Science.gov

Sample records for ion size studied

  1. Conductivity studies of Chitosan doped with different ammonium salts: Effect of ion size

    NASA Astrophysics Data System (ADS)

    Mohan, C. Raja; Senthilkumar, M.; Jayakumar, K.

    2015-06-01

    In the present investigation influence of ion size on the electrical properties of various ammonium salts of various concentrations doped with Chitosan liquid electrolyte has been studied. The attachment of ammonium salts with Chitosan has been confirmed through FTIR Spectrum. Polarizability is calculated from the refractive index data. Addition of ammonium salts increases the conductivity. It is also observed that increase in ion size, increases the ionic conductivity due to increase in amorphous nature of the material. Increase in concentration leads to increase in conductivity due to the presence of more number of free ions.

  2. Ion generation and CPC detection efficiency studies in sub 3-nm size range

    SciTech Connect

    Kangasluoma, J.; Junninen, H.; Sipilae, M.; Kulmala, M.; Petaejae, T.; Lehtipalo, K.; Mikkilae, J.; Vanhanen, J.; Attoui, M.; Worsnop, D.

    2013-05-24

    We studied the chemical composition of commonly used condensation particle counter calibration ions with a mass spectrometer and found that in our calibration setup the negatively charged ammonium sulphate, sodium chloride and tungsten oxide are the least contaminated whereas silver on both positive and negative and the three mentioned earlier in positive mode are contaminated with organics. We report cut-off diameters for Airmodus Particle Size Magnifier (PSM) 1.1, 1.3, 1.4, 1.6 and 1.6-1.8 nm for negative sodium chloride, ammonium sulphate, tungsten oxide, silver and positive organics, respectively. To study the effect of sample relative humidity on detection efficiency of the PSM we used different humidities in the differential mobility analyzer sheath flow and found that with increasing relative humidity also the detection efficiency of the PSM increases.

  3. Study of the Influence Between Barium Ions and Calcium Ions on Morphology and Size of Coprecipitation in Microemulsion

    NASA Astrophysics Data System (ADS)

    Wang, Nong; Meng, Qing Luo

    2015-03-01

    In this paper, we systematically drew a series of inverse-microemulsion quasi-ternary system phase diagrams of OP-10+C8H17OH+C6H12+brine (CaCl2/BaCl2) by adjusting the ratio of CaCl2 and BaCl2. On this basis, microemulsions have been prepared with seven different molar ratios of Ca2+/Ba2+, and calcium carbonate and barium carbonate coprecipitation products were obtained by reaction with an equimolar amount of sodium carbonate. The influence of barium ion to morphology and composition of nanometer calcium carbonate were studied. These samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The SEM photographs indicated that when the content of Ca2+ was higher, some incomplete large cube of coprecipitation particles were formed in solution, but with the content of Ba2+ increased gradually, they formed a large number of small spherical particles, with the further increase of Ba2+ concentration, the particles mainly had structures of irregular polyhedron eventually. The measurement results of FTIR and XRD indicated that CaCO3 coprecipitation products gradually changed from calcite to the vaterite, eventually turned into being aragonite with the further increase of Ba2+ concentration.

  4. In situ TEM studies of micron-sized all-solid-state fluoride ion batteries: Preparation, prospects, and challenges.

    PubMed

    Hammad Fawey, Mohammed; Chakravadhanula, Venkata Sai Kiran; Reddy, Munnangi Anji; Rongeat, Carine; Scherer, Torsten; Hahn, Horst; Fichtner, Maximilian; Kübel, Christian

    2016-07-01

    Trustworthy preparation and contacting of micron-sized batteries is an essential task to enable reliable in situ TEM studies during electrochemical biasing. Some of the challenges and solutions for the preparation of all-solid-state batteries for in situ TEM electrochemical studies are discussed using an optimized focused ion beam (FIB) approach. In particular redeposition, resistivity, porosity of the electrodes/electrolyte and leakage current are addressed. Overcoming these challenges, an all-solid-state fluoride ion battery has been prepared as a model system for in situ TEM electrochemical biasing studies and first results on a Bi/La0.9 Ba0.1 F2.9 half-cell are presented. Microsc. Res. Tech. 79:615-624, 2016. © 2016 Wiley Periodicals, Inc. PMID:27145192

  5. Application of Ion Mobility-Mass Spectrometry to the Study of Ionic Clusters: Investigation of Cluster Ions with Stable Sizes and Compositions

    PubMed Central

    Ohshimo, Keijiro; Komukai, Tatsuya; Takahashi, Tohru; Norimasa, Naoya; Wu, Jenna Wen Ju; Moriyama, Ryoichi; Koyasu, Kiichirou; Misaizu, Fuminori

    2014-01-01

    Stable cluster sizes and compositions have been investigated for cations and anions of ionic bond clusters such as alkali halides and transition metal oxides by ion mobility-mass spectrometry (IM-MS). Usually structural information of ions can be obtained from collision cross sections determined in IM-MS. In addition, we have found that stable ion sizes or compositions were predominantly produced in a total ion mass spectrum, which was constructed from the IM-MS measurement. These stable species were produced as a result of collision induced dissociations of the ions in a drift cell. We have confirmed this result in the sodium fluoride cluster ions, in which cuboid magic number cluster ions were predominantly observed. Next the stable compositions, which were obtained for the oxide systems of the first row transition metals, Ti, Fe, and Co, are characteristic for each of the metal oxide cluster ions. PMID:26819887

  6. Theory of Nanocluster Size Distributions from Ion Beam Synthesis

    SciTech Connect

    Yuan, C.W.; Yi, D.O.; Sharp, I.D.; Shin, S.J.; Liao, C.Y.; Guzman, J.; Ager III, J.W.; Haller, E.E.; Chrzan, D.C.

    2008-06-13

    Ion beam synthesis of nanoclusters is studied via both kinetic Monte Carlo simulations and the self-consistent mean-field solution to a set of coupled rate equations. Both approaches predict the existence of a steady state shape for the cluster size distribution that depends only on a characteristic length determined by the ratio of the effective diffusion coefficient to the ion flux. The average cluster size in the steady state regime is determined by the implanted species/matrix interface energy.

  7. Theory of Nanocluster Size Distributions from Ion Beam Synthesis

    SciTech Connect

    Yuan, C. W.; Yi, D. O.; Shin, S. J.; Liao, C. Y.; Guzman, J.; Haller, E. E.; Chrzan, D. C.; Sharp, I. D.; Ager, J. W. III

    2009-04-10

    Ion beam synthesis of nanoclusters is studied via both kinetic Monte Carlo simulations and the self-consistent mean-field solution to a set of coupled rate equations. Both approaches predict the existence of a steady-state shape for the cluster-size distribution that depends only on a characteristic length determined by the effective diffusion coefficient, the ion solubility, and the volumetric ion flux. The average cluster size in the steady-state regime is determined by the implanted species or matrix interface energy.

  8. Size effects in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Hu-Rong, Yao; Ya-Xia, Yin; Yu-Gao, Guo

    2016-01-01

    Size-related properties of novel lithium battery materials, arising from kinetics, thermodynamics, and newly discovered lithium storage mechanisms, are reviewed. Complementary experimental and computational investigations of the use of the size effects to modify electrodes and electrolytes for lithium ion batteries are enumerated and discussed together. Size differences in the materials in lithium ion batteries lead to a variety of exciting phenomena. Smaller-particle materials with highly connective interfaces and reduced diffusion paths exhibit higher rate performance than the corresponding bulk materials. The thermodynamics is also changed by the higher surface energy of smaller particles, affecting, for example, secondary surface reactions, lattice parameter, voltage, and the phase transformation mechanism. Newly discovered lithium storage mechanisms that result in superior storage capacity are also briefly highlighted. Project supported by the National Natural Science Foundation of China (Grant Nos. 51225204 and 21303222), the Shandong Taishan Scholarship, China, the Ministry of Science and Technology, China (Grant No. 2012CB932900), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA09010000).

  9. Study on size distribution of total aerosol and water-soluble ions during an Asian dust storm event at Jeju Island, Korea.

    PubMed

    Park, S H; Song, C B; Kim, M C; Kwon, S B; Lee, K W

    2004-01-01

    Soil dust particles transported from loess regions of the Asian continent, called Asian dust, highly influences the air quality of north-eastern Asia and the northern Pacific Ocean. In order to investigate the effects of these dust storms on the chemical composition of atmospheric aerosol particles with different size, measurements of size distributions of total aerosol and major ion species were carried out on Jeju Island, Korea during April 2001. Juju Island was chosen for the study because the levels of emissions of anthropogenic air pollutants are very low. A 5-stage cascade impactor was used to sample size-fractionated aerosol particles. Samples were analyzed for major water-soluble ions using Dionex DX-120 ion chromatograph. The average mass concentration of total aerosol was found to be 24.4 and 108.3 microg m(-3) for non-Asian dust and Asian dust periods, respectively. The total aerosol size distribution, measured during the non-Asian dust period, was bimodal, whereas the coarse particles dominated the size distribution of total aerosol during the Asian dust period. It was found that SO4(2-), NH4+ and K+ were mainly distributed in fine particles, while Cl-, NO3-, Na+, Mg2+ and Ca2+ were in coarse particles. Although SO4(2-) was mainly distributed in fine particles, during the Asian dust period, the concentrations in coarse particles were significantly increased. This indicates heterogeneous oxidation of SO2 on wet surfaces of basic soil dust particles. The NH4+ was found to exist as (NH4)2SO4 in fine particles, with a molar ratio of NH4+ to SO4(2-) of 2.37 and 1.52 for non-Asian dust and Asian dust periods, respectively. Taking into account the proximity of the sampling site to the sea, and the observed chloride depletion, coarse mode nitrate, during the non-Asian dust period, is assumed to originate from the reaction of nitric acid with sodium chloride on the surfaces of sea-salt particles although the chloride depletion was not shown to be large enough to

  10. Influence of ion size and charge on osmosis.

    PubMed

    Cannon, James; Kim, Daejoong; Maruyama, Shigeo; Shiomi, Junichiro

    2012-04-12

    Osmosis is fundamental to many processes, such as in the function of biological cells and in industrial desalination to obtain clean drinking water. The choice of solute in industrial applications of osmosis is highly important in maximizing efficiency and minimizing costs. The macroscale process of osmosis originates from the nanoscale properties of the solvent, and therefore an understanding of the mechanisms of how these properties determine osmotic strength can be highly useful. For this reason, we have undertaken molecular dynamics simulations to systematically study the influence of ion size and charge on the strength of osmosis of water through carbon nanotube membranes. Our results show that strong osmosis occurs under optimum conditions of ion placement near the region of high water density near the membrane wall and of maintenance of a strong water hydration shell around the ions. The results in turn allow greater insight into the origin of the strong osmotic strength of real ions such as NaCl. Finally, in terms of practical simulation, we highlight the importance of avoiding size effects that can occur if the simulation cell is too small. PMID:22397596

  11. Influence of ion size and charge on osmosis.

    PubMed

    Cannon, James; Kim, Daejoong; Maruyama, Shigeo; Shiomi, Junichiro

    2012-04-12

    Osmosis is fundamental to many processes, such as in the function of biological cells and in industrial desalination to obtain clean drinking water. The choice of solute in industrial applications of osmosis is highly important in maximizing efficiency and minimizing costs. The macroscale process of osmosis originates from the nanoscale properties of the solvent, and therefore an understanding of the mechanisms of how these properties determine osmotic strength can be highly useful. For this reason, we have undertaken molecular dynamics simulations to systematically study the influence of ion size and charge on the strength of osmosis of water through carbon nanotube membranes. Our results show that strong osmosis occurs under optimum conditions of ion placement near the region of high water density near the membrane wall and of maintenance of a strong water hydration shell around the ions. The results in turn allow greater insight into the origin of the strong osmotic strength of real ions such as NaCl. Finally, in terms of practical simulation, we highlight the importance of avoiding size effects that can occur if the simulation cell is too small.

  12. Hofmeister effects: interplay of hydration, nonelectrostatic potentials, and ion size.

    PubMed

    Parsons, Drew F; Boström, Mathias; Lo Nostro, Pierandrea; Ninham, Barry W

    2011-07-21

    The classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloids, and corresponding theories of electrolytes, are unable to explain ion specific forces between colloidal particles quantitatively. The same is true generally, for surfactant aggregates, lipids, proteins, for zeta and membrane potentials and in adsorption phenomena. Even with fitting parameters the theory is not predictive. The classical theories of interactions begin with continuum solvent electrostatic (double layer) forces. Extensions to include surface hydration are taken care of with concepts like inner and outer Helmholtz planes, and "dressed" ion sizes. The opposing quantum mechanical attractive forces (variously termed van der Waals, Hamaker, Lifshitz, dispersion, nonelectrostatic forces) are treated separately from electrostatic forces. The ansatz that separates electrostatic and quantum forces can be shown to be thermodynamically inconsistent. Hofmeister or specific ion effects usually show up above ≈10(-2) molar salt. Parameters to accommodate these in terms of hydration and ion size had to be invoked, specific to each case. Ionic dispersion forces, between ions and solvent, for ion-ion and ion-surface interactions are not explicit in classical theories that use "effective" potentials. It can be shown that the missing ionic quantum fluctuation forces have a large role to play in specific ion effects, and in hydration. In a consistent predictive theory they have to be included at the same level as the nonlinear electrostatic forces that form the skeletal framework of standard theory. This poses a challenge. The challenges go further than academic theory and have implications for the interpretation and meaning of concepts like pH, buffers and membrane potentials, and for their experimental interpretation. In this article we overview recent quantitative developments in our evolving understanding of the theoretical origins of specific ion, or Hofmeister effects. These are demonstrated

  13. Gu's function scale of ion hydration force and charge size

    NASA Astrophysics Data System (ADS)

    Gu, Hong-Kan

    1997-06-01

    “Water Vapor Chemistry” as a new science was discovered and established from trace analysis in Gu's laboratory(Gu, 1991; Gu et al., 1991). Gu's Function shows that the trace metal ion concentration in water vapor has positive correlation to “specific electron affinity constant” last ionization potential I z/ion valence Z and negative correlation to ion volume V and coordination number N(Gu, 1994). Gu's Function C=f[(Iz/Z)/VN] of the bond parameter in water vapor chemistry corresponds to the potential energy function Z'e 2/r in the Schrodinger Equation of quantum chemistry. In, different ions with the same 2+ charge, the ion concentration of water—water vapor transfer may be much different. This shows that the 2+ charge of different ions has different attractive force (hydration force). This different attractive force of the charge can be scaled with the relative energy or charge size from Gu's Function.

  14. Free energy of ion hydration: Interface susceptibility and scaling with the ion size

    NASA Astrophysics Data System (ADS)

    Dinpajooh, Mohammadhasan; Matyushov, Dmitry V.

    2015-07-01

    Free energy of solvation of a spherical ion in a force-field water is studied by numerical simulations. The focus is on the linear solvation susceptibility connecting the linear response solvation free energy to the squared ion charge. Spherical hard-sphere solutes, hard-sphere ions, and Kihara solutes (Lennard-Jones modified hard-sphere core) are studied here. The scaling of the solvation susceptibility with the solute size significantly deviates from the Born equation. Using empirical offset corrections of the solute size (or the position of the first peak of the solute-solvent distribution function) do not improve the agreement with simulations. We advance a new perspective on the problem by deriving an exact relation for the radial susceptibility function of the interface. This function yields an effective cavity radius in the Born equation calculated from the solute-solvent radial distribution function. We find that the perspective of the local response, assuming significant alteration of the solvent structure by the solute, is preferable compared to the homogeneous approximation assuming intact solvent structure around the solute. The model finds a simple explanation of the asymmetry of hydration between anions and cations in denser water shells around anions and smaller cavity radii arising from the solute-solvent density profiles.

  15. Plasma size and power scaling of ion temperature gradient driven turbulence

    SciTech Connect

    Idomura, Yasuhiro; Nakata, Motoki

    2014-02-15

    The transport scaling with respect to plasma size and heating power is studied for ion temperature gradient driven turbulence using a fixed-flux full-f gyrokinetic Eulerian code. It is found that when heating power is scaled with plasma size, the ion heat diffusivity increases with plasma size in a local limit regime, where fixed-gradient δf simulations predict a gyro-Bohm scaling. In the local limit regime, the transport scaling is strongly affected by the stiffness of ion temperature profiles, which is related to the power degradation of confinement.

  16. Relation between the ion size and pore size for an electric double-layer capacitor.

    PubMed

    Largeot, Celine; Portet, Cristelle; Chmiola, John; Taberna, Pierre-Louis; Gogotsi, Yury; Simon, Patrice

    2008-03-01

    The research on electrochemical double layer capacitors (EDLC), also known as supercapacitors or ultracapacitors, is quickly expanding because their power delivery performance fills the gap between dielectric capacitors and traditional batteries. However, many fundamental questions, such as the relations between the pore size of carbon electrodes, ion size of the electrolyte, and the capacitance have not yet been fully answered. We show that the pore size leading to the maximum double-layer capacitance of a TiC-derived carbon electrode in a solvent-free ethyl-methylimmidazolium-bis(trifluoro-methane-sulfonyl)imide (EMI-TFSI) ionic liquid is roughly equal to the ion size (approximately 0.7 nm). The capacitance values of TiC-CDC produced at 500 degrees C are more than 160 F/g and 85 F/cm(3) at 60 degrees C, while standard activated carbons with larger pores and a broader pore size distribution present capacitance values lower than 100 F/g and 50 F/cm(3) in ionic liquids. A significant drop in capacitance has been observed in pores that were larger or smaller than the ion size by just an angstrom, suggesting that the pore size must be tuned with sub-angstrom accuracy when selecting a carbon/ion couple. This work suggests a general approach to EDLC design leading to the maximum energy density, which has been now proved for both solvated organic salts and solvent-free liquid electrolytes. PMID:18257568

  17. Relation between the ion size and pore size for an electric double-layer capacitor.

    PubMed

    Largeot, Celine; Portet, Cristelle; Chmiola, John; Taberna, Pierre-Louis; Gogotsi, Yury; Simon, Patrice

    2008-03-01

    The research on electrochemical double layer capacitors (EDLC), also known as supercapacitors or ultracapacitors, is quickly expanding because their power delivery performance fills the gap between dielectric capacitors and traditional batteries. However, many fundamental questions, such as the relations between the pore size of carbon electrodes, ion size of the electrolyte, and the capacitance have not yet been fully answered. We show that the pore size leading to the maximum double-layer capacitance of a TiC-derived carbon electrode in a solvent-free ethyl-methylimmidazolium-bis(trifluoro-methane-sulfonyl)imide (EMI-TFSI) ionic liquid is roughly equal to the ion size (approximately 0.7 nm). The capacitance values of TiC-CDC produced at 500 degrees C are more than 160 F/g and 85 F/cm(3) at 60 degrees C, while standard activated carbons with larger pores and a broader pore size distribution present capacitance values lower than 100 F/g and 50 F/cm(3) in ionic liquids. A significant drop in capacitance has been observed in pores that were larger or smaller than the ion size by just an angstrom, suggesting that the pore size must be tuned with sub-angstrom accuracy when selecting a carbon/ion couple. This work suggests a general approach to EDLC design leading to the maximum energy density, which has been now proved for both solvated organic salts and solvent-free liquid electrolytes.

  18. Size scaling of negative hydrogen ion sources for fusion

    NASA Astrophysics Data System (ADS)

    Fantz, U.; Franzen, P.; Kraus, W.; Schiesko, L.; Wimmer, C.; Wünderlich, D.

    2015-04-01

    The RF-driven negative hydrogen ion source (H-, D-) for the international fusion experiment ITER has a width of 0.9 m and a height of 1.9 m and is based on a ⅛ scale prototype source being in operation at the IPP test facilities BATMAN and MANITU for many years. Among the challenges to meet the required parameters in a caesiated source at a source pressure of 0.3 Pa or less is the challenge in size scaling of a factor of eight. As an intermediate step a ½ scale ITER source went into operation at the IPP test facility ELISE with the first plasma in February 2013. The experience and results gained so far at ELISE allowed a size scaling study from the prototype source towards the ITER relevant size at ELISE, in which operational issues, physical aspects and the source performance is addressed, highlighting differences as well as similarities. The most ITER relevant results are: low pressure operation down to 0.2 Pa is possible without problems; the magnetic filter field created by a current in the plasma grid is sufficient to reduce the electron temperature below the target value of 1 eV and to reduce together with the bias applied between the differently shaped bias plate and the plasma grid the amount of co-extracted electrons. An asymmetry of the co-extracted electron currents in the two grid segments is measured, varying strongly with filter field and bias. Contrary to the prototype source, a dedicated plasma drift in vertical direction is not observed. As in the prototype source, the performance in deuterium is limited by the amount of co-extracted electrons in short as well as in long pulse operation. Caesium conditioning is much harder in deuterium than in hydrogen for which fast and reproducible conditioning is achieved. First estimates reveal a caesium consumption comparable to the one in the prototype source despite the large size.

  19. Ion size effects on the osmotic pressure and electrocapillarity in a nanoslit: Symmetric and asymmetric ion sizes.

    PubMed

    Rajni; Oh, J M; Kang, I S

    2016-06-01

    We analyze the effect of asymmetric finite ion size in nanoconfinement in the view of osmotic pressure and electrocapillarity. When the confinement width becomes comparable with the Debye length, the overlapped electric double layer is significantly deformed by the steric effects. We derive the osmotic pressure from the modified Poisson-Boltzmann equation in a nanoslit to examine the deviation from the ideal osmotic pressure and the repulsive force on the wall considering the asymmetry of ion sizes. Then the electrocapillarity due to the steric effect is investigated under constant potential condition with the flat interface assumption. Later, the deformation by the electrocapillarity is also considered in the first order approximation. PMID:27415363

  20. Ion size effects on the osmotic pressure and electrocapillarity in a nanoslit: Symmetric and asymmetric ion sizes.

    PubMed

    Rajni; Oh, J M; Kang, I S

    2016-06-01

    We analyze the effect of asymmetric finite ion size in nanoconfinement in the view of osmotic pressure and electrocapillarity. When the confinement width becomes comparable with the Debye length, the overlapped electric double layer is significantly deformed by the steric effects. We derive the osmotic pressure from the modified Poisson-Boltzmann equation in a nanoslit to examine the deviation from the ideal osmotic pressure and the repulsive force on the wall considering the asymmetry of ion sizes. Then the electrocapillarity due to the steric effect is investigated under constant potential condition with the flat interface assumption. Later, the deformation by the electrocapillarity is also considered in the first order approximation.

  1. Ion size effects on the osmotic pressure and electrocapillarity in a nanoslit: Symmetric and asymmetric ion sizes

    NASA Astrophysics Data System (ADS)

    Rajni; Oh, J. M.; Kang, I. S.

    2016-06-01

    We analyze the effect of asymmetric finite ion size in nanoconfinement in the view of osmotic pressure and electrocapillarity. When the confinement width becomes comparable with the Debye length, the overlapped electric double layer is significantly deformed by the steric effects. We derive the osmotic pressure from the modified Poisson-Boltzmann equation in a nanoslit to examine the deviation from the ideal osmotic pressure and the repulsive force on the wall considering the asymmetry of ion sizes. Then the electrocapillarity due to the steric effect is investigated under constant potential condition with the flat interface assumption. Later, the deformation by the electrocapillarity is also considered in the first order approximation.

  2. Size evolution of ion beam synthesized Pb nanoparticles in Al

    NASA Astrophysics Data System (ADS)

    Wang, Huan; Zhu, Hongzhi

    2014-07-01

    The size evolution of Pb nanoparticles (NPs) synthesized by ion implantation in an epitaxial Al film has been experimentally investigated. The average radius R of Pb NPs was determined as a function of implantation fluence f. The R( f) data were analyzed using various growth models. Our observations suggest that the size evolution of Pb NPs is controlled by the diffusion-limited growth kinetics ( R 2∝ f). With increasing implantation current density, the diffusion coefficient of Pb atoms in Al is evident to be enhanced. By a comparative analysis of the R( f) data, values of the diffusion coefficient of Pb in Al were obtained.

  3. Size scaling of negative hydrogen ion sources for fusion

    SciTech Connect

    Fantz, U. Franzen, P.; Kraus, W.; Schiesko, L.; Wimmer, C.; Wünderlich, D.

    2015-04-08

    The RF-driven negative hydrogen ion source (H{sup −}, D{sup −}) for the international fusion experiment ITER has a width of 0.9 m and a height of 1.9 m and is based on a ⅛ scale prototype source being in operation at the IPP test facilities BATMAN and MANITU for many years. Among the challenges to meet the required parameters in a caesiated source at a source pressure of 0.3 Pa or less is the challenge in size scaling of a factor of eight. As an intermediate step a ½ scale ITER source went into operation at the IPP test facility ELISE with the first plasma in February 2013. The experience and results gained so far at ELISE allowed a size scaling study from the prototype source towards the ITER relevant size at ELISE, in which operational issues, physical aspects and the source performance is addressed, highlighting differences as well as similarities. The most ITER relevant results are: low pressure operation down to 0.2 Pa is possible without problems; the magnetic filter field created by a current in the plasma grid is sufficient to reduce the electron temperature below the target value of 1 eV and to reduce together with the bias applied between the differently shaped bias plate and the plasma grid the amount of co-extracted electrons. An asymmetry of the co-extracted electron currents in the two grid segments is measured, varying strongly with filter field and bias. Contrary to the prototype source, a dedicated plasma drift in vertical direction is not observed. As in the prototype source, the performance in deuterium is limited by the amount of co-extracted electrons in short as well as in long pulse operation. Caesium conditioning is much harder in deuterium than in hydrogen for which fast and reproducible conditioning is achieved. First estimates reveal a caesium consumption comparable to the one in the prototype source despite the large size.

  4. Effect of a RF Wave on Ion Cyclotron Instability in Size Distributed Impurities Containing Plasmas

    SciTech Connect

    Sharma, A. K.; Tripathi, V. K.; Annou, R.

    2008-09-07

    The effect of a large amplitude lower hybrid wave on current driven ion cyclotron waves in a dusty plasma where dust grains are size distributed is examined. The influence of the lower hybrid wave on the stabilization of the instability is studied. The efficacy of rf is dust density dependent.

  5. Nightside auroral zone and polar cap ion outflow as a function of substorm size and phase

    NASA Astrophysics Data System (ADS)

    Wilson, G. R.; Ober, D. M.; Germany, G. A.; Lund, E. J.

    2004-02-01

    Because the high latitude ionosphere is an important source of plasma for the magnetosphere under active conditions, we have undertaken a study of the way ion outflow from the nightside auroral zone and polar cap respond to substorm activity. We have combined data from the Ultraviolet Imager (UVI) on Polar with ion upflow measurements from the TEAMS instrument on the FAST spacecraft to construct a picture of ion upflow from these regions as a function of substorm size and as a function of time relative to substorm onset. We use data taken during solar minimum in the northern hemisphere between December 1996 and February 1997. We find that the total nightside auroral zone ion outflow rate (averaged over substorm phase) depends on the size of the substorm, increasing by about a factor of 10 for both O+ and H+ from the smallest to the largest substorms in our study. The combined outflow rate from both the polar cap and the nightside auroral zone goes up by a factor of 7 for both ions for the same change in conditions. Regardless of storm size, the nightside auroral zone outflow rate increases by about a factor of 2 after onset, reaching its peak level after about 20 min. These results indicate that the change in the nightside auroral zone ion outflow rate that accompanies substorm onset is not as significant as the change from low to high magnetic activity. As a consequence, the prompt increase in the near earth plasma sheet energy density of O+ and H+ ions that accompanies onset [, 1996] is likely due to local energization of ions already present rather than to the sudden arrival and energization of fresh ionospheric plasma.

  6. CaCO3 size distribution: A paleocarbonate ion proxy?

    NASA Astrophysics Data System (ADS)

    Broecker, W. S.; Clark, E.

    1999-10-01

    Lysocline reconstructions play an important role in scenarios purporting to explain the lowered atmospheric CO2 content of glacial time. These reconstructions are based on indicators such as the CaCO3 content, the percent of coarse fraction, the ratio of fragments to whole foraminifera shells, the ratio of solution-susceptible to solution-resistant species, and the ratio of coarse to fine CaCO3. All assume that changes with time in the composition of the input material do not bias the result. However, as the composition of the input material does depend on climate, none of these indicators provides an absolute measure of the extent of dissolution. In this paper we evaluate the reliability of the ratio of >63 µm CaCO3 to total CaCO3 as a dissolution indicator. We present here results that suggest that in today's tropics this ratio appears to be determined solely by CO3= ion concentration and water depth (i.e., the saturation state of bottom waters). This finding offers the possibility that the size fraction index can be used to reconstruct CO3= ion concentrations for the late Quaternary ocean to an accuracy of ±5 µmol kg-1.

  7. Laser ion acceleration toward future ion beam cancer therapy - Numerical simulation study -

    PubMed Central

    Kawata, Shigeo; Izumiyama, Takeshi; Nagashima, Toshihiro; Takano, Masahiro; Barada, Daisuke; Kong, Qing; Gu, Yan Jun; Wang, Ping Xiao; Ma, Yan Yun; Wang, Wei Min

    2013-01-01

    Background: Ion beam has been used in cancer treatment, and has a unique preferable feature to deposit its main energy inside a human body so that cancer cell could be killed by the ion beam. However, conventional ion accelerator tends to be huge in its size and its cost. In this paper a future intense-laser ion accelerator is proposed to make the ion accelerator compact. Subjects and methods: An intense femtosecond pulsed laser was employed to accelerate ions. The issues in the laser ion accelerator include the energy efficiency from the laser to the ions, the ion beam collimation, the ion energy spectrum control, the ion beam bunching and the ion particle energy control. In the study particle computer simulations were performed to solve the issues, and each component was designed to control the ion beam quality. Results: When an intense laser illuminates a target, electrons in the target are accelerated and leave from the target; temporarily a strong electric field is formed between the high-energy electrons and the target ions, and the target ions are accelerated. The energy efficiency from the laser to ions was improved by using a solid target with a fine sub-wavelength structure or by a near-critical density gas plasma. The ion beam collimation was realized by holes behind the solid target. The control of the ion energy spectrum and the ion particle energy, and the ion beam bunching were successfully realized by a multi-stage laser-target interaction. Conclusions: The present study proposed a novel concept for a future compact laser ion accelerator, based on each component study required to control the ion beam quality and parameters. PMID:24155555

  8. Studies of ion solvation using pulse radiolysis

    SciTech Connect

    Jonah, C.D.; Lin, Yi.

    1991-01-01

    In this paper we describe our measurements of ion solvation in a series of alcohols. Benzophenone is dissolved in an alcohol at a sufficiently high concentration so that the electrons formed by radiation will react with the benzophenone molecule to form the anion. The spectrum of the anion is then observed as a function of time. As the benzophenone anion solvates, the spectrum shifts to the blue. The results of our measurements clearly show that both the size of the solvent molecules and their shapes are important in the solvation process. Different spectral relaxation processes are observed for ions than are observed for electron solvation, the simple'' ion system that has been most heavily studied. In addition, these results suggest that the rate of solvation may be different for ions in solution than for dipoles in solution. 26 refs., 3 figs.

  9. Spot size dependence of laser accelerated protons in thin multi-ion foils

    SciTech Connect

    Liu, Tung-Chang Shao, Xi; Liu, Chuan-Sheng; Eliasson, Bengt; Wang, Jyhpyng; Chen, Shih-Hung

    2014-06-15

    We present a numerical study of the effect of the laser spot size of a circularly polarized laser beam on the energy of quasi-monoenergetic protons in laser proton acceleration using a thin carbon-hydrogen foil. The used proton acceleration scheme is a combination of laser radiation pressure and shielded Coulomb repulsion due to the carbon ions. We observe that the spot size plays a crucial role in determining the net charge of the electron-shielded carbon ion foil and consequently the efficiency of proton acceleration. Using a laser pulse with fixed input energy and pulse length impinging on a carbon-hydrogen foil, a laser beam with smaller spot sizes can generate higher energy but fewer quasi-monoenergetic protons. We studied the scaling of the proton energy with respect to the laser spot size and obtained an optimal spot size for maximum proton energy flux. Using the optimal spot size, we can generate an 80 MeV quasi-monoenergetic proton beam containing more than 10{sup 8} protons using a laser beam with power 250 TW and energy 10 J and a target of thickness 0.15 wavelength and 49 critical density made of 90% carbon and 10% hydrogen.

  10. Functional implications of species differences in the size and morphology of the isthmo optic nucleus (ION) in birds.

    PubMed

    Gutiérrez-Ibáñez, Cristián; Iwaniuk, Andrew N; Lisney, Thomas J; Faunes, Macarena; Marín, Gonzalo J; Wylie, Douglas R

    2012-01-01

    In birds, there is a retinofugal projection from the brain to the retina originating from the isthmo optic nucleus (ION) in the midbrain. Despite a large number of anatomical, physiological and histochemical studies, the function of this retinofugal system remains unclear. Several functions have been proposed including: gaze stabilization, pecking behavior, dark adaptation, shifting attention, and detection of aerial predators. This nucleus varies in size and organization among some species, but the relative size and morphology of the ION has not been systematically studied. Here, we present a comparison of the relative size and morphology of the ION in 81 species of birds, representing 17 different orders. Our results show that several orders of birds, besides those previously reported, have a large, well-organized ION, including: hummingbirds, woodpeckers, coots and allies, and kingfishers. At the other end of the spectrum, parrots, herons, waterfowl, owls and diurnal raptors have relatively small ION volumes. ION also appears to be absent or unrecognizable is several taxa, including one of the basal avian groups, the tinamous, which suggests that the ION may have evolved only in the more modern group of birds, Neognathae. Finally, we demonstrate that evolutionary changes in the relative size and the cytoarchitectonic organization of ION have occurred largely independent of phylogeny. The large relative size of the ION in orders with very different lifestyles and feeding behaviors suggest there is no clear association with pecking behavior or predator detection. Instead, our results suggest that the ION is more complex and enlarged in birds that have eyes that are emmetropic in some parts of the visual field and myopic in others. We therefore posit that the ION is involved in switching attention between two parts of the retina i.e. from an emmetropic to a myopic part of the retina.

  11. Functional Implications of Species Differences in the Size and Morphology of the Isthmo Optic Nucleus (ION) in Birds

    PubMed Central

    Gutiérrez-Ibáñez, Cristián; Iwaniuk, Andrew N.; Lisney, Thomas J.; Faunes, Macarena; Marín, Gonzalo J.; Wylie, Douglas R.

    2012-01-01

    In birds, there is a retinofugal projection from the brain to the retina originating from the isthmo optic nucleus (ION) in the midbrain. Despite a large number of anatomical, physiological and histochemical studies, the function of this retinofugal system remains unclear. Several functions have been proposed including: gaze stabilization, pecking behavior, dark adaptation, shifting attention, and detection of aerial predators. This nucleus varies in size and organization among some species, but the relative size and morphology of the ION has not been systematically studied. Here, we present a comparison of the relative size and morphology of the ION in 81 species of birds, representing 17 different orders. Our results show that several orders of birds, besides those previously reported, have a large, well-organized ION, including: hummingbirds, woodpeckers, coots and allies, and kingfishers. At the other end of the spectrum, parrots, herons, waterfowl, owls and diurnal raptors have relatively small ION volumes. ION also appears to be absent or unrecognizable is several taxa, including one of the basal avian groups, the tinamous, which suggests that the ION may have evolved only in the more modern group of birds, Neognathae. Finally, we demonstrate that evolutionary changes in the relative size and the cytoarchitectonic organization of ION have occurred largely independent of phylogeny. The large relative size of the ION in orders with very different lifestyles and feeding behaviors suggest there is no clear association with pecking behavior or predator detection. Instead, our results suggest that the ION is more complex and enlarged in birds that have eyes that are emmetropic in some parts of the visual field and myopic in others. We therefore posit that the ION is involved in switching attention between two parts of the retina i.e. from an emmetropic to a myopic part of the retina. PMID:22666395

  12. Ion acoustic and dust acoustic waves at finite size of plasma particles

    SciTech Connect

    Andreev, Pavel A. Kuz'menkov, L. S.

    2015-03-15

    We consider the influence of the finite size of ions on the properties of classic plasmas. We focus our attention at the ion acoustic waves for electron-ion plasmas. We also consider the dusty plasmas where we account the finite size of ions and particles of dust and consider the dispersion of dust acoustic waves. The finite size of particles is a classical effect as well as the Coulomb interaction. The finite size of particles considerably contributes to the properties of the dense plasmas in the small wavelength limit. Low temperature dense plasmas, revealing the quantum effects, are also affected by the finite size of plasma particles. Consequently, it is important to consider the finite size of ions in the quantum plasmas as well.

  13. Nanomaterial size distribution analysis via liquid nebulization coupled with ion mobility spectrometry (LN-IMS).

    PubMed

    Jeon, Seongho; Oberreit, Derek R; Van Schooneveld, Gary; Hogan, Christopher J

    2016-02-21

    We apply liquid nebulization (LN) in series with ion mobility spectrometry (IMS, using a differential mobility analyzer coupled to a condensation particle counter) to measure the size distribution functions (the number concentration per unit log diameter) of gold nanospheres in the 5-30 nm range, 70 nm × 11.7 nm gold nanorods, and albumin proteins originally in aqueous suspensions. In prior studies, IMS measurements have only been carried out for colloidal nanoparticles in this size range using electrosprays for aerosolization, as traditional nebulizers produce supermicrometer droplets which leave residue particles from non-volatile species. Residue particles mask the size distribution of the particles of interest. Uniquely, the LN employed in this study uses both online dilution (with dilution factors of up to 10(4)) with ultra-high purity water and a ball-impactor to remove droplets larger than 500 nm in diameter. This combination enables hydrosol-to-aerosol conversion preserving the size and morphology of particles, and also enables higher non-volatile residue tolerance than electrospray based aerosolization. Through LN-IMS measurements we show that the size distribution functions of narrowly distributed but similarly sized particles can be distinguished from one another, which is not possible with Nanoparticle Tracking Analysis in the sub-30 nm size range. Through comparison to electron microscopy measurements, we find that the size distribution functions inferred via LN-IMS measurements correspond to the particle sizes coated by surfactants, i.e. as they persist in colloidal suspensions. Finally, we show that the gas phase particle concentrations inferred from IMS size distribution functions are functions of only of the liquid phase particle concentration, and are independent of particle size, shape, and chemical composition. Therefore LN-IMS enables characterization of the size, yield, and polydispersity of sub-30 nm particles.

  14. Nanomaterial size distribution analysis via liquid nebulization coupled with ion mobility spectrometry (LN-IMS).

    PubMed

    Jeon, Seongho; Oberreit, Derek R; Van Schooneveld, Gary; Hogan, Christopher J

    2016-02-21

    We apply liquid nebulization (LN) in series with ion mobility spectrometry (IMS, using a differential mobility analyzer coupled to a condensation particle counter) to measure the size distribution functions (the number concentration per unit log diameter) of gold nanospheres in the 5-30 nm range, 70 nm × 11.7 nm gold nanorods, and albumin proteins originally in aqueous suspensions. In prior studies, IMS measurements have only been carried out for colloidal nanoparticles in this size range using electrosprays for aerosolization, as traditional nebulizers produce supermicrometer droplets which leave residue particles from non-volatile species. Residue particles mask the size distribution of the particles of interest. Uniquely, the LN employed in this study uses both online dilution (with dilution factors of up to 10(4)) with ultra-high purity water and a ball-impactor to remove droplets larger than 500 nm in diameter. This combination enables hydrosol-to-aerosol conversion preserving the size and morphology of particles, and also enables higher non-volatile residue tolerance than electrospray based aerosolization. Through LN-IMS measurements we show that the size distribution functions of narrowly distributed but similarly sized particles can be distinguished from one another, which is not possible with Nanoparticle Tracking Analysis in the sub-30 nm size range. Through comparison to electron microscopy measurements, we find that the size distribution functions inferred via LN-IMS measurements correspond to the particle sizes coated by surfactants, i.e. as they persist in colloidal suspensions. Finally, we show that the gas phase particle concentrations inferred from IMS size distribution functions are functions of only of the liquid phase particle concentration, and are independent of particle size, shape, and chemical composition. Therefore LN-IMS enables characterization of the size, yield, and polydispersity of sub-30 nm particles. PMID:26750519

  15. Experimental study of particle formation by ion-ion recombination.

    PubMed

    Nagato, Kenkichi; Nakauchi, Masataka

    2014-10-28

    Particle formation by ion-ion recombination has been studied using an ion-ion recombination drift tube (IIR-DT). IIR-DT uses two DC corona ionizers to produce positive and negative ions at the ends of the drift tube. The ions of different polarity move in opposite directions along the electric field in the drift tube. We observed significant particle formation using ions generated in purified air containing H2O, SO2, and NH3. Particle formation was suppressed when no drift field was applied. We also observed few particles when we used a single discharge (positive or negative only). These results clearly show that particle formation observed in the IIR-DT was caused by nucleation by ion-ion recombination. Positive and negative ion species produced by corona ionizers were investigated using an atmospheric pressure ionization mass spectrometer. The ions involved in the particle formation were suggested to include H3O(+)(H2O)n and NH4(+)(H2O)n for positive ions and sulfur-based ions such as SO5(-), SO5(-)NO2, and HSO4(-) for negative ions. PMID:25362301

  16. Transcellular ion flow in Escherichia coli B and electrical sizing of bacterias.

    PubMed

    Zimmermann, U; Schulz, J; Pilwat, G

    1973-10-01

    Dielectric breakdown of cell membranes and, in response, transcellular ion flows were measured in Escherichia coli B 163 and B 525 using a Coulter counter as the detector with a hydrodynamic jet focusing close to the orifice of the counter. Plotting the relative pulse height for compensated amplification of a certain size of the cells against increasing detector current, a rather sharp bend within the linear function was found, which did not occur when measuring fixed cells or polystyrene latex. The start current for transcellular ion flow causing the change of the slope is different for the potassium-deficient mutant B 525 in comparison with the wild-type B 163, indicating a change in the membrane structure of B 525 by mutation and demonstrating the sensitivity of the method for studying slight changes in membrane structure in general. The theoretical size distributions for two current values in the range of transcellular ion flow were constructed from the true size distribution at low detector currents, assuming an idealized sharp changeover of the bacterial conductivity from zero to one-third of the electrolyte conductivity.

  17. Coarse-grained simulations of an ionic liquid-based capacitor: I. Density, ion size, and valency effects.

    PubMed

    Breitsprecher, Konrad; Košovan, Peter; Holm, Christian

    2014-07-16

    We introduce a hierarchy of generic coarse-grained models of ionic liquids of increasing complexity. We use them in molecular dynamics simulations to study the differential capacitance of a capacitor consisting of an ionic liquid between two planar electrodes. The primary goal is to explain the complex dependence of the differential capacitance Cd on the electrode potential U in simple terms, e.g. in terms of the size and valency of the ions. For this purpose we introduce the symmetric model A, which qualitatively reproduces the Cd(U) dependence predicted by the mean-field theory but also reveals strong quantitative deviations. We further introduce size asymmetry in model A by increasing the cation size. In model B we vary the cation valency, keeping the sizes of both ions constant. We show that simultaneous increases in size and valency may compensate for each other, leading to a Cd(U) very similar to that for the symmetric case. We interpret distinct features in Cd(U) on the basis of the density profiles of the ions and charge density profiles. We focus on the first two ion layers at the electrode, and demonstrate that the polarization of the ionic liquid proceeds through replacement of one ion type by the other, in contrast to the simple increase in ion concentrations typical for dilute systems. The understanding gained for the simple models serves as a reference for interpretation of complex effects of ion size, valency and shape. This is carried through in part II (a separate article) where we show how the planar shape of ions in model C brings new features to the Cd(U) curve and also to the polarization mechanism.

  18. Anomalous cyclic voltammetric response from pores smaller than ion size by voltage-induced force.

    PubMed

    Yang, Cheol-Min; Jung, Hwan Jung; Kim, Yong Jung

    2015-05-15

    Nanoporous carbons, with different micropore size distributions, were prepared based on waste coffee grounds by a chemical activation process in order to elucidate the correlation between desolvated ions and pores smaller than the sizes of ions using an organic electrolyte. The pore structure of the coffee-based nanoporous carbon was strongly dependent on the heat-treatment temperature prior to the activation process. Cyclic voltammograms of the nanoporous carbons mainly dominated by the smaller pore relative to that of the bare ion size clearly showed deviation from an ideal feature of the current response. It was clearly envisaged that even a bare ion of a size larger than the pore size can penetrate into the pore by voltage-induced force. PMID:25668782

  19. Additional considerations about the role of ion size in charge reversal.

    PubMed

    Martín-Molina, A; Hidalgo-Álvarez, R; Quesada-Pérez, M

    2009-10-21

    The effect of the ion size on the charge reversal process is studied via canonical Monte Carlo simulation. To this end, a primitive model of electrolyte is used to analyze the electric double layer formed by an asymmetric electrolyte in the presence of a charged planar wall. Different values of ion diameters and surface charge densities are used so as to determine the conditions at which the charge reversal first occurs. For each case, the apparent surface charge density is calculated as a function of the distance from the charged wall for the different electrolyte concentrations in order to establish the minimal salt concentration required for the charge reversal. We will refer to this electrolyte concentration as the reversal concentration and will show how it depends on the surface charge density and on the ion size. From the apparent surface charge density profiles, the distance from the wall at which the charge reversal arises as well as its intensity can be also inferred. PMID:21715840

  20. Cluster Size Dependence of Etching by Reactive Gas Cluster Ion Beams

    SciTech Connect

    Toyoda, Noriaki; Yamada, Iaso

    2008-11-03

    Mass-selected reactive gas cluster ion beams (GCIB) were formed using a permanent magnetic filter. Irradiations of CO{sub 2} GCIB on amorphous carbon films and irradiations of SF{sub 6} and SF{sub 6}/Ar mixed GCIB on Si surfaces were performed to study the cluster size dependence on etching yields by reactive GCIB. The reactive sputtering yield of carbon by CO{sub 2} GCIB was almost ten times higher than that by Ar GCIB. In the case of (CO{sub 2}){sub 20000} GCIB with energy of 20 keV (1 eV/atom), it showed the high sputtering yield of 200 atoms/ion, however, there was little crater formation on the carbon surface. It is thought that very soft etching without crater formation would take place in this condition. In the case of SF{sub 6} GCIB on Si, the etching depth of Si showed maximum value when the fraction of SF{sub 6} to Ar was around 50%. As the etching yield was higher than pure SF{sub 6} GCIB, there was a strong ion assisted etching effects in the case of Ar/SF{sub 6} mixed cluster ion irradiations.

  1. Beam size reduction of a several hundred-keV compact ion microbeam system by improving the extraction condition in an ion source

    NASA Astrophysics Data System (ADS)

    Ishii, Yasuyuki; Ohkubo, Takeru; Kamiya, Tomihiro; Saitoh, Yuichi

    2015-04-01

    A several hundred-keV compact ion microbeam system with a three-stage acceleration lens has been developed to form an ion beam of several micrometers in diameter. In a previous study of the Ohkubo et al. (2013) and Ishii et al. (2014), a hydrogen beam of 143 keV having 17 μm diameter was experimentally formed using such a microbeam system. It was demonstrated that a three-stage acceleration lens functioned as a focusing lens and indicated that the beam diameter (hereinafter referred to as the "beam size") depended on the extraction voltage to generate the ion beam and the vacuum pressure in the extraction space in a plasma-type ion source. In this study, the hydrogen beam sizes were experimentally measured at 130 keV as functions of the extraction voltage and vacuum pressure to form the beam size with several micrometers in diameter. These two relationships showed that beam sizes were reduced in the extraction voltage range of 400-500 V and when the vacuum pressure was lowered to a minimum value of 5.33 × 10-5 Pa. In addition, the result showed that the beam size was dominantly influenced by the vacuum pressure. Consequently, a hydrogen beam 5.8 μm in diameter was formed experimentally-the smallest beam yet obtained.

  2. Production and appearance size of multiply charged stoichiometric and nonstoichiometric SO/sub 2/ cluster ions

    SciTech Connect

    Scheier, P.; Walder, G.; Stamatovic, A.; Maerk, T.D.

    1989-01-15

    We report the first well resolved SO/sub 2/ cluster ion spectrum showing doubly charged parent and fragment ions. The critical appearance size deduced for doubly charged SO/sub 2/ clusters is n/sub 2/ = 21 and for triply charged SO/sub 2/ clusters n/sub 3/ = 49. This result is compared with theoretical predictions.

  3. Effect Of Grain Size-Distribution And Nonthermal Ion Distribution On Dust Acoustic Solitons

    SciTech Connect

    Annou, K.; Annou, R.

    2005-10-31

    The investigation of the formation of non-linear coherent structures in dusty plasmas taking into account the dust size and non-thermal ion distributions is conducted. Conditions of the existence of solitons in terms of the Mach number, concentration of non-thermal ions, dust charge and the permeability of the grains are evaluated.

  4. Design, microfabrication, and analysis of micrometer-sized cylindrical ion trap arrays.

    PubMed

    Cruz, D; Chang, J P; Fico, M; Guymon, A J; Austin, D E; Blain, M G

    2007-01-01

    A description of the design and microfabrication of arrays of micrometer-scale cylindrical ion traps is offered. Electrical characterization and initial ion trapping experiments with a massively parallel array of 5 microm internal radius (r(0)) sized cylindrical ion traps (CITs) are also described. The ion trap, materials, and design are presented and shown to be critical in achieving minimal trapping potential while maintaining minimal power consumption. The ion traps, fabricated with metal electrodes, have inner radii of 1, 2, 5, and 10 microm and range from 5 to 24 microm in height. The electrical characteristics of packaged ion trap arrays were measured with a vector network analyzer. The testing focused on trapping toluene (C(7)H(8)), mass 91, 92, or 93 amu, in the 5 microm sized CITs. Ions were formed via electron impact ionization and were ejected by turning off the rf voltage applied to the ring electrode; a current signal was collected at this time. Optimum ionization and trapping conditions, such as a sufficient pseudopotential well and high ionization to ion loss rate ratio (as determined by simulation), proved to be difficult to establish due to the high device capacitance and the presence of exposed dielectric material in the trapping region. However, evidence was obtained suggesting the trapping of ions in 1%-15% of the traps in the array. These first tests on micrometer-scale CITs indicated the necessary materials and device design modifications for realizing ultrasmall and low power ion traps.

  5. Estimating neutral nanoparticle steady state size distribution and growth according to measurements of intermediate air ions

    NASA Astrophysics Data System (ADS)

    Tammet, H.; Komsaare, K.; Hõrrak, U.

    2013-05-01

    The concentration of nanometer aerosol particles in atmospheric air during quiet periods of new particle formation is low and direct measuring is difficult. We study what information about neutral particles can be drawn from measurements of intermediate ions, which are the electrically charged particles between 1.5-7.5 nm in diameter. If the coagulation sink of nanoparticles and the growth rate of charged particles are known, then the steady state equations allow us to calculate the size distribution of neutral nanoparticles. Variations in the trial value of the growth rate have a minor effect on the estimates of the concentrations and size distributions. There exists a value of the constant growth rate of charged nanoparticles that leads to a minimum deviation of the estimated growth rate of neutral nanoparticles from the growth rate of charged nanoparticles. Rough estimates of the growth rate and size distribution of neutral nanoparticles are derived despite the fact that the sample data of intermediate ion measurements is not accompanied by simultaneous measurements of the background aerosol and ionization rate. In the case of a near-median intermediate ion concentration of 21 ± 2 cm-3 in the urban air of a small town, the growth rate of nanoparticles is estimated to be about 2 nm h-1, while the growth flux or apparent nucleation rate is about 0.5 cm-3 s-1 at 3 nm and about 0.08 cm-3 s-1 at 7 nm. The results suggest that the process of new particle formation is not interrupted during the quiet periods between events of intensive nucleation of atmospheric aerosols.

  6. Self-assembled asymmetric membrane containing micron-size germanium for high capacity lithium ion batteries

    DOE PAGES

    Byrd, Ian; Chen, Hao; Webber, Theron; Li, Jianlin; Wu, Ji

    2015-10-23

    We report the formation of novel asymmetric membrane electrode containing micron-size (~5 μm) germanium powders through a self-assembly phase inversion method for high capacity lithium ion battery anode. 850 mA h g-1 capacity (70%) can be retained at a current density of 600 mA g-1 after 100 cycles with excellent rate performance. Such a high retention rate has rarely been seen for pristine micron-size germanium anodes. Moreover, scanning electron microscope studies reveal that germanium powders are uniformly embedded in a networking porous structure consisting of both nanopores and macropores. It is believed that such a unique porous structure can efficientlymore » accommodate the ~260% volume change during germanium alloying and de-alloying process, resulting in an enhanced cycling performance. Finally, these porous membrane electrodes can be manufactured in large scale using a roll-to-roll processing method.« less

  7. Self-assembled asymmetric membrane containing micron-size germanium for high capacity lithium ion batteries

    SciTech Connect

    Byrd, Ian; Chen, Hao; Webber, Theron; Li, Jianlin; Wu, Ji

    2015-10-23

    We report the formation of novel asymmetric membrane electrode containing micron-size (~5 μm) germanium powders through a self-assembly phase inversion method for high capacity lithium ion battery anode. 850 mA h g-1 capacity (70%) can be retained at a current density of 600 mA g-1 after 100 cycles with excellent rate performance. Such a high retention rate has rarely been seen for pristine micron-size germanium anodes. Moreover, scanning electron microscope studies reveal that germanium powders are uniformly embedded in a networking porous structure consisting of both nanopores and macropores. It is believed that such a unique porous structure can efficiently accommodate the ~260% volume change during germanium alloying and de-alloying process, resulting in an enhanced cycling performance. Finally, these porous membrane electrodes can be manufactured in large scale using a roll-to-roll processing method.

  8. Does Cation Size Affect Occupancy and Electrostatic Screening of the Nucleic Acid Ion Atmosphere?

    PubMed

    Gebala, Magdalena; Bonilla, Steve; Bisaria, Namita; Herschlag, Daniel

    2016-08-31

    Electrostatics are central to all aspects of nucleic acid behavior, including their folding, condensation, and binding to other molecules, and the energetics of these processes are profoundly influenced by the ion atmosphere that surrounds nucleic acids. Given the highly complex and dynamic nature of the ion atmosphere, understanding its properties and effects will require synergy between computational modeling and experiment. Prior computational models and experiments suggest that cation occupancy in the ion atmosphere depends on the size of the cation. However, the computational models have not been independently tested, and the experimentally observed effects were small. Here, we evaluate a computational model of ion size effects by experimentally testing a blind prediction made from that model, and we present additional experimental results that extend our understanding of the ion atmosphere. Giambasu et al. developed and implemented a three-dimensional reference interaction site (3D-RISM) model for monovalent cations surrounding DNA and RNA helices, and this model predicts that Na(+) would outcompete Cs(+) by 1.8-2.1-fold; i.e., with Cs(+) in 2-fold excess of Na(+) the ion atmosphere would contain an equal number of each cation (Nucleic Acids Res. 2015, 43, 8405). However, our ion counting experiments indicate that there is no significant preference for Na(+) over Cs(+). There is an ∼25% preferential occupancy of Li(+) over larger cations in the ion atmosphere but, counter to general expectations from existing models, no size dependence for the other alkali metal ions. Further, we followed the folding of the P4-P6 RNA and showed that differences in folding with different alkali metal ions observed at high concentration arise from cation-anion interactions and not cation size effects. Overall, our results provide a critical test of a computational prediction, fundamental information about ion atmosphere properties, and parameters that will aid in the

  9. Site-Specific Fragmentation of Polystyrene Molecule Using Size-Selected Ar Gas Cluster Ion Beam

    NASA Astrophysics Data System (ADS)

    Moritani, Kousuke; Mukai, Gen; Hashinokuchi, Michihiro; Mochiji, Kozo

    2009-04-01

    The secondary ion mass spectrum (SIMS) of a polystyrene thin film was investigated using a size-selected Ar gas cluster ion beam (GCIB). The fragmentation in the SIM spectrum varied by kinetic energy per atom (Eatom); the Eatom dependence of the secondary ion intensity of the fragment species of polystyrene can be essentially classified into three types based on the relationship between Eatom and the dissociation energy of a specific bonding site in the molecule. These results indicate that adjusting Eatom of size-selected GCIB may realize site-specific bond breaking within a molecule.

  10. Determining the size-dependent structure of ligand-free gold-cluster ions.

    PubMed

    Schooss, Detlef; Weis, Patrick; Hampe, Oliver; Kappes, Manfred M

    2010-03-28

    Ligand-free metal clusters can be prepared over a wide size range, but only in comparatively small amounts. Determining their size-dependent properties has therefore required the development of experimental methods that allow characterization of sample sizes comprising only a few thousand mass-selected particles under well-defined collision-free conditions. In this review, we describe the application of these methods to the geometric structural determination of Au(n)(+) and Au(n)(-) with n = 3-20. Geometries were assigned by comparing experimental data, primarily from ion-mobility spectrometry and trapped ion electron diffraction, to structural models from quantum chemical calculations.

  11. Voltage dependence of cluster size in carbon films using plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    McKenzie, D. R.; Tarrant, R. N.; Bilek, M. M. M.; Pearce, G.; Marks, N. A.; McCulloch, D. G.; Lim, S. H. N.

    2003-05-01

    Carbon films were prepared using a cathodic arc with plasma immersion ion implantation (PIII). Using Raman spectroscopy to determine cluster size, a comparison is made between cluster sizes at high voltage and a low duty cycle of pulses with the cluster sizes produced at low voltage and a higher duty cycle. We find that for ion implantation in the range 2-20 kV, the cluster size depends more on implantation energy ( E) than implantation frequency ( f), unlike stress relief, which we have previously shown [M.M.M. Bilek, et al., IEEE Trans. in Plasma Sci., Proceedings 20th ISDEIV 1-5 July 2002, Tours, France, Cat. No. 02CH37331, IEEE, Piscataway, NJ, USA, p. 95] to be dependent on the product Ef. These differences are interpreted in terms of a model in which the ion impacts create thermal spikes.

  12. Sample size estimation in prevalence studies.

    PubMed

    Arya, Ravindra; Antonisamy, Belavendra; Kumar, Sushil

    2012-11-01

    Estimation of appropriate sample size for prevalence surveys presents many challenges, particularly when the condition is very rare or has a tendency for geographical clustering. Sample size estimate for prevalence studies is a function of expected prevalence and precision for a given level of confidence expressed by the z statistic. Choice of the appropriate values for these variables is sometimes not straight-forward. Certain other situations do not fulfil the assumptions made in the conventional equation and present a special challenge. These situations include, but are not limited to, smaller population size in relation to sample size, sampling technique or missing data. This paper discusses practical issues in sample size estimation for prevalence studies with an objective to help clinicians and healthcare researchers make more informed decisions whether reviewing or conducting such a study. PMID:22562262

  13. Interfacial Studies of Sized Carbon Fiber

    SciTech Connect

    Shahrul, S. N.; Hartini, M. N.; Hilmi, E. A.; Nizam, A.

    2010-03-11

    This study was performed to investigate the influence of sizing treatment on carbon fiber in respect of interfacial adhesion in composite materials, Epolam registered 2025. Fortafil unsized carbon fiber was used to performed the experiment. The fiber was commercially surface treated and it was a polyacrylonitrile based carbon fiber with 3000 filament per strand. Epicure registered 3370 was used as basic sizing chemical and dissolved in two types of solvent, ethanol and acetone for the comparison purpose. The single pull out test has been used to determine the influence of sizing on carbon fiber. The morphology of carbon fiber was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The apparent interfacial strength IFSS values determined by pull out test for the Epicure registered 3370/ethanol sized carbon fiber pointed to a good interfacial behaviour compared to the Epicure registered 3370/acetone sized carbon fiber. The Epicure registered 3370/ethanol sizing agent was found to be effective in promoting adhesion because of the chemical reactions between the sizing and Epolam registered 2025 during the curing process. From this work, it showed that sized carbon fiber using Epicure registered 3370 with addition of ethanol give higher mechanical properties of carbon fiber in terms of shear strength and also provided a good adhesion between fiber and matrix compared to the sizing chemical that contain acetone as a solvent.

  14. Interfacial Studies of Sized Carbon Fiber

    NASA Astrophysics Data System (ADS)

    Shahrul, S. N.; Hartini, M. N.; Hilmi, E. A.; Nizam, A.

    2010-03-01

    This study was performed to investigate the influence of sizing treatment on carbon fiber in respect of interfacial adhesion in composite materials, Epolam® 2025. Fortafil unsized carbon fiber was used to performed the experiment. The fiber was commercially surface treated and it was a polyacrylonitrile based carbon fiber with 3000 filament per strand. Epicure® 3370 was used as basic sizing chemical and dissolved in two types of solvent, ethanol and acetone for the comparison purpose. The single pull out test has been used to determine the influence of sizing on carbon fiber. The morphology of carbon fiber was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The apparent interfacial strength IFSS values determined by pull out test for the Epicure® 3370/ethanol sized carbon fiber pointed to a good interfacial behaviour compared to the Epicure® 3370/acetone sized carbon fiber. The Epicure® 3370/ethanol sizing agent was found to be effective in promoting adhesion because of the chemical reactions between the sizing and Epolam® 2025 during the curing process. From this work, it showed that sized carbon fiber using Epicure® 3370 with addition of ethanol give higher mechanical properties of carbon fiber in terms of shear strength and also provided a good adhesion between fiber and matrix compared to the sizing chemical that contain acetone as a solvent.

  15. Ionic size effects to molecular solvation energy and to ion current across a channel resulted from the nonuniform size-modified PNP equations

    NASA Astrophysics Data System (ADS)

    Qiao, Yu; Tu, Bin; Lu, Benzhuo

    2014-05-01

    Ionic finite size can impose considerable effects to both the equilibrium and non-equilibrium properties of a solvated molecular system, such as the solvation energy, ionic concentration, and transport in a channel. As discussed in our former work [B. Lu and Y. C. Zhou, Biophys. J. 100, 2475 (2011)], a class of size-modified Poisson-Boltzmann (PB)/Poisson-Nernst-Planck (PNP) models can be uniformly studied through the general nonuniform size-modified PNP (SMPNP) equations deduced from the extended free energy functional of Borukhov et al. [I. Borukhov, D. Andelman, and H. Orland, Phys. Rev. Lett. 79, 435 (1997)] This work focuses on the nonuniform size effects to molecular solvation energy and to ion current across a channel for real biomolecular systems. The main contributions are: (1) we prove that for solvation energy calculation with nonuniform size effects (through equilibrium SMPNP simulation), there exists a simplified approximation formulation which is the same as the widely used one in PB community. This approximate form avoids integration over the whole domain and makes energy calculations convenient. (2) Numerical calculations show that ionic size effects tend to negate the solvation effects, which indicates that a higher molecular solvation energy (lower absolute value) is to be predicted when ionic size effects are considered. For both calculations on a protein and a DNA fragment systems in a 0.5M 1:1 ionic solution, a difference about 10 kcal/mol in solvation energies is found between the PB and the SMPNP predictions. Moreover, it is observed that the solvation energy decreases as ionic strength increases, which behavior is similar as those predicted by the traditional PB equation (without size effect) and by the uniform size-modified Poisson-Boltzmann equation. (3) Nonequilibrium SMPNP simulations of ion permeation through a gramicidin A channel show that the ionic size effects lead to reduced ion current inside the channel compared with the results

  16. Controlling the rheological behavior of ceramic slurries and consolidated bodies: Interpenetrating networks and ion size effects

    NASA Astrophysics Data System (ADS)

    Fisher, Matthew Lyle

    counterion size on short range repulsive forces at high salt concentrations was investigated with alumina and silica slurries coagulated with the chlorides of Li+, Na+, K+, Cs+ and TMA+ (tetramethylammonium+). The results clearly show that the range of the repulsive forces correlated with the size of the unhydrated ion, namely stronger particle networks are achieved with smaller counterions. The findings are contradictory to the widely accepted hydration force model. Silica and alumina slurries were also studied at and below the iep where the indifferent electrolyte cations would not be expected to adsorb. It appears that a lyotropic sequence for excluded ions exists and is correlated to the hydration of ions and surfaces.

  17. [Size distributions of water-soluble inorganic ions in atmospheric aerosols in Fukang].

    PubMed

    Miao, Hong-Yan; Wen, Tian-Xue; Wang, Yue-Si; Liu, Zi-Rui; Wang, Li; Lan, Zhong-Dong

    2014-06-01

    To investigate the levels and size distributions of water soluble inorganic components, samples were collected with Andersen cascade sampler from Feb. 2011 to Feb. 2012, in Fukang, and were analyzed by IC. The variation trend, concentration level, composition, sources and size distribution of major ions during non-heating period were compared with heating period. Based on the specific samples, ionic compositions and size distributions were analyzed during heavy pollution, straw burning and spring planting periods. The results showed that inorganic components in Fukang were severely affected by heating. The total water soluble ions in fine and coarse particles during non-heating and heating periods were 11.17, 12.68 microg x m(-3) and 35.98, 22.22 microg x m(-3), respectively. SO4(2-) was mainly from saline-alkali soil, NO3(-) and NH4(+) were from resuspension of farmland soil during non-heating period, while SO4(2-), NO3(-) and NH4(+) were all from the fossil fuel consumption during the heating period. All ions were bimodal distribution during non-heating and heating periods. During the heating period, the particle size growth of SO4(2-), NO3(-) and NH4(+) in fine mode was found, SO4(2-) and NH4(+) peaked at 3.3-4.7 microm in coarse particles. Secondary pollutions were serious during heavy pollution days with high levels of secondary ions between 1.1 and 2.1 microm. Biomass burning obviously affected the size distribution of ions during the straw burning period and ions focused on smaller than 0.65 microm, while there were more soil dusts during spring planting periods and ions concentrated in larger than 3.3 microm.

  18. Development of PIXE, PESA and Transmission Ion Microscopy Capability to Measure Aerosols by Size and Time

    SciTech Connect

    Shutthanandan, Shuttha ); Thevuthasan, Theva ); Disselkamp, Robert S. ); Stroud, Ashley M.; Cavanagh, Andrew S.; Adams, Evan M.; Baer, Donald R. ); Barrie, Leonard A. ); Cliff, Steven S.; Jimenez-Cruz, M; Cahill, Thomas A.

    2002-01-01

    The elemental analysis of aerosol composition with high time and spatial resolution is crucial in the studies related to environmental issues such as human health, urban smog formation, regional visibility, and climate change. The effects of atmospheric aerosols are closely related to their size distribution, which plays a major role in understanding transport and removal processes and in pinpointing possible aerosol sources. Hence, there is a need for simultaneous measurements of compositions and particle size distribution of aerosols. We have developed a capability that consists of a combination of PIXE, PESA and STIM (same location on the sample) at the accelerator facility in Environmental Molecular Sciences Laboratory (EMSL) to address some of the needs associated with time series and size distribution. Simultaneous measurements of PIXE and PESA can be performed on aerosols collected using 3 stage improved rotating drum impactor by size (3 modes, 2.5 to 0.07 um) and time (2 mm rotation for every 8 hours) on a 20 cm long Teflon strips with a time resolution of 2 hours (using 500 micron size proton beam). Two Teflon strips can be mounted on the manipulator at the same time without breaking the vacuum through a load-lock. Movable and fixed surface barrier detectors are used for PESA and STIM measurements respectively. Preliminary measurements were carried out using the aerosol samples collected at the 62nd floor of Williams Tower in Houston, Texas. These aerosol samples were also analyzed by synchrotron x-ray microprobe (S-XRF) at Advanced Light Source (ALS) and the comparison of XRF and ion beam results along with the details of the capability will be discussed.

  19. Design, microfabrication, and analysis of micrometer-sized cylindrical ion trap arrays

    NASA Astrophysics Data System (ADS)

    Cruz, D.; Chang, J. P.; Fico, M.; Guymon, A. J.; Austin, D. E.; Blain, M. G.

    2007-01-01

    A description of the design and microfabrication of arrays of micrometer-scale cylindrical ion traps is offered. Electrical characterization and initial ion trapping experiments with a massively parallel array of 5μm internal radius (r0) sized cylindrical ion traps (CITs) are also described. The ion trap, materials, and design are presented and shown to be critical in achieving minimal trapping potential while maintaining minimal power consumption. The ion traps, fabricated with metal electrodes, have inner radii of 1, 2, 5, and 10μm and range from 5to24μm in height. The electrical characteristics of packaged ion trap arrays were measured with a vector network analyzer. The testing focused on trapping toluene (C7H8), mass 91, 92, or 93amu, in the 5μm sized CITs. Ions were formed via electron impact ionization and were ejected by turning off the rf voltage applied to the ring electrode; a current signal was collected at this time. Optimum ionization and trapping conditions, such as a sufficient pseudopotential well and high ionization to ion loss rate ratio (as determined by simulation), proved to be difficult to establish due to the high device capacitance and the presence of exposed dielectric material in the trapping region. However, evidence was obtained suggesting the trapping of ions in 1%-15% of the traps in the array. These first tests on micrometer-scale CITs indicated the necessary materials and device design modifications for realizing ultrasmall and low power ion traps.

  20. Design, microfabrication, and analysis of micrometer-sized cylindrical ion trap arrays

    SciTech Connect

    Cruz, D.; Chang, J. P.; Fico, M.; Guymon, A. J.; Austin, D. E.; Blain, M. G.

    2007-01-15

    A description of the design and microfabrication of arrays of micrometer-scale cylindrical ion traps is offered. Electrical characterization and initial ion trapping experiments with a massively parallel array of 5 {mu}m internal radius (r{sub 0}) sized cylindrical ion traps (CITs) are also described. The ion trap, materials, and design are presented and shown to be critical in achieving minimal trapping potential while maintaining minimal power consumption. The ion traps, fabricated with metal electrodes, have inner radii of 1, 2, 5, and 10 {mu}m and range from 5 to 24 {mu}m in height. The electrical characteristics of packaged ion trap arrays were measured with a vector network analyzer. The testing focused on trapping toluene (C{sub 7}H{sub 8}), mass 91, 92, or 93 amu, in the 5 {mu}m sized CITs. Ions were formed via electron impact ionization and were ejected by turning off the rf voltage applied to the ring electrode; a current signal was collected at this time. Optimum ionization and trapping conditions, such as a sufficient pseudopotential well and high ionization to ion loss rate ratio (as determined by simulation), proved to be difficult to establish due to the high device capacitance and the presence of exposed dielectric material in the trapping region. However, evidence was obtained suggesting the trapping of ions in 1%-15% of the traps in the array. These first tests on micrometer-scale CITs indicated the necessary materials and device design modifications for realizing ultrasmall and low power ion traps.

  1. Heavy Ion Radiation Effects Studies With Ion Photon Emission Microscopy

    SciTech Connect

    Branson, J. V.; Hattar, K.; Vizkelethy, G.; Powell, C. J.; Doyle, B. L.; Rossi, P.

    2011-06-01

    The development of a new radiation effects microscopy (REM) technique is crucial as emerging semiconductor technologies demonstrate smaller feature sizes and thicker back end of line (BEOL) layers. To penetrate these materials and still deposit sufficient energy into the device to induce single event effects, high energy heavy ions are required. Ion photon emission microscopy (IPEM) is a technique that utilizes coincident photons, which are emitted from the location of each ion impact to map out regions of radiation sensitivity in integrated circuits and devices, circumventing the obstacle of focusing high-energy heavy ions. Several versions of the IPEM have been developed and implemented at Sandia National Laboratories (SNL). One such instrument has been utilized on the microbeam line of the 6 MV tandem accelerator at SNL. Another IPEM was designed for ex-vacu use at the 88'' cyclotron at Lawrence Berkeley National Laboratory (LBNL). Extensive engineering is involved in the development of these IPEM systems, including resolving issues with electronics, event timing, optics, phosphor selection, and mechanics. The various versions of the IPEM and the obstacles, as well as benefits associated with each will be presented. In addition, the current stage of IPEM development as a user instrument will be discussed in the context of recent results.

  2. PLEPS study of ions implanted RAFM steels

    NASA Astrophysics Data System (ADS)

    Sojak, S.; Slugeň, V.; Egger, W.; Ravelli, L.; Petriska, M.; Veterníková, J.; Stacho, M.; Sabelová, V.

    2014-04-01

    Current nuclear power plants (NPP) require radiation, heat and mechanical resistance of their structural materials with the ability to stay operational during NPP planned lifetime. Radiation damage much higher, than in the current NPP, is expected in new generations of nuclear power plants, such as Generation IV and fusion reactors. Investigation of perspective structural materials for new generations of nuclear power plants is among others focused on study of reduced activation ferritic/martensitic (RAFM) steels. These steels have good characteristics as reduced activation, good resistance to volume swelling, good radiation, and heat resistance. Our experiments were focused on the study of microstructural changes of binary Fe-Cr alloys with different chromium content after irradiation, experimentally simulated by ion implantations. Fe-Cr alloys were examined, by Pulsed Low Energy Positron System (PLEPS) at FRM II reactor in Garching (Munich), after helium ion implantations at the dose of 0.1 C/cm2. The investigation was focused on the chromium effect and the radiation defects resistivity. In particular, the vacancy type defects (monovacancies, vacancy clusters) have been studied. Based on our previous results achieved by conventional lifetime technique, the decrease of the defects size with increasing content of chromium is expected also for PLEPS measurements.

  3. Improved conversion efficiency of Cr4+ ions in Cr: YAG transparent ceramics by optimization the particle sizes of sintering aids

    NASA Astrophysics Data System (ADS)

    Zhou, Tianyuan; Zhang, Le; Zhang, Jian; Yang, Hao; Liu, Peng; Chen, Yuanzhi; Qiao, Xuebin; Tang, Dingyuan

    2015-12-01

    In this study, fully dense chromium doped Y3Al5O12 ceramics with an average grain size of ∼3 μm were successfully fabricated by a solid state reactive sintering method under vacuum, and the effect of particle sizes of applied divalent dopants (CaO and MgO) on the optical properties, conversion efficiency of Cr4+ ions as well as microstructures of the fabricated Cr doped YAG ceramics were investigated. It was found that the conversion efficiency of Cr4+ ions in Cr: YAG ceramics depended strongly on the particle sizes of divalent dopants. For the sample doped with fine divalent dopants, the absorption coefficient at 1030 nm was 3.7 cm-1, which was 12 times higher than that of the sample doped with coarse divalent dopants.

  4. Field-size effect of physical doses in carbon-ion scanning using range shifter plates

    SciTech Connect

    Inaniwa, Taku; Furukawa, Takuji; Nagano, Ai; Sato, Shinji; Saotome, Naoya; Noda, Koji; Kanai, Tatsuaki

    2009-07-15

    A field-size effect of physical doses was studied in scanning irradiation with carbon ions. For the target volumes of 60x60x80, 40x40x80, and 20x20x80 mm{sup 3}, the doses along the beam axis within the spread-out Bragg peaks reduced to 99.4%, 98.2%, and 96.0% of the dose for the target of 80x80x80 mm{sup 3}, respectively. The present study revealed that the observed reductions can be compensated for by adopting the three-Gaussian form of lateral dose distributions for the pencil beam model used in the treatment planning system. The parameters describing the form were determined through the irradiation experiments making flat concentric squared frames with a scanned carbon beam. Since utilizing the three-Gaussian model in the dose optimization loop is at present time consuming, the correction for the field-size effect should be implemented as a ''predicted-dose scaling factor.'' The validity of this correction method was confirmed through the irradiation of a target of 20x20x80 mm{sup 3}.

  5. Estimating neutral nanoparticle steady-state size distribution and growth according to measurements of intermediate air ions

    NASA Astrophysics Data System (ADS)

    Tammet, H.; Komsaare, K.; Hõrrak, U.

    2013-09-01

    Continuous measurements of intermediate air ion size distributions were carried out in the small town Tartu, Estonia, from 1 April 2010 through 7 November 2011. The intermediate ions are charged aerosol particles of diameter 1.5-7.5 nm. In this paper we study what information about neutral nanoparticles of atmospheric aerosols can be drawn from the air ion measurements. Rough estimates of the growth rate and the size distribution of neutral nanoparticles were derived for the subset of measurements while the concentration of the intermediate ions was close to the median and remains in the range of 21 ± 2 cm-3. This criterion excludes the specific new particle formation events characterized with high concentration of intermediate ions and includes only most typical quiet periods between the events when the simultaneous growth, depletion and recharging of particles are described with steady-state equations. We estimated the growth rate of nanoparticles to be about 2 nm h-1 while the growth flux or apparent nucleation rate proved to be about 0.5 cm-3 s-1 at 3 nm and about 0.08 cm-3 s-1 at 7 nm. The results suggest that the process of new particle formation is not interrupted during the quiet periods between events of intensive nucleation of atmospheric aerosols.

  6. Laser photodetachment diagnostics of a 1/3-size negative hydrogen ion source for NBI

    SciTech Connect

    Geng, S.; Tsumori, K.; Nakano, H.; Kisaki, M.; Ikeda, K.; Takeiri, Y.; Osakabe, M.; Nagaoka, K.; Kaneko, O.

    2015-04-08

    To investigate the flows of charged particles in front of the plasma grid (PG) in a negative hydrogen ion source, the information of the local densities of electrons and negative hydrogen ions (H-) are necessary. For this purpose, the laser photodetachment is applied for pure hydrogen plasmas and Cs-seeded plasma in a 1/3-size negative hydrogen ion source in NIFS-NBI test stand. The H- density obtained by photodetachment is calibrated by the results from cavity ring-down (CRD). The pressure dependence and PG bias dependence of the local H- density are presented and discussed. The results show that H- density increases significantly by seeding Cs into the plasma. In Cs-seeded plasma, relativity exists between the H- ion density and plasma potential.

  7. Sample size calculation in metabolic phenotyping studies.

    PubMed

    Billoir, Elise; Navratil, Vincent; Blaise, Benjamin J

    2015-09-01

    The number of samples needed to identify significant effects is a key question in biomedical studies, with consequences on experimental designs, costs and potential discoveries. In metabolic phenotyping studies, sample size determination remains a complex step. This is due particularly to the multiple hypothesis-testing framework and the top-down hypothesis-free approach, with no a priori known metabolic target. Until now, there was no standard procedure available to address this purpose. In this review, we discuss sample size estimation procedures for metabolic phenotyping studies. We release an automated implementation of the Data-driven Sample size Determination (DSD) algorithm for MATLAB and GNU Octave. Original research concerning DSD was published elsewhere. DSD allows the determination of an optimized sample size in metabolic phenotyping studies. The procedure uses analytical data only from a small pilot cohort to generate an expanded data set. The statistical recoupling of variables procedure is used to identify metabolic variables, and their intensity distributions are estimated by Kernel smoothing or log-normal density fitting. Statistically significant metabolic variations are evaluated using the Benjamini-Yekutieli correction and processed for data sets of various sizes. Optimal sample size determination is achieved in a context of biomarker discovery (at least one statistically significant variation) or metabolic exploration (a maximum of statistically significant variations). DSD toolbox is encoded in MATLAB R2008A (Mathworks, Natick, MA) for Kernel and log-normal estimates, and in GNU Octave for log-normal estimates (Kernel density estimates are not robust enough in GNU octave). It is available at http://www.prabi.fr/redmine/projects/dsd/repository, with a tutorial at http://www.prabi.fr/redmine/projects/dsd/wiki. PMID:25600654

  8. Protein adsorption on DEAE ion-exchange resins with different ligand densities and pore sizes.

    PubMed

    Lu, Hui-Li; Lin, Dong-Qiang; Zhu, Mi-Mi; Yao, Shan-Jing

    2012-11-01

    Ion exchange chromatography (IEC) is a common and powerful technique for the purification of proteins. The ligand density and pore properties of ion-exchange resins have significant effects on the separation behaviors of protein, however, the understandings are quite limited. In the present work, the adsorption isotherms of bovine serum albumin (BSA) and human serum albumin (HSA) were investigated systematically with series of diethylaminoethyl (DEAE) ion-exchange resins, which have different ligand densities and pore sizes. The Langmuir equation was used to fit the experimental data and the influences of ligand density and pore size on the saturated adsorption capacity and the dissociation constant were discussed. The zeta potentials and hydrodynamic diameters of proteins at different pHs were also measured, and the surface charge characteristics of proteins and the adsorption mechanism were discussed. The results demonstrated that the ligand density, pore size, and protein properties affect the protein adsorption capacities in an integrative way. An integrative parameter was introduced to describe the complicated effects of ligand density and pore size on the protein adsorption. For a given protein, the ligand density and pore size should be optimized for improving the protein adsorption.

  9. Lithium-Ion Cell Storage Study

    NASA Technical Reports Server (NTRS)

    Lee, Leonine; Rao, Gopalkrishna M.

    2000-01-01

    This viewgraph presentation reviews the issues concerning storage of lithium ion batteries. The presentation outlines tests used to establish a best long term storage for the lithium ion cells. Another objective of the study was to determine the preferred solstice condition for the lithium ion chemistry (polymer and liquid electrolyte). It also compared voltage clamped with trickle charge storage. The tests and results are reviewed

  10. Ion beam shaping of Au nanoparticles in silica: Particle size and concentration dependence

    SciTech Connect

    Dawi, E. A.; Mink, M. P.; Vredenberg, A. M.; Habraken, F. H. P. M.; Rizza, G.

    2009-04-01

    Irradiation with swift heavy ions of spherical Au nanoparticles confined within a silica matrix shapes them into prolate nanorods and nanowires whose principal axes are aligned along the beam direction. In the present paper, we investigate the role that is played by the initial nanoparticle size and concentration in this so-called ion-shaping mechanism. We have produced silica films wherein Au nanoparticles with average diameters of 15, 30, and 45 nm were embedded within a single plane and have irradiated these films at 300 K at normal incidence with 18, 25, and 54 MeV Ag ions. We demonstrate the existence of both threshold and saturation fluences for the elongation effects mentioned. The values of these critical fluences depend both on the ion energy and the initial nanoparticle size. Moreover, we show that 45 nm Au particles are not deformed when irradiated with 18 MeV Ag ions, such that this value corresponds to an energy threshold for the deformation process. As far as the influence of the nanoparticle concentration on the shaping characteristics is concerned, we have found that above the critical irradiation fluence, the deformation effect becomes very sensitive to the initial concentration of the nanoparticles.

  11. The importance of ion size and electrode curvature on electrical double layers in ionic liquids

    SciTech Connect

    Feng, G.; Qiao, R.; Huang, J; Dai, S.; Sumpter, B. G.; Meunier, V.

    2011-01-01

    Room-temperature ionic liquids (ILs) are an emerging class of electrolytes for supercapacitors. We investigate the effects of ion size and electrode curvature on the electrical double layers (EDLs) in two ILs 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF{sub 6}], using a combination of molecular dynamics (MD) and quantum density functional theory (DFT) simulations. The sizes of the counter-ion and co-ion affect the ion distribution and orientational structure of EDLs. The EDL capacitances near both planar and cylindrical electrodes were found to follow the order: [BMIM][Cl] (near the positive electrode) > [BMIM][PF{sub 6}] (near the positive electrode) ≈ [BMIM][Cl] (near the negative electrode) ≈ [BMIM][PF{sub 6}] (near the negative electrode). The EDL capacitance was also found to increase as the electrode curvature increases. These capacitance data can be fit to the Helmholtz model and the recently proposed exohedral electrical double-cylinder capacitor (xEDCC) model when the EDL thickness is properly parameterized, even though key features of the EDLs in ILs are not accounted for in these models. To remedy the shortcomings of existing models, we propose a “Multiple Ion Layers with Overscreening” (MILO) model for the EDLs in ILs that takes into account two critical features of such EDLs, i.e., alternating layering of counter-ions and co-ions and charge overscreening. The capacitance computed from the MILO model agrees well with the MD prediction. Although some input parameters of the MILO model must be obtained from MD simulations, the MILO model may provide a new framework for understanding many important aspects of EDLs in ILs (e.g., the variation of EDL capacitance with the electrode potential) that are difficult to interpret using classical EDL models and experiments.

  12. The Importance of Ion Size and Electrode Curvature on Electrical Double Layers in Ionic Liquids

    SciTech Connect

    Feng, Guang; Qiao, Rui; Huang, Jingsong; Dai, Sheng; Sumpter, Bobby G; Meunier, Vincent

    2010-01-01

    Room-temperature ionic liquids (ILs) are an emerging class of electrolytes for supercapacitors. We investigate the effects of ion size and electrode curvature on the electrical double layers (EDLs) in two ILs 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF(6)], using a combination of molecular dynamics (MD) and quantum density functional theory (DFT) simulations. The sizes of the counter-ion and co-ion affect the ion distribution and orientational structure of EDLs. The EDL capacitances near both planar and cylindrical electrodes were found to follow the order: [BMIM][Cl] (near the positive electrode) > [BMIM][PF(6)] (near the positive electrode) {approx} [BMIM][Cl] (near the negative electrode) {approx} [BMIM][PF(6)] (near the negative electrode). The EDL capacitance was also found to increase as the electrode curvature increases. These capacitance data can be fit to the Helmholtz model and the recently proposed exohedral electrical double-cylinder capacitor (xEDCC) model when the EDL thickness is properly parameterized, even though key features of the EDLs in ILs are not accounted for in these models. To remedy the shortcomings of existing models, we propose a 'Multiple Ion Layers with Overscreening' (MILO) model for the EDLs in ILs that takes into account two critical features of such EDLs, i.e., alternating layering of counter-ions and co-ions and charge overscreening. The capacitance computed from the MILO model agrees well with the MD prediction. Although some input parameters of the MILO model must be obtained from MD simulations, the MILO model may provide a new framework for understanding many important aspects of EDLs in ILs (e.g., the variation of EDL capacitance with the electrode potential) that are difficult to interpret using classical EDL models and experiments.

  13. Effects of dust size distribution on dust negative ion acoustic solitary waves in a magnetized dusty plasma

    SciTech Connect

    Ma, Yi-Rong; Qi, Xin; Sun, Jian-An; Duan, Wen-Shan; Yang, Lei

    2013-08-15

    Dust negative ion acoustic solitary waves in a magnetized multi-ion dusty plasma containing hot isothermal electron, ions (light positive ions and heavy negative ions) and extremely massive charge fluctuating dust grains are investigated by employing the reductive perturbation method. How the dust size distribution affect the height and the thickness of the nonlinear solitary wave are given. It is noted that the characteristic of the solitary waves are different with the different dust size distribution. The magnitude of the external magnetic field also affects the solitary wave form.

  14. Lithium ion rechargeable systems studies

    SciTech Connect

    Levy, S.C.; Lasasse, R.R.; Cygan, R.T.; Voigt, J.A.

    1995-02-01

    Lithium ion systems, although relatively new, have attracted much interest worldwide. Their high energy density, long cycle life and relative safety, compared with metallic lithium rechargeable systems, make them prime candidates for powering portable electronic equipment. Although lithium ion cells are presently used in a few consumer devices, e.g., portable phones, camcorders, and laptop computers, there is room for considerable improvement in their performance. Specific areas that need to be addressed include: (1) carbon anode--increase reversible capacity, and minimize passivation; (2) cathode--extend cycle life, improve rate capability, and increase capacity. There are several programs ongoing at Sandia National Laboratories which are investigating means of achieving the stated objectives in these specific areas. This paper will review these programs.

  15. Radical Ions of Cycloparaphenylenes: Size Dependence Contrary to the Neutral Molecules.

    PubMed

    Fujitsuka, Mamoru; Tojo, Sachiko; Iwamoto, Takahiro; Kayahara, Eiichi; Yamago, Shigeru; Majima, Tetsuro

    2014-07-01

    Cycloparaphenylenes (CPPs) have attracted wide attention because of their interesting properties owing to distorted and strained aromatic systems and radially oriented p orbitals. For application of CPPs, information on their charged states (radical cation and radical anion) is essential. Here, we measured absorption spectra of the radical cations and the radical anions of CPPs with various ring sizes over a wide spectral region by means of radiation chemical methods. The peak position of the near-IR bands for both the radical cation and the radical anion shifted to lower energies with an increase in the ring size. This trend is contrary to what is observed for transitions between the HOMO and LUMO of the neutral CPP. The observed spectra of the CPP radical ions were reasonably assigned based on time-dependent density functional theory. These results indicate that the next HOMO and the next LUMO levels are important in the electronic transitions of radical ions. PMID:26279550

  16. Finite-size effects on plasmonlike excitations in relativistic heavy-ion collisions

    SciTech Connect

    Trueman, T.L. )

    1992-03-15

    The modifications of plasmonlike excitations in hot hadronic or quark-gluon matter due to the finite size of the systems that will be produced in relativistic heavy-ion collisions are investigated. It is shown that the relevant parameter is {ital RM}{sup 2}/{vert bar}{bold q}{vert bar} where {ital R} is the size of the system, {ital M} is the mass of the plasmon in an infinite system, and {bold q} is its three-momentum in the plasmon. If {ital RM}{sup 2}/{vert bar}{bold q}{vert bar}{much lt}1, the plasmon excitations will not be produced. This has important implications for plasmons generated in heavy-ion collisions by electromagnetic interactions which have been suggested by some authors.

  17. Size-dependent stability toward dissociation and ligand binding energies of phosphine-ligated gold cluster ions

    SciTech Connect

    Johnson, Grant E.; Priest, Thomas A.; Laskin, Julia

    2014-01-01

    The stability of sub-nanometer size gold clusters ligated with organic molecules is of paramount importance to the scalable synthesis of monodisperse size-selected metal clusters with highly tunable chemical and physical properties. For the first time, a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS) equipped with surface induced dissociation (SID) has been employed to investigate the time and collision energy resolved fragmentation behavior of cationic doubly charged gold clusters containing 7-9 gold atoms and 6-7 triphenylphosphine (TPP) ligands prepared by reduction synthesis in solution. The TPP ligated gold clusters are demonstrated to fragment through three primary dissociation pathways: (1) Loss of a neutral TPP ligand from the precursor gold cluster, (2) asymmetric fission and (3) symmetric fission and charge separation of the gold core resulting in formation of complementary pairs of singly charged fragment ions. Threshold energies and activation entropies of these fragmentation pathways have been determined employing Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of the experimental SID data. It is demonstrated that the doubly charged cluster ion containing eight gold atoms and six TPP ligands, (8,6)2+, exhibits exceptional stability compared to the other cationic gold clusters examined in this study due to its large ligand binding energy of 1.76 eV. Our findings demonstrate the dramatic effect of the size and extent of ligation on the gas-phase stability and preferred fragmentation pathways of small TPP-ligated gold clusters.

  18. A Study of Single Pass Ion Effects at the ALS

    SciTech Connect

    Byrd, J.M.; Thomson, J.; Chao, A.W.; Heifets, S.; Minty, M.G.; Seeman, J.T.; Stupakov, G.V.; Zimmermann, F.; Raubenheimer, T.O.; /CERN

    2011-09-13

    We report the results of experiments on a 'fast beam-ion instability' at the Advanced Light Source (ALS). This ion instability, which can arise even when the ions are not trapped over multiple beam passages, will likely be important for many future accelerators. In our experiments, we filled the ALS storage ring with helium gas, raising the pressure approximately two orders of magnitude above the nominal pressure. With gaps in the bunch train large enough to avoid conventional (multi-turn) ion trapping, we observed a factor of 2-3 increase in the vertical beam size along with coherent beam oscillations which increased along the bunch train. Ion trapping has long been recognized as a potential limitation in electron storage rings. The ions, generated by beam-gas collisions, become trapped in the negative potential of the beam and accumulate over multiple beam passages. The trapped ions are then observed to cause a number of deleterious effects such as an increasing beam phase space, a broadening and shifting of the beam transverse oscillation frequencies (tunes), collective beam instabilities, and beam lifetime reductions. All of these effects are of concern for the next generation of accelerators, such as the B-factories or damping rings for future linear colliders, which will store high beam currents with closely spaced bunches and ultra-low beam emittances. One of the standard solutions used to prevent ion trapping is to include a gap in the bunch train which is long compared to the bunch spacing. In this case, the ions are first strongly-focused by the passing electron bunches and then over-focused in the gap. With a sufficiently large gap, the ions can be driven to large amplitudes where they form a diffuse halo and do not affect the beam. In this paper, we describe experiments that study a new regime of transient ion instabilities predicted to arise in future electron storage rings, and linacs with bunch trains. These future rings and linacs, which will be

  19. Sampling of ions at atmospheric pressure: ion transmission and ion energy studied by simulation and experiment

    NASA Astrophysics Data System (ADS)

    Große-Kreul, Simon; Hübner, Simon; Benedikt, Jan; von Keudell, Achim

    2016-04-01

    Mass spectrometry of ions from atmospheric pressure plasmas is a challenging diagnostic method that has been applied to a large variety of cold plasma sources in the past. However, absolute densities can usually not be obtained, moreover, the process of sampling of ions and neutrals from such a plasma inherently influences the measured composition. These issues are studied in this contribution by a combination of experimental and numerical methods. Different numerical domains are sequentially coupled to calculate the ion transmission from the source to the mass analyzer. It is found that the energy of the sampled ions created by a radio-frequency microplasma operated in a He-N2 mixture at atmospheric pressure is of the order of 0.1 eV and that it depends linearly on the ion mass in good agreement with the expectation for seeded particles accelerated in a supersonic expansion. Moreover, the measured ion energy distribution from an afterglow of an atmospheric pressure plasma can be reproduced on basis of the particle trajectories in the sampling system. Eventually, an estimation of the absolute flux of ions to the detector is deduced.

  20. Application of ion implantation to electrochemical studies

    SciTech Connect

    Vallet, C.E.; White, C.W.

    1990-01-01

    The application of ion implantation to electrochemical studies is illustrated with a study of electrocatalysis of the chlorine evolution reaction at RuO{sub 2}, IrO{sub 2}, TiO{sub 2} mixed oxide anodes in chloride solutions. Electrode/solution interfaces of well defined catalyst composition are generated in a reproducible manner by implantation of Ru (or Ir) into Ti followed by in situ oxidation of the near surface titanium alloys. Ion implantation enables the tailoring on an atomic scale of an electrochemical interface. Analysis by Rutherford backscattering adds the ability of quantitative mechanistic study in terms of actual ion concentration at the interface. In addition, ion implantation, as a processing technique, creates new materials with improved properties which may have future practical use in catalytic materials.

  1. Efficient removal of heavy metal ions with biopolymer template synthesized mesoporous titania beads of hundreds of micrometers size.

    PubMed

    Wu, Na; Wei, Huanhuan; Zhang, Lizhi

    2012-01-01

    We demonstrated that mesoporous titania beads of uniform size (about 450 μm) and high surface area could be synthesized via an alginate biopolymer template method. These mesoporous titania beads could efficiently remove Cr(VI), Cd(II), Cr(III), Cu(II), and Co(II) ions from simulated wastewater with a facile subsequent solid-liquid separation because of their large sizes. We chose Cr(VI) removal as the case study and found that each gram of these titania beads could remove 6.7 mg of Cr(VI) from simulated wastewater containing 8.0 mg·L(-1) of Cr(VI) at pH = 2.0. The Cr(VI) removal process was found to obey the Langmuir adsorption model and its kinetics followed pseudo-second-order rate equation. The Cr(VI) removal mechanism of titania beads might be attributed to the electrostatic adsorption of Cr(VI) ions in the form of negatively charged HCrO(4)(-) by positively charged TiO(2) beads, accompanying partial reduction of Cr(VI) to Cr(III) by the reductive surface hydroxyl groups on the titania beads. The used titania beads could be recovered with 0.1 mol·L(-1) of NaOH solution. This study provides a promising micro/nanostructured adsorbent with easy solid-liquid separation property for heavy metal ions removal. PMID:22129207

  2. Efficient removal of heavy metal ions with biopolymer template synthesized mesoporous titania beads of hundreds of micrometers size.

    PubMed

    Wu, Na; Wei, Huanhuan; Zhang, Lizhi

    2012-01-01

    We demonstrated that mesoporous titania beads of uniform size (about 450 μm) and high surface area could be synthesized via an alginate biopolymer template method. These mesoporous titania beads could efficiently remove Cr(VI), Cd(II), Cr(III), Cu(II), and Co(II) ions from simulated wastewater with a facile subsequent solid-liquid separation because of their large sizes. We chose Cr(VI) removal as the case study and found that each gram of these titania beads could remove 6.7 mg of Cr(VI) from simulated wastewater containing 8.0 mg·L(-1) of Cr(VI) at pH = 2.0. The Cr(VI) removal process was found to obey the Langmuir adsorption model and its kinetics followed pseudo-second-order rate equation. The Cr(VI) removal mechanism of titania beads might be attributed to the electrostatic adsorption of Cr(VI) ions in the form of negatively charged HCrO(4)(-) by positively charged TiO(2) beads, accompanying partial reduction of Cr(VI) to Cr(III) by the reductive surface hydroxyl groups on the titania beads. The used titania beads could be recovered with 0.1 mol·L(-1) of NaOH solution. This study provides a promising micro/nanostructured adsorbent with easy solid-liquid separation property for heavy metal ions removal.

  3. Effects of size and concentration on diffusion-induced stress in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Ma, Zengsheng; Gao, Xiang; Wang, Yan; Lu, Chunsheng

    2016-07-01

    Capacity fade of lithium-ion batteries induced by chemo-mechanical degradation during charge-discharge cycles is the bottleneck in design of high-performance batteries, especially high-capacity electrode materials. Stress generated due to diffusion-mechanical coupling in lithium-ion intercalation and deintercalation is accompanied by swelling, shrinking, and even micro-cracking. In this paper, we propose a theoretical model for a cylindrical nanowire electrode by combining the bond-order-length-strength and diffusion theories. It is shown that size and concentration have a significant influence on the stress fields in radial, hoop, and axial directions. This can explain why a smaller electrode with a huge volume change survives in the lithiation/delithiation process.

  4. Effect of Nuclear Size on the Stopping Power of Ultrarelativistic Heavy Ions

    SciTech Connect

    Datz, S.; Krause, H.F.; Vane, C.R.; Knudsen, H.; Grafstroem, P.; Schuch, R.H.

    1996-09-01

    A new formulation for the theory of electronic stopping power of ions at relativistic energies has been proposed by Lindhard and So/rensen (LS). In it, they find that, at sufficiently high energy, nuclear size effects should act to reduce the momentum transfer to electrons and hence the stopping power. To test this result, we passed beams of 33.2-TeV {sup 208}Pb ions ({gamma}=168) from the CERN-SPS through targets of C, Si, Cu, Sn, and Pb, and measured energy loss and beam broadening. The LS theory for stopping power is confirmed, but with a slight drift upward from theory for high-{ital Z} targets. A drastic decrease in energy straggling (factor of {approximately}14) predicted by LS cannot be deconvoluted from the multiple Coulomb scattering distribution. {copyright} {ital 1996 The American Physical Society.}

  5. Propagation of electro-kinetic waves in magnetized GaN semiconductor with nano-sized ion colloids

    SciTech Connect

    Saxena, Ajay; Sharma, Giriraj; Jat, K. L.; Rishi, M. P.

    2015-07-31

    Based on hydrodynamic model of multi-component plasma, an analytical study on propagation of longitudinal electro-kinetic (LEK) waves in wurtzite and zincblende structures of GaN is carried out. Nano-sized ion colloids (NICs) are embedded in the sample by the technique of ion-implantation. The implanted NICs are considered massive by an order as compared to the host lattice points and do not participate in Based LEK perturbations. Though, the NICs are continuously bombarded by the electrons as well as the holes yet, the former acquires a net negative charge owing to relatively higher mobility of electrons and consequently results into depletion of electron density in the medium. It i s found that the presence of charged NICs significantly modifies the dispersion and amplification characteristics of LEK waves in magnetized GaN semiconductor plasma and their role becomes increasingly effective as the fraction of charge on them increases.

  6. Computing excess functions of ionic solutions: the smaller-ion shell model versus the primitive model. 2. Ion-size parameters.

    PubMed

    Fraenkel, Dan

    2015-01-13

    A recent Monte Carlo (MC) simulation study of the primitive model (PM) of ionic solutions ( Abbas, Z. et al. J. Phys. Chem. B 2009 , 113 , 5905 ) has resulted in an extensive "mapping" of real aqueous solutions of 1-1, 2-1, and 3-1 binary electrolytes and a list of "recommended ionic radii" for many ions. For the smaller cations, the model-experiment fitting process gave much larger radii than the respective crystallographic radii, and those cations were therefore claimed to be hydrated. In Part 1 (DOI 10.1021/ct5006938 ) of the present work, the above study for the unrestricted PM - dubbed MC-UPM - has been confronted with the Smaller-ion Shell (SiS) treatment ( Fraenkel, D. Mol. Phys. 2010 , 108 , 1435 ), or "DH-SiS", by comparing the range and quality of model-experiment fits of the mean ionic activity coefficient as a function of ionic concentration. Here I compare the ion-size parameters (ISPs) of "best fit" of the two models and argue that since ISPs derived from DH-SiS are identical with (or close to) crystallographic or thermochemical ionic diameters for both cations and anions, and they do not depend on the counterion - they are more reliable, as physicochemical entities, than the PM-derived "recommended ionic radii".

  7. Regulating the Size and Stabilization of Lipid Raft-Like Domains and Using Calcium Ions as Their Probe

    NASA Astrophysics Data System (ADS)

    Raviv, Uri; Szekely, Or

    2012-02-01

    In this paper, we apply means to probe, stabilize and control the size of lipid raft-like domains in vitro. In biomembranes the size of lipid rafts is ca. 10 - 30 nm. In vitro, mixing saturated and unsaturated lipids results in micro-domains, which are unstable and coalesce. Using solution X-ray scattering, we studied the structure of binary and ternary lipid mixtures in the presence of calcium ions. Three lipids were used: saturated, unsaturated and a hybrid (1-saturated-2-unsaturated) lipid that is predominant in the phospholipids of cellular membranes. Only membranes composed of the saturated lipid can adsorb calcium ions, become charged and therefore considerably swell. The selective calcium affinity was used to show that binary mixtures, containing the saturated lipid, phase separated into large-scale domains. Our data suggests that by introducing the hybrid lipid to a mixture of the saturated and unsaturated lipids, the size of the domains decreased with the concentration of the hybrid lipid, until the three lipids could completely mix. We attribute this behavior to the tendency of the hybrid lipid to act as a line-active co-surfactant that can easily reside at the interface between the saturated and the unsaturated lipids and reduce the line-tension between them.

  8. Size-to-charge dispersion of collision-induced dissociation product ions for enhancement of structural information and product ion identification.

    PubMed

    Zinnel, Nathanael F; Russell, David H

    2014-05-20

    Ion mobility is used to disperse product ions formed by collision-induced dissociation (CID) on the basis of charge state and size-to-charge ratio. We previously described an approach for combining CID with ion mobility mass spectrometry (IM-MS) for dispersing fragment ions along charge state specific trend lines (Zinnel, N. F.; Pai, P. J.; Russell, D. H. Anal. Chem. 2012, 84, 3390; Sowell, R. A.; Koeniger, S. L.; Valentine, S. J.; Moon, M. H.; Clemmer, D. E. J. Am. Soc. Mass Spectrom. 2004, 15, 1341; McLean, J. A.; Ruotolo, B. T.; Gillig, K. J.; Russell, D. H. Int. J. Mass Spectrom. 2005, 240, 301), and this approach was used to assign metal ion binding sites for human metallothionein protein MT-2a (Chen, S. H.; Russell, W. K.; Russell, D. H. Anal. Chem. 2013, 85, 3229). Here, we use this approach to distinguish b-type N-terminal fragment ions from both internal fragment ions and y-type C-terminal fragment ions. We also show that in some cases specific secondary structural elements, viz., extended coils or helices, can be obtained for the y-type fragment ions series. The advantage of this approach is that product ion identity can be correlated to gas-phase ion structure, which provides rapid identification of the onset and termination of extended coil structure in peptides.

  9. Depth resolution at organic interfaces sputtered by argon gas cluster ions: the effect of energy, angle and cluster size.

    PubMed

    Seah, M P; Spencer, S J; Havelund, R; Gilmore, I S; Shard, A G

    2015-10-01

    An analysis is presented of the effect of experimental parameters such as energy, angle and cluster size on the depth resolution in depth profiling organic materials using Ar gas cluster ions. The first results are presented of the incident ion angle dependence of the depth resolution, obtained at the Irganox 1010 to silicon interface, from profiles by X-ray photoelectron spectrometry (XPS). By analysis of all relevant published depth profile data, it is shown that such data, from delta layers in secondary ion mass spectrometry (SIMS), correlate with the XPS data from interfaces if it is assumed that the monolayers of the Irganox 1010 adjacent to the wafer substrate surface have an enhanced sputtering rate. SIMS data confirm this enhancement. These results show that the traditional relation for the depth resolution, FWHM = 2.1Y(1/3) or slightly better, FWHM = P(X)Y(1/3)/n(0.2), where n is the argon gas cluster size, and P(X) is a parameter for each material are valid both at the 45° incidence angle of the argon gas cluster sputtering ions used in most studies and at all angles from 0° to 80°. This implies that, for optimal depth profile resolution, 0° or >75° incidence may be significantly better than the 45° traditionally used, especially for the low energy per atom settings required for the best resolved profiles in organic materials. A detailed analysis, however, shows that the FWHM requires a constant contribution added in quadrature to the above such that there are minimal improvements at 0° or greater than 75°. A critical test at 75° confirms the presence of this constant contribution.

  10. Size-restricted proton transfer within toluene-methanol cluster ions.

    PubMed

    Chiang, Chi-Tung; Shores, Kevin S; Freindorf, Marek; Furlani, Thomas; DeLeon, Robert L; Garvey, James F

    2008-11-20

    To understand the interaction between toluene and methanol, the chemical reactivity of [(C6H5CH3)(CH3OH) n=1-7](+) cluster ions has been investigated via tandem quadrupole mass spectrometry and through calculations. Collision Induced Dissociation (CID) experiments show that the dissociated intracluster proton transfer reaction from the toluene cation to methanol clusters, forming protonated methanol clusters, only occurs for n = 2-4. For n = 5-7, CID spectra reveal that these larger clusters have to sequentially lose methanol monomers until they reach n = 4 to initiate the deprotonation of the toluene cation. Metastable decay data indicate that for n = 3 and n = 4 (CH3OH)3H(+) is the preferred fragment ion. The calculational results reveal that both the gross proton affinity of the methanol subcluster and the structure of the cluster itself play an important role in driving this proton transfer reaction. When n = 3, the cooperative effect of the methanols in the subcluster provides the most important contribution to allow the intracluster proton transfer reaction to occur with little or no energy barrier. As n >or= 4, the methanol subcluster is able to form ring structures to stabilize the cluster structures so that direct proton transfer is not a favored process. The preferred reaction product, the (CH3OH)3H(+) cluster ion, indicates that this size-restricted reaction is driven by both the proton affinity and the enhanced stability of the resulting product.

  11. Postage stamp-sized array sensor for the sensitive screening test of heavy-metal ions.

    PubMed

    Zhang, Yu; Li, Xiao; Li, Hui; Song, Ming; Feng, Liang; Guan, Yafeng

    2014-10-01

    The sensitive determination of heavy-metal ions has been widely investigated in recent years due to their threat to the environment and to human health. Among various analytical detection techniques, inexpensive colorimetric testing papers/strips play a very important role. The limitation, however, is also clear: the sensitivity is usually low and the selectivity is poor. In this work, we have developed a postage stamp-sized array sensor composed of nine commercially available heterocyclic azo indicators. Combining filtration-based enrichment with an array of technologies-based pattern-recognition, we have obtained the discrimination capability for seven heavy-metal ions (Hg(2+), Pb(2+), Ag(+), Ni(2+), Cu(2+), Zn(2+), and Co(2+)) at their Chinese wastewater discharge standard concentrations. The allowable detection level of Hg(2+) was down to 0.05 mg L(-1). The heavy-metal ions screening test was readily achieved using a standard chemometric approach. And the array sensor applied well in real water samples.

  12. Postage stamp-sized array sensor for the sensitive screening test of heavy-metal ions.

    PubMed

    Zhang, Yu; Li, Xiao; Li, Hui; Song, Ming; Feng, Liang; Guan, Yafeng

    2014-10-01

    The sensitive determination of heavy-metal ions has been widely investigated in recent years due to their threat to the environment and to human health. Among various analytical detection techniques, inexpensive colorimetric testing papers/strips play a very important role. The limitation, however, is also clear: the sensitivity is usually low and the selectivity is poor. In this work, we have developed a postage stamp-sized array sensor composed of nine commercially available heterocyclic azo indicators. Combining filtration-based enrichment with an array of technologies-based pattern-recognition, we have obtained the discrimination capability for seven heavy-metal ions (Hg(2+), Pb(2+), Ag(+), Ni(2+), Cu(2+), Zn(2+), and Co(2+)) at their Chinese wastewater discharge standard concentrations. The allowable detection level of Hg(2+) was down to 0.05 mg L(-1). The heavy-metal ions screening test was readily achieved using a standard chemometric approach. And the array sensor applied well in real water samples. PMID:25068762

  13. Characterization of tip size and geometry of the pipettes used in scanning ion conductance microscopy.

    PubMed

    Tognoni, Elisabetta; Baschieri, Paolo; Ascoli, Cesare; Pellegrini, Monica; Pellegrino, Mario

    2016-04-01

    Scanning ion-conductance microscopy (SICM) belongs to the family of scanning-probe microscopies. The spatial resolution of these techniques is limited by the size of the probe. In SICM the probe is a pipette, obtained by heating and pulling a glass capillary tubing. The size of the pipette tip is therefore an important parameter in SICM experiments. However, the characterization of the tip is not a consolidated routine in SICM experimental practice. In addition, potential and limitations of the different methods available for this characterization may not be known to all users. We present an overview of different methods for characterizing size and geometry of the pipette tip, with the aim of collecting and facilitating the use of several pieces of information appeared in the literature in a wide interval of time under different disciplines. In fact, several methods that have been developed for pipettes used in cell physiology can be also fruitfully employed in the characterization of the SICM probes. The overview includes imaging techniques, such as scanning electron microscopy and atomic Force microscopy, and indirect methods, which measure some physical parameter related to the size of the pipette. Examples of these parameters are the electrical resistance of the pipette filled with a saline solution and the surface tension at the pipette tip. We discuss advantages and drawbacks of the methods, which may be helpful in answering a wide range of experimental questions. PMID:26826619

  14. AFE ion mass spectrometer design study

    NASA Technical Reports Server (NTRS)

    Wright, Willie

    1989-01-01

    This final technical report covers the activities engaged in by the University of Texas at Dallas, Center for Space Sciences in conjunction with the NASA Langley Research Center, Systems Engineering Division in design studies directed towards defining a suitable ion mass spectrometer to determine the plasma parameter around the Aeroassisted Flight Experiment vehicle during passage through the earth's upper atmosphere. Additional studies relate to the use of a Langmuir probe to measure windward ion/electron concentrations and temperatures. Selected instrument inlet subsystems were tested in the NASA Ames Arc-Jet Facility.

  15. Particle model of full-size ITER-relevant negative ion source.

    PubMed

    Taccogna, F; Minelli, P; Ippolito, N

    2016-02-01

    This work represents the first attempt to model the full-size ITER-relevant negative ion source including the expansion, extraction, and part of the acceleration regions keeping the mesh size fine enough to resolve every single aperture. The model consists of a 2.5D particle-in-cell Monte Carlo collision representation of the plane perpendicular to the filter field lines. Magnetic filter and electron deflection field have been included and a negative ion current density of j(H(-)) = 660 A/m(2) from the plasma grid (PG) is used as parameter for the neutral conversion. The driver is not yet included and a fixed ambipolar flux is emitted from the driver exit plane. Results show the strong asymmetry along the PG driven by the electron Hall (E × B and diamagnetic) drift perpendicular to the filter field. Such asymmetry creates an important dis-homogeneity in the electron current extracted from the different apertures. A steady state is not yet reached after 15 μs.

  16. Planetary size comparisons: A photographic study

    NASA Technical Reports Server (NTRS)

    Meszaros, S. P.

    1983-01-01

    Over the past two decades NASA spacecraft missions obtained photographs permitting accurate size measurements of the planets and moons, and their surface features. Planetary global views are displayed at the same scale, in each picture to allow visual size comparisons. Additionally, special geographical features on some of the planets are compared with selected Earth areas, again at the same scale. Artist renderings and estimated sizes are used for worlds not yet reached by spacecraft. Included with each picture is number designation for use in ordering copies of the photos.

  17. Studies in ion source development for application in heavy ion fusion

    SciTech Connect

    Kapica, Jonathan G.

    2004-05-30

    The overall purpose of these experiments is to contribute to the development of ion injector technology in order to produce a driver for use in a heavy-ion-fusion (HIF) power generating facility. The overall beam requirements for HIF are quite demanding; a short list of the constraints is the following: (1) Low cost (a large portion of overall cost will come from the beam system); (2) Bright, low emittance beam; (3) Total beam energy 5MJ; (4) Spot size 3mm (radius); (5) Pulse Duration 10ns; (6) Current on target 40kA; (7) Repetition Rate 5Hz; (8) Standoff from target 5m; and (9) Transverse Temp < 1 keV. The reasons for employing ion beams in inertial fusion systems become obvious when the repetition rate required is considered. While laser drivers are useful in producing a proof-of-concept, they will be incapable of application in power generation. Consequently attempts in the U.S. to achieve a power generating system make use of linear ion accelerators. It is apparent that the accelerator system requires the highest quality input as obtainable. Therefore injector design is an essential portion of the entire inertial fusion system. At Lawrence Berkeley and Lawrence Livermore National Laboratories experiments are being conducted using two injector formats. For this project I have conducted a series of studies using both. The next two sections provide a brief description of the sources used for my experiments.

  18. Studies of ion sputtered silicon(111) surfaces

    NASA Astrophysics Data System (ADS)

    Brown, Ari-David

    A comprehensive study of morphological evolution of regular features formed on ion sputtered Si(111) surfaces was conducted. The physics governing feature formation was clarified, and the varieties of morphologies formed on these surfaces were explored. Energetic Ar+ ions directed at an oblique angle of incidence were used to sputter etch heated Si(111) substrates inside of an ultra-high vacuum chamber. Self-organization of highly regular sputter ripples possessing sub-micron lengthscales was observed, using in situ UV light scattering spectroscopy and ex situ atomic force microscopy techniques. Distinct rippling morphologies dependent upon ion fluence were produced on Si(111). For low fluence, the surface was characterized by highly ordered corrugations possessing wavevector parallel to the projected ion beam direction (parallel mode ripples). For high fluence, less highly ordered ripples possessing wavevector perpendicular to the ion beam (perpendicular mode ripples) dominated the morphology. At intermediate ion fluence, the surface morphology was best described as a quasi-rectangular array of sputter dots consisting of a superposition of both one-dimensional rippling modes. The transition between the two one-dimensional rippling morphologies occurred at higher fluence with increasing sample temperature or with decreasing ion flux. In addition, each ripple mode was observed to coarsen with increasing fluence. For low ion fluence, the surface evolution was explained using a standard linear theory of sputter rippling. An activation energy for adatom diffusion on Si(111) was extracted and found to equal 1.7 +/- 0.1 eV, and the steady-state adatom concentration was found to be of order 10% of surface sites. For high ion fluence, a kinetic Monte Carlo simulation incorporating a minimal model of sputter rippling was used to predict the formation of two mutually perpendicular ripple modes. The simulated surface also exhibited ripple coarsening, as a consequence

  19. Regulating the size and stabilization of lipid raft-like domains and using calcium ions as their probe.

    PubMed

    Szekely, Or; Schilt, Yaelle; Steiner, Ariel; Raviv, Uri

    2011-12-20

    We apply a means to probe, stabilize, and control the size of lipid raft-like domains in vitro. In biomembranes the size of lipid rafts is ca. 10-30 nm. In vitro, mixing saturated and unsaturated lipids results in microdomains, which are unstable and coalesce. This inconsistency is puzzling. It has been hypothesized that biological line-active surfactants reduce the line tension between saturated and unsaturated lipids and stabilize small domains in vivo. Using solution X-ray scattering, we studied the structure of binary and ternary lipid mixtures in the presence of calcium ions. Three lipids were used: saturated, unsaturated, and a hybrid (1-saturated-2-unsaturated) lipid that is predominant in the phospholipids of cellular membranes. Only membranes composed of the saturated lipid can adsorb calcium ions, become charged, and therefore considerably swell. The selective calcium affinity was used to show that binary mixtures, containing the saturated lipid, phase separated into large-scale domains. Our data suggests that by introducing the hybrid lipid to a mixture of the saturated and unsaturated lipids, the size of the domains decreased with the concentration of the hybrid lipid, until the three lipids could completely mix. We attribute this behavior to the tendency of the hybrid lipid to act as a line-active cosurfactant that can easily reside at the interface between the saturated and the unsaturated lipids and reduce the line tension between them. These findings are consistent with a recent theory and provide insight into the self-organization of lipid rafts, their stabilization, and size regulation in biomembranes.

  20. Size and Charge Dependence of Ion Transport in Human Nail Plate.

    PubMed

    Baswan, Sudhir M; Li, S Kevin; LaCount, Terri D; Kasting, Gerald B

    2016-03-01

    The electrical properties of human nail plate are poorly characterized yet are a key determinate of the potential to treat nail diseases, such as onychomycosis, using iontophoresis. To address this deficiency, molar conductivities of 17 electrolytes comprising 12 ionic species were determined in hydrated human nail plate in vitro. Cation transport numbers across the nail for 11 of these electrolytes were determined by the electromotive force method. Effective ionic mobilities and diffusivities at infinite dilution for all ionic species were determined by regression analysis. The ratios of diffusivities in nail to those in solution were found to correlate inversely with the hydrodynamic radii of the ions according to a power law relationship having an exponent of -1.75 ± 0.27, a substantially steeper size dependence than observed for similar experiments in skin. Effective diffusivities of cations in nail were 3-fold higher than those of comparably sized anions. These results reflect the strong size and charge selectivity of the nail plate for ionic conduction and diffusion. The analysis implies that efficient transungual iontophoretic delivery of ionized drugs having radii upward of 5 Å (molecular weight, ca. ≥ 340 Da) will require chemical or mechanical alteration of the nail plate. PMID:26886342

  1. Size and Charge Dependence of Ion Transport in Human Nail Plate.

    PubMed

    Baswan, Sudhir M; Li, S Kevin; LaCount, Terri D; Kasting, Gerald B

    2016-03-01

    The electrical properties of human nail plate are poorly characterized yet are a key determinate of the potential to treat nail diseases, such as onychomycosis, using iontophoresis. To address this deficiency, molar conductivities of 17 electrolytes comprising 12 ionic species were determined in hydrated human nail plate in vitro. Cation transport numbers across the nail for 11 of these electrolytes were determined by the electromotive force method. Effective ionic mobilities and diffusivities at infinite dilution for all ionic species were determined by regression analysis. The ratios of diffusivities in nail to those in solution were found to correlate inversely with the hydrodynamic radii of the ions according to a power law relationship having an exponent of -1.75 ± 0.27, a substantially steeper size dependence than observed for similar experiments in skin. Effective diffusivities of cations in nail were 3-fold higher than those of comparably sized anions. These results reflect the strong size and charge selectivity of the nail plate for ionic conduction and diffusion. The analysis implies that efficient transungual iontophoretic delivery of ionized drugs having radii upward of 5 Å (molecular weight, ca. ≥ 340 Da) will require chemical or mechanical alteration of the nail plate.

  2. Mass size distributions of water-soluble inorganic and organic ions in size-segregated aerosols over metropolitan Newark in the US east coast

    NASA Astrophysics Data System (ADS)

    Zhao, Yunliang; Gao, Yuan

    2008-06-01

    To characterize the mass size distributions of water-soluble inorganic and organic ions associated with urban particulate matter, a total of 15 sets of size-segregated aerosol samples were collected by a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) in the urban area of Newark in New Jersey from July to December 2006. The mass concentrations of PM1.8 accounted for ∼68% of the mass concentrations of PM10. The mass concentrations of the total water-soluble ions in PM1.8 accounted for 31-81% of the mass concentrations of PM1.8. Sulfate was the dominant ion in fine particles, accounting for 31% of the PM1.8 mass with its dominant mode at 0.32-0.56 μm throughout all the samples. Nitrate size distributions were bi-modal, peaking at 0.32-0.56 and 3.2-5.6 μm, and the shift of the nitrate dominant fraction between fine and coarse modes was affected by temperature. The ratios of nitrate to PM1.8 varied significantly, 0.5-27%. The C2-C4 dicarboxylic acids accounted for 1.9±0.9% of PM1.8 mass, with oxalate being the dominant ion. The size distributions of oxalate exhibited two to four modes with the dominant one at 0.32-0.56 μm. Chloride existed in both coarse and fine modes, suggesting the influence of sea-salt aerosol and anthropogenic emissions. A crucial formation mechanism for the mass size distributions of these ions observed at this location is likely to be a combination of the gas-to-particle conversion and in-cloud/fog processing.

  3. Fundamental studies of ion injection and trapping of electrosprayed ions on a quadrupole ion trap mass spectrometer

    NASA Astrophysics Data System (ADS)

    Quarmby, Scott Thomas

    The quadrupole ion trap is a highly versatile and sensitive analytical mass spectrometer. Because of the advantages offered by the ion trap, there has been intense interest in coupling it to ionization techniques such as electrospray which form ions externally to the ion trap. In this work, experiments and computer simulations were employed to study the injection of electrosprayed ions into the ion trap of a Finnigan MAT LCQ LC/MS n mass spectrometer. The kinetic energy distribution of the ion beam was characterized and found to be relatively wide, a result of the high pressures from the atmospheric pressure source. One of the most important experimental parameters which affects ion injection efficiency is the RF voltage applied to the ring electrode. A theoretical model was fit to experimental data allowing the optimum RF voltage for trapping a given m/z ion to be predicted. Computer simulations of ion motion were performed to study the effect of various instrumental parameters on trapping efficiency. A commercially available ion optics program, SIMION v6.0, was chosen because it allowed the actual ion trap electrode geometry including endcap holes to be simulated. In contrast to previous computer simulations, SIMION provided the ability to start ions outside the ion trap and to simulate more accurately the injection of externally formed ions. The endcap holes were found to allow the RF field to penetrate out of the ion trap and affect ions as they approached the ion trap. From these simulations, a model for the process by which injected ions are trapped was developed. Using these computer simulations, techniques of improving trapping efficiency were investigated. Most previous techniques perturb ions which are already in the ion trap and therefore cannot be used to accumulate ions; the ability to accumulate ions is a necessity with ionization sources such as electrospray which form ions continuously. One such novel technique for improving trapping efficiency

  4. Synthesis of Large-Sized Single-Crystal Hexagonal Boron Nitride Domains on Nickel Foils by Ion Beam Sputtering Deposition.

    PubMed

    Wang, Haolin; Zhang, Xingwang; Liu, Heng; Yin, Zhigang; Meng, Junhua; Xia, Jing; Meng, Xiang-Min; Wu, Jinliang; You, Jingbi

    2015-12-22

    Large-sized single-crystal h-BN domains with a lateral size up to 100 μm are synthesized on Ni foils by ion-beam sputtering deposition. The nucleation density of h-BN is dramatically decreased by reducing the concentrations of both active sites and species on the Ni surface through a brief in situ pretreatment of the substrate and optimization of the growth parameters, enabling the growth of large-sized domains.

  5. Melting point trends and solid phase behaviors of model salts with ion size asymmetry and distributed cation charge.

    PubMed

    Lindenberg, E K; Patey, G N

    2015-07-14

    The melting point trends of model salts composed of coarse grain ions are examined using NPT molecular dynamics simulations. The model salts incorporate ion size asymmetry and distributed cation charge, which are two common features in ionic liquids. A series of single-phase and two-phase simulations are done at set temperatures with 50 K intervals for each salt, and the normal melting point is estimated within 50 K. The melting point trends are then established relative to a charge-centered, size symmetric salt with a normal melting point between 1250 K and 1300 K. We consider two sets of size asymmetric salts with size ratios up to 3:1; the melting point trends are different in each set. The lowest melting point we find is between 450 K and 500 K, which is a reduction of over 60% from the charge-centered, size symmetric case. In both sets, we find diversity in the solid phase structures. For all size ratios with small cation charge displacements, the salts crystallize with orientationally disordered cations. When the partial cation charge is far enough off-center in salts with ion size ratios near 1:1, the salts can become trapped in glassy states and have underlying crystal structures that are orientationally ordered. At ion size ratios near 3:1, the salts with large cation charge displacements show premelting transitions at temperatures as low as 300 K. After the premelting transition, these salts exist either as fast ion conductors, where the smaller anions move through a face centered cubic (fcc) cation lattice, or as plastic crystals, where ion pairs rotate on a fcc lattice.

  6. Size controlled CuO nanoparticles for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Waser, Oliver; Hess, Michael; Güntner, Andreas; Novák, Petr; Pratsinis, Sotiris E.

    2013-11-01

    Monocrystalline copper(II) oxide nanoparticles were made by scalable flame spray pyrolysis (FSP) and analyzed by X-ray diffraction (XRD), nitrogen adsorption (BET), transmission electron microscopy (TEM) and X-ray absorption near edge structure (XANES). Their primary particle diameter was closely controlled from 6 to 50 nm by varying the FSP conditions. Their electrochemical performance as Li-ion battery materials was tested in composite electrodes vs. Li-metal. Near theoretical specific charges were obtained for intermediate CuO sizes of 20 and 50 nm (dBET). In contrast, larger, commercially available CuO (dBET = 670 nm) exhibited significantly lower practical specific charge due to incomplete oxidation in the delithiation cycle as indicated by the remaining Cu and Cu2O by XRD and XANES analysis.

  7. Effect of gold ion concentration on size and properties of gold nanoparticles in TritonX-100 based inverse microemulsions

    NASA Astrophysics Data System (ADS)

    Ahmad, Tokeer; Wani, Irshad A.; Ahmed, Jahangeer; Al-Hartomy, Omar A.

    2014-04-01

    Gold nanoparticles have been prepared successfully using TritonX-100 inverse microemulsion at different concentrations of HAuCl4 (0.1, 0.05, 0.04, 0.03, 0.02 and 0.01 M). We have studied the effect of gold ion concentration on the particle size, morphology, surface area and optical properties of the gold nanoparticles. The gold nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, UV-Visible spectroscopy and Brunauer-Emmett-Teller surface area analysis. X-ray diffraction studies show the monophasic nature of the gold nanoparticles. TritonX-100 stabilized gold nanoparticles were appeared to be agglomerated at higher concentrations (0.1 and 0.05 M) of Au3+ with an average grain size of 60 and 50 nm, respectively. Monodisperse and uniform gold nanoparticles with well-defined morphologies of an average grain size of 15 and 25 nm were obtained at lower concentrations (0.01 and 0.02 M). UV-Visible spectroscopy shows the characteristic surface plasmon resonance peak ~540 nm along with the peaks at shorter and longer wavelengths may be due to the higher order plasmon resonance of the gold nanoparticles. The surface areas of the gold nanoparticles were found to be in the range of 5.8-107 m2/g which were well in agreement with the electron microscopic studies.

  8. Effect of gold ion concentration on size and properties of gold nanoparticles in TritonX-100 based inverse microemulsions

    NASA Astrophysics Data System (ADS)

    Ahmad, Tokeer; Wani, Irshad A.; Ahmed, Jahangeer; Al-Hartomy, Omar A.

    2013-04-01

    Gold nanoparticles have been prepared successfully using TritonX-100 inverse microemulsion at different concentrations of HAuCl4 (0.1, 0.05, 0.04, 0.03, 0.02 and 0.01 M). We have studied the effect of gold ion concentration on the particle size, morphology, surface area and optical properties of the gold nanoparticles. The gold nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, UV-Visible spectroscopy and Brunauer-Emmett-Teller surface area analysis. X-ray diffraction studies show the monophasic nature of the gold nanoparticles. TritonX-100 stabilized gold nanoparticles were appeared to be agglomerated at higher concentrations (0.1 and 0.05 M) of Au3+ with an average grain size of 60 and 50 nm, respectively. Monodisperse and uniform gold nanoparticles with well-defined morphologies of an average grain size of 15 and 25 nm were obtained at lower concentrations (0.01 and 0.02 M). UV-Visible spectroscopy shows the characteristic surface plasmon resonance peak ~540 nm along with the peaks at shorter and longer wavelengths may be due to the higher order plasmon resonance of the gold nanoparticles. The surface areas of the gold nanoparticles were found to be in the range of 5.8-107 m2/g which were well in agreement with the electron microscopic studies.

  9. Particle size effect of Ni-rich cathode materials on lithium ion battery performance

    SciTech Connect

    Hwang, Ilkyu; Lee, Chul Wee; Kim, Jae Chang; Yoon, Songhun

    2012-01-15

    Graphical abstract: The preparation condition of Ni-rich cathode materials was investigated. When the retention time was short, a poor cathode performance was observed. For long retention time condition, cathode performance displayed a best result at pH 12. Highlights: Black-Right-Pointing-Pointer Ni-rich cathode materials (LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}) were prepared by co-precipitation method using separate addition of Al salt. Black-Right-Pointing-Pointer Particle size of Ni-rich cathode materials became larger with increase of retention time and solution pH. Black-Right-Pointing-Pointer Cathode performance was poor for low retention time. Black-Right-Pointing-Pointer Optimal pH for co-precipitation was 12. -- Abstract: Herein, Ni-rich cathode materials (LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}) in lithium ion batteries are prepared by a separate addition of Ni/Co salt and Al sol solution using a continuously stirred tank reactor. Retention time and solution pH were controlled in order to obtain high performance cathode material. Particle size increase was observed with a higher retention time of the reactants. Also, primary and secondary particles became smaller according to an increase of solution pH, which was probably due to a decrease of growth rate. From the cathode application, a high discharge capacity (175 mAh g{sup -1}), a high initial efficiency (90%) and a good cycleability were observed in the cathode material prepared under pH 12 condition, which was attributed to its well-developed layered property and the optimal particle size. However, rate capability was inversely proportional to the particle size, which was clarified by a decrease of charge-transfer resistance measured in the electrochemical impedance spectroscopy.

  10. Comparison between Free and Immobilized Ion Effects on Hydrophobic Interactions: A Molecular Dynamics Study.

    PubMed

    Huang, Kai; Gast, Sebastian; Ma, C Derek; Abbott, Nicholas L; Szlufarska, Izabela

    2015-10-15

    Fundamental studies of the effect of specific ions on hydrophobic interactions are driven by the need to understand phenomena such as hydrophobically driven self-assembly or protein folding. Using β-peptide-inspired nanorods, we investigate the effects of both free ions (dissolved salts) and proximally immobilized ions on hydrophobic interactions. We find that the free ion effect is correlated with the water density fluctuation near a nonpolar molecular surface, showing that such fluctuation can be an indicator of hydrophobic interactions in the case of solution additives. In the case of immobilized ion, our results demonstrate that hydrophobic interactions can be switched on and off by choosing different spatial arrangements of proximal ions on a nanorod. For globally amphiphilic nanorods, we find that the magnitude of the interaction can be further tuned using proximal ions with varying ionic sizes. In general, univalent proximal anions are found to weaken hydrophobic interactions. This is in contrast to the effect of free ions, which according to our simulations strengthen hydrophobic interactions. In addition, immobilized anions of increasing ionic size do not follow the same ordering (Hofmeister-like ranking) as free ions when it comes to their impact on hydrophobic interactions. The immobilized ion effect is not simply correlated with the water density fluctuation near the nonpolar side of the amphiphilic nanorod. We propose a molecular picture that explains the contrasting effects of immobilized versus free ions.

  11. Burst size distributions in the digitized data of the ion chambers t Mt. Norikura and sea level stations

    NASA Technical Reports Server (NTRS)

    Kusunose, M.; Wada, M.; Kudo, S.; Chuang, L. S.

    1985-01-01

    A practical and simple method for burst rejection is applied to the digitized data of cosmic ray ion chambers at Mt. Norikura, Tokyo and Kochi. As a result of burst rejection, the burst size frequency distributions in the digitized data at mountain altitude and sea level ion chambers is obtained. Results show that there are no significant differences between the digital and analog data processing in burst rejection.

  12. EPR Studies of Gating Mechanisms in Ion Channels

    PubMed Central

    Chakrapani, Sudha

    2015-01-01

    Ion channels open and close in response to diverse stimuli, and the molecular events underlying these processes are extensively modulated by ligands of both endogenous and exogenous origin. In the past decade, high-resolution structures of several channel types have been solved, providing unprecedented details of the molecular architecture of these membrane proteins. Intrinsic conformational flexibility of ion channels critically governs their functions. However, the dynamics underlying gating mechanisms and modulations are obscured in the information from crystal structures. While nuclear magnetic resonance spectroscopic methods allow direct measurements of protein dynamics, they are limited by the large size of these membrane protein assemblies in detergent micelles or lipid membranes. Electron paramagnetic resonance (EPR) spectroscopy has emerged as a key biophysical tool to characterize structural dynamics of ion channels and to determine stimulus-driven conformational transition between functional states in a physiological environment. This review will provide an overview of the recent advances in the field of voltage- and ligand-gated channels and highlight some of the challenges and controversies surrounding the structural information available. It will discuss general methods used in site-directed spin labeling and EPR spectroscopy and illustrate how findings from these studies have narrowed the gap between high-resolution structures and gating mechanisms in membranes, and have thereby helped reconcile seemingly disparate models of ion channel function. PMID:25950970

  13. Targeting high value metals in lithium-ion battery recycling via shredding and size-based separation.

    PubMed

    Wang, Xue; Gaustad, Gabrielle; Babbitt, Callie W

    2016-05-01

    Development of lithium-ion battery recycling systems is a current focus of much research; however, significant research remains to optimize the process. One key area not studied is the utilization of mechanical pre-recycling steps to improve overall yield. This work proposes a pre-recycling process, including mechanical shredding and size-based sorting steps, with the goal of potential future scale-up to the industrial level. This pre-recycling process aims to achieve material segregation with a focus on the metallic portion and provide clear targets for subsequent recycling processes. The results show that contained metallic materials can be segregated into different size fractions at different levels. For example, for lithium cobalt oxide batteries, cobalt content has been improved from 35% by weight in the metallic portion before this pre-recycling process to 82% in the ultrafine (<0.5mm) fraction and to 68% in the fine (0.5-1mm) fraction, and been excluded in the larger pieces (>6mm). However, size fractions across multiple battery chemistries showed significant variability in material concentration. This finding indicates that sorting by cathode before pre-treatment could reduce the uncertainty of input materials and therefore improve the purity of output streams. Thus, battery labeling systems may be an important step towards implementation of any pre-recycling process.

  14. A two-scale non-local model of swelling porous media incorporating ion size correlation effects

    NASA Astrophysics Data System (ADS)

    Le, T. D.; Moyne, C.; Murad, M. A.; Lima, S. A.

    2013-12-01

    A new two-scale model is proposed for derivation of the macroscopic modified effective stress principle for swelling porous media saturated by an electrolyte solution containing finite size ions. A non-local pore-scale model is developed within the framework of Statistical Mechanics in conjunction with the thermodynamic approach based on Density Functional Theory leading to a nonlinear integral Fredholm equation of second kind for the ion/nanopore correlation function coupled with Poisson problem for the electric double layer potential. When combined with the fluid equilibrium condition such non-local electrochemical problem gives rise to a constitutive law for the fluid stress tensor in terms of the disjoining pressure which is decomposed into several components of different nature. The homogenization procedure based on formal asymptotic expansions is applied to up-scale the model to the macroscale leading to a two-scale constitutive law for the swelling pressure appearing in the modified effective stress principle with improved accuracy incorporating the deviations from the Gouy-Chapman Poisson-Boltzmann-based theory due to the finite size short-range ion-ion correlation effects. The integro-differential problem posed in a periodic cell is discretized by collocation schemes. Numerical results are obtained for a stratified arrangement of parallel macromolecules showing that the effects of ion-ion correlation forces give rise to anomalous attraction patterns between the particles for divalent ions.

  15. Effective pore size and radius of capture for K(+) ions in K-channels.

    PubMed

    Moldenhauer, Hans; Díaz-Franulic, Ignacio; González-Nilo, Fernando; Naranjo, David

    2016-01-01

    Reconciling protein functional data with crystal structure is arduous because rare conformations or crystallization artifacts occur. Here we present a tool to validate the dimensions of open pore structures of potassium-selective ion channels. We used freely available algorithms to calculate the molecular contour of the pore to determine the effective internal pore radius (r(E)) in several K-channel crystal structures. r(E) was operationally defined as the radius of the biggest sphere able to enter the pore from the cytosolic side. We obtained consistent r(E) estimates for MthK and Kv1.2/2.1 structures, with r(E) = 5.3-5.9 Å and r(E) = 4.5-5.2 Å, respectively. We compared these structural estimates with functional assessments of the internal mouth radii of capture (r(C)) for two electrophysiological counterparts, the large conductance calcium activated K-channel (r(C) = 2.2 Å) and the Shaker Kv-channel (r(C) = 0.8 Å), for MthK and Kv1.2/2.1 structures, respectively. Calculating the difference between r(E) and r(C), produced consistent size radii of 3.1-3.7 Å and 3.6-4.4 Å for hydrated K(+) ions. These hydrated K(+) estimates harmonize with others obtained with diverse experimental and theoretical methods. Thus, these findings validate MthK and the Kv1.2/2.1 structures as templates for open BK and Kv-channels, respectively. PMID:26831782

  16. Effective pore size and radius of capture for K+ ions in K-channels

    PubMed Central

    Moldenhauer, Hans; Díaz-Franulic, Ignacio; González-Nilo, Fernando; Naranjo, David

    2016-01-01

    Reconciling protein functional data with crystal structure is arduous because rare conformations or crystallization artifacts occur. Here we present a tool to validate the dimensions of open pore structures of potassium-selective ion channels. We used freely available algorithms to calculate the molecular contour of the pore to determine the effective internal pore radius (rE) in several K-channel crystal structures. rE was operationally defined as the radius of the biggest sphere able to enter the pore from the cytosolic side. We obtained consistent rE estimates for MthK and Kv1.2/2.1 structures, with rE = 5.3–5.9 Å and rE = 4.5–5.2 Å, respectively. We compared these structural estimates with functional assessments of the internal mouth radii of capture (rC) for two electrophysiological counterparts, the large conductance calcium activated K-channel (rC = 2.2 Å) and the Shaker Kv-channel (rC = 0.8 Å), for MthK and Kv1.2/2.1 structures, respectively. Calculating the difference between rE and rC, produced consistent size radii of 3.1–3.7 Å and 3.6–4.4 Å for hydrated K+ ions. These hydrated K+ estimates harmonize with others obtained with diverse experimental and theoretical methods. Thus, these findings validate MthK and the Kv1.2/2.1 structures as templates for open BK and Kv-channels, respectively. PMID:26831782

  17. Ion correlations in nanofluidic channels: Effects of ion size, valence, and concentration on voltage- and pressure-driven currents

    PubMed Central

    Hoffmann, Jordan

    2013-01-01

    The effects of ion-ion and ion-wall correlations in nanochannels are explored, specifically how they influence voltage- and pressure-driven currents and pressure-to-voltage energy conversion. Cations of different diameters (0.15, 0.3, and 0.9 nm) and different valences (+1, +2, and +3) at concentrations ranging from 10–6 M to 1 M are considered in 50 nm- and 100 nm-wide nanoslits with wall surface charges ranging from 0 C/m2 to –0.3 C/m2. These parameters are typical of nanofluidic devices. Ion correlations have significant effects on device properties over large parts of this parameter space. These effects are the result of ion layering (oscillatory concentration profiles) for large monovalent cations and charge inversion (more cations in the first layer near the wall than necessary to neutralize the surface charge) for the multivalent cations. The ions were modeled as charged, hard spheres using density functional theory of fluids and current was computed with the Navier-Stokes equations with two different no-slip conditions. PMID:23286510

  18. Microstructural study and size control of iron oxide nanoparticles produced by microemulsion technique

    NASA Astrophysics Data System (ADS)

    Koutzarova, T.; Kolev, S.; Ghelev, Ch.; Paneva, D.; Nedkov, I.

    2006-05-01

    In this paper we study the possibility to control the size of iron oxide (Fe3O4) nanoparticles by the microemulsion technique. We used a water-in-oil reverse microemulsion system with n-hexadecil trimethylammonium bromide (CTAB) as a cationic surfactant, n-butanol as a co-surfactant, n-hexanol as a continuous oil phase, and aqueous phase. The magnetite nanopowders were synthesized by a single microemulsion technique in which the aqueous phase contains only metal ions (Fe2+ and Fe3+). The particle size of the powders varied in the range of 14-36 nm depending on the preparation conditions. We studied the influence of changing the water/surfactant ratio (W 0 = 5, 10, 15, 20) and the metallic ion (Fe2+ and Fe3+) concentration on the particle size distribution and crystallinity of Fe3O4.

  19. How alkali metal ion binding alters the conformation preferences of gramicidin A: a molecular dynamics and ion mobility study.

    PubMed

    Chen, Liuxi; Gao, Yi Qin; Russell, David H

    2012-01-12

    Here, we present a systematic study combing electrospray ionization-ion mobility experiments and an enhanced sampling molecular dynamics, specifically integrated tempering sampling molecular dynamics simulations (ITS-MDS), to explore the conformations of alkali metal ion (Na, K, and Cs) adducts of gramicidin A (GA) in vacuo. Folding simulation is performed to obtain inherent conformational preferences of neutral GA to provide insights about how the binding of metal ions influences the intrinsic conformations of GA. The comparison between conformations of neutral GA and alkali metal ion adducts reveals a high degree of structural similarity, especially between neutral GA and [GA + Na](+); however, the structural similarities decrease as ionic radius of the metal increases. Collision cross section (CCS) profiles for [GA + Na](+) and [GA + Cs](+) ions obtained from by ITS-MDS compare favorably with the experimental CCS, but there are significant differences from CCS profiles for [GA + K](+) ions. Such discrepancies between the calculated and measured CCS profiles for [GA + K](+) are discussed in terms of limitations in the simulation force field as well as possible size-dependent coordination of the [GA + K](+) ion complex.

  20. Design study of primary ion provider for relativistic heavy ion collider electron beam ion source.

    PubMed

    Kondo, K; Kanesue, T; Tamura, J; Okamura, M

    2010-02-01

    Brookhaven National Laboratory has developed the new preinjector system, electron beam ion source (EBIS) for relativistic heavy ion collider (RHIC) and National Aeronautics and Space Administration Space Radiation Laboratory. Design of primary ion provider is an essential problem since it is required to supply beams with different ion species to multiple users simultaneously. The laser ion source with a defocused laser can provide a low charge state and low emittance ion beam, and is a candidate for the primary ion source for RHIC-EBIS. We show a suitable design with appropriate drift length and solenoid, which helps to keep sufficient total charge number with longer pulse length. The whole design of primary ion source, as well as optics arrangement, solid targets configuration and heating about target, is presented.

  1. Synthesis and structure of some nano-sized rare-earth metal ions doped potassium hexacyanoferrates

    NASA Astrophysics Data System (ADS)

    Narayan, Himanshu; Alemu, Hailemichael; Nketsa, Pusetso F.; Manatha, Toka J.; Madhavi Thakurdesai, And

    2015-05-01

    Rare-earth ions doped potassium hexacyanoferrates (KR-HCF); with the general formula KRFe(CN)6 · 3H2 O [with, R≡Y, Gd and Yb] nanoparticles were synthesized through precipitation. Characterization was done through particle-size analyzer, scanning electron microscopy (SEM), Fourier Transform infra-red (FTIR) and Raman spectroscopy, and powder X-ray diffraction (XRD). The XRD data was analyzed on FullProf Software Suite program and the unit-cell structure and lattice parameters of KR-HCF samples were determined from scratch and refined further. All the three KR-HCF nanoparticles seem to crystallize in the orthorhombic primitive PMMM space-group. Reasonably good agreement was found with the previously reported lattice constants of KGd-HCF and KYb-HCF orthorhombic single-crystals, except that they assume different space-groups. The observed dissimilarity of space-groups may be attributed to the different time scales involved in the synthesis process. Moreover, the crystal structure of KYFe(CN)6 · 3H2 O nanoparticles is being reported for the very first time.

  2. Experimental and theoretical investigation of the effects of sample size on copper plasma immersion ion implantation into polyethylene

    SciTech Connect

    Zhang Wei; Wu Zhengwei; Liu Chenglong; Pu Shihao; Zhang Wenjun; Chu, Paul K.

    2007-06-01

    Polymers are frequently surface modified to achieve special surface characteristics such as antibacterial properties, wear resistance, antioxidation, and good appearance. The application of metal plasma immersion ion implantation (PIII) to polymers is of practical interest as PIII offers advantages such as low costs, small instrument footprint, large area, and conformal processing capability. However, the insulating nature of most polymers usually leads to nonuniform plasma implantation and the surface properties can be adversely impacted. Copper is an antibacterial element and our previous experiments have shown that proper introduction of Cu by plasma implantation can significantly enhance the long-term antibacterial properties of polymers. However, lateral variations in the implant fluence and implantation depth across the insulating substrate can lead to inconsistent and irreproducible antibacterial effects. In this work, the influence of the sample size on the chemical and physical properties of copper plasma-implanted polyethylene is studied experimentally and theoretically using Poisson's equation and plasma sheath theory. Our results indicate that the sample size affects the implant depth profiles. For a large sample, more deposition occurs in the center region, whereas the implantation to deposition ratio shows less variation across the smaller sample. However, the Cu elemental chemical state is not affected by this variation. Our theoretical study discloses that nonuniform metal implantation mainly results from the laterally different surface potential on the insulating materials due to surface charge buildup and more effective charge transfer near the edge of the sample.

  3. The uses of electron beam ion traps in the study of highly charged ions

    SciTech Connect

    Knapp, D.

    1994-11-02

    The Electron Beam Ion Trap (EBIT) is a relatively new tool for the study of highly charged ions. Its development has led to a variety of new experimental opportunities; measurements have been performed with EBITs using techniques impossible with conventional ion sources or storage rings. In this paper, I will highlight the various experimental techniques we have developed and the results we have obtained using the EBIT and higher-energy Super-EBIT built at the Lawrence Livermore National Laboratory. The EBIT employs a high-current-density electron beam to trap, ionize, and excite a population of ions. The ions can be studied in situ or extracted from the trap for external experiments. The trapped ions form an ionization-state equilibrium determined by the relative ionization and recombination rates. Ions of several different elements may simultaneously be present in the trap. The ions are nearly at rest, and, for most systems, all in their ground-state configurations. The electron-ion interaction energy has a narrow distribution and can be varied over a wide range. We have used the EBIT devices for the measurement of electron-ion interactions, ion structure, ion-surface interactions, and the behavior of low-density plasmas.

  4. A computer program for sample size computations for banding studies

    USGS Publications Warehouse

    Wilson, K.R.; Nichols, J.D.; Hines, J.E.

    1989-01-01

    Sample sizes necessary for estimating survival rates of banded birds, adults and young, are derived based on specified levels of precision. The banding study can be new or ongoing. The desired coefficient of variation (CV) for annual survival estimates, the CV for mean annual survival estimates, and the length of the study must be specified to compute sample sizes. A computer program is available for computation of the sample sizes, and a description of the input and output is provided.

  5. Optical properties and size distribution of the nanocolloids made of rare-earth ion-doped NaYF4

    NASA Astrophysics Data System (ADS)

    Patel, Darayas N.; Lewis, Ashley; Wright, Donald M.; Lewis, Danielle; Valentine, Rueben; Valentine, Maucus; Wessley, Dennis; Sarkisov, Sergey; Darwish, Abdalla M.

    2015-03-01

    In this paper we investigate optical properties and size distribution of the nano-colloids made of trivalent rare-earth ion doped fluorides: holmium and ytterbium, thulium and ytterbium, and erbium and ytterbium co-doped NaYF4. These materials were synthesized by using simple co-precipitation synthetic method. The initially prepared micro-crystals had very weak or no visible upconversion fluorescence signals when being pumped with a 980-nm laser. The fluorescence intensity significantly increased after the crystals were annealed at a temperature of 400°C - 600°C undergoing the transition from cubic alpha to hexagonal beta phase of the fluoride host. Nano-colloids of the crystals were made in polar solvents using the laser ablation and ball milling methods. Size analyses of the prepared nano-colloids were conducted using a dynamic light scatterometer and atomic force microscope. The nano-colloids were filled in holey PCFs and their fluorescent properties were studied and the feasibility of new a type of fiber amplifier/laser was evaluated.

  6. Size characterization of ion tracks in PET and PTFE using SAXS

    NASA Astrophysics Data System (ADS)

    Schauries, D.; Rodriguez, M. D.; Afra, B.; Bierschenk, T.; Trautmann, C.; Mudie, S.; Kluth, P.

    2015-12-01

    Ion tracks in polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE) were created by swift heavy ion irradiation and subsequently characterized using small angle X-ray scattering (SAXS). Due to their reduced density compared to the surrounding matrix, cylindrical geometry, and parallel orientation, ion tracks produce a characteristic scattering pattern which allows quantitative analysis of their radius with high precision. For ion tracks in PET thermal annealing led to a gradual fading with a decrease in density difference yet a simultaneous increase in ion track radius. Such an increase in radius is the direct opposite compared to temperature induced ion track shrinking in inorganic materials, and suggests a very different thermal response of the polymer.

  7. Size of lethality target in mouse immature oocytes determined with accelerated heavy ions.

    PubMed

    Straume, T; Dobson, R L; Kwan, T C

    1989-01-01

    Mouse immature oocytes were irradiated in vivo with highly charged, heavy ions from the Bevalac accelerator at the Lawrence Berkeley Laboratory. The particles used were 670-MeV/nucleon Si14+, 570-MeV/nucleon Ar18+, and 450-MeV/nucleon Fe26+. The cross-sectional area of the lethality target in these extremely radiosensitive cells was determined from fluence-response curves and information on energy deposition by delta rays. Results indicate a target cross-section larger than that of the nucleus, one which closely approximates the cross-sectional area of the entire oocyte. For 450-MeV/nucleon Fe26+ particles, the predicted target cross-sectional area is 120 +/- 16 microns2, comparing well with the microscopically determined cross-sectional area of 111 +/- 12 microns2 for these cells. The present results are in agreement with our previous target studies which implicate the oocyte plasma membrane.

  8. Size of lethality target in mouse immature oocytes determined with accelerated heavy ions.

    PubMed

    Straume, T; Dobson, R L; Kwan, T C

    1989-01-01

    Mouse immature oocytes were irradiated in vivo with highly charged, heavy ions from the Bevalac accelerator at the Lawrence Berkeley Laboratory. The particles used were 670-MeV/nucleon Si14+, 570-MeV/nucleon Ar18+, and 450-MeV/nucleon Fe26+. The cross-sectional area of the lethality target in these extremely radiosensitive cells was determined from fluence-response curves and information on energy deposition by delta rays. Results indicate a target cross-section larger than that of the nucleus, one which closely approximates the cross-sectional area of the entire oocyte. For 450-MeV/nucleon Fe26+ particles, the predicted target cross-sectional area is 120 +/- 16 microns2, comparing well with the microscopically determined cross-sectional area of 111 +/- 12 microns2 for these cells. The present results are in agreement with our previous target studies which implicate the oocyte plasma membrane. PMID:2657842

  9. Neutron generators with size scalability, ease of fabrication and multiple ion source functionalities

    DOEpatents

    Elizondo-Decanini, Juan M

    2014-11-18

    A neutron generator is provided with a flat, rectilinear geometry and surface mounted metallizations. This construction provides scalability and ease of fabrication, and permits multiple ion source functionalities.

  10. Pseudopotential approach for dust acoustic solitary waves in dusty plasmas with kappa-distributed ions and electrons and dust grains having power law size distribution

    SciTech Connect

    Banerjee, Gadadhar; Maitra, Sarit

    2015-04-15

    Sagdeev's pseudopotential method is used to study small as well as arbitrary amplitude dust acoustic solitons in a dusty plasma with kappa distributed electrons and ions with dust grains having power law size distribution. The existence of potential well solitons has been shown for suitable parametric region. The criterion for existence of soliton is derived in terms of upper and lower limit for Mach numbers. The numerical results show that the size distribution can affect the existence as well as the propagation characteristics of the dust acoustic solitons. The effect of kappa distribution is also highlighted.

  11. Studying mechanosensitive ion channels using liposomes.

    PubMed

    Martinac, Boris; Rohde, Paul R; Battle, Andrew R; Petrov, Evgeny; Pal, Prithwish; Foo, Alexander Fook; Vásquez, Valeria; Huynh, Thuan; Kloda, Anna

    2010-01-01

    Mechanosensitive (MS) ion channels are the primary molecular transducers of mechanical force into electrical and/or chemical intracellular signals in living cells. They have been implicated in innumerable mechanosensory physiological processes including touch and pain sensation, hearing, blood pressure control, micturition, cell volume regulation, tissue growth, or cellular turgor control. Much of what we know about the basic physical principles underlying the conversion of mechanical force acting upon membranes of living cells into conformational changes of MS channels comes from studies of MS channels reconstituted into artificial liposomes. Using bacterial MS channels as a model, we have shown by reconstituting these channels into liposomes that there is a close relationship between the physico-chemical properties of the lipid bilayer and structural dynamics bringing about the function of these channels.

  12. Ion irradiation studies of oxide ceramics

    SciTech Connect

    Zinkle, S.J.

    1988-01-01

    This paper presents the initial results of an investigation of the depth-dependent microstructures of three oxide ceramics following ion implantation to moderate doses. The implantations were performed using ion species that occur as cations in the target material; for example, Mg/sup +/ ions were used for MgO and MgAl/sub 2/O/sub 4/ (spinel) irradiations. This minimized chemical effects associated with the implantation and allowed a more direct evaluation to be made of the effects of implanted ions on the microstructure. 11 refs., 14 figs.

  13. A Study of School Size among Alabama's Public High Schools

    ERIC Educational Resources Information Center

    Lindahl, Ronald A.; Cain, Patrick M., Sr.

    2012-01-01

    The purpose of this study was to examine the relationship between the size of Alabama's public high schools, selected school quality and financial indicators, and their students' performance on standardized exams. When the socioeconomic level of the student bodies is held constant, the size of high schools in Alabama has relatively little…

  14. Studying the Body Sizes of Echinoidea during the Mesozoic Era

    NASA Astrophysics Data System (ADS)

    Tenorio, E.; Gupta, A.; Panneerselvam, S.; Heim, N. A.; Payne, J.

    2013-12-01

    Body size is an important trait that is affected by many factors such as temperature and space, more specifically the distance from the equator. We are studying whether Bergmann's rule or Cope's rule is dominant in the class Echinoidea during the Mesozoic Era. Bergmann's rule states that temperature and body size have an inverse correlation: as temperature decreases, body size increases. Bergmann's rule also states that as the distance from the equator increases, body size increases. The other principle we are studying, Cope's rule, dictates that the overall body size of an organism increases over time. Because CO2 is a greenhouse gas, we used rCO2 as a proxy for paleotemperature. The result from plotting body size against time was that as time progressed, body size tended to increase, supporting Cope's rule. By conducting correlation tests, we found that rCO2 and maximum area had a small, but significant, negative correlation, proving Bergmann's rule, but showing that there are other significant factors affecting the body sizes of Echinoids during this time period. After plotting the sizes against space, we found that these two factors had an inverse correlation during the Jurassic and Cretaceous periods, indicating that as distance from equator increases, size decreases. Cope's rule was supported since the overall trend is an increase in Echinoidea body size; in terms of space, however, Bergmann's rule did not apply to the class Echinoidea because the overall body size of the echinoderm decreased as the distance from equator increased. With this unexpected result, we concluded that there must have been another driving force other than temperature that influenced echinoids during the Mesozoic Era.

  15. An ion cyclotron resonance study of reactions of some atomic and simple polyatomic ions with water

    NASA Technical Reports Server (NTRS)

    Karpas, Z.; Anicich, V. G.; Huntress, W. T., Jr.

    1978-01-01

    Reactions of various positive ions with water vapor were studied by ion cyclotron resonance mass spectrometric techniques. Rate constants and product distributions were determined for reactions of the ions: Ar(+), Co(+), N2(+), and CO2(+), CH2(+), and CH4(+), CH2Cl(+), HCO(+), H2CO(+), H2COH(+), H2S(+) and HS(+). The results obtained in this work are compared with earlier reported data where available.

  16. OGO 6 ion concentration irregularity studies

    NASA Technical Reports Server (NTRS)

    Mcclure, J. P.

    1973-01-01

    Research is reported concerning the ionospheric F-region irregularities. The results are based on in-situ OGO-6 measurements of the total ion concentration N sub i. A proposed mechanism for the generation of equatorial F-region irregularities and the morphological results, and the occurrence of Fe(+) ions in the equatorial F-region are discussed. Related research papers are included.

  17. Ion and neuropharmacological studies of barnacle settlement

    NASA Astrophysics Data System (ADS)

    Rittschof, Dan; Maki, James; Mitchell, Ralph; Costlow, John D.

    Experiments tested effects of altering ion concentrations and the effects of additions of biologically active substances in the media surrounding settling stage barnacle larvae. Alteration of ionic concentrations did not result in induction of metamorphosis. Excess potassium ion, magnesium ion and calcium ion inhibited settlement. Potassium ion affected young cyprids while other cations had more pronounced effects on older cyprids. Replacement of one cation by another reduced the inhibitory effects of all but calcium. Excess magnesium was routinely inhibitory while lowered magnesium had little effect. Calcium ion could be increased 50% by lowering magnesium concentrations without affecting settlement. However, low calcium ion concentrations inhibited settlement. Of the biologically active substances tested, only soluble barnacle settlement factor and dibuteryl cAMP induced metamorphosis. SITS, a calcium channel blocker, inhibited settlement and negated the effects SF +. Most of the other compounds inhibited settlement at millimolar concentrations and had no effect when tested at lower concentrations. Picrotoxin, a compound that interferes with chloride ion movement (and membrane depolarization) strongly inhibited metamorphosis with an EC 50 of 10 -6 mol.

  18. In situ formed Si nanoparticle network with micron-sized Si particles for lithium-ion battery anodes.

    PubMed

    Wu, Mingyan; Sabisch, Julian E C; Song, Xiangyun; Minor, Andrew M; Battaglia, Vincent S; Liu, Gao

    2013-01-01

    To address the significant challenges associated with large volume change of micrometer-sized Si particles as high-capacity anode materials for lithium-ion batteries, we demonstrated a simple but effective strategy: using Si nanoparticles as a structural and conductive additive, with micrometer-sized Si as the main lithium-ion storage material. The Si nanoparticles connected into the network structure in situ during the charge process, to provide electronic connectivity and structure stability for the electrode. The resulting electrode showed a high specific capacity of 2500 mAh/g after 30 cycles with high initial Coulombic efficiency (73%) and good rate performance during electrochemical lithiation and delithiation: between 0.01 and 1 V vs Li/Li(+).

  19. Size fluctuations of the initial source and event-by-event transverse momentum fluctuations in relativistic heavy-ion collisions

    SciTech Connect

    Broniowski, Wojciech; Chojnacki, Mikolaj; Obara, Lukasz

    2009-11-15

    We show that the event-by-event fluctuations of the transverse size of the initial source, which follow directly from the Glauber treatment of the earliest stage of relativistic heavy-ion collisions, cause, after hydrodynamic evolution, fluctuations of the transverse flow velocity at hadronic freeze-out. This, in turn, leads to event-by-event fluctuations of the average transverse momentum, . Simulations with GLISSANDO for the Glauber phase, followed by a realistic hydrodynamic evolution and statistical hadronization carried out with THERMINATOR, lead to agreement with the Relativistic Heavy Ion Collider (RHIC) data. In particular, the magnitude of the effect, its centrality dependence, and the weak dependence on the incident energy are properly reproduced. Our results show that the bulk of the observed event-by-event fluctuations may be explained by the fluctuations of the size of the initial source.

  20. Integrating Si nanoscale building blocks into micro-sized materials to enable practical applications in lithium-ion batteries.

    PubMed

    Yi, Ran; Gordin, Mikhail L; Wang, Donghai

    2016-01-28

    This article highlights recent advances in micro-sized silicon anode materials composed of silicon nanoscale building blocks for lithium-ion batteries. These materials show great potential in practical applications since they combine good cycling stability, high rate performance, and high volumetric capacity. Different preparation methods are introduced and the features and performance of the resulting materials are discussed. Key take-away points are interspersed through the discussion, including comments on the roles of the nanoscale building blocks. Finally, we discuss current challenges and provide an outlook for future development of micro-sized silicon-based anode materials.

  1. Thermal treatment-induced ductile-to-brittle transition of submicron-sized Si pillars fabricated by focused ion beam

    SciTech Connect

    Wang, Yue-cun; Xie, De-gang; Ning, Xiao-hui; Shan, Zhi-wei

    2015-02-23

    Si pillars fabricated by focused ion beam (FIB) had been reported to have a critical size of 310–400 nm, below which their deformation behavior would experience a brittle-to-ductile transition at room temperature. Here, we demonstrated that the size-dependent transition was actually stemmed from the amorphous Si (a-Si) shell introduced during the FIB fabrication process. Once the a-Si shell was crystallized, Si pillars would behave brittle again with their modulus comparable to their bulk counterpart. The analytical model we developed has been proved to be valid in deriving the moduli of crystalline Si core and a-Si shell.

  2. Temperature-dependent toxicities of nano zinc oxide to marine diatom, amphipod and fish in relation to its aggregation size and ion dissolution.

    PubMed

    Wong, Stella W Y; Leung, Kenneth M Y

    2014-08-01

    This study, for the first time, concurrently investigated the influence of seawater temperature, exposure concentration and time on the aggregation size and ion dissolution of nano zinc oxides (nZnO) in seawater, and the interacting effect of temperature and waterborne exposure of nZnO to the marine diatom Skeletonema costatum, amphipod Melita longidactyla and fish Oryzias melastigma, respectively. Our results showed that aggregate size was jointly affected by seawater temperature, nZnO concentration and exposure time. Among the three factors, the concentration of nZnO was the most important and followed by exposure time, whereas temperature was less important as reflected by their F values in the three-way analysis of variance (concentration: F3, 300 = 247.305; time: F2, 300 = 20.923 and temperature: F4, 300 = 4.107; All p values <0.001). The aggregate size generally increased with increasing nZnO concentration and exposure time. The release of Zn ions from nZnO was significantly influenced by seawater temperature and exposure time; the ion dissolution rate generally increased with decreasing temperature and increasing exposure time. Growth inhibition of diatoms increased with increasing temperature, while temperature and nZnO had an interactional effect on their photosynthesis. For the amphipod, mortality was positively correlated with temperature. Fish larvae growth rate was only affected by temperature but not nZnO, while the two factors interactively modulated the expression of heat shock and metallothionein proteins. Evidently, temperature can influence aggregate size and ion dissolution and thus toxicity of nZnO to the marine organisms in a species-specific manner. PMID:24219175

  3. Size distributions of aerosol and water-soluble ions in Nanjing during a crop residual burning event.

    PubMed

    Wang, Honglei; Zhu, Bin; Shen, Lijuan; Kang, Hanqing

    2012-01-01

    To investigate the impact on urban air pollution by crop residual burning outside Nanjing, aerosol concentration, pollution gas concentration, mass concentration, and water-soluble ion size distribution were observed during one event of November 4-9, 2010. Results show that the size distribution of aerosol concentration is bimodal on pollution days and normal days, with peak values at 60-70 and 200-300 nm, respectively. Aerosol concentration is 10(4) cm(-3) x nm(-1) on pollution days. The peak value of spectrum distribution of aerosol concentration on pollution days is 1.5-3.3 times higher than that on a normal day. Crop residual burning has a great impact on the concentration of fine particles. Diurnal variation of aerosol concentration is trimodal on pollution days and normal days, with peak values at 03:00, 09:00 and 19:00 local standard time. The first peak is impacted by meteorological elements, while the second and third peaks are due to human activities, such as rush hour traffic. Crop residual burning has the greatest impact on SO2 concentration, followed by NO2, O3 is hardly affected. The impact of crop residual burning on fine particles (< 2.1 microm) is larger than on coarse particles (> 2.1 microm), thus ion concentration in fine particles is higher than that in coarse particles. Crop residual burning leads to similar increase in all ion components, thus it has a small impact on the water-soluble ions order. Crop residual burning has a strong impact on the size distribution of K+, Cl-, Na+, and F- and has a weak impact on the size distributions of NH4+, Ca2+, NO3- and SO4(2-).

  4. Ion cyclotron emission studies: Retrospects and prospects

    NASA Astrophysics Data System (ADS)

    Gorelenkov, N. N.

    2016-05-01

    Ion cyclotron emission (ICE) studies emerged in part from the papers by A.B. Mikhailovskii published in the 1970s. Among the discussed subjects were electromagnetic compressional Alfvénic cyclotron instabilities with the linear growth rate √ {n_α /n_e } driven by fusion products, -particles which draw a lot of attention to energetic particle physics. The theory of ICE excited by energetic particles was significantly advanced at the end of the 20th century motivated by first DT experiments on TFTR and subsequent JET experimental studies which we highlight. More recently ICE theory was advanced by detailed theoretical and experimental studies on spherical torus (ST) fusion devices where the instability signals previously indistinguishable in high aspect ratio tokamaks due to high toroidal magnetic field became the subjects of experiments. We discuss further prospects of ICE theory applications for future burning plasma (BP) experiments such as those to be conducted in ITER device in France, where neutron and gamma rays escaping the plasma create extremely challenging conditions fusion alpha particle diagnostics.

  5. Ion cyclotron emission studies: Retrospects and prospects

    DOE PAGES

    Gorelenkov, N. N.

    2016-06-05

    Ion cyclotron emission (ICE) studies emerged in part from the papers by A.B. Mikhailovskii published in the 1970s. Among the discussed subjects were electromagnetic compressional Alfv,nic cyclotron instabilities with the linear growth rate similar ~ √(nα/ne) driven by fusion products, -particles which draw a lot of attention to energetic particle physics. The theory of ICE excited by energetic particles was significantly advanced at the end of the 20th century motivated by first DT experiments on TFTR and subsequent JET experimental studies which we highlight. Recently ICE theory was advanced by detailed theoretical and experimental studies on spherical torus (ST) fusionmore » devices where the instability signals previously indistinguishable in high aspect ratio tokamaks due to high toroidal magnetic field became the subjects of experiments. Finally, we discuss prospects of ICE theory applications for future burning plasma (BP) experiments such as those to be conducted in ITER device in France, where neutron and gamma rays escaping the plasma create extremely challenging conditions fusion alpha particle diagnostics.« less

  6. Diagnostics for studies of novel laser ion acceleration mechanisms

    SciTech Connect

    Senje, Lovisa; Aurand, Bastian; Wahlström, Claes-Göran; Yeung, Mark; Kuschel, Stephan; Rödel, Christian; Wagner, Florian; Roth, Markus; Li, Kun; Neumayer, Paul; Dromey, Brendan; Jung, Daniel; Bagnoud, Vincent; Zepf, Matthew; Kuehl, Thomas

    2014-11-15

    Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel acceleration mechanisms in terms of their angular energy distribution, conversion efficiency, and plasma density evolution.

  7. Diagnostics for studies of novel laser ion acceleration mechanisms.

    PubMed

    Senje, Lovisa; Yeung, Mark; Aurand, Bastian; Kuschel, Stephan; Rödel, Christian; Wagner, Florian; Li, Kun; Dromey, Brendan; Bagnoud, Vincent; Neumayer, Paul; Roth, Markus; Wahlström, Claes-Göran; Zepf, Matthew; Kuehl, Thomas; Jung, Daniel

    2014-11-01

    Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel acceleration mechanisms in terms of their angular energy distribution, conversion efficiency, and plasma density evolution.

  8. Beam-transport study of an isocentric rotating ion gantry with minimum number of quadrupoles

    NASA Astrophysics Data System (ADS)

    Pavlovic, Márius; Griesmayer, Erich; Seemann, Rolf

    2005-06-01

    A beam-transport study of an isocentric gantry for ion therapy is presented. The gantry is designed with the number of quadrupoles down to the theoretical minimum, which is the feature published for the first time in this paper. This feature has been achieved without compromising the ion-optical functions of the beam-transport system that is capable of handling non-symmetric beams (beams with different emittances in vertical and horizontal plane), pencil-beam scanning, double-achromatic optics and beam-size control. Ion-optical properties of the beam-transport system are described, discussed and illustrated by computer simulations performed by the TRANSPORT-code.

  9. Negative and positive cesium ion studies

    NASA Technical Reports Server (NTRS)

    Kuehn, D. G.; Sutliff, D. E.; Chanin, L. M.

    1978-01-01

    Mass spectrometric analyses have been performed on the positive and negative species from discharges in Cs, He-Cs, and He-H2-Cs mixtures. Sampling was conducted through the electrodes of normal glow discharges and from close-spaced heated-cathode conditions, which approximate a cesium thermionic converter. No negative Cs ions were observed for Cs pressures less than .01 torr. Identified species included Cs(+), Cs2(+), Cs(-), and what appeared to be multiply charged ions. Low-mass negative and positive ions attributed to H2 were observed when an He-H2 mixture was also present in the discharge region.

  10. Studies on Molecular and Ion Transport in Silicalite Membranes and Applications as Ion Separator for Redox Flow Battery

    NASA Astrophysics Data System (ADS)

    Yang, Ruidong

    Microporous zeolite membranes have been widely studied for molecular separations based on size exclusion or preferential adsorption-diffusion mechanisms. The MFI-type zeolite membranes were also demonstrated for brine water desalination by molecular sieving effect. In this research, the pure silica MFI-type zeolite (i.e. silicalite) membrane has been for the first time demonstrated for selective permeation of hydrated proton (i.e. H3O+) in acidic electrolyte solutions. The silicalite membrane allows for permeation of H 3O+ ions, but is inaccessible to the large hydrated multivalent vanadium ions due to steric effect. The silicalite membrane has been further demonstrated as an effective ion separator in the all-vanadium redox flow battery (RFB).The silicalite is nonionic and its proton conductivity relies on the electric field-driven H3O+ transport through the sub nanometer-sized pores under the RFB operation conditions. The silicalite membrane displayed a significantly reduced self-discharge rate because of its high proton-to-vanadium ion transport selectivity. However, the nonionic nature of the silicalite membrane and very small diffusion channel size render low proton conductivity and is therefore inefficient as ion exchange membranes (IEMs) for practical applications. The proton transport efficiency may be improved by reducing the membrane thickness. However, the zeolite thin films are extremely fragile and must be supported on mechanically strong and rigid porous substrates. In this work, silicalite-Nafion composite membranes were synthesized to achieve a colloidal silicalite skin on the Nafion thin film base. The "colloidal zeolite-ionic polymer" layered composite membrane combines the advantages of high proton-selectivity of the zeolite layer and the mechanical flexibility and low proton transport resistance of the ionic polymer membrane. The composite membrane exhibited higher proton/vanadium ion separation selectivity and lower electrical resistance than

  11. [Characteristics of mass size distributions of water-soluble, inorganic ions during summer and winter haze days of Beijing].

    PubMed

    Huang, Yi-Min; Liu, Zi-Rui; Chen, Hong; Wang, Yue-Si

    2013-04-01

    To investigate the size distribution characteristics of water soluble inorganic ions in haze days, the particle samples were collected by two Andersen cascade impactors in Beijing during summer and winter time and each sampling period lasted two weeks. Online measurement of PM10 and PM2.5 using TEOM were also conducted at the same time. Sources and formation mechanism of water soluble inorganic ions were analyzed based on their size distributions. The results showed that average concentrations of PM10 and PM 2.5 were (245.5 +/- 8.4) microg x m(-3) and (120.2 +/- 2.0) microg x m(-3) during summer haze days (SHD), and were (384.2 +/- 30.2) microg x m(-3) and (252.7 +/- 47.1) microg x m(-3) during winter haze days (WHD), which suggested fine particles predominated haze pollution episode in both seasons. Total water-soluble inorganic ions concentrations were higher in haze days than those in non-haze days, especially in fine particles. Furthermore, concentrations of secondary inorganic ions (SO4(2-), NO3(-) and NH4(+)) increased quicker than other inorganic ions in fine particles during haze days, indicating secondary inorganic ions played an important role in the formation of haze pollution. Similar size distributions were found for all Sinorganic water soluble ions except for NO3(-), during SHD and WHD. SO4(2-) and NH4(+) dominated in the fine mode (PM1.0) while Mg2+ and Ca2+ accumulated in coarse fraction, Na+, Cl- and K+ showed a bimodal distribution. For NO3(-), however, it showed a bimodal distribution during SHD and a unimodal distribution dominated in the fine fraction was found during WHD. The average mass median aerodynamic diameter (MMAD) of SO4(2-) was 0.64 microm in SHD, which suggested the formation of SO4(2-) was mainly attributed to in-cloud processes. Furthermore, a higher apparent conversion rate of sulfur dioxide (SOR) was found in SHD, indicating more fine particles were produced by photochemical reaction in haze days than that in non-haze days. The

  12. Cation size effects in mixed-ion metaphosphate glasses: structural characterization by multinuclear solid state NMR spectroscopy.

    PubMed

    Schneider, J; Tsuchida, J; Eckert, H

    2013-09-14

    Metaphosphate glasses with two monovalent species A(1-x)B(x)PO3 (0 ≤x≤ 1) show mixed-ion effects (MIE) in the dc conductivities and glass transition temperatures, which are strongly dependent on the cation size mismatch between the two mobile species. In the present contribution, mixed-ion metaphosphate glasses based on the cation combinations Cs-Li, Rb-Li, and Cs-Ag, exhibiting particularly large size mismatches, are analyzed by (31)P, (87)Rb, (109)Ag and (133)Cs NMR to determine possible correlations between this mismatch and some of the structural properties critical to the development of the MIE: the local environments around the mobile species and their spatial distribution relative to each other. The results are compared with those obtained in the Na-Ag metaphosphate series, which serves as a reference system, with minimized cation mismatch MIE. The local coordination environments of the Ag(+), Rb(+) and Cs(+) ions follow analogous compositional trends as previously observed in Na-based mixed-ion metaphosphate glasses: for a given cation species A, the average A-O distance shows an expansion/compression when this cation is replaced by a second species B with smaller/bigger ionic radius, respectively. This compositional differentiation of the structural sites for the mobile species may contribute to the MIE. Concerning the relative spatial distribution of the mobile ions, results from (7)Li-(133)Cs (SEDOR) experiments indicate a random mixture of Cs and Li in Cs-Li metaphosphate glasses. While this result is in agreement with one of the fundamental hypotheses of the models proposed to describe the MIE, it is at variance with the observation of various partial cation segregation phenomena observed in Na-based mixed alkali glasses. This result suggests that cation size mismatch is not the decisive parameter in determining segregation or non-statistical mixing of cations in the glass. In the Cs-Ag and Na-Ag glasses, (109)Ag spin-echo NMR reveals a progressive

  13. Fourier transform ion cyclotron resonance mass spectrometric study of gas-phase ion-molecule reactions

    SciTech Connect

    Yin, Winnie Weixin.

    1993-01-01

    Gas-phase ion-molecule reactions of rare earth (include Sc, Y, and all the lanthanide series) metal ion (except Pm[sup +]) reactions with benzene and alkyl benzene ligands were systematically studied by FT/ICR mass spectrometry. An electronic configuration d[sup 1]s[sup 1] was found to be necessary for the ions to insert into C-C and/or C-H bonds of alkyl groups of the ligands. When the promotion energy for the transition groups of the ligands. When the promotion energy for the transition f[sup n]s[sup 1] [yields] f[sup n[minus]1]d[sup 1]s[sup 1] was large, no reaction resulting from activation was observed. Some of the rare earth metal ions do not activate C-C or C-H bond of saturated hydrocarbons, but are rather reactive with alkyl groups of aromatic ligands. Most of the rare earth ions only from intact complex ions with benzene, while Sc[sup +], Y[sup +], La[sup +] and Ce[sup +] form metal-benzyne ions. Rare earth metal ions are quite oxophilic and readily react with background oxygen containing species when the reactions with organic ligand(s). A hyperbolic ion trap for ET/ICR mass spectrometry was evaluated experimentally and compared with the most commonly used cubic ion trap. The hyperbolic trap offers several advantages over the cubic ion trap. The hyperbolic trap offers several advantages over the cubic trap: improved mass resolving power, improved mass accuracy for wide-range mass spectra, and elimination of frequency shift due to different ion cyclotron radius. But z-ejection is more pronounced in the hyperbolic than in the cubic trap.

  14. High time resolution studies of upstream ions

    NASA Technical Reports Server (NTRS)

    Anderson, K. A.; Levedahl, W. K.; Lin, R. P.; Parks, G. K.

    1984-01-01

    The influence of phi, the angle between the interplanetary magnetic field and the earth-sun vector on ions and electrons in the earth's bow shock, was investigated in terms of ISEE 2 data. A small phi was associated with intermediate energy upstream ions and reduced populations of low energy, about 1.6 keV, ion fluxes. The magnitude of phi was closely related to particular, constant energy levels, e.g., a phi of 40 deg and an energy of 30 keV and a phi of 75 deg and an energy of 6 keV. Ion fluxes are high in the angles form 60-80 deg and feature energies of 55-280 keV. The acceleration process up to the high energy levels in the 1-3 min interval from upstream to downstream occurs more rapidly than could be accounted for by a first-order Fermi process.

  15. Using fluorometry and ion-sensitive microelectrodes to study the functional expression of heterologously-expressed ion channels and transporters in Xenopus oocytes

    PubMed Central

    Musa-Aziz, Raif; Boron, Walter F.; Parker, Mark D.

    2010-01-01

    The Xenopus laevis oocyte is a model system for the electrophysiological study of exogenous ion transporters. Three main reasons make the oocyte suitable for this purpose: (a) it has a large cell size (~1 mm diameter), (b) it has an established capacity to produce—from microinjected mRNAs or cRNAs—exogenous ion transporters with close-to-physiological post-translational modifications and actions, and (c) its membranes contain endogenous ion-transport activities which are usually smaller in magnitude than the activities of exogenously-expressed ion transporters. The expression of ion-transporters as green-fluorescent-protein fusions allows the fluorometric assay of transporter yield in living oocytes. Monitoring of transporter-mediated movement of ions such as Cl−, H+ (and hence base equivalents like OH−1 and HCO3−), K+, and Na+ is achieved by positioning the tips of ion-sensitive microelectrodes inside the oocyte and/or at the surface of the oocyte plasma membrane. The use of ion-sensitive electrodes is critical for studying net ion-movements mediated by electroneutral transporters. The combined use of fluorometry and electrophysiology expedites transporter study by allowing measurement of transporter yield prior to electrophysiological study and correlation of relative transporter yield with transport rates. PMID:20051266

  16. Amphiphilic organic ion pairs in solution: a theoretical study.

    PubMed

    Pradines, Vincent; Poteau, Romuald; Pimienta, Veronique

    2007-07-16

    The macroscopic manifestation of hydrophobic interactions for amphiphilic organic ion pairs (tetraalkylammonium-anion) has been shown experimentally by measuring their association constants and their affinity with the organic phase. Beyond a certain size, there is a direct relation between association constants and chain lengths in tetraalkylammonium ions. We propose to cast a bridge between these results and geometrical properties considered at the level of a single ion pair by means of quantum chemistry calculations performed on model systems: trimethylalkylammonium-pentyl sulfate instead of tetraalkylammonium-dodecyl sulfate. Two limiting cases are considered: head-to-head configurations, which yield an optimal electrostatic interaction between polar heads, and parallel configurations with a balance between electrostatic and hydrophobic interactions. All properties (geometries, complexation energies, and atomic charges) were obtained at the MP2 level of calculation, with water described by a continuum model (CPCM). Dispersion forces link hydrocarbon chains of tetraalkylammonium ions and pentyl sulfate, thus yielding (for the largest ion pairs) parallel configurations favored with respect to head-to-head geometries by solute-solvent electrostatic interactions. Given the small experimental association energies, we probe the accuracy limit of the MP2 and CPCM methods. However, clear trends are obtained as a function of chain length, which agree with the experimental observations. The calculated monotonic stabilization of ion pairs when the hydrocarbon chain increases in length is discussed in terms of electrostatic interactions (between ions and between ion pairs and water), dispersion forces, and cavitation energies.

  17. Dilepton Production In Ion-Ion Collisions Studied Using HADES

    SciTech Connect

    Kugler, A.; Krizek, F.; Pleskac, R.; Pospisil, V.; Taranenko, A.; Tlusty, P.; Wagner, V.; Agakichiev, H.; Froehlich, I.; Gilardi, C.; Kuehn, W.; Lehnert, J.; Lins, E.; Metag, V.; Novotny, R.; Perez, T.; Ritman, J.; Spruck, B.; Toia, A.; Traxler, M.

    2007-10-26

    The High-Acceptance Di-Electron Spectrometer installed at GSI Darmstadt is a second generation experiment to study production of dielectron pairs from proton, pion and nucleus induced reactions at the SIS/BEVALAC energy regime. During period 2002-4 medium-resolution data have been taken with HADES on the light C+C system at 1 and 2 AGeV. The data analysis confirms former finding of the DLS collaboration. First physics run on slightly heavier system Ar+KCl was carried out will almost full HADES setup at 2005.

  18. Size distributions of gold nanoclusters studied by liquid chromatography

    SciTech Connect

    WILCOXON,JESS P.; MARTIN,JAMES E.; PROVENCIO,PAULA P.

    2000-05-23

    The authors report high pressure liquid chromatography, (HPLC), and transmission electron microscopy, (TEM), studies of the size distributions of nanosize gold clusters dispersed in organic solvents. These metal clusters are synthesized in inverse micelles at room temperature and those investigated range in diameter from 1--10 nm. HPLC is sensitive enough to discern changes in hydrodynamic volume corresponding to only 2 carbon atoms of the passivating agent or metal core size changes of less than 4 {angstrom}. The authors have determined for the first time how the total cluster volume (metal core + passivating organic shell) changes with the size of the passivating agent.

  19. Rational design of a minimal size sensor array for metal ion detection.

    PubMed

    Palacios, Manuel A; Wang, Zhuo; Montes, Victor A; Zyryanov, Grigory V; Anzenbacher, Pavel

    2008-08-01

    The focus of this study was to demonstrate that, in the luminescent sensors, the signal transduction may possibly be the most important part in the sensing process. Rational design of fluorescent sensor arrays for cations utilizing extended conjugated chromophores attached to 8-hydroxyquinoline is reported. All of the optical sensors utilized in the arrays comprise the same 8-hydroxyquinoline (8-HQ) receptor and various conjugated chromophores to yield a different response to various metal cations. This is because the conjugated chromophores attached to the receptor are partially quenched in their resting state, and upon the cation coordination by the 8-HQ, the resulting metalloquinolinolate complex displays a change in fluorescence. A delicate balance of conjugation, fluorescence enhancement, energy transfer, and a heavy metal quenching effect results in a fingerprint-like pattern of responses for each sensor-cation complex. Principal component analysis (PCA) and linear discriminant analysis (LDA) are used to demonstrate the contribution of individual sensors within the array, information that may be used to design sensor arrays with the smallest number of sensor elements. This approach allows discriminating between 10 cations by as few as two or even one sensor element. Examples of arrays comprising various numbers of sensor elements and their utility in qualitative identification of Ca(2+), Mg(2+), Cd(2+), Hg(2+), Co(2+), Zn(2+), Cu(2+), Ni(2+), Al(3+), and Ga(3+) ions are presented. A two-member array was found to identify 11 analytes with 100% accuracy. Also the best two of the sensors were tested alone and both were found to be able to discriminate among the samples with 99% and 96% accuracy, respectively. To illustrate the utility of this approach to a real-world application, identification of enhanced soft drinks based on their Ca(2+), Mg(2+), and Zn(2+) cation content was performed. The same approach to reducing array elements was used to construct three

  20. A study of the charged ice grains in the Enceladus plume with a composite size distribution

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Hill, T. W.

    2013-12-01

    We study the negatively charged ice grains in the Enceladus plume ranging from nanometer to micrometer in size based on Cassini's multiple instrument observations. We have constructed a composite size distribution by combining the CAPS nanograin size distributions (Hill et al., 2012 JGR) and the CDA dust power-law size distribution (Kempf et al., 2008 Icarus). We also study the charging of the ice grains using RPWS-LP data (Morooka et al., 2011 JGR). E3 and E5 CDA data are not available, but RPWS detected impacts of micron sized dust grains with the same power law size distribution (Ye et al., 2012 AGU meeting). Our size distribution formula is fitted with E3 and E5 CAPS and RPWS data, and constrained with the total dust charge density inferred from the RPWS-LP cold plasma data. The fitting with E17 and E18 CAPS nanograin data (Tokar et al., 2012 AGU meeting) and RPWS dust data (Ye et al., 2013 MAPS workshop) will also be discussed. Based on the charge per grain and the size distribution, the densities, source rate, motion, and currents of the ice grains can be calculated. Our size distribution implies that the grains ~2-20 nm dominate in both charge density and number density. But the mass density is very sensitive to the larger grains. We discuss the mass densities and source rates with different size distribution parameters, and compare with the water vapor plume. We study the trajectories of the charged ice grains in both Enceladus and Saturn frames, and calculate the dust currents from their motion. We find that the total dust pickup current at Enceladus is ≥10^5 A. We will also discuss the ion and dust current systems and resulting magnetic perturbations near the moon.

  1. Ab Initio Molecular Dynamics Study on the Interactions between Carboxylate Ions and Metal Ions in Water.

    PubMed

    Mehandzhiyski, Aleksandar Y; Riccardi, Enrico; van Erp, Titus S; Trinh, Thuat T; Grimes, Brian A

    2015-08-20

    The interaction between a carboxylate anion (deprotonated propanoic acid) and the divalent Mg(2+), Ca(2+), Sr(2+), Ba(2+) metal ions is studied via ab initio molecular dynamics. The main focus of the study is the selectivity of the carboxylate-metal ion interaction in aqueous solution. The interaction is modeled by explicitly accounting for the solvent molecules on a DFT level. The hydration energies of the metal ions along with their diffusion and mobility coefficients are determined and a trend correlated with their ionic radius is found. Subsequently, a series of 16 constrained molecular dynamics simulations for every ion is performed, and the interaction free energy is obtained from thermodynamic integration of the forces between the metal ion and the carboxylate ion. The results indicate that the magnesium ion interacts most strongly with the carboxylate, followed by calcium, strontium, and barium. Because the interaction free energy is not enough to explain the selectivity of the reaction observed experimentally, more detailed analysis is performed on the simulation trajectories to understand the steric changes in the reaction complex during dissociation. The solvent dynamics appear to play an important role during the dissociation of the complex and also in the observed selectivity behavior of the divalent ions.

  2. Toxicity of different-sized copper nano- and submicron particles and their shed copper ions to zebrafish embryos.

    PubMed

    Hua, Jing; Vijver, Martina G; Ahmad, Farooq; Richardson, Michael K; Peijnenburg, Willie J G M

    2014-08-01

    Three sizes of copper nanoparticles (Cu NPs; 25 nm, 50 nm, and 100 nm), 1 submicron-sized particle, and Cu(NO3 )2 were added to the culture buffer of zebrafish embryos from 24 h postfertilization to 120 h postfertilization. In suspensions of Cu NPs and the Cu submicron-sized particle, the main contribution to the toxicity to zebrafish embryos was from the particle form of Cu particles (Cu NPparticle , >71%) rather than from dissolved Cu from the Cu particles (Cu NPion ). All particles tested as well as copper nitrate inhibited hatching, altered behavioral responses, and increased the incidence of malformations. Different kinds of abnormalities were observed in the morphology and behavior of the zebrafish embryos, depending on the particle size of the Cu suspensions tested. The median lethal concentrations of Cu NPparticle (25 nm, 50 nm, and 100 nm), the submicron-sized particle, and copper nitrate were 0.58 mg/L, 1.65 mg/L, 1.90 mg/L, 0.35 mg/L, and 0.70 mg/L, respectively. Submicron-sized particles and copper nitrate were more toxic than Cu NPs, and smaller Cu NPs were more toxic than larger Cu NPs. Dissolution of Cu NPs and the subsequent ion toxicity was not the primary mechanism of Cu NP toxicity in zebrafish embryos.

  3. Photoionization and ion cyclotron resonance studies of the ion chemistry of ethylene oxide

    NASA Technical Reports Server (NTRS)

    Corderman, R. R.; Williamson, A. D.; Lebreton, P. R.; Buttrill, S. E., Jr.; Beauchamp, J. L.

    1976-01-01

    The formation of the ethylene oxide molecular ion and its subsequent ion-molecule reactions leading to the products C2H5O(+) and C3H5O(+) have been studied using time-resolved photoionization mass spectroscopy, ion cyclotron resonance spectroscopy, and photoelectron spectroscopy. An examination of the effects of internal energy on reactivity shows that the ratio of C3H5O(+) to C2H5O(+) increases by an order of magnitude with a single quantum of vibrational energy. The formation of (C2H4O/+/)-asterisk in a collision-induced isomerization is found which yields a ring-opened structure by C-C bond cleavage. The relaxed ring-opened C2H4O(+) ion reacts with neutral ethylene oxide by CH2(+) transfer to yield an intermediate product ion C3H6O(+) which gives C3H5O(+) by loss of H.

  4. Size matters: a study on naming and size knowledge in dementia of the Alzheimer type.

    PubMed

    Moreno-Martinez, F Javier

    2010-12-01

    Category-specificity was longitudinally studied over a period of 12 months in seven Alzheimer disease patients, with two semantic tasks differing with respect to verbal processing demands: picture naming and a size ordering task. Items from each task were matched on all cognitive and psycholinguistic variables known to differ across domains (living-nonliving). Naming performance of patients was poorer than that of normal controls. Regarding category-specific effects, while naming performance of patients was parallel to that of normal controls, patients' performance with the size ordering task revealed a different scaling of living things while that of nonliving things mirrored performance of normal controls. This suggests that caution is needed when the picture naming task is exclusively used to document category-specific effects. PMID:20544501

  5. Ejection of Coulomb Crystals from a Linear Paul Ion Trap for Ion-Molecule Reaction Studies.

    PubMed

    Meyer, K A E; Pollum, L L; Petralia, L S; Tauschinsky, A; Rennick, C J; Softley, T P; Heazlewood, B R

    2015-12-17

    Coulomb crystals are being increasingly employed as a highly localized source of cold ions for the study of ion-molecule chemical reactions. To extend the scope of reactions that can be studied in Coulomb crystals-from simple reactions involving laser-cooled atomic ions, to more complex systems where molecular reactants give rise to multiple product channels-sensitive product detection methodologies are required. The use of a digital ion trap (DIT) and a new damped cosine trap (DCT) are described, which facilitate the ejection of Coulomb-crystallized ions onto an external detector for the recording of time-of-flight (TOF) mass spectra. This enables the examination of reaction dynamics and kinetics between Coulomb-crystallized ions and neutral molecules: ionic products are typically cotrapped, thus ejecting the crystal onto an external detector reveals the masses, identities, and quantities of all ionic species at a selected point in the reaction. Two reaction systems are examined: the reaction of Ca(+) with deuterated isotopologues of water, and the charge exchange between cotrapped Xe(+) with deuterated isotopologues of ammonia. These reactions are examples of two distinct types of experiment, the first involving direct reaction of the laser-cooled ions, and the second involving reaction of sympathetically-cooled heavy ions to form a mixture of light product ions. Extensive simulations are conducted to interpret experimental results and calculate optimal operating parameters, facilitating a comparison between the DIT and DCT approaches. The simulations also demonstrate a correlation between crystal shape and image shape on the detector, suggesting a possible means for determining crystal geometry for nonfluorescing ions.

  6. Visual exposure to large and small portion sizes and perceptions of portion size normality: Three experimental studies

    PubMed Central

    Robinson, Eric; Oldham, Melissa; Cuckson, Imogen; Brunstrom, Jeffrey M.; Rogers, Peter J.; Hardman, Charlotte A.

    2016-01-01

    Portion sizes of many foods have increased in recent times. In three studies we examined the effect that repeated visual exposure to larger versus smaller food portion sizes has on perceptions of what constitutes a normal-sized food portion and measures of portion size selection. In studies 1 and 2 participants were visually exposed to images of large or small portions of spaghetti bolognese, before making evaluations about an image of an intermediate sized portion of the same food. In study 3 participants were exposed to images of large or small portions of a snack food before selecting a portion size of snack food to consume. Across the three studies, visual exposure to larger as opposed to smaller portion sizes resulted in participants considering a normal portion of food to be larger than a reference intermediate sized portion. In studies 1 and 2 visual exposure to larger portion sizes also increased the size of self-reported ideal meal size. In study 3 visual exposure to larger portion sizes of a snack food did not affect how much of that food participants subsequently served themselves and ate. Visual exposure to larger portion sizes may adjust visual perceptions of what constitutes a ‘normal’ sized portion. However, we did not find evidence that visual exposure to larger portions altered snack food intake. PMID:26702602

  7. Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    van Pinxteren, Dominik; Wadinga Fomba, Khanneh; Mertes, Stephan; Müller, Konrad; Spindler, Gerald; Schneider, Johannes; Lee, Taehyoung; Collett, Jeffrey L.; Herrmann, Hartmut

    2016-03-01

    Cloud water samples were taken in September/October 2010 at Mt. Schmücke in a rural, forested area in Germany during the Lagrange-type Hill Cap Cloud Thuringia 2010 (HCCT-2010) cloud experiment. Besides bulk collectors, a three-stage and a five-stage collector were applied and samples were analysed for inorganic ions (SO42-,NO3-, NH4+, Cl-, Na+, Mg2+, Ca2+, K+), H2O2 (aq), S(IV), and dissolved organic carbon (DOC). Campaign volume-weighted mean concentrations were 191, 142, and 39 µmol L-1 for ammonium, nitrate, and sulfate respectively, between 4 and 27 µmol L-1 for minor ions, 5.4 µmol L-1 for H2O2 (aq), 1.9 µmol L-1 for S(IV), and 3.9 mgC L-1 for DOC. The concentrations compare well to more recent European cloud water data from similar sites. On a mass basis, organic material (as DOC × 1.8) contributed 20-40 % (event means) to total solute concentrations and was found to have non-negligible impact on cloud water acidity. Relative standard deviations of major ions were 60-66 % for solute concentrations and 52-80 % for cloud water loadings (CWLs). The similar variability of solute concentrations and CWLs together with the results of back-trajectory analysis and principal component analysis, suggests that concentrations in incoming air masses (i.e. air mass history), rather than cloud liquid water content (LWC), were the main factor controlling bulk solute concentrations for the cloud studied. Droplet effective radius was found to be a somewhat better predictor for cloud water total ionic content (TIC) than LWC, even though no single explanatory variable can fully describe TIC (or solute concentration) variations in a simple functional relation due to the complex processes involved. Bulk concentrations typically agreed within a factor of 2 with co-located measurements of residual particle concentrations sampled by a counterflow virtual impactor (CVI) and analysed by an aerosol mass spectrometer (AMS), with the deviations being mainly caused by systematic

  8. Study on space charge compensation in negative hydrogen ion beam.

    PubMed

    Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E

    2016-02-01

    Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results. PMID:26932087

  9. Study on space charge compensation in negative hydrogen ion beam.

    PubMed

    Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E

    2016-02-01

    Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.

  10. Generalized stern models of the electric double layer considering the spatial variation of permittvity and finite size of ions in saturation regime.

    PubMed

    Gongadze, Ekaterina; Van Rienen, Ursula; Iglič, Aleš

    2011-12-01

    The interaction between a charged metal implant surface and a surrounding body fluid (electrolyte solution) leads to ion redistribution and thus to formation of an electrical double layer (EDL). The physical properties of the EDL contribute essentially to the formation of the complex implant-biosystem interface. Study of the EDL began in 1879 by Hermann von Helmholtz and still today remains a scientific challenge. The present mini review is focused on introducing the generalized Stern theory of an EDL, which takes into account the orientational ordering of water molecules. To ascertain the plausibility of the generalized Stern models described, we follow the classical model of Stern and introduce two Langevin models for spatial variation of the relative permittivity for point-like and finite sized ions. We attempt to uncover the subtle interplay between water ordering and finite sized ions and their impact on the electric potential near the charged implant surface. Two complementary effects appear to account for the spatial dependency of the relative permittivity near the charged implant surface - the dipole moment vectors of water molecules are predominantly oriented towards the surface and water molecules are depleted due to the accumulation of counterions. At the end the expressions for relative permittivity in both Langevin models were generalized by also taking into account the cavity and reaction field.

  11. Rational design of a minimal size sensor array for metal ion detection.

    PubMed

    Palacios, Manuel A; Wang, Zhuo; Montes, Victor A; Zyryanov, Grigory V; Anzenbacher, Pavel

    2008-08-01

    The focus of this study was to demonstrate that, in the luminescent sensors, the signal transduction may possibly be the most important part in the sensing process. Rational design of fluorescent sensor arrays for cations utilizing extended conjugated chromophores attached to 8-hydroxyquinoline is reported. All of the optical sensors utilized in the arrays comprise the same 8-hydroxyquinoline (8-HQ) receptor and various conjugated chromophores to yield a different response to various metal cations. This is because the conjugated chromophores attached to the receptor are partially quenched in their resting state, and upon the cation coordination by the 8-HQ, the resulting metalloquinolinolate complex displays a change in fluorescence. A delicate balance of conjugation, fluorescence enhancement, energy transfer, and a heavy metal quenching effect results in a fingerprint-like pattern of responses for each sensor-cation complex. Principal component analysis (PCA) and linear discriminant analysis (LDA) are used to demonstrate the contribution of individual sensors within the array, information that may be used to design sensor arrays with the smallest number of sensor elements. This approach allows discriminating between 10 cations by as few as two or even one sensor element. Examples of arrays comprising various numbers of sensor elements and their utility in qualitative identification of Ca(2+), Mg(2+), Cd(2+), Hg(2+), Co(2+), Zn(2+), Cu(2+), Ni(2+), Al(3+), and Ga(3+) ions are presented. A two-member array was found to identify 11 analytes with 100% accuracy. Also the best two of the sensors were tested alone and both were found to be able to discriminate among the samples with 99% and 96% accuracy, respectively. To illustrate the utility of this approach to a real-world application, identification of enhanced soft drinks based on their Ca(2+), Mg(2+), and Zn(2+) cation content was performed. The same approach to reducing array elements was used to construct three

  12. Capacitance of graphene in aqueous electrolytes: The effects of dielectric saturation of water and finite size of ions

    NASA Astrophysics Data System (ADS)

    Sharma, P.; Mišković, Z. L.

    2014-09-01

    We present a theoretical model for electrolytically top-gated graphene, in which we analyze the effects of dielectric saturation of water due to possibly strong electric fields near the surface of a highly charged graphene, as well as the steric effects due to the finite size of salt ions in an aqueous electrolyte. By combining two well-established analytical models for those two effects, we show that the total capacitance of the solution-gated graphene is dominated by its quantum capacitance for gating potentials ≲1V, which is the range of primary interest for most sensor applications of graphene. On the other hand, at the potentials ≳1V the total capacitance is dominated by a universal capacitance of the electric double layer in the electrolyte, which exhibits a dramatic decrease of capacitance with increasing gating potential due to the interplay of a fully saturated dielectric constant of water and ion crowding near graphene.

  13. Seasonal variations and size distributions of water-soluble ions of atmospheric particulate matter at Shigatse, Tibetan Plateau.

    PubMed

    Yang, Yongjie; Zhou, Rui; Yan, Yan; Yu, Yue; Liu, Junqing; Di, Yi'an; Du, Zhenyu; Wu, Dan

    2016-02-01

    Size-segregated atmospheric particulate matter (PM) samples were collected from July 2012 to September 2013 at Shigatse, high-altitude (3836 m above sea level) site on the south Tibetan Plateau (TP); objectives were to determine the characteristics and size distribution of water-soluble ions (WSIs). Eight major WSIs (Na(+), K(+), Mg(2+), Ca(2+), NH4(+), Cl(-), SO4(2-), and NO3(-)) were detected by ion chromatography. The total concentrations of WSIs were 6370 ± 1916 ng m(-3) in dry season (October - December, January - April), and 5261 ± 769 ng/m(3) during wet phase (May - September). The contribution of K(+) (130 ng m(-3)), Cl(-) (2035 ng m(-3)), SO4(2-) (1176 ng m(-3)), and NO3(-) (706 ng m(-3))(-)were significantly enhanced in dry season, and that of Na(+) (455 ng m(-3)), Mg(2+)(65.4 ng m(-3)), Ca(2+)(1034 ng m(-3)), and NH4(+) (1948 ng m(-3)) were significantly enhanced during wet phase. Mg(2+) and Ca(2+) were concentrated in the coarse mode, and the other ions concentrated in fine mode and coarse mode during two seasons. The correlation coefficients between K(+) and NH4(+), Cl(-), SO4(2-) and NO3(-) were 0.58 (P < 0.01), 0.40 (P < 0.05), 0.82 (P < 0.01) and 0.69 (P < 0.01), indicating their dominant contribution from biomass burning in dry season. The significant correlation between NH4(+) and HCO3(-) which were calculated by ion balance (r = 0.89, P < 0.01), suggesting the source from nitrogen fertilizers during wet phase.

  14. A Study of Single-Pass Ion Effects at the ALS.

    NASA Astrophysics Data System (ADS)

    Byrd, J. M.; Thomson, J.; Chao, A. W.; Heifets, S.; Minty, M. G.; Seeman, J. T.; Stupakov, G. V.; Zimmermann, F.; Raubenheimer, T. O.

    1997-05-01

    We report studies of single-pass ion effects performed at the Advanced Light Source (ALS). To enhance the ion effects, the ALS vacuum pressure was intentionally increased to about 50 nTorr by a remotely controlled inflow of helium gas. At this pressure we observe, on a synchrotron light monitor, a blowup of the vertical beam size for as few as 10 consecutive bunches (97% empty ring). No blow-up is observed when a single bunch is stored in the ring. For gaps in the fill pattern of 25 and 50%, where conventional ion trapping is not expected, we observe an approximate doubling of the vertical emittance. Nonuniform beam loss for vertical beam scraping indicates that the tail of the bunch train is driven by the instabilty more than the head. Therefore, the blow-up appears to be caused by a single-pass ion effect. In some but not all studies we also observed coherent vertical betatron oscillations, as evidenced by a pattern of lower betatron sidebands, whose envelope peaked around the estimated ion frequency. Both the beam-size blow-up and the betatron sidebands are consistent with theoretical predictions for the `fast beam-ion instability'.

  15. Sample size calculation for meta-epidemiological studies.

    PubMed

    Giraudeau, Bruno; Higgins, Julian P T; Tavernier, Elsa; Trinquart, Ludovic

    2016-01-30

    Meta-epidemiological studies are used to compare treatment effect estimates between randomized clinical trials with and without a characteristic of interest. To our knowledge, there is presently nothing to help researchers to a priori specify the required number of meta-analyses to be included in a meta-epidemiological study. We derived a theoretical power function and sample size formula in the framework of a hierarchical model that allows for variation in the impact of the characteristic between trials within a meta-analysis and between meta-analyses. A simulation study revealed that the theoretical function overestimated power (because of the assumption of equal weights for each trial within and between meta-analyses). We also propose a simulation approach that allows for relaxing the constraints used in the theoretical approach and is more accurate. We illustrate that the two variables that mostly influence power are the number of trials per meta-analysis and the proportion of trials with the characteristic of interest. We derived a closed-form power function and sample size formula for estimating the impact of trial characteristics in meta-epidemiological studies. Our analytical results can be used as a 'rule of thumb' for sample size calculation for a meta-epidemiologic study. A more accurate sample size can be derived with a simulation study.

  16. Ion collision cross section analyses in quadrupole ion traps using the filter diagonalization method: a theoretical study.

    PubMed

    Jiang, Ting; He, Miyi; Guo, Dan; Zhai, Yanbing; Xu, Wei

    2016-04-28

    Previously, we have demonstrated the feasibility of measuring ion collision cross sections (CCSs) within a quadrupole ion trap by performing time-frequency analyses of simulated ion trajectories. In this study, an improved time-frequency analysis method, the filter diagonalization method (FDM), was applied for data analyses. Using the FDM, high resolution could be achieved in both time- and frequency-domains when calculating ion time-frequency curves. Owing to this high-resolution nature, ion-neutral collision induced ion motion frequency shifts were observed, which further cause the intermodulation of ion trajectories and thus accelerate image current attenuation. Therefore, ion trap operation parameters, such as the ion number, high-order field percentage and buffer gas pressure, were optimized for ion CCS measurements. Under optimized conditions, simulation results show that a resolving power from 30 to more than 200 could be achieved for ion CCS measurements. PMID:27066889

  17. Research and development optical deep space antenna sizing study

    NASA Technical Reports Server (NTRS)

    Wonica, D.

    1994-01-01

    Results from this study provide a basis for the selection of an aperture size appropriate for a research and development ground-based receiver for deep space optical communications. Currently achievable or near-term realizable hardware performance capabilities for both a spacecraft optical terminal and a ground terminal were used as input parameters to the analysis. Links were analyzed using OPTI, our optical link analysis program. Near-term planned and current missions were surveyed and categorized by data rate and telecommunications-subsystems prime power consumption. The spacecraft optical-terminal transmitter power was selected by matching these (RF) data rates and prime power requirements and by applying power efficiencies suitable to an optical communications subsystem. The study was baselined on a Mars mission. Results are displayed as required ground aperture size for given spacecraft transmitter aperture size, parametrized by data rate, transmit optical power, and wavelength.

  18. Hydrogenated Anatase TiO2 as Lithium-Ion Battery Anode: Size-Reactivity Correlation.

    PubMed

    Zheng, Jing; Liu, Lei; Ji, Guangbin; Yang, Qifan; Zheng, Lirong; Zhang, Jing

    2016-08-10

    An improved hydrogenation strategy for controllable synthesis of oxygen-deficient anatase TiO2 (H-TiO2) is performed via adjusting the particle size of starting rectangular anatase TiO2 nanosheets from 90 to 30 nm. The morphology and structure characterizations obviously demonstrate that the starting materials of TiO2 nanosheets are transformed into nanoparticles with distinct size reduction; meanwhile, the concentration of oxygen vacancy is gradually increased with the decreasing particle size of starting TiO2. As a result, the Li-storage performance of H-TiO2 is not only much better than that of the pure TiO2 but also elevated stage by stage with the decreasing particle size of starting TiO2; especially the H-TiO2 with highest concentration of oxygen vacancy from smallest TiO2 nanosheets shows the best Li-storage performance with a stable discharge capacity 266 mAh g(-1) after 100 cycles at 1 C. Such excellent performance should be attributed to the joint action from oxygen vacancy and size effect, which promises significant enhancement of high electronic conductivity without weakening Li(+) diffusion via hydrogenation strategy. PMID:27434151

  19. Hydrogenated Anatase TiO2 as Lithium-Ion Battery Anode: Size-Reactivity Correlation.

    PubMed

    Zheng, Jing; Liu, Lei; Ji, Guangbin; Yang, Qifan; Zheng, Lirong; Zhang, Jing

    2016-08-10

    An improved hydrogenation strategy for controllable synthesis of oxygen-deficient anatase TiO2 (H-TiO2) is performed via adjusting the particle size of starting rectangular anatase TiO2 nanosheets from 90 to 30 nm. The morphology and structure characterizations obviously demonstrate that the starting materials of TiO2 nanosheets are transformed into nanoparticles with distinct size reduction; meanwhile, the concentration of oxygen vacancy is gradually increased with the decreasing particle size of starting TiO2. As a result, the Li-storage performance of H-TiO2 is not only much better than that of the pure TiO2 but also elevated stage by stage with the decreasing particle size of starting TiO2; especially the H-TiO2 with highest concentration of oxygen vacancy from smallest TiO2 nanosheets shows the best Li-storage performance with a stable discharge capacity 266 mAh g(-1) after 100 cycles at 1 C. Such excellent performance should be attributed to the joint action from oxygen vacancy and size effect, which promises significant enhancement of high electronic conductivity without weakening Li(+) diffusion via hydrogenation strategy.

  20. Size dependent electrochemical detection of trace heavy metal ions based on nano-patterned carbon sphere electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Lu-Hua; Li, Wen-Cui; Yan, Dong; Wang, Hua; Lu, An-Hui

    2016-07-01

    The challenge in efficient electrochemical detection of trace heavy metal ions (HMI) for early warning is to construct an electrode with a nano-patterned architecture. In this study, a range of carbon electrodes with ordered structures were fabricated using colloidal hollow carbon nanospheres (HCSs) as sensing materials for trace HMI (represented by Pb(ii)) detection by square wave anodic stripping voltammetry. The regular geometrical characteristics of the carbon electrode allow it to act as a model system for the estimation of electron transfer pathways by calculating contact points between HCSs and a glassy carbon electrode. A clear correlation between the contact points and the electron transfer resistance has been established, which fits well with the quadratic function model and is dependent on the size of HCSs. To our knowledge, this is the first clear function that expresses the structure-sensing activity relationship of carbon-based electrodes. The prepared carbon electrode is capable of sensing Pb(ii) with a sensitivity of 0.160 μA nM-1, which is much higher than those of other electrodes reported in the literature. Its detection limit of 0.6 nM is far below the guideline value (72 nM) given by the US Environmental Protection Agency. In addition, the carbon electrode could be a robust alternative to various heavy metal sensors.The challenge in efficient electrochemical detection of trace heavy metal ions (HMI) for early warning is to construct an electrode with a nano-patterned architecture. In this study, a range of carbon electrodes with ordered structures were fabricated using colloidal hollow carbon nanospheres (HCSs) as sensing materials for trace HMI (represented by Pb(ii)) detection by square wave anodic stripping voltammetry. The regular geometrical characteristics of the carbon electrode allow it to act as a model system for the estimation of electron transfer pathways by calculating contact points between HCSs and a glassy carbon electrode. A

  1. Study of Cold Potassium Atom - Calcium Ion Reactions

    NASA Astrophysics Data System (ADS)

    Egodapitiya, Kisra; Gang, Shu; Clark, Robert; Brown, Kenneth

    2016-05-01

    We report on our progress towards constructing a hybrid system for studying reactions between cold Potassium (K) atoms and cold Calcium (Ca+) ions. Ca+ ions will be trapped and Doppler-cooled inside a linear quadrupole ion trap. Cold K atoms will be created inside a magneto optical trap, such that the ion and the atoms are in an overlapping volume. Trapping and re-pumping beams for the Potassium MOT are derived from the same laser with wavelength 766 nm using two acousto optic modulators. The reaction products will be detected using a time-of- flight mass spectrometer that is designed to detect radially ejected ions. The main objective of this experiment is to study the rate coefficients, and identification of reaction channels between cold K atoms and Ca+ ions. Subsequently this setup will be used to study reactions between cold K atoms and sympathetically cooled molecular ions such as CaO+, and to study internal state quenching of molecular ions.

  2. A new technique for the study of charge transfer in multiply charged ion-ion collisions

    SciTech Connect

    Shinpaugh, J.L.; Meyer, F.W.; Datz, S.

    1994-12-31

    While large cross sections (>10{sup {minus}16} cm{sup 2}) have been predicted for resonant charge transfer in ion-ion collisions, no experimental data exist for multiply charged systems. A novel technique is being developed at the ORNL ECR facility to allow study of symmetric charge exchange in multiply charged ion-ion collisions using a single ion source. Specific intra-beam charge transfer collisions occurring in a well-defined interaction region labeled by negative high voltage are identified and analyzed by electrostatic analysis in combination with ion time-of-flight coincidence detection of the collision products. Center-of-mass collision energies from 400 to 1000 eV are obtained by varying source and labeling-cell voltages. In addition, by the introduction of a target gas into the high-voltage cell, this labeling-voltage method allows measurement of electron-capture and -loss cross sections for ion-atom collisions. Consequently, higher collision energies can be investigated without the requirement of placing the ECR source on a high-voltage platform.

  3. Electron-spin-polarized He^+ ion source for studying ion-surface interaction dynamics

    NASA Astrophysics Data System (ADS)

    Bixler, D. L.; Lancaster, J. C.; Popple, R. A.; Dunning, F. B.; Walters, G. K.

    1997-03-01

    An electron-spin-polarized He^+ ion source has been developed to study the dynamics of ion-surface interactions. The He^+ ions are produced by Penning ionization in collisions between helium metastable atoms contained in a weak rf-excited discharge. The 2^3S metastable atoms in the discharge are polarized by optical pumping using a 300 mW Ti:sapphire laser tuned to the 2^3S_1-2^3P1 (D_1) transition at 1.083μm. Spin conservation during Penning ionization results in the production of polarized He^+ ions which are extracted from the discharge through a small canal and focused on the target surface using a series of electrostatic lenses, which reduce the energy spread in the beam to ~ 3 eV through chromatic abberation. Currents of ~ 10-9 A are achieved at ion energies of >= 10 eV. The ion beam polarization is determined by allowing the beam to strike a clean Au(100) surface and observing the polarization of the ejected secondary electrons. He^+ ion polarizations of ~ 10 % are routinely obtained, and work is underway to further improve this polarization. ^*Research supported by the U.S. Department of Energy and the Robert A. Welch Foundation. DLB is the recipient of a Texaco Fellowship.

  4. Electron-spin-polarized He^+ ion source for studying ion-surface interaction dynamics

    NASA Astrophysics Data System (ADS)

    Bixler, D. L.; Lancaster, J. C.; Popple, R. A.; Dunning, F. B.; Walters, G. K.

    1997-04-01

    An electron-spin-polarized He^+ ion source has been developed to study the dynamics of ion-surface interactions. The He^+ ions are produced by Penning ionization in collisions between helium metastable atoms contained in a weak rf-excited discharge. The 2^3S metastable atoms in the discharge are polarized by optical pumping using a 300 mW Ti:sapphire laser tuned to the 2^3S_1-2^3P1 (D_1) transition at 1.083μm. Spin conservation during Penning ionization results in the production of polarized He^+ ions which are extracted from the discharge through a small canal and focused on the target surface using a series of electrostatic lenses, which reduce the energy spread in the beam to ~ 3 eV through chromatic abberation. Currents of ~ 10-9 A are achieved at ion energies of >= 10 eV. The ion beam polarization is determined by allowing the beam to strike a clean Au(100) surface and observing the polarization of the ejected secondary electrons. He^+ ion polarizations of ~ 10 % are routinely obtained, and work is underway to further improve this polarization. ^*Research supported by the U.S. Department of Energy and the Robert A. Welch Foundation.

  5. The contraction of granules of nanoporous super-cross-linked polystyrene sorbents as a result of the exclusion of large-sized mineral electrolyte ions from the polymer phase

    NASA Astrophysics Data System (ADS)

    Pastukhov, A. V.; Davankov, V. A.; Tsyurupa, M. P.; Blinnikova, Z. K.; Kavalerskaya, N. E.

    2009-03-01

    The deformation of neutral super-cross-linked polystyrene sorbents and ionites based on styrene-divinylbenzene gel-type copolymers brought in contact with concentrated solutions of HCl, H3PO4, NaOH, NH4Cl, (NH4)2SO4, and LiCl electrolytes was studied by dilatometry for separate spherical granules. Considerable contraction of super-cross-linked polystyrene matrices swollen in water was observed in concentrated solutions containing large-sized lithium, sulfate, and phosphate ions. Volume compressive strain correlated with the size of excluded hydrated ions. The contraction effect was caused by the difference in the osmotic pressure of water in thin pores and water in concentrated solutions filling large pores. The exclusion effect ignored earlier should also influence the degree of ion exchange and volume deformation of standard ion-exchange resins brought in contact with solutions of various electrolytes.

  6. A study of single and binary ion plasma expansion into laboratory-generated plasma wakes

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth Herbert, Jr.

    1988-01-01

    Plasma expansion into the wake of a large rectangular plate immersed in a collisionless, supersonic plasma was investigated in laboratory experiments. The experimental conditions address both single ion and binary ion plasma flows for the case of a body whose size is large in comparison with the Debye length, when the potential difference between the body and the plasma is relatively small. A new plasma source was developed to generate equi-velocity, binary ion plasma flows, which allows access to new parameter space that have previously been unavailable for laboratory studies. Specifically, the new parameters are the ionic mass ratio and the ionic component density ratio. In a series of experiments, a krypton-neon plasma is employed where the ambient density ratio of neon to krypton is varied more than an order of magnitude. The expansion in both the single ion and binary ion plasma cases is limited to early times, i.e., a few ion plasma periods, by the combination of plasma density, plasma drift speed, and vacuum chamber size, which prevented detailed comparison with self-similar theory.

  7. Thermal characterization of large size lithium-ion pouch cell based on 1d electro-thermal model

    NASA Astrophysics Data System (ADS)

    Vertiz, G.; Oyarbide, M.; Macicior, H.; Miguel, O.; Cantero, I.; Fernandez de Arroiabe, P.; Ulacia, I.

    2014-12-01

    Thermal management is one of the key factors to keep lithium-ion cells in optimum electrical performance, under safe working conditions and into a reasonably low ageing process. This issue is becoming particularly relevant due to the heterogeneous heat generation along the cell. Cell working temperature is determined by ambient temperature, heat generation and evacuation capacity. Therefore, thermal management is established by: i) the intrinsic thermal properties (heat capacity & thermal conductivity) and ii) the heat generation electro-thermal parameters (internal resistance, open circuit voltage & entropic factor). In this research, different methods - calculated and experimental - are used to characterize the main heat properties of a 14Ah -LiFePO4/graphite-commercial large sizes pouch cell. In order to evaluate the accuracy of methods, two comparisons were performed. First, Newman heat generation estimations were compared with experimental heat measurements. Secondly, empirical thermal cell behaviour was match with 1D electro-thermal model response. Finally, considering the results, the most adequate methodology to evaluate the key thermal parameters of a large size Lithium-ion pouch cell are proposed to be: i) pulse method for internal resistance, ii)heat loss method for entropic factor; and iii)experimental measurement (ARC calorimeter and C-177-97 standard method) for heat capacity and thermal conductivity.

  8. Subnanometer poly-silicon gap structure formation: Comparison study between size expansion and size reduction

    NASA Astrophysics Data System (ADS)

    Hashim, U.; Nazwa, T.; Dhahi, Th. S.

    2012-06-01

    This study describes the comparison among the three fabrication methods of an array of poly-silicon nanogap structures. The three different methods are size expansion technique (SET), size reduction technique (SRT) and e-beam lithography (EBL) technique. Generally, SRT involves the breaking of the primarily pattern with no gap structure into nanogap scale. Conversely, SET engages in the process of enhancing the initially microgap pattern into nanogap scale. EBL refers to a lithographic process that uses a focused beam of electrons to form the circuit patterns needed for material deposition on or removal from the wafer. Using conventional photolithography, a procedure to fabricate poly-silicon nanogap structure on the wafer scale is designed. The nanogap (NG) fabrication procedure is based on the standard CMOS technology follows by employing both methods respectively. The lateral nanogap is introduced in the fabrication process using poly-silicon as an anode electrode. The similarity and distinction will be highlighted for each particular process involved in the fabrication of nanogap structures. The simple least-cost method does not require complicated nanolithography method of fabrication but it is still possible to measure the electrical properties of a single molecule. On top of that, these techniques can be applied extensively to different designs of nanogap structure down to several nanometer levels of dimensions. The innovative method reported here can easily produce a nanogap electrode in a reproducible manner.

  9. Theoretical study of the thioformyl ion

    NASA Technical Reports Server (NTRS)

    Wilson, S.

    1978-01-01

    The equilibrium structure of the thioformyl ion has been determined from an ab initio matrix Hartree-Fock calculation, and an estimated rotation constant has been derived. A rotation constant of 21.7 GHz is obtained for HCS(+); the corresponding constant for DCS(+) is 18.3 GHz. If the vibration-rotation interaction constants for HCS(+) are assumed to be the same as those for HCP, then the rotation constant is 21.6 GHz, while the vibration-rotation constants of DCP give a rotation constant of 18.3 GHz for DCS(+).

  10. Atrial inflow can alter regurgitant jet size: in vitro studies.

    PubMed

    Grimes, R Y; Nyarko, S J; Pulido, G A; Yang, S; Walker, P G; Levine, R A; Yoganathan, A P

    1995-01-01

    Recent studies have attempted to predict the severity of regurgitant lesions from color Doppler jet size, which is a function of orifice momentum for free jets. Jets of mitral and tricuspid regurgitation, however, are opposed by flows entering the atria. Despite their low velocities, these counterflows may have considerable momentum that can limit jet penetration. The purpose of this study was to address the hypothesis that such counterflow fields influence regurgitant jet size. Steady flow was driven through 2.4- and 5.1-mm-diameter circular orifices at 2 to 6 m/s. At a constant orifice velocity and flow rate, the velocity of a uniform counterflow field was varied from 5 to 30 cm/s. Jet dimensions were measured by both fluorescent dye visualization and Doppler color flow mapping. The results showed that despite its relatively low velocities, counterflow dramatically curtailed jet length and area. Jet dimensions were functions of the ratio of jet to counterflow momentum. Thus, atrial inflow may participate in determining jet size and can alter the relation between jet size and lesion severity in mitral and tricuspid regurgitation.

  11. Size effects on insect hovering aerodynamics: an integrated computational study.

    PubMed

    Liu, H; Aono, H

    2009-03-01

    Hovering is a miracle of insects that is observed for all sizes of flying insects. Sizing effect in insect hovering on flapping-wing aerodynamics is of interest to both the micro-air-vehicle (MAV) community and also of importance to comparative morphologists. In this study, we present an integrated computational study of such size effects on insect hovering aerodynamics, which is performed using a biology-inspired dynamic flight simulator that integrates the modelling of realistic wing-body morphology, the modelling of flapping-wing and body kinematics and an in-house Navier-Stokes solver. Results of four typical insect hovering flights including a hawkmoth, a honeybee, a fruit fly and a thrips, over a wide range of Reynolds numbers from O(10(4)) to O(10(1)) are presented, which demonstrate the feasibility of the present integrated computational methods in quantitatively modelling and evaluating the unsteady aerodynamics in insect flapping flight. Our results based on realistically modelling of insect hovering therefore offer an integrated understanding of the near-field vortex dynamics, the far-field wake and downwash structures, and their correlation with the force production in terms of sizing and Reynolds number as well as wing kinematics. Our results not only give an integrated interpretation on the similarity and discrepancy of the near- and far-field vortex structures in insect hovering but also demonstrate that our methods can be an effective tool in the MAVs design. PMID:19258688

  12. Size effects on insect hovering aerodynamics: an integrated computational study.

    PubMed

    Liu, H; Aono, H

    2009-03-01

    Hovering is a miracle of insects that is observed for all sizes of flying insects. Sizing effect in insect hovering on flapping-wing aerodynamics is of interest to both the micro-air-vehicle (MAV) community and also of importance to comparative morphologists. In this study, we present an integrated computational study of such size effects on insect hovering aerodynamics, which is performed using a biology-inspired dynamic flight simulator that integrates the modelling of realistic wing-body morphology, the modelling of flapping-wing and body kinematics and an in-house Navier-Stokes solver. Results of four typical insect hovering flights including a hawkmoth, a honeybee, a fruit fly and a thrips, over a wide range of Reynolds numbers from O(10(4)) to O(10(1)) are presented, which demonstrate the feasibility of the present integrated computational methods in quantitatively modelling and evaluating the unsteady aerodynamics in insect flapping flight. Our results based on realistically modelling of insect hovering therefore offer an integrated understanding of the near-field vortex dynamics, the far-field wake and downwash structures, and their correlation with the force production in terms of sizing and Reynolds number as well as wing kinematics. Our results not only give an integrated interpretation on the similarity and discrepancy of the near- and far-field vortex structures in insect hovering but also demonstrate that our methods can be an effective tool in the MAVs design.

  13. Polarization Studies in Fast-Ion Beam Spectroscopy

    SciTech Connect

    Trabert, E

    2001-12-20

    In a historical review, the observations and the insight gained from polarization studies of fast ions interacting with solid targets are presented. These began with J. Macek's recognition of zero-field quantum beats in beam-foil spectroscopy as indicating alignment, and D.G. Ellis' density operator analysis that suggested the observability of orientation when using tilted foils. Lastly H. Winter's studies of the ion-beam surface interaction at grazing incidence yielded the means to produce a high degree of nuclear orientation in ion beams.

  14. Study of the storm time fluxes of heavy ions

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The characteristics of the storm time ring current ions in the energy range of 0.5 to 16 keV were investigated. Data were processed and analyzed from the energetic ion mass spectrometer aboard the S3-3 satellite. Results are used for planning and operating the ion mass spectrometer experiment on the ISEE spacecraft, for selecting and processing the ISEE ion data, and for planning and conducting coordinated satellite experiments in support of the International Magnetospheric Study (IMS). It is established from the S3-3 ion data that relatively large fluxes of energetic (keV) 0(+) and H(+) ions are frequently flowing upward from the ionosphere along magnetic field lines in the polar auroral regions. Also, from investigations with the same instrument during the main phase of three moderate (D sub ST approximately 100) magnetic storms, it is found that the number density of 0(+) ions in the ring current was comparable to H(+) ion density the range 0.5 to 15 keV.

  15. Heavy Ion Effects on Kelvin-Helmholtz Instability: Hybrid Study

    NASA Astrophysics Data System (ADS)

    Burgess, D.; Lin, D.

    2015-12-01

    Kelvin-Helmholtz instability (KHI) is a candidate mechanism for solar wind tansportation into the magnetosphere. The statistical study of Bouhram et al. 2005 has shown that heavy ions could dominate the magnetopause for as much as 30% of the time on the dusk side. Thus the influence of heavy ions in solar wind-magnetosphere coupling should not be neglected. However, the magnetohydrodynamic (MHD) linear theory for KHI does not include any ion effects, and people working on the heavy ion effects have not come to an agreement either. Whether the heavy ions promote or inhibit the KHI still remains not well addressed. With a two-dimensional hybrid model, we investigated the effects of ion mass number on the KHI growth rate, starting from the simplest case of uniform density and uniform magnetic field perpendicular to the shear flow. It is shown that the growth rate of the KHI is lower with a heavier mass number. We try to to derive the linear theory for the kinetic KHI and compare it with the hybrid simulation results. The linear theory with ion effects considered is going to be further verified with varying heavy ion fractions and finite magnetic shear. More implications for the dawn-dusk asymmetry of KHI on planetary magnetopause are desirable when comparing the results of opposite magnetic field directions relative to the flow vorticity.

  16. Ion beam studies of hydrogen in metals

    SciTech Connect

    Myers, S.M.; Wampler, W.R.; Besenbacher, F.; Robinson, S.L.; Moody, N.R.

    1984-01-01

    Methods based on ion implantation and nuclear reaction analysis were used to investigate the behavior of hydrogen isotopes in metals. The binding enthalpy of deuterium (D) at irradiation effects, He bubbles, D/sub 2/ bubbles, and metal-oxide interfaces was measured for Al, Fe, Ni, Cu, Pd, austenitic stainless steel, Inconel, and amorphous Fe/sub 40/Ni/sub 40/P/sub 14/B/sub 6/. The binding enthalpies determined for the pure metals are in excellent agreement with mechanistic calculations based on effective-medium theory and other information. Surface-limited release of D from Fe, stainless steel, and Inconel was measured as a function of temperature and the state of surface oxidation. The release rate was accurately proportional to the square of the D concentration in solution, permitting the results to be expressed in terms of a surface recombination coefficient. This quantity was up to four orders of magnitude greater for an ion-sputtered surface than for a surface with electropolish oxide. The diffusion coefficient and solid solubility of tritium in stainless steel were measured for the first time at the ice point, thereby extending downward by three orders of magnitude the diffusivities available from conventional permeation experiments. Deuterium concentration profiles resulting from electrochemical charging of Incoloy 903 were measured as a function of charging current, thereby providing a direct, systematic calibration of such charging in an austenitic material where conventional permeation measurements are precluded by the small hydrogen diffusion rate.

  17. ESR studies on pet irradiated with high energy ions

    NASA Astrophysics Data System (ADS)

    Chipară, Mircea Ioan; Bunget, Ion; Georgescu, Rodica; Georgescu, Edith; Vîlcov, Isabela

    1983-05-01

    Electron spin resonance studies on polyethylene terephtalate films, irradiated with high energy oxygen and sulphur ions are reported. The dependence of the resonance line parameters on time, temperature and on UV postirradiation time is investigated.

  18. Sample size considerations for clinical research studies in nuclear cardiology.

    PubMed

    Chiuzan, Cody; West, Erin A; Duong, Jimmy; Cheung, Ken Y K; Einstein, Andrew J

    2015-12-01

    Sample size calculation is an important element of research design that investigators need to consider in the planning stage of the study. Funding agencies and research review panels request a power analysis, for example, to determine the minimum number of subjects needed for an experiment to be informative. Calculating the right sample size is crucial to gaining accurate information and ensures that research resources are used efficiently and ethically. The simple question "How many subjects do I need?" does not always have a simple answer. Before calculating the sample size requirements, a researcher must address several aspects, such as purpose of the research (descriptive or comparative), type of samples (one or more groups), and data being collected (continuous or categorical). In this article, we describe some of the most frequent methods for calculating the sample size with examples from nuclear cardiology research, including for t tests, analysis of variance (ANOVA), non-parametric tests, correlation, Chi-squared tests, and survival analysis. For the ease of implementation, several examples are also illustrated via user-friendly free statistical software.

  19. A Basic Study on Cost Based Lot Sizing

    NASA Astrophysics Data System (ADS)

    Sashio, Kentaro; Kaihara, Toshiya; Fujii, Susumu; Inao, Shinya

    To deal with the diversification of consumers' needs and to survive in the severe competitive environment, a grate deal of effort has been paid by manufacturers. Respecting the background, importance of effective lot sizing has been focused. Although variety of lot sizing algorithms has been proposed, most of their objective functions are based on time and quantity criteria. However, it is difficult to select an appropriate criterion universally, because the most important criterion is changed dynamically in real manufacturing environment. Then product cost seems to be a universal criterion, since profit is generally quite important factor in manufacturing enterprises. On the other hand, a concept of Distributed Virtual Factory (DVF) has been proposed as a new simulation environment for evaluating the performance of whole manufacturing systems. By performing simulation with DVF, all the information required to product cost calculation can be obtained. In this study, we propose an effective lot sizing methodology which performs Activity Based Costing (ABC) and minimizes product cost directly. We clarify the validity of the proposed lot sizing method through simulation experiments with DVF.

  20. Sample size considerations for clinical research studies in nuclear cardiology.

    PubMed

    Chiuzan, Cody; West, Erin A; Duong, Jimmy; Cheung, Ken Y K; Einstein, Andrew J

    2015-12-01

    Sample size calculation is an important element of research design that investigators need to consider in the planning stage of the study. Funding agencies and research review panels request a power analysis, for example, to determine the minimum number of subjects needed for an experiment to be informative. Calculating the right sample size is crucial to gaining accurate information and ensures that research resources are used efficiently and ethically. The simple question "How many subjects do I need?" does not always have a simple answer. Before calculating the sample size requirements, a researcher must address several aspects, such as purpose of the research (descriptive or comparative), type of samples (one or more groups), and data being collected (continuous or categorical). In this article, we describe some of the most frequent methods for calculating the sample size with examples from nuclear cardiology research, including for t tests, analysis of variance (ANOVA), non-parametric tests, correlation, Chi-squared tests, and survival analysis. For the ease of implementation, several examples are also illustrated via user-friendly free statistical software. PMID:26403142

  1. Reusable Launch Vehicle Tank/Intertank Sizing Trade Study

    NASA Technical Reports Server (NTRS)

    Dorsey, John T.; Myers, David E.; Martin, Carl J.

    2000-01-01

    A tank and intertank sizing tool that includes effects of major design drivers, and which allows parametric studies to be performed, has been developed and calibrated against independent representative results. Although additional design features, such as bulkheads and field joints, are not currently included in the process, the improved level of fidelity has allowed parametric studies to be performed which have resulted in understanding of key tank and intertank design drivers, design sensitivities, and definition of preferred design spaces. The sizing results demonstrated that there were many interactions between the configuration parameters of internal/external payload, vehicle fineness ratio (half body angle), fuel arrangement (LOX-forward/LOX-aft), number of tanks, and tank shape/arrangement (number of lobes).

  2. Study of the negative ion extraction mechanism from a double-ion plasma in negative ion sources

    SciTech Connect

    Goto, I.; Nishioka, S.; Hatayama, A.; Miyamoto, K.

    2015-04-08

    We have developed a 2D3V-PIC model of the extraction region, aiming to clarify the basic extraction mechanism of H{sup −} ions from the double-ion plasma in H{sup −} negative ion sources. The result shows the same tendency of the H{sup −} ion density n{sub H{sup −}} as that observed in the experiments, i.e.,n{sub H{sup −}} in the upstream region away from the plasma meniscus (H{sup −} emitting surface) has been reduced by applying the extraction voltage. At the same time, relatively slow temporal oscillation of the electric potential compared with the electron plasma frequency has been observed in the extraction region. Results of the systematic study using a 1D3V-PIC model with the uniform magnetic field confirm the result that the electrostatic oscillation is identified to be lower hybrid wave. The effect of this oscillation on the H{sup −} transport will be studied in the future.

  3. SnSb micron-sized particles for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Simonin, L.; Lafont, U.; Kelder, E. M.

    Micrometre-sized particles of Sn/SnSb were produced with a simple technique consisting in melting commercial ingots of tin and antimony separately at 280 °C and 680 °C, respectively, and casting them together in a ceramic boat. The solid alloy was then crushed into a homogeneous powder by grinding and sieving. The obtained powder was characterised by X-ray diffraction, and electron microscopy. Elemental and phase composition analyses were performed via, inductive coupled plasma and differential scanning calorimetry, respectively. The material was further tested as electrode material in a lithium galvanic cell. It showed relatively good capacity retention for at least 15 cycles. TEM analysis on post-mortem electrode samples showed the formation of nanostructures after the first discharge followed by a progressive disappearance of the micron-sized particles upon further cycling. Fading at higher cycles is explained by the formation of isolated metallic nano-particles that become inactive for further storage of lithium.

  4. A simulation study of linear RF ion guides for AMS

    NASA Astrophysics Data System (ADS)

    Zhao, X.-L.; Litherland, A. E.

    2015-02-01

    The use of radiofrequency multipoles and particularly the radiofrequency quadrupole (RFQ) controlled gas cell to facilitate on-line isobar separations for Accelerator Mass Spectrometry (AMS) is being explored experimentally and theoretically in a preliminary way at present. These new methods have the potential to extend greatly the analytical scope of AMS. However, there are many technical challenges to adapt an RF gas cell isobar separating device and still maintain stable and high transmission for routine AMS using the high current Cs+ sputter ion sources developed for nuclear physics and adapted to the detection of rare radioactive isotopes for AMS. An overview of linear RF ion guide properties is therefore needed to assist in the conceptualization of their efficient additions into AMS. In this work the intrinsic properties of linear RF ion guides, which are relevant to the generation of the RF induced ion energy distributions and for the evaluation of the ion transmissions in vacuum, are systematically studied using SIMION 8.1. These properties are compared among radiofrequency quadrupole, hexapole and octupole ion guides, so that their usefulness for AMS applications can be evaluated and compared. By simulation it is found that to prepare a typical RF captured AMS ion beam to within a safe range of ion energies prior to the onset of gas interactions, a higher multipole is more suitable for the first RF field receptor, while a quadrupole operated with q2 ∼ 0.5 is more suited as the final ion guide for concentrating the energy-cooled ions near axis.

  5. Tooth Wear Prevalence and Sample Size Determination : A Pilot Study

    PubMed Central

    Abd. Karim, Nama Bibi Saerah; Ismail, Noorliza Mastura; Naing, Lin; Ismail, Abdul Rashid

    2008-01-01

    Tooth wear is the non-carious loss of tooth tissue, which results from three processes namely attrition, erosion and abrasion. These can occur in isolation or simultaneously. Very mild tooth wear is a physiological effect of aging. This study aims to estimate the prevalence of tooth wear among 16-year old Malay school children and determine a feasible sample size for further study. Fifty-five subjects were examined clinically, followed by the completion of self-administered questionnaires. Questionnaires consisted of socio-demographic and associated variables for tooth wear obtained from the literature. The Smith and Knight tooth wear index was used to chart tooth wear. Other oral findings were recorded using the WHO criteria. A software programme was used to determine pathological tooth wear. About equal ratio of male to female were involved. It was found that 18.2% of subjects have no tooth wear, 63.6% had very mild tooth wear, 10.9% mild tooth wear, 5.5% moderate tooth wear and 1.8 % severe tooth wear. In conclusion 18.2% of subjects were deemed to have pathological tooth wear (mild, moderate & severe). Exploration with all associated variables gave a sample size ranging from 560 – 1715. The final sample size for further study greatly depends on available time and resources. PMID:22589636

  6. Size and dopant-concentration dependence of photoluminescence properties of ion-implanted phosphorus- and boron-codoped Si nanocrystals

    NASA Astrophysics Data System (ADS)

    Nakamura, Toshihiro; Adachi, Sadao; Fujii, Minoru; Sugimoto, Hiroshi; Miura, Kenta; Yamamoto, Shunya

    2015-04-01

    We investigate the nanocrystallite-size and dopant-concentration dependence of the photoluminescence (PL) properties of heavily phosphorus- (P) and boron- (B) codoped Si nanocrystals (Si NCs), prepared using a combination of sputtering and ion implantation techniques. We find that the heavily doped Si NC exhibits three exotic luminescence bands, A, B, and C. The peak energy of band A redshifts with increasing dopant concentration. This band is due to the band-to-band transition at the reduced Si-NC band gap caused by the formation of impurity bands together with band-tailing effects. The PL redshift becomes large when the nanocrystallite size decreases, suggesting the occurrence of the quantum-confinement-induced carrier doping effect. The peak energies of bands B and C are independent of both the concentration and size, indicating that these bands are due to transitions between defect- and/or impurity-related localized states. Band A shows stronger thermal quenching than the PL band in pure (undoped) Si NCs, the magnitude of which depends on the dopant concentration. The stronger thermal quenching in band A is probably due to the thermally induced migration of electrons in the impurity band.

  7. Comparative Study of Non-Enveloped Icosahedral Viruses Size

    PubMed Central

    Nikitin, Nikolai; Trifonova, Ekaterina; Evtushenko, Evgeniy; Kirpichnikov, Mikhail; Atabekov, Joseph; Karpova, Olga

    2015-01-01

    Now, as before, transmission electron microscopy (TEM) is a widely used technique for the determination of virions size. In some studies, dynamic light scattering (DLS) has also been applied for this purpose. Data obtained by different authors and using different methods could vary significantly. The process of TEM sample preparation involves drying on the substrate, which can cause virions to undergo morphology changes. Therefore, other techniques should be used for measurements of virions size in liquid, (i.e. under conditions closer to native). DLS and nanoparticle tracking analysis (NTA) provide supplementary data about the virions hydrodynamic diameter and aggregation state in liquid. In contrast to DLS, NTA data have a higher resolution and also are less sensitive to minor admixtures. In the present work, the size of non-enveloped icosahedral viruses of different nature was analyzed by TEM, DLS and NTA: the viruses used were the encephalomyocarditis virus (animal virus), and cauliflower mosaic virus, brome mosaic virus and bean mild mosaic virus (plant viruses). The same, freshly purified, samples of each virus were used for analysis using the different techniques. The results were compared with earlier published data and description databases. DLS data about the hydrodynamic diameter of bean mild mosaic virus, and NTA data for all examined viruses, were obtained for the first time. For all virus samples, the values of size obtained by TEM were less than virions sizes determined by DLS and NTA. The contribution of the electrical double layer (EDL) in virions hydrodynamic diameter was evaluated. DLS and NTA data adjusted for EDL thickness were in better agreement with TEM results. PMID:26545232

  8. Gold nanoparticles in aqueous solutions: influence of size and pH on hydrogen dissociative adsorption and Au(iii) ion reduction.

    PubMed

    Ershov, B G; Abkhalimov, E V; Solovov, R D; Roldughin, V I

    2016-05-21

    The shift of the localized surface plasmon resonance (LSPR) band of gold nanoparticles to shorter wavelengths upon saturation of the hydrosol with hydrogen is used as a tool to study the electrochemical processes on the particle surface. It is shown that dissociative adsorption of hydrogen takes place on the surface of a particle and results in the migration of a proton into the dispersion medium, while the electron remains on the nanoparticle, i.e., a hydrogen-like nanoelectrode is formed. It is shown that Au(iii) ions can be reduced on the gold nanoelectrodes. A thermodynamic scheme explaining the shift of the LSPR band is used to explain the peculiarities of the Au(iii) ion reduction. The reduction rate does not depend on the ion concentration and varies linearly with pH. The observed correlations are explained in terms of a simple model of electrochemical processes taking place on the nanoparticle as an electrode. It is shown that with an increase in the particle size, its capacity for dissociative adsorption of hydrogen decreases and the Au(iii) reduction slows down.

  9. Ion implantation in semiconductors studied by Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Langouche, G.

    1989-03-01

    The application of Mössbauer spectroscopy as an extremely sensitive characterization technique for ion-implanted semiconductors, is illustrated. Factors influencing the final landing site of implanted ions are first reviewed, as well as ion beam induced material modifications. Recent applications of Mössbauer spectroscopy in this field are then discussed including the study of supersaturated solutions of Sb and Sn in Si, the formation of epitaxial and buried silicides and the search for the DX-center in GaAs.

  10. Photoreflectance Study of Boron Ion-Implanted (100) Cadmium Telluride

    NASA Technical Reports Server (NTRS)

    Amirtharaj, P. M.; Odell, M. S.; Bowman, R. C., Jr.; Alt, R. L.

    1988-01-01

    Ion implanted (100) cadmium telluride was studied using the contactless technique of photoreflectance. The implantations were performed using 50- to 400-keV boron ions to a maximum dosage of 1.5 x 10(16)/sq cm, and the annealing was accomplished at 500 C under vacuum. The spectral measurements were made at 77 K near the E(0) and E(1) critical points; all the spectra were computer-fitted to Aspnes' theory. The spectral line shapes from the ion damaged, partially recovered and undamaged, or fully recovered regions could be identified, and the respective volume fraction of each phase was estimated.

  11. System-size independence of directed flow measured at the BNL relativistic heavy-ion collider.

    SciTech Connect

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Krueger, K.; Spinka, H. M.; Underwood, D. G.; High Energy Physics; Univ. of Illinois; Panjab Univ.; Variable Energy Cyclotron Centre; Kent State Univ.; Particle Physic Lab.; STAR Collaboration

    2008-01-01

    We measure directed flow (v{sub 1}) for charged particles in Au+Au and Cu+Cu collisions at {radical}s{sub NN} = 200 and 62.4 GeV, as a function of pseudorapidity ({eta}), transverse momentum (p{sub t}), and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all available model implementations, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to v{sub 1} in different collision systems, and investigate possible explanations for the observed sign change in v{sub 1}(p{sub t}).

  12. System-size independence of directed flow measured at the BNL relativistic heavy-ion collider.

    PubMed

    Abelev, B I; Aggarwal, M M; Ahammed, Z; Anderson, B D; Arkhipkin, D; Averichev, G S; Bai, Y; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Baumgart, S; Beavis, D R; Bellwied, R; Benedosso, F; Betts, R R; Bhardwaj, S; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Biritz, B; Bland, L C; Bombara, M; Bonner, B E; Botje, M; Bouchet, J; Braidot, E; Brandin, A V; Bueltmann, S; Burton, T P; Bystersky, M; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Callner, J; Catu, O; Cebra, D; Cendejas, R; Cervantes, M C; Chajecki, Z; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, J Y; Cheng, J; Cherney, M; Chikanian, A; Choi, K E; Christie, W; Chung, S U; Clarke, R F; Codrington, M J M; Coffin, J P; Cormier, T M; Cosentino, M R; Cramer, J G; Crawford, H J; Das, D; Dash, S; Daugherity, M; de Moura, M M; Dedovich, T G; Dephillips, M; Derevschikov, A A; Derradi de Souza, R; Didenko, L; Dietel, T; Djawotho, P; Dogra, S M; Dong, X; Drachenberg, J L; Draper, J E; Du, F; Dunlop, J C; Dutta Mazumdar, M R; Edwards, W R; Efimov, L G; Elhalhuli, E; Elnimr, M; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Eun, L; Fachini, P; Fatemi, R; Fedorisin, J; Feng, A; Filip, P; Finch, E; Fine, V; Fisyak, Y; Gagliardi, C A; Gaillard, L; Gangadharan, D R; Ganti, M S; Garcia-Solis, E; Ghazikhanian, V; Ghosh, P; Gorbunov, Y N; Gordon, A; Grebenyuk, O; Grosnick, D; Grube, B; Guertin, S M; Guimaraes, K S F F; Gupta, A; Gupta, N; Guryn, W; Haag, B; Hallman, T J; Hamed, A; Harris, J W; He, W; Heinz, M; Heppelmann, S; Hippolyte, B; Hirsch, A; Hoffman, A M; Hoffmann, G W; Hofman, D J; Hollis, R S; Huang, H Z; Hughes, E W; Humanic, T J; Igo, G; Iordanova, A; Jacobs, P; Jacobs, W W; Jakl, P; Jin, F; Jones, P G; Judd, E G; Kabana, S; Kajimoto, K; Kang, K; Kapitan, J; Kaplan, M; Keane, D; Kechechyan, A; Kettler, D; Khodyrev, V Yu; Kiryluk, J; Kisiel, A; Klein, S R; Knospe, A G; Kocoloski, A; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kouchpil, V; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kumar, A; Kumar, L; Kurnadi, P; Lamont, M A C; Landgraf, J M; Lange, S; Lapointe, S; Laue, F; Lauret, J; Lebedev, A; Lednicky, R; Lee, C-H; Levine, M J; Li, C; Li, Y; Lin, G; Lin, X; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, J; Liu, L; Ljubicic, T; Llope, W J; Longacre, R S; Love, W A; Lu, Y; Ludlam, T; Lynn, D; Ma, G L; Ma, J G; Ma, Y G; Mahapatra, D P; Majka, R; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Matis, H S; Matulenko, Yu A; McShane, T S; Meschanin, A; Millane, J; Miller, M L; Minaev, N G; Mioduszewski, S; Mischke, A; Mitchell, J; Mohanty, B; Morozov, D A; Munhoz, M G; Nandi, B K; Nattrass, C; Nayak, T K; Nelson, J M; Nepali, C; Netrakanti, P K; Ng, M J; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Okada, H; Okorokov, V; Olson, D; Pachr, M; Pal, S K; Panebratsev, Y; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Phatak, S C; Planinic, M; Pluta, J; Poljak, N; Porile, N; Poskanzer, A M; Potekhin, M; Potukuchi, B V K S; Prindle, D; Pruneau, C; Pruthi, N K; Putschke, J; Qattan, I A; Raniwala, R; Raniwala, S; Ray, R L; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Russcher, M J; Rykov, V; Sahoo, R; Sakrejda, I; Sakuma, T; Salur, S; Sandweiss, J; Sarsour, M; Schambach, J; Scharenberg, R P; Schmitz, N; Seger, J; Selyuzhenkov, I; Seyboth, P; Shabetai, A; Shahaliev, E; Shao, M; Sharma, M; Shi, S S; Shi, X-H; Sichtermann, E P; Simon, F; Singaraju, R N; Skoby, M J; Smirnov, N; Snellings, R; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Staszak, D; Stock, R; Strikhanov, M; Stringfellow, B; Suaide, A A P; Suarez, M C; Subba, N L; Sumbera, M; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Symons, T J M; Szanto de Toledo, A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thein, D; Thomas, J H; Tian, J; Timmins, A R; Timoshenko, S; Tokarev, M; Trainor, T A; Tram, V N; Trattner, A L; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Van Buren, G; van der Kolk, N; van Leeuwen, M; Vander Molen, A M; Varma, R; Vasconcelos, G M S; Vasilevski, I M; Vasiliev, A N; Videbaek, F; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Wada, M; Waggoner, W T; Wang, F; Wang, G; Wang, J S; Wang, Q; Wang, X; Wang, X L; Wang, Y; Webb, J C; Westfall, G D; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wu, J; Wu, Y; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yang, Y Y; Yepes, P; Yoo, I-K; Yue, Q; Zawisza, M; Zbroszczyk, H; Zhan, W; Zhang, H; Zhang, S; Zhang, W M; Zhang, Y; Zhang, Z P; Zhao, Y; Zhong, C; Zhou, J; Zoulkarneev, R; Zoulkarneeva, Y; Zuo, J X

    2008-12-19

    We measure directed flow (v_{1}) for charged particles in Au+Au and Cu+Cu collisions at sqrt[s_{NN}]=200 and 62.4 GeV, as a function of pseudorapidity (eta), transverse momentum (p_{t}), and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all available model implementations, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to v_{1} in different collision systems, and investigate possible explanations for the observed sign change in v_{1}(p_{t}). PMID:19113699

  13. System-size independence of directed flow at the RelativisticHeavy-Ion Collider

    SciTech Connect

    STAR Coll

    2008-09-20

    We measure directed flow (v{sub 1}) for charged particles in Au + Au and Cu + Cu collisions at {radical}s{sub NN} = 200 GeV and 62.4 GeV, as a function of pseudorapidity ({eta}), transverse momentum (p{sub t}) and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all available model implementations, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to v{sub 1} in different collision systems, and investigate possible explanations for the observed sign change in v{sub 1}(p{sub t}).

  14. Studies in High Current Density Ion Sources for Heavy Ion FusionApplications

    SciTech Connect

    Chacon-Golcher, E.

    2002-06-01

    This dissertation develops diverse research on small (diameter {approx} few mm), high current density (J {approx} several tens of mA/cm{sup 2}) heavy ion sources. The research has been developed in the context of a programmatic interest within the Heavy Ion Fusion (HIF) Program to explore alternative architectures in the beam injection systems that use the merging of small, bright beams. An ion gun was designed and built for these experiments. Results of average current density yield () at different operating conditions are presented for K{sup +} and Cs{sup +} contact ionization sources and potassium aluminum silicate sources. Maximum values for a K{sup +} beam of {approx}90 mA/cm{sup 2} were observed in 2.3 {micro}s pulses. Measurements of beam intensity profiles and emittances are included. Measurements of neutral particle desorption are presented at different operating conditions which lead to a better understanding of the underlying atomic diffusion processes that determine the lifetime of the emitter. Estimates of diffusion times consistent with measurements are presented, as well as estimates of maximum repetition rates achievable. Diverse studies performed on the composition and preparation of alkali aluminosilicate ion sources are also presented. In addition, this work includes preliminary work carried out exploring the viability of an argon plasma ion source and a bismuth metal vapor vacuum arc (MEVVA) ion source. For the former ion source, fast rise-times ({approx} 1 {micro}s), high current densities ({approx} 100 mA/cm{sup 2}) and low operating pressures (< 2 mtorr) were verified. For the latter, high but acceptable levels of beam emittance were measured ({var_epsilon}{sub n} {le} 0.006 {pi} mm {center_dot} mrad) although measured currents differed from the desired ones (I {approx} 5mA) by about a factor of 10.

  15. Plasma studies of the permanent magnet electron cyclotron resonance ion source at Peking University

    SciTech Connect

    Ren, H. T.; Peng, S. X. Xu, Y.; Zhao, J.; Lu, P. N.; Chen, J.; Zhang, A. L.; Zhang, T.; Guo, Z. Y.; Chen, J. E.

    2014-02-15

    At Peking University (PKU) we have developed several 2.45 GHz Permanent Magnet Electron Cyclotron Resonance ion sources for PKUNIFTY, SFRFQ, Coupled RFQ and SFRFQ, and Dielectric-Wall Accelerator (DWA) projects (respectively, 50 mA of D{sup +}, 10 mA of O{sup +}, 10 mA of He{sup +}, and 50 mA of H{sup +}). In order to improve performance of these ion sources, it is necessary to better understand the principal factors that influence the plasma density and the atomic ion fraction. Theoretical analysis about microwave transmission and cut-off inside the discharge chamber were carried out to study the influence of the discharge chamber diameters. As a consequence, experimental studies on plasma density and ion fraction with different discharge chamber sizes have been carried out. Due to the difficulties in measuring plasma density inside the discharge chamber, the output beam current was measured to reflect the plasma density. Experimental results show that the plasma density increases to the maximum and then decreases significantly as the diameter changed from 64 mm to 30 mm, and the atomic ion fraction has the same tendency. The maximum beam intensity was obtained with the diameter of 35 mm, but the maximum atomic ion fraction with a diameter of 40 mm. The experimental results are basically accordant with the theoretical calculation. Details are presented in this paper.

  16. Plasma studies of the permanent magnet electron cyclotron resonance ion source at Peking University

    NASA Astrophysics Data System (ADS)

    Ren, H. T.; Peng, S. X.; Xu, Y.; Zhao, J.; Lu, P. N.; Chen, J.; Zhang, A. L.; Zhang, T.; Guo, Z. Y.; Chen, J. E.

    2014-02-01

    At Peking University (PKU) we have developed several 2.45 GHz Permanent Magnet Electron Cyclotron Resonance ion sources for PKUNIFTY, SFRFQ, Coupled RFQ&SFRFQ, and Dielectric-Wall Accelerator (DWA) projects (respectively, 50 mA of D+, 10 mA of O+, 10 mA of He+, and 50 mA of H+). In order to improve performance of these ion sources, it is necessary to better understand the principal factors that influence the plasma density and the atomic ion fraction. Theoretical analysis about microwave transmission and cut-off inside the discharge chamber were carried out to study the influence of the discharge chamber diameters. As a consequence, experimental studies on plasma density and ion fraction with different discharge chamber sizes have been carried out. Due to the difficulties in measuring plasma density inside the discharge chamber, the output beam current was measured to reflect the plasma density. Experimental results show that the plasma density increases to the maximum and then decreases significantly as the diameter changed from 64 mm to 30 mm, and the atomic ion fraction has the same tendency. The maximum beam intensity was obtained with the diameter of 35 mm, but the maximum atomic ion fraction with a diameter of 40 mm. The experimental results are basically accordant with the theoretical calculation. Details are presented in this paper.

  17. Size distributions of nano/micron dicarboxylic acids and inorganic ions in suburban PM episode and non-episodic aerosol

    NASA Astrophysics Data System (ADS)

    Hsieh, Li-Ying; Kuo, Su-Ching; Chen, Chien-Lung; Tsai, Ying I.

    The distribution of nano/micron dicarboxylic acids and inorganic ions in size-segregated suburban aerosol of southern Taiwan was studied for a PM episode and a non-episodic pollution period, revealing for the first time the distribution of these nanoscale particles in suburban aerosols. Inorganic species, especially nitrate, were present in higher concentrations during the PM episode. A combination of gas-to-nuclei conversion of nitrate particles and accumulation of secondary photochemical products originating from traffic-related emissions was likely a crucial cause of the PM episode. Sulfate, ammonium, and oxalic acid were the dominant anion, cation, and dicarboxylic acid, respectively, accounting for a minimum of 49% of the total anion, cation or dicarboxylic acid mass. Peak concentrations of these species occurred at 0.54 μm in the droplet mode during both non-episodic and PM episode periods, indicating an association with cloud-processed particles. On average, sulfate concentration was 16-17 times that of oxalic acid. Oxalic acid was nevertheless the most abundant dicarboxylic acid during both periods, followed by succinic, malonic, maleic, malic and tartaric acid. The mass median aerodynamic diameter (MMAD) of oxalic acid was 0.77 μm with a bi-modal presence at 0.54 μm and 18 nm during non-episodic pollution and an MMAD of 0.67 μm with mono-modal presence at 0.54 μm in PM episode aerosol. The concomitant formation of malonic acid and oxalic acid was attributed to in-cloud processes. During the PM episode in the 5-100 nm nanoscale range, an oxalic acid/sulfate mass ratio of 40.2-82.3% suggested a stronger formation potential for oxalic acid than for sulfate in the nuclei mode. For total cations (TC), total inorganic anions (TIA) and total dicarboxylic acids (TDA), major contributing particles were in the droplet mode, with least in the nuclei mode. The ratio of TDA to TIA in the nuclei mode increased greatly from 8.40% during the non-episodic pollution

  18. Size-Controlled Synthesis of Copper Oxide Particles on Reduced Graphene Oxide for Lithium-Ion Battery Anode Applications.

    PubMed

    Jang, Haneul; Kim, Kyungbae; Chang, Hyejung; Kim, Jae-Hun; Choi, Hyunjoo

    2015-11-01

    Copper oxide/reduced graphene oxide (rGO) hybrids have been successfully synthesized by attaching copper ions onto the functional groups of GO by means of a solution process, which causes precipitation and agglomeration of copper oxides during subsequent thermal reduction of the GO. The resulting copper oxide/rGO hybrid exhibited improved electrochemical performance compared to monolithic CuO, which is presumed to be due to rGO acting as a mechanical support that buffers the volume change in copper oxides that occurs as a result of the conversion reaction during charge/discharge cycling. Furthermore, it was found that the size of the copper oxide particles can be optimized by adjusting the annealing time, with a hybrid annealed for 30 min achieving a reversible capacity of 544 mA h g(-1) and an initial coulombic efficiency of 62.7%.

  19. Seasonal variation and secondary formation of size-segregated aerosol water-soluble inorganic ions during pollution episodes in Beijing

    NASA Astrophysics Data System (ADS)

    Huang, Xiaojuan; Liu, Zirui; Zhang, Junke; Wen, Tianxue; Ji, Dongsheng; Wang, Yuesi

    2016-02-01

    Particulate matter (PM) pollution is a serious issue that has aroused great public attention in Beijing. To examine the seasonal characteristics of aerosols in typical pollution episodes, water-soluble inorganic ions (SO42 -, NO3-, NH4+, Cl-, K+, Na+, Ca2 + and Mg2 +) in size-segregated PM collected by an Anderson sampler (equipped with 50% effective cut-off diameters of 9.0, 5.8, 4.7, 3.3, 2.1, 1.1, 0.65, 0.43 μm and an after filter) were investigated in four intensive campaigns from June 2013 to May 2014 in the Beijing urban area. Pronounced seasonal variation of TWSIs in fine particles (aerodynamic diameter less than 2.1 μm) was observed, with the highest concentration in summer (71.5 ± 36.3 μg/m3) and the lowest in spring (28.1 ± 15.2 μg/m3). Different ion species presented different seasonal characteristics of mass concentration and size distribution, reflecting their different dominant sources. As the dominant component, SO42 -, NO3- and NH4+ (SNA) in fine particles appeared to play an important role in the formation of high PM pollution since its contribution to the TWSIs and PM2.1 mass increased significantly during pollution episodes. Due to the hygroscopic growth and enhanced secondary formation in the droplet mode (0.65-2.1 μm) from clean days to polluted days, the size distribution peak of SNA in the fine mode tended to shift from 0.43-0.65 μm to 0.65-2.1 μm. Relative humidity (RH) and temperature contributed to influence the secondary formation and regulate the size distributions of sulfates and nitrates. Partial correlation analysis found that high RH would promote the sulfur and nitrogen oxidation rates in the fine mode, while high temperature favored the sulfur oxidation rate in the condensation mode (0.43-0.65 μm) and reduced the nitrogen oxidation rate in the droplet mode (0.65-2.1 μm). The NO3-/SO42 - mass ratio in PM2.1 (73% of the samples) exceeded 1.0, suggesting that vehicle exhaust currently makes a greater contribution to aerosol

  20. Dicarboxylic acids, ω-oxocarboxylic acids, α-dicarbonyls, WSOC, OC, EC, and inorganic ions in wintertime size-segregated aerosols from central India: Sources and formation processes.

    PubMed

    Deshmukh, Dhananjay K; Kawamura, Kimitaka; Deb, Manas K

    2016-10-01

    The size distributions of aerosols can provide evidences for their sources and formation processes in the atmosphere. Size-segregated aerosols (9-sizes) were collected in urban site (Raipur: 21.2°N and 82.3°E) in central India during winter of 2012-2013. The samples were analyzed for dicarboxylic acids (C2-C12), ω-oxocarboxylic acids (ωC2-ωC9), pyruvic acid and α-dicarbonyls (C2-C3) as well as elemental carbon (EC), organic carbon (OC), water-soluble OC (WSOC) and inorganic ions. Diacids showed a predominance of oxalic acid (C2) followed by succinic and azelaic acid whereas ω-oxoacids exhibited a predominance of glyoxylic acid and glyoxal was more abundant than methylglyoxal in all the sizes. Diacids, ω-oxoacids and α-dicarbonyls showed bimodal size distribution with peaks in fine and coarse modes. High correlations of fine mode diacids and related compounds with potassium and levoglucosan suggest that they were presumably due to a substantial contribution of primary emission from biomass burning and secondary production from biomass burning derived precursors. High correlations of C2 with higher carbon number diacids (C3-C9) suggest that they have similar sources and C2 may be produced via the decay of its higher homologous diacids in fine mode. Considerable portions of diacids and related compounds in coarse mode suggest that they were associated with mineral dust particles by their adsorption and photooxidation of anthropogenic and biogenic precursors via heterogeneous reaction on dust surface. This study demonstrates that biomass burning and dust particles are two major factors to control the size distribution of diacids and related compounds in the urban aerosols from central India. PMID:27414241

  1. Design study of electron cyclotron resonance-ion plasma accelerator for heavy ion cancer therapy.

    PubMed

    Inoue, T; Hattori, T; Sugimoto, S; Sasai, K

    2014-02-01

    Electron Cyclotron Resonance-Ion Plasma Accelerator (ECR-IPAC) device, which theoretically can accelerate multiple charged ions to several hundred MeV with short acceleration length, has been proposed. The acceleration mechanism is based on the combination of two physical principles, plasma electron ion adiabatic ejection (PLEIADE) and Gyromagnetic Autoresonance (GYRAC). In this study, we have designed the proof of principle machine ECR-IPAC device and simulated the electromagnetic field distribution generating in the resonance cavity. ECR-IPAC device consisted of three parts, ECR ion source section, GYRAC section, and PLEIADE section. ECR ion source section and PLEIADE section were designed using several multi-turn solenoid coils and sextupole magnets, and GYRAC section was designed using 10 turns coil. The structure of ECR-IPAC device was the cylindrical shape, and the total length was 1024 mm and the maximum diameter was 580 mm. The magnetic field distribution, which maintains the stable acceleration of plasma, was generated on the acceleration center axis throughout three sections. In addition, the electric field for efficient acceleration of electrons was generated in the resonance cavity by supplying microwave of 2.45 GHz. PMID:24593537

  2. Design study of electron cyclotron resonance-ion plasma accelerator for heavy ion cancer therapy

    SciTech Connect

    Inoue, T. Sugimoto, S.; Sasai, K.; Hattori, T.

    2014-02-15

    Electron Cyclotron Resonance-Ion Plasma Accelerator (ECR-IPAC) device, which theoretically can accelerate multiple charged ions to several hundred MeV with short acceleration length, has been proposed. The acceleration mechanism is based on the combination of two physical principles, plasma electron ion adiabatic ejection (PLEIADE) and Gyromagnetic Autoresonance (GYRAC). In this study, we have designed the proof of principle machine ECR-IPAC device and simulated the electromagnetic field distribution generating in the resonance cavity. ECR-IPAC device consisted of three parts, ECR ion source section, GYRAC section, and PLEIADE section. ECR ion source section and PLEIADE section were designed using several multi-turn solenoid coils and sextupole magnets, and GYRAC section was designed using 10 turns coil. The structure of ECR-IPAC device was the cylindrical shape, and the total length was 1024 mm and the maximum diameter was 580 mm. The magnetic field distribution, which maintains the stable acceleration of plasma, was generated on the acceleration center axis throughout three sections. In addition, the electric field for efficient acceleration of electrons was generated in the resonance cavity by supplying microwave of 2.45 GHz.

  3. Research study of droplet sizing technology leading to the development of an advanced droplet sizing system

    NASA Technical Reports Server (NTRS)

    Hess, C. F.; Smart, A. E.; Espinosa, V. E.

    1985-01-01

    An instrument to measure the size and velocity of droplets was developed. The instrument uses one of two techniques, as appropriate. In the first technique two small laser beams of one color identify the center of a larger laser beam of a different color. This defines a region of almost uniform intensity where the light scattered by the individual droplets can be related to their size. The first technique uses the visibility of a Doppler burst and validates it against the peak intensity of the signal's pedestal. Results are presented for monodisperse, bimodal, trimodal, and polydisperse sprays produced by the Berglund-Liu droplet generator and a pressure nozzle. Size distributions of a given spray obtained using three different size ranges show excellent self-consistency in the overlapping region. Measurements of sprays of known characteristics exhibit errors in the order of 10%. The principles of operation and design criteria of the instrument are discussed in great detail.

  4. Ionization efficiency studies for xenon ions with thesuperconducting ECR ion source VENUS

    SciTech Connect

    Leitner, Daniela; Lyneis, Claude M.; Todd, DamonS.; Tarvainen,Olli

    2007-06-05

    Ionization efficiency studies for high charge state xenon ions using a calibrated gas leak are presented. A 75% enriched {sup 129}Xe gas leak with a gas flow equivalent to 5.11p{mu}A was used in all the measurements. The experiments were performed at the VENUS (Versatile ECR ion source for Nuclear Science) ion source for 18 GHz, 28 GHz and double frequency operation. Overall, total ionization efficiencies close to 100% and ionization efficiencies into a single charge state up to 22% were measured. The influence of the biased disk on the ionization efficiency was studied and the results were somewhat surprising. When the biased disk was removed from the plasma chamber, the ionization efficiency was dramatically reduced for single frequency operation. However, using double frequency heating the ionization efficiencies achieved without the biased disk almost matched the ionization efficiencies achieved with the biased probe. In addition, we have studied the influence of the support gas on the charge state distribution of the xenon ions. Either pure oxygen or a mixture of oxygen and helium were used as support gases. The addition of a small amount of helium can increase the ionization efficiency into a single charge state by narrowing the charge state distribution. Furthermore by varying the helium flow the most efficient charge state can be shifted over a wide range without compromising the ionization efficiency. This is not possible using only oxygen as support gas. Results from these studies are presented and discussed.

  5. Utilizing Neon Ion Microscope for GaSb nanopatterning studies: Nanostructure formation and comparison with low energy nanopatterning

    NASA Astrophysics Data System (ADS)

    El-Atwani, Osman; Huynh, Chuong; Norris, Scott

    2016-05-01

    Low energy irradiation of GaSb surfaces has been shown to lead to nanopillar formation. Being performed ex-situ, controlling the parameters of the ion beam for controlled nanopattern formation is challenging. While mainly utilized for imaging and cutting purposes, the development of multibeam (helium/neon) ion microscopes has opened the path towards the use of these microscopes for in-situ ion irradiation and nanopatterning studies. In this study, in-situ irradiation (neon ions)/imaging (helium ions) of GaSb surfaces is performed using Carl Zeiss-neon ion microscope at low energies (5 and 10 keV). Imaging with helium ions, nanodots were shown to form at particular fluences after which are smoothed. Ex-situ imaging with SEM showed nanopore formation of size controlled by the ion energy and fluence. Compared to lower energy ex-situ neon ion irradiation at similar fluxes, where nanopillars are formed, the results demonstrated a transition in the nanostructure type and formation mechanism as the energy is changed from 2 to 5 keV. Simulations show an increase in the ballistic diffusion and a decrease in the strength of phase separation as a function of ion energy in agreement with the suppression of nanopillar formation at higher energies. Collision cascade simulations suggest a transition toward bulk-driven mechanisms.

  6. A statistical study of ion pitch-angle distributions

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.; Mcentire, R. W.; Lui, A. T. Y.; Krimigis, S. M.

    1987-01-01

    Preliminary results of a statistical study of energetic (34-50 keV) ion pitch-angle distributions (PADs) within 9 Re of earth provide evidence for an orderly pattern consistent with both drift-shell splitting and magnetopause shadowing. Normal ion PADs dominate the dayside and inner magnetosphere. Butterfly PADs typically occur in a narrow belt stretching from dusk to dawn through midnight, where they approach within 6 Re of earth. While those ion butterfly PADs that typically occur on closed drift paths are mainly caused by drift-shell splitting, there is also evidence for magnetopause shadowing in observations of more frequent butterfly PAD occurrence in the outer magnetosphere near dawn than dusk. Isotropic and gradient boundary PADs terminate the tailward extent of the butterfly ion PAD belt.

  7. Ejection of solvated ions from electrosprayed methanol/water nanodroplets studied by molecular dynamics simulations.

    PubMed

    Ahadi, Elias; Konermann, Lars

    2011-06-22

    The ejection of solvated small ions from nanometer-sized droplets plays a central role during electrospray ionization (ESI). Molecular dynamics (MD) simulations can provide insights into the nanodroplet behavior. Earlier MD studies have largely focused on aqueous systems, whereas most practical ESI applications involve the use of organic cosolvents. We conduct simulations on mixed water/methanol droplets that carry excess NH(4)(+) ions. Methanol is found to compromise the H-bonding network, resulting in greatly increased rates of ion ejection and solvent evaporation. Considerable differences in the water and methanol escape rates cause time-dependent changes in droplet composition. Segregation occurs at low methanol concentration, such that layered droplets with a methanol-enriched periphery are formed. This phenomenon will enhance the partitioning of analyte molecules, with possible implications for their ESI efficiencies. Solvated ions are ejected from the tip of surface protrusions. Solvent bridging prior to ion secession is more extensive for methanol/water droplets than for purely aqueous systems. The ejection of solvated NH(4)(+) is visualized as diffusion-mediated escape from a metastable basin. The process involves thermally activated crossing of a ~30 kJ mol(-1) free energy barrier, in close agreement with the predictions of the classical ion evaporation model. PMID:21591733

  8. Vibrationally resolved negative ion photoelectron spectroscopic studies of niobium clusters

    SciTech Connect

    Green, S.M.E.; Alex, S.; Leopold, D.G.

    1996-12-31

    Negative ion photoelectron spectroscopy provides a means of obtaining vibrational data for atoms and small molecules {open_quotes}chemisorbed{close_quotes} on size-selected metal clusters. In the present study, Nb{sub 3}O{sup -}, Nb{sub 4}O{sup -} and Nb{sub 4}CO{sup -} were prepared in a flowing afterglow ion-molecule reactor equipped with a metal cathode cluster source. The 488 nm photoelectron spectrum of the mass-selected Nb{sub 3}O{sup -} anions shows a vertical transition to the ground state of neutral Nb{sub 3}O, with weak progressions in the Nb{sub 3}-O stretching (710{+-}20 cm{sup -1} in Nb{sub 3}O) and Nb, bending (320{+-}15 cm{sup -1}-in both Nb{sub 3}O and Nb{sub 3}O{sup -}) vibrational modes. These results indicate that the Nb{sub 3}O{sup -} anion, like Nb{sub 3}O and Nb{sub 3}O{sup +}, has a planar Ca{sub 2v} structure with the O atom bridging two Nb atoms. The Nb{sub 4}O{sup -} spectrum shows resolved transitions to the ground state of Nb{sub 3}O and to an excited electronic state lying 3050{+-}20 cm{sup -1} higher in energy. In analogy with the Nb{sub 4}O results, the 670{+-}20 cm{sup -1} frequency observed for the Nb{sub 4}O ground state is assigned to a metal-oxygen stretching mode, and the 215{+-}15 cm{sup -1} and 195{+-}15 cm{sup -1} frequencies observed in the ground and excited states, respectively, to a bending mode of the metal cluster. The electron affinities of Nb{sub 3}O and Nb{sub 4}O are 1.402 and 1.178 ({+-}0.006) eV, respectively. Preliminary, ongoing studies of mass selected Nb{sub 4}CO{sup -} anions prepared under a variety of source conditions thus far suggest the presence of two isomers, one with a greatly weakened but intact CO bond as indicated by a very low CO stretching frequency of about 1300 cm{sup -1} and the other with the dissociated C and O atoms bound separately to the niobium cluster.

  9. Beam Energy and System-size Dependence of the Space-time Extent of the Pion Emission Source Produced in Heavy-Ion Collisions

    NASA Astrophysics Data System (ADS)

    Mwai, Alex

    The primary goal of high-energy nuclear physics is to develop a thorough understanding of the QCD phase diagram: Its different phases, their boundaries, and the physics they define. Heavy-ion collisions reproduce at a microscale the conditions necessary to initiate the phase transitions of nuclear matter that are only possible at extreme temperatures (T) and baryon chemical potential (mu_{B}). An important probe utilized in studies of the hot and dense matter created in heavy-ion collisions is the method of Hanbury-Brown and Twiss interferometry. The technique is useful in providing measurements in space and time of the pion emission sources at freeze-out. One enduring question of interest in studies of the QCD phase diagram is the position in T and mu_{B} coordinates of the QCD Critical End Point (CEP) as well as the onset of deconfinement, as predicted by model calculations. According to these models, the Equation of State (EoS) should soften in the vicinity of the CEP and/or a first order phase transition. The expanding hot and dense system is sensitive to changes in the EoS. A softening of the EoS will therefore be reflected in measurements of the final size in space-time of the pion emission source. Another question is how small can a system be before we see a turn-off of hydrodynamically driven final-state effects. In this thesis, detailed HBT measurements obtained using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC) are presented for three beam collision energies (sqrt{s_{NN}}. = 39, 62, and 200 GeV) and three collision species (d+Au, Cu+Cu, and Au+Au). The measurements are studied for their dependence on collision geometry and transverse mass (m_{T}), and observations are made on how the small asymmetric system, d+Au, compares to the A+A systems for these dependencies. In addition, newly observed universal scaling patterns with the initial transverse size, bar{R}, and 1/sqrt{m_{T}} for both RHIC HBT measurements and the Pb+Pb collision

  10. Electrochemical properties of large-sized pouch-type lithium ion batteries with bio-inspired organic cathode materials

    NASA Astrophysics Data System (ADS)

    Yeo, Jae-Seong; Yoo, Eun-Ji; Ha, Sang-Hyeon; Cheong, Dong-Ik; Cho, Sung-Baek

    2016-05-01

    To investigate the feasibility of scaling up bio-inspired organic materials as cathode materials in lithium ion batteries, large-sized pouch cells are successfully prepared via tape casting using lumichrome with an alloxazine structure and aqueous styrene butadiene rubber-carboxymethyl cellulose (SBR-CMC) binders. A battery module with a two-in-series, six-in-parallel (2S6P) configuration is also successfully fabricated and is able to power blue LEDs (850 mW). Lumichrome shows no structural changes during the fabrication processes used to produce the positive electrode. The large-sized pouch cells show two sets of cathodic and anodic peaks with average potentials of 2.58 V and 2.26 V vs. Li/Li+, respectively. The initial discharge capacities are 142 mAh g-1 and 148 mAh g-1 for ethylene carbonate-dimethyl carbonate (EC-DMC) and tetraethylene glycol dimethyl ether (TEGDME) electrolytes, respectively, similar to that of a coin cell (149 mAh g-1). The EC-DMC-injected pouch cells exhibit higher rate performance and cyclability than the TEGDME-injected ones. The TEGDME electrolyte is not suitable for lithium metal anodes because of electrolyte decomposition and subsequent cell swelling.

  11. Evaluation of particle size distributions produced during ultra-violet nanosecond laser ablation and their relative contributions to ion densities in the inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Moses, Lance M.; Farnsworth, Paul B.

    2015-11-01

    Relative contributions to ion densities in the inductively coupled plasma (ICP) of particles of various sizes produced by laser ablation (LA) were investigated. Particles generated by 266 nm, ns LA of BaF2, CaF2, and a scandium aluminum alloy, characterized using SEM, consisted of hard and soft agglomerates, spherical particles, and irregularly-shaped particles. Although soft agglomerates and spherical particles were common to aerosols generated by LA in all cases, hard agglomerates appeared to be unique to the scandium aluminum alloy, while irregularly-shaped exfoliated particles were unique to the calcium and barium fluoride windows. The spatial distributions of Ca, Ba, and Sc ions in the ICP were determined from laser-induced fluorescence images taken with filters of pore sizes from 1-8 μm added in-line to the transport tube upstream from the ICP. In all cases, a significant fraction of the ions formed in the ICP originated from micron-sized particles. Differences in the penetration depths of nanometer-sized agglomerates and micron-sized particles were about 2 mm for Ca and 1 mm for Ba. Differences in the penetration depths of nanometer and micron-sized agglomerates observed in the case of aluminum scandium were much less significant. This suggests that micron-sized hard-agglomerates and nanometer-sized soft-agglomerates experience very similar vaporization patterns. Additionally, there was evidence that flow patterns in the transport tube affect the trajectories of particles entering the plasma.

  12. RISR Observations of High Ion Temperatures: A Case Study

    NASA Astrophysics Data System (ADS)

    Akbari, H.; Semeter, J. L.

    2015-12-01

    Incoherent scatter radars (ISRs) measure the frequency spectrum of the scattered signal from random thermal fluctuations in the ionospheric plasma. Once fitted to a theoretical model, the shape of the spectrum provides estimates to a number of plasma parameters including the ion temperature. The theoretical models of the frequency spectrum of the scattered signal have been often developed based on a set of assumptions on the state of the plasma. One of the most common assumptions is that the plasma is in thermal equilibrium consisting of electron and ion populations that can be described by Maxwellian distributions. Such an assumption, however, is commonly violated at high latitudes where the interactions between the ionosphere and the magnetosphere result in a very dynamic plasma environment. One example of such violations occurs on the edge of auroral arcs when the presence of strong electric fields (<100 mV/m) may cause the ion velocity distribution to deviate from Maxwellian. In such cases, the assumption of thermal equilibrium in the standard ISR fitting procedure results in significant errors in derivation of the plasma parameters. In this study we investigate an event in which the ion temperature measured by the Resolute Bay incoherent scatter radar (RISR) reaches to values as high as 8000 (K). Based on RISR measurements of the electric fields we calculate the expected Joule heating and investigate the possible role of ISR misfitting (caused by deviation of the ion distribution from Maxwellian) in over estimating the ion temperature.

  13. Kr ion irradiation study of the depleted-uranium alloys

    NASA Astrophysics Data System (ADS)

    Gan, J.; Keiser, D. D.; Miller, B. D.; Kirk, M. A.; Rest, J.; Allen, T. R.; Wachs, D. M.

    2010-12-01

    Fuel development for the reduced enrichment research and test reactor (RERTR) program is tasked with the development of new low enrichment uranium nuclear fuels that can be employed to replace existing high enrichment uranium fuels currently used in some research reactors throughout the world. For dispersion type fuels, radiation stability of the fuel-cladding interaction product has a strong impact on fuel performance. Three depleted-uranium alloys are cast for the radiation stability studies of the fuel-cladding interaction product using Kr ion irradiation to investigate radiation damage from fission products. SEM analysis indicates the presence of the phases of interest: U(Al, Si) 3, (U, Mo)(Al, Si) 3, UMo 2Al 20, U 6Mo 4Al 43 and UAl 4. Irradiations of TEM disc samples were conducted with 500 keV Kr ions at 200 °C to ion doses up to 2.5 × 10 19 ions/m 2 (˜10 dpa) with an Kr ion flux of 10 16 ions/m 2/s (˜4.0 × 10 -3 dpa/s). Microstructural evolution of the phases relevant to fuel-cladding interaction products was investigated using transmission electron microscopy.

  14. Experimental study of ion heating and acceleration during magnetic reconnection

    SciTech Connect

    Hsu, S.C.

    2000-01-28

    This dissertation reports an experimental study of ion heating and acceleration during magnetic reconnection, which is the annihilation and topological rearrangement of magnetic flux in a conductive plasma. Reconnection is invoked often to explain particle heating and acceleration in both laboratory and naturally occurring plasmas. However, a simultaneous account of reconnection and its associated energy conversion has been elusive due to the extreme inaccessibility of reconnection events, e.g. in the solar corona, the Earth's magnetosphere, or in fusion research plasmas. Experiments for this work were conducted on MRX (Magnetic Reconnection Experiment), which creates a plasma environment allowing the reconnection process to be isolated, reproduced, and diagnosed in detail. Key findings of this work are the identification of local ion heating during magnetic reconnection and the determination that non-classical effects must provide the heating mechanism. Measured ion flows are sub-Alfvenic and can provide only slight viscous heating, and classical ion-electron interactions can be neglected due to the very long energy equipartition time. The plasma resistivity in the reconnection layer is seen to be enhanced over the classical value, and the ion heating is observed to scale with the enhancement factor, suggesting a relationship between the magnetic energy dissipation mechanism and the ion heating mechanism. The observation of non-classical ion heating during reconnection has significant implications for understanding the role played by non-classical dissipation mechanisms in generating fast reconnection. The findings are relevant for many areas of space and laboratory plasma research, a prime example being the currently unsolved problem of solar coronal heating. In the process of performing this work, local measurements of ion temperature and flows in a well-characterized reconnection layer were obtained for the first time in either laboratory or observational

  15. Experimental study of transition metal ion doping on TiO2 with photocatalytic behavior.

    PubMed

    Siddhapara, K S; Shah, D V

    2014-08-01

    In this research, we have studied the doping behaviors of three transition metal ion dopants on the crystal phase, particle sizes, XRD patterns, EDAX spectra, and photoreactivity of TiO2 nanoparticles. Test metal ion concentrations ranged from 1% to 4 at.%, we report the growth of [Fe, Co and Mn]xTiO2 nanocrystals prepared by Sol-Gel technique, followed by freeze-drying treatment at -30 °C temperature for 12 hrs. The obtained Gel was thermally treated at different temperature like 200 °C, 400 °C, 600 °C, 800 °C. Thermal gravimetric analysis (TGA) shows that dopant concentration affects thermal decomposition. The photoreactivities of transition metal ion-doped TiO2 nanoparticles under UV irradiation were quantified by the degradation of formaldehyde.

  16. Ion balances of size-resolved tropospheric aerosol samples: implications for the acidity and atmospheric processing of aerosols

    NASA Astrophysics Data System (ADS)

    Kerminen, Veli-Matti; Hillamo, Risto; Teinilä, Kimmo; Pakkanen, Tuomo; Allegrini, Ivo; Sparapani, Roberto

    A large set of size-resolved aerosol samples was inspected with regard to their ion balance to shed light on how the aerosol acidity changes with particle size in the lower troposphere and what implications this might have for the atmospheric processing of aerosols. Quite different behaviour between the remote and more polluted environments could be observed. At the remote sites, practically the whole accumulation mode had cation-to-anion ratios clearly below unity, indicating that these particles were quite acidic. The supermicron size range was considerably less acidic and may in some cases have been close to neutral or even alkaline. An interesting feature common to the remote sites was a clear jump in the cation-to-anion ratio when going from the accumulation to the Aitken mode. The most likely reason for this was cloud processing which, via in-cloud sulphate production, makes the smallest accumulation-mode particles more acidic than the non-activated Aitken-mode particles. A direct consequence of the less acidic nature of the Aitken mode is that it can take up semi-volatile, water-soluble gases much easier than the accumulation mode. This feature may have significant implications for atmospheric cloud condensation nuclei production in remote environments. In rural and urban locations, the cation-to-anion ratio was close to unity over most of the accumulation mode, but increased significantly when going to either larger or smaller particle sizes. The high cation-to-anion ratios in the supermicron size range were ascribed to carbonate associated with mineral dust. The ubiquitous presence of carbonate in these particles indicates that they were neutral or alkaline, making them good sites for heterogeneous reactions involving acidic trace gases. The high cation-to-anion ratios in the Aitken mode suggest that these particles contained some water-soluble anions not detected by our chemical analysis. This is worth keeping in mind when investigating the hygroscopic

  17. A study of SS size distribution during runoff and fractionation of phosphates depending on soil size in agricultural watershed.

    PubMed

    Sa, S H; Masuda, T; Hosoi, Y

    2005-01-01

    Characterization of the differences and algal-available fractions of P in soils, suspended solids, and bottom sediments have been the main topics of research during the past decade. However, the size distribution and properties of particulate matter in runoff have not been much studied in Japan. Here we study particle size distribution during runoff and the chemical characteristics of P in each soil size fraction and relate them to land use. The temporal variation of particulate sizes during rain events is different in each watershed. Most particles have the size in the range of 10-100 microm. Also, the percentage of BAP in TP as well as percentage of PCOD in SS also varies temporally and spatially during runoff. To investigate how soil particles characteristics depend on land use, soil samples from two watersheds are examined. For particle size distribution and specific gravity, no significant difference among watersheds is found. However, C, N, and P content are indirectly proportional to the particle size, which means smaller particle size results in larger. H2O-extracted P, NH4Cl-extracted P, NAI-P, Apatite-P, Organic-P, and TP contents in each soil particle sample vary depending on particle size, land use, and watershed.

  18. Class-Size Policy: The STAR Experiment and Related Class-Size Studies. NCPEA Policy Brief. Volume 1, Number 2

    ERIC Educational Resources Information Center

    Achilles, Charles M.

    2012-01-01

    This brief summarizes findings on class size from over 25 years of work on the Tennessee Student Teacher Achievement Ratio (STAR) randomized, longitudinal experiment, and other Class-Size Reduction (CSR) studies throughout the United States, Australia, Hong Kong, Sweden, Great Britain, and elsewhere. The brief concludes with recommendations. The…

  19. Computer Simulation Studies of Ion Channels at High Temperatures

    NASA Astrophysics Data System (ADS)

    Song, Hyun Deok

    The gramicidin channel is the smallest known biological ion channel, and it exhibits cation selectivity. Recently, Dr. John Cuppoletti's group at the University of Cincinnati showed that the gramicidin channel can function at high temperatures (360 ˜ 380K) with significant currents. This finding may have significant implications for fuel cell technology. In this thesis, we have examined the gramicidin channel at 300K, 330K, and 360K by computer simulation. We have investigated how the temperature affects the current and differences in magnitude of free energy between the two gramicidin forms, the helical dimer (HD) and the double helix (DH). A slight decrease of the free energy barrier inside the gramicidin channel and increased diffusion at high temperatures result in an increase of current. An applied external field of 0.2V/nm along the membrane normal results in directly observable ion transport across the channels at high temperatures for both HD and DH forms. We found that higher temperatures also affect the probability distribution of hydrogen bonds, the bending angle, the distance between dimers, and the size of the pore radius for the helical dimer structure. These findings may be related to the gating of the gramicidin channel. Methanococcus jannaschii (MJ) is a methane-producing thermophile, which was discovered at a depth of 2600m in a Pacific Ocean vent in 1983. It has the ability to thrive at high temperatures and high pressures, which are unfavorable for most life forms. There have been some experiments to study its stability under extreme conditions, but still the origin of the stability of MJ is not exactly known. MJ0305 is the chloride channel protein from the thermophile MJ. After generating a structure of MJ0305 by homology modeling based on the Ecoli ClC templates, we examined the thermal stability, and the network stability from the change of network entropy calculated from the adjacency matrices of the protein. High temperatures increase the

  20. Novel computational approach for studying ph effects, excluded volume and ion-ion correlations in electrical double layers around polyelectrolytes and nanoparticles

    NASA Astrophysics Data System (ADS)

    Ovanesyan, Zaven

    , which are important details for proper description of EDL properties. In this thesis, we implement an efficient and accurate classical solvation density functional theory (CDSFT) for EDLs of spherical macroions and cylindrical polyelectrolytes embedded in aqueous electrolytes. This approach extends the capabilities of mean field approximations by taking into account electrostatic ion-ion correlations, size asymmetry and excluded volume effects without compromising the computational cost. We apply the computational tool to study the structural and thermodynamic properties of the ionic atmosphere around B-DNA and spherical nanoparticles. We demonstrate that the presence of solvent molecules at experimental concentration and size values has a significant impact on the layering of ions. This layering directly influences the integrated charge and mean electrostatic potential in the diffuse region of the spherical electrical double layer (SEDL) and have a noticeable impact on the behavior of zeta potential (ZP). Recently, we have extended the aforementioned CSDFT to account for the charge-regulated mechanisms of the macroion surface on the structural and thermodynamic properties of spherical EDLs. In the approach, the CSDFT is combined with a surface complexation model to account for ion correlation and excluded volume effects on the surface titration of spherical macroions. We apply the proposed computational approach to describe the role that the ion size and solvent excluded volume play on the surface titration properties of silica nanoparticles. We analyze the effects of the nanoparticle size, pH and salt concentration of the aqueous solution on the nanoparticle's surface charge and zeta potential. The results reveal that surface charge density and zeta potential significantly depend on excluded volume and ion-ion correlation effects as well as on pH for monovalent ion species at high salt concentrations. Overall, our results are in good agreement with Monte Carlo

  1. Effect of particle size of drinking-water treatment residuals on the sorption of arsenic in the presence of competing ions.

    PubMed

    Caporale, Antonio G; Punamiya, Pravin; Pigna, Massimo; Violante, Antonio; Sarkar, Dibyendu

    2013-09-15

    Arsenite [As(III)] and arsenate [As(V)] sorption by Fe- and Al-based drinking-water treatment residuals (WTR) was studied as a function of particle size at different pHs, and in the presence of competing ligands, namely, phosphate, citrate, and oxalate. Both WTRs showed high affinity for As oxyanions. However, Al-WTR showed higher As(III) and As(V) sorption capacity than Fe-WTR because of their greater surface area. The effect of particle size on As sorption was pronounced on Fe-WTR, where the smaller fraction sorbed more As(III) and As(V) than the larger fractions, whereas relatively minor effects of particle size on As sorption was observed for Al-WTR. Arsenite sorption on both WTRs increased with increasing pH up to circum-neutral pHs and then decreased at higher pHs, whereas As(V) sorption decreased steadily with increasing pH. The capacity of competing ligands to inhibit sorption was greater for As(III) than As(V) on both WTRs (particularly on Al-WTR) following the sequence: oxalateion residence time on the WTR surfaces: the longer the residence time, the less effective were the competing ligands in As desorption.

  2. Ion mobility studies of electronically excited States of atomic transition metal cations: development of an ion mobility source for guided ion beam experiments.

    PubMed

    Iceman, Christopher; Rue, Chad; Moision, Robert M; Chatterjee, Barun K; Armentrout, P B

    2007-07-01

    The design of an ion mobility source developed to couple to a guided ion beam tandem mass spectrometer is presented. In these exploratory studies, metal ions are created continuously by electron ionization of the volatile hexacarbonyls of the three group 6 transition metals. These ions are focused into a linear hexapole ion trap, which collects the ions and then creates high intensity pulses of ions, avoiding excessive ion losses resulting from the low duty cycle of pulsed operation. The ion pulses are injected into a six-ring drift cell filled with helium where ions having different electronic configurations can separate because they have different ion mobilities. Such separation is observed for chromium ions and compares favorably with the pioneering work of Kemper and Bowers (J. Phys. Chem.1991, 95, 5134). The results are then extended to Mo(+) and W(+), which also show efficient configuration separation. The source conditions needed for high intensities and good configuration separation are discussed in detail and suggestions for further improvements are also provided.

  3. Synthesis of hematite (alpha-Fe2O3) nanorods: diameter-size and shape effects on their applications in magnetism, lithium ion battery, and gas sensors.

    PubMed

    Wu, Changzheng; Yin, Ping; Zhu, Xi; OuYang, Chuanzi; Xie, Yi

    2006-09-14

    surface area or diameter size of hematite nanorods can also influence the lithium intercalation performances. These results give us a guideline for the study of the size-dependent properties for functional materials as well as further applications for magnetic materials, lithium-ion batteries, and gas sensors. PMID:16956266

  4. Enhancing ion yields in time-of-flight-secondary ion mass spectrometry: a comparative study of argon and water cluster primary beams.

    PubMed

    Sheraz née Rabbani, Sadia; Razo, Irma Berrueta; Kohn, Taylor; Lockyer, Nicholas P; Vickerman, John C

    2015-02-17

    Following from our previous Letter on this topic, this Article reports a detailed study of time-of-flight-secondary ion mass spectrometry (TOF-SIMS) positive ion spectra generated from a set of model biocompounds (arginine, trehalose, DPPC, and angiotensin II) by water cluster primary ion beams in comparison to argon cluster beams over a range of cluster sizes and energies. Sputter yield studies using argon and water beams on arginine and Irganox 1010 have confirmed that the sputter yields using water cluster beams lie on the same universal sputtering curve derived by Seah for argon cluster beams. Thus, increased ion yield using water cluster beams must arise from increased ionization. The spectra and positive ion signals observed using cluster beams in the size range from 1,000 to 10,000 and the energy range 5-20 keV are reported. It is confirmed that water cluster beams enhance proton related ionization over against argon beams to a significant degree such that enhanced detection sensitivities from 1 μm(2) in the region of 100 to 1,000 times relative to static SIMS analysis with Ar2000 cluster beams appear to be accessible. These new studies show that there is an unexpected complexity in the ionization enhancement phenomenon. Whereas optimum ion yields under argon cluster bombardment occur in the region of E/n ≥ 10 eV (where E is the beam energy and n the number of argon atoms in the cluster) and fall rapidly when E/n < 10 eV; for water cluster beams, ion yields increase significantly in this E/n regime (where n is the number of water molecules in the cluster) and peak for 20 keV beams at a cluster size of 7,000 or E/n ∼3 eV. This important result is explored further using D2O cluster beams that confirm that in this low E/n regime protonation does originate to a large extent from the water molecules. The results, encouraging in themselves, suggest that for both argon and water cluster beams, higher energy beams, e.g., 40 and 80 keV, would enable larger

  5. Enhancing ion yields in time-of-flight-secondary ion mass spectrometry: a comparative study of argon and water cluster primary beams.

    PubMed

    Sheraz née Rabbani, Sadia; Razo, Irma Berrueta; Kohn, Taylor; Lockyer, Nicholas P; Vickerman, John C

    2015-02-17

    Following from our previous Letter on this topic, this Article reports a detailed study of time-of-flight-secondary ion mass spectrometry (TOF-SIMS) positive ion spectra generated from a set of model biocompounds (arginine, trehalose, DPPC, and angiotensin II) by water cluster primary ion beams in comparison to argon cluster beams over a range of cluster sizes and energies. Sputter yield studies using argon and water beams on arginine and Irganox 1010 have confirmed that the sputter yields using water cluster beams lie on the same universal sputtering curve derived by Seah for argon cluster beams. Thus, increased ion yield using water cluster beams must arise from increased ionization. The spectra and positive ion signals observed using cluster beams in the size range from 1,000 to 10,000 and the energy range 5-20 keV are reported. It is confirmed that water cluster beams enhance proton related ionization over against argon beams to a significant degree such that enhanced detection sensitivities from 1 μm(2) in the region of 100 to 1,000 times relative to static SIMS analysis with Ar2000 cluster beams appear to be accessible. These new studies show that there is an unexpected complexity in the ionization enhancement phenomenon. Whereas optimum ion yields under argon cluster bombardment occur in the region of E/n ≥ 10 eV (where E is the beam energy and n the number of argon atoms in the cluster) and fall rapidly when E/n < 10 eV; for water cluster beams, ion yields increase significantly in this E/n regime (where n is the number of water molecules in the cluster) and peak for 20 keV beams at a cluster size of 7,000 or E/n ∼3 eV. This important result is explored further using D2O cluster beams that confirm that in this low E/n regime protonation does originate to a large extent from the water molecules. The results, encouraging in themselves, suggest that for both argon and water cluster beams, higher energy beams, e.g., 40 and 80 keV, would enable larger

  6. Atomic size effects studied by transport in single silicide nanowires

    NASA Astrophysics Data System (ADS)

    Miccoli, I.; Edler, F.; Pfnür, H.; Appelfeller, S.; Dähne, M.; Holtgrewe, K.; Sanna, S.; Schmidt, W. G.; Tegenkamp, C.

    2016-03-01

    Ultrathin metallic silicide nanowires with extremely high aspect ratios can be easily grown, e.g., by deposition of rare earth elements on semiconducting surfaces. These wires play a pivotal role in fundamental research and open intriguing perspectives for CMOS applications. However, the electronic properties of these one-dimensional systems are extremely sensitive to atomic-sized defects, which easily alter the transport characteristics. In this study, we characterized comprehensively TbSi2 wires grown on Si(100) and correlated details of the atomic structure with their electrical resistivities. Scanning tunneling microscopy (STM) as well as all transport experiments were performed in situ using a four-tip STM system. The measurements are complemented by local spectroscopy and density functional theory revealing that the silicide wires are electronically decoupled from the Si template. On the basis of a quasiclassical transport model, the size effect found for the resistivity is quantitatively explained in terms of bulk and surface transport channels considering details of atomic-scale roughness. Regarding future applications the full wealth of these robust nanostructures will emerge only if wires with truly atomically sharp interfaces can be reliably grown.

  7. Novel computational approach for studying ph effects, excluded volume and ion-ion correlations in electrical double layers around polyelectrolytes and nanoparticles

    NASA Astrophysics Data System (ADS)

    Ovanesyan, Zaven

    , which are important details for proper description of EDL properties. In this thesis, we implement an efficient and accurate classical solvation density functional theory (CDSFT) for EDLs of spherical macroions and cylindrical polyelectrolytes embedded in aqueous electrolytes. This approach extends the capabilities of mean field approximations by taking into account electrostatic ion-ion correlations, size asymmetry and excluded volume effects without compromising the computational cost. We apply the computational tool to study the structural and thermodynamic properties of the ionic atmosphere around B-DNA and spherical nanoparticles. We demonstrate that the presence of solvent molecules at experimental concentration and size values has a significant impact on the layering of ions. This layering directly influences the integrated charge and mean electrostatic potential in the diffuse region of the spherical electrical double layer (SEDL) and have a noticeable impact on the behavior of zeta potential (ZP). Recently, we have extended the aforementioned CSDFT to account for the charge-regulated mechanisms of the macroion surface on the structural and thermodynamic properties of spherical EDLs. In the approach, the CSDFT is combined with a surface complexation model to account for ion correlation and excluded volume effects on the surface titration of spherical macroions. We apply the proposed computational approach to describe the role that the ion size and solvent excluded volume play on the surface titration properties of silica nanoparticles. We analyze the effects of the nanoparticle size, pH and salt concentration of the aqueous solution on the nanoparticle's surface charge and zeta potential. The results reveal that surface charge density and zeta potential significantly depend on excluded volume and ion-ion correlation effects as well as on pH for monovalent ion species at high salt concentrations. Overall, our results are in good agreement with Monte Carlo

  8. Study of ion-irradiated tungsten in deuterium plasma

    NASA Astrophysics Data System (ADS)

    Khripunov, B. I.; Gureev, V. M.; Koidan, V. S.; Kornienko, S. N.; Latushkin, S. T.; Petrov, V. B.; Ryazanov, A. I.; Semenov, E. V.; Stolyarova, V. G.; Danelyan, L. S.; Kulikauskas, V. S.; Zatekin, V. V.; Unezhev, V. N.

    2013-07-01

    Experimental study aimed at investigation of neutron induced damage influence on fusion reactor plasma facing materials is reported. Displacement damage was produced in tungsten by high-energy helium and carbon ions at 3-10 MeV. The reached level of displacement damage ranged from several dpa to 600 dpa. The properties of the irradiated tungsten were studied in steady-state deuterium plasma on the LENTA linear divertor simulator. Plasma exposures were made at 250 eV of ion energy to fluence 1021-1022 ion/сm2. Erosion dynamics of the damaged layer and deuterium retention were observed. Surface microstructure modifications and important damage of the 5 μm layer shown. Deuterium retention in helium-damaged tungsten (ERD) showed its complex behavior (increase or decrease) depending on implanted helium quantity and the structure of the surface layer.

  9. [Spectroscopic studies on transition metal ions in colored diamonds].

    PubMed

    Meng, Yu-Fei; Peng, Ming-Sheng

    2004-07-01

    Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples.

  10. [Spectroscopic studies on transition metal ions in colored diamonds].

    PubMed

    Meng, Yu-Fei; Peng, Ming-Sheng

    2004-07-01

    Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples. PMID:15766067

  11. Analyzing insulin samples by size-exclusion chromatography: a column degradation study.

    PubMed

    Teska, Brandon M; Kumar, Amit; Carpenter, John F; Wempe, Michael F

    2015-04-01

    Investigating insulin analogs and probing their intrinsic stability at physiological temperature, we observed significant degradation in the size-exclusion chromatography (SEC) signal over a moderate number of insulin sample injections, which generated concerns about the quality of the separations. Therefore, our research goal was to identify the cause(s) for the observed signal degradation and attempt to mitigate the degradation in order to extend SEC column lifespan. In these studies, we used multiangle light scattering, nuclear magnetic resonance, and gas chromatography-mass spectrometry methods to evaluate column degradation. The results from these studies illustrate: (1) that zinc ions introduced by the insulin product produced the observed column performance issues; and (2) that including ethylenediaminetetraacetic acid, a zinc chelator, in the mobile phase helped to maintain column performance.

  12. Shift reagents in ion mobility spectrometry: the effect of the number of interaction sites, size and interaction energies on the mobilities of valinol and ethanolamine.

    PubMed

    Fernández-Maestre, Roberto; Meza-Morelos, Dairo; Wu, Ching

    2016-05-01

    Overlapping peaks interfere in ion mobility spectrometry (IMS), but they are separated introducing mobility shift reagents (SR) in the buffer gas forming adducts with different collision cross-sections (size). IMS separations using SR depend on the ion mobility shifts which are governed by adduct's size and interaction energies (stabilities). Mobility shifts of valinol and ethanolamine ions were measured by electrospray-ionization ion mobility-mass spectrometry (MS). Methyl-chloro propionate (M) was used as SR; 2-butanol (B) and nitrobenzene (N) were used for comparison. Density functional theory was used for calculations. B produced the smallest mobility shifts because of its small size. M and N have two strong interaction sites (oxygen atoms) and similar molecular mass, and they should produce similar shifts. For both ethanolamine and valinol ions, stabilities were larger for N adducts than those of M. With ethanolamine, M produced a 68% shift, large compared to that using N, 61%, because M has a third weak interaction site on the chlorine atom and, therefore, M has more interaction possibilities than N. This third site overrode the oxygen atoms' interaction energy that favored the adduction of ethanolamine with N over that with M. On the contrary, with valinol mobility shifts were larger with N than with M (21 vs 18%) because interaction energy favored even more adduction of valinol with N than with M; that is, the interaction energy difference between adducts of valinol with M and N was larger than that between those adducts with ethanolamine, and the third M interaction could not override this larger difference. Mobility shifts were explained based on the number of SR's interaction sites, size of ions and SR, and SR-ion interaction energies. This is the first time that the number of interaction sites is used to explain mobility shifts in SR-assisted IMS. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Empirical study of the tails of mutual fund size

    NASA Astrophysics Data System (ADS)

    Schwarzkopf, Yonathan; Farmer, J. Doyne

    2010-06-01

    The mutual fund industry manages about a quarter of the assets in the U.S. stock market and thus plays an important role in the U.S. economy. The question of how much control is concentrated in the hands of the largest players is best quantitatively discussed in terms of the tail behavior of the mutual fund size distribution. We study the distribution empirically and show that the tail is much better described by a log-normal than a power law, indicating less concentration than, for example, personal income. The results are highly statistically significant and are consistent across fifteen years. This contradicts a recent theory concerning the origin of the power law tails of the trading volume distribution. Based on the analysis in a companion paper, the log-normality is to be expected, and indicates that the distribution of mutual funds remains perpetually out of equilibrium.

  14. Grain size dependent magneto-dielectric studies on Lu3Fe5O12

    NASA Astrophysics Data System (ADS)

    Ashok Kumar, K.; Manimuthu, P.; Ezhilarasi, V. S.; Venkateswaran, C.

    2014-09-01

    Polycrystalline Lu3Fe5O12 ceramics (LFO) with garnet structure were prepared by solid-state reaction method and a part of the sample was ball milled for 15 h (LFO15h) using a high energy ball mill to study the grain size effect. The cubic garnet phase was confirmed for both LFO and LFO15h samples by X-ray diffraction analysis. The magnetic behavior was studied using a Vibrating Sample Magnetometer and it shows a clear hysteresis loop with ferrimagnetic ordering at room temperature for both LFO and LFO15h samples. X-ray photoelectron spectra reveal the presence of single valence state of Fe ions (Fe3+) in the unmilled sample and mixed valence state of Fe ions (i.e., Fe2+ and Fe3+) in the 15 h ball milled sample. Magneto-dielectric (MD) studies that have been carried out using an indigenous magneto-impedance setup show large MD coupling at room temperature for the LFO15 h in comparison to the LFO sample, making it a candidate explorable for applications in magneto dielectric devices.

  15. Design and synthesis of micron-sized spherical aggregates composed of hollow Fe2O3 nanospheres for use in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Cho, Jung Sang; Hong, Young Jun; Lee, Jong-Heun; Kang, Yun Chan

    2015-04-01

    A novel structure denoted a ``hollow nanosphere aggregate'' is synthesized by introducing nanoscale Kirkendall diffusion to the spray pyrolysis process. The hollow Fe2O3 nanosphere aggregates with spherical shape and micron size are synthesized as the first target material. A solid iron oxide-carbon composite powder that is prepared by a one-pot spray pyrolysis process is transformed into the hollow Fe2O3 nanosphere aggregates by sequential post-pyrolysis treatments under reducing and oxidizing atmospheres. The nanoscale Kirkendall diffusion plays a key role in the formation of the hollow Fe2O3 nanosphere aggregates with spherical shape and micron size. The unique structure of the hollow Fe2O3 nanosphere aggregates results in their superior electrochemical properties as an anode material for lithium ion batteries by improving the structural stability during cycling. The hollow metal oxide nanosphere aggregates with various compositions for wide applications including energy storage can be prepared by the simple fabrication method introduced in this study.A novel structure denoted a ``hollow nanosphere aggregate'' is synthesized by introducing nanoscale Kirkendall diffusion to the spray pyrolysis process. The hollow Fe2O3 nanosphere aggregates with spherical shape and micron size are synthesized as the first target material. A solid iron oxide-carbon composite powder that is prepared by a one-pot spray pyrolysis process is transformed into the hollow Fe2O3 nanosphere aggregates by sequential post-pyrolysis treatments under reducing and oxidizing atmospheres. The nanoscale Kirkendall diffusion plays a key role in the formation of the hollow Fe2O3 nanosphere aggregates with spherical shape and micron size. The unique structure of the hollow Fe2O3 nanosphere aggregates results in their superior electrochemical properties as an anode material for lithium ion batteries by improving the structural stability during cycling. The hollow metal oxide nanosphere aggregates with

  16. Characterization and properties of micro- and nanowires of controlled size, composition, and geometry fabricated by electrodeposition and ion-track technology

    PubMed Central

    2012-01-01

    Summary The combination of electrodeposition and polymeric templates created by heavy-ion irradiation followed by chemical track etching provides a large variety of poly- and single-crystalline nanowires of controlled size, geometry, composition, and surface morphology. Recent results obtained by our group on the fabrication, characterization and size-dependent properties of nanowires synthesized by this technique are reviewed, including investigations on electrical resistivity, surface plasmon resonances, and thermal instability. PMID:23365800

  17. Synthesis of nano-sized silicon from natural halloysite clay and its high performance as anode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhou, Xiangyang; Wu, Lili; Yang, Juan; Tang, Jingjing; Xi, Lihua; Wang, Biao

    2016-08-01

    Recently, nanostructured Si has been intensively studied as a promising anode candidate for lithium ion batteries due to its ultrahigh capacity. However, the downsizing of Si to nanoscale dimension is often impeded by complicated and expensive methods. In this work, natural halloysite clay was utilized for the production of Si nanoparticles through selective acid etching and modified magnesiothermic reduction processes. The physical and chemical changes of these samples during the various processes have been analyzed. The as-prepared Hsbnd Si from halloysite clay is composed of many interconnected Si nanoparticles with an average diameter of 20-50 nm. Owing to the small size and porous nature, the Hsbnd Si nanoparticles exhibit a satisfactory performance as an anode for lithium ion batteries. Without further modification, a stable capacity over 2200 mAh g-1 at a rate of 0.2 C after 100 cycles and a reversible capacity above 800 mAh g-1 at a rate of 1 C after 1000 cycles can be obtained. As a result, this synthetic route is cost-effective and can be scaled up for mass production of Si nanoparticles, which may facilitate valuable utilization of halloysite clay and further commercial application of Si-based anode materials.

  18. Synthesis of nano-sized silicon from natural halloysite clay and its high performance as anode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhou, Xiangyang; Wu, Lili; Yang, Juan; Tang, Jingjing; Xi, Lihua; Wang, Biao

    2016-08-01

    Recently, nanostructured Si has been intensively studied as a promising anode candidate for lithium ion batteries due to its ultrahigh capacity. However, the downsizing of Si to nanoscale dimension is often impeded by complicated and expensive methods. In this work, natural halloysite clay was utilized for the production of Si nanoparticles through selective acid etching and modified magnesiothermic reduction processes. The physical and chemical changes of these samples during the various processes have been analyzed. The as-prepared Hsbnd Si from halloysite clay is composed of many interconnected Si nanoparticles with an average diameter of 20-50 nm. Owing to the small size and porous nature, the Hsbnd Si nanoparticles exhibit a satisfactory performance as an anode for lithium ion batteries. Without further modification, a stable capacity over 2200 mAh g-1 at a rate of 0.2 C after 100 cycles and a reversible capacity above 800 mAh g-1 at a rate of 1 C after 1000 cycles can be obtained. As a result, this synthetic route is cost-effective and can be scaled up for mass production of Si nanoparticles, which may facilitate valuable utilization of halloysite clay and further commercial application of Si-based anode materials.

  19. Recent developments of ion sources for life-science studies at the Heavy Ion Medical Accelerator in Chiba (invited).

    PubMed

    Kitagawa, A; Drentje, A G; Fujita, T; Muramatsu, M; Fukushima, K; Shiraishi, N; Suzuki, T; Takahashi, K; Takasugi, W; Biri, S; Rácz, R; Kato, Y; Uchida, T; Yoshida, Y

    2016-02-01

    With about 1000-h of relativistic high-energy ion beams provided by Heavy Ion Medical Accelerator in Chiba, about 70 users are performing various biology experiments every year. A rich variety of ion species from hydrogen to xenon ions with a dose rate of several Gy/min is available. Carbon, iron, silicon, helium, neon, argon, hydrogen, and oxygen ions were utilized between 2012 and 2014. Presently, three electron cyclotron resonance ion sources (ECRISs) and one Penning ion source are available. Especially, the two frequency heating techniques have improved the performance of an 18 GHz ECRIS. The results have satisfied most requirements for life-science studies. In addition, this improved performance has realized a feasible solution for similar biology experiments with a hospital-specified accelerator complex.

  20. Recent developments of ion sources for life-science studies at the Heavy Ion Medical Accelerator in Chiba (invited)

    NASA Astrophysics Data System (ADS)

    Kitagawa, A.; Drentje, A. G.; Fujita, T.; Muramatsu, M.; Fukushima, K.; Shiraishi, N.; Suzuki, T.; Takahashi, K.; Takasugi, W.; Biri, S.; Rácz, R.; Kato, Y.; Uchida, T.; Yoshida, Y.

    2016-02-01

    With about 1000-h of relativistic high-energy ion beams provided by Heavy Ion Medical Accelerator in Chiba, about 70 users are performing various biology experiments every year. A rich variety of ion species from hydrogen to xenon ions with a dose rate of several Gy/min is available. Carbon, iron, silicon, helium, neon, argon, hydrogen, and oxygen ions were utilized between 2012 and 2014. Presently, three electron cyclotron resonance ion sources (ECRISs) and one Penning ion source are available. Especially, the two frequency heating techniques have improved the performance of an 18 GHz ECRIS. The results have satisfied most requirements for life-science studies. In addition, this improved performance has realized a feasible solution for similar biology experiments with a hospital-specified accelerator complex.

  1. Recent developments of ion sources for life-science studies at the Heavy Ion Medical Accelerator in Chiba (invited).

    PubMed

    Kitagawa, A; Drentje, A G; Fujita, T; Muramatsu, M; Fukushima, K; Shiraishi, N; Suzuki, T; Takahashi, K; Takasugi, W; Biri, S; Rácz, R; Kato, Y; Uchida, T; Yoshida, Y

    2016-02-01

    With about 1000-h of relativistic high-energy ion beams provided by Heavy Ion Medical Accelerator in Chiba, about 70 users are performing various biology experiments every year. A rich variety of ion species from hydrogen to xenon ions with a dose rate of several Gy/min is available. Carbon, iron, silicon, helium, neon, argon, hydrogen, and oxygen ions were utilized between 2012 and 2014. Presently, three electron cyclotron resonance ion sources (ECRISs) and one Penning ion source are available. Especially, the two frequency heating techniques have improved the performance of an 18 GHz ECRIS. The results have satisfied most requirements for life-science studies. In addition, this improved performance has realized a feasible solution for similar biology experiments with a hospital-specified accelerator complex. PMID:26932117

  2. Effect of ion dispersion forces on the electric double layer of colloids: a Monte Carlo simulation study.

    PubMed

    Martín-Molina, Alberto; Ibarra-Armenta, José G; Quesada-Pérez, Manuel

    2009-02-26

    In this work, the effect of ionic dispersion forces on the electric double layer of colloids is evaluated through Monte Carlo simulations. Particularly, the influence of these forces on the zeta-potential (as a representative electrokinetic property) is assessed. Ion polarizability is included in the primitive model with the help of the Lifshitz theory. In this way, ion specificity is not considered by means of phenomenological (and unknown a priori) parameters. Our results reveal that the ionic van der Waals forces are responsible (to some extent) for the specificity of the zeta-potential. In any case, the specific ion effects due to ion polarizability are strongly influenced by ion size. Furthermore, a preliminary study on the effect of ionic dehydration shows how this phenomenon improves the qualitative agreement between experimental data and simulations achieved in considering ionic dispersion forces. PMID:19199701

  3. Experimental Studies of Ion Beam Neutralization: Preliminary Results

    SciTech Connect

    Ding, N.; Polansky, J.; Downey, R.; Wang, J.

    2011-05-20

    A testing platform is designed to study ion beam neutralization in the mesothermal, collisionless region. In the experimental setup, argon neutrals were ionized in a microwave cavity and accelerated by a plasma lens system which was biased to 2500 V above the system ground. Electrons were boiled off from two hot tungsten filaments to neutralize the ion beam. The plasma is diagnosed using Langmuir probe and Faraday probe. A 3-D traversing system and a complete data acquisition loop were developed to efficiently measure 3-D beam profile. Preliminary measurements of beam profiles are presented for different operating conditions.

  4. Fundamental studies on the Cs dynamics under ion source conditions

    SciTech Connect

    Friedl, R. Fantz, U.

    2014-02-15

    The performance of surface conversion based negative hydrogen ion sources is mainly determined by the caesium dynamics. Therefore, fundamental investigations in vacuum and plasma are performed at a flexible laboratory setup with ion source parameters. Studies on the influence of Cs on the plasma parameters of H{sub 2} and D{sub 2} plasmas showed that n{sub e} and T{sub e} in the bulk plasma are not affected by relevant amounts of Cs and no isotopic differences could be observed. The coating of the vessel surfaces with Cs, however, leads to a considerable gettering of hydrogen atoms from the plasma volume and to the decrease of n{sub e} close to a sample surface due to the formation of negative ions.

  5. Ion mobility studies of carbohydrates as group I adducts: isomer specific collisional cross section dependence on metal ion radius.

    PubMed

    Huang, Yuting; Dodds, Eric D

    2013-10-15

    Carbohydrates play numerous critical roles in biological systems. Characterization of oligosaccharide structures is essential to a complete understanding of their functions in biological processes; nevertheless, their structural determination remains challenging in part due to isomerism. Ion mobility spectrometry provides the means to resolve gas phase ions on the basis of their shape-to-charge ratios, thus providing significant potential for separation and differentiation of carbohydrate isomers. Here, we report on the determination of collisional cross sections for four groups of isomeric carbohydrates (including five isomeric disaccharides, four isomeric trisaccharides, two isomeric pentasaccharides, and two isomeric hexasaccharides) as their group I metal ion adducts (i.e., [M + Li](+), [M + Na](+), [M + K](+), [M + Rb](+), and [M + Cs](+)). In all, 65 collisional cross sections were measured, the great majority of which have not been previously reported. As anticipated, the collisional cross sections of the carbohydrate metal ion adducts generally increase with increasing metal ion radius; however, the collisional cross sections were found to scale with the group I cation size in isomer specific manners. Such measurements are of substantial analytical value, as they illustrate how the selection of charge carrier influences carbohydrate ion mobility determinations. For example, certain pairs of isomeric carbohydrates assume unique collisional cross sections upon binding one metal ion, but not another. On the whole, these data suggest a role for the charge carrier as a probe of carbohydrate structure and thus have significant implications for the continued development and application of ion mobility spectrometry for the distinction and resolution of isomeric carbohydrates.

  6. Effect of finite ion sizes in an electrostatic potential distribution for a charged soft surface in contact with an electrolyte solution.

    PubMed

    Chanda, Sourayon; Das, Siddhartha

    2014-01-01

    We provide a theory to analyze the impact of finite ion sizes (or steric effect) in electrostatic potential distribution for a charged soft surface in contact with an electrolyte solution. The theory is based on a free energy model that appropriately accounts for the contribution of finite ion sizes as well as the structural characteristics of a soft interface, represented by a combination of a rigid surface and a fixed charge layer (FCL), with the FCL being in contact with an electrolyte solution forming an electric double layer (EDL). This FCL contains a particular kind of ion which is impermeable to the electrolyte solution, and this impermeability is quantified in terms of the corresponding Donnan potential of the "membrane" represented by the FCL-electrolyte interface. We find that consideration of the finite ion size increases the magnitude of this Donnan potential, with the extent of increase being dictated by three length scales, namely, the thickness of the FCL, the thickness of the electrolyte EDL, and the thickness of an equivalent EDL within the FCL. Such regulation of the Donnan potential strongly affects the distribution of the permeable electrolyte ions within the FCL, which in turn will have significant implications in several processes involving "soft" biological membranes. PMID:24580227

  7. A new high transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

    NASA Astrophysics Data System (ADS)

    Franchin, A.; Downard, A. J.; Kangasluoma, J.; Nieminen, T.; Lehtipalo, K.; Steiner, G.; Manninen, H. E.; Petäjä, T.; Flagan, R. C.; Kulmala, M.

    2015-06-01

    Reliable and reproducible measurements of atmospheric aerosol particle number size distributions below 10 nm require optimized classification instruments with high particle transmission efficiency. Almost all DMAs have an unfavorable potential gradient at the outlet (e.g. long column, Vienna type) or at the inlet (nano-radial DMA). This feature prevents them from achieving a good transmission efficiency for the smallest nanoparticles. We developed a new high transmission inlet for the Caltech nano-radial DMA (nRDMA) that increases the transmission efficiency to 12 % for ions as small as 1.3 nm in mobility equivalent diameter (corresponding to 1.2 × 10-4 m2 V-1 s-1 in electrical mobility). We successfully deployed the nRDMA, equipped with the new inlet, in chamber measurements, using a Particle Size Magnifier (PSM) and a booster Condensation Particle Counter (CPC) as a counter. With this setup, we were able to measure size distributions of ions between 1.3 and 6 nm, corresponding to a mobility range from 1.2 × 10-4 to 5.8 × 10-6 m2 V-1 s-1. The system was modeled, tested in the laboratory and used to measure negative ions at ambient concentrations in the CLOUD 7 measurement campaign at CERN. We achieved a higher size resolution than techniques currently used in field measurements, and maintained a good transmission efficiency at moderate inlet and sheath air flows (2.5 and 30 LPM, respectively). In this paper, by measuring size distribution at high size resolution down to 1.3 nm, we extend the limit of the current technology. The current setup is limited to ion measurements. However, we envision that future research focused on the charging mechanisms could extend the technique to measure neutral aerosol particles as well, so that it will be possible to measure size distributions of ambient aerosols from 1 nm to 1 μm.

  8. Damage growth in Si during self-ion irradiation: A study of ion effects over an extended energy range

    SciTech Connect

    Holland, O.W.; El-Ghor, M.K.; White, C.W.

    1989-01-01

    Damage nucleation/growth in single-crystal Si during ion irradiation is discussed. For MeV ions, the rate of growth as well as the damage morphology are shown to vary widely along the track of the ion. This is attributed to a change in the dominant, defect-related reactions as the ion penetrates the crystal. The nature of these reactions were elucidated by studying the interaction of MeV ions with different types of defects. The defects were introduced into the Si crystal prior to high-energy irradiation by self-ion implantation at a medium energy (100 keV). Varied damage morphologies were produced by implanting different ion fluences. Electron microscopy and ion-channeling measurements, in conjunction with annealing studies, were used to characterize the damage. Subtle changes in the predamage morphology are shown to result in markedly different responses to the high-energy irradiation, ranging from complete annealing of the damage to rapid growth. These divergent responses occur over a narrow range of dose (2--3 /times/ 10/sup 14/ cm/sup /minus/2/) of the medium-energy ions; this range also marks a transition in the growth behavior of the damage during the predamage implantation. A model is proposed which accounts for these observations and provides insight into ion-induced growth of amorphous layers in Si and the role of the amorphous/crystalline interface in this process. 15 refs, 9 figs.

  9. Design and synthesis of micron-sized spherical aggregates composed of hollow Fe2O3 nanospheres for use in lithium-ion batteries.

    PubMed

    Cho, Jung Sang; Hong, Young Jun; Lee, Jong-Heun; Kang, Yun Chan

    2015-05-14

    A novel structure denoted a "hollow nanosphere aggregate" is synthesized by introducing nanoscale Kirkendall diffusion to the spray pyrolysis process. The hollow Fe2O3 nanosphere aggregates with spherical shape and micron size are synthesized as the first target material. A solid iron oxide-carbon composite powder that is prepared by a one-pot spray pyrolysis process is transformed into the hollow Fe2O3 nanosphere aggregates by sequential post-pyrolysis treatments under reducing and oxidizing atmospheres. The nanoscale Kirkendall diffusion plays a key role in the formation of the hollow Fe2O3 nanosphere aggregates with spherical shape and micron size. The unique structure of the hollow Fe2O3 nanosphere aggregates results in their superior electrochemical properties as an anode material for lithium ion batteries by improving the structural stability during cycling. The hollow metal oxide nanosphere aggregates with various compositions for wide applications including energy storage can be prepared by the simple fabrication method introduced in this study.

  10. Size control of nanopores formed on SiO{sub 2} glass by swift-heavy-ion irradiation and its application to highly sensitive biomolecular detection

    SciTech Connect

    Nomura, Ken-ichi; Fujimaki, Makoto; Awazu, Koichi; Komatsubara, Tetsuro

    2011-09-15

    Swift-heavy-ion irradiation creates latent tracks in SiO{sub 2} glass and nanopores with a high aspect ratio can be formed along these ion paths by selective etching of the latent tracks using hydrogen fluoride (HF) vapor. Here we report that the size of nanopores can easily be controlled by simply changing the temperature of the HF solution generating the vapor and/or that of the SiO{sub 2} glass exposed to the vapor. Furthermore, this method of size control was used to produce SiO{sub 2} glass sheets with nanopores of different sizes and number densities for use as the waveguide layer in the sensing plates for a waveguide-mode sensor. In comparison with nonperforated plates, the increased surface area due to the formation of nanopores was found to create up to a tenfold increase in sensitivity.

  11. Application of a static quadrupole deviator to the deposition of size-selected cluster ions from a laser vaporization source

    NASA Astrophysics Data System (ADS)

    Alayan, R.; Arnaud, L.; Bourgey, A.; Broyer, M.; Cottancin, E.; Huntzinger, J. R.; Lermé, J.; Vialle, J. L.; Pellarin, M.; Guiraud, G.

    2004-07-01

    An electrostatic quadrupole deviator is used to separate charged from neutral clusters produced by a laser vaporization source. Because of their rather constant velocity, this device which is basically an energy selector also acts as an efficient mass filter. We have simulated and studied its capability to generate beams of size-selected charged clusters. Typical beam currents of a few tens of pA allow the formation of two-dimensional cluster deposits within a few minutes. Platinum and indium clusters are deposited on electron microscopy grids coated with an amorphous carbon film. For low-density assemblies of particles in the nanometer range, size histograms are discussed in relation with the mass selectivity of the apparatus. An upper limit for the dispersion of selected cluster diameters is found to be of the order of ±8% which is at least five times better than the dispersion of neutral species.

  12. Utilization of Benchtop Next Generation Sequencing Platforms Ion Torrent PGM and MiSeq in Noninvasive Prenatal Testing for Chromosome 21 Trisomy and Testing of Impact of In Silico and Physical Size Selection on Its Analytical Performance

    PubMed Central

    Minarik, Gabriel; Repiska, Gabriela; Hyblova, Michaela; Nagyova, Emilia; Soltys, Katarina; Budis, Jaroslav; Duris, Frantisek; Sysak, Rastislav; Gerykova Bujalkova, Maria; Vlkova-Izrael, Barbora; Biro, Orsolya; Nagy, Balint; Szemes, Tomas

    2015-01-01

    Objectives The aims of this study were to test the utility of benchtop NGS platforms for NIPT for trisomy 21 using previously published z score calculation methods and to optimize the sample preparation and data analysis with use of in silico and physical size selection methods. Methods Samples from 130 pregnant women were analyzed by whole genome sequencing on benchtop NGS systems Ion Torrent PGM and MiSeq. The targeted yield of 3 million raw reads on each platform was used for z score calculation. The impact of in silico and physical size selection on analytical performance of the test was studied. Results Using a z score value of 3 as the cut-off, 98.11% - 100% (104-106/106) specificity and 100% (24/24) sensitivity and 99.06% - 100% (105-106/106) specificity and 100% (24/24) sensitivity were observed for Ion Torrent PGM and MiSeq, respectively. After in silico based size selection both platforms reached 100% specificity and sensitivity. Following the physical size selection z scores of tested trisomic samples increased significantly—p = 0.0141 and p = 0.025 for Ion Torrent PGM and MiSeq, respectively. Conclusions Noninvasive prenatal testing for chromosome 21 trisomy with the utilization of benchtop NGS systems led to results equivalent to previously published studies performed on high-to-ultrahigh throughput NGS systems. The in silico size selection led to higher specificity of the test. Physical size selection performed on isolated DNA led to significant increase in z scores. The observed results could represent a basis for increasing of cost effectiveness of the test and thus help with its penetration worldwide. PMID:26669558

  13. Molecular dynamics study of accelerated ion-induced shock waves in biological media

    NASA Astrophysics Data System (ADS)

    de Vera, Pablo; Mason, Nigel J.; Currell, Fred J.; Solov'yov, Andrey V.

    2016-09-01

    We present a molecular dynamics study of the effects of carbon- and iron-ion induced shock waves in DNA duplexes in liquid water. We use the CHARMM force field implemented within the MBN Explorer simulation package to optimize and equilibrate DNA duplexes in liquid water boxes of different sizes and shapes. The translational and vibrational degrees of freedom of water molecules are excited according to the energy deposited by the ions and the subsequent shock waves in liquid water are simulated. The pressure waves generated are studied and compared with an analytical hydrodynamics model which serves as a benchmark for evaluating the suitability of the simulation boxes. The energy deposition in the DNA backbone bonds is also monitored as an estimation of biological damage, something which is not possible with the analytical model. Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by Gerardo Delgado Barrio, Andrey V. Solov'yov, Pablo Villarreal, Rita Prosmiti.

  14. Molecular dynamics study of accelerated ion-induced shock waves in biological media

    NASA Astrophysics Data System (ADS)

    de Vera, Pablo; Mason, Nigel J.; Currell, Fred J.; Solov'yov, Andrey V.

    2016-09-01

    We present a molecular dynamics study of the effects of carbon- and iron-ion induced shock waves in DNA duplexes in liquid water. We use the CHARMM force field implemented within the MBN Explorer simulation package to optimize and equilibrate DNA duplexes in liquid water boxes of different sizes and shapes. The translational and vibrational degrees of freedom of water molecules are excited according to the energy deposited by the ions and the subsequent shock waves in liquid water are simulated. The pressure waves generated are studied and compared with an analytical hydrodynamics model which serves as a benchmark for evaluating the suitability of the simulation boxes. The energy deposition in the DNA backbone bonds is also monitored as an estimation of biological damage, something which is not possible with the analytical model.

  15. Thermal Characterization Study of Lithium-Ion Cells

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.; Miller, Thomas B.; Bennett, William R.

    2007-01-01

    The primary challenge in designing a full scale lithium-ion (Li-ion) battery system is safety under both normal operating as well as abusive conditions. The normal conditions involve expected charge/discharge cycles and it is known that heat evolves in batteries during those cycles. This is a major concern in the design for high power applications and careful thermal management is necessary to alleviate this concern. An emerging thermal measurement technology, such as the electrochemical calorimetric of batteries, will aid in the development of advanced, safe battery system. To support this technology, several "commercial-off-the-shelf" (COTS) Li-ion cells with different chemistries and designs are being evaluated for different cycling regimes at a given operating temperature. The Accelerated Rate Calorimeter (ARC)-Arbin cycler setup is used to measure the temperature, voltage, and current of the cells at different charge/discharge rates. Initial results demonstrated good cell cyclability. During the cycle testing, the cell exhibited an endothermic cooling in the initial part of the charge cycle. The discharge portion of the cycle is exothermic during the entire discharge period. The presence of an endothermic reaction indicates a significant entropy effect during the beginning of charge cycle. Further studies will be performed to understand the thermal characteristics of the Li-ion cells at the different operating conditions. The effects on the thermal response on cell aging and states-of-charge will also be identified.

  16. Ion engine auxiliary propulsion applications and integration study

    NASA Technical Reports Server (NTRS)

    Zafran, S. (Editor)

    1977-01-01

    The benefits derived from application of the 8-cm mercury electron bombardment ion thruster were assessed. Two specific spacecraft missions were studied. A thruster was tested to provide additional needed information on its efflux characteristics and interactive effects. A Users Manual was then prepared describing how to integrate the thruster for auxiliary propulsion on geosynchronous satellites. By incorporating ion engines on an advanced communications mission, the weight available for added payload increases by about 82 kg (181 lb) for a 100 kg (2200 lb) satellite which otherwise uses electrothermal hydrazine. Ion engines can be integrated into a high performance propulsion module that is compatible with the multimission modular spacecraft and can be used for both geosynchronous and low earth orbit applications. The low disturbance torques introduced by the ion engines permit accurate spacecraft pointing with the payload in operation during thrusting periods. The feasibility of using the thruster's neutralizer assembly for neutralization of differentially charged spacecraft surfaces at geosynchronous altitude was demonstrated during the testing program.

  17. Progress of the Proton-Ion Medical Machine Study (PIMMS).

    PubMed

    Bryant, P J

    1999-06-01

    The Proton-Ion Medical Machine Study (PIMMS) was set up following an agreement between Professor M. Regler of the Med-AUSTRON (Austria) and Professor U. Amaldi of the TERA Foundation (Italy) to join their efforts in the design of a medical synchrotron that could later be adapted to individual national needs. CERN agreed to host this study inside its PS Division and to contribute one full-time member to the study team. The study group has worked in collaboration with GSI (Germany) and was more recently joined by Onkologie 2000 (Czech Republic). Work started in January 1996 and is expected to finish during 1998. The agreed aim of the study was to investigate and design a generic facility that would allow the direct clinical comparison of protons and carbon ions for cancer treatment. The accelerator was to be designed primarily for high-precision active beam scanning with both protons and ions, but was also to be capable of delivering proton beams with passive spreading. PMID:10394382

  18. Test particle study of ion transport in drift type turbulence

    SciTech Connect

    Vlad, M.; Spineanu, F.

    2013-12-15

    Ion transport regimes in drift type turbulence are determined in the frame of a realistic model for the turbulence spectrum based on numerical simulations. The model includes the drift of the potential with the effective diamagnetic velocity, turbulence anisotropy, and dominant waves. The effects of the zonal flow modes are also analyzed. A semi-analytical method that is able to describe trajectory stochastic trapping or eddying is used for obtaining the transport coefficients as function of the parameters of the turbulence. Analytical approximations of the transport coefficients are derived from the results. They show the transition from Bohm to gyro-Bohm scaling as plasma size increases in very good agreement with the numerical simulations.

  19. The effects of ion mass variation and domain size on octupolar out-of-plane magnetic field generation in collisionless magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Graf von der Pahlen, J.; Tsiklauri, D.

    2015-03-01

    Graf von der Pahlen and Tsiklauri [Phys. Plasmas 21, 060705 (2014)] established that the generation of octupolar out-of-plane magnetic field structure in a stressed X-point collapse is due to ion currents. The field has a central region, comprising of the well-known quadrupolar field (quadrupolar components), as well as four additional poles of reversed polarity closer to the corners of the domain (octupolar components). In this extended work, the dependence of the octupolar structure on domain size and ion mass variation is investigated. Simulations show that the strength and spatial structure of the generated octupolar magnetic field is independent of ion to electron mass ratio; thus showing that ion currents play a significant role in out-of-plane magnetic structure generation in physically realistic scenarios. Simulations of different system sizes show that the width of the octupolar structure remains the same and has a spacial extent of the order of the ion inertial length. The width of the structure thus appears to be independent on boundary condition effects. The length of the octupolar structure, however, increases for greater domain sizes, prescribed by the external system size. This was found to be a consequence of the structure of the in-plane magnetic field in the outflow region halting the particle flow and thus terminating the in-plane currents that generate the out-of-plane field. The generation of octupolar magnetic field structure is also established in a tearing-mode reconnection scenario. The differences in the generation of the octupolar field and resulting qualitative differences between X-point collapse and tearing-mode are discussed.

  20. The effects of ion mass variation and domain size on octupolar out-of-plane magnetic field generation in collisionless magnetic reconnection

    SciTech Connect

    Graf von der Pahlen, J.; Tsiklauri, D.

    2015-03-15

    Graf von der Pahlen and Tsiklauri [Phys. Plasmas 21, 060705 (2014)] established that the generation of octupolar out-of-plane magnetic field structure in a stressed X-point collapse is due to ion currents. The field has a central region, comprising of the well-known quadrupolar field (quadrupolar components), as well as four additional poles of reversed polarity closer to the corners of the domain (octupolar components). In this extended work, the dependence of the octupolar structure on domain size and ion mass variation is investigated. Simulations show that the strength and spatial structure of the generated octupolar magnetic field is independent of ion to electron mass ratio; thus showing that ion currents play a significant role in out-of-plane magnetic structure generation in physically realistic scenarios. Simulations of different system sizes show that the width of the octupolar structure remains the same and has a spacial extent of the order of the ion inertial length. The width of the structure thus appears to be independent on boundary condition effects. The length of the octupolar structure, however, increases for greater domain sizes, prescribed by the external system size. This was found to be a consequence of the structure of the in-plane magnetic field in the outflow region halting the particle flow and thus terminating the in-plane currents that generate the out-of-plane field. The generation of octupolar magnetic field structure is also established in a tearing-mode reconnection scenario. The differences in the generation of the octupolar field and resulting qualitative differences between X-point collapse and tearing-mode are discussed.

  1. A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

    NASA Astrophysics Data System (ADS)

    Franchin, Alessandro; Downard, Andy; Kangasluoma, Juha; Nieminen, Tuomo; Lehtipalo, Katrianne; Steiner, Gerhard; Manninen, Hanna E.; Petäjä, Tuukka; Flagan, Richard C.; Kulmala, Markku

    2016-06-01

    Reliable and reproducible measurements of atmospheric aerosol particle number size distributions below 10 nm require optimized classification instruments with high particle transmission efficiency. Almost all differential mobility analyzers (DMAs) have an unfavorable potential gradient at the outlet (e.g., long column, Vienna type) or at the inlet (nano-radial DMA), preventing them from achieving a good transmission efficiency for the smallest nanoparticles. We developed a new high-transmission inlet for the Caltech nano-radial DMA (nRDMA) that increases the transmission efficiency to 12 % for ions as small as 1.3 nm in Millikan-Fuchs mobility equivalent diameter, Dp (corresponding to 1.2 × 10-4 m2 V-1 s-1 in electrical mobility). We successfully deployed the nRDMA, equipped with the new inlet, in chamber measurements, using a particle size magnifier (PSM) and as a booster a condensation particle counter (CPC). With this setup, we were able to measure size distributions of ions within a mobility range from 1.2 × 10-4 to 5.8 × 10-6 m2 V-1 s-1. The system was modeled, tested in the laboratory and used to measure negative ions at ambient concentrations in the CLOUD (Cosmics Leaving Outdoor Droplets) 7 measurement campaign at CERN. We achieved a higher size resolution (R = 5.5 at Dp = 1.47 nm) than techniques currently used in field measurements (e.g., Neutral cluster and Air Ion Spectrometer (NAIS), which has a R ˜ 2 at largest sizes, and R ˜ 1.8 at Dp = 1.5 nm) and maintained a good total transmission efficiency (6.3 % at Dp = 1.5 nm) at moderate inlet and sheath airflows (2.5 and 30 L min-1, respectively). In this paper, by measuring size distributions at high size resolution down to 1.3 nm, we extend the limit of the current technology. The current setup is limited to ion measurements. However, we envision that future research focused on the charging mechanisms could extend the technique to measure neutral aerosol particles as well, so that it will be possible

  2. Preparation of nano-sized graphite-supported CuO and Cu-Sn as active materials in lithium ion batteries.

    PubMed

    Jung, Dong-Won; Jeong, Jae-Hun; Kong, Byung-Seon; Lee, Jung Kyoo; Oh, Eun-Suok

    2012-04-01

    Nano-sized Cu-Sn and Cu oxide particles supported on ball-milled graphite were synthesized, and their electrochemical characteristics for use as anode active materials in lithium-ion batteries were investigated. The samples were also characterized via FE-SEM, XRD, and TGA. Most of the Cu oxides on BMG were monoclinic CuO crystals, whereas the Cu-Sn particles were composed of hexagonal Cu3Sn and tetragonal SnO2 crystals. These particles may contribute to an increase in the reversible capacity of lithium ion batteries.

  3. Composites from powder coated towpreg - Studies with variable tow sizes

    NASA Technical Reports Server (NTRS)

    Hugh, Maylene K.; Marchello, Joseph M.; Baucom, Robert M.; Johnston, Norman J.

    1992-01-01

    Part fabrication from composite materials usually costs less when larger fiber tow bundles are used. On the other hand, mechanical properties generally are lower for composites made using larger size tows. This situation gives rise to a choice between costs and properties in determining the best fiber tow bundle size to employ in preparing prepreg materials for part fabrication. To address this issue, unidirectional and eight harness satin fabric composite specimens were fabricated from 3k, 6k, and 12k carbon fiber reinforced LARC-TPI powder coated towpreg. Short beam shear strengths and longitudinal and transverse flexure properties were obtained for the unidirectional specimens. Tension properties were obtained for the eight harness satin woven towpreg specimens. Knowledge of the variation of properties with tow size may serve as a guide in material selection for part fabrication.

  4. Composites from powder coated towpreg - Studies with variable tow sizes

    NASA Astrophysics Data System (ADS)

    Hugh, Maylene K.; Marchello, Joseph M.; Baucom, Robert M.; Johnston, Norman J.

    Part fabrication from composite materials usually costs less when larger fiber tow bundles are used. On the other hand, mechanical properties generally are lower for composites made using larger size tows. This situation gives rise to a choice between costs and properties in determining the best fiber tow bundle size to employ in preparing prepreg materials for part fabrication. To address this issue, unidirectional and eight harness satin fabric composite specimens were fabricated from 3k, 6k, and 12k carbon fiber reinforced LARC-TPI powder coated towpreg. Short beam shear strengths and longitudinal and transverse flexure properties were obtained for the unidirectional specimens. Tension properties were obtained for the eight harness satin woven towpreg specimens. Knowledge of the variation of properties with tow size may serve as a guide in material selection for part fabrication.

  5. Separation of organic ion exchange resins from sludge -- engineering study

    SciTech Connect

    Duncan, J.B.

    1998-08-25

    This engineering study evaluates the use of physical separation technologies to separate organic ion exchange resin from KE Basin sludge prior to nitric acid dissolution. This separation is necessitate to prevent nitration of the organics in the acid dissolver. The technologies under consideration are: screening, sedimentation, elutriation. The recommended approach is to first screen the Sludge and resin 300 microns then subject the 300 microns plus material to elutriation.

  6. Grain size assisted formation of pseudotachylites: A numerical study

    NASA Astrophysics Data System (ADS)

    Thielmann, Marcel; Rozel, Antoine; Kaus, Boris; Ricard, Yanick

    2014-05-01

    The processes resulting in the formation of lithospheric-scale shear zones are still poorly understood. Among others, shear heating and grain size reduction have been proposed to be viable weakening mechanisms to localize deformation and form lithospheric-scale shear zones. The interplay between both mechanisms is particularly interesting, as both compete for a part of the deformational work. High temperatures favor grain growth, therefore one would expect larger grain sizes in shear zones that have been formed by shear heating. However, larger temperatures increase strain rates, thus also the amount of deformational work, which in turn would favor grain size reduction. Here we investigate the interplay between both mechanisms using numerical models of a viscoelastic slab deforming in simple shear, employing a viscous rheology composed of dislocation and diffusion creep. Grain size evolution is governed by a recently developed physics-based evolution law. We develop scaling laws for the peak stress and the dominating deformation mechanisms depending on various material parameters and boundary conditions. We find that grain size reduction alone does not localize deformation in simple shear. In conjunction with shear heating however, a localized shear zone is formed due to thermal runaway. During this process, grain size is significantly reduced. Depending on grain growth parameters, a mylonitic shear zone is formed in which deformation is permanently localized and which deforms in diffusion creep. Additionally, the stress required to initiate thermal runaway is reduced compare to cases with shear heating alone, thus facilitating the formation of a narrow localized shear zone in the ductile regime. These results have several implications ranging and from simultaneous pseudotachylite and mylonite formation at depths below the seismogenic depth to subduction initiation.

  7. Particle sizing in rocket motor studies utilizing hologram image processing

    NASA Technical Reports Server (NTRS)

    Netzer, David; Powers, John

    1987-01-01

    A technique of obtaining particle size information from holograms of combustion products is described. The holograms are obtained with a pulsed ruby laser through windows in a combustion chamber. The reconstruction is done with a krypton laser with the real image being viewed through a microscope. The particle size information is measured with a Quantimet 720 image processing system which can discriminate various features and perform measurements of the portions of interest in the image. Various problems that arise in the technique are discussed, especially those that are a consequence of the speckle due to the diffuse illumination used in the recording process.

  8. Nano-sized LiMn2O4 spinel cathode materials exhibiting high rate discharge capability for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Chen, Yingchao; Xie, Kai; Pan, Yi; Zheng, Chunman

    2011-08-01

    Nano-sized LiMn2O4 spinel with well crystallized homogeneous particles (60 nm) is synthesized by a resorcinol-formaldehyde route. Micro-sized LiMn2O4 spinel with micrometric particles (1 μm) is prepared by a conventional solid-state reaction. These two samples are characterized by XRD, SEM, TEM, BET, and electrochemical methods. At current rate of 0.2C (1C = 148 mA g-1), a discharge capacity of 136 mAh g-1 is obtained on the nano-sized LiMn2O4, which is higher than that of micro-sized one (103 mAh g-1). Furthermore, compared to the micro-sized sample, nano-sized LiMn2O4 shows much better rate capability, i.e. a capacity of 85 mAh g-1, 63% of that at 0.2C, is realized at 60C. The excellent high rate performance of nano-sized LiMn2O4 spinel may be attributed to its impurity-free nano-sized particles, higher surface area and well crystalline. The outstanding electrochemical performances demonstrate that the nano-sized LiMn2O4 spinel will be the promising cathode materials for high power lithium-ion batteries used in hybrid and electric vehicles.

  9. Finite-size effects in nanocomposites: experimental and computational studies

    NASA Astrophysics Data System (ADS)

    Clarke, L. I.; Roman, M. P.; Skau, E. W.; Stevens, D. R.; Downen, L. N.; Hoffman, T. J.; Bochinski, J. R.

    2012-02-01

    Many proposed applications for electrically-conducting composite materials (smart textiles, e-m shielding coatings, tissue scaffolds) are nanostructured - that is, characteristic sample length scales may be similar to at least one dimension of the embedded particle. This is particularly true for long aspect-ratio particles such as nanotubes where the length of the particle can approach or exceed the thickness of a thin nanocomposite film or a nanofiber diameter. In these cases, the formation of a particle network and thus the electrical conductivity enhancement is affected by finite size effects, that is, percolation thresholds and the width of the transition to percolation differ with sample size [Stevens et al., Phys. Rev. E 84, 021126 (2011)]. We present experimental electrical conductivity and 3-D continuum Monte-Carlo simulation results on such finite-sized percolation effects for particles with aspect ratios of 1 to 1000 and discuss proposed scaling laws and techniques to improve conductance in the finite-size regime.

  10. Bach Adsorption Study for the Extraction of Silver Ions by Hydrazone Compounds from Aqueous Solution

    PubMed Central

    Mohamad Ali, Abdussalam Salhin; Abdul Razak, Norfarhah; Ab Rahman, Ismail

    2012-01-01

    Sorbent materials based on a hydrazone Schiff base compound, C14H11BrN4O4, were prepared either by immobilizing the ligand into sol-gel (SG1) or bonding to silica (SG2). The sorbent materials were characterized by FT-IR, EDX, SEM, TEM, and TGA. The sorption characteristics of a matrix of eight transition metal ions (Ag+, Cu2+, Co2+, Ni2+, Fe3+, Pb2+, Zn2+, and Mn2+) using batch method were studied. Several key parameters that affected the extraction efficiency such as pH, contact time, metal ions concentration, and gel size (for SGl) were investigated and optimized. Under the optimized conditions, the physically immobilized hydrazone sorbent (SG1) exhibits highest selectivity towards Ag+ ions, while the chemically bonded hydrazone sorbent (SG2) exhibits high extraction for all metal ions tested. However, for practical applications such as the removal and preconcentration of Ag+, the physically immobilized sorbent (SG1) is preferred. PMID:22629138

  11. Distributions of deposited energy and ionization clusters around ion tracks studied with Geant4 toolkit

    NASA Astrophysics Data System (ADS)

    Burigo, Lucas; Pshenichnov, Igor; Mishustin, Igor; Hilgers, Gerhard; Bleicher, Marcus

    2016-05-01

    The Geant4-based Monte Carlo model for Heavy-Ion Therapy (MCHIT) was extended to study the patterns of energy deposition at sub-micrometer distance from individual ion tracks. Dose distributions for low-energy 1H, 4He, 12C and 16O ions measured in several experiments are well described by the model in a broad range of radial distances, from 0.5 to 3000 nm. Despite the fact that such distributions are characterized by long tails, a dominant fraction of deposited energy (∼80%) is confined within a radius of about 10 nm. The probability distributions of clustered ionization events in nanoscale volumes of water traversed by 1H, 2H, 4He, 6Li, 7Li, and 12C ions are also calculated. A good agreement of calculated ionization cluster-size distributions with the corresponding experimental data suggests that the extended MCHIT can be used to characterize stochastic processes of energy deposition to sensitive cellular structures.

  12. Atomic resolution study of displacement cascades in ion-irradiated platinum

    NASA Astrophysics Data System (ADS)

    Pramanik, Dipankar; Seidman, David N.

    1986-07-01

    The field-ion microscope technique has been employed to study, on an atomic scale, the vacancy structure of individual depleted zones (DZs) in platinum specimens which had been created by 20-keV Kr+ ions. DZs are the final quiescent state of collision cascades. The irradiations were performed in situ at 60 K and the specimens were examined at this temperature by the pulse field-evaporation technique. The following experimental quantities were determined for each DZ: (a) the absolute number of vacancies (ν); (b) the average diameter; (c) the average vacancy concentration based on ν and the actual volume filled by the vacancies; (d) the radial distribution function of the vacancies out to the ninth nearest-neighbor; (e) the fraction of first-nearest-neighbor vacancies in clusters of size n; (f) the average depth (L) from the irradiated surface, measured along a direction parallel to the incident ion beam, at which each DZ was detected and its direction of elongation; and (g) the sputtering yield based on the number of vacancies detected in the near-surface region (<5 Å thick). All of the measured quantities are compared with corresponding quantities extracted from either an analytical model or a Monte Carlo computer code (Transport of Ions in Matter—trim) of radiation damage. We demonstrate that it is possible to transform a microscopic spatial distribution of vacancies to a continuous radiation damage profile with atomic resolution.

  13. Neutron-induced reaction studies using stored ions

    NASA Astrophysics Data System (ADS)

    Glorius, Jan; Litvinov, Yuri A.; Reifarth, René

    2015-11-01

    Storage rings provide unique possibilities for investigations of nuclear reactions. Radioactive ions can be stored if the ring is connected to an appropriate facility and reaction studies are feasible at low beam intensities because of the recycling of beam particles. Using gas jet or droplet targets, charged particle-induced reactions on short-lived isotopes can be studied in inverse kinematics. In such a system a high-flux reactor could serve as a neutron target extending the experimental spectrum to neutron-induced reactions. Those could be studied over a wide energy range covering the research fields of nuclear astrophysics and reactor safety, transmutation of nuclear waste and fusion.

  14. Capillary electrophoretic study of thiolated alpha-cyclodextrin-capped gold nanoparticles with tetraalkylammonium ions.

    PubMed

    Paau, Man Chin; Lo, Chung Keung; Yang, Xiupei; Choi, Martin M F

    2009-11-27

    Capillary zone electrophoresis (CZE) has been employed to characterize nanometer-sized thiolated alpha-cyclodextrin-capped gold nanoparticles (alpha-CD-S-AuNPs). The addition of tetrabutylammonium (Bu(4)N(+)) ions to the run buffer greatly narrows the migration peak of alpha-CD-S-AuNP. The optimal run buffer was determined to be 10mM Bu(4)N(+) in 30 mM phosphate buffer at pH 12 and an applied voltage of 15 kV. The effect of various tetraalkylammonium ions on the peak width and electrophoretic mobility (mu(e)) of alpha-CD-S-AuNP was studied in detail. Bu(4)N(+) ions assist in inter-linking the alpha-CD-S-AuNPs and narrowing the migration peak in CZE. This observation can be explained by the fact that each Bu(4)N(+) ion can simultaneously interact with several hydrophobic cavities of the surface-attached alpha-CDs on AuNPs. The TEM images show that alpha-CD-S-AuNPs with Bu(4)N(+) are linked together but in the absence of Bu(4)N(+), they are more dispersed. The migration mechanism in CZE is based on the formation of inclusion complexes between Bu(4)N(+) and alpha-CD-S-AuNPs which induces changes in the charge-to-size ratio of alpha-CD-S-AuNPs and mu(e). An inverse linear relationship (r(2)>0.998) exists between the mu(e) and size of alpha-CD-S-AuNPs in the core range 1.4-4.1 nm. The CZE analyses are rapid with migration time less than 4 min. A few nanoliters of each of the alpha-CD-S-AuNP samples were injected hydrodynamically at 0.5 psi for 5s. Our work confirms that CZE is an efficient tool for characterizing the sizes of alpha-CD-S-AuNPs using Bu(4)N(+) ions. PMID:19853853

  15. Direct reaction experimental studies with beams of radioactive tin ions

    SciTech Connect

    Jones, K. L. Ayres, A.; Bey, A.; Burcher, S.; Cartegni, L.; Cerizza, G.; Ahn, S.; Allmond, J. M.; Beene, J. R.; Galindo-Uribarri, A.; Liang, J. F.; Nesaraja, C. D.; Pain, S. D.; Radford, D. C.; Schmitt, K. T.; Smith, M. S.; Stracener, D. W.; Varner, R. L.; Bardayan, D. W.; Baugher, T.; and others

    2015-10-15

    The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at {sup 100}Sn, through 10 stable isotopes and the N = 82 shell closure at {sup 132}Sn out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic nuclei. Here we present one experiment knocking out neutrons from tin isotopes that are already neutron deficient and two reactions that add a neutron to neutron-rich {sup 130}Sn. Both techniques rely on selective particle identification and the measurement of γ rays in coincidence with charged ions. We present the goals of the two experiments and the particle identification for the channels of interest. The final results will be presented in future publications.

  16. Direct Reaction Experimental Studies with Beams of Radioactive Tin Ions

    SciTech Connect

    Jones, K. L.; Ahn, S.H.; Allmond, James M; Ayres, A.; Bardayan, Daniel W; Baugher, T.; Bazin, D.; Beene, James R; Berryman, J. S.; Bey, A.; Bingham, C. R.; Cartegni, L.; Chae, K. Y.; Gade, A.; Galindo-Uribarri, Alfredo {nmn}; Garcia-Ruiz, R.F.; Grzywacz, Robert Kazimierz; Howard, Meredith E; Kozub, R. L.; Liang, J Felix; Manning, Brett M; Matos, M.; McDaniel, S.; Miller, D.; Nesaraja, Caroline D; O'Malley, Patrick; Padgett, S; Padilla-Rodal, Elizabeth; Pain, Steven D; Pittman, S. T.; Radford, David C; Ratkiewicz, Andrew J; Schmitt, Kyle; Smith, Michael Scott; Stracener, Daniel W; Stroberg, S.; Tostevin, Jeffrey A; Varner Jr, Robert L; Weisshaar, D.; Wimmer, K.

    2015-01-01

    The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at Sn-100, through 10 stable isotopes and the N = 82 shell closure at Sn-132 out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic nuclei. Here we present one experiment knocking out neutrons from tin isotopes that are already neutron deficient and two reactions that add a neutron to neutron-rich Sn-130. Both techniques rely on selective particle identification and the measurement of gamma rays in coincidence with charged ions. We present the goals of the two experiments and the particle identification for the channels of interest. The final results will be presented in future publications.

  17. A comparative first principles study on trivalent ion incorporated SSZ-13 zeolites.

    PubMed

    Wen, Cui; Geng, Lu; Han, Lina; Wang, Jiancheng; Chang, Liping; Feng, Gang; Kong, Dejin; Liu, Jianwen

    2015-11-28

    The dispersion-corrected density functional theory has been used to study the trivalent ions B, Al, Ga, and Fe incorporated SSZ-13-type zeolites. The associated structure and Brønsted/Lewis acidity change caused by the incorporation ions were comparatively studied. It was found that the smaller the radius differences of the incorporation ions are, the smaller the changes in the structure will be and the less acidity will be enhanced for the Brønsted sites. The trivalent Al is found to be the most favorable trivalent incorporation ion and Na is found to be the most favorable charge balanced ion for the synthesis of SSZ-13-type zeolites due to size comparability, which are in line with the experimental observation. The substitution energies which show the relative synthesis difficulty level were also applied for B, Al, Ga, and Fe incorporated zeolites and found that the difficulty decreases with order of Fe > B > Ga ≫ Al, also in good agreement with the experimental observations. Adsorption studies for the NH3 and pyridine molecules indicate that adsorption on the Brønsted acid sites is more stable than on the Lewis acid sites. The Brønsted acidity was found to follow the order of HAl-SSZ-13 > HGa-SSZ-13 ≈ HFe-SSZ-13 > HB-SSZ-13 where the Lewis acidity was found to follow the order of HGa-SSZ-13 ≈ HFe-SSZ-13 > HAl-SSZ-13 > HB-SSZ-13. Our results provide new insights for the synthesis of the SSZ-13-type zeolites and fundamental information for the zeolitic catalyst designation to enhance the catalytic performance. PMID:26477513

  18. A critique of comparative studies of brain size

    PubMed Central

    Healy, Susan D; Rowe, Candy

    2006-01-01

    In recent years, there have been over 50 comparative analyses carried out in which social or ecological variables have been used to explain variation in whole brain size, or a part thereof, in a range of vertebrate species. Here, we review this body of work, pointing out that there are a number of substantial problems with some of the assumptions that underpin the hypotheses (e.g. what brain size means), with the data collection and with the ways in which the data are combined in the analyses. These problems are particularly apparent in those analyses in which attempts are made to correlate complex behaviour with parts of the brain that carry out multiple functions. We conclude that now is the time to substantiate these results with data from experimental manipulations. PMID:17476764

  19. Increased size selectivity of Si quantum dots on SiC at low substrate temperatures: An ion-assisted self-organization approach

    SciTech Connect

    Seo, D. H.; Das Arulsamy, A.; Rider, A. E.; Levchenko, I.; Ostrikov, K.

    2010-01-15

    A simple, effective, and innovative approach based on ion-assisted self-organization is proposed to synthesize size-selected Si quantum dots (QDs) on SiC substrates at low substrate temperatures. Using hybrid numerical simulations, the formation of Si QDs through a self-organization approach is investigated by taking into account two distinct cases of Si QD formation using the ionization energy approximation theory, which considers ionized in-fluxes containing Si{sup 3+} and Si{sup 1+} ions in the presence of a microscopic nonuniform electric field induced by a variable surface bias. The results show that the highest percentage of the surface coverage by 1 and 2 nm size-selected QDs was achieved using a bias of -20 V and ions in the lowest charge state, namely, Si{sup 1+} ions in a low substrate temperature range (227-327 deg. C). As low substrate temperatures ({<=}500 deg. C) are desirable from a technological point of view, because (i) low-temperature deposition techniques are compatible with current thin-film Si-based solar cell fabrication and (ii) high processing temperatures can frequently cause damage to other components in electronic devices and destroy the tandem structure of Si QD-based third-generation solar cells, our results are highly relevant to the development of the third-generation all-Si tandem photovoltaic solar cells.

  20. Cellular track model for study of heavy ion beams

    NASA Technical Reports Server (NTRS)

    Shinn, Judy L.; Katz, Robert; Cucinotta, Francis A.; Wilson, John W.; Ngo, Duc M.

    1993-01-01

    Track theory is combined with a realistic model of a heavy ion beam to study the effects of nuclear fragmentation on cell survival and biological effectiveness. The effects of secondary reaction products are studied as a function of depth in a water column. Good agreement is found with experimental results for the survival of human T-l cells exposed to monoenergetic carbon, neon, and argon beams under aerobic and hypoxia conditions. The present calculation, which includes the effect of target fragmentation, is a significant improvement over an earlier calculation because of the use of a vastly improved beam model with no change in the track theory or cellular response parameters.

  1. Studies of Interstellar Pickup Ions in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Isenberg, Philip A.; Lee, Martin A.; Mobius, Eberhard

    1996-01-01

    The work under this grant involves studies of the interaction of interstellar pickup ions with the solar wind, with the goal of a comprehensive model of the particle distributions and wave intensities to be expected throughout the heliosphere, as well as the interactions of those distributions with the solar wind termination shock. In the past year, we have completed a number of projects, including observations and modeling of the effects of a large scattering mean free path on the pickup He(+) seen at AMPTE, an analytical model of anisotropic pickup tons in a steady radial magnetic field, and a derivation of a reduced solar wind Mach number due to increased estimates on the inflowing hydrogen density allowing for a weak termination shock. In the next year, we plan to investigate in more detail the correspondence between our models of anisotropic pickup ions and the data on spectra, variations, and proton-He(+) correlation provided by AMPTE, Ulysses, and our instrument on SOHO. We will model the time-dependent pickup ion density resulting from finite periods of radial magnetic field. We will also incorporate the effects of a large mean free path into our analysis of the He(+) focusing cone, leading to more accurate parameter values for the interstellar helium gas. This progress report also includes a discussion of our Space Physics Educational Outreach activities in the past year and plans for the next year.

  2. Electrical studies on silver based fast ion conducting glassy materials

    SciTech Connect

    Rao, B. Appa Kumar, E. Ramesh Kumari, K. Rajani Bhikshamaiah, G.

    2014-04-24

    Among all the available fast ion conductors, silver based glasses exhibit high conductivity. Further, glasses containing silver iodide enhances fast ion conducting behavior at room temperature. Glasses of various compositions of silver based fast ion conductors in the AgI−Ag{sub 2}O−[(1−x)B{sub 2}O{sub 3}−xTeO{sub 2}] (x=0 to1 mol% in steps of 0.2) glassy system have been prepared by melt quenching method. The glassy nature of the compounds has been confirmed by X-ray diffraction. The electrical conductivity (AC) measurements have been carried out in the frequency range of 1 KHz–3MHz by Impedance Analyzer in the temperature range 303–423K. The DC conductivity measurements were also carried out in the temperature range 300–523K. From both AC and DC conductivity studies, it is found that the conductivity increases and activation energy decreases with increasing the concentration of TeO{sub 2} as well as with temperature. The conductivity of the present glass system is found to be of the order of 10{sup −2} S/cm at room temperature. The ionic transport number of these glasses is found to be 0.999 indicating that these glasses can be used as electrolyte in batteries.

  3. Studies of Ion Beam Charge Neutralization by Ferroelectric Plasma Sources

    NASA Astrophysics Data System (ADS)

    Stepanov, A.; Gilson, E. P.; Grisham, L.; Davidson, R. C.

    2013-10-01

    Space-charge forces limit the possible transverse compression of high perveance ion beams that are used in ion-beam-driven high energy density physics applications; the minimum radius to which a beam can be focused is an increasing function of perveance. The limit can be overcome if a plasma is introduced in the beam path between the focusing element and the target in order to neutralize the space charge of the beam. This concept has been implemented on the Neutralized Drift Compression eXperiment (NDCX) at LBNL using Ferroelectric Plasma Sources (FEPS). In our experiment at PPPL, we propagate a perveance-dominated ion beam through a FEPS to study the effect of the neutralizing plasma on the beam envelope and its evolution in time. A 30-60 keV space-charge-dominated Argon beam is focused with an Einzel lens into a FEPS located at the beam waist. The beam is intercepted downstream from the FEPS by a movable Faraday cup that provides time-resolved 2D current density profiles of the beam spot on target. We report results on: (a) dependence of charge neutralization on FEPS plasma density; (b) effects on beam emittance, and (c) time evolution of the beam envelope after the FEPS pulse. Research supported by the U.S. Department of Energy.

  4. Studies of Interstellar Pickup Ions in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Isenberg, Philip A.; Lee, Martin A.; Mobius, Eberhard

    1996-11-01

    The work under this grant involves studies of the interaction of interstellar pickup ions with the solar wind, with the goal of a comprehensive model of the particle distributions and wave intensities to be expected throughout the heliosphere, as well as the interactions of those distributions with the solar wind termination shock. In the past year, we have completed a number of projects, including observations and modeling of the effects of a large scattering mean free path on the pickup He(+) seen at AMPTE, an analytical model of anisotropic pickup tons in a steady radial magnetic field, and a derivation of a reduced solar wind Mach number due to increased estimates on the inflowing hydrogen density allowing for a weak termination shock. In the next year, we plan to investigate in more detail the correspondence between our models of anisotropic pickup ions and the data on spectra, variations, and proton-He(+) correlation provided by AMPTE, Ulysses, and our instrument on SOHO. We will model the time-dependent pickup ion density resulting from finite periods of radial magnetic field. We will also incorporate the effects of a large mean free path into our analysis of the He(+) focusing cone, leading to more accurate parameter values for the interstellar helium gas. This progress report also includes a discussion of our Space Physics Educational Outreach activities in the past year and plans for the next year.

  5. Design studies for the next generation electron ion colliders

    NASA Astrophysics Data System (ADS)

    Sayed, Hisham Kamal; Bogacz, S. A.; Krafft, G.

    2014-04-01

    The next generation Electron Ion Collider (EIC) at Thomas Jefferson National Accelerator Facility (JLAB) utilizes a figure-8 shaped ion and electron rings. EIC has the ability to preserve the ion polarization during acceleration, where the electron ring matches in footprint with a figure-8 ion ring. The electron ring is designed to deliver a highly polarized high luminous electron beam at interaction point (IP). The main challenges of the electron ring design are the chromaticity compensation and maintaining high beam polarization of 70% at all energies 3-11 GeV without introducing transverse orbital coupling before the IP. The very demanding detector design limits the minimum distance between the final focus quadrupole and the interaction point to 3.5 m which results in a large β function inside the final focus quadrupoles leading to increased beam chromaticity. In this paper, we present a novel chromaticity compensation scheme that mitigates IP chromaticity by a compact chromaticity compensation section with multipole magnet components. In addition, a set of spin rotators are utilized to manipulate the polarization vector of the electron beam in order to preserve the beam polarization. The spin rotator solenoids introduce undesired coupling between the horizontal and vertical betatron motion of the beam. We introduce a compact and modular orbit decoupling insert that can fit in the limited space of the straight section in the figure-8 ring. We show a numerical study of the figure-8 ring design with the compact straight section, which includes the interaction region, chromaticity compensation section, and the spin rotators, the figure-8 design performance is evaluated with particle tracking.

  6. Design studies for the next generation electron ion colliders

    SciTech Connect

    Sayed, Hisham Kamal; Bogacz, Slawomir A.; Krafft, Geoffrey A.

    2014-04-01

    The next generation Electron Ion Collider (EIC) at Thomas Jefferson National Accelerator Facility (JLAB) utilizes a figure-8 shaped ion and electron rings. EIC has the ability to preserve the ion polarization during acceleration, where the electron ring matches in footprint with a figure-8 ion ring. The electron ring is designed to deliver a highly polarized high luminous electron beam at interaction point (IP). The main challenges of the electron ring design are the chromaticity compensation and maintaining high beam polarization of 70% at all energies 3–11 GeV without introducing transverse orbital coupling before the IP. The very demanding detector design limits the minimum distance between the final focus quadrupole and the interaction point to 3.5 m which results in a large β function inside the final focus quadrupoles leading to increased beam chromaticity. In this paper, we present a novel chromaticity compensation scheme that mitigates IP chromaticity by a compact chromaticity compensation section with multipole magnet components. In addition, a set of spin rotators are utilized to manipulate the polarization vector of the electron beam in order to preserve the beam polarization. The spin rotator solenoids introduce undesired coupling between the horizontal and vertical betatron motion of the beam. We introduce a compact and modular orbit decoupling insert that can fit in the limited space of the straight section in the figure-8 ring. We show a numerical study of the figure-8 ring design with the compact straight section, which includes the interaction region, chromaticity compensation section, and the spin rotators, the figure-8 design performance is evaluated with particle tracking.

  7. Predicting the number and sizes of IBD regions among family members and evaluating the family size requirement for linkage studies.

    PubMed

    Yang, Wanling; Wang, Zhanyong; Wang, Lusheng; Sham, Pak-Chung; Huang, Peng; Lau, Yu Lung

    2008-12-01

    With genotyping of high-density single nucleotide polymorphisms (SNPs) replacing that of microsatellite markers in linkage studies, it becomes possible to accurately determine the genomic regions shared identity by descent (IBD) by family members. In addition to evaluating the likelihood of linkage for a region with the underlining disease (the LOD score approach), an appropriate question to ask is what would be the expected number and sizes of IBD regions among the affecteds, as there could be more than one region reaching the maximum achievable LOD score for a given family. Here, we introduce a computer program to allow the prediction of the total number of IBD regions among family members and their sizes. Reversely, it can be used to predict the portion of the genome that can be excluded from consideration according to the family size and user-defined inheritance mode and penetrance. Such information has implications on the feasibility of conducting linkage analysis on a given family of certain size and structure or on a few small families when interfamily homogeneity can be assumed. It can also help determine the most relevant members to be genotyped for such a study. Simulation results showed that the IBD regions containing true mutations are usually larger than regions IBD due to random chance. We have made use of this feature in our program to allow evaluation of the identified IBD regions based on Bayesian probability calculation and simulation results.

  8. Copper-ion-assisted growth of gold nanorods in seed-mediated growth: significant narrowing of size distribution via tailoring reactivity of seeds.

    PubMed

    Wen, Tao; Hu, Zhijian; Liu, Wenqi; Zhang, Hui; Hou, Shuai; Hu, Xiaona; Wu, Xiaochun

    2012-12-18

    In the well-developed seed-mediated growth of gold nanorods (GNRs), adding the proper amount of Cu(2+) ions in the growth solution leads to significant narrowing in the size distribution of the resultant GNRs, especially for those with shorter aspect ratios (corresponding longitudinal surface plasmon resonance (LSPR) peaks shorter than 750 nm). Cu(2+) ions were found to be able to catalyze the oxidative etching of gold seeds by oxygen, thus mediating subsequent growth kinetics of the GNRs. At proper Cu(2+) concentrations, the size distribution of the original seeds is greatly narrowed via oxidative etching. The etched seeds are highly reactive and grow quickly into desired GNRs with significantly improved size distribution. A similar mechanism can be employed to tune the end cap of the GNRs. Except for copper ions, no observable catalytic effect is observed from other cations presumably due to their lower affinity to oxygen. Considering the widespread use of seed-mediated growth in the morphology-controlled synthesis of noble metal nanostructures, the tailoring in seed reactivity we presented herein could be extended to other systems. PMID:23173599

  9. Ion-ion and ion-solvent interactions in lithium imidazolide electrolytes studied by Raman spectroscopy and DFT models.

    PubMed

    Scheers, Johan; Niedzicki, Leszek; Zukowska, Grażyna Z; Johansson, Patrik; Wieczorek, Władysław; Jacobsson, Per

    2011-06-21

    Molecular level interactions are of crucial importance for the transport properties and overall performance of ion conducting electrolytes. In this work we explore ion-ion and ion-solvent interactions in liquid and solid polymer electrolytes of lithium 4,5-dicyano-(2-trifluoromethyl)imidazolide (LiTDI)-a promising salt for lithium battery applications-using Raman spectroscopy and density functional theory calculations. High concentrations of ion associates are found in LiTDI:acetonitrile electrolytes, the vibrational signatures of which are transferable to PEO-based LiTDI electrolytes. The origins of the spectroscopic changes are interpreted by comparing experimental spectra with simulated Raman spectra of model structures. Simple ion pair models in vacuum identify the imidazole nitrogen atom of the TDI anion to be the most important coordination site for Li(+), however, including implicit or explicit solvent effects lead to qualitative changes in the coordination geometry and improved correlation of experimental and simulated Raman spectra. To model larger aggregates, solvent effects are found to be crucial, and we finally suggest possible triplet and dimer ionic structures in the investigated electrolytes. In addition, the effects of introducing water into the electrolytes-via a hydrate form of LiTDI-are discussed.

  10. Ion beam technology applications study. [ion impact, implantation, and surface finishing

    NASA Technical Reports Server (NTRS)

    Sellen, J. M., Jr.; Zafran, S.; Komatsu, G. K.

    1978-01-01

    Specific perceptions and possible ion beam technology applications were obtained as a result of a literature search and contact interviews with various institutions and individuals which took place over a 5-month period. The use of broad beam electron bombardment ion sources is assessed for materials deposition, removal, and alteration. Special techniques examined include: (1) cleaning, cutting, and texturing for surface treatment; (2) crosslinking of polymers, stress relief in deposited layers, and the creation of defect states in crystalline material by ion impact; and (3) ion implantation during epitaxial growth and the deposition of neutral materials sputtered by the ion beam. The aspects, advantages, and disadvantages of ion beam technology and the competitive role of alternative technologies are discussed.

  11. Felion: a Cryogenic Ion Trap Apparatus for Spectroscopic Studies with Felix

    NASA Astrophysics Data System (ADS)

    Brunken, S.; Kluge, L.; Fanghanel, S.; Potapov, A.; Asvany, O.; Schlemmer, S.; Oomens, J.; Redlich, B.; Stoffels, A.

    2013-06-01

    The combination of ion trapping techniques with sensitive action spectroscopy schemes has been developed in recent years as a powerful tool to obtain spectra of gas-phase molecular ions from the UV to the (F)IR spectral regions. Here we report on the status of a specifically designed, dedicated cryogenic 22-pole ion trap apparatus (FELion), developed and built in Cologne, Germany, and intended to be installed permanently at the "Free-Electron Lasers for Infrared eXperiments" (FELIX) facility in Nijmegen, the Netherlands. This instrument will allow to record gas-phase IR and FIR spectra of mass-selected, internally cold molecular ions at temperatures in the range 4-300 K. By the use of diverse ionization methods, e.g. electron impact and electrospray ionization, a multitude of molecular ions can be generated and stored in the trap, including astrophysically relevant species ranging in size from the three-atomic H_3^+ up to large polycyclic aromatic hydrocarbon (PAH) ions, but also biomolecular ions like amino acids, peptides, or nucleobases. In combination with the powerful (F)IR radiation of the free electron lasers FELIX-1 and -2 (60-2500 cm^{-1}) and FLARE (6-100 cm^{-1}) at the FELIX facility, a variety of action spectroscopy schemes can be employed to study the ro-vibrational spectra of the stored ions, such as IR multiphoton dissociation, (F)IR/UV double resonance spectroscopy, or the method of laser induced reactions (LIR). In this talk we will give a detailed account of the experimental setup and present the first results obtained with the new apparatus. e.g., S. Schlemmer, E. Lescop, J. von Richthofen, D. Gerlich, and M. A. Smith, J. Chem. Phys. 117, 2068 (2002) J. Oomens, B. G. Sartakov, G. Meijer, and G. van Helden, Int. J. Mass Spectrom. 254, 1 (2006) T. R. Rizzo, J. A. Stearns, and O. V. Boyarkin, International Reviews in Physical Chemistry 28, 481 (2009) FLARE: Free-electron Laser for Advanced spectroscopy and high-Resolution Experiments

  12. Studies of transition states and radicals by negative ion photodetachment

    SciTech Connect

    Metz, R.B.

    1991-12-01

    Negative ion photodetachment is a versatile tool for the production and study of transient neutral species such as reaction intermediates and free radicals. Photodetachment of the stable XHY{sup {minus}} anion provides a direct spectroscopic probe of the transition state region of the potential energy surface for the neutral hydrogen transfer reaction X + HY {yields} XH + Y, where X and Y are halogen atoms. The technique is especially sensitive to resonances, which occur at a specific energy, but the spectra also show features due to direct scattering. We have used collinear adiabatic simulations of the photoelectron spectra to evaluate trail potential energy surfaces for the biomolecular reactions and have extended the adiabatic approach to three dimensions and used it to evaluate empirical potential energy surfaces for the I + Hl and Br + HI reactions. In addition, we have derived an empirical, collinear potential energy surface for the Br + HBr reaction that reproduces our experimental results and have extended this surface to three dimensions. Photodetachment of a negative ion can be also used to study neutral free radicals. We have studied the vibrational and electronic spectroscopy of CH{sub 2}NO{sub 2} by photoelectron spectroscopy of CH{sub 2}NO{sub 2}{sup {minus}}, determining the electron affinity of CH{sub 2}NO{sub 2}, gaining insight on the bonding of the {sup 2}B{sub 1} ground state and observing the {sup 2}A{sub 2} excited state for the first time. Negative ion photodetachment also provides a novel and versatile source of mass-selected, jet-cooled free radicals. We have studied the photodissociation of CH{sub 2}NO{sub 2} at 270, 235, and 208 nm, obtaining information on the dissociation products by measuring the kinetic energy release in the photodissociation.

  13. Plasma desorption mass spectrometry in studies of formation and sputtering of fullerenes by MeV atomic ions

    NASA Astrophysics Data System (ADS)

    Bitensky, I.; Brinkmalm, G.; Demirev, P.; Eriksson, J.; H»Kansson, P.; Papaléo, R.; Sundqvist, B. U. R.; Zubarev, R.

    1994-10-01

    An account is presented on plasma desorption mass spectrometry (PDMS) studies of different carbon-containing organic solids utilizing megaelectronvolt (MeV) atomic ions from the Uppsvala EN-tandem accelerator. Positive ions of even-numbered carbon clusters (C+n, n = 40 to> 200) are ejected as a result of the interaction of the fast MeV ions with the target. The distribution of cluster sizes suggests that stable, closed carbon-cage structures -- fullerenes - are formed. Among the investigated materials that produce carbon clusters are poly(vinylidenefluoride) and fluorinated fullerenes -- C60F2m. For comparison purposes data from C60 targets have been also collected and analyzed. PDMS has been used for the in situ assessment of the damaging of C60 films by MeV heavy ions. Results on delayed electron emission from C-60 sputtered by MeV ions from C60 fullerene targets are also presented. A model of fullerene formation as a result of MeV ion interactions with the organic solid, including the yield dependence on primary ion charge state, is summarized. Both the data and the model suggest that fullerenes are formed as a result of a single primary ion impact and that they are ejected from an axially expanding infratrack plasma region. Results on different types of coalescence reactions in synthetic C60 fullerene targets and in blends of pure (synthetic) C60 with polystyrene leading to ejection of higher mass positive fullerene ions (C+k, k from 60 to more than 200) are also reported. The coalescence reactions are induced by the interaction of a single MeV ion with the solid. We argue that our data contribute to elucidating some general patterns of the fullerene formation mechanism.

  14. Hydration of magnesia cubes: a helium ion microscopy study

    PubMed Central

    Schneider, Johannes; Bourret, Gilles R

    2016-01-01

    Summary Physisorbed water originating from exposure to the ambient can have a strong impact on the structure and chemistry of oxide nanomaterials. The effect can be particularly pronounced when these oxides are in physical contact with a solid substrate such as the ones used for immobilization to perform electron or ion microscopy imaging. We used helium ion microscopy (HIM) and investigated morphological changes of vapor-phase-grown MgO cubes after vacuum annealing and pressing into foils of soft and high purity indium. The indium foils were either used as obtained or, for reference, subjected to vacuum drying. After four days of storage in the vacuum chamber of the microscope and at a base pressure of p < 10−7 mbar, we observed on these cubic particles the attack of residual physisorbed water molecules from the indium substrate. As a result, thin magnesium hydroxide layers spontaneously grew, giving rise to characteristic volume expansion effects, which depended on the size of the particles. Rounding of the originally sharp cube edges leads to a significant loss of the morphological definition specific to the MgO cubes. Comparison of different regions within one sample before and after exposure to liquid water reveals different transformation processes, such as the formation of Mg(OH)2 shells that act as diffusion barriers for MgO dissolution or the evolution of brucite nanosheets organized in characteristic flower-like microstructures. The findings underline the significant metastability of nanomaterials under both ambient and high-vacuum conditions and show the dramatic effect of ubiquitous water films during storage and characterization of oxide nanomaterials. PMID:27335725

  15. Hydration of magnesia cubes: a helium ion microscopy study.

    PubMed

    Schwaiger, Ruth; Schneider, Johannes; Bourret, Gilles R; Diwald, Oliver

    2016-01-01

    Physisorbed water originating from exposure to the ambient can have a strong impact on the structure and chemistry of oxide nanomaterials. The effect can be particularly pronounced when these oxides are in physical contact with a solid substrate such as the ones used for immobilization to perform electron or ion microscopy imaging. We used helium ion microscopy (HIM) and investigated morphological changes of vapor-phase-grown MgO cubes after vacuum annealing and pressing into foils of soft and high purity indium. The indium foils were either used as obtained or, for reference, subjected to vacuum drying. After four days of storage in the vacuum chamber of the microscope and at a base pressure of p < 10(-7) mbar, we observed on these cubic particles the attack of residual physisorbed water molecules from the indium substrate. As a result, thin magnesium hydroxide layers spontaneously grew, giving rise to characteristic volume expansion effects, which depended on the size of the particles. Rounding of the originally sharp cube edges leads to a significant loss of the morphological definition specific to the MgO cubes. Comparison of different regions within one sample before and after exposure to liquid water reveals different transformation processes, such as the formation of Mg(OH)2 shells that act as diffusion barriers for MgO dissolution or the evolution of brucite nanosheets organized in characteristic flower-like microstructures. The findings underline the significant metastability of nanomaterials under both ambient and high-vacuum conditions and show the dramatic effect of ubiquitous water films during storage and characterization of oxide nanomaterials. PMID:27335725

  16. Equilibrium studies of copper ion adsorption onto palm kernel fibre.

    PubMed

    Ofomaja, Augustine E

    2010-07-01

    The equilibrium sorption of copper ions from aqueous solution using a new adsorbent, palm kernel fibre, has been studied. Palm kernel fibre is obtained in large amounts as a waste product of palm oil production. Batch equilibrium studies were carried out and system variables such as solution pH, sorbent dose, and sorption temperature were varied. The equilibrium sorption data was then analyzed using the Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherms. The fit of these isotherm models to the equilibrium sorption data was determined, using the linear coefficient of determination, r(2), and the non-linear Chi-square, chi(2) error analysis. The results revealed that sorption was pH dependent and increased with increasing solution pH above the pH(PZC) of the palm kernel fibre with an optimum dose of 10g/dm(3). The equilibrium data were found to fit the Langmuir isotherm model best, with a monolayer capacity of 3.17 x 10(-4)mol/g at 339K. The sorption equilibrium constant, K(a), increased with increasing temperature, indicating that bond strength between sorbate and sorbent increased with temperature and sorption was endothermic. This was confirmed by the increase in the values of the Temkin isotherm constant, B(1), with increasing temperature. The Dubinin-Radushkevich (D-R) isotherm parameter, free energy, E, was in the range of 15.7-16.7kJ/mol suggesting that the sorption mechanism was ion exchange. Desorption studies showed that a high percentage of the copper was desorbed from the adsorbent using acid solutions (HCl, HNO(3) and CH(3)COOH) and the desorption percentage increased with acid concentration. The thermodynamics of the copper ions/palm kernel fibre system indicate that the process is spontaneous and endothermic. PMID:20346574

  17. Equilibrium studies of copper ion adsorption onto palm kernel fibre.

    PubMed

    Ofomaja, Augustine E

    2010-07-01

    The equilibrium sorption of copper ions from aqueous solution using a new adsorbent, palm kernel fibre, has been studied. Palm kernel fibre is obtained in large amounts as a waste product of palm oil production. Batch equilibrium studies were carried out and system variables such as solution pH, sorbent dose, and sorption temperature were varied. The equilibrium sorption data was then analyzed using the Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherms. The fit of these isotherm models to the equilibrium sorption data was determined, using the linear coefficient of determination, r(2), and the non-linear Chi-square, chi(2) error analysis. The results revealed that sorption was pH dependent and increased with increasing solution pH above the pH(PZC) of the palm kernel fibre with an optimum dose of 10g/dm(3). The equilibrium data were found to fit the Langmuir isotherm model best, with a monolayer capacity of 3.17 x 10(-4)mol/g at 339K. The sorption equilibrium constant, K(a), increased with increasing temperature, indicating that bond strength between sorbate and sorbent increased with temperature and sorption was endothermic. This was confirmed by the increase in the values of the Temkin isotherm constant, B(1), with increasing temperature. The Dubinin-Radushkevich (D-R) isotherm parameter, free energy, E, was in the range of 15.7-16.7kJ/mol suggesting that the sorption mechanism was ion exchange. Desorption studies showed that a high percentage of the copper was desorbed from the adsorbent using acid solutions (HCl, HNO(3) and CH(3)COOH) and the desorption percentage increased with acid concentration. The thermodynamics of the copper ions/palm kernel fibre system indicate that the process is spontaneous and endothermic.

  18. External dacryocystorhinostomy. A prospective study comparing the size of the operative and healed ostium.

    PubMed

    Bumsted, R M; Linberg, J V; Anderson, R L; Barreras, R

    1982-07-01

    This study compares the size of the operative anastomosis with the size of the healed intranasal ostium resulting from 22 external dacryocystorhinostomies. The area of the healed intranasal ostium was approximately 2% of the area of the surgical anastomosis. No correlation was found between the size of the surgical anastomosis and the size of the healed ostium. In all cases, excellent functional results were obtained, regardless of the size of the healed ostium. This study suggests the size of the surgical anastomosis is not directly related to the success of the procedure, although it must be large enough to technically perform the procedure.

  19. Design and construction of a imaging instrument for studying ion emission from pure ion emitters

    SciTech Connect

    Olson, J.E.

    1993-09-01

    The development of new ion sources is important in the area of surface analysis to make it easier to perform more sensitive and accurate analyses. In surface analysis a primary ion beam composed of a single species can help when predicting and interpreting the results. Therefore, much interest and effort has been focused on producing pure ion emitters. An instrument has been designed and constructed to view the current densities of the ions being emitted from pure ion emitters. The instrument electrostatically accelerates and focuses the ion beam onto a microchannel plate detector equipped with a phosphor screen for viewing the images. These images are used to identify areas of enhanced ion emission. Once these areas are identified, the investigator can use other instruments to analyze them, and hopefully develop a better understanding of the chemistry and physics involved in the ion emission process. A computer based control system has been integrated into the system to simplify the operation of the instrument and provide safety features to protect the hardware from damage. A closed-circuit video camera system is used to allow the images to be remotely viewed during imaging procedures. Experiments show that the instrument has a lower detection limit of 7.45 {times} 10{sup 3} ions/sec/mm{sup 2} and a spatial resolution of approximately 3 {minus} 4 {mu}m. Results from imaging cesium zeolite and perrhenate ion sources indicate that the ions are primarily being emitted from the surface of the sources and not from the interfacial region between the substrate and the emitter material.

  20. Formation of gas-phase peptide ions and their dissociation in MALDI: insights from kinetic and ion yield studies.

    PubMed

    Moon, Jeong Hee; Yoon, Sohee; Bae, Yong Jin; Kim, Myung Soo

    2015-01-01

    Insights on mechanisms for the generation of gas-phase peptide ions and their dissociation in matrix-assisted laser desorption ionization (MALDI) gained from the kinetic and ion yield studies are presented. Even though the time-resolved photodissociation technique was initially used to determine the dissociation kinetics of peptide ions and their effective temperature, it was replaced by a simpler method utilizing dissociation yields from in-source decay (ISD) and post-source decay (PSD). The ion yields for a matrix and a peptide were measured by repeatedly irradiating a region on a sample and collecting ion signals until the sample in the region was completely depleted. Matrix- and peptide-derived gas-phase cations were found to be generated by pre-formed ion emission or by ion-pair emission followed by anion loss, but not by laser-induced ionization. The total number of ions, that is, matrix plus peptide, was found to be equal to the number of ions emitted from a pure matrix. A matrix plume was found to cool as it expanded, from around 800-1,000 K to 400-500 K. Dissociation of peptide ions along b/y channels was found to occur statistically, that is, following RRKM behavior. Small critical energy (E0  = 0.6-0.7 eV) and highly negative critical entropy (ΔS(‡)  = -30 to -25 eu) suggested that the transition structure was stabilized by multiple intramolecular interactions.

  1. Temperature-dependant study of phosphorus ion implantation in germanium

    NASA Astrophysics Data System (ADS)

    Razali, M. A.; Smith, A. J.; Jeynes, C.; Gwilliam, R. M.

    2012-11-01

    We present experimental results on shallow junction formation in germanium by phosphorus ion implantation and standard rapid thermal processing. An attempt is made to improve phosphorus activation by implanting phosphorus at high and low temperature. The focus is on studying the germanium damage and phosphorus activation as a function of implant temperature. Rutherford backscattering spectrometry with channelling and Hall Effect measurements are employed for characterisation of germanium damage and phosphorus activation, respectively. High and low temperature implants were found to be better compared to room temperature implant.

  2. Ion plume/S-band carrier interaction study

    NASA Technical Reports Server (NTRS)

    Stanton, P.

    1981-01-01

    A study was performed to determine the effects of a mercury ion thruster plume on an S-band telecommunication carrier. Experiments were carried out on a 30 cm thruster in a JPL test chamber. Results from simple analytical models were compared with the above measurements and major discrepancies were discovered. Modifications to the electron density model provided a qualitative explanation, but further work is necessary for a quantitative answer. The results indicate the effects of the plume, on S and X Band telecommunications will be minor, with the possible exception of critical angle blockage.

  3. Accelerated simulation study of space charge effects in quadrupole ion traps using GPU techniques.

    PubMed

    Xiong, Xingchuang; Xu, Wei; Fang, Xiang; Deng, Yulin; Ouyang, Zheng

    2012-10-01

    Space charge effects play important roles in the performance of various types of mass analyzers. Simulation of space charge effects is often limited by the computation capability. In this study, we evaluate the method of using graphics processing unit (GPU) to accelerate ion trajectory simulation. Simulation using GPU has been compared with multi-core central processing unit (CPU), and an acceleration of about 390 times have been obtained using a single computer for simulation of up to 10(5) ions in quadrupole ion traps. Characteristics of trapped ions can be investigated at detailed levels within a reasonable simulation time. Space charge effects on the trapping capacities of linear and 3D ion traps, ion cloud shapes, ion motion frequency shift, mass spectrum peak coalescence effects between two ion clouds of close m/z are studied with the ion trajectory simulation using GPU.

  4. Size dependence of cavity volume: a molecular dynamics study.

    PubMed

    Patel, Nisha; Dubins, David N; Pomès, Régis; Chalikian, Tigran V

    2012-02-01

    Partial molar volume, V°, has been used as a tool to sample solute hydration for decades. The efficacy of volumetric investigations of hydration depends on our ability to reliably discriminate between the cavity, V(C), and interaction, V(I), contributions to the partial molar volume. The cavity volume, V(C), consists of the intrinsic volume, V(M), of a solute molecule and the thermal volume, V(T), with the latter representing the volume of the effective void created around the solute. In this work, we use molecular dynamics simulations in conjunction with the Kirkwood-Buff theory to compute the partial molar volumes for organic solutes of varying sizes in water. We perform our computations using the Lennard-Jones and Coulombic pair potentials as well as truncated potentials which contain only the Lennard-Jones but not the Coulombic contribution. The partial molar volume computed with the Lennard-Jones potentials in the absence of the Coulombic term nearly coincides with the cavity volume, V(C). We determine the thermal volume, V(T), for each compound by subtracting its van der Waals volume, V(W), from V(C). Finally, we apply the spherical approximation of solute geometry to evaluate the thickness of the thermal volume, δ. Our results reveal an increase in the thickness of thermal volume, δ, with an increase in the size of the solute. This finding may be related to dewetting of large nonpolar solutes and the concomitant increase in the compressibility of water of hydration. PMID:22133917

  5. Caesium Free Negative Ion Sources for Neutral Beam Injectors: a Study of Negative Ion Production on Graphite Surface in Hydrogen and Deuterium Plasma

    SciTech Connect

    Schiesko, L.; Carrere, M.; Cartry, G.; Layet, J.-M.

    2009-03-12

    Negative ion generation on HOPG graphite surface has been studied in hydrogen and deuterium plasma. We measure Ion Distribution Function (IDF) of negative ions coming from graphite surface bombarded by positive ions in H{sub 2}/D{sub 2} plasmas. We showed that negative ions flux was proportional to positive ion flux and was strongly dependant on impinging energy. IDF study shows two generation mechanisms are involved: sputtering of adsorbed H/D as negative ions and, in a less important way, double electron capture. We compare H{sub 2}/D{sub 2} plasmas, and point out isotopic effect between H{sup -} and D{sup -} production.

  6. Test particle study of minor ions in solar wind turbulence

    NASA Technical Reports Server (NTRS)

    Zurbuchen, Th.; Bochsler, P.; Politano, H.; Pouquet, A.

    1995-01-01

    We perform a parameter study of the temporal evolution of a test particle distribution function in MHD turbulence. The turbulent fields are calculated using a pseudo-spectral method and periodic boundary conditions on a regular grid of 180(exp 3) points, appropriate for incompressible, homogeneous and isotropic turbulence. Initially, the kinetic and the magnetic energy are equal on the average. Both, deterministic and random initial conditions are used, in the former case with zeros of the magnetic field located at grid points, in the latter case located by interpolation between grid points. The evolution of the minor ion distribution function is studied in detail as these turbulent fields evolve, developing strong current and vorticity sheets. Using the full collisionless equation of motion for the test particles, the efficiency of nonlinear interactions can be studied. The results are compared to theoretical predictions and are then discussed in connection with the observations of the dynamical properties of solar wind minor ions derived from in situ observations.

  7. Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    van Pinxteren, D.; Fomba, K. W.; Mertes, S.; Müller, K.; Spindler, G.; Schneider, J.; Lee, T.; Collett, J.; Herrmann, H.

    2015-09-01

    caused by systematic differences and limitations of the approaches (such as outgassing of dissolved gases during residual particle sampling). Scavenging efficiencies (SEs) of aerosol constituents were 0.56-0.94, 0.79-0.99, 0.71-98, and 0.67-0.92 for SO42-, NO3-, NH4+, and DOC, respectively, when calculated as event means with in-cloud data only. SEs estimated using data from an upwind site were substantially different in many cases, revealing the impact of gas-phase uptake (for volatile constituents) and mass losses across Mt. Schmücke likely due to physical processes such as droplet scavenging by trees and/or entrainment. Drop size-resolved cloud water concentrations of major ions SO42-, NO3-, and NH4+ revealed two main profiles: decreasing concentrations with increasing droplet size and "U"-shapes. In contrast, profiles of typical coarse particle mode minor ions were often increasing with increasing drop size, highlighting the importance of a species' particle concentration size distribution for the development of size-resolved solute concentration patterns. Concentration differences between droplet size classes were typically < 2 for major ions from the 3-stage collector and somewhat more pronounced from the 5-stage collector, while they were much larger for minor ions. Due to a better separation of droplet populations, the 5-stage collector was capable of resolving some features of solute size dependencies not seen in the 3-stage data, especially sharp concentration increases (up to a factor of 5-10) in the smallest droplets for many solutes.

  8. Gyrokinetic study of the impact of the electron to ion heating ratio on the turbulent diffusion of highly charged impurities

    SciTech Connect

    Angioni, C.

    2015-10-15

    A gyrokinetic study based on numerical and analytical calculations is presented, which computes the dependence of the turbulent diffusion of highly charged impurities on the ratio of the electron to the ion heat flux of the plasma. Nonlinear simulations show that the size of the turbulent diffusion of heavy impurities can vary by one order of magnitude with fixed total heat flux and is an extremely sensitive function of the electron to ion heat flux ratio. Numerical linear calculations are found to reproduce the nonlinear results. Thereby, a quasi-linear analytical approach is used to explain the origin of this dependence.

  9. Water-soluble ions in atmospheric aerosols measured in five sites in the Yangtze River Delta, China: Size-fractionated, seasonal variations and sources

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; Zhu, Bin; Shen, Lijuan; Xu, Honghui; An, Junlin; Xue, Guoqiang; Cao, Jinfei

    2015-12-01

    In order to investigate the regional variations of water-soluble ions (WSIs), size-resolved measurement of aerosol particles and WSIs was conducted by using Anderson Sampler and Ion Chromatography at five sites (Nanjing, Suzhou, Lin'an, Hangzhou and Ningbo) in the Yangtze River Delta (YRD) region, China in the Autumn of 2012 and Winter, Spring and Summer of 2013. WSIs exhibited obvious seasonal variations due to the monsoon conversion, with the highest level in winter and lowest level in summer. The aerosol mass concentrations and WSIs in different size segments varied with four seasons. The dominant ions concentrations in PM2.1 ranked in the order of SO42- > NO3- > NH4+ > Cl- > K+ > Ca2+, and the dominant ions concentrations in PM2.1-10 ranked in the order of Ca2+ > NO3- > SO42- > Cl- > NH4+ > Na+. The size spectra of mass and WSIs concentration peaked mostly at 0.43-0.65 μm in four seasons. The concentration discrepancies of WSIs in different cities were caused by the geographic locations and emission source. It's belonged to ammonium-rich distribution in PM2.1 and ammonium-poor distribution in PM2.1-10 in the YRD region. The impact of temperature on mass concentrations of NO3- and NH4+ in PM2.1 were stronger than those in PM2.1-10. PCA analysis shows that the sources of WSIs dominant by anthropogenic sources, soil particles or falling dust, sea salt and burning process.

  10. Determination of free and total sulfate and phosphate in glycosaminoglycans by column-switching high-performance size-exclusion and ion chromatography and single-column ion chromatography.

    PubMed

    Ruiz-Calero, V; Puignou, L; Diez, M; Galceran, M T

    2001-02-01

    Analytical procedures for the determination of free and total sulfate and phosphate in glycosaminoglycans by high-performance liquid chromatography were studied. A column-switching method coupling high-performance size-exclusion chromatography (HPSEC) and ion chromatography (IC) is proposed for the determination of free anions. Good run-to-run and day-to-day precision values (RSD) of < 4.7% were obtained for both anions. Total anion contents were determined after wet acid hydrolysis with nitric acid-hydrogen peroxide (5 + 1) by single-column IC and ICP-AES elemental analysis in order to validate the results. Recoveries ranging from 94.6 to 99.0% for sulfate and from 80.8 to 94.0% for phosphate were obtained. Both HPSEC-IC and single-column IC methods were applied to the analysis of a low molecular mass heparin, a non-fractionated heparin and a chondroitin 4-sulfate. From the free and total sulfate determinations, the content of linked sulfur was calculated and ranged from 5.1 to 12.2% m/m. PMID:11235098

  11. Electrochemical and thermal studies of lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Lu, Wenquan

    The structural, electrochemical, and thermal characteristics of carbonaceous anodes and LiNi0.8Co0.2O2 cathode in Li-ion cells were investigated using various electrochemical and calorimetric techniques. The electrode-electrolyte interface was investigated for various carbonaceous materials such as graphite with different shapes, surface modified graphite with copper, and novel carbon material derived from sepiolite template. The structural and morphological properties were determined using XRD, TGA, SEM, BET techniques. The electrochemical characteristics were studied using conventional electrochemical techniques such as galvanostatic charge/discharge cycling, cyclic voltammetry, and impedance (AC and DC) methods. It was observed that the electrochemical active surface area instead of the BET area plays a critical role in the irreversible capacity loss associated with the carbonaceous anodes. It was also found that the exfoliation of carbon anodes especially in PC based electrolyte could be significantly reduced by protective copper coating of the natural graphite. LiNi0.8Co0.2O2 cathode material was found to possess high energy density and excellent cycling characteristics. The structural and electrochemical properties of LiNi0.8Co 0.2O2 synthesized by sol-gel and solid-state methods were studied. Results of the AC impedance spectroscopy carried out on LiNi 0.8Co0.2O2 cathodes revealed that the charge transfer resistance is a function of the state of charge. The solid state Li + diffusion was calculated to be around 10-13 cm2/s in the oxide particle by Warburg impedance method. In addition, the cell fabricated with LiNi0.8Co0.2O 2 cathode showed excellent energy and power performance under static and dynamic load conditions that prevail in Electric and Hybrid Vehicles. Thermal properties of the LiNi0.8Co0.2O2 cathode, carbonaceous anodes, and Li-ion cells fabricated with these electrodes were also investigated using isothermal microcalorimetry (IMC), differential

  12. Detailed studies of full-size ATLAS12 sensors

    NASA Astrophysics Data System (ADS)

    Hommels, L. B. A.; Allport, P. P.; Baca, M.; Broughton, J.; Chisholm, A.; Nikolopoulos, K.; Pyatt, S.; Thomas, J. P.; Wilson, J. A.; Kierstead, J.; Kuczewski, P.; Lynn, D.; Arratia, M.; Klein, C. T.; Ullan, M.; Fleta, C.; Fernandez-Tejero, J.; Bloch, I.; Gregor, I. M.; Lohwasser, K.; Poley, L.; Tackmann, K.; Trofimov, A.; Yildirim, E.; Hauser, M.; Jakobs, K.; Kuehn, S.; Mahboubi, K.; Mori, R.; Parzefall, U.; Clark, A.; Ferrere, D.; Gonzalez Sevilla, S.; Ashby, J.; Blue, A.; Bates, R.; Buttar, C.; Doherty, F.; McMullen, T.; McEwan, F.; O`Shea, V.; Kamada, S.; Yamamura, K.; Ikegami, Y.; Nakamura, K.; Takubo, Y.; Unno, Y.; Takashima, R.; Chilingarov, A.; Fox, H.; Affolder, A. A.; Casse, G.; Dervan, P.; Forshaw, D.; Greenall, A.; Wonsak, S.; Wormald, M.; Cindro, V.; Kramberger, G.; Mandić, I.; Mikuž, M.; Gorelov, I.; Hoeferkamp, M.; Palni, P.; Seidel, S.; Taylor, A.; Toms, K.; Wang, R.; Hessey, N. P.; Valencic, N.; Hanagaki, K.; Dolezal, Z.; Kodys, P.; Bohm, J.; Stastny, J.; Mikestikova, M.; Bevan, A.; Beck, G.; Milke, C.; Domingo, M.; Fadeyev, V.; Galloway, Z.; Hibbard-Lubow, D.; Liang, Z.; Sadrozinski, H. F.-W.; Seiden, A.; To, K.; French, R.; Hodgson, P.; Marin-Reyes, H.; Parker, K.; Jinnouchi, O.; Hara, K.; Sato, K.; Sato, K.; Hagihara, M.; Iwabuchi, S.; Bernabeu, J.; Civera, J. V.; Garcia, C.; Lacasta, C.; Marti i Garcia, S.; Rodriguez, D.; Santoyo, D.; Solaz, C.; Soldevila, U.

    2016-09-01

    The "ATLAS ITk Strip Sensor Collaboration" R&D group has developed a second iteration of single-sided n+-in-p type micro-strip sensors for use in the tracker upgrade of the ATLAS experiment at the High-Luminosity (HL) LHC. The full size sensors measure approximately 97 × 97mm2 and are designed for tolerance against the 1.1 ×1015neq /cm2 fluence expected at the HL-LHC. Each sensor has 4 columns of 1280 individual 23.9 mm long channels, arranged at 74.5 μm pitch. Four batches comprising 120 sensors produced by Hamamatsu Photonics were evaluated for their mechanical, and electrical bulk and strip characteristics. Optical microscopy measurements were performed to obtain the sensor surface profile. Leakage current and bulk capacitance properties were measured for each individual sensor. For sample strips across the sensor batches, the inter-strip capacitance and resistance as well as properties of the punch-through protection structure were measured. A multi-channel probecard was used to measure leakage current, coupling capacitance and bias resistance for each individual channel of 100 sensors in three batches. The compiled results for 120 unirradiated sensors are presented in this paper, including summary results for almost 500,000 strips probed. Results on the reverse bias voltage dependence of various parameters and frequency dependence of tested capacitances are included for validation of the experimental methods used. Comparing results with specified values, almost all sensors fall well within specification.

  13. Computational studies of ion pairing. 8. Ion pairing of tetraalkylammonium ions to nitrosobenzene and benzaldehyde redox species. A general binding motif for the interaction of tetraalkylammonium ions with benzenoid species.

    PubMed

    Fry, Albert J

    2013-06-01

    Very little data is available on the detailed structures of ion pairs in solution, since few general experimental methods are available for obtaining such information. For this reason, computational methods have emerged as the method of choice for determining the structures of organic ion pairs in solution. The present study examines the ion pairs between a series of tetraalkylammonium ions and several redox forms of nitrosobenzene and a series of substituted benzaldehydes. The structures, though previously unexpected, are chemically reasonable and fit into a previous pattern of ion pairing described in previous publications in this series. To date in these studies, a total of 73 ion pairs and related species have in fact been identified having exactly the same unusual orientation of the tetraalkylammonium component with respect to the donor species. The results are pertinent to topics of general current interest, including self-assembly, molecular recognition, and supramolecular assembly.

  14. The sound of size: crossmodal binding in pitch-size synesthesia: a combined TMS, EEG and psychophysics study.

    PubMed

    Bien, Nina; ten Oever, Sanne; Goebel, Rainer; Sack, Alexander T

    2012-01-01

    Crossmodal binding usually relies on bottom-up stimulus characteristics such as spatial and temporal correspondence. However, in case of ambiguity the brain has to decide whether to combine or segregate sensory inputs. We hypothesise that widespread, subtle forms of synesthesia provide crossmodal mapping patterns which underlie and influence multisensory perception. Our aim was to investigate if such a mechanism plays a role in the case of pitch-size stimulus combinations. Using a combination of psychophysics and ERPs, we could show that despite violations of spatial correspondence, the brain specifically integrates certain stimulus combinations which are congruent with respect to our hypothesis of pitch-size synesthesia, thereby impairing performance on an auditory spatial localisation task (Ventriloquist effect). Subsequently, we perturbed this process by functionally disrupting a brain area known for its role in multisensory processes, the right intraparietal sulcus, and observed how the Ventriloquist effect was abolished, thereby increasing behavioural performance. Correlating behavioural, TMS and ERP results, we could retrace the origin of the synesthestic pitch-size mappings to a right intraparietal involvement around 250 ms. The results of this combined psychophysics, TMS and ERP study provide evidence for shifting the current viewpoint on synesthesia more towards synesthesia being at the extremity of a spectrum of normal, adaptive perceptual processes, entailing close interplay between the different sensory systems. Our results support this spectrum view of synesthesia by demonstrating that its neural basis crucially depends on normal multisensory processes.

  15. In situ study of heavy ion induced radiation damage in NF616 (P92) alloy

    NASA Astrophysics Data System (ADS)

    Topbasi, Cem; Motta, Arthur T.; Kirk, Mark A.

    2012-06-01

    NF616 is a nominal 9Cr ferritic-martensitic steel that is amongst the primary candidates for cladding and duct applications in the Sodium-Cooled Fast Reactor, one of the Generation IV nuclear energy systems. In this study, an in situ investigation of the microstructure evolution in NF616 under heavy ion irradiation has been conducted. NF616 was irradiated to 8.4 dpa at 50 K and to 7.6 dpa at 473 K with 1 MeV Kr ions. Nano-sized defects first appeared as white dots in dark-field TEM images and their areal density increased until saturation (˜6 dpa). Dynamic observations at 50 K and 473 K showed appearance and disappearance of TEM-visible defect clusters under irradiation that continued above saturation dose. Quantitative analysis showed no significant change in the average size (˜3-4 nm) and distribution of defect clusters with increasing dose at 50 K and 473 K. These results indicate a cascade-driven process of microstructure evolution under irradiation in these alloys that involves both the formation of TEM-visible defect clusters by various degrees of cascade overlap and cascade induced defect cluster elimination. According to this mechanism, saturation of defect cluster density is reached when the rate of defect cluster formation by overlap is equal to the rate of cluster elimination during irradiation.

  16. Computational studies of transport in ion channels using metadynamics.

    PubMed

    Furini, Simone; Domene, Carmen

    2016-07-01

    Molecular dynamics simulations have played a fundamental role in numerous fields of science by providing insights into the structure and dynamics of complex systems at the atomistic level. However, exhaustive sampling by standard molecular dynamics is in most cases computationally prohibitive, and the time scales accessible remain significantly shorter than many biological processes of interest. In particular, in the study of ion channels, realistic models to describe permeation and gating require accounting for large numbers of particles and accurate interaction potentials, which severely limits the length of the simulations. To overcome such limitations, several advanced methods have been proposed among which is metadynamics. In this algorithm, an external bias potential to accelerate sampling along selected collective variables is introduced. This bias potential discourages visiting regions of the configurational space already explored. In addition, the bias potential provides an estimate of the free energy as a function of the collective variables chosen once the simulation has converged. In this review, recent contributions of metadynamics to the field of ion channels are discussed, including how metadynamics has been used to search for transition states, predict permeation pathways, treat conformational flexibility that underlies the coupling between gating and permeation, or compute free energy of permeation profiles. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov.

  17. Study of negative ion transport phenomena in a plasma source

    NASA Astrophysics Data System (ADS)

    Riz, D.; Paméla, J.

    1996-07-01

    NIETZSCHE (Negative Ions Extraction and Transport ZSimulation Code for HydrogEn species) is a negative ion (NI) transport code developed at Cadarache. This code calculates NI trajectories using a 3D Monte-Carlo technique, taking into account the main destruction processes, as well as elastic collisions (H-/H+) and charge exchanges (H-/H0). It determines the extraction probability of a NI created at a given position. According to the simulations, we have seen that in the case of volume production, only NI produced close to the plasma grid (PG) can be extracted. Concerning the surface production, we have studied how NI produced on the PG and accelerated by the plasma sheath backward into the source could be extracted. We demonstrate that elastic collisions and charge exchanges play an important role, which in some conditions dominates the magnetic filter effect, which acts as a magnetic mirror. NI transport in various conditions will be discussed: volume/surface production, high/low plasmas density, tent filter/transverse filter.

  18. Study on ion formation in electrospray droplet impact secondary ion mass spectrometry.

    PubMed

    Asakawa, Daiki; Fujimaki, Susumu; Hashimoto, Yutaka; Mori, Kunihiko; Hiraoka, Kenzo

    2007-01-01

    A new type of cluster secondary ion mass spectrometry (SIMS), named electrospray droplet impact (EDI), has been developed in our laboratory. In general, rather strong negative ions as well as positive ions can be generated by EDI compared with conventional SIMS. In this work, various aspects of ion formation in EDI are investigated. The Brønsted bases (proton acceptor) and acids (proton donor) mixed in the analyte samples enhanced the signal intensities of deprotonated molecules (negative ions) and protonated molecules (positive ions), respectively, for analytes. This suggests the occurrence of heterogeneous proton transfer reactions (i.e. M + M' --> [M+H](+) + [M'-H](-)) in the shockwave-heated selvedge of the colliding interface between the water droplet and the solid sample deposited on the metal substrate. EDI-SIMS shows a remarkable tolerance to the large excess of salts present in samples. The mechanism for desorption/ionization in EDI is much simpler than those for MALDI and SIMS because only very thin sample layers take part in the shockwave-heated selvedge and complicated higher-order reactions are largely suppressed.

  19. Determination of phytate in high molecular weight, charged organic matrices by two-dimensional size exclusion-ion chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two-dimensional chromatography method for analyzing anionic targets (specifically phytate) in complex matrices is described. Prior to quantification by anion exchange chromatography, the sample matrix was prepared by size exclusion chromatography, which removed the majority of matrix complexities....

  20. Predictions of particle size and lattice diffusion pathway requirements for sodium-ion anodes using eta-Cu6Sn5 thin films as a model system

    SciTech Connect

    Baggetto, Loic; Jumas, Dr. Jean-Claude; Gorka, Joanna; Bridges, Craig A; Veith, Gabriel M

    2013-01-01

    Geometrically well-defined Cu6Sn5 thin films were used as model systems to estimate the diffusion depth and diffusion pathway requirements of Li and Na ions in alloy anodes. eta-Cu6Sn5 anodes have an initial reversible capacity towards Li of 545 mAh g-1 (Li3.96Sn or 19.8 Li/Cu6Sn5) and a very low initial irreversible capacity of 1.6 Li/Cu6Sn5. In contrast, the reaction with Na is limited with a reversible capacity of 160 mAh g-1 compared to the expected 516 mAh g-1. The potential profile is analogous to that of pure Sn with an average potential of 0.3 V. X-ray diffraction and 119Sn-M ssbauer measurements show that this limited capacity is likely resulting from the limited diffusion of Na into the anode particles not the formation of a low Na-content phase. This is substantiated by the analysis of the structure of eta-Cu6Sn5 which revealed zig-zag and tunnel diffusion pathways with spherical voids with a diameter very close to that of Na+. Moreover, our results also indicate that an alloy of eta-Cu6Sn5 should have optimized particle sizes of about 10 nm in diameter to increase the Na-capacity significantly. An alternative system consisting of a mixture of Cu6Sn5 and Sn of nominal composition Cu6Sn10 has been studied as possible Na-ion anode material possessing higher storage capacity than pure Cu6Sn5. Indeed this mixture of phase delivers a larger initial reversible storage capacity up to 400 mAh g-1. Finally, we have evidenced that the presence of Cu in Cu6Sn5 and in Cu6Sn10 suppresses the anomalous electrolyte decomposition normally measured for pure Sn at 1.2 V during discharge.

  1. [Ion specificity during ion exchange equilibrium in natural clinoptilolite].

    PubMed

    He, Yun-Hua; Li, Hang; Liu, Xin-Min; Xiong, Hai-Ling

    2015-03-01

    Zeolites have been widely applied in soil improvement and environment protection. The study on ion specificity during ion exchange equilibrium is of important significance for better use of zeolites. The maximum adsorption capacities of alkali ions during ion exchange equilibrium in the clinoptilolite showed obvious specificity. For alkali metal ions with equivalent valence, the differences in adsorption capacity increased with the decrease of ionic concentration. These results cannot be well explained by the classical theories including coulomb force, ionic size, hydration, dispersion force, classic induction force and surface complexation. We found that the coupling of polarization effects resulted from the quantum fluctuation of diverse alkali metal ions and electric field near the zeolite surface should be the primary reason for specific ion effect during ion exchange in zeolite. The result of this coupling effect was that the difference in the ion dipole moment increased with the increase of surface potential, which further expanded the difference in the adsorption ability between zeolite surface and ions, resulting in different ion exchange adsorption ability at the solid/liquid interface. Due to the high surface charge density of zeolite, ionic size also played an important role in the distribution of ions in the double diffuse layer, which led to an interesting result that distinct differences in exchange adsorption ability of various alkali metal ions were only detected at high surface potential (the absolute value was greater than 0.2 V), which was different from the ion exchange equilibrium result on the surface with low charge density.

  2. Initial Scale Development: Sample Size for Pilot Studies

    ERIC Educational Resources Information Center

    Johanson, George A.; Brooks, Gordon P.

    2010-01-01

    Pilot studies are often recommended by scholars and consultants to address a variety of issues, including preliminary scale or instrument development. Specific concerns such as item difficulty, item discrimination, internal consistency, response rates, and parameter estimation in general are all relevant. Unfortunately, there is little discussion…

  3. Ion-beam depth-profiling studies of leached glasses

    SciTech Connect

    Houser, C.A.; Tsong, I.S.T.; White, W.B.; Wintenberg, A.L.; Miller, P.D.; Moak, C.D.

    1981-01-01

    Ion-beam depth-profiling was carried out on three different glasses leached (or hydrated) in deionized water using /sup 1/H(/sup 19/F,..cap alpha gamma..)/sup 16/O nuclear reaction, secondary ion mass spectrometry (SIMS) and sputter-induced photon spectrometry (SIPS) techniques. The depth-profiles show an interdiffusion mechanism in which the sodium ions in the glass are depleted and replaced by hydrogen (H/sup +/) or hydronium (H/sub 3/O/sup +/) ions from the solution. The leaching behavior does not show significant difference whether the glass surface is fractured or polished. Problems of mobile ion migration caused by ion bombardment and loss of hydrogen during analysis are discussed.

  4. Computational study of ion beam extraction phenomena through multiple apertures

    SciTech Connect

    Hu, Wanpeng; Sang, Chaofeng; Tang, Tengfei; Wang, Dezhen; Li, Ming; Jin, Dazhi; Tan, Xiaohua

    2014-03-15

    The process of ion extraction through multiple apertures is investigated using a two-dimensional particle-in-cell code. We consider apertures with a fixed diameter with a hydrogen plasma background, and the trajectories of electrons, H{sup +} and H{sub 2}{sup +} ions in the self-consistently calculated electric field are traced. The focus of this work is the fundamental physics of the ion extraction, and not particular to a specific device. The computed convergence and divergence of the extracted ion beam are analyzed. We find that the extracted ion flux reaching the extraction electrode is non-uniform, and the peak flux positions change according to operational parameters, and do not necessarily match the positions of the apertures in the y-direction. The profile of the ion flux reaching the electrode is mainly affected by the bias voltage and the distance between grid wall and extraction electrode.

  5. Review of target studies for heavy ion fusion

    SciTech Connect

    Lindl, J.D.; Bangerter, R.D.; Mark, J.W.K.; Pan, Y.L.

    1986-10-24

    We present an updated set of gain curves for radiation driven ion beam targets. The improved target performance calculated with nuclear spin polarized fuel will also be discussed. We discuss the conditions required for efficient conversion to x-rays of ion beam energy. These requirements are compared with those obtained for lasers. Recent results on symmetry requirements for direct drive ion beam targets are presented.

  6. Molecular Dynamical Study on Ion Channeling through Peptide Nanotube

    NASA Astrophysics Data System (ADS)

    Sumiya, Norihito; Igami, Daiki; Takeda, Kyozaburo

    2011-12-01

    We theoretically study the possibility of ion channeling through peptide nanotubes (PNTs). After designing the minimal peptide nanorings (PNRs) and their aggregated form (peptide nanotubes, PNT) computationally, we carry out molecular dynamics (MD) calculations for cation channeling. The present MD calculations show that cation channeling through PNTs occurs. Furthermore, inter-ring hydrogen bonds (HBs) survive and maintain the tubular form of PNTs during cation channeling. We introduce mobility such that cation channeling can be evaluated quantitatively. As the ionic radius of the cation becomes smaller, the effective relaxation time τ becomes larger. Accordingly, mobilities of 10-2˜10-3[cm2/volt/sec] are calculated. In contrast, when an anion (F-) passes through the PNT, the inter-ring HBs are broken, thus inducing breakdown of the peptide backbone. Consequently, H atoms from the broken HBs surround the channeling anion (F-) and halt its motion.

  7. Spectroscopic studies of cold, gas-phase biomolecular ions

    NASA Astrophysics Data System (ADS)

    Rizzo, Thomas R.; Stearns, Jaime A.; Boyarkin, Oleg V.

    While the marriage of mass spectrometry and laser spectroscopy is not new, developments over the last few years in this relationship have opened up new horizons for the spectroscopic study of biological molecules. The combination of electrospray ionisation for producing large biological molecules in the gas phase together with cooled ion traps and multiple-resonance laser schemes are allowing spectroscopic investigation of individual conformations of peptides with more than a dozen amino acids. Highly resolved infrared spectra of single conformations of such species provide important benchmarks for testing the accuracy of theoretical calculations. This review presents a number of techniques employed in our laboratory and in others for measuring the spectroscopy of cold, gas-phase protonated peptides. We show examples that demonstrate the power of these techniques and evaluate their extension to still larger biological molecules.

  8. A macromolecular crowding study of RNA folding and activity: polymer pore size matters! (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Börner, Richard; Fiorini, Erica; Paudel, Bishnu; Rueda, David; Sigel, Roland K. O.

    2016-03-01

    Catalytic RNAs, like the group IIB intron ribozyme of S. cerevesiae, require a high magnesium(II) concentration to show folding and function in vitro [1]. In contrast, in vivo conditions are characterized by a highly crowded cellular environment and much lower ion concentration. Molecular crowding agents are a widespread tool to mimic cellular crowding [2]. However, particular physical/chemical properties explaining the crowders influence are mostly not understood. In this study, we gain new insights on how polymer properties like viscosity, pore size etc. influence the activity and folding of a large RNA. We combined bulk activity assays and single-molecule Förster Resonance Energy Transfer experiments, screening the PEG volume fraction (%) and molecular weight (MW). Our results revealed that upon the influence of crowding agents, a compaction of the underlying structure depends on the PEG % and the presence of different PEG MW and % unveiled an optimal pore size in terms of catalytic activity. In summary, an increasing density of the crowding environment shifts the RNA towards the most compact state, but the ribozyme is only active if the crowders network matches its size [4]. We interpret the most compact state as necessary, but not sufficient, to keep the ribozyme active. Financial support from the European Research Council (MIRNA N° 259092, to RKOS), the Swiss National Fund (SNF), and the Forschungskredit Grant of the University of Zürich (FK-14-096 and 15-092 to RB) are gratefully acknowledged. [1] Swisher J.F., Su L.J., Brenowitz M., Anderson V.E., Pyle A.M., J. Mol. Bio., 315, 297-310 (2002). [2] Kilburn D., Roh J.H., Guo L., Briber R.M., Woodson S.A., JACS, 132, 8690-6 (2010). [3] Steiner M., Karunatilaka K.S., Sigel R.K.O., Rueda D., Proc. Natl. Acad. Sci. U.S.A.,105, 13853-8 (2008). [4] aBörner R, Fiorini E, Sigel R.K.O., Chimia, 69, 207-212 (2015).; bFiorini E., Paudel B., Börner R., Rueda D., Sigel R.K.O., submitted. [5] König S.L.B., Hadzic M

  9. A study of light ion accelerators for cancer treatment

    SciTech Connect

    Prelec, K.

    1997-07-01

    This review addresses several issues, such as possible advantages of light ion therapy compared to protons and conventional radiation, the complexity of such a system and its possible adaptation to a hospital environment, and the question of cost-effectiveness compared to other modalities for cancer treatment or to other life saving procedures. Characteristics and effects of different types of radiation on cells and organisms will be briefly described; this will include conventional radiation, protons and light ions. The status of proton and light ion cancer therapy will then be described, with more emphasis on the latter; on the basis of existing experience the criteria for the use of light ions will be listed and areas of possible medical applications suggested. Requirements and parameters of ion beams for cancer treatment will then be defined, including ion species, energy and intensity, as well as parameters of the beam when delivered to the target (scanning, time structure, energy spread). Possible accelerator designs for light ions will be considered, including linear accelerators, cyclotrons and synchrotrons and their basic features given; this will be followed by a review of existing and planned facilities for light ions. On the basis of these considerations a tentative design for a dedicated light ion facility will be suggested, a facility that would be hospital based, satisfying the clinical requirements, simple to operate and reliable, concluding with its cost-effectiveness in comparison with other modalities for treatment of cancer.

  10. [Fluorescence spectroscopic study of interaction between Fe-protoporphyrin in myoglobin and Cu(II) ions].

    PubMed

    Feng, Yu-ying; Yang, Hui; Gu, Xiao-tian; Jiang, Hui-jun; Lu, Tian-hong

    2003-06-01

    In this paper, the interaction between Cu(II) ions and Fe-protoporphyrin in horse-heart myoglobin (FePP-Mb) was studied. As a result, some of the Fe(II) ions in FePP-Mb were found to be replaced by Cu(II) ions forming CuPP-Mb, by adding Cu(II) ions into the myoglobin solution. The interaction became stronger when adding more Cu(II) ions into the myoglobin solution. By studying the metal ions' interaction with myoglobin proteins as macromolecules and discussing the interaction mechanism, this work provides a theoretical basis for the further study of hazardous metal ions' interaction with the human body and its mechanism. The fluorescence spectroscopic method used in this study has higher sensitivity than the ordinary UV and CD methods.

  11. Dividing to unveil protein microheterogeneities: traveling wave ion mobility study.

    PubMed

    Halgand, F; Habchi, Johnny; Cravello, Laetitia; Martinho, Marlène; Guigliarelli, Bruno; Longhi, Sonia

    2011-10-01

    Overexpression of a protein in a foreign host is often the only route toward an exhaustive characterization, especially when purification from the natural source(s) is hardly achievable. The key issue in these studies relies on quality control of the purified recombinant protein to precisely determining its identity as well as any undesirable microheterogeneities. While standard proteomics approaches preclude unbiased search for modifications, the optional technique of top-down tandem mass spectrometry (MSMS) requires the use of highly accurate and highly resolved experiments to reveal subtle sequence modifications. In the present study, the top-down MSMS approach combined with traveling wave ion mobility (TWIM) separation was evaluated for its ability to achieve high sequence coverage and to reveal subtle microheterogeneities that were hitherto only accessible with Fourier-transform ion cyclotron resonance-MS instruments. The power of this approach is herein illustrated in an in-depth analysis of both the wild type and K496C variant of the recombinant X domain (XD; aa's 459-507) of the measles virus phosphoprotein expressed in Escherichia coli . Using top-down MSMS combined with TWIM, we show that XD samples occasionally exhibit a microheterogeneity that could not be anticipated from the nucleotide sequence of the encoding constructs and that likely reflects a genetic drift, neutral or not, occurring during expression. In addition, a 1-oxyl-2,2,5,5-tetramethyl-δ3-pyrroline-3-methyl methanethiosulfonate nitroxide probe that was grafted onto the K496C XD variant was shown to undergo oxidation and/or protonation in the electrospray ionization source, leading to artifactual mass increases.

  12. Studies of the Mirrortron ion accelerator concept and its application to heavy-ion drivers

    SciTech Connect

    Post, R.F.; Schwager, L.A. ); Douglass, S.R.; Jones, B.R.; Lambert, M.A.; Larson, D.L. . Dept. of Applied Science)

    1990-11-30

    The Mirrortron accelerator is a plasma-based ion accelerator concept that, when implemented, should permit both higher acceleration gradients and higher peak-current capabilities than is possible with conventional induction-type accelerators. Control over the acceleration and focussing of an accelerated beam should approach that achieved in vacuum-field-based ion accelerators. In the Mirrortron a low density (10{sup 10} to 10{sup 11} cm{sup {minus}3}) hot electron'' plasma is confined by a long solenoidal magnetic field capped by mirrors.'' Acceleration of pre-bunched ions is accomplished by activating a series of fast-pulsed mirror coils spaced along the acceleration tube. The hot electrons, being repelled by mirror action, leave the plasma ions behind to create a localized region of high electrical gradient (up to of order 100 MV/m). At the laboratory an experiment and analyses to elucidate the concept and its scaling laws as applied to heavy-ion drivers are underway and will be described. 4 refs., 5 figs.

  13. Experimental studies on ion acceleration and stream line detachment in a diverging magnetic field

    PubMed Central

    Terasaka, K.; Yoshimura, S.; Ogiwara, K.; Aramaki, M.; Tanaka, M. Y.

    2010-01-01

    The flow structure of ions in a diverging magnetic field has been experimentally studied in an electron cyclotron resonance plasma. The flow velocity field of ions has been measured with directional Langmuir probes calibrated with the laser induced fluorescence spectroscopy. For low ion-temperature plasmas, it is concluded that the ion acceleration due to the axial electric field is important compared with that of gas dynamic effect. It has also been found that the detachment of ion stream line from the magnetic field line takes place when the parameter |fciLB∕Vi| becomes order unity, where fci, LB, and Vi are the ion cyclotron frequency, the characteristic scale length of magnetic field inhomogeneity, and the ion flow velocity, respectively. In the detachment region, a radial electric field is generated in the plasma and the ions move straight with the E×B rotation driven by the radial electric field. PMID:20838424

  14. Computational Study of Primary Electrons in the Cusp Region of an Ion Engine's Discharge Chamber

    NASA Technical Reports Server (NTRS)

    Stueber, Thomas J. (Technical Monitor); Deshpande, Shirin S.; Mahalingam, Sudhakar; Menart, James A.

    2004-01-01

    In this work a computer code called PRIMA is used to study the motion of primary electrons in the magnetic cusp region of the discharge chamber of an ion engine. Even though the amount of wall area covered by the cusps is very small, the cusp regions are important because prior computational analyses have indicated that most primary electrons leave the discharge chamber through the cusps. The analysis presented here focuses on the cusp region only. The affects of the shape and size of the cusp region on primary electron travel are studied as well as the angle and location at which the electron enters the cusp region. These affects are quantified using the confinement length and the number density distributions of the primary electrons. In addition to these results comparisons of the results from PRIMA are made to experimental results for a cylindrical discharge chamber with two magnetic rings. These comparisons indicate the validity of the computer code called PRIMA.

  15. Electrochemical quartz crystal microbalance (EQCM) study of ion dynamics in nanoporous carbons.

    PubMed

    Tsai, Wan-Yu; Taberna, Pierre-Louis; Simon, Patrice

    2014-06-18

    Electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry (CV) measurements were used to characterize ion adsorption in carbide-derived carbon (CDC) with two different average pore sizes (1 and 0.65 nm), from neat and solvated 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI) electrolytes. From the electrode mass change in neat EMI-TFSI, it was shown that one net charge stored corresponds almost to one single ion at high polarization; in that case, no ion-pairing or charge screening by co-ions were observed. In 2 M EMI-TFSI in acetonitrile electrolyte, experimental solvation numbers were estimated for EMI(+) cation, showing a partial desolvation when cations were adsorbed in confined carbon pores. The extent of desolvation increased when decreasing the carbon pore size (from 1 down to 0.65 nm). The results also suggest that EMI(+) cation owns higher mobility than TFSI(-) anion in these electrolytes.

  16. AN EXPERIMENTAL PROPOSAL TO STUDY HEAVY-ION COOLING IN THE AGS DUE TO BEAM GAS OR THE INTRABEAM SCATTERING.

    SciTech Connect

    TRBOJEVIC, D.; AHERNS, L.; ROSER, T.; MACKAY, W.; BRENNAN, J.; BLASKIEWICZ,M.; PARZEN, G.; BEEBE-WANG, J.

    2006-06-23

    Low emittance of not-fully-stripped gold (Z=79) Au{sup +77} Helium-like ion beams from the AGS (Alternating Gradient Synchrotron) injector to the Relativistic Heavy Ion Collider (RHIC) could be attributed to the cooling phenomenon due to inelastic intrabeam scattering [1,2] or due to electron de-excitations from collisions with the residual gas [3]. The low emittance gold beams have always been observed at injection in the Relativistic Heavy Ion Collider (RHIC). There have been previous attempts to attribute the low emittance to a cooling due to the exchange of energy between ions during the inelastic intrabeam scattering. The Fano-Lichten theory [4] of electron promotion might be applied during inelastic collisions between helium like gold ions in the AGS. The two K-shell electrons in gold Au{sup +77} could get promoted if the ions reach the critical distance of the closest approach during intra-beam scattering or collisions with the residual gas. During collisions if the ion energy is large enough, a quasi-molecule could be formed, and electron excitation could occur. During de-excitations of electrons, photons are emitted and a loss of total bunch energy could occur. This would lead to smaller beam size. We propose to inject gold ions with two missing electrons into RHIC, at injection energy, and study the beam behavior with bunched and de-bunched beam, varying the RF voltage and the beam intensity. If the ''cooling'' is observed additional X-ray detectors could be installed to observe emitted photons.

  17. A mass spectrometry study of n-octane: Electron impact ionization and ion-molecule reactions

    NASA Astrophysics Data System (ADS)

    Jiao, C. Q.; DeJoseph, C. A.; Garscadden, A.

    2001-02-01

    Electron impact ionization of n-octane over an energy range of 10-70 eV and the subsequent ion-molecule reactions with the parent molecule have been studied using Fourier-transform mass spectrometry. Molecular ion and fragment ions C1+-C6+ are produced from the electron impact with a total ionization cross section of 1.4±0.2×10-15 cm2 between 60 and 70 eV. C3H7+ is the most abundant ion at most of the ionizing energies with the exception for E⩽16 eV where C6H13+ and C6H12+ are the most abundant. Among the fragment ions only C4H7+ and smaller ions react readily with the parent molecule, primarily producing C5H11+ and C4H9+, with rate coefficients of 0.32-2.4×10-9 cm3s-1. Essentially all of the ions, including the molecular ion and the large fragment ions, undergo decomposition upon collision with neutral molecules after they are kinetically excited to an energy range of 1-5 eV, forming a variety of small hydrocarbon ions. Many of the decomposition product ions in turn are capable of further reacting with n-octane. Isotope reagents have been utilized in experiments to probe the type of the ion-molecule reactions studied.

  18. Plasmonics for the study of metal ion-protein interactions.

    PubMed

    Grasso, Giuseppe; Spoto, Giuseppe

    2013-02-01

    The study of metal-protein interactions is an expanding field of research investigated by bioinorganic chemists as it has wide applications in biological systems. Very recently, it has been reported that it is possible to study metal-protein interactions by immobilizing biomolecules on metal surfaces and applying experimental approaches based on plasmonics which have usually been used to investigate protein-protein interactions. This is possible because the electronic structure of metals generates plasmons whose properties can be exploited to obtain information from biomolecules that interact not only with other molecules but also with ions in solution. One major challenge of such approaches is to immobilize the protein to be studied on a metal surface with preserved native structure. This review reports and discusses all the works that deal with such an expanding new field of application of plasmonics with specific attention to surface plasmon resonance, highlighting the advantages and drawbacks of such approaches in comparison with other experimental techniques traditionally used to study metal-protein interactions.

  19. XAFS Studies of Silver Environments in Ion-Exchanged Glasses

    SciTech Connect

    Yang, X. C.; Dubiel, M.

    2007-02-02

    The X-ray absorption fine structure (XAFS) technique was used to analyze the structural geometry of Ag atoms introduced into soda-lime silicate glass and soda aluminosilicate glass by ion-exchange methods. The results show that Ag+ ions in aluminosilicate glass are coordinated by about two oxygens and the nearest-neighbor Ag-O distance increases when the Ag+-for-Na+ ion-exchange ratio is larger than 0.47. When the exchange ratio is low, the introduced Ag+ ions are stabilized at the non-bridge oxygen (NBO) site with a Ag-O distance of 2.20 A, and the Na+ ions in the AlO4 site are exchanged by Ag+ ions after full replacement of the NBO sites with a Ag-O distance of 2.28 A. The disorder of Ag-O coordination increases with increasing ion-exchange ratio in aluminosilicate glass where Ag+ ions are coordinated by NBO and bridge oxygen (BO)

  20. Strain-based in-situ study of anion and cation insertion into porous carbon electrodes with different pore sizes

    SciTech Connect

    Black, Jennifer M; Feng, Guang; Fulvio, Pasquale F; Hillesheim, Patrick C; Dai, Sheng; Gogotsi, Yury G.; Cummings, Peter T; Kalinin, Sergei V; Balke, Nina

    2013-01-01

    The expansion of porous carbon electrodes in a room temperature ionic liquid (RTIL) is studied using in-situ atomic force microscopy (AFM). The effect of carbon surface area and pore size/pore size distribution on the observed strain profile and ion kinetics is examined. Also, the influence of potential scan rate on the strain response is investigated. By analyzing the strain data at various potential scan rates information on ion kinetics in the different carbon materials is obtained. Molecular dynamics (MD) simulations are performed to compare with and provide molecular insights into experimental results, which is the first MD work investigating the pressure exerted on porous electrodes under applied potential in a RTIL electrolyte. Using MD, the pressure exerted on the pore wall is calculated as a function of potential/charge for both a micropore (1.2 nm) and a mesopore (7.0 nm). The shape of the calculated pressure profile matches closely with the strain profiles observed experimentally.

  1. A laboratory study of collisional electrostatic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Suszcynsky, D. M.; Cartier, S. L.; Merlino, R. L.; Dangelo, N.

    1986-01-01

    The effects of neutral-particle collisions on electrostatic ion cyclotron instability are analyzed. Experiments were conducted in the Q machine of Motley (1975) with a cesium plasma in which the neutral gas pressure in the main chamber varied from about 5 microtorr-10 mtorr. The relation between electrostatic ion cyclotron wave amplitude and frequency and neutral argon pressure is examined. It is observed that over the full range of neutral pressure the frequency changes by less than 10 percent and the ion cyclotron waves continue to be excited and reach amplitudes of at least several percent at values of the neutral pressure where the ion-neutral collision frequency/ion gyrofrequency is about 0.3.

  2. Studies of complex fragment emission in heavy ion reactions

    SciTech Connect

    Charity, R.J.; Sobotka, L.G.

    1992-01-01

    Our work involves the study of intermediate energy heavy-ion nuclear reactions. This work has two foci. On the one hand, we desire to learn about the properties of nuclear matter under abnormal conditions, in this energy domain, predominately low densities. This purpose runs abreast of the second, which is the study of the relevant reaction mechanisms. The two objectives are inexorably linked because our experimental laboratory for studying nuclear matter properties is a dynamic one. We are forced to ask how nuclear matter properties, such as phase transitions, are reflected in the dynamics of the reactions. It may be that irrefutable information about nuclear matter will not be extracted from the reaction work. Nevertheless, we are compelled to undertake this effort not only because it is the only game in town and as yet we do not know that information cannot be extracted, but also because of our second objective. The process leads to an understanding of the reaction mechanism themselves and therefore to the response characteristics of finite, perhaps non-equilibrium, strongly interacting systems. Our program has been: To study energy, mass, and angular momentum deposition by studying incomplete fusion reactions. To gain confidence that we understand how highly excited systems decompose by studying all emissions from the highly excited systems. To push these kinds of studies into the intermediate energy domain, with excitation function studies. And attempt to learn about the dynamics of the decays using particle-particle correlations. In the last effort, we have decided to focus on simple systems, where we believe, definitive statements are possible. These avenues of research share a common theme, large complex fragment production.

  3. Understanding the Size-Dependent Sodium Storage Properties of Na2C6O6-Based Organic Electrodes for Sodium-Ion Batteries.

    PubMed

    Wang, Yaqun; Ding, Yu; Pan, Lijia; Shi, Ye; Yue, Zhuanghao; Shi, Yi; Yu, Guihua

    2016-05-11

    Organic electroactive materials represent a new generation of sustainable energy storage technology due to their unique features including environmental benignity, material sustainability, and highly tailorable properties. Here a carbonyl-based organic salt Na2C6O6, sodium rhodizonate (SR) dibasic, is systematically investigated for high-performance sodium-ion batteries. A combination of structural control, electrochemical analysis, and computational simulation show that rational morphological control can lead to significantly improved sodium storage performance. A facile antisolvent method was developed to synthesize microbulk, microrod, and nanorod structured SRs, which exhibit strong size-dependent sodium ion storage properties. The SR nanorod exhibited the best performance to deliver a reversible capacity of ∼190 mA h g(-1) at 0.1 C with over 90% retention after 100 cycles. At a high rate of 10 C, 50% of the capacity can be obtained due to enhanced reaction kinetics, and such high electrochemical activity maintains even at 80 °C. These results demonstrate a generic design route toward high-performance organic-based electrode materials for beyond Li-ion batteries. Using such a biomass-derived organic electrode material enables access to sustainable energy storage devices with low cost, high electrochemical performance and thermal stability.

  4. Body Size Extinction and Origination Selectivity: A Case Study of Marine Gastropods

    NASA Astrophysics Data System (ADS)

    Kuo, E.; Seixas, G.; Faerber, M.; Payne, J.

    2012-12-01

    Body size has received exceptional interest in evolutionary biology because of its correlation with many ecological and physiological traits. Because large size is typically associated with long generation time and small population size, it has been widely assumed that extinction risk is positively correlated with body size. Data from Pleistocene and Holocene terrestrial mammals and birds support this inference. However, there have been few studies on size bias of marine invertebrate animals, so the true extent of this pattern remains unknown. For this study, we compiled genus-level body size data for marine gastropods spanning the entire Phanerozoic. We use this dataset to examine the statistical evidence for size bias in both origination and extinction of marine gastropods. We perform logistic regression analyses on the data from each Phanerozoic stage to determine the association of body size with origination and extinction. Contrary to previous studies on terrestrial vertebrates, we observe no strong or persistent association between body size and the probability that a genus either originated or went extinct during that stage. Hence, our findings indicate that size bias in extinction risk may reflect particular aspects of mammalian biology or anthropogenic environmental change rather than a general pattern of animal evolution.

  5. Spectroscopic studies of cathode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Totir, Dana Alexa

    2000-10-01

    Structural changes that occur during electrochemical cycling of lithium-ion battery cathode materials have been investigated using in situ spectroscopic techniques. A new method was developed for the preparation of carbon and binder free cathodes utilizing powder materials of interest for commercial batteries. The extraordinary quality of the cyclic voltammetric curves recorded for this type of electrodes during the in situ measurements allows direct correlations to be made between the state of charge of the material and its structural and electronic characteristics. LiCoO2, LiMn2O4 and LiCo0.15Ni 0.85O2 electrodes were evaluated using cycling voltammetry and the mean diffusion coefficient for Li-ions in the lattice (DLi) was calculated for LiMn2O4. LiMn2O4 electrodes prepared by this technique have been studied in situ using Mn K-edge XAS. Data analysis for the species formed at different potentials indicated a contraction of the lattice associated with the increase in the oxidation state of manganese. In situ Raman spectra of particles of LiMn2O 4, and LiCoO2 embedded in Au and also of KS-44 graphite and carbon microfibers MCF28 embedded in thermally annealed Ni have been recorded as a function of the applied potential. Fe K-edge XAFS of pyrite electrodes in a Li/PEO(LiClO4)/FeS 2 cell and S K-edge XANES measurements of a FeS2 electrode in a non-aqueous electrolyte have been acquired as a function of the state of charge. The studies have clearly evidenced the formation of metallic Fe and Li2S as intermediates after 4 e- discharge and the formation of Li2FeS2 after 2 e- recharge. While Fe K-edge studies have indicated that there is no change in the Fe environment and oxidation state upon 4 e- recharge, the results obtained from S K-edge studies are inconclusive for this stage. Finally, in situ Co K-edge XAFS data were obtained for the first time during the electrochemical cycling of electrodeposited Co(OH) 2 films in alkaline solutions. The results support

  6. Promoting the Adsorption of Metal Ions on Kaolinite by Defect Sites: A Molecular Dynamics Study

    PubMed Central

    Li, Xiong; Li, Hang; Yang, Gang

    2015-01-01

    Defect sites exist abundantly in minerals and play a crucial role for a variety of important processes. Here molecular dynamics simulations are used to comprehensively investigate the adsorption behaviors, stabilities and mechanisms of metal ions on defective minerals, considering different ionic concentrations, defect sizes and contents. Outer-sphere adsorbed Pb2+ ions predominate for all models (regular and defective), while inner-sphere Na+ ions, which exist sporadically only at concentrated solutions for regular models, govern the adsorption for all defective models. Adsorption quantities and stabilities of metal ions on kaolinite are fundamentally promoted by defect sites, thus explaining the experimental observations. Defect sites improve the stabilities of both inner- and outer-sphere adsorption, and (quasi) inner-sphere Pb2+ ions emerge only at defect sites that reinforce the interactions. Adsorption configurations are greatly altered by defect sites but respond weakly by changing defect sizes or contents. Both adsorption quantities and stabilities are enhanced by increasing defect sizes or contents, while ionic concentrations mainly affect adsorption quantities. We also find that adsorption of metal ions and anions can be promoted by each other and proceeds in a collaborative mechanism. Results thus obtained are beneficial to comprehend related processes for all types of minerals. PMID:26403873

  7. A Comparative Study of Power and Sample Size Calculations for Multivariate General Linear Models

    ERIC Educational Resources Information Center

    Shieh, Gwowen

    2003-01-01

    Repeated measures and longitudinal studies arise often in social and behavioral science research. During the planning stage of such studies, the calculations of sample size are of particular interest to the investigators and should be an integral part of the research projects. In this article, we consider the power and sample size calculations for…

  8. Another Look at the Glass and Smith Study on Class Size

    ERIC Educational Resources Information Center

    Phelps, James L.

    2011-01-01

    One of the most influential studies affecting educational policy is Glass and Smith's 1978 study, "Meta-Analysis of Research on the Relationship of Class-Size and Achievement." Since its publication, educational policymakers have referenced it frequently as the justification for reducing class size. While teachers and the public had long believed…

  9. Managers' Understanding of Workplace Health Promotion within Small and Medium-Sized Enterprises: A Phenomenological Study

    ERIC Educational Resources Information Center

    Moore, Ann; Parahoo, Kader; Fleming, Paul

    2011-01-01

    Objective: This study aimed at exploring managers' understanding of workplace health promotion and experiences of workplace health promotion activity within small and medium-sized enterprises. Design: A Heideggerian interpretive phenomenological methodology was adopted. Setting: This study was undertaken with small and medium-sized enterprise…

  10. Ion implantation and annealing studies in III-V nitrides

    SciTech Connect

    Zolper, J.C.; Pearton, S.J.; Williams, J.S.; Tan, H.H.; Karlicek, R.J. Jr.; Stall, R.A.

    1996-12-31

    Ion implantation doping and isolation is expected to play an enabling role for the realization of advanced III-Nitride based devices. In fact, implantation has already been used to demonstrate n- and p-type doping of GaN with Si and Mg or Ca, respectively, as well as to fabricate the first GaN junction field effect transistor. Although these initial implantation studies demonstrated the feasibility of this technique for the III-Nitride materials, further work is needed to realize its full potential. After reviewing some of the initial studies in this field, the authors present new results for improved annealing sequences and defect studies in GaN. First, sputtered AlN is shown by electrical characterization of Schottky and Ohmic contacts to be an effect encapsulant of GaN during the 1,100 C implant activation anneal. The AlN suppresses N-loss from the GaN surface and the formation of a degenerate n{sup +}-surface region that would prohibit Schottky barrier formation after the implant activation anneal. Second, they examine the nature of the defect generation and annealing sequence following implantation using both Rutherford Backscattering (RBS) and Hall characterization. They show that for a Si-dose of 1 x 10{sup 16} cm{sup {minus}2} 50% electrical donor activation is achieved despite a significant amount of residual implantation-induced damage in the material.

  11. Fifth high-energy heavy-ion study

    SciTech Connect

    Not Available

    1981-10-01

    This was the fifth of a continuing series of summer studies held at LBL to discuss high energy heavy ion collisions. Recently, a similar meeting has been held on alternate years at GSI (Darmstadt); and, in 1979, we held a meeting at LBL exclusively devoted to ultra-relativistic nuclear collisions. Two new features distinguish this study from earlier meetings in the series. First, the energy range for discussion was broadened by including collisions from about 20 MeV/nucleon to the highest available in the cosmic radiation. The lower range, particularly below 100 MeV/nucleon, will be under intense study in the near future with machines such as the upgraded Bevalac, Michigan State University Superconducting Cyclotron, GANIL in France, and the SC at CERN. Recently, the high energy collision regime has been expanded by the successful operation of the CERN ISR with alpha particles. Second, in addition to an extensive program of invited talks, we decided for the first time to actively solicit contributions. Forty-seven individual items from the conference were prepared separately for the data base. (GHT)

  12. Development of a low-cost small-sized scanning transmission ion microscope of moderate resolution with educational and other potential applications

    NASA Astrophysics Data System (ADS)

    Pallone, Arthur

    2009-03-01

    Scanning transmission ion microscopy (STIM) has applications in many fields of study such as materials and device engineering, biological and geological sciences, and the arts. Since STIM is practiced at ion beam facilities, many persons outside of the ion beam community who could benefit from STIM are unaware of its potential. In an effort to better educate the public about STIM, an inexpensive portable demonstration unit suitable for interactive classroom use and public outreach events is under development. The required parts are readily available, mostly at local electronics and office supply stores. Progress toward completion of the demonstration unit and future efforts to modify the unit to support thin film research will be discussed. Activities that demonstrate the three modes of STIM will also be presented.

  13. Radiotracer studies on ion-selective membranes based on poly(vinyl chloride) matrices.

    PubMed

    Jaber, A M; Moody, G J; Thomas, J D; Willcox, A

    1977-10-01

    Radiotracer studies with (45)Ca, (89)Sr and (133)Ba have provided evidence that the permeation of magnesium, strontium and barium ions through PVC membranes containing Orion 92-20-02 liquid ion-exchanger is inhibited by their low affinity for the liquid ion-exchanger sites. Experiments with (7)Be indicate a strong affinity of the membrane for beryllium ions with corresponding inhibition of permeation. When acid is present in the solution on one side of the membrane, preferential permeation by protons may lead to transport of ions against their concentration gradient in order to maintain the balance of charge.

  14. Study on evolution of gases from fluoropolymer films bombarded with heavy ions

    NASA Astrophysics Data System (ADS)

    Minamisawa, Renato Amaral; Zimmerman, Robert Lee; Budak, Satilmis; Ila, Daryush

    2008-04-01

    Ion beam bombardment provides a unique way of material modification by inducing a high degree of localized electronic excitation. The ion track, or affected volume along the ion path through the material is related to the total damage and possible structural changes. Here we study the evolution of gases emitted by poly(tetrafluorethylene-co-perfluoro-(propyl vinyl ether)) (PFA) fluoropolymer bombarded with MeV gold ions. The gas was monitored by a residual gas analyzer (RGA), as a function of the ion fluence. Micro-Raman, atomic force microscopy and optical absorption were used to analyze the chemical structure changes and sputtering yield.

  15. Does bearing size influence metal ion levels in large-head metal-on-metal total hip arthroplasty? A comparison of three total hip systems

    PubMed Central

    2014-01-01

    Background The purpose of the study was twofold: first, to determine whether there is a statistically significant difference in the metal ion levels among three different large-head metal-on-metal (MOM) total hip systems. The second objective was to assess whether position of the implanted prostheses, patient demographics or factors such as activity levels influence overall blood metal ion levels and whether there is a difference in the functional outcomes between the systems. Methods In a cross-sectional cohort study, three different metal-on-metal total hip systems were assessed: two monoblock heads, the Durom socket (Zimmer, Warsaw, IN, USA) and the Birmingham socket (Smith and Nephew, Memphis, TN, USA), and one modular metal-on-metal total hip system (Pinnacle, Depuy Orthopedics, Warsaw, IN, USA). Fifty-four patients were recruited, with a mean age of 59.7 years and a mean follow-up time of 41 months (12 to 60). Patients were evaluated clinically, radiologically and biochemically. Statistical analysis was performed on all collected data to assess any differences between the three groups in terms of overall blood metal ion levels and also to identify whether there was any other factor within the group demographics and outcomes that could influence the mean levels of Co and Cr. Results Although the functional outcome scores were similar in all three groups, the blood metal ion levels in the larger monoblock large heads (Durom, Birmingham sockets) were significantly raised compared with those of the Pinnacle group. In addition, the metal ion levels were not found to have a statistically significant relationship to the anteversion or abduction angles as measured on the radiographs. Conclusions When considering a MOM THR, the use of a monoblock large-head system leads to higher elevations in whole blood metal ions and offers no advantage over a smaller head modular system. PMID:24472283

  16. The double electrostatic ion ring experiment: a unique cryogenic electrostatic storage ring for merged ion-beams studies.

    PubMed

    Thomas, R D; Schmidt, H T; Andler, G; Björkhage, M; Blom, M; Brännholm, L; Bäckström, E; Danared, H; Das, S; Haag, N; Halldén, P; Hellberg, F; Holm, A I S; Johansson, H A B; Källberg, A; Källersjö, G; Larsson, M; Leontein, S; Liljeby, L; Löfgren, P; Malm, B; Mannervik, S; Masuda, M; Misra, D; Orbán, A; Paál, A; Reinhed, P; Rensfelt, K-G; Rosén, S; Schmidt, K; Seitz, F; Simonsson, A; Weimer, J; Zettergren, H; Cederquist, H

    2011-06-01

    We describe the design of a novel type of storage device currently under construction at Stockholm University, Sweden, using purely electrostatic focussing and deflection elements, in which ion beams of opposite charges are confined under extreme high vacuum cryogenic conditions in separate "rings" and merged over a common straight section. The construction of this double electrostatic ion ring experiment uniquely allows for studies of interactions between cations and anions at low and well-defined internal temperatures and centre-of-mass collision energies down to about 10 K and 10 meV, respectively. Position sensitive multi-hit detector systems have been extensively tested and proven to work in cryogenic environments and these will be used to measure correlations between reaction products in, for example, electron-transfer processes. The technical advantages of using purely electrostatic ion storage devices over magnetic ones are many, but the most relevant are: electrostatic elements which are more compact and easier to construct; remanent fields, hysteresis, and eddy-currents, which are of concern in magnetic devices, are no longer relevant; and electrical fields required to control the orbit of the ions are not only much easier to create and control than the corresponding magnetic fields, they also set no upper mass limit on the ions that can be stored. These technical differences are a boon to new areas of fundamental experimental research, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology. For examples, studies of interactions with internally cold molecular ions will be particular useful for applications in astrophysics, while studies of solvated ionic clusters will be of relevance to aeronomy and biology.

  17. Alkali metal ion storage properties of sulphur and phosphorous molecules encapsulated in nanometer size carbon cylindrical pores

    NASA Astrophysics Data System (ADS)

    Ishii, Yosuke; Sakamoto, Yuki; Song, Hayong; Tashiro, Kosuke; Nishiwaki, Yoshiki; Al-zubaidi, Ayar; Kawasaki, Shinji

    2016-03-01

    We investigated the physical and chemical stabilities of sulfur and phosphorus molecules encapsulated in a mesoporous carbon (MPC) and two kinds of single-walled carbon nanotubes (SWCNTs) having different cylindrical pore diameters. The sublimation temperatures of sulfur molecules encapsulated in MPC and the two kinds of SWCNTs were measured by thermo-gravimetric measurements. It was found that the sublimation temperature of sulfur molecules encapsulated in SWCNTs having mean tube diameter of 1.5 nm is much higher than any other molecules encapsulated in larger pores. It was also found that the capacity fading of lithium-sulfur battery can be diminished by encapsulation of sulfur molecules in SWCNTs. We also investigated the electrochemical properties of phosphorus molecules encapsulated in SWCNTs (P@SWCNTs). It was shown that P@SWCNT can adsorb and desorb both Li and Na ions reversibly.

  18. A new strategy for pressed powder eye shadow analysis: allergenic metal ion content and particle size distribution.

    PubMed

    Contado, Catia; Pagnoni, Antonella

    2012-08-15

    Nine cheap eye shadow products were analyzed through graphite furnace atomic absorption spectrometry (GF-AAS) to quantify their Cr, Co and Ni contents, all known to be skin sensitizers. In many cases, the concentrations were higher than 1 or 5 ppm (μg/g), i.e. the limits recommended in the scientific literature to minimize the risk of reaction in particularly sensitive subjects. In most cases, the concentration of Cr was higher than that of Ni and Co, up to a limit case of 150 mg/g. In this particular sample, the potential amount of Cr that could be released in ionic form was determined in sweat simulating solutions by GF-AAS and confirmed through a specific spectrofluorimetric method; the results indicated the presence of approximately 80-90 ppb (ng/g) of Cr(3+). The water dispersible particles were isolated from the eye shadow powders through a simple solvent extraction procedure. The aqueous suspensions were then sorted through sedimentation field flow fractionation (SdFFF) and the particles sizes were calculated from experimental fractograms using theory. For the most part, the computed sizes were in the micron range, as confirmed by some SEM photographs taken on fractions collected during the separations. The SdFFF coupled off-line with the GFAAS enabled elemental characterization of pigment particles as a function of size. This finding reduces the concern that the ingredients of such makeup formulations may contain nanoparticles.

  19. What about N? A methodological study of sample-size reporting in focus group studies

    PubMed Central

    2011-01-01

    Background Focus group studies are increasingly published in health related journals, but we know little about how researchers use this method, particularly how they determine the number of focus groups to conduct. The methodological literature commonly advises researchers to follow principles of data saturation, although practical advise on how to do this is lacking. Our objectives were firstly, to describe the current status of sample size in focus group studies reported in health journals. Secondly, to assess whether and how researchers explain the number of focus groups they carry out. Methods We searched PubMed for studies that had used focus groups and that had been published in open access journals during 2008, and extracted data on the number of focus groups and on any explanation authors gave for this number. We also did a qualitative assessment of the papers with regard to how number of groups was explained and discussed. Results We identified 220 papers published in 117 journals. In these papers insufficient reporting of sample sizes was common. The number of focus groups conducted varied greatly (mean 8.4, median 5, range 1 to 96). Thirty seven (17%) studies attempted to explain the number of groups. Six studies referred to rules of thumb in the literature, three stated that they were unable to organize more groups for practical reasons, while 28 studies stated that they had reached a point of saturation. Among those stating that they had reached a point of saturation, several appeared not to have followed principles from grounded theory where data collection and analysis is an iterative process until saturation is reached. Studies with high numbers of focus groups did not offer explanations for number of groups. Too much data as a study weakness was not an issue discussed in any of the reviewed papers. Conclusions Based on these findings we suggest that journals adopt more stringent requirements for focus group method reporting. The often poor and

  20. Modification of Polymer Materials by Ion Bombardment: Case Studies

    SciTech Connect

    Bielinski, D. M.; Jagielski, J.; Piatkowska, A.

    2009-03-10

    The paper discusses possibility of application of ion beam bombardment for modification of polymers. Changes to composition, structure and morphology of the surface layer produced by the treatment and their influence on engineering and functional properties of wide range of polymer materials are presented. Special attention has been devoted to modification of tribological properties. Ion bombardment results in significant reduction of friction, which can be explained by increase of hardness and wettability of polymer materials. Hard but thin enough skin does not result in cracking but improves their abrasion resistance. Contrary to conventional chemical treatment ion beam bombardment works even for polymers hardly susceptible to modification like silicone rubber or polyolefines.

  1. A rotary nano ion pump: a molecular dynamics study.

    PubMed

    Lohrasebi, A; Feshanjerdi, M

    2012-09-01

    The dynamics of a rotary nano ion pump, inspired by the F (0) part of the F(0)F(1)-ATP synthase biomolecular motor, were investigated. This nanopump is composed of a rotor, which is constructed of two carbon nanotubes with benzene rings, and a stator, which is made of six graphene sheets. The molecular dynamics (MD) method was used to simulate the dynamics of the ion nanopump. When the rotor of the nanopump rotates mechanically, an ion gradient will be generated between the two sides of the nanopump. It is shown that the ion gradient generated by the nanopump is dependant on parameters such as the rotary frequency of the rotor, temperature and the amounts and locations of the positive and negative charges of the stator part of the nanopump. Also, an electrical potential difference is generated between the two sides of the pump as a result of its operation.

  2. Application of ion chromatography in clinical studies and pharmaceutical industry.

    PubMed

    Michalski, Rajmund

    2014-01-01

    Ion chromatography is a well-established regulatory method for analyzing anions and cations in environmental, food and many other samples. It offers an enormous range of possibilities for selecting stationary and mobile phases. Additionally, it usually helps to solve various separation problems, particularly when it is combined with different detection techniques. Ion chromatography can also be used to determine many ions and substances in clinical and pharmaceutical samples. It provides: availability of high capacity stationary phases and sensitive detectors; simple sample preparation; avoidance of hazardous chemicals; decreased sample volumes; flexible reaction options on a changing sample matrix to be analyzed; or the option to operate a fully-automated system. This paper provides a short review of the ion chromatography applications for determining different inorganic and organic substances in clinical and pharmaceutical samples.

  3. Feasibility study of heavy ion physics program at NICA

    NASA Astrophysics Data System (ADS)

    Batyuk, P. N.; Kekelidze, V. D.; Kolesnikov, V. I.; Rogachevsky, O. V.; Sorin, A. S.; Voronyuk, V. V.

    2016-07-01

    There are strong experimental and theoretical evidences that in collisions of heavy ions at relativistic energies nuclear matter undergoes a phase transition to the deconfined state—Quark Gluon Plasma. The caused energy region of such transition was not found at high energy at SPS and RHIC and search for this energy is shifted to lower energies, which will be covered by the future NICA (Dubna), FAIR (Darmstadt) facilities and BES II at RHIC. Fixed target and collider experiments at the NICA facility will work at the energy range from a few AGeV up to √ {{S_{NN}}} = 11GeV GeV and will study the most interesting area on the nuclear matter phase diagram. The most remarkable results were observed in the study of collective phenomena occurring in the early stage of nuclear collisions. Investigation of the collective flow will provide information on Equation of State (EoS) for nuclear matter. Study of the Event-by-Event fluctuations and correlations can give us signals of critical behavior of the system. Femtoscopy analysis provides the space-time history of the collisions. Also, it was found that baryon stopping power revealing itself as a "wiggle" in excitation function of curvature of the (net)proton rapidity spectrum relates to the order of the phase transition. The available observations of an enhancement of dilepton rates at low invariant masses may serve as a signal of the chiral symmetry restoration in hot and dense matter. Due to this fact, measurements of the dilepton spectra are considered to be an important part of the NICA physics program. The study of strange particles and hypernuclei production gives additional information on the EoS and "strange" axis of the QCD phase diagram. In this paper a feasibility of the considered investigations is shown by the detailed Monte Carlo simulations applied to the planned experiments (BM@N, MPD) at NICA.

  4. Observations on ion track structure in semiconductors : a phenomenological study

    NASA Technical Reports Server (NTRS)

    Selva, L. E.; Wallace, R. E.

    2001-01-01

    An ion track structure model at the nanometer scale is presented. The model is based on electrostatic principles and is supported by observed experimental results conducted on power MOSFETs. The model predicts the existence of a transient induced electric field following the passage of an energetic heavy ion. There are two segments to the field (a radial and an axial component). It is the interaction of this transient electric field with the local environment that can trigger a catastrophic failure.

  5. Spatial fractionation of the dose using neon and heavier ions: A Monte Carlo study

    SciTech Connect

    Peucelle, C.; Martínez-Rovira, I.; Prezado, Y.

    2015-10-15

    Purpose: This work explores a new radiation therapy approach which might trigger a renewed use of neon and heavier ions to treat cancers. These ions were shown to be extremely efficient in radioresistant tumor killing. Unfortunately, the efficient region also extends into the normal tissue in front of the tumor. The strategy the authors propose is to profit from the well-established sparing effect of thin spatially fractionated beams, so that the impact on normal tissues might be minimized while a high tumor control is achieved. The main goal of this work is to provide a proof of concept of this new approach. With that aim, a dosimetric study was carried out as a first step to evaluate the interest of further explorations of this avenue. Methods: The GATE/GEANT4 v.6.1 Monte Carlo simulation platform was employed to simulate arrays of rectangular minibeams (700 μm × 2 cm) of four ions (Ne, Si, Ar, and Fe). The irradiations were performed with a 2 cm-long spread-out Bragg peak centered at 7 cm-depth. Dose distributions in a water phantom were scored considering two minibeams center-to-center distances: 1400 and 3500 μm. Peak and valley doses, peak-to-valley dose ratios (PVDRs), beam penumbras, and relative contribution of nuclear fragments and electromagnetic processes were assessed as figures of merit. In addition, the type and proportion of the secondary nuclear fragments were evaluated in both peak and valley regions. Results: Extremely high PVDR values (>100) and low valley doses were obtained. The higher the atomic number (Z) of the primary ion is, the lower the valleys and the narrower the penumbras. Although the yield of secondary nuclear products increases with Z, the actual dose being deposited by the secondary nuclear fragments in the valleys starts to be the dominant contribution at deeper points, helping in the sparing of proximal normal tissues. Additionally, a wider center-to-center distance leads to a minimized contribution of heavier secondary

  6. XPS Study of Plasma- and Argon Ion-Sputtered Polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Kliss, Mark (Technical Monitor)

    1997-01-01

    The similarity of plasma-polymerized tetrafluoroethylene (PPTFE) and the fluoropolymer film deposited by rf (radio frequency) plasma sputtering (SPTFE) of polytetrafluoroethylene (PTFE), noted earlier in the literature, has been reconfirmed. FT-IR (Fourier Transform Infrared), XPS (X ray Photoelectron Spectroscopy) and UV (ultraviolet) spectroscopy has been employed in apparently the first study to involve preparation of PPTFE and SPTFE in the same reactor and under comparable low-power plasma conditions. Most of the work concerned the use of He or Ar as sputtering gas, but some runs were also carried out with the other rare gases Ne, Kr and Xe. The C1s XPS spectra of SPTFE films displayed a relatively higher content of CF2 groups, and yielded higher F/C (fluorine / carbon) ratios, than PPTFE films, while the SPTFE films were somewhat more transparent in the UV than PPTFE. The F/C ratios for SPTFE were essentially independent of the rare gas used for sputtering. Increasing rf power from 10 to 50 W for Xe plasma-sputtering of PTFE resulted in successively lower F/C ratios (1.55 to 1.21), accompanied by sputtering of the glass reactor occurring at 40 W and above. Some limited XPS, FT-IR and UV data are presented on Ar ion-sputtered PTFE.

  7. Metals leachability from medical waste incinerator fly ash: A case study on particle size comparison.

    PubMed

    Sukandar, Sukandar; Yasuda, Kenji; Tanaka, Masaru; Aoyama, Isao

    2006-12-01

    This paper presents the results from a study of metals leachability of medical waste incinerator fly ash in Japan on the basis of particle size. Sequential extraction and Toxicity Characteristic Leaching Procedure (TCLP) analysis were carried out in order to quantify the leaching amount of metals in each categorized particle size. Sequential extraction was also subjected to identify the preference of binding matrix of metals. The results of sequential extraction showed an increase both exchangeable and carbonate associated chromium concentrations in the bigger particle size fractions. Likewise, concentrations of carbonate matrix of arsenic and tin tended to increase in the bigger particle size fractions. In contrast, exchangeable associated cadmium as well as both exchangeable and carbonate matrices of barium were found higher in the smaller particle size fractions. However, no correlation was found in Kendal-tau correlation analysis between particle size of the ash and metals leachability of the TCLP.

  8. Porous carbon spheres and monoliths: morphology control, pore size tuning and their applications as Li-ion battery anode materials.

    PubMed

    Roberts, Aled D; Li, Xu; Zhang, Haifei

    2014-07-01

    The development of the next generation of advanced lithium-ion batteries (LIBs) requires new & advanced materials and novel fabrication techniques in order to push the boundaries of performance and open up new and exciting markets. Structured carbon materials, with controlled pore features on the micron and nanometer scales, are explored as advanced alternatives to conventional graphite as the active material of the LIB anode. Mesoporous carbon materials, carbon nanotube-based materials, and graphene-based materials have been extensively investigated and reviewed. Morphology control (e.g., colloids, thin films, nanofibrous mats, monoliths) and hierarchical pores (particularly the presence of large pores) exhibit an increasing influence on LIB performance. This tutorial review focuses on the synthetic techniques for preparation of porous carbon spheres and carbon monoliths, including hydrothermal carbonization, emulsion templating, ice templating and new developments in making porous carbons from sustainable biomass and metal-organic framework templating. We begin with a brief introduction to LIBs, defining key parameters and terminology used to assess the performance of anode materials, and then address synthetic techniques for the fabrication of carbon spheres & monoliths and the relevant composites, followed, respectively, by a review of their performance as LIB anode materials. The review is completed with a prospective view on the possible direction of future research in this field.

  9. A qualitative study of psychological, social and behavioral barriers to appropriate food portion size control

    PubMed Central

    2013-01-01

    Background Given the worldwide prevalence of overweight and obesity, there is a clear need for meaningful practical healthy eating advice - not only in relation to food choice, but also on appropriate food portion sizes. As the majority of portion size research to date has been overwhelmingly quantitative in design, there is a clear need to qualitatively explore consumers’ views in order to fully understand how food portion size decisions are made. Using qualitative methodology this present study aimed to explore consumers’ views about factors influencing their portion size selection and consumption and to identify barriers to appropriate portion size control. Methods Ten focus groups with four to nine participants in each were formed with a total of 66 persons (aged 19–64 years) living on the island of Ireland. The semi-structured discussions elicited participants’ perceptions of suggested serving size guidance and explored the influence of personal, social and environmental factors on their food portion size consumption. Audiotapes of the discussions were professionally transcribed verbatim, loaded into NVivo 9, and analysed using an inductive thematic analysis procedure. Results The rich descriptive data derived from participants highlight that unhealthy portion size behaviors emanate from various psychological, social and behavioral factors. These bypass reflective and deliberative control, and converge to constitute significant barriers to healthy portion size control. Seven significant barriers to healthy portion size control were apparent: (1) lack of clarity and irrelevance of suggested serving size guidance; (2) guiltless eating; (3) lack of self-control over food cues; (4) distracted eating; (5) social pressures; (6) emotional eating rewards; and (7) quantification habits ingrained from childhood. Conclusions Portion size control strategies should empower consumers to overcome these effects so that the consumption of appropriate food portion sizes

  10. School District Size and Academic Performance: A Multi-Year Study

    ERIC Educational Resources Information Center

    Lenear, Bonnie Clariss

    2013-01-01

    Purpose: The purpose of this study was to determine the effect of school district size on the academic performance of Texas students. Specifically addressed was the extent to which differences in school district size were related to differences in student academic performance. The academic performance of the three major ethnic groups (i.e., Black,…

  11. Size, Expenditures, MAT6 Scores, and Dropout Rates: A Correlational Study of Arkansas School Districts.

    ERIC Educational Resources Information Center

    Kennedy, Robert L.; And Others

    This study investigated school district size, the consolidation of small school districts to make larger ones, and the linear relationships of school district size to expense per average daily attendance (ADA), basic and composite scores on the MAT6 standard achievement test, and secondary school dropout rate. Correlational analysis revealed that…

  12. Spectroscopic studies of the effect of the metal ions on the structure of mucin

    NASA Astrophysics Data System (ADS)

    Su, Yunlan; Xu, Yizhuang; Yang, Limin; Weng, Shifu; Soloway, R. D.; Wang, Dujin; Wu, Jinguang

    2009-02-01

    In this study the binding characteristics of mucin to calcium ion was examined by Fourier Transform Infrared (FT-IR), FT-Raman, Transmission Electron Microscope (TEM), and Dynamic Light Scattering (DLS) methods. The binding site of the interaction between mucin and calcium ions could be confirmed by FT-IR and FT-Raman techniques. When the concentration of Ca 2+ is relatively low, Ca 2+ prefers to coordinate with the carbohydrate moiety of mucins. When the concentration of Ca 2+ is high, Ca 2+ will also interact with the protein moiety of mucins. The morphology and the size of CaCl 2-mucin solution could be obtained by TEM and DLS methods, respectively. The hydrodynamic radius of CaCl 2-mucin mixture decreases compared with pure mucin solution, which may result from that Ca 2+ induces a contraction or folding of mucin chains to form a more compact configuration. The activity of the cations in modifying the structure of mucin may be of great importance for the biological function in normal and disease states.

  13. Metal ions diffusion through polymeric matrices: A total reflection X-ray fluorescence study

    NASA Astrophysics Data System (ADS)

    Boeykens, S.; Caracciolo, N.; D'Angelo, M. V.; Vázquez, C.

    2006-11-01

    This work proposes the use of X-ray fluorescence with total reflection geometry to explore the metal ions transport in aqueous hydrophilic polymer solutions. It is centered in the study of polymer concentration influence on ion diffusion. This subject is relevant to various and diverse applications, such as drug controlled release, microbiologic corrosion protection and enhanced oil recovery. It is anticipated that diffusion is influenced by various factors in these systems, including those specific to the diffusing species, such as charge, shape, molecular size, and those related to the structural complexity of the matrix as well as any specific interaction between the diffusing species and the matrix. The diffusion of nitrate salts of Ba and Mn (same charge, different hydrodynamic radii) through water-swollen polymeric solutions and gels in the 0.01% to 1% concentration ranges was investigated. The measurements of the metal concentration were performed by TXRF analysis using the scattered radiation by the sample as internal standard. Results are discussed according to different physical models for solute diffusion in polymeric solutions.

  14. A molecular dynamics study of phase transition in strongly coupled pair-ion plasmas

    SciTech Connect

    Baruah, Swati; Ganesh, R.; Avinash, K.

    2015-08-15

    Existence of phase transition in strongly coupled pair-ion plasmas with soft core is investigated. Extensive Molecular Dynamics (MD) simulations are performed in the canonical ensemble, for such plasmas, at different temperatures, to analyze phase stability. Our studies show interesting phase co-existence between liquid-like and vapor-like phases. The different phases are identified by calculating the ensemble averaged density. This and the corresponding critical properties are calculated directly from MD simulation. The critical temperature of vapor-liquid coexistence is obtained, and the corresponding critical value of density is also estimated for different sizes of the soft core. We have used a novel method that allows the location of phase coexistence through a constant density simulation in which the temperature is changed in a single time-step (quenching) in order to place the system in a thermodynamically and mechanically unstable state, resulting in spontaneous separation of two coexisting phases. The results obtained from this temperature quench MD method also show the coexistence of vapor-liquid phase in pair-ion plasmas. The critical exponents obtained directly from MD simulation are found to be in close agreement with the values predicted by a mean-field theory.

  15. Double-plasma enhanced carbon shield for spatial/interfacial controlled electrodes in lithium ion batteries via micro-sized silicon from wafer waste

    NASA Astrophysics Data System (ADS)

    Chen, Bing-Hong; Chuang, Shang-I.; Duh, Jenq-Gong

    2016-11-01

    Using spatial and interfacial control, the micro-sized silicon waste from wafer slurry could greatly increase its retention potential as a green resource for silicon-based anode in lithium ion batteries. Through step by step spatial and interfacial control for electrode, the cyclability of recycled waste gains potential performance from its original poor retention property. In the stages of spatial control, the electrode stabilizers of active, inactive and conductive additives were mixed into slurries for maintaining architecture and conductivity of electrode. In addition, a fusion electrode modification of interfacial control combines electrolyte additive, technique of double-plasma enhanced carbon shield (D-PECS) to convert the chemical bond states and to alter the formation of solid electrolyte interphases (SEIs) in the first cycle. The depth profiles of chemical composition from external into internal electrode illustrate that the fusion electrode modification not only forms a boundary to balance the interface between internal and external electrodes but also stabilizes the SEIs formation and soothe the expansion of micro-sized electrode. Through these effect approaches, the performance of micro-sized Si waste electrode can be boosted from its serious capacity degradation to potential retention (200 cycles, 1100 mAh/g) and better meet the requirements for facile and cost-effective in industrial production.

  16. Ion sputtering rates of W-, Ti- and Cr-carbides studied at different Ar + ion incidence angles

    NASA Astrophysics Data System (ADS)

    Zalar, A.; Kovač, J.; Praček, B.; Panjan, P.; Čeh, M.

    2008-08-01

    To study the ion sputtering rates of W-, Ti- and Cr-carbides, trilayer structures comprising C-graphite (59 nm)/WC (50 nm)/W (38 nm), C-graphite (56 nm)/TiC (40 nm)/Ti (34 nm) and C-graphite (46 nm)/C 3C 2 (60 nm)/Cr (69 nm) with a tolerance ±2% were sputter deposited onto smooth silicon substrates. Their precise structural and compositional characterization by transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) revealed that the WC and Cr 3C 2 layers were amorphous, while the TiC layer had a polycrystalline structure. The ion sputtering rates of all three carbides, amorphous carbon and polycrystalline Cr, Ti and W layers were determined by means of Auger electron spectroscopy depth profiling as a function of the angle of incidence of two symmetrically inclined 1 keV Ar + ion beams in the range between 22° and 82°. The sputtering rates were calculated from the known thicknesses of the layers and the sputtering times necessary to remove the individual layers. It was found that the sputtering rates of carbides, C-graphite and metals were strongly angle dependent. For the carbides in the range between 36° and 62° the highest ion sputtering rate was found for Cr 3C 2 and the lowest for TiC, while the values of the sputtering rates for WC were intermediate. The normalized sputtering yields calculated from the experimentally obtained data for all three carbides followed the trend of theoretical results obtained by calculation of the transport of ions in solids by the SRIM code. The sputtering yields are also presented in terms of atoms/ion. Our experimental data for two ion incidence angles of 22° and 49° and reported values of other authors for C-graphite and metals are mainly inside the estimated error of about ±20%. The influence of the ion-induced surface topography on the measured sputtering yields was estimated from the atomic force microscope (AFM) measurements at the intermediate points of

  17. Determination of phytate in high molecular weight, charged organic matrices by two-dimensional size exclusion-ion chromatography.

    PubMed

    Elkin, Kyle R; Slingsby, Rosanne; Bryant, Ray B

    2016-08-15

    A two-dimensional chromatography method for analyzing phytate or other ionic targets in matrices containing high molecular weight, charged organic species is described. Prior to quantification by anion exchange chromatography, the sample matrix was prepared by size exclusion chromatography, which removed the majority of the matrix. Quantification of phytate on the AS11-HC was sensitive (0.25µM, 0.17mg/l) and reproducible (4.6% RSD) allowing this method to provide baseline separation of phytate from a manure extract within 14min. The method is simple, requiring only sample filtering, reproducible (between-run variation 5% RSD) and linear from 0.38 to 76µM (0.25-50mg/l). The method is suitable for routine determination of phytate in high organic matrices such as manure extracts.

  18. High temperature annealing studies of strontium ion implanted glassy carbon

    NASA Astrophysics Data System (ADS)

    Odutemowo, O. S.; Malherbe, J. B.; Prinsloo, L.; Langa, D. F.; Wendler, E.

    2016-03-01

    Glassy carbon samples were implanted with 200 keV strontium ions to a fluence of 2 × 1016 ions/cm2 at room temperature. Analysis with Raman spectroscopy showed that ion bombardment amorphises the glassy carbon structure. Partial recovery of the glassy carbon structure was achieved after the implanted sample was vacuum annealed at 900 °C for 1 h. Annealing the strontium ion bombarded sample at 2000 °C for 5 h resulted in recovery of the glassy carbon substrate with the intensity of the D peak becoming lower than that of the pristine glassy carbon. Rutherford backscattering spectroscopy (RBS) showed that the implanted strontium diffused towards the surface of the glassy carbon after annealing the sample at 900 °C. This diffusion was also accompanied by loss of the implanted strontium. Comparison between the as-implanted and 900 °C depth profiles showed that less than 30% of the strontium was retained in the glassy carbon after heat treatment at 900 °C. The RBS profile after annealing at 2000 °C indicated that no strontium ions were retained after heat treatment at this temperature.

  19. Microstructural evolution of RPV steels under proton and ion irradiation studied by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Wu, Y. C.; Liu, X. B.; Wang, R. S.; Nagai, Y.; Inoue, K.; Shimizu, Y.; Toyama, T.

    2015-03-01

    The microstructural evolution of reactor pressure vessel (RPV) steels induced by proton and heavy ion irradiation at low temperature (∼373 K) has been investigated using positron annihilation spectroscopy (PAS), atom probe tomography (APT), transmission electron microscopy (TEM) and nanoindentation. The PAS results indicated that both proton and heavy ion irradiation produce a large number of matrix defects, which contain small-size defects such as vacancies, vacancy-solute complexes, dislocation loops, and large-size vacancy clusters. In proton irradiated RPV steels, the size and number density of vacancy cluster defects increased rapidly with increasing dose due to the migration and agglomeration of vacancies. In contrast, for Fe ion irradiated steels, high density, larger size vacancy clusters can be easily induced at low dose, showing saturation in PAS response with increasing dose. No clear precipitates, solute-enriched clusters or other forms of solute segregation were observed by APT. Furthermore, dislocation loops were observed by TEM after 1.0 dpa, 240 keV proton irradiation, and an increase of the average nanoindentation hardness was found. It is suggested that ion irradiation produces many point defects and vacancy cluster defects, which induce the formation of dislocation loops and the increase of nanoindentation hardness.

  20. Use of LEED, Auger emission spectroscopy and field ion microscopy in microstructural studies.

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Buckley, D. H.; Pepper, S. V.; Brainard, W. A.

    1972-01-01

    The studies reported were conducted to gain a fundamental understanding of adhesion and dynamic friction on an atomic or microscopic level. Fundamental aspects of low energy electron diffraction (LEED), Auger emission spectroscopy (AES), and field ion microscopy (FIM) are discussed. Typical results of studies conducted are considered, giving attention to LEED-AES experiments, pin and disk experiments, and field ion microscope investigations.

  1. Biosynthesis of Cd-bound phytochelatins by Phaeodactylum tricornutum and their speciation by size-exclusion chromatography and ion-pair chromatography coupled to ICP-MS.

    PubMed

    Loreti, Valeria; Toncelli, Daniel; Morelli, Elisabetta; Scarano, Gioacchino; Bettmer, Jörg

    2005-10-01

    Cd-bound phytochelatins (Cd-PCs) have been synthesised by incubation of Phaeodactylum tricornutum cell cultures with Cd and purified by size-exclusion chromatography-UV-Vis. These complexes, which were identified in previous work, have now been used as model substances to develop and optimise ion-pair chromatography (IPC) coupled to inductively coupled plasma-mass spectrometry (ICP-MS) for analysis of Cd-PCs. Subsequent analysis of samples taken from Silene vulgaris plants cultivated under heavy metal stress conditions revealed Cd signals but no Cd-PC signals. By use of isotopically enriched (116)Cd-PCs the sample preparation steps were verified to determine the stability of the analytes. We observed species transformation between Cd-PCs and other unidentified Cd complexes. Consequently, the kinetic and thermodynamic lability of Cd-PCs are decisive factors in their detection.

  2. A study on geometry effect of transmission coil for micro size magnetic induction coil

    NASA Astrophysics Data System (ADS)

    Lee, Kyung Hwa; Jun, Byoung Ok; Kim, Seunguk; Lee, Gwang Jun; Ryu, Mingyu; Choi, Ji-Woong; Jang, Jae Eun

    2016-05-01

    The effects of transmission (Tx) coil structure have been studied for micro-size magnetic induction coil. The size of the receiving (Rx) coil should be shrunk to the micrometer level for the various new applications such as micro-robot and wireless body implanted devices. In case of the macro-scale magnetic induction coil, the power transmission efficiency is generally considered to be higher as the inductance of the transmission coil became larger; however, the large size difference between macro-size Tx coil and micro-size Rx coil can decrease the power transmission efficiency due to the difference of resonance frequency. Here, we study a correlation of the power transmission with the size and distance between the macro-size Tx and micro-size Rx coils using magnetic induction technique. The maximum power efficiency was 0.28/0.23/0.13/0.12% at the distance of 0.3/1/3/5 cm between Rx and Tx coil. In addition, more efficient wireless power transferring method is suggested with a floating coil for the body implantable devices. The voltage output increased up to 5.4 mV than the original one Tx coil system. The results demonstrated the foundational wireless power transferring system with enhanced power efficiency.

  3. Kinetic study of ion-acoustic plasma vortices

    SciTech Connect

    Khan, S. A.; Aman-ur-Rehman; Mendonca, J. T.

    2014-09-15

    The kinetic theory of electron plasma waves with finite orbital angular momentum has recently been introduced by Mendonca. This model shows possibility of new kind of plasma waves and instabilities. We have extended the theory to ion-acoustic plasma vortices carrying orbital angular momentum. The dispersion equation is derived under paraxial approximation which exhibits a kind of linear vortices and their Landau damping. The numerical solutions are obtained and compared with analytical results which are in good agreement. The physical interpretation of the ion-acoustic plasma vortices and their Landau resonance conditions are given for typical case of Maxwellian plasmas.

  4. Ion irradiation tolerance of graphene as studied by atomistic simulations

    SciTech Connect

    Ahlgren, E. H.; Lehtinen, O.; Kotakoski, J.; Krasheninnikov, A. V.

    2012-06-04

    As impermeable to gas molecules and at the same time transparent to high-energy ions, graphene has been suggested as a window material for separating a high-vacuum ion beam system from targets kept at ambient conditions. However, accumulation of irradiation-induced damage in the graphene membrane may give rise to its mechanical failure. Using atomistic simulations, we demonstrate that irradiated graphene even with a high vacancy concentration does not show signs of such instability, indicating a considerable robustness of graphene windows. We further show that upper and lower estimates for the irradiation damage in graphene can be set using a simple model.

  5. Study of holograms made with saccharides and iron ions

    NASA Astrophysics Data System (ADS)

    Ordóñez-Padilla, M. M.; Olivares-Pérez, A.; Dorantes-García, V.; Vallejo-Mendoza, R.; Fuentes-Tapia, I.

    2012-03-01

    We present the performance characterization of photosensitive film emulsions prepared with saccharides like: pectin, fructose and sugar (Glass ®), at certain physicochemical conditions for holographic recording. The photo-oxidation was carried out with concentrations of iron ions, Fe+3. We analyzed the parameters of the diffraction efficiencies of each grating constructed with saccharides film. The work was to achieve stability and non-toxicity of the films prepared easily with water-Fe ions. We performed an experimental comparison of the holographic films capacity between the three saccharides.

  6. Perceptions of work environment priorities: Are there any differences by company size? An ecological study

    PubMed Central

    Nordlöf, Hasse; Wijk, Katarina; Westergren, Karl-Erik

    2015-01-01

    BACKGROUND: Earlier studies suggest that the quality of handling occupational health and safety (OHS) activities differs between companies of different sizes. Company size is a proxy variable for other variables affecting OHS performance. OBJECTIVE: The objective of this study was to investigate if there is an association between company size and perceptions of work environment prioritizations. METHODS: Data from 106 small- and medium-sized Swedish manufacturing companies was collected. One manager and one safety delegate at each company rated different aspects of their companies’ work environment prioritizations with a 43-item questionnaire. Ratings were aggregated to a summary statistic for each company before analysis. RESULTS: No significant differences in perceptions of priority were found to be associated with company sizes. This is in contrast to earlier studies of objective differences. The respondents in small companies, however, showed significantly greater consensus in their ratings. CONCLUSIONS: Company size does not appear to be associated with perceptions of work environment prioritizations. Company size is an important proxy variable to study in order to understand what factors enable and obstruct safe and healthy workplaces. The work presented here should be viewed as an initial exploration to serve as direction for future academic work. PMID:26409368

  7. PARTICLE SIZE DISTRIBUTIONS FROM SELECT RESIDENCES PARTICIPATING IN THE NERL RTP PM PANEL STUDY

    EPA Science Inventory

    Particle Size Distributions from Select Residences Participating in the NERL RTP PM Panel Study. Alan Vette, Ronald Williams, and Michael Riediker, U.S. Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC 27711; Jonathan Thornburg...

  8. First principles study of nanostructured TiS2 electrodes for Na and Mg ion storage

    NASA Astrophysics Data System (ADS)

    Li, S. N.; Liu, J. B.; Liu, B. X.

    2016-07-01

    The development of competitive Na- and Mg-ion batteries (NIBs and MIBs) with performance comparable to Li-ion batteries is hindered by the major challenge of finding advanced electrode materials. In this work, nanostructured TiS2 electrodes including nanosheets, nanoribbons and nanotubes are shown by first principles calculations to achieve improved Na and Mg ion diffusion as compared with the bulk phase. Comparative studies between Li, Na, and Mg reveal that the diffusion kinetics of Na ions would especially benefit from the nanostructure design of TiS2. More specifically, the Na ion diffusivity turns out to be considerably higher than Li ion diffusivity, which is opposite to that observed in bulk TiS2. However, in the case of Mg ions, fast diffusion is still beyond attainment since a relatively high degree of interaction is expected between Mg and the S atoms. Edge-induced modifications of diffusion properties appear in both Na and Mg ions, while the mobility of Li ions along the ribbon edges may not be as appealing. Effects of the curvature of nanotubes on the adsorption strength and ion conductivity are also explored. Our results highlight the nanostructure design as a rich playground for exploring electrodes in NIBs and MIBs.

  9. Theoretical studies of defect formation and target heating by intense pulsed ion beams

    NASA Astrophysics Data System (ADS)

    Barnard, J. J.; Schenkel, T.; Persaud, A.; Seidl, P. A.; Friedman, A.; Grote, D. P.; Davidson, R. C.; Gilson, E. P.; Kaganovich, I.

    2015-11-01

    We present results of three studies related to experiments on NDCX-II, the Neutralized Drift Compression Experiment, a short-pulse (~ 1ns), high-current (~ 70A) linear accelerator for 1.2 MeV ions at LBNL. These include: (a) Coupled transverse and longitudinal envelope calculations of the final non-neutral ion beam transport, followed by neutralized drift and final focus, for a number of focus and drift lengths and with a series of ion species (Z =1-19). Predicted target fluences were obtained and target temperatures in the 1 eV range estimated. (b) HYDRA simulations of the target response for Li and He ions and for Al and Au targets at various ion fluences (up to 1012 ions/pulse/mm2) and pulse durations, benchmarking temperature estimates from the envelope calculations. (c) Crystal-Trim simulations of ion channeling through single-crystal lattices, with comparisons to ion transmission data as a function of orientation angle of the crystal foil and for different ion intensities and ion species. This work was performed under the auspices of the U.S. DOE under contracts DE-AC52-07NA27344 (LLNL), DE-AC02-05CH11231 (LBNL) and DE-AC02-76CH0307 (PPPL) and was supported by the US DOE Office of Science, Fusion Energy Sciences. LLNL-ABS-67521.

  10. A Pilot Study of Ion - Molecule Reactions at Temperatures Relevant to the Atmosphere of Titan

    NASA Astrophysics Data System (ADS)

    Zymak, Illia; Žabka, Ján; Polášek, Miroslav; Španěl, Patrik; Smith, David

    2016-11-01

    Reliable theoretical models of the chemical kinetics of the ionosphere of Saturn's moon, Titan, is highly dependent on the precision of the rates of the reactions of ambient ions with hydrocarbon molecules at relevant temperatures. A Variable Temperature Selected Ions Flow Tube technique, which has been developed primarily to study these reactions at temperatures within the range of 200-330 K, is briefly described. The flow tube temperature regulation system and the thermalisation of ions are also discussed. Preliminary studies of two reactions have been carried out to check the reliability and efficacy of kinetics measurements: (i) Rate constants of the reaction of CH3 + ions with molecular oxygen were measured at different temperatures, which indicate values in agreement with previous ion cyclotron resonance measurements ostensibly made at 300 K. (ii) Formation of CH3 + ions in the reaction of N2 + ions with CH4 molecules were studied at temperatures within the range 240-310 K which showed a small but statistically significant decrease of the ratio of product CH3 + ions to reactant N2 + ions with reaction temperature.

  11. A Pilot Study of Ion - Molecule Reactions at Temperatures Relevant to the Atmosphere of Titan

    NASA Astrophysics Data System (ADS)

    Zymak, Illia; Žabka, Ján; Polášek, Miroslav; Španěl, Patrik; Smith, David

    2016-04-01

    Reliable theoretical models of the chemical kinetics of the ionosphere of Saturn's moon, Titan, is highly dependent on the precision of the rates of the reactions of ambient ions with hydrocarbon molecules at relevant temperatures. A Variable Temperature Selected Ions Flow Tube technique, which has been developed primarily to study these reactions at temperatures within the range of 200-330 K, is briefly described. The flow tube temperature regulation system and the thermalisation of ions are also discussed. Preliminary studies of two reactions have been carried out to check the reliability and efficacy of kinetics measurements: (i) Rate constants of the reaction of CH3 + ions with molecular oxygen were measured at different temperatures, which indicate values in agreement with previous ion cyclotron resonance measurements ostensibly made at 300 K. (ii) Formation of CH3 + ions in the reaction of N2 + ions with CH4 molecules were studied at temperatures within the range 240-310 K which showed a small but statistically significant decrease of the ratio of product CH3 + ions to reactant N2 + ions with reaction temperature.

  12. Thermal-stability studies of electrode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Jiang, Junwei

    2005-07-01

    The thermal stability of lithium-ion batteries has recently attracted attention for two major reasons. (1) Attempts to make large-size cells used in power tools, E-bikes and EVs. Large cells have lower surface area to volume ratios and hence heat dissipation is more problematic than 18650-size cells. Safety problems, therefore, for large cells are more serious. (2) Next generation high-capacity electrodes will increase the energy density of lithium-ion cells meaning even an 18650-size cell may face safety concerns. This thesis presents studies of the thermal stability of electrode materials in electrolytes to understand their reactivity. A search for new positive electrode materials with high thermal stability was made. The thermal stability of two common electrode materials (Li0.81 C6 and Li0.5CoO2) in lithium-ion cells was studied by Accelerating Rate Calorimeter (ARC). Li0.81C 6 has much lower reactivity with lithium bis(oxalato)borate (LiBOB) electrolyte compared to LiPF6 electrolyte. It is not the case, however, for Li0.5CoO2. Oven tests of full LiCoO 2/C 18650-size cells with LiBOB or LiPF6 electrolytes, confirmed the ARC results. ARC was then used to study the reactivity of existing electrode materials. The thermal stability of a negative electrode material was found to increase with the binding energy of Li atoms hosted in the material. Li0.5VO 2 (B) has a higher lithium binding energy (2.45 eV vs. Li) than Li 0.81C6 (0.1 eV vs. Li) and Li7Ti5O 12 (1.55 eV) and it shows the highest thermal stability in EC/DEC among the three materials. The reactivity of two existing positive electrode materials, LiMn2O4 and LiFePO4, was studied. Cell systems expected to be highly tolerant to thermal abuse were suggested: LiFePO 4/C or Li4Ti5O12 in LiBOB electrolytes. The system, x Li[Ni1/2Mn1/2]O2 • y LiCoO2 • z Li[Li1/3Mn2/3]O2 (x + y + z = 1), was explored for new positive electrode materials with large capacity and high thermal stability. Li[(Ni0.5Mn0.5) xCo1-x]O2 (0

  13. Study of the normal heart size in Northwest part of Iranian population: a cadaveric study

    PubMed Central

    Mohammadi, Shabnam; Hedjazi, Arya; Sajjadian, Maryam; Ghoroubi, Naser; Mohammadi, Maryam; Erfani, Saeed

    2016-01-01

    Introduction: The heart is in a muscular organ in the middle mediastinum. According to our knowledge, there is no standard data about the anthropologic parameters of normal Iranian hearts. Hence, the aim of the present study was to investigate the normal heart size in Iranian cadavers. Methods: In a cross-sectional study, 550 cadavers (104 female/446 male) from June 2014 to July 2015 in the Razavi Khorasan province of Iran were included in the study. After approval of the Ethical Committee, cadavers were divided into 10 groups based on age groups. Length, width, weight, chordae tendineae, papillary muscles, and heart valves were measured using vernier caliper. Finally, data were analyzed using SPSS software. Results: The mean values of the demographic data were as follows: age= 42.12 ± 21.34 years; weight = 60.38 ± 15.32 kg; height = 158.14 ± 23.77 cm; and BMI = 24.66 ± 17.60 kg/m2. The mean values of the heart length, width, chordae tendineae, pupillary muscles, weight, and index of the heart were 11.41 ± 2.15 cm, 8.21 ± 4.38 cm, 19.41 ± 6.70, 5.74 ± 1.96, 247.78 ± 62.27 grams, and 5.74 ± 1.96, respectively. In addition, the circumference of the tricuspid valve, circumference of the mitral valves, and tricuspid and mitral areas were 8.80 ± 1.11 cm, 9.43 ± 1.44 cm, 4.11 ± 0.71 cm2, and 4.50 ± 0.90 cm2, respectively. Conclusion: Mean values of the heart’s length and width was similar to previous reports from western population. The circumference of the tricuspid valve was less than the textbook’s data, while circumference of the mitral valves was more than it. The study findings provide valuable information about standard data of the heart in the Iranian population, which is useful for surgeons as well as anthropologists. However, multi-center studies with a larger sample size are required to complete data about anatomical characteristics of normal hearts. PMID:27777697

  14. Structural and magnetic studies of thin Fe57 films formed by ion beam assisted deposition

    NASA Astrophysics Data System (ADS)

    Lyadov, N. M.; Bazarov, V. V.; Vagizov, F. G.; Vakhitov, I. R.; Dulov, E. N.; Kashapov, R. N.; Noskov, A. I.; Khaibullin, R. I.; Shustov, V. A.; Faizrakhmanov, I. A.

    2016-08-01

    Thin Fe57 films with the thickness of 120 nm have been prepared on glass substrates by using the ion-beam-assisted deposition technique. X-ray diffraction, electron microdiffraction and Mössbauer spectroscopy studies have shown that as-deposited films are in a stressful nanostructured state containing the nanoscaled inclusions of α-phase iron with the size of ∼10 nm. Room temperature in-plane and out-of-plane magnetization measurements confirmed the presence of the magnetic α-phase in the iron film and indicated the strong effect of residual stresses on magnetic properties of the film as well. Subsequent thermal annealing of iron films in vacuum at the temperature of 450 °C stimulates the growth of α-phase Fe crystallites with the size of up to 20 nm. However, electron microdiffraction and Mössbauer spectroscopic data have shown the partial oxidation and carbonization of the iron film during annealing. The stress disappeared after annealing of the film. The magnetic behaviour of the annealed samples was characterized by the magnetic hysteresis loop with the coercive field of ∼10 mT and the saturation magnetization decreased slightly in comparison with the α-phase Fe magnetization due to small oxidation of the film.

  15. A study of ion emissions in MAVEN/IUVS data

    NASA Astrophysics Data System (ADS)

    Connour, Kyle; Schneider, Nicholas M.; Deighan, Justin; Jain, Sonal Kumar; Stevens, Michael H.; Evans, Scott; Stewart, Ian; Crismani, Matteo; Stiepen, Arnaud; Chaffin, Michael S.; McClintock, William; Holsclaw, Gregory; Lefevre, Franck; Lo, Daniel; Clarke, John T.; Mayyasi, Majd A.; Montmessin, Franck; Jakosky, Bruce

    2016-10-01

    The Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile EvolutionN (MAVEN) mission is designed to measure radiances of several of the most abundant species present in Mars' atmosphere. Many spectral features are associated with ions; one of the most prominent spectral features in the mid-ultraviolet region is the CO2+ Ultraviolet Doublet (UVD) at 289 nm. However this emission, and many others, results from several radiative processes, some of which originate from the ionization process and is therefore not diagnostic of the ion densities. Several other emissions are diagnostic of ion densities, especially at high altitudes, and therefore lend themselves to density retrievals based on inclusion of all radiative processes. The most promising of these is the Fox-Duffendack-Barker (FDB) (3,0) band at 314 nm, near the long-wavelength limit of the IUVS instrument. We report on a new process for performing density retrievals of CO2+ with particular attention to the credibility of high-altitude signal in the FDB bands as well as the associated uncertainties. We also investigate the feasibility of C+ and other ion density retrievals.

  16. Chromium ion plating studies for enhancement of bearing lifetime

    NASA Technical Reports Server (NTRS)

    Davis, J. H.

    1982-01-01

    Six 440-C hardened stainless steel roller bearing test rods were ion plated with various chromium films of thicknesses from .2 microns to 7 microns. The thinner (approximately .2 microns) coating sample had 3 times the fatigue life of the unplated (standard) specimens. Contrastingly, the samples having thicker coatings (several microns) had short fatigue lives (about 3% of the unplated standard).

  17. Studies on the Effects of Gaseous Ions on Plant Growth

    PubMed Central

    Krueger, Albert P.; Beckett, J. C.; Andriese, Paul C.; Kotaka, Sadao

    1962-01-01

    Air pollutants seriously interfere with the maintenance of unipolar ionized atmospheres required in experimenting with the biological effects of gaseous ions. The construction and operation of an air purification unit designed to reduce air pollution to tolerable levels are described; it has functioned satisfactorily in conducting experiments with plants and animals. PMID:14459882

  18. Optical studies of ion-beam synthesized metal alloy nanoparticles

    SciTech Connect

    Magudapathy, P. Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K.

    2015-06-24

    Au{sub x}Ag{sub 1-x} alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ∼45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar{sup +} ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar{sup +} ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of Au{sub x}Ag{sub 1-x} nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

  19. One-year observations of size distribution characteristics of major aerosol constituents at a coastal receptor site in Hong Kong - Part 1: Inorganic ions and oxalate

    NASA Astrophysics Data System (ADS)

    Bian, Q.; Huang, X. H. H.; Yu, J. Z.

    2014-09-01

    Size distribution data of major aerosol constituents are essential in source apportioning of visibility degradation, testing and verification of air quality models incorporating aerosols. We report here 1-year observations of mass size distributions of major inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, magnesium and calcium) and oxalate at a coastal suburban receptor site in Hong Kong, China. A total of 43 sets of size-segregated samples in the size range of 0.056-18 μm were collected from March 2011 to February 2012. The size distributions of sulfate, ammonium, potassium and oxalate were characterized by a dominant droplet mode with a mass mean aerodynamic diameter (MMAD) in the range of ~ 0.7-0.9 μm. Oxalate had a slightly larger MMAD than sulfate on days with temperatures above 22 °C as a result of the process of volatilization and repartitioning. Nitrate was mostly dominated by the coarse mode but enhanced presence in fine mode was detected on winter days with lower temperature and lower concentrations of sea salt and soil particles. This data set reveals an inversely proportional relationship between the fraction of nitrate in the fine mode and product of the sum of sodium and calcium in equivalent concentrations and the dissociation constant of ammonium nitrate (i.e., (1/([Na+] + 2[Ca2+]) × (1/Ke')) when Pn_fine is significant (> 10%). The seasonal variation observed for sea salt aerosol abundance, with lower values in summer and winter, is possibly linked with the lower marine salinities in these two seasons. Positive matrix factorization was applied to estimate the relative contributions of local formation and transport to the observed ambient sulfate level through the use of the combined data sets of size-segregated sulfate and select gaseous air pollutants. On average, the regional/super-regional transport of air pollutants was the dominant source at this receptor site, especially on high-sulfate days while local formation

  20. One-year observations of size distribution characteristics of major aerosol constituents at a coastal receptor site in Hong Kong - Part 1: Inorganic ions and oxalate

    NASA Astrophysics Data System (ADS)

    Bian, Q.; Huang, X. H. H.; Yu, J. Z.

    2014-01-01

    Size distribution data of major aerosol constituents are essential in source apportioning of visibility degradation, testing and verification of air quality models incorporating aerosols. We report here one-year observations of mass size distributions of major inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, magnesium and calcium) and oxalate at a coastal suburban receptor site in Hong Kong, China. A total of 43 sets of size segregated samples in the size range of 0.056-18 μm were collected from March 2011 to February 2012. The size distributions of sulfate, ammonium, potassium and oxalate were characterized by a dominant droplet mode with a mass mean aerodynamic diameter (MMAD) in the range of ~0.7-0.9 μm. Oxalate had a slightly larger MMAD than sulfate on days with temperatures above 22 °C as a result of the process of volatilization and repartitioning. Nitrate was mostly dominated by the coarse mode but enhanced presence in fine mode was detected on winter days with lower temperature and lower concentrations of sea salt and soil particles. This data set reveals an inversely proportional relationship between the fraction of nitrate in the fine mode and product of the sum of sodium and calcium in equivalent concentrations and the dissociation constant of ammonium nitrate (i.e., (1/[Na+] + 2[Ca2+]) × (1/Ke')). The seasonal variation observed for sea salt aerosol abundance, with lower values in summer and winter, is possibly linked with the lower marine salinities in these two seasons. Positive matrix factorization was applied to estimate the relative contributions of local formation and transport to the observed ambient sulfate level through the use of the combined datasets of size-segregated sulfate and select gaseous air pollutants. On average, the regional/super-regional transport of air pollutants was the dominant source at this receptor site, especially on high sulfate days, while local formation processes contributed approximately

  1. Studies on a Q/A selector for the SECRAL electron cyclotron resonance ion source.

    PubMed

    Yang, Y; Sun, L T; Feng, Y C; Fang, X; Lu, W; Zhang, W H; Cao, Y; Zhang, X Z; Zhao, H W

    2014-08-01

    Electron cyclotron resonance ion sources are widely used in heavy ion accelerators in the world because they are capable of producing high current beams of highly charged ions. However, the design of the Q/A selector system for these devices is challenging, because it must have a sufficient ion resolution while controlling the beam emittance growth. Moreover, this system has to be matched for a wide range of ion beam species with different intensities. In this paper, research on the Q/A selector system at the SECRAL (Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou) platform both in experiment and simulation is presented. Based on this study, a new Q/A selector system has been designed for SECRAL II. The features of the new design including beam simulations are also presented.

  2. Study on the Growth and the Photosynthetic Characteristics of Low Energy C+ Ion Implantation on Peanut

    PubMed Central

    Han, Yuguo; Xu, Lei; Yang, Peiling; Ren, Shumei

    2013-01-01

    Employing the Nonghua 5 peanut as experimental material, the effects of low energy C+ ion implantation on caulis height, root length, dry weight, photosynthetic characteristics and leaf water use efficiency (WUE) of Peanut Ml Generation were studied. Four fluences were observed in the experiment. The results showed that ion implantation harmed the peanut seeds because caulis height, root length and dry weight all were lower in the treatments than in CK, and the harm was aggravated with the increase of ion fluence. Both Pn and Tr show a saddle-shape curve due to midday depression of photosynthesis. Low fluence of low energy C+ ion implantation could increase the diurnal average Pn of peanut. The diurnal variation of Tr did not change as significantly as Pn. The light saturation point (LSP) was restrained by the ions. After low energy C+ ion implantation, WUE was enhanced. When the fluence increased to a certain level, the WUE began to decrease. PMID:23861939

  3. Laboratory Studies of Thermal Energy Charge Transfer of Silicon and Iron Ions in Astrophysical Plasmas

    NASA Technical Reports Server (NTRS)

    Kwong, Victor H. S.

    1996-01-01

    Charge transfer at electron-volt energies between multiply charged atomic ions and neutral atoms and molecules is of considerable importance in astrophysics, plasma physics, and in particular, fusion plasmas. In the year covered by this report, several major tasks were completed. These include: (1) the re-calibration of the ion gauge to measure the absolute particle densities of H2, He, N2, and CO for our current measurements; (2) the analysis of data for charge transfer reactions of N(exp 2 plus) ion and He, H2, N2, and CO; (3) measurement and data analysis of the charge transfer reaction of (Fe(exp 2 plus) ion and H2; (4) charge transfer measurement of Fe(exp 2 plus) ion and H2; and (5) redesign and modification of the ion detection and data acquisition system for the low energy beam facility (reflection time of flight mass spectrometer) dedicated to the study of state select charge transfer.

  4. Thermodynamics and kinetics of ion speciation in supercritical aqueous solutions: A molecular based study

    SciTech Connect

    Chialvo, A.A.; Cummings, P.T. |; Simonson, J.M.; Mesmer, R.E.

    1997-05-01

    Molecular simulation of infinitely dilute NaCl aqueous solutions are performed to study the Na{sup +}/Cl{sup -} ion pairing in a polarizable and a nonpolarizable solvent at supercritical conditions. The Simple Point Charge, Pettitt-Rossky, and Fumi-Tosi models for the water-water, ion-water, and ion-ion interactions are used in determining the degree of dissociation, its temperature and density dependence, and the kinetics of the interconversion between ion-pair configurations in a nonpolarizable medium. To assess the effect of the solvent polarizability on the stability of the ion-pair configurations, we replace the Simple Point Charge by the Polarizable Point Charge water model and determine the anion-cation potential of mean force at T{sub r}=1.20 and {rho}{sub r}=1.5.

  5. Coupled ion and network dynamics in polymer electrolytes: Monte Carlo study of a lattice model

    NASA Astrophysics Data System (ADS)

    Dürr, O.; Dieterich, W.; Nitzan, A.

    2004-12-01

    Monte Carlo simulations are used to study ion and polymer chain dynamic properties in a simplified lattice model with only one species of mobile ions. The ions interact attractively with specific beads in the host chains, while polymer beads repel each other. Cross linking of chains by the ions reduces chain mobilities which in turn suppresses ionic diffusion. Diffusion constants for ions and chains as a function of temperature follow the Vogel-Tammann-Fulcher (VTF) law with a common VTF temperature at low ion concentration, but both decouple at higher concentrations, in agreement with experimental observations. Our model allows us to introduce pressure as an independent variable through calculations of the equation of state using the quasichemical approximation, and to detect an exponential pressure dependence of the ionic diffusion.

  6. Studies on a Q/A selector for the SECRAL electron cyclotron resonance ion source

    SciTech Connect

    Yang, Y.; Sun, L. T.; Feng, Y. C.; Fang, X.; Lu, W.; Zhang, W. H.; Cao, Y.; Zhang, X. Z.; Zhao, H. W.

    2014-08-15

    Electron cyclotron resonance ion sources are widely used in heavy ion accelerators in the world because they are capable of producing high current beams of highly charged ions. However, the design of the Q/A selector system for these devices is challenging, because it must have a sufficient ion resolution while controlling the beam emittance growth. Moreover, this system has to be matched for a wide range of ion beam species with different intensities. In this paper, research on the Q/A selector system at the SECRAL (Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou) platform both in experiment and simulation is presented. Based on this study, a new Q/A selector system has been designed for SECRAL II. The features of the new design including beam simulations are also presented.

  7. Time-resolved positron annihilation spectroscopy study of relaxation dynamics of ion damage in fused quartz

    NASA Astrophysics Data System (ADS)

    Tsuchida, Hidetsugu; Mizuno, Shohei; Tsutsumi, Hironori; Kinomura, Atsushi; Suzuki, Ryoichi; Itoh, Akio

    2016-05-01

    Relaxation dynamics of ion damage in fused quartz is investigated by our newly developed pump–probe technique combining energetic ions (pump) with slow positrons (probe). This method enables determination of time-resolved positron lifetime. We study the time-dependent relaxation of ion damage, by analyzing the intensity variation in the ortho-positronium lifetime component associated with irradiation damage. For irradiation with 160 keV He ions in the temperature range of 300–573 K, the positron annihilation lifetime spectra are obtained as a function of time after ion irradiation. We observe that the relaxation time of ion damage is strongly influenced by specimen temperatures; the relaxation time constant is approximately 400 ms at room temperature (300 K) and becomes smaller with an increasing temperature. Analysis for the effect of temperature on damage accumulation reveals that the activation energy for thermal annealing of the observed damage is approximately 0.1 eV.

  8. Radiotracer studies on calcium ion-selective electrode membranes based on poly(vinyl chloride) matrices.

    PubMed

    Craggs, A; Moody, G J; Thomas, J D; Willcox, A

    Radiotracer studies with (45)Ca and (36)Cl demonstrate that PVC matrix membranes containing Orion 92-20-02 liquid calcium ion-exchanger are permselective to counter-cations. Diffusion coefficients are quoted for the migration of (45)Ca between pairs of calcium solutions and are discussed in terms of solution concentration, membrane thickness and concentration level of sensor in the membrane. Migration of calcium ions from calcium chloride solution to a Group (II) metal chloride solution through a PVC membrane containing calcium liquid ion-exchanger is discussed in terms of solvent extraction and electrode selectivity coefficient parameters. Thus, magnesium, strontium and barium ions appear to inhibit migration through the membrane by their low affinity for the membrane liquid ion-exchanger sites, while the inhibition by beryllium ions is attributed to site blockage by the strong affinity of dialkylphosphate sites for beryllium.

  9. Studies on a Q/A selector for the SECRAL electron cyclotron resonance ion source.

    PubMed

    Yang, Y; Sun, L T; Feng, Y C; Fang, X; Lu, W; Zhang, W H; Cao, Y; Zhang, X Z; Zhao, H W

    2014-08-01

    Electron cyclotron resonance ion sources are widely used in heavy ion accelerators in the world because they are capable of producing high current beams of highly charged ions. However, the design of the Q/A selector system for these devices is challenging, because it must have a sufficient ion resolution while controlling the beam emittance growth. Moreover, this system has to be matched for a wide range of ion beam species with different intensities. In this paper, research on the Q/A selector system at the SECRAL (Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou) platform both in experiment and simulation is presented. Based on this study, a new Q/A selector system has been designed for SECRAL II. The features of the new design including beam simulations are also presented. PMID:25173256

  10. Reliability studies on NPN RF power transistors under swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Pushpa, N.; Praveen, K. C.; Gnana Prakash, A. P.; Naik, P. S.; Cressler, John D.; Gupta, S. K.; Revannasiddaiah, D.

    2012-02-01

    NPN RF power transistors were irradiated with 140 MeV Si 10+ ions, 100 MeV F 8+ ions, 50 MeV Li 3+ ions and Co-60 gamma radiation in the dose range from 100 krad to 100 Mrad. The transistor characteristics are studied before and after irradiation from which the parameters such as Gummel characteristics, excess base current (Δ IB = IBpost - IBpre), dc current gain ( hFE), transconductance ( gm) and collector-saturation current ( ICSat) are determined. The degradation observed in the electrical characteristics is almost the same for different types of ion irradiated NPN RF power transistors with similar total doses although there is a large difference in the linear energy transfer (LET) of the ions. Further, it was observed more degradation in DC I- V characteristics of ion irradiated devices than the Co-60 gamma irradiated devices for higher doses.

  11. Size and space controlled hexagonal arrays of superparamagnetic iron oxide nanodots: magnetic studies and application

    PubMed Central

    Ghoshal, Tandra; Maity, Tuhin; Senthamaraikannan, Ramsankar; Shaw, Matthew T.; Carolan, Patrick; Holmes, Justin D.; Roy, Saibal; Morris, Michael A.

    2013-01-01

    Highly dense hexagonally arranged iron oxide nanodots array were fabricated using PS-b-PEO self-assembled patterns. The copolymer molecular weight, composition and choice of annealing solvent/s allows dimensional and structural control of the nanopatterns at large scale. A mechanism is proposed to create scaffolds through degradation and/or modification of cylindrical domains. A methodology based on selective metal ion inclusion and subsequent processing was used to create iron oxide nanodots array. The nanodots have uniform size and shape and their placement mimics the original self-assembled nanopatterns. For the first time these precisely defined and size selective systems of ordered nanodots allow careful investigation of magnetic properties in dimensions from 50 nm to 10 nm, which delineate the nanodots are superparamagnetic, well-isolated and size monodispersed. This diameter/spacing controlled iron oxide nanodots systems were demonstrated as a resistant mask over silicon to fabricate densely packed, identical ordered, high aspect ratio silicon nanopillars and nanowire features. PMID:24072037

  12. Interaction of monovalent ions with the water liquid-vapor interface - A molecular dynamics study

    NASA Technical Reports Server (NTRS)

    Wilson, Michael A.; Pohorille, Andrew

    1991-01-01

    Results of molecular dynamics calculations are presented for a series of ions at infinite dilution near the water liquid-vapor interface. The free energies of ion transfer from the bulk to the interface are discussed, as are the accompanying changes of water structure at the surface and ion mobilities as a function of their proximity to the interface. It is shown that simple dielectric models do not provide an accurate description of ions at the water surface. The results of the study should be useful in the development of better models incorporating the shape and molecular structure of the interface.

  13. Allometry and size control: what can studies of body size regulation teach us about the evolution of morphological scaling relationships?

    PubMed

    Mirth, Christen K; Anthony Frankino, W; Shingleton, Alexander W

    2016-02-01

    The relationship between organ and body size, known as morphological allometry, has fascinated biologists for over a century because changes in allometry generate the vast diversity of organism shapes. Nevertheless, progress has been limited in understanding the genetic mechanisms that regulate allometries and how these mechanisms evolve. This is perhaps because allometry is measured at the population level, however adult organ and body size depends on genetic background and the developmental environment of individuals. Recent findings have enhanced our understanding of how insects regulate their organ and body sizes in response to environmental conditions, particularly nutritional availability. We argue that merging these developmental insights with a population genetics approach will provide a powerful system for understanding the evolution of allometry.

  14. Allometry and size control: what can studies of body size regulation teach us about the evolution of morphological scaling relationships?

    PubMed

    Mirth, Christen K; Anthony Frankino, W; Shingleton, Alexander W

    2016-02-01

    The relationship between organ and body size, known as morphological allometry, has fascinated biologists for over a century because changes in allometry generate the vast diversity of organism shapes. Nevertheless, progress has been limited in understanding the genetic mechanisms that regulate allometries and how these mechanisms evolve. This is perhaps because allometry is measured at the population level, however adult organ and body size depends on genetic background and the developmental environment of individuals. Recent findings have enhanced our understanding of how insects regulate their organ and body sizes in response to environmental conditions, particularly nutritional availability. We argue that merging these developmental insights with a population genetics approach will provide a powerful system for understanding the evolution of allometry. PMID:27436558

  15. Hydration studies of electrospray ions from amino acids and small peptides

    NASA Astrophysics Data System (ADS)

    Nguyen, Chuong (Steve)

    regarding the ion formation mechanism of ESI. Additional studies revealed that the extent of the increase in ion yield was directly related to the charge state and molecular weight of the solute ions. In sum, this evidence strongly indicated that gas phase ions produced from charged droplets, as in electrospray ionization, must proceed by the sequence of events assumed in the Ion Evaporation Model proposed by Iribarne and Thomson rather than in the Charged Residue Model originally proposed by Malcolm Dole and coworkers. The hydration behaviors of electrospray ions from peptides with similar primary amino acid sequences and capable of forming ions with more than one charge state were also investigated. In a study with dipeptides, the extent of hydration was found to vary widely and to depend not only on the chemical composition of the ions but also on their configurations and charge states. The results obtained with lysine oligomers clearly indicated that the number of charges on an ion played an important role in the solvation process. An exception to this generalization was found in an experiment with multiply protonated pentalysine ions. For example, the quadruply protonated monomers of that species were found to undergo charge reduction via proton exchange with the surrounding water molecules in such a way as to maximize the distance between charges on the molecule, thereby reducing the internal repulsive forces. The hydration study of angiotensin II and III showed that while the former has an additional hydrophilic amino acid on the N-terminus, the latter peptide was more hydrophilic. This result suggests that the hydrophilicities of peptides are not a simple sum of the hydrophilicities of the individual amino acid components. As further evidence of interaction complexity, the Magic Number Clusters containing 21 water molecules were obtained with the doubly protonated angiotensin III, but not with the doubly protonated angiotensin II. Taken together, these observations

  16. Focused ion beam etching of nanometer-size GaN/AlGaN device structures and their optical characterization by micro-photoluminescence/Raman mapping

    SciTech Connect

    Kuball, M.; Benyoucef, M.; Morrissey, F.H.; Foxon, C.T.

    2000-07-01

    The authors report on the nano-fabrication of GaN/AlGaN device structures using focused ion beam (FIB) etching, illustrated on a GaN/AlGaN heterostructure field effect transistor (HFET). Pillars as small as 20nm to 300nm in diameter were fabricated from the GaN/AlGaN HFET. Micro-photoluminescence and UV micro-Raman maps were recorded from the FIB-etched pattern to assess its material quality. Photoluminescence was detected from 300nm-size GaN/AlGaN HFET pillars, i.e., from the AlGaN as well as the GaN layers in the device structure, despite the induced etch damage. Properties of the GaN and the AlGaN layers in the FIB-etched areas were mapped using UV Micro-Raman spectroscopy. Damage introduced by FIB-etching was assessed. The fabricated nanometer-size GaN/AlGaN structures were found to be of good quality. The results demonstrate the potential of FIB-etching for the nano-fabrication of III-V nitride devices.

  17. Uniform power method for sample size calculation in historical control studies with binary response.

    PubMed

    Lee, J J; Tseng, C

    2001-08-01

    Makuch and Simon gave a sample size calculation formula for historical control (HC) studies that assumed that the observed response rate in the control group is the true response rate. We dropped this assumption and computed the expected power and expected sample size to evaluate the performance of the procedure under the omniscient model. When there is uncertainty in the HC response rate but this uncertainty is not considered, Makuch and Simon's method produces a sample size that gives a considerably lower power than that specified. Even the larger sample size obtained from the randomized design formula and applied to the HC setting does not guarantee the advertised power in the HC setting. We developed a new uniform power method to search for the sample size required for the experimental group to yield an exact power without relying on the estimated HC response rate being perfectly correct. The new method produces the correct uniform predictive power for all permissible response rates. The resulting sample size is closer to the sample size needed for the randomized design than Makuch and Simon's method, especially when there is a small difference in response rates or a limited sample size in the HC group. HC design may be a viable option in clinical trials when the patient selection bias and the outcome evaluation bias can be minimized. However, the common perception of the extra sample size savings is largely unjustified without the strong assumption that the observed HC response rate is equal to the true control response rate. Generally speaking, results from HC studies need to be confirmed by studies with concurrent controls and cannot be used for making definitive decisions.

  18. Adsorption of Pb(II) ions from aqueous solution by native and activated bentonite: kinetic, equilibrium and thermodynamic study.

    PubMed

    Kul, Ali Riza; Koyuncu, Hülya

    2010-07-15

    In this study, the adsorption kinetics, equilibrium and thermodynamics of Pb(II) ions on native (NB) and acid activated (AAB) bentonites were examined. The specific surface areas, pore size and pore-size distributions of the samples were fully characterized. The adsorption efficiency of Pb(II) onto the NB and AAB was increased with increasing temperature. The kinetics of adsorption of Pb(II) ions was discussed using three kinetic models, the pseudo-first-order, the pseudo-second-order and the intra-particle diffusion model. The experimental data fitted very well the pseudo-second-order kinetic model. The initial sorption rate and the activation energy were also calculated. The activation energy of the sorption was calculated as 16.51 and 13.66 kJ mol(-1) for NB and AAB, respectively. Experimental results were also analysed by the Langmuir, Freundlich and Dubinin-Redushkevich (D-R) isotherm equations at different temperatures. R(L) separation factor for Langmuir and the n value for Freundlich isotherm show that Pb(II) ions are favorably adsorbed by NB and AAB. Thermodynamic quantities such as Gibbs free energy (DeltaG), the enthalpy (DeltaH) and the entropy change of sorption (DeltaS) were determined as about -5.06, 10.29 and 0.017 kJ mol(-1) K(-1), respectively for AAB. It was shown that the sorption processes were an endothermic reactions, controlled by physical mechanisms and spontaneously.

  19. Study of effect of variables on particle size of telmisartan nanosuspensions using box-Behnken design.

    PubMed

    Rao, M R P; Bajaj, A

    2014-12-01

    Telmisartan, an orally active nonpeptide angiotensin II receptor antagonist is a BCS Class II drug having aqueous solubility of 9.9 µg/ml and hence oral bioavailability of 40%. The present study involved preparation of nanosuspensions by evaporative antisolvent precipitation technique to improve the saturation solubility and dissolution rate of telmisartan. Various stabilizers such as TPGS, PVPK 30, PEG 6000 were investigated of which TPGS was found to provide maximum decrease in particle size and accord greater stability to the nanosuspensions. Box-Behnken design was used to investigate the effect of independent variables like stabilizer concentration, time and speed of stirring on particle size of nanosuspensions. Pharmacodynamic studies using Goldblatt technique were undertaken to evaluate the effect of nano-sizing on the hypotensive effect of the drug. Concentration of TPGS and speed of rotation were found to play an important role in particle size of the nanosuspensions whereas time of stirring displayed an exponential relationship with particle size. Freeze dried nanocrystals obtained from nanosuspension of least particle size were found to have increased saturation solubility of telmisartan in different dissolution media. The reconstituted nanosuspension was found to reduce both systolic and diastolic blood pressure without affecting pulse pressure and heart rate. Statistical tools can be used to identify key process and formulation parameters which play a significant role in controlling the particle size in nanosuspensions.

  20. Studying Equilibrium in the Chemical Reaction between Ferric and Iodide Ions in Solution Using a Simple and Inexpensive Approach

    ERIC Educational Resources Information Center

    Nikolaychuk, Pavel Anatolyevich; Kuvaeva, Alyona Olegovna

    2016-01-01

    A laboratory experiment on the study of the chemical equilibrium based on the reaction between ferric and iodide ions in solution with the formation of ferrous ions, free iodine, and triiodide ions is developed. The total concentration of iodide and triiodide ions in the reaction mixture during the reaction is determined by the argentometric…

  1. Comparative study on size dependence of melting temperatures of pure metal and alloy nanoparticles

    SciTech Connect

    Chen, C. L.; Lee, J.-G.; Arakawa, K.; Mori, H.

    2011-07-04

    A comparative study on the size dependence of the melting temperatures of pure metal and alloy nanoparticles has been carried out. It was found that the melting temperatures of Bi-Sn, In-Sn, and Pb-Sn alloy nanoparticles decreased more rapidly with decreasing particle size than those of the constituent metal nanoparticles (Bi, In, Pb, Sn). Namely, the size dependence of the melting temperature was stronger for the alloy nanoparticles than that for the constituent metal nanoparticles. Results calculated with a thermodynamic model were in good agreement with the experimental observations.

  2. Systematic study of finite-size effects in quantum Monte Carlo calculations of real metallic systems

    SciTech Connect

    Azadi, Sam Foulkes, W. M. C.

    2015-09-14

    We present a systematic and comprehensive study of finite-size effects in diffusion quantum Monte Carlo calculations of metals. Several previously introduced schemes for correcting finite-size errors are compared for accuracy and efficiency, and practical improvements are introduced. In particular, we test a simple but efficient method of finite-size correction based on an accurate combination of twist averaging and density functional theory. Our diffusion quantum Monte Carlo results for lithium and aluminum, as examples of metallic systems, demonstrate excellent agreement between all of the approaches considered.

  3. Experimental study of Siphon breaker about size effect in real scale reactor design

    SciTech Connect

    Kang, S. H.; Ahn, H. S.; Kim, J. M.; Joo, H. M.; Lee, K. Y.; Seo, K.; Chi, D. Y.; Kim, M. H.

    2012-07-01

    Rupture accident within the pipe of a nuclear reactor is one of the main causes of a loss of coolant accident (LOCA). Siphon-breaking is a passive method that can prevent a LOCA. In this study, either a line or a hole is used as a siphon-breaker, and the effect of various parameters, such as the siphon-breaker size, pipe rupture point, pipe rupture size, and the presence of an orifice, are investigated using an experimental facility similar in size to a full-scale reactor. (authors)

  4. Modeling the X-ray Process, and X-ray Flaw Size Parameter for POD Studies

    NASA Technical Reports Server (NTRS)

    Koshti, Ajay M.

    2014-01-01

    Nondestructive evaluation (NDE) method reliability can be determined by a statistical flaw detection study called probability of detection (POD) study. In many instances, the NDE flaw detectability is given as a flaw size such as crack length. The flaw is either a crack or behaving like a crack in terms of affecting the structural integrity of the material. An alternate approach is to use a more complex flaw size parameter. The X-ray flaw size parameter, given here, takes into account many setup and geometric factors. The flaw size parameter relates to X-ray image contrast and is intended to have a monotonic correlation with the POD. Some factors such as set-up parameters, including X-ray energy, exposure, detector sensitivity, and material type that are not accounted for in the flaw size parameter may be accounted for in the technique calibration and controlled to meet certain quality requirements. The proposed flaw size parameter and the computer application described here give an alternate approach to conduct the POD studies. Results of the POD study can be applied to reliably detect small flaws through better assessment of effect of interaction between various geometric parameters on the flaw detectability. Moreover, a contrast simulation algorithm for a simple part-source-detector geometry using calibration data is also provided for the POD estimation.

  5. The arithmetic problem size effect in children: an event-related potential study

    PubMed Central

    Van Beek, Leen; Ghesquièr, Pol; De Smedt, Bert; Lagae, Lieven

    2014-01-01

    This study used for the first time event-related potentials (ERPs) to examine the well-known arithmetic problem size effect in children. The electrophysiological correlates of this problem size effect have been well documented in adults, but such information in children is lacking. In the present study, 22 typically developing 12-year-olds were asked to solve single-digit addition problems of small (sum ≤ 10) and large problem size (sum > 10) and to speak the solution into a voice key while ERPs were recorded. Children displayed similar early and late components compared to previous adult studies on the problem size effect. There was no effect of problem size on the early components P1, N1, and P2. The peak amplitude of the N2 component showed more negative potentials on left and right anterior electrodes for large additions compared to small additions, which might reflect differences in attentional and working memory resources between large and small problems. The mean amplitude of the late positivity component which follows the N2, was significantly larger for large than for small additions at right parieto-occipital electrodes, in line with previous adult data. The ERPs of the problem size effect during arithmetic might be a useful neural marker for future studies on fact retrieval impairments in children with mathematical difficulties. PMID:25309405

  6. A Device to Study Gas-Phase Ion Reactions of Organic Radicals and Diradicals

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Bierbaum, Veronica M.; Ellison, G. Barney; Kato, Shuji

    2004-03-01

    Chemical ionization mass spectrometry uses ion reactions to monitor the atmospheric chemistry complex molecules. Proton transfer mass spectrometry is now a common method to monitor a large number of volatile organic compounds. Recent studies have shown that ion chemistry can be used to detect organic radicals. We have built an experiment to study the reactions of ions (both positive and negative) with complex organic radicals and diradicals. A supersonic pyrolysis nozzle produced a clean and intense stream of hydrocarbon radicals/diradicals which were studied with a flowing afterglow-selected ion flow tube (FA-SIFT) instrument. Reactions of a simple radical, allyl (CH2CHCH2), and a diradical, ortho-benzyne (o-C6H4), with the hydronium (H3O+) and hydroxide (HO-) ions were examined at thermal energy (roughly 300 K).

  7. A simple formula for the calculation of sample size in pilot studies.

    PubMed

    Viechtbauer, Wolfgang; Smits, Luc; Kotz, Daniel; Budé, Luc; Spigt, Mark; Serroyen, Jan; Crutzen, Rik

    2015-11-01

    One of the goals of a pilot study is to identify unforeseen problems, such as ambiguous inclusion or exclusion criteria or misinterpretations of questionnaire items. Although sample size calculation methods for pilot studies have been proposed, none of them are directed at the goal of problem detection. In this article, we present a simple formula to calculate the sample size needed to be able to identify, with a chosen level of confidence, problems that may arise with a given probability. If a problem exists with 5% probability in a potential study participant, the problem will almost certainly be identified (with 95% confidence) in a pilot study including 59 participants. PMID:26146089

  8. Studies of peptide a- and b-type fragment ions using stable isotope labeling and integrated ion mobility/tandem mass spectrometry.

    PubMed

    Riba Garcia, Isabel; Giles, Kevin; Bateman, Robert H; Gaskell, Simon J

    2008-12-01

    The structures of peptide a- and b-type fragment ions were studied using synthetic peptides including a set of isomeric peptides, differing in the sequence location of an alanine residue labeled with (15)N and uniformly with (13)C. The pattern of isotope labeling of second-generation fragment ions derived via a(n) and b(n) ions (where n = 4 or 5) suggested that these intermediates existed in part as macrocyclic structures, where alternative sites of ring opening gave rise to different linear forms whose simple cleavage might give rise to the observed final products. Similar conclusions were derived from combined ion mobility/tandem MS analyses where different fragmentation patterns were observed for isomeric a- or b-type ions that display different ion mobilities. These analyses were facilitated by a new approach to the processing of ion mobility/tandem MS data, from which distinct and separate product ion spectra are derived from ions that are incompletely separated by ion mobility. Finally, an example is provided of evidence for a macrocyclic structure for b(n) ions where n = 8 or 9.

  9. Mid-Infrared Nice-Ohms Spectrometer for the Study of Cold Molecular Ions

    NASA Astrophysics Data System (ADS)

    Porambo, Michael; Pearson, Jessica; Talicska, Courtney; McCall, Benjamin J.

    2014-06-01

    Molecular ions are involved in the chemistry of many interesting systems, such as the atmosphere, combustion reactions, and the interstellar medium. Challenging aspects of studying molecular ions spectroscopically include producing ions in enough abundance and, for large or fluxional ions, overcoming the problem of quantum dilution at high vibrational and rotational temperature. Furthermore, highly precise transition frequencies are needed to answer many questions involving molecular ions, such as the presence of specific candidate ions in the interstellar medium. To address these challenges, we have constructed a mid-infrared spectrometer that uses a difference frequency generation (DFG) light source to probe cooled molecular ions produced in a continuous supersonic expansion discharge source. The cooling of the ions achieved through supersonic expansion mitigates the problem of quantum dilution. High sensitivity to detect the 1012 ions per cm3 produced is accomplished through the use of noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) as a detection technique. Finally, an optical frequency comb is used to measure the transition frequencies of molecular ions precisely. This talk will present the current status of the instrument and preliminary studies to optimize and characterize its performance. Initial studies of room temperature methane allowed us to verify the use of NICE-OHMS for inferring rotational temperature of a molecular sample through Boltzmann plot analysis. Spectroscopy of H_3^+ and HN_2^+ extended this temperature verification to molecular ions. Future work on H_2CO^+, with the goal of determining its rovibrational transitions to a precision on the order of 1 MHz to aid in astronomical detection, will also be presented.

  10. Size study of dust produced in a CCP RF discharge for the simulation of Titan's chemistry

    SciTech Connect

    Alcouffe, G.; Cernogora, G.; Hadamcik, E.; Szopa, C.; Renard, J. B.

    2008-09-07

    A radio-frequency discharge in a N{sub 2}-CH{sub 4} gaseous mixture is used to reproduce Titan's aerosols. To understand the dust growth mechanisms, the effect of different parameters on their size is studied. It is shown that the tholins are bigger for a large amount of methane and for a lower gas flow in the plasma. The evolution of tholins' size with plasma duration is also presented.

  11. FIM/IAP/TEM studies of ion implanted nickel emitters

    SciTech Connect

    Walck, S.D.; Hren, J.J.

    1985-01-01

    Accurate depth profiling of implanted hydrogen and its isotopes in metals is extremely important. Field ion microscopy and atom-probe techniques provide the most accurate depth profiling analytical method of any available. In addition, they are extremely sensitive to hydrogen. This paper reports our early work on hydrogen trapping at defects in metals using the Field Ion Microscope/Imaging Atom Probe (FIM/IAP). Our results deal primarily with the control experiments required to overcome instrumental difficulties associated with in situ implantation and the influence of a high electric field. Transmission Electron Microscopy (TEM) has been used extensively to independently examine the influence of high electric fields on emitters. 11 references, 7 figures.

  12. A study of ion composition and dynamics at Comet Halley

    NASA Technical Reports Server (NTRS)

    Shelley, E. G.; Fuselier, S. A.

    1991-01-01

    This report details the participation by Lockheed co-investigators in the reduction, analysis, and interpretation of data obtained by the Ion Mass Spectrometer onboard the Giotto mission to Comet Halley. The data analysis activities and much of the scientific collaboration was shared by this team. One objective of the effort under this contract was to use data obtained by the Giotto Ion Mass Spectrometer (IMS) during the encounter with comet Halley for the purpose of advancing our understanding of the chemistry and physics of the interaction of the solar wind with comets and obtaining new information on the comet's composition. An additional objective was to make this unique data set available in a format which can be easily used by the reset of the cometary science community for other analysis in the future. The IMS has two sensors: the High Intensity Spectrometer (HIS) and the High Energy Range Spectrometer (HERS).

  13. Automatable lipid bilayer formation for ion channel studies

    NASA Astrophysics Data System (ADS)

    Poulos, Jason L.; Bang, Hyunwoo; Jeon, Tae-Joon; Schmidt, Jacob J.

    2008-08-01

    Transmembrane proteins and ion channels are important drug targets and have been explored as single molecule sensors. For these proteins to function normally they must be integrated within lipid bilayers; however, the labor and skill required to create artificial lipid bilayers have the limited the possible applications utilizing these proteins. In order to reduce the complexity and cost of lipid bilayer formation and measurement, we have modified a previously published lipid bilayer formation technique using mechanically contacted monolayers so that the process is automatable, requiring minimal operator input. Measurement electronics are integrated with the fluid handling system, greatly reducing the time and operator feedback characteristically required of traditional bilayer experiments. To demonstrate the biological functionality of the resultant bilayers and the system's capabilities as a membrane platform, the ion channel gramicidin A was incorporated and measured with this system.

  14. NaCl crystallization in apolar nanometer-sized confinement studied by atomistic simulations.

    PubMed

    Kalcher, Immanuel; Dzubiella, Joachim

    2013-12-01

    The structure and growth of molecular NaCl crystals in bulk and in a narrow, nanometer-sized apolar confinement are examined by explicit-water molecular dynamics computer simulations. It is demonstrated that fast crystallization and subsequent diffusion-controlled cluster growth in bulk is triggered by supersaturations that exceed a certain threshold value. In confinement, simulated in a pseudo grand canonical setup, salt is shown to be expelled from the narrow apolar slab region, and the effective ion concentration inside the nanoconfinement is always considerably lower than the reservoir salt concentration so that no fast crystallization takes place. For very small slab widths (d<1.5 nm) salt is almost entirely expelled while water remains in the slab, indicating a capillary evaporation phenomenon for the polar ions. If forced into the apolar confinement by simulating in a strictly canonical setup, we find stable crystals only if at least three crystalline planes fit into the slab, which happens above a 2-nm slab width. In this case the (100) plane of the bulk crystal is oriented parallel to the apolar surface delimited by a subnanometer thin hydration layer. This work presents molecular-level insight of salt crystallization in apolar confinements of a nanometer scale with possible implications in double-layer supercapacitor physics and geological salt weathering. PMID:24483449

  15. Creating and studying ion acoustic waves in ultracold neutral plasmas

    SciTech Connect

    Killian, T. C.; Castro, J.; McQuillen, P.; O'Neil, T. M.

    2012-05-15

    We excite ion acoustic waves in ultracold neutral plasmas by imprinting density modulations during plasma creation. Laser-induced fluorescence is used to observe the density and velocity perturbations created by the waves. The effect of expansion of the plasma on the evolution of the wave amplitude is described by treating the wave action as an adiabatic invariant. After accounting for this effect, we determine that the waves are weakly damped, but the damping is significantly faster than expected for Landau damping.

  16. A study on major inorganic ion composition of atmospheric aerosols.

    PubMed

    Salve, P R; Krupadam, R J; Wate, S R

    2007-04-01

    Atmospheric aerosol samples were collected from Akola and Buldana region covering around 40 sqkm area during October-November 2002 and were analyzed for ten major inorganic ions namely F-, Cl-, NO3-, SO4(2-), PO4(2-), Na+, K+, Ca2+, Mg2+ and NH4+ using ion chromatographic technique. The average mass of aerosols was found to be 225.81 microg/m3 with standard deviation of 31.29 and average total water soluble load of total cations and anions was found to be 4.32 microg/m3. The concentration of ions in samples showed a general pattern as SO4(2-) > NO3- > Cl- > PO4(2-) > F- for anions and Na+ > Ca2+ > NH4+ > Mg2+ > K+ for cations. The overall composition of the aerosols was taken into account to identify the sources. The trend showed higher concentration of sodium followed by calcium, sulfate, nitrate, phosphate and ammoinum and found to be influenced by terrestrial sources. The presence of SO4(2-) and NO3- in aerosols may be due to re-suspension of soil particles. Ca2+, Mg2+ and Cl- are to be derived from soil materials. The presence of NH4+ may be attributed to the reaction of NH3 vapors with acidic gases may react or condense on an acidic particle surface of anthropogenic origin. The atmospheric aerosol is slightly acidic due to neutralization of basicity by SO2 and NO(x).

  17. A study of void size growth in nonequilibrium stochastic systems of point defects

    NASA Astrophysics Data System (ADS)

    Kharchenko, Dmitrii O.; Kharchenko, Vasyl O.; Bashtova, Anna I.

    2016-05-01

    We study properties of voids growth dynamics in a stochastic system of point defects in solids under nonequilibrium conditions (sustained irradiation). It is shown that fluctuations of defect production rate (external noise) increase the critical void radius comparing to a deterministic system. An automodel regime of void size growth in a stochastic system is studied in detail. Considering a homogeneous system, it is found that external noise does not change the universality of the void size distribution function; the mean void size evolves according to classical nucleation theory. The noise increases the mean void size and spreads the void size distribution. Studying dynamics of spatially extended systems it was shown that vacancies remaining in a matrix phase are able to organize into vacancy enriched domains due to an instability caused by an elastic lattice deformation. It is shown that dynamics of voids growth is defined by void sinks strength with void size growth exponent varying from 1/3 up to 1/2.

  18. Study of Nickel Ion Release in Simulated Body Fluid from C+-IMPLANTED Nickel Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Shafique, Muhammad Ahsan; Murtaza, G.; Saadat, Shahzad; Zaheer, Zeeshan; Shahnawaz, Muhammad; Uddin, Muhammad K. H.; Ahmad, Riaz

    2016-05-01

    Nickel ion release from NiTi shape memory alloy is an issue for biomedical applications. This study was planned to study the effect of C+ implantation on nickel ion release and affinity of calcium phosphate precipitation on NiTi alloy. Four annealed samples are chosen for the present study; three samples with oxidation layer and the fourth without oxidation layer. X-ray diffraction (XRD) spectra reveal amorphization with ion implantation. Proton-induced X-ray emission (PIXE) result shows insignificant increase in Ni release in simulated body fluid (SBF) and calcium phosphate precipitation up to 8×1013ions/cm2. Then Nickel contents show a sharp increase for greater ion doses. Corrosion potential decreases by increasing the dose but all the samples passivate after the same interval of time and at the same level of VSCE in ringer lactate solution. Hardness of samples initially increases at greater rate (up to 8×1013ions/cm2) and then increases with lesser rate. It is found that 8×1013ions/cm2 (≈1014) is a safer limit of implantation on NiTi alloy, this limit gives us lesser ion release, better hardness and reasonable hydroxyapatite incubation affinity.

  19. Small sample sizes in the study of ontogenetic allometry; implications for palaeobiology

    PubMed Central

    Vavrek, Matthew J.

    2015-01-01

    Quantitative morphometric analyses, particularly ontogenetic allometry, are common methods used in quantifying shape, and changes therein, in both extinct and extant organisms. Due to incompleteness and the potential for restricted sample sizes in the fossil record, palaeobiological analyses of allometry may encounter higher rates of error. Differences in sample size between fossil and extant studies and any resulting effects on allometric analyses have not been thoroughly investigated, and a logical lower threshold to sample size is not clear. Here we show that studies based on fossil datasets have smaller sample sizes than those based on extant taxa. A similar pattern between vertebrates and invertebrates indicates this is not a problem unique to either group, but common to both. We investigate the relationship between sample size, ontogenetic allometric relationship and statistical power using an empirical dataset of skull measurements of modern Alligator mississippiensis. Across a variety of subsampling techniques, used to simulate different taphonomic and/or sampling effects, smaller sample sizes gave less reliable and more variable results, often with the result that allometric relationships will go undetected due to Type II error (failure to reject the null hypothesis). This may result in a false impression of fewer instances of positive/negative allometric growth in fossils compared to living organisms. These limitations are not restricted to fossil data and are equally applicable to allometric analyses of rare extant taxa. No mathematically derived minimum sample size for ontogenetic allometric studies is found; rather results of isometry (but not necessarily allometry) should not be viewed with confidence at small sample sizes. PMID:25780770

  20. Utility of microcosm studies for predicting phylloplane bacterium population sizes in the field.

    PubMed

    Kinkel, L L; Wilson, M; Lindow, S E

    1996-09-01

    Population sizes of two ice nucleation-active strains of Pseudomonas syringae were compared on leaves in controlled environments and in the field to determine the ability of microcosm studies to predict plant habitat preferences in the field. The P. syringae strains investigated were the parental strains of recombinant deletion mutant strains deficient in ice nucleation activity that had been field tested for their ability to control plant frost injury. The population size of the P. syringae strains was measured after inoculation at three field locations on up to 40 of the same plant species that were studied in the growth chamber. There was seldom a significant relationship between the mean population size of a given P. syringae strain incubated under either wet or dry conditions in microcosms and the mean population size which could be recovered from the same species when inoculated in the field. Specifically, on some plant species, the population size recovered from leaves in the field was substantially greater than from that species in a controlled environment, while for other plant species field populations were significantly smaller than those observed under controlled conditions. Population sizes of inoculated P. syringae strains, however, were frequently highly positively correlated with the indigenous bacterial population size on the same plant species in the field, suggesting that the ability of a particular plant species to support introduced bacterial strains is correlated with its ability to support large bacterial populations or that indigenous bacteria enhance the survival of introduced strains. Microcosm studies therefore seem most effective at assessing possible differences between parental and recombinant strains under a given environmental regime but are limited in their ability to predict the specific population sizes or plant habitat preferences of bacteria on leaves under field conditions. PMID:16535405

  1. Simulation Studies of Beam-Beam Effects of a Ring-Ring Electron-Ion Collider Based on CEBAF

    SciTech Connect

    Yuhong Zhang,Ji Qiang

    2009-05-01

    The collective beam-beam effect can potentially cause a rapid growth of beam sizes and reduce the luminosity of a collider to an unacceptably low level. The ELIC, a proposed ultra high luminosity electron-ion collider based on CEBAF, employs high repetition rate crab crossing colliding beams with very small bunch transverse sizes and very short bunch lengths, and collides them at up to 4 interaction points with strong final focusing. All of these features can make the beam-beam effect challenging. In this paper, we present simulation studies of the beam-beam effect in ELIC using a self-consistent strong-strong beam-beam simulation code developed at Lawrence Berkeley National Laboratory. This simulation study is used for validating the ELIC design and for searching for an optimal parameter set.

  2. Exploring the interaction between lithium ion and defective graphene surface using dispersion corrected DFT studies

    SciTech Connect

    Vijayakumar, M.; Hu, Jian Z.

    2013-10-15

    To analyze the lithium ion interaction with realistic graphene surfaces, we carried out dispersion corrected DFT-D3 studies on graphene with common point defects and chemisorbed oxygen containing functional groups along with defect free graphene surface. Our study reveals that, the interaction between lithium ion (Li+) and graphene is mainly through the delocalized π electron of pure graphene layer. However, the oxygen containing functional groups pose high adsorption energy for lithium ion due to the Li-O ionic bond formation. Similarly, the point defect groups interact with lithium ion through possible carbon dangling bonds and/or cation-π type interactions. Overall these defect sites render a preferential site for lithium ions compared with pure graphene layer. Based on these findings, the role of graphene surface defects in lithium battery performance were discussed.

  3. Size-dependent catalytic kinetics and dynamics of Pd nanocubes: a single-particle study.

    PubMed

    Chen, Tao; Zhang, Yuwei; Xu, Weilin

    2016-08-10

    Due to the well-known significant effect of the size on the catalytic activity of nanocatalysts, here we use single-molecule fluorescence microscopy to study the size-dependent catalytic kinetics and dynamics of individual Pd nanocubes. A series of size-dependent catalytic properties were revealed in both product formation and product desorption processes. It was found that, due to the different adsorption mechanisms of substrate molecules on Pd nanocubes, H2 adsorption is independent of the size of Pd nanocubes, while the large flat resazurin molecules show stronger adsorption on larger sized Pd nanocubes. Apparently, the Pd nanocubes can be divided into three types: when the size of the Pd nanocube is small, substrate binding can prohibit product desorption and product desorption prefers the direct pathway; when the size is in an appropriate range, the product desorption process could be independent of substrate binding and shows no selectivity between two parallel desorption pathways; if the size is large enough, substrate binding can promote product desorption and product desorption prefers the indirect pathway. We also observed the surface-restructuring-induced dynamic heterogeneity of individual Pd nanocubes in both product formation and desorption processes with timescales of about tens to one hundred seconds. The activity fluctuation of individual Pd nanocubes was found to be mainly due to the spontaneous surface-restructuring rather than the catalysis. Furthermore, we estimated the size-dependent activation energies and time scales of spontaneous dynamic surface restructuring, which are fundamental to heterogeneous catalysis. The work presented here reveals new insight into nanocatalysis and exemplifies the advantages of the single-molecule approach in probing the catalytic properties of nanocatalysts. PMID:27465438

  4. A longitudinal study of the relationships between the Big Five personality traits and body size perception.

    PubMed

    Hartmann, Christina; Siegrist, Michael

    2015-06-01

    The present study investigated the longitudinal development of body size perception in relation to different personality traits. A sample of Swiss adults (N=2905, 47% men), randomly selected from the telephone book, completed a questionnaire on two consecutive years (2012, 2013). Body size perception was assessed with the Contour Drawing Rating Scale and personality traits were assessed with a short version of the Big Five Inventory. Longitudinal analysis of change indicated that men and women scoring higher on conscientiousness perceived themselves as thinner one year later. In contrast, women scoring higher on neuroticism perceived their body size as larger one year later. No significant effect was observed for men scoring higher on neuroticism. These results were independent of weight changes, body mass index, age, and education. Our findings suggest that personality traits contribute to body size perception among adults.

  5. System Size, Energy, and Centrality Dependence of Pseudorapidity Distributions of Charged Particles in Relativistic Heavy-Ion Collisions

    SciTech Connect

    Alver, B.; Back, B. B.; Baker, M. D.; Barton, D. S.; Chai, Z.; Holzman, B.; Nouicer, R.; Pak, R.; Sedykh, I.; Stankiewicz, M. A.; Steinberg, P.; Sukhanov, A.; Szostak, A.; Wyngaardt, S.; Ballintijn, M.; Busza, W.; Gulbrandsen, K.; Henderson, C.; Kane, J. L.; Kulinich, P.

    2009-04-10

    We present the first measurements of the pseudorapidity distribution of primary charged particles in Cu+Cu collisions as a function of collision centrality and energy, {radical}(s{sub NN})=22.4, 62.4, and 200 GeV, over a wide range of pseudorapidity, using the PHOBOS detector. A comparison of Cu+Cu and Au+Au results shows that the total number of produced charged particles and the rough shape (height and width) of the pseudorapidity distributions are determined by the number of nucleon participants. More detailed studies reveal that a more precise matching of the shape of the Cu+Cu and Au+Au pseudorapidity distributions over the full range of pseudorapidity occurs for the same N{sub part}/2A rather than the same N{sub part}. In other words, it is the collision geometry rather than just the number of nucleon participants that drives the detailed shape of the pseudorapidity distribution and its centrality dependence at RHIC energies.

  6. A Study of Ion Velocities Observed by TIDE and How It Relates to Magnetospheric Circulation

    NASA Technical Reports Server (NTRS)

    Elliott, H. A.; Comfort, R. H.; Craven, P. D.; Chandler, M. O.; Moore, T. E.

    1998-01-01

    The high-latitude ion velocities measured by the Thermal Ion Dynamics Experiment (TIDE) instrument on the Polar spacecraft will be examined in relation to magnetospheric circulation. TIDE derives ion velocities from moments of measured distribution functions. Hydrogen and oxygen ions are E X B drifting in the polar cap and cleft regions with a speed of about 5-20 km/s at apogee (approximately 9 Re) and a speed of 1-2 km/s at perigee (approximately 1.8 Re). At perigee 0+ is typically seen flowing down in the polar cap and outflowing from the cleft. At the transition from downflowing to upflowing there is also seen a reversal in the ion convection. The convection at perigee is consistent with standard ionospheric convection models for given Interplanetary Magnetic Field (IMF) conditions. Convection at high altitude (approximately 8.9 Re) polar regions has not been studied very much since there have not been many satellites in this region. Unlike previous missions to this region TIDE in conjunction the Plasma Source Instrument (PSI) can measure ions with as low an energy as several electron Volts. The outflowing ions observed by TIDE at apogee are believed to be important to the overall circulation of the magnetosphere. The convection of these outflowing ions at apogee will be related to the IMF. This study tries to answer the question of how the IMF response of the convection influences the overall circulation of the magnetosphere.

  7. Heavy ion elastic recoil detection analysis set up for electronic sputtering studies

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Avasthi, D. K.; Tripathi, A.; Kabiraj, D.; Sugathan, P.; Chaudhary, G. K.; Barua, P.

    2006-04-01

    Heavy ion elastic recoil detection analysis (ERDA) set up with a large solid angle (greater than or similar to 4.8 msr) Delta E - E position-sensitive telescope detector is developed at Inter University Accelerator Centre as a dedicated facility for the study of electronic sputtering of thin films under swift heavy ion (SHI) irradiation. The detector consists of a gas ionization chamber (Delta E ) and a solid-state surface barrier detector ( E ) housed in a same assembly. The electronic sputtering yield (atoms/ion) is determined by analyzing on-line fluence-dependent ERDA data obtained from a variety of thin films. Large erosion (> 10 5 atoms/ion) of carbon from a-C:H by 150 MeV Ag 13+ ions, evolution of nitrogen (greater than or similar to 880 atoms/ion) from copper nitride and depletion of oxygen (greater than or similar to 1000 atoms/ion) from copper oxide film under 200 MeV Au 15+ ion impact are studied and reported in this work. The electronic sputtering of these materials is discussed on the basis of the thermal spike model of SHI and solid interaction.

  8. Clinical study using novel endoscopic system for measuring size of gastrointestinal lesion

    PubMed Central

    Oka, Kiyoshi; Seki, Takeshi; Akatsu, Tomohiro; Wakabayashi, Takao; Inui, Kazuo; Yoshino, Junji

    2014-01-01

    AIM: To verify the performance of a lesion size measurement system through a clinical study. METHODS: Our proposed system, which consists of a conventional endoscope, an optical device, an optical probe, and a personal computer, generates a grid scale to measure the lesion size from an endoscopic image. The width of the grid scale is constantly adjusted according to the distance between the tip of the endoscope and lesion because the lesion size on an endoscopic image changes according to the distance. The shape of the grid scale was corrected to match the distortion of the endoscopic image. The distance was calculated using the amount of laser light reflected from the lesion through an optical probe inserted into the instrument channel of the endoscope. The endoscopist can thus measure the lesion size without contact by comparing the lesion with the size of the grid scale on the endoscopic image. (1) A basic test was performed to verify the relationship between the measurement error eM and the tilt angle of the endoscope; and (2) The sizes of three colon polyps were measured using our system during endoscopy. These sizes were immediately measured by scale after their removal. RESULTS: There was no error at α = 0°. In addition, the values of eM (mean ± SD) were 0.24 ± 0.11 mm (α = 10°), 0.90 ± 0.58 mm (α = 20°) and 2.31 ± 1.41 mm (α = 30°). According to these results, our system has been confirmed to measure accurately when the tilt angle is less than 20°. The measurement error was approximately 1 mm in the clinical study. Therefore, it was concluded that our proposed measurement system was also effective in clinical examinations. CONCLUSION: By combining simple optical equipment with a conventional endoscope, a quick and accurate system for measuring lesion size was established. PMID:24744595

  9. Origin of Capacity Fading in Nano-Sized Co3O4Electrodes: Electrochemical Impedance Spectroscopy Study

    PubMed Central

    2008-01-01

    Transition metal oxides have been suggested as innovative, high-energy electrode materials for lithium-ion batteries because their electrochemical conversion reactions can transfer two to six electrons. However, nano-sized transition metal oxides, especially Co3O4, exhibit drastic capacity decay during discharge/charge cycling, which hinders their practical use in lithium-ion batteries. Herein, we prepared nano-sized Co3O4with high crystallinity using a simple citrate-gel method and used electrochemical impedance spectroscopy method to examine the origin for the drastic capacity fading observed in the nano-sized Co3O4anode system. During cycling, AC impedance responses were collected at the first discharged state and at every subsequent tenth discharged state until the 100th cycle. By examining the separable relaxation time of each electrochemical reaction and the goodness-of-fit results, a direct relation between the charge transfer process and cycling performance was clearly observed.

  10. Minimum Sample Size for Cronbach's Coefficient Alpha: A Monte-Carlo Study

    ERIC Educational Resources Information Center

    Yurdugul, Halil

    2008-01-01

    The coefficient alpha is the most widely used measure of internal consistency for composite scores in the educational and psychological studies. However, due to the difficulties of data gathering in psychometric studies, the minimum sample size for the sample coefficient alpha has been frequently debated. There are various suggested minimum sample…

  11. 78 FR 76888 - MAP-21 Comprehensive Truck Size and Weight Limits Study Materials

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-19

    ... legal questions, please contact Michael Harkins, FHWA Office of the Chief Counsel, (202) 366-4928, or by... to deliver this Study to Congress within the required timeframe, the closing date is changed from... for Progress in the 21st Century Act (MAP-21) Comprehensive Truck Size and Weight Limits Study,...

  12. Improving Sensitivity in Ultrasound Molecular Imaging by Tailoring Contrast Agent Size Distribution: In Vivo Studies

    PubMed Central

    Streeter, Jason E.; Gessner, Ryan; Miles, Iman; Dayton, Paul A.

    2010-01-01

    Molecular imaging with ultrasound relies on microbubble contrast agents (MCAs) selectively adhering to a ligand-specific target. Prior studies have shown that only small quantities of microbubbles are retained at their target sites, therefore, enhancing contrast sensitivity to low concentrations of microbubbles is essential to improve molecular imaging techniques. In order to assess the effect of MCA diameter on imaging sensitivity, perfusion and molecular imaging studies were performed with microbubbles of varying size distributions. To assess signal improvement and MCA circulation time as a function of size and concentration, blood perfusion was imaged in rat kidneys using nontargeted size-sorted MCAs with a Siemens Sequoia ultrasound system (Siemans, Mountain View, CA) in cadence pulse sequencing (CPS) mode. Molecular imaging sensitivity improvements were studied with size-sorted αvβ3-targeted bubbles in both fibrosarcoma and R3230 rat tumor models. In perfusion imaging studies, video intensity and contrast persistence was ≈8 times and ≈3 times greater respectively, for “sorted 3-micron” MCAs (diameter, 3.3 ± 1.95 μm) when compared to “unsorted” MCAs (diameter, 0.9 ± 0.45 μm) at low concentrations. In targeted experiments, application of sorted 3-micron MCAs resulted in a ≈20 times video intensity increase over unsorted populations. Tailoring size-distributions results in substantial imaging sensitivity improvement over unsorted populations, which is essential in maximizing sensitivity to small numbers of MCAs for molecular imaging. PMID:20236606

  13. An evaluation of different measures of dynamically recrystallized grain size for paleopiezometry or paleowattometry studies

    NASA Astrophysics Data System (ADS)

    Lopez-Sanchez, M. A.; Llana-Fúnez, S.

    2015-05-01

    Paleopiezometry and paleowattometry studies are essential to validate models of lithospheric deformation and therefore increasingly common in structural geology. These studies require a single measure of dynamically recrystallized grain size in natural mylonites to estimate the magnitude of differential paleostress (or the rate of mechanical work). This contribution tests the various measures of grain size used in the literature and proposes the frequency peak of a grain size distribution as the most robust estimator for paleopiezometry or paleowattometry studies. The novelty of the approach resides in the use of the Gaussian kernel density estimator as an alternative to the classical histograms, which improves reproducibility. A free, open-source, easy-to-handle script named GrainSizeTools ( http://www.TEOS-10.org) was developed with the aim of facilitating the adoption of this measure of grain size in paleopiezometry or paleowattometry studies. The major advantage of the script over other programs is that by using the Gaussian kernel density estimator and by avoiding manual steps in the estimation of the frequency peak, the reproducibility of results is improved.

  14. Comparative study of ion conducting pathways in borate glasses

    SciTech Connect

    Hall, Andreas; Swenson, Jan; Adams, Stefan

    2006-11-01

    The conduction pathways in metal-halide doped silver, lithium, and sodium diborate glasses have been examined by bond valence analysis of reverse Monte Carlo (RMC) produced structural models of the glasses. Although all glass compositions have basically the same short-range structure of the boron-oxygen network, it is evident that the intermediate-range structure is strongly dependent on the type of mobile ion. The topography of the pathways and the coordination of the pathway sites differ distinctly between the three glass systems. The mobile silver ions in the AgI-doped glass tend to be mainly iodine-coordinated and travel in homogeneously distributed pathways located in salt-rich channels of the borate network. In the NaCl-doped glass, there is an inhomogeneous spatial distribution of pathways that reflects the inhomogeneous introduction of salt ions into the glass. However, since the salt clusters are not connected, no long-range conduction pathways are formed without including also oxygen-rich regions. The pathways in the LiCl-doped glass are slightly more evenly distributed compared to the NaCl-doped glass (but not as ordered as in the AgI-doped glass), and the regions of mainly oxygen-coordinated pathway sites are of higher importance for the long-range migration. In order to more accurately investigate how these differences in the intermediate-range order of the glasses affect the ionic conductivity, we have compared the realistic structure models to more or less randomized structures. An important conclusion from this comparison is that we find no evidence that a pronounced intermediate-range order in the atomic structure or in the network of conduction pathways, as in the AgI-doped glass, is beneficial for the dc conductivity.

  15. Crab Crossing Schemes and Studies for Electron Ion Collider

    SciTech Connect

    S. Ahmed, Y. Derbenev, V. Morozov, A. Castilla, G.A. Krafft, B. Yunn, Y. Zhang, J.R. Delayen

    2011-09-01

    This report shows our progress in crab crossing consideration for future electron-ion collider envisioned at JLab. In this design phase, we are evaluating two crabbing schemes viz., the deflecting and dispersive. The mathematical formulations and lattice design for these schemes are discussed in this paper. Numerical simulations involving particle tracking through a realistic deflecting RF cavity and optics illustrate the desired crab tilt of 25 mrad for 1.35 MV. Evolution of beam propagation are shown which provides the physical insight of the crabbing phenomenon.

  16. Ion beam analysis in cultural heritage studies: Milestones and perspectives

    SciTech Connect

    Dran, Jean-Claude; Calligaro, Thomas

    2013-07-18

    For three decades, ion beam analysis (IBA) in external mode was considered as the best choice for the characterisation of cultural heritage materials, as it combines excellent analytical performance and non-invasive character. However, in recent years, other analytical techniques arose as serious competitors, such as those based on synchrotron radiation (X-ray absorption, fluorescence or diffraction) or those using portable instruments (XRF, micro-Raman). It is shown that nevertheless IBA remains unmatched thanks to two unique features, namely the analysis of light elements and the high-resolution 3D chemical imaging.

  17. Studies of energetic ion confinement during fishbone events in PDX

    SciTech Connect

    Strachan, J.D.; Grek, B.; Heidbrink, W.; Johnson, D.; Kaye, S.; Kugel, H.; LeBlanc, B.; McGuire, K.

    1984-11-01

    The 2.5-MeV neutron emission from the beam-target d(d,n,)/sup 3/He fusion reaction has been examined for all PDX deuterium plasmas which were heated by deuterium neutral beams. The magnitude of the emission was found to scale classically and increase with T/sub e//sup 3/2/ as expected when electron drag is the primary energy degradation mechanism. The time evolution of the neutron emission through fishbone events was measured and used to determine the confinement properties of the energetic beam ions. Many of the experimental results are predicted by the Mode Particle Pumping theory.

  18. Electromagnetic Ion Cyclotron Waves near the Plasmapause: A CLUSTER Case Study

    NASA Astrophysics Data System (ADS)

    Fraser, B. J.; Liu, Y.; Menk, F. W.

    2011-12-01

    Electromagnetic ion cyclotron (EMIC) waves in the Pc1 ultra-low frequency wave band (0.2-5Hz) observed in the plasmasphere and magnetosphere are generated by micro-scale instabilities associated with keV energetic protons of ring current origin. This case study presents a typical EMIC wave event with frequency 1.8-3.5 Hz observed by the four Cluster spacecraft when passing through perigee (L ~ 4:2) and moving northward on 2 November 2001 around 08 MLT. The event occurred around the magnetic equatorial plane within magnetic latitude range ±18 degrees with a short duration of 50 minutes. The associated cold electron density data show the wave power was confined within the narrow shell of the plasmapause where the electron density gradient decreased from 30-80 cm-3 to 20 cm-3. The radial scale size of the wave region is estimated at ~ 0:77 Re. The wave polarization was dominantly left-handed around the equatorial region and inner side of source region, but appeared right-handed close to the outer edge of the plasmapause and at higher latitudes. The Poynting flux and minimum variance analysis indicate that the wave energy was mainly transported towards high latitudes though oblique propagation was seen around the equatorial region. Enhanced H+, He+ and O+ particle energy fluxes were seen during the wave event over energy range ~25eV-40keV. Unfortunately the lower energy cold plasma composition data were not available. These observations suggest the waves originated around the equatorial region in the high density outer plasmasphere-plasmapause which overlaps the ring current; ideal conditions for wave generation by the ion cyclotron instability.

  19. Class Size.

    ERIC Educational Resources Information Center

    Ellis, Thomas I.

    1985-01-01

    After a brief introduction identifying current issues and trends in research on class size, this brochure reviews five recent studies bearing on the relationship of class size to educational effectiveness. Part 1 is a review of two interrelated and highly controversial "meta-analyses" or statistical integrations of research findings on class size,…

  20. Gamma-resonance study of the reaction of iron ions with synthetic L-dopa melanin

    SciTech Connect

    Bagirov, R.M.; Stukan, R.A.; Lapina, V.A.; Dontsov, A.E.; Ostrovskii, M.A.

    1986-07-01

    The reaction of Fe/sup 3 +/ and Fe/sup 2 +/ ions with synthetic L-dopa melanin, which is a model compound of natural melanin (the melanoprotein granules in the pigment epithelial cells in vertebrate and human eyes), has been studied by gamma-resonance spectroscopy. The investigations showed that L-dopa melanin is capable of effectively binding iron ions and that it displays oxidative or reducing properties with respect to Fe, depending on the composition of the subsystem of the Fe ions and the ambient pH. Trivalent Fe/sup 3 +/ ions form stronger complexes with L-dopa melanin than do Fe/sup 2 +/ ions. The coordination takes place mainly with the carboxyl groups and the amino and imino groups of the polymer. The conformational state of the polymer apparently changes as the pH is varied.

  1. Modelling third harmonic ion cyclotron acceleration of deuterium beams for JET fusion product studies experiments

    NASA Astrophysics Data System (ADS)

    Schneider, M.; Johnson, T.; Dumont, R.; Eriksson, J.; Eriksson, L.-G.; Giacomelli, L.; Girardo, J.-B.; Hellsten, T.; Khilkevitch, E.; Kiptily, V. G.; Koskela, T.; Mantsinen, M.; Nocente, M.; Salewski, M.; Sharapov, S. E.; Shevelev, A. E.; Contributors, JET

    2016-11-01

    Recent JET experiments have been dedicated to the studies of fusion reactions between deuterium (D) and Helium-3 (3He) ions using neutral beam injection (NBI) in synergy with third harmonic ion cyclotron radio-frequency heating (ICRH) of the beam. This scenario generates a fast ion deuterium tail enhancing DD and D3He fusion reactions. Modelling and measuring the fast deuterium tail accurately is essential for quantifying the fusion products. This paper presents the modelling of the D distribution function resulting from the NBI+ICRF heating scheme, reinforced by a comparison with dedicated JET fast ion diagnostics, showing an overall good agreement. Finally, a sawtooth activity for these experiments has been observed and interpreted using SPOT/RFOF simulations in the framework of Porcelli’s theoretical model, where NBI+ICRH accelerated ions are found to have a strong stabilizing effect, leading to monster sawteeth.

  2. Dosimetry in radiobiological studies with the heavy ion beam of the Warsaw cyclotron

    NASA Astrophysics Data System (ADS)

    Kaźmierczak, U.; Banaś, D.; Braziewicz, J.; Czub, J.; Jaskóła, M.; Korman, A.; Kruszewski, M.; Lankoff, A.; Lisowska, H.; Malinowska, A.; Stępkowski, T.; Szefliński, Z.; Wojewódzka, M.

    2015-12-01

    The aim of this study was to verify various dosimetry methods in the irradiation of biological materials with a 12C ion beam at the Heavy Ion Laboratory of the University of Warsaw. To this end the number of ions hitting the cell nucleus, calculated on the basis of the Si-detector system used in the set-up, was compared with the number of ion tracks counted in irradiated Solid State Nuclear Track Detectors and with the number of ion tracks detected in irradiated Chinese Hamster Ovary cells processed for the γ-H2AX assay. Tests results were self-consistent and confirmed that the system serves its dosimetric purpose.

  3. Study on the microwave ion source of the 100-MeV proton linac

    NASA Astrophysics Data System (ADS)

    Kwon, Hyeok-Jung

    2016-09-01

    A microwave ion source is used as an ion source for the 100-MeV proton accelerator at the Korea Multi-purpose Accelerator Complex (KOMAC). The specifications of the ion source are a 50-keV energy and a 20-mA peak current. The plasma is operated in the CW mode by using a magnetron, and the pulse beam is extracted using a semiconductor switch located in the extraction power supply. The beam characteristics were measured based on the pulse voltage and current. A test stand was also installed to study the beam characteristics of the ion source off-line. In this paper, the pulse beam characteristics of the ion source are presented, and the installation of the test stand is reported.

  4. Computer simulations of ions in radio-frequency traps

    NASA Technical Reports Server (NTRS)

    Williams, A.; Prestage, J. D.; Maleki, L.; Djomehri, J.; Harabetian, E.

    1990-01-01

    The motion of ions in a trapped-ion frequency standard affects the stability of the standard. In order to study the motion and structures of large ion clouds in a radio-frequency (RF) trap, a computer simulation of the system that incorporates the effect of thermal excitation of the ions was developed. Results are presented from the simulation for cloud sizes up to 512 ions, emphasizing cloud structures in the low-temperature regime.

  5. Acute Effect of Cigarette Smoking on Pupil Size and Ocular Aberrations: A Pre- and Postsmoking Study

    PubMed Central

    Erdem, Uzeyir; Gundogan, Fatih C.; Dinc, Umut Aslı; Yolcu, Umit; Ilhan, Abdullah; Altun, Salih

    2015-01-01

    Aim. To evaluate the acute effects of cigarette smoking on photopic and mesopic pupil sizes and wavefront aberrations. Methods. Cigarette smoker volunteers were recruited in the study. Photopic and mesopic pupil sizes and total ocular aberrations were measured before smoking and immediately after smoking. All volunteers were asked to smoke a single cigarette containing 1.0 mg nicotine. Pupil sizes and total ocular aberrations were assessed by optical path difference scanning system (OPD-Scan II ARK-10000, NIDEK). Only the right eyes were considered for statistical analysis. The changes of pupil size and total ocular aberrations after smoking were tested for significance by Wilcoxon signed ranks test. Results. Mean photopic pupil size decreased from 3.52 ± 0.73 mm to 3.29 ± 0.58 mm (P = 0.001) after smoking. Mean mesopic pupil size was also decreased from 6.42 ± 0.75 mm to 6.14 ± 0.75 mm after smoking (P = 0.001). There was a decrease in all the measured components of aberrations (total wavefront aberration, higher-order aberration, total coma, total trefoil, total tetrafoil, total spherical aberration and total higher-order aberration) after smoking; however the differences were insignificant for all (P > 0.05). Conclusion. Our results indicate that pupil constricts after smoking. On the other hand, smoking does not alter ocular aberrations. PMID:25699189

  6. Demonstration of multi- and single-reader sample size program for diagnostic studies software

    NASA Astrophysics Data System (ADS)

    Hillis, Stephen L.; Schartz, Kevin M.

    2015-03-01

    The recently released software Multi- and Single-Reader Sample Size Sample Size Program for Diagnostic Studies, written by Kevin Schartz and Stephen Hillis, performs sample size computations for diagnostic reader-performance studies. The program computes the sample size needed to detect a specified difference in a reader performance measure between two modalities, when using the analysis methods initially proposed by Dorfman, Berbaum, and Metz (DBM) and Obuchowski and Rockette (OR), and later unified and improved by Hillis and colleagues. A commonly used reader performance measure is the area under the receiver-operating-characteristic curve. The program can be used with typical common reader-performance measures which can be estimated parametrically or nonparametrically. The program has an easy-to-use step-by-step intuitive interface that walks the user through the entry of the needed information. Features of the software include the following: (1) choice of several study designs; (2) choice of inputs obtained from either OR or DBM analyses; (3) choice of three different inference situations: both readers and cases random, readers fixed and cases random, and readers random and cases fixed; (4) choice of two types of hypotheses: equivalence or noninferiority; (6) choice of two output formats: power for specified case and reader sample sizes, or a listing of case-reader combinations that provide a specified power; (7) choice of single or multi-reader analyses; and (8) functionality in Windows, Mac OS, and Linux.

  7. TEM and Moessbauer Study of Nano Sized Fe{sub 2}MnAl Flakes

    SciTech Connect

    Vinesh, A.; Sudheesh, V. D.; Lakshmi, N.; Venugopalan, K.

    2011-07-15

    Magnetic and structural properties of L21 ordered Fe{sub 2}MnAl Heusler alloy have been studied by X-ray diffraction, Transmission electron microscopy (TEM), Moessbauer spectroscopy and DC magnetization. Structural texturing induced by ball milling is destroyed on heating while Moessbauer and DC magnetization studies show magnetic texturing persists after thermal treatment. TEM shows large distribution in particle size with an average size of 27 nm. Thermal annealing of ball milled sample results L2{sub 1} ordering and the needle shaped particle contributes spin texturing.

  8. Simulation studies of acceleration of heavy ions and their elemental compositions; IFSR--755

    SciTech Connect

    Toida, Mieko; Ohsawa, Yukiharu

    1996-07-01

    By using a one-dimensional, electromagnetic particle simulation code with full ion and electron dynamics, we have studied the acceleration of heavy ions by a nonlinear magnetosonic wave in a multi-ion-species plasma. First, we describe the mechanism of heavy ion acceleration by magnetosonic waves. We then investigate this by particle simulations. The simulation plasma contains four ion species: H, He, O, and Fe. The number density of He is taken to be 10% of that of H, and those of O and Fe are much lower. Simulations confirm that, as in a single-ion-species plasma, some of the hydrogens can be accelerated by the longitudinal electric field formed in the wave. Furthermore, they show that magnetosonic waves can accelerate all the particles of all the heavy species (He, O, and Fe) by a different mechanism, i.e., by the transverse electric field. The maximum speeds of the heavy species are about the same, of the order of the wave propagation speed. These are in good agreement with theoretical prediction. These results indicate that, if high-energy ions are produced in the solar corona through these mechanisms, the elemental compositions of these heavy ions can be similar to that of the background plasma, i.e., the corona.

  9. Exposure to Air Ions in Indoor Environments: Experimental Study with Healthy Adults

    PubMed Central

    Wallner, Peter; Kundi, Michael; Panny, Michael; Tappler, Peter; Hutter, Hans-Peter

    2015-01-01

    Since the beginning of the 20th century there has been a scientific debate about the potential effects of air ions on biological tissues, wellbeing and health. Effects on the cardiovascular and respiratory system as well as on mental health have been described. In recent years, there has been a renewed interest in this topic. In an experimental indoor setting we conducted a double-blind cross-over trial to determine if higher levels of air ions, generated by a special wall paint, affect cognitive performance, wellbeing, lung function, and cardiovascular function. Twenty healthy non-smoking volunteers (10 female, 10 male) participated in the study. Levels of air ions, volatile organic compounds and indoor climate factors were determined by standardized measurement procedures. Air ions affected the autonomous nervous system (in terms of an increase of sympathetic activity accompanied by a small decrease of vagal efferent activity): In the test room with higher levels of air ions (2194/cm3 vs. 1038/cm3) a significantly higher low to high frequency ratio of the electrocardiography (ECG) beat-to-beat interval spectrogram was found. Furthermore, six of nine subtests of a cognitive performance test were solved better, three of them statistically significant (verbal factor, reasoning, and perceptual speed), in the room with higher ion concentration. There was no influence of air ions on lung function and on wellbeing. Our results indicate slightly activating and cognitive performance enhancing effects of a short-term exposure to higher indoor air ion concentrations. PMID:26569277

  10. Exposure to Air Ions in Indoor Environments: Experimental Study with Healthy Adults.

    PubMed

    Wallner, Peter; Kundi, Michael; Panny, Michael; Tappler, Peter; Hutter, Hans-Peter

    2015-11-01

    Since the beginning of the 20th century there has been a scientific debate about the potential effects of air ions on biological tissues, wellbeing and health. Effects on the cardiovascular and respiratory system as well as on mental health have been described. In recent years, there has been a renewed interest in this topic. In an experimental indoor setting we conducted a double-blind cross-over trial to determine if higher levels of air ions, generated by a special wall paint, affect cognitive performance, wellbeing, lung function, and cardiovascular function. Twenty healthy non-smoking volunteers (10 female, 10 male) participated in the study. Levels of air ions, volatile organic compounds and indoor climate factors were determined by standardized measurement procedures. Air ions affected the autonomous nervous system (in terms of an increase of sympathetic activity accompanied by a small decrease of vagal efferent activity): In the test room with higher levels of air ions (2194/cm³ vs. 1038/cm³) a significantly higher low to high frequency ratio of the electrocardiography (ECG) beat-to-beat interval spectrogram was found. Furthermore, six of nine subtests of a cognitive performance test were solved better, three of them statistically significant (verbal factor, reasoning, and perceptual speed), in the room with higher ion concentration. There was no influence of air ions on lung function and on wellbeing. Our results indicate slightly activating and cognitive performance enhancing effects of a short-term exposure to higher indoor air ion concentrations.

  11. The study towards high intensity high charge state laser ion sources.

    PubMed

    Zhao, H Y; Jin, Q Y; Sha, S; Zhang, J J; Li, Z M; Liu, W; Sun, L T; Zhang, X Z; Zhao, H W

    2014-02-01

    As one of the candidate ion sources for a planned project, the High Intensity heavy-ion Accelerator Facility, a laser ion source has been being intensively studied at the Institute of Modern Physics in the past two years. The charge state distributions of ions produced by irradiating a pulsed 3 J/8 ns Nd:YAG laser on solid targets of a wide range of elements (C, Al, Ti, Ni, Ag, Ta, and Pb) were measured with an electrostatic ion analyzer spectrometer, which indicates that highly charged ions could be generated from low-to-medium mass elements with the present laser system, while the charge state distributions for high mass elements were relatively low. The shot-to-shot stability of ion pulses was monitored with a Faraday cup for carbon target. The fluctuations within ±2.5% for the peak current and total charge and ±6% for pulse duration were demonstrated with the present setup of the laser ion source, the suppression of which is still possible.

  12. The study towards high intensity high charge state laser ion sources.

    PubMed

    Zhao, H Y; Jin, Q Y; Sha, S; Zhang, J J; Li, Z M; Liu, W; Sun, L T; Zhang, X Z; Zhao, H W

    2014-02-01

    As one of the candidate ion sources for a planned project, the High Intensity heavy-ion Accelerator Facility, a laser ion source has been being intensively studied at the Institute of Modern Physics in the past two years. The charge state distributions of ions produced by irradiating a pulsed 3 J/8 ns Nd:YAG laser on solid targets of a wide range of elements (C, Al, Ti, Ni, Ag, Ta, and Pb) were measured with an electrostatic ion analyzer spectrometer, which indicates that highly charged ions could be generated from low-to-medium mass elements with the present laser system, while the charge state distributions for high mass elements were relatively low. The shot-to-shot stability of ion pulses was monitored with a Faraday cup for carbon target. The fluctuations within ±2.5% for the peak current and total charge and ±6% for pulse duration were demonstrated with the present setup of the laser ion source, the suppression of which is still possible. PMID:24593615

  13. Experimental studies on ion acceleration and stream line detachment in a diverging magnetic field

    SciTech Connect

    Terasaka, K.; Ogiwara, K.; Tanaka, M. Y.; Yoshimura, S.; Aramaki, M.

    2010-07-15

    The flow structure of ions in a diverging magnetic field has been experimentally studied in an electron cyclotron resonance plasma. The flow velocity field of ions has been measured with directional Langmuir probes calibrated with the laser induced fluorescence spectroscopy. For low ion-temperature plasmas, it is concluded that the ion acceleration due to the axial electric field is important compared with that of gas dynamic effect. It has also been found that the detachment of ion stream line from the magnetic field line takes place when the parameter |f{sub ci}L{sub B}/V{sub i}| becomes order unity, where f{sub ci}, L{sub B}, and V{sub i} are the ion cyclotron frequency, the characteristic scale length of magnetic field inhomogeneity, and the ion flow velocity, respectively. In the detachment region, a radial electric field is generated in the plasma and the ions move straight with the ExB rotation driven by the radial electric field.

  14. Surface microanalytical studies of nitrogen ion-implanted steel

    NASA Astrophysics Data System (ADS)

    Dodd, Charles G.; Meeker, G. P.; Baumann, Scott M.; Norberg, James C.; Legg, Keith O.

    1985-03-01

    Five types of industrial steels, 1018, 52100, M-2, 440C, and 304 were ion implanted with nitrogen and subjected to surface microanalysis by three independent surface techniques: AES, RBS, and SIMS. The results provided understanding for earlier observations of the properties of various types of steel after nitrogen implantation. The steels that retained the most nitrogen and that have been reported to benefit the most in improved tribological properties from ion implantation were ferritic carbon and austenitic stainless steels, such as soft 1018 and 304, respectively. Heat-treated martensitic carbon steels such as 52100 and M-2 tool steel were found to retain the least nitrogen, and they have been reported to benefit less from nitrogen implantation; however, the interaction of transition metal carbides in M-2 with nitrogen has not been clarified. The data showed that 440C steel retained as much nitrogen as 1018 and 304, but treatment benefits may be limited to improvements in properties related to toughness and impact resistance.

  15. High latitude minor ion enhancements: A clue for studies of magnetosphere-atmosphere coupling. [using OGO 6 ion mass spectrometer

    NASA Technical Reports Server (NTRS)

    Taylor, H. A., Jr.

    1973-01-01

    Unexpectedly abrupt and pronounced distributions of the thermal molecular ions NO(+), O2(+) and N2(+) were observed at mid and high latitudes by the OGO-6 ion mass spectrometer. These minor ions may reach concentration levels exceeding 1000 ions/cu cm at altitudes as great as 1000 km, suggestive of scale heights well in excess of those inferred from low and mid-latitude measurements, under relatively undisturbed conditions. The high latitude ion enhancements were observed to be narrowly defined in time and space, with molecular ion concentrations changing by as much as an order of magnitude between successive orbits.

  16. An experimental and theoretical study of the seepage migration of suspended particles with different sizes

    NASA Astrophysics Data System (ADS)

    Bai, Bing; Xu, Tao; Guo, Zhiguang

    2016-08-01

    This study experimentally investigates the effect of particle size, particle concentration and flow velocity on the migration of suspended particles of size 1.02-47 μm in porous media. The results show that at the same flow velocity, the peak values of the breakthrough curves decrease and corresponding pore volumes increase slightly with increasing particles size. The migration velocity of smaller suspended particles is even greater than water flow velocity, which is attributed to the size exclusion effect. With increase of the injected particle concentration, the deposition coefficients of small single particles increase at first and then tend to a steady state or even decrease slightly, explained by the maximum retention concentration. The dispersivity of small particles decreases with increasing velocity. However, at a high flow velocity, the hydrodynamic dispersivity becomes increasingly dominant with the increase of particle size. The deposition coefficients for large-sized particles are higher than those for small-sized particles, which is attributed to considerable mass removal due to straining. An analytical solution, considering the release effect of sorbed particles, is developed to account for the one-dimensional flow and dispersive effect using a source function method, and then three transport parameters—dispersivity, deposition coefficient and release coefficient—are fitted using the experimental results. Finally, suspended-particle migration is predicted by the proposed model for short-time constant-concentration injection and repeated three-pulse injection. Overall, particle size has a significant effect on the seepage migration parameters of suspended particles in porous media such as the particle velocity, dispersivity and deposition coefficient.

  17. Effects of Climate Change on Subterranean Termite Territory Size: A Simulation Study

    PubMed Central

    Lee, Sang-Hee; Chon, Tae-Soo

    2011-01-01

    In order to study how climate change affects the territory size of subterranean termites, a lattice model was used to simulate the foraging territory of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), and the minimized local rules that are based on empirical data from the development of termites' foraging territory was applied. A landscape was generated by randomly assigning values ranging from 0.0 to 1.0 to each lattice site, which represented the spatially distributed property of the landscape. At the beginning of the simulation run, N territory seeds - one for each founding pair, were randomly distributed on the lattice space. The territories grew during the summer and shrank during the winter. In the model, the effects of climate change were demonstrated by changes in two variables: the period of the summer season, T, and the percentage of the remaining termite cells, σ, after the shrinkage. The territory size distribution was investigated in the size descending order for the values of T (= 10, 15, ... , 50) and σ (= 10, 15, ... , 50) at a steady state after a sufficiently long time period. The distribution was separated into two regions: the larger-sized territories and the smaller-sized territories. The slope, m, of the distribution of territory size on a semi-log scale for the larger-sized territories was maximal with T (45 ≤ T ≤ 50) in the maximal range and with σ in the optimal range (30 ≤ σ ≤ 40), regardless of the value of N. The results suggest that the climate change can influence the termite territory size distribution under the proper balance of T and σ in combination. PMID:21870966

  18. A Initio Studies of Polarisabilities of Ions in Crystals.

    NASA Astrophysics Data System (ADS)

    Tole, Philip

    Available from UMI in association with The British Library. This thesis is concerned with the ab initio calculation of polarisabilities of ions in crystals. For a binary salt the Clausius-Mossotti equation relates the refractive index to the in-crystal polarisability of the ion-pair. However, there is no experimental means of separating the sum into anion and cation components. Theoretical models which use isolated ion polarisabilities to do this are physically unrealistic and have met with little success. A much better model has been developed using ab initio all-electron CHF calculations. The in-crystal environment is represented by a 'molecular' cluster embedded in a point-charge lattice. The physical features important to the success of the model are the nearest-neighbour overlap compression and the isotropic part of the electrostatic potential arising from the point -charge lattice. Calculations on simple first row alkali halides show the cation to be independent of these forces whereas the anion becomes, smaller, more bound and less polarisable in the crystal. When corrections for correlation are added the agreement with Clausius-Mossotti polarisabilities is at the 5% level or better. This implies a reduction in polarisability by factors of up to 2 with respect to the free ion. The polarisabilities for the anions in LiF, NaF, KF, LiCl, NaCl, KCl, LiBr, NaBr, KBr, CaF _2, BeO, MgO, CaO, Li_2O, Na_2O, K_2O, BeS, CaS, Li_2S, Na_2 S and K_2S were calculated. Anion polarisability is found to vary with lattice parameter but hardly at all with coordination number. Calculations on Be_2C show that in-crystal compression is sufficient to stabilise even C^{4 -}, which has a polarisability of over 20 au. Anions at the surface of LiF and MgO were also modelled. Because anisotropic overlap and electrostatic factors tend to cancel, the ion in 5-, 4- and 3-coordinate surface sites has a polarisability only a few per cent greater than in the bulk solid. Implications for

  19. Theoretical study of electron capture in ion-ion and ion-atom collisions. Progress report, September 1, 1980-April 30, 1981

    SciTech Connect

    Lieber, M.; Chan, F.T.

    1981-04-01

    The eikonal approximation has been recently shown to be of significant utility in the study of electron capture cross sections for energetic ion-atom collisions. The method generally gives much better agreement with available experimental data than does the simple OBK approximation without substantially increasing the difficulty of computation. In the present work, the total cross section is computed for electron capture into an arbitrary nl subshell of H/sup +/, C/sup +6/, O/sup +8/, and Fe/sup +24/ ions from ground state hydrogen atoms, at energies of 40 to 200 keV/nuclear (30 to 100 keV in the H/sup +/ case). These species were selected because of their importance in fusion studies. Interesting variations with l were obtained. Cross sections for capture into an arbitrary final n-shell, or into all final bound states were also obtained. An analytical closed form expression is derived for electron capture from an arbitrary initial nlm state to an arbitrary final n'l'm' state of a hydrogenic target. Numerical results are presented for all n' = 2,3 final states in hydrogen, which may be subjected to experimental test in the near future. Extension of the eikonal method to multielectron targets was studied. There are ambiguities in the method requiring further analysis. Agreement with experimental data is nevertheless satisfactory, but the high energy results are suspect.

  20. A Experimental Study of Ion Behavior in the Advanced Toroidal Facility

    NASA Astrophysics Data System (ADS)

    Wade, Mickey Ray

    Stellarators represent one of the most promising magnetic confinement concepts for a fusion reactor because of their intrinsic ability to operate at steady state, though legitimate concerns about various aspects of the stellarator concept must be addressed. One of these concerns is the seemingly unfavorable single-particle confinement properties inherent to the stellarator design. Although previous experimental studies of ion confinement in stellarators have indicated that the ions behave classically and are generally well confined, these studies were limited in scope. To complement these experiments and to provide additional information about ion behavior in stellarators, an experimental investigation of ion behavior has been performed on the Advanced Toroidal Facility (ATF). Measurements were made of both the thermal- and fast-ion distributions during electron cyclotron heating (ECH) and neutral beam injection (NBI). The purpose of this work was to study thermal- and fast-ion confinement in ATF with particular emphasis placed on constructing a consistent picture of ion confinement based on experimentally measured data. The primary ion diagnostic used in these studies was a two -dimensional scanning neutral particle analyzer (NPA). Extensive studies of fast-ion behavior in various operating regimes on ATF were conducted. These studies were performed during NBI and encompass a wide range of plasma densities, ranging from extremely low density ( |{n}_{e} <=q 7.5 times 10 ^{12} cm^{ -3}) to extremely high density (| {n}_{e} >=q 8.0 times 10^ {13} cm^{-3}) . Fokker-Planck simulations of the measured data suggest that the injected ions behave classically and indicate that the injected beam power is not well absorbed at low and intermediate densities because of large charge-exchange and shine-through losses. Further simulations using the PROCTR transport analysis code indicate that this reduced absorption is probably the cause of the thermal collapse observed in