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1

Hot atom chemistry and radiopharmaceuticals  

SciTech Connect

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

Krohn, Kenneth A.; Moerlein, Stephen M.; Link, Jeanne M.; Welch, Michael J. [University of Washington, Department of Radiology, Molecular Imaging Center, 1959 NE Pacific St., Box 356004, Seattle, WA 98195-6004 (United States); Washington University, Department of Radiology, Division of Radiological Sciences, 510 South Kingshighway, St. Louis, MO 63110 (United States); University of Washington, Department of Radiology, Molecular Imaging Center, 1959 NE Pacific St., Box 356004, Seattle, WA 98195-6004 (United States); Washington University, Department of Radiology, Division of Radiological Sciences, 510 South Kingshighway, St. Louis, MO 63110 (United States)

2012-12-19

2

Hot atoms in cosmic chemistry.  

PubMed

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

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

1984-01-01

3

Hot atoms in cosmic chemistry  

NASA Astrophysics Data System (ADS)

High energy chemical reactions and atom molecule interactions might be important for cosmic chemistry with respect to the accelerated species in solar wind, cosmic rays, colliding gas and dust clouds and secondary knock-on particles in solids. ``Hot'' atoms with energies ranging from a few eV to some MeV can be generated via nuclear reactions and consequent recoil processes. The chemical fate of the radioactive atoms can be followed by radiochemical methods (radio GC or HPLC). Hot atom chemistry may serve for laboratory simulation of the reactions of energetic species with gaseous or solid interstellar matter. Due to the effective measurement of 108-1010 atoms only it covers a low to medium dose regime and may add to the studies of ion implantation which due to the optical methods applied are necessarily in the high dose regime. Experimental results are given for the systems: C/H2O (gas), C/H2O (solid, 77 K), N/CH4 (solid, 77K) and C/NH3 (solid, 77 K). Nuclear reactions used for the generation of 2 to 3 MeV atoms are: 14N(p, ?) 11C, 16O(p, ?pn) 11C and 12C(d,n) 13N with 8 to 45 MeV protons or deuterons from a cyclotron. Typical reactions products are: CO, CO2, CH4, CH2O, CH3OH, HCOOH, NH3, CH3NH2, cyanamide, formamidine, guanidine etc. Products of hot reactions in solids are more complex than in corresponding gaseous systems, which underlines the importance of solid state reactions for the build-up of precursors for biomolecules in space. As one of the major mechanisms for product formation, the simultaneous or fast consecutive reactions of a hot carbon with two target molecules (reaction complex) is discussed.

R鰏sler, K.; Jung, H.-J.; Nebeling, B.

4

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

5

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

SciTech Connect

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

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

1987-01-01

6

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

7

Hot and super-hot hydrogen atoms in microwave plasma  

SciTech Connect

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

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

2009-11-02

8

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

9

Radiation safety procedures for Atomics International Hot Laboratory  

Microsoft Academic Search

The radiation safety procedures for the safe operation of Atomics International Hot Laboratory are contained in this document. Specific operating procedures are included for normal operating and maintenance tasks.

H. E. Clow; W. F. Heine; W. R. McCurnin

1972-01-01

10

Fundamental Atomic Plasma Chemistry for Semiconductor Manufacturing Process Analysis  

Microsoft Academic Search

An absence of fundamental atomic plasma chemistry data (e.g. electron impact cross-sections) hinders the application of plasma process models in semiconductor manufacturing. Of particular importance is excited state plasma chemistry data for metallization applications. This paper describes important plasma chemistry processes in the context of high density plasmas for metallization application and methods for the calculation of data for the

P. L. G. Ventzek; V. Kudrya; V. Astapenko; A. Eletskii; D. Zhang; P. J. Stout; S. Rauf; M. Orlowski

2002-01-01

11

Atomic Absorption Spectrometry Perkin Elmer 500, Chemistry & Biochemistry  

E-print Network

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

Gruner, Daniel S.

12

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

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, Universit鋞 Kassel, Heinrich-Plett-Stra遝 40, 34132 Kassel (Germany)] [Theoretische Physik, Universit鋞 Kassel, Heinrich-Plett-Stra遝 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 癈 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 癈 in 1989 but had a maximum venting temperature of only 121 癈 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

Primordial chemistry and enzyme evolution in a hot environment.  

PubMed

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

Wolfenden, Richard

2014-08-01

17

Early chemistry in hot and dense nitromethane: Molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

We report density functional molecular dynamic simulations to determine the early chemical events of hot (T=3000 K) and dense (?=1.97 g/cm3, V/V0=0.68) nitromethane (CH3NO2). The first step in the decomposition process is an intermolecular proton abstraction mechanism that leads to the formation of CH3NO2H+ and the aci ion H2CNO2-. This event is also confirmed to occur in a fast annealing simulation to a final temperature of 4000 K at ?=2.20 g/cm3. An intramolecular hydrogen transfer that transforms nitromethane into the aci acid form, CH2NO2H, accompanies this event. To our knowledge, this is the first confirmation of chemical reactivity with bond selectivity for an energetic material near the Chapman-Jouget state of the fully reacted material. We also report the decomposition mechanism followed up to the formation of H2O as the first stable product. We note that similarities in the global features of reactants, intermediates, and products of the reacting fluid seem to indicate a threshold for similar chemistry in the range of high densities and temperatures reported herein.

Riad Manaa, M.; Reed, Evan J.; Fried, Laurence E.; Galli, Giulia; Gygi, Fran鏾is

2004-06-01

18

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

19

Students' use of atomic and molecular models in learning chemistry  

Microsoft Academic Search

The objective of this study was to investigate the development of introductory college chemistry students' use of atomic and molecular models to explain physical and chemical phenomena. The study was conducted during the first semester of the course at a University and College II. Public institution (Carnegie Commission of Higher Education, 1973). Students' use of models was observed during one-on-one

Eileen Ann O'Connor

1997-01-01

20

A collisional-radiative average atom model for hot plasmas  

SciTech Connect

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

Rozsnyai, B.F.

1996-10-17

21

Effects of surface chemistry on hot corrosion life  

NASA Technical Reports Server (NTRS)

Hot corrosion life prediction methodology based on a combination of laboratory test data and field service turbine components, which show evidence of hot corrosion, were examined. Components were evaluated by optical metallography, scanning electron microscopy (SEM), and electron micropulse (EMP) examination.

Fryxell, R. E.; Gupta, B. K.

1984-01-01

22

Effects of surface chemistry on hot corrosion life  

NASA Technical Reports Server (NTRS)

This program has its primary objective: the development of hot corrosion life prediction methodology based on a combination of laboratory test data and evaluation of field service turbine components which show evidence of hot corrosion. The laboratory program comprises burner rig testing by TRW. A summary of results is given for two series of burner rig tests. The life prediction methodology parameters to be appraised in a final campaign of burner rig tests are outlined.

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

1985-01-01

23

Effects of surface chemistry on hot corrosion life  

NASA Technical Reports Server (NTRS)

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

Fryxell, R. E.

1984-01-01

24

Analytical chemistry in a new analytical hot cell facility  

SciTech Connect

The Remote Analytical Laboratory is a new facility at the Idaho Chemical Processing Plant designed to handle samples from the processing of spent nuclear fuel. It consists of a cold laboratory for analyzing process make-up samples, a warm laboratory for analyzing low-level (<100 mR/h) radioactive samples, and a hot cell for analyzing high-level radioactive samples. The hot cell is built in an L shape and contains six work stations, each equipped with a viewing window and two master/slave manipulators. The cell interfaces with a waste handling cell and maintenance area on one end and a glove box complex that interfaces with the warm laboratory on the other end. This paper discusses the remote analytical techniques and equipment developed for use in this facility.

Wade, M.A.; Dykes, F.W.; Goettsche, J.H.; Lewis, A.L.; Lewis, P.C.; Marushia, P.C.; Murphy, J.A.; Reeder, S.D.; Trannell, D.R.; Trejo, L.E.

1985-11-01

25

Early chemistry in hot and dense nitromethane: Molecular dynamics simulations  

Microsoft Academic Search

We report density functional molecular dynamic simulations to determine the early chemical events of hot (T=3000 K) and dense (&rgr;=1.97 g\\/cm3, V\\/V0=0.68) nitromethane (CH3NO2). The first step in the decomposition process is an intermolecular proton abstraction mechanism that leads to the formation of CH3NO2H+ and the aci ion H2CNO2?. This event is also confirmed to occur in a fast annealing

M. Riad Manaa; Evan J. Reed; Laurence E. Fried; Giulia Galli

2004-01-01

26

Early chemistry in hot and dense nitromethane: Molecular dynamics simulations  

Microsoft Academic Search

We report density functional molecular dynamic simulations to determine the early chemical events of hot (T=3000 K) and dense (rho=1.97 g\\/cm3, V\\/V0=0.68) nitromethane (CH3NO2). The first step in the decomposition process is an intermolecular proton abstraction mechanism that leads to the formation of CH3NO2H+ and the aci ion H2CNO2-. This event is also confirmed to occur in a fast annealing

M. Riad Manaa; Evan J. Reed; Laurence E. Fried; Giulia Galli; Fran鏾is Gygi

2004-01-01

27

Origin of bond energy effects in hot atom chemistry  

Microsoft Academic Search

Six-particle T+CD trajectory studies show that bond energy ; effects on H abstraction, previously explored with a 3-particle LEPS potential, ; arise from correlation of barrier height with exoergicity. (AIP);

Sally Chapman; Trina Valencich; Don L. Bunker

1974-01-01

28

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

29

Organic Molecules in the Galactic Center. Hot Core Chemistry without Hot Cores  

E-print Network

We study the origin of large abundances of complex organic molecules in the Galactic center (GC). 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 CH3OH abundance between clouds varies by nearly two orders of magnitude from 2.4x10^{-8} to 1.1x10^{-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. 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. 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 (similar 10^{5}years) shocks with velocities >6km/s 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.

M. A. Requena-Torres; J. Mart韓-Pintado; A. Rodr韌uez-Franco; S. Mart韓; N. J. Rodr韌uez-Fern醤dez; P. de Vicente

2006-05-18

30

Organic Molecules in the Galactic Center. Hot Core Chemistry without Hot Cores  

E-print Network

To study the origin of the large abundances of complex organic molecules in the Galactic center (GC), we have 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 have derived the physical properties of GC molecular clouds and the abundances of the complex molecules.The CH3OH abundance between clouds varies by nearly two orders of magnitude from 2.4x10^{-8} to 1.1x10^{-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 of 4-8. 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. We find that both the abundance and the abundance ratios of the complex molecules relative to CH3OH in hot cores are similar to that found in the GC clouds. However, hot corin...

Requena-Torres, M A; Mart韓, S; Mart韓-Pintado, J; Rodr'iguez-Fern'andez, N J; Rodr韌uez-Franco, A

2006-01-01

31

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

32

Applications of atomic force microscopy in biophysical chemistry of cells.  

PubMed

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

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

2010-05-13

33

Hydrogen atom initiated chemistry. [chemical evolution in planetary atmospheres  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

34

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

35

Electronic Friction Dominates Hydrogen Hot-Atom Relaxation on Pd(100)  

NASA Astrophysics Data System (ADS)

We study the dynamics of transient hot H atoms on Pd(100) that originated from dissociative adsorption of H2. The methodology developed here, denoted AIMDEF, consists of ab initio molecular dynamics simulations that include a friction force to account for the energy transfer to the electronic system. We find that the excitation of electron-hole pairs is the main channel for energy dissipation, which happens at a rate that is five times faster than energy transfer into Pd lattice motion. Our results show that electronic excitations may constitute the dominant dissipation channel in the relaxation of hot atoms on surfaces.

Blanco-Rey, M.; Juaristi, J. I.; D韊z Mui駉, R.; Busnengo, H. F.; Kroes, G. J.; Alducin, M.

2014-03-01

36

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

Microsoft Academic Search

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

Gurmukh Singh; Amitabha Mukhopadyay

2010-01-01

37

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

38

Dry soldering with hot filament produced atomic hydrogen  

DOEpatents

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

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

1995-01-01

39

Dry soldering with hot filament produced atomic hydrogen  

DOEpatents

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

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

1995-04-25

40

Comparative Study on Hot Atom Coronae of Solar and Extrasolar Planets  

NASA Astrophysics Data System (ADS)

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

Shematovich, Valery

41

March 31, 2014 16:23 World Scientific Review Volume -9in x 6in BaudouinGuerinKaiser Cold and hot atomic vapors: a testbed for astrophysics?  

E-print Network

the atomic structure and to spectroscopy. It seems however that in the last decades, part of the atomic and hot atomic vapors: a testbed for astrophysics? Q. Baudouin, W. Guerin, and R. Kaiser Institut Non Lin Atomic physics experiments, based on hot vapors or laser-cooled atomic samples, may be useful to simulate

Paris-Sud XI, Universit茅 de

42

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 癈 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

43

Experimental Constraints on Hot Spring Fluid Chemistry in Back Arc Basins  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

44

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

45

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

46

Symmetry in chemistry from the hydrogen atom to?proteins  

PubMed Central

The last 2 decades have seen discoveries in highly excited states of atoms and molecules of phenomena that are qualitatively different from the 損lanetary 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 搈olecular behavior of a nonrigid linear structure undergoing collective rotation and vibration. Highly excited states of molecules described in the 搒tandard molecular model display normal mode couplings, which induce bifurcations on the route to molecular chaos. New approaches such as rigid杗onrigid correlation, vibrons, and quantum groups suggest a unified view of collective electronic motion in atoms and nuclear motion in molecules. PMID:8962040

Kellman, Michael?E.

1996-01-01

47

Hot Organic Molecules Toward a Young Low-Mass Star: A Look at Inner Disk Chemistry  

E-print Network

Spitzer Space Telescope spectra of the low mass young stellar object (YSO) IRS 46 (L_bol ~ 0.6 L_sun) in Ophiuchus reveal strong vibration-rotation absorption bands of gaseous C2H2, HCN, and CO2. This is the only source out of a sample of ~100 YSO's that shows these features and the first time they are seen in the spectrum of a solar-mass YSO. Analysis of the Spitzer data combined with Keck L- and M-band spectra gives excitation temperatures of > 350 K and abundances of 10(-6)-10(-5) with respect to H2, orders of magnitude higher than those found in cold clouds. In spite of this high abundance, the HCN J=4-3 line is barely detected with the James Clerk Maxwell Telescope, indicating a source diameter less than 13 AU. The (sub)millimeter continuum emission and the absence of scattered light in near-infrared images limits the mass and temperature of any remnant collapse envelope to less than 0.01 M_sun and 100 K, respectively. This excludes a hot-core type region as found in high-mass YSO's. The most plausible origin of this hot gas rich in organic molecules is in the inner (<6 AU radius) region of the disk around IRS 46, either the disk itself or a disk wind. A nearly edge-on 2-D disk model fits the spectral energy distribution (SED) and gives a column of dense warm gas along the line of sight that is consistent with the absorption data. These data illustrate the unique potential of high-resolution infrared spectroscopy to probe organic chemistry, gas temperatures and kinematics in the planet-forming zones close to a young star.

F. Lahuis; E. F. van Dishoeck; A. C. A. Boogert; K. M. Pontoppidan; G. A. Blake; C. P. Dullemond; N. J. Evans II; M. R. Hogerheijde; J. K. Joergensen; J. E. Kessler-Silacci; C. Knez

2005-11-29

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

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

50

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

51

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

52

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

53

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

54

Measurement of the Impact of Halogen Atom Chemistry on Volatile Organic Compounds in the Arctic  

NASA Astrophysics Data System (ADS)

It is well known that ozone and mercury depletion events occur in the Arctic during spring, around the time of polar sunrise. It has been suggested that halogen atoms, in particular bromine, play an important role in the onset of these depletion events, during which chlorine chemistry is also occurring. A variety of carbonyl compounds are produced when chlorine atoms react with VOCs, and destruction of aldehydes is seen as a result of bromine atom chemistry. Thus, these two halogen atoms impact the distribution of carbonyl compounds, and the ketone/aldehyde ratio is sensitive to the levels of chlorine and bromine that are present. During a field study in Barrow, Alaska, January - March of 2005, a variety of alkanes, ketones and aldehydes were measured using a preconcentrating autosampler-gas chromatograph-mass spectrometer from an inland site, and via Tenax-based sampling and GC-FID analysis in the vicinity of the Barrow lead. Additionally, ambient samples were collected in canisters and analyzed off-site, and the results from those canisters were used to evaluate the data collected with the instruments mentioned above. Here we discuss what can be learned about the sources and reactions of these compounds by examining the relationships between these species and ozone during a time period ranging from pre-polar sunrise, when ozone is not depleted, to post-polar sunrise, when substantial surface halogen chemistry is occurring.

Cavender, A.; Tackett, P.; Keil, A.; Shepson, P.; Young, V.

2005-12-01

55

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

56

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

57

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

SciTech Connect

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

Not Available

1993-08-01

58

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

PubMed Central

This paper describes measurements of the dynamics of hot electron cooling in photoexcited gold nanoparticles (Au NPs) with diameters of ?3.5 nm, and passivated with either a hexadecylamine or hexadecanethiolate adlayer, using ultrafast transient absorption spectroscopy. Fits of these dynamics with temperature-dependent Mie theory reveal that both the electronic heat capacity and the electron杙honon coupling constant are larger for the thiolated NPs than for the aminated NPs, by 40% and 30%, respectively. Density functional theory calculations on ligand-functionalized Au slabs show that the increase in these quantities is due to an increased electronic density of states near the Fermi level upon ligand exchange from amines to thiolates. The lifetime of hot electrons, which have thermalized from the initial plasmon excitation, increases with increasing electronic heat capacity, but decreases with increasing electron杙honon coupling, so the effects of changing surface chemistry on these two quantities partially cancel to yield a hot electron lifetime of thiolated NPs that is only 20% longer than that of aminated NPs. This analysis also reveals that incorporation of a temperature-dependent electron杙honon coupling constant is necessary to adequately fit the dynamics of electron cooling. PMID:23440215

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

2013-01-01

59

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梐n 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

60

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.

61

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

62

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

63

Interstellar sulfur chemistry  

NASA Technical Reports Server (NTRS)

The results of a chemical model of SO, CS, and OCS chemistry in dense clouds are summarized. The results are obtained from a theoretical study of sulfur chemistry in dense interstellar clouds using a large-scale time-dependent model of gas-phase chemistry. Among the results are the following: (1) owing to activation energy, the reaction of CS with O atoms is efficient as a loss mechanism of CS during the early phases of cloud evolution or in hot and oxygen-rich sources such as the KL nebula; (2) if sulfur is not abnormally depleted in dense clouds, then the observed abundances of SO, SO2, H2S, CS, OCS, H2CS, and SiS indicate that sulfur is mostly atomic in dense clouds; and (3) OCS is stable against reactions with neutral atoms and radicals in dense clouds.

Prasad, S. S.; Huntress, W. T., Jr.

1980-01-01

64

Building chemistry one atom at a time: An investigation of the effects of two curricula in students' understanding of covalent bonding and atomic size  

NASA Astrophysics Data System (ADS)

Chemists have to rely on models to aid in the explanation of phenomena they experience. Instruction of atomic theory has been used as the introduction and primary model for many concepts in chemistry. Therefore, it is important for students to have a robust understanding of the different atomic models, their relationships and their limitations. Previous research has shown that students have alternative conceptions concerning their interpretation of atomic models, but there is less exploration into how students apply their understanding of atomic structure to other chemical concepts. Therefore, this research concentrated on the development of three Model Eliciting Activities to investigate the most fundamental topic of the atom and how students applied their atomic model to covalent bonding and atomic size. Along with the investigation into students' use of their atomic models, a comparison was included between a traditional chemistry curriculum using an Atoms First approach and Chemistry, Life, the Universe and Everything (CLUE), a NSF-funded general chemistry curriculum. Treatment and Control groups were employed to determine the effectiveness of the curricula in conveying the relationship between atoms, covalent bonds and atomic size. The CLUE students developed a Cloud representation on the Atomic Model Eliciting Activity and maintained this depiction through the Covalent Bonding Model Eliciting Activity. The traditional students more often illustrated the atom using a Bohr representation and continued to apply the same model to their portrayal of covalent bonding. During the analysis of the Atomic Size Model Eliciting Activity, students had difficulty fully supporting their explanation of the atomic size trend. Utilizing the beSocratic platform, an activity was designed to aid students' construction of explanations using Toulmin's Argumentation Pattern. In order to study the effectiveness of the activity, the students were asked questions relating to a four-week long investigation into the identity of an inorganic salt during their laboratory class. Students who completed the activity exhibited an improvement in their explanation of the identity of their salt's cation. After completing the activity, another question was posed about the identity of their anion. Both groups saw a decrease in the percentage of students who included reasoning in their answer; however, the activity group maintained a significantly higher percentage of responses with a reasoning than the control group.

Bull, Barbara Jeanne

65

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

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

66

Study of gas-phase chemistry in a hot-wire chemical vapor deposition reactor with trimethylsilane and hexamethyldisilane  

NASA Astrophysics Data System (ADS)

Gas-phase chemistry involved in the decomposition of trimethylsilane and hexamethyldisilane (HMDS) on a hot tungsten filament and the secondary gas-phase reactions in a HWCVD reactor has been studied using vacuum ultraviolet laser single photon ionization in tandem with TOF-MS. On the hot W filament, trimethylsilane is decomposed into (CH3)2HSi and CH3 radicals and HMDS is decomposed into (CH3)5Si2, CH3, and (CH3)3Si radicals. Biradical combination reactions among primary radicals and those later formed are found to be the main gas-phase reaction pathways in the reactor for both precursors. Characteristic reactions of trimethylsilane are those with (CH3)2HSi and (CH3)2HSiCH2 radicals directly or indirectly involved, resulting in the formation of peaks at m/z = 88, 118, 132, 146, 116 and 130. With relatively heavier radicals generated from the decomposition of HMDS, the characteristic reactions for HMDS are believed to be those producing peaks in higher mass region, such as peaks at m/z = 204, 218, 262, 276, and 290.

Eustergerling, Brett; Li, Xinmao; Shi, Yujun

2007-06-01

67

Atomic force microscopy of hot spot reaction sites in impacted RDX and laser heated AP  

SciTech Connect

An atomic force microscope (AFM) has been used to reveal residual sub-micron sized decomposition sites in drop weight impacted RDX and laser irradiated AP crystals. In impacted RDX, the small and early reaction sites observed are hemispherical craters, ranging in size from 20--300 nm. The smallest reaction site encompassed about 10,000 molecules with an expected energy evolution of 2 {times} 10{sup {minus}14} J. On a somewhat larger scale hillocks of 200--800 nm were observed, their shape giving evidence of internal reaction and hot spot melting. Dislocation densities as high as 5 {times} 10{sup 12} per cm{sup 2} were observed in sub-ignited RDX. High resolution AFM images of the RDX lattice structure indicate molecular rotation as well as displacements at dislocation sites. In AP, after nanosecond pulsed laser irradiation, reaction sites were trumpet shaped with a smallest size of approximately 50 nm. Most sites contained a crystallographically oriented central square lid formed above the surrounding crystal surface, probably relating to the orthorhombic to cubic phase transition documented in micron scale cracking patterns observed at the laser heated sites.

Sharma, J.; Coffey, C.S. [Naval Surface Warfare Center, Silver Spring, MD (United States); Ramaswamy, A.L.; Armstrong, R.W. [Univ. of Maryland, College Park, MD (United States)

1996-07-01

68

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.

Gon鏰lves, Gil; Vila, Mercedes; Bdikin, Igor; de Andr閟, Alicia; Emami, Nazanin; Ferreira, Rute A. S.; Carlos, Lu韘 D.; Gr醕io, Jos; Marques, Paula A. A. P.

2014-10-01

69

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

PubMed

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

Gon鏰lves, Gil; Vila, Mercedes; Bdikin, Igor; de Andr閟, Alicia; Emami, Nazanin; Ferreira, Rute A S; Carlos, Lu韘 D; Gr醕io, Jos; Marques, Paula A A P

2014-01-01

70

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

Gon鏰lves, Gil; Vila, Mercedes; Bdikin, Igor; de Andr閟, Alicia; Emami, Nazanin; Ferreira, Rute A. S.; Carlos, Lu韘 D.; Gr醕io, Jos; Marques, Paula A. A. P.

2014-01-01

71

Peripheral heme substituents control the hydrogen-atom abstraction chemistry in cytochromes P450  

PubMed Central

We elucidate the hydroxylation of camphor by cytochrome P450 with the use of density functional and mixed quantum mechanics/molecular mechanics methods. Our results reveal that the enzyme catalyzes the hydrogen-atom abstraction step with a remarkably low free-energy barrier. This result provides a satisfactory explanation for the experimental failure to trap the proposed catalytically competent high-valent heme Fe(IV) oxo (oxyferryl) species responsible for this hydroxylation chemistry. The primary and previously unappreciated contribution to stabilization of the transition state is the interaction of positively charged residues in the active-site cavity with carboxylate groups on the heme periphery. A similar stabilization found in dioxygen binding to hemerythrin, albeit with reversed polarity, suggests that this mechanism for controlling the relative energetics of redox-active intermediates and transition states in metalloproteins may be widespread in nature. PMID:12771375

Guallar, Victor; Baik, Mu-Hyun; Lippard, Stephen J.; Friesner, Richard A.

2003-01-01

72

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

Microsoft Academic Search

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

H閘io Elael Bonini Viana; Paulo Alves Porto

2010-01-01

73

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

74

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

ERIC Educational Resources Information Center

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

Heinz, William F.; Hoh, Jan H.

2005-01-01

75

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

76

Hot Organic Molecules Toward a Young Low-Mass Star: A Look at Inner Disk Chemistry  

E-print Network

Spitzer Space Telescope spectra of the low mass young stellar object (YSO) IRS 46 (L_bol ~ 0.6 L_sun) in Ophiuchus reveal strong vibration-rotation absorption bands of gaseous C2H2, HCN, and CO2. This is the only source out of a sample of ~100 YSO's that shows these features and the first time they are seen in the spectrum of a solar-mass YSO. Analysis of the Spitzer data combined with Keck L- and M-band spectra gives excitation temperatures of > 350 K and abundances of 10(-6)-10(-5) with respect to H2, orders of magnitude higher than those found in cold clouds. In spite of this high abundance, the HCN J=4-3 line is barely detected with the James Clerk Maxwell Telescope, indicating a source diameter less than 13 AU. The (sub)millimeter continuum emission and the absence of scattered light in near-infrared images limits the mass and temperature of any remnant collapse envelope to less than 0.01 M_sun and 100 K, respectively. This excludes a hot-core type region as found in high-mass YSO's. The most plausible o...

Lahuis, F; Boogert, A C A; Dullemond, C P; Hogerheijde, M R; J鴕gensen, J K; Kessler-Silacci, J E; Knez, C; Pontoppidan, K M; Van Dishoeck, E F

2006-01-01

77

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

SciTech Connect

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

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

1984-08-01

78

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

79

Emanation of 54Mn and 57Co impurity hot atoms from metal iron upon annealing the radiation damage  

NASA Astrophysics Data System (ADS)

Irradiation of metallic iron with intense (10 ??) beams of deuterons (Ed - 9.0/8.2 MeV; fluence, 1.01022 m-2) is accompanied by the formation of a metastable ?-phase in the bulk of metal. Short annealing at low temperature (at (8735) K for 10 min) of irradiated samples leads to a degradation of the ?-phase of iron, to a reversion of the irradiated metal into the low-temperature state of ?-Fe, which is typical at room temperature, and is followed by a higher emanation of 54Mn atoms into the gaseous phase (almost by two orders of magnitude higher as compared to the vapor pressure values under this temperature). The results that are principally coincident with the ones given above (accelerated transport and subsequent excessive emanation of the hot atoms into the gaseous phase) have been obtained for 57Co as well.

Alekseev, I.

2015-01-01

80

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

81

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

82

Doing Chemistry  

NSDL National Science Digital Library

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

Brooks, David W.

2010-05-25

83

Experimental investigation of high-frequency-difference twin beams in hot cesium atoms  

NASA Astrophysics Data System (ADS)

We experimentally investigate the quantum-correlated twin beams generated through stimulated nondegenerate four-wave mixing in the double-lambda atomic system. A 2.5-dB noise reduction of intensity difference with 18.4-GHz frequency difference at the cesium D1 line is observed in a Cs vapor cell. The quantitative theoretical analysis reveals the experimental difficulty in getting high quantum correlation in Cs atoms because of the large hyperfine splitting of the ground states. However, it is favorable for obtaining quantum correlation in a wide range of pump detunings and relative long lengths of vapor cells. This quantum correlation provides a potential resource for possible coherent interfaces between atomic and solid-state systems due to its wavelength at the Cs D1 line which lies well within the wavelength regime of the exciton emission from InAs quantum dots.

Guo, Miaojun; Zhou, Haitao; Wang, Dan; Gao, Jiangrui; Zhang, Junxiang; Zhu, Shiyao

2014-03-01

84

Neutral atom analyzers for diagnosing hot plasmas: A review of research at the ioffe physicotechnical institute  

NASA Astrophysics Data System (ADS)

Research on neutral particle diagnostics of thermonuclear plasmas that has been carried out in recent years at the Ioffe Physicotechnical Institute of the Russian Academy of Sciences (St. Petersburg, Russia) is reviewed. Work on the creation and improvement of neutral atom analyzers was done in two directions: for potential applications (in particular, on the International Thermonuclear Experimental Reactor, which is now under construction at Cadarache in France) and for investigation of the ion plasma component in various devices (in particular, in the largest tokamaks, such as JET, TFTR, and JT-60). Neutral atom analyzers are the main tool for studying the behavior of hydrogen ions and isotopes in magnetic confinement systems. They make it possible to determine energy spectra, to perform the isotope analysis of atom fluxes from the plasma, to measure the absolute intensity of the fluxes, and to record how these parameters vary with time. A comparative description of the analyzers developed in recent years at the Ioffe Institute is given. These are ACORD-12/24 analyzers for recording 0.2-100-keV hydrogen and deuterium atoms with a tunable range of simultaneously measured energies, CNPA compact analyzers for a fixed energy gain in the ranges 80-1000 eV and 0.8-100 keV, an ISEP analyzer for simultaneously recording the atoms of all the three hydrogen isotopes (H, D, and T) in the energy range 5-700 keV, and GEMMA analyzers for recording atom fluxes of hydrogen and helium isotopes in the range 0.1-4 MeV. The scintillating detectors of the ISEP and GEMMA analyzers have a lowered sensitivity to neutrons and thus can operate without additional shielding in neutron fields of up to 109 n/(cm2 s). These two types of analyzers, intended to operate under deuterium-tritium plasma conditions, are prototypes of atom analyzers created at the Ioffe Institute for use in the International Thermonuclear Experimental Reactor. With these analyzers, a number of new results have been obtained in recent years in various devices. Some results are presented from investigation of ions in the Globus-M spherical tokamak, the W7-AS stellarator, and the JET tokamak by means of the analyzers developed at the Ioffe Institute. Challenges and opportunities for applying these diagnostics in the International Thermonuclear Experimental Reactor project are discussed.

Kislyakov, A. I.; Petrov, M. P.

2009-07-01

85

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

86

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

87

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

88

On the mechanism of H atom production in hot filament activated H2 and CH4/H2 gas mixtures.  

PubMed

This article reports systematic measurements of the power utilization by Ta (and Re) hot filaments (HFs) operating in a poor vacuum, in pure He, N(2), and H(2), and in CH(4)/H(2) gas mixtures of relevance to diamond growth by HF chemical vapor deposition, as functions of filament temperature T(fil) (in the range of 1800-2700 K) and gas pressure p (in the range of 10(-2)-100 Torr). In the cases of H(2) and the CH(4)/H(2) gas mixtures, the power consumption studies are complemented by in situ measurements of the relative H atom densities [H] near the HF--which are seen to maximize at p approximately 10-20 Torr and thereafter to remain constant or, at the highest T(fil), to decline at higher p. These (and many previous) findings are rationalized by a companion theoretical analysis, which reduces the complex array of chemisorption and desorption processes that must contribute to the HF-surface mediated dissociation of H(2) to a two-step mechanism involving H atom formation by dissociative adsorption at bare (S(*)) sites and by desorption at hydrogenated (SH) sites on the HF surface. PMID:19655886

Comerford, Dane W; Smith, James A; Ashfold, Michael N R; Mankelevich, Yuri A

2009-07-28

89

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

90

Chemistry of the outer planets  

NASA Technical Reports Server (NTRS)

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

Scattergood, Thomas W.

1992-01-01

91

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

92

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

93

Impact of Different Levels of Detail in Atomic Metal Plasma Chemistry on Multidimensional Plasma Equipment Models  

Microsoft Academic Search

The metric of goodness for a plasma chemistry model for a high-density metal plasma that one would use for metal deposition is how accurately it permits the flux of different charged and neutral species incident into a structure to be estimated for given process conditions. While electron impact cross-sections are not the only variables that impact this metric, they are

P. L. G. Ventzek; S. Rauf; V. Arunachalam; A. Eletskii; A. Astapenko; M. Golubkov; V. Golubkov; V. Kudrya

2000-01-01

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

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

NASA Technical Reports Server (NTRS)

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

Nickolaisen, Scott L.; Cartland, Harry E.

1993-01-01

96

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

97

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

SciTech Connect

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

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

1993-12-01

98

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

SciTech Connect

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

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

2006-07-01

99

CHEMISTRY CURRICULUM SEMESTER I  

E-print Network

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

Srinivasan, N.

100

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

NASA Astrophysics Data System (ADS)

The inclusion of the history of science in science curricula梐nd specially, in the curricula of science teachers梚s 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抯 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 搉ew historiography of science.

Viana, H閘io Elael Bonini; Porto, Paulo Alves

2010-01-01

101

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

102

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

103

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

104

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

PubMed

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

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

2014-01-01

105

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

PubMed Central

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

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

2014-01-01

106

KFC2: a knowledge-based hot spot prediction method based on interface solvation, atomic density, and plasticity features.  

PubMed

Hot spots constitute a small fraction of protein-protein interface residues, yet they account for a large fraction of the binding affinity. Based on our previous method (KFC), we present two new methods (KFC2a and KFC2b) that outperform other methods at hot spot prediction. A number of improvements were made in developing these new methods. First, we created a training data set that contained a similar number of hot spot and non-hot spot residues. In addition, we generated 47 different features, and different numbers of features were used to train the models to avoid over-fitting. Finally, two feature combinations were selected: One (used in KFC2a) is composed of eight features that are mainly related to solvent accessible surface area and local plasticity; the other (KFC2b) is composed of seven features, only two of which are identical to those used in KFC2a. The two models were built using support vector machines (SVM). The two KFC2 models were then tested on a mixed independent test set, and compared with other methods such as Robetta, FOLDEF, HotPoint, MINERVA, and KFC. KFC2a showed the highest predictive accuracy for hot spot residues (True Positive Rate: TPR = 0.85); however, the false positive rate was somewhat higher than for other models. KFC2b showed the best predictive accuracy for hot spot residues (True Positive Rate: TPR = 0.62) among all methods other than KFC2a, and the False Positive Rate (FPR = 0.15) was comparable with other highly predictive methods. PMID:21735484

Zhu, Xiaolei; Mitchell, Julie C

2011-09-01

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

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

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 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

110

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 癈. 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 癈). 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 癈 with a constant growth rate of 0.70 /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癈. 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 /cycle upon prime grade Si(100) was observed at substrate temperatures between 100 and 170 癈. 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 癈 ranged b

Knisley, Thomas Joseph

111

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

112

Theoretical Modeling of Interstellar Chemistry  

NASA Technical Reports Server (NTRS)

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

Charnley, Steven

2009-01-01

113

Hot Sauce Hot Spots  

NSDL National Science Digital Library

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

Muller, Eric

2007-01-01

114

Materials News: Interfacial chemistry and atomic arrangement of ZrO2 - La2/3Sr1/3MnO3 pillar-matrix structures  

NASA Astrophysics Data System (ADS)

We studied ZrO2 - La2/3Sr1/3MnO3 pillar-matrix thin films which were found to show anomalous magnetic and electron transport properties. With the application of an aberration-corrected transmission electron microscope, interfacial chemistry, and atomic-arrangement of the system, especially of the pillar-matrix interface were revealed at atomic resolution. Minor amounts of Zr were found to occupy Mn positions within the matrix. The Zr concentration reaches a minimum near the pillar-matrix interface accompanied by oxygen vacancies. La and Mn diffusion into the pillar was revealed at atomic resolution and a concomitant change of the Mn valence state was observed.

Zhou, Dan; Sigle, Wilfried; Okunishi, Eiji; Wang, Yi; Kelsch, Marion; Habermeier, Hanns-Ulrich; van Aken, Peter A.

2014-12-01

115

Chemistry Activities  

NSDL National Science Digital Library

This collection of resource features demonstrations, laboratory investigations, teaching tips, worksheets and other chemistry-related activities. Materials include investigations of mols, nuclear energy, the periodic table, weight and mass, elements, calculations, equations, pH, atomic weight, half-lives, and reactions.

116

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

SciTech Connect

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

Bench, T.R.

1997-05-01

117

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

118

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

119

Deposition of O atomic layers on Si(100) substrates for epitaxial Si-O superlattices: investigation of the surface chemistry  

NASA Astrophysics Data System (ADS)

Epitaxial Si-O superlattices consist of alternating periods of crystalline Si layers and atomic layers of oxygen (O) with interesting electronic and optical properties. To understand the fundamentals of Si epitaxy on O atomic layers, we investigate the O surface species that can allow epitaxial Si chemical vapor deposition using silane. The surface reaction of ozone on H-terminated Si(100) is used for the O deposition. The oxygen content is controlled precisely at and near the atomic layer level and has a critical impact on the subsequent Si deposition. There exists only a small window of O-contents, i.e. 0.7-0.9 atomic layers, for which the epitaxial deposition of Si can be realized. At these low O-contents, the O atoms are incorporated in the Si-Si dimers or back bonds (-OSiH), with the surface Si atoms mainly in the 1+ oxidation state, as indicated by infrared spectroscopy. This surface enables epitaxial seeding of Si. For O-contents higher than one atomic layer, the additional O atoms are incorporated in the Si-Si back bonds as well as in the Si-H bonds, where hydroxyl groups (-Si-OH) are created. In this case, the Si deposition thereon becomes completely amorphous.

Jayachandran, Suseendran; Delabie, Annelies; Billen, Arne; Dekkers, Harold; Douhard, Bastien; Conard, Thierry; Meersschaut, Johan; Caymax, Matty; Vandervorst, Wilfried; Heyns, Marc

2015-01-01

120

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

121

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

122

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

ERIC Educational Resources Information Center

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

Viana, Helio Elael Bonini; Porto, Paulo Alves

2010-01-01

123

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

124

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

125

Hot oxygen corona at Europa  

NASA Astrophysics Data System (ADS)

A model of the hot oxygen exosphere at Europa was constructed. The source term for the hot atoms was assumed to be dissociative recombination of O2+ and Liouville's theorem was used to calculate their altitude distribution. It was found that near the surface the hot oxygen density is in excess of 200 cm-3, dropping to a value on the order of 50 cm-3 at 1500 km. These calculations indicate that the hot atomic oxygen densities are considerably less than the thermal molecular oxygen ones, but slightly larger than the measured sodium values. The escape flux of the hot oxygen atoms was calculated to be on the order of 1.4108 atoms cm-2 sec-1. This corresponds to a global escape rate of 4.41025 atoms sec-1, which is more than an order of magnitude less than the estimated atmospheric sputtering rate.

Nagy, Andrew F.; Kim, Jhoon; Cravens, Thomas E.; Kliore, Arvydas J.

126

Kinetics of Fast Atoms in the Terrestrial Atmosphere  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

127

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

128

Roy L. Johnston School of Chemistry  

E-print Network

, dynamics, atomic segregation ... RLJ, Dalton Trans. 4193 (2003). Simulation of Plasmon Spectra) 颅 Drug Molecule-Enzyme Docking John Wilkie (Chemistry) Applications of Nature-Inspired Computation to Optimisation Problems in Chemistry John Wilkie (Chemistry) 路 Differential & Cultural Evolution (structure

Heinke, Dietmar

129

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.

130

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, 揅hem. Geo., 235, (2006) pp. 352-365 [2] IC Lyon, JM Saxton, G Turner, R Hinton, 揜apid 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, 揗ass 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

131

Chemistry 321 Organic Chemistry  

E-print Network

Chemistry 321 Organic Chemistry Fall 2010 MWF 1:00-2:00 Reichardt Bldg 202 Instructor: Thomas Dept.) Office Hours: By appointment Required Materials: Organic Chemistry 7th Ed., J. McMurry, Brooks of Organic Chemistry 7th Ed. by John McMurry. The course will focus on the bonding, stability, and shapes

Wagner, Diane

132

CHEMISTRY 11500 General Chemistry  

E-print Network

CHEMISTRY 11500 General Chemistry Spring 2014 Professor Dr. John J. Nash; BRWN 4103C; phone: 494.edu (Lab) Required Course Materials Chemistry: The Molecular Nature of Matter and Change, 6th Ed., by M. S. Silberberg, McGraw-Hill, 2012. Chemistry 11500 Laboratory Manual, 2013-2014, Hayden-McNeil Publishing, Inc

Jiang, Wen

133

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

134

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

135

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

136

Chemistry for Fuel Cells  

NSDL National Science Digital Library

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

2012-09-13

137

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.

138

Exotic Atoms and Muonium  

NASA Astrophysics Data System (ADS)

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

Horv醫h, D.

139

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

140

Nonaqueous sol-gel chemistry applied to atomic layer deposition: tuning of photonic band gap properties of silica opals.  

PubMed

Combining both electromagnetic simulations and experiments, it is shown that the photonic pseudo band gap (PPBG) exhibited by a silica opal can be fully controlled by Atomic Layer Deposition (ALD) of titania into the pores of the silica spheres constituting the opal. Different types of opals were assembled by the Langmuir-Blodgett technique: homogeneous closed packed structures set up of, respectively, 260 and 285 nm silica spheres, as well as opal heterostructures consisting of a monolayer of 430 nm silica spheres embedded within 10 layers of 280 nm silica spheres. For the stepwise infiltration of the opals with titania, titanium isopropoxide and acetic acid were used as metal and oxygen sources, in accordance with a recently published non-aqueous approach to ALD. A shift of the direct PPBG, its disappearance, and the subsequent appearance and shifting of the inverse PPBG are observed as the opal is progressively filled. The close agreement between simulated and experimental results is striking, and promising in terms of predicting the properties of advanced photonic materials. Moreover, this work demonstrates that the ALD process is rather robust and can be applied to the coating of complex nanostructures. PMID:20648325

Marichy, Catherine; Dech閦elles, Jean-Francois; Willinger, Marc-Georg; Pinna, Nicola; Ravaine, Serge; Vall閑, Renaud

2010-05-01

141

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.

Mark Bishop

142

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

143

HOT-ATOM CHEMISTRY OF ARSENATES--EFFECT OF CATION, WATER OF CRYSTALLIZATION AND IRRADIATION TEMPERATURE ON THE RETENTION OF RADIOARSENIC IN NEUTRON-IRRADIATED SOLID ARSENATES  

Microsoft Academic Search

The effects of variables on retention of arsenic(V) were studied in ; arsenates of Li, NH, Na, K, Co(II), and Ba, using thermalized neutrons. ; For Na釮AsO 7 H釵, storage at -72 and -196 deg C after ; irradiation had little effect on the retention, while storage at room temperature ; showed a graduai increase in the retention with time.

Nobufusa Saito; Isao Tomita

1962-01-01

144

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

145

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

146

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

147

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

148

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

149

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."

150

Hot and Cold  

NSDL National Science Digital Library

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

Industry, Oregon M.

1997-01-01

151

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

NASA Astrophysics Data System (ADS)

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

Lerchbacher, Christoph; Zinner, Silvia; Leitner, Harald

2012-12-01

152

Hot Air  

NSDL National Science Digital Library

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

Observatory, The U.

2011-01-01

153

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

SciTech Connect

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

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

2011-04-15

154

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

155

Educational Multiwavelength Atomic Emission Spectrometer  

E-print Network

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

Nazarenko, Alexander

156

Plasma processing and chemistry  

Microsoft Academic Search

The growing field of applications of plasma as deposition, etching, surface modification and chemical conversion has stimulated a renewed interest in plasma science in the atomic physical chemistry regime. The necessity to optimize the various plasma processing techniques in terms of rates, and material properties has made it mandatory to take a new look at the various processes, as fragmentation,

D C Schram; J A M van der Mullen; M C M van de Sanden

1994-01-01

157

Chemistry 675 Advanced Organic Chemistry  

E-print Network

Fall 2014 Chemistry 675 Advanced Organic Chemistry MWF 10:35-11:30 AM 200 LSB Professor John D Description: CHE675 is a graduate-level organic chemistry course focused on physical organic chemistry, which deals with the structure and reactivity of organic molecules and provides the foundation

Doyle, Robert

158

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

159

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

160

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.

161

Hot Tickets  

ERIC Educational Resources Information Center

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

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

2008-01-01

162

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 ...

163

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

164

Colour Chemistry  

ERIC Educational Resources Information Center

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

Griffiths, J.; Rattee, I. D.

1973-01-01

165

Organic Chemistry  

NSDL National Science Digital Library

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

166

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

167

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.

168

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.

169

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.

170

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

171

Forensic Chemistry  

NASA Astrophysics Data System (ADS)

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

Bell, Suzanne

2009-07-01

172

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

173

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

174

Analytical Chemistry  

NSDL National Science Digital Library

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

Henderson, David E.

175

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

176

Modelling the sulphur chemistry evolution in Orion KL  

E-print Network

We study the sulphur chemistry evolution in the Orion KL along the gas and grain phases of the cloud. We investigate the processes that dominate the sulphur chemistry and to determine how physical and chemical parameters, such as the final star mass and the initial elemental abundances, influence the evolution of the hot core and of the surrounding outflows and shocked gas (the plateau). We independently modelled the chemistry evolution of both components 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 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 differ...

Esplugues, G B; Goicoechea, J R; Cernicharo, J

2014-01-01

177

How iron-containing proteins control dioxygen chemistry: a detailed atomic level description via accurate quantum chemical and mixed quantum mechanics\\/molecular mechanics calculations  

Microsoft Academic Search

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

Richard A. Friesner; Mu-Hyun Baik; Benjamin F. Gherman; Victor Guallar; Maria E. Wirstam; Robert B. Murphy; Stephen J. Lippard

2003-01-01

178

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

Microsoft Academic Search

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

Jean-Marie Lehn

2004-01-01

179

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.

2007-06-06

180

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

181

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 ...

182

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

183

ION CHEMISTRY 40 Years of  

E-print Network

Cristol Chemistry Building Room 142 Event Parking Euclid Auto Park $3.00 per day on Saturday and Sunday Beverages Coffee Hot and Iced Tea Lemonade 16thSt 15thSt Euclid Ave 18thSt Euclid Ave 18thSt Broadway University Memorial Center (UMC) Euclid AutoPark FA ATLS CHEM Ketchum Library POWR ENVD MUS EKLC Hellems Arts

Lineberger, W. Carl

184

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

185

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.

186

Atmospheric chemistry of CF 3CH 2CF 2CH 3 (HFC365mfc): Kinetics and mechanism of chlorine atom initiated oxidation, infrared spectrum, and global warming potential  

Microsoft Academic Search

Smog chamber\\/FTIR techniques were used to study the chlorine atom initiated oxidation of CF3CH2CF2CH3 in 700Torr of N2\\/O2 at 296K. Relative rate techniques were used to measure k(Cl+CF3CH2CF2CH3)=(1.020.14)10?15cm3molecule?1s?1. The reaction proceeds via attack on the 朇H3 group leading to formation of CF3CH2CF2CHO which in turn is oxidized to CF3CHO and COF2. The integrated IR band strength of CF3CH2CF2CH3 over the

Y. Inoue; M. Kawasaki; T. J. Wallington; M. D. Hurley

2008-01-01

187

Physical Chemistry and Theoretical Chemistry CHM1441H Mathematical Methods  

E-print Network

to quantum mechanics, potential scattering, formal scattering theory, and second quantization. Prerequisite), physical realizations of quantum computers (trapped ions, NMR, quantum dots, cavity QED, trapped atoms Physical Chemistry CHM1443H Intermediate Quantum Mechanics Elements of group theory and its applications

Chan, Hue Sun

188

Effects of NH3 and N2 additions to hot filament activated CH4/H2 gas mixtures  

NASA Astrophysics Data System (ADS)

Resonance enhanced multiphoton ionization and cavity ring down spectroscopies have been used to provide spatially resolved measurements of relative H atom and CH3 radical number densities, and NH column densities, in a hot filament (HF) reactor designed for diamond chemical vapor deposition and here operating with a 1% CH4/n/H2 gas mixture梬here n represents defined additions of N2 or NH3. Three-dimensional modeling of the H/C/N chemistry prevailing in such HF activated gas mixtures allows the relative number density measurements to be placed on an absolute scale. Experiment and theory both indicate that N2 is largely unreactive under the prevailing experimental conditions, but NH3 additions are shown to have a major effect on the gas phase chemistry and composition. Specifically, NH3 additions introduce an additional series of "H-shift" reactions of the form NHx+H?NHx-1+H2 which result in the formation of N atoms with calculated steady state number densities >1013 cm-3 in the case of 1% NH3 additions in the hotter regions of the reactor. These react, irreversibly, with C1 hydrocarbon species forming HCN products, thereby reducing the concentration of free hydrocarbon species (notably CH3) available to participate in diamond growth. The deduced reduction in CH3 number density due to competing gas phase chemistry is shown to be compounded by NH3 induced modifications to the hot filament surface, which reduce its efficiency as a catalyst for H2 dissociation, thus lowering the steady state gas phase H atom concentrations and the extent and efficiency of all subsequent gas phase transformations.

Smith, James A.; Wills, Jonathan B.; Moores, Helen S.; Orr-Ewing, Andrew J.; Ashfold, Michael N. R.; Mankelevich, Yuri A.; Suetin, Nikolay V.

2002-07-01

189

Nuclear Chemistry.  

ERIC Educational Resources Information Center

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

Chemical and Engineering News, 1979

1979-01-01

190

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

191

Chemistry Notes  

ERIC Educational Resources Information Center

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

School Science Review, 1973

1973-01-01

192

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

193

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

194

Radioanalytical Chemistry  

NSDL National Science Digital Library

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

Hardy, James K.

195

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.

Foundation, Wgbh E.

2011-03-21

196

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.

197

Stratospheric chemistry  

SciTech Connect

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

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

1991-01-01

198

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

199

Computational Chemistry for Chemistry Educators  

NSDL National Science Digital Library

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

Sendlinger, Shawn C.; Metz, Clyde R.

200

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

201

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.

Wojn醨ovits, L.

202

Position: Assistant Professor of Chemistry, Physical Chemistry  

E-print Network

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

203

CHEMISTRY 107-01 GENERAL CHEMISTRY I  

E-print Network

CHEMISTRY 107-01 GENERAL CHEMISTRY I Spring 2002 8:00 am - 8:50 am, MTuWTh Rm. CNSB 243 INSTRUCTOR-1835 Email: chfindley@ulm.edu URL: http://www.ulm.edu/chemistry/findley COURSE Content: Principles of modern chemistry. Goals/ Objectives: CHEM 107 is the first semester of a fundamental introduction to chemistry

Findley, Gary L.

204

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.

205

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

206

Chemistry & Industry  

NSDL National Science Digital Library

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

1997-01-01

207

Chemistry Now  

NSDL National Science Digital Library

The National Science Foundation (NSF) recently teamed up with NBC and the National Science Teachers Association to celebrate the International Year of Chemistry. Their big joint project was to create Chemistry Now, a weekly online video series that uncovers and explains the science of common, physical objects. There are over two dozen short films here that cover topics like the chemistry of salt, grapheme, safety glass, and the common cheeseburger. All of the videos are lively and interesting, and they can be used in a wide range of classroom settings to provide visual and audio reinforcement of topics that might be addressed in course lectures and other activities. The videos are completely free and the site includes links to other organizations that have created similar videos.

2012-08-17

208

Chemistry & Industry  

NSDL National Science Digital Library

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

2006-01-11

209

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

210

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

ERIC Educational Resources Information Center

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

Hanes, Cara

2004-01-01

211

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

212

/6582 Biophysical Chemistry Fall Biophysical Chemistry  

E-print Network

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

Sherrill, David

213

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.

214

Definition Chemistry  

E-print Network

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

Boisvert, Jeff

215

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

216

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.

217

Countertop Chemistry  

NSDL National Science Digital Library

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

218

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

219

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

220

Common Chemistry  

NSDL National Science Digital Library

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

Chemical Abstracts Service (CAS)

221

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

222

Chlorine Chemistry  

NSDL National Science Digital Library

From poolcenter.com comes the Chlorine Chemistry Web site. Ten questions related to chlorine are answered such as What's the History of Chlorine, How Does Chlorine Work to Sanitize, and What Effect Does pH Have on Chlorine. Each is briefly explained in simple and non-technical language.

223

Bad Chemistry  

NSDL National Science Digital Library

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

Lehmann, Kevin; University, Princeton

224

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

225

Magnetohydrodynamic Simulations of Hot Jupiter Thermospheres  

NASA Astrophysics Data System (ADS)

The majority of models of atmospheric escape from hot Jupiters have focused on one-dimensional, spherically-symmetric models. We present the results from 2-dimensional axisymmetric simulations of hot Jupiters including tidal gravity and magnetic fields as well as photo-ionization and photoelectric heating due to multiple atomic species. Escape is suppressed in polar and equatorial regions by tidal gravity and magnetic fields, respectively, reducing mass-loss estimates achieved through 1-dimensional models. For sufficiently large magnetic field strengths, an equatorial magnetic dead zone creates a static reservoir of hot gas extending to multiple planetary radii and exhibiting temperatures hotter than found within the escaping gas. The possibility of observing this reservoir of gas is discussed, as well as the influence of heavy atoms on the result.

Christie, Duncan; Arras, Phil; Li, Zhi-Yun

2015-01-01

226

Interactive Teaching Units: Green Chemistry  

NSDL National Science Digital Library

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

2009-06-08

227

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.

228

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 M鴏ler-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-Fran鏾is; Ball, Caleb J; Gill, Peter M W

2015-01-21

229

Chemistry Gateways and Resources  

NSDL National Science Digital Library

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

2008-03-14

230

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

231

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

232

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 ...

233

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 Li鑗e (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

234

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.

235

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.

236

SYLLABUS for CHEMISTRY 2310 ORGANIC CHEMISTRY 1  

E-print Network

SYLLABUS for CHEMISTRY 2310 ORGANIC CHEMISTRY 1 Lectures: Monday, Wednesday and Friday 8:35 AM-9 路 Highly Recommended Equipment: Turning Point Clicker 路 Highly Recommended: (1) "Organic Chemistry I Homework. 路 Class Objective: To study and begin to understand organic chemistry 路 Methods: Lectures

Simons, Jack

237

SYLLABUS CHEMISTRY 5710 ADVANCED ORGANIC CHEMISTRY LABORATORY  

E-print Network

SYLLABUS CHEMISTRY 5710 ADVANCED ORGANIC CHEMISTRY LABORATORY T, Th 9:40AM-10:30AM HEB 2006 understanding of organic chemistry. Methods: lectures, problem solving, laboratory experiments, laboratory reports, Prerequisites: Organic Chemistry II and Lab (Chem 2320 and Chem 2325) DATES (Approximate (except

Simons, Jack

238

ORGANIC CHEMISTRY UCLA Organic Chemistry Faculty  

E-print Network

ORGANIC CHEMISTRY UCLA Organic Chemistry Faculty perform research in molecular machines, exotic Harran, Professor and D.J. & J.M Cram Chair in Organic Chemistry: The Harran Group explores new, Distinguished Professor and Saul Winstein Chair in Organic Chemistry: The Houk Group develops qualitative rules

Levine, Alex J.

239

CHEMISTRY DEPARTMENT Chem 315 (Honors Organic Chemistry)  

E-print Network

CHEMISTRY DEPARTMENT Chem 315 (Honors Organic Chemistry) Fall 2014 Important Registration Information Admission to Honors Organic Chemistry (Fall 2014) is restricted to the following students are interested in taking CHE315 in the fall should register for Organic Chemistry CHE307 and apply for admission

Lawson, Catherine L.

240

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

241

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

242

Electroanalytical chemistry  

SciTech Connect

Many of the most significant electroanalytical advances may still lie ahead, according to Allen J. Bard of the University of Texas at Austin. Listening to Bard's presentation at the Eastern Analytical Symposium last November, one could not help but come away with the impression that electroanalytical chemistry may be entering the most exciting era in its history. It is an era in which we will see electrochemistry in the gas and solid phases, electrochemical resolution on the order of angstroms (scanning tunneling electrochemistry), and electrochemical expert systems.

Borman, S.

1987-02-15

243

Azulene Chemistry  

NSDL National Science Digital Library

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

244

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

245

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.

246

Interaction of hydrogen, methane, ethylene, and cyclopentane with hot tungsten: Implications for the growth of diamond films  

SciTech Connect

The production of hydrogen atoms from H[sub 2] was found to be largest on clean tungsten, less on carburized tungsten, and not observable on graphite. Evaporation of tungsten from carburized tungsten was seen at temperatures below 2500 [degree]C but not below 2200 [degree]C. XPS measurements indicated that slightly carburized tungsten contained some graphite in the surface region while heavily carburized tungsten contained much more graphite. The surface concentration of carbon was found to depend in a complicated manner on the balance between carbide and graphite growth and carbon evaporation. The reaction probability of the incident gas is also a determining factor. In addition, computer simulations were used to calculate the concentrations of various species in the gas phase under conditions which are typical of those used in diamond hot-filament CVD reactors. Calculated gas-phase species distributions near the substrate for carbon-atom/H[sub 2] mixtures are found to be similar for most species to those calculated for CH[sub 4]/H[sub 2] mixtures. It appears that the fast H[sub 2] and H chemistry determines the equilibrium mixture and that it is nearly independent of the type of carbon containing species introduced near the filament. Literature results obtained in typical diamond hot-filament CVD reactors are compared and interpreted on the basis of the present data.

Winters, H.F.; Seki, H. (IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120-6099 (United States)); Rye, R.R.; Coltrin, M.E. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States))

1994-07-15

247

What is Chemistry?  

NSDL National Science Digital Library

Provided by Kiwi Web Chemistry & New Zealand, the "What is Chemistry?" Web site offers a wealth of chemistry information and links. Visitors can read the definition of and link to other sites on inorganic chemistry, organic chemistry, analytical chemistry, physical chemistry, stoichiometry, nuclear chemistry, alchemy, and biochemistry. Other pages of the site explore acids and bases, redox reductions, equations, moles, periodic tables, and more. This extensive and interesting site does a good job of clearly explaining some difficult concepts as well as providing educators and students a good source of other quality sites containing similar content.

Campbell, Allan

248

Tropospheric Chemistry  

NASA Technical Reports Server (NTRS)

The fundamental processes that control the chemical composition and cycles of the global troposphere and how these processes and properties affect the physical behavior of the atmosphere are examined. The long-term information needs for tropospheric chemistry are: to be able to predict tropospheric responses to perturbations, both natural and anthropogenic, of these cycles, and to provide the information required for the maintenance and effective future management of the atmospheric component of our global life support system. The processes controlling global tropospheric biogeochemical cycles include: the input of trace species into the troposphere, their long-range transport and distribution as affected by the mean wind and vertical venting, their chemical transformations, including gas to particle conversion, leading to the appearance of aerosols or aqueous phase reactions inside cloud droplets, and their removal from the troposphere via wet (precipitation) and dry deposition.

Mohnen, V.

1984-01-01

249

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

250

New sources for the hot oxygen geocorona  

NASA Technical Reports Server (NTRS)

This paper investigates new sources of thermospheric non thermal (hot) oxygen due to exothermic reactions involving numerous minor (ion and neutral) and metastable species. Numerical calculations are performed for low altitude, daytime, winter conditions, with moderately high solar activity and low magnetic activity. Under these conditions we find that the quenching of metastable species are a significant source of hot oxygen, with kinetic energy production rates a factor of ten higher than those due to previously considered O2(+) and NO(+) dissociative recombination reactions. Some of the most significant new sources of hot oxygen are reactions involving quenching of O(+)((sup 2)D), O((sup 1)D), N((sup 2)D), O(+)((sup 2)P) and vibrationally excited N2 by atomic oxygen.

Richards, P. G.; Hickey, M. P.; Torr, D. G.

1994-01-01

251

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

252

Chemistry 320N Organic Chemistry II  

E-print Network

Chemistry 320N Organic Chemistry II for Prehealth Professionals Unique number: 52365 Spring 2013 M students can access the information. #12;Required Text: Brown, Foote, Iverson, & Anslyn Organic Chemistry are less important for Organic II than Organic I, but still incredibly useful at times). Weekly Recitation

253

Chemistry 224 Fall 2008 Honors General Chemistry  

E-print Network

Chemistry 224 Fall 2008 Honors General Chemistry Dr. Greg Williams Office hours: Onyx 182 Tu and Th regularly learn more chemistry and earn higher grades. Classroom office hours will be held in Onyx 171; there will be no formal presentations during office hours. There is also an office hour on Wednesday 2-3 pm in Onyx 182

Richmond, Geraldine L.

254

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

255

Hot Air Balloon  

NSDL National Science Digital Library

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

Centers, Oakland D.

2012-01-01

256

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

257

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.

258

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,

259

Quark interactions and colour chemistry  

NASA Astrophysics Data System (ADS)

The interaction between quarks, according to the current theory of quantum chromo-dynamics, is formally rather similar to the electromagnetic interaction between electrons and nucleons, both being governed by locally gauge-invariant field theories. It is tempting therefore to discuss the spectroscopy of hadrons, which are quark composites bound by colour forces, in the same language as the spectroscopy of atoms and molecules which are bound states of electrons and nucleons held together by e.m. forces. Because of the difference in gauge groups, however, the dynamics are very different. Nonetheless, it appears likely that metastable multiquark hadron states can exist which are analogous to atoms and molecules in QED. In these lectures, tentative steps are taken in developing the rudiments of a new 慶olour chemistry of these atoms and 憁olecules.

Hong-Mo, Chan

260

Chemistry by the Case: Integrated Case Teaching and Team Learning.  

ERIC Educational Resources Information Center

Introduces a chemistry unit, the "Evolving Atom", based on a problem-based learning approach designed for non-science majors. Uses the case method to address memory loss in mice during instruction. (Contains 14 references.) (YDS)

Dinan, Frank J.

2002-01-01

261

Hot subdwarfs revisited  

SciTech Connect

The properties and evolutionary status of the hot B and O subdwarfs are reinvestigated using recent homogeneous grids of hot, high-gravity model atmospheres and detailed convective envelope calculations appropriate to the hot subdwarf region of the H-R diagram discussed by Greenstein and Sargent. An alternative method of analysis of the hot subdwarfs is outlined, where comparisons between observations and theoretical evolutionary tracks are made as close to the fundamental observational results as possible, and are performed directly in the observer's (i.e., (U-B) versus (B-V), or (B-V) versus D(0.1) of H..gamma..) diagram. As an illustrative example of this procedure, we use a set of gravitationally contracting pre--white dwarf evolutionary sequences at M/sub asterisk//M/sub sun/ = 0.4, 0.6, and 0.8 which are found to evolve through the hot subdwarf domain along the extended horizontal branch.

Wesemael, F.; Wingent, D.E.; Cabot, W.; Van Horn, H.M.; Fontaine, G.

1982-03-01

262

Elementary and brief introduction of hadronic chemistry  

NASA Astrophysics Data System (ADS)

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

Tangde, Vijay M.

2013-10-01

263

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

264

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

265

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

266

ACS Green Chemistry Institute  

NSDL National Science Digital Library

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

2005-12-13

267

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

268

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

269

Optimization of Hot Standby  

E-print Network

% of the total hot standby capacity can be provided at less than one third of the cost of maximizing hot standby capacity. The appropriate use of this plot can provide useful insights to aid in the decision making process. Minimum Hot Standby, Mlb/hr Cos... provides some flexibility to reduce costs by selecting the most cost effective drive. Which drive to use depends on several factors including he cost of electricity, overall site steam balance and the perceived reliability of turbines versus motors...

de Souza, J.; Holden, D.

2004-01-01

270

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."

271

Descriptive Chemistry in High School Curriculum.  

ERIC Educational Resources Information Center

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

Rajan, Raj G.

1983-01-01

272

Ion-Molecule Chemistry in Titan's Ionosphere  

NASA Technical Reports Server (NTRS)

We present a summary of the information available from laboratory studies of ion-molecule reactions that is relevant to the chemistry occuring in Titan's ionopshere. Reaction information from the literature has been collated and we have measured many new reations, including some ion-atom reactions.

Anicich, V. G.; McEwan, M. J.

1996-01-01

273

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.

274

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

275

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

276

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

277

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

278

FALL 2012 (as of 7/24/12) GENERAL CHEMISTRY TEXTBOOK LIST  

E-print Network

FALL 2012 (as of 7/24/12) GENERAL CHEMISTRY TEXTBOOK LIST Course Number ISBN Number Title of Text;FALL 2012 GENERAL CHEMISTRY TEXTBOOK LIST (con't) Course Number ISBN Number Title of Text and and/or Material Edition Author Publishers 10901 0077700562 Chemistry: Atoms First, 1st Ed., (packaged

Pittendrigh, Barry

279

CHEMISTRY COURSE OFFERINGS SPRING, 2013 CHEM 0001-01 CHEMICAL FUNDAMENTALS W/LAB  

E-print Network

, electroanalytical, and spectroscopic instrumentation. For chemistry and life science majors, as well as studentsCHEMISTRY COURSE OFFERINGS SPRING, 2013 (10/31/12) CHEM 0001-01 CHEMICAL FUNDAMENTALS W/LAB Atomic, and thermochemistry. Additional topics may include qualitative thermodynamics and equilibrium and chemistry

Kounaves, Samuel P.

280

Chemistry in grain aggregates: a source of complex molecules?  

NASA Astrophysics Data System (ADS)

The aggregation of grains in dense protostellar clouds brings together materials such as silicates, carbons, polycyclic aromatic hydrocarbons and ices to form porous structures with high internal volume. Some physical and chemical properties of these aggregate grains are discussed in the context of the role that they may play in the formation of complex organic and organometallic compounds. One characteristic of such grains that is unique outside planetary systems is the availability of all elements and a number of their common compounds in a composite solid. In dark clouds, the chemistry inside aggregate grains will be driven by cosmic ray heating and sputtering. This occurs in an environment where the products of such reactions can be retained within the dust particle. Hot atom chemistry and secondary reactions are facilitated by the re-entrant nature of such aggregated structures, leading to the possible formation of complex organic compounds. In particular, the sputtering of Si, Mg and Fe from silicate dust is discussed, and it is shown that a variety of organometallic compounds could be expected in ices within aggregate grains. The optical depth for ultraviolet light within aggregates is large, so that materials inside such grains will be effectively shielded from ambient radiation. However, the incorporation of luminifors such as those grain components responsible for the extended red emission converts ultraviolet to visible and near-infrared radiation, and might moderate photochemistry within aggregates. It is suggested that the chemical environment within aggregates may be conducive to the formation and retention of complex molecules such as amino acids, peptides and a variety of organometallic compounds.

Duley, W. W.

2000-12-01

281

Adhesive Bonding to Galvanized Steel: II. Substrate Chemistry, Morphology and Bond Failure Analysis  

Microsoft Academic Search

Galvanized substrate morphology, oxide layer chemistry, bond failure modes, failure loci, and bondline corrosion have been investigated for adhesive bonds to galvanized steel. Significant differences in surface morphology were observed between the relatively smooth surfaces of hot-dipped substrates and the considerably rougher texture of 揺lectroplated substrates. The hot-dipped substrates were also chemically heterogeneous, with significant amounts of Al, Mg, Ca,

Robert T. Foister

1987-01-01

282

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....

283

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

284

Reactor hot spot analysis  

SciTech Connect

The principle methods for performing reactor hot spot analysis are reviewed and examined for potential use in the Applied Physics Division. The semistatistical horizontal method is recommended for future work and is now available as an option in the SE2-ANL core thermal hydraulic code. The semistatistical horizontal method is applied to a small LMR to illustrate the calculation of cladding midwall and fuel centerline hot spot temperatures. The example includes a listing of uncertainties, estimates for their magnitudes, computation of hot spot subfactor values and calculation of two sigma temperatures. A review of the uncertainties that affect liquid metal fast reactors is also presented. It was found that hot spot subfactor magnitudes are strongly dependent on the reactor design and therefore reactor specific details must be carefully studied. 13 refs., 1 fig., 5 tabs.

Vilim, R.B.

1985-08-01

285

Industrial Chemistry and School Chemistry: Making Chemistry Studies More Relevant  

ERIC Educational Resources Information Center

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

Hofstein, Avi; Kesner, Miri

2006-01-01

286

Index to the Understanding the Atom Series.  

ERIC Educational Resources Information Center

This index was prepared for the set of 51 booklets in the "Understanding the Atom Series" published by the U. S. Atomic Energy Commission for high school students and their teachers. In addition to the index, a complete list of the series is provided in which the booklets are grouped into the categories of physics, chemistry, biology, nuclear

Atomic Energy Commission, Oak Ridge, TN. Div. of Technical Information.

287

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

288

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

289

The Hot Tub Mystery  

NSDL National Science Digital Library

This case study sets up a mystery and asks students to solve it using science: why was the couple found dead in their hot tub? The material asks students to connect seemingly unrelated factors, such as blood pressure, hot water and alcohol. The material would be most appropriate for lower level undergraduate students. The case study and teaching notes may be downloaded in PDF format. The site also includes a section for instructor feedback where general comments may be read and contributed.

House, Herbert

2011-01-06

290

Implications of SWAS Observations for Interstellar Chemistry and Star Formation  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

291

Hot off the press.  

PubMed

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as forazoline A from an Actinomadura species. PMID:25565355

Hill, Robert A; Sutherland, Andrew

2015-01-28

292

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 Kr黦er; Donatella Cassettari; Bj鰎n Hessmo; Thomas Maier; J鰎g Schmiedmayer

1999-12-23

293

Thomson Atom  

Microsoft Academic Search

The historical development leading up to the Rutherford-Bohr model of the atom is briefly surveyed. The atomic model, suggested by J. J. Thomson before Rutherford's model, is investigated. The quantization shows that the bound states bear a marked resemblance to those of the hydrogen atom. However, the states are in general nondegenerate. Thus, the Thomson atom could not have survived

Henry Zatzkis

1958-01-01

294

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

295

Undergraduate Courses in Chemistry Catalogue Descriptions and Course Syllabi  

E-print Network

-1036.) (3H,3C) CHEM 1015 % CHEM 1016 % Atoms & Atomic Structure 14 Organic Chemistry 15 Periodic Table 7, and important applications. (Dupli- cates 1015-1016) (3H,3C) CHEM 1035 / 1035H % CHEM 1036 / 1036H % Elements/Periodic Table 7 Chemical Kinetics 13 Nomenclature 3 Chemical Equilibrium 13 Mass Relationships 7 Acid

Crawford, T. Daniel

296

Pushing the Rainbow: Frontiers in Color Chemistry; Light and Color in Chemistry- Report on Two American Chemical Society Presidential Events  

NASA Astrophysics Data System (ADS)

On Sunday March 21, 1999, the 217th ACS National Meeting in Anaheim, California sponsored two Presidential Events, "Pushing the Rainbow: Frontiers in Color Chemistry" and "Light and Color in Chemistry". The events included 10 exceptional and very different speakers who explored various aspects of the importance of light and color in chemistry and chemistry teaching, in other sciences, and in art and human culture. Support for the events was provided by Research Corporation, General Atomics Sciences Education Foundation, Eastman Kodak Company, American Chemical Society, and University of Wisconsin-Madison Materials Research Science and Engineering Center for Nanostructured Materials and Interfaces.

Gettys, Nancy S.

1999-06-01

297

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

298

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1979-February 14, 1980  

SciTech Connect

The program consists of six interrelated areas: (1) Reactions of iodine with alkenes and alkynes activated by radiative neutron capture and isomeric transition in low pressure gaseous systems employing additives and rare gas moderators, high pressure, and liquid systems. Special attention was given to the reactivity of excited complex formation and structural effects of electrophilic iodine attack on various pi-bond systems. (2) The gas-to-condensed phase transition in halogen high energy chemistry. Current interest involves the study of caging effects of an ice lattice on recombination reactions involving neutron-irradiated frozen aqueous solutions of halogenated organic and biochemical solutes in order to learn more about kinetic energy effects, halogen size, solute molecule size, steric effects and hydrogen bonding within an ice lattice cage. (3) Systematics of halogen hot atom reactions. The reactions of /sup 80m/Br, /sup 80/Br, /sup 82m/Br + /sup 82/Br, /sup 82/Br, /sup 82/Br, /sup 128/I, /sup 130/I, and /sup 130m/I + /sup 130/I activated by radiative neutron capture or isomeric transition in hydrocarbons and halo-substituted alkanes in low pressure and high pressure gaseous systems employing additives and rare gas moderators are currently being studied. (4) Mathematical and computer simulation studies of caging events within an ice lattice are being investigated. (5) At Brookhaven National Laboratory, cyclotron-produced chlorine and fluorine hot atoms substitution reactions with molecules possessing a single chiral center are under investigation to determine the role of hot atom kinetic energy, halogen atom, enantioner structure, steric effects and phase on the extent of substitution by retention of configuration or by Walden inversion. (6) The applications of high energy techniques and concepts to neutron activation analysis for trace element determinations in biological systems was continued.

Rack, E.P.

1980-02-01

299

School of Chemistry CHEM3100: Chemistry at a Molecular Level  

E-print Network

Chemistry Mills, Rebecca Chemistry Morawski, Adrian Chemistry Mountford, Daniel Chemistry Newman, Aidan 1.67 Prof G S Beddard Room 2.89 Dr J Fisher Room G.01 Dr D Shalashilin Room 2.86 Dr D Shalashilin

Rzepa, Henry S.

300

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, Bj鰎n

2015-01-01

301

Igniting Chemistry in Fireworks  

NSDL National Science Digital Library

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

Foundation, Wgbh E.

2004-01-29

302

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

303

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

304

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

ERIC Educational Resources Information Center

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

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

2001-01-01

305

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 1947颅1960. Mary Kilpatrick was a chemistry faculty member from 1947

Heller, Barbara

306

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.

307

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

308

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.

309

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.

310

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

311

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

312

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

313

Interaction of cold atoms with short laser pulses  

Microsoft Academic Search

We present a powerful diagnostic system to observe the interaction of ultrafast laser pulses with trapped ^87Rb atoms. The ionization of cold atoms and the formation of cold molecules in an intense laser field in the muK temperature range open new branches of research in chemistry, metrology, and quantum physics. However, the interaction of cold atoms with short laser pulses

Karen Chamberlin; Derek Lilla; Kyle Taylor; Kevin Zick; Greg Taft; Hai Nguyen

2006-01-01

314

Hot Jupiter Magnetospheres  

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

315

Computational chemistry and aeroassisted orbital transfer vehicles  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

316

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

317

Brooklyn College Department of Chemistry  

E-print Network

Brooklyn College Department of Chemistry General Chemistry I Syllabus GENERAL CHEMISTRY I 颅 SPRING Manual for General Chemistry, M. N. Kobrak, Ed., First Edition," Kendall/Hunt, Dubuque, IA 2008 Coordinator for General Chemistry TBA Undergraduate Chemistry Advisor: TBA Undergraduate Deputy Chair: Prof

Kobrak, Mark N.

318

Hot-Water Worms May Use Bacteria as Shield  

NSDL National Science Digital Library

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

Roach, John

2009-06-17

319

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

320

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.

321

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

322

Explanation of charged nanoparticle production from hot surfaces  

Microsoft Academic Search

The production of charged nanoparticles from hot surfaces like glowing wires was used earlier in connection with mobility classification, but the phenomenon was not understood. In the present paper, negative particle charge is explained by thermoemission of electrons and positive particle charge by surface ionization of impurity atoms with low ionization energy. Such impurities are inevitably present even in high-purity

C. Peineke; A. Schmidt-Ott

2008-01-01

323

What's Hot? What's Not?  

ERIC Educational Resources Information Center

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

Buczynski, Sandy

2006-01-01

324

Keep It Hot!  

NSDL National Science Digital Library

Student teams design insulated beverage bottles with the challenge to test them to determine which materials (and material thicknesses) work best at insulating hot water to keep it warm for as long as possible. Students test and compare their designs in still air and under a stream of moving air from a house fan.

RESOURCE GK-12 Program,

325

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

326

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

327

Extrapolating to "Hot Jupiters"  

E-print Network

Extrapolating to "Hot Jupiters" P. Zarka LESIA, Observatoire de Paris, Meudon Collaborators : R-15) HOM (L=7-11) Io-DAM (L=6) = 90掳 non-Io-DAM ? B [Zarka, 2000] 路 5 radio planets 路 6 LF (KOM, Lyman-) [Prang茅 et al., 1996] #12;[Zarka et al., 2001] Planetary Radio Emissions 路 nonthermal cyclotron

Demoulin, Pascal

328

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

329

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

330

Kamchatka's thermal hot springs  

NSDL National Science Digital Library

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

Kamchatka, Vision O.

331

Some Like it Hot  

NSDL National Science Digital Library

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

Bortman, Henry; Magazine, Astrobiology

332

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.

333

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...

334

Hot-hole photodetectors  

NASA Astrophysics Data System (ADS)

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

2014-05-01

335

Atomic Spectroscopy  

NSDL National Science Digital Library

This article outlines the main concepts of atomic structure, with some emphasis on terminology and notation. Topics of discussion include wavelengths, intensities, shapes of spectral lines, and LS coupling. Originally appearing in the Atomic, Molecular, and Optical Physics Handbook, edited by Drake, this online version of Atomic Spectroscopy contains internal links as well as external links to spectroscopic data.

Martin, William; Wiese, Wolfgang

2003-10-10

336

Hadronic Atoms  

E-print Network

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

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

2009-03-02

337

If Mars had hot-spots  

NASA Astrophysics Data System (ADS)

There are tantalizing clues to possible existence of outgassing sources, the hot-spots, on Mars. If confirmed, they would result in the presence of numerous chemical species "locally" that would otherwise go undetected in observations with poor spatial resolution. This paper is on the prediction of species that would form in the martian atmosphere following the outgassing from any possible hot-spots. Two sets of observations may imply the existence of regions of outgassing on Mars: a tentative detection of formaldehyde (CH2O) "locally", in the north equatorial spring, from the Phobos spacecraft in 1989 (Korablev, et al., Planet Space Sci. 41, 441, 1993), and indications of recent groundwater seepage and surface runoff particularly at middle and high martian latitudes (Malin and Edgett, Science, 288, 2330, 2000). The relatively short photochemical lifetime of 13 hrs for CH2 O in the martian atmosphererequires a "continuous" source of methane, whose oxidation provides the most efficient mechanism for producing formaldehyde. CH2O is an important precursor to the formation of complex hydrocarbons. Attempts to detect the species expected to be outgassed from the hot-spots or those that would form in the ensuing atmospheric chemistry have failed, perhaps because the observations were averaged over large areas, usually the disk or the hemisphere (the exception being the above local HCHO tentative detection). Considering the current disk-averaged upper limits of possible outgassed molecules including CH4 , SO2 , etc. and their possible enhancement over the hot-spots, we have developed chemical models to predict the abundances of new species that are expected to be formed in the Martian atmosphere locally. The Planetary Fourier Spectrometer on Mars Express appears well-suited for detecting many of the species.

Wong, A.; Atreya, S.

338

Organic Chemistry 51B -Winter 2013 Organic Chemistry Peer Tutoring Program Chemistry 51B Reactions List  

E-print Network

Organic Chemistry 51B - Winter 2013 Organic Chemistry Peer Tutoring Program Chemistry 51B Reactions(s). Chapter 7: Nucleophilic Substitution + + NaOH CH3O- #12;Organic Chemistry 51B - Winter 2013 Organic Chemistry Peer Tutoring Program Chapter 8: Elimination Reactions #12;Organic Chemistry 51B - Winter 2013

Rose, Michael R.

339

Refurbishment of an Analytical Laboratory Hot Cell Facility  

SciTech Connect

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

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

1996-08-01

340

Exercising Safely in Hot Weather  

MedlinePLUS

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

341

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 ...

342

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

343

Atom structures  

E-print Network

The atom structure of an atomic boolean algebra with operators is some canonically defined frame or relational structure that is based on the set of atoms of the algebra. We discuss the relation between varieties of boolean algebras with operators and the induced class of atom structures. Our main result states that for a variety V of boolean algebras with conjugated operators, the corresponding class At V of atom structures is elementary; moreover, an (infinite) axiomatization of At V can be generated from the equations defining V. 1

Yde Venema

1997-01-01

344

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

345

atomic spectra 1 Atomic Spectra  

E-print Network

Physics, pp. 88-93 (Rutherford nuclear model), 93-106 (atomic structure and electron spectra) 2. D. W 3. Beiser: Concepts of Modern Physics, pp. 131-161 (atomic structure and electron spectra) 4. E. Lamb, Jr. and R. C. Retherford: The Structure of the Hydrogen Atom by a Microwave Method, Phys

Glashausser, Charles

346

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

347

HPAM: Hirshfeld partitioned atomic multipoles  

NASA Astrophysics Data System (ADS)

An implementation of the Hirshfeld (HD) and Hirshfeld-Iterated (HD-I) atomic charge density partitioning schemes is described. Atomic charges and atomic multipoles are calculated from the HD and HD-I atomic charge densities for arbitrary atomic multipole rank l on molecules of arbitrary shape and size. The HD and HD-I atomic charges/multipoles are tested by comparing molecular multipole moments and the electrostatic potential (ESP) surrounding a molecule with their reference ab initio values. In general, the HD-I atomic charges/multipoles are found to better reproduce ab initio electrostatic properties over HD atomic charges/multipoles. A systematic increase in precision for reproducing ab initio electrostatic properties is demonstrated by increasing the atomic multipole rank from l=0 (atomic charges) to l=4 (atomic hexadecapoles). Both HD and HD-I atomic multipoles up to rank l are shown to exactly reproduce ab initio molecular multipole moments of rank L for L?l. In addition, molecular dipole moments calculated by HD, HD-I, and ChelpG atomic charges only ( l=0) are compared with reference ab initio values. Significant errors in reproducing ab initio molecular dipole moments are found if only HD or HD-I atomic charges used. Program summaryProgram title: HPAM Catalogue identifier: AEKP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKP_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License v2 No. of lines in distributed program, including test data, etc.: 500 809 No. of bytes in distributed program, including test data, etc.: 13 424 494 Distribution format: tar.gz Programming language: C Computer: Any Operating system: Linux RAM: Typically, a few hundred megabytes Classification: 16.13 External routines: The program requires 'formatted checkpoint' files obtained from the Gaussian 03 or Gaussian 09 quantum chemistry program. Nature of problem: An ab initio molecular charge density ?(r) is partitioned into Hirshfeld (HD) and Hirshfeld-Iterated (HD-I) atomic charge densities ?(r) on a grid. Atomic charges q and multipoles Qlma are calculated from the partitioned atomic charge densities ?(r) by numerical integration. Solution method: Molecular and isolated atomic grids are generated for the molecule of interest. The ab initio density matrix P and basis functions ?(r) are read in from 'formatted checkpoint' files obtained from the Gaussian 03 or 09 quantum chemistry programs. The ab initio density is evaluated for the molecule and the isolated atoms/atomic ions on grids and used to construct Hirshfeld (HD) and Hirshfeld-I (HD-I) partitioned atomic charges densities ?(r), which are used to calculate atomic charges q and atomic multipoles Qlma by integration. Restrictions: The ab initio density matrix can be calculated at the HF, DFT, MP2, or CCSD levels with ab initio Gaussian basis sets that include up to s, p, d, f, g functions for either closed shell or open shell molecules. Running time: The running time varies with the size of the molecule, the size of the ab initio basis set, and the coarseness of the desired grid. The run time can range from a minute or less for water to 15 minutes for neopentane.

Elking, Dennis M.; Perera, Lalith; Pedersen, Lee G.

2012-02-01

348

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 ...

349

Chemistry 2321 SPRING 2013 Honors Organic Chemistry II  

E-print Network

Chemistry 2321 SPRING 2013 Honors Organic Chemistry II Instructor: Prof. Matt Sigman, Office HEB: "Organic Chemistry" Janice Smith (3rd addition) Recommended: "Organic Chemistry II as a Second Language. Course Description: This class is the second half of honors organic chemistry. Lecture topics include

Simons, Jack

350

Organic Chemistry Laboratory I Fall 2014 Chemistry 341  

E-print Network

Organic Chemistry Laboratory I 颅 Fall 2014 Chemistry 341 Instructor Office Phone Email Office Hours Organic Chemistry - Gilbert & Martin (5th Ed.) Supplemental Text: Organic Chemistry 颅 McMurry (8th Ed that someone skilled in the art of chemistry could successfully repeat the experiment. 3. Relevant Data (10 Pts

Nickrent, Daniel L.

351

Organic Chemistry Laboratory II Fall 2014 Chemistry 443  

E-print Network

Organic Chemistry Laboratory II 颅 Fall 2014 Chemistry 443 Instructor Office Phone Email Office Organic Chemistry - Gilbert & Martin (5th Ed.) Supplemental Text: Organic Chemistry 颅 McMurry (8th Ed in the art of chemistry could successfully repeat the experiment. 3. Relevant Data (9 Pts.) 4. Results

Nickrent, Daniel L.

352

Organic Chemistry Laboratory II Spring 2014 Chemistry 443  

E-print Network

Organic Chemistry Laboratory II 颅 Spring 2014 Chemistry 443 Instructor Office Phone Email Office Organic Chemistry - Gilbert & Martin (5th Ed.) Supplemental Text: Organic Chemistry 颅 McMurry (7th Ed.) Lectures are Mondays at 3 pm in Neckers 240 and Laboratories are in Neckers 203/205 Textbook website: http://thomsonedu.com/chemistry

Nickrent, Daniel L.

353

Hot spring metagenomics.  

PubMed

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

L髉ez-L髉ez, Olalla; Cerd醤, Mar韆 Esperanza; Gonz醠ez-Siso, Mar韆 Isabel

2013-01-01

354

The hot chocolate effect  

NASA Astrophysics Data System (ADS)

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

Crawford, Frank S.

1982-05-01

355

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

356

The Destruction of Nitric Oxide by Nitrogen Atoms from Plasma Jets: Designing for Thermal Stratification  

Microsoft Academic Search

Following the previous demonstration (Behbahani et al., 1982) that the efficiency of nitrogen plasmas in reducing NO is largely due to N atoms contained in small pockets of very hot gas, the mechanism by which pressure gradients atomize temperature distributions into hot 慸roplets is considered. This leads to substituting a vortex for the magnetic rotation of the arc, simplifying the

HOUSHANG F. BEHBAHANI; ANNE-MARIE WARRIS; FELIX J. WEINBERG

1983-01-01

357

A model of hollow cathode plasma chemistry  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

358

Hot refueling hazards.  

PubMed

Hot refueling in the special operations community has several potential hazards which can accompany the operation. The MC-130 Panel Operator's (PO) position is located in the exhaust of the number 3 engine, subjecting him to fumes, heat, and exhaust blast. The hypothesis was that time constraints should be implemented to the work load due to heat and carbon monoxide exposure. The hypothesis was confirmed for heat exposure but not for significant carbon monoxide exposure. PMID:2496343

Hammer, D L

1989-03-01

359

Quarkonium in Hot Medium  

SciTech Connect

I review recent progress in studying quarkonium properties in hot medium as well as possible consequences for quarkonium production in heavy ion collisions. There has been considerable interest in studying quarkonia in hot medium since the publication of the famous Matsui and Satz paper. It has been argued that color screening in a deconfined QCD medium will suppress the existence of quarkonium states, signaling the formation of a quark-gluon plasma (QGP) in heavy-ion collisions. Although this idea was proposed a long time ago, first principle QCD calculations, which go beyond qualitative arguments, have been performed only recently. Such calculations include lattice QCD determinations of quarkonium correlators; potential model calculations of the quarkonium spectral functions with potentials based on lattice QCD, as well as effective field theory approaches that justify potential models and reveal new medium effects. Spectral properties of heavy quark bound states are important ingredients in modeling of heavy quarkonium production in hot medium as will be discussed later.

Petreczky, P.

2010-08-02

360

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

361

Atom Builder  

NSDL National Science Digital Library

This website allows the user to build their own Carbon Atom out of elementary particles (up quarks, down quarks, and electrons). As protons, neutrons, and electrons are added to the atom, the atom changes from one element to another. From hydrogen the atom changes into helium, then lithium, and on up through the Periodic table until it finally becomes carbon. If, while being built, the balance between protons, neutrons, and electrons is not sufficiently maintained, the atom will either become radioactive and decay, or become so ionized that it will attach itself to a molecule outside the building area. In either case, the user must start over. The activity is over when the atom changes into carbon. Read the guides for assistance.

2010-12-22

362

Matthew F. Tuchler Associate Professor of Chemistry  

E-print Network

TAUGHT Chemistry 110 颅 General Chemistry (as of 2012) Chemistry 111 颅 General Chemistry Chemistry 112Matthew F. Tuchler Associate Professor of Chemistry EMPLOYER: Department of Chemistry, Washington: tuchlerm@wlu.edu EDUCATION: B.A. in Chemistry, Haverford College, 1986 M.A. in Chemistry, University

Marsh, David

363

The Chemistry of Cocaine  

NSDL National Science Digital Library

This case study on the chemistry of cocaine is in the form of a classroom discussion between a professor and her students about cocaine, its addictive properties, a search for an addiction treatment, and the chemistry involved in the synthesis of cocaine in its various forms. The case can be used to teach nucleophilic addition reactions, nucleophilic acyl substitution, and cocaine metabolism. In addition, it provides students with experience in locating, reading, and analyzing a research paper. The case was designed for the second course in a two-course sequence in undergraduate organic chemistry, but it could be adapted for medicinal chemistry classes.

Brahmadeo Dewprashad

2010-01-01

364

Atmospheric Chemistry (Program Description)  

NSF Publications Database

... of Atmospheric Sciences Atmospheric Chemistry Description Supports research to measure and ... on the chemical reactions among atmospheric species; the sources and sinks of important trace gases ...

365

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

ERIC Educational Resources Information Center

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

Buffaloe, Jacquelin F.

366

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

367

Teaching Assistants Department of Chemistry  

E-print Network

to familiarize you with your teaching responsibilities for General Chemistry and Organic Chemistry and to provideGuide for Teaching Assistants Department of Chemistry The University of Chicago #12;漏 2012 Department of Chemistry, The University of Chicago (2nd edition) #12;i Preface Welcome to the Chemistry

He, Chuan

368

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梩hat 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

369

The Deceptive Difficulty of Descriptive Chemistry and the Chemistry Curriculum.  

ERIC Educational Resources Information Center

Suggesting that descriptive chemistry is basic to basic chemical literacy, offers examples of descriptive chemistry problems (with answers) based on inexpensive, short, safe, striking, and simple lecture experiments. Issues related to the teaching of descriptive chemistry are also addressed. (JN)

Bent, Henry A.

1984-01-01

370

Atomic oxygen testing with thermal atom systems - A critical evaluation  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

371

Chemistry of detonation soot: Diamonds, graphite, and volatiles  

SciTech Connect

Detonation of a number of pure and composite explosives in tanks filled with Ar gas have yielded solid carbonaceous products (soots) with a rich chemistry. Although there are similarities, the soot from each explosive has some uniqueness. The soot are composed of very small solid particles of graphite and often diamond, having characteristic dimensions of about 20 atomic diameters. This small size and the presence of a 25 wt % heat-labile component implies an important surface chemistry for these soots. The heat-labile compounds may give clues about the structure, the surface chemistry, and the mechanism of soot formation. 17 refs., 3 figs., 1 tab.

Greiner, N.R.; Hermes, R.

1989-01-01

372

SAM: Science of Atoms and Molecules  

NSDL National Science Digital Library

This is the portal for the Concord Consortium's Science of Atoms and Molecules Project (SAM), a collection of field-tested activities designed to integrate biology, chemistry, and physics. Each activity provides guided explorations through simulations and models, all within a framework that builds a foundation for understanding atomic/molecular structure. The collection features four themes: motion and energy, charge, atoms/molecules, and light. The overarching concept that connects all four is that atoms and molecules are the fundamental basis for all interactions. The models are all free to all registered users. Registration allows teachers to set up classroom groups, capture student data, and store student work products. SAM is part of the Concord Consortium, an NSF-supported project that provides a library of "deeply digital" examples to support technology-based curriculum materials. The collection covers a wide range of topics in physics, biology, and chemistry.

2011-05-04

373

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.

374

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

375

Atomic Mobile  

NSDL National Science Digital Library

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

History, American M.

2012-06-26

376

Chemistry Guidelines for Supplemental Funding  

NSF Publications Database

... of Chemistry Under certain circumstances, PIs of grants supported by the Division of Chemistry may ... funding requests in the Division of Chemistry include: replacement or repair of damaged instruments ...

377

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

378

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

379

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.

380

Chemistry of Moth Repellents  

ERIC Educational Resources Information Center

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

Pinto, Gabriel

2005-01-01

381

Rolf Claessen's Chemistry Index  

NSDL National Science Digital Library

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

382

General Chemistry Online  

NSDL National Science Digital Library

This educational site features: A searchable database of over 800 common compound names; Hyperlinked notes for first semester general chemistry; Interactive graphing, popup tables, and calculators; an index of self-guided tutorials, quizzes, and drills on specific topics; a searchable glossary; and a Chemistry Exam Survival Guide

383

Brushing Up on Chemistry.  

ERIC Educational Resources Information Center

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

Trantow, Ashley

2002-01-01

384

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

385

Coupled Phenomena in Chemistry.  

ERIC Educational Resources Information Center

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

Matsubara, Akira; Nomura, Kazuo

1979-01-01

386

Chemistry 365 Useful Information  

E-print Network

Chemistry 365 Quiz II Useful Information kB = 1. 380662 ? 10-16 erg/K h = 6. 6256 ? 10-27 erg sec homonuclear diatomic molecules. Assume that the nuclei have spin 1. March 18, 1994 over... #12;Chemistry 365

Ronis, David M.

387

Stratospheric chemistry and transport  

NASA Technical Reports Server (NTRS)

A Chemical Tracer Model (CTM) that can use wind field data generated by the General Circulation Model (GCM) is developed to implement chemistry in the three dimensional GCM of the middle atmosphere. Initially, chemical tracers with simple first order losses such as N2O are used. Successive models are to incorporate more complex ozone chemistry.

Prather, Michael; Garcia, Maria M.

1990-01-01

388

Selectivity in Analytical Chemistry  

NSDL National Science Digital Library

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

2005-11-01

389

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

390

Silicon chemistry in interstellar clouds  

NASA Technical Reports Server (NTRS)

A new model of interstellar silicon chemistry is presented that explains the lack of SiO detections in cold clouds and 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. As part of the explanation of the lack of SiO detections at low temperatures and densities, the 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 abundance of oxygen bearing molecules and the depletion of interstellar silicon.

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

1990-01-01

391

Hot cell examination table  

DOEpatents

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

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

1991-01-01

392

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.

House, Herbert

2005-01-01

393

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

394

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

395

Korarchaeota Diversity, Biogeography, and Abundance in Yellowstone and Great Basin Hot Springs and  

E-print Network

, Nevada, United States of America, 2 School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, United States of America, 3 Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona, United States of America Abstract Over 100 hot spring sediment samples were

Ahmad, Sajjad

396

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...

397

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

398

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

399

Hot Subdwarf Stars  

NASA Astrophysics Data System (ADS)

Hot subdwarf stars (sdBs, sdOs) are core helium-burning stars at the blue end of the horizontal branch or have evolved even beyond that stage. They are found in all Galactic stellar populations and are sufficiently common to account for the UV-upturn of early-type galaxies. About half of the sdBs reside in close binaries; companions are white dwarfs or low-mass main-sequence stars. Binary population-synthesis models explain naturally the actual sdB binary fractions of field and globular cluster stars as well as of He-sdOs if white-dwarf mergers are considered. Hot helium flashes explain the chemical composition of He-sdOs. Asteroseismology of a dozen pulsating sdB stars allowed determination of their masses and detection of a planet to V391 Peg. The discoveries of an sdO star unbound to the Galaxy, potential SN Ia progenitors and probably a hidden population of neutron stars or black hole companions have great impact on astrophysics at large.

Heber, Ulrich

2009-09-01

400

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

401

Microstructure Evolution of Gas Atomized Iron Based ODS Alloys  

SciTech Connect

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

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

2011-08-09

402

Experimental investigation and computational modeling of hot filament diamond chemical vapor deposition  

NASA Astrophysics Data System (ADS)

A joint investigation has been undertaken of the gas-phase chemistry taking place in a hot-filament chemical vapor-deposition (HFCVD) process for diamond synthesis on silica surfaces by a detailed comparison of numerical modeling and experimental results. Molecular beam sampling using quadrupole mass spectroscopy and resonance-enhanced multiphoton ionization time of flight mass spectroscopy (REMPI-TOF-MS) has been used to determine absolute concentrations of stable hydrocarbons and radicals. Resulting species of a CH4/H2, a CH4/D2 (both 0.5%/99.5%) and a C2H2/H2 (0.25%/99.75%) feedgas mixture were investigated for varying filament and substrate temperatures. Spatially resolved temperature profiles at various substrate temperatures, obtained from coherent anti-Stokes Raman spectroscopy (CARS) of hydrogen, are used as input parameters for the numerical code to reproduce hydrogen atom, methyl radical, methane, acetylene, and ethylene concentration profiles in the boundary layer of the substrate. In addition, the concentration of vibrationally excited hydrogen is determined by CARS. Results reveal only qualitative agreement between measured data and simulations, concerning concentrations of stable species and radicals probed near the surface, on filament and substrate temperature dependence, respectively. Hydrogen and deuterium experiments show similar behaviour for all species. In the case of CH4 as feedgas the model describes measured concentration profiles of CH3, CH4, and C2H2 qualitatively well. Large differences between model and experiment occur for hydrogen atoms (factor of 2) and C2H4 (factor of 3). For acetylene as feedgas the model is not able to give any predictions because no conversion of C2H2 is seen in the model in contrast to the experiment.

Zumbach, Volker; Sch鋐er, J鰎g; Tobai, Jens; Ridder, Michael; Dreier, Thomas; Schaich, Thomas; Wolfrum, J黵gen; Ruf, Bernhard; Behrendt, Frank; Deutschman, Olaf; Warnatz, J黵gen

1997-10-01

403

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

404

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

SciTech Connect

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

Not Available

1981-09-01

405

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

406

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

407

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

408

Full of Hot Air: Hot Air Balloon Building  

NSDL National Science Digital Library

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

Houston, Children'S M.

2010-01-01

409

Surface Chemistry Research  

NSDL National Science Digital Library

This Topic in Depth explores the field of surface chemistry. First, the American Chemical Society's (ACS) Division of Colloid and Surface Chemistry publicizes its members initiatives to "investigate the interaction of surfaces with fluids having molecular densities spanning the range from liquids to ultra-high vacuum" (1). Researchers can find out about upcoming meetings, awards, and membership opportunities. The second website presents Chalmers University of Technology's research activities in surfactants and microemulsions, environmental catalysis, fuels engineering, and metal working chemistry (2). Students and teachers can discover the basics of surface chemistry and its benefits to society. Next, University of Canterbury features its studies which "help in the development of portable devices in freshwater analysis, microelectrodes, chemically modified electrodes & biochips for sensors, nanoparticle assemblies for smart materials, [and] novel electrode material for catalysis of industrial processes" (3). Users can view posters detailing their research as well as articles describing the group's latest news and results. Fourth, the US Naval Research Lab describes its surface chemistry research interests, facilities, and its strengths (4). Individuals can find lists of the Lab's journal articles, reports, and technical papers. The fifth website, provided by the University of Virginia, addresses how the chemistry of aerogels makes them "attractive materials for use as catalysts, catalyst substrates, and adsorbents" (5). The website contains illustrations of the interaction between water and aerogel compounds. Sixth, the Environmental Molecular Sciences Laboratory presents its Ultra-high Vacuum (UHV) Surface Chemistry-High-Resolution Electron Energy Loss Spectroscopy (HREELS) System capabilities to "study the molecular-level chemistry of adsorbates on metal oxide surfaces" (6 ). The website offers a concise overview of sample preparation, handling, and manipulation. Lastly, the University of Michigan provides links to in-depth discussions and informational images of the research projects of its four surface chemistry research groups (7). Researchers can find slide show presentations of the group's work, lists of its publications, and information on the individual researchers' education and work. [RME

410

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爊m) 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牥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

411

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

PubMed

The surface properties of the plant cuticle play a crucial role in plant-pathogen interactions and the retention and penetration of agriculturally important chemicals. This paper describes the use of X-ray photoelectron spectroscopy (XPS), time-of-flight secondary-ion mass spectrometry (ToF-SIMS), tapping-mode atomic force microscopy (TM-AFM) and scanning electron microscopy (SEM) to determine surface-specific chemical and material properties of the adaxial surface of Prunus laurocerasus L. leaves. XPS data, derived from the uppermost few nanometres (< 10 nm) of the leaf surface, were consistent with the wax components and functionality known to be present within the waxes. ToF-SIMS provided molecular speciation from the outermost monolayer of the leaf surface, indicating the importance of a family of acetates with chain lengths ranging from C20 to C34. The presence of alkanes with C29 and C31 chain lengths was also confirmed. SEM and TM-AFM topography images revealed a textured granular surface, while simultaneously recorded AFM phase images revealed heterogeneous material properties at the nanoscale. The relevance of these data to plant cuticle development, allelochemistry and agrochemical delivery is discussed. PMID:15565289

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

2005-04-01

412

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

413

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

414

Organic Chemistry Laboratory I Spring 2014 Chemistry 341  

E-print Network

Organic Chemistry Laboratory I 颅 Spring 2014 Chemistry 341 Instructor Office Phone Email Office Text: Experimental Organic Chemistry - Gilbert & Martin (5th Ed.) Supplemental Text: (Chem. 340) Organic Chemistry 颅 McMurry (7th Ed.) Lectures are Mondays at 4 pm in Neckers 240 and Laboratories

Nickrent, Daniel L.

415

ORGANIC CHEMISTRY I: CHEMISTRY 360 SYLLABUS SPRING 2014  

E-print Network

ORGANIC CHEMISTRY I: CHEMISTRY 360 SYLLABUS SPRING 2014 Classroom: SL104 Dr. Craig P. Jasperse of Carey's Organic Chemistry as used at NDSU, contact me in order to use what you have.) 2) Solutions Manual: "Solutions Manual, Organic Chemistry, 6th Edition OR 7th edition", by Simek, Wade Note

Jasperse, Craig P.

416

Legendre Functions Quantum Chemistry: Chemistry 180-345A  

E-print Network

Legendre Functions Quantum Chemistry: Chemistry 180-345A In class we showed that the the angular Fall 2003 #12;Quantum Chemistry -2- Chemistry 180-345A which is divergent at x = 卤1 (i.e., at = 0 to normalize the wavefunction. Finally, returning to the more general case of m 0 we simply note

Ronis, David M.

417

CHEMISTRY 243: Introductory Physical Chemistry II. General Information  

E-print Network

CHEMISTRY 243: Introductory Physical Chemistry II. General Information Lectures: Monday & Wednesday, Inc., 2006) J.R. Barrante, Applied Mathematics for Physical Chemistry, 3rd edition (Pearson Education, Inc., 2004) Supplementary Texts 1. G. W. Castellan, Physical Chemistry 3rd edition (Benjamin Cummings

Ronis, David M.

418

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

419

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

420

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.

421

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.

422

Linux4Chemistry  

NSDL National Science Digital Library

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

Kuznik, Nikodem.

2005-11-02

423

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

424

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

425

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

426

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.

427

Pittsburgh conference 1989 and exposition on analytical chemistry and applied spectroscopy (Abstracts)  

SciTech Connect

This book covers the proceedings of the 1989 Pittsburgh Conference and Exposition on Analytical Chemistry and Applied Spectroscopy. Some of the topics presented at the conference include the following: atomic spectroscopy; bioanalysis and life sciences; molecular spectroscopy; electroanalytical chemistry and gas chromotography.

Not Available

1989-01-01

428

Rutherford Atom  

Microsoft Academic Search

The identification of the 揷orpuscle (later renamed ? 揺lectron) by J.J. Thomson (18561940) in 1897 inspired the design\\u000a of atomic models by the British school of mechanistic physics. The obvious initial assumption, based on relative weights,\\u000a was that atoms consisted of thousands of elementary particles whose measured ratio of charge to mass (e\\/m) was about 2000 times that of the

J. L. Heilbron

429

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

430

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

431

TRUEX hot demonstration  

SciTech Connect

In FY 1987, a program was initiated to demonstrate technology for recovering transuranic (TRU) elements from defense wastes. This hot demonstration was to be carried out with solution from the dissolution of irradiated fuels. This recovery would be accomplished with both PUREX and TRUEX solvent extraction processes. Work planned for this program included preparation of a shielded-cell facility for the receipt and storage of spent fuel from commercial power reactors, dissolution of this fuel, operation of a PUREX process to produce specific feeds for the TRUEX process, operation of a TRUEX process to remove residual actinide elements from PUREX process raffinates, and processing and disposal of waste and product streams. This report documents the work completed in planning and starting up this program. It is meant to serve as a guide for anyone planning similar demonstrations of TRUEX or other solvent extraction processing in a shielded-cell facility.

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

1990-04-01

432

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

433

Energetic Metastable Oxygen and Nitrogen Atoms in the Terrestrial Atmosphere  

NASA Technical Reports Server (NTRS)

We have investigated the energy distributions of the metastable oxygen atoms in the terrestrial thermosphere. Nascent O(lD) atoms play a fundamental role in the energy balance and chemistry of the terrestrial atmosphere, because they are produced by photo-chemical reactions in the excited electronic states and carry significant translational energies.

Kharchenko, Vasili

2003-01-01

434

A feature-based approach to modeling protein-protein interaction hot spots.  

PubMed

Identifying features that effectively represent the energetic contribution of an individual interface residue to the interactions between proteins remains problematic. Here, we present several new features and show that they are more effective than conventional features. By combining the proposed features with conventional features, we develop a predictive model for interaction hot spots. Initially, 54 multifaceted features, composed of different levels of information including structure, sequence and molecular interaction information, are quantified. Then, to identify the best subset of features for predicting hot spots, feature selection is performed using a decision tree. Based on the selected features, a predictive model for hot spots is created using support vector machine (SVM) and tested on an independent test set. Our model shows better overall predictive accuracy than previous methods such as the alanine scanning methods Robetta and FOLDEF, and the knowledge-based method KFC. Subsequent analysis yields several findings about hot spots. As expected, hot spots have a larger relative surface area burial and are more hydrophobic than other residues. Unexpectedly, however, residue conservation displays a rather complicated tendency depending on the types of protein complexes, indicating that this feature is not good for identifying hot spots. Of the selected features, the weighted atomic packing density, relative surface area burial and weighted hydrophobicity are the top 3, with the weighted atomic packing density proving to be the most effective feature for predicting hot spots. Notably, we find that hot spots are closely related to pi-related interactions, especially pi . . . pi interactions. PMID:19273533

Cho, Kyu-il; Kim, Dongsup; Lee, Doheon

2009-05-01

435

Circuit hot electron effect simulation  

Microsoft Academic Search

Hot electron effects resulting from high electric fields in submicron devices can severely degrade device characteristics. As a result, severe performance degradation can occur at the circuit level. No simulator exists to predict this effect. The purpose of this paper is to present circuit hot electron effect simulation using our recently developed simulator. As a result, a circuit performance degradation

S. Aur; D. E. Hocevar; Ping Yang

1987-01-01

436

Spectral Modeling Hot Star Winds  

E-print Network

Spectral Modeling of X-Rays from Hot Star Winds Emma Wollman Advisor: David Cohen #12;Hot Stars 路路 Short-livedShort-lived (~ 1-10 million yrs)(~ 1-10 million yrs) #12;Stellar Winds 路 Net momentum 路 More luminosity !"stronger wind 路 Mass-loss rate determines the fate of the star #12;X-ray Production

Cohen, David

437

Hot hollow cathode gun assembly  

DOEpatents

A hot hollow cathode deposition gun assembly includes a hollow body having a cylindrical outer surface and an end plate for holding an adjustable heat sink, the hot hollow cathode gun, two magnets for steering the plasma from the gun into a crucible on the heat sink, and a shutter for selectively covering and uncovering the crucible.

Zeren, J.D.

1983-11-22

438

Mammoth Hot Springs Online Tour  

NSDL National Science Digital Library

This Yellowstone National Park website offers an online tour of the Mammoth Hot Springs. Prominent hot springs and terraces are highlighted with photos and information concerning their cycles of activity. Similar tours of the Old Faithful area, the Norris Geyser Basin, the Fountain Paint Pots, and the Grand Canyon of Yellowstone are also available online.

Park, Yellowstone N.

439

SOURCE ASSESSMENT: ASPHALT HOT MIX  

EPA Science Inventory

This report summarizes data on air emissions from the asphalt hot mix industry. A representative asphalt hot mix plant was defined, based on the results of an industrial survey, to assess the severity of emissions from this industry. Source severity was defined as the ratio of th...

440

Student Orientation Guide Organic Chemistry  

E-print Network

Student Orientation Guide CHEM N3AL Organic Chemistry June 22-August 14, 2015 Organic Chemistry Understanding the Principles of Organic Chemistry, A Laboratory Experience by Steven F. Pedersen and Arlyn M. Myers. (ISBN: 9781111428167) Organic Chemistry Laboratory Notebook, by Steven F. Pedersen, Jesse H

Rubin, Yoram

441

CHEMISTRY 324W ORGANIC LABORATORY  

E-print Network

1 Fall 2010 CHEMISTRY 324W ORGANIC LABORATORY Course Information Title: Chemistry 324W, Organic a scientific paper consistent with the format of the Journal of Organic Chemistry, American Chemical Society. 7 of Organic Chemistry format. #12;2 Experiment sources: While the text for this course is an excellent guide

Wagner, Diane

442

ORGANIC CHEMISTRY II Spring 2012  

E-print Network

CHE 325 ORGANIC CHEMISTRY II Spring 2012 Instructor: Professor James Kallmerten 4-014A Center: Carey and Giuliano, "Organic Chemistry" 8th Edition "Solutions Manual for Organic Chemistry" Molecular of a two-semester sequence presenting a foundational introduction to the science of organic chemistry

Raina, Ramesh

443

Chemistry Wrap Up  

NSDL National Science Digital Library

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

Jeffrey M. Pristera

2000-04-01

444

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

445

Physical Chemistry Animation Index  

NSDL National Science Digital Library

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

446

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

447

Computer Aided CHEmistry (CAChe)  

NSDL National Science Digital Library

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

448

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

449

The Chemistry Hypermedia Project  

NSDL National Science Digital Library

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

1996-01-01

450

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

451

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

452

Chemistry Laboratory Safety Check  

ERIC Educational Resources Information Center

An accident prevention/safety check list for chemistry laboratories is printed. Included are checks of equipment, facilities, storage and handling of chemicals, laboratory procedures, instruction procedures, and items to be excluded from chemical laboratories. (SL)

Patnoe, Richard L.

1976-01-01

453

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.

454

Darwinian evolution and chemistry  

Microsoft Academic Search

Some significant results are collected with a view to ascertain whether a Darwinian chemical evolution is at work in chemistry\\u000a and, if so, to define its specific characters. To this aim prebiotic chemistry, homochirality; chemical reactions and emergence\\u000a of new properties are considered. The Darwinian process of mutation by chance, selection and replication appears to translate\\u000a into chemical exploration of

Gian Paolo Chiusoli

2009-01-01

455

Nicotine Smoke Chemistry  

NSDL National Science Digital Library

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

456

NASA: Aura Atmospheric Chemistry  

NSDL National Science Digital Library

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

457

EPA Environmental Chemistry Laboratory  

NASA Technical Reports Server (NTRS)

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

1993-01-01

458

Impact of surface chemistry  

PubMed Central

The applications of molecular surface chemistry in heterogeneous catalyst technology, semiconductor-based technology, medical technology, anticorrosion and lubricant technology, and nanotechnology are highlighted in this perspective. The evolution of surface chemistry at the molecular level is reviewed, and the key roles of surface instrumentation developments for in situ studies of the gas杝olid, liquid杝olid, and solid杝olid interfaces under reaction conditions are emphasized. PMID:20880833

Somorjai, Gabor A.; Li, Yimin

2011-01-01

459

CHM 1050, Section 02 Honors General Chemistry I  

E-print Network

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

Zakarian, Armen

460

Updated January 2014 Summary of Chemistry Degree Requirements  

E-print Network

Physical Chemistry Lab 417 418 419 Instrumental Analysis 429 Related Science Requirements:1 (35 - 38 to study reaction mechanisms, kinetic analysis, isotope effects, and qualitative molecular orbital theory) The principles of time-independent quantum mechanics and their application to model atomic and molecular systems

Richmond, Geraldine L.

461

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

462

Keep It Cool in Hot Weather  

MedlinePLUS

... in the Summer Sun Keep it Cool in Hot Weather Keep it Cool in Hot Weather Advice for Older People Applies to All ... factors that can increase risk include an extremely hot home, lack of transportation, overdressing and visiting overcrowded ...

463

Hot Plate-Magnetic Stirrer (ChemPages Lab)  

NSDL National Science Digital Library

Hot Plate/Magnetic Stirrer: this is a resource in the collection "ChemPages Laboratory Resources". The hotplate/magnetic stirrer is a single device that can heat liquids and stir them with a magnetic stir bar. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.

464

Hot oxygen and carbon escape from the martian atmosphere  

NASA Astrophysics Data System (ADS)

The escape of hot O and C atoms from the present martian atmosphere during low and high solar activity conditions has been studied with a Monte-Carlo model. The model includes the initial energy distribution of hot atoms, elastic, inelastic, and quenching collisions between the suprathermal atoms and the ambient cooler neutral atmosphere, and applies energy dependent total and differential cross sections for the determination of the collision probability and the scattering angles. The results yield a total loss rate of hot oxygen of 2.3-2.91025 s-1 during low and high solar activity conditions and is mainly due to dissociative recombination of O2+ and CO2+. The total loss rates of carbon are found to be 0.8 and 3.21024 s-1 for low and high solar activity, respectively, with photodissociation of CO being the main source. Depending on solar activity, the obtained carbon loss rates are up to ~40 times higher than the CO2+ ion loss rate inferred from Mars Express ASPERA-3 observations. Finally, collisional effects above the exobase reduce the escape rates by about 20-30% with respect to a collionless exophere.

Gr鰈ler, H.; Lichtenegger, H.; Lammer, H.; Shematovich, V. I.

2014-08-01

465

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

466

Atom Interferometry  

SciTech Connect

Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton抯 constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

Mark Kasevich

2008-05-07

467

Atom Interferometry  

SciTech Connect

Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton's constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gyroscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be used to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

Kasevich, Mark (Stanford University) [Stanford University

2008-05-08

468

Prof. Tom Ziegler -Department of Chemistry University of Calgary-Calgary,Alberta,Canada T2N 1N4  

E-print Network

.00 pm. #12;400 b.c. John Dalton (1766 - 1844 ) Early Atomic Theory #12;"We are perhaps not far removed to the spirit of chemistry. - A. Comte, Philosophie Positive, 1830. #12;Atomic Theory Nield Bohr (1885 Quantum Wave-Mechanics Hartree Atomic Theory R.K.Mullikan Molecular Orbital theory Some too good

Ziegler, Tom

469

H? Absorption by Hot Jupiter Atmospheres  

NASA Astrophysics Data System (ADS)

While the investigation of the hydrogen content of Hot Jupiter outflows is primarily done through observed Lyman-? absorption during transit. The observation by Jensen et al. of H? absorption by the atmospheres of HD189733b and HD209458b offers a complementary probe of the hydrogen content of hot Jupiter atmospheres. Motivated by this observation, we have developed a model of a hydrostatic atmosphere in thermal and photoionization equilibrium in order to better understand the HD189733b detection. The n=2 level population is calculated by balancing collisional and radiative processes. The H? absorption signal is primarily due to metastable 2s hydrogen found in the neutral atomic layer where its abundance varies slowly with radius despite the total hydrogen abundance decreasing exponentially. The 2s hydrogen is primarily formed through collisional excitation from the ground state and is subsequently destroyed by collisional transitions to the 2p state followed by rapid radiative de-excitation With an enhanced ionization rate, the model can approximately reproduce the HD189733b H? transit depths.

Christie, Duncan; Arras, Phil; Li, Zhi-Yun

2014-11-01

470

Chemistry Student Handbook College of Science  

E-print Network

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

Hickman, Mark

471

Hot-Jupiters and hot-Neptunes: a common origin?  

E-print Network

We compare evolutionary models for close-in exoplanets coupling irradiation and evaporation due respectively to the thermal and high energy flux of the parent star with observations of recently discovered new transiting planets. The models provide an overall good agreement with observations, although at the very limit of the quoted error bars of OGLE-TR-10, depending on its age. Using the same general theory, we show that the three recently detected hot-Neptune planets (GJ436, $\\rho$ Cancri, $\\mu$ Ara) may originate from more massive gas giants which have undergone significant evaporation. We thus suggest that hot-Neptunes and hot-Jupiters may share the same origin and evolution history. Our scenario provides testable predictions in terms of the mass-radius relationships of these hot-Neptunes.

I. Baraffe; G. Chabrier; T. S. Barman; F. Selsis; F. Allard; P. H. Hauschildt

2005-05-03

472

Neptune's 'Hot' South Pole  

NASA Technical Reports Server (NTRS)

These thermal images show a 'hot' south pole on the planet Neptune. These warmer temperatures provide an avenue for methane to escape out of the deep atmosphere.

The images were obtained with the Very Large Telescope in Chile, using an imager/spectrometer for mid-infrared wavelengths on Sept. 1 and 2, 2006. The telescope is operated by the European Organization for Astronomical Research in the Southern Hemisphere (known as ESO).

Scientists say Neptune's south pole is 'hotter' than anywhere else on the planet by about 10 degrees Celsius (50 degrees Fahrenheit). The average temperature on Neptune is about minus 200 degrees Celsius (minus 392 degrees Fahrenheit).

The upper left image samples temperatures near the top of Neptune's troposphere (near 100 millibar pressure, which is one-tenth the Earth atmospheric pressure at sea level). The hottest temperatures are indicated at the lower part of the image, at Neptune's south pole (see the graphic at the upper right). The lower two images, taken 6.3 hours apart, sample temperatures at higher altitudes in Neptune's stratosphere. They do show generally warmer temperatures near, but not at, the south pole. They also show a distinct warm area which can be seen in the lower left image and rotated completely around the back of the planet and returned to the earth-facing hemisphere in the lower right image.

2007-01-01

473

Solutions for Hot Situations  

NASA Technical Reports Server (NTRS)

From the company that brought the world an integral heating and cooling food service system after originally developing it for NASA's Apollo Program, comes yet another orbital offshoot: a product that can be as thin as paper and as strong as steel. Nextel Ceramic Textiles and Composites from 3M Company offer space-age protection and innovative solutions for hot situations, ranging from NASA to NASCAR. With superior thermal protection, Nextel fabrics, tape, and sleevings outperform other high temperature textiles such as aramids, carbon, glass, and quartz, permitting engineers and manufacturers to handle applications up to 2,500 F (1,371 C). The stiffness and strength of Nextel Continuous Ceramic Fibers make them a great match for improving the rigidity of aluminum in metal matrix composites. Moreover, the fibers demonstrate low shrinkage at operating temperatures, which allow for the manufacturing of a dimensionally stable product. These novel fibers also offer excellent chemical resistance, low thermal conductivity, thermal shock resistance, low porosity, and unique electrical properties.

2003-01-01

474

Hot Spot Cosmic Accelerators  

NASA Astrophysics Data System (ADS)

The Universe is a violent place - as astronomers use increasingly sensitive means and methods to study the diverse processes out there, they become aware of the extraordinary forces acting in the space that surrounds us. With larger telescopes and ever-more sophisticated instruments, new information is gained about remote celestial objects and their behaviour. Among the most intriguing ones are the radio galaxies which emit prodiguous amounts of energy, in the form of fast-moving particles and intense electromagnetic radiation. One of these is known as 3C 445 ; it is located near the celestial equator within the zodiacal constellation Aquarius (The Waterman), at a distance of about 1 billion light-years. It most probably harbours a black hole at its centre, more massive than the one at the centre of our own galaxy, the Milky Way ( ESO PR 19/02 ). This galaxy was first observed from Cambridge (United Kingdom) in the 1950's and was listed as radio source no. 445 in the Third Cambridge Catalogue (1959), hence the name. Later observations revealed a strong outflow from this galaxy's active centre, visible on radio maps as two opposite plasma jets with strong synchrotron radiation ( [2]) originating from rapidly moving electrons in the associated magnetic field (image "a" in PR Photo 26/02 ). Now, a trio of European astronomers [1] have used two advanced instruments, ISAAC and FORS1 on the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory (Chile) to obtain near-infrared images of these jets (images "b" and "c" in PR Photo 26/02 ). As can be clearly seen on the radio picture of 3C 445 obtained with the NRAO Very Large Array (VLA) radio facility ("a"), the plasma jets of fast particles emanating from the galaxy ram into the surrounding intergalactic medium (mostly primordial hydrogen), thereby producing two "shocks" , both at a distance of approximately 1.5 million light-years from the central galaxy and with particularly strong synchrotron emission. With a total length of more than 3 million light-years, or no less than one-and-a-half times the distance from the Milky Way to the Andromeda galaxy, this structure is indeed gigantic. The region where the jets collide with the intergalactic medium are known as " hot spots ". Superposing the intensity contours of the radio emission from the southern "hot spot" on a near-infrared J-band (wavelength 1.25 祄) VLT ISAAC image ("b") shows three distinct emitting areas; they are even better visible on the I-band (0.9 祄) FORS1 image ("c"). This emission is obviously associated with the shock front visible on the radio image. This is one of the first times it has been possible to obtain an optical/near-IR image of synchrotron emission from such an intergalactic shock and, thanks to the sensitivity and image sharpness of the VLT, the most detailed view of its kind so far . The central area (with the strongest emission) is where the plasma jet from the galaxy centre hits the intergalactic medium. The light from the two other "knots", some 10 - 15,000 light-years away from the central "hot spot", is also interpreted as synchrotron emission. However, in view of the large distance, the astronomers are convinced that it must be caused by electrons accelerated in secondary processes at those sites . The new images thus confirm that electrons are being continuously accelerated in these "knots" - hence called "cosmic accelerators" - far from the galaxy and the main jets, and in nearly empty space. The exact physical circumstances of this effect are not well known and will be the subject of further investigations. The present VLT-images of the "hot spots" near 3C 445 may not have the same public appeal as some of those beautiful images that have been produced by the same instruments during the past years. But they are not less valuable - their unusual importance is of a different kind, as they now herald the advent of fundamentally new insights into the

2002-11-01

475

Hot Hydrogen Test Facility  

SciTech Connect

The core in a nuclear thermal rocket will operate at high temperatures and in hydrogen. One of the important parameters in evaluating the performance of a nuclear thermal rocket is specific impulse, ISP. This quantity is proportional to the square root of the propellant's absolute temperature and inversely proportional to square root of its molecular weight. Therefore, high temperature hydrogen is a favored propellant of nuclear thermal rocket designers. Previous work has shown that one of the life-limiting phenomena for thermal rocket nuclear cores is mass loss of fuel to flowing hydrogen at high temperatures. The hot hydrogen test facility located at the Idaho National Lab (INL) is designed to test suitability of different core materials in 2500 deg. C hydrogen flowing at 1500 liters per minute. The facility is intended to test low activity uranium containing materials but is also suited for testing cladding and coating materials. In this first installment the facility is described. Automated data acquisition, flow and temperature control, vessel compatibility with various core geometries and overall capabilities are discussed.

Swank, W. David; Carmack, Jon; Werner, James E.; Pink, Robert J.; Haggard, DeLon C.; Johnson, Ryan [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415 (United States)

2007-01-30

476

Frontiers in Atmospheric Chemistry Modelling  

NASA Astrophysics Data System (ADS)

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

Colette, Augustin; Bessagnet, Bertrand; Meleux, Frederik; Rou飈, Laurence

2013-04-01

477

Atomic Spectra  

NSDL National Science Digital Library

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

478

Atomic Structure  

Microsoft Academic Search

Data obtained from the Rutherford scattering experiment are used to present a simple picture of the structure of the atom. This picture is shown to be in agreement with the experimental findings on the electrical nature of matter. On the assumption that the particles which make up the nucleus (neucleons) are neutrons and protons, a \\

R. E. Lapp; H. L. Andrews

1948-01-01

479

Not so hot "hot spots" in the oceanic mantle.  

PubMed

Excess volcanism and crustal swelling associated with hot spots are generally attributed to thermal plumes upwelling from the mantle. This concept has been tested in the portion of the Mid-Atlantic Ridge between 34 degrees and 45 degrees (Azores hot spot). Peridotite and basalt data indicate that the upper mantle in the hot spot has undergone a high degree of melting relative to the mantle elsewhere in the North Atlantic. However, application of various geothermometers suggests that the temperature of equilibration of peridotites in the mantle was lower, or at least not higher, in the hot spot than elsewhere. The presence of H(2)O-rich metasomatized mantle domains, inferred from peridotite and basalt data, would lower the melting temperature of the hot spot mantle and thereby reconcile its high degree ofmelting with the lack of a mantle temperature anomaly. Thus, some so-called hot spots might be melting anomalies unrelated to abnormally high mantle temperature or thermal plumes. PMID:17808242

Bonath, E

1990-10-01

480

Chemistry Under Extreme Conditions  

NASA Astrophysics Data System (ADS)

It has long been recognized that shock compression of condensed matter can generate chemical reactions. The best-known examples of this are the reactions that release energy during the detonation of a high explosive. Despite this, very little is known about molecular processes occurring behind the shock front in a condensed phase. I will describe a domain of ``extreme chemistry'' that is of particular interest and relevance. Extreme chemistry occurs when temperatures are comparable to molecular bond energies, and when molecular bond energies are strongly modified by pressure. In this region the notions of conventional chemistry must be completely rethought. I will review extreme chemistry in several contexts: the reactions of shocked liquids and plastics, reactions of detonating high explosives, and reactions under static compression. In the area of shocked liquids and plastics, I will ask whether traditional shock Hugoniot measurements can provide any information on underlying chemistry. For high explosives, I will discuss the nature of reactions at the Chapman-Jouget state. Finally, I will discuss the discovery of a novel superionic phase of water and a symmetric hydrogen bonded phase of formic acid under static compression. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

Fried, Laurence

2005-07-01

481

Stationary light in cold atomic gases  

E-print Network

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

Gor Nikoghosyan; Michael Fleischhauer

2009-09-16

482

Dear Colleague Letter on Cyber-Enabled Chemistry  

NSF Publications Database

... to the Division of Chemistry relevant to cyber-enabled chemistry Dear Colleague: The National ... Chemistry; Inorganic, Bioinorganic & Organometallic Chemistry; Organic & Macromolecular Chemistry ...

483

Interactive Chemistry Journey (by Steven D. Gammon, Lynn Hunsberger, Sharon Hutchison)  

NASA Astrophysics Data System (ADS)

Prentice Hall: Upper Saddle River, NJ, 1997. CD-ROM (Hybrid, MAC and WIN). ISBN 013 548116-3. 26.25 purchased separately; 10.00 when purchased with Prentice Hall Textbook. Interactive Chemistry Journey is a single CD-ROM packed with excellent chemistry content. Every topic that would be covered in high school chemistry and first-year college chemistry is well represented: basic skills, energy and matter, atomic structure, molecular structure, gases, kinetics, and equilibrium. Each content unit has interactive lessons and problems, including MCAT review questions. Several units have simulations that the student can manipulate to better understand the concepts.

McCool, Debra J.

1998-05-01

484

Atmospheric chemistry of ethyl propionate.  

PubMed

Ethyl propionate is a model for fatty acid ethyl esters used as first-generation biodiesel. The atmospheric chemistry of ethyl propionate was investigated at 980 mbar total pressure. Relative rate measurements in 980 mbar N(2) at 293 0.5 K were used to determine rate constants of k(C(2)H(5)C(O)OC(2)H(5) + Cl) = (3.11 0.35) 10(-11), k(CH(3)CHClC(O)OC(2)H(5) + Cl) = (7.43 0.83) 10(-12), and k(C(2)H(5)C(O)OC(2)H(5) + OH) = (2.14 0.21) 10(-12) cm(3) molecule(-1) s(-1). At 273-313 K, a negative Arrhenius activation energy of -3 kJ mol(-1) is observed.. The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar N(2) gave the following products (stoichiometric yields): ClCH(2)CH(2)C(O)OC(2)H(5) (0.204 0.031), CH(3)CHClC(O)OC(2)H(5) (0.251 0.040), and C(2)H(5)C(O)OCHClCH(3) (0.481 0.088). The chlorine atom-initiated oxidation of ethyl propionate in 980 mbar of N(2)/O(2) (with and without NO(x)) gave the following products: ethyl pyruvate (CH(3)C(O)C(O)OC(2)H(5)), propionic acid (C(2)H(5)C(O)OH), formaldehyde (HCHO), and, in the presence of NO(x), PAN (CH(3)C(O)OONO(2)). The lack of acetaldehyde as a product suggests that the CH(3)CH(O)C(O)OC(2)H(5) radical favors isomerization over decomposition. From the observed product yields, we conclude that H-abstraction by chlorine atoms from ethyl propionate occurs 20.4 3.1%, 25.1 4.0%, and 48.1 8.8% from the CH(3)-, -CH(2)-, and -OCH(2)- groups, respectively. The rate constant and branching ratios for the reaction between ethyl propionate and the OH radical were investigated theoretically using quantum mechanical calculations and transition state theory. The stationary points along the reaction path were optimized using the CCSD(T)-F12/VDZ-F12//BH&HLYP/aug-cc-pVTZ level of theory; this model showed that OH radicals abstract hydrogen atoms primarily from the -OCH(2)- group (80%). PMID:22524192

Andersen, Vibeke F; 豶ns, Kristian B; J鴕gensen, Solvejg; Nielsen, Ole John; Johnson, Matthew S

2012-05-31

485

A de Broglie-Bohr Model for the Hydrogen Atom Frank Rioux  

E-print Network

A de Broglie-Bohr Model for the Hydrogen Atom Frank Rioux Chemistry Department CSB|SJU The 1913 Bohr model of the hydrogen atom was replaced by Schrodinger's wave mechanical model in 1926. However to the nucleus. The de Broglie-Bohr model of the hydrogen atom presented here treats the electron as a particle

Rioux, Frank

486

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

E-print Network

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

Apkarian, V. Ara

487

History of Atomic Theory  

NSDL National Science Digital Library

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

Mcnees, Mrs.

2010-10-26

488

Hot carrier diffusion in graphene  

E-print Network

We report an optical study of charge transport in graphene. Diffusion of hot carriers in epitaxial graphene and reduced graphene oxide samples are studied using an ultrafast pump-probe technique with a high spatial resolution. Spatiotemporal...

Ruzicka, Brian Andrew; Wang, Shuai; Werake, Lalani Kumari; Weintrub, Ben; Loh, Kian Ping; Zhao, Hui

2010-11-01

489

Delivering hot water more economically.  

PubMed

Jonathan Jones, European product manager at Tyco Thermal Controls, explains the economic and other benefits of using electrically trace-heated single pipe distribution, in place of the more "traditional" flow and return system, for hot water supply. PMID:20527595

Jones, Jonathan

2010-05-01

490

Science360: Chemistry  

NSDL National Science Digital Library

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

491

Atmospheric chemistry research  

SciTech Connect

Global environmental changes are occurring all around us, and the energy industry is a major player in the changes that are taking place. Wise energy policy can only be generated from a position of informed enlightenment and understanding about the environmental consequences of energy production and utilization. The atmospheric chemistry research being conducted at the University of Kentucky's Center for Applied Energy Research is geared toward providing the knowledge necessary to allow industrial and legislative officials to make responsible energy decisions in the 1990's and beyond. Three programs are described: the Kentucky Acid Deposition Program Precipitation chemistry network; modeling of regional and urban photochemistry and acid deposition; and modeling of global tropospheric chemistry.

Saylor, R.D. (Center for Applied Energy Research, Lexington, KY (USA))

1990-01-01

492

Practical Chemistry: Nuffield Foundation  

NSDL National Science Digital Library

Young people and others should know about the foundations of modern chemistry and this novel site from the Nuffield Foundation provides a nice mixture of resources to accomplish this goal. The Foundation partnered with the Royal Society of Chemistry (RSC) to create this trove, which visitors will find easy to use and navigate. As the authors describe it, these practical activities are designed to "enable students to apply and extend their knowledge and understanding of chemistry in novel investigative situations." It's important to browse the Topics area, as this contains sections like States of Matter, Bonding, structure, properties, Analysis, Energy and entropy, and The Earth and atmosphere. The great thing about these activities is that they are self-contained, and they require only a modest investment in actual materials and educational background. Finally, the Standard Techniques area will help visitors learn some lab basics, including the heating of various substances, using thermometers properly, and the correct use of a Bunsen burner.

493

Air Composition and Chemistry  

NASA Astrophysics Data System (ADS)

This book is about the atmosphere and humanity's influence on it. For this new edition, Brimblecombe has rewritten and updated much of the book. In the early chapters, he discusses the geochemical, biological and maritime sources of the trace gases. Next, he examines the chemistry of atmospheric gases, suspended particles, and rainfall. After dealing with the natural atmosphere, he examines the sources of air pollution and its effects, with all scenarios updated from the last edition. Scenarios include decline in health, damage to plants and animals, indoor pollution, and acid rain. The final chapters, also revised, are concerned with the chemistry and evolution of the atmospheres of the planets of the solar system. Students with an interest in chemistry and the environmental sciences will find this book highly valuable.

Brimblecombe, Peter

1996-01-01

494

Atomic force microscope mediated chromatography  

NASA Astrophysics Data System (ADS)

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

Anderson, M. S.

2013-02-01

495

Free-electron induced chemistry Theoretical Chemistry Section, BARC, Mumbai  

E-print Network

Free-electron induced chemistry Theoretical Chemistry Section, BARC, Mumbai Chemical reactions in chemical physics and biophysics. The central quantity in the theoretical description of such chemical, I shall present the quantum chemical methodologies for computing the potential energy surfaces

Shyamasundar, R.K.

496

Digital biology and chemistry.  

PubMed

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

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

2014-09-01

497

What Can the Bohr-Sommerfeld Model Show Students of Chemistry in the 21st Century?  

ERIC Educational Resources Information Center

Bohr's model of the atom is considered to be important by general chemistry textbooks. A shortcoming of this model was that it could not explain the spectra of atoms containing more than one electron. To increase the explanatory power of the model, Sommerfeld hypothesized the existence of elliptical orbits. This study aims to elaborate a framework

Niaz, Mansoor; Cardellini, Liberato