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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

RADIOACTIVE METALLOFULLERENES: HOT ATOM CHEMISTRY ASPECTS.  

E-print Network

RADIOACTIVE METALLOFULLERENES: HOT ATOM CHEMISTRY ASPECTS. Yu.S.Grushko, M.A. Khodorkovski, V, in radioactive form, endometallofullerenes become the subject of new branch of radiochemistry and materials studies and monitoring of 1 #12;chemical properties of metallofullerenes, in technology of radioactive

Titov, Anatoly

3

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

4

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

5

Hot-atom incorporation of tritium atoms into fullerenes  

NASA Astrophysics Data System (ADS)

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

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

1994-10-01

6

Steady state theory of hot atom reactions  

Microsoft Academic Search

A simple steady state theory of hot atom reactions is developed based on the Boltzmann equation. The solution to this equation is approximated by a local Maxwell distribution involving the temperature of the hot atoms and steady state distributions are calculated by determining steady values of the hot atom temperature. General considerations imply the existence of steady state distributions with

Joel Keizer

1973-01-01

7

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

8

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.

9

Modeling hot spring chemistries with applications to martian silica formation  

USGS Publications Warehouse

Many recent studies have implicated hydrothermal systems as the origin of martian minerals across a wide range of martian sites. Particular support for hydrothermal systems include silica (SiO2) deposits, in some cases >90% silica, in the Gusev Crater region, especially in the Columbia Hills and at Home Plate. We have developed a model called CHEMCHAU that can be used up to 100??C to simulate hot springs associated with hydrothermal systems. The model was partially derived from FREZCHEM, which is a colder temperature model parameterized for broad ranges of temperature (<-70 to 25??C), pressure (1-1000 bars), and chemical composition. We demonstrate the validity of Pitzer parameters, volumetric parameters, and equilibrium constants in the CHEMCHAU model for the Na-K-Mg-Ca-H-Cl-ClO4-SO4-OH-HCO3-CO3-CO2-O2-CH4-Si-H2O system up to 100??C and apply the model to hot springs and silica deposits.A theoretical simulation of silica and calcite equilibrium shows how calcite is least soluble with high pH and high temperatures, while silica behaves oppositely. Such influences imply that differences in temperature and pH on Mars could lead to very distinct mineral assemblages. Using measured solution chemistries of Yellowstone hot springs and Icelandic hot springs, we simulate salts formed during the evaporation of two low pH cases (high and low temperatures) and a high temperature, alkaline (high pH) sodic water. Simulation of an acid-sulfate case leads to precipitation of Fe and Al minerals along with silica. Consistency with martian mineral assemblages suggests that hot, acidic sulfate solutions are plausibility progenitors of minerals in the past on Mars. In the alkaline pH (8.45) simulation, formation of silica at high temperatures (355K) led to precipitation of anhydrous minerals (CaSO4, Na2SO4) that was also the case for the high temperature (353K) low pH case where anhydrous minerals (NaCl, CaSO4) also precipitated. Thus we predict that secondary minerals associated with massive silica deposits are plausible indicators on Mars of precipitation environments and aqueous chemistry. Theoretical model calculations are in reasonable agreement with independent experimental silica concentrations, which strengthens the validity of the new CHEMCHAU model. ?? 2011 Elsevier Inc.

Marion, G.M.; Catling, D.C.; Crowley, J.K.; Kargel, J.S.

2011-01-01

10

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

11

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

12

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

NASA Astrophysics Data System (ADS)

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

Amaran, Saieswari; Kosloff, Ronnie; Tomza, Micha?; Skomorowski, Wojciech; Paw?owski, Filip; Moszynski, Robert; Rybak, Leonid; Levin, Liat; Amitay, Zohar; Berglund, J. Martin; Reich, Daniel M.; Koch, Christiane P.

2013-10-01

13

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

SciTech Connect

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

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

2013-10-28

14

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

15

Chemistry of hot springs along the Eastern Lau Spreading Center  

NASA Astrophysics Data System (ADS)

The Eastern Lau Spreading Center (ELSC) is the southernmost part of the back-arc spreading axis in the Lau Basin, west of the Tonga trench and the active Tofua volcanic arc. Over its 397-km length it exhibits large and systematic changes in spreading rate, magmatic/tectonic processes, and proximity to the volcanic arc. In 2005, we collected 81 samples of vent water from six hydrothermal fields along the ELSC. The chemistry of these waters varies both within and between vent fields, in response to changes in substrate composition, temperature and pressure, pH, water/rock ratio, and input from magmatic gases and subducted sediment. Hot-spring temperatures range from 229° to 363 °C at the five northernmost fields, with a general decrease to the south that is reversed at the Mariner field. The southernmost field, Vai Lili, emitted water at up to 334 °C in 1989 but had a maximum venting temperature of only 121 °C in 2005, due to waning activity and admixture of bottom seawater into the subseafloor plumbing system. Chloride varies both within fields and from one field to another, from a low of 528 mmol/kg to a high of 656 mmol/kg, and may be enriched by phase separation and/or leaching of Cl from the rock. Concentrations of the soluble elements K, Rb, Cs, and B likewise increase southward as the volcanic substrate becomes more silica-rich, especially on the Valu Fa Ridge. Iodine and ? 7Li increase southward, and ? 11B decreases as B increases, apparently in response to increased input from subducted sediment as the arc is approached. Species that decrease southward as temperature falls are Si, H 2S, Li, Na/Cl, Fe, Mn, and 87Sr/ 86Sr, whereas pH, alkalinity, Ca, and Sr increase. Oxygen isotopes indicate a higher water/rock ratio in the three systems on Valu Fa Ridge, consistent with higher porosity in more felsic volcanic rocks. Vent waters at the Mariner vent field on the Valu Fa Ridge are significantly hotter, more acid and metal-rich, less saline, and richer in dissolved gases and other volatiles, including H 2S, CO 2, and F, than the other vent fields, consistent with input of magmatic gases. The large variations in geologic and geophysical parameters produced by back-arc spreading along the ELSC, which exceed those along mid-ocean ridge spreading axes, produce similar large variations in the composition of vent waters, and thus provide new insights into the processes that control the chemistry of submarine hot springs.

Mottl, Michael J.; Seewald, Jeffrey S.; Wheat, C. Geoffrey; Tivey, Margaret K.; Michael, Peter J.; Proskurowski, Giora; McCollom, Thomas M.; Reeves, Eoghan; Sharkey, Jessica; You, C.-F.; Chan, L.-H.; Pichler, Thomas

2011-02-01

16

Hot hydrogen atom reactions moderated by H2 and He  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

17

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

18

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 planet’s 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

19

Hot-atom synthesis of organic compounds on Jupiter  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

20

Nonequilibrium velocity distribution and reaction rate in hot-atom reactions  

Microsoft Academic Search

The nonequilibrium velocity distribution and reaction rate in hot-atom reactions are studied by solving the time-dependent Boltzmann equation with the Monte Carlo simulation. The explicit time-dependent velocity distribution, temperature, and rate constant of hot atoms from initial to steady states are obtained for a simple model system where hot atoms are dispersed in the heat bath of surrounding molecules without

Katsuhisa Koura

1976-01-01

21

Pre-cometary ice composition from hot core chemistry.  

PubMed

Pre-cometary ice located around star-forming regions contains molecules that are pre-biotic compounds or pre-biotic precursors. Molecular line surveys of hot cores provide information on the composition of the ice since it sublimates near these sites. We have combined a hydrostatic hot core model with a complex network of chemical reactions to calculate the time-dependent abundances of molecules, ions, and radicals. The model considers the interaction between the ice and gas phase. It is applied to the Orion hot core where high-mass star formation occurs, and to the solar-mass binary protostar system IRAS 16293-2422. Our calculations show that at the end of the hot core phase both star-forming sites produce the same prebiotic CN-bearing molecules. However, in the Orion hot core these molecules are formed in larger abundances. A comparison of the calculated values with the abundances derived from the observed line data requires a chemically unprocessed molecular cloud as the initial state of hot core evolution. Thus, it appears that these objects are formed at a much younger cloud stage than previously thought. This implies that the ice phase of the young clouds does not contain CN-bearing molecules in large abundances before the hot core has been formed. The pre-biotic molecules synthesized in hot cores cause a chemical enrichment in the gas phase and in the pre-cometary ice. This enrichment is thought to be an important extraterrestrial aspect of the formation of life on Earth and elsewhere. PMID:16225436

Tornow, Carmen; Kührt, Ekkehard; Motschmann, Uwe

2005-10-01

22

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

23

Unique products of the reaction of isoprene with atomic chlorine: Potential markers of chlorine atom chemistry  

NASA Astrophysics Data System (ADS)

The contribution of atomic chlorine to the chemistry of marine regions as well as the Arctic at ground level at polar sunrise is the subject of a number of recent studies. However, identifying the specific chlorine atom precursors has proven difficult. One potential approach is the measurement of definitive products of chlorine atom reactions, for example with biogenic hydrocarbons. We report here product studies of the chlorine atom reaction with isoprene using ppm concentrations at one atmosphere air and 298 K in a NOx-free system using atmospheric pressure ionization-mass spectrometry (API-MS) as well as GC-MS. 1-chloro-3-methyl-3-butene-2-one (CMBO) is identified as a unique product of this reaction, and there is evidence of the formation of three additional isomers of CMBO as well. Methyl vinyl ketone (MVK) is formed in small yields (9 ± 5 %), consistent with earlier studies of this reaction in which an upper yield of 13% was reported. The stable product expected from allylic hydrogen atom abstraction (measured in earlier kinetic studies to be 15% of the total reaction), 2-methylene-3-butenal, is also tentatively identified using API-MS. Assuming that similar chemistry occurs at the ppb-ppt levels found in the atmosphere, identification of CMBO and/or its isomers in field studies could provide strong evidence of chlorine atom chemistry in low NOx environments where there are also sources of isoprene.

Nordmeyer, Trent; Wang, Weihong; Ragains, Mark L.; Finlayson-Pitts, Barbara J.; Spicer, Chet W.; Plastridge, Robert A.

24

Testing grain-surface chemistry in hot core regions  

Microsoft Academic Search

Many complex organic molecules have been detected in star-forming regions like CH3OCH3 and CH3CH2CN. Studying their chemistry is important, since these species may eventually be incorporated into circumstellar disks and thus become part of the material from which future planetary systems are made. Two scenarios for their formation have been proposed: grain-surface formation and high-temperature gas-phase reactions (van Dishoeck &

Suzanne E. Bisschop; Jes K. Jørgensen; Ewine F. van Dishoeck

2005-01-01

25

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

26

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

27

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

28

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

E-print Network

Femtosecond two-photon photoassociation of hot magnesium atoms: A quantum dynamical study using) Femtosecond two-photon photoassociation of hot magnesium atoms: A quantum dynamical study using thermal random; published online 31 October 2013) Two-photon photoassociation of hot magnesium atoms by femtosecond laser

Koch, Christiane

29

Organic molecules in the Galactic center. Hot core chemistry without hot cores  

NASA Astrophysics Data System (ADS)

Aims.We study the origin of large abundances of complex organic molecules in the Galactic center (GC). Methods: .We carried out a systematic study of the complex organic molecules CH3OH, C2H5OH, (CH3)2O, HCOOCH3, HCOOH, CH3COOH, H2CO, and CS toward 40 GC molecular clouds. Using the LTE approximation, we derived the physical properties of GC molecular clouds and the abundances of the complex molecules. The abundances of complex organic molecules in the GC are compared with those measured in hot cores and hot corinos, in which these complex molecules are also abundant. Results: .The CH3OH abundance between clouds varies by nearly two orders of magnitude from 2.4×10-8 to 1.1×10-6. The abundance of the other complex organic molecules relative to that of CH3OH is basically independent of the CH3OH abundance, with variations of only a factor 4-8. We find that both the abundance and the abundance ratios of the complex molecules relative to CH3OH in hot cores are similar to those found in the GC clouds. However, hot corinos show different abundance ratios than observed in hot cores and in GC clouds. The rather constant abundance of all the complex molecules relative to CH3OH suggests that all complex molecules are ejected from grain mantles by shocks. Frequent (~105 years) shocks with velocities >6 km s-1 are required to explain the high abundances in gas phase of complex organic molecules in the GC molecular clouds. The rather uniform abundance ratios in the GC clouds and in Galactic hot cores indicate a similar average composition of grain mantles in both kinds of regions. The Sickle and the Thermal Radio Arches, affected by UV radiation, show different relative abundances in the complex organic molecules due to the differentially photodissociation of these molecules.

Requena-Torres, M. A.; Martín-Pintado, J.; Rodríguez-Franco, A.; Martín, S.; Rodríguez-Fernández, N. J.; de Vicente, P.

2006-09-01

30

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 MaCl in the gas stream, velocity 0.3 Mach. The alloys are Udiment 700, Rene 80, uncoated and with RT21, Codep, or NiCoCrAlY coatings. These tests were completed for specimens in the as-processed condition and after aging at 1100 C in oxidizing or inert evnivronments for time up to 600 hours. Coil inductance changes used for periodic nondestructive inspection of specimens were useful in following the course of corrosion. Typical sulfidation was observed in all cases, structurally similar to that observed for service-run turbine components. Aging at cuased a severe decrease in hot corrosion life of RT21 and Codep coatings and a significant but less decrease in the life of the NiCoCrAlY coating. The extent of these decreases was much greater for all three coatings on U700 substrates than on Rene 80 substrates. Coating/substrate interdiffusion rather than by surface oxidation.

Fryxell, R. E.

1985-01-01

31

Resonance enhanced multiphoton ionisation probing of H atoms in a hot lament chemical vapour deposition reactor  

E-print Network

Resonance enhanced multiphoton ionisation probing of H atoms in a hot Ðlament chemical vapour multiphoton ionisation (MPI) spectroscopy, resonance enhanced at the two photon energy by the state, to detect

Bristol, University of

32

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

33

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, Özgür; Türe, Orkun

2014-05-01

34

Entanglement of the orbital angular momentum states of the photons generated in a hot atomic ensemble  

E-print Network

Quantum protocols will be more efficient with high-dimensional entangled states. Photons carrying orbital angular momenta can be used to create a high-dimensional entangled state. In this paper we experimentally demonstrate the entanglement of the orbital angular momentum between the Stokes and anti-Stokes photons generated in a hot atomic ensemble using spontaneous four-wave-mixing. This experiment also suggests the existence of the entanglement concerned with spatial degrees of freedom between the hot atomic ensemble and the Stokes photon.

Qun-Feng Chen; Bao-Sen Shi; Yong-Sheng Zhang; Guang-Can Guo

2008-07-01

35

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

36

Evolution of the Martian surface pressure caused by hot O and C atom escape  

NASA Astrophysics Data System (ADS)

Low energetic (few eV) neutral atoms which are produced due to dissociative recombination, photo dissociation, charge exchange and so on in planetary thermospheres play an important role for the escape of heavy atmospheric species at Mars. The newly photochemically generated energetic neutral atoms, O and C are traced from their point of origin up to the exobase or beyond, by using a 3D Monte-Carlo model and the kinetics and transport characteristics of these particles are determined. The simulation includes the collision of the suprathermal particles with the background gas, energy transfer, and the tracing of secondary and cascaded hot atoms, which are generated in collisions of the hot particles with ambient constituents. A nonlinear electron dissociative recombination coefficient as well as energy and mass dependent collision cross sections and their corresponding scattering angles are also taken into account. In this model we consider elastic, inelastic and quenching collisions between the traced hot particle and the ambient neutral atmosphere. To determine the collision probability the energy and mass dependent total collision cross sections are used. The scattering angle after a collision between the traced hot particle and the background neutrals are chosen randomly from the corresponding differential collision cross section. We also include rotational and vibrational excitation energies for the calculation of the initial energy of the produced hot oxygen and carbon atoms. With the simulation of the loss rates for O and C over the past, starting from the end of the Noachian Epoch up to now, the loss of the CO2 atmosphere during the history can be calculated. With these losses one can estimate the evolution of the surface pressure and its influence to the climate conditions and to the planetary habitability caused by hot atom escape.

Gröller, H.; Lammer, H.; Lichtenegger, H. I. M.; Dutuit, O.; Shematovich, V. I.; Kulikov, Y. N.

2011-10-01

37

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

38

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

E-print Network

Analysis and control Cluster Chemistry And Dynamics Special Feature: Ultrafast dynamics in atomic reprints, see: Notes: #12;Ultrafast dynamics in atomic clusters: Analysis and control Vlasta Bonacic clusters: Vlasta Bonacic-Koutecky, Roland Mitric, Ute Werner, Ludger Wöste, and R. Stephen Berry doi:10

Berry, R. Stephen

39

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

NASA Astrophysics Data System (ADS)

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. We have combined selected aspects of the chemistry of hot spring fluids with constraints imposed by a geologically reasonable assemblage of minerals in the system Na 2O-K 2O-CaO-MgO-FeO-Fe 2OrAl 2O 3-SiO 2-H 2O-HCl-H 2S to assess the effect of temperature on the composition of the aqueous phase and the activities of mineral components in plagioclase and epidote solid solutions. Assuming ƒO 2(g) and ƒS 2(g) controlled by pyrite-pyrrhotite-magnetite equilibria, a constant dissolved Ca concentration, and a dissolved Cl concentration equivalent to that of seawater, increasing temperature from 250 to 400°C at 500 bars results in systematic changes in the composition of mineral phases, which in turn constrain pH and the distribution of aqueous species. The model predicts that dissolved concentrations of Fe, SiO 2, K, H 2S, and H 2 increase, while Na and pH (25°c) decrease with increasing temperature. pH ( in-situ) decreases slightly with increasing temperature, and has a value of 5.16 at 400°C. Dissolved Mg concentrations do not exceed 1 mmolal at any temperature investigated. Allowing for differences in pressure and total dissolved Cl, the predicted effect of temperature on fluid chemistry is in good agreement with results from basalt alteration and plagioclase + epidote + quartz recrystallization experiments, and in some cases, with results from hot spring fluids at mid-ocean ridges. Some vent fluids, in particular NGS (EPR, 21°N) and vent-4 (EPR, 11°N), however, reveal pH and/or dissolved Fe, H 2S, H 2, and SiO 2 concentrations, which are difficult to reconcile with measured temperatures in comparison with results of temperature dependent mineral solubility calculations, and suggest that these fluids have lost heat by conduction on ascent to the seafloor. That many hot spring vent fluids are characterized by variable degrees of conductive heat loss renders measured temperatures unreliable as indicators of the maximum temperature of subseafloor hydrothermal alteration processes. The implications of this are significant for hot spring fluids which reveal large Cl variations relative to seawater, since likely mechanisms to account for such variability typically require temperatures in excess of those inferred for subseafloor reaction zones by simply correcting measured temperatures for the effects of adiabatic cooling.

Seyfried, W. E., Jr.; Ding, Kang; Berndt, M. E.

1991-12-01

40

Alcohol chemistry in the Galactic Center molecular clouds. A gigantic Hot Core  

NASA Astrophysics Data System (ADS)

We have carried out a systematic study of CH3OH, C2H5OH, (CH3)2O, HCOOCH3, HCOOH, CH3COOH, H2CO and CS in different Galactic Center (GC) molecular clouds. Figure 1 shows the relative abundances of those molecules with respect to CH3OH in the GC as function of the CH3OH abundance. The CH3OH abundance between sources in the GC varies in nearly two orders of magnitude. The abundance ratio of these molecules relative to CH3OH is basically independent of the CH3OH abundances and only varies in a factor of ~ 4 - 8. The abundance ratio of CS relative to CH3OH seem to vary by a factor of 60. Our data are compared with observations of the same molecules in short-lived objects like the hot cores. The abundance and the abundance ratios of the complex molecules relative to CH3OH in massive hot cores are similar to that found in the GC clouds. Alcohol related chemistry is believed to be driven by gas phase reactions after evaporation of alcohols from grain mantles. Gas phase chemistry based in the ejection of alcohols from grains (see Charnley et al. 1995; Horn et al. (2004)) can not explain the observed abundances of HCOOCH3 in the GC and the rather constant relative abundances of the other complex molecules. Our data suggest that basically all the molecules related to alcohol chemistry could be produced on grain mantles and/or depleted from gas phase after their formation. This interpretation requires frequent shocks in the GC region to keep the high abundances of these molecules in gas phase and a rather uniform average composition of the icy grain mantles. The molecular clouds associated with the Sickle and the Thermal Radio Arches (TRA), which seem to be affected by UV radiation, see Rodriguez-Fernandez et al. (2001), show lower abundances of C2H5OH relative to CH3OH which could be explained by shock ejection and photo dissociation conditions.

Requena Torres, M. A.; Martín-Pintado, J.; Rodríguez-Franco, A.; Martín, S.; Rodríguez-Fer?Ndez, N. J.

41

Possibility of nonexistence of hot and superhot hydrogen atoms in electrical discharges  

SciTech Connect

Recently, the existence of extremely energetic hydrogen atoms in electrical discharges has been proposed in the literature with large controversy, from the analysis of the anomalous broadening of hydrogen Balmer lines. In this paper, the velocity distribution of H atoms and the profiles of the emitting atom lines created by the exothermic reaction H{sub 2}{sup +}+H{sub 2}{yields}H{sub 3}{sup +}+H+{Delta}E are calculated, as a function of the internal energy defect {Delta}E. The shapes found for the non-Maxwell-Boltzmann distributions resulting in non-Gaussian line profiles raise serious arguments against the existence of hot and superhot H atoms as it has been proposed, at least with those temperatures.

Loureiro, J. [Instituto de Plasmas e FuSao Nuclear-Laboratorio Associado, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, 1049-001 Lisboa (Portugal); Amorim, J. [Laboratorio Nacional de Ciencia e Tecnologia do Bietanol (CTBE), Caixa Postal 6170, CEP 13083-970 Campinas, SP (Brazil)

2010-09-15

42

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 rigid–nonrigid correlation, vibrons, and quantum groups suggest a unified view of collective electronic motion in atoms and nuclear motion in molecules. PMID:8962040

Kellman, Michael?E.

1996-01-01

43

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

44

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

45

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

46

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

47

Introductory Lecture Time-resolved chemistry at atomic resolution  

E-print Network

variety of chemical processes can hardly be overestimated. While molecular structure is a basic concept rapid atom dynamics the existing experimental methods needed vast improvement, as motions of several a,3 and crystallization,4 while slower-moving solid-state reactions5 must also be mentioned. A distinction can be made

Coppens, Philip

48

Atomic structure and chemistry of human serum albumin  

NASA Technical Reports Server (NTRS)

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

He, Xiao M.; Carter, Daniel C.

1992-01-01

49

Resonance enhanced multiphoton ionization probing of H atoms and CH3 radicals in a hot lament chemical vapour deposition reactor  

E-print Network

reactor used for diamond chemical vapour deposition (CVD). Parameters varied include the hydrocarbon (CH4 to reinforce the consensus view that H atom production during diamond CVD in a hot ®lament reactor arises as a result of dissociative adsorption on the hot ®lament surface, whereas CH3 radical formation is dominated

Bristol, University of

50

Analysis of electromagnetically induced transparency and slow light in a hot vapor of atoms undergoing collisions  

NASA Astrophysics Data System (ADS)

We present a detailed theoretical treatment of a three-level ? system in a hot atomic vapor interacting with a coupling and a probe field of arbitrary strengths, leading to electromagnetically induced transparency and slow light under the two-photon resonance condition. We take into account all the relevant decoherence processes including collisions. Velocity-changing collisions (VCCs) are modeled in the strong-collision limit effectively, which helps in achieving optical pumping by the coupling beam across the entire Doppler profile. The steady-state expressions for the atomic density-matrix elements are numerically evaluated to yield the experimentally measured response characteristics. The predictions, taking into account a dynamic rate of influx of atoms in the two lower levels of the ? , are in excellent agreement with the reported experimental results for H4e? . The role played by the VCC parameter is seen to be distinct from that by the transit time or Raman coherence decay rate.

Ghosh, Joyee; Ghosh, R.; Goldfarb, F.; Le Gouët, J.-L.; Bretenaker, F.

2009-08-01

51

Eley-Rideal surface chemistry: Direct reactivity of gas phase atomic hydrogen with adsorbed species  

SciTech Connect

Selected examples of Eley-Rideal surface chemistry are presented in order to review this field. Reactions on Ru(100) only are considered. The specific examples employed are: (i) hydrogenation of oxygen atoms, (ii) hydrogenation of CO, (iii) formation of dihydrogen, and (iv) hydrogenation of formate. 80 refs., 8 figs.

Weinberg, W.H. [Univ. of California, Santa Barbara, CA (United States)] [Univ. of California, Santa Barbara, CA (United States)

1996-10-01

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

The Materials Chemistry of Atomic Oxygen with Applications to Anisotropic Etching of Submicron Structures in Microelectronics and the Surface Chemistry Engineering of Porous Solids  

NASA Technical Reports Server (NTRS)

Neutral atomic oxygen is the most abundant component of the ionospheric plasma in the low Earth orbit environment (LEO; 200 to 700 kilometers altitude) and can produce significant degradation of some spacecraft materials. In order to produce a more complete understanding of the materials chemistry of atomic oxygen, the chemistry and physics of O-atom interactions with materials were determined in three radically different environments: (1) The Space Shuttle cargo bay in low Earth orbit (the EOIM-3 space flight experiment), (2) a high-velocity neutral atom beam system (HVAB) at Los Alamos National Laboratory (LANL), and (3) a microwave-plasma flowing-discharge system at JSC. The Space Shuttle and the high velocity atom beam systems produce atom-surface collision energies ranging from 0.1 to 7 eV (hyperthermal atoms) under high-vacuum conditions, while the flowing discharge system produces a 0.065 eV surface collision energy at a total pressure of 2 Torr. Data obtained in the three different O-atom environments referred to above show that the rate of O-atom reaction with polymeric materials is strongly dependent on atom kinetic energy, obeying a reactive scattering law which suggests that atom kinetic energy is directly available for overcoming activation barriers in the reaction. General relationships between polymer reactivity with O atoms and polymer composition and molecular structure have been determined. In addition, vacuum ultraviolet photochemical effects have been shown to dominate the reaction of O atoms with fluorocarbon polymers. Finally, studies of the materials chemistry of O atoms have produced results which may be of interest to technologists outside the aerospace industry. Atomic oxygen 'spin-off' or 'dual use' technologies in the areas of anisotropic etching in microelectronic materials and device processing, as well as surface chemistry engineering of porous solid materials are described.

Koontz, Steve L.; Leger, Lubert J.; Wu, Corina; Cross, Jon B.; Jurgensen, Charles W.

1994-01-01

54

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

55

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

56

Atomic and Molecular Quantum Theory Course Number: C561 Chemistry, Indiana University C-14 c 2003, Srinivasan S. Iyengar (instructor)  

E-print Network

Atomic and Molecular Quantum Theory Course Number: C561 Chemistry, Indiana University C-14 c 2003, Srinivasan S. Iyengar (instructor) #12;Atomic and Molecular Quantum Theory Course Number: C561 D A little bit (instructor) #12;Atomic and Molecular Quantum Theory Course Number: C561 2. Using these ket vectors the Sz

Iyengar, Srinivasan S.

57

RADIATION CHEMISTRY OF GASES  

Microsoft Academic Search

Discussions are presented concerning the advantages and limitations of ; gas phase studies in radiation chemistry, observed effects of phase in radiation, ; hot reactions, reactions of thermal I atoms, HCl catalyzed chain isomerizations, ; molecular Hâ detachment, fragmentation of charged species, role of excited ; states, and dissociative electron attachment. (J.R.D.);

1962-01-01

58

Research and citation impact of publications by the Chemistry Division at Bhabha Atomic Research Centre  

Microsoft Academic Search

The paper analyses the citations to 1733 publications published during 1970–1999 by the Chemistry Division at Bhabha Atomic\\u000a Research Centre, using Science Citation Index 1982–2003 as the source data. The extent of citations received, in terms of\\u000a the number of citations per paper, yearwise break up of citations, domainwise citations, self-citations and citations by others,\\u000a diachronous self-citation rate, citing authors,

B. S. Kademani; Vijai Kumar; Ganesh Surwase; Anil Sagar; Lalit Mohan; Anil Kumar; C. R. Gaderao

2007-01-01

59

Chemistry of the heaviest elements--one atom at a time  

SciTech Connect

In keeping with the goal of the Viewpoint series of the Journal of Chemical Education, this article gives a 75-year perspective of the chemistry of the heaviest elements, including a 50-year retrospective view of past developments, a summary of current research achievements and applications, and some predictions about exciting, new developments that might be envisioned within the next 25 years. A historical perspective of the importance of chemical separations in the discoveries of the transuranium elements from neptunium (Z=93) through mendelevium (Z=101) is given. The development of techniques for studying the chemical properties of mendelevium and still heavier elements on the basis of measuring the radioactive decay of a single atom (''atom-at-a-time'' chemistry) and combining the results of many separate experiments is reviewed. The influence of relativistic effects (expected to increase as Z{sup 2}) on chemical properties is discussed. The results from recent atom-at-a-time studies of the chemistry of the heaviest elements through seaborgium (Z=106) are summarized and show that their properties cannot be readily predicted based on simple extrapolation from the properties of their lighter homologues in the periodic table. The prospects for extending chemical studies to still heavier elements than seaborgium are considered and appear promising.

Hoffman, Darleane C.; Lee, Diana M.

2000-01-01

60

Realistic theory of electromagnetically induced transparency and slow light in a hot atomic vapor  

NASA Astrophysics Data System (ADS)

We present a realistic theoretical treatment of a three-level ? system in a hot atomic vapor interacting with a coupling and a probe field of arbitrary strengths, leading to electromagnetically-induced transparency and slow light under the two-photon resonance condition. We take into account all the relevant decoherence processes including collisions. Velocity-changing collisions (VCCs) are modeled in the strong collision limit effectively, which helps in achieving optical pumping by the coupling beam across the entire Doppler profile. We take into account a dynamic rate of influx of atoms in the two lower levels of the ?, and an outflux from all the three levels. The steady-state expressions for the atomic density-matrix elements are numerically evaluated to yield the experimentally measured response characteristics. Our predictions are in excellent agreement with the reported experimental results for 4He*. The role played by the VCC parameter is seen to be distinct from that by the transit time or Raman coherence decay rate.

Ghosh, R.; Ghosh, J.; Goldfarb, F.; Le Gouët, J.-L.; Bretenaker, F.

2009-02-01

61

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

ERIC Educational Resources Information Center

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

Rodriguez, Maria A.; Niaz, Mansoor

2002-01-01

62

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

Microsoft Academic Search

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

Ingo Eilks

2005-01-01

63

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

PubMed

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

Niaz, Mansoor; Cardellini, Liberato

2011-12-01

64

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

65

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" wave—an 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

66

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.

67

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

68

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

69

Effects of atomic chlorine wall recombination: Comparison of a plasma chemistry model with experiment  

SciTech Connect

Results from a plasma chemistry model provide predictions of spatially and temporally averaged plasma properties. Application of the model to chlorine-etch process conditions, typical of a high plasma-density transformer coupled plasma reactor, provides plasma composition dependence on reactor operating parameter such as power and pressure. Model results also show the dependence of species concentrations on the atomic-chlorine recombination rate at reactor walls. Comparison of model predictions to measured composition trends as determined by Langmuir probe, actinometry, and ion-energy analysis reveals a critical wall-recombination probability of about 0.1 for chlorine atoms on a chlorinated anodized-aluminum surface. At or above this critical value, the model reproduces the experimentally observed trends, while employing a recombination probability below this value results in predictions that are inconsistent with the data. The model determines gas-phase and surface-species compositions in plasma-etch reactors through the solution of species, mass, electron-energy, and surface-site conservation equations. The use of well mixed reactor approximations reduces the computational expense of detailed kinetics calculations and allows investigation into the dependence of plasma chemistry on uncertain kinetic parameters. The dominance of surface reaction rates in determining plasma properties is expected to be equally important in more complex two-dimensional inductively coupled plasma models due to the highly diffuse nature of these low-pressure reactors. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

Meeks, E.; Shon, J.W. [Sandia National Laboratories, Livermore, California 94551-0969 (United States)] [Sandia National Laboratories, Livermore, California 94551-0969 (United States); Ra, Y.; Jones, P. [Lam Research Corporation, Fremont, California 94538-6401 (United States)] [Lam Research Corporation, Fremont, California 94538-6401 (United States)

1995-11-01

70

Thermal chemistry of the Cu-KI5 atomic layer deposition precursor on a copper surface  

SciTech Connect

The thermal chemistry of a Cu(I) ketoiminate complex, Cu-KI5, resulting from the modification of the known Air Products CupraSelect{sup ®} copper CVD precursor Cu(hfac)(tmvs) designed to tether the two ligands via an isopropoxide linker, was studied under ultrahigh vacuum on a Cu(110) single-crystal surface by using a combination of temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy. Adsorption at low temperatures was determined to take place via the displacement of the vinyl ligand by the surface. Molecular desorption was seen at 210?K, and the evolution of Cu(II)-KI5{sub 2} was established to take place at 280?K, presumably from a disproportionation reaction that also leads to the deposition of Cu(0). Other sets of desorption products were seen at 150, 250, and 430?K, all containing copper atoms and small organic moieties with molecular masses below 100 amu. The latter TPD peak in particular indicates significant fragmentation of the ligands, likely at the C–N bond that holds the vinylsilane-isopropoxide moiety tethered to the ketoimine fragment, and possibly also at the union between the vinylsilane and the alkoxide linker. The 430?K temperature measured for this chemistry may set an upper limit for clean Cu film deposition, but since reactivity on the surface was also found to be inhibited at higher surface coverages, it may be delayed to higher temperatures under atomic layer deposition conditions.

Ma, Qiang; Zaera, Francisco, E-mail: zaera@ucr.edu [Department of Chemistry, University of California, Riverside, California 92521 (United States)

2015-01-01

71

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

PubMed

Conspectus Hot wire chemical vapor deposition (HWCVD), also referred to as catalytic CVD (Cat-CVD), has been used to produce Si-containing thin films, nanomaterials, and functional polymer coatings that have found wide applications in microelectronic and photovoltaic devices, in automobiles, and in biotechnology. The success of HWCVD is largely due to its various advantages, including high deposition rate, low substrate temperatures, lack of plasma-induced damage, and large-area uniformity. Film growth in HWCVD is induced by reactive species generated from primary decomposition on the metal wire or from secondary reactions in the gas phase. In order to achieve a rational and efficient optimization of the process, it is essential to identify the reactive species and to understand the chemical kinetics that govern the production of these precursor species for film growth. In this Account, we report recent progress in unraveling the complex gas-phase reaction chemistry in the HWCVD growth of silicon carbide thin films using organosilicon compounds as single-source precursors. We have demonstrated that laser ionization mass spectrometry is a powerful diagnostic tool for studying the gas-phase reaction chemistry when combined with the methods of isotope labeling and chemical trapping. The four methyl-substituted silane molecules, belonging to open-chain alkylsilanes, dissociatively adsorb on W and Ta filaments to produce methyl radical and H2 molecule. Under the typical deposition pressures, with increasing number of methyl substitution, the dominant chemistry occurring in the gas phase switches from silylene/silene reactions to free-radical short chain reactions. This change in dominant reaction intermediates from silylene/silene to methyl radicals explains the observation from thin film deposition that silicon carbide films become more C-rich with a decreasing number of Si-H bonds in the four precursor molecules. In the case of cyclic monosilacyclobutanes, we have shown that ring-opening reactions play a vital role in characterizing the reaction chemistry. On the other hand, exocyclic Si-H(CH3) bond cleavages are more important in the less-puckered disilacyclobutane molecules. Metal filaments are essential in HWCVD since they serve as catalysts to decompose precursor gases to reactive species, which initiate gas-phase reaction chemistry and thin film growth. We discuss the structural changes in metal filaments when exposed to various precursor gases. Depending on the nature of the radical intermediates formed from the hot-wire decomposition and subsequent gas-phase reactions, metal silicides and carbides can be formed. Overall, study of the gas-phase reaction chemistry in HWCVD provides important knowledge of the chemical species produced prior to their deposition on a substrate surface. This helps in identifying the major contributor to alloy formation on the filament itself and the film growth, and consequently, in determining the properties of the deposited films. An integrated knowledge of the gas-phase reaction chemistry, filament alloy formation, and thin film deposition is required for an efficient deposition of high-quality thin films and nanomaterials. PMID:25586211

Shi, Yujun

2015-02-17

72

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

Gonçalves, Gil; Vila, Mercedes; Bdikin, Igor; de Andrés, Alicia; Emami, Nazanin; Ferreira, Rute A. S.; Carlos, Luís D.; Grácio, José; Marques, Paula A. A. P.

2014-01-01

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.

Gonçalves, Gil; Vila, Mercedes; Bdikin, Igor; de Andrés, Alicia; Emami, Nazanin; Ferreira, Rute A. S.; Carlos, Luís D.; Grácio, José; Marques, Paula A. A. P.

2014-10-01

74

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

Microsoft Academic Search

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

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

1997-01-01

75

Atomic Scale Structure-Chemistry Relationships at Oxide Catalyst Surfaces and Interfaces  

NASA Astrophysics Data System (ADS)

Oxide catalysts are integral to chemical production, fuel refining, and the removal of environmental pollutants. However, the atomic-scale phenomena which lead to the useful reactive properties of catalyst materials are not sufficiently understood. In this work, the tools of surface and interface science and electronic structure theory are applied to investigate the structure and chemical properties of catalytically active particles and ultrathin films supported on oxide single crystals. These studies focus on structure-property relationships in vanadium oxide, tungsten oxide, and mixed V-W oxides on the surfaces of alpha-Al2O3 and alpha-Fe2O 3 (0001)-oriented single crystal substrates, two materials with nearly identical crystal structures but drastically different chemical properties. In situ synchrotron X-ray standing wave (XSW) measurements are sensitive to changes in the atomic-scale geometry of single crystal model catalyst surfaces through chemical reaction cycles, while X-ray photoelectron spectroscopy (XPS) reveals corresponding chemical changes. Experimental results agree with theoretical calculations of surface structures, allowing for detailed electronic structure investigations and predictions of surface chemical phenomena. The surface configurations and oxidation states of V and W are found to depend on the coverage of each, and reversible structural shifts accompany chemical state changes through reduction-oxidation cycles. Substrate-dependent effects suggest how the choice of oxide support material may affect catalytic behavior. Additionally, the structure and chemistry of W deposited on alpha-Fe 2O3 nanopowders is studied using X-ray absorption fine structure (XAFS) measurements in an attempt to bridge single crystal surface studies with real catalysts. These investigations of catalytically active material surfaces can inform the rational design of new catalysts for more efficient and sustainable chemistry.

McBriarty, Martin E.

76

Modelling of configurational transitions in atomic Department of Chemistry, University of Chicago -929 East 57th St., Chicago, IL 60637,  

E-print Network

1 Modelling of configurational transitions in atomic systems R.S.Berry Department of Chemistry.e. transitions that change the system's geometric structure, include chemical reactions in gases, transitions in clusters of inert gases . . . . . . . . . . . . . . . . . . . . 20 3.2 Phase transitions in simple clusters

Berry, R. Stephen

77

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

ERIC Educational Resources Information Center

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

Pfennig, Brian W.; Schaefer, Amy K.

2011-01-01

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

Realistic theory of electromagnetically-induced transparency and slow light in a hot vapor of atoms undergoing collisions  

E-print Network

We present a realistic theoretical treatment of a three-level $\\Lambda$ system in a hot atomic vapor interacting with a coupling and a probe field of arbitrary strengths, leading to electromagnetically-induced transparency and slow light under the two-photon resonance condition. We take into account all the relevant decoherence processes including col5Blisions. Velocity-changing collisions (VCCs) are modeled in the strong collision limit effectively, which helps in achieving optical pumping by the coupling beam across the entire Doppler profile. The steady-state expressions for the atomic density-matrix elements are numerically evaluated to yield the experimentally measured response characteristics. The predictions, taking into account a dynamic rate of influx of atoms in the two lower levels of the $\\Lambda$, are in excellent agreement with the reported experimental results for $^4$He*. The role played by the VCC parameter is seen to be distinct from that by the transit time or Raman coherence decay rate.

Joyee Ghosh; R. Ghosh; F. Goldfarb; J. -L. Le Gouët; F. Bretenaker

2009-01-23

80

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

81

Probing the Chemistry and Dynamics of Hot Molecular Cores Using Highly Excited Cyanopolyynic Transitions  

NASA Astrophysics Data System (ADS)

A hyperfine line fitting program is presented, which decomposes an observed rotational transition into its individual hyperfine components. The fit is optimized by the use of the Levenberg-Marquardt algorithm (for non-linear fitting) or Caruana's algorithm (linearization of the Gaussian function). From the optimal fit, various parameters from the decomposed components are derived such as the linewidth dispersion, peak brightness temperature and peak position in velocity units. The closeness in frequency units of two neighbouring hyperfine components within a rotational transition spectrum allows the derivation of a more credible estimate of the optical depth for the observed source of emission. Effective smoothing of the data subsequent to the fitting procedure greatly reduces the perceived error in the determination of various physical conditions of the observed region. The technique has been employed in observations of massive hot molecular cores (HMCs), considered to be the birthplace of high mass stars. In particular, observations of the cyanopolyynes HC_3N and HC_5N, each of which include a quadrupole hyperfine structure, as well as methyl cyanide, CH_3CN, have been analysed with this technique and modelled with a radiative transfer code incorporating non-LTE conditions, in order to derive abundances and column densities for a total of 10 HMCs and 5 massive cores. Using these derived parameters for each core, we have been able to test the time-dependent chemical models presented for these species by Chapman et al. (2009) and thus verify the suitability of their usefulness as "chemical clocks" by which to constrain the ages of the observed objects. In addition to this work, a detailed study of the magnetic hyperfine structure of a selection of inversion transitions of NH_3 is presented. As part of the continuing preparatory work for Herschel, SOFIA and, in particular, ALMA - improved rest frequencies for this commonly used kinetic temperature detecting species in star-forming cores will be forthcoming.

Loughnane, Robert John; Lique, François; Singh, Navtej; Kurtz, Stan

2014-06-01

82

Ion-atom charge-transfer reactions and a hot intercloud medium. [in interstellar space  

NASA Technical Reports Server (NTRS)

An investigation is conducted concerning the ionization equilibrium of carbon in a hot intercloud medium (ICM), taking into account various charge-transfer reactions. Attention is given to problems related to observations of carbon along the lines of sight to several unreddened stars. It is pointed out that the observed underabundance of C III and overabundance of C I can be consistent with the presence of a hot, partially ionized ICM, provided that two of the charge-transfer reactions considered are rapid at thermal energies.

Steigman, G.

1975-01-01

83

Chemistry  

NSDL National Science Digital Library

These sites willhelp you gain greater understanding of Chemistry! Weather is also available Three areas to be on the test. STUDY HARD!!!! Equations Types of Equations Types of Equations text/htmlMichigan Teacher Network Matter Density of solids Density of solids text/htmlICSD ScienceZone Metals Kidneys and Metals Problem Set Kidneys and Metals Problem Set image/tiffCenter for Digital Curriculum Research POTENTIAL SURROGATE METALS FOR INCINERATOR TRIAL BURNS POTENTIAL SURROGATE METALS FOR INCINERATOR TRIAL BURNS text/html Let it snow Interactive Weather Maker Interactive Weather Maker urlexample ...

Riley

2006-04-22

84

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.

85

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

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

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

88

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

89

Surface chemistry of the atomic layer deposition of metals and group III oxides  

NASA Astrophysics Data System (ADS)

Atomic Layer Deposition (ALD) is a thin-film growth technique offering precise control of film thickness and the ability to coat high-aspect-ratio features such as trenches and nanopowders. Unlike other film growth techniques, ALD does not require harsh processing conditions and is not limited by line-of-sight deposition. Emerging applications for ALD materials include semiconductor devices, gas sensors, and water-diffusion barriers. The chemistry behind ALD involves understanding how the precursors interact with surfaces to deposit the desired material. All ALD precursors need to be stable on the substrate to ensure self-limiting behavior yet reactive enough to be easily removed with the second reagent. Recent precursor development has provided many volatile organometallic compounds for most of the periodic table. As the number of precursors increases, proper precursor choice becomes crucial. This is because the film properties, growth rates, and growth temperature vary widely between the precursors. Many of the above traits can be predicted with knowledge of the precursor reaction mechanisms. This thesis aims to link surface reaction mechanisms to observed growth and nucleation trends in metal and oxide ALD systems. The first portion of this thesis explores the mechanisms of two ALD oxide systems. First, I examine the mechanism of ALD alumina with ozone. Ozone is used as an oxidant in the semiconductor industry because the deposited Al 2O3 films possess better insulating properties and ozone is easier to purge from a vacuum system. FT-IR analysis reveals a complicated array of surface intermediates such as formate, carbonate, and methoxy groups that form during Al2O3 growth with ozone. Next, a new method to deposit thin films of Ga2O3 is introduced. Gallium oxide is a transparent conducting oxide that needs expensive solid precursors to be deposited by ALD. I show that trimethylgallium is a good high-temperature ALD precursor that deposits films of Ga2O 3 with low impurities and a good growth rate. The second section of this thesis focuses on two metal ALD systems. One major drawback of metal ALD systems is their inability to nucleate on many oxide surfaces. This greatly limits the applications of metal ALD for interconnects and flexible electrodes. The first emphasis is an on a new palladium ALD system using palladium (II) hexafluoroacetylaceonate (Pd(hfac)2) and formalin. FT-IR studies show that the Pd(hfac)2 dissociatively adsorbs, releasing free hfacH molecules that bind to Lewis acid sites on the alumina. The observed nucleation period of Pd is linked to surface poisoning by hfacH. In a related experiment, I use trimethylaluminum exposures to remove excess hfacH from the surface. Trimethylaluminum is able to ligand exchange an easier to remove methyl group with the surface hfacH, This treatment causes palladium to nucleate much more rapidly and deposit at lower temperatures. Finally, I examine ToRuS, a new precursor solution for Ru ALD. ToRuS, a solution of RuO4 in perfluoroethers, deposits ruthenium faster and at lower temperatures than all other Ru precursors. The mechanism for deposition and role of the perfluoroethers, however, is poorly understood. In the first study, I couple FT-IR spectroscopy with ab-initio calculations to identify the surface species formed when the perfluoroether solvent adsorbs on alumina. These surface species bind strongly to the alumina surface, creating a nonpolar, fluorinated layer. I then use these results to understand how ToRuS deposits Ru films. The fluorinated layer solvates RuO4, stabilizing it near the surface until it can be reduced by H2 gas. FT-IR and XPS analysis shows that the fluorinated layer does not leave carbonaceous impurities on the ruthenium surface or impedes metal deposition.

Goldstein, David Nathan

90

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

91

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

92

Atomic carbon emission from photodissociation of CO2. [planetary atmospheric chemistry  

NASA Technical Reports Server (NTRS)

Atomic carbon fluorescence, C I 1561, 1657, and 1931 A, has been observed from photodissociation of CO2, and the production cross sections have been measured. A line emission source provided the primary photons at wavelengths from threshold to 420 A. The present results suggest that the excited carbon atoms are produced by total dissociation of CO2 into three atoms. The cross sections for producing the O I 1304-A fluorescence through photodissociation of CO2 are found to be less than 0.01 Mb in the wavelength region from 420 to 835 A. The present data have implications with respect to photochemical processes in the atmospheres of Mars and Venus.

Wu, C. Y. R.; Phillips, E.; Lee, L. C.; Judge, D. L.

1978-01-01

93

A large atomic chlorine source inferred from mid-continental reactive nitrogen chemistry.  

PubMed

Halogen atoms and oxides are highly reactive and can profoundly affect atmospheric composition. Chlorine atoms can decrease the lifetimes of gaseous elemental mercury and hydrocarbons such as the greenhouse gas methane. Chlorine atoms also influence cycles that catalytically destroy or produce tropospheric ozone, a greenhouse gas potentially toxic to plant and animal life. Conversion of inorganic chloride into gaseous chlorine atom precursors within the troposphere is generally considered a coastal or marine air phenomenon. Here we report mid-continental observations of the chlorine atom precursor nitryl chloride at a distance of 1,400 km from the nearest coastline. We observe persistent and significant nitryl chloride production relative to the consumption of its nitrogen oxide precursors. Comparison of these findings to model predictions based on aerosol and precipitation composition data from long-term monitoring networks suggests nitryl chloride production in the contiguous USA alone is at a level similar to previous global estimates for coastal and marine regions. We also suggest that a significant fraction of tropospheric chlorine atoms may arise directly from anthropogenic pollutants. PMID:20220847

Thornton, Joel A; Kercher, James P; Riedel, Theran P; Wagner, Nicholas L; Cozic, Julie; Holloway, John S; Dubé, William P; Wolfe, Glenn M; Quinn, Patricia K; Middlebrook, Ann M; Alexander, Becky; Brown, Steven S

2010-03-11

94

He-Ion and Self-Atom Induced Damage and Surface-Morphology Changes of a Hot W Target  

SciTech Connect

We report results of measurements on the evolution of the surface morphology of a hot tungsten surface due to impacting low-energy (80 12,000 eV) He ions and of simulations of damage caused by cumulative bombardment of 1 and 10 keV W self-atoms. The measurements were performed at the ORNL Multicharged Ion Research Facility (MIRF), while the simulations were done at the Kraken supercomputing facility of the University of Tennessee. At 1 keV, the simulations show strong defect-recombination effects that lead to a saturation of the total defect number after a few hundreds impacts, while sputtering leads to an imbalance of the vacancy and interstitial number. On the experimental side, surface morphology changes were investigated over a broad range of fluences for both virgin and pre-damaged W-targets. At the lowest accumulated fluences, small surface-grain features and near-surface He bubbles are observed. At the largest fluences, individual grain characteristics disappear in FIB/SEM scans, and the entire surface is covered by a multitude of near-surface bubbles with a broad range of sizes, and disordered whisker growth, while in top-down SEM imaging the surface is virtually indistinguishable from the nano-fuzz produced on linear plasma devices. These features are evident at progressively lower fluences as the He-ion energy is increased.

Meyer, Fred W [ORNL; Hijazi, Hussein Dib [ORNL; Krstic, Predrag S [ORNL; Dadras, Mostafa Jonny [ORNL; Meyer III, Harry M [ORNL; Parish, Chad M [ORNL; Bannister, Mark E [ORNL

2014-01-01

95

He-ion and self-atom induced damage and surface-morphology changes of a hot W target  

NASA Astrophysics Data System (ADS)

We report results of measurements on the evolution of the surface morphology of a hot tungsten surface due to impacting low-energy (80-12?000 eV) He ions and of simulations of damage caused by cumulative bombardment of 1 and 10 keV W self-atoms. The measurements were performed at the ORNL Multicharged Ion Research Facility, while the simulations were done at the Kraken supercomputing facility of the University of Tennessee. At 1 keV, the simulations show strong defect-recombination effects that lead to a saturation of the total defect number after a few hundred impacts, while sputtering leads to an imbalance of the vacancy and interstitial number. On the experimental side, surface morphology changes were investigated over a broad range of fluences, energies and temperatures for both virgin and pre-damaged W-targets. At the lowest accumulated fluences, small surface-grain features and near-surface He bubbles are observed. At the largest fluences, individual grain characteristics disappear in focused ion beam/scanning electron microscopy (FIB/SEM) scans, and the entire surface is covered by a multitude of near-surface bubbles with a broad range of sizes, and disordered whisker growth, while in top-down SEM imaging the surface is virtually indistinguishable from the nano-fuzz produced on linear plasma devices. These features are evident at progressively lower fluences as the He-ion energy is increased.

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

2014-04-01

96

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

97

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 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 Dalton’s 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, Hélio Elael Bonini; Porto, Paulo Alves

2010-01-01

98

Analysis of the Essential Nutrient Strontium in Marine Aquariums by Atomic Absorption Spectroscopy: An Undergraduate Analytical Chemistry Laboratory Exercise  

NASA Astrophysics Data System (ADS)

An undergraduate atomic absorption spectroscopy (AAS) laboratory experiment is presented involving the analysis of the essential nutrient strontium in a real-life sample, sea water. The quantitative analysis of strontium in sea water is a problem well suited for an undergraduate analytical chemistry laboratory. Sea water contains numerous components which prevent the direct quantitative determination of strontium. Students learn first hand about the role of interferences in analytical measurements, and about the method of standard addition which is used to minimize these effects. This laboratory exercise also introduces undergraduate students to practical problems associated with AAS. We encourage students as a part of this experiment to collect and analyze marine water samples from local pet shops.

Gilles de Pelichy, Laurent D.; Adam, Carl; Smith, Eugene T.

1997-10-01

99

Fascinating hydrogen atom transfer chemistry of alkenes inspired by problems in total synthesis.  

PubMed

The magical HAT: Radical hydrofunctionalization processes of alkenes recently witnessed tremendous progress. The coupling of heteroatom-substituted alkenes was achieved by means of catalytic hydrogen atom transfer (HAT), enabling the construction of functionalized quaternary centers with unusual ease. Challenging thermodynamically controlled hydrogenations and isomerizations of alkenes as well as reductions of vinyl halides were accomplished using HAT processes. PMID:25703197

Simonneau, Antoine; Oestreich, Martin

2015-03-16

100

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

SciTech Connect

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

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

1987-04-24

101

State-specific reactions of atomic transition-metal ions with Hâ, HD, and Dâ: effects of d orbitals on chemistry  

Microsoft Academic Search

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

J. L. Elkind; P. B. Armentrout

1987-01-01

102

Carbon atom, dimer and trimer chemistry on diamond surfaces from molecular dynamics simulations  

SciTech Connect

Spectroscopic studies of various atmospheres appearing in diamond film synthesis suggest evidence for carbon atoms, dimers, or trimers. Molecular dynamics simulations with the Brenner hydrocarbon potential are being used to investigate the elementary reactions of these species on a hydrogen-terminated diamond (111) surface. In principle these types of simulations can be extended to simulations of growth morphologies, in the 1-2 monolayer regime presently.

Valone, S.M.

1995-07-01

103

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

104

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

105

Hot Canyon  

ScienceCinema

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

None

2013-03-01

106

Atmospheric Chemistry of t-CF3CF=CHCl: Reactions with Cl Atoms, OH Radicals and Ozone  

NASA Astrophysics Data System (ADS)

Recognition of the adverse environmental consequences of the release of chlorofluorocarbons (CFCs) and Halons into the atmosphere has led to an international effort to replace these compounds with environmentally acceptable alternatives. While safeguarding the stratospheric ozone layer has been at the forefront of these efforts, concerns related to global climate change are becoming an increasingly important consideration in the choice of alternative compounds because of their significant atmospheric lifetime and radiative properties. Saturated hydrofluorocarbons (HFCs), such as CH2FCF3 (HFC-134a), have become widely used CFC replacements. HFCs do not contain chlorine and therefore do no contribute to the chlorine based catalytic destruction of stratospheric ozone. The atmospheric lifetime of HFCs is determined by their reactivity towards OH radicals. Saturated HFCs such as HFC-134a display modest reactivity towards OH radicals and hence have modest global warming potentials. Trans-3,3,3-trifluoro-1-chloro-propene (t-CF3CH=CHCl), is an unsaturated hydrochlorofluorocarbon (HCFC), which has been developed as a potential replacement for CFCs and saturated HFCs. Prior to any large-scale industrial use an assessment of the atmospheric chemistry, and hence, environmental impact of t-CF3CH=CHCl), is needed. Smog chamber/FTIR techniques were used to determine the following properties for t-CF3CH=CHCl: (i) kinetics of reactions with chlorine atoms (ii) kinetics of reactions with hydroxyl radicals (iii) kinetics of reactions with ozone, (iv) atmospheric lifetimes, (v) atmospheric degradation mechanism, and (vi) global warming potentials. The atmospheric lifetime of t- CF3CH=CHCl is determined by reaction with OH radicals and is approximately 26 days. The global warming potential of t-CF3CH=CHCl is approximately 7 for a 100 year time horizon. The results are discussed with regard to the environmental impact of t-CF3CF=CHCl and the atmospheric chemistry of unsaturated hydrochlorofluorocarbons.

Sulbaek Andersen, M. P.; Nielsen, O. J.; Nilsson, E. J.; Johnson, M. S.

2008-12-01

107

The effects of solution chemistry on the sticking efficiencies of viable Enterococcus faecalis: An atomic force microscopy and modeling study  

NASA Astrophysics Data System (ADS)

Atomic force microscopy (AFM) and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory in combination with the interaction force boundary layer (IFBL) model have been used to empirically and theoretically calculate sticking efficiencies (?) of Enterococcus faecalis cells against a silica glass surface. Sticking efficiencies were calculated in solutions of varying pH and ionic strength and related to maximum distances of transport through a hypothetical soil block using colloid filtration theory. AFM measurements show that the repulsive and attractive forces between E. faecalis cells and a glass surface are a function of ionic strength but are less sensitive to changes in solution pH. Zeta (?)-potential measurements of the cells and glass surfaces correlate with these trends. Calculated DLVO energy profiles predict much greater sensitivity to changing solution chemistry. Sticking efficiencies derived from AFM measurements range from 9.6 × 10 -17 to 1 in solutions of low ionic strength (IS) and from 2.6 × 10 -33 to 1 at higher IS. Corresponding ? values determined from DLVO theory are essentially zero in all tested solutions. Sticking efficiencies calculated in this study are smaller than values determined from column and field studies in similar systems; however, ? derived from AFM data and the IFBL model more closely represent field data than do values calculated from DLVO energy values. A comparison with different methods of calculating ? suggests that reversible adhesion may be significant in column-scale transport studies.

Cail, Tracy L.; Hochella, Michael F.

2005-06-01

108

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

PubMed Central

The superlative electronic properties of graphene suggest its use as the foundation of next generation integrated circuits. However, this application requires precise control of the interface between graphene and other materials, especially the metal oxides that are commonly used as gate dielectrics. Towards that end, organic seeding layers have been empirically shown to seed ultrathin dielectric growth on graphene via atomic layer deposition (ALD), although the underlying chemical mechanisms and structural details of the molecule/dielectric interface remain unknown. Here, confocal resonance Raman spectroscopy is employed to quantify the structure and chemistry of monolayers of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on graphene before and after deposition of alumina with the ALD precursors trimethyl aluminum (TMA) and water. Photoluminescence measurements provide further insight into the details of the growth mechanism, including the transition between layer-by-layer growth and island formation. Overall, these results reveal that PTCDA is not consumed during ALD, thereby preserving a well-defined and passivating organic interface between graphene and deposited dielectric thin films. PMID:22905282

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

2012-01-01

109

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

110

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

111

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

E-print Network

Surface chemistry and infrared absorbance changes during ZnO atomic layer deposition on ZrO2 and Ba deposition (ALD) was achieved using sequential exposures of Zn CH2CH3 2 and H2O on ZrO2 and BaTiO3 particles spectroscopy. The BaTiO3 and ZrO2 particles initially displayed vibrational features consistent with surface

George, Steven M.

112

Connected Chemistry  

NSDL National Science Digital Library

Connected Chemistry, a novel learning environment for teaching chemistry, is appropriate for use in both high school and undergraduate chemistry classrooms. Connected Chemistry comprises several molecular simulations designed to enable instructors to teach chemistry using the perspective of emergent phenomena. That is, it allows students to see observed macro-level chemical phenomena, like many other scientific phenomena, as resultant from the interactions of many individual agents on a micro-level. This perspective is especially appropriate to the study of chemistry where the interactions between multitudes of molecules on the atomic level give rise to the macro-level concepts that students study in the classroom. Connected Chemistry comprises molecular simulations embedded in the NetLogo modeling software (1). The collection contains several predesigned simulations of closed chemical systems to teach specific chemistry concepts. Currently, Connected Chemistry contains models for teaching Brønsted Lowry acid base theory, enzyme kinetics, radical polymerization, buffer chemistry, kinetics, chemical equilibrium, and crystallization. Instructors and students can individually tailor the predesigned simulations or generate new simulations as they are needed in the context of a particular lesson, classroom, or department.

113

New precursors and chemistry for the growth of transition metal films by atomic layer deposition  

NASA Astrophysics Data System (ADS)

The advancing complexity of advanced microelectronic devices is placing rigorous demands on currently used PVD and CVD deposition techniques. The ALD deposition method is proposed to meet the film thickness and conformality constraints needed by the semiconductor industry in future manufacturing processes. Unfortunately, there is a limited number of chemical precursors available that have high thermal stability, reactivity, and vapor pressure suitable for ALD film growth to occur. These properties collectively contribute to the lack of suitable transition metal precursors available for use in ALD. In this thesis, we report the discovery of a series of novel transition metal diazadienate precursors that promising properties deemed suitable for ALD. The volatility and thermal stability of the new transition metal diazadienyl compounds were studied by preparative sublimation and capillary tube melting point/decomposition experiments. Thermogravimetric analyses (TGA) demonstrate precursor residues of less than 4% at 500 °C. In addition, sublimation data, melting points, and decomposition temperatures for all complexes are presented. The manganese diazadienyl complex has the highest decomposition temperature of the series of complexes produced (325 °C). During preparative sublimations, the product recoveries of all transition metal diazadienyl complexes were greater than 92.0% with nonvolatile residues of less than 7.0%. This is an excellent indication that these complexes may be suitable candidates as metal precursors for ALD. Nickel nitride (NixN) films have been studied as an intermediate material for the formation of both nickel metal and nickel silicide using chemical vapor deposition. Herein, we describe the ALD growth of nickel nitride thin films from bis(1,4-di-tert-butyl-1,3-diazabutadiene) nickel(II) (Ni(tBu2DAD)2) and 1,1-dimethylhydrazine. An ALD window for the deposition of nickel nitride films on 500 nm thermal SiO2 substrates was observed between 225 and 240 °C with a constant growth rate of 0.70 Å/cycle. X-Ray photoelectron spectroscopy (XPS) showed all expected ionizations with carbon concentrations below the detection limit after argon ion sputtering. Due to preferential nitrogen sputtering in XPS, Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) were performed and subsequently revealed Ni:N ratios between 2-4 for films deposited within the ALD window. AFM measurements revealed a RMS roughness value of 10.8 nm on an as-deposited film at 225°C. All as-deposited films were amorphous as determined by X-ray diffraction. Copper is the primary interconnect material in microelectronics devices, due to its high conductivity and low affinity towards electromigration. With transistor gate lengths scheduled to reach 14 nm by 2014, there are severe demands upon the current film growth techniques used in device fabrication. The ALD film growth method is ideally suited for future microelectronics manufacturing, since it inherently provides highly conformal thin films, even in high aspect ratio nanoscale features, and allows sub-nanometer control over film thicknesses. In Chapter 4, we describe the atomic layer deposition of high purity, low resistivity copper metal thin films using a three precursor sequence entailing Cu(dmap)2, formic acid, and hydrazine. In this process, Cu(dmap) 2 is unreactive towards hydrazine but is transformed to copper(II) formate, which is then readily reduced to copper metal by subsequent hydrazine exposure. The present work therefore addresses a central problem with the ALD growth of metal thin films: low reactivity of metal precursors toward common reducing agents. A constant growth rate of 0.47-0.50 Å/cycle upon prime grade Si(100) was observed at substrate temperatures between 100 and 170 °C. Compositional analyses (XPS and TOF-ERDA) revealed copper films with low levels of carbon, oxygen, nitrogen, and hydrogen. Powder X-ray diffraction spectra of all films showed polycrystalline copper. The resistivities of films grown between 100 and 140 °C ranged b

Knisley, Thomas Joseph

114

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

115

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

116

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.

Eric Muller

2007-01-01

117

Fluorine hot atom oxidation of bismuth vapor. A comment on the evaluation of the BiF bond energy  

NASA Astrophysics Data System (ADS)

The energetics of the chemiluminescent reaction between bismuth dimers and fluorine atoms (T.C. Devore et al., Chem. Phys. 155 (1991) 423; 156 (1991) 156) has been evaluated to better refine a determination of the bismuth fluoride dissociation energy. By directly examining the spectrum of the SF 6 discharge used to generate the F atoms to establish the significant energy imparted to these dissociation products and by exploring F atom chemiluminescent reactions with known energetics, the F atom beam is established to have contributed a maximum of 0.8-0.9 eV to the chemiluminescent process. Based upon the observed population of the ?'=4 level of the BiF A0 + state resulting from the Bi 2 + F reaction, a BiF bond energy of 3.9 ± 0.2 eV is established. This value is slightly higher than a very recent evaluation of the BiF bond energy (Yoo et al., Chem. Phys. 166 (1992) 215) but disagrees with previous determinations in the literature. Many of the previous evaluations of the group 15 halide dissociation energies have been based on Birge—Sponer extrapolations. The data now available for BiF permits an evaluation of the nature of these extrapolations for this molecule. The limitations of these extrapolations and possible corrections for these shortcomings are presented.

Devore, T. C.; Gole, J. L.

1993-08-01

118

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

119

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

PubMed

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

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

2011-12-01

120

Exchange and polarization effects in the elementary excitation spectrum of a hydrogen atom immersed in a hot plasma  

SciTech Connect

The one-particle hydrogenic Green's function has been calculated for a partially ionized plasma consisting of hydrogen atoms, electrons, and protons at high temperatures. The theoretical method extends a previous publication and involves an evaluation of the mass operator in the Dyson equation to include proper self-energy parts to ''all orders'' in the screened interaction. This mass operator characterizes the effective micropotential felt by the atom in the plasma and determines all of the one-particle properties and some two-particle properties associated with the atomic subsystem. The first-order mass operator is nonzero only for exchange scattering, which leads to a frequency-independent exchange shift. This temperature- and density-dependent theory of the exchange shift replaces the usual semiphenomenological schemes based on the Slater-Kohn-Sham type of theory. The exchange-shifted Green's functions are used in evaluating the higher-order contributions. Computer calculations and the resolution of the poles of the Green's function lead to level shifts, widths, and spectral functions. These are calculated within both the second-order and the all-order theory. The second-order theory, which may be valid at sufficiently high densities and in turbulent plasmas, overemphasises the atom-plasmon coupling and shows new structures. The inclusion of contributions beyond second order removes these structures and produces a more ''conventional'' spectral-intensity function. The effects of center-of-mass motion on the level shifts and level profiles are investigated and the onset of plasma instabilities touched upon. These calculations make contact with the work on ''plasma-polarization shifts'' and provide an approach to q,..omega..-dependent plasma microfields.

Dharma-wardana, M.W.C.; Grimaldi, F.; Lecourt, A.; Pellissier, J.

1980-01-01

121

Chemistry on Stamps.  

ERIC Educational Resources Information Center

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

Schreck, James O.

1986-01-01

122

CHEMISTRY CURRICULUM SEMESTER I  

E-print Network

CHEMISTRY CURRICULUM SEMESTER ­ I Chemistry-I: Physical principles (2:1) Atomic structure. Gas laws, mean free path, viscosity, Maxwell-Boltzmann distribution of velocity, real gases, van der-state approximation, Arrhenius equation and collision theory and catalysis. SEMESTER ­ II Chemistry-II: Structure

Srinivasan, N.

123

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

124

College Chemistry Students' Understanding of Potential Energy in the Context of Atomic-Molecular Interactions  

ERIC Educational Resources Information Center

Understanding the energy changes that occur as atoms and molecules interact forms the foundation for understanding the macroscopic energy changes that accompany chemical processes. In order to identify ways to scaffold students' understanding of the connections between atomic-molecular and macroscopic energy perspectives, we conducted a…

Becker, Nicole M.; Cooper, Melanie M.

2014-01-01

125

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

ERIC Educational Resources Information Center

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

Eilks, Ingo

2005-01-01

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

Pressure and electrical resistivity measurements on hot expanded nickel: comparisons with quantum molecular dynamics simulations and average atom approaches.  

PubMed

We present experimental results on pressure and resistivity on expanded nickel at a density of 0.1 g/cm3 and temperature of a few eV. These data, corresponding to the warm dense matter regime, are used to benchmark different theoretical approaches. A comparison is presented between fully three-dimensional quantum molecular dynamics (QMD) methods, based on density functional theory, with average atom methods, that are essentially one dimensional. In this regime the evaluation of the thermodynamic properties as well as electrical properties is difficult due to the concurrence of density and thermal effects which directly drive the metal-nonmetal transition. Experimental pressures and resistivities are given in a tabular form with temperatures deduced from QMD simulations. PMID:21230400

Clérouin, Jean; Starrett, Charles; Faussurier, Gérald; Blancard, Christophe; Noiret, Pierre; Renaudin, Patrick

2010-10-01

128

Atmospheric chemistry of n-butanol: kinetics, mechanisms, and products of Cl atom and OH radical initiated oxidation in the presence and absence of NO(x).  

PubMed

Smog chamber/FTIR techniques were used to determine rate constants of k(Cl+n-butanol) = (2.21 +/- 0.38) x 10(-10) and k(OH+n-butanol) = (8.86 +/- 0.85) x 10(-12) cm(3) molecule(-1) s(-1) in 700 Torr of N(2)/O(2) diluent at 296 +/- 2K. The sole primary product identified from the Cl atom initiated oxidation of n-butanol in the absence of NO was butyraldehyde (38 +/- 2%, molar yield). The primary products of the Cl atom initiated oxidation of n-butanol in the presence of NO were (molar yield) butyraldehyde (38 +/- 2%), propionaldehyde (23 +/- 3%), acetaldehyde (12 +/- 4%), and formaldehyde (33 +/- 3%). The substantially lower yields of propionaldehyde, acetaldehyde, and formaldehyde as primary products in experiments conducted in the absence of NO suggests that chemical activation is important in the atmospheric chemistry of CH(3)CH(2)CH(O)CH(2)OH and CH(3)CH(O)CH(2)CH(2)OH alkoxy radicals. The primary products of the OH radical initiated oxidation of n-butanol in the presence of NO were (molar yields) butyraldehyde (44 +/- 4%), propionaldehyde (19 +/- 2%), and acetaldehyde (12 +/- 3%). In all cases, the product yields were independent of oxygen concentration over the partial pressure range of 10-600 Torr. The yields of propionaldehyde, acetaldehyde, and formaldehyde quoted above were not corrected for secondary formation via oxidation of higher aldehydes and should be treated as upper limits. The reactions of Cl atoms and OH radicals with n-butanol proceed 38 +/- 2 and 44 +/- 4%, respectively, via attack on the alpha-position to give an alpha-hydroxy alkyl radical which reacts with O(2) to give butyraldehyde. The results are discussed with respect to the atmospheric chemistry of n-butanol. PMID:19462959

Hurley, M D; Wallington, T J; Laursen, L; Javadi, M S; Nielsen, O J; Yamanaka, T; Kawasaki, M

2009-06-25

129

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

130

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

NASA Technical Reports Server (NTRS)

There are numerous hydrothermal fields within the Great Basin of North America, some of which have been exploited for geothermal resources. With methane and other carbon-bearing compounds being observed, in some cases with high concentrations, however, their origins and formation conditions remain unknown. Thus, studying hydrothermal springs in this area provides us an opportunity to expand our knowledge of subsurface (bio)chemical processes that generate organic compounds in hydrothermal systems, and aid in future development and exploration of potential energy resources as well. While isotope measurement has long been used for recognition of their origins, there are several secondary processes that may generate variations in isotopic compositions: oxidation, re-equilibration of methane and other alkanes with CO2, mixing with compounds of other sources, etc. Therefore, in addition to isotopic analysis, other evidence, including water chemistry and rock compositions, are necessary to identify volatile compounds of different sources. Surprise Valley Hot Springs (SVHS, 41º32'N, 120º5'W), located in a typical basin and range province valley in northeastern California, is a terrestrial hydrothermal spring system of the Great Basin. Previous geophysical studies indicated the presence of clay-rich volcanic and sedimentary rocks of Tertiary age beneath the lava flows in late Tertiary and Quaternary. Water and gas samples were collected for a variety of chemical and isotope composition analyses, including in-situ pH, alkalinity, conductivity, oxidation reduction potential (ORP), major and trace elements, and C and H isotope measurements. Fluids issuing from SVHS can be classified as Na-(Cl)-SO4 type, with the major cation and anion being Na+ and SO4 2-, respectively. Thermodynamic calculation using ORP and major element data indicated that sulfate is the most dominant sulfur species, which is consistent with anion analysis results. Aquifer temperatures at depth estimated by both dissolved SiO2 and Na-K-Ca geothermometers are in the range of 125.0 to 135.4 oC, and higher than the values measured at orifices (77.3 to 90.0 oC). CO2 and homologs of straight chain alkanes (C1-C5) were identified in gas samples. Carbon isotope values of alkanes increase with carbon numbers. The 13C fractionation between CO2 and dissolved inorganic carbon suggests they are out of carbon isotope equilibrium. The hypothesis regarding the formation of carbon-bearing compounds in SVHS may involve two processes: 1) Under high heat flow conditions which are caused by regional faulting and crustal extension, original high molecular weight organic compounds (kerogens) in clay-rich rocks decomposed to generate methane and other alkane homologs. 2) The SVHS area is associated with outflow structures, and distant from the heat source. Anaerobic oxidation of methane (AOM) with sulfate at shallow depth (< 90 oC) is suggested as being responsible for the generation of CO2 in SVHS.

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

2013-01-01

131

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

132

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

NASA Astrophysics Data System (ADS)

There are numerous hydrothermal fields within the Great Basin of North America, some of which have been exploited for geothermal resources. With methane and other carbon-bearing compounds being observed, however, their origins and formation conditions remain unknown. Thus, studying hydrothermal springs in this area provides us an opportunity to understand subsurface (bio)chemical processes that generate organic compounds, and aid in future development and exploration of potential energy resources as well. While isotope measurement has long been used for identification of their origins, there are secondary processes that may generate variations in isotopic compositions: oxidation, re-equilibration of methane and other alkanes with CO2, mixing with compounds of other sources, etc. Therefore, in addition to isotopic analysis, other lines of evidence, including water chemistry and rock compositions, are necessary to identify origins of volatile compounds. Surprise Valley Hot Springs (SVHS, 41°32'N, 120°5'W), located in a typical basin and range province in northeastern California, is a terrestrial hydrothermal spring system of the Great Basin. Previous geophysical studies indicated the presence of clay-rich volcanic and sedimentary rocks of Tertiary age beneath the lava flows during late Tertiary and Quaternary. Water and gas samples were collected for a variety of chemical and isotope composition analyses, including in-situ pH, alkalinity, oxidation reduction potential (ORP), major and trace elements, and C and H isotope measurements. Fluids issuing from SVHS can be classified as Na-(Cl)-SO4 type, with the major cation and anion being Na+ and SO42-, respectively. Thermodynamic calculation using ORP and major element data indicated that sulfate is the most dominant sulfur species, which is consistent with anion analysis results. Aquifer temperatures at depth estimated by both dissolved SiO2 and Na-K-Ca geothermometers are in the range of 125.0 to 135.4 °C, and higher than the values measured at orifices (77.3 to 90.0 °C). CO2 and homologs of straight chain alkanes (C1-C5) were identified in gas samples. Carbon isotope values of alkanes increase with carbon numbers. The 13C fractionation between CO2 and dissolved inorganic carbon suggests they are out of carbon isotope equilibrium. The hypothesis regarding the formation of carbon-bearing compounds in SVHS may involve two processes: 1) Under high heat flow conditions caused by regional faulting and crustal extension, original high molecular weight organic compounds (kerogens) in clay-rich rocks decomposed to generate methane and other alkanes. 2) The SVHS area is associated with outflow structures, and distant from the heat source. Anaerobic oxidation of methane with sulfate at shallow depth (< 90 °C) is suggested as being responsible for the generation of CO2 in SVHS.

Fu, Q.; Socki, R.; Niles, P. B.; Romanek, C. S.; Datta, S.; Darnell, M.; Bissada, A. K.

2013-12-01

133

147Chemistry Chemistry (Chem)  

E-print Network

147Chemistry Chemistry (Chem) Bayly Foundation PROFESSORS FRANCE, PLEVA ASSOCIATE PROFESSORS ALty A student may complete only one of the majors listed in the Department of Chemistry. The major in chemistry leading to a Bachelor of Arts degree requires completion of 44 credits as follows: 1. Chemistry 111, 112

Dresden, Gregory

134

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

135

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.

136

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

137

A complete basis set model chemistry. I. The total energies of closed-shell atoms and hydrides of the first-row elements  

NASA Astrophysics Data System (ADS)

The major source of errror in most ab initio calculations of molecular energies is the truncation of the one-electron basis set. A complete basis set model chemistry is defined to include corrections for basis set truncation errors. This model uses double zeta plus polarization level atomic pair natural orbital basis sets to calculate molecular self-consistent-field (SCF) energies and correlation energies. The small corrections to give the complete basis set SCF energies are then estimated using the l-6 asymptotic convergence of the multicenter angular momentum expansion. The calculated correlation energies of the atoms He, Be, and Ne, and of the hydrides LiH, BH3, CH4, NH3, H2O, and HF, using the double zeta plus polarization basis sets vary from 83.0% to 91.2% of the experimental correlation energies. However, extrapolation of each of the pair energies and pair-coupling terms to the complete basis set values using the asymptotic convergence of pair natural orbital expansions retrieves from 99.5±0.7% to 101.1±0.6% of the experimental correlation energies for these atoms and molecules. With the exception of ammonia which gave 101.1%, the calculated correlation energies agree with the experimental values to within the error limits of the experiments for all these atoms and molecules with more than four electrons. The total extrapolated energies (ESCF+ECorrelation) are then in agreement with experiment to within ±0.0014 hartree (root mean square deviation) and represent the most accurate total energy calculations yet reported for the molecules. The largest discrepancies with experiment occur for methane, where we obtain ETotal =-40.5112 hartree compared to EExpt =-40.514±0.002 hartree, and ammonia, where we obtain ETotal =-56.5659 hartree compared to EExpt =-56.563±0.002 hartree.

Petersson, G. A.; Bennett, Andrew; Tensfeldt, Thomas G.; Al-Laham, Mohammad A.; Shirley, William A.; Mantzaris, John

1988-08-01

138

The Relationship Between Atomic and Oxide Ion Formation From Sputtered Particles During SIMS and The Chemistry of The Substrate Material. (Invited)  

NASA Astrophysics Data System (ADS)

It is well known that the chemical composition of a substance can influence the instrumental mass bias in secondary ion mass spectrometry (SIMS) [1][2] and the matrix chemistry influences relative sensitivity factors for many compounds [3][4]. When samples are smaller than the primary beam size, the chemistry of the substrate, and the matrix of the sample, influence the secondary ion yields. There are numerous applications where this can occur. Even the relative production of simple molecular species can be influenced by the substrate chemistry by preferential binding to the atoms from the region above the sample making the desired simple molecular ion less likely to occur. We have performed a study of the influence of substrate material on sensitivity factors. Substrates of C, Si, and Au, were used for measurements of Th, and U ions and their oxide and dioxide ions. Oxygen backfilling was also used for some measurements (see Figure 1). Correlations exist, in the case where oxygen backfilling was not used, with the dissociation energies of the substrate element oxides and the element oxide ions from the particles. This correlation can be observed in Figure 2. A complete set of data thus far collected will be presented. References [1] EH Hauri,, AM Shaw, JH Wang, JE Dixon, PL King, C Mandeville, “Chem. Geo.”, 235, (2006) pp. 352-365 [2] IC Lyon, JM Saxton, G Turner, R Hinton, “Rapid Comm. in Mass Spec.”, 8 (10), (1994), pp. 837-843 [3] RG Wilson, FA Stevie, and CW Magee Secondary-ion mass spec. Wiley-interscience, New York (1989). ISBN No.: 0 471 51945 6 [4] AJ Fahey, “Mass Spec. and Ion Proc.”, 176, (1998), pp. 63-76 Figure 1: Oxide signals with O-flooding on 3 different substrates. Figure 2: Oxide signals without O-flooding on 3 different substrates.

Fahey, A. J.; Zeissler, C.; Newbury, D.; Davis, J.; Lindstrom, R.

2010-12-01

139

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

140

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

141

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

Microsoft Academic Search

A study was conducted to determine the weldability of Inconel 718 shells. Two pieces of Inconel 718 were welded together with a Hastelloy B-2 filler. The Inconel surface condition was varied by heat-treating and by using several different cleaning processes. The surface chemistry following each modification was determined by Auger spectroscopy. Each conditioned Inconel hollow cylinder (shell) was also checked

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

1987-01-01

142

Oxygen-Atom Transfer Chemistry and Thermolytic Properties of a Di-tert-Butylphosphate-Ligated Mn4 O4 Cubane.  

PubMed

[Mn4 O4 {O2 P(OtBu)2 }6 ] (1), an Mn4 O4 cubane complex combining the structural inspiration of the photosystem II oxygen-evolving complex with thermolytic precursor ligands, was synthesized and fully characterized. Core oxygen atoms within complex 1 are transferred upon reaction with an oxygen-atom acceptor (PEt3 ), to give the butterfly complex [Mn4 O2 {O2 P(OtBu)2 }6 (OPEt3 )2 ]. The cubane structure is restored by reaction of the latter complex with the O-atom donor PhIO. Complex 1 was investigated as a precursor to inorganic Mn metaphosphate/pyrophosphate materials, which were studied by X-ray absorption spectroscopy to determine the fate of the Mn4 O4 unit. Under the conditions employed, thermolyses of 1 result in reduction of the manganese to Mn(II) species. Finally, the related butterfly complex [Mn4 O2 {O2 P(pin)}6 (bpy)2 ] (pin=pinacolate) is described. PMID:25676196

Van Allsburg, Kurt M; Anzenberg, Eitan; Drisdell, Walter S; Yano, Junko; Tilley, T Don

2015-03-16

143

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.

144

Flying Over Atoms  

NSDL National Science Digital Library

Flying Over Atoms provides tools for teaching about atoms and solid surfaces in an introductory chemistry course. Flying Over Atoms introduces and stimulates interest in atomic surfaces and current methods for imaging at the atomic scale. Flying over Atoms uses Scanning Tunneling Microscope (STM) data and the software program Vistapro, published by Rom Tech, Inc. (not provided) to allow students to create QuickTime movies of atomic landscapes.

145

Numerical Simulation of Delft-Jet-in-Hot-Coflow (DJHC) Flames Using the Eddy Dissipation Concept Model for Turbulence–Chemistry Interaction  

Microsoft Academic Search

In this paper, we report results of a numerical investigation of turbulent natural gas combustion for a jet in a coflow of\\u000a lean combustion products in the Delft-Jet-in-Hot-Coflow (DJHC) burner which emulates MILD (Moderate and Intense Low Oxygen\\u000a Dilution) combustion behavior. The focus is on assessing the performance of the Eddy Dissipation Concept (EDC) model in combination\\u000a with two-equation turbulence

Ashoke De; Ernst Oldenhof; Pratap Sathiah; Dirk Roekaerts

2011-01-01

146

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

Microsoft Academic Search

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

Luigi Calamari; Fabio Abeni; Ferdinando Calegari; Luigi Stefanini

2007-01-01

147

Phase equilibria in subseafloor hydrothermal systems: A review of the role of redox, temperature, pH and dissolved Cl on the chemistry of hot spring fluids at mid-ocean ridges  

NASA Astrophysics Data System (ADS)

Time series measurements of the chemistry of hot spring fluids at mid-ocean ridges (MOR) have revealed steady state concentrations of dissolved species that indicate solubility control by mineral phases in subseafloor reaction zones [Campbell et al., 1988a; Bowers et al., 1988; Butterfield et al. 1994]. That MOR hot spring fluids have relatively low measured pH values (3.1 to 3.9), and are variably depleted in Mg and SO4, while enriched in Ca, K, and Si [Von Damm, 1990] relative to seawater, is entirely consistent with heterogeneous equilibria involving feldspar, chlorite, epidote ± quartz and NaCl fluids at temperatures in the vicinity of 375-400°C [Seyfried et al., 1991]. The high concentrations of so-called "soluble" elements, such as Li, Rb, Cs, and B [Von Damm et al., 1985; Spivack and Edmond, 1987], however, require an abundance of fresh rock (basalt/diabase) relative to the mass of seawater (i.e., low fluid/rock ratio). That these elements also fall to reveal significant compositional changes in fluids from specific hot springs sampled several times over a six year period [Campbell et al., 1985a; Butterfield et al. 1994; Butterfield and Massoth 1994] indicates a non-static and expanding reaction zone caused by penetration of seawater into previously unaltered portions of a solidified magma chamber. Although most vent fluids reveal short term stability [Campbell et al. 1988a; Butterfield and Massoth 1994], this is not always the case, as evidenced by the temporal evolution of the composition of vent fluids at the North Cleft segment of the Juan de Fuca Ridge [Butterfield et al. 1991; Butterfield and Massoth, 1994], and at 9-10degN EPR [Von Damm et al. 1991].

Seyfried, W. E., Jr.; Ding, Kang

148

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.

149

Chemistry of americium  

Microsoft Academic Search

Essential features of the descriptive chemistry of americium are reviewed. Chapter titles are: discovery, atomic and nuclear properties, collateral reading, production and uses, chemistry in aqueous solution, metal, alloys, and compounds, and, recovery, separation, purification. Author and subject indexes are included. (JCB)

Schulz

1976-01-01

150

Presenting the Bohr Atom.  

ERIC Educational Resources Information Center

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

Haendler, Blanca L.

1982-01-01

151

Chemistry: Experiments, Demonstrations and Other Activities Suggested for Chemistry.  

ERIC Educational Resources Information Center

This publication is a handbook used in conjunction with the course of study in chemistry developed through the New York State Education Department and The University of the State of New York. It contains experiments, demonstrations, and other activities for a chemistry course. Areas covered include the science of chemistry, the atomic structure of…

New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.

152

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

SciTech Connect

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

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

2012-03-20

153

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

PubMed Central

Summary One key component in the assembly of nanoparticles is their precise positioning to enable the creation of new complex nano-objects. Controlling the nanoscale interactions is crucial for the prediction and understanding of the behaviour of nanoparticles (NPs) during their assembly. In the present work, we have manipulated bare and functionalized gold nanoparticles on flat and patterned silicon and silicon coated substrates with dynamic atomic force microscopy (AFM). Under ambient conditions, the particles adhere to silicon until a critical drive amplitude is reached by oscillations of the probing tip. Beyond that threshold, the particles start to follow different directions, depending on their geometry, size and adhesion to the substrate. Higher and respectively, lower mobility was observed when the gold particles were coated with methyl (–CH3) and hydroxyl (–OH) terminated thiol groups. This major result suggests that the adhesion of the particles to the substrate is strongly reduced by the presence of hydrophobic interfaces. The influence of critical parameters on the manipulation was investigated and discussed viz. the shape, size and grafting of the NPs, as well as the surface chemistry and the patterning of the substrate, and finally the operating conditions (temperature, humidity and scan velocity). Whereas the operating conditions and substrate structure are shown to have a strong effect on the mobility of the particles, we did not find any differences when manipulating ordered vs random distributed particles. PMID:21977418

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

2011-01-01

154

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

155

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

156

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

SciTech Connect

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

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

2006-03-03

157

Interstellar chemistry  

PubMed Central

In the past half century, radioastronomy has changed our perception and understanding of the universe. In this issue of PNAS, the molecular chemistry directly observed within the galaxy is discussed. For the most part, the description of the molecular transformations requires specific kinetic schemes rather than chemical thermodynamics. Ionization of the very abundant molecular hydrogen and atomic helium followed by their secondary reactions is discussed. The rich variety of organic species observed is a challenge for complete understanding. The role and nature of reactions involving grain surfaces as well as new spectroscopic observations of interstellar and circumstellar regions are topics presented in this special feature. PMID:16894148

Klemperer, William

2006-01-01

158

Hypercarbon chemistry  

SciTech Connect

This text points out the emerging significance of higher-valent carbon compounds. It describes the compounds of carbon with coordination numbers greater than four and explores the delocalized bonds of ..pi.. aromatic molecules as a basis for rational description of orbitals; localized multicentered orbitals; the interactions of metallic ions with other atoms and molecules; the skeletal electron counts as a guide for synthesis; and the isolobal concept. Illustrated are the ways in which these subjects bring together structure and reactivity in the great diversity of novel carbon chemistry and its relationship to that of boron, lithium, hydrogen, the metals, and others.

Olah, G.A.; Prakash, G.K.S.; Wade, K.; Field, I.D.; Williams, R.E.

1987-01-01

159

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.

2011-07-22

160

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

161

Computational chemistry  

NASA Technical Reports Server (NTRS)

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

Arnold, J. O.

1987-01-01

162

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

163

The Place of Macromolecules in Freshman Chemistry  

ERIC Educational Resources Information Center

Discusses the inclusion of knowledge on macromolecules into a freshman chemistry course which emphasizes topics in organic chemistry, polymer science and biochemistry, atoms, chemical thermodynamics, and inorganic chemistry. Indicates that the program is the only way to keep chemistry education up to date. (CC)

Wunderlich, Bernhard

1973-01-01

164

European TV Brings Chemistry into the Home  

ERIC Educational Resources Information Center

Describes television programs broadcast in the Netherlands and West Germany which explain what chemistry is all about. Both programs, planned under the direction of trained chemists, comprise 13 half-hour presentations and include segments on energy, polymers, chemical processes, the chemistry of life, atomic and molecular chemistry, and chemistry…

O'Sullivan, Dermot A.

1975-01-01

165

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

E-print Network

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

Thi, Wing-Fai; Kamp, Inga

2009-01-01

166

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

167

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.

168

Search for methylamine in high mass hot cores  

NASA Astrophysics Data System (ADS)

Aims: We aim to detect methylamine, CH3NH2, in a variety of hot cores and use it as a test for the importance of photon-induced chemistry in ice mantles and mobility of radicals. Specifically, CH3NH2 cannot be formed from atom addition to CO whereas other NH2-containing molecules such as formamide, NH2CHO, can. Methods: Submillimeter spectra of several massive hot core regions were taken with the James Clerk Maxwell Telescope (JCMT). Abundances are determined with the rotational diagram method where possible. Results: Methylamine is not detected, giving upper limit column densities between 1.9-6.4 × 1016 cm-2 for source sizes corresponding to the 100 K envelope radius. Combined with previously obtained JCMT data analysed in the same way, abundance ratios of CH3NH2, NH2CHO and CH3CN with respect to each other and to CH3OH are determined. These ratios are compared with Sagittarius B2 observations, where all species are detected, and to hot core models. Conclusions: The observed ratios suggest that both methylamine and formamide are overproduced by up to an order of magnitude in hot core models. Acetonitrile is however underproduced. The proposed chemical schemes leading to these molecules are discussed and reactions that need further laboratory studies are identified. The upper limits obtained in this paper can be used to guide future observations, especially with ALMA. Appendices are available in electronic form at http://www.aanda.org

Ligterink, N. F. W.; Tenenbaum, E. D.; van Dishoeck, E. F.

2015-04-01

169

The Relationship Between Atomic and Oxide Ion Formation From Sputtered Particles During SIMS and The Chemistry of The Substrate Material. (Invited)  

Microsoft Academic Search

It is well known that the chemical composition of a substance can influence the instrumental mass bias in secondary ion mass spectrometry (SIMS) [1][2] and the matrix chemistry influences relative sensitivity factors for many compounds [3][4]. When samples are smaller than the primary beam size, the chemistry of the substrate, and the matrix of the sample, influence the secondary ion

A. J. Fahey; C. Zeissler; D. Newbury; J. Davis; R. Lindstrom

2010-01-01

170

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

ERIC Educational Resources Information Center

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

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

2012-01-01

171

Chemistry and the Atomic Nucleus  

Microsoft Academic Search

An informal account is given of the development of the Berkeley school of science and radiochemistry, followed by a summary of the results of radiocarbon dating measurements in relation to archaeological problems. A few suggestions are made as to future potential uses of radioisotope techniques in science and in industry.

Willard F. Libby

1958-01-01

172

148 Chemistry/Chinese Chemistry 347 (3)--Advanced Organic Chemistry  

E-print Network

148 Chemistry/Chinese Chemistry 347 (3)--Advanced Organic Chemistry Prerequisite: Chemistry 242,syntheticmethodology,mod- ernsyntheticreactions,protectinggroups,naturalprod- uctssynthesis,andcombinatorialchemistry.France. Spring Chemistry 350 (3)--Advanced Inorganic Chemistry Prerequisites: Chemistry 250, 252, and 262. Anintro

Dresden, Gregory

173

Analytical Chemistry Springboard  

NSDL National Science Digital Library

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

1995-01-01

174

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."

175

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

176

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

177

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.

Oregon Museum of Science and Industry

1997-01-01

178

TCD-IISc Symposium "Chemistry & Chemical Biology"  

E-print Network

in cancer drug discovery and relevant biomechanical mechanisms. Thorfinnur Gunnlaugsson, Professor Connon, Professor of Synthetic Chemistry. Research interests include organocatalysis, the discovery. Valeria Nicolosi, ERC Research Professor. Research interest in the liquid-phase processing and atom-by-atom

O'Mahony, Donal E.

179

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

180

Chemistry 687: Statistical Mechanics and Chemistry Syllabus: Spring 2010  

E-print Network

Chemistry 687: Statistical Mechanics and Chemistry Syllabus: Spring 2010 Instructor: Prof. John D; occupation numbers; Fermi and Bose statistics B. Quantum Ideal gases C. Phonons in harmonic solid; Einstein and Debye models D. Free electron model for metals E. Classical limit F. Classical ideal gases of atoms

Weeks, John D.

181

Hot Air  

NSDL National Science Digital Library

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

2012-08-06

182

Pre-University Chemistry Course  

NSDL National Science Digital Library

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

1998-01-01

183

Chemistry-nuclear chemistry division. Progress report, October 1979-September 1980  

SciTech Connect

This report presents the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, element migration and fixation, inorganic chemistry, isotope separation and analysis, atomic and molecular collisions, molecular spectroscopy, muonic x rays, nuclear cosmochemistry, nuclear structure and reactions, radiochemical separations, theoretical chemistry, and unclassified weapons research.

Ryan, R.R. (comp.)

1981-05-01

184

Green Chemistry Educational Resources  

NSDL National Science Digital Library

Created by the American Chemical Society (ACS), this website offers a set of lesson plans, multimedia demonstrations, and lab exercises for educators interested in introducing their students to green chemistry. First-time visitors can scroll down to the "Activities and Experiments" area where they will find activities that include "Bleaching With Green Oxidation Chemistry" and â??Cleaning Up With Atom Economy," Moving on, visitors can also take advantage of the "Online Resources" area. Here they will find links to materials developed at the University of Oregon and the Green Chemistry Network. Finally, the site is rounded out by the "More Educational Resources" area, which includes links to National Chemistry Week and the ChemMatters magazine.

185

Search for methylamine in high mass hot cores  

E-print Network

We aim to detect methylamine, CH$_{3}$NH$_{2}$, in a variety of hot cores and use it as a test for the importance of photon-induced chemistry in ice mantles and mobility of radicals. Specifically, CH$_3$NH$_2$ cannot be formed from atom addition to CO whereas other NH$_2$-containing molecules such as formamide, NH$_2$CHO, can. Submillimeter spectra of several massive hot core regions were taken with the James Clerk Maxwell Telescope. Abundances are determined with the rotational diagram method where possible. Methylamine is not detected, giving upper limit column densities between 1.9 $-$ 6.4 $\\times$ 10$^{16}$ cm$^{-2}$ for source sizes corresponding to the 100 K envelope radius. Combined with previously obtained JCMT data analyzed in the same way, abundance ratios of CH$_{3}$NH$_{2}$, NH$_{2}$CHO and CH$_{3}$CN with respect to each other and to CH$_{3}$OH are determined. These ratios are compared with Sagittarius B2 observations, where all species are detected, and to hot core models. The observed ratios su...

Ligterink, N F W; van Dishoeck, E F

2015-01-01

186

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

187

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

188

Nanostructured thin layers of vanadium oxides doped with cobalt, prepared by pulsed laser ablation: chemistry, local atomic structure, morphology and magnetism  

Microsoft Academic Search

Cobalt-doped vanadium oxide thin layers prepared by pulsed laser ablation are investigated from the following points of view: (1) the chemical states by X-ray photoelectron spectroscopy (XPS), (2) the local atomic order by X-ray absorption fine structure at both vanadium and cobalt K-edges, (3) the morphology of the films by atomic force microscopy (AFM) and (4) the magnetic properties by

C. M. Teodorescu; G. Socol; C. Negrila; D. Luca; D. Macovei

2010-01-01

189

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.

190

Atomic Structure Timeline  

NSDL National Science Digital Library

Lee Buescher is a microbiology and chemistry instructor at Watertown High School in Watertown, WI. He maintains the Atomic Structure Timeline page. The timeline follows major discoveries and advancements throughout history related to atomic structure. From Democritus to Bohr to modern day scientists, the descriptions and links explain the individual and what they accomplished.

Buescher, Lee.

191

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.

192

When Atoms Want  

ERIC Educational Resources Information Center

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

Talanquer, Vicente

2013-01-01

193

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

194

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 ...

195

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

196

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

197

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

198

General aspects of research in inorganic and solid-state recoil chemistry—A critical survey  

NASA Astrophysics Data System (ADS)

Following a condensed review of the main features of hot-atom chemistry in inorganic solids a fictitious investigation is examined for some shortcomings which appear in the literature. Popper's basic concepts of scientific research are recommended to guide future work. Using Rössler's "ligand abstraction model" as an example, it has been shown that (1) new correlations may be found between experimental parameters even if very good correlations already exist; (2) existing experimental facts may not be sufficient to falsify one of the correlations; and (3) new experiments can be suggested, the results of which may make one of the models more probable than the other or even falsify of them.

Müller, Horst

199

Chemistry of Transactinides  

NASA Astrophysics Data System (ADS)

In this chapter, the chemical properties of the man-made transactinide elements rutherfordium, Rf (element 104), dubnium, Db (element 105), seaborgium, Sg (element 106), bohrium, Bh (element 107), hassium, Hs (element 108), and copernicium, Cn (element 112) are reviewed, and prospects for chemical characterizations of even heavier elements are discussed. The experimental methods to perform rapid chemical separations on the time scale of seconds are presented and comments are given on the special situation with the transactinides where chemistry has to be studied with single atoms. It follows a description of theoretical predictions and selected experimental results on the chemistry of elements 104 through 108, and element 112.

Kratz, J. V.

200

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.

201

Chemistry Open Textbook  

NSDL National Science Digital Library

This free chemistry textbook from Boundless Learning is based off openly available educational resources such as "government resources, open educational repositories, and other openly licensed websites." The textbook contains 25 chapters such as Introduction to Chemistry, Atoms, Molecules, and Ions, and Mass Relationships and Chemical Equations. The textbook can be browsed on this page or downloaded as a pdf. Students can register for a free Boundless account to access a search engine and other study tools to efficiently find specific topics and master the content.

202

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

203

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

204

The atomic structure and chemistry of Fe-rich steps on antiphase boundaries in Ti-doped Bi{sub 0.9}Nd{sub 0.15}FeO{sub 3}  

SciTech Connect

Stepped antiphase boundaries are frequently observed in Ti-doped Bi{sub 0.85}Nd{sub 0.15}FeO{sub 3}, related to the novel planar antiphase boundaries reported recently. The atomic structure and chemistry of these steps are determined by a combination of high angle annular dark field and bright field scanning transmission electron microscopy imaging, together with electron energy loss spectroscopy. The core of these steps is found to consist of 4 edge-sharing FeO{sub 6} octahedra. The structure is confirmed by image simulations using a frozen phonon multislice approach. The steps are also found to be negatively charged and, like the planar boundaries studied previously, result in polarisation of the surrounding perovskite matrix.

MacLaren, Ian, E-mail: ian.maclaren@glasgow.ac.uk; Craven, Alan J.; Schaffer, Bernhard [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); SuperSTEM Laboratory, SciTech Daresbury, Keckwick Lane, Warrington WA4 4AD (United Kingdom); Wang, LiQiu [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Ramasse, Quentin M. [SuperSTEM Laboratory, SciTech Daresbury, Keckwick Lane, Warrington WA4 4AD (United Kingdom); Kalantari, Kambiz; Reaney, Ian M. [Department of Materials Science and Engineering, University of Sheffield, Mappin St, Sheffield S1 3JD (United Kingdom)

2014-06-01

205

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.

Shodor Computational Science Institute

206

CHEMISTRY 320 PHYSICAL CHEMISTRY I  

E-print Network

CHEMISTRY 320 PHYSICAL CHEMISTRY I Fall 2009 9:00 am - 10:30 am, MW CNSB 211 INSTRUCTOR INFORMATION of the physical principles of chemistry. Goals/ Objectives: CHEM 320 presents chemical principles from a fundamental physical point of view. Topics covered include: properties of gases, thermodynamics (heat, work

Findley, Gary L.

207

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

208

ANIONIC EFFECTS IN HOT SURFACE COMBUSTIONS  

Microsoft Academic Search

Hot surface oxidations are commonly thought to involve initial free radical hydrogen atom abstraction. Our evidence implicates initial Lewis base deprotonation by O•- atomic oxygen radical anions to form negatively charged carbanions. Subsequent rate determining electron transfers generate free radicals which only then give rise to combustion. Correlations regarding ignition temperatures and hydrocarbon oxidation product identity are consistent with carbanionic

William Bannister; Alfred Donatelli; Francis Bonner; Fang Lai; Pradeep Kurup; James Egan; Edwin Jahngen; Shih-Kun Chiang; Sandip Sengupta; Ramaswamy Nagarajan; Nukul Euaphantasate; Virinder Parma; Mario Cazeca; Eric Chen; Antonio Morales

209

Matrix-Isolation Studies on the Radiation-Induced Chemistry in H2O/CO2 Systems: Reactions of Oxygen Atoms and Formation of HOCO Radical.  

PubMed

The radiation-induced transformations occurring upon X-ray irradiation of solid CO2/H2O/Ng systems (Ng = Ar, Kr, Xe) at 8-10 K and subsequent annealing up to 45 K were studied by Fourier transform infrared spectroscopy. The infrared (IR) spectra of deposited matrices revealed the presence of isolated monomers, dimers, and intermolecular H2O···CO2 complexes. Irradiation resulted in effective decomposition of matrix-isolated carbon dioxide and water yielding CO molecules and OH radicals, respectively. Annealing of the irradiated samples led to formation of O3, HO2, and a number of xenon hydrides of HXeY type (in the case of xenon matrices). The formation of these species was used for monitoring of the postirradiation thermally induced chemical reactions involving O and H atoms generated by radiolysis. It was shown that the radiolysis of CO2 in noble-gas matrices produced high yields of stabilized oxygen atoms. In all cases, the temperatures at which O atoms become mobile and react are lower than those of H atoms. Dynamics and reactivity of oxygen atoms was found to be independent of the precursor nature. In addition, the formation of HOCO radicals was observed in all the noble-gas matrices at remarkably low temperatures. The IR spectra of HOCO and DOCO were first characterized in krypton and xenon matrices. It was concluded that the formation of HOCO was mainly due to the radiation-induced evolution of the weakly bound H2O···CO2 complexes. This result indicates the significance of weak intermolecular interactions in the radiation-induced chemical processes in inert low-temperature media. PMID:25469518

Ryazantsev, Sergey V; Feldman, Vladimir I

2015-03-19

210

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

211

Organophosphorus chemistry  

E-print Network

2087 Organophosphorus chemistry Paul R. Hanson Editorial Open Access Address: Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045-7582, USA Email: Paul R. Hanson - phanson@ku.edu. Keywords: organophosphorus... Beilstein J. Org. Chem. 2014, 10, 2087–2088. doi:10.3762/bjoc.10.217 Received: 28 July 2014 Accepted: 06 August 2014 Published: 04 September 2014 This article is part of the Thematic Series "Organophosphorus chemistry" Guest Editor: P. R. Hanson © 2014...

Hanson, Paul R.

2014-09-04

212

Technetium chemistry  

SciTech Connect

Technetium chemistry is a young and developing field. Despite the limited knowledge of its chemistry, technetium is the workhorse for nuclear medicine. Technetium is also a significant environmental concern because it is formed as a byproduct of nuclear weapons production and fission-power generators. Development of new technetium radio-pharmaceuticals and effective environmental control depends strongly upon knowledge of basic technetium chemistry. The authors performed research into the basic coordination and organometallic chemistry of technetium and used this knowledge to address nuclear medicine and environmental applications. This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

Burns, C.; Bryan, J.; Cotton, F.; Ott, K.; Kubas, G.; Haefner, S. [Los Alamos National Lab., NM (United States); Barrera, J. [Dartmouth Coll., Hanover, NH (United States); Hall, K. [Univ. of Washington, Seattle, WA (United States); Burrell, A. [Massey Univ., Palmerston North (New Zealand)

1996-04-01

213

Crystal Chemistry  

NSDL National Science Digital Library

This resource is a lecture from Tulane University that explores atoms and how they interact with one another to determine the physical and structural properties of crystals. Topics include atoms, isotopes, the quantum mechanical view of the atom, the electronic structure of atoms, ions, electronegativity, and various types of bonds that bind the atoms together in a crystal structure. Tables and illustrations accompany the text.

Nelson, Stephen A.

214

Atmospheric chemistry of sulfuryl fluoride: reaction with OH radicals, Cl atoms and O3, atmospheric lifetime, IR spectrum, and global warming potential.  

PubMed

Sulfuryl fluoride (SO2F2) is a radiatively active industrial chemical released into the atmosphere in significant (ktonne/ year) quantities. The potential for SO2F2 to contribute to radiative forcing of climate change needs to be assessed. Long path length FTIR/smog chamber techniques were used to investigate the kinetics of the gas-phase reactions of Cl atoms, OH radicals, and O3 with SO2F2, in 700 Torr total pressure of air or N2 at 296 +/- 1 K. Upper limits of k(Cl + SO2F2) < 9 x 10(-19), k(OH + SO2F2) < 1.7 x 10(-14) and k(O3 + SO2F2) < 5.5 x 10(-24) cm3 molecule(-1) s(-1) were determined. Reaction with Cl atoms, OH radicals, or O3 does not provide an efficient removal mechanism for SO2F2. The infrared spectrum of SO2F2 is reported and a radiative efficiency of 0.196 W m(-2) ppbv(-1) was calculated. Historic production data estimates are presented which provide an upper limit for expected atmospheric concentrations. The radiative forcing of climate change associated with emissions of SO2F2 depends critically on the atmospheric lifetime of SO2F2. Further research is urgently needed to define the magnitude of potential nonatmospheric sinks. PMID:19320159

Andersen, M P Sulbaek; Blake, D R; Rowland, F S; Hurley, M D; Wallington, T J

2009-02-15

215

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

216

Hot Deformation Behavior of Incoloy 901 Through Hot Tensile Testing  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

217

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.

218

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

219

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 ...

220

Basic Chemistry for the Cement Industry.  

ERIC Educational Resources Information Center

This combined student workbook and instructor's guide contains nine units for inplant classes on basic chemistry for employees in the cement industry. The nine units cover the following topics: chemical basics; measurement; history of cement; atoms; bonding and chemical formulas; solids, liquids, and gases; chemistry of Portland cement…

Turner, Mason

221

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.

222

Circumstellar chemistry  

NASA Technical Reports Server (NTRS)

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

Glassgold, Alfred E.; Huggins, Patrick J.

1987-01-01

223

for Undergraduate CHEMISTRY MAJORS  

E-print Network

, Geochemistry, Hazardous Waste Management, Inorganic Chemistry, Materials Science, Medicinal Chemistry, OilHANDBOOK 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.

224

Atomic-scale measurement of structure and chemistry of a single-unit-cell layer of LaAlO3 embedded in SrTiO3.  

PubMed

A single layer of LaAlO3 with a nominal thickness of one unit cell, which is sandwiched between a SrTiO3 substrate and a SrTiO3 capping layer, is quantitatively investigated by high-resolution transmission electron microscopy. By the use of an aberration-corrected electron microscope and by employing sophisticated numerical image simulation procedures, significant progress is made in two aspects. First, the structural as well as the chemical features of the interface are determined simultaneously on an atomic scale from the same specimen area. Second, the evaluation of the structural and chemical data is carried out in a fully quantitative way on the basis of the absolute image contrast, which has not been achieved so far in materials science investigations using high-resolution electron microscopy. Considering the strong influence of even subtle structural details on the electronic properties of interfaces in oxide materials, a fully quantitative interface analysis, which makes positional data available with picometer precision together with the related chemical information, can contribute to a better understanding of the functionality of such interfaces. PMID:23452378

Jia, Chun-Lin; Barthel, Juri; Gunkel, Felix; Dittmann, Regina; Hoffmann-Eifert, Susanne; Houben, Lothar; Lentzen, Markus; Thust, Andreas

2013-04-01

225

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.

2011-05-20

226

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

227

Green Chemistry  

NSDL National Science Digital Library

Learn about a study in which participants discovered contaminants in their homes, and how green chemistry may provide alternatives to such everyday toxins, in this video adapted from Contaminated Without Consent.

WGBH Educational Foundation

2011-03-21

228

Chemistry Notes.  

ERIC Educational Resources Information Center

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

School Science Review, 1981

1981-01-01

229

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

Allan A. Gahr

2003-02-01

230

Chemistry Tutorials  

NSDL National Science Digital Library

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

231

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

ERIC Educational Resources Information Center

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

Buffaloe, Jacquelin F.

232

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

SciTech Connect

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

Ryan, R.R. (comp.)

1982-05-01

233

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

234

Have a Chemistry Field Day in Your Area.  

ERIC Educational Resources Information Center

Describes a full day of chemistry fun and competition for high school chemistry students. Notes teams have five students from each high school. Lists five competitive events for each team: titration, qualitative analysis, balancing equations, general chemistry quiz, and quantitative analysis with atomic absorption spectroscopy. (MVL)

Mattson, Bruce M.; And Others

1989-01-01

235

Chemistry makes graphene beyond graphene.  

PubMed

Although graphene is extremely inert in chemistry because of the giant delocalized ? electron system, various methods have been developed to achieve its efficient chemical modification. Covalent chemistry is effective to modulate the physical properties of graphene. By converting the sp(2) hybridized carbon atoms to sp(3) ones, new two-dimensional (2D) materials and 2D superlattices with fascinating features beyond mother graphene could be built from the graphene scaffold, greatly expanding the graphene family and its attraction. In this Perspective, the power of covalent chemistry is demonstrated from the viewpoint of tailoring graphene's energy band structure as well as creating new 2D materials and 2D superlattices. A specific focus is laid on the general consideration and understanding of covalent graphene chemistry toward electronic devices and material science. PMID:25126670

Liao, Lei; Peng, Hailin; Liu, Zhongfan

2014-09-01

236

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.

Shawn C. Sendlinger

237

Chemistry and evolution of Titan's atmosphere  

NASA Technical Reports Server (NTRS)

The chemistry and evolution of Titan's atmosphere are reviewed, in light of the scientific findings from the Voyager mission. It is argued that the present N2 atmosphere may be Titan's initial atmosphere, rather than one photochemically derived from an original NH3 atmosphere. The escape rate of hydrogen from Titan is controlled by photochemical production from hydrocarbons. CH4 is irreversibly converted to less hydrogen-rich hydrocarbons, which over geologic time accumulate on the surface to a layer thickness of about 0.5 km. Magnetospheric electrons interacting with Titan's exosphere may dissociate enough N2 into hot, escaping N atoms to remove about 0.2 of Titan's present atmosphere over geologic time. The energy dissipation of magnetospheric electrons exceeds solar EUV energy deposition in Titan's atmosphere by an order of magnitude, and is the principal driver of nitrogen photochemistry. The environmental conditions in Titan's upper atmosphere are favorable to building up complex molecules, particularly in the north polar cap region.

Strobel, D. F.

1982-01-01

238

Atoms in Astronomy.  

ERIC Educational Resources Information Center

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

Blanchard, Paul A.

239

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

240

Radiation Chemistry  

NASA Astrophysics Data System (ADS)

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

Wojnárovits, L.

241

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

242

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.

Jacqueline S. Miller

2007-02-01

243

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.

244

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

245

Atmospheric Pseudohalogen Chemistry  

NASA Technical Reports Server (NTRS)

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

Lary, David John

2004-01-01

246

Chemistry Experiments  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

247

Polymer Chemistry  

NASA Technical Reports Server (NTRS)

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

Williams, Martha; Roberson, Luke; Caraccio, Anne

2010-01-01

248

Tropospheric chemistry  

NASA Technical Reports Server (NTRS)

The chemistry of the background troposphere, the source region, and the transition regions are discussed. The troposphere is governed by heterogeneous chemistry far more so than the stratosphere. Heterogeneous processes of interest involve scavenging of trace gases by aerosols, cloud and precipitation elements leading to aqueous phase chemical reactions and to temporary and permanent removal of material from the gas phase. Dry deposition is a major removal process for ozone, as well as for other gases of importance in tropospheric photochemistry. These processes are also discussed.

Mohnen, V. A.; Chameides, W.; Demerjian, K. L.; Lenschow, D. H.; Logan, J. A.; Mcneal, R. J.; Penkett, S. A.; Platt, U.; Schurath, U.; Dias, P. D.

1985-01-01

249

Using Computational Chemistry Activities to Promote Learning and Retention in a Secondary School General Chemistry Setting  

ERIC Educational Resources Information Center

This article describes the results of using state-of-the-art, research-quality software as a learning tool in a general chemistry secondary school classroom setting. I present three activities designed to introduce fundamental chemical concepts regarding molecular shape and atomic orbitals to students with little background in chemistry, such as…

Ochterski, Joseph W.

2014-01-01

250

Complex Chemistry on Interstellar Grains  

NASA Astrophysics Data System (ADS)

Early interstellar chemical models considered complex molecule formation on grains [Allen & Robinson (1977)], but current models assume that simple molecules form on grains and subsequent gas phase ion-molecule reactions produce the more complex species [Ruffle & Herbst (2001), Charnley (2001)]. It has been shown, however, that gas phase ion-molecule reactions are insufficient for the production of such complex organic species as ethanol (CH3CH2OH) and methyl formate (CH3OCHO) [Horn et al. (2004)]. Organics such as acetaldehyde (CH3CHO), ethanol, methyl formate, acetic acid (CH3COOH), and glycolaldehyde (CH2OHCHO) have also been detected in high abundance in regions of grain mantle disruption or evaporation, indicating that these species are formed on grain surfaces [see Chengalur & Kanekar (2003), Bottinelli et al. (2004), Hollis et al. (2001)]. The mechanisms for complex molecule production on grains are clearly much more important, and much more complex, than has been recognized. Recent observational studies of these types of species have offered insight into the mechanisms for their possible grain surface synthesis. The relative hot core abundances of the 2C structural isomers methyl formate, acetic acid, and glycolaldehyde (52:2:1, respectively [Hollis et al. (2001)]) indicate that if they form on grains it is not from kinetically-controlled single-atom addition reactions. Likewise, the 3C aldose sugar, glyceraldehyde (CH2OHCHOHCHO), was not detected in Sgr B2(N-LMH) [Hollis et al. (2004)] while the 3C ketose sugar, dihydroxyacetone (CO(CH2OH)2) was detected in this source [Widicus Weaver & Blake (2005)]. Chemical pathways favoring the more stable carbonates over acids and aldehydes are required to explain these results. Interestingly, all of these species can be formed from reactions involving the abundant grain mantle constituents CO, HCOOH, and CH3OH and their radical precursors. A model has been developed to investigate this type of chemical network, and the preliminary results of this model will be presented. The reactions incorporated into this model include photolysis of grain surface species, radical-radical combination reactions between photolysis products, aldehyde proton abstraction reactions, and radical recombination reactions between the photolysis products and aldehyde radicals. H addition reactions dominate the grain surface chemistry at low temperature, forming simple species such as water, methanol, and formaldehyde. Photolysis of simple grain mantle constituents leads to the production of surface radicals that can efficiently compete with H addition reactions at warmer temperatures, and so periodic thermal processing of grain mantles will lead to the buildup of more complex species such as formic acid, methyl formate, formamide, acetaldehyde, and glycolaldehyde. Aldehyde proton abstraction reactions can efficiently compete with single-atom addition reactions at both low and high temperatures, and so the mobile radicals can then react with the resultant aldehyde radicals to form more complex species. Simpler species will be favored at low temperature, but these radicals may also be stored in the grain mantle at low temperature and undergo more complex reactions upon grain mantle heating in hot core regions.

Widicus Weaver, Susanna L.; Kelley, Matthew J.; Blake, Geoffrey A.

251

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

252

Chemistry Notes.  

ERIC Educational Resources Information Center

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

School Science Review, 1983

1983-01-01

253

Chemistry Notes.  

ERIC Educational Resources Information Center

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

School Science Review, 1983

1983-01-01

254

Chemistry Notes  

ERIC Educational Resources Information Center

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

School Science Review, 1976

1976-01-01

255

Chemistry Notes  

ERIC Educational Resources Information Center

Short articles on the kinetics of the hydrogen peroxide-iodide ion reaction, simulation of fluidization catalysis, the use of Newman projection diagrams to represent steric relationships in organic chemistry, the use of synthetic substrates for proteolytic enzyme reactions, and two simple clock reactions"--hydrolysis of halogenoalkanes and…

School Science Review, 1972

1972-01-01

256

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.

257

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.

Kevin Lehmann

258

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.

WGBH Educational Foundation

2010-02-12

259

Chemistry Notes  

ERIC Educational Resources Information Center

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

School Science Review, 1972

1972-01-01

260

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

261

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.

262

Chemistry Notes.  

ERIC Educational Resources Information Center

Presents procedures, experiments, demonstrations, teaching suggestions, and information on a variety of chemistry topics including, for example, inert gases, light-induced reactions, calculators, identification of substituted acetophenones, the elements, analysis of copper minerals, extraction of metallic strontium, equilibrium, halogens, and…

School Science Review, 1982

1982-01-01

263

Hydrocarbon chemistry  

SciTech Connect

The objective of this book is to provide a conprehensive up-to-date treatment of the field encompassing both basic chemistry and practical application. Topics include the following: basic information about hydrocarbons, their definitions, uses as energy sources, synthesis and conversion; hydrocarbon production from petroleum and natural gas and synthesis C1 sources; and various aspects of transformations of hydrocarbons.

Olah, G.A.; Molnar, A.

1995-08-01

264

Reinventing chemistry.  

PubMed

Chemistry is in a period of change, from an era focused on molecules and reactions, to one in which manipulations of systems of molecules and reactions will be essential parts of controlling larger systems. This Essay traces paths from the past to possible futures. PMID:25682927

Whitesides, George M

2015-03-01

265

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.

266

Chemistry in one dimension.  

PubMed

We report benchmark results for one-dimensional (1D) atomic and molecular systems interacting via the Coulomb operator |x|(-1). Using various wavefunction-type approaches, such as Hartree-Fock theory, second- and third-order Møller-Plesset perturbation theory and explicitly correlated calculations, we study the ground state of atoms with up to ten electrons as well as small diatomic and triatomic molecules containing up to two electrons. A detailed analysis of the 1D helium-like ions is given and the expression of the high-density correlation energy is reported. We report the total energies, ionization energies, electron affinities and other physical properties of the many-electron 1D atoms and, using these results, we construct the 1D analog of Mendeleev's periodic table. We find that the 1D periodic table contains only two groups: the alkali metals and the noble gases. We also calculate the dissociation curves of several 1D diatomics and study the chemical bond in H2(+), HeH(2+), He2(3+), H2, HeH(+) and He2(2+). We find that, unlike their 3D counterparts, 1D molecules are primarily bound by one-electron bonds. Finally, we study the chemistry of H3(+) and we discuss the stability of the 1D polymer resulting from an infinite chain of hydrogen atoms. PMID:25518906

Loos, Pierre-François; Ball, Caleb J; Gill, Peter M W

2015-02-01

267

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.

268

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.

269

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.

270

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

271

Hot oxygen corona of Mars  

SciTech Connect

Electron dissociative recombination of O2(+) ions in the Venus ionosphere, which may be an important source of suprathermal atomic oxygen, is presently considered as a factor in the Mars exosphere; due to the weaker surface gravitational attraction of Mars, a hot oxygen corona thus formed would be denser than that of Venus at altitudes greater than 2000 km despite Mars' lower ionospheric content. If such an extended oxygen corona does exist on Mars, its collisional interaction with Phobos would lead to the formation of an oxygen gas torus whose average number density is of the order of only 1-2/cu cm along the Phobos orbit. 51 references.

Ip, W.H.

1988-10-01

272

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

273

Hot Weather Tips  

MedlinePLUS

... Form - A A + A You are here Home HOT Weather Tips Printer-friendly version We all suffer in hot weather. However, for elderly and disabled people and ... stress and following these tips for dealing with hot weather. Wear cool clothing: See that the person ...

274

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.

2012-07-24

275

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 Liège (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

276

9-11 April 2008 Hot Roller Embossing for the Creation of  

E-print Network

operating temperature, gas permeability, structural strength, optical properties and chemical resistance when compared to silicon and glass. Recent advancement in polymer chemistry has produced some high temperatures and hasher chemical environment. Polymer replication techniques such as hot embossing, injection

Paris-Sud XI, Université de

277

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.

2011-01-01

278

Chemistry 106X -Spring 2011 General Chemistry  

E-print Network

Chemistry 106X - Spring 2011 General Chemistry Instructor: Christopher Iceman Class: MWF 1 and can be purchased in the UAF bookstore or elsewhere: · Chemistry and Chemical Reactivity 7th Ed for Chemistry and Chemical Reactivity 7th Ed. (1 or 2 semester) · TurningPoint Technologies ResponseCard RF

Wagner, Diane

279

Chemistry 675 (CHE 675) Advanced Organic Chemistry  

E-print Network

Chemistry 675 (CHE 675) Advanced Organic Chemistry Fall Semester 2011 Professor James Hougland675 is a graduate-level organic chemistry course that can be continued in the Spring semester as CHE685. These two courses focus on physical organic chemistry, which deals with the structure

Mather, Patrick T.

280

Chemistry 106X -Fall 2010 General Chemistry  

E-print Network

Chemistry 106X - Fall 2010 General Chemistry Instructor: Christopher Iceman Class: MWF 9 bookstore or elsewhere: · Chemistry and Chemical Reactivity 7th Ed. by Kotz, Treichel, and Townsend-0-495-38703-9 Electronic Book - ISBN 978-0-495-68043-7 · OWL pin number for Chemistry and Chemical Reactivity 7th Ed. (1

Wagner, Diane

281

Chemistry 411/611 Inorganic Chemistry (2010)  

E-print Network

1 Chemistry 411/611 Inorganic Chemistry (2010) Instructor: Assistant Professor Mathew M. Maye: M-W 4:00-5:00, and by appointment Credits: 3 Text: (Required) Shriver & Atkins, "Inorganic Chemistry. (Suggested for CHE611 Students pursuing Inorganic) Huheey, "Inorganic Chemistry: Principles of Structure

Mather, Patrick T.

282

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

283

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.

284

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

285

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

286

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.

287

Industrial Chemistry and School Chemistry: Making chemistry studies more relevant  

Microsoft Academic Search

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

Avi Hofstein; Miri Kesner

2006-01-01

288

Intermediate-energy nuclear chemistry workshop  

SciTech Connect

This report contains the proceedings of the LAMPF Intermediate-Energy Nuclear Chemistry Workshop held in Los Alamos, New Mexico, June 23-27, 1980. The first two days of the Workshop were devoted to invited review talks highlighting current experimental and theoretical research activities in intermediate-energy nuclear chemistry and physics. Working panels representing major topic areas carried out indepth appraisals of present research and formulated recommendations for future research directions. The major topic areas were Pion-Nucleus Reactions, Nucleon-Nucleus Reactions and Nuclei Far from Stability, Mesonic Atoms, Exotic Interactions, New Theoretical Approaches, and New Experimental Techniques and New Nuclear Chemistry Facilities.

Butler, G.W.; Giesler, G.C.; Liu, L.C.; Dropesky, B.J.; Knight, J.D.; Lucero, F.; Orth, C.J.

1981-05-01

289

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,

290

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.

291

Geochemistry of Champagne Hot Springs shallow hydrothermal vent field and associated sediments, Dominica, Lesser Antilles  

E-print Network

Geochemistry of Champagne Hot Springs shallow hydrothermal vent field and associated sediments and precipitate chemistry, as well as comparing the submarine vent chemistry with nearby on-land hydrothermal hydrothermal venting, located approximately 40 m to the north of CHS. This area consists of hydrothermally

Pichler, Thomas

292

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.

293

CHEMISTRY 450 Spring, 2009  

E-print Network

of Science Journals: D-G WEEK 4 (28 January): Green Chemistry Journals: H-N WEEK 5 (4 February): Green Chemistry Journals: O-Z WEEK 6 (11 February): Green Chemistry; Group Presentations (Life-cycle analysis

Stuart, Steven J.

294

HotBot  

NSDL National Science Digital Library

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

295

Effervescent atomization  

Microsoft Academic Search

Effervescent atomization is a method of twin-fluid atomization that involves bubbling a small amount of gas into the liquid before it is ejected from the atomizer. The technique of bubbling gas directly into the liquid stream inside the atomizer body is essentially different from other methods of twin-fluid atomization (either internal or external mixing) and leads to significant improvements in

S. D Sovani; P. E Sojka; A. H Lefebvre

2001-01-01

296

Stratospheric chemistry  

NASA Technical Reports Server (NTRS)

Recent improvements in the data base for the currently identified reactions describing the chemistry of the major families of trace gas species, HO(x), NO(x), ClO(x), and hydrocarbons are assessed. The important coupling reactions between the families are introduced progressively. Chemical aspects such as heterogeneous reactions and reactions of sodium species, the importance of which are not yet completely established, are discussed. Recent attempts to reconcile some of the more unexpected kinetic behavior which has emerged from the extensive experimental studies of key reactions with current reaction rate theory are also examined. The uncertainties in the current kinetic and photochemical data base is given. The prospects for improvement of data for known reactions of atmospheric importance as well as for the identification of gaps in the chemical description of the atmosphere.

Cox, R. A.; Demore, W. B.; Ferguson, E. E.; Lesclaux, R.; Ravishankara, A. R.; Sander, S. P.; Sze, N. D.; Zellner, R.

1985-01-01

297

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

298

Chemistry -Bachelor of Science (SCH) Chemistry: ACS Certified  

E-print Network

Chemistry Lab I AND 1 CH 4110 Pharmaceutical Chemistry I 3 CH 1153 University Chemistry I Recitation 1 CH 4120 Pharmaceutical Chemistry II 3 OR CH 4320 Inorganic Chemistry II 3 CH 1112 University ChemistryChemistry - Bachelor of Science (SCH) Chemistry: ACS Certified Total Credits Required: 128 Required

299

Reviews Book: Sustainable Energy—Without 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 Energy—Without 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

300

Laboratory studies into the cosmic origins of organic chemistry  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

301

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 with the relationship between electronic structure, chemical bonding, and atomic order. It also investigates ...

Sadoway, Donald

302

CHEMISTRY 3020-42232 PHYSICAL CHEMISTRY I  

E-print Network

CHEMISTRY 3020-42232 PHYSICAL CHEMISTRY I Fall 2011 8:00 am - 8:50 am, MWF CNSB 211 INSTRUCTOR interpretations of the physical principles of chemistry. Goals/ Objectives: CHEM 3020 presents chemical principles from a fundamental physical point of view. Topics covered include: properties of gases, thermodynamics

Findley, Gary L.

303

CHEMISTRY 3022-63067 PHYSICAL CHEMISTRY II  

E-print Network

CHEMISTRY 3022-63067 PHYSICAL CHEMISTRY II Spring 2014 8:00 am - 8:50 am, MWF CNSB 211 INSTRUCTOR interpretations of the physical principles of chemistry. Goals/ Objectives: CHEM 3022 presents chemical principles consequences. Topics covered include: properties of gases, thermodynamics (heat, work, internal energy

Findley, Gary L.

304

FACULTY POSITION IN INORGANIC CHEMISTRY Department of Chemistry  

E-print Network

FACULTY POSITION IN INORGANIC CHEMISTRY Department of Chemistry Syracuse University The Department of Chemistry at Syracuse University invites applications for a tenure track faculty position at the Assistant Professor level in inorganic chemistry with specialization in materials chemistry (broadly defined

Doyle, Robert

305

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.

Christopher Griffith

306

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

307

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

308

Microscale Effects from Global Hot Plasma Imagery  

NASA Technical Reports Server (NTRS)

We have used a three-dimensional model of recovery phase storm hot plasmas to explore the signatures of pitch angle distributions (PADS) in global fast atom imagery of the magnetosphere. The model computes mass, energy, and position-dependent PADs based on drift effects, charge exchange losses, and Coulomb drag. The hot plasma PAD strongly influences both the storm current system carried by the hot plasma and its time evolution. In turn, the PAD is strongly influenced by plasma waves through pitch angle diffusion, a microscale effect. We report the first simulated neutral atom images that account for anisotropic PADs within the hot plasma. They exhibit spatial distribution features that correspond directly to the PADs along the lines of sight. We investigate the use of image brightness distributions along tangent-shell field lines to infer equatorial PADS. In tangent-shell regions with minimal spatial gradients, reasonably accurate PADs are inferred from simulated images. They demonstrate the importance of modeling PADs for image inversion and show that comparisons of models with real storm plasma images will reveal the global effects of these microscale processes.

Moore, T. E.; Fok, M.-C.; Perez, J. D.; Keady, J. P.

1995-01-01

309

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.

310

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).

Oakland Discovery Centers

2012-01-01

311

Hot Spot at Yellowstone  

ERIC Educational Resources Information Center

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

Dress, Abby

2005-01-01

312

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

313

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

314

CH171 Fall 2009 CH171-Life Science Chemistry I  

E-print Network

CH171 Fall 2009 CH171-Life Science Chemistry I Fall 2009 Instructor: Dr. Rosemary White email Course Description:One-semester introduction to general chemistry including atomic structure, chemical bonds, stoichiometry, properties of gases, molecular interactions, solutions, chemical reactions, acids

315

Supramolecular Coordination Chemistry and Functional Microporous Molecular Materials  

E-print Network

is the chemistry of compounds formed via interactions between atoms. "Supramolecu- lar chemistry" is the analogous direction (for example, cis vs trans coordination of a reactive metal center), (c) molecular or ionic charge-order structure), or (d) the reversibility of supramolecular association (for example, to obtain thermodynamic

Dinolfo, Peter H.

316

Nuclear chemistry progress report  

SciTech Connect

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

Viola, V.E.; Kwiatkowski, K.

1993-08-01

317

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

318

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

319

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

320

Chem 792 Course announcement Chemistry 792  

E-print Network

Chem 792 Course announcement Chemistry 792 MOLECULAR COLLISION THEORY Spring 1999 COURSE ANNOUNCEMENT G.S. Ezra gse1@cornell.edu We describe the concepts and methods of molecular collision theory to the Theory of Atomic and Molec- ular Collisions (Wiley, 1989). G.S. Ezra 1 Cornell University #12;

321

Polyhedra in physics, chemistry and geometry  

E-print Network

In this article we review some problems in physics, chemistry and mathematics that lead naturally to a class of polyhedra which include the Platonic solids. Examples include the study of electrons on a sphere, cages of carbon atoms, central configurations of gravitating point particles, rare gas microclusters, soliton models of nuclei, magnetic monopole scattering and geometrical problems concerning point particles.

Michael Atiyah; Paul Sutcliffe

2003-03-31

322

ACS Green Chemistry Institute  

NSDL National Science Digital Library

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

323

Digital Resource Package for Teaching Atomic Structure  

NSDL National Science Digital Library

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

Laura Moin

324

Atomic Structure  

NSDL National Science Digital Library

In this activity students explore the structure and properties of atoms. They construct models of atoms with properties of particular mass and charge; create models of atoms with different stabilities by adding or subtracting neutrons, protons, and electrons to a model atom; and determine that the same element may have varying number of neutrons and these form isotopes.Students will be able to:

The Concord Consortium

2011-12-11

325

Atom Chips  

E-print Network

Atoms can be trapped and guided using nano-fabricated wires on surfaces, achieving the scales required by quantum information proposals. These Atom Chips form the basis for robust and widespread applications of cold atoms ranging from atom optics to fundamental questions in mesoscopic physics, and possibly quantum information systems.

Ron Folman; Peter Krüger; Donatella Cassettari; Björn Hessmo; Thomas Maier; Jörg Schmiedmayer

1999-12-23

326

Delights of Chemistry  

NSDL National Science Digital Library

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

327

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

328

Oxygen Chemistry in the Circumstellar Envelope of the Carbon-Rich Star IRC+10216  

E-print Network

In this paper we study the oxygen chemistry in the C-rich circumstellar shells of IRC+10216. The recent discoveries of oxygen bearing species (water, hydroxyl radical and formaldehyde) toward this source challenge our current understanding of the chemistry in C-rich circumstellar envelopes. The presence of icy comets surrounding the star or catalysis on iron grain surfaces have been invoked to explain the presence of such unexpected species. This detailed study aims at evaluating the chances of producing O-bearing species in the C-rich circumstellar envelope only by gas phase chemical reactions. For the inner hot envelope, it is shown that although most of the oxygen is locked in CO near the photosphere (as expected for a C/O ratio greater than 1), some stellar radii far away species such as H2O and CO2 have large abundances under the assumption of thermochemical equilibrium. It is also shown how non-LTE chemistry makes very difficult the CO-->H2O,CO2 transformation predicted in LTE. Concerning the chemistry in the outer and colder envelope, we show that formaldehyde can be formed through gas phase reactions. However, in order to form water vapor it is necessary to include a radiative association between atomic oxygen and molecular hydrogen with a quite high rate constant. The chemical models explain the presence of HCO+ and predict the existence of SO and H2CS (which has been detected in a 3 mm line survey to be published). We have modeled the line profiles of H2CO, H2O, HCO+, SO and H2CS using a non-local radiative transfer model and the abundance profiles predicted by our chemical model. The results have been compared to the observations and discussed.

Marcelino Agundez; Jose Cernicharo

2006-05-25

329

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."

330

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

331

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

332

Hot Springs Creek  

USGS Multimedia Gallery

USGS scientist Jennifer Lewicki measures the discharge along a tributary to Hot Springs Creek, Akutan Island, Alaska. Steam (upper left) rises from 3 high-temperature springs that discharge into the tributary....

333

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

334

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

335

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

336

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

337

Hot ammonia in Orion  

SciTech Connect

Ten inversion lines from nonmetastable rotational levels of NH/sub 3/ have been detected in the Kleinmann-Low (KL) nebula in Orion. Six of these lines were previoulsy undetected. The emission arises from levels which have energies up to 1150 K above the ground state, indicating that the NH/sub 3/ is immersed in a hot, dense medium. Three well-defined kinematical components within KL are evident in emission from NH/sub 3/ and other molecules. The emission from hot NH/sub 3/ is dominated by the component having V/sub LSR/=5.2 km s/sup -1/ and ..delta..V =10--12 km s/sup -1/. A non-LTE analysis of NH/sub 3/ emission from this ''hot core'' component reveals that the minimum particle density in this source is approx.5 x 10 cm/sup -3/, and that the kinetic temperature is > or approx. =220 K. The diameter of the hot core source is probably within a factor of 2 to 6'' (5 x 10/sup 16/ cm). The hot core is undoubtedly associated with one of the compact infrared sources in KL, and we suggest on the basis of position and velocity coincidences that it is IRc2. The hot core appears to contain about one Jeans mass at the inferred temperature and density. We therefore suggest that this object is a very young protostar which is still in the throes of its initial collapse.

Morris, M.; Palmer, P.; Zuckerman, B.

1980-04-01

338

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

339

Hot off the press.  

PubMed

A personal selection of 33 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as artesin A from Artemisia sieversiana. PMID:25733078

Hill, Robert A; Sutherland, Andrew

2015-03-25

340

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

341

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

342

Unsymmetrical hot electron heating in quasi-ballistic nanocontacts  

PubMed Central

Electrons are allowed to pass through a single atom connected to two electrodes without being scattered as the characteristic size is much smaller than the inelastic mean free path. In this quasi-ballistic regime, it is difficult to predict where and how power dissipation occurs in such current-carrying atomic system. Here, we report direct assessment of electrical heating in a metallic nanocontact. We find asymmetric electrical heating effects in the essentially symmetric single-atom contact. We simultaneously identified the voltage polarity independent onset of the local heating by conducting the inelastic noise spectroscopy. As a result, we revealed significant heat dissipation by hot electrons transmitting ballistically through the junction that creates a hot spot at the current downstream. This technique can be used as a platform for studying heat dissipation and transport in atomic/molecular systems. PMID:22355731

Tsutsui, Makusu; Kawai, Tomoji; Taniguchi, Masateru

2012-01-01

343

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

344

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 known binding energies of the neutral atom and the isoelectronic negative ion. This model correctly

Kais, Sabre

345

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.

WGBH Educational Foundation

2004-01-29

346

Chemistry for Potters.  

ERIC Educational Resources Information Center

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

Denio, Allen A.

1980-01-01

347

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

348

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

349

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

350

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

2009-04-09

351

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, Björn

2015-01-01

352

Computational chemistry research  

NASA Technical Reports Server (NTRS)

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

Levin, Eugene

1987-01-01

353

Cometary MHD and chemistry  

NASA Technical Reports Server (NTRS)

An MHD and chemical comet-coma model was developed, applying the computer program of Huebner (1985) for the detailed chemical evolution of a spherically expanding coma and the program of Schmidt and Wegman (1982) and Wegman (1987) for the MHD flow of plasma and magnetic field in a comet to the Giotto-mission data on the ion abundances measured by the HIS ion mass spectrometer. The physics and chemistry of the coma are modeled in great detail, including photoprocesses, gas-phase chemical kinetics, energy balance with a separate electron temperature, multifluid hydrodynamics with a transition to free molecular flow, fast-streaming atomic and molecular hydrogen, counter and cross streaming of the ionized species relative to the neutral species in the coma-solar wind interaction region with momentum exchange by elastic collisions, mass-loading through ion pick-up, and Lorentz forces of the advected magnetic field. The results, both inside and outside of the contact surface, are discussed and compared with the relevant HIS ion mass spectra.

Wegmann, R.; Schmidt, H. U.; Huebner, W. F.; Boice, D. C.

1987-01-01

354

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.

355

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

356

Chemistry -Bachelor of Science (SCH) Chemistry: ACS Certified  

E-print Network

of the following courses Course Credits CH 1110 University Chemistry I 4 Course Credits AND CH 4110 Pharmaceutical Chemistry I 3 CH 1111 University Chemistry Lab I 1 CH 4120 Pharmaceutical Chemistry II 3 OR CH 4320Chemistry - Bachelor of Science (SCH) Chemistry: ACS Certified Total Credits Required: 128 Required

357

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

358

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

359

Mechanisms in Photographic Chemistry  

ERIC Educational Resources Information Center

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

Sahyun, M. R. V.

1974-01-01

360

Teaching School Chemistry.  

ERIC Educational Resources Information Center

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

Waddington, D. J., Ed.

361

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.

362

CHEMISTRY DEPARTMENT HANDBOOKFOR STUDENTS  

E-print Network

CHEMISTRY DEPARTMENT HANDBOOKFOR STUDENTS Millersville University Millersville, Pennsylvania in the ChemistryDepartment. It brings together material not collected in other places and is not meant Resources 2 Programs in Chemistry and The General Education Curriculum Record Form 3 The Major Requirements

Hardy, Christopher R.

363

History of Chemistry.  

ERIC Educational Resources Information Center

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

Servos, John W.

1985-01-01

364

Chemistry as General Education  

NASA Astrophysics Data System (ADS)

Science courses are common in most general education requirements. This paper addresses the role of chemistry classes in meeting these requirements. Chemistry professors have for many years questioned the appropriateness of the standard introductory chemistry course as general education, resulting in the growing popularity of specialized non-majors courses. I suggest that current non-major chemistry courses cover too much consumer chemistry and ignore some of the big contributions of chemistry to human knowledge. Majors chemistry courses, while they prepare students for majoring in science, do not address these issues either. Consequently, chemistry courses are often an ineffective and unpopular way to meet general education science requirements. Part of the reason for this dilemma is the lack of chemists who address the contributions of chemistry to human knowledge in general. I propose that faculty at liberal arts colleges engage in this important task and that non-majors chemistry textbooks incorporate questions and issues that relate chemistry to a broader view of human knowledge. If these things happen, perhaps chemistry courses will become more effective as general education.

Tro, Nivaldo J.

2004-01-01

365

Chemistry and Biochemistry Scholarships  

E-print Network

Chemistry and Biochemistry Scholarships Complete Scholarship Name Application Deadline Date Contact to Chemistry and Biochemistry entering graduate students who have asked for consideration to serve as research senior in the Department of Chemistry and Biochemistry based on faculty recommendation for undergraduate

Almor, Amit

366

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

367

IR Hot Wave  

SciTech Connect

The IR Hot Wave{trademark} furnace is a breakthrough heat treatment system for manufacturing metal components. Near-infrared (IR) radiant energy combines with IR convective heating for heat treating. Heat treatment is an essential process in the manufacture of most components. The controlled heating and cooling of a metal or metal alloy alters its physical, mechanical, and sometimes chemical properties without changing the object's shape. The IR Hot Wave{trademark} furnace offers the simplest, quickest, most efficient, and cost-effective heat treatment option for metals and metal alloys. Compared with other heat treatment alternatives, the IR Hot Wave{trademark} system: (1) is 3 to 15 times faster; (2) is 2 to 3 times more energy efficient; (3) is 20% to 50% more cost-effective; (4) has a {+-}1 C thermal profile compared to a {+-}10 C thermal profile for conventional gas furnaces; and (5) has a 25% to 50% smaller footprint.

Graham, T. B.

2010-04-01

368

Atom interferometers and atom holography  

SciTech Connect

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

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

1999-06-11

369

79Black Holes -Hot Stuff! Artist's impression of gas falling into a black hole  

E-print Network

79Black Holes - Hot Stuff! Artist's impression of gas falling into a black hole Image credit: NASA / Dana Berry, SkyWorks Digital When gas flows into a black hole, it gets very hot and emits light. The gas is heated because the atoms collide with each other as they fall into the black hole. Far away

370

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

371

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

372

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.

Boggan, William

373

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

374

Hot-Recycled-Solid pilot plant 1991 status report  

Microsoft Academic Search

At Lawrence Livermore National Laboratory, we are studying above ground oil shale retorting and have developed the LLNL Hot-Recycled-Solid (HRS) process as a generic second-generation, rapid pyrolysis retorting system in which recycled shale is the solid heat carrier. In 1984--1987, we operated a 1 tonne-per-day HRS pilot plant to study retorting chemistry in an actual recirculation loop. In 1989 we

1991-01-01

375

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.

Vision of Kamchatka

376

Editor's Note: Hot Properties  

NSDL National Science Digital Library

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

Chris Ohana

2008-01-01

377

HOT GAS CLEANUP PROCESS  

EPA Science Inventory

The report gives results of a study to identify and classify 22 hot gas cleanup (HGC) processes for desulfurizing reducing gases at above 430 C according to absorbent type into groups employing solid, molten salt, and molten metal absorbents. It describes each process in terms of...

378

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.

379

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

380

Hot Dry Rock - Summary  

Microsoft Academic Search

Hot Dry Rock adds a new flexibility to the utilization of geothermal energy. Almost always the approach has been to limit that utilization to places where there is a natural source of water associated with a source of heat. Actually, the result was that steam was mined. Clearly there are much larger heat resources available which lack natural water to

Tennyson; George P. Jr

1992-01-01

381

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

382

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.

Henry Bortman

383

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

384

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 ...

385

Exercising Safely in Hot Weather  

MedlinePLUS

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

386

Simulations of Autoignition and Laminar Premixed Flames in Methane/Air Mixtures Diluted with Hot Products  

E-print Network

context. De Joannon et al. [6] continued investigating diluted counterflow diffusion flames and commented on MILD chemistry, concluding that reactant dilution with an inert species slows down oxidative chemical kinetics and increases the distance... ) that at the exit the hot gases were virtually in chemical equilibrium at the adiabatic flame temperature. These are called ``hot products” in this paper. (Note that a chemical equilibrium solver could have been used for defining this state, but the differences...

Sidey, J.; Mastorakos, E.; Gordon, R. L.

2014-04-23

387

113. ARAI Hot cell (ARA626) Building wall sections and details ...  

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

113. ARA-I Hot cell (ARA-626) Building wall sections and details of radio chemistry lab. Shows high-bay roof over hot cells and isolation rooms below grade storage pit for fuel elements. Norman Engineering Company: 961-area/SF-626-A-4. Date: January 1959. Ineel index code no. 068-0626-00-613-102724. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

388

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

Microsoft Academic Search

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

Zhang Jingrong; Wang Wei; Yang Fan; Cai Tong

1993-01-01

389

Surface chemistry: a non-negligible parameter in determining optical properties of small colloidal metal nanoparticles  

Microsoft Academic Search

Surface chemistry can become pronounced in determining the optical properties of colloidal metal nanoparticles as the nanoparticles become so small (diameters <20 nm) that the surface atoms, which can undergo chemical interactions with the environment, represent a significant fraction of the total number of atoms although this effect is often ignored. For instance, formation of chemical bonds between surface atoms

Yugang Sun; Stephen K. Gray; Sheng Peng

2011-01-01

390

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

391

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

392

Green Systems Solar Hot Water  

E-print Network

Thermal Panels (Trex enclosure) Hot Water Storage Tank (TS-5; basement) Hot Water Heaters (HW-1Green Systems Solar Hot Water Heating the Building Co-generation: Heat Recovery System: Solar,2; basement) Pre-heats water so water heaters don't need to use as much energy Gas-powered, high efficiency

Schladow, S. Geoffrey

393

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

394

Probing the plasma chemistry in a microwave reactor used for diamond chemical vapor deposition by cavity ring down spectroscopy  

E-print Network

Probing the plasma chemistry in a microwave reactor used for diamond chemical vapor deposition a and CH radicals and H n=2 atoms have been measured in a diamond growing microwave reactor operating to thermal chemistry which drives the formation of ground state H atoms and the distributions of electron

Bristol, University of

395

Hot Tub Rash (Pseudomonas Dermatitis/Folliculitis)  

MedlinePLUS

... How Do I Protect Myself and My Family? "Hot Tub Rash" ( Pseudomonas Dermatitis / Folliculitis) Below are answers ... hot tub rash and healthy swimming. What is Hot Tub Rash? Hot tub rash, or dermatitis, is ...

396

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.

397

Atomic Mobile  

NSDL National Science Digital Library

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

American Museum of Natural History

2012-06-26

398

Atomic supersymmetry  

NASA Technical Reports Server (NTRS)

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

Kostelecky, V. Alan

1993-01-01

399

Hot chocolate effect  

SciTech Connect

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

Crawford, F.S.

1982-05-01

400

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 communities—their 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. PMID:25369743

López-López, Olalla; Cerdán, María Esperanza; González-Siso, María Isabel

2013-01-01

401

THE HOT CHOCOLATE EFFECT  

SciTech Connect

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

Crawford, Frank S.

1980-12-01

402

Session: Hot Dry Rock  

SciTech Connect

This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of four presentations: ''Hot Dry Rock - Summary'' by George P. Tennyson, Jr.; ''HDR Opportunities and Challenges Beyond the Long Term Flow Test'' by David V. Duchane; ''Start-Up Operations at the Fenton Hill HDR Pilot Plant'' by Raymond F. Ponden; and ''Update on the Long-Term Flow Testing Program'' by Donald W. Brown.

Tennyson, George P. Jr.; Duchane, David V.; Ponden, Raymond F.; Brown, Donald W.

1992-01-01

403

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.

Steven Shaw

2011-10-13

404

The ''hot'' patella  

SciTech Connect

Increased patellar uptake on bone scans is seen quite commonly but the possible or probable etiologies of this finding have not been previously well described. A review of 100 consecutive bone scans showed that the incidence of bilateral ''hot'' patellae is 15%. Identified etiologies include osteoarthritic degenerative disease (35%), fracture, possible metastatic disease, bursitis, Paget's disease, and osteomyelitis. The value of careful history, physical examination, and radiographs is stressed.

Kipper, M.S.; Alazraki, N.P.; Feiglin, D.H.

1982-01-01

405

HOT infrared photodetectors  

NASA Astrophysics Data System (ADS)

At present, uncooled thermal detector focal plane arrays are successfully used in staring thermal imagers. However, the performance of thermal detectors is modest, they suffer from slow response and they are not very useful in applications requiring multispectral detection. Infrared (IR) photon detectors are typically operated at cryogenic temperatures to decrease the noise of the detector arising from various mechanisms associated with the narrow band gap. There are considerable efforts to decrease system cost, size, weight, and power consumption to increase the operating temperature in so-called high-operating-temperature (HOT) detectors. Initial efforts were concentrated on photoconductors and photoelectromagnetic detectors. Next, several ways to achieve HOT detector operation have been elaborated including non-equilibrium detector design with Auger suppression and optical immersion. Recently, a new strategies used to achieve HOT detectors include barrier structures such as nBn, material improvement to lower generation-recombination leakage mechanisms, alternate materials such as superlattices and cascade infrared devices. Another method to reduce detector's dark current is reducing volume of detector material via a concept of photon trapping detector. In this paper, a number of concepts to improve performance of photon detectors operating at near room temperature are presented. Mostly three types of detector materials are considered — HgCdTe and InAsSb ternary alloys, and type-II InAs/GaSb superlattice. Recently, advanced heterojunction photovoltaic detectors have been developed. Novel HOT detector designs, so called interband cascade infrared detectors, have emerged as competitors of HgCdTe photodetectors.

Martyniuk, P.; Rogalski, A.

2013-06-01

406

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

407

Industrial Chemistry and School Chemistry: Making chemistry studies more relevant  

NASA Astrophysics Data System (ADS)

In this paper, we present the development and implementation over the period of more than 15 years of learning materials focusing on industrial chemistry as the main theme. The work was conducted in the Department of Science Teaching at the Weizmann Institute of Science, Israel. The project’s general goal was to teach chemistry concepts in the context of industrial chemistry in order to present chemistry as a relevant topic both to the students personally as well as to the society in which they live. The learning materials that were developed during this period were in alignment with the changes and reforms that were conducted in the Israeli educational system. These developments were accompanied with intensive and comprehensive professional development courses and workshops. In addition, several research and evaluation projects were conducted with the goal to assess students’ achievements and to probe into the students’ perceptions regarding the classroom learning environment and the teachers’ and students’ attitudes towards the various instructional and learning materials techniques that were implemented in the programme throughout these years. This paper is structured attempting to describe the curricular cycle in alignment with Goodlad’s and Van den Akker’s curriculum representations.

Hofstein, Avi; Kesner, Miri

2006-07-01

408

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

409

Chemflex Overview: Common Chemistry core  

E-print Network

393 3 Physical polymer science CHM 394 3 Organic polymer science BS Pharmaceutical Chemistry CourseChemflex Overview: Common Chemistry core CHM 40, 41 (or CHM 30, 31) 8 Introductory chemistry CHM 110,111,112,113 8 Organic chemistry CHM 332 3 Analytical chemistry CHM 201*** 2 Technical writing CHM

Napier, Terrence

410

atomic spectra 1 Atomic Spectra  

E-print Network

Physics, pp. 88-93 (Rutherford nuclear model), 93-106 (atomic structure and electron spectra) 2. D. Watomic spectra 1 Atomic Spectra '96, THK-MRM Object To become familiar with the construction and interpret spin-orbit doublets and triplets in alkali spectra. References 1. Serway, Moses and Moyer: Modern

Glashausser, Charles

411

PREFACE: Hot Quarks 2004  

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

412

Atmospheric chemistry of perfluorobutenes (CF 3CF dbnd CFCF 3 and CF 3CF 2CF dbnd CF 2): Kinetics and mechanisms of reactions with OH radicals and chlorine atoms, IR spectra, global warming potentials, and oxidation to perfluorocarboxylic acids  

NASA Astrophysics Data System (ADS)

Relative rate techniques were used to determine k(Cl + CF 3CF dbnd CFCF 3) = (7.27 ± 0.88) × 10 -12, k(Cl + CF 3CF 2CF dbnd CF 2) = (1.79 ± 0.41) × 10 -11, k(OH + CF 3CF dbnd CFCF 3) = (4.82 ± 1.15) × 10 -13, and k(OH + CF 3CF 2CF dbnd CF 2) = (1.94 ± 0.27) × 10 -12 cm 3 molecule -1 s -1 in 700 Torr of air or N 2 diluent at 296 K. The chlorine atom- and OH radical-initiated oxidation of CF 3CF dbnd CFCF 3 in 700 Torr of air gives CF 3C(O)F in molar yields of 196 ± 11 and 218 ± 20%, respectively. Chlorine atom-initiated oxidation of CF 3CF 2CF dbnd CF 2 gives molar yields of 97 ± 9% CF 3CF 2C(O)F and 97 ± 9% COF 2. OH radical-initiated oxidation of CF 3CF 2CF dbnd CF 2 gives molar yields of 110 ± 15% CF 3CF 2C(O)F and 99 ± 8% COF 2. The atmospheric fate of CF 3CF 2C(O)F and CF 3C(O)F is hydrolysis to give CF 3CF 2C(O)OH and CF 3C(O)OH. The atmospheric lifetimes of CF 3CF dbnd CFCF 3 and CF 3CF 2CF dbnd CF 2 are determined by reaction with OH radicals and are approximately 24 and 6 days, respectively. The contribution of CF 3CF dbnd CFCF 3 and CF 3CF 2CF dbnd CF 2 to radiative forcing of climate change will be negligible.

Young, Cora J.; Hurley, Michael D.; Wallington, Timothy J.; Mabury, Scott A.

413

Chemistry PowerPoint Lessons and Instructional Materials  

NSDL National Science Digital Library

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

414

Thomas-Fermi equation of state: The hot curve  

SciTech Connect

We derive the high-temperature limit of the equation of state based on the Thomas-Fermi statistical theory of the atom. The resulting ''hot curve'' is in fact the ideal Fermi gas. We expand the thermodynamic properties of this gas in powers of the fugacity and use this expansion to construct a representation of the pressure, accurate to about 0.1%. This representation is compared with the actual theory for aluminum and the ''hot curve'' is found to represent it well over a large region of interest in applications. 10 refs., 3 figs., 1 tab.

Baker, G.A. Jr.; Johnson, J.D.

1989-01-01

415

Combinatorial chemistry synthesis techniques  

Microsoft Academic Search

As pharmaceutical companies race to find new and novel drugs faster, the tools of combinatorial chemistry are increasingly playing a larger role. Chemists can now prepare hundreds or thousands of analogs simultaneously to reveal structure-activity relationships (SAR) all at once and potentially shorten the discovery process for new drugs by years. A wide variety of solid-phase organic chemistry techniques have

Michael L. Vazquez

1997-01-01

416

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

417

Chemistry 101 Spring, 2012  

E-print Network

Chemistry 101 Spring, 2012 Tentative Course Syllabus Millington 211; TR, 11-12:20 Instructor: S.K. Knudson; Office: Nope; Hours: by appt. email: skknud@wm.edu Text: Hill, McCreary, Kolb; Chemistry Shapes (4) 3 R, 2/16 The Mole and Reaction Stoichiometry (5) 3 T, 3/20 Gases and Gas Laws; Solids

Pike, Robert D.

418

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.

419

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.

420

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

421

Basic Chemistry Review  

NSDL National Science Digital Library

This assignment reviews basic of chemistry for students who should have had 2 introductory semesters of basic chemistry prior to enrolling in the Fundamental of Water Quality course for which the assignment is used. Assignment reviews basic equation balancing and questions about valence and concentration conversion that students will confront regularly in any geochemistry course.

Thomas Meixner

422

Chemistry in Microfluidic Channels  

ERIC Educational Resources Information Center

General chemistry introduces principles such as acid-base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of…

Chia, Matthew C.; Sweeney, Christina M.; Odom, Teri W.

2011-01-01

423

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

424

Reactive Chemistry Blog  

NSDL National Science Digital Library

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

425

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

426

Tropospheric Halogen Chemistry  

Microsoft Academic Search

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

R. von Glasow; P. J. Crutzen

2003-01-01

427

Chemistry and Biochemistry Scholarships  

E-print Network

Chemistry and Biochemistry Scholarships Complete Scholarship Name Application Deadline Date Contact Endowment Fund To provide support for undergraduate biomedical research in the Department of Chemistry/Biochemistry and biochemistry undergraduate majors. Deadline is based on University Awards Day deadline. Virginia Rogers 803

Almor, Amit

428

TU KAISERSLAUTERN DEPARTMENT OF CHEMISTRY  

E-print Network

.................................................................................................22 FOOD CHEMISTRY AND TOXICOLOGY: JUN.-Prof. Dr. M. Esselen...............................................................................24 FOOD CHEMISTRY AND TOXICOLOGY: Prof. Dr. E. Richling......................................................................................26 FOOD CHEMISTRY AND TOXICOLOGY: Prof. Dr. Dr. D. Schrenk

Madlener, Klaus

429

A Continuous Source of Bose-Einstein Condensed Atoms  

E-print Network

the ratio of the healing length to the condensate size. In our experiment, this energy was typically-perfect isolation of the hot at- oms from the cold, because a single laser- cooled atom has enough energy to knock of the two condensates, the excitation energy per atom is approximately equal to the chemical potential times

430

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

431

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

432

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 Millimétrique (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

433

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

434

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

435

Hot Springs, Virginia  

SciTech Connect

Three major springs are located in the Warm Springs Valley of the Allegheny Mountains in western Virginia along US route 220--the Warm, Hot and Healing--all now owned by Virginia Hot Springs, Inc. The Homestead, a large and historic luxurious resort, is located at Hot Springs. The odorless mineral water used at The Homestead spa flows from several springs at temperatures ranging from 39{degrees}C to 41{degrees}C (102{degrees} to 106{degrees}F) (Loam and Gersh, 1992). It is piped to individual, one-person bathtubs in separate men`s and women`s bathhouses, where is is mixed to provide an ideal temperature of 40{degrees}C (104{degrees}F). Tubs are drained and refilled after each use so that no chemical treatment is necessary. Mineral water from the same springs is used in an indoor swimming pool maintained at 29{degrees}C (84{degrees}F), and an outdoor swimming pool maintained at 22{degrees}C (72{degrees}F). Eight kilometers (5 miles) away to the northeast, but still within the 6,000-ha (15,000-acre) Homestead property, are the Warm Springs, which flow at 36{degrees}C (96{degrees}F). The rate of discharge is so great, 63 L/s (1000 gpm) (Muffler, 1979) that the two large Warm Springs pools, in separate men`s and women`s buildings, maintain the temperature on a flow-through basis requiring no chemical treatment. The men`s pool was designed by Thomas Jefferson and opened in 1761; the ladies` pool was opened in 1836. The adjacent {open_quotes}drinking spring{close_quotes} and the two covered pools have been preserved in their original condition.

Lund, J.W.

1996-05-01

436

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

437

The Hot Tub Mystery  

NSDL National Science Digital Library

Roma and Clint Underhill are relaxing after a stressful day in their hot tub with some wine. But tragedy strikes, and the next morning their lifeless bodies are found in the water by their housekeeper. The paramedics who respond to her frantic 911 call pronounce the couple dead at the scene and call in the police to investigate. Developed for use in a lower-level undergraduate course on human physiology, students work through the various parts of this interrupted case to discover the cause of death, and in the process learn about blood pressure regulation.

Herbert House

2005-01-01

438

Hot Off the Press  

NSDL National Science Digital Library

Environmental Health Perspectives (EHP) , a peer-reviewed environmental health research journal (published by the National Institute of Environmental Health Sciences, part of the National Institutes of Health,) provides the EHP Student Edition for high school and college teachers and their students. Each edition contains news articles that summarize a wide variety of scientific information and original research, which are paired with complementary lessons that introduce students to hot-off-the-press science. This article presents ways to integrate EHP's online content in the classroom.

Barry Schlegel

2006-10-01

439

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

440

Korean Kimchi Chemistry: A Multicultural Chemistry Connection  

ERIC Educational Resources Information Center

Connecting science with different cultures is one way to interest students in science, to relate science to their lives, and at the same time to broaden their horizons in a variety of ways. In the lesson described here, students make kimchi, a delicious and popular Korean dish that can be used to explore many important chemistry concepts,…

Murfin, Brian

2009-01-01

441

EVOLVING FROM GREEN CHEMISTRY TO SUSTAINABLE CHEMISTRY  

EPA Science Inventory

The twelve principles of green chemistry provide a foundation and pathway which allows researchers to incorporate greenness into existing reactions or when developing new technologies. Research from our laboratory has adopted many of these principles and utlizes them as a major c...

442

Mechanical gate control for atom-by-atom cluster assembly with scanning probe microscopy.  

PubMed

Nanoclusters supported on substrates are of great importance in physics and chemistry as well as in technical applications, such as single-electron transistors and nanocatalysts. The properties of nanoclusters differ significantly from those of either the constituent atoms or the bulk solid, and are highly sensitive to size and chemical composition. Here we propose a novel atom gating technique to assemble various atom clusters composed of a defined number of atoms at room temperature. The present gating operation is based on the transfer of single diffusing atoms among nanospaces governed by gates, which can be opened in response to the chemical interaction force with a scanning probe microscope tip. This method provides an alternative way to create pre-designed atom clusters with different chemical compositions and to evaluate their chemical stabilities, thus enabling investigation into the influence that a single dopant atom incorporated into the host clusters has on a given cluster stability. PMID:25014188

Sugimoto, Yoshiaki; Yurtsever, Ayhan; Hirayama, Naoki; Abe, Masayuki; Morita, Seizo

2014-01-01

443

Surface chemistry of LiNi0.5Mn1.5O4 particles coated by Al2O3 using atomic layer deposition for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

The effects of depositing ultrathin (<1 nm) Al2O3 coatings on LiNi0.5Mn1.5O4 (LNMO) particles using atomic layer deposition (ALD) are presented. Promising electrochemical performance of the Al2O3 ALD coated LNMO at 30 °C is demonstrated in not only significantly improved coulombic efficiency, cycle retention, and rate capability, but also in dramatically suppressed self-discharge and dissolution of transition metals. Combined analyses by electrochemical impedance spectroscopy, ex-situ X-ray photoelectron spectroscopy, and ex-situ time-of-flight secondary ion mass spectrometry reveal that the solid electrolyte interphase layer on the Al2O3 ALD coated LNMO is much thinner and contains fewer organic species than the one on the bare LNMO. This difference originates from the suppression of the side reaction at high voltage by the Al2O3 ALD protective coating. Also, fluorination of Al2O3 ALD layer upon repeated charge-discharge cycling is confirmed, and this can account for the capacity increases during the initial charge-discharge cycles. Finally, it is also demonstrated that a full LNMO/Li4Ti5O12 battery incorporating the Al2O3 ALD coated LNMO outperforms the one incorporating only bare LNMO.

Kim, Jin Wook; Kim, Dong Hyeon; Oh, Dae Yang; Lee, Hyeyoun; Kim, Ji Hyun; Lee, Jae Hyun; Jung, Yoon Seok

2015-01-01

444

Detailed computation of hot-plasma atomic spectra  

E-print Network

We present recent evolutions of the detailed opacity code SCO-RCG which combines statistical modelings of levels and lines with fine-structure calculations. The code now includes the Partially-Resolved-Transition-Array model, which allows one to replace a complex transition array by a small-scale detailed calculation preserving energy and variance of the genuine transition array and yielding improved high-order moments. An approximate method for studying the impact of strong magnetic field on opacity and emissivity was also recently implemented. The Zeeman line profile is modeled by fourth-order Gram-Charlier expansion series, which is a Gaussian multiplied by a linear combination of Hermite polynomials. Electron collisional line broadening is often modeled by a Lorentzian function and one has to calculate the convolution of a Lorentzian with Gram-Charlier distribution for a huge number of spectral lines. Since the numerical cost of the direct convolution would be prohibitive, we propose, in order to obtain t...

Pain, Jean-Christophe; Blenski, Thomas

2015-01-01

445

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

446

Atoms in astronomy  

NASA Technical Reports Server (NTRS)

Aspects of electromagnetic radiation and atomic physics needed for an understanding of astronomical applications are explored. Although intended primarily for teachers, this brochure is written so that it can be distributed to students if desired. The first section, Basic Topics, is suitable for a ninth-grade general science class; the style is simple and repetitive, and no mathematics or physics background is required. The second section, Intermediate and Advanced Topics, requires a knowledge of the material in the first section and assumes a generally higher level of achievement and motivation on the part of the student. These latter topics might fit well into junior-level physics, chemistry, or earth-science courses. Also included are a glossary, a list of references and teaching aids, class exercises, and a question and answer section.

Blanchard, P. A.

1976-01-01

447

Microfabricated plastic chips by hot embossing methods and their applications for DNA separation and detection  

Microsoft Academic Search

Design and fabrication of microfluidic devices on polymethylmethacrylate (PMMA) substrates for analytical chemistry and biomedical-related applications using novel microfabrication methods are described. The image of microstructures is transferred from quartz master templates possessing the inverse image of the devices to plastic plates by using hot embossing methods. The microchannels on quartz master templates are formed by the combination of metal

Gwo-Bin Lee; Shu-Hui Chen; Guan-Ruey Huang; Wang-Chou Sung; Yen-Heng Lin

2001-01-01

448

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

SciTech Connect

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

Inokuti, Mitio; Dehmer, P. M.; Pratt, S. T.; Poliakoff, E. D.; Dehmer, J. L.; Stockbauer, Roger; Dill, Dan; Parr, A. C.; Jackson, K. H.; Zare, R. N.; Person, J. C.; Nicole, P. P.; Fowler, D. E.; Codling, K.; West, J. B.; Ederer, D. L.; Cole, B. E.; Loomba, D.; Wallace, Scott; Swanson, J. R.; Poliakoff, E. D.; Spence, David; Chupka, W. A.; Stevens, C. M.; Shyn, W. T.; Sharp, W. E.; Kim, Y. K.; Eggarter, E.; Baer, T.; Hanson, J. D.; Shimamura, Isao; Dillon, Michael A.

1981-09-01

449

Radiations from hot nuclei  

NASA Technical Reports Server (NTRS)

The investigation indicates that nuclei with excitation energy of a few hundred MeV to BeV are more likely to radiate hot nuclear clusters than neutrons. These daughter clusters could, furthermore, de-excite emitting other hot nuclei, and the chain continues until these nuclei cool off sufficiently to evaporate primarily neutrons. A few GeV excited nuclei could radiate elementary particles preferentially over neutrons. Impact of space radiation with materials (for example, spacecraft) produces highly excited nuclei which cool down emitting electromagnetic and particle radiations. At a few MeV excitation energy, neutron emission becomes more dominant than gamma-ray emission and one often attributes the cooling to take place by successive neutron decay. However, a recent experiment studying the cooling process of 396 MeV excited Hg-190 casts some doubt on this thinking, and the purpose of this investigation is to explore the possibility of other types of nuclear emission which might out-compete with neutron evaporation.

Malik, F. Bary

1993-01-01

450

Hot air solar engine  

SciTech Connect

A hot air solar engine has two heat engines at opposing ends of a common piston assembly to provide alternate cooperative expansion and compression action. Each of the heat engines has a compressor and an expander wherein a single dual-diameter piston head serves as the piston portion of each. The hot air solar engine further includes a solar collector having positioning means for maintaining alignment with the sun's position. The solar collector has a paraboloid cylinder shaped reflector and a heat exchanger assembly disposed about the focal line of the reflector for receiving concentrated sunlight. The heat exchanger assembly includes first and second heat exchangers cooperating with the first and second heat engines. The heat exchangers are comprised of multiple parallel tubes each having a recuperator portion located within a recuperator chamber which receives heated air exhausted by the heat engines, and a collector portion located within a collector chamber equidistant from the focal line of the reflector which receives heat from the concentrated solar radiation. The recuperator chamber is contiguous to the collector chamber to increase solar efficiency, and the heat engines and heat exchanger assembly use environmental air as the working fluid allowing open system operation on an air-standard thermodynamic cycle. Fuel may be supplied to further heat the exhaust air through combustion as it is supplied to the recuperator chamber, thus permitting operation without sunlight.

Parry, J.F.W.

1983-11-15

451

Is It Time to Retire the Hybrid Atomic Orbital?  

ERIC Educational Resources Information Center

A rationale for the removal of the hybrid atomic orbital from the chemistry curriculum is examined. Although the hybrid atomic orbital model does not accurately predict spectroscopic energies, many chemical educators continue to use and teach the model despite the confusion it can cause for students. Three arguments for retaining the model in the…

Grushow, Alexander

2011-01-01

452

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

453

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

454

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

455

Atomic force microscopy and x-ray photoelectron spectroscopy investigations of the morphology and chemistry of a PdCl2/SnCl2 electroless plating catalysis system adsorbed onto shape memory alloy particles  

NASA Astrophysics Data System (ADS)

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 (SnO2 and PdO) and hydroxide [Sn(OH)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)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.

2004-11-01

456

Atmospheric chemistry of 4:2 fluorotelomer acrylate [C4F9CH2CH2OC(O)CH=CH2]: kinetics, mechanisms, and products of chlorine-atom- and OH-radical-initiated oxidation.  

PubMed

Relative rate techniques were used to measure the rate constants k[Cl + C(4)F(9)CH(2)CH(2)OC(O)CH=CH(2)] = (2.21 +/- 0.16) x 10(-10) and k[OH + C(4)F(9)CH(2)CH(2)OC(O)CH=CH(2)] = (1.13 +/- 0.12) x 10(-11) cm(3) molecule(-1) s(-1) in 700 Torr of N(2) or air diluent at 296 K. The atmospheric lifetime of C(4)F(9)CH(2)CH(2)OC(O)CHCH(2) (4:2 FTAc) is determined by its reaction with OH radicals and is approximately 1 day. The chlorine-atom-initiated oxidation of 4:2 FTAc in 700 Torr of air at 296 K gives C(4)F(9)CH(2)C(O)H in molar yields of 18% and 10% in the absence and presence of NO, respectively. The OH-radical-initiated oxidation of 4:2 FTAc in 700 Torr of air in the presence of NO gives HCHO in a molar yield of (102 +/- 7)%, with C(4)F(9)CH(2)CH(2)OC(O)C(O)H (4:2 fluorotelomer glyoxylate) as the expected coproduct. The atmospheric fate of the 4:2 fluorotelomer glyoxylate will be photolysis and reaction with OH radicals, which will lead to the formation of C(4)F(9)CH(2)C(O)H and ultimately perfluorinated carboxylic acids. The atmospheric oxidation of fluorotelomer acrylates is a potential source of perfluorinated carboxylic acids in remote locations. PMID:19275140

Butt, Craig M; Young, Cora J; Mabury, Scott A; Hurley, Michael D; Wallington, Timothy J

2009-04-01

457

Atmospheric chemistry of 4:2 fluorotelomer iodide (n-C4F9CH2CH2I): kinetics and products of photolysis and reaction with OH radicals and Cl atoms.  

PubMed

Relative rate techniques were used to study the title reactions and determine rate constants of k(Cl + C(4)F(9)CH(2)CH(2)I) = (1.25 +/- 0.15) x 10(-12) and k(OH + C(4)F(9)CH(2)CH(2)I) = (1.2 +/- 0.6) x 10(-12) cm(3) molecule(-1) s(-1) in 700 Torr total pressure at 295 K. The fluorotelomer aldehyde (C(4)F(9)CH(2)CHO), perfluorinated aldehyde (C(4)F(9)CHO), fluorotelomer acid (C(4)F(9)CH(2)C(O)OH), fluorotelomer peracid (C(4)F(9)CH(2)C(O)OOH), and several perfluorocarboxylic acids were detected by in situ FTIR spectroscopy and offline analysis as products of the chlorine atom initiated oxidation of C(4)F(9)CH(2)CH(2)I in air. The UV-visible spectra of C(4)F(9)CH(2)CH(2)I and C(2)H(5)Cl were recorded over the range of 200-400 nm. Photolysis of C(4)F(9)CH(2)CH(2)I gives C(4)F(9)CH(2)CHO as the major observed product. By assumption of a photolysis quantum yield of unity, it was calculated that the atmospheric lifetime of C(4)F(9)CH(2)CH(2)I is determined by photolysis and is a few days. A mechanism for the atmospheric oxidation of fluorotelomer iodides, (C(x)F(2x+1)CH(2)CH(2)I, where x = 2, 4, 6,...) is proposed. Atmospheric oxidation of fluorotelomer iodides is a potential source of perfluorocarboxylic acids. PMID:19053571

Young, Cora J; Hurley, Michael D; Wallington, Timothy J; Mabury, Scott A

2008-12-25

458

Preliminary geothermal investigations at Manley Hot Springs, Alaska  

NASA Astrophysics Data System (ADS)

Shallow, thermally disturbed ground at Manley Hot Springs constitutes an area of 1.2 km by 0.6 km along the lower slopes of Bean Ridge on the north side of the Tanana Valley. This area includes 32 springs and seeps and one warm (29.1 C) well. The hottest springs range in temperature from 61 to 47 C and are presently utilized for space heating and irrigation. The goal was to characterize the geothermal system present at Manley Hot Springs and delineate likely sites for geothermal drilling. Several surveys were conducted over a grid system which included shallow ground temperature, helium soil gas, mercury soil and resistivity surveys. In addition, a reconnaissance ground temperature survey and water chemistry sampling program was undertaken. The preliminary results, including some preliminary water chemistry, show that shallow hydrothermal activity can be delineated by many of the surveys. Three localities are targeted as likely geothermal well sites, and a model is proposed for the geothermal system at Manley Hot Springs.

East, J.; Wescott, E. M.; Turner, D. L.

1982-04-01

459

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

460

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

461

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

462

Web-Based Job Submission Interface for the GAMESS Computational Chemistry Program  

ERIC Educational Resources Information Center

A Web site is described that facilitates use of the free computational chemistry software: General Atomic and Molecular Electronic Structure System (GAMESS). Its goal is to provide an opportunity for undergraduate students to perform computational chemistry experiments without the need to purchase expensive software.

Perri, M. J.; Weber, S. H.

2014-01-01

463

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.

464

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

465

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

ERIC Educational Resources Information Center

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

Schlenker, Richard M.

466

Rydberg levels and ionization potential of francium measured by laser-resonance ionization in a hot cavity  

Microsoft Academic Search

A highly sensitive method of detecting atoms in samples has been used for spectral investigations of the rare radioactive element Fr. The method is based on laser-resonance photoionization of Fr atoms in a hot quasi-enclosed cavity. The investigations have been carried out with samples in which short-lived radioactive ²²¹Fr atoms formed at a rate of approximately 10³ atoms\\/sec. The data

S. V. Andreev; V. I. Mishin; V. S. Letokhov

1988-01-01

467

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 duel—a 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.

2014-09-18

468

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

469

Frontiers in analytical chemistry  

SciTech Connect

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

Amato, I.

1988-12-15

470

Linux4Chemistry  

NSDL National Science Digital Library

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

Kuznik, Nikodem.

471

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.

472

Computational quantum chemistry website  

SciTech Connect

This report contains the contents of a web page related to research on the development of quantum chemistry methods for computational thermochemistry and the application of quantum chemistry methods to problems in material chemistry and chemical sciences. Research programs highlighted include: Gaussian-2 theory; Density functional theory; Molecular sieve materials; Diamond thin-film growth from buckyball precursors; Electronic structure calculations on lithium polymer electrolytes; Long-distance electronic coupling in donor/acceptor molecules; and Computational studies of NOx reactions in radioactive waste storage.

none,

1997-08-22

473

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

474

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.

475

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

476

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

477

B.A. DEGREE REQUIREMENTS FOR CHEMISTRY (CHEMISTRY TRACK)  

E-print Network

.) At least 4 credits chosen from: CHE 411: Inorganic Chemistry (3) CHE 422: Inorganic Laboratory TechniquesB.A. DEGREE REQUIREMENTS FOR CHEMISTRY (CHEMISTRY TRACK) Requirements include 36 credits in chemistry core courses, 32 of which are taken in specific courses. Each student's course of study includes

Doyle, Robert

478

Faculty Position in Inorganic Chemistry Department of Chemistry  

E-print Network

Faculty Position in Inorganic Chemistry Department of Chemistry Purdue University The Department at the Assistant Professor level in inorganic chemistry. Successful candidates may have interests in any research area of inorganic chemistry, broadly defined. Purdue has a tradition of excellence in inorganic

Fernández-Juricic, Esteban

479

B.A. DEGREE REQUIREMENTS FOR CHEMISTRY (BIOLOGICAL CHEMISTRY TRACK)  

E-print Network

Chemistry (3) CHE 412: Metals in Medicine (3) CHE 422: Inorganic Laboratory Techniques (1) CHE 427B.A. DEGREE REQUIREMENTS FOR CHEMISTRY (BIOLOGICAL CHEMISTRY TRACK) Requirements include 21 credits from chemistry core courses, 6 credits from the list, (2) below, of approved biology/biochemistry core

Doyle, Robert

480

A Chemistry Minute: Recognizing Chemistry in Our Daily Lives  

ERIC Educational Resources Information Center

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

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

2008-01-01

481

Application of the principles of green chemistry in analytical chemistry  

Microsoft Academic Search

The introduction of the dimension of green chemistry into the assessment of ana- lytical methods should be a natural development trend in chemistry and should coincide with its general policy. Some of the principles of green chemistry—such as prevention of waste generation; safer solvents and auxiliaries; design for energy efficiency; safer chemistry to minimize the potential of chemical accidents; development

Mihkel Koel; Mihkel Kaljurand

2006-01-01

482

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.

2012-06-26

483

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

484

Silicon chemistry in interstellar clouds  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

485

Emergences of supramolecular chemistry: from supramolecular chemistry to supramolecular science  

Microsoft Academic Search

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

Jacques VicensQuentin Vicens; Quentin Vicens

486

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.

487

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.

488

Virtual Chemistry Experiments  

NSDL National Science Digital Library

Chemistry applets simulate various experiments, apparatus, and chemical processes. The display and operation of an applet can be controlled by the user through the PARAM options in the APPLET tag and through JavaScript commands.

David N. Blauch

489

Forensic Chemistry Lab Manual  

NSDL National Science Digital Library

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

Thompson, Robert

490

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.

491

Computer Individualizes Chemistry Course  

ERIC Educational Resources Information Center

A new teaching aid, designed to monitor each freshman chemistry student's progress, to identify specific weaknesses and strengths in his grasp of course material, and to prescribe individual study assignments, is described. (DT)

Chemical and Engineering News, 1974

1974-01-01

492

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

493

Discovery in chemistry  

SciTech Connect

The question, ''Where do axioms and postulates originate.'' is addressed. The article assumes that they are acquired by inductive logic and are new ideas or discoveries. How discoveries happen in chemistry is the topic of the talk.

Holley, C.E. Jr.

1982-12-01

494

STRATEGIESEMPLOYERS ANY CHEMISTRY DISCIPLINE  

E-print Network

departments Industries: Chemical, pharmaceutical, biotechnology, food, feed, cosmetics, agricultural Environment Agriculture Food Science Cosmetics Forensics ANALYTICAL CHEMISTRY Government agencies: U, biotechnology, food, feed, cosmetics, agricultural, environmental, petroleum, consumer products, legal, medical

New Hampshire, University of

495

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

B.J. Yoblinski

2003-03-01

496

Chemistry with a Peel.  

ERIC Educational Resources Information Center

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

Borer, Londa; Larsen, Eric

1997-01-01

497

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)