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1

Hot atom chemistry and radiopharmaceuticals  

SciTech Connect

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. [University of Washington, Department of Radiology, Molecular Imaging Center, 1959 NE Pacific St., Box 356004, Seattle, WA 98195-6004 (United States); Washington University, Department of Radiology, Division of Radiological Sciences, 510 South Kingshighway, St. Louis, MO 63110 (United States); University of Washington, Department of Radiology, Molecular Imaging Center, 1959 NE Pacific St., Box 356004, Seattle, WA 98195-6004 (United States); Washington University, Department of Radiology, Division of Radiological Sciences, 510 South Kingshighway, St. Louis, MO 63110 (United States)

2012-12-19

2

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

3

Hot atoms in cosmic chemistry.  

PubMed

High energy chemical reactions and atom molecule interactions might be important for cosmic chemistry with respect to the accelerated species in solar wind, cosmic rays, colliding gas and dust clouds and secondary knock-on particles in solids. "Hot" atoms with energies ranging from a few eV to some MeV can be generated via nuclear reactions and consequent recoil processes. The chemical fate of the radioactive atoms can be followed by radiochemical methods (radio GC or HPLC). Hot atom chemistry may serve for laboratory simulation of the reactions of energetic species with gaseous or solid interstellar matter. Due to the effective measurement of 10(8)-10(10) atoms only it covers a low to medium dose regime and may add to the studies of ion implantation which due to the optical methods applied are necessarily in the high dose regime. Experimental results are given for the systems: C/H2O (gas), C/H2O (solid, 77 K), N/CH4 (solid, 77K) and C/NH3 (solid, 77 K). Nuclear reactions used for the generation of 2 to 3 MeV atoms are: N(p,alpha) 11C, 16O(p,alpha pn) 11C and 12C(d,n) 13N with 8 to 45 MeV protons or deuterons from a cyclotron. Typical reactions products are: CO, CO2, CH4, CH2O, CH3OH, HCOOH, NH3, CH3NH2, cyanamide, formamidine, guanidine etc. Products of hot reactions in solids are more complex than in corresponding gaseous systems, which underlines the importance of solid state reactions for the build-up of precursors for biomolecules in space. As one of the major mechanisms for product formation, the simultaneous or fast consecutive reactions of a hot carbon with two target molecules (reaction complex) is discussed. PMID:11537799

Rossler, K; Jung, H J; Nebeling, B

1984-01-01

4

Hot hydrogen atoms - Initiators of reactions of interest in interstellar chemistry and evolution  

NASA Technical Reports Server (NTRS)

Hot hydrogen atoms possess kinetic (or translational) energy in excess of that to be expected if the atoms were in thermal equilibrium with the surroundings. In the investigation reported the hot hydrogen atoms were generated by the photolysis of donor molecules. The light sources for the photolysis were 1000-watt xenon or 500-watt mercury lamps combined with a filter system. The experiments show that hot hydrogen atoms can initiate reactions among simple molecules to produce biomolecules of significance.

Hong, K.-Y.; Hong, J.-H.; Becker, R. S.

1974-01-01

5

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

6

Hot hydrogen atoms reactions of interest in molecular evolution and interstellar chemistry  

NASA Technical Reports Server (NTRS)

Hot hydrogen atoms which are photochemically generated initiate reactions among mixtures of methane, ethane, water and ammonia, to produce ethanol, organic amines, organic acids, and amino acids. Both ethanol and ethyl amine can also act as substrates for formation of amino acids. The one carbon substrate methane is sufficient as a carbon source to produce amino acids. Typical quantum yields for formation of amino acids are approximately 0.00002 to 0.00004. In one experiment, 6 protein amino acids were identified and 8 nonprotein amino acids verified utilizing gas chromatography-mass spectroscopy. We propose that hot atoms, especially hydrogen, initiate reactions in the thermodynamic nonequilibrium environment of interstellar space as well as in the atmospheres of planets.

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

1974-01-01

7

Hot and super-hot hydrogen atoms in microwave plasma  

SciTech Connect

'Super-hot' (kinetic energy {approx}4-8 eV) and 'hot' (kinetic energy {approx}0.3 eV) H atoms were detected in a surface wave (500 MHz) generated H{sub 2} plasma column, at pressure p=0.01 mbar, from the analysis of the H{sub {beta}}, H{sub {gamma}}, H{sub {delta}}, and H{sub {epsilon}} emission line profiles. These profiles were found to evolve from single Gaussian to bi-Gaussian toward the plasma column end. Population inversion between the levels 5{yields}4 and 6{yields}4 was detected. At pressure p=0.2 mbar, super-hot atoms were not detected and the temperature of the hot atoms was found to increase with the upper level principal quantum number.

Tatarova, E.; Felizardo, E.; Dias, F. M.; Lino da Silva, M.; Ferreira, C. M. [Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Gordiets, B. [Lebedev Physics Institute, 11991 Moscow (Russian Federation)

2009-11-02

8

Hot hydrogen in prebiological and interstellar chemistry  

NASA Technical Reports Server (NTRS)

Two articles discuss the recent experimental work of Hong et al. on the production of amino acids and gas-phase organic compounds from the ultraviolet irradiation of simple gases, with hot hydrogen atoms used as the principal energy conversion agent. The reaction possibilities involving frozen ices are mentioned in both articles, as well as the significance of three-body collisions in this situation.

Sagan, C.

1975-01-01

9

Cold Light from Hot Atoms and Molecules  

SciTech Connect

The introduction of rare earth atoms and molecules into lighting discharges led to great advances in efficacy of these lamps. Atoms such as Dy, Ho and Ce provide excellent radiation sources for lighting applications, with rich visible spectra, such that a suitable combination of these elements can provide high quality white light. Rare earth molecules have also proved important in enhancing the radiation spectrum from phosphors in fluorescent lamps. This paper reviews some of the current aspects of lighting research, particularly rare earth chemistry and radiation, and the associated fundamental atomic and molecular data.

Lister, Graeme [OSRAM SYLVANIA, CRSL, 71 Cherry Hill Drive, Beverly, MA (United States); Curry, John J. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

2011-05-11

10

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

11

RADIOACTIVE METALLOFULLERENES: HOT ATOM CHEMISTRY ASPECTS.  

E-print Network

with radioactive isotopes can be useful for medical diagnostics, therapy of cancer and immunotherapy. Itinerary in reactor on metallofullerenes and what is survivability of original chemical form at thermal neutron is retention, percent of capture events which retain the original molecule. The thermal neutron capture results

Titov, Anatoly

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

Atomic Absorption Spectrometry Perkin Elmer 500, Chemistry & Biochemistry  

E-print Network

Atomic Absorption Spectrometry · Perkin Elmer 500, Chemistry & Biochemistry · Perkin Elmer 560 AA calorimeter, Chemistry & Biochemistry Cell Sorting and Harvesting · B-D FacsCalibur - cell sorter, CBMG · Cell Ultracentrifuge with Scanning UV/Vis Absorbance and Rayleigh Interference, Chemistry & Biochemistry · Beckman J-6B

Gruner, Daniel S.

14

The early days of atomic absorption spectrometry in clinical chemistry  

NASA Astrophysics Data System (ADS)

An account is given of the first applications of atomic absorption spectrometry in clinical chemistry. These include the determination of calcium and magnesium in blood serum and of these elements, together with a range of heavy metals, in urine.

Willis, J. B.

1999-12-01

15

Reaction studies of hot silicon, germanium and carbon atoms  

SciTech Connect

The goal of this project was to increase the authors understanding of the interplay between the kinetic and electronic energy of free atoms and their chemical reactivity by answering the following questions: (1) what is the chemistry of high-energy carbon silicon and germanium atoms recoiling from nuclear transformations; (2) how do the reactions of recoiling carbon, silicon and germanium atoms take place - what are the operative reaction mechanisms; (3) how does the reactivity of free carbon, silicon and germanium atoms vary with energy and electronic state, and what are the differences in the chemistry of these three isoelectronic atoms This research program consisted of a coordinated set of experiments capable of achieving these goals by defining the structures, the kinetic and internal energy, and the charge states of the intermediates formed in the gas-phase reactions of recoiling silicon and germanium atoms with silane, germane, and unsaturated organic molecules, and of recoiling carbon atoms with aromatic molecules. The reactions of high energy silicon, germanium, and carbon atoms created by nuclear recoil were studied with substrates chosen so that their products illuminated the mechanism of the recoil reactions. Information about the energy and electronic state of the recoiling atoms at reaction was obtained from the variation in end product yields and the extent of decomposition and rearrangement of primary products (usually reactive intermediates) as a function of total pressure and the concentration of inert moderator molecules that remove kinetic energy from the recoiling atoms and can induce transitions between electronic spin states. 29 refs.

Gaspar, P.P.

1990-11-01

16

Presentation of Atomic Structure in Turkish General Chemistry Textbooks  

ERIC Educational Resources Information Center

Research in science education has recognized the importance of teaching atomic structure within a history and philosophy of science perspective. The objective of this study is to evaluate general chemistry textbooks published in Turkey based on the eight criteria developed in previous research. Criteria used referred to the atomic models of

Niaz, Mansoor; Costu, Bayram

2009-01-01

17

Production and reactions of silicon atoms in hot wire deposition of amorphous silicon  

NASA Astrophysics Data System (ADS)

Decomposing silane and hydrogen molecules on a hot tungsten filament is an alternative method of depositing hydrogenated microcrystal and amorphous Si for thin-film semmiconductor devices. This "hot-wire" method can have significant advantages, such as high film deposition rates. The deposition chemistry involves Si and H atoms released from the filament, followed by their reactions with the vapor and surfaces. To establish these deposition pathways, we measure radicals at the substrate with a home built, threshold ionization mass spectrometer. The design and operation of this mass spectrometer for radical detection, and the behavior of Si atom production and reactions, will be presented. This work is supported by the National Renewable Energy Laboratory, Golden, CO 80401

Zheng, Wengang; Gallagher, Alan

2003-10-01

18

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

19

Elements and Atoms: Case Studies in the Development of Chemistry  

NSDL National Science Digital Library

Carmen Giunta at Le Moyne College created this website to offer a series of articles by the pioneers in the science of atoms and elements. The author provides background and commentary on the work in order to educate users about how scientists work. The website is divided into four parts: elements, atoms, classification of atoms, and back to atoms. Students can find links for definitions of archaic chemical terms throughout the articles. Those interested in the history of chemistry will find fascinating materials on Aristotle, Lavoisier, Soddy, and many more prominent scientists.

Giunta, Carmen

20

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

21

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

22

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

23

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

24

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

25

Phase equilibria constraints on the chemistry of hot spring fluids at mid-ocean ridges  

Microsoft Academic Search

Recent advances in experimental and theoretical geochemistry have made it possible to assess both homogeneous and heterogeneous equilibria involving a wide range of aqueous species at temperatures and pressures appropriate to model hydrothermal alteration processes at mid-ocean ridges. The authors have combined selected aspects of the chemistry of hot spring fluids with constraints imposed by a geologically reasonable assemblage of

W. E. Jr. Seyfried; K. Ding; M. E. Berndt

1991-01-01

26

The Relation Between Alloy Chemistry and Hot-Cracking  

NASA Technical Reports Server (NTRS)

Hot cracking is a problem in welding 2195 aluminum-lithium alloy. Weld wire additives seem to reduce the problem. This study proposes a model intended to clarify the way alloying elements affect hot-cracking. The brittle temperature range of an alloy extends wherever the tensile stress required to move the meniscus of the liquid film at the grain/dendrite boundaries is less than the bulks flow stress Sigma(sub B) of the grains: 2gamma/delta <= sigma(sub B) + P where gamma is boundary film surface tension delta= boundary film thickness P = gas pressure (Some alloys outgas.) If the above condition is not met, the grains deform under stress and the liquid film remains in place. Curves of 2gamma/delta and sigma(sub B) vs. temperature in the range just below the melting temperature determine the hot cracking susceptibility of an alloy. Both are zero at onset of solidification. sigma(sub B) rises as the thermal activation of the slip mechanism is reduced. 2gamma/delta rises as the film thickness delta which can be estimated from the Scheil equation, drops. But, given an embrittled alloy, whether the alloy actually cracks is determined by the strain imposed upon it in the embrittled condition. A critical strain is estimated, Epsilon(sub C) on the order of Epsilon(sub C) is approximately delta/l where L = grain size and where the the volume increment due to the strain, concentrated at the liquid film, is on the order of the liquid film volume. In the early 80's an empirical critical strain cracking envelope Epsilon(sub C)(T) was incorporated into a damage criterion to estimate the effect of welding parameters on the formation of microfissures in a superalloy with good results. These concepts, liquid film decoherence vs. grain bulk deformation and critical strain, form the key elements of a quantitative theory of hot-cracking applicable for assessing the effect of alloying elements on hot-cracking during welding.

Nunes, A. C., Jr.; Talia, J. E.

2000-01-01

27

Hot-wire produced atomic hydrogen: effects during and after amorphous-silicon deposition  

Microsoft Academic Search

The role of hot-wire atomic hydrogen during a-Si:H deposition is elucidated by investigating hydrogen diffusion into and within hot-wire deposited a-Si:H films. We exposed device-quality a-Si:H layers to atomic hydrogen in order to mimic the atomic hydrogen flux during deposition. Initially, exposure of as-deposited a-Si:H films leads to an enhancement of the hydrogen concentration by a factor of 2. A

A. M Brockhoff; W. F van der Weg; F. H. P. M Habraken

2001-01-01

28

Equilibrium Chemistry Calculations for Model Hot-Jupiter Atmospheres  

NASA Astrophysics Data System (ADS)

Every planet in our solar system has different elemental abundances from our sun's. It is thus necessary to explore a variety of elemental abundances when investigating exoplanet atmospheres. Composition is key to unraveling a planet's formation history and determines the radiative behavior of an atmosphere, including its spectrum (Moses et al. 2013). We consider here two commonly discussed situations: [C]/[O] > 1 and 10x and 100x heavy-element enrichment. For planets above 1200 K, equilibrium chemistry is a valid starting point in atmospheric analysis. For HD 209458b, this assumption was verified by comparing the results of a robust kinetics code (non-ideal behavior) to the results of an equilibrium chemistry code (ideal behavior). Both codes output similar results for the dayside of the planet (Agundez et al. 2012). Using NASA's open-source Chemical Equilibrium Abundances code (McBride and Gordon 1996), we calculate the molecular abundances of species of interest across the dayside of model planets with a range of: elemental abundance profiles, degree of redistribution, relevant substellar temperatures, and pressures. We then explore the compositional gradient of each model planet atmosphere layer using synthetic abundance images of target spectroscopic species (water, methane, carbon monoxide). This work was supported by the NASA Planetary Atmospheres grant NNX12AI69G and NASA Astrophysics Data Analysis Program NNX13AF38G.

Blumenthal, Sarah; Harrington, Joseph; Bowman, M. Oliver; Blecic, Jasmina

2014-11-01

29

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

30

Applications of Atomic Force Microscopy in Biophysical Chemistry of Cells  

PubMed Central

This article addresses the question of what information and new insights atomic force microscopy (AFM) provides that are of importance and relevance to cellular biophysical chemistry research. Three enabling aspects of AFM are discussed: (a) visualization of membrane structural features with nanometer resolution, such as microvilli, ridges, porosomes, lamellapodia, and filopodia; (b) revealing structural evolution associated with cellular signaling pathways by time-dependent and high-resolution imaging of the cellular membrane in correlation with intracellular components from simultaneous optical microscopy; and (c) qualitative and quantitative measurements of single cell mechanics by acquisition of force-deformation profiles and extraction of Youngs moduli for the membrane as well as cytoskeleton. A future prospective of AFM is also presented. PMID:20405961

Deng, Zhao; Lulevich, Valentin; Liu, Fu-tong; Liu, Gang-yu

2014-01-01

31

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

32

Analysis and control Cluster Chemistry And Dynamics Special Feature: Ultrafast dynamics in atomic clusters  

E-print Network

alerts when new articles cite this article - sign up in the box Subspecialty Collections www.pnas.org/cgi/collection/cluster_chemistry Cluster Chemistry and Dynamics Special Feature collection(s): This article, along with others on similarAnalysis and control Cluster Chemistry And Dynamics Special Feature: Ultrafast dynamics in atomic

Berry, R. Stephen

33

Unraveling the complex chemistry using dimethylsilane as a precursor gas in hot wire chemical vapor deposition.  

PubMed

The gas-phase reaction chemistry when using dimethylsilane (DMS) as a source gas in a hot-wire chemical vapor deposition (CVD) process has been studied in this work. The complex chemistry is unraveled by using a soft 10.5 eV single photon ionization technique coupled with time-of-flight mass spectrometry in combination with the isotope labelling and chemical trapping methods. It has been demonstrated that both free-radical reactions and those involving silylene/silene intermediates are important. The reaction chemistry is characterized by the formation of 1,1,2,2-tetramethyldisilane (TMDS) from dimethylsilylene insertion into the Si-H bond of DMS, trimethylsilane (TriMS) from free-radical recombination, and 1,3-dimethyl-1,3-disilacyclobutane (DMDSCB) from the self dimerization of either dimethylsilylene or 1-methylsilene. At low filament temperatures and short reaction time, silylene chemistry dominates. The free-radical reactions become more important with increasing temperature and time. The same three products have been detected when using tantalum and tungsten filaments, indicating that changing the filament material from Ta to W does not affect much the gas-phase reaction chemistry when using DMS as a source gas in a hot-wire CVD reactor. PMID:24647875

Toukabri, Rim; Shi, Yujun

2014-05-01

34

Effect of molecular size on the threshold energy producing a 51 Cr hot atom  

Microsoft Academic Search

The lowest retention values of51Cr hot atom in various forms of the -diketonetype complexes, Cr(bzac)3, Cr(dpm)3 and Cr(dbm)3, as well as Cr(acac)3 as a reference, were obtained in the experimental condition in which they are regarded as the primary retentions. From these retention values, the threshold energies for producing a hot atom, the appearance energies, were estimated using the calculated

T. Matsuura; H. Takenawa; T. Suzuki; R. Hirota; K. Sasaki

1990-01-01

35

Atomic Carbon Chemistry in Photolyzed Triton-like Ices  

NASA Astrophysics Data System (ADS)

We report photochemical studies of thin cryogenic ice films composed of N2, CH4 and CO in ratios similar to those on the surfaces of Neptune's largest satellite, Triton, and on Pluto. Experiments were performed using a hydrogen discharge lamp, which provides an intense source of ultraviolet light in order to elucidate the solar induced photochemistry of these icy bodies. Characterization via infrared spectroscopy showed that C2H6 and C2H2, and HCO are formed by the dissociation of CH4 into H and CH3 and the subsequent reaction of these radicals within the ice. Other radical species, such as C2, C2-, CN, and CNN are observed in the visible and UV regions of the spectrum. These species imply a rich chemistry based on reactions of atomic carbon with the N2 matrix. We discuss the implications of the formation of these radicals for the chemical evolution of Triton and Pluto. Ultimately, this work suggests that C2-, CN, HCO, and CNN may be found in significant quantities on the surfaces of Triton and Pluto and that new observations of these objects in the appropriate wavelength regions are warranted.

Johnson, Paul; Hodyss, R.; Howard, H. R.; Goguen, J. D.; Kanik, I.

2010-10-01

36

Atomic Structure. Independent Learning Project for Advanced Chemistry (ILPAC). Unit S2.  

ERIC Educational Resources Information Center

This unit on atomic structure is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit consists of two levels. Level one focuses on the atomic nucleus. Level two focuses on the arrangement of extranuclear electrons, approaching atomic orbitals through both electron bombardment and spectra.

Inner London Education Authority (England).

37

Cavity QED and quantum information processing with "hot" trapped atoms  

E-print Network

We propose a method to implement cavity QED and quantum information processing in high-Q cavities with a single trapped but non-localized atom. The system is beyond the Lamb-Dick limit due to the atomic thermal motion. Our method is based on adiabatic passages, which make the relevant dynamics insensitive to the randomness of the atom position with an appropriate interaction configuration. The validity of this method is demonstrated from both approximate analytical calculations and exact numerical simulations. We also discuss various applications of this method based on the current experimental technology.

L. -M. Duan; A. Kuzmich; H. J. Kimble

2002-08-08

38

Modeling Bohr's theory of hydrogen atom for physics and chemistry education, and computer science graduates  

Microsoft Academic Search

This article is basically targeted for the advanced university and college undergraduate and graduate students of physics and chemistry education, computational physics and chemistry, and computer science. Here, we employed Microsoft Excel software system to perform computer simulations for modeling Bohr's theory of hydrogen atom in college and university classroom setting. We developed necessary computer algorithm to compute discrete values

Gurmukh Singh; Amitabha Mukhopadyay

2010-01-01

39

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

40

Atomic-resolution characterization of interface structure and chemistry in the STEM  

SciTech Connect

Combination of Z-contrast imaging and EELS (electron energy loss spectroscopy) allows the local structure and chemistry of interfaces to be determined on the atomic scale. In this paper, these two complementary techniques are used to analyze the structure and chemistry of a nominally 25 degree [100] symmetric tilt boundary in an electroceramic SrTiO{sub 3} bicrystal.

Browning, N.D.; McGibbon, M.M.; McGibbon, A.J.; 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

1994-03-01

41

Evolution of the Atomic Concept and the Beginnings of Modern Chemistry  

NSDL National Science Digital Library

This website from the University of Virginia provides an overview of the advancements in chemistry and physics that led to the atomic model of matter. The ideas of Galileo, Dalton, Gay-Lussac, Avogadro, and others are presented in order to describe the development of kinetic theory, element patterns, and other concepts in modern chemistry. Also, the site quotes nineteenth century scientists who opposed the atomic model.

Fowler, Michael

2006-11-21

42

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

43

Dry soldering with hot filament produced atomic hydrogen  

DOEpatents

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

44

Dry soldering with hot filament produced atomic hydrogen  

DOEpatents

A system 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.

Panitz, Janda K. G. (Edgewood, NM); Jellison, James L. (Albuquerque, NM); Staley, David J. (Los Lunas, NM)

1995-01-01

45

Preliminary considerations of high temperature aqueous chemistry for representative hot springs in Guangdong, China  

NASA Astrophysics Data System (ADS)

This presentation aims at helping understand general physical and chemical conditions that control geothermal flow to the ground surface. Conditions directly under the ground surface play critical roles in determining the pattern of geothermal flow fields. Controlling factors include structural features, source temperature, hydraulic properties, chemical conditions etc. However, they are hardly measured in a comprehensive way in laboratory or field experimental conditions. There are needs for characterizing conditions evolving during upward thermal flow and to relate physics and chemistry to heat distribution. Geothermal flow depends on exactly how heat diffusion works in the deep ground (the heat conductivity and convection), and the physics and chemistry behind this is complex and not well understood. We employed aqueous geochemistry methods to study heat and geochemistry behavior in deep underground. We develop scheme to relate elevated temperatures and heat to chemistry. The setup for elevated heat is expected to expand the capability of numerical models, so that the temperature effect can be more completely described. The heat has a significant effect on the speciation of water, tending to be more acidic and at more reduced state at an elevated temperature. For example, given an average pH 8.3 for spring outflow cooled down to 25oC, the corresponding hot water at 200oC could have pH as low as 5.8. The findings show that the numerical model effectively simulates chemical behavior in deep ground.

Lu, G.; Liu, R.; Gu, R.; Wang, Y.

2013-12-01

46

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. PMID:8962040

Kellman, Michael E.

1996-01-01

47

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

48

The impact of atmospheric circulation on the chemistry of the hot Jupiter HD 209458b  

E-print Network

We investigate the effects of atmospheric circulation on the chemistry of the hot Jupiter HD 209458b. We use a simplified dynamical model and a robust chemical network, as opposed to previous studies which have used a three dimensional circulation model coupled to a simple chemical kinetics scheme. The temperature structure and distribution of the main atmospheric constituents are calculated in the limit of an atmosphere that rotates as a solid body with an equatorial rotation rate of 1 km/s. Such motion mimics a uniform zonal wind which resembles the equatorial superrotation structure found by three dimensional circulation models. The uneven heating of this tidally locked planet causes, even in the presence of such a strong zonal wind, large temperature contrasts between the dayside and nightside, of up to 800 K. This would result in important longitudinal variations of some molecular abundances if the atmosphere were at chemical equilibrium. The zonal wind, however, acts as a powerful disequilibrium process...

Agundez, M; Iro, N; Selsis, F; Hersant, F; Hebrard, E; Dobrijevic, M

2012-01-01

49

Comparative Study on Hot Atom Coronae of Solar and Extrasolar Planets  

NASA Astrophysics Data System (ADS)

Solar/stellar forcing on the upper atmospheres of the solar and extrasolar planets via both absorption of the XUV (soft X-rays and extreme ultraviolet) radiation and atmospheric sputtering results in the formation of an extended neutral corona populated by the suprathermal (hot) H, C, N, and O atoms (see, e.g., Johnson et al., 2008). The hot corona, in turn, is altered by an inflow of the solar wind/magnetospheric plasma and local pick-up ions onto the planetary exosphere. Such inflow results in the formation of the superthermal atoms (energetic neutral atoms - ENAs) due to the charge exchange with the high-energy precipitating ions and can affect the long-term evolution of the atmosphere due to the atmospheric escape. The origin, kinetics and transport of the suprathermal H, C, N, and O atoms in the transition regions (from thermosphere to exosphere) of the planetary atmospheres are discussed. Reactions of dissociative recombination of the ionospheric ions CO _{2} (+) , CO (+) , O _{2} (+) , and N _{2} (+) with thermal electrons are the main photochemical sources of hot atoms. The dissociation of atmospheric molecules by the solar/stellar XUV radiation and accompanying photoelectron fluxes and the induced exothermic photochemistry are also the important sources of the suprathermal atoms. Such kinetic systems with the non-thermal processes are usually investigated with the different (test particles, DSMC, and hybrid) versions of the kinetic Monte Carlo method. In our studies the kinetic energy distribution functions of suprathermal and superthermal atoms were calculated using the stochastic model of the hot planetary corona (Shematovich, 2004, 2010; Groeller et al., 2014), and the Monte Carlo model (Shematovich et al., 2011, 2013) of the high-energy proton and hydrogen atom precipitation into the atmosphere respectively. These functions allowed us to estimate the space distribution of suprathermals in the planetary transition regions. An application of these numerical models to study the atmospheric gas flow in the transition region from the collision-dominated thermosphere to collisionless exosphere, and the non-thermal escape will be discussed and illustrated with the simple 1D-models of the hot coronae of the solar and extrasolar planets. This work is supported by the RFBR project No. 14-02-00838a and by the Basic Research Program of the Presidium of the Russian Academy of Sciences (Program 22). begin{itemize} Johnson et al., Sp. Sci.Rev., 2008, v. 139, 355. Shematovich, Solar System Res., 2004, v.38, 28. Shematovich, Solar System Res., 2010, v.44, 96. Shematovich et al., J. Geophys. Res., 2011, v.116, A11320; 2013, v. 118, 1231. Groeller et al., Planet. Space Sci., 2014.

Shematovich, Valery

50

Scattering of cold-atom coherences by hot atoms: frequency shifts from background-gas collisions.  

PubMed

Frequency shifts from background-gas collisions currently contribute significantly to the inaccuracy of atomic clocks. Because nearly all collisions with room-temperature background gases that transfer momentum eject the cold atoms from the clock, the interference between the scattered and unscattered waves in the forward direction dominates these frequency shifts. We show they are ? 10 times smaller than in room-temperature clocks and that van der Waals interactions produce the cold-atom background-gas shift. General considerations allow the loss of the Ramsey fringe amplitude to bound this frequency shift. PMID:23683186

Gibble, Kurt

2013-05-01

51

Scattering of Cold-Atom Coherences by Hot Atoms: Frequency Shifts from Background-Gas Collisions  

NASA Astrophysics Data System (ADS)

Frequency shifts from background-gas collisions currently contribute significantly to the inaccuracy of atomic clocks. Because nearly all collisions with room-temperature background gases that transfer momentum eject the cold atoms from the clock, the interference between the scattered and unscattered waves in the forward direction dominates these frequency shifts. We show they are ?10 times smaller than in room-temperature clocks and that van der Waals interactions produce the cold-atom background-gas shift. General considerations allow the loss of the Ramsey fringe amplitude to bound this frequency shift.

Gibble, Kurt

2013-05-01

52

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

53

Verification survey of the hot cell facility site, General Atomics, San Diego, California  

SciTech Connect

From 1958, General Atomics maintain a hot cell facility in support of government-funded research into reactor fuels. As the use of the facility declined, General Atomics entered into an agreement with DOE to dismantle the facility and decontaminate and decommission (D&D) the site so that it could made available for unrestricted use. The Environmental Survey and Site Assessment Program (ESSAP) was requested to verify the final radiological status of the D&D effort. This is the report of ESSAP survey and verification activities conducted at the San Diego site from November 1999 through March 2000.

Adams, W. C.

2000-06-30

54

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

55

Distribution of Reaction Products. VI. Hot-Atom Reactions, T + HR  

Microsoft Academic Search

A three-atom model has been employed in a first study of the dynamics of the reactions of hot tritium with hydrogen-containing organic molecules, e.g., T + CH4. After exploring many extended-LondonEyringPolanyiSato (LEPS) potential-energy hypersurfaces of the type introduced in Part II, a surface was obtained which was in qualitative accord with experiment in that it predicted predominantly abstraction at the

P. J. Kuntz; E. M. Nemeth; J. C. Polanyi; W. H. Wong

1970-01-01

56

Nearest-neighbor atom interference effect on bound-free opacity of hot dense gold plasma  

NASA Astrophysics Data System (ADS)

Quantum interference, similar to Young double-slit interference, takes place between the photoionization processes of two same kind atoms when the nuclei separation is less than or comparable to the de Broglie wavelength of the ionized electrons. In dense plasma, the average nearest-neighbor atom distance maybe comparable to or even less than the wavelength of the outgoing electrons, the photoionization cross section of the atoms as well as the opacity of the plasma will be affected by this kind of interferences among atoms. In the present work, we first attain the nearest-neighbor distributions of the atoms in hot dense plasmas by performing an average-atom molecular dynamics (AAMD) simulation. Then, the effective total photoionization cross section is obtained by integrating the two atom interference effects over the nearest-neighbor distributions. At last, the bound-free and Rosseland mean opacities of Au plasmas at 100 eV and different densities show that the interference effects are considerable when the density is larger than 1 g/cm3.

Hou, Yong; Wu, Jianhua; Yuan, Jianmin

2013-03-01

57

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

58

Physics and chemistry in the process of hot-wire deposition of thin film silicon  

NASA Astrophysics Data System (ADS)

Hotwire Chemical Vapor Deposition (CVD) has been used in preparing high quality low hydrogen content hydrogenated amorphous or polycrystalline silicon thin film in recent years. Comparing to the most commonly used glow discharge method, Hotwire CVD has the potential of high speed deposition avoiding the damage caused by ion bombardment associated with plasma. Although device quality thin films have been prepared by this method, and some empirical optimized deposition conditions have been established, the mechanisms controlling this technique are not clear. A homebuild threshold ionization mass spectrometer was constructed in this lab, allowing the radicals to be observed with high sensitivity. Hydrogen dissociation on the hot metal surface was studied first both by the direct detection of hydrogen atoms from the hot surface and the temperature change due to the hydrogen dissociation, it was confirmed that the activation energy of this process is around 2.25eV, the same as the dissociation in the gas phase. Further, we observed a first order dependence of hydrogen dissociation probability on the hydrogen pressure. This observation contradicts previously reported models of second order desorption. The monosilicon radicals Si and SiH3 were observed. It was observed that the silane decomposition on the hot surface is mainly a function of filament temperature, but the species released from that surface also depend on the surface condition, and thus on the silane exposure history of that piece of filament. Si is believed to deteriorate the film quality, by comparing the depleted silane and the Si flux, it is observed that Si experienced a lot of gas phase reactions before reaching the substrate, which leads to less reactive precursors. This observation is consistence with Molenbroek's study on the optimization of deposition condition. The dominant disilicon radical is identified as Si2H2, which in the form of lowest energy isomer, is suppose to be much less reactive than Si, and thus contributes to good quality thin film deposition. The corresponding Si insert reaction Si + SiH4 was also studied and an effective reaction coefficient of KSeff = 5 x 10-12( cm3/s was established.

Zheng, Wengang

59

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

60

Heavy-metal, extreme chemistry and puzzling pulsation: ultraviolet clues to the formation of hot subdwarfs  

NASA Astrophysics Data System (ADS)

Subdwarf B stars are low-mass core-helium burning stars with a very thin hydrogen envelope; in most cases, surface helium and light elements are depleted, heavy elements are enhanced by a factor ten. It is argued that normal He-poor sdB stars evolve from giants which have been stripped almost to the core to reveal helium-enriched material. As the star ignites helium and contracts to the extreme horizontal branch, radiative processes re-stratify the internal chemistry of the atmosphere and the helium sinks. When does this happen, how long does it take, and what does it look like? A small number of sdB stars have intermediate helium abundances (He-sdB) and a few have extraordinary surface compositions. The pulsating "zirconium" star LS IV-14 116 shows a four dex overabundance of zirconium, yttrium and strontium. Two other He-sdBs show a four dex overabundace of lead. Such stars are almost completely unexplored in the space ultraviolet.We will observe the ultraviolet spectrum of LS IV-14 116 and two other chemically peculiar hot subdwarfs in order to determine:(a) the impact of extraordinary composition on their overall flux distribution and hence on measurements of their effective temperatures,(b) the degree of stratification in the atmosphere (how thick is the enhanced layer?), and(c) the abundances of species not observable in the visible.(d) the ultraviolet lightcurve due to the principle pulsation modes of LS IV-14 116.The observations will allow us to explore the processes that lead to heavily stratified atmospheres and to the transformation of red giants with helium-enriched surface into horizontal-branch stars with helium-poor surfaces.

Jeffery, C.

2014-10-01

61

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

62

Demystifying Introductory Chemistry. Part 4: An Approach to Reaction Thermodynamics through Enthalpies, Entropies, and Free Energies of Atomization.  

ERIC Educational Resources Information Center

Presents an alternative approach to teaching reaction thermodynamics in introductory chemistry courses using calculations of enthalpies, entropies, and free energies of atomization. Uses a consistent concept, that of decomposition of a compound to its gaseous atoms, to discuss not only thermodynamic parameters but also equilibrium and

Spencer, James N.; And Others

1996-01-01

63

Quantitative Chemical Imaging of Atomic-Scale Chemistry Changes at Interfaces Research Team: Nigel Browning, Hao Yang  

E-print Network

Quantitative Chemical Imaging of Atomic-Scale Chemistry Changes at Interfaces Research Team: Nigel method to quantify atomic-scale changes in structure, composition, and bonding that occur at interfaces Make use of advanced capabilities for chemical imaging under varied environmental conditions afforded

64

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

65

Chemistry  

NSDL National Science Digital Library

Finds ChemEd DL resources related to the sections of the General Chemistry textbook, Chemistry, by Kenneth W. Whitten, Raymond E. Davis, M. Larry Peck, George G. Stanley published by Brooks/Cole, 2010.

66

The atmospheric chemistry of methyl salicylatereactions with atomic chlorine and with ozone  

NASA Astrophysics Data System (ADS)

Methyl salicylate is one of a number of semiochemicals, signal molecules, emitted by herbivore-infested plants. These signal molecules attract predators of the herbivore, and the chemicals thus act indirectly as part of the defence mechanism of the plant. Previous studies have shown that ozone damage to plants can also elicit the emission of signal molecules. The fate of these signal molecules in the atmosphere is not known. Preliminary studies have been undertaken to examine the atmospheric chemistry of methyl salicylate for the first time. Rate coefficients for the reaction of methyl salicylate with atomic chlorine and with ozone have been determined; the values are (2.80.3)10 -12 and 410 -21 cm 3 molecule -1 s -1. These results suggest that neither reaction with atomic chlorine nor reaction with ozone will provide important loss routes for methyl salicylate in the atmosphere. The possible importance of photolysis of methyl salicylate in the atmosphere is considered.

Canosa-Mas, Carlos E.; Duffy, Justin M.; King, Martin D.; Thompson, Katherine C.; Wayne, Richard P.

67

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

68

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

69

Excitation of atomic nuclei in hot plasma through resonance inverse electron bridge  

NASA Astrophysics Data System (ADS)

A process of nucleus excitation by photons under the mechanism of the inverse electron bridge (IEB) is examined provided the energies of atomic and nuclear transitions coincide. It is shown that in this case, the excitation of nuclei with EL[ML] transition with the energy ?N?10keV is strengthened relative to the process of photoabsorption by nucleus by a factor of 1/(?Nr0)2(L +2) [e4/(?Nr0)2(L+2)], where r0 is a typical size of domain in the ion shell for accumulation of electronic integrals. In the Rb84 nuclei the IEB cross section for the 3.4 keV M1 transition 6-(463.59 keV) ?5-(463.59keV ) can exceed even a photoexcitation cross section for the 3.4keVE1 transition with the reduced probability in the Weisskopf model BW .u.(E1)=1. This result can be important for understanding the mechanisms of atomic nucleus excitation in hot plasma. In particular, the considered process is capable to provide the existence of so called gamma luminescence wave or a nuclear isomer "burning" wavean analog of self-maintaining process of triggered depopulation of nuclear isomer.

Tkalya, E. V.; Akhrameev, E. V.; Arutyunyan, R. V.; Bol'shov, L. A.; Kondratenko, P. S.

2014-09-01

70

Diffusive grain-surface chemistry involving the atoms and diatomic molecules of two elements  

E-print Network

A model of the grain surface chemistry involving the accretion of atoms of two different elements, X and Y, and their reactions to form species X_2, XY, and Y_2 was examined for a wide range of choices for the values of its three free parameters - the accretion rate of X and Y, the desorption rate of X and the grain surface sweeping time of Y, all considered relative to the grain surface sweeping rate of X. Relative production rates of the diatomics were calculated with five methods involving, respectively, a high-order truncation of the master equation, a low-order truncation of the master equation, the standard deterministic rate equation approach, a modified rate equation approach and a set of approximations which are in some cases appropriate for accretion dominated chemistry. The accuracies of the relative production rates calculated with the different methods were assessed for the wide range of model parameters. The more accurate of the low-truncation master equation calculations and the standard deterministic rate equation approach gives results which are in most cases within ten or twenty per cent of the results given by the high-truncation master equation calculations. For many cases, the more accurate of the low order truncation and the standard deterministic rate equation approaches is indicated by a consideration of the average number of atoms of the two species on the grain's surface.

J. G. L. Rae; N. J. B. Green; T. W. Hartquist; M. J. Pilling; T. Toniazzo

2003-03-31

71

Chemistry Notes  

ERIC Educational Resources Information Center

Twelve new chemistry expermiments are described. Broad areas covered include atomic structure, solubility, gaseous diffusion, endothermic reactions, alcohols, equilibrium, atomic volumes, and some improvised apparatus. (PS)

School Science Review, 1972

1972-01-01

72

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

Microsoft Academic Search

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

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

2010-01-01

73

Breakdown into nanoscale of graphene oxide: Confined hot spot atomic reduction and fragmentation  

NASA Astrophysics Data System (ADS)

Nano-graphene oxide (nano-GO) is a new class of carbon based materials being proposed for biomedical applications due to its small size, intrinsic optical properties, large specific surface area, and easy to functionalize. To fully exploit nano-GO properties, a reproducible method for its production is of utmost importance. Herein we report, the study of the sequential fracture of GO sheets onto nano-GO with controllable lateral width, by a simple, and reproducible method based on a mechanism that we describe as a confined hot spot atomic fragmentation/reduction of GO promoted by ultrasonication. The chemical and structural changes on GO structure during the breakage were monitored by XPS, FTIR, Raman and HRTEM. We found that GO sheets starts breaking from the defects region and in a second phase through the disruption of carbon bonds while still maintaining crystalline carbon domains. The breaking of GO is accompanied by its own reduction, essentially by the elimination of carboxylic and carbonyl functional groups. Photoluminescence and photothermal studies using this nano-GO are also presented highlighting the potential of this nanomaterial as a unique imaging/therapy platform.

Gonalves, Gil; Vila, Mercedes; Bdikin, Igor; de Andrs, Alicia; Emami, Nazanin; Ferreira, Rute A. S.; Carlos, Lus D.; Grcio, Jos; Marques, Paula A. A. P.

2014-10-01

74

Breakdown into nanoscale of graphene oxide: Confined hot spot atomic reduction and fragmentation.  

PubMed

Nano-graphene oxide (nano-GO) is a new class of carbon based materials being proposed for biomedical applications due to its small size, intrinsic optical properties, large specific surface area, and easy to functionalize. To fully exploit nano-GO properties, a reproducible method for its production is of utmost importance. Herein we report, the study of the sequential fracture of GO sheets onto nano-GO with controllable lateral width, by a simple, and reproducible method based on a mechanism that we describe as a confined hot spot atomic fragmentation/reduction of GO promoted by ultrasonication. The chemical and structural changes on GO structure during the breakage were monitored by XPS, FTIR, Raman and HRTEM. We found that GO sheets starts breaking from the defects region and in a second phase through the disruption of carbon bonds while still maintaining crystalline carbon domains. The breaking of GO is accompanied by its own reduction, essentially by the elimination of carboxylic and carbonyl functional groups. Photoluminescence and photothermal studies using this nano-GO are also presented highlighting the potential of this nanomaterial as a unique imaging/therapy platform. PMID:25339424

Gonalves, Gil; Vila, Mercedes; Bdikin, Igor; de Andrs, Alicia; Emami, Nazanin; Ferreira, Rute A S; Carlos, Lus D; Grcio, Jos; Marques, Paula A A P

2014-01-01

75

Breakdown into nanoscale of graphene oxide: Confined hot spot atomic reduction and fragmentation  

PubMed Central

Nano-graphene oxide (nano-GO) is a new class of carbon based materials being proposed for biomedical applications due to its small size, intrinsic optical properties, large specific surface area, and easy to functionalize. To fully exploit nano-GO properties, a reproducible method for its production is of utmost importance. Herein we report, the study of the sequential fracture of GO sheets onto nano-GO with controllable lateral width, by a simple, and reproducible method based on a mechanism that we describe as a confined hot spot atomic fragmentation/reduction of GO promoted by ultrasonication. The chemical and structural changes on GO structure during the breakage were monitored by XPS, FTIR, Raman and HRTEM. We found that GO sheets starts breaking from the defects region and in a second phase through the disruption of carbon bonds while still maintaining crystalline carbon domains. The breaking of GO is accompanied by its own reduction, essentially by the elimination of carboxylic and carbonyl functional groups. Photoluminescence and photothermal studies using this nano-GO are also presented highlighting the potential of this nanomaterial as a unique imaging/therapy platform. PMID:25339424

Goncalves, Gil; Vila, Mercedes; Bdikin, Igor; de Andres, Alicia; Emami, Nazanin; Ferreira, Rute A. S.; Carlos, Luis D.; Gracio, Jose; Marques, Paula A. A. P.

2014-01-01

76

Diffusive grain-surface chemistry involving the atoms and diatomic molecules of two elements  

E-print Network

A model of the grain surface chemistry involving the accretion of atoms of two different elements, X and Y, and their reactions to form species X_2, XY, and Y_2 was examined for a wide range of choices for the values of its three free parameters - the accretion rate of X and Y, the desorption rate of X and the grain surface sweeping time of Y, all considered relative to the grain surface sweeping rate of X. Relative production rates of the diatomics were calculated with five methods involving, respectively, a high-order truncation of the master equation, a low-order truncation of the master equation, the standard deterministic rate equation approach, a modified rate equation approach and a set of approximations which are in some cases appropriate for accretion dominated chemistry. The accuracies of the relative production rates calculated with the different methods were assessed for the wide range of model parameters. The more accurate of the low-truncation master equation calculations and the standard determ...

Rae, J G L; Hartquist, T W; Pilling, M J; Toniazzo, T

2003-01-01

77

The chemistry of sodium chloride involvement in processes related to hot corrosion  

NASA Technical Reports Server (NTRS)

Sodium chloride is one of the primary contaminants that enter gas turbine engines and contribute, either directly or indirectly, to the hot corrosion degradation of hot-gas-path components. The paper surveys the results of laboratory experiments along with thermodynamic and mass transport calculations, intended for elucidating the behavior of sodium chloride in combustion environments. It is shown that besides being a source of sodium for the formation of corrosive liquid Na2SO4, the NaCl itself contributes in other indirect ways to the material degradation associated with the high-temperature environmental attack. In addition, the experimental results lend credence to the conceptual scheme presented schematically (behavior of NaCl in a turbine engine combustion gas environment) and resolve conflicting aspects of relevant NaCl misconceptions.

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

1979-01-01

78

Use of a PhET Interactive Simulation in General Chemistry Laboratory: Models of the Hydrogen Atom  

ERIC Educational Resources Information Center

An activity supporting the PhET interactive simulation, Models of the Hydrogen Atom, has been designed and used in the laboratory portion of a general chemistry course. This article describes the framework used to successfully accomplish implementation on a large scale. The activity guides students through a comparison and analysis of the six

Clark, Ted M.; Chamberlain, Julia M.

2014-01-01

79

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

80

Laboratory studies on tropospheric iodine chemistry: bridging the atomic, molecular and particle scale  

NASA Astrophysics Data System (ADS)

High mixing ratios of the iodine oxides IO and OIO have been observed in the polar, mid-latitude and tropical marine boundary layer (MBL). The impact of the iodine chemistry on the oxidizing capacity of the MBL is well documented. Moreover, there is evidence showing that the bursts of new particles measured in coastal regions are produced by the biogenic emission of iodine containing precursors, followed by the photochemical production and condensation of iodine oxide vapours. Airborne measurements of particle growth rates show that these particles can reach significant sizes where they can contribute to the regional aerosol loading, thus suggesting a potential impact on climate on a regional or global scale. Within the frame of the INSPECT project (INorganic Secondary Particle Evolution, Chemistry and Transport) we wish to understand at a fundamental level the tendency for the iodine oxides formed from IO and OIO recombination to condense into particles. Elemental analysis of iodine oxide particles (IOP) made in the laboratory shows that they have the empirical formula I2O5. The major question is how this happens: through formation of I2O5 in the gas phase, followed by polymerization, or by condensation of various IxOy to form amorphous iodine oxides, which subsequently rearrange to I2O5. We are studying the gas phase photochemistry leading to nucleation of IOP, their growth kinetics, aspects of their heterogeneous chemistry, and their properties as ice condensation nuclei. In order to bridge the molecular and the particle scales, a wide variety of techniques are being used, including CRDS, ARAS, LIF, UV-VIS spectroscopy, PI-TOF-MS and mobility particle size scanning. The results obtained so far provide new and interesting insights to the problem. From the gas phase point of view, a unit iodine atom quantum yield from OIO photolysis has been now established across its strong visible spectral bands. This result implies a short lifetime of OIO and explains why in general it could not be observed during daytime in the field. This is also consistent with recently observed ozone depletion events possibly correlated to high concentrations of IO. On the other hand, atmospheric modelling shows that the rate of formation of condensable iodine vapours decreases when a high OIO photolysis rate is considered, although the modelled values are still consistent with the rates of particle formation observed in the MBL. On the particle scale, the role of water and sulphuric acid vapour uptake on the formation and growth of IOP has been studied by analysis of the observed changes to measured particle size distribution data. In the case of water, hygroscopic growth factors have been determined at different ambient relative humidities, while for H2SO4 the uptake coefficient onto IOP has been evaluated. The experimental data suggests the possibility of a ternary nucleation route involving iodine oxide-water-acid vapours. Currently, pulsed laser photolysis coupled to PI-TOF-MS is being used to study the transition regime between the gas and particle phase. With this technique it is possible to resolve small clusters up to 1200 amu with sufficient resolution to determine, e.g., whether I2O4 or I2O5 is the condensable unit of IOP.

Gomez Martin, J.; Saunders, R. W.; Blitz, M. A.; Mahajan, A. S.; Plane, J. M.

2008-12-01

81

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

82

Doing Chemistry  

NSDL National Science Digital Library

This website includes over 150 chemistry experiments in the following areas: Atomic Structure, Bonding, Chemical Reactions, Colligative Properties, Condensed States, Electrochemistry, Equilibrium Gases, Instrumentation, Limiting Reactant and more.

Brooks, David W.

2010-05-25

83

Ultra-Slow Light and Enhanced Nonlinear Optical Effects in a Coherently Driven Hot Atomic Gas  

E-print Network

We report the observation of small group velocities of order 90 meters per second, and large group delays of greater than 0.26 ms, in an optically dense hot rubidium gas (~360 K). Media of this kind yield strong nonlinear interactions between very weak optical fields, and very sharp spectral features. The result is in agreement with previous studies on nonlinear spectroscopy of dense coherent media.

Michael M. Kash; Vladimir A. Sautenkov; Alexander S. Zibrov; L. Hollberg; George R. Welch; Mikhail D. Lukin; Yuri Rostovtsev; Edward S. Fry; Marlan O. Scully

1999-04-07

84

Atomic-scale control of TiO6 octahedra through solution chemistry towards giant dielectric response  

NASA Astrophysics Data System (ADS)

The structures of many important functional oxides contain networks of metal-oxygen polyhedral units i.e. MOn. The correlation between the configurations and connectivities of these MOn to properties is essentially important to be well established to conduct the design, synthesis and application of new MOn-based functional materials. In this paper, we report on an atomic-scale solution-chemistry approach that for the first time enables TiO6 octahedral network control starting from metastable brookite TiO2 through simultaneously tuning pH values and interfering ions (Fe3+, Sc3+, and Sm3+). The relationship between solution chemistry and the resultant configuration/connectivity of TiO6 octahedra in TiO2 and lepidocrocite titanate is mapped out. Apart from differing crystalline phases and morphologies, atomic-scale TiO6 octahedral control also endows numerous defect dipoles for giant dielectric responses. The structural and property evolutions are well interpreted by the associated H+/OH- species in solution and/or defect states associated with Fe3+ occupation within TiO6 octahedra. This work therefore provides fundamental new insights into controlling TiO6 octahedral arrangement essential for atomic-scale structure-property design.

Hu, Wanbiao; Li, Liping; Li, Guangshe; Liu, Yun; Withers, Ray L.

2014-10-01

85

Atomic-scale control of TiO6 octahedra through solution chemistry towards giant dielectric response.  

PubMed

The structures of many important functional oxides contain networks of metal-oxygen polyhedral units i.e. MOn. The correlation between the configurations and connectivities of these MOn to properties is essentially important to be well established to conduct the design, synthesis and application of new MOn-based functional materials. In this paper, we report on an atomic-scale solution-chemistry approach that for the first time enables TiO6 octahedral network control starting from metastable brookite TiO2 through simultaneously tuning pH values and interfering ions (Fe(3+), Sc(3+), and Sm(3+)). The relationship between solution chemistry and the resultant configuration/connectivity of TiO6 octahedra in TiO2 and lepidocrocite titanate is mapped out. Apart from differing crystalline phases and morphologies, atomic-scale TiO6 octahedral control also endows numerous defect dipoles for giant dielectric responses. The structural and property evolutions are well interpreted by the associated H(+)/OH(-) species in solution and/or defect states associated with Fe(3+) occupation within TiO6 octahedra. This work therefore provides fundamental new insights into controlling TiO6 octahedral arrangement essential for atomic-scale structure-property design. PMID:25301286

Hu, Wanbiao; Li, Liping; Li, Guangshe; Liu, Yun; Withers, Ray L

2014-01-01

86

Atomic-scale control of TiO6 octahedra through solution chemistry towards giant dielectric response  

PubMed Central

The structures of many important functional oxides contain networks of metal-oxygen polyhedral units i.e. MOn. The correlation between the configurations and connectivities of these MOn to properties is essentially important to be well established to conduct the design, synthesis and application of new MOn-based functional materials. In this paper, we report on an atomic-scale solution-chemistry approach that for the first time enables TiO6 octahedral network control starting from metastable brookite TiO2 through simultaneously tuning pH values and interfering ions (Fe3+, Sc3+, and Sm3+). The relationship between solution chemistry and the resultant configuration/connectivity of TiO6 octahedra in TiO2 and lepidocrocite titanate is mapped out. Apart from differing crystalline phases and morphologies, atomic-scale TiO6 octahedral control also endows numerous defect dipoles for giant dielectric responses. The structural and property evolutions are well interpreted by the associated H+/OH? species in solution and/or defect states associated with Fe3+ occupation within TiO6 octahedra. This work therefore provides fundamental new insights into controlling TiO6 octahedral arrangement essential for atomic-scale structure-property design. PMID:25301286

Hu, Wanbiao; Li, Liping; Li, Guangshe; Liu, Yun; Withers, Ray L.

2014-01-01

87

Thomas{endash}Fermi-like and average atom models for dense and hot matter  

SciTech Connect

All the Thomas{endash}Fermi approaches to the thermodynamics and atomic physics properties of dense and ionized matter consisting of a single element are systematically derived and compared within a density-functional theoretical framework. The corresponding results are contrasted to those of the average atom model by using similar approximations for exchange, correlation, and gradient corrections. Emphasis is led on equations of state, ionization, level shifts, and radial moments. The same numerical algorithms are used to unravel similar trends or identify specific ones, in terms of density and temperature variations. The most sophisticated Thomas{endash}Fermi{endash}Dirac{endash}Weiz{umlt a}cker method yields the closest results to the hybrid average atom model using quantized bound states. Parameters ranges of potential interest for inertially confined thermonuclear fusion stress out density in the 0.1{endash}10 times the solid, and temperature up to 10 keV. {copyright} {ital 1996 American Institute of Physics.}

Fromy, P.; Deutsch, C.; Maynard, G. [Laboratoire de Physique des Gaz et Plasmas (Associe au CNRS), Bat. 212, Universite Paris XI, 91405 Orsay (France)] [Laboratoire de Physique des Gaz et Plasmas (Associe au CNRS), Bat. 212, Universite Paris XI, 91405 Orsay (France)

1996-03-01

88

Competition of silene/silylene chemistry with free radical chain reactions using 1-methylsilacyclobutane in the hot-wire chemical vapor deposition process.  

PubMed

The gas-phase reaction chemistry of using 1-methylsilacyclobutane (MSCB) in the hot-wire chemical vapor deposition (CVD) process has been investigated by studying the decomposition of MSCB on a heated tungsten filament and subsequent gas-phase reactions in a reactor. Three pathways exist to decompose MSCB on the filament to form ethene/methylsilene, propene/methylsilylene, and methyl radicals. The activation energies for forming propene and methyl radical, respectively, are determined to be 68.7 1.3 and 46.7 2.5 kJmol(-1), which demonstrates the catalytic nature of the decomposition. The secondary gas-phase reactions in the hot-wire CVD reactor are characterized by the competition between a free radical chain reaction and the cycloaddition of silene reactive species produced either from the primary decomposition of MSCB on the filament or the isomerization of silylene species. At lower filament temperatures of 1000-1100 C and short reaction time (t ? 15 min), the free radical chain reaction is equally important as the silene chemistry. With increasing filament temperature and reaction time, silene chemistry predominates. PMID:22934960

Badran, I; Forster, T D; Roesler, R; Shi, Y J

2012-10-18

89

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

90

The role of electronic excitation in ultracold atom-ion chemistry  

NASA Astrophysics Data System (ADS)

The role of electronic excitation in chemical reactions between ultracold Ca atoms and Ba^+ ions confined in a hybrid trap is studied. This prototypical system is energetically precluded from reacting in its ground state, allowing a particularly simple interpretation of the data. It is found that while electronic excitation of the ion can critically influence the chemical reaction rate, electronic excitation in the neutral atom is relatively unimportant. It is experimentally demonstrated that with the correct choice of the atom-ion pair it is possible to mitigate the unwanted effects of these chemical reactions in ultracold atom-ion environments, marking a crucial step towards the next generation of hybrid devices.

Sullivan, Scott; Rellergert, Wade; Kotochigova, Svetlana; Hudson, Eric

2012-06-01

91

The Atomic and Molecular Universe: Collisions in Hot Plasmas to the Building Blocks of Life  

NASA Astrophysics Data System (ADS)

Basic atomic and molecular collision phenomena are operative at the core of an enormous range of astrophysical plasmas, including the interstellar medium (ISM), protostellar regions, stars, our Sun, and planetary atmospheres, ionospheres, & magnetospheres. Laboratory measurements of cross sections and lifetimes are needed to establish plasma charge-state distributions. A required database includes absolute electron- impact excitation, ionization, and recombination cross sections in highly-charged ions (HCIs); photoionization cross sections; and absolute single- and multiple charge-exchange cross sections between a neutral target and an HCI, as when a solar/stellar wind meets a circumstellar cloud or passing comet to generate X- rays via charge exchange. Since satellites and spacecraft often detect photons from the astronomical object, the infrared-to-X- ray emissions are governed by a balance between collisional excitation and radiative decay, so that accurate lifetimes, branching fractions, and Einstein A and B coefficients are also needed. On yet another level, observations in the infrared-to- millimeter wave region from, for example, the Green Bank Telescope, Spitzer, Sofia, Herschel, and the James Webb Telescope provide information on molecular formation in the ISM and protostellar regions. Over 144 atomic, molecular, and ionic species have been identified to date. Recent laboratory results will be given on formation of some of these polyatomic molecules in superthermal, ground-state H- and O-atom collisions with simple, grain-adsorbed species, and results compared to the impressive array of space spectroscopic data.

Chutjian, Ara

2010-03-01

92

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

93

Laboratory studies on tropospheric iodine chemistry: bridging the atomic, molecular and particle scale  

Microsoft Academic Search

High mixing ratios of the iodine oxides IO and OIO have been observed in the polar, mid-latitude and tropical marine boundary layer (MBL). The impact of the iodine chemistry on the oxidizing capacity of the MBL is well documented. Moreover, there is evidence showing that the bursts of new particles measured in coastal regions are produced by the biogenic emission

J. Gomez Martin; R. W. Saunders; M. A. Blitz; A. S. Mahajan; J. M. Plane

2008-01-01

94

Determination of Mercury in Milk by Cold Vapor Atomic Fluorescence: A Green Analytical Chemistry Laboratory Experiment  

ERIC Educational Resources Information Center

Green analytical chemistry principles were introduced to undergraduate students in a laboratory experiment focused on determining the mercury concentration in cow and goat milk. In addition to traditional goals, such as accuracy, precision, sensitivity, and limits of detection in method selection and development, attention was paid to the

Armenta, Sergio; de la Guardia, Miguel

2011-01-01

95

Photon pair production from a hot atomic ensemble in the diamond configuration  

NASA Astrophysics Data System (ADS)

This thesis discusses four-wave mixing (4WM) in a warm ensemble of rubidium using the diamond configuration level structure. Both classical 4WM and nonclassical photon-pair production are investigated. Quantum information science has spawned a great amount of experimental work on the interaction of light with collective modes of excitation in atomic ensembles. Plans to build quantum networks and quantum repeaters with atom ensembles take advantage of nonlinear interactions to produce and store non-classical states of light. These technologies will require photon sources that not only generate nonclassical light, but also resonant, narrow band light. Here we investigate a system which could be used as such a source. We take advantage of the 4WM interaction in a warm ensemble of Rubidium atoms. Our scheme utilizes the diamond energy level configuration which, in rubidium, allows for correlated pairs at telecommunications wavelengths. We start by examining the properties of classical 4WM in the system. We measure the resonance structure and see that it can be understood in terms of velocity class selective resonant enhancement and power splitting effects. The efficiency of the process is low and limited by linear absorption of the pumps. Our observations agree with a semi-classical Maxwell-Bloch theoretical treatment. Next we observe pair generation by spontaneous 4WM from the warm ensemble. The temporal profile of the cross-correlation function (CCF) for the photons depends on pump-laser power and detuning. This allows us to produce biphotons with controllable spectra. A simple quantum optical theoretical treatment based on linear filtering gives qualitative agreement with the data. We show that the photon pairs are polarization entangled, clearly violating Bell's Inequality. A perturbative quantum optical treatment predicts the polarization state of the pairs and agrees with our measurements. We analyze the photon statistics of the source and find the largest violation of the two beam Cauchy-Schwarz inequality from a warm atomic source yet. We cast the system as a heralded single photon source at telecommunications wavelengths and see that it is competitive with other systems in terms of spectral brightness.

Willis, Richard Thomas

96

From {sup 3}He{at}C{sub 60} to {sup 3}H{at}C{sub 60}: Hot-atom incorporation of tritium in C{sub 60}  

SciTech Connect

The introduction of tritium into the cavity of C{sub 60} using hot-atom chemistry was studied. Neutron irradiation of {sup 3}He in {sup 3}He{at}C{sub 60} produced tritium ions and atoms which enter the C{sub 60}. {sup 3}H{at}C{sub 60} was detected with a scintillation counter. The Bingel reaction was carried out on this material under conditions so that the monoadduct formed predominantly, and the products were probed for tritium activity. Analysis with {sup 3}He NMR gave a peak with the characteristic {sup 3}He shift for the malonate product. The product fractions gave only 33% of the original activity; most was recovered in the unreacted C{sub 60} portion. No reaction was observed between C{sub 60} and the stable radical di-tert-butylnitroxide; all tritium activity was recovered in the C{sub 60} peak. These results suggest similarities in properties between {sup 3}H{at}C{sub 60} and pure C{sub 60}, implying that the tritium exists as a free atom inside the molecule.

Khong, A.; Cross, R.J.; Saunders, M.

2000-05-04

97

High Metallicity and Non-Equilibrium Chemistry in the Dayside Atmosphere of Hot-Neptune Gj 436b  

E-print Network

We present a detailed analysis of the dayside atmosphere of the hot-Neptune GJ 436b, based on recent Spitzer observations. We report statistical constraints on the thermal and chemical properties of the planetary atmosphere, ...

Madhusudhan, Nikku

98

Deep Atomic Binding (DAB) Hypothesis: A New Approach of Fission Product Chemistry  

SciTech Connect

Former studies assumed that, after fission process occurs, the highly ionized new born atoms (20-22 positive charge), ionize the media in which they pass through before becoming stable atoms in a manner similar to 4-MeV ?-particles. Via ordinary chemical reactions with the surroundings, each stable atom has a probability to form chemical compound. Since there are about 35 different elemental atoms created through fission processes, a large number of chemical species were suggested to be formed. But, these suggested chemical species were not found in the environment after actual releases of FP during accidents like TMI (USA, 1979), and Chernobyl (former USSR, 1986), also the models based on these suggested reactions and species could not interpret the behavior of these actual species. It is assumed here that the ionization states of the new born atoms and the long term high temperature were not dealt with in an appropriate way and they were the reasons of former models failure. Our new approach of Deep Atomic Binding (DAB) based on the following: 1-The new born atoms which are highly ionized, 10-12 electrons associated with each nucleus, having a large probability to create bonds between them to form molecules. These bonds are at the L, or M shells, and we call it DAB. 2-The molecules stay in the reactor at high temperatures for long periods, so they undergo many stages of composition and decomposition to form giant molecules. By applying DAB approach, field data from Chernobyl, TMI and nuclear detonations could be interpreted with a wide coincidence resulted. (author)

Ajlouni, Abdul-Wali M.S. [Ministry of Energy and Mineral Resources (Jordan)

2006-07-01

99

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

PubMed

The effect of the Si-H bond on the gas-phase reaction chemistry of trimethylsilane in the hot-wire chemical vapor deposition (HWCVD) process has been studied by examining its decomposition on a hot tungsten filament and the secondary gas-phase reactions in a reactor using a soft laser ionization source coupled with mass spectrometry. Trimethylsilane decomposes on the hot filament via Si-H and Si-CH(3) bond cleavages. A short-chain mechanism is found to dominate in the secondary reactions in the reactor. It has been shown that the hydrogen abstractions of both Si-H and C-H occur simultaneously, with the abstraction of Si-H being favored. Tetramethylsilane and hexamethyldisilane are the two major products formed from the radical recombination reactions in the termination steps. Three methyl-substituted disilacyclobutane molecules, i.e., 1,3-dimethyl-1,3-disilacyclobutane, 1,1,3-trimethyl-1,3-disilacyclobutane, and 1,1,3,3-tetramethyl-1,3-disilacyclobutane are also produced in reactor from the cycloaddition reactions of methyl-substituted silene species. Compared to tetramethylsilane and hexamethyldisilane, a common feature with trimethylsilane is that the short-chain mechanism still dominates. However, a more active involvement of the reactive silene intermediates has been found with trimethylsilane. PMID:21834557

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

2011-09-22

100

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

101

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

102

The H + OCS hot atom reaction - CO state distributions and translational energy from time-resolved infrared absorption spectroscopy  

NASA Technical Reports Server (NTRS)

Time-resolved infrared diode laser spectroscopy has been used to probe CO internal and translational excitation from the reaction of hot H atoms with OCS. Product distributions should be strongly biased toward the maximum 1.4 eV collision energy obtained from 278 nm pulsed photolysis of HI. Rotations and vibrations are both colder than predicted by statistical density of states theory, as evidenced by large positive surprisal parameters. The bias against rotation is stronger than that against vibration, with measurable population as high as v = 4. The average CO internal excitation is 1920/cm, accounting for only 13 percent of the available energy. Of the energy balance, time-resolved sub-Doppler line shape measurements show that more than 38 percent appears as relative translation of the separating CO and SH fragments. Studies of the relaxation kinetics indicate that some rotational energy transfer occurs on the time scale of our measurements, but the distributions do not relax sufficiently to alter our conclusions. Vibrational distributions are nascent, though vibrational relaxation of excited CO is unusually fast in the OCS bath, with rates approaching 3 percent of gas kinetic for v = 1.

Nickolaisen, Scott L.; Cartland, Harry E.

1993-01-01

103

Biophysical evaluation of cells on nanotubular surfaces: the effects of atomic ordering and chemistry  

PubMed Central

After the implantation of a biomaterial in the body, the first interaction occurs between the cells in contact with the biomaterial surface. Therefore, evaluating the cellsubstrate interface is crucial for designing a successful implant. In this study, the interaction of MC3T3 osteoblasts was studied on commercially pure and alloy (Ti6Al4V) Ti surfaces treated with amorphous and crystalline titanium dioxide nanotubes. The results indicated that the presence of nanotubes increased the density of osteoblast cells in comparison to bare surfaces (no nanotubes). More importantly, our finding shows that the chemistry of the substrate affects the cell density rather than the morphology of the cells. A novel approach based on the focused ion beam technique was used to investigate the biophysical cellsubstrate interaction. The analysis revealed that portions of the cells migrated inside the crystalline nanotubes. This observation was correlated with the super hydrophilic properties of the crystalline nanotubes. PMID:25143725

Shokuhfar, Tolou; Hamlekhan, Azhang; Chang, Jen-Yung; Choi, Chang Kyoung; Sukotjo, Cortino; Friedrich, Craig

2014-01-01

104

CHEMISTRY CURRICULUM SEMESTER I  

E-print Network

CHEMISTRY CURRICULUM SEMESTER ­ I Chemistry-I: Physical principles (2:1) Atomic structure-state approximation, Arrhenius equation and collision theory and catalysis. SEMESTER ­ II Chemistry-II: Structure orbital theory: polyatomic molecules - Walsh diagram; Main group chemistry: periodic properties, chemistry

Srinivasan, N.

105

Physics and chemistry of hot-wire chemical vapor deposition from silane: Measuring and modeling the silicon epitaxy deposition rate  

Microsoft Academic Search

We measure and successfully model the deposition rate (R) of epitaxial Si by hot-wire chemical vapor deposition (HWCVD) onto (100) silicon over a wide range of growth conditions. A deposition rate model based on the fundamentals of gas-filament and gas-substrate interactions is presented; the results are consistent with the observed dependences of R on gas pressure, flow, and filament area.

Ina T. Martin; Charles W. Teplin; James R. Doyle; Howard M. Branz; Paul Stradins

2010-01-01

106

Atomic resolution crystal structures and quantum chemistry meet to reveal subtleties of hydroxynitrile lyase catalysis.  

PubMed

Hydroxynitrile lyases are versatile enzymes that enantiospecifically cope with cyanohydrins, important intermediates in the production of various agrochemicals or pharmaceuticals. We determined four atomic resolution crystal structures of hydroxynitrile lyase from Hevea brasiliensis: one native and three complexes with acetone, isopropyl alcohol, and thiocyanate. We observed distinct distance changes among the active site residues related to proton shifts upon substrate binding. The combined use of crystallography and ab initio quantum chemical calculations allowed the determination of the protonation states in the enzyme active site. We show that His(235) of the catalytic triad must be protonated in order for catalysis to proceed, and we could reproduce the cyanohydrin synthesis in ab initio calculations. We also found evidence for the considerable pK(a) shifts that had been hypothesized earlier. We envision that this knowledge can be used to enhance the catalytic properties and the stability of the enzyme for industrial production of enantiomerically pure cyanohydrins. PMID:18524775

Schmidt, Andrea; Gruber, Karl; Kratky, Christoph; Lamzin, Victor S

2008-08-01

107

In situ investigation of surface chemistry for chemically driven atomic layer epitaxy of II-VI semiconductor thin films  

NASA Astrophysics Data System (ADS)

Atomic Layer Epitaxy (ALE) can provide atomic scale control of the growth of ultra thin semiconductor films. This thesis presents an overview of an in situ molecular-level study of surface chemistry for heteroepitaxy of II-VI semiconductor by using a binary reaction sequence with hydride and metalorganic precursors. The study focused primarily on developing a fundamental understanding of surface chemistry in a model material system: the growth of US on ZnSe (100). Dimethylcadmium and H2S precursors were sequentially dosed onto a c(2x2) ZnSe (100) substrate and characterization of the growth surface at each growth step was accomplished in the growth chamber under UHV conditions. The surface chemical composition was probed by Auger electron spectroscopy (AES) and low energy ion scattering spectroscopy (LEIS) and the surface order was determined by low energy electron diffraction (LEED). These measurements showed that, at a substrate temperature of 300 K, self-limiting reactions resulted in saturated chemisorption of one Cd and one S monolayer during each cycle of the binary reaction sequence, yielding the layer-by-layer growth of an ordered stoichiometric US film. We investigated surface chemistry of our model system in further detail using near edge X-ray fine structure (NEXAFS) spectroscopy and temperature programmed desorption (TPD) spectroscopy. NEXAFS and TPD results revealed that the growth surface is terminated by either a monolayer of surface methyl or hydrogen subsequent to saturation with either DMCd or H2S respectively, at 300 K. These surface terminating groups (CH3 or H) passivate the growth surface, preventing further uptake of the precursors once monolayer coverage is reached. However, surface CH3 or H is reactive to the alternative precursor, so the other constituent can be deposited subsequently. Therefore, both methyl and hydrogen termination provide satisfactory self-limiting reactions that allow the growth to proceed in a layer-by-layer manner. Heteroepitaxy of ZnS on Si(100) using a similar binary reaction sequence has also been proposed. The initial stage of our study has focused on the interactions of potential precursors with Si(100). Adsorption and desorption mechanisms of H2S on Si(100) have been investigated by using AES, TPD and LEED. The surface is saturated by 0.5 ML of H2S for all substrate exposure temperatures, i.e. -145C -425C. Desorption of hydrogen and diffusion of sulfur occur almost simultaneously after dissociative adsorption of H2S on Si(100). This process makes it impossible to form 1.0 ML of surface sulfur without a separate means of H-atom removal. Alternative approaches to initiating the growth of a II-VI semiconductor on Si(100), such as the use of a group III or group V intermediary layer, are discussed.

Han, Ming

2000-10-01

108

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

PubMed Central

Uncovering the chemical and physical links between natural environments and microbial communities is becoming increasingly amenable owing to geochemical observations and metagenomic sequencing. At the hot spring known as Bison Pool in Yellowstone National Park, the cooling of the water in the outflow channel is associated with an increase in oxidation potential estimated from multiple field-based measurements. Representative groups of proteins whose sequences were derived from metagenomic data also exhibit an increase in average oxidation state of carbon in the protein molecules with distance from the hot-spring source. The energetic requirements of reactions to form selected proteins used in the model were computed using amino-acid group additivity for the standard molal thermodynamic properties of the proteins, and the relative chemical stabilities of the proteins were investigated by varying temperature, pH and oxidation state, expressed as activity of dissolved hydrogen. The relative stabilities of the proteins were found to track the locations of the sampling sites when the calculations included a function for hydrogen activity that increases with temperature and is higher, or more reducing, than values consistent with measurements of dissolved oxygen, sulfide and oxidation-reduction potential in the field. These findings imply that spatial patterns in the amino acid compositions of proteins can be linked, through energetics of overall chemical reactions representing the formation of the proteins, to the environmental conditions at this hot spring, even if microbial cells maintain considerably different internal conditions. Further applications of the thermodynamic calculations are possible for other natural microbial ecosystems. PMID:21853048

Dick, Jeffrey M.; Shock, Everett L.

2011-01-01

109

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

PubMed

Uncovering the chemical and physical links between natural environments and microbial communities is becoming increasingly amenable owing to geochemical observations and metagenomic sequencing. At the hot spring known as Bison Pool in Yellowstone National Park, the cooling of the water in the outflow channel is associated with an increase in oxidation potential estimated from multiple field-based measurements. Representative groups of proteins whose sequences were derived from metagenomic data also exhibit an increase in average oxidation state of carbon in the protein molecules with distance from the hot-spring source. The energetic requirements of reactions to form selected proteins used in the model were computed using amino-acid group additivity for the standard molal thermodynamic properties of the proteins, and the relative chemical stabilities of the proteins were investigated by varying temperature, pH and oxidation state, expressed as activity of dissolved hydrogen. The relative stabilities of the proteins were found to track the locations of the sampling sites when the calculations included a function for hydrogen activity that increases with temperature and is higher, or more reducing, than values consistent with measurements of dissolved oxygen, sulfide and oxidation-reduction potential in the field. These findings imply that spatial patterns in the amino acid compositions of proteins can be linked, through energetics of overall chemical reactions representing the formation of the proteins, to the environmental conditions at this hot spring, even if microbial cells maintain considerably different internal conditions. Further applications of the thermodynamic calculations are possible for other natural microbial ecosystems. PMID:21853048

Dick, Jeffrey M; Shock, Everett L

2011-01-01

110

Influence of plasma chemistry on impurity incorporation in AlN prepared by plasma enhanced atomic layer deposition  

NASA Astrophysics Data System (ADS)

Impurities in aluminum nitride films prepared by plasma enhanced atomic layer deposition using NH3-, N2/H2- and N2-based plasmas are investigated by combining time-of-flight elastic recoil detection analysis (ERDA) and Fourier transform infrared spectroscopy. Different atomistic growth mechanisms are found to exist between the plasma chemistries. N2-plasma is shown as not suitable for the low-temperature deposition of AlN. Films deposited by NH3- and N2/H2-based processes are nitrogen rich and heavily hydrogenated. Carbon impurities exist at higher concentrations for the N2/H2-processes. The discovery of nitrile groups in the films indicates that carbon impurities can be partially attributed to an undesirable reaction occurring during the plasma step between nitrogen species and CH groups. Unremoved ligands from the metal precursor are the other source of carbon. A comparison of the hydrogen content within the films as determined by infrared absorption spectroscopy and ERDA suggests the NH3-based films have large quantities of unbonded hydrogen, whereas hydrogen in the N2/H2-based films is mostly in the form NHx. For the N2/H2-based processes, the addition of argon into the plasma mixture is shown to enhance amine formation.

Pyymaki Perros, Alexander; Hakola, Hanna; Sajavaara, Timo; Huhtio, Teppo; Lipsanen, Harri

2013-12-01

111

Reduction biodegradable brushed PDMAEMA derivatives synthesized by atom transfer radical polymerization and click chemistry for gene delivery.  

PubMed

Novel reducible and degradable brushed poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) derivatives were synthesized and evaluated as non-viral gene delivery vectors. First, alkyne-functionalized poly(aspartic acid) with a disulfide linker between the propargyl group and backbone poly([(propargyl carbamate)-cystamine]-?,?-aspartamide) (P(Asp-SS-AL)) was synthesized. Second, linear low molecular weight (LMW) monoazido-functionalized PDMAEMAs synthesized via atom transfer radical polymerization were conjugated to the polypeptide side-chains of P(Asp-SS-AL) via click chemistry to yield high molecular weight (HMW) polyaspartamide-based disulfide-containing brushed PDMAEMAs (PAPDEs). The PAPDEs were able to condense plasmid DNA to form 100 to 200nm polyplexes with positive ?-potentials. Moreover, in the presence of dithiothreitol the PAPDEs degraded into LMW PDAMEMA, resulting in disintegration of the PAPDE/DNA polyplexes and subsequent release of plasmid DNA. In vitro experiments revealed that the PAPDEs were less cytotoxic and more effective in gene transfection than control 25kDa poly(ethyleneimine) and HMW linear PDMAEMA. In conclusion, reducible and degradable polycations composed of LMW PDMAEMAs coupled to a polypeptide backbone via reduction-sensitive disulfide bonds are effective gene vectors with an excellent cytocompatibility. PMID:23660547

Liu, Jia; Xu, Yanglin; Yang, Qizhi; Li, Cao; Hennink, Wim E; Zhuo, Renxi; Jiang, Xulin

2013-08-01

112

Mercury chemistry in the MBL: Modeling results including Hg + halogen atom reaction rate constants  

NASA Astrophysics Data System (ADS)

The inclusion, of recently published kinetic data for the reactions between gas phase elemental Hg and halogen atoms and molecules, in a photochemical box model including aerosols of the Marine Boundary Layer (MBL), suggests that the cycling of Hg over the world's oceans may be much more dynamic than was once thought, as a direct result of halogen activation from marine aerosols. The rate of gas phase oxidation of Hg(0) in the model leads to high concentrations of gas phase oxidised Hg (Hg(II)), which is deposited to the sea surface either directly from the gas phase or indirectly via scavenging by sea salt and non-sea-salt sulphate aerosol particles and subsequent deposition. The model base run predicts Hg(II) concentrations higher than those measured in the marine atmosphere, and a lifetime for Hg(0) of a matter of days, rather than months as has been generally assumed. In light of previous measurements and the known stability of the hemispherical background concentration of Hg(0) the influence of liquid water content (the number of deliquescent aerosol droplets), cloud optical depth at the top of the boundary layer, and the Henry's Law constants for HgCl2 and HgBr2 have been investigated. In order to maintain a stable background concentration of Hg(0) a source strength (for emission from the sea, or entrainment from the free troposphere) of at least 15 ng m-2 hr-1 is required, which seems most unlikely considering results from flux chamber experiments. The model therefore either overestimates the rate of gas phase oxidation or lacks a fundamental reduction process. The evidence from studies of mercury depletion events in the Arctic troposphere lend support to the fast reaction between Hg(0) and Br containing radicals which have been included in the model, it is necessary therefore to investigate homogeneous and heterogeneous mechanisms for the reduction of Hg(II) to Hg(0) in order to explain the measured Hg(II) concentrations in the MBL and the stable hemispherical background of Hg(0).

Hedgecock, I. M.; Pirrone, N.

2003-04-01

113

Physics and chemistry of hot-wire chemical vapor deposition from silane: Measuring and modeling the silicon epitaxy deposition rate  

NASA Astrophysics Data System (ADS)

We measure and successfully model the deposition rate (R) of epitaxial Si by hot-wire chemical vapor deposition (HWCVD) onto (100) silicon over a wide range of growth conditions. A deposition rate model based on the fundamentals of gas-filament and gas-substrate interactions is presented; the results are consistent with the observed dependences of R on gas pressure, flow, and filament area. Gas-phase measurements of silane depletion allow calculation of the average radical sticking coefficient from the film deposition rate. Our findings indicate that the epitaxial deposition rate can be increased sufficiently to enable an economical epitaxial film-silicon photovoltaic tech-nology on low-cost foreign substrates. The model can be simply adapted to apply to the HWCVD of amorphous, nanocrystalline, and polycrystalline Si.

Martin, Ina T.; Teplin, Charles W.; Doyle, James R.; Branz, Howard M.; Stradins, Paul

2010-03-01

114

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

115

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

116

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

117

Laboratory studies of stratospheric bromine chemistry: Kinetics of the reactions of bromine monoxide with nitrogen dioxide and atomic oxygen  

SciTech Connect

A laser flash photolysis - long path absorption - technique has been employed to study the kinetics of the reaction BrO+NO2+M(k[sub 16]) yields products as a function of temperature (248-346 K), pressure (16-800 Torr), and buffer gas identity (N2, CF4). 351 nm photolysis of NO2/Br2/N2 mixtures generated BrO. The BrO decay in the presence of excess NO2 was followed by UV absorption at 338.3 nm. The reaction is in the falloff regime between third and second order over the entire range of conditions investigated. This is the first study where temperature dependent measurements of k[sub 16](P,T) have been reported at pressures greater than 12 Torr; hence, these results help constrain choices of k[sub 16](P,T) for use in modeling stratospheric BrO(x) chemistry. The kinetics of the important stratospheric reaction BrO+O(P-3)(k[sub 14]) yields Br+O2 in N2 buffer gas have been studied as a function of temperature (233-328 K) and pressure (25-150 Torr) using a novel dual laser flash photolysis/long path absorption/resonance fluorescence technique. 248 nm pulsed laser photolysis of Br2/O3/N2 mixtures produces O atoms in excess over Br2. After a delay sufficient for BrO to be generated, a 532 nm laser pulse photolysis a small fraction of the O3 to generate O(P-3). The decay of O(P-3) in the presence of an excess, known concentration of BrO, as determined by UV absorption at 338.3 nm and by numerical simulation, is then followed by time-resoved atomic resonance fluorescence spectroscopy. The experimental results have shown the reaction kinetics to be independent of pressure, to increase with decreasing temperature, and to be faster than suggested by the only previous (indirect) measurement. The resulting Anhenius expression for k[sub 14](T) is k[sub 14](T) = 1.64 x 10(exp -11) exp(263/T) cm(exp 3) molecule(exp-1)s(exp -1). The absolute accuracy of k[sub 14](T) at any temperature within the range studied is estimated to be +/- 25%.

Thorn, R.P.

1993-01-01

118

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

119

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

120

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

121

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

122

Chemistry touches your life every day, from the air you breathe to the food you eat. The science of chemistry examines the atomic and  

E-print Network

of pesticides in ground water as well as bisphenol-A in disposable plastic food/drink containers, synthesis/visible spectrophotometer Steady-state and time-resolved laser fluorescence spectrophotometers Atomic absorption

Miles, Will

123

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

124

Confectionary Chemistry.  

ERIC Educational Resources Information Center

Presents activities and demonstrations that enable teachers to use various types of confections as tactile experiences to spark chemistry students' interest and generate enthusiasm for learning. Presents uses of candy in teaching about atomic structure, spontaneous nuclear decay, chemical formulas, fractoluminescence, the effect of a molecular

Levine, Elise Hilf

1996-01-01

125

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

126

Nobody Can See Atoms: Science Camps Highlighting Approaches for Making Chemistry Accessible to Blind and Visually Impaired Students  

ERIC Educational Resources Information Center

Curricula for three chemistry camp experiences for blind and visually impaired (BVI) individuals that incorporated single- and multiday activities and experiments accessible to BVI students are described. Feedback on the camps from students, mentors, and instructors indicates that these events allowed BVI students, who in many cases have been

Wedler, Henry B.; Boyes, Lee; Davis, Rebecca L.; Flynn, Dan; Franz, Annaliese; Hamann, Christian S.; Harrison, Jason G.; Lodewyk, Michael W.; Milinkevich, Kristin A.; Shaw, Jared T.; Tantillo, Dean J.; Wang, Selina C.

2014-01-01

127

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

128

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

129

Energetic oxygen atoms in the polar geocorona  

NASA Astrophysics Data System (ADS)

The role of the auroral sources induced by the electron and proton precipitation in the formation of the hot oxygen corona in the polar upper atmosphere is studied. It is found that both electron precipitation through exothermic chemistry and proton precipitation through atmospheric sputtering significantly contribute to the population of the hot oxygen geocorona. It is also found that only atmospheric sputtering results in the formation of the escape flux of energetic oxygen atoms, providing an important source of heavy atoms for the magnetosphere. The exothermic chemistry induced by the electron precipitation and/or by the absorption of the solar UV radiation is operating continuously in the polar upper atmosphere and results in a steady population of the very near-Earth environment by suprathermal oxygen atoms with energies below a few eV. By contrast, atmospheric sputtering by magnetospheric protons provides a more variable contribution, strongly coupled with the cusp region. It produces the more energetic oxygen atoms that populate the external regions of the hot oxygen geocorona. The results of calculations are in a good agreement with the analysis of the low-latitude perigee Low Energy Neutral Atom (LENA) images showing that the instrument signal consists of low to medium energy (5-30 eV) oxygen atoms produced in and near the cusp region. The more energetic (>30 eV) fraction of energetic oxygen atoms produced by the ion-induced atmospheric sputtering could be responsible for the energetic neutrals observed by the instrument far away from the cusp or oval regions. The total escape flux of oxygen atoms associated with atmospheric sputtering by protons is found about 8 1023 s-1; therefore this mechanism may provide a substantial contribution to the magnetospheric oxygen population.

Shematovich, V. I.; Bisikalo, D. V.; GRard, J.-C.

2006-10-01

130

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

131

CHEMISTRY IN EVAPORATING ICES-UNEXPLORED TERRITORY  

SciTech Connect

We suggest that three-body chemistry may occur in warm high-density gas evaporating in transient co-desorption events on interstellar ices. Using a highly idealized computational model we explore the chemical conversion from simple species of the ice to more complex species containing several heavy atoms, as a function of density and of adopted three-body rate coefficients. We predict that there is a wide range of densities and rate coefficients in which a significant chemical conversion may occur. We discuss the implications of this idea for the astrochemistry of hot cores.

Cecchi-Pestellini, Cesare [INAF-Osservatorio Astronomico di Cagliari, Strada n.54, Loc. Poggio dei Pini, 09012 Capoterra (Italy); Rawlings, Jonathan M. C.; Viti, Serena; Williams, David A., E-mail: ccp@ca.astro.i, E-mail: jcr@star.ucl.ac.u, E-mail: sv@star.ucl.ac.u, E-mail: daw@star.ucl.ac.u [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2010-12-20

132

Circumstellar chemistry  

NASA Technical Reports Server (NTRS)

Recent theoretical studies of circumstellar chemistry are discussed for both red-giant and protostellar winds. The generalized photochemical model is able to account for the recently discovered silicon-bearing molecules in the prototypical, C-rich, AGB star IRC + 10216. The surprising occurrence of CO in protostellar winds that are largely atomic is interpreted to be the result of the high density and the rapid decrease of the temperature with distance that is expected for such winds.

Glassgold, A. E.; Mamon, G. A.

1991-01-01

133

Atom probe study of the carbon distribution in a hardened martensitic hot-work tool steel X38CrMoV5-1.  

PubMed

The microstructure of the hardened common hot-work tool steel X38CrMoV5-1 has been characterized by atom probe tomography with the focus on the carbon distribution. Samples quenched with technically relevant cooling parameters ? from 0.1 (30 K/s) to 12 (0.25 K/s) have been investigated. The parameter ? is an industrially commonly used exponential cooling parameter, representing the cooling time from 800 to 500 C in seconds divided with hundred. In all samples pronounced carbon segregation to dislocations and cluster formation could be observed after quenching. Carbon enriched interlath films with peak carbon levels of 6-10 at.%, which have been identified to be retained austenite by TEM, show a thickness increase with increasing ?. Therefore, the fraction of total carbon staying in the austenite grows. This carbon is not available for the tempering induced precipitation of secondary carbides in the bulk. Through all samples no segregation of any substitutional elements takes place. Charpy impact testing and fracture surface analysis of the hardened samples reveal the cooling rate induced microstructural distinctions. PMID:22391101

Lerchbacher, Christoph; Zinner, Silvia; Leitner, Harald

2012-07-01

134

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

135

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

136

Department of Chemistry & Biochemistry UCLA Chemistry, Biochemistry & Chemistry Material Science  

E-print Network

Department of Chemistry & Biochemistry UCLA Chemistry, Biochemistry & Chemistry Material Science ...........................................................................................................................................4 Chemistry & Biochemistry Undergraduate Office..............................................................................................6 Majors in Chemistry & Biochemistry

Levine, Alex J.

137

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

138

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.

139

Chemistry for Fuel Cells  

NSDL National Science Digital Library

This presentation provides a basic introduction to the chemistry involved with fuel cell technology. The material covers chemical bonds, some basic atomic properties, the Noble Gas Theory and how the chemistry of fuel cells works.This document may be downloaded in Microsoft PowerPoint file format.

2012-09-13

140

A Coupled Chemistry-emission Model for Atomic Oxygen Green and Red-doublet Emissions in the Comet C/1996 B2 Hyakutake  

NASA Astrophysics Data System (ADS)

The green (5577 ) and red-doublet (6300, 6364 ) lines are prompt emissions of metastable oxygen atoms in the 1 S and 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 H2O. A coupled chemistry-emission model is developed to study the production and loss mechanisms of the O(1 S) and O(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 H2O to the green (red) line emission is 30%-70% (60%-90%), while CO2 and CO are the next potential sources contributing 25%-50% (<5%). The ratio of the photoproduction rate of O(1 S) to O(1 D) would be around 0.03 (0.01) if H2O is the main source of oxygen lines, whereas it is ~0.6 if the parent is CO2. Our calculations suggest that the yield of O(1 S) production in the photodissociation of H2O 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

2012-03-01

141

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.

142

Ethylene oxide and acetaldehyde in hot cores  

NASA Astrophysics Data System (ADS)

Context. Ethylene oxide (c-C2H4O), and its isomer acetaldehyde (CH3CHO), are important complex organic molecules because of their potential role in the formation of amino acids. The discovery of ethylene oxide in hot cores suggests the presence of ring-shaped molecules with more than 3 carbon atoms such as furan (c-C4H4O), to which ribose, the sugar found in DNA, is closely related. Aims: Despite the fact that acetaldehyde is ubiquitous in the interstellar medium, ethylene oxide has not yet been detected in cold sources. We aim to understand the chemistry of the formation and loss of ethylene oxide in hot and cold interstellar objects (i) by including in a revised gas-grain network some recent experimental results on grain surfaces and (ii) by comparison with the chemical behaviour of its isomer, acetaldehyde. Methods: We introduce a complete chemical network for ethylene oxide using a revised gas-grain chemical model. We test the code for the case of a hot core. The model allows us to predict the gaseous and solid ethylene oxide abundances during a cooling-down phase prior to star formation and during the subsequent warm-up phase. We can therefore predict at what temperatures ethylene oxide forms on grain surfaces and at what temperature it starts to desorb into the gas phase. Results: The model reproduces the observed gaseous abundances of ethylene oxide and acetaldehyde towards high-mass star-forming regions. In addition, our results show that ethylene oxide may be present in outer and cooler regions of hot cores where its isomer has already been detected. Our new results are compared with previous results, which focused on the formation of ethylene oxide only. Conclusions: Despite their different chemical structures, the chemistry of ethylene oxide is coupled to that of acetaldehyde, suggesting that acetaldehyde may be used as a tracer for ethylene oxide towards cold cores.

Occhiogrosso, A.; Vasyunin, A.; Herbst, E.; Viti, S.; Ward, M. D.; Price, S. D.; Brown, W. A.

2014-04-01

143

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

144

How Iron-Containing Proteins Control Dioxygen Chemistry: A Detailed Atomic Level Description Via Accurate Quantum Chemical and Mixed Quantum Mechanics/Molecular Mechanics Calculations.  

SciTech Connect

Over the past several years, rapid advances in computational hardware, quantum chemical methods, and mixed quantum mechanics/molecular mechanics (QM/MM) techniques have made it possible to model accurately the interaction of ligands with metal-containing proteins at an atomic level of detail. In this paper, we describe the application of our computational methodology, based on density functional (DFT) quantum chemical methods, to two diiron-containing proteins that interact with dioxygen: methane monooxygenase (MMO) and hemerythrin (Hr). Although the active sites are structurally related, the biological function differs substantially. MMO is an enzyme found in methanotrophic bacteria and hydroxylates aliphatic C-H bonds, whereas Hr is a carrier protein for dioxygen used by a number of marine invertebrates. Quantitative descriptions of the structures and energetics of key intermediates and transition states involved in the reaction with dioxygen are provided, allowing their mechanisms to be compared and contrasted in detail. An in-depth understanding of how the chemical identity of the first ligand coordination shell, structural features, electrostatic and van der Waals interactions of more distant shells control ligand binding and reactive chemistry is provided, affording a systematic analysis of how iron-containing proteins process dioxygen. Extensive contact with experiment is made in both systems, and a remarkable degree of accuracy and robustness of the calculations is obtained from both a qualitative and quantitative perspective.

Friesner, Richard A.(Columbia University) [Columbia University; Baik, Mu-Hyun (Columbia University) [Columbia University; Gherman, Benjamin F.(Columbia University) [Columbia University; Guallar, Victor (Washington University) [Washington University; Wirstam, Maria E.(1836) [1836; Murphy, Robert B.(Schrodinger Inc) [Schrodinger Inc; Lippard, Stephen J.(Massachusetts Institute of Technology) [Massachusetts Institute of Technology

2003-03-01

145

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

146

An Introduction to Chemistry: Nuclear Chemistry  

NSDL National Science Digital Library

This cost-free resource is a chapter from a textbook on introductory chemistry, developed for learners with little background in physics or chemistry. This chapter deals with the atomic nucleus and radiation, nuclear energy, and uses of radioactive substances. It is appropriate for teachers seeking additional content knowledge, high school physics and chemistry courses, and college-level preparatory chemistry. It builds a foundation to understand the physical forces in the nucleus (electrostatic force and strong force), and explains how chemical reactions differ from nuclear reactions. Graphs and diagrams depict what happens in radioactive decay. The section on chemical nuclear equations is straightforward and comprehensible for non-scientists. This collection is part of An Introduction to Chemistry, a set of resources developed by Mark Bishop which includes two textbooks, 15 animated tutorials, downloadable Power Point presentations for teachers, concept maps, and 3D molecular models.

Bishop, Mark

147

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

148

Oxygen-Induced Restructuring of Rutile TiO(2)(110): Formation Mechanism, Atomic Models, and Influence on Surface Chemistry  

SciTech Connect

The rutile TiO{sub 2} (110) (1x1) surface is considered the prototypical ''well-defined'' system in the surface science of metal oxides. Its popularity results partly from two experimental advantages: bulk-reduced single crystals do not exhibit charging, and stoichiometric surfaces--as judged by electron spectroscopes--can be prepared reproducibly by sputtering and annealing in oxygen. We present results that show that this commonly-applied preparation procedure may result in a surface structure that is by far more complex than generally anticipated. Flat, (1x1) terminated surfaces are obtained by sputtering and annealing in ultrahigh vacuum. When re-annealed in oxygen at moderate temperatures (470 K to 660 K), irregular networks of partially-connected, pseudohexagonal rosettes (6.5 x 6 {angstrom} wide), one-unit cell wide strands, and small ({approximately} tens of {angstrom}) (1x1) islands appear. This new surface phase is formed through reaction of oxygen gas with interstitial Ti from the reduced bulk. Because it consists of an incomplete, kinetically-limited (1x1) layer, this phenomenon has been termed restructuring. We report a combined experimental and theoretical study that systematically explores this restructuring process. The influence of several parameters (annealing time, temperature, pressure, sample history, gas) on the surface morphology is investigated using STM. The surface coverage of the added phase as well as the kinetics of the restructuring process are quantified by LEIS and SSIMS measurements in combination with annealing in {sup 18}O-enriched gas. Atomic models of the essential structural elements are presented and are shown to be stable with first-principles density functional calculations. The effect of oxygen-induced restructuring on surface chemistry and its importance for TiO{sub 2} and other bulk-reduced oxide materials is briefly discussed.

Li, Min; Hebenstreit, Wilhelm; Diebold, Ulrike; Henderson, Michael A.; Jennison, Dwight R.

1999-07-07

149

UNC-Chapel Hill Chemistry Fundamentals Program  

NSDL National Science Digital Library

The course materials include readings and sample problems on mathematics and calculator use in chemistry, and provides short readings in basic and advanced concepts in chemistry, including: - Nomenclature - Atomic Structure - Stoichiometry - Acid-Base Chemistry - Kinetics - Equilibria - Redox reactions - Thermodynamics - Nuclear Chemistry

150

3.091 Introduction to Solid State Chemistry, Fall 2002  

E-print Network

Basic principles of chemistry and their application to engineering systems. The relationship between electronic structure, chemical bonding, and atomic order. Characterization of atomic arrangements in crystalline and ...

Sadoway, Donald R.

151

Surface chemistry and infrared absorbance changes during ZnO atomic layer deposition on ZrO2 and BaTiO3 particles  

NASA Astrophysics Data System (ADS)

ZnO atomic layer deposition (ALD) was achieved using sequential exposures of Zn(CH2CH3)2 and H2O on ZrO2 and BaTiO3 particles at 450 K. The surface chemistry of ZnO ALD was monitored in vacuum using Fourier transform infrared spectroscopy. The BaTiO3 and ZrO2 particles initially displayed vibrational features consistent with surface hydroxyl (-OH) groups. Zn(CH2CH3)2 exposure removed the surface hydroxyl groups and created Zn(CH2CH3)* surface species. The subsequent H2O exposure removed the Zn(CH2CH3)* surface species and produced ZnOH* surface species. Repeating the Zn(CH2CH3)2 and H2O exposures in an ABAB... reaction sequence at 450 K progressively deposited ZnO. Because ZnO is a semiconductor, the background infrared absorbance increased with the number of AB cycles during the deposition of the ZnO film. The increasing background infrared absorbance during long Zn(CH2CH3)2 exposures also revealed that the Zn(CH2CH3)2 reaction is not self-limiting. The background absorbance was modulated dramatically by the presence of ethyl (-CH2CH3) or hydroxyl (-OH) groups on the surface of the growing ZnO film. The infrared absorbance was higher with hydroxyl (-OH) groups and lower with ethyl (-CH2CH3) groups on the ZnO surface. The background absorbance changes were not linear with surface coverage. The large changes in absorbance after low reactant exposure suggested that the most reactive surface sites may be most influential in affecting the film conductance. Transmission electron microscopy (TEM) was used to examine the ZnO films deposited on the ZrO2 and BaTiO3 particles. The TEM images revealed ZrO2 and BaTiO3 particles encapsulated by conformal ZnO films. The ZnO films had a thickness of ~43 A? after 20 AB reaction cycles and ~65 A? after 30 AB reaction cycles, respectively. These TEM images are consistent with a ZnO ALD growth rate at 450 K of ~2.2 A?/AB cycle.

Ferguson, J. D.; Weimer, A. W.; George, S. M.

2005-01-01

152

A kinetic study of reactions of calcium-containing molecules with O and H atoms: implications for calcium chemistry in the upper atmosphere.  

PubMed

This paper describes the kinetic study of a number of gas-phase reactions involving neutral Ca-containing species, many of which are important for describing the chemistry of meteor-ablated calcium in the Earth's upper atmosphere. Ca atoms were produced thermally in the upstream section of a fast flow tube, and then converted to the molecular species CaO, CaO(2), CaO(3), CaCO(3) or Ca(OH)(2) by the addition of appropriate reagents. Atomic O or H was added further downstream, and both Ca and CaO were detected at the downstream end of the flow tube by laser-induced fluorescence. The following rate coefficients were determined: k(CaO + O --> Ca + O(2)) = (3.1) x 10(-10) at 300 K and (1.3) x 10(-10) at 203 K; k(CaO(2) + O --> CaO + O(2)) = (2.2) x 10(-11) at 300 K and (1.6) x 10(-11) at 203 K; k(CaO(2) + H --> products, 298 K) = (1.2 +/- 0.6) x 10(-11); k(CaCO(3) + O --> CaO(2) + CO(2), 300 K) < or = 1.0 x 10(-12); k(CaCO(3) + H--> CaOH + CO(2), 298 K) > or = 2.8 x 10(-12) and < or = 3.6 x 10(-11); k(CaO(3) + H--> CaOH + O(2), 298 K) > or = 1.7 x 10(-11); k(Ca(OH)(2) + H --> CaOH + H(2)O, 298 K) > or = 1.1 x 10(-11); k(CaOH + H --> Ca + H(2)O, 298 K) > or = 1.1x 10(-11) cm(3) molecule(-1) s(-1). The kinetics of the reactions of Ca and CaO with NO(2) and N(2)O were also studied, yielding k(Ca + NO(2) --> CaO + NO) = (2.6 +/- 0.3) x 10(-10) at 300 K and (2.0 +/- 0.3) x 10(-10) at 203 K; k(CaO + NO(2) --> CaO(2) + NO) = (8.1 +/- 2.0) x 10(-10) at 300 K and (2.9 +/- 1.0) x 10(-10) at 202 K; k(CaO + N(2)O --> CaO(2) + N(2)) = (4.2 +/- 1.7) x 10(-11) at 300 K and (2.2 +/- 1.2) x 10(-12) at 206 K; k(CaO + H(2) --> Ca + H(2)O, 300 K) = (3.4 +/- 1.3) x 10(-10) cm(3) molecule(-1) s(-1). Electronic structure calculations of the relevant potential energy surfaces were performed to interpret the experimental results, and the atmospheric implications of these measurements are then discussed. PMID:20532345

Broadley, Sarah L; Plane, John M C

2010-08-21

153

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

154

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

155

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

156

Educational Multiwavelength Atomic Emission Spectrometer  

E-print Network

Educational Multiwavelength Atomic Emission Spectrometer Alexander Y. Nazarenko* Chemistry multiwavelength emission instrument utilizing a commercial grating monochromator, a fiber optic sensor to collect visualization makes the spectrometer a useful educational tool. Key Words: Atomic emission spectroscopy; CCD

Nazarenko, Alexander

157

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

158

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

159

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

160

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

Microsoft Academic Search

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

Cronauer

2011-01-01

161

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

162

Green Chemistry  

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, green chemistry links (including conferences), and an online preview of the ACS-published book Real-World Cases in Green Chemistry are all found at the site. Five video clips on green chemistry from the standpoint of academia, industry, and small business are also featured (Windows Media Player). 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. Check back often for updates.

2002-01-01

163

Nebulizer comparison studies and their effects on plasma chemistry in inductively coupled plasma elemental atom and ion emission profiles utilizing acousto-optic tunable filter-hyperspectral imaging.  

E-print Network

?? An inductively coupled plasma acousto-optic tunable filter hyperspectral imaging (ICP-AOTF-HSI) system was used to examine multiple nebulizers with respect to strontium ionization and atomization (more)

Cherok, Courtney Alexandra

2009-01-01

164

Hot spots in ammonium nitrate  

E-print Network

existing work on the topic and found a wide range of activation energies quoted for this process. This may be due to flawed kinetic models, or to the complexity of the sequence of reactions involved in AN decomposition. 1.2 Hot spots Hot spots are regions... possible without the assistance of others. Corporately, Orica Mining Services and the Atomic Weapons Establishment envisioned and funded the project. From Orica, Ian Kirby, Jim Chan, John Cooper and Richard Goodridge all provided useful support, insight...

Taylor, Nicholas

2011-07-12

165

Atmospheric escape from hot Jupiters  

Microsoft Academic Search

The extra-solar planet HD 209458b has been found to have an extended atmosphere of escaping atomic hydrogen (Vidal-Madjar et al. 2003), suggesting that ``hot Jupiters'' closer to their parent stars could evaporate. Here we estimate the atmospheric escape (so called evaporation rate) from hot Jupiters and their corresponding life time against evaporation. The calculated evaporation rate of HD 209458b is

A. Lecavelier des Etangs; A. Vidal-Madjar; J. C. McConnell; G. Hbrard

2004-01-01

166

ENVIRONMENTAL CHEMISTRY  

EPA Science Inventory

Environmental chemistry is applied to estimating the exposure of ecosystems and humans to various chemical environmental stressors. Among the stressors of concern are mercury, pesticides, and arsenic. Advanced analytical chemistry techniques are used to measure these stressors ...

167

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

168

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents background information, laboratory procedures, classroom materials/activities, and chemistry experiments. Topics include sublimation, electronegativity, electrolysis, experimental aspects of strontianite, halide test, evaluation of present and future computer programs in chemistry, formula building, care of glass/saturated calomel

School Science Review, 1983

1983-01-01

169

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

170

Atoms, Molecules, and Ions  

NSDL National Science Digital Library

General chemistry WebCT exam/quiz questions. The Atoms, Molecules, and Ions topic covers the basics of the composition of atoms, including subatomic particles, elements, allotropes, and isotopes. Periodic placement and trends, molar mass, and molecular formulas and ions are also included.

2008-02-12

171

Deuterium chemistry of dense gas in the vicinity of low-mass and massive star forming regions  

E-print Network

The standard interstellar ratio of deuterium to hydrogen (D/H) atoms is $\\sim 1.5 \\times 10^{-5}$. However, the deuterium fractionation is in fact found to be enhanced, to different degrees, in cold, dark cores, hot cores around massive star forming regions, lukewarm cores, and warm cores ({\\it hereafter}, hot corinos) around low-mass star forming regions. In this paper, we investigate the overall differences in the deuterium chemistry between hot cores and hot corinos. We have modelled the chemistry of dense gas around low-mass and massive star forming regions using a gas-grain chemical model. We investigate the influence of varying the core density, the depletion efficiency of gaseous species on to dust grains, the collapse mode and the final mass of the protostar on the chemical evolution of star forming regions. We find that the deuterium chemistry is, in general, most sensitive to variations of the depletion efficiency on to grain surfaces, in agreement with observations. In addition, the results showed ...

Awad, Zainab; Bayet, Estelle; Caselli, Paola

2014-01-01

172

Chemistry Links  

NSDL National Science Digital Library

This compiled site contains titles and links to over 40 sites, journal articles, course and tutorial materials, simulations, batteries, and other resources. Definitions of chemistry, theoretical chemistry, organic, physical and nuclear chemistry are integrated with the links to outside materials. A number of useful keywords are included to help users navigate the materials.

Charnine, Michael

2011-04-01

173

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

174

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.

175

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

176

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

177

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.

178

for Undergraduate CHEMISTRY MAJORS  

E-print Network

Technology, Colloid and Surface Chemistry, Consumer Products, Food and Flavor Chemistry, Forensic ChemistryHANDBOOK for Undergraduate CHEMISTRY MAJORS DEPARTMENT OF CHEMISTRY Fall 2010 #12;#12;TABLE OF CONTENTS A Career in Chemistry - What It Means ___________________________________________ 4 What do

Stuart, Steven J.

179

Hot Ice  

Microsoft Academic Search

THAT the experiments of Dr. Carnelley on hot ice have excited much interest is not to be wondered at. His statement, however, that ice could be raised to a temperature of 180 without melting was so amazing that many a one could not accept it without repeating the experiments. Soon after the first short notice of Dr. Carnelley appeared in

C. J. E. Brutel de La Rivire; A. van Hasselt

1881-01-01

180

Hot Ice  

Microsoft Academic Search

As my name has been mentioned in NATURE in connection with Dr. Carnelley's experiments on hot ice it may possibly be convenient if I describe the experiments in which I have failed to raise the temperature of ice and camphor above their fusing-points when they are heated in vacuo.

Herbert McLeod

1881-01-01

181

Hot Ice  

Microsoft Academic Search

I VENTURE, in referring to Dr. Lodge's letter of this week, to put before your readers the meaning of the remarks made on Dr. Carnelley's experiment at the Chemical Society by Prof. Ayrton, who is now away from England. I understood him to say that as Dr. Carnelley's hot ice is obviously in a condition which cannot be represented within

John Perry; A. VAN HASSELT

1881-01-01

182

Hot Ice  

Microsoft Academic Search

BEING a reader of NATURE, I have become quite interested in Mr. Thos. Carnelley's experiments with hot ice. Although Mr. Carnelley's experiments would seem to be sufficiently accurate to prove that the ice was in a heated condition, I would still like to offer an additional method to heat the ice, and also a method to test for heat in

George B. Richmond

1881-01-01

183

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.

184

Analytical Chemistry  

NSDL National Science Digital Library

This document contains a list of detailed lecture notes covering a wide range of topics including equilibrium, titrations, sample preparation, acids and bases, buffers, spectrophotometry, potentiometry and chromatography. This site is part of a collection of notes from a general chemistry course taught at the State University of West Georgia. This document gives supplementary material that could be useful to intermediate chemistry majors in an analytical chemistry course or new faculty developing a course.

Henderson, David E.

2011-06-01

185

TCD-IISc Symposium in Chemistry & Chemical Biology Monday 24th  

E-print Network

-dimensional nanomaterials: exploring the flatland atom-by-atom" Valeria Nicolosi, Chemistry & Physics, Trinity College 10 materials" Balaji Jagirdar, Inorganic & Physical Chemistry, IISc 1.00-2.15 pm: Lunch Break 2.15- 3.00pm Chemistry, IISc 4.55-5.30pm: "It's Fun at the Bottom" - Adventures in Actinide Chemistry" Robert Baker

O'Mahony, Donal E.

186

Image Storage in Hot Vapors  

E-print Network

We theoretically investigate image propagation and storage in hot atomic vapor. A $4f$ system is adopted for imaging and an atomic vapor cell is placed over the transform plane. The Fraunhofer diffraction pattern of an object in the object plane can thus be transformed into atomic Raman coherence according to the idea of ``light storage''. We investigate how the stored diffraction pattern evolves under diffusion. Our result indicates, under appropriate conditions, that an image can be reconstructed with high fidelity. The main reason for this procedure to work is the fact that diffusion of opposite-phase components of the diffraction pattern interfere destructively.

L. Zhao; T. Wang; Y. Xiao; S. F. Yelin

2007-10-22

187

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

188

Martian corona: Nonthermal sources of hot heavy species  

Microsoft Academic Search

We have studied the production of hot O and C atoms, and hot CO2 and CO molecules in the Martian upper atmosphere and exosphere by dissociative recombination (DR) of O2+ and CO+ ions, and sputtering of the atmosphere by incident O+ pick-up ions. Production and collisional thermalization of the hot particles in the upper atmosphere are described by using a

F. Cipriani; F. Leblanc; J. J. Berthelier

2007-01-01

189

Supramolecular chemistry: from molecular information towards self-organization and complex matter  

Microsoft Academic Search

Molecular chemistry has developed a wide range of very powerful procedures for constructing ever more sophisticated molecules from atoms linked by covalent bonds. Beyond molecular chemistry lies supramolecular chemistry, which aims at developing highly complex chemical systems from components interacting via non-covalent intermolecular forces. By the appropriate manipulation of these interactions, supramolecular chemistry became progressively the chemistry of molecular information,

Jean-Marie Lehn

2004-01-01

190

ORGANIC CHEMISTRY UCLA Organic Chemistry Faculty  

E-print Network

ORGANIC CHEMISTRY UCLA Organic Chemistry Faculty perform research in molecular machines, exotic CHEMISTRY FACULTY RESEARCH INTERESTS Anne M. Andrews, Professor-in-Residence: Understanding how areas of interest include cross- coupling reactions, green chemistry, heterocycle synthesis, and natural

Levine, Alex J.

191

Atmospheric chemistry of perfluoroalkanesulfonamides: kinetic and product studies of the OH radical and Cl atom initiated oxidation of N-ethyl perfluorobutanesulfonamide.  

PubMed

Perfluorooctanesulfonamides [C8F17SO2N(R1)(R2)] are present in the atmosphere and may, via atmospheric transport and oxidation, contribute to perfluorocarboxylates (PFCA) and perfluorooctanesulfonate (PFOS) pollution in remote locations. Smog chamber experiments with the perfluorobutanesulfonyl analogue N-ethyl perfluorobutanesulfonamide [NEtFBSA; C4F9SO2N(H)CH2CH3] were performed to assess this possibility. By use of relative rate methods, rate constants for reactions of NEtFBSA with chlorine atoms (296 K) and OH radicals (301 K) were determined to be kCL) = (8.37 +/- 1.44) x 10(-12) and kOH = (3.74 +/- 0.77) x 10(-13) cm3 molecule(-1) s(-1), indicating OH reactions will be dominant in the troposphere. Simple modeling exercises suggestthat reaction with OH radicals will dominate removal of perfluoroalkanesulfonamides from the gas phase (wet and dry deposition will not be important) and that the atmospheric lifetime of NEtFBSA in the gas phase will be 20-50 days, thus allowing substantial long-range atmospheric transport. Liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis showed that the primary products of chlorine atom initiated oxidation were the ketone C4F9SO2N(H)COCH3; aldehyde 1, C4F9SO2N(H)CH2CHO; and a product identified as C4F9SO2N(C2H5O)- by high-resolution MS but whose structure remains tentative. Another reaction product, aldehyde 2, C4F9SO2N(H)CHO, was also observed and was presumed to be a secondary oxidation product of aldehyde 1. Perfluorobutanesulfonate was not detected above the level of the blank in any sample; however, three perfluoroalkanecarboxylates (C3F7CO2-, C2F5CO2-, and CF3CO2-) were detected in all samples. Taken together, results suggest a plausible route by which perfluorooctanesulfonamides may serve as atmospheric sources of PFCAs, including perfluorooctanoic acid. PMID:16509330

Martin, J W; Ellis, D A; Mabury, S A; Hurley, M D; Wallington, T J

2006-02-01

192

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

193

5.61 Physical Chemistry, Fall 2004  

E-print Network

Introductory quantum chemistry; particles and waves; wave mechanics; atomic structure and the Periodic Table; valence and molecular orbital theory; molecular structure; and photochemistry. From the course home page: Course ...

Griffin, Robert Guy

194

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

195

"Doing Chemistry."  

ERIC Educational Resources Information Center

Summarizes papers presented at the Sixth Biennial Conference on Chemical Education in the area of "Doing Chemistry," i.e., demonstrations and student experiments. A bibliography of 21 presented papers in this area is attached. (CS)

Journal of Chemical Education, 1981

1981-01-01

196

Cooperative Chemistry  

NSDL National Science Digital Library

Concept mapping in the organic chemistry laboratory can supplant cookbook activities with higher cognitive exercises. The common thread of most organic lab experiments is the synthesis, isolation, purification, and characterization of a carbon compound. T

Gahr, Allan A.

2003-02-01

197

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

198

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

199

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

200

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

201

TCD-IISc Symposium "Chemistry & Chemical Biology"  

E-print Network

. Valeria Nicolosi, ERC Research Professor. Research interest in the liquid-phase processing and atom and catalysis . Robert Baker, Assistant Professor in Chemistry. Research interest in fundamental and applied and photochemical reactions, with emphasis on radical chemistry and charge transfer at disordered carbons and oxide

O'Mahony, Donal E.

202

Nuclear Chemistry, Science (Experimental): 5316.62.  

ERIC Educational Resources Information Center

This nuclear chemistry module includes topics on atomic structure, instability of the nucleus, detection strengths and the uses of radioactive particles. Laboratory work stresses proper use of equipment and safe handling of radioactive materials. Students with a strong mathematics background may consider this course as advanced work in chemistry.

Williams, Russell R.

203

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.

204

Physical Chemistry and Theoretical Chemistry CHM1441H Mathematical Methods  

E-print Network

to reaction coordinates, and motor protein driven conformational feedback loops. Other topics to be covered is to introduce mathematical techniques that are commonly encountered in Physical Chemistry. Topics discussed of atomic and molecular processes; Theoretical formulation and discussion of experimental implementation

Chan, Hue Sun

205

CHEMISTRY 320 PHYSICAL CHEMISTRY I  

E-print Network

), physical transformations (including phase transitions), solutions, electrochemistry, and chemical kinetics of the physical principles of chemistry. Goals/ Objectives: CHEM 320 presents chemical principles from, internal energy, enthalpy and entropy), chemical thermodynamics (Gibbs free energy and chemical potentials

Findley, Gary L.

206

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

207

Mechanisms Influencing "Hot-Wire" Deposition of Hydrogenated Amorphous Silicon  

SciTech Connect

Intrinsic hydrogenated amorphous silicon (a-Si:H) has been deposited using a hot tungsten filament in pure silane to drive the deposition chemistry--the ''hot-wire'' deposition method. The electronic and infrared properties of the film have been measured as a function of deposition parameters, leading to three principal conclusions. First, to obtain a high quality material, the Si atoms evaporated from the filament (distance L from the substrate) must react with silane (density ns) before reaching the substrate; this requires nsL greater than a critical value. Second, radical-radical reactions cause deterioration of film properties at high values of G(nsL),3 where G is the film growth rate; this requires G(nsL)3 less than a critical value. Finally, the film quality is a function of G, and as G is increased the substrate temperature must be correspondingly increased to obtain high film quality. By optimizing these parameters, we have produced films with excellent electronic properties (e.g., ambipolar diffusion length >200 nm) at >5 nm/s deposition rate. Based on these insights, formulas are also given for optimizing film properties in multiple-filament geometries and in diluted silane.

Molenbroek, E. C.; Mahan, A. H.; Gallagher, A.

1997-08-15

208

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.

209

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

210

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.

211

Atomic and molecular supernovae  

NASA Technical Reports Server (NTRS)

Atomic and molecular physics of supernovae is discussed with an emphasis on the importance of detailed treatments of the critical atomic and molecular processes with the best available atomic and molecular data. The observations of molecules in SN 1987A are interpreted through a combination of spectral and chemical modelings, leading to strong constraints on the mixing and nucleosynthesis of the supernova. The non-equilibrium chemistry is used to argue that carbon dust can form in the oxygen-rich clumps where the efficient molecular cooling makes the nucleation of dust grains possible. For Type Ia supernovae, the analyses of their nebular spectra lead to strong constraints on the supernova explosion models.

Liu, Weihong

1997-01-01

212

Unlocking the Atom  

NSDL National Science Digital Library

In this project, high school chemistry students investigate atomic structure from a historical perspective. Assuming the personas of eight legendary scientists and their assistants, students stage a mock gathering to explore the evolution of the atomic model. This role-playing activity may also serve as a template for weaving the rich history of science into other subject areas. The project culminates in individually written news stories about the "meeting of the minds," an assignment that allows students to weave history, modern atomic theory, and their own twist on events that might transpire if deceased scientists could converse.

Miller, Jacqueline S.; Craft, Jennifer L.

2007-02-01

213

Undergraduate Courses in Chemistry Catalogue Descriptions and Course Syllabi  

E-print Network

-1036.) (3H,3C) CHEM 1015 % CHEM 1016 % Atoms & Atomic Structure 14 Organic Chemistry 15 Periodic Table 7, and important applications. (Dupli- cates 1015-1016) (3H,3C) CHEM 1035 / 1035H % CHEM 1036 / 1036H % Elements/Periodic) 1035-1036: GENERAL CHEMISTRY Principles of the science, character of the elements and their more

Crawford, T. Daniel

214

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

215

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.

2006-01-11

216

Position: Assistant Professor of Chemistry, Physical Chemistry  

E-print Network

John Grey Position: Assistant Professor of Chemistry, Physical Chemistry Email: jkgrey@unm.edu Phone: 505.277.1658; Fax: 505.277.2609 Office: Clark Hall B70 Homepage: http://chemistry.unm.edu/faculty_web/jgrey Education B.S. in Chemistry, 1999, Michigan Technological University, Houghton, MI Ph.D. in Chemistry

217

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 ...

218

Computational Chemistry with RNA Secondary Structures  

E-print Network

Chemistry. On the other hand, a relatively small number of measurably physical parameters together thermodynamic and kinetic properties without recourse to an atom-by-atom model of the molecule. Here we review holds: (i) i = k if and only if j = l, and (ii) k

Stadler, Peter F.

219

ISSN 1463-9076 Physical Chemistry Chemical Physics  

E-print Network

2011 | Pages 3561­4164 COVER ARTICLE Nizkorodov et al. Molecular chemistry of organic aerosols throughISSN 1463-9076 Physical Chemistry Chemical Physics www.rsc.org/pccp Volume 13 | Number 9 | 7 March the application of high resolution mass spectrometry HOT ARTICLE Weingart, Garavelli et al. Product formation

Nizkorodov, Sergey

220

Atmospheric Chemistry of Venus-like Exoplanets Laura Schaefer  

E-print Network

- 1 - Atmospheric Chemistry of Venus-like Exoplanets by Laura Schaefer and Bruce Fegley, Jr thermodynamic calculations to model atmospheric chemistry on terrestrial exoplanets that are hot enough observations of the atmospheres of terrestrial-sized exoplanets by current and proposed space observatories

Fegley Jr., Bruce

221

/6582 Biophysical Chemistry Fall Biophysical Chemistry  

E-print Network

/6582 Biophysical Chemistry Fall 1 CHEM /6582 Biophysical Chemistry Course meeting place concepts in biophysical chemistry. You will develop an understanding of how thermodynamics, kinetics literature concerning the application of biophysical techniques to characterize biological molecules

Sherrill, David

222

Green Chemistry  

NSDL National Science Digital Library

This audio segment from PRI's The World Science Podcast explores the science of Green Chemistry. Hear about companies that are developing greener chemicals, and learn why they are fast becoming an attractive alternative for the multi-billion dollar chemical industry.

Foundation, Wgbh E.

2010-02-12

223

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

224

Atmospheric Chemistry  

NSDL National Science Digital Library

This set of links provides access to resources on atmospheric chemistry, especially acid deposition, air pollution, and air quality. The sites include personal and government pages, universities and research groups, non-governmental organizations and meetings, and products and services. There are also links to related search topics.

225

Definition Chemistry  

E-print Network

1 · Definition · Chemistry · Factors · Mitigation MinE 422 Acid Rock Drainage Online `Gard Guide is a great source of information Terminology · acid rock drainage (ARD) · saline drainage (SD) · acid mine or acid and metalliferous drainage (AMD) · mining influenced water (MIW) · neutral mine drainage (NMD

Boisvert, Jeff

226

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

227

Analytical Chemistry  

NSDL National Science Digital Library

This site features lecture notes for first and second level courses in analytical chemistry. Topics include titrations, gravimetry, kinetics and electrochemistry (redox). Potentiometry, coulometry, voltammetry, spectroscopic and separation methods are presented as well, and are illustrated with QuickTime animations.

Hardy, James K.

2011-03-30

228

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

229

Chemistry Newsletter # 7  

NSF Publications Database

... the Division of Chemistry Don Burland to retire from the Division of Chemistry Mathematical and ... WITHIN THE DIVISION OF CHEMISTRY The Division of Chemistry has completed its national search and is ...

230

CHEMISTRY DEPARTMENT HANDBOOKFOR STUDENTS  

E-print Network

/ENVIRONMENTAL, Bachelor of Science in Chemistry with Option in Environmental Chemistry 27 BS CHEM/NANOTECHNOLOGY, Bachelor in Biochemistry 85 Minor in Environmental Chemistry 86 1st, 2nd and 3rd Floor Maps of the Chemistry Rooms

Hardy, Christopher R.

231

UCLA CHEMISTRY & BIOCHEMISTRY  

E-print Network

UCLA CHEMISTRY & BIOCHEMISTRY ORIENTATION HANDBOOK 2012-2013 #12;Table of Contents Introduction .............................................................................................................................................2 Chemistry & Biochemistry Undergraduate Office ................................................................................................................................................4 Biochemistry

Levine, Alex J.

232

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 ITUs, 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.

2009-06-08

233

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.

234

Chemistry 675 Advanced Organic Chemistry  

E-print Network

. Chisholm 4-006 CST jdchisho@syr.edu 443-6894 Office Hours: By appointment, between 9 AM and 5 PM Course in my office (CST 4-006) or my mailbox in the chemistry office (CST 1-014). Late problem sets will have

Doyle, Robert

235

Environmental Chemistry II (Atmospheric Chemistry)  

E-print Network

Seinfeld, J. H. and Pandis, S. N. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change Monday, December 16 at 4:00 p.m. (Climate Change and comprehensive) Exams I and II are planned as two for undergraduate students than graduate students. Grading Scale 85 -100% at least an A- 75 - 84% at least a B- 65

Dibble, Theodore

236

Interstellar Grain Surface Chemistry  

NASA Technical Reports Server (NTRS)

Chemistry on grain surfaces plays an Important role in the formation of interstellar Ices, It can also influence the composition of the gas phase through outgassing near luminous, newly formed stars. This paper reviews the chemical processes taking place on Interstellar grain surfaces with the emphasis on those transforming CO into other hydrocarbons. At low, molecular cloud temperatures (approximately equal to 10K), physisorption processes dominate interstellar grain surface chemistry and GO is largely hydrogenated through reactions with atomic H and oxidized through reactions with atomic O. The former will lead to the formation of H2CO and CH3OH ices, while the latter results in CO2 ice. The observational evidence for these ices in molecular clouds will be discussed. Very close to protostars, the gas and grain temperatures are much higher (approximately equal to 500K) and chemisorption processes, including catalytic surface reactions, becomes important. This will be illustrated based upon our studies of the Fischer-Tropsch Synthesis of CH4 from CO on metallic surfaces. Likely, this process has played an important role in the early solar nebula. Observational consequences will be pointed out.

Tielens, Alexander G. G. M.; Cuzzi, Jeffrey N. (Technical Monitor)

1995-01-01

237

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

238

Environmental Chemistry  

NSDL National Science Digital Library

In this activity with several mini experiments, learners explore the chemistry that helps scientists learn about the environment and how they can help save it. Learners will determine if pollutants that have entered the ground water can also enter plants. Then, learners examine fossils to see if any changes have occurred over time in a particular species of sea mollusks. Finally, learners act as chemists to recycle paper by making paper from toilet paper.

Shaw, Maisie; Gomez, Maria

2010-01-01

239

Eleventh IHAC symposium  

SciTech Connect

Abstracts of papers for the 11th International Hot Atom chemistry Symposia are presented in this volume. These are grouped under the following sessions: nuclear chemistry and solid-state hot atom chemistry I; inorganic and solid-state hot atom chemistry II; positronium, mu-meson, and recoil tritium chemistry; kinetic theory of energetic chemical reactions; astrochemistry; inorganic and solid-state hot atom chemistry III; chemistry of energetic atoms; and target chemistry and synthesis I. (ATT)

Not Available

1982-01-01

240

Chemistry 411/611 Inorganic Chemistry (2011)  

E-print Network

1 Chemistry 411/611 Inorganic Chemistry (2011) Instructor: Assistant Professor Mathew M. Maye Chemistry", 5th Edition, Freeman Press. Available at SU bookstore. The solution manual is optional. (Suggested for CHE611 Students pursuing Inorganic) Huheey, "Inorganic Chemistry: Principles of Structure

Mather, Patrick T.

241

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

242

Teaching the Shapes of the Hydrogenlike and Hybrid Atomic Orbitals.  

ERIC Educational Resources Information Center

Discussed is the treatment of the concept of atomic orbitals in college chemistry textbooks; specifically the nodal surfaces of hybrid orbitals. Presented is a method of illustrating and introducing hydrogen-like atomic orbitals using computer graphics. (CW)

Allendoerfer, Robert D.

1990-01-01

243

School of Chemistry CHEM3100: Chemistry at a Molecular Level  

E-print Network

School of Chemistry CHEM3100: Chemistry at a Molecular Level Tutorial Groups 2013/14 Name Programme Tutor Ahmed, Zacher Medicinal Chemistry Arif, Saboor Chemistry Bagnall, Samuel Chemistry Barbara, David Chemistry Beaumont, Nicholas Chemistry Quinn, Michael J Chemistry Bennett, Matthew Chemistry Booth, Natalie

Rzepa, Henry S.

244

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

245

Chemguide: Atomic Orbitals  

NSDL National Science Digital Library

This web page explains what atomic orbitals are in a way that makes it appropriate for pre-college introductory chemistry or physics courses. It goes into detail on s and p orbitals, including their shapes and energies, while devoting less discussion to d and f orbitals. The author uses an analogy comparing an atom to a multi-story house -- with the nucleus on the ground floor and then various rooms (orbitals) on the higher floors occupied by the electrons. A full page debunks the misconception that "orbitals" are like "orbits" (common among beginning students). Beyond this foundation, the tutorial explores how electrons fill orbitals (from low-to-high energy). It concludes with a set of questions, with answers provided, for self-gauging understanding. This page is part of Chemguide, an informational website developed by a veteran high school teacher to promote deeper understanding of concepts in introductory and intermediate-level chemistry.

Clark, Jim

2013-02-20

246

Part 2. Three Primary Areas of Theoretical Chemistry Chapter 5. An Overview of Theoretical Chemistry  

E-print Network

, and plastic materials comprised of molecules. All such forms of molecular matter are what chemistry is about addresses is molecular structure, which means how the molecule's atoms are linked together by bonds and what-zwitterion form with dotted hydrogen bond. The connectivity among the atoms in arginine is dictated by the well

Simons, Jack

247

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.

248

(Pesticide chemistry)  

SciTech Connect

This report summarizes a trip by L. W. Barnthouse of the Environmental Sciences Division (ESD), Oak Ridge National Laboratory (ORNL), to Hamburg, Federal Republic of Germany (FRG), where he participated in the 7th International Congress of Pesticide Chemistry. He chaired a workshop on experimental systems for determining effects of pesticides on nontarget organisms and gave an oral presentation at a symposium on pesticide risk assessment. Before returning to the United States, Dr. Barnthouse visited the Netherlands Institute for Sea Research in Texel, the Netherlands.

Barnthouse, L.W.

1990-09-04

249

Chemistry References  

NSDL National Science Digital Library

This site highlights chemistry resources that we consider essentiala fabulous periodic table, a database of chemical compounds, a set of demonstrations of chemical reactions that are just plain spectacular, and, dont forget, laboratory safety. Articles from the web sites Whats That Stuff? and Science News for Kids can be used as supplemental reading all through the year. This site explains the history and characteristics of over 20 substances, such as sunscreen, Cheese Whiz, baseballs, fluoride, new car smell, ink, lipstick, bug spray, and licorice. The individual articles are nontechnical for the most part and are presented in a fun way that readers will enjoy. Also, if a ...

Kim

2007-08-08

250

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

251

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents laboratory procedures, classroom materials/activities, and demonstrations, including: vapor pressure of liquid mixtures and Raoult's law; preparation/analysis of transition metal complexes of ethylammonium chloride; atomic structure display using a ZX81 (includes complete program listing); "pop-up" models of molecules and ions; reactions

School Science Review, 1982

1982-01-01

252

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

253

Heavy element nuclear chemistry at JAERI  

Microsoft Academic Search

The present status of heavy element nuclear chemistry research at JAERI (Japan Atomic Energy Research Institute) is reviewed.\\u000a Production of the transactinide nuclei 261Rf and 262Db via the reactions of 248Cm(18O,5n) and 248Cm(19F, 5n), respectively, at the JAERI tandem accelerator is reported. Study of the aqueous chemistry of Rf is being carried out with\\u000a a newly developed rapid ion-exchange separation

Y. Nagame; M. Asai; H. Haba; K. Tsukada; I. Nishinaka; S. Goto; A. Toyoshima; K. Akiyama; M. Sakama; Y. L. Zhao; S. Ichikawa; H. Nakahara

2003-01-01

254

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

255

APPROXIMATE CHEMISTRY 113  

E-print Network

APPROXIMATE CHEMISTRY 113 Spring 2014 Forensic Science Professors James T. Spencer (jtspence SKILLS: Chemistry 113, Forensic Science, is focused upon the application of scientific methods specifically relevant to crime detection and analysis will be presented. No prior chemistry instruction

Doyle, Robert

256

Sawyer Environmental Chemistry Research  

E-print Network

1 Sawyer Environmental Chemistry Research Laboratory Sawyer Environmental Research Center University of Maine #12;2 Mission Statement The Sawyer Environmental Chemistry Research Laboratory is a multi industry. The Sawyer Environmental Chemistry Research Laboratory employs advanced analytical techniques

Thomas, Andrew

257

Why Teach Environmental Chemistry?  

ERIC Educational Resources Information Center

Discusses the importance of teaching environmental chemistry in secondary school science classes, and outlines five examples of environmental chemistry problems that focus on major concepts of chemistry and have critical implications for human survival and well-being. (JR)

Gardner, Marjorie H.

1974-01-01

258

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.

259

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.

260

Atomic Structure: Investigating Atoms  

NSDL National Science Digital Library

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of three Science Objects in the Atomic Structure SciPack. It discusses the

National Science Teachers Association (NSTA)

2010-05-24

261

Really Hot Stars  

NASA Astrophysics Data System (ADS)

Spectacular VLT Photos Unveil Mysterious Nebulae Summary Quite a few of the most beautiful objects in the Universe are still shrouded in mystery. Even though most of the nebulae of gas and dust in our vicinity are now rather well understood, there are some which continue to puzzle astronomers. This is the case of a small number of unusual nebulae that appear to be the subject of strong heating - in astronomical terminology, they present an amazingly "high degree of excitation". This is because they contain significant amounts of ions, i.e., atoms that have lost one or more of their electrons. Depending on the atoms involved and the number of electrons lost, this process bears witness to the strength of the radiation or to the impact of energetic particles. But what are the sources of that excitation? Could it be energetic stars or perhaps some kind of exotic objects inside these nebulae? How do these peculiar objects fit into the current picture of universal evolution? New observations of a number of such unusual nebulae have recently been obtained with the Very Large Telescope (VLT) at the ESO Paranal Observatory (Chile). In a dedicated search for the origin of their individual characteristics, a team of astronomers - mostly from the Institute of Astrophysics & Geophysics in Lige (Belgium) [1] - have secured the first detailed, highly revealing images of four highly ionized nebulae in the Magellanic Clouds, two small satellite galaxies of our home galaxy, the Milky Way, only a few hundred thousand light-years away. In three nebulae, they succeeded in identifying the sources of energetic radiation and to eludicate their exceptional properties: some of the hottest, most massive stars ever seen, some of which are double. With masses of more than 20 times that of the Sun and surface temperatures above 90 000 degrees, these stars are truly extreme. PR Photo 09a/03: Nebula around the hot star AB7 in the SMC. PR Photo 09b/03: Nebula near the hot Wolf-Rayet star BAT99-2 in the LMC. PR Photo 09c/03: Nebula near the hot binary star BAT99-49 in the LMC. PR Photo 09d/03: The N44C Nebula in the LMC. Four unique images of highly excited nebulae in the Magellanic Clouds ESO PR Photo 09a/03 ESO PR Photo 09a/03 [Preview - JPEG: 400 x 472 pix - 74k [Normal - JPEG: 800 x 943 pix - 720k] [Full-Res - JPEG: 1200 x 1414 pix - 1.2M] ESO PR Photo 09b/03 ESO PR Photo 09b/03 [Preview - JPEG: 400 x 466 pix - 70k [Normal - JPEG: 800 x 931 pix - 928k] [Full-Res - JPEG: 1200 x 1397 pix - 1.8M] ESO PR Photo 09c/03 ESO PR Photo 09c/03 [Preview - JPEG: 400 x 469 pix - 74k [Normal - JPEG: 800 x 937 pix - 1.1M] [Full-Res - JPEG: 1200 x 1405 pix - 2.2M] ESO PR Photo 09d/03 ESO PR Photo 09d/03 [Preview - JPEG: 400 x 473 pix - 28k [Normal - JPEG: 800 x 945 pix - 368k] [Full-Res - JPEG: 1200 x 1418 pix - 600k] Captions: PR Photo 09a/03 is a reproduction of a "near-true" three-colour composite image of the highly excited nebula around the hot double star AB7 in the Small Magellanic Cloud (SMC), obtained in January 2002 with the FORS1 multi-mode instrument at the 8.2-m VLT MELIPAL telescope at the Paranal Observatory (Chile). It is based on three exposures through narrow-band optical (interference) filters that isolate the light from specific atoms and ions. In this rendering, the blue colour represents the light from singly ionized Helium (He II; wavelength 468.6 nm; exposure time 30 min), green corresponds to doubly ionized oxygen ([O III]; 495.7 + 500.7 nm; 5 min) and red to hydrogen atoms (H; H-alpha line at 656.2 nm; 5 min). Of these three ions, He II is the tracer of high excitation, i.e. the bluest areas of the nebula are the hottest. The sky field measures 400 x 400 arcsec2; the original pixel size on the 2k x 2k CCD is 0.23 arcsec. North is up and east to the left. Before combination, the CCD frames were flat-fielded and cleaned of cosmic-rays. Moreover, the stars in the blue (He II) image were removed in order to provide a clearer view of the surrounding nebular emission. The reproduced brightness is proportional to the squar

2003-04-01

262

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

263

Combustion chemistry  

SciTech Connect

This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

Brown, N.J. [Lawrence Berkeley Laboratory, CA (United States)

1993-12-01

264

Environmental chemistry. Seventh edition  

SciTech Connect

This book presents a basic understanding of environmental chemistry and its applications. In addition to providing updated materials in this field, the book emphasizes the major concepts essential to the practice of environmental chemistry. Topics of discussion include the following: toxicological chemistry; toxicological chemistry of chemical substances; chemical analysis of water and wastewater; chemical analysis of wastes and solids; air and gas analysis; chemical analysis of biological materials and xenobiotics; fundamentals of chemistry; and fundamentals of organic chemistry.

Manahan, S.E. [Univ. of Missouri, Columbia, MO (United States)

1999-11-01

265

Atomic Physics  

NSDL National Science Digital Library

This collection provides a basic introduction to Atomic Physics. It reviews the building blocks of atomic structure, explores atomic isotopes, explains Einstein's famous equation E = mc2, and introduces the various types of radiation.

Griffith, Christopher

266

Science Update: Inorganic Chemistry.  

ERIC Educational Resources Information Center

Describes areas of inorganic chemistry which have changed dramatically in the past year or two, including photochemistry, electrochemistry, organometallic complexes, inorganic reaction theory, and solid state chemistry. (DS)

Rawls, Rebecca

1981-01-01

267

Recent Progress in ultracold atoms  

E-print Network

to it ?" - Albert Einstein #12;Non Zero Circulation !! How to rotate an irrotational fluid? x iy 1 x2 y2 fei, dx big. Particles are fuzzy. hot cold #12;S. Bose A. Einstein BEC predicted in 1924 by Bose and Einstein What is Bose-Einstein condensation (BEC)? #12;300 K to 1 mK 109 atoms 1 mK to 1 mK 108 106 atoms

Baltisberger, Jay H.

268

Biology 3515/Chemistry 3515 Biological Chemistry Laboratory  

E-print Network

Biology 3515/Chemistry 3515 Biological Chemistry Laboratory Spring 2013 (Draft Syllabus, 23 August 2012) Course Description and Objectives: This course is intended for students who have taken Biology and function, particularly for enzymes. Prerequisites: Biology 3510 or Chemistry 3510 Instructor: David P

Simons, Jack

269

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

270

The Chemistry of Life Part I Macromolecules and  

E-print Network

Components Atoms are composed of 3 subatomic particles Electrons ­ negatively charged Protons ­ positively molecules together Ionic bonds: form between charged particles (Ions) #12;2 Organic Chemistry Carbon makes

Cochran-Stafira, D. Liane

271

3.091 Introduction to Solid State Chemistry, Fall 2004  

E-print Network

This course explores the basic principles of chemistry and their application to engineering systems. It deals withthe relationship between electronic structure, chemical bonding, and atomic order. It also investigates ...

Sadoway, Donald

272

Lower-Secondary Introductory Chemistry Course: A Novel Approach Based on Science-Education Theories, with Emphasis on the Macroscopic Approach, and the Delayed Meaningful Teaching of the Concepts of Molecule and Atom  

ERIC Educational Resources Information Center

We present a programme for a novel introductory lower-secondary chemistry course (seventh or eighth grade) that aims at the application of theories of science education, and in particular of conceptual/meaningful learning and of teaching methodology that encourages active and inquiry forms of learning The approach is rigorous with careful use of

Tsaparlis, Georgios; Kolioulis, Dimitrios; Pappa, Eleni

2010-01-01

273

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

274

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

275

The University of North Carolina at Chapel Hill: Chemistry Fundamentals Program  

NSDL National Science Digital Library

The University of North Carolina at Chapel Hill Chemistry Fundamentals Program offers an interactive review of the fundamentals of chemistry for incoming college freshman chemistry students. The basic link offers materials about chemical nomenclature, atomic structure, stoichiometry, and acid base chemistry. After learning about these essentials, users can progress to more advanced topics such as gas laws, thermodynamics, kinetics, and redox chemistry. The explanations are linked with a useful chemistry glossary. The website offers many online calculators to deal with compressibility, unit conversion, and various other chemical problems. Students can also find a helpful review of mathematics used in chemistry.

276

The University of North Carolina at Chapel Hill: Chemistry Fundamentals Program  

NSDL National Science Digital Library

The University of North Carolina at Chapel Hill Chemistry Fundamentals Program offers an interactive review of the fundamentals of chemistry for incoming college freshman chemistry students. The basic link offers materials about chemical nomenclature, atomic structure, stoichiometry, and acid base chemistry. After learning about these essentials, users can progress to more advanced topics such as gas laws, thermodynamics, kinetics, and redox chemistry. The explanations are linked with a useful chemistry glossary. The website offers many online calculators to deal with compressibility, unit conversion, and various other chemical problems. Students can also find a helpful review of mathematics used in chemistry.

2007-05-19

277

Using Games To Teach Chemistry: An Annotated Bibliography  

Microsoft Academic Search

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, &

Jeanne V. Russell

1999-01-01

278

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

279

Using Games To Teach Chemistry: An Annotated Bibliography.  

ERIC Educational Resources Information Center

Lists 67 published or marketed chemistry games organized under the following categories: (1) general knowledge; (2) elements and atomic structure; (3) nomenclature, formulas, and equation writing; (4) chemical reactions; (5) solutions and solubilities; (6) organic chemistry, and (8) miscellaneous subjects. Includes a brief description of each

Russell, Jeanne V.

1999-01-01

280

Department of Chemistry and Biochemistry CBF Enrichment Program The Department of Chemistry and Biochemistry student community has enthusiastically participated  

E-print Network

and Analytical Chemistry · Surface tensiometer · Atomic absorption spectrometer · Benchtop FT-NMR · Bomb calorimeter · Flash photolysis instrument · IC chromatograph #12;Biochemistry · Gel Documentation Hardware

Sze, Lawrence

281

Atom Interferometers  

E-print Network

Interference with atomic and molecular matter waves is a rich branch of atomic physics and quantum optics. It started with atom diffraction from crystal surfaces and the separated oscillatory fields technique used in atomic clocks. Atom interferometry is now reaching maturity as a powerful art with many applications in modern science. In this review we first describe the basic tools for coherent atom optics including diffraction by nanostructures and laser light, three-grating interferometers, and double wells on AtomChips. Then we review scientific advances in a broad range of fields that have resulted from the application of atom interferometers. These are grouped in three categories: (1) fundamental quantum science, (2) precision metrology and (3) atomic and molecular physics. Although some experiments with Bose Einstein condensates are included, the focus of the review is on linear matter wave optics, i.e. phenomena where each single atom interferes with itself.

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

2007-12-21

282

Reviews Book: Sustainable EnergyWithout the Hot Air Equipment: Doppler Effect Unit Book: The Physics of Rugby Book: Plastic Fantastic: How the Biggest Fraud in Physics Shook the Scientific World Equipment: Brunel Eyecam Equipment: 200x Digital Microscope Book: The Atom and the Apple: Twelve Tales from Contemporary Physics Book: Physics 2 for OCR Web Watch  

NASA Astrophysics Data System (ADS)

WE RECOMMEND Sustainable EnergyWithout the Hot Air This excellent book makes sense of energy facts and figures Doppler Effect Unit Another simple, effective piece of kit from SEP Plastic Fantastic: How the Biggest Fraud in Physics Shook the Scientific World Intriguing and unique write-up of an intellectual fraud case Brunel Eyecam An affordable digital eyepiece for your microscope 200x Digital Microscope An adjustable digital flexcam for classroom use The Atom and the Apple: Twelve Tales from Contemporary Physics A fascinating round-up of the recent history of physics WORTH A LOOK The Physics of Rugby Book uses sport analogy and context to teach physics concepts Physics 2 for OCR Essential textbook for the course but otherwise pointless WEB WATCH Some free teaching materials are better than those you'd pay for

2009-09-01

283

Advances in applied radiation chemistry  

NASA Astrophysics Data System (ADS)

Applied radiation chemistry seems to take position between pure radiation chemistry and radiation processing. APPLIED means, by the dictionary such as Larouse, "related or turned to practical knowledge or use" and is differentiated from the pure one and its application. Pure science, however, stretches on a continuous line and becomes "turned to practical use" in the way of research, frequently far to the application over through the applied one. These continuities between the pure, the applied and the application of sciences may easily be connected over each other, sometimes by a scientific enthusiasm. Here the importance is correct distinction, but not simple discrimination. To-day in my presentation I would like to put main emphasis on APPLIED radiation chemistry but not exclude out simply PURE radiation chemistry and radiation PROCESSING. In addition, the word of ADVANCES means the progresses in the past, including some expectations in the future. The expectation is looked forward by the selection, connected with future applicability and with strongly individual character. The topics related to advances here in my talk shall be focused mainly for the works investigated in Japan Atomic Energy Research Institute (JAERI) Laboratories from standpoint of my short experience.

Okamura, Seizo

284

so Ris Report * Danish Atomic Energy Commission  

E-print Network

in Bitumen of Low-Level Radioactive Waste Water Evaporator Concentrate at the Danish Atomic Energy Com Incorporation in Bitumen of Low-Level Radioactive Waste Water Evaporator Concentrate at the Danish Atomic Energy Risø Chemistry Department Abstract The plant for evaporation of radioactive waste water at the Research

285

Why chemistry? Chemistry is fundamental: it is the enabling  

E-print Network

Chemistry Why chemistry? Chemistry is fundamental: it is the enabling science that underlies many technology. A chemistry degree gives you the understanding to contribute to our future in very topical areas) in Chemistry BSc (Hons) in Chemistry MChem (Hons) in Chemistry (with an industrial placement year) MChem (Hons

Sussex, University of

286

Justine P. Roth Assistant Professor of Chemistry  

E-print Network

1 Justine P. Roth Assistant Professor of Chemistry Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 Phone: (410) 5167835, Fax: (410) 5168420, Email: jproth@jhu.edu URL: www.jhu.edu/~chem/roth. P. Roth* in preparation. 27. "Heavy Atom Isotope Effects as Probes of Transition Metal

Roth, Justine P.

287

Supramolecular chemistry: Functional structures on the mesoscale  

Microsoft Academic Search

F or over 100 years, chemistry has focused primarily on un- derstanding the behavior of molecules and their construction from constituent atoms. Our current level of understanding of molecules and chemical construction techniques has given us the confidence to tackle the construction of virtually any molecule, be it biological or designed, organic or inorganic, monomeric or macromolecular in origin. During

SonBinh T. Nguyen; Douglas L. Gin; Joseph T. Hupp; Xi Zhang

2001-01-01

288

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

289

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

290

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

291

Mechanisms influencing {open_quotes}hot-wire{close_quotes} deposition of hydrogenated amorphous silicon  

SciTech Connect

Intrinsic hydrogenated amorphous silicon (a-Si:H) has been deposited using a hot tungsten filament in pure silane to drive the deposition chemistry{emdash}the {open_quotes}hot-wire{close_quotes} deposition method. The electronic and infrared properties of the film have been measured as a function of deposition parameters, leading to three principal conclusions. First, to obtain a high quality material, the Si atoms evaporated from the filament (distance L from the substrate) must react with silane (density n{sub s}) before reaching the substrate; this requires n{sub s}L greater than a critical value. Second, radical-radical reactions cause deterioration of film properties at high values of G(n{sub s}L),{sup 3} where G is the film growth rate; this requires G(n{sub s}L){sup 3} less than a critical value. Finally, the film quality is a function of G, and as G is increased the substrate temperature must be correspondingly increased to obtain high film quality. By optimizing these parameters, we have produced films with excellent electronic properties (e.g., ambipolar diffusion length {gt}200 nm) at {gt}5 nm/s deposition rate. Based on these insights, formulas are also given for optimizing film properties in multiple-filament geometries and in diluted silane. {copyright} {ital 1997 American Institute of Physics.}

Molenbroek, E.C.; Mahan, A.H. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)] [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Gallagher, A. [JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440 (United States)] [JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440 (United States)

1997-08-01

292

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

293

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.

294

Hot ice computer  

Microsoft Academic Search

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

Andrew Adamatzky

2009-01-01

295

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

296

Hot air balloon engine  

Microsoft Academic Search

This paper describes a solar powered reciprocating engine based on the use of a tethered hot air balloon fuelled by hot air from a glazed collector. The basic theory of the balloon engine is derived and used to predict the performance of engines in the 10kW to 1MW range. The engine can operate over several thousand metres altitude with thermal

Ian Edmonds

2009-01-01

297

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

298

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. PMID:24452558

Chan, Justin; Natekar, Aniket; Koren, Gideon

2014-01-01

299

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

300

6. HOT AIR PORTION OF DAMPERS. Hot Springs National ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. HOT AIR PORTION OF DAMPERS. - Hot Springs National Park, Bathhouse Row, Lamar Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

301

Hadronic Atoms  

E-print Network

We review the theory of hadronic atoms in QCD+QED. The non-relativistic effective Lagrangian approach, used to describe this type of bound states, is illustrated with the case of pi+pi- atoms. In addition, we discuss the evaluation of isospin-breaking corrections to hadronic atom observables by invoking chiral perturbation theory.

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

2009-03-02

302

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

303

Georgia Tech Chemistry & Biochemistrywww.chemistry.gatech.edu/rig --Research  

E-print Network

Georgia Tech Chemistry & Biochemistrywww.chemistry.gatech.edu/rig -- Research New Faculty Workshop.aip.org ! #12;Georgia Tech Chemistry & Biochemistrywww.chemistry.gatech.edu/rig -- Research New Faculty Workshop

Feig, Andrew

304

From the Academy Supramolecular chemistry: Functional structures on  

E-print Network

molecules and hold them together. In contrast, the forces used to organize and hold together supramolecular of molecules and their construction from constituent atoms. Our current level of understanding of molecules the last few decades, chemists have extended their investigations beyond atomic and molecular chemistry

305

Exploring Conceptual Frameworks of Models of Atomic Structures and Periodic Variations, Chemical Bonding, and Molecular Shape and Polarity: A Comparison of Undergraduate General Chemistry Students with High and Low Levels of Content Knowledge  

ERIC Educational Resources Information Center

The purpose of the study was to explore students' conceptual frameworks of models of atomic structure and periodic variations, chemical bonding, and molecular shape and polarity, and how these conceptual frameworks influence their quality of explanations and ability to shift among chemical representations. This study employed a purposeful sampling

Wang, Chia-Yu; Barrow, Lloyd H.

2013-01-01

306

Igniting Chemistry in Fireworks  

NSDL National Science Digital Library

Students learn about the concepts of spectral chemistry, combustion, and the nature of fire through the use of visually rich fireworks resources. Optional resources address chemical reactions for those who want a more advanced chemistry lesson.

Foundation, Wgbh E.

2004-01-29

307

Computational Chemistry Robots  

E-print Network

Computational Chemistry Robots ACS Sep 2005 Computational Chemistry Robots J. A. Townsend, P. Murray-Rust, S. M. Tyrrell, Y. Zhang jat45@cam.ac.uk Can high-throughput computation provide a reliable experimental resource for molecular...

Townsend, Joseph A; Murray-Rust, Peter; Tyrrell, Simon M; Zhang, Yong

308

Environmental chemistry: Volume A  

SciTech Connect

This is an extensive introduction to environmental chemistry for engineering and chemical professionals. The contents of Volume A include a brief review of basic chemistry prior to coverage of litho, atmo, hydro, pedo, and biospheres.

Yen, T.F.

1999-08-01

309

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

310

The Chemistry Hypermedia Project  

NSDL National Science Digital Library

These materials and documents are typical of those presented in an undergraduate course in general chemistry, analytical chemistry, and analytical instrumentation. Resources for educators include Excel spreadsheet simulations for analytical and physical chemistry, prototype JavaScripts and PERL scripts, lists of web workshops and publications, and links to the most recent papers and presentations from the Chemistry Hypermedia Project. There are also tutorials for equilibrium practice problems and analytical spectroscopy.

311

Why chemistry? Chemistry is fundamental: it is the enabling science  

E-print Network

Chemistry Why chemistry? Chemistry is fundamental: it is the enabling science that underlies many technology. A chemistry degree allows you to understand and to contribute to our future. Chemistry is challenging: understanding the very fabric of matter is both stimulating and rewarding. Studying chemistry

Sussex, University of

312

Chemistry Division Department of Biological  

E-print Network

1 Chemistry Division Department of Biological and Chemical Sciences, Illinois Institute-13 Chemistry Division invites nominations for Kilpatrick Fellowship for the academic year 2012's Chemistry Department from 1947­1960. Mary Kilpatrick was a chemistry faculty member from 1947

Heller, Barbara

313

Adam Benoit Medicinal Chemistry  

E-print Network

#12;Adam Benoit Medicinal Chemistry Ph.D. Thesis Title: Synthesis and Evaluation of Acridine Country: United States #12;Amit Gangar Medicinal Chemistry Ph.D. Thesis Title: Design and Development Wagner Home Country: India #12;Dan Wang Medicinal Chemistry M.S. Thesis Title: Synthesis and Evaluation

Thomas, David D.

314

A chronicler of chemistry  

NASA Astrophysics Data System (ADS)

Thomas Hager, author of popular science books that revisit some of the most significant developments in chemistry over the past century, talks to Nature Chemistry about the challenges of writing for a general audience, and how his dislike of chemistry was turned around by a fellow Oregonian of considerable repute.

2012-04-01

315

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

316

Chemistry and Art.  

ERIC Educational Resources Information Center

Describes a Chemistry and Art project developed for secondary students and teachers sponsored by the National Gallery and The Royal Society of Chemistry in the United Kingdom. Discusses aspects of the techniques used in creating five paintings as well as the chemistry involved in their making, deterioration, conservation, and restoration.

Berry, Martyn

1999-01-01

317

Environmental Chemistry Activities.  

ERIC Educational Resources Information Center

The authors of this curriculum supplement believe in a laboratory approach to chemistry and express the feeling that environmental chemistry provides the students an opportunity to apply theoretical chemistry to important practical problems. There are eighteen activities presented, each accompanied with behavioral objectives, one or more suggested

Jackland, Thomas; And Others

318

Engineering Materials and Chemistry  

E-print Network

................................................................................................. 10 #12;3 Course staff Dr John Daniels (Materials) Course Coordinator & Lecturer Room 217, School: by appointment A/Prof Stephen Colbran (Chemistry) Lecturer Room 225 Dalton Building (F12) Phone: 9385 4737 s: by appointment Ms Anne Ayres (Chemistry) Chemistry Tutorial and Laboratory Administrator Room 105 Dalton Building

New South Wales, University of

319

Dynamic polarizabilities of rare-earth-metal atoms and dispersion coefficients for their interaction with helium atoms  

E-print Network

Dynamic polarizabilities of rare-earth-metal atoms and dispersion coefficients for their interaction with helium atoms Xi Chu Department of Chemistry, University of Montana, Missoula, Montana 59812; published 29 March 2007 The dynamic scalar and tensor polarizabilities of the rare-earth-metal atoms

Chu, Xi

320

Automatic hot water recovery system  

SciTech Connect

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 located near the hot water outlet. The higher pressure cold water forces the hot water back into the storage tank and out of the hot water lines until pressure is equalized. Loss of unused heat trapped in the hot water lines is minimized thereby saving energy.

Haws, S.K.

1982-03-30

321

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."

322

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

323

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

324

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

325

Surface morphology and chemistry of Prunus laurocerasus L. leaves: a study using X-ray photoelectron spectroscopy, time-of-flight secondary-ion mass spectrometry, atomic-force microscopy and scanning-electron microscopy  

Microsoft Academic Search

The surface properties of the plant cuticle play a crucial role in plantpathogen interactions and the retention and penetration of agriculturally important chemicals. This paper describes the use of X-ray photoelectron spectroscopy (XPS), time-of-flight secondary-ion mass spectrometry (ToF-SIMS), tapping-mode atomic force microscopy (TM-AFM) and scanning electron microscopy (SEM) to determine surface-specific chemical and material properties of the adaxial surface of

Mark C. Perkins; Clive J. Roberts; David Briggs; Martyn C. Davies; Adrian Friedmann; Clifford A. Hart; Gordon A. Bell

2005-01-01

326

Alcohol, Chemistry and You  

NSDL National Science Digital Library

Developed by Kennesaw State University, ChemCases.com is a series of curriculum units that link responsible decision making in product development with chemical principles taught in college General Chemistry. Alcohol, Chemistry and You, by Dr. Bill Boggan, is the latest offering by the Web site, which "looks at the chemistry of beverage alcohol (ethyl alcohol) through the eyes of a General Chemistry student." The fourteen chapter lessons cover everything from what ethyl alcohol is to alcohol addiction, relating it to various principles learned in a general chemistry course.

2001-01-01

327

New Trends in Chemistry Teaching. Volume V. The Teaching of Basic Sciences: Chemistry.  

ERIC Educational Resources Information Center

This collection of articles, originally published in national and international journals, is fifth in a series devoted to trends in teaching chemistry. The volume is divided into nine sections, each with an introduction explaining why papers have been selected and outlining their particular interest. Section I provides a list of atomic masses,

United Nations Educational, Scientific, and Cultural Organization, Paris (France).

328

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 sinulariaoid A from a Sinularia species. PMID:25322472

Hill, Robert A; Sutherland, Andrew

2014-11-01

329

Hot Binaries: Observational Results.  

National Technical Information Service (NTIS)

Interferometric work on hot binary and multiple stars is summarized, from the earliest eyepiece interferometry to recent speckle and AO duplicity surveys. Multiplicity fractions for cluster, field, and runaway O stars are discussed.

W. I. Hartkopf

2010-01-01

330

Hot and dark matter  

E-print Network

In this thesis, we build new Effective Field Theory tools to describe the propagation of energetic partons in hot and dense media, and we propose two new reactions for dark matter in the early universe. In the first part, ...

D'Eramo, Francesco

2012-01-01

331

Saturn's Hot Plasma Explosions  

NASA Video Gallery

This animation based on data obtained by NASA's Cassini Spacecraft shows how the "explosions" of hot plasma on the night side (orange and white) periodically inflate Saturn's magnetic field (white ...

332

Hot dry rock update  

SciTech Connect

Hot-dry-rock experiments at Los Alamos, NM since 1970 are reviewed briefly, with emphasis on activities since 1977. These include hydraulic fracturing, seismic mapping, fracture mapping, and development of downhole instrumentation. (MHR)

Whetten, J.; Brown, D.; Potter, R.

1983-12-01

333

Historical Account And Branching To Rarefied Gas Dynamics Of Atomic and Molecular Beams : A Continuing And Fascinating Odyssey Commemorated By Nobel Prizes Awarded To 23 Laureates In Physics And Chemistry  

NASA Astrophysics Data System (ADS)

This Historical Account derived in part from D. R. Herschbach was presented as an opening lecture of the Molecular Beam Session organized at the 24th International Symposium on Rarefied Gas Dynamics held in Bari, Italy, in July 2004. The emphasis is on the impressive results due to the molecular beam techniques in the last century. The first section summarizes the historical beam experiments performed by 14 Nobel Prize laureates having used the thermally effusive sources to establish the basic principles of Modern Physics. The second section is on the branching of Molecular Beams to Rarefied Gas Dynamics having permitted to investigate the physics of supersonic free jets and transform the molecular beam techniques. Finally, the last section relates the spectacular molecular beam experiments in helium free jet ultracooling, molecular spectroscopy, chemical reaction dynamics, clustering and modification of low density matter, and biomolecule mass spectrometry, rewarded by nine Nobel Prizes in Chemistry from 1986 to 2002.

Campargue, Roger

2005-05-01

334

The Hot Tub Mystery  

NSDL National Science Digital Library

This case study sets up a mystery and asks students to solve it using science: why was the couple found dead in their hot tub? The material asks students to connect seemingly unrelated factors, such as blood pressure, hot water and alcohol. The material would be most appropriate for lower level undergraduate students. 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.

House, Herbert

2011-01-06

335

1E5 CHEMISTRY [5 credits] Lecturer(s): Assistant Prof. Michael Bridge (mbridge@tcd.ie)  

E-print Network

trends in the periodic table (in both elements and their compounds) with the underlying trends; atomic structure; electronic structure and the periodic table; bonding; elementary structural chemistry Chemical change; elements, compounds and mixtures; atomic theory; stoichiometry and chemical equations

O'Mahony, Donal E.

336

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

337

Automatic hot water recovery system  

Microsoft Academic Search

A heat recovery system recovers hot water to an insulated tank through reciprocally variable volume chambers which are biased to draw water from hot water lines when the pressure throughout the system is equalized. One-way valving means permits continuous water flow when desired through the hot water tank to the hot water outlet. In a specific embodiment, bias is effected

Haws

1985-01-01

338

Atomic weights: no longer constants of nature  

USGS Publications Warehouse

Many of us were taught that the standard atomic weights we found in the back of our chemistry textbooks or on the Periodic Table of the Chemical Elements hanging on the wall of our chemistry classroom are constants of nature. This was common knowledge for more than a century and a half, but not anymore. The following text explains how advances in chemical instrumentation and isotopic analysis have changed the way we view atomic weights and why they are no longer constants of nature

Coplen, Tyler B.; Holden, Norman E.

2011-01-01

339

Atomic Weights No Longer Constants of Nature  

SciTech Connect

Many of us grew up being taught that the standard atomic weights we found in the back of our chemistry textbooks or on the Periodic Table of the Chemical Elements hanging on the wall of our chemistry classroom are constants of nature. This was common knowledge for more than a century and a half, but not anymore. The following text explains how advances in chemical instrumentation and isotopic analysis has changed the way we view atomic weights and why they are no longer constants of nature.

Coplen, T.B.; Holden, N.

2011-03-01

340

The Elemental Compositions and Cloud Properties of Hot Jupiters: A Comprehensive Atmospheric Retrieval Study of Hot Jupiter Transmission Spectra  

NASA Astrophysics Data System (ADS)

Recent transit surveys using the Hubble Space Telescope have provided an unprecedented set of high-SNR hot Jupiter transmission spectra. Here, I present the main conclusions from a comprehensive atmospheric retrieval study of eight hot Jupiters using the new self-consistent atmospheric retrieval framework SCARLET. For each planet, I derive statistically robust constraints on the metallicity and carbon-to-oxygen ratio of the atmospheric gas, as well as the particle size and vertical extend of clouds and hazes, by combining self-consistent modeling of the atmospheric chemistry and physics with robust Bayesian statistics.

Benneke, Bjrn

2014-11-01

341

Atmospheric chemistry of HCF2O(CF2CF2O)xCF2H (x=2-4): kinetics and mechanisms of the chlorine-atom-initiated oxidation.  

PubMed

Smog chamber/FTIR techniques were used to measure k(Cl+HCF(2)O(CF(2)CF(2)O)(x)CF(2)H)=(5.31.5)10(-17) cm(3) molecule(-1) s(-1) in 700 Torr of N(2)/O(2) diluent at 2961 K. The Cl-initiated atmospheric oxidation of HCF(2)O(CF(2)CF(2)O)(x)CF(2)H, x=2,3 and 4, gave COF(2) in molar yields of (59341)%, (75871)% and (93973)%, respectively, with no other observable carbon-containing products (i.e., essentially complete conversion of the hydrofluoropolyethers into COF(2)). Quantitative infrared spectra for HCF(2)O(CF(2)CF(2)O)(x)CF(2)H (x=2-4) were recorded and used to estimate the radiative efficiencies of the title compounds (1.07, 1.33, and 1.36 W m(-2) ppb(-1)). Global warming potentials (100 year time horizon) of 3870, 4730 and 5060 were estimated for HCF(2)O(CF(2)CF(2)O)(x)CF(2)H, x=2, 3 and 4, respectively. The results are discussed with respect to the atmospheric chemistry and environmental impact of hydrofluoropolyethers. PMID:20981750

Sulbaek Andersen, Mads P; Andersen, Vibeke F; Nielsen, Ole J; Sander, Stanley P; Wallington, Timothy J

2010-12-17

342

Future of Chemistry Assumptions: Taking Chemistry in New Directions**  

E-print Network

Future of Chemistry Assumptions: Taking Chemistry in New Directions** George M. Whitesides* Keywords: Bioorganic chemistry · genomics · medicinal chemistry · philosophy of chemistry "When in scientists. We all do it. We also take it as an article of faith that serious predic- tions are almost always

Prentiss, Mara

343

atomic spectra 1 Atomic Spectra  

E-print Network

. Eisberg and Resnick: Quantum Physics of Atoms, Molecules, Solids, Nuclei and Particles, pp. 95-119, p286 Physics, pp. 88-93 (Rutherford nuclear model), 93-106 (atomic structure and electron spectra) 2. D. W. Preston and E. R. Dietz: The Art of Experimental Physics, pp. 397- 399, resolution of optical instruments

Glashausser, Charles

344

Department of Chemistry Table of Contents  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Green & Environmental Chemistry . . . . . . . . . . . . . . . . . . . . 17 Physical Chemistry W ith strengths in polymer science, green and environmental chemistry, bioorganic, bioinorganic

Kurnikova, Maria

345

Environmental chemistry: Volume B  

SciTech Connect

This is an extensive introduction to environmental chemistry for engineering and chemical professionals. The contents of Volume B include equilibria processes, chemical processes, biochemical processes, and physicochemical processes.

Yen, T.F.

1999-08-01

346

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

347

The Separate and Collective Effects of Personalization, Personification, and Gender on Learning with Multimedia Chemistry Instructional Materials  

ERIC Educational Resources Information Center

Chemistry is a difficult subject to learn and teach for students in general. Additionally, female students are under-represented in chemistry and the physical sciences. Within chemistry, atomic and electronic structure is a key concept and several recommendations in the literature describe how this topic can be taught better. These recommendations

Halkyard, Shannon

2012-01-01

348

Deuterium chemistry in the Orion Bar PDR. ``Warm'' chemistry starring CH{2}D^+  

NASA Astrophysics Data System (ADS)

Context: High levels of deuterium fractionation in gas-phase molecules are usually associated with cold regions, such as prestellar cores. Significant fractionation ratios are also observed in hot environments such as hot cores or hot corinos, where they are believed to be produced by the evaporation of the icy mantles surrounding dust grains, and are thus remnants of a previous cold (either gas-phase or grain surface) chemistry. The recent detection of DCN towards the Orion Bar, in a clump at a characteristic temperature of 70 K, has shown that high deuterium fractionation can also be detected in PDRs. The Orion Bar clumps thus appear to be a good environment for the observational study of deuterium fractionation in luke warm gas, allowing us to validate chemistry models for a different temperature range, where dominating fractionation processes are predicted to differ from those in cold gas (<20 K). Aims: We aimed to study observationally in detail the chemistry at work in the Orion Bar PDR, to understand whether DCN is either produced by ice mantle evaporation or is the result of warm gas-phase chemistry, involving the CH2D+ precursor ion (which survives higher temperatures than the usual H2D+ precursor). Methods: Using the APEX and the IRAM 30 m telescopes, we targeted selected deuterated species towards two clumps in the Orion Bar. Results: We confirmed the detection of DCN and detected two new deuterated molecules (DCO+ and HDCO) towards one clump in the Orion Bar PDR. Significant deuterium fractionations are found for HCN and H2CO, but we measured a low fractionation in HCO^+. We also provide upper limits to other molecules relevant to deuterium chemistry. Conclusions: We argue that grain evaporation in the clumps is unlikely to be a dominant process, and we find that the observed deuterium fractionation ratios are consistent with predictions of pure gas-phase chemistry models at warm temperatures (T ~ 50 K). We show evidence that warm deuterium chemistry driven by CH2D+ is at work in the clumps. Based on observations with the IRAM 30 m telescope at Pico Veleta (Spain) and the Atacama Pathfinder EXperiment (APEX) telescope. IRAM is funded by the INSU/CNRS (France), the MPG (Germany) and the IGN (Spain). APEX is a collaboration between the Max-Planck-Institut fr Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory.

Parise, B.; Leurini, S.; Schilke, P.; Roueff, E.; Thorwirth, S.; Lis, D. C.

2009-12-01

349

Hot Oil Removes Wax  

NASA Technical Reports Server (NTRS)

Mineral oil heated to temperature of 250 degrees F (121 degrees C) found effective in removing wax from workpieces after fabrication. Depending upon size and shape of part to be cleaned of wax, part immersed in tank of hot oil, and/or interior of part flushed with hot oil. Pump, fittings, and ancillary tooling built easily for this purpose. After cleaning, innocuous oil residue washed off part by alkaline aqueous degreasing process. Serves as relatively safe alternative to carcinogenic and environmentally hazardous solvent perchloroethylene.

Herzstock, James J.

1991-01-01

350

Rotational hot Brownian motion  

E-print Network

We establish an effective Markov theory for the rotational Brownian motion of hot nanobeads and nanorods. Compact analytical expressions for the effective temperature and friction are derived from the fluctuating hydrodynamic equations of motion. They are verified by comparison with recent measurements and with GPU powered parallel molecular dynamics simulations over a wide temperature range. This provides unique insights into the physics of hot Brownian motion and an excellent starting point for further experimental tests and applications involving laser-heated nanobeads, nanorods and Janus particles.

Daniel Rings; Dipanjan Chakraborty; Klaus Kroy

2012-03-14

351

The distribution of hot spots  

NASA Technical Reports Server (NTRS)

Statistical analyses are compared for two published hot spot data sets, one minimal set of 42 and another larger set of 117, using three different approaches. First, the earths surface is divided into 16 equal-area fractions and the observed distribution of hot spots among them is analyzed using chi-square tests. Second, cumulative distributions about the principal axes of the hot spot inertia tensor are used to describe hot spot distribution. Finally, a hot spot density function is constructed for each of the two hot spot data sets. The methods all indicate that hot spots have a nonuniform distribution, even when statistical fluctuations are considered. To the first order, hot spots are concentrated on one half of of the earth's surface area; within that portion, the distribution is consistent with a uniform distribution. The observed hot spot densities for neither data set are explained solely by plate speed.

Stefanick, M.; Jurdy, D. M.

1984-01-01

352

Chemistry @ Imperial College 2007 Introduction  

E-print Network

Chemistry @ Imperial College 2007 #12;2 Introduction Imperial College is a world leading University. As the central science Chemistry has been a major contributor to this success. The Chemistry Department is at the forefront of modern Chemistry research, both in our core discipline and at the interfaces of Chemistry

353

Hot-Water Worms May Use Bacteria as Shield  

NSDL National Science Digital Library

This National Geographic news article highlights research being done to study the Pompeii worm (Alvinella pompejana), the most heat tolerant complex organism on Earth, and its microscopic symbionts. Bacteria on the worms' backs act like firefighters' blankets, shielding the worms from intermittent blasts of hot, metal-rich water. Scientists are currently characterizing the chemistry of the vent environment by sequencing a large amount of DNA from the bacterial community-the metagenome. The page includes links to related National Geographic sites.

Roach, John

2009-06-17

354

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

355

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

356

DISEQUILIBRIUM CARBON, OXYGEN, AND NITROGEN CHEMISTRY IN THE ATMOSPHERES OF HD 189733b AND HD 209458b  

SciTech Connect

We have developed a one-dimensional photochemical and thermochemical kinetics and diffusion model to study the effects of disequilibrium chemistry on the atmospheric composition of 'hot-Jupiter' exoplanets. Here we investigate the coupled chemistry of neutral carbon, hydrogen, oxygen, and nitrogen species on HD 189733b and HD 209458b and we compare the model results with existing transit and eclipse observations. We find that the vertical profiles of molecular constituents are significantly affected by transport-induced quenching and photochemistry, particularly on the cooler HD 189733b; however, the warmer stratospheric temperatures on HD 209458b help maintain thermochemical equilibrium and reduce the effects of disequilibrium chemistry. For both planets, the methane and ammonia mole fractions are found to be enhanced over their equilibrium values at pressures of a few bar to less than an mbar due to transport-induced quenching, but CH{sub 4} and NH{sub 3} are photochemically removed at higher altitudes. Disequilibrium chemistry also enhances atomic species, unsaturated hydrocarbons (particularly C{sub 2}H{sub 2}), some nitriles (particularly HCN), and radicals like OH, CH{sub 3}, and NH{sub 2}. In contrast, CO, H{sub 2}O, N{sub 2}, and CO{sub 2} more closely follow their equilibrium profiles, except at pressures {approx}<1 {mu}bar, where CO, H{sub 2}O, and N{sub 2} are photochemically destroyed and CO{sub 2} is produced before its eventual high-altitude destruction. The enhanced abundances of CH{sub 4}, NH{sub 3}, and HCN are expected to affect the spectral signatures and thermal profiles of HD 189733b and other relatively cool, transiting exoplanets. We examine the sensitivity of our results to the assumed temperature structure and eddy diffusion coefficients and discuss further observational consequences of these models.

Moses, Julianne I. [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States); Visscher, C. [Lunar and Planetary Institute, Houston, TX 77058 (United States); Fortney, J. J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Showman, A. P.; Lewis, N. K.; Griffith, C. A. [Department of Planetary Sciences and Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States); Klippenstein, S. J. [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Shabram, M. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Friedson, A. J. [Earth and Space Sciences Division, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Marley, M. S.; Freedman, R. S., E-mail: jmoses@spacescience.org [NASA Ames Research Center, Moffett Field, CA 94035 (United States)

2011-08-10

357

Difficulties Implementing a Web Based PBL: Insight into Atomic Theory taught via a WebQuest  

Microsoft Academic Search

To foster student driven learning I developed a Web Quest that can teach atomic theory to a high school chemistry class. This Web Quest allows students the opportunity to examine the worlds of notable scientists that have contributed throughout time to the foundation of chemistry with their theories of atomic structure. The students' job is to defend the work of

Muhsinah L. Holmes

358

Atom interferometry  

Microsoft Academic Search

We have demonstrated an atom interferometer with completely separated beams using three 200 nm period transmission gratings.\\u000a A stretched 10 cm long and 10 ?m thick metal foil, was inserted in the interferometer so that separated portions of the atom\\u000a wave went on opposite sides of the foil. A fringe amplitude of up to 900 cps was observed, which allows

Jrg Schmiedmayer; Christopher Ekstrom; Michael Chapman; Troy Hammond; David Pritchard

359

Cold Atoms  

NASA Astrophysics Data System (ADS)

This chapter and the following one address collective effects of quantum particles, that is, the effects which are observed when we put together a large number of identical particles, for example, electrons, helium-4 or rubidium-85 atoms. We shall see that quantum particles can be classified into two categories, bosons and fermions, whose collective behavior is radically different. Bosons have a tendency to pile up in the same quantum state, while fermions have a tendency to avoid each other. We say that bosons and fermions obey two different quantum statistics, the Bose-Einstein and the Fermi-Dirac statistics, respectively. Temperature is a collective effect, and in Section 5.1 we shall explain the concept of absolute temperature and its relation to the average kinetic energy of molecules. We shall describe in Section 5.2 how we can cool atoms down thanks to the Doppler effect, and explain how cold atoms can be used to improve the accuracy of atomic clocks by a factor of about 100. The effects of quantum statistics are prominent at low temperatures, and atom cooling will be used to obtain Bose-Einstein condensates at low enough temperatures, when the atoms are bosons.

Bellac, Michel Le

2014-11-01

360

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

361

Translationally hot neutrals in etching discharges Timothy J. Sommerer and Mark J. Kushner  

E-print Network

Translationally hot neutrals in etching discharges Timothy J. Sommerer and Mark J. Kushner and intluence of translationally energetic ions in low-pressure etching discharges is well known. Neutral atoms in these plasmas. Neutral species may, however, become translationally hot through either charge exchange

Kushner, Mark

362

Silicon nanowire growth on glass substrates using hot wire chemical vapor deposition  

Microsoft Academic Search

We report here, the first observation of silicon nanowire growth via the VLS route at 400C using the HWCVD technique with gold (Au) as catalyst. The supersaturation of the alloy droplet, due to a large flux of atomic silicon generated due to efficient dissociation of the silane over the hot wire, leads to the precipitation of Si nanowires. The hot

Nagsen P. Meshram; Alka Kumbhar; R. O. Dusane

2011-01-01

363

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

364

Dr. Carnelley's Hot Ice  

Microsoft Academic Search

THE remarkable observation made by Dr. Carnelley that ice in a vacuum is very permanent, even though surrounded by and apparently in contact with very hot bodies, has caused him to suppose and maintain that the ice itself is at a high temperature; a supposition which has been apparently confirmed by preliminary calorimetric determinations. This proposition has naturally met with

Oliver J. Lodge

1881-01-01

365

Hot Dog Champ Defeated  

E-print Network

Broadcast Transcript: Arthritic jaw? Recent wisdom tooth extraction? The universe saying "It is time"? Whatever. All we know is that Japan's six year domination of Nathan's Famous July 4th Hot Dog Eating contest at Coney Island came to an end...

Hacker, Randi; Tsutsui, William; Bleier, R.H.

2007-07-25

366

Hot piston ring tests  

NASA Astrophysics Data System (ADS)

As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

Allen, David J.; Tomazic, William A.

1987-12-01

367

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

368

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.

369

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.

370

What's Hot? What's Not?  

ERIC Educational Resources Information Center

When Goldilocks finds three bowls of porridge at different temperatures in the three bears' house, she accurately assesses the situation and comes up with one of the most recognizable lines in children's literature," This porridge is too hot; this porridge is too cold; aahh, this porridge is just right!" Goldilocks' famous line is a perfect

Buczynski, Sandy

2006-01-01

371

Hot piston ring tests  

NASA Technical Reports Server (NTRS)

As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

Allen, David J.; Tomazic, William A.

1987-01-01

372

Hot corrosion of materials  

Microsoft Academic Search

Alloys and ceramics may experience accelerated corrosion at high temperatures when their surfaces are coated by a thin film of fused salt in an oxidizing environment. Because of their high thermodynamic stabilities, fused alkali sulfates are frequently deposited or condensed onto hot substrates from the combustion product gases or else by the oxidation of heavy metal contaminants in the fuel,

Robert A. Rapp

1990-01-01

373

Chlorine Chemistry Division  

NSDL National Science Digital Library

This site is provided by the American Chemistry Council's Chlorine Chemistry Division. The page contains several links that give an introduction to chlorine, its uses, and issues surrounding the chemical compound. There is also a link to the Chlorine Science Center which provides classroom activities and a chlorine compound of the month.

2008-01-02

374

High School Chemistry.  

ERIC Educational Resources Information Center

Preparation for college or life, working conditions and continuing education for high school chemistry teachers, and form/function of high school chemistry textbooks were addressed in presentations at the Seventh Biennial Conference on Chemical Education (Stillwater, Oklahoma 1982). Workshops, lectures, and demonstrations were also presented to

Journal of Chemical Education, 1983

1983-01-01

375

Selectivity in Analytical Chemistry  

NSDL National Science Digital Library

The International Union of Pure and Applied Chemistry (IUPAC) has put online a draft of recommendations for the correct use of the terms "selectivity" and "specificity" in analytical chemistry. The provisional report, available for download in .pdf format, was drafted by the IUPAC's Analytical Division Task Force, and reader comments are welcomed until September 30, 2001.

2001-01-01

376

Selectivity in Analytical Chemistry  

NSDL National Science Digital Library

The International Union of Pure and Applied Chemistry (IUPAC) has put online a draft of recommendations for the correct use of the terms "selectivity" and "specificity" in analytical chemistry. The provisional report, available for download in .pdf format, was drafted by the IUPAC's Analytical Division Task Force, and reader comments are welcomed until September 30, 2001.

2005-11-01

377

Movies in Chemistry Education  

ERIC Educational Resources Information Center

This article reviews numerous studies on chemistry movies. Movies, or moving pictures, are important elements of multimedia and signify a privileged or motivating means of presenting knowledge. Studies on chemistry movies show that the first movie productions in this field were devoted to university lectures or documentaries. Shorter movies were

Pekdag, Bulent; Le Marechal, Jean-Francois

2010-01-01

378

Environmental Chemistry Library  

NSDL National Science Digital Library

This is an "everything" site for the teaching of environmental chemistry. The site contains some unique case studies, a list of textbooks, lab and modeling activities and other educational content. The content is still in development, but the material provided would be helpful in developing a unit or course on environmental chemistry.

2011-03-31

379

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

380

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

381

Chemistry from Issues.  

ERIC Educational Resources Information Center

Describes the "Chemistry from Issues" project at Chelsea College. Provides the background information, rationale, and overall structure of a proposed course about the importance of chemistry to common culture. Outlines one module about the British steel industry that has been taught at King's College. (TW)

Harding, Jan; Donaldson, Jim

1986-01-01

382

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

383

Hot helium flow test facility summary report  

SciTech Connect

This report summarizes the results of a study conducted to assess the feasibility and cost of modifying an existing circulator test facility (CTF) at General Atomic Company (GA). The CTF originally was built to test the Delmarva Power and Light Co. steam-driven circulator. This circulator, as modified, could provide a source of hot, pressurized helium for high-temperature gas-cooled reactor (HTGR) and gas-cooled fast breeder reactor (GCFR) component testing. To achieve this purpose, a high-temperature impeller would be installed on the existing machine. The projected range of tests which could be conducted for the project is also presented, along with corresponding cost considerations.

Not Available

1980-06-01

384

Exercising Safely in Hot Weather  

MedlinePLUS

... older adults and people with health problems. Being hot for too long can cause hyperthermiaa heat- ... those who want to be active when its hot outside: l Check the weather forecast. If its ...

385

Hot Tub Rash (Pseudomonas Folliculitis)  

MedlinePLUS

newsletter | contact Share | Hot Tub Rash ( Pseudomonas Folliculitis) Information for adults A A A This image displays follicular elevations of the skin and small pus-filled lesions. Overview Hot tub rash ( Pseudomonas folliculitis) is an infection of ...

386

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

387

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

388

Chemistry 675 (CHE 675) Advanced Organic Chemistry  

E-print Network

, with required reading assignments given on the syllabus. Learning outcomes Upon completion of this course, a student should have mastered the following areas / skills: Understand the structure of organic molecules of interest Gain an appreciation of the current state of mechanistic investigation in chemistry and related

Mather, Patrick T.

389

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

390

Atomic force microscopy and x-ray photoelectron spectroscopy investigations of the morphology and chemistry of a PdCl{sub 2}/SnCl{sub 2} electroless plating catalysis system adsorbed onto shape memory alloy particles  

SciTech Connect

A study of the different stages of the electroless deposition of copper on micronic NiTi shape memory alloy particles activated by one-step and two-step methods has been conducted from both a chemical and a morphological point of view. The combination of x-ray photoelectron spectroscopy (XPS) measurements and atomic force microscopy (AFM) imaging has allowed detection of the distribution of the formed compounds and depth quantification and estimation of the surface topographic parameters. For the two-step method, at the sensitization of the early stages, it is observed by AFM that Sn is absorbed in form of clusters that tend to completely cover the surface and form a continuous film. XPS analysis have shown that Sn and Pd are first absorbed in form of oxide (SnO{sub 2} and PdO) and hydroxide [Sn(OH){sub 4}]. After the entire sensitization step, the NiTi substrate is covered with Sn-based compounds. After the sensitization and the activation steps the powder roughness increases. Behavior of the Sn and Pd growth for the one-step method does not follow the behavior found for the two-step method. Indeed, XPS analysis shows a three-dimensional (3D) growth of Pd clusters on top of a mixture of metallic tin, oxide (SnO) and hydroxide [Sn(OH){sub 2}]. These Pd clusters are covered with a thin layer of Pd-oxide contamination induced by the electroless process. The mean roughness for the one-step and two-step processes are equivalent. After copper deposition, the decrease of mean roughness is attributed to a filling of surface valleys, observed after the Sn-Pd coating step.

Silvain, J.F.; Fouassier, O.; Lescaux, S. [Institut de Chimie de la Matiere Condensee de Bordeaux (ICMCB) - CNRS, Universite de Bordeaux 1, 87 Avenue du Dr A. Schweitzer, F-33608 PESSAC (France); Veeco, Z.I. de la Gaudree, 11 Rue Marie Poussepin, F-91412 Dourdain (France)

2004-11-01

391

AtomicAtomicAtomicAtomic pncpncpncpnc theory:theory:theory:theory: current stAtus Andcurrent stAtus Andcurrent stAtus Andcurrent stAtus And  

E-print Network

· Astrophysics · Actinide ion studies for chemistry models · State-insensitive cooling and trapping · Atomic of Colorado Searches for new physics beyond the Standard Model motivAtion: pnc imotivAtion: pnc imotiv · Analysis of various experiments · Study of long-range interactions · Other nuclear physics applications

Safronova, Marianna

392

Automatic hot water recovery system  

SciTech Connect

A heat recovery system recovers hot water to an insulated tank through reciprocally variable volume chambers which are biased to draw water from hot water lines when the pressure throughout the system is equalized. One-way valving means permits continuous water flow when desired through the hot water tank to the hot water outlet. In a specific embodiment, bias is effected by a piston having opposing faces of unequal area forming reciprocally moving walls of the chambers.

Haws, S. K.

1985-05-21

393

The Hot Particles Data Base  

Microsoft Academic Search

During 19871996, more than 1,800 Chernobyl hot particles were selected by scanning thin soil layers with a dosimeter. Size\\u000a and radionuclides activity in hot particles were measurement. The Hot particles database (in Microsoft Access) was created\\u000a by integrating this information and complemented with data on hot particles sampled in 1986 in Poland and inside of the Shelter.\\u000a This database is

Marina Zhurba; Valery Kashparov; Noureddine Ahamdach; Brit Salbu; Vasyl Yoschenko; Svyatolslav Levchuk

394

Sulfur Donor Atom Effects on Copper(I)/O2 Chemistry with Thioanisole Containing Tetradentate N3S Ligand Leading to ?-1,2-Peroxo-Dicopper(II) species  

PubMed Central

To better understand the effect of thioether coordination in copper-O2 chemistry, the tetradentate N3S ligand LASM (2-(methylthio)-N,N-bis((pyridin-2-yl)methyl)benzenamine) and related alkylether ligand LEOE (2-ethoxy-N,N-bis((pyridin-2-yl)methyl)ethanamine) have been studied. The corresponding copper(I) complexes, [(LASM)CuI]+ (1a) and [(LEOE)CuI]+ (3a) were studies as were the related compound [(LESE)CuI]+ (2a, LESE = (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 CH3CN and 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 [(LASM)CuII(CH3OH)]2+ (1c) and [(LESE)CuII(CH3OH)]2+ (2c) have also been obtained and indicate nearly identical copper coordination environments. Oxygenation of 1a at reduced temperature gives a characteristic deep blue colored intermediate [{(LASM)CuII}2(O22?)]2+ (1bP) with absorption features at 442 (1,500 M?1cm?1), 530 (8,600 M?1cm?1) and 605 nm (10,400 M?1cm?1); these values compare well to the LMCT transitions previously reported for [{(LESE)CuII}2(O22?)]2+ (2bP). Resonance Raman data for [{(LASM)CuII}2(O22?)]2+ (1bP) support the formation of ?-1,2-peroxo species (?(O-O) = 828 cm?1 (?(18O2) = 48), ?sym(Cu-O) = 547 cm?1 (?(18O2) = 23) and ?asym(Cu-O) = 497 cm?1 (?(18O2) = 22) and suggest the LASM ligand is a poorer electron donor to copper than is LESE. In contrast, the oxygenation of [(LEOE)CuI]+ (3a), possessing an ether donor as an analogue of the thioether in LESE, led to the formation of a bis(?-oxo) species [{(LEOE)CuIII}2(O2?)2]2+ (3bO; 380 nm, ? ~ 10,000 M?1cm?1). This result provides further support for the sulfur influence in 1bP and 2bP, in particular coordination of the sulfur to the Cu. Thermal decomposition of 1bP is accompanied by ligand sulfoxidation. The structure of [{(LEOE)CuII(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 1bP, 2bP and 3bO is presented. PMID:20822156

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

2010-01-01

395

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 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

2010-01-08

396

Oil recovery by hot waterflooding  

Microsoft Academic Search

Injection of hot water into an oil-bearing formation to increase oil recovery has been known almost as long as conventional waterflooding. In many instances, hot water has been injected in order to increase the injectivity of wells by controlling the deposition of waxes. With the growing interest in steam-flooding during recent years, hot waterflooding has also been gaining prominence. This

Farouq Ali

1968-01-01

397

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

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

Microstructure Evolution of Gas Atomized Iron Based ODS Alloys  

SciTech Connect

In a simplified process to produce precursor powders for oxide dispersion-strengthened (ODS) alloys, gas-atomization reaction synthesis (GARS) was used to induce a surface oxide layer on molten droplets of three differing erritic stainless steel alloys during break-up and rapid solidification. The chemistry of the surface oxide was identified using auger electron spectroscopy (AES) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The precursor iron-base powders were consolidated at 850 C and 1,300 C using hot isostatic pressing (HIPing). Consolidation at the lower temperature resulted in a fully dense microstructure, while preventing substantial prior particle-boundary-oxide dissociation. Microstructural analysis of the alloys consolidated at the higher temperature confirmed a significant reduction in prior-particle-boundary-oxide volume fraction, in comparison with the lower-temperature-consolidated sample. This provided evidence that a high-temperature internal oxygen-exchange reaction occurred between the metastable prior particle-boundary-oxide phase (chromium oxide) and the yttrium contained within each prior particle. This internal oxygen-exchange reaction is shown to result in the formation of yttrium-enriched oxide dispersoids throughout the alloy microstructure. The evolving microstructure was characterized using transmission electron microscopy (TEM) and high-energy X-ray diffraction (HE-XRD).

Rieken, J.R.; Anderson, I.E.; Kramer, M.J.

2011-08-09

400

Microstructure Evolution of Gas Atomized Iron Based ODS Alloys  

SciTech Connect

In a simplified process to produce precursor powders for oxide dispersion-strength- ened (ODS) alloys, gas-atomization reaction synthesis (GARS) was used to induce a surface oxide layer on molten droplets of three differing erritic stainless steel alloys during break-up and rapid solidification. The chemistry of the surface oxide was identified using auger electron spectroscopy (AES) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The precursor iron-base powders were consolidated at 850 C and 1,300 C using hot isostatic pressing (HIPing). Consolidation at the lower temperature resulted in a fully dense microstructure, while preventing substantial prior particle-boundary-oxide dissociation. Microstructural analysis of the alloys consolidated at the higher temperature confirmed a significant reduction in prior-particle-boundary-oxide volume fraction, in comparison with the lower-temperature-consolidated sample. This provided evidence that a high-temperature internal oxygen-exchange reaction occurred between the metastable prior particle-boundary-oxide phase (chromium oxide) and the yttrium contained within each prior particle. This internal oxygen-exchange reaction is shown to result in the formation of yttrium-enriched oxide dispersoids throughout the alloy microstructure. The evolving microstructure was characterized using transmission electron microscopy (TEM) and high-energy X-ray diffraction (HE-XRD).

Rieken, J.R.; Anderson, I.E.; Kramer, M.J.; Anderegg, J.W.; Shechtman, D.

2009-12-01

401

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

402

Hot Spring Metagenomics  

PubMed Central

Hot springs have been investigated since the XIX century, but isolation and examination of their thermophilic microbial inhabitants did not start until the 1950s. Many thermophilic microorganisms and their viruses have since been discovered, although the real complexity of thermal communities was envisaged when research based on PCR amplification of the 16S rRNA genes arose. Thereafter, the possibility of cloning and sequencing the total environmental DNA, defined as metagenome, and the study of the genes rescued in the metagenomic libraries and assemblies made it possible to gain a more comprehensive understanding of microbial communitiestheir diversity, structure, the interactions existing between their components, and the factors shaping the nature of these communities. In the last decade, hot springs have been a source of thermophilic enzymes of industrial interest, encouraging further study of the poorly understood diversity of microbial life in these habitats.

Lopez-Lopez, Olalla; Cerdan, Maria Esperanza; Gonzalez-Siso, Maria Isabel

2013-01-01

403

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

404

The hot chocolate effect  

NASA Astrophysics Data System (ADS)

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, Frank S.

1982-05-01

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

Chemistry in Bioinformatics  

E-print Network

F R O N T M A T T E R Chemistry in Bioinformatics Peter Murray?Rust,1 John B. O. Mitchell,1 and Henry S. Rzepa2 1 Unilever Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge. CB2... 1EW, UK. 2 Department of Chemistry, Imperial College London, SW7 2AY, UK. Abstract Chemical information is now seen as critical for most areas of life sciences. But unlike Bioinformatics, where data is Openly available and freely re...

Murray-Rust, Peter; Mitchell, John B O; Rzepa, Henry S

2005-05-19

407

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.

408

Chemistry in Bioinformatics  

E-print Network

ral ssBioMed CentBMC Bioinformatics Open AcceChemistry in Bioinformatics Peter Murray-Rust1, John BO Mitchell1 and Henry S Rzepa*2 Address: 1Unilever Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge... , Lensfield Road, Cambridge. CB2 1EW, UK. and 2Department of Chemistry, Imperial College London, SW7 2AY, UK. Email: Peter Murray-Rust - pm286@cam.ac.uk; John BO Mitchell - jbom1@cam.ac.uk; Henry S Rzepa* - rzepa@ic.ac.uk * Corresponding author Equal...

Murray-Rust, Peter; Mitchell, John B O; Rzepa, Henry S

2005-06-07

409

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.

National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs,

410

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.

411

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.

412

Critical Nuclear Charges for N-Electron Atoms  

E-print Network

Critical Nuclear Charges for N-Electron Atoms ALEXEI V. SERGEEV, SABRE KAIS Department of Chemistry is proposed to describe the motion of a loosely bound electron in a multielectron atom when the nuclear charge, which is treated as a continuous parameter, approaches its critical value. The critical nuclear charge

Kais, Sabre

413

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

414

I. Required core Chemistry Courses (1905 & 1925) Chemistry  

E-print Network

Advisor: Advisee: I. Required core Chemistry Courses (1905 & 1925) Chemistry CH 111 PY 211 _____ PY 212 _____ (or PY 242 _____ or PY 252 ______) II. Chemistry Options (one required) 1905 (Concentration in Chemistry) Option A (2 advanced CH courses, 401 or higher, only one may

415

National Chemistry Week Theme: "Candy: The Sweet Side of Chemistry"  

E-print Network

National Chemistry Week Theme: "Candy: The Sweet Side of Chemistry" Super Science Saturday Saturday-on chemistry and science demonstrations! All students & families are welcome! Fun & educational for all ages! Sponsored by: American Chemical Society LSU Department of Chemistry LSU Athletic Department Free admission

Stephens, Jacqueline

416

INSTRUMENTAL METHODS IN PHYSICAL CHEMISTRY Chemistry 434 Syllabus ----Fall 10  

E-print Network

INSTRUMENTAL METHODS IN PHYSICAL CHEMISTRY Chemistry 434 Syllabus ---- Fall 10 Instructor Dr-11:15A Text: Handouts in Class Supplements (all optional): Experimental Physical Chemistry, 2nd ed, Arthur Halpern Experiments in Physical Chemistry, 6th ed, Shoemaker, Garland, and Nibler Building

Wagner, Diane

417

Longitudinal chemical gradients in hot Jupiter atmospheres  

NASA Astrophysics Data System (ADS)

We have built a pseudo two-dimensional (altitude and longitude) model to study the chemistry in the atmosphere of hot Jupiters. Our model considers a vertical column of atmosphere that rotates along the equator, mimicking a superrotating wind. We have applied it to the well known exoplanets HD 209458b and HD 189733b. We find that below a certain pressure level, which may be located somewhere between 10 bar and 10 mbar depending on the molecule, the chemical composition is given by thermochemical equilibrium, while about such level, the dynamical time scales for vertical and horizontal mixing compete producing a complex abundance distribution with altitude and longitude. A main conclusion of our study is that some molecules such as CO, H2O, and N2 maintain rather constant abundances with altitude and longitude while others such as CO2, CH4, NH3, and HCN show important abundance gradients as a function of longitude.

Agundez, M.; Parmentier, V.; Venot, O.; Selsis, F.

2013-09-01

418

Working in Hot Weather or Hot Workplace Environments Subject: Procedures and Guidelines for Working in Hot Environments  

E-print Network

Working in Hot Weather or Hot Workplace Environments Subject: Procedures and Guidelines for Working is intended to prevent potential heat induced illness as a result of hot weather or hot workplace environments in hot weather or hot workplace environments. The following parameters will serve as triggers

Lennard, William N.

419

Planetary atoms  

Microsoft Academic Search

We have experimentally observed the systematic onset of strong mixing of confirugations in core-excited autoionization states of Ba as a function of excitation level of the core electron relative to the Rydberg electron. This behavior was originally suggested by Percival in his discussion of Planetary Atoms.

W. Cooke; L. Bloomfield; R. Freeman; J. Bokor

420

Planetary atoms  

Microsoft Academic Search

We have experimentally observed the systematic onset of strong mixing of confirugations in core-excited autoionization states of Ba as a function of excitation level of the core electron relative to the Rydberg electron. This behavior was originally suggested by Percival in his discussion of Planetary Atoms.

W. E. Cooke; L. A. Bloomfield; R. R. Freeman; J. Bokor

1985-01-01

421

Atomic Spectra  

NSDL National Science Digital Library

In this Flash animation the user can view the atomic emission spectra (400-700nm) of eight different elements. A dragable marker allows the user to approximate the wavelength of the various spectral lines. The effect of resolution can be examined in the sodium spectrum in the region 550-600nm.

422

Chemistry-Based QuickTime, Shockwave Flash, GIF Animations, and Streaming Audio  

NSDL National Science Digital Library

The Chemistry-Based QuickTime, Shockwave Flash, GIF Animations, and Streaming Audio Web site is provided to "support the teaching of concepts in chemistry in freshman through graduate level courses." Dr. Thomas Chasteen's site offers links to multimedia files related to chemiluminescence, gel electrophoresis, how a grating works, gas chromatography and mass spectrometry, titrations, atomic emission detector, and much more. The site is a good collection of helpful visual learning tools that chemistry students will surly appreciate.

Chasteen, Thomas G.

1969-12-31

423

Learn Chemistry: Chemistry Resources for Teachers  

NSDL National Science Digital Library

The Royal Society of Chemistry has created this most useful website to help teachers and students of chemistry learn about the field via interactive experiments, diagrams, animations, and so on. The site includes over 3,300 resources. Visitors can get started by using the Resource Type tab. Here they can browse through ten different headings, including Worksheet, Quiz, Tutorial, and Podcast. The Experiments area is quite wonderful, as it includes over 340 different experiments that can be conducted in the classroom. A few highlights in this area include "Challenging Medicines: Making Medicines," "The Salt Cellar Mystery," and "Which solution is which?" Overall, it's a tremendous site and one that visitors will want to share with friends.

424

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

425

High School Chemistry.  

ERIC Educational Resources Information Center

Summarizes papers presented at the Sixth Biennial Conference on Chemical Education in the area of high school chemistry, particularly dealing with the high school/college interface. A bibliography of 16 presented papers on this topic is attached. (CS)

Journal of Chemical Education, 1981

1981-01-01

426

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

427

Sequencing General Chemistry  

NSDL National Science Digital Library

The material in the authors' general chemistry curriculum has been rearranged into a sequence thought to be more logical to students than the traditional sequence. This fresh approach does not radically change course content but rather produces a systemat

Yoblinski, B. J.

2003-03-01

428

Chemistry for Nonscientists  

ERIC Educational Resources Information Center

Discusses the case of DDT which can be introduced to nonscience students in a chemistry course, including the development of DDT, problems associated with its adverse effects, and curtailment of its use in our environments. (CC)

Weil, Thomas A.; And Others

1974-01-01

429

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.

430

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

431

Chemistry and Detective Fiction.  

ERIC Educational Resources Information Center

Describes an interdisciplinary program consisting of two courses. The first course deals with the chemistry of drugs and poisons; the second course focuses on fictional works in which these drugs and poisons are central to the plots. (SK)

Labianca, Dominick A.; Reeves, William J.

1981-01-01

432

Supplemental instruction in chemistry  

NASA Astrophysics Data System (ADS)

This study was designed to measure some effects of supplemental instruction in chemistry. Supplemental instruction is a peer-led cooperative learning program that encourages students to develop conceptual understanding by articulating both understandings and misconceptions in a think-aloud fashion. Supplemental instruction was offered three hours weekly outside of class and lab time for students in four classes of General Organic and Biological Chemistry. Over a two-year period 108 students volunteered to participate in this program; 45 students did not participate. As measured by final grades in chemistry and responses to a questionnaire, supplemental instruction was effective in increasing students' achievement in chemistry. Further research is needed to determine the in-depth effects of supplemental instruction on students' learning, problem solving, and self-esteem.

Lundeberg, Mary A.

433

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

434

Environmental Bioinorganic Chemistry  

ERIC Educational Resources Information Center

Discusses some important aspects of bioinorganic chemistry, including interactions of organisms with metallic and nonmetallic elements and compounds. Indicates that many environmental problems are created by human exploitation of nature and technologies if studied from a bioinorganic chemical viewpoint. (CC)

Ochiai, Ei-Ichiro

1974-01-01

435

Making Chemistry Relevant  

ERIC Educational Resources Information Center

Discusses the conduct of a general inorganic chemistry course in a community junior college with emphases upon students' participation and interests. Included are a list of proposed topics and two samples of evaluation sheet. (CC)

Suter, Patricia H.

1974-01-01

436

Enzymes in Analytical Chemistry.  

ERIC Educational Resources Information Center

Presents tabular information concerning recent research in the field of enzymes in analytic chemistry, with methods, substrate or reaction catalyzed, assay, comments and references listed. The table refers to 128 references. Also listed are 13 general citations. (CS)

Fishman, Myer M.

1980-01-01

437

Chemistry 455 Chemical Nanotechnology  

E-print Network

Chemistry 455 Chemical Nanotechnology 4 units Prof. Richard Brutchey, Fall 2014 (Lecture = 12:00�12:50 pm MWF) CHEM 455 is an upper-division undergraduate course in Chemical Nanotechnology. The intent

Rohs, Remo

438

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

439

Connected ChemistryIncorporating Interactive Simulations into the Chemistry Classroom  

Microsoft Academic Search

The aim of this paper is to describe a novel modeling and simulation package, connected chemistry, and assess its impact on students' understanding of chemistry. Connected chemistry was implemented inside the NetLogo modeling environment. Its design goal is to present a variety of chemistry concepts from the perspective of emergent phenomenathat is, how macro-level patterns in chemistry result from the

Mike Stieff; Uri Wilensky

2003-01-01

440

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

441

Multiscale models of atmospheric mercury: bromine chemistry, air-sea exchange, and global transport  

E-print Network

Multiscale models of atmospheric mercury: bromine chemistry, air-sea exchange, and global transport Multiscale models of atmospheric mercury: bromine chemistry, air-sea exchange, and global transport Abstract by atomic bromine (Br) in the tropo- sphere by combining kinetic data for the Hg-Br system with modeled

Holmes, Christopher D.

442

CHEMISTRY 324W ORGANIC LABORATORY  

E-print Network

1 Fall 2010 CHEMISTRY 324W ORGANIC LABORATORY Course Information Title: Chemistry 324W, Organic for multiple chemistry classes) $5 key deposit fee (refunded at end of semester with return of key) Course a scientific paper consistent with the format of the Journal of Organic Chemistry, American Chemical Society. 7

Wagner, Diane

443

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

444

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

445

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. PMID:20880833

Somorjai, Gabor A.; Li, Yimin

2011-01-01

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

NASA: Aura Atmospheric Chemistry  

NSDL National Science Digital Library

Aura is the EOS chemistry mission which aims to answer three important questions: is the ozone layer recovering, is air quality getting worse, and is the Earth's climate changing? Aura will continue the long term series of atmospheric chemistry measurements made by earlier missions. The Aura spacecraft operates in a 705 km sun-synchronous polar orbit, with an ascending equator crossing at 1:45 PM. On the site, visitors will find an overview of the mission, documentation, tools, links, and FAQs.

2007-05-14

448

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

449

EPA Environmental Chemistry Laboratory  

NASA Technical Reports Server (NTRS)

The Environmental Protection Agency's (EPA) Chemistry Laboratory (ECL) is a national program laboratory specializing in residue chemistry analysis under the jurisdiction of the EPA's Office of Pesticide Programs in Washington, D.C. At Stennis Space Center, the laboratory's work supports many federal anti-pollution laws. The laboratory analyzes environmental and human samples to determine the presence and amount of agricultural chemicals and related substances. Pictured, ECL chemists analyze environmental and human samples for the presence of pesticides and other pollutants.

1993-01-01

450

Quantitative quantum chemistry  

Microsoft Academic Search

We review the current status of quantum chemistry as a predictive tool of chemistry and molecular physics, capable of providing highly accurate, quantitative data about molecular systems. We begin by reviewing wave-function based electronic-structure theory, emphasizing the N-electron hierarchy of coupled-cluster theory and the one-electron hierarchy of correlation-consistent basis sets. Following a discussion of the slow basis-set convergence of dynamical

Trygve Helgaker; Wim Klopper; David P. Tew

2008-01-01

451

Atomic Structure: Properties of Atoms  

NSDL National Science Digital Library

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of three Science Objects in the Atomic Structure SciPack. It explores the

National Science Teachers Association (NSTA)

2010-05-24

452

Ethylene oxide and Acetaldehyde in hot cores  

E-print Network

[Abridged] Ethylene oxide and its isomer acetaldehyde are important complex organic molecules because of their potential role in the formation of amino acids. Despite the fact that acetaldehyde is ubiquitous in the interstellar medium, ethylene oxide has not yet been detected in cold sources. We aim to understand the chemistry of the formation and loss of ethylene oxide in hot and cold interstellar objects (i) by including in a revised gas-grain network some recent experimental results on grain surfaces and (ii) by comparison with the chemical behaviour of its isomer, acetaldehyde. We test the code for the case of a hot core. The model allows us to predict the gaseous and solid ethylene oxide abundances during a cooling-down phase prior to star formation and during the subsequent warm-up phase. We can therefore predict at what temperatures ethylene oxide forms on grain surfaces and at what temperature it starts to desorb into the gas phase. The model reproduces the observed gaseous abundances of ethylene oxid...

Occhiogrosso, A; Herbst, E; Viti, S; Ward, M D; Price, S D; Brown, W A

2014-01-01

453

Hot Molecular Cores in Infrared Dark Clouds  

NASA Astrophysics Data System (ADS)

We present high angular resolution continuum images and molecular line spectra obtained at 345 GHz with the Submillimeter Array (SMA) toward two massive cores that lie within Infrared Dark Clouds (IRDCs): G034.43+00.24 MM1 and G024.33+00.11 MM1. Both of these cores contain bright, unresolved (<2'') objects that have previously been imaged in the millimeter/submillimeter continuum with the Institut de RadioAstronomie Millimtrique (IRAM) Plateau de Bure Interferometer and SMA and show complex molecular line chemistry. The new, higher angular resolution SMA continuum images reveal that both cores contain massive (8, 26 M ?), unresolved (0farcs6; ~3000 AU) continuum emission features and emission from many complex molecular transitions, which confirm that these are hot molecular cores, an early stage in the formation of a high-mass star. Because these hot cores are located within IRDCs, they may well represent the very earliest phases in the formation of high-mass protostars and, hence, their detailed study may reveal the initial conditions within high-mass star-forming cores, before they are shredded apart by stellar winds and radiation.

Rathborne, J. M.; Garay, G.; Jackson, J. M.; Longmore, S.; Zhang, Q.; Simon, R.

2011-11-01

454

History of Atomic Theory  

NSDL National Science Digital Library

Students research websites to find how the atomic theory has developed over the years. Ancient Greek Atoms shapes and sizes Read carefully on this website to find what Democritus thought about the shapes of atoms. Wikibooks Democritus Property of Atoms Atom Builder Atomic Magic Heisenberg (Wave Model Atomic Models PDF Handout Short and sweet and to the point for many of the atomic models used. Atomic Models Webquest Nice pictures of five models plus useful links. Atomic Theories Easy to read Data Table Atomic Theory Atomic Theory Atomic Theory Useful, includes illustration of ...

Mcnees, Mrs.

2010-10-26

455

Hot oiling spreadsheet  

SciTech Connect

One of the most common oil-field treatments is hot oiling to remove paraffin from wells. Even though the practice is common, the thermal effectiveness of the process is not commonly understood. In order for producers to easily understand the thermodynamics of hot oiling, a simple tool is needed for estimating downhole temperatures. Such a tool has been developed that was distributed as a compiled, public-domain-software spreadsheet. That spreadsheet has evolved into an interactive from on the World Wide Web and has been adapted into a Windows{trademark} program by Petrolite, St. Louis MO. The development of such a tools was facilitated by expressing downhole temperatures in terms of analytic formulas. Considerable algebraic work is required to develop such formulas. Also, the data describing hot oiling is customarily a mixture of practical units that must be converted to a consistent set of units. To facilitate the algebraic manipulations and to assure unit conversions are correct, during development parallel calculations were made using the spreadsheet and a symbolic mathematics program. Derivation of the formulas considered falling film flow in the annulus and started from the transient differential equations so that the effects of the heat capacity of the tubing and casing could be included. While this approach to developing a software product does not have the power and sophistication of a finite element or difference code, it produces a user friendly product that implements the equations solved with a minimum potential for bugs. This allows emphasis in development of the product to be placed on the physics.

Mansure, A.J. [Sandia National Labs., Albuquerque, NM (United States). Geothermal Research Dept.

1996-09-01

456

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

457

Education & Experience B.S. Chemistry, University of California  

E-print Network

) Henry Dreyfus Teacher-Scholar Award (2001) U.S. Presidential Early Career Award for Scientists Award (1993) David L. Patrick Professor of Chemistry Tel 360-650-3128 Western Washington University Fax 360-650-2826 516 High St., Bellingham, WA 98225 david.patrick@wwu.edu http://atom.chem.wwu.edu/dept/facstaff/dpatrick/patrick

Patrick, David L.

458

A Sub-Symbolic Artificial Chemistry Adam Faulconbridge1  

E-print Network

RBN-World A Sub-Symbolic Artificial Chemistry Adam Faulconbridge1 , Susan Stepney2 , Julian F). However, real-world atoms have internal structure (e.g. electron shells) that is not incorporated higher-level structures (e.g. the breakage of bonds where catalysts separate from their products

Stepney, Susan

459

E Pluribus Tres: The 2009 Nobel Prize in Chemistry  

PubMed Central

Summary This years Nobel Prize in Chemistry celebrates a multitude of research areas, making the difficult selection of those most responsible for providing atomic details of the nanomachine that makes proteins according to genetic instructions. The Ribosome and RNA polymerase (recognized in 2006) structures highlight a puzzling asymmetry at the origins of biology. PMID:20004159

Carter, Charles W.

2009-01-01

460

CHM 1050, Section 02 Honors General Chemistry I  

E-print Network

. Combinations of only about a hundred of atoms in the periodic table give rise to the immense variety of known and historically played a major role in the formulation of the periodic table. The course "Honors General Chemistry by Silberberg. Topics include measurement and dimensional analysis, classification of matter, periodic

Zakarian, Armen

461

Dissociation of the Ethyl Radical: An Exercise in Computational Chemistry  

ERIC Educational Resources Information Center

A set of exercises for use in a typical physical chemistry laboratory course are described, modeling the unimolecular dissociation of the ethyl radical to form ethylene and atomic hydrogen. Students analyze the computational results both qualitatively and quantitatively. Qualitative structural changes are compared to approximate predicted values

Nassabeh, Nahal; Tran, Mark; Fleming, Patrick E.

2014-01-01

462

Hot air drum evaporator  

DOEpatents

An evaporation system for aqueous radioactive waste uses standard 30 and 55 gallon drums. Waste solutions form cascading water sprays as they pass over a number of trays arranged in a vertical stack within a drum. Hot dry air is circulated radially of the drum through the water sprays thereby removing water vapor. The system is encased in concrete to prevent exposure to radioactivity. The use of standard 30 and 55 gallon drums permits an inexpensive compact modular design that is readily disposable, thus eliminating maintenance and radiation build-up problems encountered with conventional evaporation systems.

Black, Roger L. (Idaho Falls, ID)

1981-01-01

463

Hot cell examination table  

DOEpatents

A table for use in a hot cell or similar controlled environment for use in examining specimens. The table has a movable table top that can be moved relative to a table frame. A shaft is fixedly mounted to the frame for axial rotation. A shaft traveler having a plurality of tilted rollers biased against the shaft is connected to the table top such that rotation of the shaft causes the shaft traveler to roll along the shaft. An electromagnetic drive is connected to the shaft and the frame for controllably rotating the shaft.

Gaal, Peter S. (Monroeville, PA); Ebejer, Lino P. (Weston, MA); Kareis, James H. (Slickville, PA); Schlegel, Gary L. (McKeesport, PA)

1991-01-01

464

Hot dry rock geothermal site evaluation, Western Snake River Plain, Idaho  

Microsoft Academic Search

Geologic, geophysical, hydrologic, and water chemistry studies have been performed to evaluate a hot dry rock geothermal prospect along the northern margin of the Western Snake River Plain, Idaho. The potential reservoir rock, Idaho Batholith granite, outcrops just north of the site, and is step faulted down to the south; it is more than 3 km deep in the southern

B. H. Arney; J. H. Beyer; D. B. Simon; F. B. Tonani; R. B. Weiss

1980-01-01

465

Altering graphene line defect properties using chemistry  

NASA Astrophysics Data System (ADS)

First-principles calculations are presented of a fundamental topological line defect in graphene that was observed and reported in Nature Nanotech. 5, 326 (2010). These calculations show that atoms and smaller molecules can bind covalently to the surface in the vicinity of the graphene line defect. It is also shown that the chemistry at the line defect has a strong effect on its electronic and magnetic properties, e.g. the ferromagnetically aligned moments along the line defect can be quenched by some adsorbates. The strong effect of the adsorbates on the line defect properties can be understood by examining how these adsorbates affect the boundary-localized states in the vicinity of the Fermi level. We also expect that the line defect chemistry will significantly affect the scattering properties of incident low-energy particles approaching it from graphene.

Vasudevan, Smitha; White, Carter; Gunlycke, Daniel

2012-02-01

466

Atomic force microscope mediated chromatography.  

PubMed

An atomic force microscope (AFM) is presented as an instrument for rapid, miniaturized chromatography. The AFM is used to inject a sample, provide shear driven liquid flow over a functionalized substrate, and detect separated components. The components are then analyzed with surface enhanced Raman spectroscopy using AFM deposition of gold nanoparticles on the separated bands. This AFM mediated chromatography (AFM-MC) is demonstrated using lipophilic dyes and normal phase chemistry. A significant reduction in both size and separation time scales is achieved with 25 ?m length scale and 1 s separation times. AFM-MC has general applications to trace chemical analysis and microfluidics. PMID:23464258

Anderson, M S

2013-02-01

467

Chemistry Student Handbook College of Science  

E-print Network

Chemistry Student Handbook College of Science React. Science #12;Contents 2 Welcome to the Department of Chemistry 2 Course Advice 3 What is Chemistry? 4 Career Profiles in Chemistry 5 An Undergraduate Degree in Chemistry 6 Chemistry Streams 13 Chemistry Honours Programme 14 Research

Hickman, Mark

468

Hot, Dry and Cloudy  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Click on the image for movie of Hot, Dry and Cloudy

This artist's concept shows a cloudy Jupiter-like planet that orbits very close to its fiery hot star. NASA's Spitzer Space Telescope was recently used to capture spectra, or molecular fingerprints, of two 'hot Jupiter' worlds like the one depicted here. This is the first time a spectrum has ever been obtained for an exoplanet, or a planet beyond our solar system.

The ground-breaking observations were made with Spitzer's spectrograph, which pries apart infrared light into its basic wavelengths, revealing the 'fingerprints' of molecules imprinted inside. Spitzer studied two planets, HD 209458b and HD 189733b, both of which were found, surprisingly, to have no water in the tops of their atmospheres. The results suggest that the hot planets are socked in with dry, high clouds, which are obscuring water that lies underneath. In addition, HD209458b showed hints of silicates, suggesting that the high clouds on that planet contain very fine sand-like particles.

Capturing the spectra from the two hot-Jupiter planets was no easy feat. The planets cannot be distinguished from their stars and instead appear to telescopes as single blurs of light. One way to get around this is through what is known as the secondary eclipse technique. In this method, changes in the total light from a so-called transiting planet system are measured as a planet is eclipsed by its star, vanishing from our Earthly point of view. The dip in observed light can then be attributed to the planet alone.

This technique, first used by Spitzer in 2005 to directly detect the light from an exoplanet, currently only works at infrared wavelengths, where the differences in brightness between the planet and star are less, and the planet's light is easier to pick out. For example, if the experiment had been done in visible light, the total light from the system would appear to be unchanged, even as the planet disappeared from view.

To capture spectra of the planets, Spitzer observed their secondary eclipses with its spectrograph. It took a spectrum of a star together with its planet, then, as the planet disappeared from view, a spectrum of just the star. By subtracting the spectrum of the star from the spectrum of the star and planet together, astronomers were able to determine the spectrum of the planet itself.

Neither of the parent stars for HD 209458b or HD 189733b can be seen with the naked eye. HD 209458b is located about 153 light-years away in the constellation Pegasus, while HD 189733b is about 62 light-years away in the constellation Vulpecula. Both planets zip around their stars in very tight orbits; HD 209458b circles once every 3.5 days, while HD 189733b orbits once every 2.2 days.

Of the approximately 200 known exoplanets, there are 12 besides HD 209458b and HD 189733b whose orbits are inclined in such a way that, from our point of view, they pass in front of their stars. At least three of these transiting exoplanets are bright enough to follow in the footsteps of HD 209458b and HD 189733 and reveal their infrared spectra to Spitzer. Astronomers hope to use Spitzer's spectrograph in the future to study HD 209458b and HD 189733b again in much greater detail, and to examine some of the other candidates for the first time.

2007-01-01

469

Technetium Chemistry in HLW  

SciTech Connect

Tc contamination is found within the DOE complex at those sites whose mission involved extraction of plutonium from irradiated uranium fuel or isotopic enrichment of uranium. At the Hanford Site, chemical separations and extraction processes generated large amounts of high level and transuranic wastes that are currently stored in underground tanks. The waste from these extraction processes is currently stored in underground High Level Waste (HLW) tanks. However, the chemistry of the HLW in any given tank is greatly complicated by repeated efforts to reduce volume and recover isotopes. These processes ultimately resulted in mixing of waste streams from different processes. As a result, the chemistry and the fate of Tc in HLW tanks are not well understood. This lack of understanding has been made evident in the failed efforts to leach Tc from sludge and to remove Tc from supernatants prior to immobilization. Although recent interest in Tc chemistry has shifted from pretreatment chemistry to waste residuals, both needs are served by a fundamental understanding of Tc chemistry.

Hess, Nancy J.; Felmy, Andrew R.; Rosso, Kevin M.; Xia Yuanxian

2005-06-06

470

Frontiers in Atmospheric Chemistry Modelling  

NASA Astrophysics Data System (ADS)

The first pan-European kilometre-scale atmospheric chemistry simulation is introduced. The continental-scale air pollution episode of January 2009 is modelled with the CHIMERE offline chemistry-transport model with a massive grid of 2 million horizontal points, performed on 2000 CPU of a high performance computing system hosted by the Research and Technology Computing Center at the French Alternative Energies and Atomic Energy Commission (CCRT/CEA). Besides the technical challenge, which demonstrated the robustness of the selected air quality model, we discuss the added value in terms of air pollution modelling and decision support. The comparison with in-situ observations shows that model biases are significantly improved despite some spurious added spatial variability attributed to shortcomings in the emission downscaling process and coarse resolution of the meteorological fields. The increased spatial resolution is clearly beneficial for the detection of exceedances and exposure modelling. We reveal small scale air pollution patterns that highlight the contribution of city plumes to background air pollution levels. Up to a factor 5 underestimation of the fraction of population exposed to detrimental levels of pollution can be obtained with a coarse simulation if subgrid scale correction such as urban increments are ignored. This experiment opens new perspectives for environmental decision making. After two decades of efforts to reduce air pollutant emissions across Europe, the challenge is now to find the optimal trade-off between national and local air quality management strategies. While the first approach is based on sectoral strategies and energy policies, the later builds upon new alternatives such as urban development. The strategies, the decision pathways and the involvement of individual citizen differ, and a compromise based on cost and efficiency must be found. We illustrated how high performance computing in atmospheric science can contribute to this aim. Although further developments are still needed to secure the results for routine policy use, the door is now open...

Colette, Augustin; Bessagnet, Bertrand; Meleux, Frederik; Roul, Laurence

2013-04-01

471

Stationary light in cold-atomic gases  

SciTech Connect

We discuss stationary light created by a pair of counterpropagating control fields in {lambda}-type atomic gases with electromagnetically induced transparency for the case of negligible Doppler broadening. In this case, the secular approximation used in the discussion of stationary light in hot vapors is no longer valid. We discuss the quality of the effective light-trapping system and show that in contrast to previous claims it is finite even for vanishing ground-state dephasing. The dynamics of the photon loss is in general nonexponential and can be faster or slower than in hot gases.

Nikoghosyan, Gor [Fachbereich Physik and Research Center OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Institute of Physical Research, 378410 Ashtarak-2 (Armenia); Fleischhauer, Michael [Fachbereich Physik and Research Center OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany)

2009-07-15

472

Rice University HOT WORK PERMIT  

E-print Network

, cutting, grinding, and soldering, thawing pipe, torch applied roofing, and welding. (References: 2000/operable. Hot Work equipment in good repair. Special precautions taken to avoid accidental operation

Natelson, Douglas

473

Atomic Mobile  

NSDL National Science Digital Library

In this hands-on OLogy activity, kids learn about matter by building their own models of carbon out of pipe cleaners, wire, and clay. The activity begins with a kid-friendly introduction to matter, elements, and atoms. The illustrated, step-by-step directions show how to use the information about carbon on the Periodic Table to create a mobile that shows the element's basic structure. A PDF version of the Periodic Table, along with a kid-friendly overview of how to read it, is also included.

474

Atomic oxygen in solid deuterium A. V. Danilychev and V. A. Apkarian*  

E-print Network

Atomic oxygen in solid deuterium A. V. Danilychev and V. A. Apkarian* Department of Chemistry 113, Japan Submitted June 8, 2000 Fiz. Nizk. Temp. 26, 909­917 September­October 2000 Atomic oxygen is photogenerated in solid D2 by 193 nm irradiation of samples initially doped with molecular oxygen. The atoms

Apkarian, V. Ara

475

Science360: Chemistry  

NSDL National Science Digital Library

Have you ever wondered about the chemistry of a cheeseburger? Well you are in luck because that is one of the subjects covered on the topical and delightful "Chemistry" section of the popular Science360 website. As it states on the site, "everything you hear, see, taste, smell and touch involves chemistry and chemicals", and here visitors can watch videos and learn about the molecular structure of water, the science behind glass blowing, and how a curious mud-like mixture is being used to soak up oil spills and insulate homes. Currently, there are about fifteen videos on the site, and visitors can sign up via a host of social media (Twitter, Facebook, and so on), to stay abreast of new additions to the site. Teachers will find that this material can be integrated into the classroom quite easily, and everyone else will just enjoy wandering through these offerings.

476

Macs in Chemistry  

NSDL National Science Digital Library

Using computers to do science is a great way to get young people hooked on the enterprise, and mobile apps and other devices make this easier than ever. The Macs in Chemistry site features dozens of applications that will help users learn about chemistry (and more) through interactive activities, quizzes, and so on. In the At a Glance area, visitors can learn about the tutorials archived here, data analysis tools, and mobile science apps. This last section is a real gem, as it contains dozens of applications including everything from 29 interactive maps of the brain to chemistry formula exercises to a working seismograph. The rest of the applications are divided into alphabetical sections. Visitors should click on the Software Reviews area for timely and detailed reviews of each application's strengths and weaknesses. The site is rounded out by a contact form and a set of useful links.

477

Reaction chemistry of cerium  

SciTech Connect

It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

NONE

1997-01-01

478

Hot toys are dead: long live hot products  

Microsoft Academic Search

Recalls the hot toys phenomenon of several past Christmases in the USA, such as for Cabbage Patch dolls and Power Rangers. Argues that such toys created headlines in order to gain publicity, but also that this trend appears to have died because of eBay: what made toys hot and a cultural event was their inaccessibility, but eBay makes them all

Christopher Byrne

2005-01-01

479

Full of Hot Air: Hot Air Balloon Building  

NSDL National Science Digital Library

In this activity, learners create a model of a hot air balloon using tissue paper and a hairdryer. Educators can use this activity to introduce learners to density and its role in why things float. This activity page features a fun how-to video that shows learners and educators how to make the hot air balloons.

Houston, Children'S M.

2010-01-01

480

Digital biology and chemistry.  

PubMed

This account examines developments in "digital" biology and chemistry within the context of microfluidics, from a personal perspective. Using microfluidics as a frame of reference, we identify two areas of research within digital biology and chemistry that are of special interest: (i) the study of systems that switch between discrete states in response to changes in chemical concentration of signals, and (ii) the study of single biological entities such as molecules or cells. In particular, microfluidics accelerates analysis of switching systems (i.e., those that exhibit a sharp change in output over a narrow range of input) by enabling monitoring of multiple reactions in parallel over a range of concentrations of signals. Conversely, such switching systems can be used to create new kinds of microfluidic detection systems that provide "analog-to-digital" signal conversion and logic. Microfluidic compartmentalization technologies for studying and isolating single entities can be used to reconstruct and understand cellular processes, study interactions between single biological entities, and examine the intrinsic heterogeneity of populations of molecules, cells, or organisms. Furthermore, compartmentalization of single cells or molecules in "digital" microfluidic experiments can induce switching in a range of reaction systems to enable sensitive detection of cells or biomolecules, such as with digital ELISA or digital PCR. This "digitizing" offers advantages in terms of robustness, assay design, and simplicity because quantitative information can be obtained with qualitative measurements. While digital formats have been shown to improve the robustness of existing chemistries, we anticipate that in the future they will enable new chemistries to be used for quantitative measurements, and that digital biology and chemistry will continue to provide further opportunities for measuring biomolecules, understanding natural systems more deeply, and advancing molecular and cellular analysis. Microfluidics will impact digital biology and chemistry and will also benefit from them if it becomes massively distributed. PMID:24889331

Witters, Daan; Sun, Bing; Begolo, Stefano; Rodriguez-Manzano, Jesus; Robles, Whitney; Ismagilov, Rustem F

2014-09-01

481

Atomic Archive  

NSDL National Science Digital Library

This site explores the science, history, and consequences of the invention of the atomic bomb. It offers information about the events and decisions that led to the development of the bomb and the events and decisions that followed, from Hiroshima and Nagasaki to today's post-Cold War era. For users who wish to understand how nuclear weapons work, the site explains basic atomic physics, nuclear fission, and nuclear fusion. It also explores the effects of nuclear weapons and ponders several "what-if" scenarios. The history section tells the stories of the first nuclear reactor and the first nuclear test in New Mexico's desert. A Resource Library includes historical documents and biographies of the nuclear pioneers, including J. Robert Oppenheimer, Albert Einstein, Edward Teller, Enrico Fermi, Hans Bethe, and many others. The site offers educators such teaching aids as interactive maps, animations, a timeline of the nuclear age, and a glossary of terms. The Nuclear News section offers topical summaries of current events pertaining to nuclear issues.

2005-02-22

482

Chemistry and materials science  

SciTech Connect

Our work in chemistry and materials science exemplifies disciplinary research and programmatic support. The disciplinary research is intended to sharpen the skills of our scientists, advance the frontiers of scientific knowledge, and provide the seeds for programs of the future. The programmatic support provides the very best scientific and engineering talent for Laboratory programs and offers the potential for new program areas. We are convinced that chemistry and materials science will be key to the future success of the Laboratory whatever its mission, and we are firmly committed to supporting this mission with the very best in scientific talent.

NONE

1995-01-01

483

Chemistry in cometary comae  

NASA Technical Reports Server (NTRS)

Significant gas-phase chemistry occurs in the comae of bright comets, as is demonstrated here for the case of Comet Hale-Bopp. The abundance ratio of the two isomers, hydrogen cyanide and hydrogen isocyanide, is shown to vary with heliocentric distance in a way that is consistent with production of HNC by ion-molecule chemistry initiated by the photoionization of water. Likewise, the first maps of emission from HCO+ show an abundance and an extended distribution that are consistent with the same chemical model.

Irvine, W. M.; Dickens, J. E.; Lovell, A. J.; Schloerb, F. P.; Senay, M.; Bergin, E. A.; Jewitt, D.; Matthews, H. E.

1998-01-01

484

Chemistry WebBook  

National Institute of Standards and Technology Data Gateway

SRD 69 NIST Chemistry WebBook (Web, free access) The NIST Chemistry WebBook contains: Thermochemical data for over 7000 organic and small inorganic compounds; thermochemistry data for over 8000 reactions; IR spectra for over 16,000 compounds; mass spectra for over 33,000 compounds; UV/Vis spectra for over 1600 compounds; electronic and vibrational spectra for over 5000 compounds; constants of diatomic molecules(spectroscopic data) for over 600 compounds; ion energetics data for over 16,000 compounds; thermophysical property data for 74 fluids.

485

Chemistry in water reactors. Reserapport. (Chemistry in water reactors).  

National Technical Information Service (NTIS)

The international conference Chemistry in Water Reactors was arranged in Nice 24-27/04/1994 by the French Nuclear Energy Society. Examples of technical program areas were primary chemistry, operational experience, fundamental studies and new technology. F...

H. P. Hermansson, K. Norring

1994-01-01

486

Atom Skimmers and Atom Lasers Utilizing Them  

NASA Technical Reports Server (NTRS)

Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

2005-01-01

487

Atomic Transport/ Dense Metallic  

E-print Network

Atomic Transport/ Dense Metallic Hydrogen Separation Systems #12;Participants -- Atomic Transport contaminants + partial pressure #12;Technology Options ­ Atomic Transport/Dense Metallic Systems Pd alloy intensification Membrane plus reactor #12;Barrier Categories-- Atomic Transport/Dense Metallic Systems Membrane

488

Hot and Cold  

NSDL National Science Digital Library

In this chemistry challenge, learners discover that many chemical reactions involve heat loss or gain. With this understanding, they try to find a combination of chemicals that could be used to make an instant cold pack. They are given baking soda, ammonium nitrate, calcium chloride, and potassium chloride, along with vinegar and water (3% hydrogen peroxide and yeast can also be used). Learners combine chemicals into calorimeters, then use thermometers to measure how the temperature changes. Calorimeters can be made by pushing a heated test tube into home insulation foam (instructions in PDF) or can be purchased (one source is Flinn Scientific). The water and ammonium nitrate, and vinegar and baking soda, are candidates for making a cold pack.

Sciencenter

2014-08-27

489

Hot Planet - Cold Comfort  

NSDL National Science Digital Library

This page features videos from the "Hot Planet- Cold Comfort" television episode, related website articles and a student activity. The videos explore how the Gulf Stream conveyor belt may shut down; how Arctic river runoff and Alaskan glacial melt are freshening the oceans; and how ocean sediments and ice cores are being studied to understand the Little Ice Age. The videos total approximately one hour in length. The website articles explore the Little Ice Age; how the Arctic functions as a global thermostat, affecting global weather patterns; and great moments in climate change. The student activity is about light absorbtion. The site also contains a challenge activity to find details in a painting that depict Little Ice Age living conditions.

490

The Deep Hot Biosphere  

NASA Astrophysics Data System (ADS)

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 range of conditions under which water can exist as a liquid. At some ancient mythic time billions of years ago in a witches' brew of precursory molecules, somewhere, somehow, on a sunny Precambrian day bright with promise some of these molecules came together in th