomposition that were two orders of magnitude smaller than the experimental ratios. On the other hand, helium is found to be a very efficient thermalizer; here, the classical model yields reasonable agreement with experiments. Application of a semiempirical hot-atom program gave quantitative agreement with experiment for either system. PMID:11542026

Aronowitz, S; Scattergood, T; Flores, J; Chang, S

1986-01-01

26

The Chemistry of Metal-Rich Hot Neptunes  

NASA Astrophysics Data System (ADS)

Neptune-mass planets with very high metallicities (100-3000 times solar) will exhibit an interesting continuum of atmospheric compositions in between the so-called hot Neptune and Super Earth exoplanet categories. If its metallicity is only slightly enhanced over solar, a Neptune-mass planet would have a photospheric composition similar to that predicted for any hydrogen-dominated, Jupiter-mass planet possessing a similar thermal structure and experiencing a similar incident stellar flux. Hydrogen-poor Super Earths, on the other hand, could have a variety of atmospheric compositions (e.g., Schaefer et al. 2011, arXiv:1108.4660), ranging from H2O-, CO2-, or N2-dominated atmospheres, to more exotic high-temperature SiO and metal-rich atmospheres, depending on the planets mass, evolutionary history, incident stellar flux, and effective temperature. A Neptune-mass planet can become metal rich through efficient hydrogen escape (e.g., for less-massive, close-in planets) or through inefficient accretion of H2, as has been suggested for our own solar-system ice giant Neptune, where carbon is enriched by 40-70 times solar (e.g., Karkoschka and Tomasko 2011, Icarus 211, 780) and oxygen may be enriched as much as 440 times solar (e.g., Lodders and Fegley 1994, Icarus 112, 368). We explore the predicted equilibrium and disequilibrium chemistry of generic hot Neptunes with metallicities varying from 1-3000 times solar and discuss observational consequences. The models are applied to the case of GJ 436b, where we find that methane will be the dominant carbon carrier until very high metallicities, near 2000x solar, at which point the planet can have roughly equal proportions of CO, H2, and CO2, with methane becoming a more minor constituent. We compare our model results with Spitzer infrared secondary-eclipse data for GJ436b. This work was supported by the NASA PATM program.

Moses, Julianne I.; Richardson, M. R.; Madhusudhan, N.; Line, M. R.; Visscher, C.; Fortney, J. J.

2012-10-01

27

Two-dimensional atomic hydrogen concentration maps in hot-filament diamond-deposition environment  

NASA Astrophysics Data System (ADS)

This paper reports the two-dimensional mapping of atomic hydrogen concentration with two-photon excited laser induced fluorescence in a multi-wire grid hot-filament chemical vapor deposition reactor. The measurements were made in a diamond film deposition environment under different filament temperatures and wire configurations. The measurement was calibrated with a titration reaction using NO2 as a titrant. The kinetic gas temperature in the reactor was measured from the Doppler broadening of the Lyman-? transition excited in the fluorescence. The filament temperature was found to have a significant effect on atomic hydrogen production and transfer to the substrate. The axial concentration distributions were compared to a one-dimensional kinetic gas-surface chemistry model with good agreement. The model produced a reasonable estimate for the bulk diamond film growth rate.

Larjo, J.; Koivikko, H.; Lahtonen, K.; Hernberg, R.

28

Alloys Fabricated by Gas Atomization and Hot Extrusion  

NASA Astrophysics Data System (ADS)

In this research, n-type (Bi2Te3)1- x (Bi2Se3) x -based thermoelectric (TE) materials were produced through a gas atomization process, and subsequently hot extruded with an extrusion ratio of 10:1 at 400 C. The effect of chemical composition on TE properties was investigated. The microstructure of all extruded bars showed a homogeneous and fine distribution of grains due to the dynamic recrystallization during the hot extrusion process. With increasing Bi2Te3 content, from 0.85 to 0.90, both electrical resistivity and Seebeck coefficient values were increased. The maximum figure of merit ( ZT) 0.673 was obtained at room temperature for (Bi2Te3)0.90(Bi2Se3)0.10 alloys due to them exhibiting higher seebeck coefficient and lower thermal conductivity than other compositions.

Madavali, Babu; Kim, Hyo-Seob; Hong, Soon-Jik

2014-06-01

29

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

SciTech Connect

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

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

1989-02-01

30

A collisional-radiative average atom model for hot plasmas  

SciTech Connect

A collisional-radiative `average atom` (AA) model is presented for the calculation of opacities of hot plasmas not in the condition of local thermodynamic equilibrium (LTE). The electron impact and radiative rate constants are calculated using the dipole oscillator strengths of the average atom. A key element of the model is the photon escape probability which at present is calculated for a semi infinite slab. The Fermi statistics renders the rate equation for the AA level occupancies nonlinear, which requires iterations until the steady state. AA level occupancies are found. Detailed electronic configurations are built into the model after the self-consistent non-LTE AA state is found. The model shows a continuous transition from the non-LTE to the LTE state depending on the optical thickness of the plasma. 22 refs., 13 figs., 1 tab.

Rozsnyai, B.F.

1996-10-17

31

Hot-atom synthesis of organic compounds on Jupiter  

NASA Technical Reports Server (NTRS)

Results of recent laboratory 'simulations' of photochemical processes on Jupiter are combined with available data on mixing rates and exposure times in the Jovian atmosphere to give quantitative predictions of the rate at which hot-atom reactions produce organic molecules. It is shown that abstraction reactions on methane by hot H atoms from solar UV photolysis of H2S will produce no more than 4 times 10 to the -17th power g/sq cm/sec for a steady-state mole fraction of total organics of approximately 10 to the -16th power. This is roughly 10 to the 7th power times less than the limit of detection of the most sensitive gas analysis experiments ever flown on a spacecraft. By far the most common organic molecule produced by this mechanism is CH3SH, methyl mercaptan, which is produced at a rate at least 600 times smaller than the rate of production of ethane by direct photolysis of CH4 at high altitudes.

Lewis, J. S.; Fegley, B., Jr.

1979-01-01

32

The chemistry of atomic transition-metal ions: Insight into fundamental aspects of organometallic chemistry  

Microsoft Academic Search

For species as simple as atomic transition-metal ions, organometallic transformations usually involve multistep processes. These transformations have been studied with the entire arsenal of experimental techniques developed for the study of ion-molecule chemistry: conventional tandem mass spectrometry, flowing afterglow (FA) techniques, and ion cyclotron resonance (ICR) mass spectrometry and its Fourier transform adaptation (FT-ICR). In this Account, the authors limit

P. B. Armentrout; J. L. Beauchamp

1989-01-01

33

Effects of surface chemistry on hot corrosion life  

NASA Technical Reports Server (NTRS)

Baseline burner rig hot corrosion with Udimet 700, Rene' 80; uncoated and with RT21, Codep, or NiCoCrAlY coatings were tested. Test conditions are: 900C, hourly thermal cycling, 0.5 ppm sodium as NaCl in the gas stream, velocity 0.3 Mach. The uncoated alloys exhibited substantial typical sulfidation in the range of 140 to 170 hours. The aluminide coatings show initial visual evidence of hot corrosion at about 400 hours, however, there is no such visual evidence for the NiCoCrAlY coatings. The turbine components show sulfidation. The extent of this distress appeared to be inversely related to the average length of mission which may, reflect greater percentage of operating time near ground level or greater percentage of operation time at takeoff conditions (higher temperatures). In some cases, however, the location of maximum distress did not exhibit the structural features of hot corrosion.

Fryxell, R. E.

1984-01-01

34

Equilibrium Chemistry of the Atmospheres of Hot Earth-like Exoplanets  

Microsoft Academic Search

The Kepler and COROT missions and Earth-based observations have discovered putative rocky exoplanets and at least some of these are very hot because they orbit their stars at close distance, e.g., CoRot-7b. Here we discuss atmospheric chemistry for an Earth-like planet hot enough to vaporize its crust. We computed the chemical equilibrium composition of a system with elemental abundances of

Laura Schaefer; K. Lodders; B. Fegley

2010-01-01

35

Infusing the Chemistry Curriculum with Green Chemistry Using Real-World Examples, Web Modules, and Atom Economy in Organic Chemistry Courses  

ERIC Educational Resources Information Center

Green chemistry is the awareness of the damaging environmental effects due to chemical research and inventions. There is emphasis on a need to include green chemistry in synthesis with atom economy in organic chemistry curriculum to ensure an environmentally conscious future generation of chemists, policy makers, health professionals and business

Cann, Michael C.; Dickneider, Trudy A.

2004-01-01

36

Hot-atom chemistry of metal complexes in organic solvents  

Microsoft Academic Search

Investigations and recent research developments concerning the scavenger ; effect of metal complexes in organic solvents are described. Retentions of \\/sup ; 60\\/Co and ⁵¹Cr were obtained after irradiating benzene solutions of 0.2-0.5 ; M Co(acac) and Cr(acac) with thermal neutrons in a nuclear reactor ; and separating the recoil products by the solvent extraction method and other ; methods.

Tominaga

1973-01-01

37

Surface Chemistry Features in the Hot Water Processing of Utah Tar Sand  

Microsoft Academic Search

The hot water processing of Utah tar sand involves two important steps in the process sequence, phase disengagement (digestion) and phase separation (flotation). Inasmuch as phase separation is accomplished by flotation, the hydrophobic\\/hydrophilic balance at the surface of the bitumen droplets was studied in conjunction with the system's solution chemistry and the results correlated with the flotation response.Contact angle measurements

M. Misra; Rosme Aguilar; J. D. Miller

1981-01-01

38

Effects of surface chemistry on hot corrosion life  

NASA Technical Reports Server (NTRS)

Burner rig tests were conducted under the following conditions: 900 C, hourly thermal cycling, 0.5 ppm sodium as NaCl in the gas stream, and Mach 0.3 velocity. The alloys tested were Udimet 700 (U700) and Rene 80, uncoated and with RT21, Codep, or NiCoCrAlY coatings. The tests, up to 1000 hours, included specimens in the as-processed condition and after aging at 1100 C in oxidizing or inert environments for up to 600 hours. Coil-inductance changes were measured for periodic nondestructive inspection of speciments and found useful in the following course of corrosion. Typical sulfidation observed in all cases was similar to that observed in service-run turbine components. Aging at 1100 C caused severe decrease in the hot corrosion life of RT21 and Codep coatings and a significant but lesser decrease in the life of NiCoCrAlY coatings. The extent of these decreases was much greater for all three coatings on U700 than on Rene substrates. A coating hot corrosion life-predicitin model was proposed. The model requires time/temperature information for a turbine component at takeoff conditions as well as environmental contaminant information.

Fryxell, R. E.; Leese, G. E.

1986-01-01

39

Hydrogen atom initiated chemistry. [chemical evolution in planetary atmospheres  

NASA Technical Reports Server (NTRS)

H Atoms have been created by the photolysis of H2S. These then initiated reactions in mixtures involving acetylene-ammonia-water and ethylene-ammonia-water. In the case of the acetylene system, the products consisted of two amino acids, ethylene and a group of primarily cyclic thio-compounds, but no free sulfur. In the case of the ethylene systems, seven amino acids, including an aromatic one, ethane, free sulfur, and a group of solely linear thio-compounds were produced. Total quantum yields for the production of amino acids were about 3 x 10 to the -5th and about 2 x 10 to the -4th with ethylene and acetylene respectively as carbon substrates. Consideration is given of the mechanism for the formation of some of the products and implications regarding planetary atmosphere chemistry, particularly that of Jupiter, are explored.

Hong, J. H.; Becker, R. S.

1979-01-01

40

The chemistry of atomic transition-metal ions: Insight into fundamental aspects of organometallic chemistry  

SciTech Connect

For species as simple as atomic transition-metal ions, organometallic transformations usually involve multistep processes. These transformations have been studied with the entire arsenal of experimental techniques developed for the study of ion-molecule chemistry: conventional tandem mass spectrometry, flowing afterglow (FA) techniques, and ion cyclotron resonance (ICR) mass spectrometry and its Fourier transform adaptation (FT-ICR). In this Account, the authors limit ourselves to those methods in which motion along the reaction coordinate is the key dynamic variable that can be controlled as reactants approach and measured as the products recede. In our laboratories, guided ion beam techniques have been developed and highly refined for studies of the variation of reaction probabilities with E{sub T}. Complementing this work are measurements of product kinetic energy release distributions (KERDs).

Armentrout, P.B. (Univ. of Utah, Salt Lake City (USA)); Beauchamp, J.L. (California Institute of Technology, Pasadena (USA))

1989-09-01

41

Kinetics of Semiconductor Surface Chemistry: Silicon Atomic Layer Processing.  

National Technical Information Service (NTIS)

Surface Kinetics play a crucial role in semiconductor processing chemistry. Our research concentrates on fundamental understanding of microscopic surface kinetics that dictate surface chemistry. We are exploring the various adsorption, decomposition, diff...

S. M. George

1993-01-01

42

Reaction studies of hot silicon, germanium and carbon atoms. Progress report, November 16, 1985-November 15, 1986.  

National Technical Information Service (NTIS)

Research has been continued on hot silicon, germanium and carbon atoms. Progress in the period November 16, 1985 to November 15, 1986 is reviewed in the following areas: (1) Recoil atom reaction studies. (2) Reactions of thermally generated free atoms.

P. P. Gaspar

1986-01-01

43

Basic actinide chemistry and physics research in close cooperation with hot laboratories: ACTILAB  

NASA Astrophysics Data System (ADS)

Basic research in actinide chemistry and physics is indispensable to maintain sustainable development of innovative nuclear technology. Actinides, especially minor actinides of americium and curium, need to be handled in special facilities with containment and radiation shields. To promote and facilitate actinide research, close cooperation with the facilities and sharing of technical and scientific information must be very important and effective. A three-year-program "Basic actinide chemistry and physics research in close cooperation with hot laboratories", ACTILAB, was started to form the basis of sustainable development of innovative nuclear technology. In this program, research on actinide solid-state physics, solution chemistry and solid-liquid interface chemistry is made using four main facilities in Japan in close cooperation with each other, where basic experiments with transuranium elements can be made. The 17O-NMR measurements were performed on (Pu0.91Am0.09)O2 to study the electronic state and the chemical behaviour of Am and Cm ions in electrolyte solutions was studied by distribution experiments.

Minato, K.; Konashi, K.; Fujii, T.; Uehara, A.; Nagasaki, S.; Ohtori, N.; Tokunaga, Y.; Kambe, S.

2010-03-01

44

Water chemistry of hot waters of Umut geothermal field (SW Turkey)  

NASA Astrophysics Data System (ADS)

Umut geothermal field is located on Menderes graben which is one of the most active geothermal regions of Turkey. In order to delineate the chemistry of the waters of Umut geothermal field, fourteen samples were taken from four wells and ten from hot springs. Discharge temperatures of the waters range from 20 to 120 C. According to the results of chemical analyses, the waters are Na+K - HCO3 type. Cation geothermometer calculations revealed a reservoir temperature greater than 200 C for Umut geothermal field waters. Stable isotope analyses results indicates that the waters are meteoric in origin.

Av?ar, zgr; Tre, Orkun

2014-05-01

45

Atoms-First Curriculum: A Comparison of Student Success in General Chemistry  

ERIC Educational Resources Information Center

We present an evaluation of the impact of an atoms-first curriculum on student success in introductory chemistry classes and find that initially a lower fraction of students obtain passing grades in the first and second quarters of the general chemistry series. This effect is more than reversed for first-quarter students after one year of

Esterling, Kevin M.; Bartels, Ludwig

2013-01-01

46

Hot Atoms and Molecules Produced by Precipitating Ions in the Martian Atmosphere  

NASA Astrophysics Data System (ADS)

Accurate parameters describing the momentum-energy transfer of precipitating ion and energetic neutral atom (ENA) fluxes, created through charge exchange collisions between solar wind ions and neutral gases in the Mars atmosphere, have been determined. For modeling the momentum and energy deposition by precipitating ion/ENA fluxes, ab initio quantum cross sections have been computed and used for atom-atom collisions for energies up to 10 keV/amu. Newly developed 'universal' cross sections, obtained via quantum scaling procedure and verified with available data of laboratory experiments, have been employed for unknown atom-molecule collisions, such as ENAs collisions with CO2, H2, or N2. Scaling methods and accurate quantum differential cross sections, obtained in our investigations, allows for realistic descriptions of energy transfer processes and production of secondary hot atoms and molecules in the Martian atmosphere. To describe ion/ENA precipitation and upward propagation of the secondary hot atoms and molecules, 3d Monte Carlo simulations have been developed using the newly constructed collision database. Formation and propagation of the upward and escape fluxes in the Mars atmosphere have been analyzed in detail with a comprehensive examination of parameters such as thermalization times, altitude dependent heating and secondary hot atom creation rates, and energy/momentum distributions in atom/molecule escape fluxes. The Monte Carlo simulations have been performed for different solar conditions and the solar wind parameters.

Lewkow, N.; Kharchenko, V. A.

2013-12-01

47

Volatile organic compound ratios as probes of halogen atom chemistry in the Arctic  

NASA Astrophysics Data System (ADS)

Volatile organic compound concentration ratios can be used as indicators of halogen chemistry that occurs during ozone depletion events in the Arctic during spring. Here we use a combination of modeling and measurements of [acetone]/[propanal] as an indicator of bromine chemistry, and [isobutane]/[n-butane] and [methyl ethyl ketone]/[n-butane] are used to study the extent of chlorine chemistry during four ozone depletion events during the Polar Sunrise Experiment of 1995. Using a 0-D photochemistry model in which the input of halogen atoms is controlled and varied, the approximate ratio of [Br]/[Cl] can be estimated for each ozone depletion event. It is concluded that there must be an additional source of propanal (likely from the snowpack) to correctly simulate the VOC chemistry of the Arctic, and further evidence that the ratio of Br atoms to Cl atoms can vary greatly during ozone depletion events is presented.

Cavender, A. E.; Biesenthal, T. A.; Bottenheim, J. W.; Shepson, P. B.

2008-03-01

48

Volatile organic compound ratios as probes of halogen atom chemistry in the Arctic  

NASA Astrophysics Data System (ADS)

Volatile organic compound concentration ratios can be used as indicators of halogen chemistry that occurs during ozone depletion events in the Arctic during spring. Here we use a combination of modeling and measurements of [acetone]/[propanal] as an indicator of bromine chemistry, and [isobutane]/[n-butane] and [methyl ethyl ketone]/[n-butane] are used to study the extent of chlorine chemistry during four ozone depletion events during the Polar Sunrise Experiment of 1995. Using a 0-D photochemistry model in which the input of halogen atoms is controlled and varied, the approximate ratio of [Br]/[Cl] can be estimated for each ozone depletion event. It is concluded that there must be an additional source of propanal (likely from the snowpack) to correctly simulate the VOC chemistry of the Arctic, and that the ratio of Br atoms to Cl atoms can vary greatly during ozone depletion events.

Cavender, A. E.; Biesenthal, T. A.; Bottenheim, J. W.; Shepson, P. B.

2007-08-01

49

Equilibrium Chemistry of the Atmospheres of Hot Earth-like Exoplanets  

NASA Astrophysics Data System (ADS)

The Kepler and COROT missions and Earth-based observations have discovered putative rocky exoplanets and at least some of these are very hot because they orbit their stars at close distance, e.g., CoRot-7b. Here we discuss atmospheric chemistry for an Earth-like planet hot enough to vaporize its crust. We computed the chemical equilibrium composition of a system with elemental abundances of the terrestrial continental crust from 500 - 4000 K as a function of pressure from 10-6 to 10+2.5 bars. Calculations were done with a Gibbs energy minimization code. We will present results for the major volatile elements H, C, N, O, and S, and the lithophile elements Na, K, Fe, Si, Mg, Al, Ca, and Ti at a nominal pressure of 100 bars as a function of temperature. The major gases are H2O and CO2 at low temperatures, and SiO, O, H, and O2 at high temperatures. We also present condensation temperatures for major compounds as a function of pressure, which will be useful in determining cloud composition. These results should be useful in planning spectroscopic studies of the atmospheres of hot Earth-like exoplanets. This work was supported by the NSF Astronomy Program and the NASA Astrobiology Program.

Schaefer, Laura; Lodders, K.; Fegley, B.

2010-10-01

50

Dry soldering with hot filament produced atomic hydrogen  

SciTech Connect

A system is disclosed for chemically transforming metal surface oxides to metal that is especially, but not exclusively, suitable for preparing metal surfaces for dry soldering and solder reflow processes. The system employs one or more hot, refractory metal filaments, grids or surfaces to thermally dissociate molecular species in a low pressure of working gas such as a hydrogen-containing gas to produce reactive species in a reactive plasma that can chemically reduce metal oxides and form volatile compounds that are removed in the working gas flow. Dry soldering and solder reflow processes are especially applicable to the manufacture of printed circuit boards, semiconductor chip lead attachment and packaging multichip modules. The system can be retrofitted onto existing metal treatment ovens, furnaces, welding systems and wave soldering system designs. 1 fig.

Panitz, J.K.G.; Jellison, J.L.; Staley, D.J.

1995-04-25

51

Symmetry in chemistry from the hydrogen atom to proteins.  

PubMed

The last 2 decades have seen discoveries in highly excited states of atoms and molecules of phenomena that are qualitatively different from the "planetary" model of the atom, and the near-rigid model of molecules, characteristic of these systems in their low-energy states. A unified view is emerging in terms of approximate dynamical symmetry principles. Highly excited states of two-electron atoms display "molecular" behavior of a nonrigid linear structure undergoing collective rotation and vibration. Highly excited states of molecules described in the "standard molecular model" display normal mode couplings, which induce bifurcations on the route to molecular chaos. New approaches such as rigid-nonrigid correlation, vibrons, and quantum groups suggest a unified view of collective electronic motion in atoms and nuclear motion in molecules. PMID:8962040

Kellman, M E

1996-12-10

52

Symmetry in chemistry from the hydrogen atom to proteins  

PubMed Central

The last 2 decades have seen discoveries in highly excited states of atoms and molecules of phenomena that are qualitatively different from the planetary model of the atom, and the near-rigid model of molecules, characteristic of these systems in their low-energy states. A unified view is emerging in terms of approximate dynamical symmetry principles. Highly excited states of two-electron atoms display molecular behavior of a nonrigid linear structure undergoing collective rotation and vibration. Highly excited states of molecules described in the standard molecular model display normal mode couplings, which induce bifurcations on the route to molecular chaos. New approaches such as rigidnonrigid correlation, vibrons, and quantum groups suggest a unified view of collective electronic motion in atoms and nuclear motion in molecules.

Kellman, Michael E.

1996-01-01

53

Chemical Principles Revisited: Updating the Atomic Theory in General Chemistry.  

ERIC Educational Resources Information Center

Presents a descriptive overview of recent achievements in atomic structure to provide instructors with the background necessary to enhance their classroom presentations. Topics considered include hadrons, quarks, leptons, forces, and the unified fields theory. (JN)

Whitman, Mark

1984-01-01

54

Production of OH Molecules by Hot Oxygen Atoms in the Upper Atmospheres of Terrestrial Planets  

NASA Astrophysics Data System (ADS)

Photodissociation of CO2 and O2 molecules and dissociative recombination of oxygen molecular ions are among the most important sources of suprathermal oxygen atoms in the upper atmospheres of terrestrial planets. The produced hot oxygen atoms can transfer energy in collisions with thermal atmospheric gases and perturb local equilibrium conditions or induce non-thermal chemical reactions. One such process is the reaction of hot O atoms with hydrogen molecules, leading to production of highly rotationally-vibrationally excited OH molecules. We report the results of extensive reactive quantum scattering calculations of O + H2(v, j) ? H + OH(v', j') and corresponding non-thermal rate coefficients at the atmospheric conditions found on Earth and Mars for different solar conditions. Possible implications of this comparative study on the physics of upper atmospheres of terrestrial planets are discussed.

Gacesa, M.; Kharchenko, V.

2012-12-01

55

Atomic structure and chemistry of human serum albumin  

NASA Astrophysics Data System (ADS)

The three-dimensional structure of human serum albumin has been determined crystallographically to a resolution of 2.8 . It comprises three homologous domains that assemble to form a heart-shaped molecule. Each domain is a product of two subdomains that possess common structural motifs. The principal regions of ligand binding to human serum albumin are located in hydrophobic cavities in subdomains IIA and IIIA, which exhibit similar chemistry. The structure explains numerous physical phenomena and should provide insight into future pharmacokinetic and genetically engineered therapeutic applications of serum albumin.

He, Xiao Min; Carter, Daniel C.

1992-07-01

56

Single-collision studies of hot atom energy transfer and chemical reaction  

SciTech Connect

This report discusses research in the collision dynamics of translationally hot atoms, with funding with DOE for the project Single-Collision Studies of Hot Atom Energy Transfer and Chemical Reaction,'' Grant Number DE-FG03-85ER13453. The work reported here was done during the period September 9, 1988 through October 31, 1991. During this period this DOE-funded work has been focused on several different efforts: (1) experimental studies of the state-to-state dynamics of the H + RH {yields} H{sub 2} R reactions where RH is CH{sub 4}, C{sub 2}H{sub 6}, or C{sub 3}H{sub 8}, (2) theoretical (quasiclassical trajectory) studies of hot hydrogen atom collision dynamics, (3) the development of photochemical sources of translationally hot molecular free radicals and characterization of the high resolution CARS spectroscopy of molecular free radicals, (4) the implementation of stimulated Raman excitation (SRE) techniques for the preparation of vibrationally state-selected molecular reactants.

Valentini, J.J. (Columbia Univ., New York, NY (United States))

1991-01-01

57

Single-collision studies of hot atom energy transfer and chemical reaction. Final report  

SciTech Connect

This report discusses research in the collision dynamics of translationally hot atoms, with funding with DOE for the project ``Single-Collision Studies of Hot Atom Energy Transfer and Chemical Reaction,`` Grant Number DE-FG03-85ER13453. The work reported here was done during the period September 9, 1988 through October 31, 1991. During this period this DOE-funded work has been focused on several different efforts: (1) experimental studies of the state-to-state dynamics of the H + RH {yields} H{sub 2} R reactions where RH is CH{sub 4}, C{sub 2}H{sub 6}, or C{sub 3}H{sub 8}, (2) theoretical (quasiclassical trajectory) studies of hot hydrogen atom collision dynamics, (3) the development of photochemical sources of translationally hot molecular free radicals and characterization of the high resolution CARS spectroscopy of molecular free radicals, (4) the implementation of stimulated Raman excitation (SRE) techniques for the preparation of vibrationally state-selected molecular reactants.

Valentini, J.J. [Columbia Univ., New York, NY (United States)

1991-12-31

58

The coordination and atom transfer chemistry of titanium porphyrin complexes  

SciTech Connect

Preparation, characterization, and reactivity of ({eta}{sup 2}- alkyne)(meso-tetratolylpoprphrinato)titanium(II) complexes are described, along with inetermetal oxygen atom transfer reactions involving Ti(IV) and Ti(III) porphyrin complexes. The {eta}{sup 2}- alkyne complexes are prepared by reaction of (TTP)TiCl{sub 2} with LiAlH{sub 4} in presence of alkyne. Structure of (OEP)Ti({eta}{sup 2}-Ph-C{triple_bond}C-Ph) (OEP=octaethylporphryin) was determined by XRD. The compounds undergo simple substitution to displace the alkyne and produce doubly substituted complexes. Structure of (TTP)Ti(4-picoline){sub 2} was also determined by XRD. Reaction of (TTP)Ti{double_bond}O with (OEP)Ti-Cl yields intermetal O/Cl exchange, which is a one-electron redox process mediated by O atom transfer. Also a zero-electron redox process mediated by atom transfer is observed when (TTP)TiCl{sub 2} is reacted with (OEP)Ti{double_bond}O.

Hays, J.A.

1993-11-05

59

Experimental Constraints on Hot Spring Fluid Chemistry in Back Arc Basins  

NASA Astrophysics Data System (ADS)

Many axial hot springs from back-arc basins are characterized by low pH and high metal concentrations compared to fluids from the mid-ocean ridge. Such differences are likely related to the presence of felsic crust and the involvement of acidic magmatic fluids in back-arc hydrothermal systems. Previous experiments that reacted fresh andesite with seawater at elevated T and P yielded pH values significantly higher than those observed in back-arc basin hot springs. Moreover, ocean drilling beneath back-arc basin hot springs revealed acid-sulfate alteration assemblages, suggesting at least transient involvement of magmatic fluids. Here we report the results of two laboratory experiments designed to assess fluid chemistry in equilibrium with acid-sulfate alteration assemblages at sub-seafloor conditions typically associated with back-arc hot springs. Both experiments reacted a K-Ca-Na-Cl fluid with a pyrophyllite-pyrite-anhydrite-quartz assemblage (PPAQ). In addition, alunite was added to the assemblage in one experiment (PPAQA). Both experiments were conducted in a flexible-cell hydrothermal apparatus utilizing an inert Au-Ti reaction cell. Fluid samples were withdrawn from the reaction cell as a function of time and temperature and analyzed for major anions, cations, pH (25C), H2, and H2S to monitor reaction progress. In the PPAQ experiment, pH varied from 3.1 to 3.4 from 350 to 365C at 0.25 Kb. At 385C, 0.26 Kb, pH dropped to 2.74, close to the value observed in many BAB hot springs. H2S varied from 2 mmol/kg at 350C, 0.25 Kb to 11 mmol/kg at 385C, 0.26 Kb. In general, K decreased and Ca increased with increasing T and decreasing P while SO4 remained low (<1 mmol/kg). In the PPAQA experiment, fluid pH was much lower, varying from 2.2 to 1.5 from 250 to 350C, 0.25 Kb. H2S was low (<1 mmol/kg) at these same conditions. Similarly, H2 was <0.003 mmol/kg, consistent with relatively oxidizing conditions. K concentration remained nearly constant while Ca increased with decreasing T. SO4 varied inversely with Ca, varying from 35 to 4 mmol/kg from 350 to 250C, respectively. Thus, the presence of alunite in the alteration assemblage yields an extremely acid fluid, depleted in H2S and enriched in SO4 compared to fluids from the PPAQ experiment. These results suggest that the composition of hot spring fluids from back-arc environments is consistent with fluid-mineral equilibria involving acid-sulfate mineral assemblages. Such assemblages may be produced by previous episodes of magmatic degassing. Accordingly, the presence of highly acidic vent fluids may reflect an important role for magmatic fluids during crustal alteration processes, but does not require the presence of an actively degassing magma chamber.

Schaen, A. T.; Saccocia, P. J.; Seewald, J.

2010-12-01

60

Ultra fast cooling of hot steel plate by air atomized spray with salt solution  

NASA Astrophysics Data System (ADS)

In the present study, the applicability of air atomized spray with the salt added water has been studied for ultra fast cooling (UFC) of a 6 mm thick AISI-304 hot steel plate. The investigation includes the effect of salt (NaCl and MgSO4) concentration and spray mass flux on the cooling rate. The initial temperature of the steel plate before the commencement of cooling is kept at 900 C or above, which is usually observed as the "finish rolling temperature" in the hot strip mill of a steel plant. The heat transfer analysis shows that air atomized spray with the MgSO4 salt produces 1.5 times higher cooling rate than atomized spray with the pure water, whereas air atomized spray with NaCl produces only 1.2 times higher cooling rate. In transition boiling regime, the salt deposition occurs which causes enhancement in heat transfer rate by conduction. Moreover, surface tension is the governing parameter behind the vapour film instability and this length scale increases with increase in surface tension of coolant. Overall, the achieved cooling rates produced by both types of salt added air atomized spray are found to be in the UFC regime.

Mohapatra, Soumya S.; Ravikumar, Satya V.; Jha, Jay M.; Singh, Akhilendra K.; Bhattacharya, Chandrima; Pal, Surjya K.; Chakraborty, Sudipto

2014-05-01

61

Two-color ghost interference with photon pairs generated in hot atoms  

SciTech Connect

We report on an experimental observation of a two-photon ghost interference experiment. A distinguishing feature of our experiment is that the photons are generated via a non-degenerated spontaneous four-wave mixing process in a hot atomic ensemble; therefore the photon has narrow bandwidth. Besides, there is a large difference in frequency between two photons in a pair. Our works may be important to achieve more secure, large transmission capacity long-distance quantum communication.

Ding Dongsheng; Zhou Zhiyuan; Shi Baosen; Zou Xubo; Guo Guangcan [Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026 (China)

2012-09-15

62

Atomic-Hydrogen Mapping in Hot-Filament Chemical-Vapor Deposition  

NASA Astrophysics Data System (ADS)

Two-dimensional maps of the atomic-hydrogen concentration distribution were acquired with two-photon laser-induced fluorescence. The environment was a hot-filament chemical-vapor-deposition reactor used for polycrystalline diamond-film deposition. The maps were measured in situ under diamond-deposition conditions with variation of the growth parameters. The parameters investigated were filament temperature, input methane concentration, and total pressure.

Larjo, Jussi; Koivikko, Heidi; Li, Daming; Hernberg, Rolf

2001-02-01

63

Atomic theories of phyllosilicates: Quantum chemistry, statistical mechanics, electrostatic theory, and crystal chemistry  

Microsoft Academic Search

This paper is a review atomic-level studies of phyllosilicates. Included are quantum chemical, crystal chemical, electrostatic, and statistical mechanical investigations. Five themes are proposed for future research: short-range water-clay, clay-clay, and ion-clay potentials; structure of defects and edges; structure and properties of interlayer water; chemical reaction and phyllosilicate edges; and electron transfer and transport. 106 refs., 3 figs., 5 tabs.

William F. Bleam

1993-01-01

64

Hot electrons and radial transport in Saturn's inner magetosphere: Modeling the effects on ion chemistry  

NASA Astrophysics Data System (ADS)

The E-ring of Saturn, located just beyond the main rings at four Saturn radii, was known to be made mostly of water and its by-products before the Cassini spacecraft arrived at Saturn in 2005. Since then, Cassini has observed water geysers on the tiny moon of Enceladus ejecting ? 100 kg of water per second into orbit around Saturn, which most agree is the chief contributor to neutrals in the E-ring. Following several key reactions, many of these neutrals go on to populate large, tenuous structures, known as neutral clouds, extending 10s of Saturn radii. The other side of the story are the ions, which are largely created by the ionization of same neutrals sourced from Enceladus. A key distinction between the neutrals and ions is that ions are carried along by Saturn's magnetic field, and revolve around Saturn at the rotation rate of the planet, while neutrals generally have much slower Keplerian speeds. It is the study of the chemical interaction of these separate, but related populations that is the subject of this thesis. We have developed a series of models to study how the coupling of these systems affect details of the other, such as composition. The first step (Chapter 2) was the development of a water-group physical chemistry model, which includes suprathermal electrons and the effect of radial ion transport. With this "one-box" model, we are able to reproduce observed water and hydrogen ion densities in Enceladus's orbit, but only when the hot electron density is ? 0.5% of the total plasma density. Radial transport is found to be slow, requiring 26 days to remove ions from the orbit of Enceladus. Moving toward the development of a radial model of ion chemistry, in Chapter 4 we present a model of Saturn's neutral clouds, which are made of material outgassing from Enceladus. The effects of dissociation and charge exchange are considered, where the details of the latter prove to be of great consequence on neutral cloud morphology. The oxygen cloud is found to the most extended, followed by H2O, and finally OH. The above efforts are combined in Chapter 5, where a neutral cloud model is used to construct a radial model of ion chemistry. It is shown that neutral H2O requires more spreading than yet modeled in order to recover observed water and hydrogen ion abundances near Enceladus. The relative abundance of water-group ion species presented will be useful for analyses of CAPS-IMS data, while loss rates derived from the model can be used to improve neutral cloud models. The case is made that ion chemistry models and neutral cloud models must be developed alongside one another in order to improve understanding of these interrelated populations at Saturn.

Fleshman, Bobby L.

65

Global Dynamics of Hot Atomic Oxygen in Mars' Upper Atmosphere and Comparison with Recent Observation  

NASA Astrophysics Data System (ADS)

The production of energetic particles in Mars's upper thermosphere and exosphere results in the formation of hot atom coronae. Dissociative recombination (DR) of O2+ ion is the dominant source of the production of hot atomic oxygen and the most important reaction for the exosphere on Mars, which occurs mostly deep in the dayside thermosphere of Mars. In this investigation, we have carried out the study of the global dynamics of energetic particles in Mars' upper atmosphere using our newly developed self-consistent Monte-Carlo model. The calculated total global escapes of hot oxygen are presented for different solar activities (solar maximum and minimum) and Martian seasons (aphelion, equinox, and perihelion). To describe self-consistently the exosphere and the upper thermosphere, a combination of our 3D Direct Simulation Monte Carlo (DSMC) model [Valeille, A., Combi, M., Bougher, S., Tenishev, V., Nagy, A., 2009. J. Geophys. Res. 114, E11006. doi:10.1029/2009JE003389] and the 3D Mars Thermosphere General Circulation Model (MTGCM) [Bougher, S.W., Bell, J.M., Murphy, J.R., Lopez-Valverde, M.A., Withers, P.G., 2006. Geophys. Res. Lett. 32, doi: 10.1029/2005GL024059. L02203] is used. Profiles of density and temperature, atmospheric loss rates, and return fluxes are studied using the model for the cases considered. Progress in updating the model physics is also described. Along with comparisons of our DSMC model outputs with those from other recent exosphere model studies, we present a comparison of our model results with the derived neutral oxygen density from atomic oxygen emission at 1304 that was detected by Alice instrument on board European Space Agency's Rosetta spacecraft [Feldman, P., Steffl, A., Parker, J, A'Hearn, M., Bertaux, J., Stern, S., Weaver, H., Slater, D., Versteeg, M., Throop, H., Cunningham, N., Feaga, L., 2011. Icarus. 214, 2, 394-399, doi:10.1016/j.icarus.2011.06.013].

Lee, Y.; Combi, M. R.; Tenishev, V.; Bougher, S. W.

2012-12-01

66

How in Spite of the Rhetoric, History of Chemistry Has Been Ignored in Presenting Atomic Structure in Textbooks.  

ERIC Educational Resources Information Center

Reports on a study designed to: (a) show how the importance of the history of chemistry has been recognized in the classroom; (b) demonstrate how criteria based on history and philosophy of science can be used to evaluate the presentation of atomic structure in general chemistry textbooks; and (c) compare new (1970-1992) and old textbooks

Rodriguez, Maria A.; Niaz, Mansoor

2002-01-01

67

Experiences and Reflections about Teaching Atomic Structure in a Jigsaw Classroom in Lower Secondary School Chemistry Lessons  

Microsoft Academic Search

This article describes and discusses an example of how atomic structure can be taught in lower secondary chemistry using a modified jigsaw-classroom method. The lesson was taught in grades 9 and 10 (age range 15 17 years) chemistry in 13 learning groups with a total of 313 students in various grammar, middle, and comprehensive schools in Germany. The written evaluation

Ingo Eilks

2005-01-01

68

Generating Molecular Rovibrational Coherence by Two-Photon Femtosecond Photoassociation of Thermally Hot Atoms  

SciTech Connect

The formation of diatomic molecules with rotational and vibrational coherence is demonstrated experimentally in free-to-bound two-photon femtosecond photoassociation of hot atoms. In a thermal gas at a temperature of 1000 K, pairs of magnesium atoms, colliding in their electronic ground state, are excited into coherent superpositions of bound rovibrational levels in an electronically excited state. The rovibrational coherence is probed by a time-delayed third photon, resulting in quantum beats in the UV fluorescence. A comprehensive theoretical model based on ab initio calculations rationalizes the generation of coherence by Franck-Condon filtering of collision energies and partial waves, quantifying it in terms of an increase in quantum purity of the thermal ensemble. Our results open the way to coherent control of a binary reaction.

Rybak, Leonid; Levin, Liat; Amitay, Zohar [Shirlee Jacobs Femtosecond Laser Research Laboratory, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Amaran, Saieswari; Kosloff, Ronnie [Institute of Chemistry, Hebrew University, Jerusalem 91904 (Israel); Tomza, Michal; Moszynski, Robert [Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland); Koch, Christiane P. [Institut fuer Theoretische Physik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Theoretische Physik, Universitaet Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel (Germany)

2011-12-30

69

HOT-ATOM CHEMISTRY OF HALOGENS IN COBALTAMMINE COMPLEX SALTS. I. HOT-ATOM CHEMISTRY OF BROMINE IN BROMOPENTAMMINE COBALT COMPLEX SALTS  

Microsoft Academic Search

Thermal neutron irradiation of STACo(NH)Br!\\/sup 2+\\/ salls, ; producing Br\\/sup 80m\\/ and Br⁸², was studied with the salts in solid and ; aqueous solution phases and as absorbed on a cation exchange resin, which was ; subsequentiy used as a meaas of separation. The fraction of radiobromine ; retained as ligand was determined by adding the sample to the resin

Nobufusa Saito; Hirotoshi Sano; Takeshi Tominaga

1960-01-01

70

Why has the bohr-sommerfeld model of the atom been ignoredby general chemistry textbooks?  

PubMed

Bohr's model of the atom is considered to be important by general chemistry textbooks. A major shortcoming of this model was that it could not explain the spectra of atoms containing more than one electron. In order to increase the explanatory power of the model, Sommerfeld hypothesized the existence of elliptical orbits. This study has the following objectives: 1) Formulation of criteria based on a history and philosophy of science framework; and 2) Evaluation of university-level general chemistry textbooks based on the criteria, published in Italy and U.S.A. Presentation of a textbook was considered to be "satisfactory" if it included a description of the Bohr-Sommerfeld model along with diagrams of the elliptical orbits. Of the 28 textbooks published in Italy that were analyzed, only five were classified as "satisfactory". Of the 46 textbooks published in U.S.A., only three were classified as "satisfactory". This study has the following educational implications: a) Sommerfeld's innovation (auxiliary hypothesis) by introducing elliptical orbits, helped to restore the viability of Bohr's model; b) Bohr-Sommerfeld's model went no further than the alkali metals, which led scientists to look for other models; c) This clearly shows that scientific models are tentative in nature; d) Textbook authors and chemistry teachers do not consider the tentative nature of scientific knowledge to be important; e) Inclusion of the Bohr-Sommerfeld model in textbooks can help our students to understand how science progresses. PMID:24061142

Niaz, Mansoor; Cardellini, Liberato

2011-12-01

71

Biomacromolecule immobilization and self-assembled monolayer chemistry on atomic layer deposited metal oxide materials  

NASA Astrophysics Data System (ADS)

Many biotechnology applications involve interfacing proteins, DNA and other macromolecules to non-biological material surfaces acting as supports. Support materials employed for this purpose span the periodic table and range from polymeric membranes/hydrogels to metals and ceramics, for example gold and hydroxyapatite. Lab-on-a-chip and other sensing/detection applications based on lithography and semiconductor technology typically rely on alkanethiol and organosilane chemistry to immobilize biological material to gold and silica. While successful in many instances, organosilane chemistry offers limited options for orthogonal chemistry and often results in multilayer film buildup. Self-assembly on gold is straight forward but gold is often undesirable from a device perspective. Recent developments in atomic layer deposition (ALD) allow fabrication of high quality thin films of alumina and high-k oxide materials that are compatible with clean room operations and are interesting emerging materials for integrated optical, electronic and biological applications. Here we will show alternative self-assembly chemistries on ALD materials for biological immobilization than those used on gold/silica and also demonstrate direct biological interfacing to high-K materials for potential use in bioscreening and detection.

Bergkvist, Magnus

2009-10-01

72

Fast etching of amorphous and microcrystalline silicon by hot-filament generated atomic hydrogen  

SciTech Connect

A hot tungsten wire effectively dissociates H{sub 2} into atomic hydrogen and thereby facilitates etching and hydrogenation of silicon. Hot filament generated atomic hydrogen etches amorphous silicon (a-Si:H) at a rate of up to 27 {angstrom}/s and microcrystalline ({micro}c) Si at rates up to 20 {angstrom}/s. A large laminar gas flow is the key to high etch rates. It provides for a fast transport of the etch products out of the reaction zone and thereby avoids redeposition. The etch rate increases with pressure and with H{sub 2} gas flow. Likewise, the etch rate rises with the filament temperature and saturates at a filament temperature of approximately 2,150 C when approaching the maximum H{sub 2} dissociation probability. The decrease of the etch rate at higher substrate temperatures is attributed to the loss of the surface coverage by atomic hydrogen. The etch selectivity between a-Si:H and {micro}c-Si drops at elevated substrate temperatures. Boron doping decreases the etch rates both for a-Si:H and {micro}c-Si, whereas phosphorous doping does not significantly affect it. This etch selectivity is caused by a catalytic effect of BH{sub 3} on the surface hindering the formation of the main etch product silane. Even for highest etch rates no surface roughening of a-Si:H occurs, however, a bond structure modification of the near surfaces arises, an effect which results in the formation of a nanocrystalline surface layer. The increase of the {micro}c-Si etch rate close to the film substrate interface characterizes the film thickness at which the coalescence of the microcrystalline nuclei starts.

Wanka, H.N.; Schubert, M.B.

1997-07-01

73

Influence of chemistry and hot rolling conditions on high permeability non-grain oriented silicon steel  

NASA Astrophysics Data System (ADS)

This paper discusses the influence of chemical composition on the final electromagnetic properties in higher permeability material. Furthermore, the effect of the hot rolling practice and the end of austenite transformation temperature range on the hot band microstructure is described. The magnetic polarization J5000 better than 1.7 T, using hot rolling conditions 40 mm transfer bar thickness, finish mill entry temperature 1000 C, and finishing temperature 800-840 C and after decarburization heat treatment and grain growth treatment, was obtained.

Hu?ady, J.; ?ernk, M.; Hilinski, E. J.; Predmersk, M.; Magurov, A.

2006-09-01

74

Undergraduate chemistry students' conceptions of atomic structure, molecular structure and chemical bonding  

NASA Astrophysics Data System (ADS)

The process of chemical education should facilitate students' construction of meaningful conceptual structures about the concepts and processes of chemistry. It is evident, however, that students at all levels possess concepts that are inconsistent with currently accepted scientific views. The purpose of this study was to examine undergraduate chemistry students' conceptions of atomic structure, chemical bonding and molecular structure. A diagnostic instrument to evaluate students' conceptions of atomic and molecular structure was developed by the researcher. The instrument incorporated multiple-choice items and reasoned explanations based upon relevant literature and a categorical summarization of student responses (Treagust, 1988, 1995). A covalent bonding and molecular structure diagnostic instrument developed by Peterson and Treagust (1989) was also employed. The ex post facto portion of the study examined the conceptual understanding of undergraduate chemistry students using descriptive statistics to summarize the results obtained from the diagnostic instruments. In addition to the descriptive portion of the study, a total score for each student was calculated based on the combination of correct and incorrect choices made for each item. A comparison of scores obtained on the diagnostic instruments by the upper and lower classes of undergraduate students was made using a t-Test. This study also examined an axiomatic assumption that an understanding of atomic structure is important in understanding bonding and molecular structure. A Pearson Correlation Coefficient, ?, was calculated to provide a measure of the strength of this association. Additionally, this study gathered information regarding expectations of undergraduate chemistry students' understanding held by the chemical community. Two questionnaires were developed with items based upon the propositional knowledge statements used in the development of the diagnostic instruments. Subgroups of items from the questionnaires were formed from the combination of items found to measure different aspects of a specific topic area using a reliability analysis. Average scores for the subgroups were compared to results obtained by students on the diagnostic instrument targeting the same topic area. There were no significant differences of the scores on both of the diagnostic instruments between the levels of undergraduate chemistry students. There were, however, significant differences on certain items of the diagnostic instruments between upper and lower class students. Additionally, misconceptions were identified within all levels of these undergraduate students that corresponded to previous results reported in the literature. A significant relationship was found to exist between the scores obtained on the two diagnostic instruments, as well as strong correlations between specific items and the total scores of the instruments. Response to the expectations questionnaires revealed no differences between the chemical industry and chemical academia, but did provide information concerning the chemical community's expectations of undergraduate chemistry students. Results indicate that undergraduate students majoring in chemistry have conceptions that are inconsistent with currently accepted scientific views. The findings also support the hypothesis that an understanding of the general structure of the atom and the roles played by electrons in molecular bonding and structure is important to an understanding of chemical properties and behavior.

Campbell, Erin Roberts

75

Reaction chemistry/nanocrystal property relations in the hot injection synthesis, the role of the solute solubility.  

PubMed

Various literature studies show that increasing the concentration of free acid in the hot injection synthesis of colloidal nanocrystals raises the diameter of the resulting nanocrystals. We analyze this reaction chemistry/nanocrystal property relation by combining reaction simulations with an experimental study on a particular CdSe nanocrystal synthesis. We find that increasing the free acid concentration has the same effect on a real synthesis as raising the solute solubility in the simulations. Both lead to larger sizes and a deterioration of the size dispersion at constant reaction rate. Since free acids are used to coordinate the cation precursors in these syntheses, this leads to a meaningful link between a parameter in reaction simulations and the composition of an experimental reaction mixture. We thus explain the increase of the nanocrystal size with the acid concentration as resulting from an enhanced consumption of the solute by nanocrystal growth, which reduces the number of nanocrystals formed. This link between a simulation parameter and the composition of the reaction mixture provides a rational basis to further explore and understand reaction chemistry/nanocrystal property relations in the hot injection synthesis. PMID:23320536

Abe, Sofie; Capek, Richard K; De Geyter, Bram; Hens, Zeger

2013-02-26

76

Infusing the Chemistry Curriculum with Green Chemistry Using Real-World Examples, Web Modules, and Atom Economy in Organic Chemistry Courses  

NASA Astrophysics Data System (ADS)

Green chemistry principles and practices have been infused in the chemistry curriculum at the University of Scranton, including courses in general, organic, and inorganic chemistry, biochemistry, environmental, polymer, industrial, and advanced organic chemistry, and chemical toxicology. Web-based green chemistry teaching modules have been developed for each of these courses. We describe the principles underlying green chemistry and methods of introducing these concepts into the curriculum with an example of incorporating green chemistry into the undergraduate lecture and laboratory organic sequence. See Featured Molecules .

Cann, Michael C.; Dickneider, Trudy A.

2004-07-01

77

Analytical Chemistry Laboratory (ACL) procedure compendium. Volume 7, Safety operation procedure for hot cell  

SciTech Connect

This volume contains the interim change notice for the safety operation procedure for hot cell. It covers the master-slave manipulators, dry waste removal, cell transfers, hoists, cask handling, liquid waste system, and physical characterization of fluids.

Not Available

1993-08-01

78

Photoresist Removal Using Atomic Hydrogen Generated by Hot-Wire Catalyzer and Effects on Si-Wafer Surface  

NASA Astrophysics Data System (ADS)

We investigated an environmentally friendly method using atomic hydrogen generated by contact catalysis on a tungsten hot-wire catalyzer to remove photoresist instead of using chemicals and its effects on a Si-wafer surface. We eventually obtained a photoresist removal rate of 2.5 ?m/min attributable to a reaction of atomic hydrogen with a positive-tone novolak photoresist, without thermal shrinkage of the photoresist film during atomic hydrogen irradiation because the photoresist shrank only under the influence of substrate heating by the catalyzer. The effects of atomic hydrogen irradiation on the substrate surfaces cannot be confirmed.

Yamamoto, Masashi; Horibe, Hideo; Umemoto, Hironobu; Takao, Kazuhisa; Kusano, Eiji; Kase, Masataka; Tagawa, Seiichi

2009-02-01

79

Probing hot spots on protein-protein interfaces with all-atom free-energy simulation.  

PubMed

Modulation of protein-protein interactions by competitive small-molecule binding emerges as a promising avenue for drug discovery. Hot spots, i.e., amino acids with important contributions to the overall interaction energy, provide useful targets within these interfaces. To avoid time-consuming mutagenesis experiments, computational alanine screening has been developed for the prediction of hot spots based on existing structural information. Here we use the all-atom free-energy force field PFF02 to identify important amino acid residues in the complexes of the chemokine interleukin-8 (CXCL8) and an N-terminal peptide of its cognate receptor CXCR1, and of ERBIN, a molecular marker of the basolateral membrane in epithelial cells, in complex with the ERBIN-binding domain of tyrosin kinase ERBB2. The results of our analysis agree with available experimental functional assays, indicating that this approach is suitable for computational alanine screening and may help to identify competitive peptides as starting points for the development of inhibitors of protein-protein interactions for pharmaceutically relevant targets. PMID:19624188

Meliciani, Irene; Klenin, Konstantin; Strunk, Timo; Schmitz, Katja; Wenzel, Wolfgang

2009-07-21

80

Probing hot spots on protein-protein interfaces with all-atom free-energy simulation  

NASA Astrophysics Data System (ADS)

Modulation of protein-protein interactions by competitive small-molecule binding emerges as a promising avenue for drug discovery. Hot spots, i.e., amino acids with important contributions to the overall interaction energy, provide useful targets within these interfaces. To avoid time-consuming mutagenesis experiments, computational alanine screening has been developed for the prediction of hot spots based on existing structural information. Here we use the all-atom free-energy force field PFF02 to identify important amino acid residues in the complexes of the chemokine interleukin-8 (CXCL8) and an N-terminal peptide of its cognate receptor CXCR1, and of ERBIN, a molecular marker of the basolateral membrane in epithelial cells, in complex with the ERBIN-binding domain of tyrosin kinase ERBB2. The results of our analysis agree with available experimental functional assays, indicating that this approach is suitable for computational alanine screening and may help to identify competitive peptides as starting points for the development of inhibitors of protein-protein interactions for pharmaceutically relevant targets.

Meliciani, Irene; Klenin, Konstantin; Strunk, Timo; Schmitz, Katja; Wenzel, Wolfgang

2009-07-01

81

Interpenetrating network hydrogels via simultaneous "click chemistry" and atom transfer radical polymerization.  

PubMed

Simultaneous interpenetrating polymer networks (sIPNs) from concurrent copper(I)-catalyzed azide-alkyne cycloaddition "click chemistry" and atom transfer radical polymerization (ATRP) are described. Semi-sIPN of poly(ethylene glycol)/poly(2-hydroxyethyl methacrylate) (semi-PEG/PHEMA-sIPN) was first prepared via simultaneous "click chemistry" and ATRP from a mixture of poly(ethylene glycol)-diazide (N3-PEG-N3, Mn=4000 g/mol), tetrakis(2-propynyloxymethyl)methane (TPOM), ethyl-2-bromobutyrate (EBB), CuBr, pentamethyldiethylenetriamine (PMDETA), and 2-hydroxyethyl methacrylate (HEMA) in dimethylformamide (DMF). Full sIPN of PEG/PHEMA (full-PEG/PHEMA-sIPN) was then prepared via simultaneous "click chemistry" and ATRP from a mixture of N3-PEG-N3 (Mn=4000 g/mol), TPOM, EBB, CuBr, PMDETA, HEMA, and poly(ethylene glycol) diacrylate) (PEGDA, Mn=575) in DMF. Both the semi- and full-sIPNs exhibit a fast gelation rate and high gel yield. The sIPNs also exhibit high swelling ratios and good mechanical and antifouling properties. The morphology and thermal behavior of the sIPNs were studied by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). These sIPNs could find applications as biomaterials for contact lenses, biomedical materials, artificial organs, and drug delivery systems. PMID:20518556

Xu, L Q; Yao, F; Fu, G D; Kang, E T

2010-07-12

82

Identification of parameters through which surface chemistry determines the lifetimes of hot electrons in small Au nanoparticles  

PubMed Central

This paper describes measurements of the dynamics of hot electron cooling in photoexcited gold nanoparticles (Au NPs) with diameters of ?3.5 nm, and passivated with either a hexadecylamine or hexadecanethiolate adlayer, using ultrafast transient absorption spectroscopy. Fits of these dynamics with temperature-dependent Mie theory reveal that both the electronic heat capacity and the electronphonon coupling constant are larger for the thiolated NPs than for the aminated NPs, by 40% and 30%, respectively. Density functional theory calculations on ligand-functionalized Au slabs show that the increase in these quantities is due to an increased electronic density of states near the Fermi level upon ligand exchange from amines to thiolates. The lifetime of hot electrons, which have thermalized from the initial plasmon excitation, increases with increasing electronic heat capacity, but decreases with increasing electronphonon coupling, so the effects of changing surface chemistry on these two quantities partially cancel to yield a hot electron lifetime of thiolated NPs that is only 20% longer than that of aminated NPs. This analysis also reveals that incorporation of a temperature-dependent electronphonon coupling constant is necessary to adequately fit the dynamics of electron cooling.

Aruda, Kenneth O.; Tagliazucchi, Mario; Sweeney, Christina M.; Hannah, Daniel C.; Schatz, George C.; Weiss, Emily A.

2013-01-01

83

Heat transfer and flow in an atomizing mist jet: a combined hot film and shadowgraph imaging approach  

NASA Astrophysics Data System (ADS)

This paper presents research in the area of heat transfer and fluid dynamics in an impinging atomizing air/water mist jet. Time averaged and fluctuating local surface heat transfer results obtained by microfoil and hot film sensors are correlated with flow field measurements of droplet diameter and velocity obtained by shadowgraph imaging and droplet tracking velocimetry. This paper seeks to understand the linkage between the atomization process in the nozzle, the two-phase flow dynamics and the surface heat transfer characteristics.

Lyons, Oisn F. P.; Quinn, Cian; Persoons, Tim; Murray, Darina B.

2012-11-01

84

Mesoscale effects in electrochemical conversion: coupling of chemistry to atomic- and nanoscale structure in iron-based electrodes.  

PubMed

The complex coupling of atomic, chemical, and electronic transformations across multiple length scales underlies the performance of electrochemical energy storage devices. Here, the coupling of chemistry with atomic- and nanoscale structure in iron conversion electrodes is resolved by combining pair distribution function (PDF) and small-angle X-ray scattering (SAXS) analysis for a series of Fe fluorides, oxyfluorides, and oxides. The data show that the anion chemistry of the initial electrode influences the abundance of atomic defects in the Fe atomic lattice. This, in turn, is linked to different atom mobilities and propensity for particle growth. Competitive nanoparticle growth in mixed anion systems contributes to a distinct nanostructure, without the interconnected metallic nanoparticles formed for single anion systems. PMID:24735418

Wiaderek, Kamila M; Borkiewicz, Olaf J; Pereira, Nathalie; Ilavsky, Jan; Amatucci, Glenn G; Chupas, Peter J; Chapman, Karena W

2014-04-30

85

Chemistry of the organic-rich hot core G327.3-0.6  

NASA Technical Reports Server (NTRS)

We present gas-phase abundances of species found in the organic-rich hot core G327.3-0.6. The data were taken with the Swedish-ESO Submillimetre Telescope (SEST). The 1-3 mm spectrum of this source is dominated by emission features of nitrile species and saturated organics, with abundances greater than those found in many other hot cores, including Sgr B2 and OMC-1. Population diagram analysis indicates that many species (CH3CN, C2H3CN, C2H5CN, CH3OH, etc.) have hot components that originate in a compact (2") region. Gas-phase chemical models cannot reproduce the high abundances of these molecules found in hot cores, and we suggest that they originate from processing and evaporation of icy grain mantle material. In addition, we report the first detection of vibrationally excited ethyl cyanide and the first detection of methyl mercaptan (CH3SH) outside the Galactic center.

Gibb, E.; Nummelin, A.; Irvine, W. M.; Whittet, D. C.; Bergman, P.; Ferris, J. P. (Principal Investigator)

2000-01-01

86

Chemistry of the Organic-Rich Hot Core G327.3-0.6  

NASA Astrophysics Data System (ADS)

We present gas-phase abundances of species found in the organic-rich hot core G327.3-0.6. The data were taken with the Swedish-ESO Submillimetre Telescope (SEST). The 1-3 mm spectrum of this source is dominated by emission features of nitrile species and saturated organics, with abundances greater than those found in many other hot cores, including Sgr B2 and OMC-1. Population diagram analysis indicates that many species (CH3CN, C2H3CN, C2H5CN, CH3OH, etc.) have hot components that originate in a compact (~2") region. Gas-phase chemical models cannot reproduce the high abundances of these molecules found in hot cores, and we suggest that they originate from processing and evaporation of icy grain mantle material. In addition, we report the first detection of vibrationally excited ethyl cyanide and the first detection of methyl mercaptan (CH3SH) outside the Galactic center.

Gibb, E.; Nummelin, A.; Irvine, W. M.; Whittet, D. C. B.; Bergman, P.

2000-12-01

87

Chemistry  

NSDL National Science Digital Library

Chemistry is the scientific study of matter and its interaction with other matter and with energy. It is the branch of natural science that deals with the composition of substances and their properties and reactions.

K-12 Outreach,

88

Minor and trace element chemistry of Lake Baikal, its tributaries, and surrounding hot springs  

Microsoft Academic Search

A Russian-American fieldwork effort on Lake Baikal, its tributaries, and surrounding hot springs was undertaken in June-July 1991. Here we report on aspects of major ion (Ca 2+, Mg2+, Na+, K+, Alk, Cl-, SOJ2-) and several minor and trace element (Li isotopes, Sr isotopes, Ba, Al, V, Cr, Ni, Cu, Ge, Cd, Hg, U) cycles. Our riverine data for major

K. Kenison Falkner; M. Church; G. LeBaron; D. Thouron; C. Jeandel; M. C. Stordal; G. A. Gill; R. Mortlock; P. Froelich; L.-H. Chan

1997-01-01

89

Hot precursor reactions during the collisions of gas-phase oxygen atoms with deuterium chemisorbed on Pt(100).  

PubMed

We utilized direct rate measurements and temperature programmed desorption to investigate reactions that occur during the collisions of gaseous oxygen atoms with deuterium-covered Pt(100). We find that both D2O and D2 desorb promptly when an oxygen atom beam impinges upon D-covered Pt(100) held at surface temperatures ranging from 90 to 150 K, and estimate effective cross sections of 12 and 1.8 A2, respectively, for the production of gaseous D2O and D2 at 90 K. The yields of D2O and D2 that desorb at 90 K are about 13% and 2%, respectively, of the initial D atom coverage, though most of the D2O product molecules (approximately 80%) thermalize to the surface rather than desorb at the surface temperatures studied. Increasing the surface temperature from 90 to 150 K causes the D2O desorption rate to decay more quickly during O atom exposures to the surface and results in lower yields of gaseous D2O. We attribute the production of D2O and D2 in these experiments to reactions involving intermediates that are not thermally accommodated to the surface, so-called hot precursors. The results are consistent with the production of hot D2O involving first the generation of hot OD groups from the reaction O*+D(a)-->OD*, where the asterisk denotes a hot precursor, followed by the parallel pathways OD*+D(a)-->D2O* and OD*+OD(a)-->D2O*+O(a). The final reaction contributes significantly to hot D2O production only later in the reaction period when thermalized OD groups have accumulated on the surface, and it becomes less important at higher temperature due to depletion of the OD(a) concentration by thermally activated D2O production. PMID:17430053

Kan, Heywood H; Shumbera, R Bradley; Weaver, Jason F

2007-04-01

90

Hot precursor reactions during the collisions of gas-phase oxygen atoms with deuterium chemisorbed on Pt(100)  

NASA Astrophysics Data System (ADS)

We utilized direct rate measurements and temperature programmed desorption to investigate reactions that occur during the collisions of gaseous oxygen atoms with deuterium-covered Pt(100). We find that both D2O and D2 desorb promptly when an oxygen atom beam impinges upon D-covered Pt(100) held at surface temperatures ranging from 90 to 150 K, and estimate effective cross sections of 12 and 1.8 A?2, respectively, for the production of gaseous D2O and D2 at 90 K. The yields of D2O and D2 that desorb at 90 K are about 13% and 2%, respectively, of the initial D atom coverage, though most of the D2O product molecules (~80%) thermalize to the surface rather than desorb at the surface temperatures studied. Increasing the surface temperature from 90 to 150 K causes the D2O desorption rate to decay more quickly during O atom exposures to the surface and results in lower yields of gaseous D2O. We attribute the production of D2O and D2 in these experiments to reactions involving intermediates that are not thermally accommodated to the surface, so-called hot precursors. The results are consistent with the production of hot D2O involving first the generation of hot OD groups from the reaction O*+D(a)-->OD*, where the asterisk denotes a hot precursor, followed by the parallel pathways OD*+D(a)-->D2O* and OD*+OD(a)-->D2O*+O(a). The final reaction contributes significantly to hot D2O production only later in the reaction period when thermalized OD groups have accumulated on the surface, and it becomes less important at higher temperature due to depletion of the OD(a) concentration by thermally activated D2O production.

Kan, Heywood H.; Shumbera, R. Bradley; Weaver, Jason F.

2007-04-01

91

Highly ionized atoms in cooling gas. [in model for cooling of hot Galactic corona  

NASA Technical Reports Server (NTRS)

The ionization of low density gas cooling from a high temperature was calculated. The evolution during the cooling is assumed to be isochoric, isobaric, or a combination of these cases. The calculations are used to predict the column densities and ultraviolet line luminosities of highly ionized atoms in cooling gas. In a model for cooling of a hot galactic corona, it is shown that the observed value of N(N V) can be produced in the cooling gas, while the predicted value of N(Si IV) falls short of the observed value by a factor of about 5. The same model predicts fluxes of ultraviolet emission lines that are a factor of 10 lower than the claimed detections of Feldman, Bruna, and Henry. Predictions are made for ultraviolet lines in cooling flows in early-type galaxies and clusters of galaxies. It is shown that the column densities of interest vary over a fairly narrow range, while the emission line luminosities are simply proportional to the mass inflow rate.

Edgar, Richard J.; Chevalier, Roger A.

1986-01-01

92

Kinematics and chemistry of the hot core in G20.08-0.14N  

NASA Astrophysics Data System (ADS)

We present Submillimeter Array (SMA) observations of the the massive star-forming region G20.08-0.14N at 335 and 345 GHz. With the SMA data, 41 molecular transitions were detected related to 11 molecular species and their isotopologues, including SO2, SO, C34S, NS, C17O, SiO, CH3OH, HC3N, H13CO+, HCOOCH3 and NH2CHO. In G20.08-0.14N, 10 transition lines out of the 41 detected belong to SO2, which dominates the appearance of the submillimetre-wave spectrum. To obtain the spatial kinematic distribution of molecules in G20.08-0.14N, we chose the strongest and unblended lines for the channel maps. The channel maps of C34S and SiO, together with their position-velocity diagrams, show that there are two accretion flows in G20.08-0.14N. Additionally, SiO emission shows a collimated outflow in the north-east-south-west direction. The direction of the outflow is revealed for the first time. The rotational temperature and column density of CH3OH are 105 K and 3.1 1017 cm-2, respectively. Our results confirm that a hot core is associated with G20.08-0.14N. The hot core is heated by a protostar radiation at its centre, not by external excitation from shocks. Images of the spatial distribution of different species have shown that the different molecules are located at different positions of the hot core. By comparing the spatial distributions and abundances of molecules, we discuss possible chemical processes for producing the complex sulphur-bearing, nitrogen-bearing and oxygen-bearing molecules in G20.08-0.14N.

Xu, Jin-Long; Wang, Jun-Jie

2013-05-01

93

Hot chemistry in the diffuse medium: spectral signature in the H2 rotational lines  

NASA Astrophysics Data System (ADS)

Most of the diffuse interstellar medium is cold, but it must harbor pockets of hot gas to explain the large observed abundances of molecules like CH+ and HCO+. Because they dissipate locally large amounts of kinetic energy, MHD shocks and coherent vortices in turbulence can drive endothermic chemical reactions or reactions with large activation barriers. We predict the spectroscopic signatures in the H2 rotational lines of MHD shocks and vortices and compare them to those observed with the ISO-SWS along a line of sight through the Galaxy which samples 20 magnitudes of mostly diffuse gas.

Verstraete, L.; Falgarone, E.; Pineau des Forets, G.; Flower, D.; Puget, J. L.

1999-03-01

94

The Use of Gas Chromatography and Mass Spectrometry to Introduce General Chemistry Students to Percent Mass and Atomic Mass Calculations  

ERIC Educational Resources Information Center

A general chemistry laboratory experiment is described that introduces students to instrumental analysis using gas chromatography-mass spectrometry (GC-MS), while simultaneously reinforcing the concepts of mass percent and the calculation of atomic mass. Working in small groups, students use the GC to separate and quantify the percent composition

Pfennig, Brian W.; Schaefer, Amy K.

2011-01-01

95

Getting Physical with Your Chemistry: Mechanically Investigating Local Structure and Properties of Surfaces with the Atomic Force Microscope  

ERIC Educational Resources Information Center

Atomic force microscope (AFM) investigates mechanically the chemical properties of individual molecules, surfaces, and materials using suitably designed probes. The current state of the art of AFM in terms of imaging, force measurement, and sample manipulation and its application to physical chemistry is discussed.

Heinz, William F.; Hoh, Jan H.

2005-01-01

96

The chemistry of alkali atoms on solid water: a study with MIES and UPS  

NASA Astrophysics Data System (ADS)

The chemistry of Na atoms in a multilayer aqueous environment was studied with metastable impact electron spectroscopy (MIES) and ultraviolet photoemission spectroscopy (UPS) under UHV conditions. Films of solid water were grown at 130 K on a rutile, 11 reconstructed, TiO 2(1 1 0) single crystal, and exposed to Na. The Na-water interaction was studied between 10 and 130 K. At small exposures, Na-induced water dissociation takes place whereby the Na gets ionized. Initially the outermost water layer remains intact. The number of OH species seen at the surface increases with exposure; finally, no molecular water, but only OH species can be detected with MIES and UPS. At sufficiently large exposures Na atoms are detected at the surface. We find that efficient water dissociation and Na solvation take place only above about 100 K. Under annealing, the mixed film is destroyed around 200 K; the titania surface is then covered by Na + and hydroxyl groups which desorb around 400 K.

Krischok, S.; Hfft, O.; Gnster, J.; Souda, R.; Kempter, V.

2003-04-01

97

Resonance enhanced multiphoton ionization probing of H atoms and CH 3 radicals in a hot filament chemical vapour deposition reactor  

Microsoft Academic Search

Resonance enhanced multiphoton ionization spectroscopy has been used to provide spatially resolved in situ measurements of H atom and CH3 radical relative number densities and the local gas temperature in a hot filament reactor used for diamond chemical vapour deposition (CVD). Parameters varied include the hydrocarbon (CH4 and C2H2), the hydrocarbon\\/H2 process gas mixing ratio, the total pressure and flow

James A. Smith; Moray A. Cook; Stephen R. Langford; Stephen A. Redman; Michael N. R. Ashfold

2000-01-01

98

Microelectrode studies of interstitial water chemistry and photosynthetic activity in a hot spring microbial mat  

SciTech Connect

Microelectrodes were used to measure oxygen, pH, and oxygenic photosynthetic activity in a hot spring microbial mat (Octopus Spring, Yellowstone National Park), where the cyanobacterium Synechoccus lividus and the filamentous bacteria Chloroflexus aurantiacus are the only known phototrophs. The data showed very high biological activities in the topmost layers of the microbial mat, resulting in extreme values for oxygen and pH. At a 1-mm depth at a 55 C site, oxygen and pH reached 900 micro M and 9.4, respectively, just after solar noon, whereas anoxic conditions with pH of 7.2 were measured before sunrise. Although diurnal changes between these extremes occurred over hours during a diurnal cycle microbial activity was great enough to give the same response in 1 to 2 mm after artificial shading. Oxygenic photosynthesis was confined to a 0.5- to 1.1-mm layer at sites with temperatures at or above about 50 C, with maximum activities in the 55 to 60 C region. The data suggest that S. lividus is the dominant primary producer of the mat. 30 references, 5 figures.

Revsbech, N.P.; Ward, D.M.

1984-08-01

99

The chemistry of sodium chloride involvement in processes related to hot corrosion. [in gas turbine engines  

NASA Technical Reports Server (NTRS)

Thermodynamic and mass transport calculations, and laboratory experiments elucidating the behavior of sodium chloride in combustion environments, in the deposition process, and in reactions with certain oxides on the surfaces of superalloys are summarized. It was found that some of the ingested salt is separated out of the air stream by the compressor. However, sodium chloride does pass from the compressor to the combustor where numerous chemical reactions take place. Here some of the salt is vaporized to yield gaseous sodium chloride molecules. Hydrogen and oxygen atoms present in the combustion products react with some sodium chloride to yield other gaseous species such as sodium, and a fraction of the salt remains as particulates. Both the gas phase and condensed sodium chloride can lead to sodium sulfate formation by various routes, all of which involve reaction with sulfur oxides and oxygen. In addition to contributing to the formation of sodium sulfate, the sodium chloride can contribute to corrosion directly.

Stearns, C. A.; Kohl, F. J.; Fryburg, G. C.

1979-01-01

100

Substrate Temperature Dependence of the Photoresist Removal Rate Using Atomic Hydrogen Generated by a Hot-Wire Tungsten Catalyst  

NASA Astrophysics Data System (ADS)

Instead of photoresist removal methods using chemicals, we investigated an environmentally friendly removal method using atomic hydrogen generated by decomposing hydrogen molecules by contact with a hot-wire tungsten catalyst. We set the distance between the catalyst and the photoresist substrate (DCS) at 20, 60, 100 and 120 mm and evaluated the apparent activation energy (EAP) for the reaction between photoresist and atomic hydrogen at each DCS. The EAP was determined from Arrhenius plots of the photoresist removal rate against the average substrate temperature. When DCS was 20 and 60 mm, EAP decreased with increasing catalyst temperature (\\mathit{WT}=2040--2420 C) and was not constant. However, when DCS was 100 and 120 mm, EAP was nearly constant at 19 1 kJ/mol without depending on \\mathit{WT}. We might obtain the activation energy of about 19 kJ/mol in the reaction of photoresist with atomic hydrogen.

Yamamoto, Masashi; Maruoka, Takeshi; Kono, Akihiko; Horibe, Hideo; Umemoto, Hironobu

2010-01-01

101

Moderation and absorption effects on hot replacement reactions of sup 38 Cl atoms in mixtures of o-dichlorobenzene and hexafluorobenzene  

SciTech Connect

Conditions are given for the equivalence of the Estrup-Wolfgang description of the hot atom reaction kinetics with the first-order Hurwitz approximation in the neutron slowing down theory. Conclusions are drawn for the applicability of this approach for describing hot atom replacement processes in reactive mixtures. Analytical and numerical calculations were carried out to explain an unusual concentration dependence of {sup 38}Cl-for-Cl substitution, found experimentally in liquid binary mixtures of o-dichlorobenzene and hexafluorobenzene.

Berei, K.; Gado, J.; Kereszturi, A.; Szatmary, Z.; Vass, Sz. (Central Research Institute for Physics of the Hungarian Academy of Sciences, Budapest (Hungary))

1990-03-22

102

Atomic scale structure and chemistry of interfaces by Z-contrast imaging and electron energy loss spectroscopy in the stem  

SciTech Connect

The macroscopic properties of many materials are controlled by the structure and chemistry at grain boundaries. A basic understanding of the structure-property relationship requires a technique which probes both composition and chemical bonding on an atomic scale. High-resolution Z-contrast imaging in the scanning transmission electron microscope (STEM) forms an incoherent image in which changes in atomic structure and composition across an interface can be interpreted directly without the need for preconceived atomic structure models. Since the Z-contrast image is formed by electrons scattered through high angles, parallel detection electron energy loss spectroscopy (PEELS) can be used simultaneously to provide complementary chemical information on an atomic scale. The fine structure in the PEEL spectra can be used to investigate the local electronic structure and the nature of the bonding across the interface. In this paper we use the complimentary techniques of high resolution Z-contrast imaging and PEELS to investigate the atomic structure and chemistry of a 25{degree} symmetric tilt boundary in a bicrystal of the electroceramic SrTiO{sub 3}.

McGibbon, M.M.; Browning, N.D.; Chisholm, M.F.; McGibbon, A.J.; Pennycook, S.J. [Oak Ridge National Lab., TN (United States); Ravikumar, V.; Dravid, V.P. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering

1994-05-01

103

Influence of atomic layer deposition chemistry on high- k dielectrics for charge trapping memories  

NASA Astrophysics Data System (ADS)

In this work we report the performance of the SiO 2/Si 3N 4/HfO 2 and SiO 2/Si 3N 4/ZrO 2 stacks with emphasis on the influence of atomic layer deposition chemistry used for forming the HfO 2 and ZrO 2 blocking layers. Two Hf precursors were employed - tetrakis(ethylmethylamino)hafnium (TEMAH) and bis(methylcyclopentadienyl)methoxymethyl hafnium (HfD-04). For ZrO 2, tetrakis(ethylmethylamino)zirconium (TEMAZ) and bis(methylcyclopentadienyl)methoxymethyl zirconium (ZrD-04) were used as metal precursors. Ozone was used as the oxygen source. The structural characteristics of the stacks were examined by transmission electron microscopy and grazing incidence X-ray diffraction. The electrical properties of the stacks were studied using platinum-gated capacitor structures. The memory performance of the stacks was evaluated by write/erase (W/E) measurements, endurance and retention testing. Endurance measurements revealed the most important difference between the stacks. The films grown from TEMAH and TEMAZ could withstand a significantly higher number of W/E pulses (>3 10 5 in the 10 V/-11 V, 10 ms regime), in comparison to the stacks made from HfD-04 and ZrD-04 precursors (<5 10 3 W/E cycles). This difference in endurance characteristics is attributed mainly to the different deposition temperatures suited for these two precursors and the nature of the layer formed at the Si 3N 4/HfO 2 and the Si 3N 4/ZrO 2 interfaces.

Nikolaou, Nikolaos; Dimitrakis, Panagiotis; Normand, Pascal; Ioannou-Sougleridis, Vassilios; Giannakopoulos, Konstantinos; Mergia, Konstantina; Kukli, Kaupo; Niinist, Jaakko; Ritala, Mikko; Leskel, Markku

2012-02-01

104

Synthesis of a novel restricted access chiral stationary phase based on atom transfer radical polymerization and click chemistry for the analysis of chiral drugs in biological matrices  

Microsoft Academic Search

A novel chiral restricted access material was synthesized via a combination of atom transfer radical polymerization (ATRP) and click chemistry. Poly(2-methyl-3-butyn-2-ol methacrylate) (pMBMA) was grafted onto porous silica gel by a surface-initiated ATRP in order to synthesize an inner layer for ?-cyclodextrin (?-CD) immobilization. The azide-modified ?-CD was bound to pMBMA by click chemistry. The results demonstrate that click chemistry

Huaisong Wang; Ping Jiang; Min Zhang; Xiangchao Dong

2011-01-01

105

Effect of Ballistic-Type Hot Atom Adsorption Mechanism on the Phase Diagram of Monomer Dimer CO O2 Surface Catalytic Reaction: A Monte Carlo Simulation  

NASA Astrophysics Data System (ADS)

We investigate the effect of the ballistic mechanism on the phase diagram using a square surface. While using this mechanism whenever an O2 molecule hits a randomly vacant selected site, the molecule breaks up into atomic form and then executes a ballistic flight. The paths of the two oxygen atoms are taken exactly to be opposite to each other, i.e. anti-parallel, and the ranges of the atoms are taken to be equal, i.e. they may fly up to 1 or 1.414 or 2 of the atomic spacing from the site of impact. Four cases have been studied on the basis of the range of hot atoms. The range of the hot oxygen atoms executing a ballistic flight might be up to the first nearest neighbourhood (1 atomic spacing from the site of impact), the second nearest neighbourhood (1.414 atomic spacing from the site of impact), the third nearest neighbourhood (2 atomic spacing from the site of impact), known as cases a, b, and c, respectively, while for case d the range of the oxygen atoms executing the ballistic flight might be up to 1 atomic spacing or 1.414 atomic spacing or 2 atomic spacing from the site of impact. The steady reactive window is observed and the continuous transition disappears. As soon as the CO partial pressure departs from zero, the production of CO2 is observed, which clearly verifies the experimental observation.

Khalid, M.; Khan M., K.; Qaisrani U., A.; Malik N., Q.

2004-06-01

106

Environmental Assessment for decontaminating and decommissioning the General Atomics Hot Cell Facility. Final [report  

SciTech Connect

This EA evaluates the proposed action to decontaminate and decommission GA`s hot cell facility in northern San Diego, CA. This facility has been used for DOE and commercial nuclear R&D for > 30 years. About 30,000 cubic feet of decontamination debris and up to 50,000 cubic feet of contaminated soil are to be removed. Low-level radioactive waste would be shipped for disposal. It was determined that the proposal does not constitute a major federal action significantly affecting the human environment according to NEPA; therefore, a finding of no significant impact is made, and an environmental impact statement is not required.

NONE

1995-08-01

107

In situ observation of thermomigration of Sn atoms to the hot end of 96.5Sn-3Ag-0.5Cu flip chip solder joints  

NASA Astrophysics Data System (ADS)

In this study, we investigated the phenomenon of thermomigration in 96.5Sn-3Ag-0.5Cu flip chip solder joints at an ambient temperature of 150 C. We observed mass protrusion on the chip side (hot end), indicating that Sn atoms moved to the hot end, and void formation on the substrate side (cold end). The diffusion markers also moved to the substrate side, in the same direction of the vacancy flux, indicating that the latter played a dominant role during the thermomigration process. The molar heat of transport (Q*) of the Sn atoms was 3.38 kJ/mol.

Ouyang, Fan-Yi; Kao, C.-L.

2011-12-01

108

Bonds Between Metal Atoms: A New Mode of Transition Metal Chemistry.  

ERIC Educational Resources Information Center

Discusses polynuclear metal clusters (containing two or more metal atoms bonded to one another as well as to nonmetallic elements), including their formation and applications. Studies of bonds between metal atoms reveal superconductors, organic-reaction catalysts, and photosensitive complexes that may play a role in solar energy. (JN)

Cotton, F. Albert; Chisholm, Malcolm H.

1982-01-01

109

Atomic hydrogen escape rate due to charge exchange with hot plasmaspheric ions  

NASA Technical Reports Server (NTRS)

Data on ion and electron temperatures and concentrations to several thousand kilometers of altitude were obtained from the Atmosphere Explorer C satellite for 1974 and to 850 km from Arecibo incoherent scatter radar measurements. These data were used to normalize diffusive equilibrium profiles. From these profiles and by using the neutral atmospheric model of Jacchia (1971) and a new hydrogen model, the charge-exchange-induced neutral hydrogen escape fluxes for equatorial and middle latitudes were calculated. The data confirm earlier estimates that the charge exchange loss is more important than Jeans escape for the earth. It is also found that inside the plasmapause this charge exchange process with hot plasmapheric ions is the major production and loss process for the satellite population in the hydrogen geocorona.

Maher, L. J.; Tinsley, B. A.

1977-01-01

110

LETTER TO THE EDITOR: Hot electrons in the tunnelling ionization of atoms  

NASA Astrophysics Data System (ADS)

A compact analytical generalization of the Landau - Dykhne approach is derived that includes rescattering of electrons in the tunnelling ionization of atoms. It is used for calculations of electron energy spectra in the high-energy region. Most of the essential features of recent measurements are reproduced analytically, that is, the onset, the extent and the relative height of the plateau. Coulomb correction is taken into account in the calculations.

Smirnov, M. B.; Krainov, V. P.

1998-06-01

111

Chemistry of the outer planets  

NASA Technical Reports Server (NTRS)

Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

Scattergood, Thomas W.

1992-01-01

112

Atomic scale structure and chemistry of interfaces by Z-contrast imaging and electron energy loss spectroscopy in the STEM  

SciTech Connect

The macroscopic properties of many materials are controlled by the structure and chemistry at the grain boundaries. A basic understanding of the structure-property relationship requires a technique which probes both composition and chemical bonding on an atomic scale. The high-resolution Z-contrast imaging technique in the scanning transmission electron microscope (STEM) forms an incoherent image in which changes in atomic structure and composition can be interpreted intuitively. This direct image allows the electron probe to be positioned over individual atomic columns for parallel detection electron energy loss spectroscopy (PEELS) at a spatial resolution approaching 0.22nm. The bonding information which can be obtained from the fine structure within the PEELS edges can then be used in conjunction with the Z-contrast images to determine the structure at the grain boundary. In this paper we present 3 examples of correlations between the structural, chemical and electronic properties at materials interfaces in metal-semiconductor systems, superconducting and ferroelectric materials.

McGibbon, M.M.; Browning, N.D.; Chisholm, M.F.; Pennycook, S.J.

1993-12-01

113

The Development of Dalton's Atomic Theory as a Case Study in the History of Science: Reflections for Educators in Chemistry  

NASA Astrophysics Data System (ADS)

The inclusion of the history of science in science curriculaand specially, in the curricula of science teachersis a trend that has been followed in several countries. The reasons advanced for the study of the history of science are manifold. This paper presents a case study in the history of chemistry, on the early developments of John Daltons atomic theory. Based on the case study, several questions that are worth discussing in educational contexts are pointed out. It is argued that the kind of history of science that was made in the first decades of the twentieth century (encyclopaedic, continuist, essentially anachronistic) is not appropriate for the development of the competences that are expected from the students of sciences in the present. Science teaching for current days will benefit from the approach that may be termed the new historiography of science.

Viana, Hlio Elael Bonini; Porto, Paulo Alves

2010-01-01

114

Experiences and Reflections about Teaching Atomic Structure in a Jigsaw Classroom in Lower Secondary School Chemistry Lessons  

NASA Astrophysics Data System (ADS)

This article describes and discusses an example of how atomic structure can be taught in lower secondary chemistry using a modified jigsaw-classroom method. The lesson was taught in grades 9 and 10 (age range 15 17 years) chemistry in 13 learning groups with a total of 313 students in various grammar, middle, and comprehensive schools in Germany. The written evaluation of the lesson focused on determining the students opinions on the teaching methods that were used. Emphasis was on gathering information from the students viewpoint. Did the students think that these methods could make science lessons more attractive? Could these methods help to promote more active student learning, cooperative learning, or communicative and social abilities? Additional data that were derived from a cognitive test and teacher feedback are also presented. The results of the study show that teaching methods like the jigsaw classroom have potential to improve students attitude towards science. The results may also indicate that it is appropriate to demand that student-oriented and cooperative-learning methods be used more often in secondary level science education.

Eilks, Ingo

2005-02-01

115

Relativistic Quantum Chemistry of Heavy Ions and Hadronic Atomic Systems: Spectra and Energy Shifts  

NASA Astrophysics Data System (ADS)

The levels energies and energy shifts are calculated for superheavy Li-like ions and some kaonic atoms on the basis of the gauge-invariant QED perturbation theory (PT) with an account of nuclear, exchange-correlation and radiative effects.

Glushkov, A. V.; Khetselius, O.; Gurnitskaya, E.; Loboda, A.; Sukharev, D.

2009-03-01

116

Shippingport Atomic Power Station steam generator tube damage and water chemistry control (1965--1975)  

Microsoft Academic Search

The four stainless steel tubed steam generators in the Shippingport Atomic Power Station were replaced in 1964 with larger, horizontal, NiCrFe Alloy 600 tubed units consistent with a power uprating of the plant. Each of the four Alloy 600 tubed units experienced tube leakage attributed to corrosion by water treatment chemicals (sodium phosphates) which concentrated locally on the tubes in

Singley

1978-01-01

117

Calculation of the Relative Chemical Stabilities of Proteins as a Function of Temperature and Redox Chemistry in a Hot Spring  

Microsoft Academic Search

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

Jeffrey M. Dick; Everett L. Shock

2011-01-01

118

State-specific reactions of atomic transition-metal ions with H/sub 2/, HD, and D/sub 2/: effects of d orbitals on chemistry  

SciTech Connect

Guided ion beam mass spectrometry has been used to examine the kinetic energy dependence of reactions of atomic ions of the entire first-row transition-metal series with molecular hydrogen. By varying the conditions under which the ions are formed, results for specific electronic states can be obtained. The periodic trends in the chemistry and derived thermodynamic information are summarized. The results can be understood by considering the spin and orbital occupation of the atomic ions.

Elkind, J.L.; Armentrout, P.B.

1987-04-09

119

Chemistry of glass-ceramic to metal bonding for header applications: III. Treatment of Inconel 718 to eliminate hot cracking during laser welding  

SciTech Connect

A study was conducted to determine the weldability of Inconel 718 shells. Two pieces of Inconel 718 were welded together with a Hastelloy B-2 filler. The Inconel surface condition was varied by heat-treating and by using several different cleaning processes. The surface chemistry following each modification was determined by Auger spectroscopy. Each conditioned Inconel hollow cylinder (shell) was also checked for pulsed laser weldability by looking for hot cracking. Abraded and solvent-cleaned Inconel shells were found to have thin surface oxides and were also found to be weldable. Heat-treated shells were shown to have a thick complex oxide layer consisting primarily of chromium, titanium, aluminum, and niobium, and were not found to be weldable. Variations of an ''oxide removal'' treatment were used and found to be ineffective in removing all of the heat-treated surface oxides. The predominant oxide left after the various removal treatments was a thick aluminum oxide laced with alkali, alkaline earth and nickel oxides, sulfides (or sulfates), and/or chlorides. Inconel shells after being treated by these oxide removal steps and variations were also found not be be laser weldable. This oxide was finally removed by electropolishing, and the resulting surface was found to be crack-free after welding. Auger analysis of fractured surfaces in hot-cracked regions revealed that the surfaces consisted of an oxide similar to that left after the removal steps, but without the aluminum oxide. Thus, it was concluded that hot cracking in heat-treated, oxide-removed Inconel 718 is due to one or all of the following: alkali, alkaline earth and nickel oxides, sulfides (or sulfates), and/or chlorides that accumulate in the cracked area.

Moddeman, W.E.; Jones, W.H.; Koeller, T.L.; Craven, S.M.; Kramer, D.P.

1987-04-24

120

A Low Temperature Neutron Irradiation Facility for Studies in Hot-Atom Chemistry and Radiation Damage Studies in Materials.  

National Technical Information Service (NTIS)

A low temperature neutron irradiation facility has been constructed and tested for the AMRA research reactor. A description of the apparatus is given and results obtained for the low temperature (-80 C) neutron irradiation of mixed crystals of sodium brom...

J. R. Hobbs C. W. Owens

1966-01-01

121

Probing the oxidation chemistry of half-sandwich iridium complexes with oxygen atom transfer reagents.  

PubMed

The new complexes [Ir(Cp*)(phpy)3,5-bis(trifluoromethyl)benzonitrile](+) (1-NCAr(+)) and [Ir(Cp*)(phpy)(styrene)](+) (1-Sty(+), Cp* = ?(5)-pentamethylcyclopentadienyl, phpy = 2-phenylene-?C(1')-pyridine-?N) were prepared as analogues of reported iridium water oxidation catalysts, to study their reactions with oxygen atom transfer (OAT) reagents at low temperatures. In no case was the desired product, an Ir(V)oxo complex, observed by spectroscopy. Instead, ligand oxidation was implicated. Oxidation of 1-NCAr(+) with the OAT reagent dimethyldioxirane (DMDO) yielded dioxygen when analyzed by GC, but formation of a heterogeneous or paramagnetic species was simultaneously observed. This amplifies uncertainty over the actual identity of iridium catalysts in the harsh oxidizing conditions required for water oxidation. Catalyst stability was then assessed for a reported styrene epoxidation mediated by [Ir(Cp*)(phpy)(OH2)](+) (1-OH2(+)). It was found that the OAT reagent iodosobenzene (PhIO) extensively oxidized the organic ligands of 1-OH2(+). Acetic acid was detected as a decomposition product. In addition, both the molecular structure and the aqueous electrochemistry of 1-OH2(+) are described for the first time. Oxidative scans revealed rapid decomposition of the complex. All of the above experiments indicate that degradation of the organic ligands in catalysts built with the Ir(Cp*)(phpy) framework are facile under oxidizing conditions. In separate experiments designed to promote ligand substitution, an unexpected silver-bridged, dinuclear Ir(III) species with terminal hydrides, [{Ir(Cp*)(phpy)H}2Ag](+) (2), was discovered. The source of Ag(+) for complex 2 was identified as AgCl. PMID:24063760

Turlington, Christopher R; Harrison, Daniel P; White, Peter S; Brookhart, Maurice; Templeton, Joseph L

2013-10-01

122

Probing the Structure and Chemistry of Perylenetetracarboxylic Dianhydride on Graphene Before and After Atomic Layer Deposition of Alumina  

PubMed Central

The superlative electronic properties of graphene suggest its use as the foundation of next generation integrated circuits. However, this application requires precise control of the interface between graphene and other materials, especially the metal oxides that are commonly used as gate dielectrics. Towards that end, organic seeding layers have been empirically shown to seed ultrathin dielectric growth on graphene via atomic layer deposition (ALD), although the underlying chemical mechanisms and structural details of the molecule/dielectric interface remain unknown. Here, confocal resonance Raman spectroscopy is employed to quantify the structure and chemistry of monolayers of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on graphene before and after deposition of alumina with the ALD precursors trimethyl aluminum (TMA) and water. Photoluminescence measurements provide further insight into the details of the growth mechanism, including the transition between layer-by-layer growth and island formation. Overall, these results reveal that PTCDA is not consumed during ALD, thereby preserving a well-defined and passivating organic interface between graphene and deposited dielectric thin films.

Johns, James E.; Karmel, Hunter J.; Alaboson, Justice M. P.; Hersam, Mark C.

2012-01-01

123

Synthesis of a novel restricted access chiral stationary phase based on atom transfer radical polymerization and click chemistry for the analysis of chiral drugs in biological matrices.  

PubMed

A novel chiral restricted access material was synthesized via a combination of atom transfer radical polymerization (ATRP) and click chemistry. Poly(2-methyl-3-butyn-2-ol methacrylate) (pMBMA) was grafted onto porous silica gel by a surface-initiated ATRP in order to synthesize an inner layer for ?-cyclodextrin (?-CD) immobilization. The azide-modified ?-CD was bound to pMBMA by click chemistry. The results demonstrate that click chemistry provides an effective route for the immobilization of ?-CD for chiral discrimination. A second ATRP reaction was then used to graft external poly(glycidyl methacrylate) (pGMA) layer onto the silica gel. The external hydrophilic layer was subsequently created by hydrolysis of the epoxy groups of the pGMA. This bi-layer grafted material exhibited both enantioseparation and protein exclusion. It can be used for the efficient separation of chiral compounds in biological samples with direct injection into an HPLC system. PMID:21256499

Wang, Huaisong; Jiang, Ping; Zhang, Min; Dong, Xiangchao

2011-03-01

124

Hot Canyon  

SciTech Connect

This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon."

None

2012-06-18

125

Hot Canyon  

SciTech Connect

This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon."

None

2012-01-01

126

Hot Canyon  

ScienceCinema

This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon."

None

2013-03-01

127

Chemistry of Cu(acac){sub 2} on Ni(110) and Cu(110) surfaces: Implications for atomic layer deposition processes  

SciTech Connect

The thermal chemistry of copper(II)acetylacetonate, Cu(acac){sub 2}, on Ni(110) and Cu(110) single-crystal surfaces was probed under vacuum by using x-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Some data for acetylacetone (Hacac, CH{sub 3}COCH{sub 2}COCH{sub 3}) adsorbed on Ni(110) are also reported as reference. Chemical transformations were identified in several steps covering a temperature range from 150 K to at least 630 K. The desorption of Hacac and a 3-oxobutanal (CH{sub 3}COCH{sub 2}CHO) byproduct was observed first at 150 and 180 K on Ni(110) and at 160 and 185 K on Cu(110), respectively. Partial loss of the acetylacetonate (acac) ligands and a likely change in adsorption geometry are seen next, with the possible production of HCu(acac), which desorbs at 200 and 235 K from the nickel and copper surfaces, respectively. Molecular Cu(acac){sub 2} desorption is observed on both surfaces at approximately 300 K, probably from recombination of Cu(acac) and acac surface species. The remaining copper atoms on the surface lose their remaining acac ligands to the substrate and become reduced directly to metallic copper. At the same time, the organic ligands follow a series of subsequent surface reactions, probably involving several C-C bond-scissions, to produce other fragments, additional Hacac and HCu(acac) in the gas phase in the case of the copper surface, and acetone on nickel. A significant amount of acac must nevertheless survive on the surface to high temperatures, because Hacac peaks are seen in the TPD at about 515 and 590 K and the C 1s XPS split associated with acac is seen up to close to 500 K. In terms of atomic layer deposition processes, this suggests that cycles could be design to run at such temperatures as long as an effective hydrogenation agent is used as the second reactant to remove the surface acac as Hacac. Only a small fraction of carbon is left behind on Ni after heating to 800 K, whereas more carbon and additional oxygen remains on the surface in the case of Cu.

Ma Qiang; Zaera, Francisco [Department of Chemistry, University of California, Riverside, California 92521 (United States)

2013-01-15

128

Atoms Chemistry review  

NSDL National Science Digital Library

See the videos we watched in class (or review for your next exam) here To play the review game we will do in class, click below then click on Periodic Table Review Eureeka home To watch videos Sodium Video Element song Element song Alkali metal video Brainiac metalsSchool Island ...

Mckinnon

2009-06-11

129

LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM  

SciTech Connect

This report describes the installation, testing, and acceptance of the Waste Treatment and Immobilization Plant (WTP) procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste (HLW) samples in a hot cell environment. The work was completed by the Analytical Process Development (APD) group in accordance with Task Order 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S Laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

SEIDEL CM; JAIN J; OWENS JW

2009-02-23

130

LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM  

SciTech Connect

This report describes the installation, testing and acceptance of the Waste Treatment and Immobilization Plant procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste samples in a hot cell environment. The 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

LOCKREM LL; OWENS JW; SEIDEL CM

2009-03-26

131

Atomic-scale structure and chemistry of interfaces by Z-contrast imaging and electron energy loss spectroscopy in the STEM  

SciTech Connect

The macroscopic properties of many materials are controlled by the structure and chemistry at grain boundaries. A basic understanding of the structure-property relationship requires a technique which probes both composition and chemical bonding on an atomic scale. The high-resolution Z-contrast imaging technique in the scanning transmission electron microscope (STEM) forms an incoherent image in which changes in atomic structure and composition can be interpreted intuitively. This direct image allows the electron probe to be positioned over individual atomic columns for parallel detection electron energy loss spectroscopy (EELS) at a spatial resolution approaching 0.22nm. In this paper we have combined the structural information available in the Z-contrast images with the bonding information obtained from the fine structure within the EELS edges to determine the grain boundary structure in a SrTiO{sub 3} bicrystal.

McGibbon, M.M.; Browning, N.D.; Chisholm, M.F.; Pennycook, S.J. [Oak Ridge National Lab., TN (United States); Ravikumar, V.; Dravid, V.P. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering

1993-12-01

132

Theoretical Modeling of Interstellar Chemistry  

NASA Technical Reports Server (NTRS)

The chemistry of complex interstellar organic molecules will be described. Gas phase processes that may build large carbon-chain species in cold molecular clouds will be summarized. Catalytic reactions on grain surfaces can lead to a large variety of organic species, and models of molecule formation by atom additions to multiply-bonded molecules will be presented. The subsequent desorption of these mixed molecular ices can initiate a distinctive organic chemistry in hot molecular cores. The general ion-molecule pathways leading to even larger organics will be outlined. The predictions of this theory will be compared with observations to show how possible organic formation pathways in the interstellar medium may be constrained. In particular, the success of the theory in explaining trends in the known interstellar organics, in predicting recently-detected interstellar molecules, and, just as importantly, non-detections, will be discussed.

Charnley, Steven

2009-01-01

133

Atomic scale structure and chemistry of interfaces by Z-contrast imaging and electron energy loss spectroscopy in the STEM.  

National Technical Information Service (NTIS)

The macroscopic properties of many materials are controlled by the structure and chemistry at the grain boundaries. A basic understanding of the structure-property relationship requires a technique which probes both composition and chemical bonding on an ...

M. M. McGibbon N. D. Browning M. F. Chisholm S. J. Pennycook

1993-01-01

134

The role of NaCl in flame chemistry, in the deposition process, and in its reactions with protective oxides as related to hot corrosion  

NASA Technical Reports Server (NTRS)

Sodium chloride is believed to be the primary source of turbine engine contamination that contributes to hot corrosion. The behavior of NaCl-containing aerosols ingested with turbine intake air is very complex; some of the NaCl may vaporize during combustion while some may remain as particulates. The NaCl can lead to Na2SO4 formation by several possible routes or it can contribute to corrosion directly. Hydrogen or oxygen atom reaction with NaCl(c) was shown to result in the release of Na(g). Gaseous NaCl in flames can be partially converted to gaseous Na2SO4 by homogeneous reactions. The remaining gaseous NaCl and other Na-containing molecules can act as sodium carriers for condensate deposition of Na2SO4 on cool surfaces. A frozen boundary layer theory was developed to predict the rates of deposition. The condensed phase NaCl can be converted directly to condensed Na2SO4 by reaction with sulfur oxides and O2. Reaction of gaseous NaCl with Cr2O3 results in the vapor phase transport of chromium by the formation of complex Cr-containing gaseous molecules. Similar gaseous complexes are formed with molybdenum. The presence of gaseous NaCl was shown to affect the oxidation kinetics of Ni-Cr alloys. It also causes changes in the surface morphology of Al2O3 scales formed on Al-containing alloys.

Kohl, F. J.; Stearns, C. A.

1979-01-01

135

Reaction Studies of Hot Silicon, Germanium and Carbon Atoms: Progress Report, February 1, 1985-July 31, 1987.  

National Technical Information Service (NTIS)

The experimental approach toward attaining the goals of this research program is briefly outlined, and the progress made in the 1985 to 1987 period is reviewed in sections entitled: (1) reactions of recoiling silicon atoms; (2) reactions of recoiling carb...

P. P. Gaspar

1987-01-01

136

Hot precursor reactions during the collisions of gas-phase oxygen atoms with deuterium chemisorbed on Pt(100)  

Microsoft Academic Search

We utilized direct rate measurements and temperature programmed desorption to investigate reactions that occur during the collisions of gaseous oxygen atoms with deuterium-covered Pt(100). We find that both D2O and D2 desorb promptly when an oxygen atom beam impinges upon D-covered Pt(100) held at surface temperatures ranging from 90 to 150 K, and estimate effective cross sections of 12 and

Heywood H. Kan; R. Bradley Shumbera; Jason F. Weaver

2007-01-01

137

Chemistry on Stamps.  

ERIC Educational Resources Information Center

Suggests how postage stamps can be incorporated into chemistry teaching. Categories considered include emergence of chemistry as a science, metric system, atoms (and molecules and ions), stoichiometry, energy relationships in chemical systems, chemical bonding, nuclear chemistry, biochemistry, geochemistry, matter (gases, liquids, and solids),

Schreck, James O.

1986-01-01

138

Experiences and Reflections about Teaching Atomic Structure in a Jigsaw Classroom in Lower Secondary School Chemistry Lessons  

ERIC Educational Resources Information Center

The study investigates the students opinions on learning in a jigsaw classroom and enquiring on what they think about jigsaw classroom having the potential to make chemistry learning more attractive and whether it can help them to improve their communicative and social skills. The study was carried out using a lesson design for teaching an

Eilks, Ingo

2005-01-01

139

The Development of Dalton's Atomic Theory as a Case Study in the History of Science: Reflections for Educators in Chemistry  

ERIC Educational Resources Information Center

The inclusion of the history of science in science curricula--and specially, in the curricula of science teachers--is a trend that has been followed in several countries. The reasons advanced for the study of the history of science are manifold. This paper presents a case study in the history of chemistry, on the early developments of John

Viana, Helio Elael Bonini; Porto, Paulo Alves

2010-01-01

140

Hot Sauce Hot Spots  

NSDL National Science Digital Library

In this activity, learners model hot spot island formation, orientation and progression with condiments. Learners squirt a thick condiment sauce on a coarsely woven fabric to model how volcanic island hot spots form.

Muller, Eric

2007-01-01

141

Single atom hot-spots at Au-Pd nanoalloys for electrocatalytic H2O2 production.  

PubMed

A novel strategy to direct the oxygen reduction reaction to preferentially produce H(2)O(2) is formulated and evaluated. The approach combines the inertness of Au nanoparticles toward oxidation, with the improved O(2) sticking probability of isolated transition metal "guest" atoms embedded in the Au "host". DFT modeling was employed to screen for the best alloy candidates. Modeling indicates that isolated alloying atoms of Pd, Pt, or Rh placed within the Au surface should enhance the H(2)O(2) production relative to pure Au. Consequently, Au(1-x)Pd(x) nanoalloys with variable Pd content supported on Vulcan XC-72 were prepared to investigate the predicted selectivity toward H(2)O(2) production for Au alloyed with Pd. It is demonstrated that increasing the Pd concentration to 8% leads to an increase of the electrocatalytic H(2)O(2) production selectivity up to nearly 95%, when the nanoparticles are placed in an environment compatible with that of a proton exchange membrane. Further increase of Pd content leads to a drop in H(2)O(2) selectivity, to below 10% for x = 0.5. It is proposed that the enhancement in H(2)O(2) selectivity is caused by the presence of individual surface Pd atoms surrounded by gold, whereas surface ensembles of contiguous Pd atoms support H(2)O formation. The results are discussed in the context of exergonic electrocatalytic H(2)O(2) synthesis in Polymer Electrolyte Fuel Cells for the simultaneous cogeneration of chemicals and electricity, the latter a credit to production costs. PMID:22023652

Jirkovsk, Jakub S; Panas, Itai; Ahlberg, Elisabet; Halasa, Matej; Romani, Simon; Schiffrin, David J

2011-12-01

142

Average atom transport properties for pure and mixed species in the hot and warm dense matter regimes  

NASA Astrophysics Data System (ADS)

The Kubo-Greenwood formulation for calculation of optical conductivities with an average atom model is extended to calculate thermal conductivities. The method is applied to species and conditions of interest for inertial confinement fusion. For the mixed species studied, the partial pressure mixing rule is used. Results including pressures, dc, and thermal conductivities are compared to ab initio calculations. Agreement for pressures is good, for both the pure and mixed species. For conductivities, it is found that the ad hoc renormalization method with line broadening, described in the text, gives best agreement with the ab initio results. However, some disagreement is found and the possible reasons for this are discussed.

Starrett, C. E.; Clrouin, J.; Recoules, V.; Kress, J. D.; Collins, L. A.; Hanson, D. E.

2012-10-01

143

Average atom transport properties for pure and mixed species in the hot and warm dense matter regimes  

SciTech Connect

The Kubo-Greenwood formulation for calculation of optical conductivities with an average atom model is extended to calculate thermal conductivities. The method is applied to species and conditions of interest for inertial confinement fusion. For the mixed species studied, the partial pressure mixing rule is used. Results including pressures, dc, and thermal conductivities are compared to ab initio calculations. Agreement for pressures is good, for both the pure and mixed species. For conductivities, it is found that the ad hoc renormalization method with line broadening, described in the text, gives best agreement with the ab initio results. However, some disagreement is found and the possible reasons for this are discussed.

Starrett, C. E.; Kress, J. D.; Collins, L. A.; Hanson, D. E. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States); Clerouin, J. [CEA, DAM, DIF, 91297 Arpajon Cedex (France); Recoules, V. [CEA, DAM, DIF, 91297 Arpajon Cedex (France); LUTH UMR8102, Observatoire de Paris, CNRS, Universite Paris Diderot, 92195 Meudon (France)

2012-10-15

144

The Origin of Carbon-bearing Volatiles in Surprise Valley Hot Springs in the Great Basin: Carbon Isotope aud Water Chemistry Characterizations  

NASA Technical Reports Server (NTRS)

There are numerous hydrothermal fields within the Great Basin of North America, some of which have been exploited for geothermal resources. With methane and other carbon-bearing compounds being observed, in some cases with high concentrations, however, their origins and formation conditions remain unknown. Thus, studying hydrothermal springs in this area provides us an opportunity to expand our knowledge of subsurface (bio)chemical processes that generate organic compounds in hydrothermal systems, and aid in future development and exploration of potential energy resources as well. While isotope measurement has long been used for recognition of their origins, there are several secondary processes that may generate variations in isotopic compositions: oxidation, re-equilibration of methane and other alkanes with CO2, mixing with compounds of other sources, etc. Therefore, in addition to isotopic analysis, other evidence, including water chemistry and rock compositions, are necessary to identify volatile compounds of different sources. Surprise Valley Hot Springs (SVHS, 4132'N, 1205'W), located in a typical basin and range province valley in northeastern California, is a terrestrial hydrothermal spring system of the Great Basin. Previous geophysical studies indicated the presence of clay-rich volcanic and sedimentary rocks of Tertiary age beneath the lava flows in late Tertiary and Quaternary. Water and gas samples were collected for a variety of chemical and isotope composition analyses, including in-situ pH, alkalinity, conductivity, oxidation reduction potential (ORP), major and trace elements, and C and H isotope measurements. Fluids issuing from SVHS can be classified as Na-(Cl)-SO4 type, with the major cation and anion being Na+ and SO4 2-, respectively. Thermodynamic calculation using ORP and major element data indicated that sulfate is the most dominant sulfur species, which is consistent with anion analysis results. Aquifer temperatures at depth estimated by both dissolved SiO2 and Na-K-Ca geothermometers are in the range of 125.0 to 135.4 oC, and higher than the values measured at orifices (77.3 to 90.0 oC). CO2 and homologs of straight chain alkanes (C1-C5) were identified in gas samples. Carbon isotope values of alkanes increase with carbon numbers. The 13C fractionation between CO2 and dissolved inorganic carbon suggests they are out of carbon isotope equilibrium. The hypothesis regarding the formation of carbon-bearing compounds in SVHS may involve two processes: 1) Under high heat flow conditions which are caused by regional faulting and crustal extension, original high molecular weight organic compounds (kerogens) in clay-rich rocks decomposed to generate methane and other alkane homologs. 2) The SVHS area is associated with outflow structures, and distant from the heat source. Anaerobic oxidation of methane (AOM) with sulfate at shallow depth (< 90 oC) is suggested as being responsible for the generation of CO2 in SVHS.

Fu, Qi; Socki, Richard A.; Niles, Paul B.; Romanek, Christopher; Datta, Saugata; Darnell, Mike; Bissada, Adry K.

2013-01-01

145

The Origin of Carbon-bearing Volatiles in Surprise Valley Hot Springs in the Great Basin: Carbon Isotope and Water Chemistry Characterizations  

NASA Technical Reports Server (NTRS)

There are numerous hydrothermal fields within the Great Basin of North America, some of which have been exploited for geothermal resources. With methane and other carbon-bearing compounds being observed, in some cases with high concentrations, however, their origins and formation conditions remain unknown. Thus, studying hydrothermal springs in this area provides us an opportunity to expand our knowledge of subsurface (bio)chemical processes that generate organic compounds in hydrothermal systems, and aid in future development and exploration of potential energy resources as well. While isotope measurement has long been used for recognition of their origins, there are several secondary processes that may generate variations in isotopic compositions: oxidation, re-equilibration of methane and other alkanes with CO2, mixing with compounds of other sources, etc. Therefore, in addition to isotopic analysis, other evidence, including water chemistry and rock compositions, are necessary to identify volatile compounds of different sources. Surprise Valley Hot Springs (SVHS, 41 deg 32'N, 120 deg 5'W), located in a typical basin and range province valley in northeastern California, is a terrestrial hydrothermal spring system of the Great Basin. Previous geophysical studies indicated the presence of clay-rich volcanic and sedimentary rocks of Tertiary age beneath the lava flows in late Tertiary and Quaternary. Water and gas samples were collected for a variety of chemical and isotope composition analyses, including in-situ pH, alkalinity, conductivity, oxidation reduction potential (ORP), major and trace elements, and C and H isotope measurements. Fluids issuing from SVHS can be classified as Na-(Cl)-SO4 type, with the major cation and anion being Na+ and SO4(2-), respectively. Thermodynamic calculation using ORP and major element data indicated that sulfate is the most dominant sulfur species, which is consistent with anion analysis results. Aquifer temperatures at depth estimated by both dissolved SiO2 and Na-K-Ca geothermometers are in the range of 125.0 to 135.4 C, and higher than the values measured at orifices (77.3 to 90.0 C). CO2 and homologs of straight chain alkanes (C1-C5) were identified in gas samples. Carbon isotope values of alkanes increase with carbon numbers. The C-13 fractionation between CO2 and dissolved inorganic carbon suggests they are out of carbon isotope equilibrium. The hypothesis regarding the formation of carbon-bearing compounds in SVHS may involve two processes: 1) Under high heat flow conditions which are caused by regional faulting and crustal extension, original high molecular weight organic compounds (kerogens) in clay-rich rocks decomposed to generate methane and other alkane homologs. 2) The SVHS area is associated with outflow structures, and distant from the heat source. Anaerobic oxidation of methane (AOM) with sulfate at shallow depth (< 90 C) is suggested as being responsible for the generation of CO2 in SVHS.

Fu, Qi; Socki, Richard A.; Niles, Paul B.; Romanek, Christopher; Datta, Saugata; Darnell, Mike; Bissada, Adry K.

2013-01-01

146

Use of a CO{sub 2} pellet non-destructive cleaning system to decontaminate radiological waste and equipment in shielded hot cells at the Bettis Atomic Power Laboratory  

SciTech Connect

This paper details how the Bettis Atomic Power Laboratory modified and utilized a commercially available, solid carbon dioxide (CO{sub 2}) pellet, non-destructive cleaning system to support the disposition and disposal of radioactive waste from shielded hot cells. Some waste materials and equipment accumulated in the shielded hot cells cannot be disposed directly because they are contaminated with transuranic materials (elements with atomic numbers greater than that of uranium) above waste disposal site regulatory limits. A commercially available CO{sub 2} pellet non-destructive cleaning system was extensively modified for remote operation inside a shielded hot cell to remove the transuranic contaminants from the waste and equipment without generating any secondary waste in the process. The removed transuranic contaminants are simultaneously captured, consolidated, and retained for later disposal at a transuranic waste facility.

Bench, T.R.

1997-05-01

147

Substrate Chemistry-Dependent Conformations of Single Laminin Molecules on Polymer Surfaces are Revealed by the Phase Signal of Atomic Force Microscopy  

PubMed Central

The conformation of single laminin molecules adsorbed on synthetic substrates is directly observed making use of the phase magnitude in tapping mode atomic force microscopy (AFM). With AFM, it is not possible to differentiate the proteins on the substrate if use is made of the height signal, since the roughness of the material becomes of the same order of magnitude as the adsorbed protein, typically 10 nm height. This work shows how AFM can be exploited to reveal protein conformation on polymer materials. Different laminin morphologies are observed on a series of different copolymers based on ethyl acrylate and hydroxyethyl acrylate as a function of the surface density of ?OH groups: from globular to completely extended morphologies of the protein molecules are obtained, and the onset of laminin network formation on some substrates can be clearly identified. The results stress the importance of the underlying synthetic substrate's surface chemistry for the biofunctional conformation of adsorbed proteins.

Hernandez, Jose Carlos Rodriguez; Salmeron Sanchez, Manuel; Soria, Jose Miguel; Gomez Ribelles, Jose Luis; Monleon Pradas, Manuel

2007-01-01

148

How Many Atomic Layers of Zinc Are in a Galvanized Iron Coating? An Experiment for General Chemistry Laboratory  

ERIC Educational Resources Information Center

This article describes an experiment using a novel gasometric assembly to determine the thickness and number of atomic layers of zinc coating on galvanized iron substrates. Students solved this problem through three stages. In the first stage, students were encouraged to find a suitable acidic concentration through the guided-inquiry approach. In

Yang, Shui-Ping

2007-01-01

149

Learning about Atoms, Molecules, and Chemical Bonds: A Case Study of Multiple-Model Use in Grade 11 Chemistry.  

ERIC Educational Resources Information Center

Reports in detail on a year-long case study of multiple-model use at grade 11. Suggests that students who socially negotiated the shared and unshared attributes of common analogical models for atoms, molecules, and chemical bonds used these models more consistently in their explanations. (Author/CCM)

Harrison, Allan G.; Treagust, David F.

2000-01-01

150

Interfacial chemistry of poly(methyl methacrylate) arising from exposure to vacuum-ultraviolet light and atomic oxygen.  

PubMed

We herein report on the chemical and physical changes that occur in thin films of poly(methyl methacrylate), PMMA, induced by exposure to high-energy vacuum ultraviolet radiation and a supersonic beam of neutral, ground electronic state O((3)P) atomic oxygen. A combination of in situ quartz crystal microbalance and in situ Fourier-transform infrared reflection-absorption spectroscopy were used to determine the photochemical reaction kinetics and mechanisms during irradiation. The surface morphological changes were measured with atomic force microscopy. The results showed there was no enhancement in the mass loss rate during simultaneous exposure of vacuum ultraviolet (VUV) radiation and atomic oxygen. Rather, the rate of mass loss was impeded when the polymer film was exposed to both reagents. This study elucidates the kinetics of photochemical and oxidative reaction for PMMA, and shows that the synergistic effect involving VUV irradiation and exposure to ground state atomic oxygen depends substantially on the relative fluxes of these reagents. PMID:20722441

Yuan, Hanqiu; Killelea, Daniel R; Tepavcevic, Sanja; Kelber, Scott I; Sibener, S J

2011-04-28

151

Kinetics of Fast Atoms in the Terrestrial Atmosphere  

NASA Technical Reports Server (NTRS)

This report summarizes our investigations performed under NASA Grant NAG5-8058. The three-year research supported by the Geospace Sciences SR&T program (Ionospheric, Thermospheric, and Mesospheric Physics) has been designed to investigate fluxes of energetic oxygen and nitrogen atoms in the terrestrial thermosphere. Fast atoms are produced due to absorption of the solar radiation and due to coupling between the ionosphere and the neutral thermospheric gas. We have investigated the impact of hot oxygen and nitrogen atoms on the thermal balance, chemistry and radiation properties of the terrestrial thermosphere. Our calculations have been focused on the accurate quantitative description of the thermalization of O and N energetic atoms in collisions with atom and molecules of the ambient neutral gas. Upward fluxes of oxygen and nitrogen atoms, the rate of atmospheric heating by hot oxygen atoms, and the energy input into translational and rotational-vibrational degrees of atmospheric molecules have been evaluated. Altitude profiles of hot oxygen and nitrogen atoms have been analyzed and compared with available observational data. Energetic oxygen atoms in the terrestrial atmosphere have been investigated for decades, but insufficient information on the kinetics of fast atmospheric atoms has been a main obstacle for the interpretation of observational data and modeling of the hot geocorona. The recent development of accurate computational methods of the collisional kinetics is seen as an important step in the quantitative description of hot atoms in the thermosphere. Modeling of relaxation processes in the terrestrial atmosphere has incorporated data of recent observations, and theoretical predictions have been tested by new laboratory measurements.

Kharchenko, Vasili A.; Dalgarno, A.; Mellott, Mary (Technical Monitor)

2002-01-01

152

Application of the atoms in molecules theory and computational chemistry in mass spectrometry analysis of 1,4-naphthoquinone derivatives.  

PubMed

Mass spectrometry analysis of 2-(acylamino)-1,4-naphthoquinone derivatives was carried out using electrospray ionization ion source in combination with tandem mass spectrometry. Protonated molecules were dissociated by application of the collision-induced dissociation (CID), and the protonation sites were suggested on the basis of the HOMO, molecular electrostatic potential map (MEP), proton affinity, and Fukui functions calculated by B3LYP/6-31+G(d,p). The main fragmentation mechanisms undergone by the protonated ions were elucidated on the basis of energy, geometry, and topology analysis of equilibrium geometries. Compounds exhibiting only aliphatic hydrogens at the lateral chain undergo interesting ketene elimination. On the other hand, only the benzoylium ion formation is detected for 2-benzoylamino-1,4-naphthoquinone. The bonds geometric and atoms in molecules parameters give evidence that acidic hydrogen atoms play an important role in the fragmentation pathways. PMID:21714561

Vessecchi, Ricardo; Lopes, Jos N C; Lopes, Norberto P; Galembeck, Srgio E

2011-11-17

153

Zen Hot Dog Molecules  

ERIC Educational Resources Information Center

Substituted cycloalkanes with one branch illustrating each topic in an instructional unit can serve as summaries or reviews in courses of organic chemistry. The hungry Zen master told the hot dog vendor to make him one with everything. You can do the same for your students.

Ryan, Dennis

2009-01-01

154

Zen Hot Dog Molecules  

NASA Astrophysics Data System (ADS)

Substituted cycloalkanes with one branch illustrating each topic in an instructional unit can serve as summaries or reviews in courses of organic chemistry. The hungry Zen master told the hot dog vendor to make him one with everything. You can do the same for your students.

Ryan, Dennis

2009-04-01

155

The Role of NaCl in Flame Chemistry, in the Deposition Process, and in Its Reactions with Protective Oxides as Related to Hot Corrosion.  

National Technical Information Service (NTIS)

Sodium chloride is believed to be the primary source of turbine engine contamination that contributes to hot corrosion. The behavior of NaCl-containing aerosols ingested with turbine intake air is very complex; some of the NaCl may vaporize during combust...

F. J. Kohl C. A. Stearns

1979-01-01

156

Double nuclear magnetic resonance and crystal chemistry at the lattice positions of diamagnetic atoms, both structural, and foreign  

Microsoft Academic Search

Double nuclear magnetic resonance (DNMR) with Jeener's pulsed sequence on proton and fluorine frequencies was used to investigate the electric quadrupole interactions of (i) 23Na in Na2Cd(SO4)22H2O, B {2\\/0}=218.51 kHz, B {2\\/2}=985 kHz, (ii) of 23Na, which enter the crystal, CaF2: Na+ (0.07 wt. %) B {2\\/0}=85.70.5 kHz, trigonal position, and (iii) 23Na which are near the foreign atom in

V. D. Shchepkin; D. I. Vainshtein; R. A. Dautov; V. M. Vinokurov

1980-01-01

157

Double nuclear magnetic resonance and crystal chemistry at the lattice positions of diamagnetic atoms, both structural, and foreign  

Microsoft Academic Search

Double nuclear magnetic resonance (DNMR) with Jeener's pulsed sequence on proton and fluorine frequencies was used to investigate the electric quadrupole interactions of (i) 23Na in Na2Cd(SO4)22H2O, B20=218.51 kHz, B22=985 kHz, (ii) of 23Na, which enter the crystal, CaF2: Na+ (0.07 wt. %) B20=85.70.5 kHz, trigonal position, and (iii) 23Na which are near the foreign atom in NaF:Ca2+ (0.02 wt.%)

V. D. Shchepkin; D. I. Vainshtein; R. A. Dautov; V. M. Vinokurov

1980-01-01

158

Atmospheric chemistry of t-CF3CH=CHCl: products and mechanisms of the gas-phase reactions with chlorine atoms and hydroxyl radicals.  

PubMed

FTIR-smog chamber techniques were used to study the products and mechanisms of the Cl atom and OH radical initiated oxidation of trans-3,3,3-trifluoro-1-chloro-propene, t-CF(3)CH=CHCl, in 700 Torr of air or N(2)/O(2) diluent at 296 2 K. The reactions of Cl atoms and OH radicals with t-CF(3)CH=CHCl occur via addition to the >C=C< double bond; chlorine atoms add 15 5% at the terminal carbon and 85 5% at the central carbon, OH radicals add approximately 40% at the terminal carbon and 60% at the central carbon. The major products in the Cl atom initiated oxidation of t-CF(3)CH=CHCl were CF(3)CHClCHO and CF(3)C(O)CHCl(2), minor products were CF(3)CHO, HCOCl and CF(3)COCl. The yields of CF(3)C(O)CHCl(2), CF(3)CHClCOCl and CF(3)COCl increased at the expense of CF(3)CHO, HCOCl and CF(3)CHClCHO as the O(2) partial pressure was increased over the range 10-700 Torr. Chemical activation plays a significant role in the fate of CF(3)CH(O)CHCl(2) and CF(3)CClHCHClO radicals. In addition to reaction with O(2) to yield CF(3)COCl and HO(2) the major competing fate of CF(3)CHClO is Cl elimination to give CF(3)CHO (not C-C bond scission as previously thought). As part of this study k(Cl + CF(3)C(O)CHCl(2)) = (2.3 0.3) 10(-14) and k(Cl + CF(3)CHClCHO) = (7.5 2.0) 10(-12) cm(3) molecule(-1) s(-1) were determined using relative rate techniques. Reaction with OH radicals is the major atmospheric sink for t-CF(3)CH=CHCl. Chlorine atom elimination giving the enol CF(3)CH=CHOH appears to be the sole atmospheric fate of the CF(3)CHCHClOH radicals. The yield of CF(3)COOH in the atmospheric oxidation of t-CF(3)CH=CHCl will be negligible (<2%). The results are discussed with respect to the atmospheric chemistry and environmental impact of t-CF(3)CH=CHCl. PMID:22187719

Andersen, M P Sulbaek; Nielsen, O J; Hurley, M D; Wallington, T J

2012-02-01

159

Surface chemistry, structure, and electronic properties from microns to the atomic scale of axially doped semiconductor nanowires.  

PubMed

Using both synchrotron-based photoemission electron microscopy/spectroscopy and scanning tunneling microscopy/spectroscopy, we obtain a complete picture of the surface composition, morphology, and electronic structure of InP nanowires. Characterization is done at all relevant length scales from micrometer to nanometer. We investigate nanowire surfaces with native oxide and molecular adsorbates resulting from exposure to ambient air. Atomic hydrogen exposure at elevated temperatures which leads to the removal of surface oxides while leaving the crystalline part of the wire intact was also studied. We show how surface chemical composition will seriously influence nanowire electronic properties. However, opposite to, for example, Ge nanowires, water or sulfur molecules adsorbed on the exterior oxidized surfaces are of less relevance. Instead, it is the final few atomic layers of the oxide which plays the most significant role by strongly negatively doping the surface. The InP nanowires in air are rather insensitive to their chemical surroundings in contrast to what is often assumed for nanowires. Our measurements allow us to draw a complete energy diagram depicting both band gap and differences in electron affinity across an axial nanowire p-n junction. Our findings thus give a robust set of quantitative values relating surface chemical composition to specific electronic properties highly relevant for simulating the performance of nanoscale devices. PMID:23062066

Hjort, Martin; Wallentin, Jesper; Timm, Rainer; Zakharov, Alexei A; Hkanson, Ulf; Andersen, Jesper N; Lundgren, Edvin; Samuelson, Lars; Borgstrm, Magnus T; Mikkelsen, Anders

2012-11-27

160

Hot Science: Hot rocks  

NSDL National Science Digital Library

This site explores two kinds of igneous rock, pumice and granite. Pumice is an example of extrusive igneous rock, while granite is an example of intrusive igneous rock. Intrusive indicates that the magma was forced close to the surface, but then cooled more slowly underneath the surface. The question, "How hot is Lava?" is linked to an explanation of the heat of lava, why it must be sampled when it is very hot, and how the samples are taken.

161

Metabolic conditions of lactating Friesian cows during the hot season in the Po valley. 2. Blood minerals and acid-base chemistry  

Microsoft Academic Search

In two consecutive summers, 21 and 18 cows respectively were monitored for acid-base chemistry and some blood minerals, to\\u000a assess their variation according to the level of heat stress at different stages of lactation. During both years, the cows\\u000a were monitored according to their lactation phase (early, mid-, and late) at the beginning of the summer. Climatic conditions\\u000a were described

Luigi Calamari; Fabio Abeni; Ferdinando Calegari; Luigi Stefanini

2007-01-01

162

Models of Hot Cores with Complex Molecules  

NASA Astrophysics Data System (ADS)

Recent models of hot cores have incorporated previously-uninvestigated chemical pathways that lead to the formation of complex organic molecules (COMs; i.e. species containing six or more atoms). In addition to the gas-phase ion-molecule reactions long thought to dominate the organic chemistry in these regions, these models now include photodissociation-driven grain surface reaction pathways that can also lead to COMs. Here, simple grain surface ice species photodissociate to form small radicals such as OH, CH3, CH2OH, CH3O, HCO, and NH2. These species become mobile at temperatures above 30 K during the warm-up phase of star formation. Radical-radical addition reactions on grain surfaces can then form an array of COMs that are ejected into the gas phase at higher temperatures. Photodissociation experiments on pure and mixed ices also show that these complex molecules can indeed form from simple species. The molecules predicted to form from this type of chemistry reasonably match the organic inventory observed in high mass hot cores such as Sgr B2(N) and Orion-KL. However, the relative abundances of the observed molecules differ from the predicted values, and also differ between sources. Given this disparity, it remains unclear whether grain surface chemistry governed by photodissociation is the dominant mechanism for the formation of COMs, or whether other unexplored gas-phase reaction pathways could also contribute significantly to their formation. The influence that the physical conditions of the source have on the chemical inventory also remains unclear. Here we overview the chemical pathways for COM formation in hot cores. We also present new modeling results that begin to narrow down the possible routes for production of COMs based on the observed relative abundances of methyl formate (HCOOCH3) and its C2H4O2 structural isomers.

Widicus Weaver, Susanna L.; Garrod, Robin T.; Laas, Jacob C.; Herbst, Eric

2011-12-01

163

XPS study of the surface chemistry of conventional hot-dip galvanised pure Zn, galvanneal and ZnAl alloy coatings on steel  

Microsoft Academic Search

This study uses X-ray photoelectron spectroscopy (XPS) to analyse the outer surfaces of galvanised, galfan and galvanneal metallic coatings obtained by hot dipping. Considerable aluminium segregation towards the surface, principally as Al2O3, has been seen in all the studied coatings. The aluminium content on the surface was surprisingly similar to or even greater than the zinc content, which is the

S Feliu; V Barranco

2003-01-01

164

A study of gas chemistry during hot-filament vapor deposition of diamond films using methane\\/hydrogen and acetylene\\/hydrogen gas mixtures  

Microsoft Academic Search

The composition of the reaction gases in a hot-filament reactor for chemical vapor deposition of diamond films was analyzed using a gas chromatograph coupled with a quartz microprobe. Concentrations of several hydrocarbons were determined as functions of filament temperature (FT) and the position of the probe relative to the filament for two feed gases, methane\\/hydrogen and acetylene\\/hydrogen. The diamond growth

Ching-Hsong Wu; M. A. Tamor; T. J. Potter; E. W. Kaiser

1990-01-01

165

Double nuclear magnetic resonance and crystal chemistry at the lattice positions of diamagnetic atoms, both structural, and foreign  

NASA Astrophysics Data System (ADS)

Double nuclear magnetic resonance (DNMR) with Jeener's pulsed sequence on proton and fluorine frequencies was used to investigate the electric quadrupole interactions of (i) 23Na in Na2Cd(SO4)22H2O, B {2/0}=218.51 kHz, B {2/2}=985 kHz, (ii) of 23Na, which enter the crystal, CaF2: Na+ (0.07 wt. %) B {2/0}=85.70.5 kHz, trigonal position, and (iii) 23Na which are near the foreign atom in NaF:Ca2+ (0.02 wt.%) B {2/0}=86.70.5 kHz, tetragonal position. Some details of DNMR experiments are analyzed. The conditions for maximum transfer of a Zeeman energy to a dipole-dipole reservoir are described for multispin systems and some crystal hydrates. The angular dependence of the Hamiltonian containing the spherical tensor operators of second rank was obtained for all possible orientations of a local coordinate system relative to a laboratory system.

Shchepkin, V. D.; Vainshtein, D. I.; Dautov, R. A.; Vinokurov, V. M.

1980-12-01

166

Heterogeneous catalysis of a copper-coated atomic force microscopy tip for direct-write click chemistry.  

PubMed

We report a constructive scanning probe lithography method that uses heterogeneous copper-coated atomic force microscopy tips to catalyze azide-alkyne cycloadditions (CuAAC) between solvated terminal alkyne molecules and azide-terminated self-assembled monolayers on silicon surfaces. Spatially controlled surface functionalization was carried out successfully with 50 mM ethanolic solutions of small molecules bearing terminal alkyne groups--propargylamine, 4-pentynoic acid, and an alkynyl-oligoethyleneoxide. We observed that reaction occurs only where the copper tip is in contact with an azide-terminated surface resulting in features with linewidths on the order of 50 nm. The extent of surface functionalization, as measured by changes in surface topography and lateral force microscopy, depends on the scanning force (31-350 nN) and scanning speed, with significant surface patterning observed even at speeds as high as 64 microm/s. In contrast with related SPL techniques, this approach affords a direct-write lithographic approach to constructively modifying and patterning surfaces at the nanoscale without the need for auxiliary reagents. All that is required is (1) an azide surface, (2) a solution of a terminal alkyne, and (3) a copper-coated AFM tip. These advantages allow the direct attachment of a potentially limitless library of molecules that bear terminal alkyne functionalities, including biomolecules, under relatively mild conditions, with sub-100 nm spatial resolution. PMID:19388653

Paxton, Walter F; Spruell, Jason M; Stoddart, J Fraser

2009-05-20

167

A COUPLED CHEMISTRY-EMISSION MODEL FOR ATOMIC OXYGEN GREEN AND RED-DOUBLET EMISSIONS IN THE COMET C/1996 B2 HYAKUTAKE  

SciTech Connect

The green (5577 Angstrom-Sign ) and red-doublet (6300, 6364 Angstrom-Sign ) lines are prompt emissions of metastable oxygen atoms in the {sup 1}S and {sup 1}D states, respectively, that have been observed in several comets. The value of the intensity ratio of green to red-doublet (G/R ratio) of 0.1 has been used as a benchmark to identify the parent molecule of oxygen lines as H{sub 2}O. A coupled chemistry-emission model is developed to study the production and loss mechanisms of the O({sup 1}S) and O({sup 1}D) atoms and the generation of red and green lines in the coma of C/1996 B2 Hyakutake. The G/R ratio depends not only on photochemistry, but also on the projected area observed for cometary coma, which is a function of the dimension of the slit used and the geocentric distance of the comet. Calculations show that the contribution of photodissociation of H{sub 2}O to the green (red) line emission is 30%-70% (60%-90%), while CO{sub 2} and CO are the next potential sources contributing 25%-50% (<5%). The ratio of the photoproduction rate of O({sup 1} S) to O({sup 1} D) would be around 0.03 ({+-}0.01) if H{sub 2}O is the main source of oxygen lines, whereas it is {approx}0.6 if the parent is CO{sub 2}. Our calculations suggest that the yield of O({sup 1} S) production in the photodissociation of H{sub 2}O cannot be larger than 1%. The model-calculated radial brightness profiles of the red and green lines and G/R ratios are in good agreement with the observations made on the comet Hyakutake in 1996 March.

Bhardwaj, Anil; Raghuram, Susarla, E-mail: bhardwaj_spl@yahoo.com, E-mail: anil_bhardwaj@vssc.gov.in, E-mail: raghuramsusarla@gmail.com [Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum 695022 (India)

2012-03-20

168

Interstellar chemistry  

PubMed Central

In the past half century, radioastronomy has changed our perception and understanding of the universe. In this issue of PNAS, the molecular chemistry directly observed within the galaxy is discussed. For the most part, the description of the molecular transformations requires specific kinetic schemes rather than chemical thermodynamics. Ionization of the very abundant molecular hydrogen and atomic helium followed by their secondary reactions is discussed. The rich variety of organic species observed is a challenge for complete understanding. The role and nature of reactions involving grain surfaces as well as new spectroscopic observations of interstellar and circumstellar regions are topics presented in this special feature.

Klemperer, William

2006-01-01

169

Atomic-Scale Design of Iron Fischer-Tropsch Catalysts: A Combined Computational Chemistry, Experimental, and Microkinetic Modeling Approach  

SciTech Connect

Efforts during this second year focused on four areas: (1) continued searching and summarizing of published Fischer-Tropsch synthesis (FTS) mechanistic and kinetic studies of FTS reactions on iron catalysts; (2) investigation of CO adsorption/desorption and temperature programmed hydrogenation (TPH) of carbonaceous species after FTS on unsupported iron and alumina-supported iron catalysts; (3) activity tests of alumina-supported iron catalysts in a fixed bed reactor; (4) sequential design of experiments, for the collection of rate data in a Berty CSTR reactor, and nonlinear-regression analysis to obtain kinetic parameters. Literature sources describing mechanistic and kinetic studies of Fischer-Tropsch synthesis on iron catalysts were compiled in a review. Temperature-programmed desorption/reaction methods (the latter using mass-spectrometry detection and also thermogravimetric analyzer (TGA)) were utilized to study CO adsorption/-desorption on supported and unsupported iron catalysts. Molecular and dissociative adsorptions of CO occur on iron catalysts at 25-150 C. The amounts adsorbed and bond strengths of adsorption are influenced by supports and promoters. That CO adsorbs dissociatively on polycrystalline Fe at temperatures well below those of FT reaction indicates that CO dissociation is facile and unlikely to be the rate-limiting step during FTS. Carbonaceous species formed after FT reaction for only 5 minutes at 200 C were initially hydrogenated under mild, isothermal condition (200 C and 1 atm), followed by TPH to 800 C. During the mild, isothermal hydrogenation, only about 0.1-0.2 mL of atomic carbon is apparently removed, while during TPH to 800 C multilayer equivalents of atomic, polymeric, carbidic, and graphitic carbons are removed. Rates of CO conversion on alumina-supported iron catalysts at 220-260 C and 20 atm are correlated well by a Langmuir-Hinshelwood expression, derived assuming carbon hydrogenation to CH and OH recombination to water to be rate-determining steps. In the coming year, studies will focus on quantitative determination of the rates of kinetically-relevant elementary steps on Fe catalysts with/without K and Pt promoters and at various levels of Al{sub 2}O{sub 3} support, providing a database for understanding (1) effects of promoter and support on elementary kinetic parameters and (2) for validation of computational models that incorporate effects of surface structure and promoters. Kinetic parameters will be incorporated into a microkinetics model, enabling prediction of rate without invoking assumptions, e.g. of a rate-determining step or a most-abundant surface intermediate. Calculations using periodic, self-consistent Density Functional Theory (DFT) methods were performed on two model surfaces: (1) Fe(110) with 1/4 ML subsurface carbon, and (2) Fe(110) with 1/4 ML Pt adatoms. Reaction networks for FTS on these systems were characterized in full detail by evaluating the thermodynamics and kinetics of each elementary step. We discovered that subsurface C stabilizes all the reactive intermediates, in contrast to Pt, which destabilizes most of them. A comparative study of the reactivities of the modified-Fe surfaces against pure Fe is expected to yield a more comprehensive understanding of promotion mechanisms for FTS on Fe.

Manos Mavrikakis; James A. Dumesic; Amit A. Gokhale; Rahul P. Nabar; Calvin H. Bartholomew; Hu Zou; Brian Critchfield

2006-03-03

170

Presenting the Bohr Atom.  

ERIC Educational Resources Information Center

Discusses the importance of teaching the Bohr atom at both freshman and advanced levels. Focuses on the development of Bohr's ideas, derivation of the energies of the stationary states, and the Bohr atom in the chemistry curriculum. (SK)

Haendler, Blanca L.

1982-01-01

171

Manipulation of gold colloidal nanoparticles with atomic force microscopy in dynamic mode: influence of particle-substrate chemistry and morphology, and of operating conditions  

PubMed Central

Summary One key component in the assembly of nanoparticles is their precise positioning to enable the creation of new complex nano-objects. Controlling the nanoscale interactions is crucial for the prediction and understanding of the behaviour of nanoparticles (NPs) during their assembly. In the present work, we have manipulated bare and functionalized gold nanoparticles on flat and patterned silicon and silicon coated substrates with dynamic atomic force microscopy (AFM). Under ambient conditions, the particles adhere to silicon until a critical drive amplitude is reached by oscillations of the probing tip. Beyond that threshold, the particles start to follow different directions, depending on their geometry, size and adhesion to the substrate. Higher and respectively, lower mobility was observed when the gold particles were coated with methyl (CH3) and hydroxyl (OH) terminated thiol groups. This major result suggests that the adhesion of the particles to the substrate is strongly reduced by the presence of hydrophobic interfaces. The influence of critical parameters on the manipulation was investigated and discussed viz. the shape, size and grafting of the NPs, as well as the surface chemistry and the patterning of the substrate, and finally the operating conditions (temperature, humidity and scan velocity). Whereas the operating conditions and substrate structure are shown to have a strong effect on the mobility of the particles, we did not find any differences when manipulating ordered vs random distributed particles.

Darwich, Samer; Rao, Akshata; Gnecco, Enrico; Jayaraman, Shrisudersan; Haidara, Hamidou

2011-01-01

172

Atmospheric chemistry of CF 3CH 2OCH 3: Reaction with chlorine atoms and OH radicals, kinetics, degradation mechanism and global warming potential  

NASA Astrophysics Data System (ADS)

FTIR smog chamber techniques were used to measure k(Cl + CF 3CH 2OCH 3) = (2.28 0.44) 10 -11 and k(OH + CF 3CH 2OCH 3) = (4.9 1.3) 10 -13 cm 3 molecule -1 s -1 in 700 Torr total pressure of air at 296 2 K. The atmospheric lifetime of CF 3CH 2OCH 3 is estimated at 25 days. Reaction of Cl atoms with CF 3CH 2OCH 3 proceeds 79 4% at the sbnd CH 3 group and 22 2% at the sbnd CH 2sbnd group. Reaction with OH radicals proceeds 55 5% at the sbnd CH 3 group yielding CF 3CH 2OCHO and 45 5% at the sbnd CH 2sbnd group yielding COF 2 and CH 3OCHO as primary oxidation products. The infrared spectrum of CF 3CH(O)OCH 3 was measured and a global warming potential GWP 100 = 8 was estimated. The atmospheric chemistry and environmental impact of CF 3CH 2OCH 3 is discussed in context of the use of hydrofluoroethers as CFC substitutes.

sterstrm, Freja From; Nielsen, Ole John; Sulbaek Andersen, Mads P.; Wallington, Timothy J.

2012-02-01

173

Exotic Atoms and Muonium  

NASA Astrophysics Data System (ADS)

In exotic atoms, one of the atomic electrons is replaced by a negatively charged particle, whereas muonium consists of a positive muon and an electron. After a general review of the theoretical and experimental aspects, the present knowledge of this field is summarized. These include muonium and the application of the muon spin resonance method in solid-state physics and chemistry, muonic hydrogen atoms, muonic molecules and muon-catalyzed fusion, pionic hydrogen atoms and their use in chemistry, testing quantum electrodynamics on heavy muonic atoms, measuring particle and nuclear properties using hadronic atoms, and testing basic symmetry principles with antiprotonic helium atoms and antihydrogen.

Horvth, D.

174

Atomic-Scale Design of Iron Fischer-Tropsch Catalysts; A Combined Computational Chemistry, Experimental, and Microkinetic Modeling Approach  

SciTech Connect

This work focuses on (1) searching/summarizing published Fischer-Tropsch synthesis (FTS) mechanistic and kinetic studies of FTS reactions on iron catalysts; (2) preparation and characterization of unsupported iron catalysts with/without potassium/platinum promoters; (3) measurement of H{sub 2} and CO adsorption/dissociation kinetics on iron catalysts using transient methods; (3) analysis of the transient rate data to calculate kinetic parameters of early elementary steps in FTS; (4) construction of a microkinetic model of FTS on iron, and (5) validation of the model from collection of steady-state rate data for FTS on iron catalysts. Three unsupported iron catalysts and three alumina-supported iron catalysts were prepared by non-aqueous-evaporative deposition (NED) or aqueous impregnation (AI) and characterized by chemisorption, BET, temperature-programmed reduction (TPR), extent-of-reduction, XRD, and TEM methods. These catalysts, covering a wide range of dispersions and metal loadings, are well-reduced and relatively thermally stable up to 500-600 C in H{sub 2} and thus ideal for kinetic and mechanistic studies. Kinetic parameters for CO adsorption, CO dissociation, and surface carbon hydrogenation on these catalysts were determined from temperature-programmed desorption (TPD) of CO and temperature programmed surface hydrogenation (TPSR), temperature-programmed hydrogenation (TPH), and isothermal, transient hydrogenation (ITH). A microkinetic model was constructed for the early steps in FTS on polycrystalline iron from the kinetic parameters of elementary steps determined experimentally in this work and from literature values. Steady-state rate data were collected in a Berty reactor and used for validation of the microkinetic model. These rate data were fitted to 'smart' Langmuir-Hinshelwood rate expressions derived from a sequence of elementary steps and using a combination of fitted steady-state parameters and parameters specified from the transient measurements. The results provide a platform for further development of microkinetic models of FTS on Fe and a basis for more precise modeling of FTS activity of Fe catalysts. Calculations using periodic, self-consistent Density Functional Theory (DFT) methods were performed on various realistic models of industrial, Fe-based FTS catalysts. Close-packed, most stable Fe(110) facet was analyzed and subsequently carbide formation was found to be facile leading to the choice of the FeC(110) model representing a Fe facet with a sub-surface C atom. The Pt adatom (Fe{sup Pt}(110)) was found to be the most stable model for our studies into Pt promotion and finally the role of steps was elucidated by recourse to the defected Fe(211) facet. Binding Energies(BEs), preferred adsorption sites and geometries for all FTS relevant stable species and intermediates were evaluated on each model catalyst facet. A mechanistic model (comprising of 32 elementary steps involving 19 species) was constructed and each elementary step therein was fully characterized with respect to its thermochemistry and kinetics. Kinetic calculations involved evaluation of the Minimum Energy Pathways (MEPs) and activation energies (barriers) for each step. Vibrational frequencies were evaluated for the preferred adsorption configuration of each species with the aim of evaluating entropy-changes, pre exponential factors and serving as a useful connection with experimental surface science techniques. Comparative analysis among these four facets revealed important trends in their relative behavior and roles in FTS catalysis. Overall the First Principles Calculations afforded us a new insight into FTS catalysis on Fe and modified-Fe catalysts.

Manos Mavrikakis; James Dumesic; Rahul Nabar; Calvin Bartholonew; Hu Zou; Uchenna Paul

2008-09-29

175

Atomic Orbitals  

NSDL National Science Digital Library

The Atomic Orbitals Web site "was established as part of an (ongoing) project at Purdue University to develop 'visualization modules' for general chemistry students." Using the Chime plug-in, which allows unique and stunning visualizations, visitors can learn what an atomic orbital is; what the 1s, 2s, 3s, 2p, 3p, and 3d orbitals are; what hybrid orbitals are; and more. The combination of easy-to-read descriptions and educational graphics make the site a great learning resource for high school and even college level chemistry students.

1969-12-31

176

Computational chemistry  

NASA Technical Reports Server (NTRS)

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.

Arnold, J. O.

1987-01-01

177

Industrial Hygiene Chemistry Course; Course Evaluator.  

National Technical Information Service (NTIS)

A set of 60 multiple choice questions on Industrial Hygiene Chemistry is presented for evaluation of a one week Industrial Hygiene Chemistry course. Questions relate to electrochemical reactions, spectrometry, gas chromatography, x-ray diffraction, atomic...

1975-01-01

178

Partial Characterization of a Novel Amphibian Hemoglobin as a Model for Graduate Student Investigation on Peptide Chemistry, Mass Spectrometry, and Atomic Force Microscopy  

ERIC Educational Resources Information Center

Graduate students in chemistry, and in biological and biomedical fields must learn the fundamentals and practices of peptide and protein chemistry as early as possible. A project-oriented approach was conducted by first-year M.Sc and Ph.D students in biological sciences. A blind glass slide containing a cellular smear and an aqueous cellular

Bemquerer, Marcelo P.; Macedo, Jessica K. A.; Ribeiro, Ana Carolina J.; Carvalho, Andrea C.; Silva, Debora O. C.; Braz, Juliana M.; Medeiros, Kelliane A.; Sallet, Lunalva A. P.; Campos, Pollyanna F.; Prates, Maura V.; Silva, Luciano P.

2012-01-01

179

Energetic Metastable Oxygen and Nitrogen Atoms in the Terrestrial Atmosphere  

NASA Technical Reports Server (NTRS)

This report summarizes our research performed under NASA Grant NAG5-11857. The three-year grant have been supported by the Geospace Sciences SR&T program. We have investigated the energetic metastable oxygen and nitrogen atoms in the terrestrial stratosphere, mesosphere and thermosphere. Hot atoms in the atmosphere are produced by solar radiation, the solar wind and various ionic reactions. Nascent hot atoms arise in ground and excited electronic states, and their translational energies are larger by two - three orders of magnitude than the thermal energies of the ambient gas. The relaxation kinetics of hot atoms determines the rate of atmospheric heating, the intensities of aeronomic reactions, and the rate of atom escape from the planet. Modeling of the non-Maxwellian energy distributions of metastable oxygen and nitrogen atoms have been focused on the determination of their impact on the energetics and chemistry of the terrestrial atmosphere between 25 and 250 km . At this altitudes, we have calculated the energy distribution functions of metastable O and N atoms and computed non-equilibrium rates of important aeronomic reactions, such as destruction of the water molecules by O(1D) atoms and production of highly excited nitric oxide molecules. In the upper atmosphere, the metastable O(lD) and N(2D) play important role in formation of the upward atomic fluxes. We have computed the upward fluxes of the metastable and ground state oxygen atoms in the upper atmosphere above 250 km. The accurate distributions of the metastable atoms have been evaluated for the day and night-time conditions.

Kharchenko, Vasili; Dalgarno, A.

2005-01-01

180

Molecules in G1.6-0.025"Hot" Chemistry in the Absence of Star Formation at the Periphery of the Galactic Center Region  

NASA Astrophysics Data System (ADS)

We present molecular line mapping of the Giant Molecular Cloud G1.6-0.025, which is located at the high-longitude end of the Central Molecular Zone (CMZ) of our Galaxy. We assess the degree of star formation activity in that region using several tracers, and find very little. We made a large-scale, medium (2') resolution map in the J = 2 - 1 transition of SiO for which we find clumpy emission over a ~0fdg8 0fdg3 sized region stretching along the Galactic plane. Toward selected positions we also took spectra in the easy-to-excite Jk = 2 k - 1 k quartet of CH3OH and the carbon monosulfide (CS) 2 - 1 line. Throughout the cloud these CH3OH lines are, remarkably, several times stronger than both the CS and the SiO lines. The large widths of all the observed lines, similar to values generally found in the Galactic center, indicate a high degree of turbulence. Several high LSR velocity clumps that have 50-80 km s-1 higher velocities than the bulk of the molecular cloud appear at the same projected position as "normal" velocity material; this may indicate cloud-cloud collisions. Statistical equilibrium modeling of the CH3OH lines observed by us and others yields relatively high densities and moderate temperatures for a representative dual velocity position. We find 8 104 cm-3/30 K for material in the G1.6-0.025 cloud and a higher temperature (190 K), but a 50% lower density in a high-velocity clump projected on the same location. Several scenarios are discussed in which shock chemistry might enhance the CH3OH and SiO abundances in G1.6-0.025 and elsewhere in the CMZ.

Menten, Karl M.; Wilson, Robert W.; Leurini, Silvia; Schilke, Peter

2009-02-01

181

Method of producing excited states of atomic nuclei. [by bombarding material with x rays or electrons generated by an x-ray tube or electron gun and chemical separation by hot atoms  

Microsoft Academic Search

A method is claimed of producing excited states of atomic nuclei which comprises bombarding atoms with x rays or electrons, characterized in that (1) in the atoms selected to be produced in the excited state of their nuclei, (a) the difference between the nuclear excitation energy and the difference between the binding energies of adequately selected two electron orbits is

M. Morita; R. Morita

1976-01-01

182

Nuclear chemistry. Annual report, 1974  

SciTech Connect

The 1974 Nuclear Chemistry Annual Report contains information on research in the following areas: nuclear science (nuclear spectroscopy and radioactivity, nuclear reactions and scattering, nuclear theory); chemical and atomic physics (heavy ion-induced atomic reactions, atomic and molecular spectroscopy, photoelectron spectroscopy and hyperfine interactions); physical, inorganic, and analytical chemistry (x-ray crystallography, physical and inorganic chemistry, geochemistry); and instrumentation. Thesis abstracts, 1974 publication titles, and an author index are also included. Papers having a significant amount of information are listed separately by title. (RWR)

Conzett, H.E.; Edelstein, N.M.; Tsang, C.F. (eds.)

1975-07-01

183

Hot spot  

Microsoft Academic Search

Using an array of portable seismometers spread out directly above the proposed site of a hot spot, researchers from the Carnegie Institution of Washington (CIW) recently produced the first high-resolution seismic image of a mantle plume---a jet of hot material that rises from the deep mantle and partially melts, producing magmas that migrate to the surface through ``hot spot'' volcanoes.

Michael Carlowicz

1997-01-01

184

Analytical Chemistry Springboard  

NSDL National Science Digital Library

The Analytical Chemistry Springboard Web site is provided by Umea University Department of Chemistry. The metadata site provides a large number of annotated links that relate to analytical chemistry. Categories include Atomic Spectroscopy, Chemometrics, Electron Spectroscopy, Mass Spectrometry, Nuclear Magnetic Resonance, X-Ray Spectroscopy, and many more. Another section on the site provides links to informational resources such as newsgroups, nonprofit organizations, and scientific literature sources. Each site has a brief description, a direct link, and informational icons that tell if the site is new, updated, or contains graphics -- all of which culminate in a simple but very helpful resource for those working in a related field.

1995-01-01

185

Green Chemistry Teaching Resources  

NSDL National Science Digital Library

The American Chemical Society (ACS) has created these excellent resources via the Green Chemistry Institute and the ACS Education Division. The goal of these materials is "to increase awareness and understanding of Green Chemistry principles, alternatives, practices, and benefits within traditional educational institutions and among practicing scientists." In the Online Resources section, visitors will find downloadable pocket guides to basic green chemistry principles, "Greener Education Materials for Chemists" from the University of Oregon, and more. Perhaps the best section of the site is Activities and Experiments, where visitors can look over activities like "Gassing Up Without Air Pollution" and "Cleaning Up With Atom Economy."

2012-10-26

186

Green Chemistry Teaching Resources  

NSDL National Science Digital Library

The American Chemical Society (ACS) has created these excellent resources via the Green Chemistry Institute and the ACS Education Division. The goal of these materials is "to increase awareness and understanding of Green Chemistry principles, alternatives, practices, and benefits within traditional educational institutions and among practicing scientists." In the Online Resources section, visitors will find downloadable pocket guides to basic green chemistry principles, "Greener Education Materials for Chemists" from the University of Oregon, and more. Perhaps the best section of the site is Activities and Experiments, where visitors can look over activities like "Gassing Up Without Air Pollution" and "Cleaning Up With Atom Economy."

187

Shape-selective catalysts for Fischer-Tropsch chemistry : atomic layer deposition of active catalytic metals. Activity report : January 1, 2005 - September 30, 2005.  

SciTech Connect

Argonne National Laboratory is carrying out a research program to create, prepare, and evaluate catalysts to promote Fischer-Tropsch (FT) chemistry - specifically, the reaction of hydrogen with carbon monoxide to form long-chain hydrocarbons. In addition to needing high activity, it is desirable that the catalysts have high selectivity and stability with respect to both mechanical strength and aging properties. The broad goal is to produce diesel fraction components and avoiding excess yields of both light hydrocarbons and heavy waxes. Originally the goal was to prepare shape-selective catalysts that would limit the formation of long-chain products and yet retain the active metal sites in a protected 'cage.' Such catalysts were prepared with silica-containing fractal cages. The activity was essentially the same as that of catalysts without the cages. We are currently awaiting follow-up experiments to determine the attrition strength of these catalysts. A second experimental stage was undertaken to prepare and evaluate active FT catalysts formed by atomic-layer deposition [ALD] of active components on supported membranes and particulate supports. The concept was that of depositing active metals (i.e. ruthenium, iron or cobalt) upon membranes with well defined flow channels of small diameter and length such that the catalytic activity and product molecular weight distribution could be controlled. In order to rapidly evaluate the catalytic membranes, the ALD coating processes were performed in an 'exploratory mode' in which ALD procedures from the literature appropriate for coating flat surfaces were applied to the high surface area membranes. Consequently, the Fe and Ru loadings in the membranes were likely to be smaller than those expected for complete monolayer coverage. In addition, there was likely to be significant variation in the Fe and Ru loading among the membranes due to difficulties in nucleating these materials on the aluminum oxide surfaces. The first series of experiments using coated membranes demonstrated that the technology needed further improvement. Specifically, observed catalytic FT activity was low. This low activity appeared to be due to: (1) low available surface area, (2) atomic deposition techniques that needed improvements, and (3) insufficient preconditioning of the catalyst surface prior to FT testing. Therefore, experimentation was expanded to the use of particulate silica supports having defined channels and reasonably high surface area. This later experimentation will be discussed in the next progress report. Subsequently, we plan to evaluate membranes after the ALD techniques are improved with a careful study to control and quantify the Fe and Ru loadings. The preconditioning of these surfaces will also be further developed. (A number of improvements have been made with particulate supports; they will be discussed in the subsequent report.) In support of the above, there was an opportunity to undertake a short study of cobalt/promoter/support interaction using the Advanced Photon Source (APS) of Argonne. Five catalysts and a reference cobalt oxide were characterized during a temperature programmed EXAFS/XANES experimental study with the combined effort of Argonne and the Center for Applied Energy Research (CAER) of the University of Kentucky. This project was completed, and it resulted in an extensive understanding of the preconditioning step of reducing Co-containing FT catalysts. A copy of the resulting manuscript has been submitted and accepted for publication. A similar project was undertaken with iron-containing FT catalysts; the data is currently being studied.

Cronauer, D. C. (Chemical Sciences and Engineering Division)

2011-04-15

188

Art in Chemistry: Chemistry in Art. Second Edition  

ERIC Educational Resources Information Center

This textbook integrates chemistry and art with hands-on activities and fascinating demonstrations that enable students to see and understand how the science of chemistry is involved in the creation of art. It investigates such topics as color integrated with electromagnetic radiation, atoms, and ions; paints integrated with classes of matter,

Greenberg, Barbara R.; Patterson, Dianne

2008-01-01

189

International Journal of Quantum Chemistry. Quantum Chemistry Symposium Number 26: Proceedings of the International Symposium on Atomic, Molecular, and Condensed Matter Theory and Computational Methods Held in St. Augustine, Florida on 14-21 March 1992.  

National Technical Information Service (NTIS)

The 32nd annual Sanibel Symposium was held March 14 to 21, 1992. The format of the symposium adopted for the past 2 years was followed again this year providing a compact 8-day schedule with an integrated program of quantum biology, quantum chemistry, and...

R. J. Bartlett

1993-01-01

190

Analysis of the Effect Exerted by the Initial Temperature of Atomized Water on the Integral Characteristics of Its Evaporation During Motion Through the Zone of "Hot" Gases  

NASA Astrophysics Data System (ADS)

We have carried out an experimental investigation of the integral characteristics of atomized water evaporation during its motion through high-temperature combustion products using a flame of fixed height as an example and a high-response measurement system of two-phase vapor-liquid flow diagnostics. The scales of the influence of the initial liquid temperature on the intensity of phase transition in the region of the combustion zone at different atomization parameters have been established. Approximate relations for the dependences of the evaporated fraction of atomized liquid on its initial temperature and droplet size have been formulated.

Volkov, R. S.; Kuznetsov, G. V.; Strizhak, P. A.

2014-03-01

191

Pre-University Chemistry Course  

NSDL National Science Digital Library

From the University of Oxford Department of Chemistry comes the Pre-University Chemistry Course teaching material Web site. This multimedia learning resource is based on the book Chemistry, Matter and the Universe by Richard E. Dickerson and Irving Geis, and contains more than twenty topics. Users can learn about atoms, molecules, moles, particles, waves, heat, energy, and more through various well-done animated and interactive activities.

1998-01-01

192

The Great Ideas of Chemistry.  

ERIC Educational Resources Information Center

Presents a list of six concepts that form the basis of modern chemistry and that should be included in introductory chemistry courses. Discusses atoms, molecules, and ions; the chemical bond; molecular shape and geometry; kinetic theory; the chemical reaction; and energy and entropy. (JRH)

Gillespie, Ronald J.

1997-01-01

193

Retained Austenite Decomposition and Carbide Formation During Tempering a Hot-Work Tool Steel X38CrMoV5-1 Studied by Dilatometry and Atom Probe Tomography  

NASA Astrophysics Data System (ADS)

The microstructural development of a hot-work tool steel X38CrMoV5-1 during continuous heating to tempering temperature has been investigated with the focus on the decomposition of retained austenite (Stage II) and carbide formation (Stages III and IV). Investigations have been carried out after heating to 673.15 K, 773.15 K, 883.15 K (400 C, 500 C, 610 C) and after a dwell time of 600 seconds at 883.15 K (610 C). Dilatometry and atom probe tomography were used to identify tempering reactions. A distinctive reaction takes place between 723.15 K and 823.15 K (450 C and 550 C) which is determined to be the formation of M3C from transition carbides. Stage II could be evidenced with the atom probe results and indirectly with dilatometry, indicating the formation of new martensite during cooling. Retained austenite decomposition starts with the precipitation of alloy carbides formed from nanometric interlath retained austenite films which are laminary arranged and cause a reduction of the carbon content within the retained austenite. Preceding enrichment of substitutes at the matrix/carbide interface in the early stages of Cr7C3 alloy carbide formation could be visualised on the basis of coarse M3C carbides within the matrix. Atom probe tomography has been found to be very useful to complement dilatational experiments in order to characterise and identify microstructural changes.

Lerchbacher, Christoph; Zinner, Silvia; Leitner, Harald

2012-12-01

194

From Cathode Rays To Alpha Particles To Quantum of Action: A Rational Reconstruction of Structure of the Atom and Its Implications for Chemistry Textbooks.  

ERIC Educational Resources Information Center

Reports on a study that involves the analysis of chemistry textbooks at the college freshman level to determine the degree to which they address developments in the history and philosophy of science. Twenty-three textbooks were evaluated on eight criteria. Contains 108 references. (DDR)

Niaz, Mansoor

1998-01-01

195

Hot and Cold  

NSDL National Science Digital Library

In this activity, learners explore temperature changes from chemical reactions by mixing urea with water in one flask and mixing calcium chloride with water in another flask. They observe that the urea flask gets cold and the calcium chloride flask gets hot. The main idea is that some chemical processes release heat energy and are exothermic, while some chemical processes absorb heat energy and are endothermic. This activity is currently used in the Nature of Matter Unit in OMSI's Chemistry Lab. Cost estimates are per 100 learners.

Industry, Oregon M.

1997-01-01

196

Chemistry Notes.  

ERIC Educational Resources Information Center

Describes experiments, demonstrations, activities and ideas relating to various fields of chemistry to be used in chemistry courses of secondary schools. Three experiments concerning differential thermal analysis are among these notes presented. (HM)

School Science Review, 1978

1978-01-01

197

Chemistry Notes  

ERIC Educational Resources Information Center

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)

School Science Review, 1976

1976-01-01

198

Chemistry Notes  

ERIC Educational Resources Information Center

Thirteen ideas are presented that may be of use to chemistry teachers. Topics covered include vitamin C, industrial chemistry, electrical conductivity, electrolysis, alkali metals, vibration modes infra-red, dynamic equilibrium, and some new demonstrations in gaseous combinations. (PS)

School Science Review, 1972

1972-01-01

199

Forensic Chemistry  

Microsoft Academic Search

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

Suzanne Bell

2009-01-01

200

Organic Chemistry  

NSDL National Science Digital Library

R. H. Logan, an chemistry instructor at North Lake College, created this introduction to organic chemistry. The introduction covers a eight types of organic compounds, including Alkanes, Alkyl Halides, and Acyl Compounds (forthcoming); Conformational Analysis and Stereoisomerism; and Instrumental Analysis of Organic Compounds, as well an extensive lesson in general chemistry.

201

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents background information, laboratory procedures, classroom materials/activities, and experiments for chemistry. Topics include superheavy elements, polarizing power and chemistry of alkali metals, particulate carbon from combustion, tips for the chemistry laboratory, interesting/colorful experiments, behavior of bismuth (III) iodine, and

School Science Review, 1982

1982-01-01

202

Hot Air  

NSDL National Science Digital Library

In this activity, learners set up an experiment to investigate the effects of hot air on the path of a laser beam. They observe the wandering position of the laser beam spot on the wall after the light travels through hot air rising from the candle flame. Learners produce a table of observations from both the Cool Air and Hot Air experiments, and answer questions using evidence from their experiment. Apply what learners discover in this experiment to real-life by discussing why stars "twinkle."

Observatory, The U.

2011-01-01

203

Rotationally resolved hot atom collisional excitation of CO2 0001 and 0002 stretching vibrations by time-resolved diode laser spectroscopy  

Microsoft Academic Search

A tunable infrared diode laser has been used to monitor the time-resolved absorption of rovibrationally excited CO2 molecules produced in collisions with fast hydrogen atoms from the 193 nm excimer laser photolysis of H2S. Nascent relative rotational population distributions were measured for the 0001 and 0002 vibrational states in CO2 following collisional excitation. The nascent distributions for both of these

J. A. ONeill; C. X. Wang; J. Y. Cai; G. W. Flynn; Ralph E. Weston

1988-01-01

204

Modelling of non-LTE atomic physics processes in hot dense plasmas during the interaction with an intense short pulse laser  

NASA Astrophysics Data System (ADS)

The implicit 2D3V particle-in-cell (PIC) code developed to study the interaction of intense lasers with matter (Petrov and Davis 2008 Comput. Phys. Commun. 179 86880 2011 Phys. Plasmas 18 073102) has been extended to include atomic physics under extreme energy density conditions. The atomic physics model is applied to aluminium. Each ionization stage contains two levels: one ground and one lumped excited state, for which various atomic physics processes such as optical field ionization, collisional ionization, excitation, de-excitation and radiative decay describe the population density. Two-dimensional PIC simulations have been carried out for laser pulses with peak intensity 1 1020 W cm?2, pulse duration 60 fs, spot size 3 m and energy 0.75 J interacting with ultrathin (0.2 m) Al foil. Radiation emitted during the lasertarget interaction is computed by accounting for both boundbound transitions and bremsstrahlung radiation. We demonstrate that the radiation signature of laser-produced plasma can be used as a complementary tool to other diagnostic techniques used in laserplasma interactions. Finally, results from the PIC model are compared to equilibrium calculations (MaxwellBoltzmann and Saha). In the early stages of laserplasma interactions (<100 fs) the plasma is far from equilibrium and equilibrium models can not be applied with confidence to model the plasma.

Davis, J.; Petrov, G. M.

2014-05-01

205

Forensic Chemistry  

NASA Astrophysics Data System (ADS)

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.

Bell, Suzanne

2009-07-01

206

Forensic chemistry.  

PubMed

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. PMID:20636064

Bell, Suzanne

2009-01-01

207

CLUSTER CHEMISTRY  

SciTech Connect

Metal cluster chemistry is one of the most rapidly developing areas of inorganic and organometallic chemistry. Prior to 1960 only a few metal clusters were well characterized. However, shortly after the early development of boron cluster chemistry, the field of metal cluster chemistry began to grow at a very rapid rate and a structural and a qualitative theoretical understanding of clusters came quickly. Analyzed here is the chemistry and the general significance of clusters with particular emphasis on the cluster research within my group. The importance of coordinately unsaturated, very reactive metal clusters is the major subject of discussion.

Muetterties, Earl L.

1980-05-01

208

Computational Chemistry for Chemistry Educators  

NSDL National Science Digital Library

This is a 15-session course on the technologies, techniques, and tools of computational chemistry. By using the same computational tools as research computational chemists, educators will have the opportunity to study chemistry in a manner very different than traditional teaching and education in chemistry.

Institute, Shodor C.

209

EnvironmentalChemistry.com  

NSDL National Science Digital Library

Produced by Kenneth Barbalace with help from Roberta and Julia Barbalace, the EnvironmentalChemistry.com website supplies innumerable environmental, chemistry, and hazardous materials information and resources. Under the Environmental Issues header, students can learn about the chemical and physical properties of asbestos, the Chernobyl disaster, and the proper way to handle household chemicals. One of the newest additions to the website is the Emergency Response Guidebook, which is used during a Dangerous goods / Hazardous Materials incident. The numerous, in-depth chemical resources include a directory of common chemicals used in industry and household products, an article explaining the structure of atoms, and a periodic table with data on elements' properties.

210

When Atoms Want  

ERIC Educational Resources Information Center

Chemistry students and teachers often explain the chemical reactivity of atoms, molecules, and chemical substances in terms of purposes or needs (e.g., atoms want or need to gain, lose, or share electrons in order to become more stable). These teleological explanations seem to have pedagogical value as they help students understand and use

Talanquer, Vicente

2013-01-01

211

Initial results on the Ag[vert bar]CdO [222] interface: Atomic scale interfacial chemistry and sequencing of ordered cadmium/oxygen planes  

SciTech Connect

In this study the authors present the first APFIM results on silver/cadmium oxide interfaces produced by internal oxidation of a Ag(Cd) alloy. Internal oxidation of binary metal alloys is a well-studied phenomenon, and is based upon preferential oxidation of solute atoms (B) in a dilute A(B) alloy. Internally-oxidized silver (cadmium) alloys are used to switch medium to high currents, and have been the focus of studies of their strength and electrical properties. Previous HREM investigations of silver/cadmium oxide interfaces, produced by internal oxidation, have determined that the cadmium oxide precipitates have a cube-on-cube orientation relationship with the silver matrix, are octahedrally shaped, are bound by [222] planes, and can be truncated along <100> directions. (The lattice misfit parameter--[nu] = 2[(a[sub CdO] + a[sub Ag])]--between silver and cadmium oxide is 0.14.) Mader and co-workers suggest, via HREM observations, that the terminating [222]-type plane of CdO is the oxygen plane. In this paper the authors present evidence that it is possible to dissect cadmium oxide precipitates on an atom-by-atom basis, via the pulsed field-evaporation technique.

Chan, D.K.; Jang, Ho; Seidman, D.N. (Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering and the Materials Research Center); Merkle, K.L. (Argonne National Lab., IL (United States))

1993-10-15

212

Quasi-random integration in quantum chemistry: Efficiency, stability, and application to the study of small atoms and molecules constrained in spherical boxes  

NASA Astrophysics Data System (ADS)

This project consists of two parts. In the first part, a series of test calculations is performed to verify that the integrals involved in the determination of atomic and molecular properties by standard self-consistent field (SCF) methods can be obtained through Halton, Korobov, or Hammersley quasi-random integration procedures. Through these calculations, we confirm that all three methods lead to results that meet the levels of precision required for their use in the calculation of properties of small atoms or molecules at least at a Hartree-Fock level. Moreover, we have ensured that the efficiency of quasi-random integration methods that we have tested is Halton=Korobov>Hammersley?pseudo-random. We also find that these results are comparable to those yielded by ordinary Monte Carlo (pseudo-random) integration, with a calculation effort of two orders of smaller magnitude. The second part, which would not have been possible without the integration method previously analyzed, contains a first study of atoms constrained in spherical boxes through SCF calculations with basis functions adapted to the features of the problem: Slater-type orbitals (STOs) trimmed by multiplying them by a function that yields 1 for 0 < r < (R-?), polynomial values for (R-?) < r < R and null for r > R, R being the radius of the box and ? a variationally determined interval. As a result, we obtain a equation of state for electrons of small systems, valid just in the limit of low temperatures, but fairly simple.

Cuenca, D. Zorrilla; Mrquez, J. Snchez; Nez, M. Fernndez; Huertas, R. Rodrguez

213

Chemistry Notes.  

ERIC Educational Resources Information Center

Outlines laboratory procedures, demonstrations, teaching suggestions, and content information related to chemistry. Topics include polarizing power; calorimetry and momentum; microcomputers in school chemistry; a constant-volume dispenser for liquids, floating magnets, and crystal lattices; preparation of chromium; and solvent polarity and

School Science Review, 1981

1981-01-01

214

SUPRAMOLECULAR CHEMISTRY  

Microsoft Academic Search

the photoinitiated forma- tion of substituted tropy- lium salts from arylcyclo- heptatrienes bearing a leaving group such as the methoxy group. Two topics of supramolecular chemistry are studied in the Supramolecular Photo- chemistry group: host-guest complexes based on calixarenes and photoswitchable rotaxanes. - Newly designed calix(4)arenes, substituted with a different number of cycloheptatrienyl or tropylium functions at the upper rim

Hans-Werner Abraham

215

Hot Tickets  

ERIC Educational Resources Information Center

This article describes the highlights of this year's BookExpo America (BEA) held at the Los Angeles Convention Center. The attendees at BEA had not minded that the air was recycled, the lighting was fluorescent, and the food was bad. The first hot book sighting came courtesy of Anne Rice. Michelle Moran, author of newly published novel, "The

Fox, Bette-Lee; Hoffert, Barbara; Kuzyk, Raya; McCormack, Heather; Williams, Wilda

2008-01-01

216

HOT AIR  

NSDL National Science Digital Library

HOT AIR -- The graphical home page of THE ANNALS OF IMPROBABLE RESEARCH FROM MIT provides a different look at scientific research. Check out a schedule of AIR events, an art gallery, and SharewAIR--an interactive and up-to-the-minute moderated forum.

217

Surface-morphology changes and damage in hot tungsten by impact of 80 eV 12 keV He-ions and keV-energy self-atoms  

NASA Astrophysics Data System (ADS)

We report results of measurements on the evolution of the surface morphology of a hot tungsten surface due to impacting low-energy (80 12,000 eV) He ions, performed at the ORNL Multicharged Ion Research Facility (MIRF). Surface-morphology changes were investigated over a broad range of fluences, energies and temperatures for both virgin and pre-damaged W-targets. At low fluences, ordered coral-like and ridge-like surface structures are observed, with great grain-to-grain variability. At the largest fluences, individual grain characteristics disappear in FIB/SEM scans, and the entire surface is covered by a multitude of near-surface bubbles with a broad range of sizes, and disordered whisker growth, while in top-down SEM imaging the surface is virtually indistinguishable from the nanofuzz produced on linear plasma devices. These features are evident at progressively lower fluences as the He-ion energy is increased. In addition, simulations were carried out of damage caused by cumulative bombardment of 1 keV W self-atoms, using LAMMPS at the Kraken supercomputing facility of the University of Tennessee. The simulations show strong defect-recombination effects that lead to a saturation of the total defect number after a few hundred impacts, while sputtering and implantation lead to an imbalance of the vacancy and interstitial numbers.

Meyer, F. W.; Krstic, P. S.; Hijazi, H.; Bannister, M. E.; Dadras, J.; Parish, C. M.; Meyer, H. M., Iii

2014-04-01

218

Circumstellar chemistry  

NASA Technical Reports Server (NTRS)

The study of the outer envelopes of cool evolved stars has become an active area of research. The physical properties of CS envelopes are presented. Observations of many wavelengths bands are relevant. A summary of observations and a discussion of theoretical considerations concerning the chemistry are summarized. Recent theoretical considerations show that the thermal equilibrium model is of limited use for understanding the chemistry of the outer CS envelopes. The theoretical modeling of the chemistry of CS envelopes provides a quantitive test of chemical concepts which have a broader interest than the envelopes themselves.

Glassgold, Alfred E.; Huggins, Patrick J.

1987-01-01

219

Barrier heights for H-atom abstraction by H*O2 from n-butanol--a simple yet exacting test for model chemistries?  

PubMed

The barrier heights involved in the abstraction of a hydrogen atom from n-butanol by the hydroperoxyl radical have been computed with both compound (CBS-QB3, CBS-APNO, G3) and coupled cluster methods. In particular, the benchmark computations CCSD(T)/cc-pVTZ//MP2/6-311G(d,p) were used to determine that the barrier heights increase in the order alpha < gamma < beta < delta < OH. Two prereaction hydrogen-bonded complexes are formed, one of which connects the TGt conformer of n-butanol to the alpha and beta transition states and the other connects to the gamma and OH channels from the TGg conformer. Four postreaction complexes were also found which link the transition states to the products, hydrogen peroxide + C(4)H(9)O radical. Abstraction from the terminal delta carbon atom does not involve either a pre or postreaction complex. A number of DFT functionals-B3LYP, BMK, MPWB1K, BB1K, MPW1K, and M05-2X-were tested to see whether the correct ranking could be obtained with computationally less expensive methods. Only the later functional predicts the correct order but requires a basis set of 6-311++G(df,pd) to achieve this. However, the absolute values obtained do not agree that well with the benchmarks; the composite G3 method predicts the correct order and comes closest (< or = 2 kJ, mol (-1)) in absolute numerical terms for H-abstraction from carbon. PMID:19882733

Black, Grinne; Simmie, John M

2010-04-30

220

Radioanalytical Chemistry  

NSDL National Science Digital Library

This website provides a course on the use of radionuclides in analytical chemistry. Types of radioactive decay are discussed as well as the techniques of scintillation counting, neutron activation analysis, and gamma spectroscopy.

Hardy, James K.

2010-07-01

221

Chemistry Notes.  

ERIC Educational Resources Information Center

Describes equipment, activities, and experiments useful in chemistry instruction, including among others, a rapid method to determine available chlorine in bleach, simple flame testing apparatus, and a simple apparatus demonstrating the technique of flash photolysis. (SK)

School Science Review, 1980

1980-01-01

222

Chemistry Notes  

ERIC Educational Resources Information Center

Several ideas are proposed for chemistry teachers to try in their classrooms. Subjects included are polymerization of acrylate, polymerization of styrene, conductivity, pollution, preparation of chlorine, redox equations, chemiluminescence, and molecular sieves. (PS)

School Science Review, 1973

1973-01-01

223

Catalytic Chemistry.  

ERIC Educational Resources Information Center

Describes an approach for making chemistry relevant to everyday life. Involves the study of kinetics using the decomposition of hydrogen peroxide by vegetable juices. Allows students to design and carry out experiments and then draw conclusions from their results. (JRH)

Borer, Londa; And Others

1996-01-01

224

Organoleptic Chemistry.  

ERIC Educational Resources Information Center

Discusses how the concept of organoleptic chemistry permeates every modern chemical experiment. Six approaches for developing organoleptic attitudes which are crucial to the experimental aspects are also presented. (HM)

Slabaugh, W. H.

1980-01-01

225

Precolumbian Chemistry.  

ERIC Educational Resources Information Center

Describes the content and development of a curriculum that provides an approach to descriptive chemistry and the history of technology through consideration of the pottery, metallurgy, pigments, dyes, agriculture, and medicine of pre-Columbian people. (DDR)

Robinson, Janet Bond

1995-01-01

226

Nuclear Chemistry.  

ERIC Educational Resources Information Center

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)

Chemical and Engineering News, 1979

1979-01-01

227

Urine chemistry  

MedlinePLUS

Chemistry - urine ... For this test, a clean-catch (midstream) urine sample is needed. For more information, see: Urine collection - clean catch . Some tests require that you collect all of your urine for 24 ...

228

Chemistry Notes.  

ERIC Educational Resources Information Center

Describes 13 activities, experiments and demonstrations, including the preparation of iron (III) chloride, simple alpha-helix model, investigating camping gas, redox reactions of some organic compounds, a liquid crystal thermometer, and the oxidation number concept in organic chemistry. (JN)

School Science Review, 1981

1981-01-01

229

Stratospheric chemistry  

SciTech Connect

Advances in stratospheric chemistry made by investigators in the United States from 1987 to 1990 are reviewed. Subject areas under consideration include photochemistry of the polar stratosphere, photochemistry of the global stratosphere, and assessments of inadvertent modification of the stratosphere by anthropogenic activity. Particular attention is given to early observations and theories, gas phase chemistry, Antarctic observations, Arctic observations, odd-oxygen, odd-hydrogen, odd-nitrogen, halogens, aerosols, modeling of stratospheric ozone, and reactive nitrogen effects.

Brune, W.H. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

230

Chemistry Tutorials  

NSDL National Science Digital Library

The California State University Stanislaus developed these interactive chemistry Web tutorials to assist college students in mass spectrometry, proton NMR chemical shifts, and more. With the many animations and figures, visitors will find assistance with the subtraction and absorption of light and with infrared absorption frequencies for numerous compounds. The titration tutorials simulate laboratory experiments without the hazards of dealing with chemicals. Students will also find a very informative lesson describing how to use Excel to record and analyze their chemistry data.

231

The Chemistry of Interstellar Hydrogen Cyanide: Observations and Theory  

NASA Astrophysics Data System (ADS)

The main results of this thesis are as follows [i)] The molecular ion HCNH+ has been detected in the dark cloud TMC-1. This is the first detection of this molecule outside the galactic center. The hyperfine structure has been resolved and shown to be similar to HNC. The analysis of the data has shown that the HCNH+ / HCN ratio is very high, as compared e.g. to the HCO+ / CO ratio (?3 10-2 vs. 10-4). [ii)] The high [HCNH+]/[HCN] ratio could be successfully reproduced by gas phase chemical models. The best agreement with observations is achieved in models with a very high metal depletion ratio ([M]/[H] ?10-11), consistent with the non-detection of silicon bearing species in this source. [iii)] The source OMC-1 has been mapped in HCN, HNC and some isotopomers with the IRAM 30 m telescope. The derived [HCN]/[HNC] and [DCN]/[HCN] ratios differ drastically from the hot core region to the ridge. HNC and, to a lesser degree, DCN, seem to avoid the star forming region around the infrared source IRc2, while they trace nicely the filamentary structure in the north of the hot core. But even in the ridge, the [HCN]/[HNC] ratio is significantly different from that of a dark cloud. The [DCN]/[HCN] ratio there is surprisingly high, given the kinetic temperatures of about 40 K and densities of about 106 cm-3. [iv)] Complementary, the hot core region was observed with the Plateau de Bure Interferometer in the HC15N(1-0) transition. It has been shown, mapping for the first time an optically thin transition in the millimeter--range, that HCN is concentrated on the hot core. The simultaneously obtained continuum data allowed a H2 column density determination in the hot core. The HCN abundance has been derived to be about 100-300 times higher than in the ridge. A comparison with a BIMA DCN(1-0) revealed that the [DCN]/[HCN] ratio is about 10 times lower than in the ridge. [v)] Chemical modelling showed that the ridge results for the [HCN]/[HNC] ratio can be successfully modelled by means of steady state gas phase chemistry of warm, dense gas. The most important assumption in this model is that HNC can be destroyed at high temperatures in reactions with atomic oxygen. The high [DCN]/[HCN] ratio could be explained without further assumptions to be due to neutral--neutral reactions which play no role in less dense gas. By investigating gas phase chemistry with CNO depletion (to model regions where the the gas freezes out onto grains), it could be shown that CNO depletion larger than about 100 (relative to solar abundances) can definitely be ruled out. The observed HCN abundance seems to favour models with a higher [C]/[CO] ratio than predicted by standard models. [vi)] The extremely high [HCN]/[HNC] ratio in the hot core could be due to influence of magnetohydrodynamic shocks or due to release of grain--surface chemistry processed ice mantles. While the results of our shock chemistry models predict a [DCN]/[HCN] ratio which is close to thet observed, the grain surface chemistry models from the literature would give ratio which is much too high. A realistic model of the region should therefore allow for both processes taking place, i.e. postprocessing of the released molecules.

Schilke, Peter

1992-03-01

232

Chemistry in 1876: The Way It Was  

ERIC Educational Resources Information Center

Provides a brief history of chemistry up to the founding of the American Chemical Society in 1876. Includes developments in the understanding of matter, phlogiston theory, atomic theory, and chemical reactions. (MLH)

Bernheim, Robert A.

1976-01-01

233

Vulcan Hot Springs known geothermal resource area: an environmental analysis  

Microsoft Academic Search

The Vulcan Hot Springs known geothermal resource area (KGRA) is one of the more remote KGRAs in Idaho. The chemistry of Vulcan Hot Springs indicates a subsurface resource temperature of 147°C, which may be high enough for power generation. An analysis of the limited data available on climate, meteorology, and air quality indicates few geothermal development concerns in these areas.

S. G. Spencer; B. F. Russell

1979-01-01

234

Cooperative Research in C1 Chemistry  

Microsoft Academic Search

C1 chemistry refers to the conversion of simple carbon-containing materials that contain one carbon atom per molecule into valuable products. The feedstocks for C1 chemistry include natural gas, carbon dioxide, carbon monoxide, methanol and synthesis gas (a mixture of carbon monoxide and hydrogen). Synthesis gas, or syngas, is produced primarily by the reaction of natural gas, which is principally methane,

Gerald P. Huffman

2000-01-01

235

Computational Chemistry for Chemistry Educators  

NSDL National Science Digital Library

In this paper we describe an ongoing project where the goal is to develop competence and confidence among chemistry faculty so they are able to utilize computational chemistry as an effective teaching tool. Advances in hardware and software have made research-grade tools readily available to the academic community. Training is required so that faculty can take full advantage of this technology, begin to transform the educational landscape, and attract more students to the study of science.

Sendlinger, Shawn C.; Metz, Clyde R.

236

Atomic force microscope: Enhanced sensitivity.  

National Technical Information Service (NTIS)

Atomic force microscopes (AFMs) are a recent development representing the state of the art in measuring ultrafine surface features. Applications are found in such fields of research as biology, microfabrication, material studies, and surface chemistry. Fi...

D. T. Davis

1995-01-01

237

The World of Chemistry  

NSDL National Science Digital Library

One doesn't have to be a Glenn Seaborg or a Lord Ernest Rutherford to learn about chemistry, though it probably couldn't help to have some of their curiosity about the world of chemistry. Young chemists and their teachers will definitely benefit from this nice resource offered by the Annenberg Media project. This original video series was produced by the University of Maryland and the Educational Film Center, and it consists of 26 half-hour programs. With industrial and research chemists demonstrating a number of high-intensity experiments and processes, the series is quite a find. The installments include such titles as "Modeling the Unseen", "The Atom", and "The Busy Electron".

1990-01-01

238

Hot Meetings  

NASA Technical Reports Server (NTRS)

A colleague walked by my office one time as I was conducting a meeting. There were about five or six members of my team present. The colleague, a man who had been with our institution (The Johns Hopkins Applied Physics Lab, a.k.a. APL) for many years, could not help eavesdropping. He said later it sounded like we we re having a raucous argument, and he wondered whether he should stand by the door in case things got out of hand and someone threw a punch. Our Advanced Composition Explorer (ACE) team was a hot group, to invoke the language that is fashionable today, although we never thought of ourselves in those terms. It was just our modus operandi. The tenor of the discussion got loud and volatile at times, but I prefer to think of it as animated, robust, or just plain collaborative. Mary Chiu and her "hot" team from the Johns Hopkins Applied Physics Laboratory built the Advanced Composition Explorer spacecraft for NASA. Instruments on the spacecraft continue to collect data that inform us about what's happening on our most important star, the Sun.

Chiu, Mary

2002-01-01

239

CoFe2O4-TiO2 and CoFe2O4-ZnO thin film nanostructures elaborated from colloidal chemistry and atomic layer deposition.  

PubMed

CoFe(2)O(4)-TiO(2) and CoFe(2)O(4)-ZnO nanoparticles/film composites were prepared from directed assembly of colloidal CoFe(2)O(4) in a Langmuir-Blodgett monolayer and atomic layer deposition (ALD) of an oxide (TiO(2) or ZnO). The combination of these two methods permits the use of well-defined nanoparticles from colloidal chemistry, their assembly on a large scale, and the control over the interface between a ferrimagnetic material (CoFe(2)O(4)) and a semiconductor (TiO(2) or ZnO). Using this approach, architectures can be assembled with a precise control from the Angstrom scale (ALD) to the micrometer scale (Langmuir-Blodgett film). The resulting heterostructures present well-calibrated thicknesses. Electron microscopy and magnetic measurement studies give evidence that the size of the nanoparticles and their intrinsic magnetic properties are not altered by the various steps involved in the synthesis process. Therefore, the approach is suitable to obtain a layered composite with a quasi-monodisperse layer of ferrimagnetic nanoparticles embedded in an ultrathin film of semiconducting material. PMID:21067161

Clavel, Guylhaine; Marichy, Catherine; Willinger, Marc-Georg; Ravaine, Serge; Zitoun, David; Pinna, Nicola

2010-12-01

240

Radiation Chemistry  

NASA Astrophysics Data System (ADS)

Ionizing radiation causes chemical changes in the molecules of the interacting medium. The initial molecules change to new molecules, resulting in changes of the physical, chemical, and eventually biological properties of the material. For instance, water decomposes to its elements H2 and O2. In polymers, degradation and crosslinking take place. In biopolymers, e.g., DNS strand breaks and other alterations occur. Such changes are to be avoided in some cases (radiation protection), however, in other cases they are used for technological purposes (radiation processing). This chapter introduces radiation chemistry by discussing the sources of ionizing radiation (radionuclide sources, machine sources), absorption of radiation energy, techniques used in radiation chemistry research, and methods of absorbed energy (absorbed dose) measurements. Radiation chemistry of different classes of inorganic (water and aqueous solutions, inorganic solids, ionic liquids (ILs)) and organic substances (hydrocarbons, halogenated compounds, polymers, and biomolecules) is discussed in concise form together with theoretical and experimental backgrounds. An essential part of the chapter is the introduction of radiation processing technologies in the fields of polymer chemistry, food processing, and sterilization. The application of radiation chemistry to nuclear technology and to protection of environment (flue gas treatment, wastewater treatment) is also discussed.

Wojnrovits, L.

241

Chemistry-Nuclear Chemistry Division. Progress report, October 1980-September 1981  

SciTech Connect

This report describes major progress in the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory during FY 1981. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, medical radioisotopes research, element migration and fixation, nuclear waste isolation research, inorganic and structural chemistry, isotope separation, analysis and applications, the newly established Nuclear Magnetic Resonance Center, atomic and molecular collisions, molecular spectroscopy, nuclear cosmochemistry, nuclear structure and reactions, pion charge exchange, radiochemical separations, theoretical chemistry, and unclassified weapons research.

Ryan, R.R. (comp.)

1982-05-01

242

Chemistry & Industry  

NSDL National Science Digital Library

Chemistry and Industry Magazine, a bimonthly product of the Society of Chemical Industry, provides selected full-text articles from the print magazine in the areas of news, commentary, features, latest results from chemical literature, and highlights from the latest European patents. In addition, there is a searchable and browsable archive of past issues, a daily news section, and searchable jobs and meetings databases. The Society of Chemical Industry is "an international association of about 6000 members aimed at furthering applied chemistry." One of the highlights of its web site is its publication section, where, under "electronic publications," readers can find updated daily news, jobs and meetings listings on chemistry, pharmaceuticals, biotechnology, and the environment.

1997-01-01

243

Kitchen Chemistry  

NSDL National Science Digital Library

There is a great deal of chemistry going on in every kitchen, even though most cooks may not be cognizant of the various interactions going on in the pot, wok, or oven. MIT's popular OpenCourseWare Initiative has recently made the contents of Dr. Patricia Christie's course on kitchen chemistry available on this site. Visitors to the site can download the syllabus, take in some assigned readings (and recipes), and look over the assignments. The assignments include investigations that involve emulsifiers, ice cream, peer teaching, and pancakes, among other things. The site also includes links to helpful readings, such as those on chocolate, the health benefits of capsicum, and the world of gluten. For people who wish to bring back the frayed connective tissue between chemistry and the culinary arts, this site is absolutely essential.

Christie, Patricia

2006-01-01

244

Chemistry Experiments  

NASA Technical Reports Server (NTRS)

The purpose of the chemistry component of the model comparison is to assess to what extent differences in the formulation of chemical processes explain the variance between model results. Observed concentrations of chemical compounds are used to estimate to what degree the various models represent realistic situations. For readability, the materials for the chemistry experiment are reported in three separate sections. This section discussed the data used to evaluate the models in their simulation of the source gases and the Nitrogen compounds (NO(y)) and Chlorine compounds (Cl(y)) species.

Brasseur, Guy; Remsberg, Ellis; Purcell, Patrick; Bhatt, Praful; Sage, Karen H.; Brown, Donald E.; Scott, Courtney J.; Ko, Malcolm K. W.; Tie, Xue-Xi; Huang, Theresa

1999-01-01

245

Atmospheric chemistry of isoflurane, desflurane, and sevoflurane: kinetics and mechanisms of reactions with chlorine atoms and OH radicals and global warming potentials.  

PubMed

The smog chamber/Fourier-transform infrared spectroscopy (FTIR) technique was used to measure the rate coefficients k(Cl + CF(3)CHClOCHF(2), isoflurane) = (4.5 0.8) 10(-15), k(Cl + CF(3)CHFOCHF(2), desflurane) = (1.0 0.3) 10(-15), k(Cl + (CF(3))(2)CHOCH(2)F, sevoflurane) = (1.1 0.1) 10(-13), and k(OH + (CF(3))(2)CHOCH(2)F) = (3.5 0.7) 10(-14) cm(3) molecule(-1) in 700 Torr of N(2)/air diluent at 295 2 K. An upper limit of 6 10(-17) cm(3) molecule(-1) was established for k(Cl + (CF(3))(2)CHOC(O)F). The laser photolysis/laser-induced fluorescence (LP/LIF) technique was employed to determine hydroxyl radical rate coefficients as a function of temperature (241-298 K): k(OH + CF(3)CHFOCHF(2)) = (7.05 1.80) 10(-13) exp[-(1551 72)/T] cm(3) molecule(-1); k(296 1 K) = (3.73 0.08) 10(-15) cm(3) molecule(-1), and k(OH + (CF(3))(2)CHOCH(2)F) = (9.98 3.24) 10(-13) exp[-(969 82)/T] cm(3) molecule(-1); k(298 1 K) = (3.94 0.30) 10(-14) cm(3) molecule(-1). The rate coefficient of k(OH + CF(3)CHClOCHF(2), 296 1 K) = (1.45 0.16) 10(-14) cm(3) molecule(-1) was also determined. Chlorine atoms react with CF(3)CHFOCHF(2) via H-abstraction to give CF(3)CFOCHF(2) and CF(3)CHFOCF(2) radicals in yields of approximately 83% and 17%. The major atmospheric fate of the CF(3)C(O)FOCHF(2) alkoxy radical is decomposition via elimination of CF(3) to give FC(O)OCHF(2) and is unaffected by the method used to generate the CF(3)C(O)FOCHF(2) radicals. CF(3)CHFOCF(2) radicals add O(2) and are converted by subsequent reactions into CF(3)CHFOCF(2)O alkoxy radicals, which decompose to give COF(2) and CF(3)CHFO radicals. In 700 Torr of air 82% of CF(3)CHFO radicals undergo C-C scission to yield HC(O)F and CF(3) radicals with the remaining 18% reacting with O(2) to give CF(3)C(O)F. Atmospheric oxidation of (CF(3))(2)CHOCH(2)F gives (CF(3))(2)CHOC(O)F in a molar yield of 93 6% with CF(3)C(O)CF(3) and HCOF as minor products. The IR spectra of (CF(3))(2)CHOC(O)F and FC(O)OCHF(2) are reported for the first time. The atmospheric lifetimes of CF(3)CHClOCHF(2), CF(3)CHFOCHF(2), and (CF(3))(2)CHOCH(2)F (sevoflurane) are estimated at 3.2, 14, and 1.1 years, respectively. The 100 year time horizon global warming potentials of isoflurane, desflurane, and sevoflurane are 510, 2540, and 130, respectively. The atmospheric degradation products of these anesthetics are not of environmental concern. PMID:22146013

Sulbaek Andersen, Mads P; Nielsen, Ole J; Karpichev, Boris; Wallington, Timothy J; Sander, Stanley P

2012-06-21

246

Energy of Atoms and Molecules, Science (Experimental): 5316.05.  

ERIC Educational Resources Information Center

This third unit in chemistry is considered for any chemistry student and particularly the college-bound student. An understanding of the material included should enable the student to understand better the concepts in the Dynamic Nature of Atoms and Molecules which are essential for Organic Chemistry, the Chemistry of Carbon and Its Compounds and

Buffaloe, Jacquelin F.

247

Nuclear Chemistry  

NSDL National Science Digital Library

This page, from the University of North Carolina - Chapel Hill Chemistry Fundamentals program and the Shodor Education Foundation, discusses five different types of radioactive decay: alpha, beta negative, gamma, positron emission, and electron capture. After examining the numerous equations, students can test their dating skills by solving three practice problems. Solutions are included.

2008-03-12

248

Chemistry Notes  

ERIC Educational Resources Information Center

Short articles on the alkylation of aniline, the preparation and properties of perbromate, using scrap copper in chemistry instruction, a safe method of burning hydrogen, and the use of an ion-charge model as an alternative to the mole concept in secondary school instruction. (AL)

School Science Review, 1972

1972-01-01

249

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents 12 chemistry notes for British secondary school teachers. Some of these notes are: (1) a simple device for testing pH-meters; (2) portable fume cupboard safety screen; and (3) Mass spectroscopy-analysis of a mass peak. (HM)

School Science Review, 1980

1980-01-01

250

Chemistry Notes.  

ERIC Educational Resources Information Center

Describes some laboratory apparatus, chemistry experiments and demonstrations, such as a Kofler block melting point apparatus, chromatographic investigation of the phosphoric acid, x-ray diffraction, the fountain experiment, endothermic sherbet, the measurement of viscosity, ionization energies and electronic configurations. (GA)

School Science Review, 1978

1978-01-01

251

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents chemistry experiments, laboratory procedures, demonstrations, and classroom materials/activities. These include: experiments on colloids, processing of uranium ore, action of heat on carbonates; color test for phenols and aromatic amines; solvent properties of non-electrolytes; stereoscopic applications/methods; a valency balance;

School Science Review, 1983

1983-01-01

252

Chemistry Notes  

ERIC Educational Resources Information Center

Describes several chemistry projects, including solubility, formula for magnesium oxide, dissociation of dinitrogen tetroxide, use of 1-chloro-2, 4-dinitrobenzene, migration of ions, heats of neutralizations, use of pocket calculators, sonic cleaning, oxidation states of manganese, and cell potentials. Includes an extract from Chemical Age on

School Science Review, 1976

1976-01-01

253

Countertop Chemistry  

NSDL National Science Digital Library

Chemistry activities and demonstrations that use common household items and kitchen chemicals. There are activities appropriate for students in elementary school, middle school, and high school. The activities were designed and tested by the Science House, the science and mathematics learning outreach program of North Carolina State University.

254

Common Chemistry  

NSDL National Science Digital Library

A web resource that contains Chemical Abstracts Service (CAS) Registry Numbers for approximately 7,800 chemicals of widespread general public interest. Common Chemistry is helpful to non-chemists who know either a name or CAS Registry Number® of a common chemical and want to pair both pieces of information.

Chemical Abstracts Service (CAS)

255

Bad Chemistry  

NSDL National Science Digital Library

This site from the Princeton Section of the American Chemical Society consists of articles about common chemical misconceptions along with examinations of the scientific explanation. The purpose of this page is to reveal common misconceptions in the field of Chemistry. The intended audience is secondary school students and their teachers. The page is at present just beginning, and additions are welcome.

Lehmann, Kevin; University, Princeton

256

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents chemistry experiments, laboratory procedures, demonstrations, teaching suggestions, and classroom materials/activities. These include: game for teaching ionic formulas; method for balancing equations; description of useful redox series; computer programs (with listings) for water electrolysis simulation and for determining chemical

School Science Review, 1983

1983-01-01

257

Hot Deformation Behavior of Incoloy 901 Through Hot Tensile Testing  

NASA Astrophysics Data System (ADS)

Hot deformation tests were conducted on cast and wrought Incoloy 901 produced by electro-slag remelting at temperatures of 950-1150 C and strain rates of 0.01-1 s-1. Both materials showed acceptable hot workability in the studied range of temperature and strain rates. However, better workability of the wrought material was associated with easier dynamic recrystallization compared to in the cast material. A complete dynamic recrystallization in the wrought material was observed at temperatures above 1100 C. On the other hand, in the cast material that was characterized by a coarse grain structure, dynamic recrystallization occurred partially and was attributed to the low density of grain boundaries. It was recognized that in order to avoid the risk of premature fracture, hot processing of the studied material should be conducted in the temperature range of 1000-1100 C. At high temperatures, over 1100 C, both materials suffered from a lack of acceptable hot workability. Rather, the wrought material showed a slight hot ductility trough around 1050 C that could be attributed to the segregation of detrimental solute atoms such as S and P to the grain boundaries. The grain boundary decohesion was controlling the fracture mechanism of the wrought material. Due to the absence of extensive DRX in the cast material, the incipient melting, void formation, and decohesion of precipitates were found responsible for the final fracture.

Mohammadi Shore, F.; Morakabati, M.; Abbasi, S. M.; Momeni, A.

2014-04-01

258

Atmospheric Pseudohalogen Chemistry  

NASA Technical Reports Server (NTRS)

Hydrogen cyanide is not usually considered in atmospheric chemical models. The paper presents three reasons why hydrogen cyanide is likely to be significant for atmospheric chemistry. Firstly, HCN is a product and marker of biomass burning. Secondly, it is also likely that lightning is producing HCN, and as HCN is sparingly soluble it could be a useful long-lived "smoking gun" marker of lightning activity. Thirdly, the chemical decomposition of HCN leads to the production of small amounts of the cyanide (CN) and NCO radicals. The NCO radical can be photolyzed in the visible portion of the spectrum yielding nitrogen atoms (N). The production of nitrogen atoms is significant as it leads to the titration of total nitrogen from the atmosphere via N+N->N2, where N2 is molecular nitrogen.

Lary, David John

2004-01-01

259

Hot tub folliculitis  

MedlinePLUS

Hot tub folliculitis is an infection of the skin around the lower part of the hair shaft ( ... Hot tub folliculitis is caused by the bacteria Pseudomonas aeruginosa . This form of bacteria survives in hot ...

260

Atoms in Astronomy.  

ERIC Educational Resources Information Center

This booklet is part of an American Astronomical Society curriculum project designed to provide teaching materials to teachers of secondary school chemistry, physics, and earth science. A Basic Topics section discusses atomic structure, emphasizing states of matter at high temperature and spectroscopic analysis of light from the stars. A section

Blanchard, Paul A.

261

Chemistry as a Second Language: Helping Students Master Core Concepts and Succeed in Chemistry  

ERIC Educational Resources Information Center

Chemistry is a unique language in and of itself that can be difficult for students to understand. For instance, a white powder can be translated down to the atomic level in a chemical equation, thus creating a chemical word that needs to be decoded. In this article, the author shares an approach to a basic curriculum that makes chemistry

Hanes, Cara

2004-01-01

262

Chemistry Gateways and Resources  

NSDL National Science Digital Library

The Chemistry Gateways and Resources collection is comprised of chemistry-related web portals, web sites, and individual digital resources pertaining to many areas of the discipline - general chemistry, organic and inorganic chemistry, physical chemistry, and others - and intended for a wide range of audiences: educators and learners, the general public, and chemistry research communities.

2008-03-14

263

Fundamentals of environmental chemistry  

Microsoft Academic Search

This book is designed to be understandable and interesting without being overly simplistic. Topics addressed include an overview of basic chemistry; matter and the basis of its physical nature and behavior; organic chemistry; biological chemistry; the chemistry of water, soil, and air; industrial chemistry; toxicological chemistry as it pertains to occupational health and human exposure to pollutants and toxicants; energy;

Manahan

1993-01-01

264

Interactive Teaching Units: Green Chemistry  

NSDL National Science Digital Library

As more and more organizations go "green", it makes sense that a number of educational institutions are participating as well. One such institution is the University of Glasgow which has developed this series of "green" chemistry teaching exercises known as Interactive Teaching units (ITUs). Currently, the site contains four ITU's, including "The Age of Refrigeration", "Titanium and the Titanium Dioxide Industry", and "The Atom Economy". The modules all draw on the concept of problem based learning to introduce key concepts of green chemistry and sustainability in an industrial context. All of these materials can be used in the college classroom in order to develop both teamwork and communication skills.

265

Transactinide nuclear chemistry at JAERI  

Microsoft Academic Search

The present status of transactinide nuclear chemistry research at JAERI (Japan Atomic Energy Research Institute) is reviewed.\\u000a Successful production of the transactinide nuclei, 261Rf and 262Db in the reactions of 248Cm(18O,5n) and 248Cm(19F,5n), respectively, at the JAERI tandem accelerator is reported. Aqueous chemistry of element 104, Rf, is being performed\\u000a with a newly developed rapid ion-exchange separation apparatus. Anion-exchange behaviour

Y. Nagame; H. Haba; K. Tsukada; M. Asai; K. Akiyama; M. Hirata; I. Nishinaka; S. Ichikawa; H. Nakahara; S. Goto; T. Kaneko; H. Kudo; A. Toyoshima; A. Shinohara; M. Schdel; J. V. Kratz; H. W. Gggeler; A. Trler

2003-01-01

266

Electron scattering in hot-dense plasmas  

NASA Astrophysics Data System (ADS)

Hot-dense plasmas have direct industrial applications in inertial confinement fusion. We have used the convergent close-coupling (CCC) method to investigate electron scattering off hydrogen and helium atoms in a hot-dense weakly coupled (Debye) plasma. The Yukawa-type Debye-Hckel potential has been used to describe the plasma screening effects. Integrated excitation, total ionization and total cross sections have been calculated over a broad range of energies and various Debye lengths, D.

Zammit, Mark C.; Fursa, Dmitry V.; Bray, Igor

2012-11-01

267

Modelling the sulphur chemistry evolution in Orion KL  

NASA Astrophysics Data System (ADS)

Context. We present a study of the sulphur chemistry evolution in the region Orion KL along the gas and grain phases of the cloud. Aims: Our aim is to investigate the processes that dominate the sulphur chemistry in Orion KL and to determine how physical and chemical parameters, such as the final mass of the star and the initial elemental abundances, influence the evolution of the hot core and of the surrounding outflows and shocked gas (the plateau). Methods: We independently modelled the chemistry evolution of the hot core and the plateau using the time-dependent gas-grain model UCL_CHEM and considering two different phase calculations. Phase I starts with the collapsing cloud and the depletion of atoms and molecules onto grain surfaces. Phase II starts when a central protostar is formed and the evaporation from grains takes place. We show how the stellar mass, the gas density, the gas depletion efficiency, the initial sulphur abundance, the shocked gas temperature, and the different chemical paths on the grains leading to different reservoirs of sulphur on the mantles affect sulphur-bearing molecules at different evolutionary stages for both components. We also compare the predicted column densities with those inferred from observations of the species SO, SO2, CS, OCS, H2S, and H2CS. Results: The models that reproduce the observations of the largest number of sulphur-bearing species in both components are those with an initial sulphur abundance of 0.1 times the sulphur solar abundance (0.1 S?) and a density of at least nH = 5 106 cm-3 in the shocked gas region. Conclusions: We conclude that most of the sulphur atoms were ionised during Phase I, consistent with an inhomogeneous and clumpy region where the UV interstellar radiation penetrates and leading to sulphur ionisation. We also conclude that the main sulphur reservoir on the ice mantles was H2S. In addition, we deduce that a chemical transition currently takes place in the plateau shocked gas, where SO and SO2 gas-phase formation reactions change from being dominated by O2 to being dominated by OH. Appendices are available in electronic form at http://www.aanda.org

Esplugues, G. B.; Viti, S.; Goicoechea, J. R.; Cernicharo, J.

2014-07-01

268

Atomic-Scale Chemistry of Metal Surfaces.  

National Technical Information Service (NTIS)

The concept of pseudo-molecules is derived from reviewing the results of Scanning Tunneling Microscopy (STM) of metal surfaces. Ni(110), Cu(110), and Ag(110) surfaces exposed to H2 or O2 at room temperature reveal the formation of one-dimensional pseudo-m...

K. Tanaka

1993-01-01

269

A chemical model for the atmosphere of hot Jupiters  

NASA Astrophysics Data System (ADS)

Context. The atmosphere of hot Jupiters can be probed by primary transit and secondary eclipse spectroscopy. Owing to the intense UV irradiation, mixing, and circulation, their chemical composition is maintained out of equilibrium and must be modeled with kinetic models. Aims: Our purpose is to release a chemical network and the associated rate coefficients, developed for the temperature and pressure range relevant to hot Jupiters atmospheres. Using this network, we study the vertical atmospheric composition of the two hot Jupiters (HD 209458b and HD 189733b) with a model that includes photolyses and vertical mixing, and we produce synthetic spectra. Methods: The chemical scheme has been derived from applied combustion models that were methodically validated over a range of temperatures and pressures typical of the atmospheric layers influencing the observations of hot Jupiters. We compared the predictions obtained from this scheme with equilibrium calculations, with different schemes available in the literature that contain N-bearing species, and with previously published photochemical models. Results: Compared to other chemical schemes that were not subjected to the same systematic validation, we find significant differences whenever nonequilibrium processes take place (photodissociations or vertical mixing). The deviations from the equilibrium, hence the sensitivity to the network, are larger for HD 189733b, since we assume a cooler atmosphere than for HD 209458b. We found that the abundances of NH3 and HCN can vary by two orders of magnitude depending on the network, demonstrating the importance of comprehensive experimental validation. A spectral feature of NH3 at 10.5 ?m is sensitive to these abundance variations and thus to the chemical scheme. Conclusions: Due to the influence of the kinetics, we recommend using a validated scheme to model the chemistry of exoplanet atmospheres. The network we release is robust for temperatures within 300-2500 K and pressures from 10 mbar up to a few hundred bars, for species made of C, H, O, and N. It is validated for species up to 2 carbon atoms and for the main nitrogen species (NH3, HCN, N2, NOx). Although the influence of the kinetic scheme on the hot Jupiters spectra remains within the current observational error bars (with the exception of NH3), it will become more important for atmospheres that are cooler or subjected to higher UV fluxes, because they depart more from equilibrium. Appendices are available in electronic form at http://www.aanda.org

Venot, O.; Hbrard, E.; Agndez, M.; Dobrijevic, M.; Selsis, F.; Hersant, F.; Iro, N.; Bounaceur, R.

2012-10-01

270

Azulene Chemistry  

NSDL National Science Digital Library

The month's featured molecules come from the paper An Azulene-Based Discovery Experiment: Challenging Students To Watch for the "False Assumption" by Charles Garner illustrating some of the chemistry of a substituted azulene. Azulene is a structural isomer of naphthalene and differs from it in several important ways, the most obvious being azulene's intense blue color, which arises from the S0 → S2 transition. Another unusual feature of this molecule is that its fluorescence arises from the reverse of this transition rather than from S1 → S0.

271

Industrial Chemistry  

NSDL National Science Digital Library

This Web site addresses Professor Dr. J. Gmehling's research group activities in "the synthesis and design of chemical processes with an emphasis on thermal separation processes." Ranging from the development of thermodynamic models to the construction of software tools and data banks, their research at the University of Oldenburg, covers a broad range in the field of Industrial Chemistry. Students and educators can view informative figures and images such as the Isothermal Flow Calorimeter and the Gas-Liquid Chromatography. Users can download the free software, Dortmund Data Bank (DDB), which searches the literature for experimental information.

272

Solar 'hot spots' are still hot  

NASA Technical Reports Server (NTRS)

Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22.

Bai, Taeil

1990-01-01

273

Industrial Chemistry and School Chemistry: Making chemistry studies more relevant  

Microsoft Academic Search

In this paper, we present the development and implementation over the period of more than 15 years of learning materials focusing on industrial chemistry as the main theme. The work was conducted in the Department of Science Teaching at the Weizmann Institute of Science, Israel. The project's general goal was to teach chemistry concepts in the context of industrial chemistry

Avi Hofstein; Miri Kesner

2006-01-01

274

The magnehydrogen in hadronic chemistry  

NASA Astrophysics Data System (ADS)

In this paper we have described in brief one of the great achievements accomplished by the Italian-American scientist Ruggero Maria Santilli [1], namely the isochemical model and magnehydrogen that form the subject matter of the hadronic Chemistry. This new chemical species of magnehydrogen consist of individual hydrogen atom bonded together and form stable clusters under a new internal attractive forces originating from the toroidal polarization of orbitals of atomic electrons when placed in strong magnetic fields. These magnecules are used as pollution free fuel and for other applications because there is no cracking involved while using the stored magnetic energy.

Zodape, Sangesh P.; Bhalekar, Anil A.

2013-10-01

275

Possible evidence for shocks in hot cores  

Microsoft Academic Search

The NS\\/CS ratio can be used to test if shocks or thermal evaporation remove grain ices during massive star formation. The two scenarios lead to differences in the subsequent chemistry: in particular, timescales are shorter if shocks are present. We have measured NS\\/CS ratios in six hot core sources through observation of high excitation NS, N34S, C34S and C33S with

J. Hatchell; S. Viti

2002-01-01

276

Compositional Analysis of Low Quantities of Phase Separation in Hot-Melt-Extruded Solid Dispersions: A Combined Atomic Force Microscopy, Photothermal FourierTransform Infrared Microspectroscopy, and Localised Thermal Analysis Approach  

Microsoft Academic Search

PurposeTo characterise phase separations in aged hot-melt-extruded solid dispersions at a micron to submicron scale.\\u000a \\u000a \\u000a \\u000a MethodsHot-melt-extruded felodipine and Eudragit E PO systems at a range of compositions were studied after a standard period of aging to allow phase separation to occur.\\u000a The samples were characterised using combined nano-thermal analysis, photothermal FTIR microspectroscopy coupled with pulsed\\u000a force mode AFM as a

Sheng Qi; Peter Belton; Kathrin Nollenberger; Andreas Gryczke; Duncan Q. M. Craig

277

Computational Chemistry List  

NSDL National Science Digital Library

The Computational Chemistry List (CCL) was established as an independent electronic forum for chemistry researchers and educators from around the world. The discussions cover all aspects of computational chemistry.

278

Ion composition and chemistry  

NASA Astrophysics Data System (ADS)

Measurements from the Vega and Giotto probes are used to study the composition and chemistry of Comet Halley. The missing parent molecules of the C+ and S+ ions which are very abundant in the outer coma of Comet Halley at a radial distance of 100,000 km are examined. Consideration is given to the atomic ions, C+, S+, He+, and Na+, the molecular ions, NH4(+), H2CN(+), and HCS(+), formaldehyde polymers and polycylic aromatic hydrogen carbons. It is suggested that the deficiency of N2 and NH3(+) and the abundance of CO and CO2 with a significant amount of H2CO cloud result from the condensation of volatile ices in the solar nebula.

Ip, W.-H.

279

Materials Selection for Long Life in LEO: A Critical Evaluation of Atomic Oxygen Testing with Thermal Atom Systems.  

National Technical Information Service (NTIS)

The use of thermal atom test methods as a materials selection and screening technique for low-Earth orbit (LEO) spacecraft is critically evaluated. The chemistry and physics of thermal atom environments are compared with the LEO environment. The relative ...

S. L. Koontz J. Kuminecz L. Leger P. Nordine

1988-01-01

280

Hot Flow Anomalies at Venus  

NASA Technical Reports Server (NTRS)

We present a multi-instrument study of a hot flow anomaly (HFA) observed by the Venus Express spacecraft in the Venusian foreshock, on 22 March 2008, incorporating both Venus Express Magnetometer and Analyzer of Space Plasmas and Energetic Atoms (ASPERA) plasma observations. Centered on an interplanetary magnetic field discontinuity with inward convective motional electric fields on both sides, with a decreased core field strength, ion observations consistent with a flow deflection, and bounded by compressive heated edges, the properties of this event are consistent with those of HFAs observed at other planets within the solar system.

Collinson, G. A.; Sibeck, David Gary; Boardsen, Scott A.; Moore, Tom; Barabash, S.; Masters, A.; Shane, N.; Slavin, J.A.; Coates, A.J.; Zhang, T. L.; Sarantos, M.

2012-01-01

281

Modelling Hot Air Balloons.  

ERIC Educational Resources Information Center

A macroscopic way of modeling hot air balloons using a Newtonian approach is presented. Misleading examples using a car tire and the concept of hot air rising are discussed. Pressure gradient changes in the atmosphere are used to explain how hot air balloons work. (KR)

Brimicombe, M. W.

1991-01-01

282

Computer Modeling Of Atomization  

NASA Technical Reports Server (NTRS)

Improved mathematical models based on fundamental principles of conservation of mass, energy, and momentum developed for use in computer simulation of atomization of jets of liquid fuel in rocket engines. Models also used to study atomization in terrestrial applications; prove especially useful in designing improved industrial sprays - humidifier water sprays, chemical process sprays, and sprays of molten metal. Because present improved mathematical models based on first principles, they are minimally dependent on empirical correlations and better able to represent hot-flow conditions that prevail in rocket engines and are too severe to be accessible for detailed experimentation.

Giridharan, M.; Ibrahim, E.; Przekwas, A.; Cheuch, S.; Krishnan, A.; Yang, H.; Lee, J.

1994-01-01

283

Radiation Research: Chemistry and Physics.  

National Technical Information Service (NTIS)

Papers in this Proceedings are grouped under the following headings: (1) primary processes in radiation physics and chemistry; (2) radiation chemistry - general chemistry; (3) radiation chemistry - DNA and model systems; (4) radiation chemistry - other mo...

J. J. Broerse G. W. Barendsen H. B. Kal A. J. van der Kogel

1983-01-01

284

Trace Chemistry  

NASA Technical Reports Server (NTRS)

The goals of the trace chemistry group were to identify the processes relevant to aerosol and aerosol precursor formation occurring within aircraft gas turbine engines; that is, within the combustor, turbine, and nozzle. The topics of discussion focused on whether the chemistry of aerosol formation is homogeneous or heterogeneous; what species are important for aerosol and aerosol precursor formation; what modeling/theoretical activities to pursue; what experiments to carry out that both support modeling activities and elucidate fundamental processes; and the role of particulates in aerosol and aerosol precursor formation. The consensus of the group was that attention should be focused on SO2, SO3, and aerosols. Of immediate concern is the measurement of the concentration of the species SO3, SO2, H2SO4 OH, HO2, H2O2, O, NO, NO2, HONO, HNO3, CO, and CO2 and particulates in various engines, both those currently in use and those in development. The recommendation was that concentration measurements should be made at both the combustor exit and the engine exit. At each location the above species were classified into one of four categories of decreasing importance, Priority I through IV, as follows: Combustor exit: Priority I species - SO3:SO2 ratio, SO3, SO2, and particulates; Priority II species: OH and O; Priority III species - NO and NO2; and Priority IV species - CO and CO2. For the Engine exit: Priority I species - SO3:SO2 ratio, SO3, SO2,H2SO4, and particulates; Priority II species: OH,HO2, H2O2, and O; Priority III species - NO, NO2, HONO, and HNO3; and Priority IV species - CO and CO2. Table I summarizes the anticipated concentration range of each of these species. For particulate matter, the quantities of interest are the number density, size distribution, and composition. In order to provide data for validating multidimensional reacting flow models, it would be desirable to make 2-D, time-resolved measurements of the concentrations of the above species and, in addition, of the pressure, temperature, and velocity. A near term goal of the experimental program should be to confirm the nonlinear effects of sulfur speciation, and if present, to provide an explanation for them. It is also desirable to examine if the particulate matter retains any sulfur. The recommendation is to examine the effects on SOx production of variations in fuel-bound sulfur and aromatic content (which may affect the amount of particulates formed). These experiments should help us to understand if there is a coupling between particulate formation and SO, concentration. Similarly, any coupling with NOx can be examined either by introducing NOx into the combustion air or by using fuel-bound nitrogen. Also of immediate urgency is the need to establish and validate a detailed mechanism for sulfur oxidation/aerosol formation, whose chemistry is concluded to be homogeneous, because there is not enough surface area for heterogeneous effects. It is envisaged that this work will involve both experimental and theoretical programs. The experimental work will require, in addition to the measurements described above, fundamental studies in devices such as flow reactors and shock tubes. Complementing this effort should be modeling and theoretical activities. One impediment to the successful modeling of sulfur oxidation is the lack of reliable data for thermodynamic and transport properties for several species, such as aqueous nitric acid, sulfur oxides, and sulfuric acid. Quantum mechanical calculations are recommended as a convenient means of deriving values for these properties. Such calculations would also help establish rate constants for several important reactions for which experimental measurements are inherently fraught with uncertainty. Efforts to implement sufficiently detailed chemistry into computational fluid dynamic codes should be continued. Zero- and one-dimensional flow models are also useful vehicles for elucidating the minimal set of species and reactions that must be included in two- and three-dimensional modeling studies.

Radhakrishnan, Krishnan; Whitefield, Philip

1999-01-01

285

Elementary and brief introduction of hadronic chemistry  

NASA Astrophysics Data System (ADS)

The discipline, today known as Quantum Chemistry for atomic and subatomic level interactions has no doubt made a significant historical contributions to the society. Despite of its significant achievements, quantum chemistry is also known for its widespread denial of insufficiencies it inherits. An Italian-American Scientist Professor Ruggero Maria Santilli during his more than five decades of dedicated and sustained research has denounced the fact that quantum chemistry is mostly based on mere nomenclatures without any quantitative scientific contents. Professor R M Santilli first formulated the iso-, geno- and hyper-mathematics [1-4] that helped in understanding numerous diversified problems and removing inadequacies in most of the established and celebrated theories of 20th century physics and chemistry. This involves the isotopic, genotopic, etc. lifting of Lie algebra that generated Lie admissible mathematics to properly describe irreversible processes. The studies on Hadronic Mechanics in general and chemistry in particular based on Santilli's mathematics[3-5] for the first time has removed the very fundamental limitations of quantum chemistry [2, 6-8]. In the present discussion, we have briefly reviewed the conceptual foundations of Hadronic Chemistry that imparts the completeness to the Quantum Chemistry via an addition of effects at distances of the order of 1 fm (only) which are assumed to be Non-linear, Non-local, Non-potential, Non-hamiltonian and thus Non-unitary and its application in development of a new chemical species called Magnecules.

Tangde, Vijay M.

2013-10-01

286

Nuclear chemistry progress report  

SciTech Connect

This is the annual progress report for the Indiana University nuclear chemistry program for the 1992/1993 year. Accomplishments include the construction, testing, and initial experimental runs of the Indiana Silicon Sphere (ISiS) 4{pi} charged particle detector. ISiS is designed to study energy dissipation and multifragmentation phenomena in light-ion-induced nuclear reactions at medium-to-high energies. Its second test run was to examine 3.6 GeV {sup 3}He beam reactions at Laboratoire National Saturne (LNS) in Saclay. The development and deployment of this system has occupied a great deal of the groups effort this reporting period. Additional work includes: calculations of isotopic IMF yields in the {sup 4}He + {sup 116,124}Sn reaction; cross sections for A = 6 - 30 fragments from the {sup 4}He + {sup 28}Si reaction at 117 and 198 MeV; charging effects of passivated silicon detectors; neck emission of intermediate-mass fragments in the fission of hot heavy nuclei.

Viola, V.E.; Kwiatkowski, K.

1993-08-01

287

Gumdrop Atoms  

NSDL National Science Digital Library

Students use gumdrops and toothpicks to make lithium atom models. Using these models, they investigate the makeup of atoms, including their relative size. Students are then asked to form molecules out of atoms, much in the same way they constructed atoms out of the particles that atoms are made of. Students also practice adding and subtracting electrons from an atom and determining the overall charges on atoms.

Integrated Teaching And Learning Program

288

Atom-photon pair laser  

SciTech Connect

We study the quantum dynamics of an ultracold atomic gas trapped in an optical lattice within an optical high-Q resonator. The atoms are coherently illuminated with the cavity resonance tuned to a blue vibrational sideband so that stimulated gain of the resonator mode is accompanied by vibrational cooling of the atoms. This system exhibits a threshold above which pairwise stimulated generation of a cavity photon and an atom in the lowest vibrational band dominates spontaneous scattering and we find a combination of optical lasing with a buildup of a macroscopic population in the lowest lattice band. Including output coupling of ground-state atoms and replenishing of hot atoms into the cavity volume leads to a coherent, quantum correlated atom-photon pair source very analogous to twin light beam generation in a nondegenerate optical parametric oscillator.

Salzburger, Thomas; Ritsch, Helmut [Institute for Theoretical Physics, University of Innsbruck, Technikerstrasse 25/2, 6020 Innsbruck (Austria)

2007-06-15

289

Atom-photon pair laser  

NASA Astrophysics Data System (ADS)

We study the quantum dynamics of an ultracold atomic gas trapped in an optical lattice within an optical high- Q resonator. The atoms are coherently illuminated with the cavity resonance tuned to a blue vibrational sideband so that stimulated gain of the resonator mode is accompanied by vibrational cooling of the atoms. This system exhibits a threshold above which pairwise stimulated generation of a cavity photon and an atom in the lowest vibrational band dominates spontaneous scattering and we find a combination of optical lasing with a buildup of a macroscopic population in the lowest lattice band. Including output coupling of ground-state atoms and replenishing of hot atoms into the cavity volume leads to a coherent, quantum correlated atom-photon pair source very analogous to twin light beam generation in a nondegenerate optical parametric oscillator.

Salzburger, Thomas; Ritsch, Helmut

2007-06-01

290

ACS Green Chemistry Institute  

NSDL National Science Digital Library

This special feature page from the American Chemical Society (ACS) showcases the up-and-coming field of "green chemistry," that is, the development of chemical products and processes that eliminate or reduce the use and generation of hazardous substances. A list of principles behind green chemistry, a searchable bibliography of green chemistry references, and green chemistry links (including conferences). This page comes from ACS's Green Chemistry Project, a three-year educational project to develop and disseminate green chemistry educational materials for graduate and undergraduate chemistry students.

2005-12-13

291

Laboratory studies into the cosmic origins of organic chemistry  

NASA Astrophysics Data System (ADS)

We have constructed a novel merged-beams apparatus to study the cosmic origins of organic chemistry. Here we report rate coefficients measurements for reactions of atomic C with H+3. These data are important for astrochemical models.

de Ruette, N.; Miller, K. A.; O'Connor, A. P.; Sttzel, J.; Urbain, X.; Savin, D. W.

2014-04-01

292

Development and Formative Evaluation of Computer Simulated College Chemistry Experiments.  

ERIC Educational Resources Information Center

This article describes the design, preparation, and initial evaluation of a set of computer-simulated chemistry experiments. The experiments entailed the use of an atomic emission spectroscope and a single-beam visible absorption spectrophometer. (Author/IRT)

Cavin, Claudia S.; Cavin, E. D.

1978-01-01

293

Delights of Chemistry  

NSDL National Science Digital Library

Developed by the University of Leeds, the Delights of Chemistry promotes the art of chemistry demonstrations. Users can find illustrations and explanations of forty chemistry experiments. Many animations of demonstrations including the magnesium lamp, thermite reaction, and the volcano reaction are available. The website is full of pictures of chemistry equipment and scientists at work. Through this site, students and educators are able to explore fun chemistry experiments without having to worry about the many hazards associated with working with chemicals.

294

Provocative Opinion: Can Chemistry be Learned Without Understanding?  

ERIC Educational Resources Information Center

Voices the opinion that clearer and more useful explanations of common chemistry are needed to facilitate understanding. Presents examples from the realms of atomic structure, periodic table, history of chemistry, valence, electronegativity, electrode potentials, covalent bonds, polar covalence, bond energy, and causes of chemical change. (GS)

Sanderson, R. T.

1974-01-01

295

AtomDB: Atomic data for X-ray astronomy  

NASA Astrophysics Data System (ADS)

This paper outlines some of the progress in the AtomDB project, which aims to model X-ray emission from hot, collisionally ionized plasmas. We define data formats for ionization, recombination, photo-ionization and autoionization. We discuss the inclusion of the XSTAR database in AtomDB, in particular using the photoionization data, and the progress in preparing a full non-equilibrium ionization model for use by modelers and observers.

Foster, Adam R.; Ji, Li; Yamaguchi, Hiroya; Smith, Randall K.; Brickhouse, Nancy S.

2013-07-01

296

Hot carbon corona in Mars' upper thermosphere and exosphere: 1. Mechanisms and structure of the hot corona for low solar activity at equinox  

NASA Astrophysics Data System (ADS)

important source reactions for hot atomic carbon on Mars are photodissociation of CO and dissociative recombination of CO+; both reactions are highly sensitive to solar activity and occur mostly deep in the dayside thermosphere. The production of energetic particles results in the formation of hot coronae that are made up of neutral atoms including hot carbon. Some of these atoms are on ballistic trajectories and return to the thermosphere, and others escape. Understanding the physics in this region requires modeling that captures the complicated dynamics of hot atoms in 3-D. This study evaluates the carbon atom inventory by investigating the production and distribution of energetic carbon atoms using the full 3-D atmospheric input. The methodology and details of the hot atomic carbon model calculation are given, and the calculated total global escape of hot carbon from the assumed dominant photochemical processes at a fixed condition, equinox (Ls = 180), and low solar activity (F10.7 = 70 at Earth) are presented. To investigate the dynamics of these energetic neutral atoms, we have coupled a self-consistent 3-D global kinetic model, the Adaptive Mesh Particle Simulator, with a 3-D thermosphere/ionosphere model, the Mars Thermosphere General Circulation Model to provide a self-consistent global description of the hot carbon corona in the upper thermosphere and exosphere. The spatial distributions of density and temperature and atmospheric loss are simulated for the case considered.

Lee, Yuni; Combi, Michael R.; Tenishev, Valeriy; Bougher, Stephen W.

2014-05-01

297

Chemistry Rocks: Redox Chemistry as a Geologic Tool.  

ERIC Educational Resources Information Center

Applies chemistry to earth science, uses rocks in chemistry laboratories, and teaches about transition metal chemistry, oxidation states, and oxidation-reduction reactions from firsthand experiences. (YDS)

Burns, Mary Sue

2001-01-01

298

Descriptive Chemistry in High School Curriculum.  

ERIC Educational Resources Information Center

Discusses incorporation of descriptive chemistry and scientific/technical writing at the high school level. After discussing the periodic table, each student prepares a paper discussing the history, atomic data, occurring/extraction/purification, properties, and uses of an element. (JN)

Rajan, Raj G.

1983-01-01

299

HotBot  

NSDL National Science Digital Library

HotBot, a service of HotWired Ventures, uses the Inktomi search engine as the heart of its new Internet search service. It claims to index the full text contents of 50 million Web pages, as well as Usenet news and mailing lists. This would make it the largest search engine on the Internet. HotBot supports Boolean AND/OR/NOT, and phrase searching. It provides relevance feedback with retrieval. It also supports chronological, domain, and geographic searches, as well as media type searches such as Java, VRML, and Acrobat. HotBot is a public "beta" site and encourages feedback and bug reports.

300

Is There an Irreducible Chemistry Core? A Shot from a Canonical Cannon.  

ERIC Educational Resources Information Center

Argues for including several key ideas in every introductory general chemistry course, including the phenomena of chemistry, the organization and classification of matter, atomic structure, molecular bonding and molecular structure, the language of chemistry, the mole, chemical reactions and reactivity, chemical kinetics, chemical equilibrium, and

Schwartz, A. Truman

1999-01-01

301

Advancing manufacturing through computational chemistry  

SciTech Connect

The capabilities of nanotechnology and computational chemistry are reaching a point of convergence. New computer hardware and novel computational methods have created opportunities to test proposed nanometer-scale devices, investigate molecular manufacturing and model and predict properties of new materials. Experimental methods are also beginning to provide new capabilities that make the possibility of manufacturing various devices with atomic precision tangible. In this paper, we will discuss some of the novel computational methods we have used in molecular dynamics simulations of polymer processes, neural network predictions of new materials, and simulations of proposed nano-bearings and fluid dynamics in nano- sized devices.

Noid, D.W.; Sumpter, B.G.; Tuzun, R.E.

1995-12-31

302

Collaborative Physical Chemistry Projects Involving Computational Chemistry  

Microsoft Academic Search

The physical chemistry classes from three colleges have collaborated on two computational chemistry projects using Quantum CAChe 3.0 and Gaussian 94W running on Pentium II PCs. Online communication by email and the World Wide Web was an important part of the collaboration. In the first project, students used molecular modeling to predict benzene derivatives that might be possible hair dyes.

David M. Whisnant; Jerry J. Howe; Lisa S. Lever

2000-01-01

303

Using Games To Teach Chemistry: An Annotated Bibliography  

NASA Astrophysics Data System (ADS)

A list of published or marketed games based on a chemistry motif is presented. Each game is listed according to its level, subject matter, and title. A bibliographic notation and a short description are given for each game. For Introductory/High School/General Chemistry, 45 games are listed under the subjects General Knowledge; Elements & Atomic Structure (not Symbols); Nomenclature, Formulas, & Equation Writing; Chemical Reactions: Solutions & Solubilities; and Other Subjects. Seventeen games are listed under Organic Chemistry and 4 games under Other Chemistry Games. Computer games designed for outdated computers (PDP-11, TRS-80, and Apple II) are not included.

Russell, Jeanne V.

1999-04-01

304

Organometallic Chemistry of Molybdenum.  

ERIC Educational Resources Information Center

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)

Lucas, C. Robert; Walsh, Kelly A.

1987-01-01

305

Chemistry for Potters.  

ERIC Educational Resources Information Center

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)

Denio, Allen A.

1980-01-01

306

Digital Resource Package for Teaching Atomic Structure  

NSDL National Science Digital Library

This digital resource package is a collection of online sources to help K-12 teachers create lessons on the Chemistry subject of atomic structures. Topics include The History of the Atom, Reference Material, Tutorials, Simulations, Questions and Activities, Periodic Tables, and resources for more advanced learners.

Moin, Laura

307

Preliminary geothermal investigations at Manley Hot Springs, Alaska  

SciTech Connect

Manley Hot Springs is one of several hot springs which form a belt extending from the Seward Peninsula to east-central Alaska. All of the hot springs are low-temperature, water-dominated geothermal systems, having formed as the result of circulation of meteoric water along deepseated fractures near or within granitic intrusives. Shallow, thermally disturbed ground at Manley Hot Springs constitutes an area of 1.2 km by 0.6 km along the lower slopes of Bean Ridge on the north side of the Tanana Valley. This area includes 32 springs and seeps and one warm (29.1/sup 0/C) well. The hottest springs range in temperature from 61/sup 0/ to 47/sup 0/C and are presently utilized for space heating and irrigation. This study was designed to characterize the geothermal system present at Manley Hot Springs and delineate likely sites for geothermal drilling. Several surveys were conducted over a grid system which included shallow ground temperature, helium soil gas, mercury soil and resistivity surveys. In addition, a reconnaissance ground temperature survey and water chemistry sampling program was undertaken. The preliminary results, including some preliminary water chemistry, show that shallow hydrothermal activity can be delineated by many of the surveys. Three localities are targeted as likely geothermal well sites, and a model is proposed for the geothermal system at Manley Hot Springs.

East, J.

1982-04-01

308

Implications of SWAS Observations for Interstellar Chemistry and Star Formation  

NASA Technical Reports Server (NTRS)

A long standing prediction of steady state gas-phase chemical theory is that H2O and O2 are important reservoirs of elemental oxygen and major coolants of the interstellar medium. Analysis of SWAS observations has set sensitive upper limits on the abundance Of O2 and has provided H2O abundances toward a variety of star forming regions. Based on these results, we show that gaseous H2O and O2 are not dominant carriers of elemental oxygen in molecular clouds. Instead the available oxygen is presumably frozen on dust grains in the form of molecular ices, with a significant portion potentially remaining in atomic form, along with CO, in the gas phase. H2O and O2 are also not significant coolants for quiescent molecular gas. In the case of H2O, a number of known chemical processes can locally elevate its abundance in regions with enhanced temperatures, such as warm regions surrounding young stars or in hot shocked gas. Thus, water can be a locally important coolant. The new information provided by SWAS, when combined with recent results from the Infrared Space Observatory, also provide several hard observational constraints for theoretical models of the chemistry in molecular clouds and we discuss various models that satisfy these conditions.

Bergin, Edwin A.; Melnick, Gary J.; Stauffer, John R.; Ashby, Matthew L. N.; Chin, Gordon; Erickson, Neal R.; Goldsmith, Paul F.; Harwit, Martin; Howe, John E.; Kleiner, Steven C.

2000-01-01

309

Study on effects of powder and flake chemistry and morphology on the properties of Al-Cu-Mg-X-X-X powder metallurgy advanced aluminum alloys  

NASA Technical Reports Server (NTRS)

The effects of alloy chemistry and particulate morphology on consolidation behavior and consolidated product properties in rapid solidification processed, powder-metallurgical Al-3Li-1.5Cu-1Mg-0.5Co-0.2Zr and Al-4.4Cu-1.5Mg-Fe-Ni-0.2Zr extrusions and forgings were studied. Microstructures and mechanical properties of both alloys are largely unaffected by particulate production method (vacuum atomization, ultrasonic atomization, or twin-roller quenching) and by particulate solidification rates between 1000 and 100,000 K/s. Consolidation processing by canning, cold compaction, degassing, and hot extrusion is sufficient to yield mechanical properties in the non-Li-containing alloy extrusions which are similar to those of 7075-Al, but ductilities and fracture toughnesses are inferior owing to poor interparticle bonding caused by lack of a vacuum-hot-pressing step during consolidation. Mechanical properties of extrusions are superior to those of forgings owing to the stronger textures produced by the more severe hot working during extrusion. The effects on mechanical properties of dispersoid size and volume fraction, substructural refinement, solid solution strengthening by Mg, and precipitate size and distribution are elucidated for both alloy types.

Meschter, P. J.; Lederich, R. J.; Oneal, J. E.; Pao, P. S.

1985-01-01

310

School Chemistry vs. Chemistry in Research: An Exploratory Experiment.  

ERIC Educational Resources Information Center

Reports on a study exploring why students are not studying chemistry. Three groups of graduating high school students and their chemistry teachers stayed at a research institute working on molecular modeling and wrote essays on school chemistry versus chemistry in research. Concludes that school chemistry does not convey today's chemistry in

Habraken, Clarisse L.; Buijs, Wim; Borkent, Hens; Ligeon, Willy; Wender, Harry; Meijer, Marijn

2001-01-01

311

Hot Spot at Yellowstone  

ERIC Educational Resources Information Center

Within this huge national park (over two million acres spread across Wyoming, Montana, and Idaho) are steaming geysers, hot springs, bubbling mudpots, and fumaroles, or steam vents. Drives on the main roads of Yellowstone take tourists through the major hot attractions, which also include Norris Geyser Basin, Upper and Lower Geyser Basin, West

Dress, Abby

2005-01-01

312

Hot Air Balloon  

NSDL National Science Digital Library

In this activity, learners build a hot air balloon using just a few sheets of tissue paper and a hair dryer. Use this activity to demonstrate how hot air rises due to density and how the volume of gas increases with temperature (Charles's Law).

Centers, Oakland D.

2012-01-01

313

Hot yoga and pregnancy  

PubMed Central

Abstract Question One of my pregnant patients wishes to continue her hot yoga exercises during pregnancy. Is this practice safe? Answer With the increased risk of neural tube defects and possibly of other malformations among fetuses exposed to excessive heat, pregnant women should avoid practising hot yoga during pregnancy.

Chan, Justin; Natekar, Aniket; Koren, Gideon

2014-01-01

314

Solar Hot Box  

NSDL National Science Digital Library

In this lesson, students explore different aspects of solar energy by building a solar hot box and testing various colors and materials to find the maximum temperature that can be reached. They will review the basic needs for alternative energy sources, identify three materials and colors that will produce maximum heat, and solve a design problem for the hot box.

315

Hot water heating system  

Microsoft Academic Search

A solar hot water heating system has a primary tank heated by solar energy utilizing a heat transfer medium circulated between a solar collector and a heat exchanger located in the primary tank. Usually a back-up tank is provided to supplement the solar system. The primary tank receives cold water from a pressurized source. Its hot water outlet is connected

1984-01-01

316

Household hot water systems  

Microsoft Academic Search

An arrangement for combination with the conventional hot water system of a house or building in which the water is conventionally heated and stored in a tank, the arrangement comprising a solar energy panel (at an upper level) with a thermostatic valve and a supplementary cold water tank, connected into the system in such a way that hot water is

Tacchi

1983-01-01

317

Hot Weather Tips  

MedlinePLUS

... A A + A You are here Home HOT Weather Tips Printer-friendly version We all suffer in hot weather. However, for elderly and disabled people and those ... conditions such as vascular disease or diabetes, the weather does not have to hit 100 degrees to ...

318

The Earth's Hot Spots.  

ERIC Educational Resources Information Center

Hot spots are isolated areas of geologic activity where volcanic eruptions, earthquakes, and upwelling currents occur far from plate boundaries. These mantle plumes are relatively stable and crustal plates drift over them. The nature and location of hot spots (with particular attention to the Hawaiian Islands and Iceland) are discussed. (DH)

Vink, Gregory E.; And Others

1985-01-01

319

History of Chemistry.  

ERIC Educational Resources Information Center

Discusses the development of chemistry in the United States by considering: (1) chemistry as an evolving body of ideas/techniques, and as a set of conceptual resources affecting and affected by the development of other sciences; and (2) chemistry related to the history of American social and economic institutions and practices. (JN)

Servos, John W.

1985-01-01

320

Mechanisms in Photographic Chemistry  

ERIC Educational Resources Information Center

Reviews current research interests in photographic chemistry, involving two proposed models for spectral sensitization of crystal defects and impurities in the photolysis reactivity and the mechanisms of development and complexation. Establishment of photographic chemistry in a chemistry curriculum is recommended. (CC)

Sahyun, M. R. V.

1974-01-01

321

Teaching School Chemistry.  

ERIC Educational Resources Information Center

This eight-chapter book is intended for use by chemistry teachers, curriculum developers, teacher educators, and other key personnel working in the field of chemical education. The chapters are: (1) "The Changing Face of Chemistry" (J. A. Campbell); (2) "Curriculum Innovation in School Chemistry" (R. B. Ingel and A. M. Ranaweera); (3) "Some

Waddington, D. J., Ed.

322

Chemistry as General Education  

ERIC Educational Resources Information Center

The efficacy of different science and chemistry courses for science-major and non-major students, and the question of chemistry's contribution to general education are evaluated. Chemistry and science curriculum are too profession- and consumer-oriented, and to overcome this problem, it is advised that all disciplines must incorporate the major

Tro, Nivaldo J.

2004-01-01

323

Green Chemistry and Education.  

ERIC Educational Resources Information Center

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)

Hjeresen, Dennis L.; Schutt, David L.; Boese, Janet M.

2000-01-01

324

Fuel Chemistry Preprints  

SciTech Connect

Papers are presented under the following symposia titles: advances in fuel cell research; biorefineries - renewable fuels and chemicals; chemistry of fuels and emerging fuel technologies; fuel processing for hydrogen production; membranes for energy and fuel applications; new progress in C1 chemistry; research challenges for the hydrogen economy, hydrogen storage; SciMix fuel chemistry; and ultraclean transportation fuels.

NONE

2005-09-30

325

Chemistry of fast electrons  

PubMed Central

A chemicurrent is a flux of fast (kinetic energy ? 0.5?1.3 eV) metal electrons caused by moderately exothermic (1?3 eV) chemical reactions over high work function (4?6 eV) metal surfaces. In this report, the relation between chemicurrent and surface chemistry is elucidated with a combination of top-down phenomenology and bottom-up atomic-scale modeling. Examination of catalytic CO oxidation, an example which exhibits a chemicurrent, reveals 3 constituents of this relation: The localization of some conduction electrons to the surface via a reduction reaction, 0.5 O2 + ?e? ? O?? (Red); the delocalization of some surface electrons into a conduction band in an oxidation reaction, O?? + CO ? CO2?? ? CO2 + ?e? (Ox); and relaxation without charge transfer (Rel). Juxtaposition of Red, Ox, and Rel produces a daunting variety of metal electronic excitations, but only those that originate from CO2 reactive desorption are long-range and fast enough to dominate the chemicurrent. The chemicurrent yield depends on the universality class of the desorption process and the distribution of the desorption thresholds. This analysis implies a power-law relation with exponent 2.66 between the chemicurrent and the heat of adsorption, which is consistent with experimental findings for a range of systems. This picture also applies to other oxidation-reduction reactions over high work function metal surfaces.

Maximoff, Sergey N.; Head-Gordon, Martin P.

2009-01-01

326

Computational chemistry research  

NASA Technical Reports Server (NTRS)

Task 41 is composed of two parts: (1) analysis and design studies related to the Numerical Aerodynamic Simulation (NAS) Extended Operating Configuration (EOC) and (2) computational chemistry. During the first half of 1987, Dr. Levin served as a member of an advanced system planning team to establish the requirements, goals, and principal technical characteristics of the NAS EOC. A paper entitled 'Scaling of Data Communications for an Advanced Supercomputer Network' is included. The high temperature transport properties (such as viscosity, thermal conductivity, etc.) of the major constituents of air (oxygen and nitrogen) were correctly determined. The results of prior ab initio computer solutions of the Schroedinger equation were combined with the best available experimental data to obtain complete interaction potentials for both neutral and ion-atom collision partners. These potentials were then used in a computer program to evaluate the collision cross-sections from which the transport properties could be determined. A paper entitled 'High Temperature Transport Properties of Air' is included.

Levin, Eugene

1987-01-01

327

Chemistry with Inexpensive Materials: Spray Bottles and Plastic Bags.  

ERIC Educational Resources Information Center

Presents eight chemistry activities that are interesting and involve simple, easily available materials. Topics include mystery writing, valentine hearts, flame tests, evaporation race, buoyancy versus mass, determination of relative masses of gases, mole sample container, and cold and hot packs. (DDR)

Zoltewicz, Susan

1993-01-01

328

Atom-by-atom assembly  

NASA Astrophysics Data System (ADS)

Atomic manipulation using a scanning tunneling microscope (STM) tip enables the construction of quantum structures on an atom-by-atom basis, as well as the investigation of the electronic and dynamical properties of individual atoms on a one-atom-at-a-time basis. An STM is not only an instrument that is used to see individual atoms by means of imaging, but is also a tool that is used to touch and take the atoms, or to hear their movements. Therefore, the STM can be considered as the eyes, hands and ears of the scientists, connecting our macroscopic world to the exciting atomic world. In this article, various STM atom manipulation schemes and their example applications are described. The future directions of atomic level assembly on surfaces using scanning probe tips are also discussed.

Hla, Saw Wai

2014-05-01

329

Atom-by-atom assembly.  

PubMed

Atomic manipulation using a scanning tunneling microscope (STM) tip enables the construction of quantum structures on an atom-by-atom basis, as well as the investigation of the electronic and dynamical properties of individual atoms on a one-atom-at-a-time basis. An STM is not only an instrument that is used to 'see' individual atoms by means of imaging, but is also a tool that is used to 'touch' and 'take' the atoms, or to 'hear' their movements. Therefore, the STM can be considered as the 'eyes', 'hands' and 'ears' of the scientists, connecting our macroscopic world to the exciting atomic world. In this article, various STM atom manipulation schemes and their example applications are described. The future directions of atomic level assembly on surfaces using scanning probe tips are also discussed. PMID:24787453

Hla, Saw Wai

2014-05-01

330

Principles of Environmental Chemistry  

NASA Astrophysics Data System (ADS)

Roy M. Harrison, Editor RSC Publishing; ISBN 0854043713; x + 363 pp.; 2006; $69.95 Environmental chemistry is an interdisciplinary science that includes chemistry of the air, water, and soil. Although it may be confused with green chemistry, which deals with potential pollution reduction, environmental chemistry is the scientific study of the chemical and biochemical principles that occur in nature. Therefore, it is the study of the sources, reactions, transport, effects, and fates of chemical species in the air, water, and soil environments, and the effect of human activity on them. Environmental chemistry not only explores each of these environments, but also closely examines the interfaces and boundaries where the environments intersect.

Hathaway, Ruth A.

2007-07-01

331

Sulphur Chemistry in the Envelopes of Massive Young Stars  

NASA Astrophysics Data System (ADS)

The sulphur chemistry in eight regions of massive star formation is studied through single-dish submillimeter spectroscopy. The SO line profiles show that up to 50% of the SO emission arises in bipolar outflows, much more than found previously for CS. Rotation temperatures of SO and SO2 range from 26 to 75 K for both envelope and outflow, while two sources show additional hot (>sim 200 K) SO2 in their envelopes. Column densities are 1014 cm-2 for H2S, OCS, SO and SO2, 1013 cm-2 for H2CS, and 1012 cm-2 for HCS+ and NS. The hot, abundant SO2 seen previously in infrared absorption is not picked up, so its angular size must be small. Molecular abundances are calculated with a Monte Carlo program, using the physical structures of the sources derived from previous submillimeter continuum and CS line data. Abundances are 10-8 for H2S, OCS, SO and SO2, 10-9 for H2CS, and 10-10 for HCS+ and NS. For SO and SO2, the number of detected lines is large enough to derive radial abundance profiles, and therefore to study their chemistry as a function of temperature. While the SO abundance appears constant over the range T = 20-80 K, the SO2 abundance may increase at T >sim 100 K. The derived abundances are compared to models of shock chemistry, hot core chemistry and high-temperature envelope chemistry.

van der Tak, Floris F. S.; Boonman, Annemieke M. S.; Braakman, Rogier; van Dishoeck, Ewine F.

332

Some Exercises Reflecting Green Chemistry Concepts  

NASA Astrophysics Data System (ADS)

Three exercises related to green chemistry are presented. In the first exercise students compare two methods to prepare aluminum hydroxide and find a new method that can save more feedstock. The second exercise has students selecting a process that reflects the atom economy concept in three methods of preparing Cu(NO 3 ) 2 . In the third exercise students determine the most reasonable ratio of stoichiometry map for maximum utilization of FeS to prepare Na 2 S 2 O 3 5H 2 O. Through these exercises, students learn the effect of green chemistry concepts.

Song, Yu-Min; Wang, Yong-Cheng; Geng, Zhi-Yuan

2004-05-01

333

Computational chemistry and aeroassisted orbital transfer vehicles  

NASA Technical Reports Server (NTRS)

An analysis of the radiative heating phenomena encountered during a typical aeroassisted orbital transfer vehicle (AOTV) trajectory was made to determine the potential impact of computational chemistry on AOTV design technology. Both equilibrium and nonequilibrium radiation mechanisms were considered. This analysis showed that computational chemistry can be used to predict (1) radiative intensity factors and spectroscopic data; (2) the excitation rates of both atoms and molecules; (3) high-temperature reaction rate constants for metathesis and charge exchange reactions; (4) particle ionization and neutralization rates and cross sections; and (5) spectral line widths.

Cooper, D. M.; Jaffe, R. L.; Arnold, J. O.

1985-01-01

334

CSA Hot Topics Series  

NSDL National Science Digital Library

The Hot Topics series provides a free sampling of the resources in Cambridge Scientific Abstracts (CSA) and the Internet Database Service (IDS). The 30 topics span subjects in the humanities, engineering, environmental policy, and medicine. Each Hot Topic gives an overview of the subject, key citations with abstracts, a list of Websites, a glossary, a comment form so that users can correspond with the editors, and a "source" section, which explains from which of CSA's paid services the resources were culled. The latest hot topic is MicroElectroMechanical systems (MEMS), "small integrated devices or systems that combine electrical and mechanical components."

335

Hot ice computer  

NASA Astrophysics Data System (ADS)

We experimentally demonstrate that supersaturated solution of sodium acetate, commonly called hot ice, is a massively-parallel unconventional computer. In the hot ice computer data are represented by a spatial configuration of crystallization induction sites and physical obstacles immersed in the experimental container. Computation is implemented by propagation and interaction of growing crystals initiated at the data-sites. We discuss experimental prototypes of hot ice processors which compute planar Voronoi diagram, shortest collision-free paths and implement AND and OR logical gates.

Adamatzky, Andrew

2009-12-01

336

Atom Interferometers  

Microsoft Academic Search

Interference with atomic and molecular matter waves is a rich branch of\\u000aatomic physics and quantum optics. It started with atom diffraction from\\u000acrystal surfaces and the separated oscillatory fields technique used in atomic\\u000aclocks. Atom interferometry is now reaching maturity as a powerful art with\\u000amany applications in modern science. In this review we first describe the basic\\u000atools

Alexander D. Cronin; Joerg Schmiedmayer; David E. Pritchard

2007-01-01

337

Atom Interferometry  

Microsoft Academic Search

The first demonstrated atom interferometers, reported in 1991 by [1] and [2] were based on the diffraction of atoms with micro fabricated structures. This class of atom interferometers is analogous\\u000a to optical interferometers, where slits or diffraction gratings have been used to divide and recombine beams of atoms. The\\u000a gratings and slits can be either material structures or periodic light

S. Chu

338

Hot off the press.  

PubMed

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as penicillitone, a metabolite of Penicillium purpurogenum. PMID:24760346

Hill, Robert A; Sutherland, Andrew

2014-06-14

339

Hadronic Atoms  

NASA Astrophysics Data System (ADS)

We review the theory of hadronic atoms in the framework of quantum chromodynamics, with photons and electrons included (QCD+QED). We illustrate the method by means of ?+?- atoms and briefly consider the application of the same approach to several other hadronic atoms.

Gasser, J.; Lyubovitskij, V. E.; Rusetsky, A.

2009-11-01

340

Atomic Interferometers  

Microsoft Academic Search

We examine the role of laser phase in multiphoton excitation of atomic transitions. Closed loops in excitation linkages create interfering channels which depend on atomic and laser phases. Such phase-dependent dynamics suggest the use of these transition linkages as atomic interferometers in which states can be decoupled (and population trapped). We show how phase and amplitude measurements are possible in

S. J. Buckle; S. M. Barnett; P. L. Knight; M. A. Lauder; D. T. Pegg

1986-01-01

341

Atom interferometers  

Microsoft Academic Search

Atom interferometers have opened up new areas of fundamental and applied research. As well known from photon optics, multiple-beam interferometers offer an increased sensitivity on the relative phases between interfering waves. Very recently, first atomic multiple-beam interferometers were realized. These concepts are based on an atomic beam that is spatially split into coherent partial de Broglie waves, where the number

J. Lone; K. Sengstock; W. Ertmer

1998-01-01

342

Hot spots of Io  

NASA Technical Reports Server (NTRS)

The size and temperature, morphology and distribution, variability, possible absorption features, and processes of hot spots on Io are discussed, and an estimate of the global heat flux is made. Size and temperature information is deconvolved to obtain equivalent radius and temperature of hot spots, and simultaneously obtained Voyager thermal and imaging data is used to match hot sources with specific geologic features. In addition to their thermal output, it is possible that hot spots are also characterized by production of various gases and particulate materials; the spectral signature of SO2 has been seen. Origins for relatively stable, low temperature sources, transient high temperature sources, and relatively stable, high-tmperature sources are discussed.

Pearl, J. C.; Sinton, W. M.

1982-01-01

343

Hot Accretion Disks Revisited  

NASA Astrophysics Data System (ADS)

All previous studies of hot (Tp 1010-1012 K), optically thin accretion disks have neglected either the presence of e+ e- pairs or advective cooling. Thus all hot disk models constructed previously have not been self-consistent. In this paper we calculate local disk models including pair physics, relevant radiative processes in the hot plasma, and the effect of advective cooling. We use a modification of the Bjrnsson & Svensson mapping method. We find that the role of e+ e- pairs in the structure of hot, optically thin accretion disks is far less significant than was previously thought. The improved description of the radiation-matter interactions provided in the present paper modify the previously obtained values of the critical parameters characterizing advectively dominated flows.

Bjoernsson, Gunnlaugur; Abramowicz, Marek A.; Chen, Xingming; Lasota, Jean-Pierre

1996-08-01

344

Interstellar Chemistry Special Feature: Interferometric observations of large biologically interesting interstellar and cometary molecules  

NASA Astrophysics Data System (ADS)

Interferometric observations of high-mass regions in interstellar molecular clouds have revealed hot molecular cores that have substantial column densities of large, partly hydrogen-saturated molecules. Many of these molecules are of interest to biology and thus are labeled "biomolecules." Because the clouds containing these molecules provide the material for star formation, they may provide insight into presolar nebular chemistry, and the biomolecules may provide information about the potential of the associated interstellar chemistry for seeding newly formed planets with prebiotic organic chemistry. In this overview, events are outlined that led to the current interferometric array observations. Clues that connect this interstellar hot core chemistry to the solar system can be found in the cometary detection of methyl formate and the interferometric maps of cometary methanol. Major obstacles to understanding hot core chemistry remain because chemical models are not well developed and interferometric observations have not been very sensitive. Differentiation in the molecular isomers glycolaldehdye, methyl formate, and acetic acid has been observed, but not explained. The extended source structure for certain sugars, aldehydes, and alcohols may require nonthermal formation mechanisms such as shock heating of grains. Major advances in understanding the formation chemistry of hot core species can come from observations with the next generation of sensitive, high-resolution arrays. biomolecules | comets | chemistry

Snyder, Lewis E.

2006-08-01

345

Geothermal hot water system  

SciTech Connect

Geothermal hot water system including a hot water tank and a warm water tank which are heated independently of each other by a close loop freon system. The closed loop freon system includes a main condenser which heats water for the warm water tank and a super-heated condenser which heats water for the hot water tank, and where the freon passes through a water evaporator which is heated by water such as from a well or other suitable source. The water evaporator in the closed loop freon system passes the water through but no environmental change to the water. An electrical circuit including aquastats in the warm water tank connected therethrough controls operation of the closed loop freon system including respective pumps on the super-heated condenser and main condenser for pumping water. Pumps pump water through the main condenser for the warm tank and through the super-heated condenser for the hot tank. The system provides for energy conservation in that the head pressure of the compressor is kept in the lower operating ranges as determined by the discharge flow of the main condenser which varies by the head pressure and temperature flow control which varies by temperature. The geothermal hot water system uses a least amount of energy in heating the water in the hot tank as well as the warm tank.

Dittell, E.W.

1983-05-10

346

LEAFLASH SPRAY DRYER: INVESTIGATION OF THE ATOMIZATION PROCESS  

Microsoft Academic Search

The atomization process of the LEAFLASH spray dryer has been investigated by laser diffractometry and video imaging. The LEAFLASH atomizer is a particular pneumatic nozzle where the pressurized gas is the hot drying air. The drying and the atomization processes are interrelated in the spray dryer. Consequently the mixing of the liquid droplets and the drying medium is very efficient,

L. F Cl ment; E. D Dumoulin; S. Lagarde; C. Bourlier

1994-01-01

347

General Chemistry Online!  

NSDL National Science Digital Library

General Chemistry Online, created by Frederick Senese, a professor at Frostburg State University, is a guide and resource for introductory chemistry students. This site provides five areas of information: The Chemistry Home Companion, Just Ask Antoine!, Chemistry Exam Survival Guide, Tutorials, and a Featured Article. The Companion is a study guide covering the basic concepts of an introductory general chemistry course. Topics include measurement, molecules and compounds, and the quantum theory. Just Ask Antoine! allows students to post their chemistry questions. An archived list provides questions and answers for the past year. The Exam Survival Guide provides tips on passing exams, checklists of objectives and skills, and two online practice exams. The Tutorial currently contains only problems and quizzes for the measurement topic. The featured article for February is about Anandamide, a "messenger molecule that plays a role in pain, depression, appetite, memory, and fertility."

Senese, Frederick A.

348

Atom interferometers and atom holography  

SciTech Connect

Various techniques of atom manipulation with a binary hologram are discussed and demonstrated experimentally. An atomic beam of metastable neon in the 1s{sub 3} state and a SiN thin film with holes that expresses the transmission function of the hologram are used to demonstrate this technique. The gray-scale holography of atoms is demonstrated for the first time. Other possibilities of holographic manipulation of atoms are also discussed.

Shimizu, Fujio; Mitake, Satoru [Institute for Laser Science and CREST, University of Electro-Communications, Chofu-shi 182-8585 (Japan); Fujita, Jun-ichi [NEC Fundamental Research Laboratories, 34 Miyukigaoka, Tsukuba 305-0841 (Japan); Morinaga, Makoto [Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113 (Japan); Kishimoto, Tetsuo [Institute for Laser Science and CREST, University of Electro-Communications, Chofu-shi 182-8585 (Japan); Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113 (Japan)

1999-06-11

349

Atom interferometry  

SciTech Connect

This paper is organized as follows: In Section II we present an elementary treatment of the underlying principles of atom interferometry. The phase evolution of an atomic de Broglie wave and the coherence of an atomic beam are discussed. A beam splitter is a key component in an interferometer. The main techniques used to split an atomic beam coherently are considered in Section III. In Section IV we discuss possible applications of atom interferometry. The second part of the chapter concentrates on existing experiments in atom interferometry. Atom interferometers that have been realized are described, and experiments that use these devices are discussed. The chapter concludes with a summary and outlook. 61 refs., 14 figs.

Adams, C.S.; Carnal, O., Mlynek, J. [Universitaet Konstanz (Germany)

1994-12-31

350

Middle School Chemistry  

NSDL National Science Digital Library

Middle school science resource from ACS. It includes activity-based lesson plans for teaching basic chemistry concepts that cover all the main concepts in middle school chemistry. Each lesson also contains integrated animations and video that a teacher can use to help explain student observations on the molecular level. Online professional development will also be available to introduce and familiarize teachers with the demonstrations, activities, and chemistry content in the site.

351

Automatic hot water recovery system  

Microsoft Academic Search

Heat in the hot water lines of a water system is automatically recovered by providing a bridge conduit between the cold water lines and the hot water lines and by depressurizing the hot water lines relative to the cold water lines thereby to automatically direct higher pressure cold water into the hot water lines through the interconnection, which preferably is

Haws

1982-01-01

352

Connecting Algebra and Chemistry.  

ERIC Educational Resources Information Center

Correlates high school chemistry curriculum with high school algebra curriculum and makes the case for an integrated approach to mathematics and science instruction. Focuses on process integration. (DDR)

O'Connor, Sean

2003-01-01

353

Science Update: Analytical Chemistry.  

ERIC Educational Resources Information Center

Briefly discusses new instrumentation in the field of analytical chemistry. Advances in liquid chromatography, photoacoustic spectroscopy, the use of lasers, and mass spectrometry are also discussed. (CS)

Worthy, Ward

1980-01-01

354

Nitrous oxide combustion chemistry  

SciTech Connect

To gain improved understanding of N2O combustion chemistry, experimentation and numerical modeling were performed, and are described. Principal conclusions are: (1) N2O emission is quite temperature dependent, and (2) for lean, homogeneous combustion systems with peak temperatures higher than 1200 K and without rapid cooling, N2O emission is low. Thermochemical property variations have substantial effects on calculated species profiles. Changes in enthalpies of formation of NH, NH2, and NNH resulted in large differences in predicted NO, N2, and N2O concentrations. Measurements were made in lean, premixed, and atmospheric pressure flat flames by microprobe sampling and gas chromatographic or chemiluminescence analysis. With 2000 ppm of either NH3, NO, or N2O added to the reactants, N2O was observed at moderate concentrations near the burner surface, and a monotonically decreasing concentrations downstream. With NH3 as dopant, early- and post-flame N2O concentration varied inversely with temperature, as did its decay rate. With N2O as dopant, product branching to NO and N2 was 8 and 92 percent. Sensitivity and rate data indicated the primary N2O formation and destruction reactions to be NH + NO = N2O + H and H + N2O = N2 + OH, and that H + O2 + M = HO2 + M plays an important role in trapping H atoms to enhance N2O survival. Flash-ignited combustion experiments were performed and studied. A mixture, where NH3 was primary photolysis absorber and fuel species, burned inhomogeneously. Concentration profiles of N2, NO, O2, and N2O were recorded. N2O added to the reactants disappeared during combustion. Post-flame NO and N2 concentrations were higher than previously reported NH3 flames, but their ratio agreed well with earlier results.

Martin, R.J.

1989-01-01

355

A model of hollow cathode plasma chemistry  

NASA Technical Reports Server (NTRS)

We have developed a new model of hollow cathode plasma chemistry based on the observation that xenon ion mobility is diffusion limited due to resonant charge exchange reactions. The model shows that vapor phase barium atoms are ionized almost immediately and electric fields accelerate the ions upstream from the emission zone. We have also applied the model to the orifice region, where the resultant ion generation profile correlates with previously reported orifice erosion.

Katz, I.; Anderson, J. R.; Polk, J. E.; Brophy, J. R.

2002-01-01

356

Atomic Microclustering  

NASA Astrophysics Data System (ADS)

Buckminsterfullerene, C60, is a molecule with perfect symmetry made up of 60 carbon atoms arranged in the shape of a soccer ball. The geometric structure of C60 is that of a truncated icosahedron with a single carbon atom occypying each vertex. Such a structure is obtained from an icosahedron by truncating each of the 12 vertices, resulting in a 5-membered ring at the location of each vertex and a 6-membered ring corresponding to each icosahedral face. The molecule exhibits a high degree of stability. The bonding environment of each atom is identical and each atom is located at the intersection of two hexagons and a pentagon. Using numerical methods and atomic potentials of logarithmic type, I will show that the 60 particles spontaneously form 12 clusters of 5 particles per cluster. The stability of this buckyball configuration is highly sensitive to the atomic interaction law, which calculations based solely on adjacency eigenvalues do not reveal.

Khushalani, Bharat

2004-05-01

357

Career Options in Chemistry.  

ERIC Educational Resources Information Center

Describes a credit/no credit course which focuses on career options in chemistry. The course (consisting of 15 one-hour seminar-type sessions) includes guest speakers for several sessions and an emphasis (in introductory sessions) on graduate school in chemistry, the chemical industry, resumes, and interviews. Also briefly describes an internship

Belloli, Robert C.

1985-01-01

358

Tropospheric Halogen Chemistry  

Microsoft Academic Search

Halogens are very reactive chemicals that are known to play an important role in anthropogenic stratospheric ozone depletion chemistry, first recognized by Molina and Rowland (1974). However, they also affect the chemistry of the troposphere. They are of special interest because they are involved in many reaction cycles that can affect the oxidation power of the atmosphere indirectly by influencing

R. von Glasow; P. J. Crutzen

2003-01-01

359

Brushing Up on Chemistry.  

ERIC Educational Resources Information Center

Presents an activity designed for use during National Chemistry Week 2002 with the theme "Chemistry Keeps Us Clean". Allows students to discover more about a cleaning product they use everyday. Students make their own toothpaste and compare its properties with those of commercial toothpaste. (MM)

Trantow, Ashley

2002-01-01

360

Undergraduate Chemistry Laboratory  

ERIC Educational Resources Information Center

Forty chemistry faculty from American Chemical Society-approved departments were interviewed to determine their goals for undergraduate chemistry laboratory. Faculty were stratified by type of institution, departmental success with regard to National Science Foundation funding for laboratory reform, and level of laboratory course. Interview

Bretz, Stacey Lowery; Fay, Michael; Bruck, Laura B.; Towns, Marcy H.

2013-01-01

361

High Energy Halogen Chemistry.  

National Technical Information Service (NTIS)

Contents: Nitrosilicone Chemistry; Chemistry of 2-Fluoro-2-nitropropanediol; Experimental -- Bis(2-fluoro-2,2-dinitropropyl)silanediols; Reaction of bis(2-fluoro-2, 2-dinitropropyl) silanediol with chlorotrimethylsilane, Bis(3-3-fluoro-3,3-dinitropropyl)p...

K. Baum P. T. Berkowitz D. A. Lerdal

1978-01-01

362

Infrared Lasers in Chemistry.  

ERIC Educational Resources Information Center

Selected infrared laser chemistry topics are discussed including carbon dioxide lasers, infrared quanta and molecules, laser-induced chemistry, structural isomerization (laser purification, sensitized reactions, and dielectric breakdown), and fundamental principles of laser isotope separation, focusing on uranium isotope separation. (JN)

John, Phillip

1982-01-01

363

Coupled Phenomena in Chemistry.  

ERIC Educational Resources Information Center

Various phenomena in chemistry and biology can be understood through Gibbs energy utilization. Some common phenomena in chemistry are explained including neutralization, hydrolysis, oxidation and reaction, simultaneous dissociation equilibrium of two weak acids, and common ion effect on solubility. (Author/SA)

Matsubara, Akira; Nomura, Kazuo

1979-01-01

364

Minicourses in Chemistry  

ERIC Educational Resources Information Center

Describes nine minicourses in chemistry designed to acquaint the non-science major with practical applications of chemistry in everyday experiences. Each course consists of daily classes for two weeks for one credit and is offered on a credit/no credit basis. (MLH)

Lygre, D. G.; And Others

1975-01-01

365

Rolf Claessen's Chemistry Index  

NSDL National Science Digital Library

This award is given to sites, that somehow are related to chemistry. The criteria to rank the sites are information content and design (layout, navigation, graphical design). Sites must contain chemistry related topics as innovative and attractive as possible. This award is given away to the best 5% of the submissions to the website and other sites reviewed by site author.

366

Cooking with Chemistry.  

ERIC Educational Resources Information Center

Suggests chemistry of cooking and analysis of culinary recipes as subject matter for introducing chemistry to an audience, especially to individuals with neutral or negative attitudes toward science. Includes sample recipes and experiments and a table listing scientific topics with related cooking examples. (JN)

Grosser, Arthur E.

1984-01-01

367

Chemistry of Moth Repellents  

ERIC Educational Resources Information Center

An effective way to teach chemistry is to examine the substances used in daily life from a pedagogical viewpoint, from the overlap of science, technology, and society (STS). A study aims to engage students in the topic of moth repellents and to encourage them to investigate the chemistry in this familiar product using a set of questions.

Pinto, Gabriel

2005-01-01

368

Reactive Chemistry Blog  

NSDL National Science Digital Library

From science writer David Bradley, this blog has brought the "latest news from the world of chemistry to web surfers everywhere" since 1999. The site crosses a research orientation with a popular look and feel. Features examine current chemistry developments in areas such as chromatography and nanotechnology, as well as news pertaining to work being done by researchers.

2005-12-01

369

Laser applications in chemistry  

SciTech Connect

This book contains the proceedings from SPIE - The International Society for Optical Engineering conference on June 5-6, 1986. Topics are presented under the following session heads: Isotope Separation and Related Photochemistry, Laser Induced Chemistry I, Laser Spectroscopy, and Laser Induced Chemistry II. There are 33 papers in this volume.

Evans, D.K.

1986-01-01

370

A search for pre-biotic molecules in hot cores  

Microsoft Academic Search

Aims:Our aim is to better understand the complex chemistry of organic molecules in the interstellar medium, leading to the formation of pre-biotic molecules such as amino acids. Methods: We have performed a search for the pre-biotic molecules amino acetonitrile (H2N CH2 CN) and vinyl acetylene (C2H3 CCH) towards four northern hot core sources using the Onsala 20 m telescope. Results:

E. S. Wirstrm; P. Bergman; . Hjalmarson; A. Nummelin

2007-01-01

371

Atomic layer etching of germanium  

Microsoft Academic Search

Atomic layer etching of Ge has been investigated experimentally based on the surface chemistry that Cl can adsorb on the clean Ge surface at room temperature and desorb thermally as GeCl2 at high temperatures. The ideal etching rate of one monolayer per cycle has been achieved. The critical Cl2 dosage for the saturated etching rate was about 7.2106 L. Increase

Keiji Ikeda; Shigeru Imai; Masakiyo Matsumura

1997-01-01

372

Hot Jupiter Magnetospheres  

NASA Astrophysics Data System (ADS)

The upper atmospheres of close-in gas giant exoplanets ("hot Jupiters") are subjected to intense heating and tidal forces from their parent stars. The atomic (H) and ionized (H+) hydrogen layers are sufficiently rarefied that magnetic pressure may dominate gas pressure for expected planetary magnetic field strength. We examine the structure of the magnetosphere using a 3D isothermal magnetohydrodynamic model that includes a static "dead zone" near the magnetic equator containing gas confined by the magnetic field, a "wind zone" outside the magnetic equator in which thermal pressure gradients and the magneto-centrifugal-tidal effect give rise to a transonic outflow, and a region near the poles where sufficiently strong tidal forces may suppress transonic outflow. Using dipole field geometry, we estimate the size of the dead zone to be several to tens of planetary radii for a range of parameters. Tides decrease the size of the dead zone, while allowing the gas density to increase outward where the effective gravity is outward. In the wind zone, the rapid decrease of density beyond the sonic point leads to smaller densities relative to the neighboring dead zone, which is in hydrostatic equilibrium. To understand the appropriate base conditions for the 3D isothermal model, we compute a simple 1D thermal model in which photoelectric heating from the stellar Lyman continuum is balanced by collisionally excited Ly? cooling. This 1D model exhibits a H layer with temperature T ~= 5000-10,000 K down to a pressure P ~ 10-100 nbar. Using the 3D isothermal model, we compute maps of the H column density as well as the Ly? transmission spectra for parameters appropriate for HD 209458b. Line-integrated transit depths sime5%-10% can be achieved for the above base conditions, in agreement with the results of Koskinen et al. A deep, warm H layer results in a higher mass-loss rate relative to that for a more shallow layer, roughly in proportion to the base pressure. Strong magnetic fields have the effect of increasing the transit signal while decreasing the mass loss, due to higher covering fraction and density of the dead zone. Absorption due to bulk fluid velocity is negligible at linewidths gsim100 km s-1 from line center. In our model, most of the transit signal arises from magnetically confined gas, some of which may be outside the L1 equipotential. Hence, the presence of gas outside the L1 equipotential does not directly imply mass loss. We verify a posteriori that particle mean free paths and ion-neutral drift are small in the region of interest in the atmosphere, and that flux freezing is a good approximation. We suggest that resonant scattering of Ly? by the magnetosphere may be observable due to the Doppler shift from the planet's orbital motion, and may provide a complementary probe of the magnetosphere. Lastly, we discuss the domain of applicability for the magnetic wind model described in this paper as well as the Roche-lobe overflow model.

Trammell, George B.; Arras, Phil; Li, Zhi-Yun

2011-02-01

373

Organic Chemistry Resources Worldwide  

NSDL National Science Digital Library

Organic Chemistry Worldwide is an excellent organic chemistry metasite that is not to be missed. Geared toward synthetic organic chemists involved in academic or industrial research, Organic Chemistry Resources Worldwide has a mission to collect and independently annotate "all useful organic chemistry sites and to present them in an intuitive way." This extensive metasite is divided into sections on literature, laboratory resources, spectroscopy and spectrometry, nomenclature and teaching, and conferences and organizations. The Literature section contains links to over 75 journals (some restricted access), 14 free databases (and many more commercial), dissertation collections, reviews, guides, patents, and current awareness sources. Examples of resources for laboratory work include links to chemical product databases, laboratory safety bulletins (.pdf), products and services, etc. Highlights of the site are an in-depth section on mass spectrometry, with links to publications and databases, and a plethora of links to organic chemistry labs worldwide, from Armenia to Uruguay.

Van Aken, Koen

1996-01-01

374

Chemistry for Kids: Summer Chemistry for Fun.  

ERIC Educational Resources Information Center

A five-week course for fourth- and fifth-grade students (titled "Chemistry for Kids") was developed. Each class session consisted of a brief lecture, a demonstration, and one or more experiments. An outline of concepts fostered, instructional strategies, and procedures used is provided. (JN)

Hufford, Kevin D.

1984-01-01

375

Chemistry for Kids: Elementary School Chemistry Activities.  

ERIC Educational Resources Information Center

Describes a program in which six experiments in chemistry were used in an elementary school science program. Discusses the problems encountered in initiating the program, and some of the ways the problems were solved. Lists the six experiments, along with the reaction or process being studied, and the application of each. (TW)

Seager, Spencer L.; Swenson, Karen T.

1987-01-01

376

Nanografting for Surface Physical Chemistry  

NASA Astrophysics Data System (ADS)

This article reveals the enabling aspects of nanografting (an atomic force microscopy-based lithography technique) in surface physical chemistry. First, we characterize self-assembled monolayers and multilayers using nanografting to place unknown molecules into a matrix with known structure or vice versa. The availability of an internal standard in situ allows the unknown structures to be imaged and quantified. The same approaches are applied to reveal the orientation and packing of biomolecules (ligands, DNA, and proteins) upon immobilization on surfaces. Second, nanografting enables systematic investigations of size-dependent mechanics at the nanometer scale by producing a series of designed nanostructures and measuring their Young's modulus in situ. Third, one can investigate systematically the influence of ligand local structure on biorecognition and protein immobilization by precisely engineering ligand nanostructures. Finally, we also demonstrate the regulation of the surface reaction mechanism, kinetics, and products via nanografting.

Liu, Maozi; Amro, Nabil A.; Liu, Gang-Yu

2008-05-01

377

Atoms, Molecules, and Kinetic Theory, Science (Experimental): 5317.63.  

ERIC Educational Resources Information Center

This course of instruction in advanced chemistry is intended for the student ready for first-year college chemistry. Presented is an in-depth review with theory and mathematics being stressed in the study of concepts involving atomic structure, bonding, states of matter, molar relationships in equations, and properties of solutions. It is

Buffaloe, Jacquelin F.

378

Atomic Mobile  

NSDL National Science Digital Library

Learners make a mobile model of a carbon atom using clay, wire, and pipe cleaners. Learners will use the periodic table as a guide and explore how atoms are made up of a nucleus of protons and neutrons with orbiting electrons. The activity includes a PDF file of a periodic table and a guide for reading it.

History, American M.

2012-06-26

379

Atomic supersymmetry  

NASA Technical Reports Server (NTRS)

Atomic supersymmetry is a quantum-mechanical supersymmetry connecting the properties of different atoms and ions. A short description of some established results in the subject are provided and a few recent developments are discussed including the extension to parabolic coordinates and the calculation of Stark maps using supersymmetry-based models.

Kostelecky, V. Alan

1993-01-01

380

CO2 Chemistry in the Atmosphere of HD189733b  

NASA Astrophysics Data System (ADS)

Recent infrared spectroscopy of hot exoplanets has opened up the door to their atmospheric composition. Atmospheric composition is controlled by thermochemical equilibrium deep in the planetary atmosphere and photochemistry higher up in the atmosphere at levels above 2 bars. These two chemistries interact near 100 bars in Jupiter-like atmospheres. HD189733b provides an excellent laboratory to study the consequences of this hot atmospheric chemistry. The recent spectrum of HD189733b obtained by Swain et al., 2009 shows absorption features of CO2, CO and H2O. These observations suggest that the observable atmosphere of HD189733b is dominated primarily by CO2 chemistry. Here we explore thermochemical equilibrium chemistry using the NASA-Goddard Chemical Equilibrium with Applications (CEA) code and the CO2 photochemistry with JPL/Caltech KINETICS code and how these chemistries manifest themselves in the observed spectrum using a radiative transfer code. We will also explore techniques for retrieving temperatures and mixing ratios from observed spectra.

Line, Michael R.; Liang, M. C.; Yung, Y. L.; Tinetti, G.

2009-09-01

381

Atomic oxygen testing with thermal atom systems - A critical evaluation  

NASA Technical Reports Server (NTRS)

The use of thermal atom (kinetic energy near 0.04 eV) test methods as a materials selection and screening technique for LEO spacecraft is critically evaluated in this paper. The physics and chemistry of the thermal atom environments are shown to produce specific mass loss rates (mg/sq cm per min) and reaction efficiencies (Re) radically different from those produced in the LEO environment. A response surface study shows that specific mass loss rates change rapidly with plasma-asher parameters and seldom agree with flight data. FEP Teflon is shown to react by a different mechanism than Kapton, polyethylene, or graphite. The Re (Re = volume of material removed/oxygen atom) of Kapton, polyethylene, Mylar, Tedlar, FEP Teflon, and graphite measured in a flowing afterglow apparatus are 0.001 to 0.0001 those measured with high-energy atoms (kinetic energy 1.5 eV or greater) in beam systems or in LEO. The effect of sample temperature and atom impact energy on Re is discussed. A simple kinetic model describing the reaction of atomic oxygen with polymer surfaces is developed. Guidelines and recommendations for thermal atom testing and interpretation of test results are presented.

Koontz, Steven L.; Albyn, Keith; Leger, Lubert J.

1991-01-01

382

Chemistry PowerPoint Lessons and Instructional Materials  

NSDL National Science Digital Library

Before becoming an author, Jeremy Schneider was a chemistry teacher. Over the past several years he has placed a number of helpful instructional resources here on his site. These particular resources cover atomic structure, quantum mechanics, atomic size, bonding, and several dozen additional topics. Visitors can browse through these resources at their leisure and each topic area includes a brief description of what is covered in each set of materials. Specifically, the resources include labs, assignments, worksheets, and handouts. Many of the resources draw on examples from the "Fundamentals of Chemistry" textbook, but the site suggests that page references from other textbooks can be substituted.

383

IR Hot Wave  

Microsoft Academic Search

The IR Hot Wave{trademark} furnace is a breakthrough heat treatment system for manufacturing metal components. Near-infrared (IR) radiant energy combines with IR convective heating for heat treating. Heat treatment is an essential process in the manufacture of most components. The controlled heating and cooling of a metal or metal alloy alters its physical, mechanical, and sometimes chemical properties without changing

2010-01-01

384

Hot Melt Recharge System.  

National Technical Information Service (NTIS)

A package assembly is described for precisely positioning a charge of hot melt adhesive onto an attachment pad or a point of use. The adhesive is heated to softening or melt temperature (280 F - 325 F) and thereafter cooled to resolidifying temperature. A...

D. J. Progar

1983-01-01

385

Hot Melt Recharge System.  

National Technical Information Service (NTIS)

A package assembly for precisely positioning a charge of hot melt adhesive onto an attachment pad or point of use is described. The adhesive is heated to softening or melt temperature (280 F to 325 F) and thereafter cooled to resolidifying temperature. A ...

D. J. Progar

1982-01-01

386

TRUEX hot demonstration  

Microsoft Academic Search

In FY 1987, a program was initiated to demonstrate technology for recovering transuranic (TRU) elements from defense wastes. This hot demonstration was to be carried out with solution from the dissolution of irradiated fuels. This recovery would be accomplished with both PUREX and TRUEX solvent extraction processes. Work planned for this program included preparation of a shielded-cell facility for the

D. B. Chamberlain; R. A. Leonard; J. C. Hoh; E. C. Gay; D. G. Kalina; G. F. Vandegrift

1990-01-01

387

The Deep Hot Biosphere  

Microsoft Academic Search

The first inhabitants of planet Earth were single-celled microorganisms and they are still with us today. Their name is truly legion, for they live everywhere, from boiling hot springs at the Earth's surface and on the seafloor to the coldest waters of the oceans and the Antarctic lakes. They are the masters of evolutionary adaptation, who have colonized the entire

Harmon Craig

1999-01-01

388

Hot off the Press  

ERIC Educational Resources Information Center

In the past, the newspaper was one of the world's most used sources of information. Recently, however, its use has declined due to the popularity of cable television and the Internet. Yet the idea of reading the morning paper with a hot cup of coffee holds many warm memories for children who watched their parents in this daily ritual. In this

Brisco, Nicole D.

2007-01-01

389

Hot gas generator  

Microsoft Academic Search

This patent describes a hot gas generator. It comprises: a vessel having a wall defining narrow, spaced apart inlet and outlet ends interconnected by a relatively wide, generally spherical combustion chamber; a pair of smooth hemispherical liners loosely positioned within the wall so as to be disposed about the combustion chamber. The hemispherical liners normally having a groove at an

J. R. Shekleton; R. W. Smith

1990-01-01

390

Some Like it Hot  

NSDL National Science Digital Library

NASA Astrobiologist Jack Farmer is featured in this web article that focuses on microrganisms found in Yellowstone hot springs and ocean floor hydrothermal vents. Included within the article are numerous links to concepts, resources, and further readings involving exobiology. and microbiology. Downloadable Quick time videos of a discussion with Farmer and hydrothermal vent activity at the ocean floor are also available.

Bortman, Henry; Magazine, Astrobiology

391

Hot-hole photodetectors  

NASA Astrophysics Data System (ADS)

By injecting high-energy charge carriers (dubbed 'hot holes') into a semiconductor, scientists have succeeded in realizing photodetectors capable of detecting ultralong wavelengths. Unil Perera from Georgia State University in the USA explains how the devices work and how they can be improved.

2014-05-01

392

OECD Focus Hot File  

NSDL National Science Digital Library

In each issue of the Organization for Economic Co-operation and Development (OECD)'s Focus Hot File, recent books and government reports of interest are listed with summaries and contact information. Past listings may be browsed by country in the Focus Compendium, and related publications are hyperlinked throughout.

393

Kamchatka's thermal hot springs  

NSDL National Science Digital Library

The Kamchatka Peninsula is featured in this website including information on geography, climate, fauna, flora, volcanoes, thermal springs, Valley of Geysers, native people, and options for travel in Kamchatka. This specific page highlights a selection of Kamchatka's hot springs, presenting basic information on temperature ranges, chemical and physical characteristics, surrounding vegetation, and general location.

Kamchatka, Vision O.

394

Editor's Note: Hot Properties  

NSDL National Science Digital Library

Properties are "hot," not in terms of real estate but in science class. Here, the editor highlights the feature articles related to this month's theme, Properties of Objects and Materials. With these articles as a guide, you can move students toward a deeper understanding of property. As you do so, they will build a strong foundation for future science learning.

Ohana, Chris

2008-01-01

395

Broadband laser cooling of trapped atoms with ultrafast pulses  

SciTech Connect

We demonstrate broadband laser cooling of atomic ions in an rf trap using ultrafast pulses from a mode-locked laser. The temperature of a single ion is measured by observing the size of a time-averaged image of the ion in the known harmonic trap potential. Although the lowest observed temperature was only about 1 K, this method efficiently cools very hot atoms and can sufficiently localize trapped atoms to produce near diffraction-limited atomic images.

Blinov, B.B.; Kohn, R.N. Jr.; Madsen, M.J.; Maunz, P.; Moehring, D.L.; Monroe, C. [FOCUS Center and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

2006-06-15

396

Nanostructuring of alumina optical waveguides by hot water treatment for tuning sensor output  

Microsoft Academic Search

A study of the nanostructuring of alumina integrated optical waveguides by means of hot water treatment to tune their outputs, namely, total internal reflection and scattering, is presented. Homogeneous alumina thin films fabricated by atomic layer deposition were exposed to hot water to form surface nano-pillars of various heights and densities. The 135-, 232- and 307-nm thick alumina films were

Mustafa M. Aslan

397

Intermittency in second-harmonic radiation from plasmonic hot spots on rough silver films  

Microsoft Academic Search

Surface enhancement of electromagnetic fields in plasmonic hot spots formed on rough silver films enables the observation of second-harmonic generation (SHG) from single metal nanoparticles. Nonlinear light scattering from these particles exhibits blinking in analogy to luminescence from single quantum dots, molecules and atoms; and fluctuations in single molecule surface-enhanced Raman scattering. Hot spots also display multiphoton white light emission

Nicholas J. Borys; Manfred J. Walter; John M. Lupton

2009-01-01

398

Moderator Chemistry Program  

SciTech Connect

Over the past fifteen months, the Systems Chemistry Group of the Reactor Engineering Department has undertaken a comprehensive study of the Department's moderator chemistry program at Savannah River Site (SRS). An internal review was developed to formalize and document this program. Objectives were as outlined in a mission statement and action plan. In addition to the mission statement and action plan, nine separate task reports have been issued during the course of this study. Each of these task reports is included in this document as a chapter. This document is an organized compilation of the individual reports issued by the Systems Chemistry Group in assessment of SRS moderator chemistry to determine if there were significant gaps in the program as ft existed in October, 1989. While these reviews found no significant gaps in that mode of operation, or any items that adversely affected safety, items were identified that could be improved. Many of the items have already been dear with or are in the process of completion under this Moderator Chemistry Program and other Reactor Restart programs. A complete list of the items of improvement found under this assessment is found in Chapter 9, along with a proposed time table for correcting remaining items that can be improved for the chemistry program of SRS reactors. An additional external review of the moderator chemistry processes, recommendations, and responses to/from the Reactor Corrosion Mitigation Committee is included as Appendix to this compilation.

Dewitt, L.V.; Gibbs, A.; Lambert, D.P.; Bohrer, S.R.; Fanning, R.L.; Houston, M.W.; Stinson, S.L.; Deible, R.W.; Abdel-Khalik, S.I.

1990-11-01

399

Moderator Chemistry Program  

SciTech Connect

Over the past fifteen months, the Systems Chemistry Group of the Reactor Engineering Department has undertaken a comprehensive study of the Department`s moderator chemistry program at Savannah River Site (SRS). An internal review was developed to formalize and document this program. Objectives were as outlined in a mission statement and action plan. In addition to the mission statement and action plan, nine separate task reports have been issued during the course of this study. Each of these task reports is included in this document as a chapter. This document is an organized compilation of the individual reports issued by the Systems Chemistry Group in assessment of SRS moderator chemistry to determine if there were significant gaps in the program as ft existed in October, 1989. While these reviews found no significant gaps in that mode of operation, or any items that adversely affected safety, items were identified that could be improved. Many of the items have already been dear with or are in the process of completion under this Moderator Chemistry Program and other Reactor Restart programs. A complete list of the items of improvement found under this assessment is found in Chapter 9, along with a proposed time table for correcting remaining items that can be improved for the chemistry program of SRS reactors. An additional external review of the moderator chemistry processes, recommendations, and responses to/from the Reactor Corrosion Mitigation Committee is included as Appendix to this compilation.

Dewitt, L.V.; Gibbs, A.; Lambert, D.P.; Bohrer, S.R.; Fanning, R.L.; Houston, M.W.; Stinson, S.L.; Deible, R.W.; Abdel-Khalik, S.I.

1990-11-01

400

Path Integral Monte Carlo Simulation of Hot, Dense Hydrogen  

Microsoft Academic Search

Path integral Monte Carlo simulations have been applied to study the hot, dense hydrogen at Mega-bar pressures corresponding to the density and temperature range of 1 < rs < 14 and 5000 K < T < 1000000 K. We determine the equation of state and study the phase diagram including the molecular, atomic and plasma regime. We discuss the effects

Burkhard Militzer

2001-01-01

401

The hot-spring genesis of the Shimen realgar deposit, northwest Hunan  

Microsoft Academic Search

The Shimen realgar deposit is characterized by the pipe-shaped orebody and the development of silica sinter and hydrothermal\\u000a explosive breccia which are typical of hot spring activity. Very similar trace-element associations are noticed between the\\u000a silica cap and the breccia and modern hot spring waters in the area. The chemistry of ore-forming solutions is also well comparable\\u000a with that of

Zhang Jingrong; Wang Wei; Yang Fan; Cai Tong

1993-01-01

402

Frontiers in analytical chemistry  

SciTech Connect

Doing more with less was the modus operandi of R. Buckminster Fuller, the late science genius, and inventor of such things as the geodesic dome. In late September, chemists described their own version of this maxim--learning more chemistry from less material and in less time--in a symposium titled Frontiers in Analytical Chemistry at the 196th National Meeting of the American Chemical Society in Los Angeles. Symposium organizer Allen J. Bard of the University of Texas at Austin assembled six speakers, himself among them, to survey pretty widely different areas of analytical chemistry.

Amato, I.

1988-12-15

403

Microscale Gas Chemistry  

NSDL National Science Digital Library

Created by Professor Bruce M. Mattson, PhD, of Creighton University's Department of Chemistry, the Microscale Gas Chemistry Website "provides instructions for the generation of gases on a microscale level along with instructions for chemical demonstrations and student laboratory experiments with the gases." The no-frills site, designed for high school and university chemistry teachers, contains clear and careful instructions for experiments with carbon dioxide, hydrogen, oxygen and nitrogen, nitrogen oxides, ammonia, ethene, chlorine, carbon monoxide, and more. An introduction offers two low-tech methods for gas generation. Data pages for relevant gases are linked to each experiment.

404

Harvard University: Environmental Chemistry  

NSDL National Science Digital Library

The Environmental Chemistry group at Harvard University created this website to promote its research in the understanding and quantification of chemistry of surfaces in environmental chemical systems. Users can learn about the group's many projects that deal with the shared topic: "What controls the formation and reactivity of a surface?" Researchers can find out about the group's seminars held at Harvard and can download many of the related publications. The website publicizes the efforts and backgrounds of the eleven people involved with environmental chemistry. Students and educators can view short, fascinating movies dealing with its results.

405

The Chemistry of Cocaine  

NSDL National Science Digital Library

This case study looks at cocaine, including its addictive properties and the chemistry involved in the synthesis of the drug in its different forms. The lesson can be used to teach nucleophilic addition reactions, nucleophilic acyl substitution, and cocaine metabolism. The material was designed for use in an undergraduate organic chemistry course but could also be used in medicinal chemistry coursework. The case study and teaching notes may be downloaded in PDF format. The site also includes a section for instructor feedback where general comments may be read and contributed.

Dewprashad, Brahmadeo

2011-01-06

406

Materials Chemistry at SFU  

NSDL National Science Digital Library

The Materials Science group at Simon Fraser University (SFU) developed this website to address the group's primary research interests in material synthesis, molecular, electronics, and photonics. Visitors will find explanations covering sixteen research topics including chemical sensors, lithography, non-linear optics, and supramolecular chemistry. Under each topic heading, users will find links discussing the faculties' current goals, recent publications, and patents. The site also features links to the Pacific Centre for Advanced Materials and Microstructures; a collaborative effort between the Materials Science group at SFU and the physics and chemistry departments at the University of British Columbia. Anyone searching for the latest investigations in materials chemistry will find this website very informative.

407

Wizardry and Chemistry  

NSDL National Science Digital Library

Students learn how common pop culture references (Harry Potter books) can relate to chemistry. While making and demonstrating their own low-intensity sparklers (muggle-versions of magic wands), students learn and come to appreciate the chemistry involved (reaction rates, Gibb's free energy, process chemistry and metallurgy). The fun part is that all wands are personalized and depend on how well students conduct the lab. Students end the activity with a class duela face-off between wands of two different chemical compositions. This lab serves as a fun, engaging review for stoichiometry, thermodynamics, redox and kinetics, as well as advanced placement course review.

University Of Houston

408

Linux4Chemistry  

NSDL National Science Digital Library

Part of the WWW Virtual Library, the Linux4Chemistry page is a metasite listing a variety of chemistry-related software available on the Web for Linux interface. The site is maintained by Nikodem Kuznik, an undergraduate at the Silesian Technical University in Gliwice, Poland. The list indicates whether the software is free, shareware, or commercial and gives brief descriptions of applications. A few of the programs listed are AllChem, AMMP molecular modeling program, CDA charge composition analysis, and Kmol molecular weight calculator. Besides the seemingly exhaustive list of Linux software for chemistry, this site also gives links to other software resources.

Kuznik, Nikodem.

2005-11-02

409

Combinatorial Chemistry Review  

NSDL National Science Digital Library

The Combinatorial Chemistry Review website was created by Dr. Oleg Larin at the M. V. Lomonosov Moscow State Academy of Fine Chemical Technology "to provide a basic introduction to the field of combinatorial chemistry describing the development of major techniques and some applications." After reading an introduction discussing the goals, principles, and applications of combinatorial synthesis, users can find more in-depth descriptions and educational figures of the polymers and linkers related to the solid phase combinatorial chemistry. The comprehensive website supplies a discussion of the methods, a helpful glossary of terms, and more.

Larin, Oleg.

410

Turkish Prospective Chemistry Teachers' Beliefs about Chemistry Teaching  

Microsoft Academic Search

In order to study the beliefs of Turkish prospective chemistry teachers about teaching chemistry, semi-structured interviews were conducted with 12 prospective teachers. Analysis of the interviews revealed that most of the prospective teachers held intermediate (transition between constructivist and traditional) beliefs about chemistry teaching. Most of the student teachers exhibited inconsistencies in their beliefs about teaching chemistry. The findings indicate

Yezdan Boz; Esen Uzuntiryaki

2006-01-01

411

A Chemistry Minute: Recognizing Chemistry in Our Daily Lives  

ERIC Educational Resources Information Center

Students in introductory chemistry classes often wonder about the relevance of chemistry to their daily lives. We have sought to increase their awareness by requiring each student in first- and second-semester general chemistry to make a two-minute presentation on a chemistry-related topic. This exercise gives students an opportunity to think

Luning Prak, Dianne J.; Copper, Christine L.

2008-01-01

412

Refurbishment of an Analytical Laboratory Hot Cell Facility  

SciTech Connect

An Analytical Laboratory Hot Cell (ALHC) Facility at Argonne National Laboratory-West (ANL-W) was in service for nearly thirty years. In order to comply with DOE regulations governing such facilities and meet ANL-W programmatic requirements, a major refurbishment effort was undertaken. To place the facility in compliance with current regulations, all penetrations within the facility were sealed, the ventilation system was redesigned, upgraded and replaced, the master-slave manipulators were replaced, the hot cell windows were removed, refurbished, and reinstalled, all hot cell utilities were replaced, a lead-shielded glovebox housing an Inductive Coupled Plasma - Atomic Emission Spectrometer (ICP-AES) System was interfaced with the hot cells, and a new CO{sub 2} fire suppression system and other ALHC support equipment were installed.

Rosenberg, K.E.; Henslee, S.P.; Michelbacher, J.A.; Coleman, R.M.

1996-08-01

413

Sulfur donor atom effects on copper(I)/O(2) chemistry with thioanisole containing tetradentate N(3)S ligand leading to ?-1,2-peroxo-dicopper(II) species.  

PubMed

To better understand the effect of thioether coordination in copper-O(2) chemistry, the tetradentate N(3)S ligand L(ASM) (2-(methylthio)-N,N-bis((pyridin-2-yl)methyl)benzenamine) and related alkylether ligand L(EOE) (2-ethoxy-N,N-bis((pyridin-2-yl)methyl)ethanamine) have been studied. The corresponding copper(I) complexes, [(L(ASM))Cu(I)](+) (1a) and [(L(EOE))Cu(I)](+) (3a), were studied as were the related compound [(L(ESE))Cu(I)](+) (2a, L(ESE) = (2-ethylthio-N,N-bis((pyridin-2-yl)methyl)ethanamine). The X-ray structure of 1a and its solution conductivity reveal a monomeric molecular structure possessing thioether coordination which persists in solution. In contrast, the C-O stretching frequencies of the derivative Cu(I)-CO complexes reveal that for these complexes, the modulated ligand arms, whether arylthioether, alkylthioether, or ether, are not coordinated to the cuprous ion. Electrochemical data for 1a and 2a in CH(3)CN and N,N-dimethylformamide (DMF) show the thioanisole moiety to be a poor electron donor compared to alkylthioether (1a is ?200 mV more positive than 2a). The structures of [(L(ASM))Cu(II)(CH(3)OH)](2+) (1c) and [(L(ESE))Cu(II)(CH(3)OH)](2+) (2c) have also been obtained and indicate nearly identical copper coordination environments. Oxygenation of 1a at reduced temperature gives a characteristic deep blue intermediate [{(L(ASM))Cu(II)}(2)(O(2)(2-))](2+) (1b(P)) with absorption features at 442 (1,500 M(-1) cm(-1)), 530 (8,600 M(-1) cm(-1)), and 605 nm (10,400 M(-1) cm(-1)); these values compare well to the ligand-to-metal charge-transfer (LMCT) transitions previously reported for [{(L(ESE))Cu(II)}(2)(O(2)(2-))](2+) (2b(P)). Resonance Raman data for [{(L(ASM))Cu(II)}(2)(O(2)(2-))](2+) (1b(P)) support the formation of ?-1,2-peroxo species ?(O-O) = 828 cm(-1)(?((18)O(2)) = 48), ?(sym)(Cu-O) = 547 cm(-1) (?((18)O(2)) = 23), and ?(asym)(Cu-O) = 497 cm(-1) (?((18)O(2)) = 22) and suggest the L(ASM) ligand is a poorer electron donor to copper than is L(ESE). In contrast, the oxygenation of [(L(EOE))Cu(I)](+) (3a), possessing an ether donor as an analogue of the thioether in L(ESE), led to the formation of a bis(?-oxo) species [{(L(EOE))Cu(III)}(2)(O(2-))(2)](2+) (3b(O); 380 nm, ? ? 10,000 M(-1) cm(-1)). This result provides further support for the sulfur influence in 1b(P) and 2b(P), in particular coordination of the sulfur to the Cu. Thermal decomposition of 1b(P) is accompanied by ligand sulfoxidation. The structure of [{(L(EOE))Cu(II)(Cl)}(2)](+) (3c) generated from the reductive dehalogenation of organic chlorides suggests that the ether moiety is weakly bound to the cupric ion. A detailed discussion of the spectroscopic and structural characteristics of 1b(P), 2b(P), and 3b(O) is presented. PMID:20822156

Lee, Yunho; Lee, Dong-Heon; Park, Ga Young; Lucas, Heather R; Narducci Sarjeant, Amy A; Kieber-Emmons, Matthew T; Vance, Michael A; Milligan, Ashley E; Solomon, Edward I; Karlin, Kenneth D

2010-10-01

414

Distributed Pore Chemistry in Porous Organic Polymers  

NASA Technical Reports Server (NTRS)

A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The sub-strate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic region, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

Koontz, Steven L. (Inventor)

1998-01-01

415

The importance of dye chemistry and TiCl4 surface treatment in the behavior of Al2O3 recombination barrier layers deposited by atomic layer deposition in solid-state dye-sensitized solar cells.  

PubMed

Atomic layer deposition (ALD) was used to fabricate Al(2)O(3) recombination barriers in solid-state dye-sensitized solar cells (ss-DSSCs) employing an organic hole transport material (HTM) for the first time. Al(2)O(3) recombination barriers of varying thickness were incorporated into efficient ss-DSSCs utilizing the Z907 dye adsorbed onto a 2 ?m-thick nanoporous TiO(2) active layer and the HTM spiro-OMeTAD. The impact of Al(2)O(3) barriers was also studied in devices employing different dyes, with increased active layer thicknesses, and with substrates that did not undergo the TiCl(4) surface treatment. In all instances, electron lifetimes (as determined by transient photovoltage measurements) increased and dark current was suppressed after Al(2)O(3) deposition. However, only when the TiCl(4) treatment was eliminated did device efficiency increase; in all other instances efficiency decreased due to a drop in short-circuit current. These results are attributed in the former case to the similar effects of Al(2)O(3) ALD and the TiCl(4) surface treatment whereas the insulating properties of Al(2)O(3) hinder charge injection and lead to current loss in TiCl(4)-treated devices. The impact of Al(2)O(3) barrier layers was unaffected by doubling the active layer thickness or using an alternative ruthenium dye, but a metal-free donor-?-acceptor dye exhibited a much smaller decrease in current due to its higher excited state energy. We develop a model employing prior research on Al(2)O(3) growth and dye kinetics that successfully predicts the reduction in device current as a function of ALD cycles and is extendable to different dye-barrier systems. PMID:22850593

Brennan, Thomas P; Bakke, Jonathan R; Ding, I-Kang; Hardin, Brian E; Nguyen, William H; Mondal, Rajib; Bailie, Colin D; Margulis, George Y; Hoke, Eric T; Sellinger, Alan; McGehee, Michael D; Bent, Stacey F

2012-09-21

416

General Chemistry Multimedia Problems  

NSDL National Science Digital Library

General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

417

Combustion Hydrodynamics and Chemistry.  

National Technical Information Service (NTIS)

Accomplishments in combustion hydrodynamics and chemistry studies consisted of a computational study of the chemical kinetics of hydrogen combustion along with some subsidiary studies and programming. Comparisons with experimental results have been genera...

E. Hyman

1981-01-01

418

Chemistry with a Peel.  

ERIC Educational Resources Information Center

Presents experiments that introduce natural product chemistry into high school classrooms. In the laboratory activities, students isolate and analyze the oil in orange peels. Students also perform a steam distillation and learn about terpenes. (DDR)

Borer, Londa; Larsen, Eric

1997-01-01

419

Magnetism in Chemistry  

ERIC Educational Resources Information Center

Discusses the technical aspects of paramagnetism and an electrostatic model called Crystal Field Theory (CFT), very often used in the case of transition metal compounds. Suggests that this discussion be included as an option for college chemistry courses. (MLH)

Brookes, R. W.; McFadyen, W. D.

1975-01-01

420

Forensic Chemistry Lab Manual  

NSDL National Science Digital Library

Any aspect of forensic science can be quite tricky, and educators will be delighted to learn about this helpful educational resource designed just for them. Created by Professor Robert Thompson of Oberlin College this online forensic chemistry lab manual is designed to help chemistry faculty in developing forensic chemistry project laboratories for both undergraduate and graduate courses. In this manual, visitors will find sample preparations, procedural details, instructions for students, and typical results in a variety of formats. Along the left-hand side of the homepage, visitors can look through the forensic chemistry analyses, which include explosives, fabric, glass, and arson. The site is rounded out by a selection of "Stories", which are meant to provide the background for chemical analyses of crime scene samples.

Thompson, Robert

421

Chemistry for Kids.  

ERIC Educational Resources Information Center

Reports two methods for interesting children in chemistry. Describes a method for producing large soap bubbles and films for study. Examines the use of simple stories to explain common chemical concepts with example given. Lists titles of available stories. (ML)

Sato, Sanae; Majoros, Bela

1988-01-01

422

Water Chemistry: Seeking Information  

ERIC Educational Resources Information Center

A survey of the available literature in water chemistry is presented. Materials surveyed include: texts, reference books, bibliographic resources, journals, American Chemical Society publications, proceedings, unpublished articles, and reports. (BT)

Delfino, Joseph J.

1977-01-01

423

Uncertainty in chemistry  

NASA Astrophysics Data System (ADS)

It might come as a disappointment to some chemists, but just as there are uncertainties in physics and mathematics, there are some chemistry questions we may never know the answer to either, suggests Fredric M. Menger.

Menger, Fredric M.

2010-09-01

424

Computer Aided CHEmistry (CAChe)  

NSDL National Science Digital Library

CAChe software is used for computational chemistry. It is simple to use and is therefore suitable for educational endeavors. Different versions include molecular mechanics, semiempirical, and density functional theory (DFT) methods of calculation.

425

General Chemistry for Engineers.  

ERIC Educational Resources Information Center

Discusses the relationship between molecular structure, intermolecular forces, and tensile strengths of a polymer and suggests that this is a logical way to introduce polymers into a general chemistry course. (Author/JN)

Kybett, B. D.

1982-01-01

426

Physical Chemistry Animation Index  

NSDL National Science Digital Library

This collection of animations, intended for a physical chemistry course, covers thermodynamics, the physical transformation of substances (such as dissolution), phase diagrams and the behaviour of matter in various states.

427

Chemistry Wrap Up  

NSDL National Science Digital Library

Class activities and independent projects for high school students using household plastic wraps can help students understand more about the chemistry of everyday objects. The activities described in this article reinforce one of the fundamental principle

Pristera, Jeffrey M.; Lloyd, Jeremy M.; Wheeler, Steven E.

2000-04-01

428

Atmospheric Chemistry (Program Description)  

NSF Publications Database

... model the concentration and distribution of gases and aerosols in the lower and middle atmosphere ... trace gases and aerosols; the aqueous-phase atmospheric chemistry; the transport of gases and ...

429

The Chemistry Hypermedia Project  

NSDL National Science Digital Library

The Chemistry Hypermedia Project was started by Professor Brian Tissue of Virginia Polytechnic Institute and State University in 1993. One of the goals stated for the site is to use the Internet to provide supplemental educational resources to chemistry students. That's accomplished by providing a large collection of hypermedia indices, which are online tutorials on various chemistry topics such as analytical chemistry, analytical instrumentation, and many others. Additional activities for students include self-paced tutorials that give students practice with equilibrium problems and a section on analytical spectroscopy. Although the student sections are a bit unorganized, the site does gives a lot of good information that kids can use to help understand these often confusing topics.

1996-01-01

430

Chemistry Societies Network  

NSDL National Science Digital Library

Users gain access to the heart of CSN's site through the site gateway which leads them to CSN's information arcade, education arcade, societies, chembytes, and conferences and events. The information arcade provides links to experts and specialists, and chemistry societies. The education arcade contains a wealth of information for educators in the chemistry arena. Societies lists chemical and chemistry-related societies, divided alphabetically by country. Chembytes provides access to a variety of news, including recent findings and discoveries, business updates, and news from around the globe. Chembytes also features a continuing series which looks in-depth at a topic recently in the news. Currently featured is NASA's attempt to return to the moon. Conferences and Events is searchable and browseable and contains a submission form so visitors can list an event. CSN's site also includes Useful Links, a listing of sites categorized and reviewed by Chemsoc and Science Park, which links to four companies offering chemistry related resources on the web.

2007-05-22

431

Elementary Organic Chemistry?  

Microsoft Academic Search

MAY I be permitted to direct attention to a question asked in a recent examination in organic chemistry for medical students, the syllabus for which states that ``the whole subject is to be treated in an elementary manner''?

J. F. Thorpe

1908-01-01

432

Opioid Peptides: Medicinal Chemistry,  

National Technical Information Service (NTIS)

The monograph presents contributions in the various aspects of the medicinal chemistry of the opioid peptides and the opiates. A number of presentations are on structure-activity relationships (SAR) of the opioid peptides; the SAR of enkephalins; morphice...

R. S. Rapaka G. Barnett R. L. Hawks

1986-01-01

433

Atomic hydrogen cleaning of EUV multilayer optics  

Microsoft Academic Search

Recent studies have been conducted to investigate the use of atomic hydrogen as an in-situ contamination removal method for EUV optics. In these experiments, a commercial source was used to produce atomic hydrogen by thermal dissociation of molecular hydrogen using a hot filament. Samples for these experiments consisted of silicon wafers coated with sputtered carbon, Mo\\/Si optics with EUV-induced carbon,

Samuel Graham Jr.; Charles A. Steinhaus; W. Miles Clift; Leonard E. Klebanoff; Sasa Bajt

2003-01-01

434

Exercising Safely in Hot Weather  

MedlinePLUS

... grouchy, acting strangely, staggering, or being unresponsive l Dry, flushed skin and a strong rapid pulse or a slow weak pulse l Not sweating even if it is hot Quick Tip For more hot weather tips, see the AgePage Hyperthermia: Too Hot for ...

435

Emergences of supramolecular chemistry: from supramolecular chemistry to supramolecular science  

Microsoft Academic Search

We describe the field of supramolecular chemistry as a consequence of the progress of chemistry from its premises to recent\\u000a achievements. Supramolecular chemistry has been claimed to be an emergent field of research taking its roots in chemistry.\\u000a According to the definitions of emergences related to hierarchy or more recently to scope, supramolecular chemistry is shown\\u000a to have bottom-up or

Jacques VicensQuentin Vicens; Quentin Vicens

436

Adventures in Organosulfur Chemistry  

Microsoft Academic Search

Irwin Douglass was born in 1904 in Des Moines, Iowa and was educated in the public schools of Nebraska, Illinois and Iowa. He received a B.S. degree from Monmouth College, Illinois in 1926 and a Ph.D. in chemistry from the University of Kansas in 1932. In his forty-six year career as a teacher of chemistry he has taught at Monmouth,

Irwin B. Douglass; Miriam L. Douglass

1995-01-01

437

Immersive chemistry video game  

Microsoft Academic Search

A team at Purdue University has been working on a NSF sponsored project to create a set of research-validated recommendations for the development of science video games. As a way to accomplish this task, the team created a three-dimensional first-person shooter video game that requires players to utilize chemistry knowledge to advance in the game-world. A team of chemistry, computer

Carlos Morales; Kermin Martnez-Hernndez; Gabriela Weaver; Ryan Pedela; Kellen Maicher; Eugene Elkin; Doug Danforth; Naveen Nattam

2006-01-01

438

Green Chemistry and Education  

NASA Astrophysics Data System (ADS)

Many students today are profoundly interested in the sustainability of their world. With growing public concern over global warming and greenhouse gases, students want to understand how human actions affect the health of our planet. Students are deeply concerned about pollution. They practice recycling. Moreover, they want to secure a healthy Earth for future generations. As students of chemistry, they have a unique opportunity to start at the ground floor of the exciting and expanding field of green chemistry.

Hjeresen, Dennis L.; Schutt, David L.; Boese, Janet M.

2000-12-01

439

Impact of surface chemistry  

PubMed Central

The applications of molecular surface chemistry in heterogeneous catalyst technology, semiconductor-based technology, medical technology, anticorrosion and lubricant technology, and nanotechnology are highlighted in this perspective. The evolution of surface chemistry at the molecular level is reviewed, and the key roles of surface instrumentation developments for in situ studies of the gassolid, liquidsolid, and solidsolid interfaces under reaction conditions are emphasized.

Somorjai, Gabor A.; Li, Yimin

2011-01-01

440

Organic Chemistry Forum  

NSDL National Science Digital Library

ChemWeb's Organic Chemistry Forum bills itself as a "free online club for the organic chemistry community." Users will need to complete a simple online form to obtain membership and access the site. One highlight of this site is free full-text access to Tetrahedron Letters. This rapid publication journal appears weekly. Along with free access to Beilstein Abstracts, the site includes jobs, a conference diary, news, discussion groups, and more.

2005-12-01

441

Organic Chemistry Forum  

NSDL National Science Digital Library

ChemWeb's Organic Chemistry Forum bills itself as a "free online club for the organic chemistry community." Users will need to complete a simple online form to obtain membership and access the site. One highlight of this site is free full-text access to Tetrahedron Letters. This rapid publication journal appears weekly. Along with free access to Beilstein Abstracts, the site includes jobs, a conference diary, news, discussion groups, and more.

2005-01-01

442

UCLA: Organic Chemistry Tutorials  

NSDL National Science Digital Library

Steven Hardinger at the Department of Chemistry and Biochemistry at UCLA created these tutorials to assist students with the difficult concepts presented in introductory organic chemistry. Students can find tutorials dealing with acids and bases, carbocations, Lewis dot structures, and more. Within each tutorial, users can find links to a dictionary that adequately explain the unfamiliar terminology. The tutorials include example problems and exercises to challenge users.

Hardinger, Steven

443

Covalent fullerene chemistry  

Microsoft Academic Search

A brief introduction to the reactivity principles governing the covalent chemistry of fullerenes is provided. The combination of synthetic fullerene and acetylene chemistry gives access to a family of novel molecular carbon allotropes with interesting physical properties. A versatile strategy for the regioselective preparation of specific bis- through hexakis-adducts of C6o based on the tether-directed remote functionalization was developed. Large

FranGois Diederich

1997-01-01

444

Acid-base chemistry  

SciTech Connect

The book is not a research compendium and there are no references to the literature. It is a teaching text covering the entire range of undergraduate subject matter dealing with acid-base chemistry (some of it remotely) as taught in inorganic, analytical, and organic chemistry courses. The excellent chapters VII through IX deal in detail with the quantitative aspects of aqueous acid-base equilibria (salt hydrolysis and buffer, titrations, polyprotic and amphoteric substances).

Hand, C.W.; Blewit, H.L.

1985-01-01

445

Chemistry in space research.  

NASA Technical Reports Server (NTRS)

Chemistry in space is discussed together with aspects of chemistry in planetary atmospheres, the prebiological synthesis of organic compounds, and carbonaceous meteorites as possible sites of extraterrestrial life. Other subjects investigated include terrestrial and extraterrestrial stable organic molecules, thermally stable macromolecules, chemical aspects of ablation, low-temperature relaxations in amorphous polymers, and solid propellants. Liquid propellant rockets are also considered along with questions of spacecraft sterilization. Individual items are announced in this issue.

Landel, R. F. (editor); Rembaum, A.

1972-01-01

446

Nicotine Smoke Chemistry  

NSDL National Science Digital Library

The featured molecules this month come from the paper Using "Basic Principles" To Understand Complex Science: Nicotine Smoke Chemistry and Literature Analogies by Jeffrey Seeman detailing some of the complexities involved in the volatilization of two alkaloids, nicotine and cocaine. Students could be asked to identify how chemistry is involved in the various steps described in the paper, and most beginning students will be surprised to learn just how complex a process the volatilization of a molecule such as nicotine is.

447

Acting Atoms.  

ERIC Educational Resources Information Center

Describes a fun game in which students act as electrons, protons, and neutrons. This activity is designed to help students develop a concrete understanding of the abstract concept of atomic structure. (DKM)

Farin, Susan Archie

1997-01-01

448

Kinetic Atom.  

ERIC Educational Resources Information Center

Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)

Wilson, David B.

1981-01-01

449

CHEMISTRY, A GUIDE FOR TEACHERS.  

ERIC Educational Resources Information Center

THE VOLUME INCLUDES AN INTRODUCTION, THE COURSE CONTENT IN CHEMISTRY, AND FIVE APPENDIXES OF USEFUL INFORMATION. THE CHEMISTRY COURSE CONTENT IS FURTHER SUBDIVIDED INTO FIVE SECTIONS--(1) THE OVERVIEW, (2) CHEMICAL REACTIONS, (3) CHEMICAL BONDING AND MOLECULAR ARCHITECTURE, (4) DESCRIPTIVE CHEMISTRY, AND (5) ADVANCED CHEMISTRY. EACH OF THE FIVE

WHEELER, HUBERT

450

The Nobel Prize in Chemistry  

NSDL National Science Digital Library

The first hundred years of Nobel Prizes for Chemistry give a beautiful picture of the development of modern chemistry. The prizes cover the whole spectrum of the basic chemical sciences, from theoretical chemistry to biochemistry, and also a number of contributions to applied chemistry.

2001-01-01

451

Secondary atomization  

Microsoft Academic Search

When a drop is subjected to a surrounding dispersed phase that is moving at an initial relative velocity, aerodynamic forces\\u000a will cause it to deform and fragment. This is referred to as secondary atomization. In this paper, the abundant literature\\u000a on secondary atomization experimental methods, breakup morphology, breakup times, fragment size and velocity distributions,\\u000a and modeling efforts is reviewed and

D. R. Guildenbecher; C. Lpez-Rivera; P. E. Sojka

2009-01-01

452

Hot chocolate effect  

SciTech Connect

The ''hot chocolate effect'' was investigated quantitatively, using water. If a tall glass cylinder is filled nearly completely with water and tapped on the bottom with a softened mallet one can detect the lowest longitudinal mode of the water column, for which the height of the water column is one-quarter wavelength. If the cylinder is rapidly filled with hot tap water containing dissolved air the pitch of that mode may descend by nearly three octaves during the first few seconds as the air comes out of solution and forms bubbles. Then the pitch gradually rises as the bubbles float to the top. A simple theoretical expression for the pitch ratio is derived and compared with experiment. The agreement is good to within the 10% accuracy of the experiments.

Crawford, F.S.

1982-05-01

453

Hot fire, cool soil  

NASA Astrophysics Data System (ADS)

Wildfires greatly increase a landscape's vulnerability to flooding and erosion events by removing vegetation and changing soils. Fire damage to soil increases with increasing soil temperature, and, for fires where smoldering combustion is absent, the current understanding is that soil temperatures increase as fuel load and fire intensity increase. Here, however, we show that this understanding that is based on experiments under homogeneous conditions does not necessarily apply at the more relevant larger scale where soils, vegetation, and fire characteristics are heterogeneous. In a catchment-scale fire experiment, soils were surprisingly cool where fuel load was high and fire was hot and, conversely, soils were hot where expected to be cooler. This indicates that the greatest fire damage to soil can occur where fuel load and fire intensity are low rather than high, and has important implications for management of fire-prone areas prior to, during, and after fire events.

Stoof, Cathelijne R.; Moore, Demie; Fernandes, Paulo M.; Stoorvogel, Jetse J.; Fernandes, Ricardo E. S.; Ferreira, Antnio J. D.; Ritsema, Coen J.

2013-04-01

454

Hot Billet Surface Qualifier  

SciTech Connect

OG Technologies, Inc. (OGT), developed a prototype of a Hot Billet Surface Qualifier (Qualifier) based on OGTs patented HotEye technology and other proprietary imaging and computing technologies. The Qualifier demonstrated its ability of imaging the cast billets in line with high definition pictures, pictures capable of supporting the detection of surface anomalies on the billets. The detection will add the ability to simplify the subsequent process and to correct the surface quality issues in a much more timely and efficient manner. This is challenging due to the continuous casting environment, in which corrosive water, temperature, vibration, humidity, EMI and other unbearable factors exist. Each installation has the potential of 249,000 MMBTU in energy savings per year. This represents a cost reduction, reduced emissions, reduced water usage and reduced mill scale.

Tzyy-Shuh Chang

2007-04-30

455

On the chemistry of a-SiO 2 deposition by plasma enhanced CVD  

NASA Astrophysics Data System (ADS)

The chemistry in depositing a-SiO 2 using tetraethoxysilane, Si(OC 2H 5) 4, (TEOS) and tetraisocyanatesilane, Si(NCO) 4, (TICS) with an oxidant is comparatively studied. In both cases, absorption and desorption reactions of intermediate precursors are seen to be dominant. TEOS/O 2 chemistry, where there is no N atom in the source gas, yields conformal step coverage over patterned surfaces. The precursor or precursors generated in TICS/O 2 chemistry are expected to contain N atom or atoms and have no surface migration property. The N atom in the precursor is believed to limit the surface migration property. This results in an uneven step coverage over patterned surfaces similar to that of SiH 4/O 2 chemistry.

Wickramanayaka, Sunil; Nakanishi, Y.; Hatanaka, Y.

1997-04-01

456

Radiological and Environmental Research Division annual report, October 1979-September 1980: fundamental molecular physics and chemistry  

SciTech Connect

Research is reported on the physics and chemistry of atoms, ions, and molecules, especially their interactions with external agents such as photons and electrons. Individual items from the report were prepared separately for the data base. (GHT)

Not Available

1981-09-01

457

Voronoidirichlet polyhedra in crystal chemistry: theory and applications  

Microsoft Academic Search

This review is devoted to the new three-dimensional geometrical methods of crystallochemical analysis based on the VoronoiDirichlet partition of crystal space. It is emphasized that the model of an atom in the crystal field as its VoronoiDirichlet polyhedron seems to be in many cases of interest in crystal chemistry, and satisfactorily reflects the form of an atomic domain. Moreover, the

Vladislav A. Blatov

2004-01-01

458

Exploring Hot Neptune Atmospheres  

Microsoft Academic Search

The first transiting 'hot Neptune'' GJ 436b inhabits an entirely new region of phase space for extrasolar planetary atmospheres. This relatively cool, low-mass object should be the first transiting extrasolar planet to sport a methane-rich atmosphere. Like Uranus and Neptune it may also have an atmosphere highly enriched in heavy elements. Our experience with the complex atmospheres of the known

Jonathan Fortney; Mark Marley; Didier Saumon

2008-01-01

459

Hot-Wheeler-Coaster  

NSDL National Science Digital Library

Students will be put into groups of 3-4 and supplied with the necessary materials to build a hot wheels track that has at least two hills. The challenge will be to design an experiment to test whether the car will coast over a second hill that is at least as high as the first one. Be sure to allow the students the freedom to choose which hill's height to vary, as either will work to demonstrate the lesson concept.

Shaw, Steven

2011-10-13

460

Solar Hot Water Heater  

NASA Technical Reports Server (NTRS)

The solar panels pictured below, mounted on a Moscow, Idaho home, are part of a domestic hot water heating system capable of providing up to 100 percent of home or small business hot water needs. Produced by Lennox Industries Inc., Marshalltown, Iowa, the panels are commercial versions of a collector co-developed by NASA. In an effort to conserve energy, NASA has installed solar collectors at a number of its own facilities and is conducting research to develop the most efficient systems. Lewis Research Center teamed with Honeywell Inc., Minneapolis, Minnesota to develop the flat plate collector shown. Key to the collector's efficiency is black chrome coating on the plate developed for use on spacecraft solar cells, the coating prevents sun heat from "reradiating," or escaping outward. The design proved the most effective heat absorber among 23 different types of collectors evaluated in a Lewis test program. The Lennox solar domestic hot water heating system has three main components: the array of collectors, a "solar module" (blue unit pictured) and a conventional water heater. A fluid-ethylene glycol and water-is circulated through the collectors to absorb solar heat. The fluid is then piped to a double-walled jacket around a water tank within the solar module.

1978-01-01

461

Jupiter's Hot, Mushy Moon  

NASA Technical Reports Server (NTRS)

Jupiter's moon Io is the most volcanically active body in the Solar System. Observations by instruments on the Galileo spacecraft and on telescopes atop Mauna Kea in Hawai'i indicate that lava flows on Io are surprisingly hot, over 1200 oC and possibly as much as 1300 oC; a few areas might have lava flows as hot as 1500 oC. Such high temperatures imply that the lava flows are composed of rock that formed by a very large amount of melting of Io's mantle. This has led Laszlo Keszthelyi and Alfred S. McEwen of the University of Arizona and me to reawaken an old hypothesis that suggests that the interior of Io is a partially-molten mush of crystals and magma. The idea, which had fallen out of favor for a decade or two, explains high-temperature hot spots, mountains, calderas, and volcanic plains on Io. If correct, Io gives us an opportunity to study processes that operate in huge, global magma systems, which scientists believe were important during the early history of the Moon and Earth, and possibly other planetary bodies as well. Though far from proven, the idea that Io has a ocean of mushy magma beneath its crust can be tested with measurements by future spacecraft.

Taylor, G. Jeffrey

2003-01-01

462

Hot spots and hot moments of carbon and nitrogen dynamics in a semiarid riparian zone  

NASA Astrophysics Data System (ADS)

Riparian ecosystems are characterized by spatial and temporal heterogeneity in physical and biological attributes, with consequences for nutrient cycling. We investigated the responses of carbon (C) and nitrogen (N) cycling processes to the hydrogeomorphic template in the riparian zone of the San Pedro River, Arizona, a large (catchment area 11,500 km2), free-flowing, semiarid river. Over an annual period we documented spatial and temporal patterns in soil, shallow groundwater, and stream nutrient chemistry as well as rates of N-transforming processes in soils of the surface (0-17 cm) and region of seasonal saturation (RoSS). A hot moment of N retention and removal was indicated by elevated rates of microbial processes during the summer monsoon season. At the same time, elevated C was observed in soil microbial biomass for both surface soils and soils in the RoSS. Analyses of C-use profiles for soil microbes, coupled with trends in stream and shallow-groundwater chemistry, further suggest that this hot moment of N removal was fueled by newly available, labile organic material. In a spatial context, patchiness in soil resources, microbial biomass, and potential denitrification were best explained by variation in microtopography; low-elevation landscape positions were hot spots of resource availability and microbial activity. Vertical heterogeneity also corresponded with variation in the factors influencing N transformation rates. Organic matter was more frequently a significant factor explaining N transformation rates in RoSS soils whereas soil water content was more often important in surface soils. Together, these patterns suggest that understanding the points on the hydrogeomorphic template, both in space and in time, that bring together water and labile organic matter will lead to greater predictive capability regarding C and N cycling in semiarid river-riparian corridors.

Harms, Tamara K.; Grimm, Nancy B.

2008-03-01

463

Curriculum Outline for Introduction to Engineering Chemistry. Second Edition. Review Cycle-Annual.  

ERIC Educational Resources Information Center

Introduction to Engineering Chemistry is a four-credit hour (one semester) course designed to introduce marine engineering students to the rudiments of basic (introductory) inorganic chemistry. The course consists of 18 units (numbered 1.0 through 18.0) focusing on these subject areas: fundamental concepts; structure of the atom and the periodic

Schlenker, Richard M.

464

The effects of computer animation on the particulate mental models of college chemistry students  

Microsoft Academic Search

Modern chemistry concepts have the particulate nature of matter at their core. Chemists explain most phenomena in terms of atomic and molecular models. The lack of understanding of chemistry concepts may be linked to the students' inability to build complete mental models that visualize particulate behavior. With computer animation technology, dynamic and three-dimensional presentations are possible. This study explores the

Vickie M. Williamson; Michael R. Abraham

1995-01-01

465

Using Computer Visualization Models in High School Chemistry: The Role of Teacher Beliefs.  

ERIC Educational Resources Information Center

This paper discusses the role of high school chemistry teachers' beliefs in implementing computer visualization software to teach atomic and molecular structure from a quantum mechanical perspective. The informants in this study were four high school chemistry teachers with comparable academic and professional backgrounds. These teachers received

Robblee, Karen M.; Garik, Peter; Abegg, Gerald L.; Faux, Russell; Horwitz, Paul

466

Effects of Driving Frequency on the Translational Temperature and Absolute Density of Si Atoms in Very High Frequency Capacitively Coupled SiF4 Plasmas  

NASA Astrophysics Data System (ADS)

The translational temperature and absolute density of Si atoms in capacitively coupled SiF4 plasmas driving with the very high frequency (VHF) of 27 MHz or 60 MHz were measured by ultraviolet absorption spectroscopy employing a ring dye laser and a hollow cathode lamp. High temperatures of Si atoms above 1000 K at 27 MHz were obtained at an electron density of 5.0 1010 cm-3, which is considerably larger than that at 60 MHz at the same electron density. The translational temperature and absolute density of SiF4 molecules were also evaluated using infrared diode laser absorption spectroscopy. From the results measured systematically, it is proposed that the hot Si atom is created due to the difference in the energy of Si atoms produced from the electron impact dissociation of SiFx (x = 1-3) radicals and SiF4 molecules. This result is very important from the viewpoint of diagnostics of atoms and plasma chemistries.

Ohta, Takayuki; Hori, Masaru; Ishida, Tetsuro; Goto, Toshio; Ito, Masafumi; Kawakami, Satoshi; Ishii, Nobuo

2003-12-01

467

Silicon chemistry in interstellar clouds  

NASA Technical Reports Server (NTRS)

Interstellar SiO was discovered shortly after CO but it has been detected mainly in high density and high temperature regions associated with outflow sources. A new model of interstellar silicon chemistry that explains the lack of SiO detections in cold clouds is presented which contains an exponential temperature dependence for the SiO abundance. A key aspect of the model is the sensitivity of SiO production by neutral silicon reactions to density and temperature, which arises from the dependence of the rate coefficients on the population of the excited fine structure levels of the silicon atom. This effect was originally pointed out in the context of neutral reactions of carbon and oxygen by Graff, who noted that the leading term in neutral atom-molecule interactions involves the quadrupole moment of the atom. Similar to the case of carbon, the requirement that Si has a quadrupole moment requires population of the J = 1 level, which lies 111K above the J = 0 ground state and has a critical density n(cr) equal to or greater than 10(6)/cu cm. The SiO abundance then has a temperature dependence proportional to exp(-111/T) and a quadratic density dependence for n less than n(cr). As part of the explanation of the lack of SiO detections at low temperatures and densities, this model also emphasizes the small efficiencies of the production routes and the correspondingly long times needed to reach equilibrium. Measurements of the abundance of SiO, in conjunction with theory, can provide information on the physical properties of interstellar clouds such as the abundances of oxygen bearing molecules and the depletion of interstellar silicon.

Langer, William D.; Glassgold, A. E.

1989-01-01

468

PREFACE: Hot Quarks 2004  

NASA Astrophysics Data System (ADS)

Why another conference devoted to ultra-relativistic heavy-ion physics? As we looked around the landscape of the existing international conferences and workshops, we realized that there was not a single one tailored to the people who are most directly involved with the actual research work: students, post-docs, and junior faculty/research scientists. Of course there are schools, but that was not what we had in mind. We wanted a meeting where young researchers could come together to discuss in depth the physics that they are working on without any hindrance. The major conferences have very limited time for discussions which is often shared amongst the most established. This leaves little room for young people to ask their questions and to get the detailed feedback which they deserve and which satisfies their curiosity. A discussion-driven workshop, centering on those without whom there will be no futurethat seemed like what was needed. And thus the Hot Quarks workshop was born. The aim of Hot Quarks was to enhance the direct exchange of scientific information among the younger members of the community, from both experiment and theory. Participation was by invitation only in order to emphasize the contributions from junior researchers. This approach makes the workshop unique among the many forums in the field. For young scientists it represented an opportunity for exposure that they would not have had in one of the major conferences. The hope is that this meeting has helped to stimulate the next generation of scientists in our field and, at the same time, strengthened their sense of community. It all came together from 18 24 July 2004, when the 77 participants met at The Inn at Snakedance in the Taos Ski Valley, New Mexico, USA, for the first Hot Quarks workshop. Photograph Participants gather in the sunshine at the foot of the Taos Ski Valley chairlift. By all accounts, Hot Quarks 2004 was a great success. Every participant had the opportunity to present her or his research and we spent an entire week talking physics and having fun from breakfast in the morning until late at night. A symbolic award was instituted for the best presentation at the workshop, dedicated to the memory of Klaus Kinder-Geiger, a sharp and brilliant young theorist who perished in the crash of Swissair Flight 111 on 2 September 1998 off the coast of Nova Scotia. It went to Denesh Molnar from Ohio State University for his outstanding talk on parton coalescence. The organizers wish to extend their gratitude to all participants for the high quality presentations making Hot Quarks 2004 a notable event. We are also very grateful for the superb hospitality of the staff of the Snakedance Inn, in particular Mitch Daniels who worked sheer miracles. Given the success of the first Hot Quarks workshop we decided to organize a second one, possibly even turning Hot Quarks into a series. The next meeting will be held in the late spring of 2006, probably in Italy. We hope it will be as memorable as the first one! Last but not least, we wish to thank all the generous sponsors of the conference: Brookhaven National Laboratory, European Organization for Nuclear Research (CERN), Gesellschaft fA~ 1/4 r Schwerionenforschung (GSI), Institute of Physics Publishing, Los Alamos National Laboratory, National Science Foundation, and Vanderbilt University. We are grateful for their support and are particularly happy that this support came from institutions both in the US and in Europe and from all the main experimental facilities that pursue a prominent heavy-ion program. Their support was essential for the success of a workshop targeting young scientists.

Antinori, Federico; Bass, Steffen A.; Bellwied, Rene; Ullrich, Thomas; Velkovska, Julia; Wiedemann, Urs

2005-04-01

469

Average Description of Dipole Gamma Transitions in Hot Atomic Nuclei  

NASA Astrophysics Data System (ADS)

A new version of the modified Lorentzian approach for radiative strength function is proposed. It is based on renewed systematics for giant dipole resonance (GDR) parameters. The gamma-decay strength functions are calculated using new GDR parameters and compared with experimental data. It is demonstrated that closed-form approaches with energy-dependent width of the gamma strength, as a rule, provide a reliable simple method for description of gamma-decay processes.

Plujko, V. A.; Gorbachenko, O. M.; Rovenskykh, E. P.; Zheltonozhskii, V. A.

2014-04-01

470

Atomic structure and spectral perturbations in hot dense plasmas  

NASA Astrophysics Data System (ADS)

Interaction mechanisms between the quantic structures of multicharged ions and dense plasmas are studied. The theoretical research aims at better understanding the microscopic aspects of equilibrium equations in ultradense plasmas and at developing optical diagnostic methods for such plasmas. It is concluded that the facilities allow such research to be performed.

Nguyen, Hoe; Grumberg, Jeanne; Leboucher-Dalimier, Elisabeth; Malnoult, Philippe; Arranz, Jean-Pierre; Brisard, Monique; Reggadi, Abdelkader; Poquerusse, Alain

1991-05-01

471

Atomic research  

NASA Technical Reports Server (NTRS)

Work performed by the University of Alabama in Huntsville's (UAH) Center for Applied Optics (CAO) entitled Atomic Research is documented. Atomic oxygen (AO) effects on materials have long been a critical concern in designing spacecraft to withstand exposure to the Low Earth Orbit (LEO) environment. The objective of this research effort was to provide technical expertise in the design of instrumentation and experimental techniques for analyzing materials exposed to atomic oxygen in accelerated testing at NASA/MSFC. Such testing was required to answer fundamental questions concerning Space Station Freedom (SSF) candidate materials and materials exposed to atomic oxygen aboard the Long-Duration Exposure Facility (LDEF). The primary UAH task was to provide technical design, review, and analysis to MSFC in the development of a state-of-the-art 5eV atomic oxygen beam facility required to simulate the RAM-induced low earth orbit (LEO) AO environment. This development was to be accomplished primarily at NASA/MSFC. In support of this task, contamination effects and ultraviolet (UV) simulation testing was also to be carried out using NASA/MSFC facilities. Any materials analysis of LDEF samples was to be accomplished at UAH.

Hadaway, James B.; Connatser, Robert; Cothren, Bobby; Johnson, R. B.

1993-01-01

472

Actuated atomizer  

NASA Technical Reports Server (NTRS)

An actuated atomizer is adapted for spray cooling or other applications wherein a well-developed, homogeneous and generally conical spray mist is required. The actuated atomizer includes an outer shell formed by an inner ring; an outer ring; an actuator insert and a cap. A nozzle framework is positioned within the actuator insert. A base of the nozzle framework defines swirl inlets, a swirl chamber and a swirl chamber. A nozzle insert defines a center inlet and feed ports. A spool is positioned within the coil housing, and carries the coil windings having a number of turns calculated to result in a magnetic field of sufficient strength to overcome the bias of the spring. A plunger moves in response to the magnetic field of the windings. A stop prevents the pintle from being withdrawn excessively. A pintle, positioned by the plunger, moves between first and second positions. In the first position, the head of the pintle blocks the discharge passage of the nozzle framework, thereby preventing the atomizer from discharging fluid. In the second position, the pintle is withdrawn from the swirl chamber, allowing the atomizer to release atomized fluid. A spring biases the pintle to block the discharge passage. The strength of the spring is overcome, however, by the magnetic field created by the windings positioned on the spool, which withdraws the plunger into the spool and further compresses the spring.

Tilton, Charles (Inventor); Weiler, Jeff (Inventor); Palmer, Randall (Inventor); Appel, Philip (Inventor)

2008-01-01

473

Mechanical gate control for atom-by-atom cluster assembly with scanning probe microscopy.  

PubMed

Nanoclusters supported on substrates are of great importance in physics and chemistry as well as in technical applications, such as single-electron transistors and nanocatalysts. The properties of nanoclusters differ significantly from those of either the constituent atoms or the bulk solid, and are highly sensitive to size and chemical composition. Here we propose a novel atom gating technique to assemble various atom clusters composed of a defined number of atoms at room temperature. The present gating operation is based on the transfer of single diffusing atoms among nanospaces governed by gates, which can be opened in response to the chemical interaction force with a scanning probe microscope tip. This method provides an alternative way to create pre-designed atom clusters with different chemical compositions and to evaluate their chemical stabilities, thus enabling investigation into the influence that a single dopant atom incorporated into the host clusters has on a given cluster stability. PMID:25014188

Sugimoto, Yoshiaki; Yurtsever, Ayhan; Hirayama, Naoki; Abe, Masayuki; Morita, Seizo

2014-01-01

474

The origin of anti-wear chemistry of ZDDP.  

PubMed

Molecular Dynamics has been used to simulate the anti-wear chemistry of zinc dialkyl dithiophosphate (ZDDP). The model simulates the digestion of abrasive particles into the zinc polyphosphate glass. The main result is that the driving force for the tribochemical reaction is not temperature but entropy due to mechanical mixing at the atomic scale. PMID:23285636

Martin, Jean Michel; Onodera, Tasuku; Minfray, Clotilde; Dassenoy, Fabrice; Miyamoto, Akira

2012-01-01

475

Energetic Metastable Oxygen and Nitrogen Atoms in the Terrestrial Atmosphere  

NASA Technical Reports Server (NTRS)

We have investigated the energy distributions of the metastable oxygen atoms in the terrestrial thermosphere. Nascent O(lD) atoms play a fundamental role in the energy balance and chemistry of the terrestrial atmosphere, because they are produced by photo-chemical reactions in the excited electronic states and carry significant translational energies.

Kharchenko, Vasili

2003-01-01

476

Is It Time to Retire the Hybrid Atomic Orbital?  

ERIC Educational Resources Information Center

A rationale for the removal of the hybrid atomic orbital from the chemistry curriculum is examined. Although the hybrid atomic orbital model does not accurately predict spectroscopic energies, many chemical educators continue to use and teach the model despite the confusion it can cause for students. Three arguments for retaining the model in the

Grushow, Alexander

2011-01-01

477

Atom Interferometry  

ScienceCinema

Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newtons constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

478

Atom Interferometry  

SciTech Connect

Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton's constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gyroscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be used to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

Kasevich, Mark (Stanford University) [Stanford University

2008-05-08

479

Atom Interferometry  

ScienceCinema

Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton's constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gyroscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be used to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

480

Atom Interferometry  

SciTech Connect

Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newtons constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

Mark Kasevich

2008-05-07