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Sample records for cu esr studies

  1. IR and ESR studies on novel Cu(II) theophyllinato complexes containing mono- or bidentate ligands

    NASA Astrophysics Data System (ADS)

    Forizs, Edit; David, L.; Cozar, O.; Chiş, V.; Damian, G.; Csibi, Jolán

    1999-05-01

    Three mixed-ligand copper(II) complexes containing theophylline and mono- or bidentate N-donor ligands (2,2'-bipyridine, 4-fluoraniline and 1,10-phenanthroline) were synthesized and characterized by elemental analysis, IR and ESR spectra. According to IR and ESR data the Cu(II) complexes exhibit a distorted tetrahedral coordination of copper by two nitrogen atoms of the monodentate or bidentate ligands and the two monodentate theophyllinate anion bonded through N(7) atom.

  2. ESR studies of Anatolian gypsum

    NASA Astrophysics Data System (ADS)

    Ulusoy, Ülkü

    2004-05-01

    Electron spin resonance (ESR) was used to date the formation and most recent recrystallization of three types of gypsum samples (massive, bedded and fracture filling gypsum) from the Sakarya Formation at Eskişehir in the middle of Turkey. The ESR spectra had the signals of Fe 3+ and Mn 2+ in addition to those of the G1 and G2 sensitive centers ( g=2.002 and 2.008) to artificial γ-irradiation. ESR intensities of G1 and G2 were enhanced by γ-ray irradiation to give equivalent doses DE for each sample. The ESR ages derived from the annual doses of 238U, 232Th and 40K contents of the samples determined by thermal neutron activation analysis (TNAA) were between 43±18 ka (massive gypsum) and 1100±466 ka (bedded gypsum) as minimal and maximal values. The ages fall into the upper Miocene-Pliocene Epoch of the geological time scale, which agreed with the stratigraphy.

  3. ESR experiments and spectra simulations in YBa2Cu3O7-x, Y2BaCuO5, and BaCuO2+x

    NASA Astrophysics Data System (ADS)

    de Mesquita, R. N.; Castilho, J. H.; Barberis, G. E.; Rettori, C.; Torriani, I.; de Lima, O. F.; Gama, S.; Jardim, R. F.; Terrile, M. C.; Basso, H.; Nascimento, O. R.

    1989-04-01

    Room-temperature X- and Q-band ESR spectra of the high-Tc superconductor YBa2Cu3O7-x and the semiconductors Y2BaCuO5 and BaCuO2+x are studied experimentally and theoretically by measuring, calculating, and fitting the powder spectra corresponding to an anisotropic Zeeman Hamiltonian for Cu2+ in orthorhombic and tetragonal local symmetries. ESR and x-ray studies in their correspoinding oxygen-deficient stoichiometries, obtained by heat treatment under vacuum, were also done. Our results support those of Bowden et al. and Vier et al. in RBa2Cu3O7-x (R=Y, Eu), indicating that the Cu(1) and Cu(2) atoms in the pure YBa2Cu3O7-x phase are not ESR active and the small resonance observed in these compounds comes from other residual phases. The purest YBa2Cu3O7-xsamples that we were able to prepare still have 0.1-0.5 % mass fraction of other residual copper compounds which are responsible for the observed resonance.

  4. ESR study of free radicals in mango

    NASA Astrophysics Data System (ADS)

    Kikuchi, Masahiro; Hussain, Mohammad S.; Morishita, Norio; Ukai, Mitsuko; Kobayashi, Yasuhiko; Shimoyama, Yuhei

    2010-01-01

    An electron spin resonance (ESR) spectroscopic study of radicals induced in irradiated fresh mangoes was performed. Mangoes in the fresh state were irradiated with γ-rays, lyophilized and then crushed into a powder. The ESR spectrum of the powder showed a strong main peak at g = 2.004 and a pair of peaks centered at the main peak. The main peak was detected from both flesh and skin specimens. This peak height gradually decreased during storage following irradiation. On the other hand, the side peaks showed a well-defined dose-response relationship even at 9 days post-irradiation. The side peaks therefore provide a useful means to define the irradiation of fresh mangoes.

  5. ESR and photoluminescence properties of Cu doped ZnS nanoparticles

    NASA Astrophysics Data System (ADS)

    Sambasivam, S.; Sathyaseelan, B.; Raja Reddy, D.; Reddy, B. K.; Jayasankar, C. K.

    2008-12-01

    Nanoparticles of Zn 1- xCu xS with Cu concentrations of x = 0.0, 0.1, 0.2, 0.3 and 0.4 were prepared by a co-precipitation reaction method from homogeneous solutions of zinc and copper salts. Both the ZnS and ZnS:Cu nanoparticles excited at about 370 nm exhibits a broad green emission band peaking around 491 nm, which confirms the characteristic feature of Zn 2+ as well as Cu 2+ ions as luminescent centers in the lattice. The TEM micrographs showed spherical morphology for ZnS nanocrystals and the average size of the particles was estimated to be around 8.5 nm. At liquid nitrogen temperature, ESR signal characteristic of Cu 2+ ions was observed in samples of all concentrations. ESR spectra analysis also indicated that Cu 2+ ions enter the host lattice by replacing Zn 2+ ions with distorted tetrahedral site symmetry.

  6. ESR studies on bleached sedimentary quartz

    NASA Astrophysics Data System (ADS)

    Walther, R.; Zilles, D.

    Some ESR signals in quartz are reported to be bleachable by sunlight and so they promise to be useful for dating sediments (Grün, 1989). The Ge signal in quartz is the only one that shows bleaching effects with UV light in short time scales (hours). Therefore we used quartz samples from the sites of Mauer ( 'Homo erectus heidelbergensis'), samples from a borehole in the Neckar valley ('Entensee', Ladenburg near Heidelberg) and samples from a pegmatite for basic studies on the Ge signal. The results show that with our standard sample preparation procedure for quartz separation (using red light as for TL samples), the natural Ge signal is not detectable, but rises clearly with gamma irradiation. Several experiments for examination of the stability and sensitivity of the Ge centre in quartz were carried out. For comparison with the behaviour of the Ge signal we measured the Al signal as well. Our experiments show that the Al signal is bleachable in long time scales (weeks). The behaviour on bleaching, irradiation and thermal annealing is very complicated, as the Al centre is a hole centre (it possibly interacts with several electron centres in the quartz and so the processes are of higher order).

  7. ESR studies of the interaction of copper(II)GHK, histidine, and Ehrlich cells.

    PubMed

    Antholine, W E; Petering, D H; Pickart, L

    1989-03-01

    The tridentate complex CuGHK does not form ESR detectable adducts upon addition to either glutathione or Ehrlich ascites cells under our conditions. The absence of adducts is consistent with the poor uptake of CuGHK by cells. ESR spectra are used to characterize adduct formation between CuGHK and histidine. The CuGHK-histidine adduct is not stable in the presence of Ehrlich ascites tumor cells. It is argued that a Cu(His)2 complex is formed as a consequence of the interaction of GHK with cells. PMID:2542448

  8. Electron Spin Resonance (ESR) studies of returned comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Tsay, Fun-Dow; Kim, Soon Sam; Liang, Ranty H.

    1989-01-01

    The most important objective of the Comet Nucleus Sample Returm Mission is to return samples which could reflect formation conditions and evolutionary processes in the early solar nebula. It is expected that the returned samples will consist of fine-grained silicate materials mixed with ices composed of simple molecules such as H2O, NH3, CH4 as well as organics and/or more complex compounds. Because of the exposure to ionizing radiation from cosmic-ray, gamma-ray, and solar wind protons at low temperature, free radicals are expected to be formed and trapped in the solid ice matrices. The kind of trapped radical species together with their concentration and thermal stability can be used as a dosimeter as well as a geothermometer to determine thermal and radiation histories as well as outgassing and other possible alternation effects since the nucleus material was formed. Since free radicals that are known to contain unpaired electrons are all paramagnetic in nature, they can be readily detected and characterized in their native form by the Electron Spin Resonance (ESR) method. In fact, ESR has been shown to be a non-destructive, highly sensitive tool for the detection and characterization of paramagnetic, ferromagnetic, and radiation damage centers in terrestrial and extraterrestrial geological samples. The potential use of ESR as an effective method in the study of returned comet nucleus samples, in particular, in the analysis of fine-grained solid state icy samples is discussed.

  9. ESR Spectroscopy Provides Direct Evidence of Cu^2+ Coordination by Three Histidine Residues in Aβ1-16

    NASA Astrophysics Data System (ADS)

    Shin, Byong-Kyu; Saxena, Sunil

    2009-03-01

    We provide direct evidence that all three histidine residues in amyloid-β1-16 (Aβ1-16) coordinate to Cu^2+. In our approach, we generate three Aβ1-16 analogues, in each of which a selected histidine residue is isotopically enriched with ^15N. Pulsed electron spin resonance (ESR) experiments such as electron spin echo envelope modulation (ESEEM) and hyperfine sublevel correlation (HYSCORE) clearly show that each of the three histidine imidazole rings at position 6, 13, and 14 in Aβ1-16 binds to Cu^2+ as each of the three Cu^2+--^15N-labeled Aβ1-16 complexes displays ESEEM and HYSCORE spectra which are distinctively different from those of the Cu^2+--nonlabeled Aβ1-16 complex. The method employed here does not require either chemical side-chain modification or amino acid residue replacement, each of which is traditionally used to determine whether an amino acid residue in a protein binds to a metal ion. We also find that the histidine coordination in Aβ1-16 is independent of the Cu^2+-to-peptide ratio, which is in contrast to the case of Aβ1-40. The ESR results suggest tight binding between the histidine residues and the Cu^2+ ion, which is likely the reason of the high binding affinity of Aβ peptide to Cu^2+.

  10. A simple double quantum coherence ESR sequence that minimizes nuclear modulations in Cu2+-ion based distance measurements

    NASA Astrophysics Data System (ADS)

    Ruthstein, Sharon; Ji, Ming; Shin, Byong-kyu; Saxena, Sunil

    2015-08-01

    Double quantum coherence (DQC) ESR is a sensitive method to measure magnetic dipolar interactions between spin labels. However, the DQC experiment on Cu2+ centers presents a challenge at X-band. The Cu2+ centers are usually coordinated to histidine residues in proteins. The electron-nuclear interaction between the Cu2+ ion and the remote nitrogen in the imidazole ring can interfere with the electron-electron dipolar interaction. Herein, we report on a modified DQC experiment that has the advantage of reduced contributions from electron-nuclear interactions, which enhances the resolution of the DQC signal to the electron-electron dipolar modulations. The modified pulse-sequence is verified on Cu2+-NO system in a polyalanine-based peptide and on a coupled Cu2+ system in a polyproline-based peptide. The modified DQC data were compared with the DEER data and good agreement was found.

  11. ESR study of superconducting K-doped C 60 "polymer"

    NASA Astrophysics Data System (ADS)

    Kinoshita, N.; Grigoryan, L. S.; Kinoshita, T.; Tokumoto, M.

    1997-03-01

    ESR measurements of the superconducting K-doped C 60 "polymer" were carried out, in order to clarify the difference from ordinary K-doped C 60, i.e. monomer. Observed ESR spectrum was simulated by four Lorentzian lines. The temperature dependences of the ESR linewidth, g factor and spin susceptibility are obtained for each ESR line. At room temperature the linewidth and g factor of the broadest ESR absorption line are, about 400 G and 2.01, respectively. The linewidths for other lines are 150, 53 and 16 G with the common g factor of 2.000. The linewidths of the ESR spectrum of superconducting K-doped C 60 "polymer" are found to be much broader than those of monomer sample. Similar to monomer sample, two absorption lines with weakly temperature-dependent intensity were observed, one of which disappeared (150 G width) below the super-conducting transition temperature ( Tc = 15 K).

  12. Study on anisotropic quantum transport in graphene sheets by ESR

    NASA Astrophysics Data System (ADS)

    Yan, Liqin; Sun, Young; Huang, Jiao; Chen, Xiaolong

    Quantum transport in graphene has attracted much attention due to its excellent thermal conductivity and high room-temperature electron mobility. Using the electron spin resonance (ESR) spectrometer for studying weak localization (WL) and weak antilocalization (WAL) effects, except for having the obvious advantage of no need for electrical contacts, differs from the electric transport measurement technique also in the dominant signal from the surface of the layer not from the bulk substrate. Here we have studied an experimental anisotropic quantum transport performed on an assemblage of vertical aligned graphene sheets from 5 to 300 K by a Bruker X-band (9.3 GHz). An anisotropic quantum transport is observed between b with WL and c with WAL axes at 5 - 50 K. With increasing temperature, the transport mechanism is changed along b and c axes. We use WL theory to fit all the spectra and obtain the coherence length Lϕ, long range scattering length Llr, intervalley scattering length Li and analyze the data. Our results indicate that ESR is a robust platform to study the intrinsic physical properties of graphene.

  13. ESR study of the photochemistry of benzoic acid derivatives

    SciTech Connect

    Jeevarajan, A.S.; Fessenden, R.W. )

    1992-12-16

    Electron spin resonance (ESR) has been used to study radical intermediates in the photochemistry of a number of aromatic carboxylic acids, esters, anhydrides, amides, imides, and nitriles. Continuous photolysis was used to produce the radicals in either aqueous or alcoholic media. The triplet states of the compounds undergo two reactions in the presence of a hydrogen donor such as 2-propanol. A hydrogen atom is transferred to certain carbon atoms of the aromatic ring forming cyclohexadienyl radicals. In most cases, addition occurs at or opposite the carboxyl (or cyano) group. The pattern of addition is attributed to the higher spin density in the triplet at those positions. This pattern also correlates with the positions of higher hyperfine splitting in the corresponding anion radicals. In a parallel reaction, a hydrogen atom is also transferred to an oxygen of the carboxyl group (for acids, anhydrides, and esters) to form the one-electron-reduction product. The cyclohexadienyl radicals are not formed by protonation on a carbon of an anion radical. The ESR spectra of most of the cyclohexadienyl radicals are highly polarized to the extent that the low-field lines appear in emission. This effect is believed to be normal chemically induced dynamic spin polarization (CIDEP) as a result of cross reactions with the other radicals present. 46 refs., 7 figs., 10 tabs.

  14. ESR, optical absorption, IR and Raman studies of xTeO{sub 2} + (70 - x)B{sub 2}O{sub 3} + 5TiO{sub 2} + 24R{sub 2}O:1CuO (x = 10, 35 and 60 mol%; R = Li, Na and K) quaternary glass system

    SciTech Connect

    Suresh, S.; Gayathri Pavani, P.; Chandra Mouli, V.

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Peak of Cu{sup 2+} is found to be maximum at around 794 nm for lithium boro tellurite glasses. Black-Right-Pointing-Pointer Variation in g{sub ||} and A{sub ||} values is due to change in environment of Cu{sup 2+} ion due to the structural change in the glass. Black-Right-Pointing-Pointer BO{sub 3}-BO{sub 4}{sup -} ring structure is interconnected by TeO{sub 3}{sup -} and TeO{sub 4}{sup -} groups, where the BO{sub 4}{sup -} groups are neighbors of TeO{sub 3}{sup -}groups. Black-Right-Pointing-Pointer The structure comprising, isolate a BO{sub 3}{sup -}, B{sub 2}O{sub 5}, BO{sub 4}{sup -}, and metaborates, which enables glass forming for Borate rich glasses. Black-Right-Pointing-Pointer Distorted TeO{sub 4/2} network with BO{sub 3}{sup -}-BO{sub 4}{sup -} ring structure and TeO{sub 3}{sup -} group is enables glass forming for tellurite rich glasses. -- Abstract: xTeO{sub 2} + (70 - x)B{sub 2}O{sub 3} + 5TiO{sub 2} + 24R{sub 2}O:1CuO (x = 10, 35 and 60; R = Li, Na and K) glass system were studied by spectroscopic techniques such as ESR, optical absorption, Raman and IR. From ESR spectra, the spin Hamiltonian parameter values indicate that the ground state of Cu{sup 2+} is d{sub x{sup 2}-y{sup 2}} and the site symmetry around the Cu{sup 2+} ion is tetragonally distorted octahedral coordination. Bonding parameters calculated from optical absorption and ESR data are found to change with alkali oxide and TeO{sub 2} content. Bonding parameters indicate a slight covalency for the in-plane {sigma} bonding as compared to in-plane and out-of-plane {pi} bonds. Both Raman and IR results show that glass network consists of TeO{sub 3}, TeO{sub 4}, BO{sub 3}, BO{sub 4} and RiO{sub 4} group as basic structural groups. BO{sub 3}-BO{sub 4}{sup -} ring structure interconnected by TeO{sub 3}{sup -} and TeO{sub 4}{sup -} groups, where the BO{sub 4}{sup -} groups are neighbors of the TeO{sub 3}{sup -} groups. BO{sub 3} {yields} BO{sub 4

  15. Diffusion studies on permeable nitroxyl spin probes through bilayer lipid membranes: A low frequency ESR study

    SciTech Connect

    Meenakumari, V.; Benial, A. Milton Franklin; Utsumi, Hideo; Ichikawa, Kazuhiro; Yamada, Ken-ichi; Hyodo, Fuminori; Jawahar, A.

    2015-06-24

    Electron spin resonance (ESR) studies were carried out for permeable 2mM {sup 14}N-labeled deutrated 3 Methoxy carbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) in pure water and 1mM, 2mM, 3mM, 4mM concentration of 14N-labeled deutrated MC-PROXYL in 400mM concentration of liposomal solution by using a 300 MHz ESR spectrometer. The ESR parameters such as linewidth, hyperfine coupling constant, g-factor, partition parameter and permeability were reported for these samples. The line broadening was observed for the nitroxyl spin probe in the liposomal solution. The line broadening indicates that the high viscous nature of the liposomal solution. The partition parameter and permeability values indicate the maximum diffusion of nitroxyl spin probes in the bilayer lipid membranes at 2 mM concentration of nitroxyl radical. This study illustrates that ESR can be used to differentiate between the intra and extra- membrane water by loading the liposome vesicles with a lipid-permeable nitroxyl spin probe. From the ESR results, the spin probe concentration was optimized as 2mM in liposomal solution for ESR phantom studies/imaging, invivo and invitro experiments.

  16. ESR studies of two new organic superconductors: {beta}``-(BEDT-TTF){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} and {kappa}{sub L}`-(BEDT-TTF){sub 2}Cu(CF{sub 3}){sub 4}(DBCE)

    SciTech Connect

    Wang, H.H.; VanZile, M.L.; Geiser, U.

    1996-10-01

    The normal-state ESR of two new organic superconductors, {beta}{double_prime}-(BEDT-TTF){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} and {kappa}{sub L}{prime}-(BEDT-TTF){sub 2}Cu(CF{sub 3}){sub 4}(DBCE) are reported. Both compounds showed metallic properties below 140 K. The former gave ESR line widths and g-values of 23-34 G and 2.004-2.012. The latter gave line widths and g-values of 45-58 G and 2.006-2.012. Orientation-dependent line widths and g-values of the {kappa}{sub L}{prime}-phase were found to be similar to that of the {kappa}-(ET){sub 4}Hg{sub 3}Br{sub 8} but not to the {kappa}{sub L}-phases in general.

  17. Persistent free radicals in woodsmoke: An ESR spin trapping study

    SciTech Connect

    Lachocki, T.M.; Church, D.F.; Pryor, W.A. )

    1989-01-01

    Free radicals are detected in the gas-phase smoke resulting from the combustion of wood using the electron spin resonance (ESR) spin trapping method. The materials were pyrolyzed by rapid heating in a quartz tube in a flowing air stream. The filtered smoke was bubbled into a dodecane solution of alpha-phenyl-N-tert-butyl nitrone, and the resulting nitroxide radicals were detected by ESR. The radicals spin trapped from woodsmoke are compared to those we have spin trapped from tobacco smoke; the smoke from both yellow pine and oak produce more intense ESR spectra than does tobacco smoke per unit mass burned under the conditions of these experiments. When woodsmoke is bubbled through pure dodecane and the resulting woodsmoke/dodecane solution is held for a delay time before the PBN is added, radicals are detected even after the woodsmoke/dodecane solution is aged for more than 20 min. Similar experiments with tobacco smoke show that radicals no longer are trapped even after much shorter delay times from tobacco smoke/dodecane solutions.

  18. ESR Study on Irradiated Ascorbic Acid Single Crystal

    NASA Astrophysics Data System (ADS)

    Tuner, H.; Korkmaz, M.

    2007-04-01

    Food irradiation is a ``cold'' process for preserving food and has been established as a safe and effective method of food processing and preservation after more than five decades of research and development. The small temperature increase, absence of residue and effectiveness of treatment of pre-packed food are the main advantages. In food industry, ascorbic acid and its derivatives are frequently used as antioxidant agents. However, irradiation is expected to produces changes in the molecules of food components and of course in the molecules of the agents added as preservation agents such as ascorbic acid. These changes in the molecular structures could cause decreases in the antioxidant actions of these agents. Therefore, the radiation resistance of these agents must be known to determine the amount of radiation dose to be delivered. Electron spin resonance (ESR) is one of the leading methods for identification of intermediates produced after irradiation. ESR spectrum of irradiated solid powder of ascorbic acid is fairly complex and determinations of involved radical species are difficult. In the present work, single crystals of ascorbic acid irradiated by gamma radiation are used to determine molecular structures of radiation induced radicalic species and four radicalic species related in pair with P21 crystal symmetry are found to be responsible from experimental ESR spectrum of gamma irradiated single crystal of ascorbic acid.

  19. ESR Study on Irradiated Ascorbic Acid Single Crystal

    SciTech Connect

    Tuner, H.; Korkmaz, M.

    2007-04-23

    Food irradiation is a 'cold' process for preserving food and has been established as a safe and effective method of food processing and preservation after more than five decades of research and development. The small temperature increase, absence of residue and effectiveness of treatment of pre-packed food are the main advantages. In food industry, ascorbic acid and its derivatives are frequently used as antioxidant agents. However, irradiation is expected to produces changes in the molecules of food components and of course in the molecules of the agents added as preservation agents such as ascorbic acid. These changes in the molecular structures could cause decreases in the antioxidant actions of these agents. Therefore, the radiation resistance of these agents must be known to determine the amount of radiation dose to be delivered. Electron spin resonance (ESR) is one of the leading methods for identification of intermediates produced after irradiation. ESR spectrum of irradiated solid powder of ascorbic acid is fairly complex and determinations of involved radical species are difficult. In the present work, single crystals of ascorbic acid irradiated by gamma radiation are used to determine molecular structures of radiation induced radicalic species and four radicalic species related in pair with P21 crystal symmetry are found to be responsible from experimental ESR spectrum of gamma irradiated single crystal of ascorbic acid.

  20. ESR, SIMS and TEMF of an Y-Ba-Cu-O superconductor

    NASA Technical Reports Server (NTRS)

    Kirschner, I.; Giber, J.; Halasz, I.

    1995-01-01

    Superconducting transition comes into being between 92 K and 82 K in the samples having a Meissner's state value of 68 vol. percent. The main material content has an orthorhombic unit cell of Y1Ba2Cu408 accompanied by low quantity CuO and a sporadic phase. A proof of anisotropic superconductivity, an unusually high Cu ion concentration and a temperature dependent transition of charge carriers have been observed.

  1. Spin dynamics in the La1.85Sr0.15Cu1-xFexO4 system probed by ESR

    NASA Astrophysics Data System (ADS)

    Cieplak, Marta Z.; Sienkiewicz, A.; Mila, F.; Guha, S.; Xiao, Gang; Xiao, J. Q.; Chien, C. L.

    1993-08-01

    We study the magnetic properties of the La1.85Sr0.15Cu1-xFexO4 system (x=0-0.1) in the vicinity of the metal-insulator (MI) transition using static-susceptibility measurements and the electron-spin resonance (ESR) of the Fe ions. Spin-glass (SG) freezing is present for all nonsuperconducting specimens. The iron ESR line broadens on approaching the freezing temperature, similarly to the effect observed in canonical spin glasses. This broadening can be attributed to the influence of the slowing down of spin fluctuations on the spin-spin relaxation rate. It depends differently on x on the two different sides of the MI transition suggesting the existence of two different SG phases: insulating (ISG) where the Fe spins couple to the Cu-spin array by superexchange interactions, and metallic (MSG), where there exists, in addition, Ruderman-Kittel-Kasuya-Yosida-like coupling mediated by the free carriers. The proximity of the MI transition suppresses this coulping, giving rise to the observed dependence of the paramagnet -SG phase boundary on x. In the MSG phase, at high temperatures, the spin-lattice relaxation mechanism is also mediated by the free carriers. It differs from the analogous process observed in conventional metals in that the ESR linewidth increases with increasing T faster than linearly. We explain this behavior by assuming that the effective magnetic field felt by the Fe moments originates mainly from the spins of holes located on the nearest-neighbor oxygen ions. The linewidth divided by T which probes the dynamical susceptibility at the Fe site varies as a+bT. Here a goes to zero as the MI transition is approached and so plays the role of the Pauli susceptibility of the free carriers, whereas b is independent of x in the vicinity of the MI transition but decreases for small Fe dopings away from the MI transition and may be identified as originating from the antiferromagnetic spin fluctuations in the system.

  2. ESR studies on hot-wire amorphous silicon

    SciTech Connect

    Unold, T.; Mahan, A.H.

    1997-07-01

    The authors measure a series of hot-wire (HW) amorphous silicon films grown with hydrogen contents C{sub H} varying between 0.5--17 at.%. From constant photocurrent method (CPM) measurements and the steady-state photocarrier grating method (SSPG) they find good agreement with previous measurements on similar hot-wire films. Electron spin resonance measurements on the same samples, however, yield significantly higher spin densities than expected. A thickness series indicates a highly defective layer close to the substrate interface. They propose that this defective layer may be due to excessive out diffusion of hydrogen during growth at high temperatures, as seen by secondary ion mass spectroscopy. ESR measurements on light-degraded samples indicate an improved stability of samples with C{sub H} < 9 at.%.

  3. Correlation between erythrocyte sedimentation rate (ESR) dynamics and blood luminescence studied using optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Novikov, Cyril N.; Bouravleva, Ekaterina V.; Fadyukova, Olga E.; Voeikov, Vladimir V.; Koshelev, Vladimir B.

    2003-10-01

    Simultaneous temporal analysis of whole human or rat blood luminescence and erythrocytes sedimentation rate (ESR) in same blood using special computerized optoelectronic devices for single photon counting and for high temporal resolution of the rate of sedimentation of red blood/plasma boundary revealed correlation between both time series. Correlation was observed in vitro in normal blood, after action of physical (height of blood column) and of chemical (hydrogen peroxide) factors, and in experimental cerebral ischemia. An ischemia was invoked in rats by occlusion of both common carotid arteries. ESR was studied with the device "ESR-scan" and the dynamics of respiratory burst (RB) by a luminol-dependent luminescence method on the same blood samples. There was a noticeable increase of intensity of RB in whole rat blood and significant acceleration of ESR in blood diluted on 50% in 90 minutes after applying a ligature on carotid arteries. The individual differences between animals attesting to different degree of RB and ESR activation in blood both in intact animals and after operational intervention was obtained. Revealed correlation points to considerable relation between blood energy and its mechanical properties.

  4. In vivo copper-mediated free radical production: an ESR spin-trapping study

    NASA Astrophysics Data System (ADS)

    Kadiiska, Maria B.; Mason, Ronald P.

    2002-04-01

    Copper has been suggested to facilitate oxidative tissue injury through a free radical-mediated pathway analogous to the Fenton reaction. By applying the electron spin resonance (ESR) spin-trapping technique, evidence for hydroxyl radical formation in vivo was obtained in rats treated simultaneously with copper and ascorbic acid or paraquat. A secondary radical spin-trapping technique was used in which the hydroxyl radical formed the methyl radical upon reaction with dimethylsulfoxide. The methyl radical was then detected by ESR spectroscopy as its adduct with the spin trap phenyl- N- t-butyl- nitrone (PBN). In contrast, lipid derived radical was detected in vivo in copper-challenged, vitamin E and selenium-deficient rats. These findings support the proposal that dietary selenium and vitamin E can protect against lipid peroxidation and copper toxicity. Since copper excreted into the bile from treated animals is expected to be maintained in the Cu(I) state (by ascorbic acid or glutathione), a chelating agent that would redox-stablilize it in the Cu(I) state was used to prevent ex vivo redox chemistry. Bile samples were collected directly into solutions of bathocuproinedisulfonic acid, a Cu(I)-stabilizing agent, and 2,2'-dipyridyl, a Fe(II)-stabilizing agent. If these precautions were not taken, radical adducts generated ex vivo could be mistaken for radical adducts produced in vivo and excreted into the bile.

  5. Design of in situ sample rotation mechanism for angle-dependent study of cantilever-detected high-frequency ESR.

    PubMed

    Ohmichi, E; Hirano, S; Ohta, H

    2013-02-01

    Cantilever detected electron spin resonance (ESR) technique is combined with a precise rotation stage for angle-dependent ESR study of a tiny single crystalline sample on the order of 1 μg. Generally speaking, sample rotation in transmission-type ESR measurement is quite difficult. However, high angle resolution Δθ(min)∼0.2° and compact design of our stage allow in situ sample rotation in strong magnetic fields at low temperatures. As a result, a systematic study of ESR spectra for different field orientations can be easily obtained without sample extraction from a cryostat. As an example, angle-dependent ESR study of Co Tutton salt in the millimeter wave region is demonstrated at liquid helium temperature.

  6. ESR studies of surface adsorption and catalysis under ultra-high vacuum conditions. Progress report, March 1, 1980-February 29, 1981

    SciTech Connect

    Freed, J.H.

    1980-11-01

    This project is directed to developing ESR for the study of surface adsorption and catalysis on clean well-characterized metallic and oxide surfaces under ultra-high vacuum (UHV) conditions and to compare the results with real surfaces, which are important in actual catalysis. Results with ESR-UHV system on the NO/sub 2//Cu system showed that only in the presence of H/sub 2/O can the surface process(es) proceed that lead to stable Cu/sup 2 +/ complexes which are observable by ESR. By monitoring the CREMSEE (cyclotron-resonance from microwave-induced secondary electron emissions) threshold, definite evidence for the oxidation of the Cu surface by the clean NO/sub 2/ has been obtained. In real systems, as opposed to the clean surfaces prepared under UHV conditions, small amounts of H/sub 2/O are usually present. The UHV studies permitted a demonstration of the reactivity requirements. Detailed studies of the oxidation process of NO/sub 2/ on Cu have been performed. A newer ESR-UHV system with better expected performance has been built. An extensive study of motional dynamics of free radicals on supported surfaces has been completed. These include the O/sub 2//sup -/ radical absorbed on Ti supported on crushed vycor and NO/sub 2/ adsorbed on crushed vycor. The O/sub 2//sup -/ is found to exhibit planar rotation about an axis perpendicular to the internuclear axis of the O/sub 2//sup -/ and parallel to the normal to the plane. The higher temperature motion may be fit with a small activation energy of 0.5Kcal/mole, while the lower temperature motion shows anomalies. The NO/sub 2/ exhibits planar-rotation at the lower temperature, but above 77/sup 0/K it becomes more nearly isotropic presumably due to translational diffusion. Preliminary experiments imply that addition of acetylene increases the rate of rotational motion of the O/sub 2//sup -/. Preliminary studies leading to time-resolved UHV-ESR experiments of photo-induced catalysis have been performed with the new

  7. Frequency Extension to the THz Range in the High Pressure ESR System and Its Application to the Shastry-Sutherland Model Compound SrCu2(BO3)2.

    PubMed

    Ohta, Hitoshi; Sakurai, Takahiro; Matsui, Ryosuke; Kawasaki, Kohei; Hirao, Yuki; Okubo, Susumu; Matsubayashi, Kazuyuki; Uwatoko, Yoshiya; Kudo, Kazutaka; Koike, Yoji

    2015-10-29

    We have made a survey of ceramics for the inner parts of the transmission-type pressure cell to achieve the high pressure and the high transmission in the THz range. By using the optimal combination of ZrO2-based ceramic and Al2O3 ceramic, we have succeeded in obtaining a pressure up to 1.5 GPa and a frequency region up to 700 GHz simultaneously. We show the high-pressure ESR results of the Shastry-Sutherland compound SrCu2(BO3)2 as an application. We observed the direct ESR transition modes between the singlet ground state and the triplet excited states up to a pressure of 1.51 GPa successfully, and obtained the precise pressure dependence of the gap energy. The gap energy is directly proved to be suppressed by the pressure. Moreover, we found that the system approaches the quantum critical point with pressure by comparing the obtained data with the theory. This result also shows the usefulness of high-pressure ESR measurement in the THz region to study quantum spin systems.

  8. Synthesis and ESR studies of 2'-deoxyuridines tethered with alkynyl, rod-like linkages#

    PubMed Central

    Sniady, Adam; Sevilla, Michael D.; Meneni, Srinivasarao; Lis, Tadeusz; Szafert, Slawomir; Khanduri, Deepthi; Finke, John M.; Dembinski, Roman

    2015-01-01

    Sonogashira coupling of diacetyl 5-ethynyl-2'-deoxyuridine with diacetyl 5-iodo-2'-deoxyuridine gave the acylated ethynediyl-linked 2'-deoxyuridine dimer (3b) (63%) that was deprotected with ammonia/methanol to ethynediyl-linked 2'-deoxyuridines (3a) (79%). Reaction of 5-ethynyl-2'-deoxyuridine (1a) with 5-iodo-2'-deoxyuridine gave the furopyrimidine linked to 2'-deoxyuridine (78%). Catalytic oxidative coupling of 1a (O2, CuI, Pd/C, DMF) gave the butadiynediyl-linked 2'-deoxyuridines (4) (84%). Double Sonogashira coupling of 5-iodo-2'-deoxyuridine with 1,4-bis(ethynyl)benzene gave 1,4-phenylenediethyne-bridged 5-ethynyl-2'-deoxyuridines (5, 83%). Cu-catalyzed cycloisomerization of dimers 4 and 5 gave their furopyrimidine derivatives. One electron addition to 1a, 3a and 4 gave the anion radical whose ESR spectra showed the unpaired electron largely localized at C6 of one uracil ring (17 G doublet) at 77 K. For the ethynediyl- and butadiynyl-linked uridines 3a and 4 the ESR spectra of their one electron oxidized species at 77 K showed that the unpaired electron is delocalized over both rings. Thus structures 3a and 4 provide an efficient electronic link for hole conduction between the uracil rings. However, for the excess electron, an activation barrier prevents coupling to both rings. These dimeric structures could provide a gate that could separate hole transfer from electron transport between strands in DNA systems. In the crystal structure of acylated dimer 3b the bases were found in the anti position to each other across the ethynyl link. Similar anti conformation was preserved in the derived furopyrimidine–deoxyuridine dinucleoside. PMID:19609983

  9. 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.

  10. Pulse radiolysis studies of short-lived species in solid amino acids as precursors of radicals and detected by ESR

    NASA Astrophysics Data System (ADS)

    Zagórski, Z. P.; Gładysz, Katarzyna

    1995-06-01

    The aim of the study was to bring closer solid state radiation chemistry and ESR spectroscopy by looking for precursors of free radicals which give ESR signals. It has been performed using time-resolved spectrophotometry (pulse radiolysis of the solid state) and diffuse reflection spectrophotometry. Alanine has been especially considered as the most investigated amino acid, important for radiation dosimetry. Absorption of the transient (Λ maximum at 460 nm) is identified as the species during deamination. The stable absorption spectrum with the Λ maximum at 345 nm is due to the same radical as the one detected by ESR. Other amino acids: valine, threonine, glutamine and arginine show similar behaviour: microsecond spectrum of the intermediate appears always at longer wavelenghts. The transient spectrum changes into stable absorption in UV of a lower wavelenght. Along with the optical spectrum, the ESR spectrum appears, of similar stability. Also, other features indicate that the same radical is responsible for both the electronic and ESR spectrum. Some amino acids, like methionine give intensive transient absorption in the microsecond range but no ESR signal, after completion of consecutive fast reactions. In that case any optical absorption is due to the stable product of radiolysis, i.e. compounds with paired electrons only.

  11. Comparison study of tooth enamel ESR spectra of cows, goats and humans.

    PubMed

    Jiao, Ling; Liu, Zhong-Chao; Ding, Yan-Qiu; Ruan, Shu-Zhou; Wu, Quan; Fan, Sai-Jun; Zhang, Wen-Yi

    2014-11-01

    The ESR radiation dosimetric properties of tooth enamel samples from cows and goats were investigated and compared with those of human samples. Samples were prepared first mechanically, and then chemically. The study results showed that the native signals from cow and goat samples were weaker than those from human samples; the radiation sensitivities for cow and goat samples were very close to those of human tooth enamel samples. These results indicated that cow and goat teeth could be alternative materials for radiation dose estimation.

  12. ESR study of the thymine anion radical in a single crystal of thymine monohydrate.

    PubMed

    Kabiljo, Z; Sanković, K; Herak, J N

    1990-09-01

    ESR spectroscopy was used to study free radicals in an irradiated single crystal of thymine monohydrate at 77 K. At low microwave power (20 microW), a broad doublet is found to be super-imposed on the well known resonance patterns of the 5-yl and 7-yl radicals. The doublet spectrum has been analysed as a difference spectrum. Its spectroscopic properties and the observed transformation into the 5-yl, H-addition radical on warming the crystal are consistent with its anion nature, T(-).

  13. Interaction of antiaggregant molecule ajoene with membranes. An ESR and 1H, 2H, 31P-NMR study.

    PubMed

    Debouzy, J C; Neumann, J M; Hervé, M; Daveloose, D; Viret, J; Apitz-Castro, R

    1989-01-01

    The structure of ajoene, a molecule extracted from garlic, has been studied by 1H-NMR and its interaction with model membranes by 1H-, 2H-, 31-P-NMR and ESR experiments. This study clearly shows that the ajoene molecule is located deep in the layer and is close to the interlayer medium. Moreover while NMR experiments show that the membrane structure is only slightly affected by the presence of ajoene, ESR experiments reveal significant modifications in phospholipid dynamics. This interaction, observed before with the phenothiazine derivative, promazine, results in an increase of the membrane fluidity in its hydrophobic part and could be related to clinical properties of ajoene.

  14. Erythrocyte sedimentation rate (ESR) measured by the Streck ESR-Auto Plus is higher than with the Sediplast Westergren method: a validation study.

    PubMed

    Vennapusa, Bharathi; De La Cruz, Laura; Shah, Hemangini; Michalski, Veronica; Zhang, Qian-Yun

    2011-03-01

    The erythrocyte sedimentation rate (ESR) is a nonspecific indicator of disease activity and is often used by clinicians in assisting diagnosis and follow-up of many inflammatory disorders. The Westergren method is considered the standard method for measuring ESR. Recently, many automated instruments have become available to address laboratory safety and time efficiency. We validated the Streck ESR-Auto Plus instrument (Streck, Omaha, NE) using the Sediplast (Polymedco, Cortlandt Manor, NY) Westergren method as the reference method. Blood samples collected in 113 EDTA tubes were transferred into Sediplast vials and Streck high-altitude vacuum tubes for measuring the ESR. There was good correlation between the Sediplast and Streck methods (0.95) using Pearson correlation. The y-intercept was at 6.5 using linear regression, indicating systematic bias with a mean difference of 7.13 using the t test (P < .0001). We modified our reference ranges to rectify the systematic bias found during validation. PMID:21350092

  15. Effects of neutron flux on the nano silica particles: ESR study

    NASA Astrophysics Data System (ADS)

    Huseynov, Elchin; Garibov, Adil; Mehdiyeva, Ravan; Huseynova, Efsane

    2016-02-01

    In this paper, we have comparatively studied the “electron spin resonance” (ESR) of SiO2 nanoparticles before and after neutron irradiation. From the comparative analysis of samples at the full sweep (sweep 5000 G at center field of 3300 G) in the same system, amount of defects were found to increase. At the field line around 3350 G, we found the free electron g species (g = 2.002) and determined that this situation is more sustainable than the other observed cases (the cases existing in values 2.5-3 and 3-5 of g-factor). Moreover, expanded section near g = 2.002 repeated with a sweep of 100 G and at two power due to microwave saturation effects has been studied.

  16. Investigation of structural and dynamic features of the radicals produced in gamma irradiated sulfanilamide: an ESR study.

    PubMed

    Colak, S; Korkmaz, M

    2003-11-28

    Characteristic features of the radiolytical intermediates produced in gamma irradiated solid sulfanilamide (SA) were investigated in the present work using ESR spectroscopy. SO(2), which is the most sensitive group to radiation of SA molecule, was found to be at the origin of radiation produced ionic radical species. The latters give rise to an axially symmetric and an isotropic ESR spectra so that their sum appears as a three line antisymmetric ESR spectrum. Heights of these lines measured with respect to the base line were used to monitor microwave, temperature, time-dependent and kinetic features of the radical species contributing to ESR spectrum. Based on the experimental results derived from this study, it was concluded that as in the case of other solid sulfonamides radiation, yield of solid SA is very low (G=0.5) compared with those obtained for sulfonamide aqueous solutions (G=3.5-5.1), so that SA and SA-containing drugs could be safely sterilized by radiation.

  17. Free radicals and SOD activity of jaw cyst. Direct measurement and spin trapping studies by ESR.

    PubMed

    Kimura, H; Simodate, H; Suzuki, M

    1990-01-01

    Free radicals produced in the fluid of jaw cysts were directly measured at room temperature using ESR. With these samples, SOD activity of the cyst fluid was measured by the ESR spin trapping method with DMPO as a trapping agent. Freeze-dried samples of cyst fluid showed a broad ESR signal at g = 2.005. Relative signal intensity of samples from jaw cysts with inflammation was higher than jaw cysts without inflammation. SOD activity of cyst fluid with high viscosity showed higher values than that of cyst fluid with low viscosity. We suggest that free radicals produced in jaw cyst damage tissues while higher SOD activity of cyst fluid play a role in a self-defense mechanism against free radicals.

  18. ESR dosimetry study of population in the vicinity of the Semipalatinsk Nuclear Test Site.

    PubMed

    Zhumadilov, Kassym; Ivannikov, Alexander; Stepanenko, Valeriy; Zharlyganova, Dinara; Toyoda, Shin; Zhumadilov, Zhaxybay; Hoshi, Masaharu

    2013-07-01

    A tooth enamel electron spin resonance (ESR) dosimetry study was carried out with the purpose of obtaining the individual absorbed radiation doses of population from settlements in the Semipalatinsk region of Kazakhstan, which was exposed to radioactive fallout traces from nuclear explosions in the Semipalatinsk Nuclear Test Site and Lop Nor test base, China. Most of the settlements are located near the central axis of radioactive fallout trace from the most contaminating surface nuclear test, which was conducted on 29 August 1949, with the maximum detected excess dose being 430 ± 93 mGy. A maximum dose of 268 ± 79 mGy was determined from the settlements located close to radioactive fallout trace resulting from surface nuclear tests on 24 August 1956 (Ust-Kamenogorsk, Znamenka, Shemonaikha, Glubokoe, Tavriya and Gagarino). An accidental dose of 56 ± 42 mGy was found in Kurchatov city residents located close to fallout trace after the nuclear test on 7 August 1962. This method was applied to human tooth enamel to obtain individual absorbed doses of residents of the Makanchi, Urdzhar and Taskesken settlements located near the Kazakhstan-Chinese border due to the influence of nuclear tests (1964-1981) at Lop Nor. The highest dose was 123 ± 32 mGy.

  19. Radicals Formed in N-Acetyl-Proline by Electron Attachment: ESR Spectroscopy and Computational Studies

    PubMed Central

    Kheir, Jeanette F.; Chomicz, Lidia; Rak, Janusz; Bowen, Kit H.; Sevilla, Michael D.

    2011-01-01

    In this study, the reactions of electrons with N-acetyl-proline are investigated by electron spin resonance (ESR) spectroscopy and DFT theory. Electrons are produced by gamma irradiation or by photo-ionization of K4Fe(CN)6 in a neutral 7.5 M LiCl-D2O aqueous glasses at low temperatures with identical results. Electrons are found to add to both the peptide bond and the carboxyl group of the acetyl-proline moiety at 77K. On annealing both the electron adducts undergo fragmentation of the peptide bond between the nitrogen and the alpha carbon of the peptide structure. However the peptide bond electron adduct radical reacts much more rapidly than the carboxyl group electron adduct radical. The DFT calculations predict that the carboxyl adduct is substantially more stable than the peptide bond adduct, with the activation barrier to N-Cα cleavage 3.7 kcal/mol for the amide electron adducts and 23 kcal/mol for the carboxyl adducts in agreement with the relative reactivity found by experiment. PMID:22044351

  20. Radicals with one-electron silver-carbon bonds formed by ionizing radiation: An ESR study

    NASA Astrophysics Data System (ADS)

    Symons, Martyn C. R.; Janes, Robert; Stevens, Andrew D.

    1989-08-01

    The radicals Ag·CH 2OH + and Ag·CHMeOH + have been prepared by low-temperature radiolysis of solutions of silver perchlorate in methanol and ethanol respectively, and characterised by ESR spectroscopy. These centres are thought to be produced by the reaction of matrix-derived radicals with silver ions. Interpretation of their ESR spectra was facilitated by using 13C- and 2H-labelled alcohols. The magnitudes of the hyperfine coupling constants give estimated spin densities of ⩾ 0.17 on silver and ≈ 0.5 on carbon.

  1. ESR and mass-spectrometric uranium-series dating studies of a mammoth tooth from stanton harcourt, Oxfordshire, England

    NASA Astrophysics Data System (ADS)

    Zhou, L. P.; McDermott, F.; Rhodes, E. J.; Marseglia, E. A.; Mellars, P. A.

    The age of the Channel Deposits at Stanton Harcourt, Oxfordshire, England, has been a topic of debate with important implications for British Pleistocene stratigraphy. Recent excavations led by K. Scott reveal ample evidence for ancient environmental conditions characteristic of an interglacial. However, the question remains on the assignment of its age. At present it is thought to represent an interglacial corresponding to either marine OI Stage 7 or 5e. In an attempt to constrain the chronology of the site, and to assess the techniques' reliability, we have made electron spin resonance (ESR) measurements on enamel and mass-spectrometric U-series measurements on both enamel and dentine from a mammoth tooth buried in the Channel Deposits at Stanton Harcourt. Four dentine samples gave U-series dates between 65.4±0.4 and 146.5±1.0 ka and two enamel samples between these dentine layers were dated to 53.3±0.2 and 61.1±0.6 ka. The corresponding ESR age estimates for the enamel samples are 59±6 and 62±4 ka (early U-uptake, EU) and 95±11 and 98±7 ka (linear U-uptake, LU). The recent U-uptake (RU) dates are 245±38 and 238±31 ka, but in light of the U-series data we would not expect these to represent realistic age estimates. Similar ESR results were obtained from two other adjacent enamel samples. The effect of the large size of the mammoth tooth on the external gamma dose, and the internal gamma contribution from the high U content of the dentine, are considered. While the recent uptake ESR dates appear to coincide with OI Stage 7, all the early and linear uptake ESR and mass-spectrometric U-series dates are younger than the expected age estimation based on recent geological interpretation and amino acid racemisation measurements (>200 ka) and optical dating studies (200-450 ka). Possible causes of the unexpected dating results are discussed. We conclude that our mass-spectrometric U-series and EU and LU ESR measurements represent minimum age estimates for the

  2. Study on ESR and inter-related properties of vacuum-dehydrated nanotubed titanic acid

    NASA Astrophysics Data System (ADS)

    Zhang, Shunli; Li, Wei; Jin, Zhensheng; Yang, Jianjun; Zhang, Jingwei; Du, Zuliang; Zhang, Zhijun

    2004-04-01

    Nanotubed titanic acid (H 2Ti 2O 4(OH) 2) is a novel kind of material. The electron spin resonance (ESR) and inter-related properties of its vacuum-dehydrated product were investigated by means of transmission electron microscopic, X-ray diffraction, ESR, diffuse reflectance spectra. The results showed that after treatment under vacuum (-0.1 MPa) at 100°C, single-electron-trapped oxygen vacancies (SETOV), characterized by a symmetrical ESR signal ( g=2.003), were generated in nanotubed H 2Ti 2O 4(OH) 2 crystal lattice. The g=2.003 ESR signal intensity ( IESR) increased with treatment time. SETOV played the role of F centers, the visible-light absorption power of vacuum-dehydrated H 2Ti 2O 4(OH) 2 was proportional to IESR. During vacuum dehydration at 100°C, the H 2Ti 2O 4(OH) 2 nanotubes shortened but its crystalline form kept unchanged. The formation mechanism of SETOV was discussed.

  3. Charge carrier behavior in UV irradiated fullerene nano whiskers based on studies of electrical conduction and ESR

    NASA Astrophysics Data System (ADS)

    Doi, Tatsuya; Koyama, Kyouhei; Bird, Jonathan P.; Aoki, Nobuyuki; Ochiai, Yuichi

    2011-12-01

    The UV light irradiation to C60 fullerene induces [2+2] cyclo-additional reaction, and creates inter-molecule bonds between C60 molecules. That reaction makes fullerene polymer from molecules. A fine crystalline wire structure consisting of C60 molecules is called a fullerene nano whisker (FNW), and also is used to fabricate n-type field effect transistors (FET) as the channel. The UV irradiation to the FNW-FET for polymerization must achieve the FET operation in ambient atmosphere. Here, a drastic changing of FET parameters has been observed. In the ESR measurement in ambient atmosphere, we have studied on temperature dependence of peak-to-peak width (ΔHPP) and ESR magnetic susceptibility ratio. The comparison, the temperature dependence of pristine FNW and UV irradiated FNW, clearly indicates that there exists a clearer difference in electronic state between pristine FNW and UV polymerized FNW.

  4. Permeability studies of redox-sensitive nitroxyl spin probes in corn oil using an L-band ESR spectrometer

    NASA Astrophysics Data System (ADS)

    Jebaraj, D. David; Utsumi, Hideo; Asath, R. Mohamed; Benial, A. Milton Franklin

    2016-05-01

    Electron spin resonance (ESR) studies were carried out for 2mM 14N labeled 2H enriched 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) and 3-carboxy-2,2,5,5,-tetramethyl-1-pyrrolidinyloxy (carboxy-PROXYL) in pure water and various concentrations of corn oil. The ESR parameters, such as the line width, hyperfine coupling constant, g-factor, rotational correlation time, partition parameter and permeability were reported for the samples. The line width broadening was observed for both nitroxyl radicals in corn oil solutions. The partition parameter for permeable MC-PROXYL in corn oil increases with increasing concentration of corn oil, which reveals that the nitroxyl spin probe permeates into the oil phase. From the results, the corn oil concentration was optimized as 50 % for phantom studies. The rotational correlation time also increases with increasing concentration of corn oil. The permeable and impermeable nature of nitroxyl spin probes was demonstrated. These results will be useful for the development of ESR/OMR imaging modalities in in vivo and in vitro studies.

  5. Spin-probe ESR study on the entrapment of organic solutes by the nanochannel of MCM-41 in benzene.

    PubMed

    Okazaki, Masaharu; Anandan, Sambandam; Seelan, Sindhu; Nishida, Masakazu; Toriyama, Kazumi

    2007-01-30

    An ESR study has been made on the adsorption of three types of aminoxyl radicals with different substituent groups in the nanochannel of MCM-41 in benzene. In the suspensions of MCM-41, all the aminoxyl radicals, usually called as spin probes, show the ESR spectra composed of two signals: the main broader one from the spin probes trapped in the nanochannel, and a sharp minor signal from those in the bulk. The spin probes adsorbed in the nanochannel retain considerable mobility especially at higher temperatures over 300 K. When fumed silica, having a surface structure similar to that of MCM-41, is employed, on the other hand, the relatively hydrophobic spin probe mainly remains in the bulk, but the hydrophilic one is mostly adsorbed and immobilized rigidly. From these results, the adsorption by the MCM-41 nanochannel in benzene is characterized by medium selectivity and considerable motional allowance to the adsorbate molecule. The mobility of the spin probe in the MCM-41 nanochannel increases and the adsorption efficiency decreases by either of the following changes made to the system: (a) increasing the channel diameter, (b) increasing the hydrophobicity of the spin probe, (c) adding a small amount of 2-propanol in the solution, (d) methylation of the surface OH groups of the nanochannel, and (e) elevating the system temperature. A model of this special type of adsorption has been proposed on the basis of the thermodynamic parameters and the ESR spectra for the modified systems including those with different solvents.

  6. Radiation damage of DNA constituents: ESR study of the adenosine:5-iodouracil cocrystal

    SciTech Connect

    Zamorano, R.

    1986-01-01

    Single cocrystals of adenosine:5-iodouracil and partially deuterated adenosine:5-iodouracil were irradiated at 4.2K, 77K, and 300K with x-rays from a 3Mev Van de Graaff electron accelerator. Several types of free radicals were produced by the radiation and were studied by X-Band and Q-Band ESR from 77K to 300K. Six radicals were identified. Two electron addition products (radicals I1 and As1) and one electron abstraction product (radical 12) are stabilized at 77K. At room temperature two hydrogen addition radicals (I3 and As2) and a singlet radical (As3) are stabilized. Upon annealing to 165K after low temperature irradiation, radicals I1 and I2 decay to nonparamagnetic species. Radical As1 remains stable from 77K to 240K. From 240K to 300K the As1 radical decays and radicals As2 and I3 gradually grow in. Irradiation and observation at room temperature produces predominantly a singlet radical (As3). The electron addition radical, I1, is a sigma*-type radical that presents the unpaired electron spin density localized mainly on the iodine atom. This radical does not de-halogenate, to produce the reactive uracilyl radical, but instead it decays into a non paramagnetic species when annealed from 77K to 300K. The low temperature radical population obtained in this cocrystal and the subsequent radical reactions upon annealing, contradict the hypothesis that, in the presence of purine:pyrimidine stacking interactions, electrons are transferred to the pyrimidines while holes are transferred to the purines.

  7. ESR study of molecular orientation and dynamics of TEMPO derivatives in CLPOT 1D nanochannels.

    PubMed

    Kobayashi, Hirokazu; Furuhashi, Yuta; Nakagawa, Haruka; Asaji, Tetsuo

    2016-08-01

    The molecular orientations and dynamics of 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) radical derivatives with large substituent groups at the 4-position (4-X-TEMPO) in the organic one-dimensional nanochannels within the nanosized molecular template 2,4,6-tris(4-chlorophenoxy)-1,3,5-triazine (CLPOT) were examined using ESR. The concentrations of guest radicals, including 4-methoxy-TEMPO (MeO-TEMPO) or 4-oxo-TEMPO (TEMPONE), in the CLPOT nanochannels in each inclusion compound (IC) were reduced by co-including 4-substituted-2,2,6,6-tetramethylpiperidine (4-R-TEMP) compounds at a ratio of 1 : 30-1 : 600. At higher temperatures, the guest radicals in each IC underwent anisotropic rotational diffusion in the CLPOT nanochannels. The rotational diffusion activation energy, Ea , associated with MeO-TEMPO or TEMPONE in the CLPOT nanochannels (6-7 kJ mol(-1) ), was independent of the size and type of substituent group and was similar to the Ea values obtained for TEMPO and 4- hydroxy-TEMPO (TEMPOL) in our previous study. However, in the case in which TEMP was used as a guest compound for dilution (spacer), the tilt of the rotational axis to the principal axis system of the g-tensor, and the rotational diffusion correlation time, τR , of each guest radical in the CLPOT nanochannels were different from the case with other 4-R-TEMP. These results indicate the possibility of controlling molecular orientation and dynamics of guest radicals in CLPOT ICs through the appropriate choice of spacer. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Quantification of Randomly-methylated-{beta}-cyclodextrin effect on liposome: An ESR study

    SciTech Connect

    Grammenos, A.; Bahri, M.A.; Guelluy, P.H.; Piel, G.; Hoebeke, M.

    2009-12-04

    In the present work, the effect of Randomly-methylated-{beta}-cyclodextrin (Rameb) on the microviscosity of dimyristoyl-L-{alpha} phosphatidylcholine (DMPC) bilayer was investigated using the electron spin resonance (ESR) technique. The ability of Rameb to extract membrane cholesterol was demonstrated. For the first time, the percentage of cholesterol extracted by Rameb from cholesterol doped DMPC bilayer was monitored and quantified throughout a wide Rameb concentration range. The effect of cholesterol on the inner part of the membrane was also investigated using 16-doxyl stearic acid spin label (16-DSA). 16-DSA seems to explore two different membrane domains and report their respective microviscosities. ESR experiments also establish that the presence of 30% of cholesterol in DMPC liposomes suppresses the jump in membrane fluidity at lipids phase-transition temperature (23.9 {sup o}C).

  9. Electrical Conductivity and ESR Studies in Iodine-Doped Polythiophene from Semiconductor to Metallic Regime

    NASA Astrophysics Data System (ADS)

    Hayashi, Shigenori; Kaneto, Keiichi; Yoshino, Katsumi; Matsushita, Rokuji; Matsuyama, Tomochika

    1986-06-01

    Dependences of electrical conductivity and ESR of iodine-doped polythiophene films, (C4H2SIy)x, on iodine concentrations which are precisely determined by a neutron activation technique (from a dilute level of y˜4× 10-4 to a deep level of y˜4× 10-1) are reported. A drastic increase of conductivity from 10-8 to 10-2 S/cm is observed at the fairly narrow dopant concentration region of 2× 10-3ESR signal also changes significantly, showing a maximum spin density and a minimum linewidth. These results are discussed to understand the semiconductor-to-metal transition in iodine-doped polythiophene, taking polaron and bipolaron models into account.

  10. ESR studies of the slow tumbling of vanadyl spin probes in nematic liquid crystals

    NASA Technical Reports Server (NTRS)

    Eastman, M. P.; Bruno, G. V.; Lawson, J. O.

    1977-01-01

    ESR line shapes that are appropriate for slowly tumbling vanadyl spin probes in viscous nematic liquid crystals were calculated by the stochastic Liouville method. Because of the symmetry possessed by vanadyl, the analysis and interpretation of these line shapes was simplified considerably. Spectral line shapes agreed well with experimental spectra of VOAcAc in the nematic liquid crystal Phase V and BEPC. Deviations from Brownian rotational diffusion were noted. A slowly fluctuating torque analysis yielded good agreement with the experimental spectra.

  11. Study of one-dimensional electron hopping and its effects on ESR line shape

    SciTech Connect

    Tang, Jau; Dikshit, S.N.; Norris, J.R. |

    1997-08-01

    Random hopping processes between discrete sites along a finite open chain or around a closed finite loop are examined. Closed form formulae are prescribed for the dependence of the ESR (electron spin resonance) line shape on the chain length and hopping rate. Significant differences between the closed loop and open chain are demonstrated. Deviation at short time from the results of diffusion in a continuum is presented.

  12. Positron annihilation and ESR study of irradiation-induced defects in silica glass

    NASA Astrophysics Data System (ADS)

    Hasegawa, M.; Tabata, M.; Fujinami, M.; Ito, Y.; Sunaga, H.; Okada, S.; Yamaguchi, S.

    1996-08-01

    The angular correlation of positron annihilation radiation (ACAR), positron lifetime and electron spin resonance (ESR) have been measured on fused and synthetic silica glass samples before and after irradiation with fast neutrons up to a dose of 8.6 × 10 18 n/cm 2 at about 150°C or with 3 MeV electrons up to a dose of 1 × 10 18 e/cm 2 below 50°C. The ACAR curves are deconvoluted into two Gaussian components: a narrow and a broad component. The narrow component is due to self-annihilation of ortho-state of positronium (p-Ps) formed in "intrinsic" structural voids with radius of about 0.3 nm, while the broad component comes from pick-off annihilation of ortho-Ps and annihilation of positrons with valence electrons presumably associated with oxygen. Detailed post-irradiation experiments reveal that two kinds of positron trapping centers (defects) are introduced. Both kinds of the defects give almost the same broad component and markedly suppress Ps formation. This suggests that they are oxygen related centers. The first type defects with the positron lifetime of about 0.25 ns anneal out at 400-500°C, while the second type defects with lifetime of 0.47 ns recover after annealing at about 600°C. Electron spin resonance (ESR) measurements were also made on the same samples to detect irradiation-induced paramagnetic center (defects): E' centers, peroxyradicals (POR) and non-bridging oxygen hole centers (NBOHC). The correspondence between the positron trapping centers and the ESR-active paramagnetic centers is not straightforward, partly because positrons can be trapped not only at the paramagnetic defects but also at diamagnetic defects. However, possible relations between these positron trapping centers and the paramagnetic defects are discussed.

  13. ESR study of stable radicals in an irradiated single crystal of deoxyguanosine 5'-phosphate (Na salt)

    SciTech Connect

    Rakvin, B.; Herak, J.N.

    1981-11-01

    Three different radical species have been identified in an irradiated single crystal of deoxyguanosine 5'-phosphate at room temperature. The dominating species is a hydrogen-addition radical with spectroscopic characteristics similar to those of the N(7)-protonated H-addition radical in guanine/sup ./HCl. The well-resolved quartet ESR pattern is believed to belong to a radical in the sugar moiety formed by breakage of the furanose ring in the same manner as that reported earlier for deoxycytidine 5'-phosphate. The third species present is either a protonated anion or a deprotonated cation located in this six-member ring of the guanine base.

  14. ESR kinetics study of the decay of low-temperature radicals in glycine and. beta. -alanine

    SciTech Connect

    Smith, C.J.; Poole, C.P. Jr.; Farach, H.A.

    1981-01-15

    Monocrystals of glycine and ..beta..-alanine have been observed by electron spin resonance (ESR) after x-irradiation near 77 /sup 0/K. The rate constants of the decay of one signal in each have been determined over the ranges 127 /sup 0/--148 /sup 0/K and 98 /sup 0/--188 /sup 0/K, respectively. Both obey first-order kinetics with activation energies of approx.7.0 and approx.2.6 kcal/mole, respectively, and pre-exponential factors of 6.4 x 10/sup 8/ and 15 Hz, respectively.

  15. ESR Study of Interfacial Hydration Layers of Polypeptides in Water-Filled Nanochannels and in Vitrified Bulk Solvents

    PubMed Central

    Lai, Yei-Chen; Chen, Yi-Fan; Chiang, Yun-Wei

    2013-01-01

    There is considerable evidence for the essential role of surface water in protein function and structure. However, it is unclear to what extent the hydration water and protein are coupled and interact with each other. Here, we show by ESR experiments (cw, DEER, ESEEM, and ESE techniques) with spin-labeling and nanoconfinement techniques that the vitrified hydration layers can be evidently recognized in the ESR spectra, providing nanoscale understanding for the biological interfacial water. Two peptides of different secondary structures and lengths are studied in vitrified bulk solvents and in water-filled nanochannels of different pore diameter (6.1∼7.6 nm). The existence of surface hydration and bulk shells are demonstrated. Water in the immediate vicinity of the nitroxide label (within the van der Waals contacts, ∼0.35 nm) at the water-peptide interface is verified to be non-crystalline at 50 K, and the water accessibility changes little with the nanochannel dimension. Nevertheless, this water accessibility for the nanochannel cases is only half the value for the bulk solvent, even though the peptide structures remain largely the same as those immersed in the bulk solvents. On the other hand, the hydration density in the range of ∼2 nm from the nitroxide spin increases substantially with decreasing pore size, as the density for the largest pore size (7.6 nm) is comparable to that for the bulk solvent. The results demonstrate that while the peptides are confined but structurally unaltered in the nanochannels, their surrounding water exhibits density heterogeneity along the peptide surface normal. The causes and implications, especially those involving the interactions between the first hydration water and peptides, of these observations are discussed. Spin-label ESR techniques are proven useful for studying the structure and influences of interfacial hydration. PMID:23840841

  16. Photochemical synthesis of simple organic free radicals on simulated planetary surfaces - An ESR study

    NASA Technical Reports Server (NTRS)

    Tseng, S.-S.; Chang, S.

    1975-01-01

    Electron spin resonance (ESR) spectroscopy provided evidence for formation of hydroxyl radicals during ultraviolet photolysis (254 nm) at -170 C of H2O adsorbed on silica gel or of silica gel alone. The carboxyl radical was observed when CO or CO2 or a mixture of CO and CO2 adsorbed on silica gel at -170 C was irradiated. The ESR signals of these radicals slowly disappeared when the irradiated samples were warmed to room temperature. However, reirradiation of CO or CO2, or the mixture CO and CO2 on silica gel at room temperature then produced a new species, the carbon dioxide anion radical, which slowly decayed and was identical with that produced by direct photolysis of formic acid adsorbed on silica gel. The primary photochemical process may involve formation of hydrogen and hydroxyl radicals. Subsequent reactions of these radicals with adsorbed CO or CO2 or both yield carboxyl radicals, CO2H, the precursors of formic acid. These results confirm the formation of formic acid under simulated Martian conditions and provide a mechanistic basis for gauging the potential importance of gas-solid photochemistry for chemical evolution on other extraterrestrial bodies, on the primitive earth, and on dust grains in the interstellar medium.

  17. ESR dosimetry using inorganic materials: a case study of Li2CO3 and CaSO4:Dy as prospective dosimeters.

    PubMed

    Murali, S; Natarajan, V; Venkataramani, R; Pushparaja; Sastry, M D

    2001-08-01

    The CO2- radical ion, detected by ESR technique in bones and teeth enamel, was proved to be invaluable in high level and retrospective dosimetry. In these matrices, impurity carbonate (at phosphate sites) was the precursor to CO2-. With a view to investigate the possibility of using inorganic materials such as lithium carbonate as ESR dosimeters, studies were carried out on gamma-irradiated Li2CO3. The intensity of radiation-induced ESR signals of Li2CO3 at g = 2.0036 (CO3-) and g = 2.0006 (CO2-) was followed as a function of gamma dose in the low dose range of 1-1350 Gy. It was observed that the intensity of the ESR signal at g = 2.0036 (CO3-) was in a linear relation with the radiation dose in the dose range 10-800 Gy and the signal at g = 2.0006 (CO2-) showed linear response in the dose range 5-800 Gy. The lowest dose that could be detected in the present studies using the signal of CO2- in Li2CO3 powder samples (approximately 50 mg) is 3.2 Gy. ESR studies were also carried out on the widely used TL dosimetric material CaSO4:Dy and in pure CaSO4 after gamma irradiation. The TL materials were used in powder as well as pellet forms. The linearity of ESR response with dose for powder and pellet forms of CaSO4: Dy was also studied using the signals at g = 2.0030 (SO3-) and at g = 2.0139 (SO4-). It was observed that the range of linearity of dose response extended between 20 and 1200 Gy, for SO3- signals. The results of dosimetric study indicate that the ESR-Li2CO3 system could be used in dosimetric applications in radiotherapy. However, for the actual applications further advancement is needed to lower the detection limit. The TL phosphor, CaSO4:Dy in powder and pellet forms, could be used as ESR dosimeter in the dose range 20-600 Gy.

  18. Vitamin E analogue Trolox C. E.s.r. and pulse-radiolysis studies of free-radical reactions.

    PubMed Central

    Davies, M J; Forni, L G; Willson, R L

    1988-01-01

    The reactions between Trolox C, a water-soluble vitamin E analogue, and several oxidizing free radicals including the hydroxyl radical and various peroxy radicals were examined by using the pulse-radiolysis technique. The results demonstrate that Trolox C may undergo rapid one-electron-transfer reactions as well as hydrogen-transfer processes; the resulting phenoxyl radical is shown to be relatively stable, in common with the phenoxyl radical derived from vitamin E. The reactions between the Trolox C phenoxyl radical and a variety of biologically relevant reducing compounds were examined by using both pulse radiolysis and e.s.r. The results demonstrate that the Trolox C phenoxyl radical is readily repaired by ascorbate (k = 8.3 x 10(6) dm3.mol-1.s-1) and certain thiols (k less than 10(5) dm3.mol-1.s-1) but not by urate, NADH or propyl gallate. Evidence from e.s.r. studies indicates that thiol-containing compounds may also enter into similar repair reactions with the alpha-tocopherol phenoxyl radical. Kinetic evidence is presented that suggests that Trolox C may 'repair' proteins that have been oxidized by free radicals. PMID:2849418

  19. Spin concentration in a possible ESR dosimeter: An electron spin echo study on X-irradiated ammonium tartrate.

    PubMed

    Brustolon, M; Zoleo, A; Lund, A

    1999-04-01

    Several single crystals and powder samples of ammonium tartrate, recently proposed as a possible ESR dosimeter, have been X-irradiated with different doses. The total radical concentration has been determined by quantitative cw ESR, by comparison with a standard. The samples have been studied by electron spin echo spectroscopy. The two-pulse echo decay has been obtained and simulated by a single exponential function for different values of the microwave power of the pulses and for different pulse lengths. The dependence of the phase memory time TM on the microwave power has been exploited to get information on the contribution of the instantaneous diffusion to spin dephasing. At room temperature in the range of radical concentrations of 10(18)-10(19) spins/cm3 the instantaneous diffusion is the dominant spin dephasing mechanism. The linear dependence of the instantaneous diffusion on the total concentration of the radicals is in agreement with the theory. From the latter result we conclude that the average radical-radical distance corresponds to a random distribution of the radicals in the matrix. A simple method of measuring the radical concentration by the ESE decays in powder samples of irradiated ammonium tartrate is described.

  20. Studies of osmoregulation in salt adaptation of cyanobacteria with ESR spin-probe techniques

    PubMed Central

    Blumwald, Eduardo; Mehlhorn, Rolf J.; Packer, Lester

    1983-01-01

    Sucrose is accumulated in response to NaCl-induced stress in the cyanobacterium Synechococcus 6311. Internal cell volume was measured by ESR spectra with 2,2,6,6-tetramethyl-4-oxopiperidinoxy free radical (TEMPONE) as a spin probe in order to calculate sucrose concentrations inside the cell. This method is rapid and reliable and provides an unambiguous measurement of absolute volumes in different osmotic environments. Because the osmolar concentration of sucrose does not counter-balance the osmolar concentrations of ions in the growth medium, we suggest that sucrose accumulation is one of the mechanisms involved in the process of adaptation to salt of Synechococcus 6311. The accumulation of sucrose in non-N2-fixing cyanobacteria such as Synechococcus 6311 and in N2-fixing cyanobacteria such as Nostoc muscorum suggests a common mechanism of osmoregulation of fresh water cyanobacteria in response to increasing NaCl concentrations in the growth medium. Images PMID:16593309

  1. An ESR and NMR study of the radiolysis of n-alkanes: Crystal structure dependence

    NASA Astrophysics Data System (ADS)

    Toriyama, K.; Okazaki, M.; Nunome, K.; Matsuura, K.

    The process of radiation damage for long-chain n-alkanes was investigated to elucidate that for polyethylene. Chain-end alkyl radicals were preferentially formed not only through primary C-H scission but also through a hydrogen atom reaction in odd- n-alkane, as was shown by analysis of the ESR spectra for isotopic mixtures of tridecane- h28/tridecane- d28 and nonadecane- h40/nonadecane- d40. To elucidate the mode of alkyl radical migration in solids through intermolecular hydrogen atom abstraction, D/H exchange was detected in mixed crystals of eicosane- d42/eicosane- h42. The chain-end region was found to be more reactive than the inner region for radical site migration. In addition, formation of a microscopic amorphous island by destruction of the crystal lattice was also detected. The influences of molecular packing were large in all cases.

  2. Preliminary study of FMO1, FMO5, CYP21, ESR1, PLIN2 and SULT2A1 as candidate gene for compounds related to boar taint.

    PubMed

    Neuhoff, Christiane; Gunawan, Asep; Farooq, Malik Omar; Cinar, Mehmet Ulas; Große-Brinkhaus, Christine; Sahadevan, Sudeep; Frieden, Luc; Tesfaye, Dawit; Tholen, Ernst; Looft, Christian; Schellander, Karl; Uddin, Muhammad Jasim

    2015-10-01

    An association study between polymorphisms of six genes and boar taint related compounds androstenone, skatole and indole was performed in a boar population (n=370). Significant association (P<0.05) was detected for SNP of FMO5 (g.494A>G) with all boar taint compounds, SNP of CYP21 (g.3911T>C) with skatole and indole, and SNP of ESR1 (g.672C>T) with androstenone and indole. mRNA expression of CYP21 and ESR1 was higher in CAB (castrated boar) compared to non-castrated boars; whereas, the expression of FMO5 and ESR1 was higher in LBT (low boar taint) compared to HBT (high boar taint) in liver tissue. FMO5, CYP21 and ESR1 proteins were less detectable in HBT compared with LBT and CAB in liver tissues. These findings suggest that FMO5, CYP21 and ESR1 gene variants might have effects on the boar taint compounds. PMID:26047979

  3. Developments of Multi-extreme High Field ESR in Kobe

    NASA Astrophysics Data System (ADS)

    Ohta, H.; Okubo, S.; Ohmichi, E.; Sakurai, T.; Zhang, W.-M.; Shimokawa, T.

    2013-03-01

    Recent developments of "multi-extreme" high magnetic field electron spin resonance (ESR) in Kobe will be reviewed. Our high magnetic field ESR covers the frequency region between 0.03 and 7 THz and the temperature region between 1.8 and 300 K. With this high magnetic field ESR system we can apply the magnetic field up to 55 T using a Cu-Ag pulsed magnet and a 300 kJ (10 kV) capacitor bank. Under this high magnetic field we can also apply the high pressure up to 1.4 GPa. As we can make the measurement under low temperature, high magnetic field and high pressure simultaneously, we name it as "multi-extreme" ESR. Moreover, in order to gain the sensitivity of our high magnetic field ESR, we have developed a micro-cantilever ESR system using a torque method, which enables the ESR measurement of micrometer size single crystal at low temperature. At the moment we are in the process of extending the magnetic field region of micro-cantilever ESR. Recently we have succeeded in making the measurement up to 369 GHz and the achieved sensitivity is about 1010 spins/G, which is much higher than that using the conventional transmission method. Finally our development of magnetization detected ESR using SQUID magnetometer (SQUID ESR) will be also presented.

  4. An ESR study of the gamma radiolysis of aromatic polyesters containing isomeric naphthalene links

    NASA Astrophysics Data System (ADS)

    Hill, David J. T.; Choi, Bong-Ku; Ahn, Hung-Kun; Choi, E.-Joon

    2001-07-01

    Six polyesters were synthesised from 4,4'-oxy-bis(benzoyl chloride) and 1,4-, 1,5-, 1,6-, 2,3-, 2,6-, and 2,7-naphthalenediol isomers. The structures of the polyesters were characterised by means of IR, inherent viscosities in tetrachloroethane (TCE), solutions at 303 K and thermal analysis. The glass transition temperatures were in the range of 425-494 K by DSC thermal analysis. All of the polyesters were irradiated in an AECL Gammacell 220 unit at a dose rate of approximately 6.7 kGy/h to doses in the range of 0-15 kGy at 77 and 300 K. ESR spectroscopy was used to examine the radicals formed during radiolysis and to measure their yields. The G-values for radical formation in the polyesters were found to be in the range 0.18-1.41 at 77 K and 0.19-0.78 at 300 K. At 77 K, up to 15% of the radicals formed on radiolysis were found to be photo-bleachable anion radicals. Annealing experiments were carried out in order to identify the neutral radicals, which were assigned to naphthyl- or phenyl- and phenoxyl-type radicals.

  5. ESR, optical absorption, and luminescence studies of the peroxy-radical defect in topaz

    SciTech Connect

    Priest, V.; Cowan, D.L. ); Yasar, H.; Ross, F.K. , University of Missouri-Columbia, Columbia, Missouri )

    1991-11-01

    Fast-neutron irradiation of natural topaz crystals produces a single paramagnetic radiation damage center in high concentration. ESR of this center shows a holelike spectrum with {ital S}=1/2 and a strongly anisotropic {ital g} tensor: {ital g}{sub {ital x}{ital x}}=2.0027, {ital g}{sub {ital y}{ital y}}=2.0055, and {ital g}{sub {ital z}{ital z}}=2.0407. We identify this defect as an intrinsic O{sub 2}{sup {minus}} center in the form of a peroxy radical. The orientation of the {ital g} tensor helps confirm this assignment, as does the extraordinary thermal stability; annealing temperatures near 800 {degree}C are required for complete removal. Two uv absorption bands are associated with the peroxy radical, each with oscillator strength near 0.09. Pumping in the higher energy band leads to a polarization-sensitive 2.5-eV luminescence; the other uv band apparently relaxes nonradiatively.

  6. Enzyme activity and structural dynamics linked to micelle formation: a fluorescence anisotropy and ESR study.

    PubMed

    Chin, Michael; Somasundaran, Ponisseril

    2014-01-01

    Activities of the enzymes, protease subtilisin and horse radish peroxidase (HRP) have been increased 50 and 40%, respectively, in the presence of the nonionic surfactant, alkyl polyglucoside, compared with the activities in buffer alone. This enzyme hyperactivity reaches a peak at 3.0 mm of surfactant. Investigation into the structure of surfactant aggregates indicates "giant" micelle superstructures at this range of surfactant concentration of 1.7 μm in diameter--dramatically decreasing to 60 and 70 nm at higher surfactant concentrations, while surface tension measurements indicate two critical micelle concentration inflection points at 0.2 and 5.0 mm, which suggests transitions in micelle structure with respect to concentration. Furthermore, electron spin resonance (ESR) indicates that the micelles in first critical micelle concentration regime are loosely packed relative to the second aggregate phase. We hypothesize that this loose packing results in diminished hydration shell repulsion between the micelles, leading to the large, micrometer-sized aggregates. We further hypothesize that it is the interaction with these loosely packed micelles that affects the flexibility of the HRP and protease enzyme structure. Time-resolved fluorescence anisotropy of subtilisin in Brij-30 indicates increasing flexibility of catalytic active site with surfactant concentration. This is correlated with an increase in enzymatic activity. PMID:24303849

  7. ESR study of free radicals in UHMW-PE fiber irradiated by gamma rays

    NASA Astrophysics Data System (ADS)

    Zhao, Yanning; Wang, Mouhua; Tang, Zhongfeng; Wu, Guozhong

    2010-04-01

    ESR spectra of the trapped radicals in an ultra-high molecular weight polyethylene (UHMW-PE) fiber irradiated by gamma rays showed well-resolved hyperfine splitting at room temperature since the c-axis of the crystallites is aligned with the fiber direction and the radicals are trapped in crystallites. The alkyl radical (-CH 2- •CH-CH 2-) was the major product after irradiation in vacuum and in air at room temperature. Some of the alkyl radicals converted to allyl radicals (-CH 2- •CH-CH=CH-) and polyenyl radicals (-CH 2- •CH-(CH=CH) n-CH 2-) during storage in vacuum. Upon storage in air atmosphere, the alkyl radicals decayed by reaction with oxygen. Of particular interest is the very slow decay rate of the alkyl radical trapped in UHMW-PE fiber, the half-life is 26 days in vacuum, and 13 days in air at room temperature, which is about 1/30 and 1/100 of that reported for high density polyethylene (HDPE), respectively. The extremely long lifetime of the alkyl radical is supposed to be caused by the large size of crystallites in UHMW-PE fiber. The rate of radical decay was accelerated by annealing at elevated temperature.

  8. Voltammetric and electrochemical ESR studies of oxidation reactions mediated by tris(4-bromophenyl)amine in acetonitrile.

    PubMed

    Wain, Andrew J; Streeter, Ian; Thompson, Mary; Fietkau, Nicole; Drouin, Ludovic; Fairbanks, Antony J; Compton, Richard G

    2006-02-16

    The electrochemical oxidation of tris(4-bromophenyl)amine in the presence of 2,6-lutidine is examined in acetonitrile. Voltammetric and spectroscopic investigations suggest that the electrogenerated triaryl aminium radical cation oxidizes 2,6-lutidine in an EC' mechanism, and an equilibrium constant for this homogeneous electron transfer is estimated. The mediated oxidation of a protected phenyl selenoglycoside by this reaction mixture is studied by the use of electrochemical ESR, employing a tubular flow cell, and signal intensity data is found to be consistent with the proposed mechanism, allowing the determination of kinetic parameters by computational simulation. Products of the mediated glycoside oxidation are determined by proton NMR and mass spectrometry. PMID:16471872

  9. ESR study of the radiolysis of cellobiose, cellulose-containing materials, and their mixtures with methyl methacrylate

    SciTech Connect

    Kozlova, E.Y.; Shostenko, A.G.; Ermolaev, S.V.

    1995-01-01

    The ESR spectra of {gamma}-irradiated cellobiose, paper waste, and cellulose extracted from paper waste and waste pulp sludge were analyzed. The kinetics of formation and decay of cellobiose radicals were investigated, and the radiation-chemical yields of the radicals formed in cellulose-containing materials were calculated. The ESR spectra of cellobiose irradiated in the presence of methyl methacrylate (MMA) were obtained. A probable mechanism of MMA grafting onto cellulose-containing matrices is considered.

  10. Validation of the Diesse Mini-Ves erythrocyte sedimentation rate (ESR) analyzer using the Westergren ESR method in patients with systemic inflammatory conditions.

    PubMed

    Happe, Marc R; Battafarano, Daniel F; Dooley, David P; Rennie, Thomas A; Murphy, Frederick T; Casey, Thomas J; Ward, John A

    2002-07-01

    The Diesse Mini-Ves (DMV) erythrocyte sedimentation rate (ESR) analyzer was designed to improve efficiency in determining the ESR. We compared the Westergren ESR method with the 4-sample DMV ESR analyzer for performance and clinical correlation. This prospective observational study, conducted at a 450-bed tertiary medical center, evaluated 291 paired samples from subjects with various systemic inflammatory conditions. Linear regression analysis revealed a statistically significant correlation between the 2 methods. Satisfactory precision of the DMV analyzer was obtained for high and mid-range ESR values. The 4-sample DMV ESR analyzer was precise and comparable in results to the Westergren ESR method. This DMV ESR analyzer is now used at our medical center based on quality control improvements that include a faster, safer, and more standardized ESR method. Hospital or office-based clinical laboratories should consider using the 4-sample DMV ESR analyzer in place of the Westergren method.

  11. ESR and magnetization studies of Fe2O3-Bi2O3-ZnO-PbO glass system

    NASA Astrophysics Data System (ADS)

    Pelluri, Sandhya Rani; Singh, Rajender

    2016-11-01

    The electron spin resonance (ESR) and magnetization measurements were undertaken to understand the magnetic phenomena in the glass system with composition (Fe2O3)x (70 Bi2O3 20 ZnO 10 PbO)1-x (x=15, 20 and 25 mol%). At high temperature the ESR spectra consists of narrow resonance at g~2. As the temperature decreases a second resonance peak emerges and with further decrease in temperature, the second resonance peak progressively shifts towards lower field value. The ESR data shows the formation of superparamagnetic clusters. The temperature dependent magnetization data exhibits a spin glass-like transition and a superparamagnetic blocking at a temperature which increases with increase in x value.

  12. Charge ordering in Nd2/3Ca1/3MnO3: ESR and magnetometry study

    NASA Astrophysics Data System (ADS)

    Polishchuk, D. M.; Tovstolytkin, A. I.; Fertman, E. L.; Desnenko, V. A.; Kravchyna, O.; Khalyavin, D. D.; Salak, A. N.; Anders, A. G.; Feher, A.

    2016-07-01

    The evolution of magnetic and electric properties of the narrow-band manganite Nd2/3Ca1/3MnO3 was studied by the electron-spin resonance (ESR), static magnetic field (dc) and resistivity techniques in the temperature range of 100-380 K. It was found that below the charge ordering temperature, TCO≈212 K, the compound is a mixture of the charge ordered and charge disordered phases in varying proportions depending on the temperature. The exchange phase process, when the amount of the charge ordered phase increases under cooling, while the amount of the charge disordered phase decreases is the most intense between ∼220 K and 180 K. At low temperatures, T<160 K, the charge ordered to the charge disordered phase ratio is about 4:1, which is in excellent agreement with previous neutron diffraction data. Both a sharp decrease of the magnetic susceptibility and a huge resistivity increase are evident of the weakening of ferromagnetic correlations and suppression of the double exchange interaction across the charge ordering due to the localization of the charge carriers.

  13. Studies on Cu(II) ternary complexes involving an aminopenicillin drug and imidazole containing ligands

    NASA Astrophysics Data System (ADS)

    Regupathy, Sthanumoorthy; Nair, Madhavan Sivasankaran

    2010-02-01

    Equilibrium studies on the ternary complex systems involving ampicillin (amp) as ligand (A) and imidazole containing ligands viz., imidazole (Him), benzimidazole (Hbim), histamine (Hist) and histidine (His) as ligands (B) at 37 °C and I = 0.15 mol dm -3 (NaClO 4) show the presence of CuABH, CuAB and CuAB 2. The proton in the CuABH species is attached to ligand A. In the ternary complexes the ligand, amp(A) binds the metal ion via amino nitrogen and carbonyl oxygen atom. The CuAB (B = Hist/His)/CuAB 2 (B = Him/Hbim) species have also been isolated and the analytical data confirmed its formation. Non-electrolytic behavior and monomeric type of chelates have been assessed from their low conductance and magnetic susceptibility values. The electronic and vibrational spectral results were interpreted to find the mode of binding of ligands to metal and geometry of the complexes. This is also supported by the g tensor values calculated from ESR spectra. The thermal behaviour of complexes were studied by TGA/DTA. The redox behavior of the complexes has been studied by cyclic voltammetry. The antimicrobial activity and CT DNA cleavage study of the complexes show higher activity for ternary complexes.

  14. Recent developments of high field ESR systems in Kobe

    NASA Astrophysics Data System (ADS)

    Ohta, H.; Tomoo, M.; Okubo, S.; Sakurai, T.; Fujisawa, M.; Tomita, T.; Kimata, M.; Yamamoto, T.; Kawauchi, M.; Kindo, K.

    2006-11-01

    The magnetic field of the high field ESR system in Kobe University has been extended to 55 T by using a new non-destructive pulse magnet and the 300 kJ (10kV) capacitor bank. The properties of new 55 T pulse magnet are reported. As an example of its application, the high field ESR measurement of a quantum spin system CsCuCl3 for Hparallela will be shown.

  15. Model membrane partition ESR study in the presence of alpha-tocopherol by a new spin probe

    SciTech Connect

    Severcan, F.; Cannistraro, S. )

    1989-08-01

    The effect of alpha-tocopherol (alpha T) on partitioning and fluidity changes occurring in phospholipid liposomes have been investigated by monitoring the X-band ESR spectrum of the high resolution amphiphilic spin probe perdeutero-di-t-butyl nitroxide (PDDTBN), which partitions in the lipid and water phase of liposomes, showing all the three resonances from each phase well resolved.

  16. Direct observation of hexamethylbenzenium radical cations generated during zeolite methanol-to-olefin catalysis: an ESR study.

    PubMed

    Kim, Sun Jung; Jang, Hoi-Gu; Lee, Jun Kyu; Min, Hyung-Ki; Hong, Suk Bong; Seo, Gon

    2011-09-01

    The generation of hexamethylbenzenium radical cations as the key reaction intermediate in chabazite-type molecular sieve acids (i.e., H-SAPO-34 and H-SSZ-13) during the methanol-to-olefin process has been directly evidenced by ESR spectroscopy. PMID:21766115

  17. Spin-probe ESR study on the dynamics of liquid molecules in the MCM-41 nanochannel: temperature dependence on 2-propanol and water.

    PubMed

    Okazaki, Masaharu; Toriyama, Kazumi

    2005-07-14

    A spin-probe ESR study has been made on the dynamics of 2-propanol and water molecules in the nanochannel of MCM-41 at various temperatures. In the former system, 2-propanol is separated into two phases: one with molecules immobilized in the ESR time scale and the other with mobile ones, even at temperatures more than 40 degrees higher than the bulk melting point. In the case of water, on the other hand, only the "immobilized" water was detected at a temperature as high as 313 K. At higher temperature, spin-probe molecule undergoes anisotropic rotational diffusion to reduce resistance from the solvent molecules in the nanochannel. These results are explained in relation to the intermolecular network intensified in the nanochannel. Static as well as dynamic structures of these solutions have been discussed.

  18. ESR study of the reaction of cyclopentadienyl complexes of zirconium hydrides with benzyl halides in the presence of 2,4,6-tri-tert-butylnitrosobenzene

    SciTech Connect

    Freidlina, R.Kh.; Gasanov, R.G.; Strunkina, L.I.; Brainina, E.M.

    1986-12-20

    An ESR study was carried out on the reactions of Cp/sub 2/ArH/sub 2/ (A), Cp/sub 2/ZrH(Cl) (B), and Cp/sub 3/ArH (C) (Cp = eta/sup 5/-C/sub 5/H/sub 5/) with benzyl halides in the presence of 2,4,6-tri-tert-butylnitrosobenzene (BNB). The ESR spectrum in the case of the reaction of (C) with BNB in benzene or toluene shows ArN(O)H radicals (Ar = 2,4,6-(Me/sub 3/C)/sub 3/C/sub 6/H/sub 2/) (a/sub H/ = 11.7, a/sub H/ = 13.0, a/sub m-H/ = 1.1 Oe). The ESR spectrum under the same conditions with C/sub 6/H/sub 5/CH/sub 2/Br shows signals for (C/sub 6/H/sub 5/CH/sub 2/N(O)Ar)/sub st/ radicals (I) (C approx. 5 x 10/sup -6/ M, a/sub N/ = 13.6, a/sub ..beta..-H/ = 14.7, a/sub m-H/ = 0.8 Oe). Radicals (I) were also obtained in the reaction of (C) with C/sub 6/H/sub 5/CH/sub 2/Cl in the presence of H, but the yield was only about 10/sup -7/ M. Radicals (I) were also detected by ESR spectroscopy in the reaction of (A) or (B) with C/sub 6/H/sub 5/CH/sub 2/Br. All the reactions were carried out in an inert-gas atmosphere at about 20/sup 0/C in the absence of irradiation. The formation of radicals (I) in the reactions studied may be attributed to the radical abstraction of bromine or chlorine from the benzyl halides.

  19. DFT studies of ESR parameters for N-O centered radicals, N-alkoxyaminyl and aminoxyl radicals.

    PubMed

    Tanaka, Akio; Nakashima, Kouichi

    2011-09-01

    Theoretical calculations of ESR parameters for aminoxyl radicals have been widely studied using the density functional theory (DFT) calculations. However, the isomer N-alkoxyaminyl radicals have been limitedly studied. With the use of experimental data for 46 N-alkoxyaminyl and 38 aminoxyl radicals, the isotropic (14)N hyperfine coupling constants (aN ) and g-factors have been theoretically estimated by several DFT calculations. The best calculation scheme of aN for N-alkoxyaminyl radicals was PCM/B3LYP/6-31 + + G(d,p) (R(2) = 0.9519, MAE = 0.034 mT), and that for aminoxyl radicals was PCM/BHandHLYP/6-31 + + G(3df,3pd) (R(2) = 0.9336, MAE = 0.057 mT). For aminoxyl radicals, the solvation models in calculations enhanced the accuracy of reproducibility. In contrast, for N-alkoxyaminyl radicals the calculations with solvation models provided no improvement. The differences in the best functionals between two types of radicals were thought to come from the contribution ratios of neutral and dipolar canonical structures in resonance forms. The aN for N-alkoxyaminyl radicals that were stabilized by small contribution of dipolar canonical structures could be precisely reproduced by B3LYP with only 20% HF exact exchange. In contrast, the aN for aminoxyl radicals stabilized by large contribution of dipolar canonical structures was well reproduced by BHandHLYP with 50% HF exchange. The best calculation scheme of g-factors was IEFPCM/B3LYP/6-31 + G(d,p) (R(2) = 0.9767, MAE = 0.0001) for not only aminoxyl but also N-alkoxyaminyl radicals.

  20. Efficiency and rate capability studies of the time-of-flight detector for isochronous mass measurements of stored short-lived nuclei with the FRS-ESR facility

    NASA Astrophysics Data System (ADS)

    Kuzminchuk-Feuerstein, Natalia; Fabian, Benjamin; Diwisch, Marcel; Plaß, Wolfgang R.; Geissel, Hans; Ayet San Andrés, Samuel; Dickel, Timo; Knöbel, Ronja; Scheidenberger, Christoph; Sun, Baohua; Weick, Helmut

    2016-06-01

    A time-of-flight (TOF) detector is used for Isochronous Mass Spectrometry (IMS) with the projectile fragment separator FRS and the heavy-ion storage ring ESR. Exotic nuclei are spatially separated in flight with the FRS at about 70% of the speed of light and are injected into the ESR. The revolution times of the stored ions circulating in the ESR are measured with a thin transmission foil detector. When the ions penetrate the thin detector foil, secondary electrons (SEs) are emitted from the surface and provide the timing information in combination with microchannel plate (MCP) detectors. The isochronous transport of the SEs is performed by perpendicular superimposed electric and magnetic fields. The detection efficiency and the rate capability of the TOF detector have been studied in simulations and experiments. As a result the performance of the TOF detector has been improved substantially: (i) The SE collection efficiency was doubled by use of an optimized set of electric and magnetic field values; now SEs from almost the full area of the foil are transmitted to the MCP detectors. (ii) The rate capability of the TOF detector was improved by a factor of four by the use of MCPs with 5 μm pore size. (iii) With these MCPs and a carbon foil with a reduced thickness of 10 μg/cm2 the number of recorded revolutions in the ESR has been increased by nearly a factor of 10. The number of recorded revolutions determine the precision of the IMS experiments. Heavy-ion measurements were performed with neon ions at 322 MeV/u and uranium fission fragments at about 370 MeV/u. In addition, measurements with an alpha source were performed in the laboratory with a duplicate of the TOF detector.

  1. Thermoluminescence, ESR and x-ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature thermal treatment

    NASA Astrophysics Data System (ADS)

    Bakshi, A. K.; Patwe, S. J.; Bhide, M. K.; Sanyal, B.; Natarajan, V.; Tyagi, A. K.; Kher, R. K.

    2008-01-01

    Thermoluminescence (TL), electron spin resonance (ESR) and x ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature treatment were carried out. Analysis of the TL glow curve indicated that the dosimetric glow peak at 240 °C reduces, whereas the low temperature satellite peak increases with the increase in the annealing temperature in the range 650-1000 °C. The influence of the annealing atmosphere on the TL glow curve structure was also observed. Reduction of the photoluminescence intensity of the annealed phosphor indicated that the environment of Dy3+ ions might have undergone some change due to high temperature treatment. Reduction in the ESR signal intensity corresponding to O_{3}^{-} and SO_{3}^{-} radicals was observed initially with the increase in the annealing temperaure; subsequently their intensity increased with temperature. Signals due to the SO_{4}^{-} radical vanished, when the phosphor was annealed beyond 800 °C. A signal corresponding to SH2- radicals was also observed in the ESR spectra for samples subjected to annealing in the temperature regime 800-1000 °C. XRD of the in situ annealed phosphor showed a change in the unit cell parameters. An endothermic peak at 860 °C in the DTA spectrum was observed.

  2. Validation of ESR analyzer using Westergren ESR method.

    PubMed

    Sikka, Meera; Tandon, Rajesh; Rusia, Usha; Madan, Nishi

    2007-07-01

    Erythrocyte sedimentation rate (ESR) is one of the most frequently ordered laboratory test. ESR analyzers were developed to provide a quick and efficient measure of ESR. We compared the results of ESR obtained by an ESR analyzer with those by the Westergren method in a group of 75 patients Linear regression analysis showed a good correlation between the two results (r = 0.818, p < 0.01). The intra class correlation was 0.82. The analyzer method had the advantages of safety, decreased technician time and improved patient care by providing quick results.

  3. Use of meta-analysis to combine candidate gene association studies: application to study the relationship between the ESR PvuII polymorphism and sow litter size.

    PubMed

    Alfonso, Leopoldo

    2005-01-01

    This article investigates the application of meta-analysis on livestock candidate gene effects. The PvuII polymorphism of the ESR gene is used as an example. The association among ESR PvuII alleles with the number of piglets born alive and total born in the first (NBA1, TNB1) and later parities (NBA, TNB) is reviewed by conducting a meta-analysis of 15 published studies including 9329 sows. Under a fixed effects model, litter size values were significantly lower in the "AA" genotype groups when compared with "AB" and "BB" homozygotes. Under the random effects model, the results were similar although differences between "AA" and "AB" genotype groups were not clearly significant for NBA and TNB. Nevertheless, the most noticeable result was the high and significant heterogeneity estimated among studies. This heterogeneity could be assigned to error sampling, genotype by environment interaction, linkage or epistasis, as referred to in the literature, but also to the hypothesis of population admixture/stratification. It is concluded that meta-analysis can be considered as a helpful analytical tool to synthesise and discuss livestock candidate gene effects. The main difficulty found was the insufficient information on the standard errors of the estimated genotype effects in several publications. Consequently, the convenience of publishing the standard errors or the concrete P-values instead of the test significance level should be recommended to guarantee the quality of candidate gene effect meta-analyses.

  4. Fe photoionization transitions in ZnSSe:Fe crystals - photo-ESR studies

    NASA Astrophysics Data System (ADS)

    Swiatek, K.; Godlewski, M.; Surkova, T. P.

    2005-02-01

    Photoionization transitions of iron ions in ZnSxSe1-x:Fe bulk crystals (0 x 1.0) were studied at temperature of 100 K. By monitoring changes of the Fe3+ electron spin resonance signal under external illumination, we are able to determine energies of Fe3+ Fe2+ + hVB transition in different ZnSxSe1-x host crystals. At low temperature (T < 170 K) we observe metastable population of photo-excited Fe3+ centres.

  5. ESR study of order and dynamics in lecithin liposomes with high cholesterol content

    NASA Astrophysics Data System (ADS)

    Costanzo, R.; De Paoli, T.; Ihlo, J. E.; Hager, A. A.; Farach, H. A.; Poole, C. P.; Knight, J. M.

    1994-02-01

    Previous studies have shown that increasing amounts of cholesterol in phosphatidyl choline liposomes (involving cholesterol/lecithin ratios up to 1), produce an increase in order and a decrease in mobility of the phospholipids in the bilayer. The present work focuses on the order and dynamics of the phospholipids in soybean and egg yolk liposomes with cholesterol/lecithin (chol/lec) ratios as high as 2. The influence of cholesterol on the order parameter and correlation times of 5-, 12- and 16-doxyl stearic acid probes, is analyzed for both types of liposomes. The order parameter increases continuously with the increase of the amount of cholesterol although the correlation time at first increases, then it levels off at a chol/lec ratio of 1, and thereafter shows a small, gradual decrease up to a ratio of 2. A statistical model of cholesterol substitution on the lecithin lattice was employed to explain the correlation time results.

  6. An ESR and DFT study of Hydration of the 2′-Deoxyuridine-5-yl Radical: Possible Hydroxyl Radical Intermediate

    PubMed Central

    Chomicz, Lidia; Petrovici, Alex; Archbold, Ian; Adhikary, Amitava; Kumar, Anil

    2014-01-01

    The mechanism of radiation-induced frank strand break formation in irradiated 5-bromo-2′-deoxyuridine (BrdU)-labelled DNA is still unclear, despite the proven radiosensitizing property of BrdU. Combination of ESR spectroscopy and quantum chemical modelling points to a simple reaction between the uridine-5-yl radical and water molecule that produces the genotoxic hydroxyl radical. PMID:25306924

  7. Photochemistry of acetylenic ketones in micellar solutions as studied by product-yield-detected ESR and transient absorption techniques.

    PubMed

    Polyakov, N E; Okazaki, M; Fukaya, H; Fujiwara, Y; Tanimoto, Y

    1995-06-01

    The electron spin resonance (ESR) spectra of the transient radical pairs in the photoreduction of 1,5-diphenyl-1,4-pentadiyn-3-one(I) and 1,3-diphenyl-2-propyn-1-one(II) in sodium dodecyl sulfate (SDS) micellar solutions have been obtained by using the product-yield-detected ESR (PYESR) technique. The PYESR spectra, detected by tracing the microwave effect on the spin-adduct yield as functions of the magnetic field, show the ESR spectra of the ketyl radical of the ketone and SDS radical as the components of the radical pairs. In addition, the growth and the decay processes of the radical pair were observed through detecting the effect of microwave pulse as functions of the delay period between a laser pulse and the off and on time, respectively, of a microwave pulse. The absorption spectra of transient species have also been obtained by using the laser flash photolysis technique. Through the analysis of these data and molecular orbital calculations, the role of acetylenic groups in the photoreactivity of acetylenic ketones is discussed.

  8. ESR studies on the thermal decomposition of trimethylamine oxide to formaldehyde and dimethylamine in jumbo squid (Dosidicus gigas) extract.

    PubMed

    Zhu, Junli; Jia, Jia; Li, Xuepeng; Dong, Liangliang; Li, Jianrong

    2013-12-15

    The effects of ferrous iron, heating temperature and different additives on the decomposition of trimethylamine oxide (TMAO) to formaldehyde (FA) and dimethylamine (DMA) and generation of free radicals in jumbo squid (Dosidicus gigas) extract during heating were evaluated by electron spin resonance (ESR). The thermal decomposition of TMAO to TMA, DMA and FA and free radical signals was observed in squid extract, whereas no DMA, FA and free radical signals were detected in cod extract or in aqueous TMAO solution in vitro at high temperatures. Significant increase in levels of DMA, FA and radicals intensity were observed in squid extract and TMAO solution in the presence of ferrous iron with increasing temperature. Hydrogen peroxide stimulated the production of DMA, FA and ESR signals in squid extract, while citric acid, trisodium citrate, calcium chloride, tea polyphenols and resveratrol had the opposite effect. Similar ESR spectra of six peaks regarded as amminium radical were detected in the squid extract and TMAO-iron(II) solution, suggesting that the amminium radical was involved in the decomposition of TMAO.

  9. Luminescence and ESR studies of relationships between O(-)-centres and structural iron in natural and synthetically hydrated kaolinites.

    PubMed

    Coyne, L M; Costanzo, P M; Theng, B K

    1989-01-01

    Luminescence, induced by dehydration and by wetting with hydrazine and unsymmetrically substituted hydrazine, and related ESR spectra have been observed from several kaolinites, synthetically hydrated kaolinites, and metahalloysites. The amine-wetting luminescence results suggest that intercalation, not a chemiluminescence reaction, is the luminescence trigger. Correlation between hydration-induced luminescence and g = 2 ESR signals associated with O(-)-centres in several natural halloysites, and concurrent diminution of the intensity of both these signal types as a function of aging in two 8.4 angstroms synthetically hydrated, kaolinites, confirm a previously-reported relationship between the luminescence induced by dehydration and in the presence of O(-)-centres (holes, i.e., electron vacancies) in the tetrahedral sheet. Furthermore, the ESR spectra of the 8.4 angstroms hydrate showed a concurrent change in the line shape of the g = 4 signal from a shape usually associated with structural Fe in an ordered kaolinite, to a simpler one typically observed in more disordered kaolinite, halloysite, and montmorillonite. Either structural Fe centres and the O(-)-centres interact, or both are subject to factors previously associated with degree of order. The results question the long-term stability of the 8.4 angstroms hydrate, although XRD does not indicate interlayer collapse over this period. Complex inter-relationships are shown between intercalation, stored energy, structural Fe, and the degree of hydration which may be reflected in catalytic as well as spectroscopic properties of the clays.

  10. Laser sputtering generation of B/sub 2/ for ESR matrix isolation studies: comparison with ab initio CI theoretical calculations

    SciTech Connect

    Knight, L.B. Jr.; Gregory, B.W.; Cobranchi, S.T.; Feller, D.; Davidson, E.R.

    1987-06-10

    The /sup 11/B/sub 2/ molecule has been trapped in neon and argon matrices at 5 +/- 1 K for ESR (electron spin resonance) investigations. Laser sputtering from solid boron was used to generate the B/sub 2/ molecule whose ground electronic state has been established experimentally for the first time to be /sup 3/..sigma../sub g//sup -/. The ESR nuclear hyperfine parameters for B/sub 2/ and B atoms have been compared with the results of ab initio CI theoretical calculations. Good agreement between theory and experiment is found for the dipolar component of the A tensor but not for the small and difficult to calculate isotropic hfs. Reasons that make the Fermi contact term especially difficult to calculate in this particular case are presented. The argon matrix ESR results yield the following magnetic parameters for /sup 11/B/sub 2/ in its ground electronic state: g/sub parallel/ = g/sub perpendicular/ = 2.0015 (4); A/sub parallel/ = +/- 11 (1) MHz and A/sub perpendicular/ = +/- 27.4 (3) MHz for /sup 11/B and the zero field parameter; and the D value is 3633 (3) MHz. As discussed, the most reasonable signs for the A values are A/sub parallel/ < O and A/sub perpendicular/ > 0. The neon matrix value of D was found to be 3840 (3) MHz and A/sub perpendicular/ in neon is +/- 26.6 (3) MHz.

  11. Luminescence and ESR studies of relationships between O(-)-centres and structural iron in natural and synthetically hydrated kaolinites

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Costanzo, P. M.; Theng, B. K.

    1989-01-01

    Luminescence, induced by dehydration and by wetting with hydrazine and unsymmetrically substituted hydrazine, and related ESR spectra have been observed from several kaolinites, synthetically hydrated kaolinites, and metahalloysites. The amine-wetting luminescence results suggest that intercalation, not a chemiluminescence reaction, is the luminescence trigger. Correlation between hydration-induced luminescence and g = 2 ESR signals associated with O(-)-centres in several natural halloysites, and concurrent diminution of the intensity of both these signal types as a function of aging in two 8.4 angstroms synthetically hydrated, kaolinites, confirm a previously-reported relationship between the luminescence induced by dehydration and in the presence of O(-)-centres (holes, i.e., electron vacancies) in the tetrahedral sheet. Furthermore, the ESR spectra of the 8.4 angstroms hydrate showed a concurrent change in the line shape of the g = 4 signal from a shape usually associated with structural Fe in an ordered kaolinite, to a simpler one typically observed in more disordered kaolinite, halloysite, and montmorillonite. Either structural Fe centres and the O(-)-centres interact, or both are subject to factors previously associated with degree of order. The results question the long-term stability of the 8.4 angstroms hydrate, although XRD does not indicate interlayer collapse over this period. Complex inter-relationships are shown between intercalation, stored energy, structural Fe, and the degree of hydration which may be reflected in catalytic as well as spectroscopic properties of the clays.

  12. Continuous-wave far-infrared ESR spectrometer for high-pressure measurements.

    PubMed

    Náfrádi, Bálint; Gaál, Richárd; Sienkiewicz, Andrzej; Fehér, Titusz; Forró, László

    2008-12-01

    We present a newly-developed microwave probe for performing sensitive high-field/multi-frequency electron spin resonance (ESR) measurements under high hydrostatic pressures. The system consists of a BeCu-made pressure-resistant vessel, which accommodates the investigated sample and a diamond microwave coupling window. The probe's interior is completely filled with a pressure-transmitting fluid. The setup operates in reflection mode and can easily be assembled with a standard oversized microwave circuitry. The probe-head withstands hydrostatic pressures up to 1.6 GPa and interfaces with our home-built quasi-optical high-field ESR facility, operating in a millimeter/submillimeter frequency range of 105-420 GHz and in magnetic fields up to 16 T. The overall performance of the probe was tested, while studying the pressure-induced changes in the spin-relaxation mechanisms of a quasi-1D conducting polymer, KC(60). The preliminary measurements revealed that the probe yields similar signal-to-noise ratio to that of commercially available low-frequency ESR spectrometers. Moreover, by observing the conduction electron spin resonance (CESR) linewidth broadening for KC(60) in an unprecedented microwave frequency range of 210-420 GHz and in the pressure range of up to 1.6 GPa, we demonstrate that a combination of high-pressure ESR probe and high-field/multi-frequency spectrometer allows us to measure the spin relaxation rates in conducting spin systems, like the quasi-1D conductor, KC(60).

  13. Studies of gas adsorption on ZnO using ESR, FTIR spectroscopy, and MHE (Microwave Hall Effect) measurements

    SciTech Connect

    Byungki Na; Vannice, M.A. ); Walters, A.B. )

    1993-04-01

    This paper describes the application of a new technique - Microwave Hall Effect (MHE) measurements - to measure electron mobilities and to determine the effect of adsorption on electron densities of powders. Conduction electron densities calculated from microwave measurements of both mobilities and conductivities, as well as ESR spectroscopy and chemisorption measurements, have been applied to characterize high-surface-area ZnO (up to 30 m[sup 2]/g) samples before and after exposure to O[sub 2], CO[sub 2], CO, and H[sub 2]. Evacuation at 673 K removed lattice oxygen to produce paramagnetic lattice vacancies, (V[sub 0][sup +])[sup [minus

  14. Production of oxygen-centered radicals by neutrophils and macrophages as studied by electron spin resonance (ESR).

    PubMed Central

    Bannister, J V; Bannister, W H

    1985-01-01

    Neutrophils and macrophages undergo a respiratory burst and an increase in the activity of the hexose monophosphate pathway in response to particulate or soluble agents. The increase in oxygen consumption was found to be associated with the production of oxygen-centered radicals. The ESR technique of spin trapping showed that besides a superoxide spin adduct, a hydroxyl spin adduct is also produced. ESR is considered to be the least ambiguous technique for the detection of free radicals. The spin-trapping agents used for oxygen-centered radical detection are usually nitrones. The most commonly used nitrone is 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), which reacts with O2-. to form 5,5-dimethyl-2-hydroperoxypyrroline-N-oxide (DMPO-OOH) and with OH. to form 5,5-dimethyl-2-hydroxypyrroline-N-oxide (DMPO-OH). Although spin-adduct formation is considered to be the most direct technique for the detection of free radicals, some disadvantages are encountered. There has been considerable interest in the isolation of the O2-. generating activity from phagocytic cells. The enzyme can be extracted with deoxycholate and gel filtration indicates that it is a high molecular weight complex. Maximum activity was between pH 7.0 and pH 7.5. The Km value was 15.8 microM for NADPH and 434 micron for NADH, indicating that NADPH is the preferred substrate. PMID:3007099

  15. ESR teleradiology survey: results.

    PubMed

    2016-08-01

    With recent developments of teleradiology technology and services, it has become necessary to better evaluate its extent and use among different countries in Europe. With this goal in mind, the ESR launched two specific surveys intended to gather the current state of adoption and implementation of teleradiology in clinical practice. A special focus on differentiating between insourcing teleradiology services among partners of the same organisation and outsourcing to external services was an essential part of the design of these surveys. The first survey was addressed to 44 national societies of different countries in Europe, while the second survey was intended for all practicing radiologist ESR members. While the results of these surveys reported here may provide a wealth of information to better understand the trends in adoption of teleradiology in Europe, they only represent a snapshot at a certain point in time. The rapid development of telecommunication tools as well as a fundamental change in practice and healthcare economics will certainly influence these observations in the upcoming years. These data, however, will provide objective and relevant parameters for supporting the efforts of experts and policy makers in promoting appropriate criteria and guidelines for adequate use of teleradiology in clinical practice. Main Messages • Understand concepts and challenges of teleradiology • Provide insight into current trends and solutions for teleradiology • Compare differences in teleradiolgy strategies between countries in Europe • Establish a reference on statistical data of usage of teleradiology in Europe. PMID:27188379

  16. Solvation of exchangeable Cu/sup 2 +/ cations by primary alcohols in montmorillonite clay studied by electron spin resonance and electron spin echo modulation spectroscopies

    SciTech Connect

    Brown, D.R.; Kevan, L.

    1988-04-07

    A montmorillonite clay (STx-1), with Mg/sup 2 +/ as the major exchangeable cation and Cu/sup 2 +/ exchanged into 5% of the Mg/sup 2 +/ sites, is used to study the interaction between the exchangeable cations and adsorbed primary alcohols, methanol, ethanol, and 1-propanol, in the clay interlayer region. Electron spin resonance (ESR) shows that, on saturation of the clay with methanol, a freely rotating Cu/sup 2 +/ center is formed in the clay interlayer. Electron spin echo modulation (ESEM) spectroscopy indicates that the center is a four-coordinate Cu/sup 2 +/ solvate, in which the methanol ligands are in a square-planar configuration. On adsorption of ethanol into the interlayer region, a rotationally restricted Cu/sup 2 +/ center is detected. ESEM again indicates a four-coordinate, square-planar solvate, and ESR of oriented clay films reveals that the major symmetry axis of the ethanol-solvated Cu/sup 2 +/ center is perpendicular to the plane of the clay lattice. Similar ESP data are reported for 1-propanol-saturated montmorillonite, and a four-coordinate, square-planar Cu/sup 2 +/ solvate, similar to that described for ethanol, is proposed.

  17. Radiolysis of carbohydrates as studied by ESR and spin-trapping—II. Glycerol- d8 xylitol, dulcitol, d-sorbitol and d-mannitol

    NASA Astrophysics Data System (ADS)

    Kuwabara, M.; Zhang, Z.-Y.; Inanami, O.; Yoshii, G.

    Studies concerning the radicals produced in glycerol by reactions with OH radicals have been carried out by investigating deuterated glycerol (glycerol-d 8) by spin-trapping with 2-methyl-2-nitrosopropane. Free radicals produced in linear carbohydrates such as xylitol, dulcitol, D-sorbitol and D-mannitol by reactions with OH radicals as well as by direct γ-radiolysis have been also investigated by spin-trapping. The ESR spectra of the spin-trapped radicals were analysed on the basis of the results from ESR and spin-trapping experiments on glycerol and deuterated glycerol, and the formation of three radical species, CHO-CH-, CH 2-CO- and HO-CH-, due to both OH reactions and direct γ-radiolysis was confirmed for all compounds. The presence of a radical, -CO-CH-, was detected for xylitol, D-sorbitol and D-mannitol. General reactions processes induced by OH reactions or γ-radiolysis in the solid state are discussed.

  18. Conformational distributions and hydrogen bonding in gel and frozen lipid bilayers: a high frequency spin-label ESR study.

    PubMed

    Dzikovski, Boris; Tipikin, Dmitriy; Freed, Jack

    2012-06-14

    The ESR parameters of PC spin labels in frozen membranes do not simply represent the membrane polarity or water penetration profile. Instead, they show a distribution between hydrogen-bonded (HB) and non-hydrogen-bonded (non-HB) states, which is affected by a number of factors in the membrane composition. Similar to the exclusion of solutes from crystallizing solvents, the pure bulk gel phase excludes nitroxides, forcing acyl chains to take bent conformations. In these conformations, the nitroxide is hydrogen-bonded. Furthermore, upon gradual cooling in the supercooled gel, PC labels undergo slow lateral aggregation, resulting in a broad background signal. However, if the sample is instantly frozen, this background is replaced by the HB component. In membranes with cholesterol, the observed HB/non-HB ratio can best be described by a partition-like equilibrium between nitroxides located in defects of lipid structure within the hydrophobic core and those close to the membrane surface. PMID:22324811

  19. Conformational Distributions and Hydrogen Bonding in Gel and Frozen Lipid Bilayers: A High Frequency Spin-Label ESR Study

    PubMed Central

    Dzikovski, Boris; Tipikin, Dmitriy

    2012-01-01

    The ESR parameters of PC spin labels in frozen membranes do not simply represent the membrane polarity or water penetration profile. Instead, they show a distribution between hydrogen-bonded (HB) and non-hydrogen bonded (non-HB) states, which is affected by a number of factors in the membrane composition. Similar to the exclusion of solutes from crystallizing solvents, the pure bulk gel phase excludes nitroxides, forcing acyl chains to take bent conformations. In these conformations the nitroxide is hydrogen-bonded. Furthermore, upon gradual cooling in the supercooled gel PC labels undergo slow lateral aggregation resulting in a broad background signal. However, if the sample is instantly frozen, this background is replaced by the HB component. In membranes with cholesterol the observed HB/ non-HB ratio can best be described by a partition-like equilibrium between nitroxides located in defects of lipid structure within the hydrophobic core and those close to the membrane surface. PMID:22324811

  20. Persistent free radical ESR signals in marine bivalve tissues. [Electron Spin Resonance (ESR)

    SciTech Connect

    Mehlorn, R.J. . Dept. of Materials Science and Mineral Engineering); Mendez, A.T. ); Higashi, R. . Bodega Marine Lab.); Fan, T. )

    1992-08-01

    Freeze-dried homogenates of the oyster Crassostrea rhizophorae collected from waters in Puerto Rico near urban and industrial sites as well as at relatively pristine locations yielded electron spin resonance (ESR) spectra characteristic of free radicals as well as spectral components of transition metal ions, dominated by manganese. The magnitudes of these ESR signals and the concentrations of trace elements (determined by X-ray fluorescence) varied considerably among oyster samples, masking any potential correlation with polluted waters. Laboratory studies were initiated to identify the factors controlling the magnitudes of the tissue free radical ESR signals. Another mollusc, Mytilus californianus collected at the Bodega Marine laboratory in northern California, was fractionated into goneds and remaining tissue. Freeze-dried homogenates of both fractions exhibited ESR signals that increased gradually with time. ESR signals were observed in freeze-dried perchloric acid (PCA) precipitates of the homogenates, delipidated PCA precipitates, and in chloroform extracts of these precipitates. Acid hydrolysis to degrade proteins to amino acids produced a residue, which yielded much larger ESR free radical signals after freeze-drying. Freshly thawed homogenates of Crassostrea rhizophorae also exhibited ESR signals. A laboratory model of copper stress in Crassostrea rhizophorae was developed to study the effect of this transition metal on dssue free radicals. Preliminary results suggested that sublethal copper exposure had little effect on tissue fire radicals, except possibly for a signal enhancement in an oyster fraction that was enriched in kidney granules. Since kidney granules are known to accumulate heavy metals in mussels and probably other marine bivalves, this signal enhancement may prove to be an indicator of free radical processes associated with heavy metal deposition in molluscs.

  1. Prognostic Significance of ESR1 Gene Amplification, mRNA/Protein Expression and Functional Profiles in High-Risk Early Breast Cancer: A Translational Study of the Hellenic Cooperative Oncology Group (HeCOG)

    PubMed Central

    Pentheroudakis, George; Kotoula, Vassiliki; Eleftheraki, Anastasia G.; Tsolaki, Eleftheria; Wirtz, Ralph M.; Kalogeras, Konstantine T.; Batistatou, Anna; Bobos, Mattheos; Dimopoulos, Meletios A.; Timotheadou, Eleni; Gogas, Helen; Christodoulou, Christos; Papadopoulou, Kyriaki; Efstratiou, Ioannis; Scopa, Chrisoula D.; Papaspyrou, Irene; Vlachodimitropoulos, Dimitrios; Linardou, Helena; Samantas, Epaminontas; Pectasides, Dimitrios; Pavlidis, Nicholas; Fountzilas, George

    2013-01-01

    Background Discrepant data have been published on the incidence and prognostic significance of ESR1 gene amplification in early breast cancer. Patients and Methods Formalin-fixed paraffin-embedded tumor blocks were collected from women with early breast cancer participating in two HeCOG adjuvant trials. Messenger RNA was studied by quantitative PCR, ER protein expression was centrally assessed using immunohistochemistry (IHC) and ESR1 gene copy number by dual fluorescent in situ hybridization probes. Results In a total of 1010 women with resected node-positive early breast adenocarcinoma, the tumoral ESR1/CEP6 gene ratio was suggestive of deletion in 159 (15.7%), gene gain in 551 (54.6%) and amplification in 42 cases (4.2%), with only 30 tumors (3%) harboring five or more ESR1 copies. Gene copy number ratio showed a significant, though weak correlation to mRNA and protein expression (Spearman's Rho <0.23, p = 0.01). ESR1 clusters were observed in 9.5% (57 gain, 38 amplification) of cases. In contrast to mRNA and protein expression, which were favorable prognosticators, gene copy number changes did not obtain prognostic significance. When ESR1/CEP6 gene ratio was combined with function (as defined by ER protein and mRNA expression) in a molecular classifier, the Gene Functional profile, it was functional status that impacted on prognosis. In univariate analysis, patients with functional tumors (positive ER protein expression and gene ratio normal or gain/amplification) fared better than those with non-functional tumors with ESR1 gain (HR for relapse or death 0.49–0.64, p = 0.003). Significant interactions were observed between gene gain/amplification and paclitaxel therapy (trend for DFS benefit from paclitaxel only in patients with ESR1 gain/amplification, p = 0.066) and Gene Functional profile with HER2 amplification (Gene Functional profile prognostic only in HER2-normal cases, p = 0.029). Conclusions ESR1 gene deletion and amplification do not

  2. ESR response of gamma-irradiated sulfamethazine

    NASA Astrophysics Data System (ADS)

    Çolak, Seyda; Korkmaz, Mustafa

    In the present work, characteristic features of the radiolytical intermediates produced in gamma-irradiated solid sulfamethazine (SMH) were investigated by electron spin resonance (ESR) spectroscopy. The heights of the resonance peaks, measured with respect to the spectrum baseline, were used to monitor microwave saturation, temperature and time-dependent kinetic features of the radical species contributing to the formation of recorded experimental ESR spectra. Three species having different spectroscopic and kinetic features were observed to be produced in gamma-irradiated SMH. SO2, which is the most sensitive group of radiation in the SMH molecule, was found to be at the origin of radiation-produced ionic radical species. Based on the experimental results derived from the present study, the applicability of ESR spectroscopy to radiosterilization of SMH was discussed. In the dose range of interest (0.5-10 kGy), the radiation yield of solid SMH was calculated to be very low (G=0.45) compared with those obtained for sulfonamide aqueous solutions (G=3.5-5.1). Based on these findings, it was concluded that SMH and SMH-containing drugs could be safely sterilized by gamma radiation and that ESR spectroscopy could be successfully used as a potential technique for monitoring their radiosterilization.

  3. In vivo dosimetry in the urethra using alanine/ESR during (192)Ir HDR brachytherapy of prostate cancer--a phantom study.

    PubMed

    Anton, Mathias; Wagner, Daniela; Selbach, Hans-Joachim; Hackel, Thomas; Hermann, Robert Michael; Hess, Clemens Friedrich; Vorwerk, Hilke

    2009-05-01

    A phantom study for dosimetry in the urethra using alanine/ESR during (192)Ir HDR brachytherapy of prostate cancer is presented. The measurement method of the secondary standard of the Physikalisch-Technische Bundesanstalt had to be slightly modified in order to be able to measure inside a Foley catheter. The absorbed dose to water response of the alanine dosimetry system to (192)Ir was determined with a reproducibility of 1.8% relative to (60)Co. The resulting uncertainty for measurements inside the urethra was estimated to be 3.6%, excluding the uncertainty of the dose rate constant Lambda. The applied dose calculated by a treatment planning system is compared to the measured dose for a small series of (192)Ir HDR irradiations in a gel phantom. The differences between the measured and applied dose are well within the limits of uncertainty. Therefore, the method is considered to be suitable for measurements in vivo.

  4. Association between oestrogen receptor alpha (ESR1) gene polymorphisms and endometriosis: a meta-analysis of 24 case-control studies.

    PubMed

    Zhao, Luyang; Gu, Chenglei; Huang, Ke; Fan, Wensheng; Li, Lian; Ye, Mingxia; Han, Weidong; Meng, Yuanguang

    2016-09-01

    The PvuII (C > T), XbaI (A > G) and (TA)n polymorphisms of ESR1 gene are potentially associated with susceptibility to endometriosis. A meta-analysis was conducted to evaluate comprehensively the associations between endometriosis and ESR1 polymorphisms. Twenty-four studies, including 2740 cases and 3208 controls, were retrieved through searches of PubMed, EMBASE, Web of Science, CBM and CNKI. Meta-analyses showed that PvuII was associated with endometriosis only for stage I-III, only under a recessive model (OR = 1.53, 95% CI 1.05 to 2.21; P = 0.025). The short allele and TA13 of (TA)n were associated with a higher risk of endometriosis (ORS = 1.71, 95% CI 1.01 to 2.81, P = 0.046; ORTA13 = 1.45, 95% CI 1.06 to 1.97, PTA13 = 0.019); TA20 repeats was associated with a lower risk (OR = 0.36, 95% CI 0.16 to 0.80; P = 0.012). No statistically significant association was found in the XbaI polymorphism. This meta-analysis indicated that the PvuII and XbaI polymorphisms were not associated with the risk of endometriosis, whereas stage classification of endometriosis was likely to influence the association of PvuII polymorphism. The (TA)n polymorphisms might play roles in the susceptibility to, or protection against, the pathogenesis of endometriosis. PMID:27373811

  5. Isotope effects in ESR spectroscopy.

    PubMed

    Stößer, Reinhard; Herrmann, Werner

    2013-06-07

    In order to present the relationship between ESR spectroscopy and isotope effects three levels are considered: (i) ESR spectroscopy is described on a general level up to the models for interpretation of the experimental spectra, which go beyond the usually used time and mass independent spin-Hamilton operator, (ii) the main characteristics of the generalized isotope effects are worked out, and finally (iii) the basic, mainly quantum mechanical effects are used to describe the coupling of electron spins with the degrees of freedom, which are accessible under the selected conditions, of the respective paramagnetic object under investigation. The ESR parameters and the respective models are formalized so far, that they include the time and mass depending influences and reflect the specific isotope effects. Relations will be established between the effects in ESR spectra to spin relaxation, to spin exchange, to the magnetic isotope effect, to the Jahn-Teller effects, as well as to the influence of zero-point vibrations. Examples will be presented which demonstrate the influence of isotopes as well as the kind of accessible information. It will be differentiated with respect to isotope effects in paramagnetic centres itself and in the respective matrices up to the technique of ESR imaging. It is shown that the use of isotope effects is indispensable in ESR spectroscopy.

  6. ESR modes in a Strong-Leg Ladder in the Tomonaga-Luttinger Liquid Phase

    NASA Astrophysics Data System (ADS)

    Zvyagin, S.; Ozerov, M.; Maksymenko, M.; Wosnitza, J.; Honecker, A.; Landee, C. P.; Turnbull, M.; Furuya, S. C.; Giamarchi, T.

    Magnetic excitations in the strong-leg quantum spin ladder compound (C7H10N)2CuBr4 (known as DIMPY) in the field-induced Tomonaga-Luttinger spin liquid phase are studied by means of high-field electron spin resonance (ESR) spectroscopy. The presence of a gapped ESR mode with unusual non-linear frequency-field dependence is revealed experimentally. Using a combination of analytic and exact diagonalization methods, we compute the dynamical structure factor and identify this mode with longitudinal excitations in the antisymmetric channel. We argue that these excitations constitute a fingerprint of the spin dynamics in a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder and owe its ESR observability to the uniform Dzyaloshinskii-Moriya interaction. This work was partially supported by the DFG and Helmholtz Gemeinschaft (Germany), Swiss SNF under Division II, and ERC synergy UQUAM project. We acknowledge the support of the HLD at HZDR, member of the European Magnetic Field Laboratory (EMFL).

  7. Fundamental studies of methanol synthesis from CO(2) hydrogenation on Cu(111), Cu clusters, and Cu/ZnO(0001).

    PubMed

    Yang, Yixiong; Evans, Jaime; Rodriguez, Jose A; White, Michael G; Liu, Ping

    2010-09-01

    A combination of experimental and theoretical methods were employed to investigate the synthesis of methanol via CO(2) hydrogenation (CO(2) + 3H(2)--> CH(3)OH + H(2)O) on Cu(111) and Cu nanoparticle surfaces. High pressure reactivity studies show that Cu nanoparticles supported on a ZnO(0001[combining macron]) single crystal exhibit a higher catalytic activity than the Cu(111) planar surface. Complementary density functional theory (DFT) calculations of methanol synthesis were also performed for a Cu(111) surface and unsupported Cu(29) nanoparticles, and the results support a higher activity for Cu nanoparticles. The DFT calculations show that methanol synthesis on Cu surfaces proceeds through a formate intermediate and the overall reaction rate is limited by both formate and dioxomethylene hydrogenation. Moreover, the superior activity of the nanoparticle is associated with its fluxionality and the presence of low-coordinated Cu sites, which stabilize the key intermediates, e.g. formate and dioxomethylene, and lower the barrier for the rate-limiting hydrogenation process. The reverse water-gas-shift (RWGS) reaction (CO(2) + H(2)--> CO + H(2)O) was experimentally observed to compete with methanol synthesis and was also considered in our DFT calculations. In agreement with experiment, the rate of the RWGS reaction on Cu nanoparticles is estimated to be approximately 2 orders of magnitude faster than methanol synthesis at T = 573 K. The experiments and calculations also indicate that CO produced by the fast RWGS reaction does not undergo subsequent hydrogenation to methanol, but instead simply accumulates as a product. Methanol production from CO hydrogenation via the RWGS pathway is hindered by the first hydrogenation of CO to formyl, which is not stable and prefers to dissociate into CO and H atoms on Cu. Our calculated results suggest that the methanol yield over Cu-based catalysts could be improved by adding dopants or promoters which are able to stabilize formyl

  8. Physics book: CRYRING@ESR

    NASA Astrophysics Data System (ADS)

    Lestinsky, M.; Andrianov, V.; Aurand, B.; Bagnoud, V.; Bernhardt, D.; Beyer, H.; Bishop, S.; Blaum, K.; Bleile, A.; Borovik, At.; Bosch, F.; Bostock, C. J.; Brandau, C.; Bräuning-Demian, A.; Bray, I.; Davinson, T.; Ebinger, B.; Echler, A.; Egelhof, P.; Ehresmann, A.; Engström, M.; Enss, C.; Ferreira, N.; Fischer, D.; Fleischmann, A.; Förster, E.; Fritzsche, S.; Geithner, R.; Geyer, S.; Glorius, J.; Göbel, K.; Gorda, O.; Goullon, J.; Grabitz, P.; Grisenti, R.; Gumberidze, A.; Hagmann, S.; Heil, M.; Heinz, A.; Herfurth, F.; Heß, R.; Hillenbrand, P.-M.; Hubele, R.; Indelicato, P.; Källberg, A.; Kester, O.; Kiselev, O.; Knie, A.; Kozhuharov, C.; Kraft-Bermuth, S.; Kühl, T.; Lane, G.; Litvinov, Yu. A.; Liesen, D.; Ma, X. W.; Märtin, R.; Moshammer, R.; Müller, A.; Namba, S.; Neumeyer, P.; Nilsson, T.; Nörtershäuser, W.; Paulus, G.; Petridis, N.; Reed, M.; Reifarth, R.; Reiß, P.; Rothhardt, J.; Sanchez, R.; Sanjari, M. S.; Schippers, S.; Schmidt, H. T.; Schneider, D.; Scholz, P.; Schuch, R.; Schulz, M.; Shabaev, V.; Simonsson, A.; Sjöholm, J.; Skeppstedt, Ö.; Sonnabend, K.; Spillmann, U.; Stiebing, K.; Steck, M.; Stöhlker, T.; Surzhykov, A.; Torilov, S.; Träbert, E.; Trassinelli, M.; Trotsenko, S.; Tu, X. L.; Uschmann, I.; Walker, P. M.; Weber, G.; Winters, D. F. A.; Woods, P. J.; Zhao, H. Y.; Zhang, Y. H.

    2016-09-01

    The exploration of the unique properties of stored and cooled beams of highly-charged ions as provided by heavy-ion storage rings has opened novel and fascinating research opportunities in the realm of atomic and nuclear physics research. Since the late 1980s, pioneering work has been performed at the CRYRING at Stockholm (Abrahamsson et al. 1993) and at the Test Storage Ring (TSR) at Heidelberg (Baumann et al. 1988). For the heaviest ions in the highest charge-states, a real quantum jump was achieved in the early 1990s by the commissioning of the Experimental Storage Ring (ESR) at GSI Helmholtzzentrum für Schwerionenforschung (GSI) in Darmstadt (Franzke 1987) where challenging experiments on the electron dynamics in the strong field regime as well as nuclear physics studies on exotic nuclei and at the borderline to atomic physics were performed. Meanwhile also at Lanzhou a heavy-ion storage ring has been taken in operation, exploiting the unique research opportunities in particular for medium-heavy ions and exotic nuclei (Xia et al. 2002).

  9. ESR identification of gamma-irradiated albendazole

    NASA Astrophysics Data System (ADS)

    Çolak, Seyda

    2010-01-01

    The use of ionizing radiation for sterilization of pharmaceuticals is a well-established technology. In the present work, the spectroscopic and kinetic features of the radicals induced in gamma-irradiated solid albendazole samples is investigated at different temperatures in the dose range of 3-34 kGy by electron spin resonance (ESR) spectroscopy. Irradiation with gamma radiation produced two different radical species in albendazole. They were fairly stable at room temperature but relatively unstable above room temperature, giving rise to an unresolved ESR spectrum consisting of three resonance peaks centered at g=2.0057. Decay activation energies of the contributing radical species were calculated to be 47.8 (±13.5) and 50.5 (±9.7) kJ/mol using the signal intensity decay data derived from annealing studies performed at high temperatures. A linear function of the applied dose was found to best describe the experimental dose-response data. Albendazole does not present the characteristics of good dosimetric materials. However, the discrimination of irradiated albendazole from its unirradiated form was possible even 6 months after storage in normal conditions. Based on these findings, it is concluded that albendazole and albendazole-containing drugs can be safely sterilized by gamma radiation and that ESR spectroscopy could be successfully used as a potential technique for monitoring their radiosterilization.

  10. ROS production in homogenate from the body wall of sea cucumber Stichopus japonicus under UVA irradiation: ESR spin-trapping study.

    PubMed

    Qi, Hang; Dong, Xiu-fang; Zhao, Ya-ping; Li, Nan; Fu, Hui; Feng, Ding-ding; Liu, Li; Yu, Chen-xu

    2016-02-01

    Sea cucumber Stichopus japonicus (S. japonicus) shows a strong ability of autolysis, which leads to severe deterioration in sea cucumber quality during processing and storage. In this study, to further characterize the mechanism of sea cucumber autolysis, hydroxyl radical production induced by ultraviolet A (UVA) irradiation was investigated. Homogenate from the body wall of S. japonicas was prepared and subjected to UVA irradiation at room temperature. Electron Spin Resonance (ESR) spectra of the treated samples were subsequently recorded. The results showed that hydroxyl radicals (OH) became more abundant while the time of UVA treatment and the homogenate concentration were increased. Addition of superoxide dismutase (SOD), catalase, EDTA, desferal, NaN3 and D2O to the homogenate samples led to different degrees of inhibition on OH production. Metal cations and pH also showed different effects on OH production. These results indicated that OH was produced in the homogenate with a possible pathway as follows: O2(-) → H2O2 → OH, suggesting that OH might be a critical factor in UVA-induced S. japonicus autolysis.

  11. ESR Study of Electron-Nuclear Dipolar Relaxation for AsO 44-Spin Probe in the Paraelectric Phase of KH 2AsO 4

    NASA Astrophysics Data System (ADS)

    Rakvin, B.; Merunka, D.

    1997-05-01

    Saturation behavior of allowed and forbidden ESR transition of AsO44-paramagnetic probe in KH2AsO4was studied in the wide temperature interval around the paraelectric-ferroelectric phase transition,Tc. The ratios between forbidden and allowed line intensities were employed to deduce information on the electron-nuclear dipolar (END) relaxation mechanism. It was shown that a proton END relaxation mechanism exhibits an extremal temperature behavior in the paraelectric phase around 230 K. The extremal temperature behavior was described by employing a model of proton hopping along the O-H···O bonds around the paramagnetic centers, and the correlation time of this hopping was estimated in the wide temperature range in the paraelectric phase (150-330 K). The temperature dependence of effective proton distance from the neighbor oxygens was obtained, and it was discussed in terms of a localization of the spin density on these oxygens caused by charge inbalance in the As-O bonds in the ferroelectric phase.

  12. Spectroscopic Evidence for Covalent Binding of Sulfadiazine to Natural Soils via 1,4-nucleophilic addition (Michael Type Addition) studied by Spin Labeling ESR

    NASA Astrophysics Data System (ADS)

    Aleksandrova, Olga

    2015-04-01

    Among different classes of veterinary pharmaceuticals, Sulfadiazine (SDZ) is widely used in animal husbandry. Its residues were detected in different environmental compartments. However, soil is a hot spot for SDZ as it receives a large portion of excreted compounds through the application of manure during soil fertilization. Ample studies on the fate of SDZ in soils showed that a large portion forms nonextractable residues (NER) along with transformation products and a low mineralization (Mueller et al., 2013). A common observation was an initially fast formation of NER up to 10% of the applied amount promptly after the application of SDZ to soil, and this portion increased up to 50% within a few days (Mueller et al., 2013; Nowak et al., 2011). A common finding for SDZ, as for other sulfonamides, was biphasic kinetics of the formation of NER, which was attributed to the occurrence of two reaction processes: a rapid, often reversible process and a slower, irreversible process (Weber et al., 1996). A single-phase reaction process was also established under anaerobic treatment (Gulkowska et al., 2014). A major focus of this work is to elucidate a reaction mechanism of covalent binding of SDZ to soil that is currently required to estimate a risk of NER formed by SDZ in soils for human health. Taking into account a key role of the amine functional groups of SDZ on its reactivity in soil, nitroxide radicals with the sewed aromatic or aliphatic amines labeled soil samples and then, were investigated by means of ESR spectroscopy. 2,5,5-Trimethyl-2-(3-aminophenyl)pyrrolidin-1-yloxy and 4-amino-2,2,6,6-Tetramethylpiperidin-1-oxyl modeled decomposition products of SDZ with the aromatic and aliphatic amines, respectively. The application of the defined combination of both spin labels (SL) to different soils well simulated a change of a paramagnetic signal of soil organic radicals interacted with SDZ. After their application to soil, SL were found in soil sites characterized

  13. Spectroscopic Evidence for Covalent Binding of Sulfadiazine to Natural Soils via 1,4-nucleophilic addition (Michael Type Addition) studied by Spin Labeling ESR

    NASA Astrophysics Data System (ADS)

    Aleksandrova, Olga

    2015-04-01

    Among different classes of veterinary pharmaceuticals, Sulfadiazine (SDZ) is widely used in animal husbandry. Its residues were detected in different environmental compartments. However, soil is a hot spot for SDZ as it receives a large portion of excreted compounds through the application of manure during soil fertilization. Ample studies on the fate of SDZ in soils showed that a large portion forms nonextractable residues (NER) along with transformation products and a low mineralization (Mueller et al., 2013). A common observation was an initially fast formation of NER up to 10% of the applied amount promptly after the application of SDZ to soil, and this portion increased up to 50% within a few days (Mueller et al., 2013; Nowak et al., 2011). A common finding for SDZ, as for other sulfonamides, was biphasic kinetics of the formation of NER, which was attributed to the occurrence of two reaction processes: a rapid, often reversible process and a slower, irreversible process (Weber et al., 1996). A single-phase reaction process was also established under anaerobic treatment (Gulkowska et al., 2014). A major focus of this work is to elucidate a reaction mechanism of covalent binding of SDZ to soil that is currently required to estimate a risk of NER formed by SDZ in soils for human health. Taking into account a key role of the amine functional groups of SDZ on its reactivity in soil, nitroxide radicals with the sewed aromatic or aliphatic amines labeled soil samples and then, were investigated by means of ESR spectroscopy. 2,5,5-Trimethyl-2-(3-aminophenyl)pyrrolidin-1-yloxy and 4-amino-2,2,6,6-Tetramethylpiperidin-1-oxyl modeled decomposition products of SDZ with the aromatic and aliphatic amines, respectively. The application of the defined combination of both spin labels (SL) to different soils well simulated a change of a paramagnetic signal of soil organic radicals interacted with SDZ. After their application to soil, SL were found in soil sites characterized

  14. Persistent free radical ESR signals in marine bivalve tissues

    SciTech Connect

    Mehlorn, R.J.; Mendez, A.T.; Higashi, R.; Fan, T.

    1992-08-01

    Freeze-dried homogenates of the oyster Crassostrea rhizophorae collected from waters in Puerto Rico near urban and industrial sites as well as at relatively pristine locations yielded electron spin resonance (ESR) spectra characteristic of free radicals as well as spectral components of transition metal ions, dominated by manganese. The magnitudes of these ESR signals and the concentrations of trace elements (determined by X-ray fluorescence) varied considerably among oyster samples, masking any potential correlation with polluted waters. Laboratory studies were initiated to identify the factors controlling the magnitudes of the tissue free radical ESR signals. Another mollusc, Mytilus californianus collected at the Bodega Marine laboratory in northern California, was fractionated into goneds and remaining tissue. Freeze-dried homogenates of both fractions exhibited ESR signals that increased gradually with time. ESR signals were observed in freeze-dried perchloric acid (PCA) precipitates of the homogenates, delipidated PCA precipitates, and in chloroform extracts of these precipitates. Acid hydrolysis to degrade proteins to amino acids produced a residue, which yielded much larger ESR free radical signals after freeze-drying. Freshly thawed homogenates of Crassostrea rhizophorae also exhibited ESR signals. A laboratory model of copper stress in Crassostrea rhizophorae was developed to study the effect of this transition metal on dssue free radicals. Preliminary results suggested that sublethal copper exposure had little effect on tissue fire radicals, except possibly for a signal enhancement in an oyster fraction that was enriched in kidney granules. Since kidney granules are known to accumulate heavy metals in mussels and probably other marine bivalves, this signal enhancement may prove to be an indicator of free radical processes associated with heavy metal deposition in molluscs.

  15. On Cu(II) Cu(II) distance measurements using pulsed electron electron double resonance

    NASA Astrophysics Data System (ADS)

    Yang, Zhongyu; Becker, James; Saxena, Sunil

    2007-10-01

    The effects of orientational selectivity on the 4-pulse electron electron double resonance (PELDOR) ESR spectra of coupled Cu(II)-Cu(II) spins are presented. The data were collected at four magnetic fields on a poly-proline peptide containing two Cu(II) centers. The Cu(II)-PELDOR spectra of this peptide do not change appreciably with magnetic field at X-band. The data were analyzed by adapting the theory of Maryasov, Tsvetkov, and Raap [A.G. Maryasov, Y.D. Tsvetkov, J. Raap, Weakly coupled radical pairs in solids:ELDOR in ESE structure studies, Appl. Magn. Reson. 14 (1998) 101-113]. Simulations indicate that orientational effects are important for Cu(II)-PELDOR. Based on simulations, the field-independence of the PELDOR data for this peptide is likely due to two effects. First, for this peptide, the Cu(II) g-tensor(s) are in a very specific orientation with respect to the interspin vector. Second, the flexibility of the peptide washes out the orientation effects. These effects reduce the suitability of the poly-proline based peptide as a good model system to experimentally probe orientational effects in such experiments. An average Cu(II)-Cu(II) distance of 2.1-2.2 nm was determined, which is consistent with earlier double quantum coherence ESR results.

  16. Photo-ESR and optical studies of Cr photoionization transition in CdZnSe:Cr crystals

    NASA Astrophysics Data System (ADS)

    Swiatek, K.; Godlewski, M.; Surkova, T. P.

    2004-02-01

    Photoionization transitions of chromium ions in CdxZn1-xSe:Cr bulk crystals (0 x 0.3) were studied in wide temperature range (4-300 K). By monitoring changes of the Cr1+ electron spin resonance signal under external illumination, we are able to determine energies of Cr2+ Cr1+ + hVB transition in different CdxZn1-xSe host crystals. At low temperature we observe metastable population of photo-excited Cr1+ centres.

  17. Reduction process of nitroxyl spin probes used in Overhauser-enhanced magnetic resonance imaging: An ESR study

    NASA Astrophysics Data System (ADS)

    Meenakumari, V.; Jawahar, A.; Premkumar, S.; Benial, A. Milton Franklin

    2016-05-01

    The Electron spin resonance studies on the reduction process of nitroxyl spin probes were carried out for 1mM 14N- labeled nitroxyl radicals in pure water and 1 mM concentration of ascorbic acid as a function of time. The electron spin resonance parameters, such as line width, hyperfine coupling constant, g-factor, signal intensity ratio and rotational correlation time were estimated. The 3-carbamoyl-PROXYL radical has narrowest line width and fast tumbling motion compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO, and 4-acetamido-TEMPO radicals. The half life time and decay rate were estimated for 1mM concentration of 14N- labeled nitroxyl radicals in 1 mM concentration of ascorbic acid. From the results, the 3-carbamoyl-PROXYL has long half life time and high stability compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO and 4-acetamido-TEMPO radicals. Therefore, this study reveals that the 3-carbamoyl-PROXYL radical can act as a good redox sensitive spin probe for Overhauser-enhanced Magnetic Resonance Imaging.

  18. Studies on spin-trapped radicals in. gamma. -irradiated aqueous L-valine solutions by high-performance liquid chromatography and ESR spectroscopy

    SciTech Connect

    Makino, K.

    1980-05-01

    Short-lived radicals produced in ..gamma..-irradiated aqueous L-valine solution were investigated by the method of spin trapping and subsequently by means of high-performance liquid chromatography combined with ESR spectroscopy. Four spin adducts due to L-valine could be identified. Among them, even the diastereoisomeric spin adducts due to L-valine could be separated. In addition, the effect of pH on the change in the spectra of the diastereoisomers is discussed.

  19. Synthesis, spectroscopic, anticancer and antibacterial studies of Ni(II) and Cu(II) complexes with 2-carboxybenzaldehyde thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Vandana

    2014-08-01

    Ni(II) and Cu(II) complexes of 2-carboxybenzaldehyde thiosemicarbazone (L) were synthesized and investigated by their spectral and analytical data. These newly synthesized complexes have a composition of M(L)X(H2O)2 (where M = Ni(II), Cu(II) and X = Cl-, NO3-, CH3COO-) and (L) is the tridentate Schiff base ligand. The ligand and its complexes have been characterized on the basis of analytical, molar conductivity, magnetic susceptibility measurements, FT-IR, ESR, 1H NMR and electronic spectral analysis. All the compounds were non-electrolytic in nature. On the basis of spectral studies an octahedral geometry has been assigned for Ni(II) and a tetragonal geometry for Cu(II) complexes. The ligand and its metal complexes were screened for their anticancer studies against human breast cancer cell lines MCF-7 and calculated minimum inhibitory concentration and also for antibacterial activity using Kirby-Bauer single disk susceptibility test.

  20. Limited Immersion in Cued Speech: A Case Study.

    ERIC Educational Resources Information Center

    Gordon, Malcolm; And Others

    The case study examines the effects on the receptive and expressive English language of a deaf 14 year old after a period of limited language immersion using Cued Speech, in which every sound in a word is represented both expressively and receptively. In a four week period the S spent approximately 14 hours per week with a modeler who cued speech…

  1. Strategy for finding new materials for ESR dosimeters

    PubMed

    Ikeya; Hassan; Sasaoka; Kinoshita; Takaki; Yamanaka

    2000-05-01

    The right strategy for finding a new ESR dosimetric material sensitive to radiation is to follow the orthodox procedures used in the development of thermoluminescence dosimeters (TLD) and phosphorescence studies. Modern procedures used in materials sciences, such as computer calculation of molecular orbitals (MO), should be employed to estimate the ESR and optical properties of prospective materials. Radiation effects in lithium and magnesium sulfates and metal salts of organic acids, such as lithium and magnesium lactates, have been investigated in search for tissue-equivalent dosimeter with a large G value.

  2. ESR

    MedlinePlus

    ... due to: Anemia Cancers such as lymphoma or multiple myeloma Kidney disease Pregnancy Thyroid disease The immune system ... Heart failure - overview Hypersensitivity vasculitis Macroglobulinemia of Waldenstrom Multiple ... vasculitis Polycythemia - newborn Polycythemia vera Polymyalgia ...

  3. Effect of Base Stacking on the Acid-Base Properties of the Adenine Cation Radical [A•+] in Solution: ESR and DFT Studies

    PubMed Central

    Adhikary, Amitava; Kumar, Anil; Khanduri, Deepti

    2015-01-01

    In this study, the acid–base properties of the adenine cation radical are investigated by means of experiment and theory. Adenine cation radical (A•+) is produced by one-electron oxidation of dAdo and of the stacked DNA-oligomer (dA)6 by Cl2•− in aqueous glass (7.5 M LiCl in H2O and in D2O) and investigated by ESR spectroscopy. Theoretical calculations and deuterium substitution at C8–H and N6–H in dAdo aid in our assignments of structure. We find the pKa value of A•+ in this system to be ca. 8 at 150 K in seeming contradiction to the accepted value of ≤ 1 at ambient temperature. However, upon thermal annealing to ≥160 K, complete deprotonation of A•+ occurs in dAdo in these glassy systems even at pH ca. 3. A•+ found in (dA)6 at 150 K also deprotonates on thermal annealing. The stability of A•+ at 150 K in these systems is attributed to charge delocalization between stacked bases. Theoretical calculations at various levels (DFT B3LYP/6-31G*, MPWB95, and HF-MP2) predict binding energies for the adenine stacked dimer cation radical of 12 to 16 kcal/mol. Further DFT B3LYP/6-31G* calculations predict that, in aqueous solution, monomeric A•+ should deprotonate spontaneously (a predicted pKa of ca. −0.3 for A•+). However, the charge resonance stabilized dimer AA•+ is predicted to result in a significant barrier to deprotonation and a calculated pKa of ca. 7 for the AA•+ dimer which is 7 pH units higher than the monomer. These theoretical and experimental results suggest that A•+ isolated in solution and A•+ in adenine stacks have highly differing acid–base properties resulting from the stabilization induced by hole delocalization within adenine stacks. PMID:18611019

  4. Studies on spin-trapped radicals in. gamma. -irradiated aqueous solutions of glycylglycine and glycyl-L-alanine by high-performance liquid chromatography and ESR spectroscopy

    SciTech Connect

    Moriya, F.; Makino, K.; Suzuki, N.; Rokushika, S.; Hatano, H.

    1980-12-25

    Aqueous solutions of glycylglycine and glycyl-L-alanine were ..gamma..-irradiated in the presence of a spin trap, 2-methyl-2-nitrosopropane. Stable spin adducts produced in the ..gamma..-irradiated solutions were analyzed by means of high-performance liquid chromatography and ESR spectroscopy. Five spin adducts were found and identified, as follows: t-BuN(O.)CH/sub 2/CONHCH/sub 2/COO/sup -/ (I) and NH/sub 3//sup +/CH/sub 2/CONHCH(COO/sup -/)N(O.)-t-Bu (IIb) from glycylglycine; t-BuN(O.)CH/sub 2/CONHCH(CH/sub 3/)COO/sup -/ (III), NH/sub 3//sup +/CH/sub 2/CONHC(CH/sub 3/)(COO/sup -/)N(O.)-t-Bu (IV) and NH/sub 3//sup +/CH/sub 2/CONHCH(COO/sup -/)CH/sub 2/N(O.)-t-Bu (V) from glycyl-L-alanine. It was found that spin adduct III exhibits ESR spectra with unequal splittings of the two ..beta.. hydrogens while spin adduct I does not. This fact revealed that the asymmetry of the delta carbon in spin adduct III causes the magnetic nonequivalence through a peptide bond. It was demonstrated that ESR spectra of spin adducts IIb and V changed remarkably with pH through the acid-dissociation equilibria of the carboxyl or amino groups. The pK/sub a/ values for the dissociation have been determined to be 2.0 for the carboxyl group of spin adduct IIb, and 3.0 for that of V.

  5. Electronic structures of CuTPP and CuTPP(F) complexes. A combined experimental and theoretical study I.

    PubMed

    Mangione, Giulia; Carlotto, Silvia; Sambi, Mauro; Ligorio, Giovanni; Timpel, Melanie; Vittadini, Andrea; Nardi, Marco Vittorio; Casarin, Maurizio

    2016-07-28

    Copper complexes of tetraphenylporphyrin (H2TPP) and tetrakis(pentafluorophenyl)porphyrin (H2TPP(F)) deposited as thin films on Au(111) have been studied experimentally and theoretically. Core level emissions from C 1s, N 1s, F 1s and Cu 2p as well as valence states of CuTPP and CuTPP(F) have been investigated using surface photoelectron spectroscopy. The interpretation of experimental results has been guided by theoretical calculations carried out on isolated species in the habit of the density functional theory. Reference to experimental and theoretical outcomes pertaining to H2TPP and H2TPP(F) allowed a confident and detailed assignment of the title molecules' X-ray and ultraviolet photoemission data. With specific reference to the latter, similar to copper phthalocyanine (CuPc), whose coordinative pocket mirrors the CuTPP/CuTPP(F) ones, the lowest ionization energy of the title compounds implies electron ejection from a ring orbital rather than from the Cu 3d-based singly occupied molecular orbital. Moreover, analogous to CuPc, the ionic contribution appears to play an important role in the Cu-N bonding. Nevertheless, differences in the number, symmetry, nature and relative position of CuTPP/CuTPP(F) occupied frontier orbitals compared to CuPc may be stated only by considering in great detail the Cu-ligand covalent interactions. PMID:27166746

  6. Synthesis, spectral characterization and thermal studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with 2-amino benzoic acid- and 2-hydroxy benzoic acid thiophen-2-ylmethylene hydrazide

    NASA Astrophysics Data System (ADS)

    Singh, Vinod P.; Singh, Pooja

    2013-03-01

    A series of metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) with 2-amino benzoic acid thiophen-2-ylmethylene hydrazide (Habth) and 2-hydroxy benzoic acid thiophen-2-ylmethylene hydrazide (Hhbth) have been synthesized. The complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, electronic, IR, NMR, ESR spectra and thermal studies (TGA and DTA). Molecular structure of the Habth ligand was determined by single crystal X-ray diffraction technique. Habth acts as a monobasic bidentate ligand in all its complexes bonding through a deprotonated Csbnd O- and lbond2 Cdbnd Nsbnd groups whereas, Hhbth acts as a monobasic bidentate in its Co(II) and Ni(II) complexes, bonding through a deprotonated Csbnd O- and lbond2 Cdbnd Nsbnd groups and as monobasic tridentate in Cu(II) and Zn(II) complexes bonding through lbond2 Cdbnd O, lbond2 Cdbnd Nsbnd and deprotonated (Csbnd O)- groups with the metal ion. Electronic spectra suggest a square planar geometry for Co(II), Ni(II) and Cu(II) complexes of Habth and Co(II) and Ni(II) complexes of Hhbth. However, the Cu(II) and Zn(II) complexes of Hhbth have octahedral geometry. The ESR spectra of Cu(II) complex of Hhbth in the solid state and in DMSO frozen solution show axial signals and suggest the presence of unpaired electron in d orbital of Cu(II). The Cu(II) complex of Habth in solid state shows isotropic signal, whereas, axial signal in DMSO frozen solution in the range of tetragonally distorted octahedral geometry due to interactions of DMSO molecules at axial positions. Thermal studies of some of the metal complexes show a multi-step decomposition pattern of bonded ligands in the complex.

  7. The Evaluation of IL6 and ESR1 Gene Polymorphisms in Primary Dysmenorrhea.

    PubMed

    Ozsoy, Asker Zeki; Karakus, Nevin; Yigit, Serbulent; Cakmak, Bulent; Nacar, Mehmet Can; Yılmaz Dogru, Hatice

    2016-01-01

    Primary dysmenorrhea is the most common gynecological complaint with painful menstrual cramps in pelvis without any pathology. It affects about half of menstruating women, and it causes significant disruption in quality of life. We investigated the association between IL6 gene promoter and ESR1 gene XbaI and PvuII polymorphisms and primary dysmenorrhea. In this case-control study, 152 unrelated young women with primary dysmenorrhea and 150 unrelated healthy age-matched controls participated. Genomic DNA was isolated and IL6 and ESR1 gene polymorphisms were genotyped using PCR-based RFLP assay. The distribution of genotype and allele frequencies of IL6 gene promoter and ESR1 gene XbaI polymorphisms were not statistically different between patients and controls (p > 0.05). However, the genotype and allele frequencies of ESR1 gene PvuII polymorphism showed statistically significant differences between primary dysmenorrhea patients and controls (p = 0.009 and p = 0.021, respectively). Statistically significant associations were also observed between age and married status of primary dysmenorrhea patients and ESR1 gene PvuII polymorphism (p = 0.044 and p = 0.023, respectively). In combined genotype analyses, AG at ESR1 XbaI and TC at ESR1 PvuII loci encoded a p-value of 0.027. Thus, individuals who are heterozygote at both loci have a lower risk of developing primary dysmenorrhea. Our study suggests no strong association between IL6 gene promoter and ESR1 gene XbaI polymorphisms and primary dysmenorrhea in Turkish women. However, ESR1 gene PvuII polymorphism showed statistically significant differences between primary dysmenorrhea patients and controls. The potential association between ESR1 gene PvuII polymorphism and age and married status of dysmenorrhea patients deserves further consideration.

  8. In situ TEM Studies of the Initial Oxidation stage of Cu and Cu Alloy Thin Films

    NASA Astrophysics Data System (ADS)

    Yang, Judith; Kang, Yihong; Luo, Langli; Ciston, James; Stach, Eric; Zhou, Guangwen

    2012-02-01

    The fundamental understanding of oxidation at the nanoscale is important for the environmental stability of coating materials as well as processing of oxide nanostructures. Our previous studies show the epitaxial growth of Cu2O islands during the initial stages of oxidation of Cu thin films, where surface diffusion and strain impact the oxide development and morphologies. The addition of secondary elements changes the oxidation mechanism. If the secondary element is non-oxidizing, such as Au, it will limit the Cu2O island growth due to the depletion of Cu near the oxide islands. When the secondary element is oxidizing, for example Ni, the alloy will show more complex behaviour, where duplex oxide islands were observed. Nucleation density and growth rate of oxide islands are observed under various temperatures and oxygen partial pressures (pO2) as a function of time by in situ ultra high vacuum (UHV)-transmission electron microscopy (TEM). Our initial results of Cu-Ni(001) oxidation is that the oxide epitaxy and morphologies change as function of Ni concentration. For higher spatial resolution, we are examining the atomic scale oxidation by aberration-corrected ETEM with 1å resolution.

  9. {beta}-decay study of {sup 77}Cu

    SciTech Connect

    Patronis, N.; De Witte, H.; Gorska, M.; Huyse, M.; Kruglov, K.; Pauwels, D.; Van de Vel, K.; Van Duppen, P.; Van Roosbroeck, J.; Thomas, J.-C.; Materna, T.; Mathieu, L.; Serot, O.

    2009-09-15

    A {beta}-decay study of {sup 77}Cu has been performed at the ISOLDE mass separator with the aim to deduce its {beta}-decay properties and to obtain spectroscopic information on {sup 77}Zn. Neutron-rich copper isotopes were produced by means of proton- or neutron-induced fission reactions on {sup 238}U. After the production, {sup 77}Cu was selectively laser ionized, mass separated, and sent to different detection systems where {beta}-{gamma} and {beta}-n coincidence data were collected. We report on the deduced half-live, decay scheme, and possible spin assignment of {sup 77}Cu.

  10. ESR technique for noninvasive way to quantify cyclodextrins effect on cell membranes

    SciTech Connect

    Grammenos, A.; Mouithys-Mickalad, A.; Guelluy, P.H.; Lismont, M.; Piel, G.; Hoebeke, M.

    2010-07-30

    Research highlights: {yields} ESR: a new tool for cyclodextrins study on living cells. {yields} Cholesterol and phospholipid extraction by Rameb in a dose- and time-dependent way. {yields} Extracted phospholipids and cholesterol form stable aggregates. {yields} ESR spectra show that lipid rafts are damaged by Rameb. {yields} Quantification of the cholesterol extraction on cell membranes in a noninvasive way. -- Abstract: A new way to study the action of cyclodextrin was developed to quantify the damage caused on cell membrane and lipid bilayer. The Electron Spin Resonance (ESR) spectroscopy was used to study the action of Randomly methylated-beta-cyclodextrin (Rameb) on living cells (HCT-116). The relative anisotropy observed in ESR spectrum of nitroxide spin probe (5-DSA and cholestane) is directly related to the rotational mobility of the probe, which can be further correlated with the microviscosity. The use of ESR probes clearly shows a close correlation between cholesterol contained in cells and cellular membrane microviscosity. This study also demonstrates the Rameb ability to extract cholesterol and phospholipids in time- and dose-dependent ways. In addition, ESR spectra enabled to establish that cholesterol is extracted from lipid rafts to form stable aggregates. The present work supports that ESR is an easy, reproducible and noninvasive technique to study the effect of cyclodextrins on cell membranes.

  11. The role of copper species on Cu/γ-Al2O3 catalysts for NH3-SCO reaction

    NASA Astrophysics Data System (ADS)

    Liang, Chunxia; Li, Xinyong; Qu, Zhenping; Tade, Moses; Liu, Shaomin

    2012-02-01

    UV-vis spectra, XRD, H2-TPR, TEM and ESR were used to characterize a series of Cu/γ-Al2O3 catalysts, which were prepared by incipient wetness impregnation using copper nitrate, copper acetate or copper sulfate as precursors, to study the role of Cu species on Cu/γ-Al2O3 catalysts for NH3-SCO reaction. It was found that the mixture of CuO phase and CuAl2O4 phase formed on various Cu/γ-Al2O3 catalysts, and the Cu species and dispersion had significant influence on the Cu/γ-Al2O3 activity. Highly dispersed CuO phase on the support would be related with its high activity for the NH3-SCO reaction.

  12. History of the youngest members of the Valles Rhyolite, Valles caldera, New Mexico using ESR dating method

    SciTech Connect

    Ogoh, K; Toyoda, S; Ikeda, S; Ikeya, M; Goff, F

    1991-01-01

    The cooling history of the Valles caldera was studied by the electron spin resonance (ESR) dating method using Al and Ti centers in quartz grains which were separated from the youngest units of the Valles Rhyolite. The ESR apparent ages are much younger than fission track ages and {sup 39}Ar- {sup 40}Ar ages. Three possibilities are suggested, the first is that the ESR ages are real, the second is that ESR method did not work for these samples, and the third is that about 10--40 ka, the signal intensity was partially reduced by a thermal event such as proposed by Harrison et al. (1986). Research on the first and second possibilities is continuing. The third possibility might explain the difference between ESR ages and those by other methods (fission track and {sup 39}Ar- {sup 40}Ar). ESR dating has produced new insights regarding the history of the Valles caldera.

  13. Adenine adlayers on Cu(111): XPS and NEXAFS study

    SciTech Connect

    Tsud, Nataliya; Bercha, Sofiia; Ševčíková, Klára; Matolín, Vladimír; Acres, Robert G.; Prince, Kevin C.

    2015-11-07

    The adsorption of adenine on Cu(111) was studied by photoelectron and near edge x-ray absorption fine structure spectroscopy. Disordered molecular films were deposited by means of physical vapor deposition on the substrate at room temperature. Adenine chemisorbs on the Cu(111) surface with strong rehybridization of the molecular orbitals and the Cu 3d states. Annealing at 150 °C caused the desorption of weakly bonded molecules accompanied by formation of a short-range ordered molecular adlayer. The interface is characterized by the formation of new states in the valence band at 1.5, 7, and 9 eV. The present work complements and refines existing knowledge of adenine interaction with this surface. The coverage is not the main parameter that defines the adenine geometry and adsorption properties on Cu(111). Excess thermal energy can further rearrange the molecular adlayer and, independent of the initial coverage, the flat lying stable molecular adlayer is formed.

  14. Study of thermal stability of Cu2Se thermoelectric material

    NASA Astrophysics Data System (ADS)

    Bohra, Anil; Bhatt, Ranu; Bhattacharya, Shovit; Basu, Ranita; Ahmad, Sajid; Singh, Ajay; Aswal, D. K.; Gupta, S. K.

    2016-05-01

    Sustainability of thermoelectric parameter in operating temperature range is a key consideration factor for fabricating thermoelectric generator or cooler. In present work, we have studied the stability of thermoelectric parameter of Cu2Se within the temperature range of 50-800°C. Temperature dependent Seebeck coefficients and electrical resistivity measurement are performed under three continuous thermal cycles. X-ray diffraction pattern shows the presence of mixed cubic-monoclinic Cu2Se phase in bare pellet which transforms to pure α-Cu2Se phase with repeating thermal cycle. Significant enhancement in Seebeck coefficient and electrical resistivity is observed which may be attributed to (i) Se loss observed in EDS and (ii) the phase transformation from mixed cubic-monoclinic structure to pure monoclinic α-Cu2Se phase.

  15. DNA CLEAVAGE AND DETECTION OF DNA RADICALS FORMED FROM HYDRALAZINE AND COPPER (II) BY ESR AND IMMUNO-SPIN TRAPPING

    PubMed Central

    Sinha, Birandra K.; Leinisch, Fabian; Bhattacharjee, Suchandra; Mason, Ronald P.

    2014-01-01

    Metal ion-catalyzed oxidation of hydrazine and its derivatives leads to the formation of the hydrazyl radical and subsequently to oxy-radicals in the presence of molecular oxygen. Here we have examined the role of Cu2+-catalyzed oxidation of hydralazine in the induction of DNA damage. Neither 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) nor dimethyl sulfoxide (DMSO) were effective in inhibiting hydralazine-Cu2+-induced DNA damage. Singlet oxygen did not appear to participate in this DNA cleavage. The one-electron oxidation of hydralazine also leads to the formation of DNA radicals as confirmed by immuno-spin trapping with 5, 5-dimethyl-1-pyrroline-N-oxide. Electron spin resonance (ESR) and spin trapping studies further confirmed the formation of DNA radicals; predominantly 2′-deoxyadenosine radical adducts were detected, while some radicals were also detected with other nucleosides. Our results suggest that free hydroxyl radicals may not be the main damaging species causing DNA cleavage, and possibly, Cu-peroxide complexes, formed from Cu+-H2O2, areresponsible for this hydralazine-Cu2+-induced DNA cleavage. PMID:24502259

  16. DNA cleavage and detection of DNA radicals formed from hydralazine and copper (II) by ESR and immuno-spin trapping.

    PubMed

    Sinha, Birandra K; Leinisch, Fabian; Bhattacharjee, Suchandra; Mason, Ronald P

    2014-04-21

    Metal ion-catalyzed oxidation of hydrazine and its derivatives leads to the formation of the hydrazyl radical and subsequently to oxy-radicals in the presence of molecular oxygen. Here, we have examined the role of Cu(2+)-catalyzed oxidation of hydralazine in the induction of DNA damage. Neither 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) nor dimethyl sulfoxide (DMSO) was effective in inhibiting hydralazine-Cu(2+)-induced DNA damage. Singlet oxygen did not appear to participate in this DNA cleavage. The one-electron oxidation of hydralazine also leads to the formation of DNA radicals as confirmed by immuno-spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide. Electron spin resonance (ESR) and spin-trapping studies further confirmed the formation of DNA radicals; predominantly, 2'-deoxyadenosine radical adducts were detected, while some radicals were also detected with other nucleosides. Our results suggest that free hydroxyl radicals may not be the main damaging species causing DNA cleavage and that possibly Cu-peroxide complexes, formed from Cu(+)-H2O2, are responsible for this hydralazine-Cu(2+)-induced DNA cleavage.

  17. Recent progress in in vivo ESR spectroscopy.

    PubMed

    Takeshita, Keizo; Ozawa, Toshihiko

    2004-09-01

    The generation of free radicals and redox status is related to various diseases and injuries that are related to radiation, aging, ischemia-reperfusion, and other oxidative factors. In vivo electron spin resonance (ESR) spectroscopy is noninvasive and detects durable free radicals in live animals. ESR spectrometers for in vivo measurements operate at a lower frequency (approximately 3.5 GHz, approximately 1 GHz, 700 MHz, and approximately 300 MHz) than usual (9-10 GHz). Several types of resonators have been designed to minimize the dielectric loss of electromagnetic waves caused by water in animal bodies. In vivo ESR spectroscopy and its imaging have been used to analyze radical generation, redox status, partial pressure of oxygen and other conditions in various disease and injury models related to oxidative stress with probes, such as nitroxyl radicals. Through these applications, the clarification of the mechanisms related to oxidative diseases (injuries) and the accumulation of basic data for radiological cancer therapy are now ongoing. In vivo ESR measurement is performed in about 10 laboratories worldwide, including ours. To introduce in vivo ESR spectroscopy to life scientists, this article reviews the recent progress of in vivo ESR spectroscopy in instrumentation and its application to the life sciences.

  18. Low Energy Dynamics in Spin-Liquid and Ordered Phases of S=1/2 Antiferromagnet Cs2CuCl4

    NASA Astrophysics Data System (ADS)

    Smirnov, A. I.; Povarov, K. Yu; Starykh, O. A.; Shapiro, A. Ya; Petrov, S. V.

    2012-12-01

    Cs2CuCl4 realizes spin-1/2 quantum antiferromagnet on a distorted triangular lattice. It remains in a quantum spin-liquid state far below Curie-Weiss temperature 4 K and exhibits an incommensurate spin ordering at TN=0.6 K. We studied Cs2CuCl4 by means of electron spin resonance (ESR) at temperatures down to 0.05 K in the frequency range 9ESR were found in the spin-liquid phase. We quantitatively describe both the shift and the splitting of the ESR line for different orientations of the applied magnetic field by accounting for the effect of a uniform Dzyaloshinskii-Moriya (DM) interaction on spinon excitations of weakly coupled Heisenberg chains. At cooling below TN, we observe at lower frequency f<40 GHz a gradual crossover of the signal from the above spinon-type ESR toward a resonance of a spiral-AFM type. However, for higher frequency f>60 GHz, we observe that the above spinon-type ESR survives deep in the ordered phase. These novel phenomena are consequences of fractionalized spinon excitations of spin chains, which are effectively decoupled in Cs2CuCl4 due to strong geometric frustration.

  19. Multilocus analysis of estrogen-related genes in Spanish postmenopausal women suggests an interactive role of ESR1, ESR2 and NRIP1 genes in the pathogenesis of osteoporosis.

    PubMed

    Morón, Francisco Jesús; Mendoza, Nicolás; Vázquez, Francisco; Molero, Eva; Quereda, Francisco; Salinas, Ana; Fontes, Juan; Martínez-Astorquiza, Txantón; Sánchez-Borrego, Rafael; Ruiz, Agustín

    2006-07-01

    Osteoporosis is a common disease with multiple environmental and genetic risk factors involved. Using a marker-by-marker approach, the role of different estrogen-related genes has been analyzed in different populations, but most of these studies ignore the complex multigenic nature of human osteoporosis. Looking for markers related to osteoporosis, we have analyzed five single nucleotide polymorphisms located in genes related to the estrogen pathway, Follicle Stimulating Hormone Receptor (FSHR) gene, the CYP19 aromatase (CYP19A1) gene, the Estrogen Receptor alpha (ESR1) gene, the Estrogen Receptor beta (ESR2) gene and the Nuclear Receptor Interacting Protein 1 (NRIP1) gene in 265 unrelated postmenopausal women. We have obtained nominal P values for the NRIP1 Gly75Gly and ESR2 *39A>G markers (P=0.013 and P=0.02 respectively), but no gene seems to be associated after multiple test corrections. Reanalysis of this study using 437 postmenopausal women confirmed our results and only detect marginal effects for ESR2 marker (P=0.045). By contrast, multilocus analysis predicted epistatic interactions between ESR1, ESR2 and NRIP1 loci and its involvement in postmenopausal osteoporosis (P=0.003). We detected two digenic genotypes involving ESR2-NRIP1 and ESR2-ESR1 genes strongly associated with osteoporosis (P=0.007). Replication of multilocus studies using 437 patients confirmed the detected interactions (P<0.01). We proposed a non-additive non-multiplicative oligogenic model including ESR2 AG genotype modulated by NRIP1 A+ or ESR1 TT genotypes involved in osteoporosis. Our results reaffirm the polygenic nature and the genetic complexity of osteoporosis trait adding a new candidate gene (NRIP1) for association studies of bone-related traits.

  20. Novel copper (Cu) loaded core-shell silica nanoparticles with improved Cu bioavailability: synthesis, characterization and study of antibacterial properties.

    PubMed

    Maniprasad, Pavithra; Santra, Swadeshmukul

    2012-08-01

    We report synthesis of a novel core-shell silica based antimicrobial nanoparticles where the silica shell has been engineered to accommodate copper (Cu). Synthesis of the core-shell Cu-silica nanoparticle (C-S CuSiO2NP) involves preparation of base-hydrolyzed Stöber silica "seed" particles first, followed by the acid-catalyzed seeded growth of the Cu-silica shell layer around the core. The Scanning Electron Microscopy (SEM) and the Transmission Electron Microscopy (TEM) measured the seed particle size to be -380 nm and the shell thickness to be -35 nm. The SEM particle characterization confirms formation of highly monodispersed particles with smooth surface morphology. Characterization of particle size distribution in solution by Dynamic Light Scattering (DLS) technique was fairly consistent with the electron microscopy results. Loading of Cu to nanoparticles was confirmed by the SEM-Energy Dispersive X-Ray Spectroscopy (EDS) and Atomic Absorption Spectroscopy (AAS). The Cu loading was estimated to be 0.098 microg of metallic copper per mg of C-S CuSiO2NP material by the AAS technique. Antibacterial efficacy of C-S CuSiO2NP was evaluated against E. coli and B. subtilis using Cu hydroxide ("Insoluble" Cu compound, sub-micron size particles) as positive control and silica "seed" particles (without Cu loading) as negative control. Bacterial growth in solution was measured against different concentrations of C-S CuSiO2NP to determine the Minimum Inhibitory Concentration (MIC) value. The estimated MIC values were 2.4 microg metallic Cu/mL for both E. coli and B. subtilis. Bac-light fluorescence microscopy based assay was used to count relative population of the live and dead bacteria cells. Antibacterial study clearly shows that C-S CuSiO2NP is more effective than insoluble Cu hydroxide particles at equivalent metallic Cu concentration, suggesting improvement of Cu bioavailability (i.e., more soluble Cu) in C-SCuSiO2NP material due to its core-shell design. PMID

  1. ESR study of the electronic structures of metallofullerenes. A comparison between La C[sub 82] and Sc C[sub 82

    SciTech Connect

    Kato, Tatsuhisa ); Suzuki, Shinzo; Kikuchi, Koichi; Achiba, Yohji )

    1993-12-23

    The line widths of the hyperfine components of ESR spectra of La C[sub 82] and Sc C[sub 82] in CS[sub 2] and toluene solutions have been measured as a function of temperature. The extent of line broadening due not only to the insufficient rotational averaging of g and hyperfine tensors but also to the spin-rotation coupling interaction have been determined. The values of anisotropy for the g and hyperfine tensors are deduced by analysis according to Kivelson's formalism for these line broadening mechanisms. Although the two spectra for La C[sub 82] and Sc C[sub 82] in solution at room temperature look similar to each other, the different electronic structure for each endohedral metal is reflected in their differing values for the anisotropy of the g and hyperfine tensors. The electronic structures of La C[sub 82] and Sc C[sub 82] are discussed comparatively in terms of a theoretical interpretation for the anisotropic correction of the g factor and the hyperfine coupling constant. The results exhibit different electronic structures for La C[sub 82] and Sc C[sub 82]; the radical electron is assigned to a [pi] orbital of the C[sub 82] cage for La C[sub 82] but to a orbital of the metal for Sc C[sub 82]. 16 refs., 4 figs., 1 tab.

  2. Light-Induced ESR Studies of Quadrimolecular Recombination Kinetics of Photogenerated Charge Carriers in Regioregular Poly(3-alkylthiophene)/C60 Composites: Alkyl Chain Dependence

    NASA Astrophysics Data System (ADS)

    Tanaka, Hisaaki; Hasegawa, Naoki; Sakamoto, Tomotaka; Marumoto, Kazuhiro; Kuroda, Shin-ichi

    2007-08-01

    Light-induced ESR (LESR) measurements have been performed on the composites of regioregular poly(3-alkylthiophene) (RR-P3AT) and C60 by using polymers having different alkyl chains (CmH2m+1 with m=6, 8, 10, 12). The quadrimolecular recombination (QR) kinetics of photogenerated charge carriers, previously reported, have been confirmed for all the composites from the excitation power (Iex) dependence of the LESR intensity showing an ˜Iex0.25 dependence. The time decay of LESR intensity is also consistent with the QR model. Considering that only bimolecular recombination is observed in regiorandom polymer composites, the occurrence of QR strongly suggests the formation of doubly charged states, either bipolarons or polaron pairs on the regioregular polymer chains. On the other hand, the QR rate constant γ has been found to exhibit weak alkyl chain dependence, contrary to the case of the field-effect mobility of pure regioregular polymers with systematic alkyl chain dependence. This implies the significant contribution of the polymer and fullerene interface in determining γ.

  3. Estrogen Receptor Alpha (ESR1)-Dependent Regulation of the Mouse Oviductal Transcriptome.

    PubMed

    Cerny, Katheryn L; Ribeiro, Rosanne A C; Jeoung, Myoungkun; Ko, CheMyong; Bridges, Phillip J

    2016-01-01

    Estrogen receptor-α (ESR1) is an important transcriptional regulator in the mammalian oviduct, however ESR1-dependent regulation of the transcriptome of this organ is not well defined, especially at the genomic level. The objective of this study was therefore to investigate estradiol- and ESR1-dependent regulation of the transcriptome of the oviduct using transgenic mice, both with (ESR1KO) and without (wild-type, WT) a global deletion of ESR1. Oviducts were collected from ESR1KO and WT littermates at 23 days of age, or ESR1KO and WT mice were treated with 5 IU PMSG to stimulate follicular development and the production of ovarian estradiol, and the oviducts collected 48 h later. RNA extracted from whole oviducts was hybridized to Affymetrix Genechip Mouse Genome 430-2.0 arrays (n = 3 arrays per genotype and treatment) or reverse transcribed to cDNA for analysis of the expression of selected mRNAs by real-time PCR. Following microarray analysis, a statistical two-way ANOVA and pairwise comparison (LSD test) revealed 2428 differentially expressed transcripts (DEG's, P < 0.01). Genotype affected the expression of 2215 genes, treatment (PMSG) affected the expression of 465 genes, and genotype x treatment affected the expression of 438 genes. With the goal of determining estradiol/ESR1-regulated function, gene ontology (GO) and bioinformatic pathway analyses were performed on DEG's in the oviducts of PMSG-treated ESR1KO versus PMSG-treated WT mice. Significantly enriched GO molecular function categories included binding and catalytic activity. Significantly enriched GO cellular component categories indicated the extracellular region. Significantly enriched GO biological process categories involved a single organism, modulation of a measurable attribute and developmental processes. Bioinformatic analysis revealed ESR1-regulation of the immune response within the oviduct as the primary canonical pathway. In summary, a transcriptomal profile of estradiol- and ESR1

  4. Synthesis, characterization, in vitro antimicrobial and DNA cleavage studies of Co(II), Ni(II) and Cu(II) complexes with ONOO donor coumarin Schiff bases

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Unki, Shrishila N.; Kulkarni, Ajaykumar D.; Naik, Vinod H.; Badami, Prema S.

    2011-01-01

    A series of Co(II), Ni(II) and Cu(II) complexes have been synthesized with Schiff bases derived from 2-hydroxy-1-naphthaldehyde and 2-oxo-2H-chromene-3-carbohydrazide/6-bromo-2-oxo-2H-chromene-3-carbohydrazide. The chelation of the complexes has been proposed in the light of analytical, spectral (IR, UV-Vis, 1H NMR, ESR, FAB-mass and fluorescence), magnetic and thermal studies. The measured molar conductance values indicate that, the complexes are non-electrolytic in nature. The redox behavior of the complexes was investigated with electrochemical method by using cyclic voltammetry. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial ( Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal activities ( Candida albicans, Cladosporium and Aspergillus niger) by MIC method. The DNA cleavage is studied by agarose gel electrophoresis method.

  5. The ESR dosimetric features of strontium sulfate and temperature effects on radiation-induced signals

    NASA Astrophysics Data System (ADS)

    Acar, Ali Osman; Polat, Mustafa; Aydin, Talat; Aydaş, Canan

    2016-06-01

    In the present work, the ESR dosimetric potential of strontium sulfate has been investigated in the radiation dose range of 1-100 Gy. It does not exhibit any ESR signal before irradiation. However, irradiation produced three intensive resonance signals (A, B and C) which increase linearly in the studied dose range. Variable temperature study showed that all ESR signals were found to decrease significantly at temperatures higher than 340 K. Kinetic studies performed at high temperatures showed that at least two distinct radical species with the activation energy values of 42.8±3.6 and 88.2±5.8 kJ/mol, respectively, contributed to the ESR signal B.

  6. 19F NMR-, ESR-, and vis-NIR-spectroelectrochemical study of the unconventional reduction behaviour of a perfluoroalkylated fullerene: dimerization of the C70(CF3)10– radical anion†

    PubMed Central

    Zalibera, Michal; Machata, Peter; Clikeman, Tyler T.; Rosenkranz, Marco; Strauss, Steven H.; Boltalina, Olga V.; Popov, Alexey A.

    2016-01-01

    The most abundant isomer of C70(CF3)10 (70-10-1) is a rare example of a perfluoroalkylated fullerene exhibiting electrochemically irreversible reduction. We show that electrochemical reversibility at the first reduction step is achieved at scan rates higher than 500 V s-1 Applying ESR-, vis-NIR-, and 19F NMR- spectroelectrochemistry, as well as mass spectrometry and DFT calculations, we show that the (70-10-1)- radical monoanion is in equilibrium with a singly-bonded diamagnetic dimeric dianion. This study is the first example of 19F NMR spectroelectrochemistry, which promises to be an important method for the elucidation of redox mechanisms of fluoroorganic compounds. Additionally, we demonstrate the importance of combining different spectroelectrochemical methods and quantitative analysis of the transferred charge and spin numbers in the determination of the redox mechanism. PMID:26359514

  7. Identification of irradiated sage tea ( Salvia officinalis L.) by ESR spectroscopy

    NASA Astrophysics Data System (ADS)

    Tepe Çam, Semra; Engin, Birol

    2010-04-01

    The use of electron spin resonance (ESR) spectroscopy to accurately distinguish irradiated from unirradiated sage tea was examined. Before irradiation, sage tea samples exhibit one asymmetric singlet ESR signal centered at g=2.0037. Besides this central signal, two weak satellite signals situated about 3 mT left and right to it in radiation-induced spectra. Irradiation with increasing doses caused a significant increase in radiation-induced ESR signal intensity at g=2.0265 (the left satellite signal) and this increase was found to be explained by a polynomial varying function. The stability of that radiation-induced ESR signal at room temperature was studied over a storage period of 9 months. Also, the kinetic of signal at g=2.0265 was studied in detail over a temperature range 313-353 K by annealing samples at different temperatures for various times.

  8. Thermodynamic Study on YBa2Cu3C7-x

    NASA Astrophysics Data System (ADS)

    Toci, F.; Schuerenkaemper, A.; Toussaint, N.; Cambini, M.; Manes, L.

    Results are related to ordering of oxygen vacancies in the YBa2Cu3O7-x lattice. The concentration and ordering of oxygen in the lattice of YBa2Cu3O7-x are fundamental for its superconducting properties. Partial free energies, enthalpies and entropies of YBa2Cu3O7-x have been obtained from oxygen standard potential measurements performed between 700 and 1100 K, by means of a miniaturized solid state galvanic cell. The oxygen molar content of the phases investigated was between 6.65 and 6.95. Oxygen diffusion kinetics was also studied by means of the same apparatus, by following the depolarization of the electrode after a coulometric titration. Structural characterization was performed by X-ray powder diffraction, metallography and scanning electron microscopy.

  9. Structural and optical studies of CuO nanostructures

    SciTech Connect

    Chand, Prakash Gaur, Anurag Kumar, Ashavani

    2014-04-24

    In the present study, copper oxide (CuO) nanostructures have been synthesized at 140 °C for different aging periods, 1, 24, 48 and 96 hrs by hydrothermal method to investigate their effects on structural and optical properties. The X-ray diffractometer (XRD) pattern indicates the pure phase formation of CuO and the particle size, calculated from XRD data, has been found to be increasing from 21 to 36 nm for the samples synthesized at different aging periods. Field emission scanning electron microscope (FESEM) analysis also shows that the average diameter and length of these rectangular nano flakes increases with increasing the aging periods. Moreover Raman spectrums also confirm the phase formation of CuO. The optical band gaps calculated through UV-visible spectroscopy are found to be decreasing from 2.92 to 2.69 eV with increase in aging periods, 1 to 96 hrs, respectively.

  10. ESR1 and ESR2 differentially regulate daily and circadian activity rhythms in female mice.

    PubMed

    Royston, S E; Yasui, N; Kondilis, A G; Lord, S V; Katzenellenbogen, J A; Mahoney, M M

    2014-07-01

    Estrogenic signaling shapes and modifies daily and circadian rhythms, the disruption of which has been implicated in psychiatric, neurologic, cardiovascular, and metabolic disease, among others. However, the activational mechanisms contributing to these effects remain poorly characterized. To determine the activational impact of estrogen on daily behavior patterns and differentiate between the contributions of the estrogen receptors ESR1 and ESR2, ovariectomized adult female mice were administered estradiol, the ESR1 agonist propylpyrazole triol, the ESR2 agonist diarylpropionitrile, or cholesterol (control). Animals were singly housed with running wheels in a 12-hour light, 12-hour dark cycle or total darkness. Estradiol increased total activity and amplitude, consolidated activity to the dark phase, delayed the time of peak activity (acrophase of wheel running), advanced the time of activity onset, and shortened the free running period (τ), but did not alter the duration of activity (α). Importantly, activation of ESR1 or ESR2 differentially impacted daily and circadian rhythms. ESR1 stimulation increased total wheel running and amplitude and reduced the proportion of activity in the light vs the dark. Conversely, ESR2 activation modified the distribution of activity across the day, delayed acrophase of wheel running, and advanced the time of activity onset. Interestingly, τ was shortened by estradiol or either estrogen receptor agonist. Finally, estradiol-treated animals administered a light pulse in the early subjective night, but no other time, had an attenuated response compared with controls. This decreased phase response was mirrored by animals treated with diarylpropionitrile, but not propylpyrazole triol. To conclude, estradiol has strong activational effects on the temporal patterning and expression of daily and circadian behavior, and these effects are due to distinct mechanisms elicited by ESR1 and ESR2 activation.

  11. Electronic structure of CuTPP and CuTPP(F) complexes: a combined experimental and theoretical study II.

    PubMed

    Mangione, Giulia; Sambi, Mauro; Carlotto, Silvia; Vittadini, Andrea; Ligorio, Giovanni; Timpel, Melanie; Pasquali, Luca; Giglia, Angelo; Nardi, Marco Vittorio; Casarin, Maurizio

    2016-09-28

    The unoccupied electronic structure of thick films of tetraphenylporphyrin and tetrakis(pentafluorophenyl)porphyrin Cu(ii) complexes (hereafter, CuTPP and CuTPP(F)) deposited on Au(111) has been studied by combining the outcomes of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy with those of spin-unrestricted time-dependent density functional (TD-DFT) calculations carried out either within the scalar relativistic zeroth order regular approximation (ZORA) framework (C, N and F K-edges) or by using the Tamm-Dancoff approximation coupled to ZORA and including spin-orbit effects (Cu L2,3-edges). Similarly to the modelling of NEXAFS outcomes pertaining to other Cu(ii) complexes, the agreement between theory and experiment is more than satisfactory, thus confirming the open-shell TD-DFT to be a useful tool to look into NEXAFS results pertinent to Cu(ii) compounds. The combined effect of metalation and phenyl (Ph) fluorine decoration is found to favour an extensive mixing between (Ph)σ* and pristine porphyrin macrocyle (pmc) (pmc)π* virtual levels. The lowest lying excitation in the C and N K-edge spectra of both CuTPP and CuTPP(F) is associated with a ligand-to-metal-charge-transfer transition, unambiguously revealed in the (CuTPP)N K-edge spectral pattern. Moreover, the comparison with literature data pertaining to the modelling of the (Cu(II))L2,3 features in the phthalocyanine-Cu(ii) (CuPc) complex provided further insights into how metal-to-ligand-charge-transfer transitions associated with excitations from 2p(Cu(II)) AOs to low-lying, ligand-based π* MOs may contribute to the Cu(ii) L2,3-edge intensity and thus weaken its believed relationship with the Cu(ii)-ligand symmetry-restricted covalency. Despite the coordinative pocket of CuTPP/CuTPP(F) mirroring CuPc, the ligand-field strength exerted by the phthalocyanine ligand on the Cu(ii) centre is experimentally found and theoretically confirmed to be slightly stronger than that experienced by Cu

  12. Study of a splat cooled Cu-Zr-noncrystalline phase.

    NASA Technical Reports Server (NTRS)

    Revcolevschi, A.; Grant, N. J.

    1972-01-01

    By rapid quenching from the melt, using the splat forming gun technique, a noncrystalline phase has been obtained in a Cu-Zr alloy containing 60 at. % Cu. Upon heating, rapid crystallization of the samples takes place at 477 C with a heat release of about 700 cal per mol. The variation of the electrical resistivity of the samples with temperature confirms the transformation. Very high resolution electron microscopy studies of the structural changes of the samples upon heating are presented and show the gradual crystallization of the amorphous structure.

  13. An attempt to model electrode change during the ESR process

    NASA Astrophysics Data System (ADS)

    Karimi-Sibaki, E.; Kharicha, A.; Wu, M.; Ludwig, A.; Holzgruber, H.; Ofner, B.; Scheriau, A.; Kubin, M.; Ramprecht, M.

    2016-07-01

    The electrode change technology is used to produce very large heavy ingots in which a number of electrodes are remelted one after another during the ESR process. Preparing the new electrode for remelting requires a certain period of time when the electric current is stopped (power off). Here, CFD simulation is used to study the behavior of a large scale ESR process during the electrode change (power off). Firstly, the electromagnetic, temperature, and turbulent flow fields in the process before electrode change are modelled. Mold current and thermal effect due to shrinkage of ingot is considered in the model. Then, a transient simulation is performed and the response of the system to the power off is continuously tracked. It is observed that the pool profile of ingot is preserved before and after electrode change. Details of the flow and temperature distributions during electrode change are presented in the paper.

  14. Detection of irradiated chicken by ESR spectroscopy of bone

    NASA Astrophysics Data System (ADS)

    Duarte, C. L.; Villavicencio, A. L. C. H.; Del Mastro, N. L.; Wiendl, F. M.

    1995-02-01

    Ionizing radiation has been used to treat poultry to remove harmful microorganisms, mainly Salmonella, which contaminates chicken, goose and other fresh and frozen poultry. This microorganism is sensitive to low dose radiation. Thus, irradiating these foods with doses between 1 to 7 kGy results in a large reduction of bacteria. Since it is necessary to determine whether irradiation has occurred and to what extend, this work studied the signal produced by ionizing radiation within the hard crystalline matrix of chicken's bone to establish a control method. Chicken's drumsticks were irradiated and bones separated from flesh were lyophilized and milled. ESR spectrum was then obtained. The ESR signal increased linearly with dose over the range 0.25 to 8.0 kGy. Free radicals evaluated during 30 days after irradiation showed stable in this period.

  15. Temperature- and gaseous phase-mediated reorganization and paramagnetic doping of solid aluminum fluorides: ESR and ab initio quantum chemical studies

    SciTech Connect

    Scholz, G.

    1998-08-01

    Based on cw-X-band ESR spectroscopic measurements of Mn{sup 2+} doped AlF{sub 3} powder samples and DFT (B3LYP)/6-31+G{sup *} quantum chemical calculations it is shown that structural reorganization of AlF{sub 3} (AlF{sub 3} (amorphous) {yields} AlF{sub 3} (crystalline)) are necessarily assisted by chemical reactions with the precipitation of water. It could be unambiguously demonstrated that Mn{sup 2+} ions are suitable spin probes for reorganization processes from amorphous to local crystalline regions in fluoride matrices. The resolution of the {sup 55}Mn-{sup 19}F- superhyperfine structure (both the formation of regular MnF{sub 6}{sup 4{minus}}-species as well as the reduction of strain effects by transformation of the amorphous parts) is a sensitive indicator of the formation of local crystalline regions. DFT(B3LYP)/6-31+G{sup *} calculations of (AlF{sub 3}){sub n}(H{sub 2}O){sub m} complexes (n: 1,2; m: 1--3) resulted in first and acceptable ideas of structures, energetical stabilities, and vibrational frequencies of hydrated AlF{sub 3}. The calculated strength of the Al-O bond, resulting in the stable {l_brace}AlF{sub 3}-OH{sub 2}{r_brace} subunit, and the favored splitting of Al-F-Al bonds by H{sub 2}O molecules, are the main reasons for the immediate and spontaneous hydration of freshly prepared amorphous AlF{sub 3}. Independent of the size of the model complexes, stable substructures like {l_brace}AlF{sub 3}-H{sub 2}O{r_brace} and {l_brace}F{sub 3}AlFAlF{sub 2}-OH{sub 2}{r_brace} can be recognized in all optimized structure models.

  16. Transient melting of an ESR electrode

    NASA Astrophysics Data System (ADS)

    Kharicha, A.; Karimi-Sibaki, E.; Bohacek, J.; Wu, M.; Ludwig, A.

    2016-07-01

    Melting parameters of ESR process such as melt rate and immersion depth of electrode are of great importance. In this paper, a dynamic mesh based simulation framework is proposed to model melt rate and shape of electrode during the ESR process. Coupling interactions between turbulent flow, temperature, and electromagnetic fields are fully considered. The model is computationally efficient, and enables us to directly calculate melting parameters. Furthermore, dynamic change of electrode shape by melting can be captured. It is necessary to control the feeding velocity of electrode due to melting instabilities in the ESR process. As such, a numerical control is implemented based on the immersion depth of electrode to achieve the steady state in the simulation. Furthermore, the modeling result is evaluated against an experiment.

  17. Synthesis, characterization and in vitro antimicrobial studies of Co(II), Ni(II) and Cu(II) complexes derived from macrocyclic compartmental ligand

    NASA Astrophysics Data System (ADS)

    El-Gammal, O. A.; Bekheit, M. M.; El-Brashy, S. A.

    2015-02-01

    New Co(II), Ni(II) and Cu(II) complexes derived from tetradentate macrocyclic nitrogen ligand, (1E,4E,8E,12E)-5,8,13,16-tetramethyl-1,4,9,12-tetrazacyclohexadeca-4,8,12,16-tetraene (EDHDH) have been synthesized. The complexes have been characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR and ESR (for Cu(II) complex)) mass, and magnetic as well as thermal analysis measurements. The complexes afforded the formulae: [Cu(EDHDH)Cl2]·2EtOH and [M(EDHDH)X2]·nH2O where M = Co(II) and Ni(II), X = Cl- or OH-, n = 1,0, respectively. The data revealed an octahedral arrangement with N4 tetradentate donor sites in addition to two Cl atoms occupying the other two sites. ESR spectrum of Cu2+ complex confirmed the suggested geometry with values of a α2and β2 indicating that the in-plane σ-bonding and in-plane π-bonding are appreciably covalent, and are consistent with very strong σ-in-plane bonding in the complexes. The molecular modeling is drawn and showed the bond length, bond angle, chemical reactivity, energy components (kcal/mol) and binding energy (kcal/mol) for all the title compounds using DFT method. Also, the thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. Moreover, the in vitro antibacterial studies of all compounds screened against pathogenic bacteria (two Gram +ve and two Gram -ve) to assess their inhibiting potential. The assay indicated that the inhibition potential is metal ion dependent. The ligand, EDHDH, Co(II) and Cu(II) complexes exhibited a remarkable antibacterial activity against Streptococcus Pyogenes as Gram +ve and Proteus vulgaris as Gram -ve bacterial strains. On the other hand, Ni(II) complex revealed a moderate antibacterial activity against both Gram +ve organisms and no activity against Gram -ve bacterial strain.

  18. Synthesis, characterization and in vitro antimicrobial studies of Co(II), Ni(II) and Cu(II) complexes derived from macrocyclic compartmental ligand.

    PubMed

    El-Gammal, O A; Bekheit, M M; El-Brashy, S A

    2015-02-25

    New Co(II), Ni(II) and Cu(II) complexes derived from tetradentate macrocyclic nitrogen ligand, (1E,4E,8E,12E)-5,8,13,16-tetramethyl-1,4,9,12-tetrazacyclohexadeca-4,8,12,16-tetraene (EDHDH) have been synthesized. The complexes have been characterized by elemental analysis, spectral (IR, UV-Vis, (1)H NMR and ESR (for Cu(II) complex)) mass, and magnetic as well as thermal analysis measurements. The complexes afforded the formulae: [Cu(EDHDH)Cl2]·2EtOH and [M(EDHDH)X2]·nH2O where M=Co(II) and Ni(II), X=Cl(-) or OH(-), n=1,0, respectively. The data revealed an octahedral arrangement with N4 tetradentate donor sites in addition to two Cl atoms occupying the other two sites. ESR spectrum of Cu(2+) complex confirmed the suggested geometry with values of a α(2)and β(2) indicating that the in-plane σ-bonding and in-plane π-bonding are appreciably covalent, and are consistent with very strong σ-in-plane bonding in the complexes. The molecular modeling is drawn and showed the bond length, bond angle, chemical reactivity, energy components (kcal/mol) and binding energy (kcal/mol) for all the title compounds using DFT method. Also, the thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. Moreover, the in vitro antibacterial studies of all compounds screened against pathogenic bacteria (two Gram +ve and two Gram -ve) to assess their inhibiting potential. The assay indicated that the inhibition potential is metal ion dependent. The ligand, EDHDH, Co(II) and Cu(II) complexes exhibited a remarkable antibacterial activity against Streptococcus Pyogenes as Gram +ve and Proteus vulgaris as Gram -ve bacterial strains. On the other hand, Ni(II) complex revealed a moderate antibacterial activity against both Gram +ve organisms and no activity against Gram -ve bacterial strain.

  19. Synthesis, characterization and in vitro antimicrobial studies of Co(II), Ni(II) and Cu(II) complexes derived from macrocyclic compartmental ligand.

    PubMed

    El-Gammal, O A; Bekheit, M M; El-Brashy, S A

    2015-02-25

    New Co(II), Ni(II) and Cu(II) complexes derived from tetradentate macrocyclic nitrogen ligand, (1E,4E,8E,12E)-5,8,13,16-tetramethyl-1,4,9,12-tetrazacyclohexadeca-4,8,12,16-tetraene (EDHDH) have been synthesized. The complexes have been characterized by elemental analysis, spectral (IR, UV-Vis, (1)H NMR and ESR (for Cu(II) complex)) mass, and magnetic as well as thermal analysis measurements. The complexes afforded the formulae: [Cu(EDHDH)Cl2]·2EtOH and [M(EDHDH)X2]·nH2O where M=Co(II) and Ni(II), X=Cl(-) or OH(-), n=1,0, respectively. The data revealed an octahedral arrangement with N4 tetradentate donor sites in addition to two Cl atoms occupying the other two sites. ESR spectrum of Cu(2+) complex confirmed the suggested geometry with values of a α(2)and β(2) indicating that the in-plane σ-bonding and in-plane π-bonding are appreciably covalent, and are consistent with very strong σ-in-plane bonding in the complexes. The molecular modeling is drawn and showed the bond length, bond angle, chemical reactivity, energy components (kcal/mol) and binding energy (kcal/mol) for all the title compounds using DFT method. Also, the thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. Moreover, the in vitro antibacterial studies of all compounds screened against pathogenic bacteria (two Gram +ve and two Gram -ve) to assess their inhibiting potential. The assay indicated that the inhibition potential is metal ion dependent. The ligand, EDHDH, Co(II) and Cu(II) complexes exhibited a remarkable antibacterial activity against Streptococcus Pyogenes as Gram +ve and Proteus vulgaris as Gram -ve bacterial strains. On the other hand, Ni(II) complex revealed a moderate antibacterial activity against both Gram +ve organisms and no activity against Gram -ve bacterial strain. PMID:25218230

  20. Numerical study of the enhancement of heat transfer for hybrid CuO-Cu Nanofluids flowing in a circular pipe.

    PubMed

    Balla, Hyder H; Abdullah, Shahrir; Mohdfaizal, Wan; Zulkifli, Rozli; Sopian, Kamaruzaman

    2013-01-01

    A numerical simulation model for laminar flow of nanofluids in a pipe with constant heat flux on the wall was built to study the effect of the Reynolds number on convective heat transfer and pressure loss. The investigation was performed for hybrid nanofluids consisting of CuO-Cu nanoparticles and compared with CuO and Cu in which the nanoparticles have a spherical shape with size 50, 50, 50nm respectively. The nanofluids were prepared, following which the thermal conductivity and dynamic viscosity were measured for a range of temperatures (10 -60°C). The numerical results obtained were compared with the existing well-established correlation. The prediction of the Nusselt number for nanofluids agrees well with the Shah correlation. The comparison of heat transfer coefficients for CuO, Cu and CuO-Cu presented an increase in thermal conductivity of the nanofluid as the convective heat transfer coefficient increased. It was found that the pressure loss increases with an increase in the Reynolds number, nanoparticle density and particle volume fraction. However, the flow demonstrates enhancement in heat transfer which becomes greater with an increase in the Reynolds number for the nanofluid flow.

  1. Cu doped ZnO pellets: study of structure and Cu specific magnetic properties.

    PubMed

    Vachhani, Prashant S; Dalba, Giusepe; Ramamoorthy, Raj Kumar; Rocca, Francesco; Sipr, Ondrej; Bhatnagar, Anil K

    2012-12-19

    Cu doped ZnO polycrystalline pellets were synthesized with Cu concentrations varying from 2 to 10 wt% by a solid state reaction route (mixing of ZnO and CuO powders). Global magnetization measurements showed that all the samples were paramagnetic. Fitting the temperature-dependence of the magnetization to the Curie-Weiss law revealed the presence of an antiferromagnetic interaction between magnetic moments. Structural characterizations were carried out by x-ray diffraction and x-ray absorption spectroscopy (XAS) at the Cu K-edge. By analyzing the XAS data, we found that at low Cu content most of the Cu atoms substitute for Zn inside the ZnO wurtzite lattice, while for higher Cu concentrations some unreacted CuO remains segregated from the Zn(1-x)Cu(x)O solid solution. Element-specific magnetic measurements were carried out by x-ray magnetic circular dichroism (XMCD) and compared to the results of ab initio calculations. The XMCD signal at the Cu K-edge originates from magnetic moments localized at Cu sites and, by monitoring the magnetic field dependence, we concur that these moments are associated with a paramagnetic state.

  2. Chemical origin of the native ESR signals in thermally treated enamel and dentin

    NASA Astrophysics Data System (ADS)

    Bachmann, Luciano; Baffa, Oswaldo; Gomes, Anderson S. L.; Zezell, Denise M.

    2004-06-01

    Heating, crushing and exposure of dental enamel to sunlight and UV radiation can introduce paramagnetic signals similar to those following exposure to ionizing radiation. The objective of this work is to use infrared and electron spin resonance (ESR) spectra to study thermally treated enamel and dentin, and identify the chemical radical or mechanisms that produce these ambiguous ESR signals. Non-irradiated bovine teeth were used. ESR spectroscopy was performed in the X band and the infrared spectroscopy was performed on a FTIR spectrometer operating between 4000 cm -1 and 400 cm -1. The results show ESR signals in dentin heated at temperatures between 100°C and 1000°C and in enamel heated at temperatures ranging from 250°C to 1000°C. The ESR signal formed after heat treatment below 400°C could be assigned to degradation products of the organic material, while the ESR signals that predominate in tissues heated between 500°C and 900°C show a maximum amplitude at 750°C and could be assigned to the cyanate ion (NCO -).

  3. Properties of the Oxidized Cu(110) Surface: The DFT study

    NASA Astrophysics Data System (ADS)

    Olenga, Antoine; Fazleev, N. G.

    2012-10-01

    The study of adsorption of oxygen on transition metal surfaces is important for the understanding of oxidation, heterogeneous catalysis, and metal corrosion. In this work we have studied from first principles the changes of electronic properties of the Cu(110) surface due to oxygen adsorption. Especially, we have focused on studies of changes in the work function, electronic density, interlayer spacing, density of states and band structure with oxygen coverage. Calculations of electronic properties from first principles have been also performed for the (110) and surface of Cu2O to use for comparison. The first-principles calculations in this work have been performed on the basis of the Density Functional Theory and using DMOl3 code. The obtained theoretical results have been compared with available experimental data.

  4. Educating for Social Responsibility. The ESR Journal.

    ERIC Educational Resources Information Center

    Pittman, Susan Peters, Ed.

    1990-01-01

    Dedicated to Seth Kreisberg, this document is the first journal issue of the Educators for Social Responsibility (ESR). It begins with "The Real Ropes Course: The Development of Social Consciousness" (Shelley Berman). The other articles are presented in five sections. The first section, "Our Relationship to Society," contains: (1) "What Should…

  5. Novel Cu(II)-M(II)-Cu(II) (M = Cu or Ni) trinuclear and [NaCu] hexanuclear complexes assembled by bi-compartmental ligands: syntheses, structures, magnetic and catalytic studies.

    PubMed

    Biswas, Surajit; Dutta, Arpan; Dolai, Malay; Bhowmick, Indrani; Rouzières, Mathieu; Clérac, Rodolphe; Panja, Anangamohan; Ali, Mahammad

    2015-05-28

    In the present work, two compartmental ligands H2L(1) and H2L(2) were in situ generated during the syntheses of new trinuclear complexes, [Cu2Ni(L(1))(2,2'-bpy)2(NO3)2][ClO4]2 (), [Cu3(L(2))(NO3)2][ClO4]2 (), and [Cu3(L(2))(NCS)2(NO3)](+) that co-crystallize in with a [Cu6(L(2))2Na2(NO3)6(NCS)4] unit to give the final molecular formula [Cu6(L(2))2Na2(NO3)6(NCS)4][Cu3(L(2))(NCS)2(NO3)]2(NO3)2·5H2O (). The magnetic property studies of revealed weak Cu(II)-Cu(II) ferromagnetic interactions in compound (JCu-Cu/kB = +1.4(1) K) and (JCu-Cu/kB = +1.6) while in intranuclear Cu(II)-Ni(II)-Cu(II) compound , the magnetic coupling between two Cu(II) ions is switched off by the diamagnetic square planar Ni(II) bridge. The catalytic epoxidation of two olefins, namely styrene and cyclooctene, by tert-BuOOH (TBHP) was also explored in the presence of a catalytic amount of , or in MeCN. For styrene oxidation, exhibited ∼57% styrene epoxide selectively (conversion ∼37%) with a TON of about 925 along with benzaldehyde (∼43%), whereas exhibited conversion up to ∼63% (TON ∼ 1575) with a good selectivity towards epoxide (∼71%). For compound , this conversion is more important (TON ∼ 8108) probably due to the presence of more active sites involved in the epoxidation. The concerted path was found to be operative for styrene oxidation while a radical path was suggested for the oxidation of cyclooctene.

  6. A XANES study of Cu speciation in high-temperature brines using synthetic fluid inclusions

    SciTech Connect

    Berry, Andrew J.; Hack, Alistair C.; Mavrogenes, John A.; Newville, Matthew; Sutton, Stephen R.

    2010-12-03

    Cu K-edge X-ray absorption near edge structure (XANES) spectra were recorded from individual synthetic brine fluid inclusions as a function of temperature up to 500 C. The inclusions serve as sample cells for high-temperature spectroscopic studies of aqueous Cu-Cl speciation. Cu{sup +} and Cu{sup 2+} can both be identified from characteristic pre-edge features. Mixed oxidation states can be deconvoluted using linear combinations of Cu{sup +} and Cu{sup 2+} spectra. This work illustrates how complex Cu XANES spectra can be interpreted successfully. Cu{sup 2+} is the stable oxidation state in solution at room temperature and Cu{sup +} at high temperatures. The change in oxidation state with temperature was completely reversible. Cu{sup +} was found to occur exclusively as the linear species [CuCl{sub 2}]{sup -} in solutions containing KCl with Cu:Cl ratios up to 1:6. In the absence of K{sup +}, there is evidence for higher order coordination of Cu{sup +}, in particular the tetrahedral complex [CuCl{sub 4}]{sup 3-}. The importance of such complexes in natural ore-forming fluids is yet to be determined, but may explain the vapor-phase partitioning of Cu as a Cl complex from a Cl-rich brine.

  7. Synthesis, spectral, antitumor and antimicrobial studies on Cu(II) complexes of purine and triazole Schiff base derivatives

    NASA Astrophysics Data System (ADS)

    Amer, Said; El-Wakiel, Nadia; El-Ghamry, Hoda

    2013-10-01

    A series of copper (II) complexes of Schiff bases derived from 7H-2,6-diaminopurine and 4H-3,5-diamino-1,2,4-triazole with 2-pyridinecarbaldehyde, salicylaldehyde, 2,4-dihydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde have been prepared. The donor atoms and the possible geometry of the complexes were investigated by means of elemental and thermal analyses, molar conductance, magnetic moment, UV-Vis, IR, ESR and mass spectra. The ligands behaved as tetradentate, coordinating through the nitrogen atom of the azomethine group and the nearest nitrogen atom to it or oxygen atom of α-hydroxyl group. The results of simultaneous DTA & TGA analyses of the complexes showed the final degradation product for these complexes is CuO. The spectral studies confirmed a four coordinate environment around the metal ion. The obtained results were supported by 3D molecular modeling of complexes using molecular mechanics (MM+) and semiempirical molecular orbital calculations (PM3). These complexes were also tested for their in vitro antimicrobial activities against some bacterial and fungal strains. Complex 2 was investigated for its cyctotoxic effect against human breast cancer (MCF7), liver carcinoma (HEPG2) and colon carcinoma cell lines (HCT116). This compound exhibited a moderate activity against the tested cell lines with IC50 of 10.3, 9.8 and 8.7 μg/ml against MCF7, HCT116 and HEPG2, respectively.

  8. An invasive and low virulent Edwardsiella tarda esrB mutant promising as live attenuated vaccine in aquaculture.

    PubMed

    Yang, Weizheng; Wang, Lixia; Zhang, Lingzhi; Qu, Jiangbo; Wang, Qiyao; Zhang, Yuanxing

    2015-02-01

    Edwardsiella tarda is a leading fish pathogen haunting worldwide aquaculture industry. In E. tarda, two-component system EsrA-EsrB positively regulates type III and VI secretion systems (T3SS and T6SS) and negatively regulates hemolysin EthA, which has been demonstrated to be essential for the invasion processes in fish. In order to develop a live attenuated vaccine (LAV) with high invasiveness to be practically and economically used as immersion-administered vaccine in aquaculture, here, we generated a random mutation library of esrB sequences by error-prone PCR and introduced them into the E. tarda esrB deletion mutant. The mutant YWZ47 with significantly increased hemolytic activity and low T3SS and T6SS secretion was screened. Phenotypes including extracellular protein profiles, invasion in macrophages, lethality toward fish, and infection kinetics were investigated in the wild-type strain EIB202 and the mutants ΔesrB, ΔT3SS, ΔT6SS, ΔT3SS/ΔT6SS, and YWZ47. Compared to the documented LAV strain ΔesrB, YWZ47 showed higher invasive capability and low in vivo virulence toward fish. Significantly higher relative percent survival (RPS) could be generated in turbot (Scophthalmus maximus) against the challenge of the wild-type EIB202 when inoculated through immersion route, and the RPS was comparable with that of ΔesrB through intraperitoneal (i.p.) injection inoculation. Two mutated points, K167M and H197L, were found by sequence analysis of EsrBYWZ47 variant. These structural modifications underpin the variations in the regulatory functions of the mutant and wild-type EsrB. This study promoted understanding of virulence regulation by EsrB in E. tarda and presented a promising candidate of invasive attenuated vaccine used in aquaculture industries. PMID:25431010

  9. An invasive and low virulent Edwardsiella tarda esrB mutant promising as live attenuated vaccine in aquaculture.

    PubMed

    Yang, Weizheng; Wang, Lixia; Zhang, Lingzhi; Qu, Jiangbo; Wang, Qiyao; Zhang, Yuanxing

    2015-02-01

    Edwardsiella tarda is a leading fish pathogen haunting worldwide aquaculture industry. In E. tarda, two-component system EsrA-EsrB positively regulates type III and VI secretion systems (T3SS and T6SS) and negatively regulates hemolysin EthA, which has been demonstrated to be essential for the invasion processes in fish. In order to develop a live attenuated vaccine (LAV) with high invasiveness to be practically and economically used as immersion-administered vaccine in aquaculture, here, we generated a random mutation library of esrB sequences by error-prone PCR and introduced them into the E. tarda esrB deletion mutant. The mutant YWZ47 with significantly increased hemolytic activity and low T3SS and T6SS secretion was screened. Phenotypes including extracellular protein profiles, invasion in macrophages, lethality toward fish, and infection kinetics were investigated in the wild-type strain EIB202 and the mutants ΔesrB, ΔT3SS, ΔT6SS, ΔT3SS/ΔT6SS, and YWZ47. Compared to the documented LAV strain ΔesrB, YWZ47 showed higher invasive capability and low in vivo virulence toward fish. Significantly higher relative percent survival (RPS) could be generated in turbot (Scophthalmus maximus) against the challenge of the wild-type EIB202 when inoculated through immersion route, and the RPS was comparable with that of ΔesrB through intraperitoneal (i.p.) injection inoculation. Two mutated points, K167M and H197L, were found by sequence analysis of EsrBYWZ47 variant. These structural modifications underpin the variations in the regulatory functions of the mutant and wild-type EsrB. This study promoted understanding of virulence regulation by EsrB in E. tarda and presented a promising candidate of invasive attenuated vaccine used in aquaculture industries.

  10. Photoelectron and computational studies of the copper-nucleoside anionic complexes, Cu{sup -}(cytidine) and Cu{sup -}(uridine)

    SciTech Connect

    Li Xiang; Ko, Yeon-Jae; Wang Haopeng; Bowen, Kit H.; Guevara-Garcia, Alfredo; Martinez, Ana

    2011-02-07

    The copper-nucleoside anions, Cu{sup -}(cytidine) and Cu{sup -}(uridine), have been generated in the gas phase and studied by both experimental (anion photoelectron spectroscopy) and theoretical (density functional calculations) methods. The photoelectron spectra of both systems are dominated by single, intense, and relatively narrow peaks. These peaks are centered at 2.63 and 2.71 eV for Cu{sup -}(cytidine) and Cu{sup -}(uridine), respectively. According to our calculations, Cu{sup -}(cytidine) and Cu{sup -}(uridine) species with these peak center [vertical detachment energy (VDE)] values correspond to structures in which copper atomic anions are bound to the sugar portions of their corresponding nucleosides largely through electrostatic interactions; the observed species are anion-molecule complexes. The combination of experiment and theory also reveal the presence of a slightly higher energy, anion-molecule complex isomer in the case of the Cu{sup -}(cytidine). Furthermore, our calculations found that chemically bond isomers of these species are much more stable than their anion-molecule complex counterparts, but since their calculated VDE values are larger than the photon energy used in these experiments, they were not observed.

  11. Component, Microstructure and Simulation Calculation Study of Bimetallic Pt-Cu Alloys Towards Catalyzing Methanol Oxidation Reaction

    NASA Astrophysics Data System (ADS)

    Wei, Shenying; Gao, Huaizhi; Li, Haibo; Li, Rui; Liu, Jifeng

    2014-12-01

    Three Pt-Cu alloys (Pt0.3Cu0.7, Pt0.5Cu0.5, and Pt0.7Cu0.3) with different Cu contents were synthesized by adjusting the Pt/Cu precursor ratio, and their electrocatalytic activities for methanol oxidation reaction (MOR) were systematically studied. Component and microstructure study revealed that the relationship between the lattice parameters and Cu content followed the Vegard's law. Electrochemistry measurement showed that the MOR catalytic activity for Pt-Cu alloys displayed a dependency on the Cu content, and it decreased following: Pt0.3Cu0.7 > Pt0.5Cu0.5 > Pt0.7Cu0.3. Among the three Pt-Cu alloys, the Pt0.3Cu0.7 alloy exhibited the highest oxidation current density and best CO tolerance activity. Density functional theory simulation calculation, taking into account the shrinking of Pt-Cu alloy's lattice after Cu incorporation, confirmed that the adsorption energy of CO also displayed a dependency on the Cu content in Pt-Cu alloys, and it increased following: Pt0.3Cu0.7 < Pt0.5Cu0.5 < Pt0.7Cu0.3 < Pt, which could rationally explain the best CO tolerance ability for the Pt0.3Cu0.7.

  12. Studies of Fe-Cu microwires with nanogranular structure

    NASA Astrophysics Data System (ADS)

    Zhukov, A.; García, C.; DelVal, J. J.; Gonzalez, J.; Knobel, M.; Serantes, D.; Baldomir, D.; Zhukova, V.

    2009-01-01

    We report on the fabrication, and structural and magnetic characterization of Cu63Fe37 microwires with granular structure produced by rapid quenching, using the Tailor-Ulitovsky method, from the immiscible alloys. X-ray diffraction study demonstrated that the structure consists of small (6-45 nm) crystallites of Cu and body centred cubic α-Fe. Magnetic properties have been measured in the range of 5-300 K using a SQUID (superconducting quantum interference device) magnetometer. The temperature dependences of the magnetization measured in a cooling regime when no external magnetic field is applied (zero-field cooling) and in the presence of the field (field cooling) show considerable difference below 20 K. This difference could be related to the presence of small α-Fe grains embedded in the Cu matrix. Those α-Fe grains appear to be blocked at temperatures below that at which the maximum of the magnetization is observed in the low temperature range. Significant magnetoresistance (about 7%) has been found in the samples studied. The shape of the observed dependences is typical of a giant magnetoresistance effect.

  13. Study of UV Cu + Ne – CuBr laser lifetime by statistical methods

    SciTech Connect

    Iliev, I P; Gocheva-Ilieva, S G

    2013-11-30

    On the basis of a large amount of experimental data, statistical investigation of the average lifetime of a UV Cu + Ne – CuBr laser depending on ten input physical laser parameters is carried out. It is found that only three of the parameters have a substantial influence on the laser lifetime. Physical analysis and interpretation of the results are provided. (lasers)

  14. Dynamics of 4-oxo-TEMPO-d16-15N nitroxide-propylene glycol system studied by ESR and ESE in liquid and glassy state in temperature range 10-295 K

    NASA Astrophysics Data System (ADS)

    Goslar, Janina; Hoffmann, Stanislaw K.; Lijewski, Stefan

    2016-08-01

    ESR spectra and electron spin relaxation of nitroxide radical in 4-oxo-TEMPO-d16-15N in propylene glycol were studied at X-band in the temperature range 10-295 K. The spin-lattice relaxation in the liquid viscous state determined from the resonance line shape is governed by three mechanisms occurring during isotropic molecular reorientations. In the glassy state below 200 K the spin-lattice relaxation, phase relaxation and electron spin echo envelope modulations (ESEEM) were studied by pulse spin echo technique using 2-pulse and 3-pulse induced signals. Electron spin-lattice relaxation is governed by a single non-phonon relaxation process produced by localized oscillators of energy 76 cm-1. Electron spin dephasing is dominated by a molecular motion producing a resonance-type peak in the temperature dependence of the dephasing rate around 120 K. The origin of the peak is discussed and a simple method for the peak shape analysis is proposed, which gives the activation energy of a thermally activated motion Ea = 7.8 kJ/mol and correlation time τ0 = 10-8 s. The spin echo amplitude is strongly modulated and FT spectrum contains a doublet of lines centered around the 2D nuclei Zeeman frequency. The splitting into the doublet is discussed as due to a weak hyperfine coupling of nitroxide unpaired electron with deuterium of reorienting CD3 groups.

  15. DNA cleavage, antibacterial, antifungal and anthelmintic studies of Co(II), Ni(II) and Cu(II) complexes of coumarin Schiff bases: Synthesis and spectral approach

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Prabhakara, Chetan T.; Halasangi, Bhimashankar M.; Toragalmath, Shivakumar S.; Badami, Prema S.

    2015-02-01

    The metal complexes of Co(II), Ni(II) and Cu(II) have been synthesized from 6-formyl-7,8-dihydroxy-4-methylcoumarin with o-toluidine/3-aminobenzotrifluoride. The synthesized Schiff bases and their metal complexes were structurally characterized based on IR, 1H NMR, 13C NMR, UV-visible, ESR, magnetic, thermal, fluorescence, mass and ESI-MS studies. The molar conductance values indicate that complexes are non-electrolytic in nature. Elemental analysis reveals ML2·2H2O [M = Co(II), Ni(II) and Cu(II)] stoichiometry, where 'L' stands for a singly deprotonated ligand. The presence of co-ordinated water molecules were confirmed by thermal studies. The spectroscopic studies suggest the octahedral geometry. Redox behavior of the complexes were confirmed by cyclic voltammetry. All the synthesized compounds were screened for their antibacterial (Escherichia coli, Pseudomonas auregenosa, klebsiella, Proteus, Staphylococcus aureus and salmonella) antifungal (Candida, Aspergillus niger and Rhizopus), anthelmintic (Pheretima posthuma) and DNA cleavage (Calf Thymus DNA) activity.

  16. Co(II), Ni(II) and Cu(II) complexes with coumarin-8-yl Schiff-bases: Spectroscopic, in vitro antimicrobial, DNA cleavage and fluorescence studies

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Unki, Shrishila N.; Kulkarni, Ajaykumar D.; Naik, Vinod H.; Badami, Prema S.

    2011-09-01

    A new series of Co(II), Ni(II) and Cu(II) complexes of the type ML·2H 2O of Schiff-bases derived from m-substituted thiosemicarbazides and 8-acetyl-7-hydroxy-4-methylcoumarin have been synthesized and characterized by spectroscopic studies. Schiff-bases exhibit thiol-thione tautomerism wherein sulphur plays an important role in the coordination. The coordination possibility of the Schiff-bases towards metal ions have been proposed in the light of elemental analyses, spectral (IR, UV-vis, FAB-mass, ESR and fluorescence), magnetic and thermal studies. The low molar conductance values in DMF indicate that, the metal complexes are non-electrolytes. The cyclic voltammetric studies suggested that, the Cu(II) and Ni(II) complexes are of single electron transfer quasi-reversible nature. The Schiff-bases and its metal complexes have been evaluated for their in vitro antibacterial ( Escherichia coli, Staphilococcus aureus, Bascillus subtilis and Salmonella typhi) and antifungal activities ( Candida albicans, Cladosporium and Aspergillus niger) by MIC method. The Schiff-base I and its metal complexes exhibited DNA cleavage activity on isolated DNA of A. niger.

  17. Synchrotron Radiation Diffraction Study of YbInCu4

    NASA Astrophysics Data System (ADS)

    Utsumi, Yuki; Sato, Hitoshi; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Namatame, Hirofumi; Taniguchi, Masaki; Hiraoka, Koichi; Kojima, Kenichi; Sugimoto, Kunihisa

    2011-05-01

    The structural change of an YbInCu4 single crystal has been investigated associated with the first-order valence-transition at TV = 42 K using synchrotron radiation diffraction. The Yb-Cu and In-Cu interatomic distances abruptly increase below TV, following the lattice expansion with no change in the C15b-type crystal structure. We find that the distance between Cu ions forming the Cu4 cluster in the crystal is almost unchanged across the valence transition. No abrupt change in the thermal rotational motion of the Cu4 cluster is observed at TV.

  18. Electrical conductivity studies on CuBr containing Al2O3 particles

    NASA Technical Reports Server (NTRS)

    Dubec, P. M.; Wagner, J. B., Jr.

    1984-01-01

    The conductivity of CuBr was studied and the role of a second phase, Al2O3, dispersed in CuBr was tested. CuBr melts at 493 C and exhibits three phases in the solid state. CuBr is a good ionic conductor with a transport number for copper ions of virtually unity with weighed proportions of the appropriate chemicals used. The CuBr materials were heated above melting point of CuBr, and the samples were sandwiched between copper electrodes. The ac conductivity, was determined at 1 kHz between 25 and 440 C depending on the sample. It was shown that at low temperatures, the conductivity for CuBr (Al2O3) increased by as much as 100, whereas in the beta phase the conductivity of CuBr containing Al2O3 decreased. The electrical conductivity studies are in agreement with earlier data.

  19. Heterogeneity and clinical significance of ESR1 mutations in ER-positive metastatic breast cancer patients receiving fulvestrant.

    PubMed

    Spoerke, Jill M; Gendreau, Steven; Walter, Kimberly; Qiu, Jiaheng; Wilson, Timothy R; Savage, Heidi; Aimi, Junko; Derynck, Mika K; Chen, Meng; Chan, Iris T; Amler, Lukas C; Hampton, Garret M; Johnston, Stephen; Krop, Ian; Schmid, Peter; Lackner, Mark R

    2016-01-01

    Mutations in ESR1 have been associated with resistance to aromatase inhibitor (AI) therapy in patients with ER+ metastatic breast cancer. Little is known of the impact of these mutations in patients receiving selective oestrogen receptor degrader (SERD) therapy. In this study, hotspot mutations in ESR1 and PIK3CA from ctDNA were assayed in clinical trial samples from ER+ metastatic breast cancer patients randomized either to the SERD fulvestrant or fulvestrant plus a pan-PI3K inhibitor. ESR1 mutations are present in 37% of baseline samples and are enriched in patients with luminal A and PIK3CA-mutated tumours. ESR1 mutations are often polyclonal and longitudinal analysis shows distinct clones exhibiting divergent behaviour over time. ESR1 mutation allele frequency does not show a consistent pattern of increases during fulvestrant treatment, and progression-free survival is not different in patients with ESR1 mutations compared with wild-type patients. ESR1 mutations are not associated with clinical resistance to fulvestrant in this study. PMID:27174596

  20. Heterogeneity and clinical significance of ESR1 mutations in ER-positive metastatic breast cancer patients receiving fulvestrant

    PubMed Central

    Spoerke, Jill M.; Gendreau, Steven; Walter, Kimberly; Qiu, Jiaheng; Wilson, Timothy R.; Savage, Heidi; Aimi, Junko; Derynck, Mika K.; Chen, Meng; Chan, Iris T.; Amler, Lukas C.; Hampton, Garret M.; Johnston, Stephen; Krop, Ian; Schmid, Peter; Lackner, Mark R.

    2016-01-01

    Mutations in ESR1 have been associated with resistance to aromatase inhibitor (AI) therapy in patients with ER+ metastatic breast cancer. Little is known of the impact of these mutations in patients receiving selective oestrogen receptor degrader (SERD) therapy. In this study, hotspot mutations in ESR1 and PIK3CA from ctDNA were assayed in clinical trial samples from ER+ metastatic breast cancer patients randomized either to the SERD fulvestrant or fulvestrant plus a pan-PI3K inhibitor. ESR1 mutations are present in 37% of baseline samples and are enriched in patients with luminal A and PIK3CA-mutated tumours. ESR1 mutations are often polyclonal and longitudinal analysis shows distinct clones exhibiting divergent behaviour over time. ESR1 mutation allele frequency does not show a consistent pattern of increases during fulvestrant treatment, and progression-free survival is not different in patients with ESR1 mutations compared with wild-type patients. ESR1 mutations are not associated with clinical resistance to fulvestrant in this study. PMID:27174596

  1. Comprehensive genetic assessment of the ESR1 locus identifies a risk region for endometrial cancer

    PubMed Central

    O’Mara, Tracy A; Glubb, Dylan M; Painter, Jodie N; Cheng, Timothy; Dennis, Joe; Attia, John; Holliday, Elizabeth G; McEvoy, Mark; Scott, Rodney J; Ashton, Katie; Proietto, Tony; Otton, Geoffrey; Shah, Mitul; Ahmed, Shahana; Healey, Catherine S; Gorman, Maggie; Martin, Lynn; Hodgson, Shirley; Fasching, Peter A; Hein, Alexander; Beckmann, Matthias W; Ekici, Arif B; Hall, Per; Czene, Kamila; Darabi, Hatef; Li, Jingmei; Dürst, Matthias; Runnebaum, Ingo; Hillemanns, Peter; Dörk, Thilo; Lambrechts, Diether; Depreeuw, Jeroen; Annibali, Daniela; Amant, Frederic; Zhao, Hui; Goode, Ellen L; Dowdy, Sean C; Fridley, Brooke L; Winham, Stacey J; Salvesen, Helga B; Njølstad, Tormund S; Trovik, Jone; Werner, Henrica MJ; Tham, Emma; Liu, Tao; Mints, Miriam; Bolla, Manjeet K; Michailidou, Kyriaki; Tyrer, Jonathan P; Wang, Qin; Hopper, John L; Peto, Julian; Swerdlow, Anthony J; Burwinkel, Barbara; Brenner, Hermann; Meindl, Alfons; Brauch, Hiltrud; Lindblom, Annika; Chang-Claude, Jenny; Couch, Fergus J; Giles, Graham G; Kristensen, Vessela N; Cox, Angela; Pharoah, Paul D P; Dunning, Alison M; Tomlinson, Ian; Easton, Douglas F; Thompson, Deborah J; Spurdle, Amanda B

    2015-01-01

    Excessive exposure to estrogen is a well-established risk factor for endometrial cancer (EC), particularly for cancers of endometrioid histology. The physiological function of estrogen is primarily mediated by estrogen receptor alpha, encoded by ESR1. Consequently, several studies have investigated whether variation at the ESR1 locus is associated with risk of EC, with conflicting results. We performed comprehensive fine-mapping analyses of 3,633 genotyped and imputed single nucleotide polymorphisms (SNPs) in 6,607 EC cases and 37,925 controls. There was evidence of an EC risk signal located at a potential alternative promoter of the ESR1 gene (lead SNP rs79575945, P = 1.86 × 10−5), which was stronger for cancers of endometrioid subtype (P = 3.76 × 10−6). Bioinformatic analysis suggests that this risk signal is in a functionally important region targeting ESR1, and eQTL analysis found that rs79575945 was associated with expression of SYNE1, a neighbouring gene. In summary, we have identified a single EC risk signal located at ESR1, at study-wide significance. Given SNPs located at this locus have been associated with risk for breast cancer, also a hormonally driven cancer, this study adds weight to the rationale for performing informed candidate fine-scale genetic studies across cancer types. PMID:26330482

  2. Comprehensive genetic assessment of the ESR1 locus identifies a risk region for endometrial cancer.

    PubMed

    O'Mara, Tracy A; Glubb, Dylan M; Painter, Jodie N; Cheng, Timothy; Dennis, Joe; Attia, John; Holliday, Elizabeth G; McEvoy, Mark; Scott, Rodney J; Ashton, Katie; Proietto, Tony; Otton, Geoffrey; Shah, Mitul; Ahmed, Shahana; Healey, Catherine S; Gorman, Maggie; Martin, Lynn; Hodgson, Shirley; Fasching, Peter A; Hein, Alexander; Beckmann, Matthias W; Ekici, Arif B; Hall, Per; Czene, Kamila; Darabi, Hatef; Li, Jingmei; Dürst, Matthias; Runnebaum, Ingo; Hillemanns, Peter; Dörk, Thilo; Lambrechts, Diether; Depreeuw, Jeroen; Annibali, Daniela; Amant, Frederic; Zhao, Hui; Goode, Ellen L; Dowdy, Sean C; Fridley, Brooke L; Winham, Stacey J; Salvesen, Helga B; Njølstad, Tormund S; Trovik, Jone; Werner, Henrica M J; Tham, Emma; Liu, Tao; Mints, Miriam; Bolla, Manjeet K; Michailidou, Kyriaki; Tyrer, Jonathan P; Wang, Qin; Hopper, John L; Peto, Julian; Swerdlow, Anthony J; Burwinkel, Barbara; Brenner, Hermann; Meindl, Alfons; Brauch, Hiltrud; Lindblom, Annika; Chang-Claude, Jenny; Couch, Fergus J; Giles, Graham G; Kristensen, Vessela N; Cox, Angela; Pharoah, Paul D P; Dunning, Alison M; Tomlinson, Ian; Easton, Douglas F; Thompson, Deborah J; Spurdle, Amanda B

    2015-10-01

    Excessive exposure to estrogen is a well-established risk factor for endometrial cancer (EC), particularly for cancers of endometrioid histology. The physiological function of estrogen is primarily mediated by estrogen receptor alpha, encoded by ESR1. Consequently, several studies have investigated whether variation at the ESR1 locus is associated with risk of EC, with conflicting results. We performed comprehensive fine-mapping analyses of 3633 genotyped and imputed single nucleotide polymorphisms (SNPs) in 6607 EC cases and 37 925 controls. There was evidence of an EC risk signal located at a potential alternative promoter of the ESR1 gene (lead SNP rs79575945, P=1.86×10(-5)), which was stronger for cancers of endometrioid subtype (P=3.76×10(-6)). Bioinformatic analysis suggests that this risk signal is in a functionally important region targeting ESR1, and eQTL analysis found that rs79575945 was associated with expression of SYNE1, a neighbouring gene. In summary, we have identified a single EC risk signal located at ESR1, at study-wide significance. Given SNPs located at this locus have been associated with risk for breast cancer, also a hormonally driven cancer, this study adds weight to the rationale for performing informed candidate fine-scale genetic studies across cancer types. PMID:26330482

  3. Calorimetric studies of Cu-Li, Li-Sn, and Cu-Li-Sn.

    PubMed

    Fürtauer, S; Tserenjav, E; Yakymovych, A; Flandorfer, H

    2013-06-01

    Integral molar enthalpies of mixing were determined by drop calorimetry for Cu-Li-Sn at 1073 K along five sections xCu/xSn ≈ 1:1, xCu/xSn ≈ 2:3, xCu/xSn ≈ 1:4, xLi/xSn ≈ 1:1, and xLi/xSn ≈ 1:4. The integral and partial molar mixing enthalpies of Cu-Li and Li-Sn were measured at the same temperature, for Li-Sn in addition at 773 K. All binary data could be described by Redlich-Kister-polynomials. Cu-Li shows an endothermic mixing effect with a maximum in the integral molar mixing enthalpy of ∼5300 J · mol(-1) at xCu = 0.5, Li-Sn an exothermic minimum of ∼ -37,000 J · mol(-1) at xSn ∼ 0.2. For Li-Sn no significant temperature dependence between 773 K and 1073 K could be deduced. Our measured ternary data were fitted on the basis of an extended Redlich-Kister-Muggianu model for substitutional solutions. Additionally, a comparison of these results to the extrapolation model of Chou is given.

  4. Electrochemical Aspects of the ESR Process

    NASA Astrophysics Data System (ADS)

    Mitchell, Alec

    2016-07-01

    Current passage in the ESR process is accomplished by at least two Faradaic reaction systems, one at the electrode/slag interface and another at the slag/ingot interface. The nature of these reactions has been investigated and is reported to be a function of the alloy composition, current density and slag composition. In this report, data generated from both DC and line- frequency AC ESR operations is used to relate laboratory investigations on these reactions to results obtained in industrial practice. The operating reaction in the line frequency AC melting of simple alloy steels is found to be principally the reversible anodic oxidation of iron (Fe/Fe2+). In the equivalent DC process there is in addition the cathodic deposition of aluminium, resulting in the formation of substantial amounts of D-type alumina inclusions in the ingot. The Faradaic reactions involve energy exchange which should be taken into account in the process energy balance. They also are likely to change the interface physical characteristics such as interfacial tension. The data is extended to the case of low frequency ESR furnaces in which it is found that the extent of the reactions is strongly dependent on current density. It is concluded that the presence of Faradaic reactions in low frequency furnaces is unlikely to lead to quality problems in the alloys and applications for which these processes are used. This conclusion appears to be supported by industrial practice and leads to a further conclusion that low frequency practices in large ESR furnaces could potentially be replaced by simpler DC systems.

  5. 1,3,5-Benzenetribenzoic Acid on Cu(111) and Graphene/Cu(111): A Comparative STM Study

    PubMed Central

    2016-01-01

    The self-assembly of 1,3,5-benzenetribenzoic acid (BTB) molecules on both Cu(111) and epitaxial graphene grown on Cu(111) were studied by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) under ultrahigh vacuum conditions. On Cu(111), the BTB molecules were found to mainly arrange in close-packed structures through H-bonding between the (partially) deprotonated carboxylic acid groups. In addition, porous structures formed by intact BTB molecules-and also based on H-bonding-were observed. On graphene grown on Cu(111) the BTB molecules mainly form porous structures accompanied by small patches of disordered close-packed structures. Upon annealing, BTB adsorbed on Cu(111) is fully deprotonated and arranges in the close-packed structure while in contrast on graphene/Cu(111) the porous network is exclusively formed. This shows that the molecular self-assembly behavior is highly dependent on the first substrate layer: one graphene layer is sufficient to considerably alter the interplay of molecule substrate and intermolecular interactions in favor of the latter interactions. PMID:27588158

  6. Characterization of macrosegregation in ESR IN-718

    NASA Technical Reports Server (NTRS)

    Domingue, J. A.; Yu, K. O.; Flanders, H. D.

    1984-01-01

    Aspects of macrosegregation theory, such as dendrite arm spacing, pool profile and mushy zone depth are beneficial to developing consumable melting process for Ion Nickel IN-718, Electro-Slag Refining, especially ESR. Aspects of microsegregation theory, such as correlation of dendrite arm spacing with heat transfer mechanisms and local solidification time, are used to minimize remnant dendritism in both ESR and Vacuum Arc Remelting VAR IN-718. Specifically, ESR IN-718 must be optimized by developing practices which maximize ingot cooling rate and minimize the steepness of the solidus and liquidus isotherms. The knowledge concerning macrosegregation in consumable melted IN-718 is in the form of correlations. Since the isotherm steepness is undoubtedly involved, investigations which include a microgravity environment might separate microsegregation effects from macrosegregation effects. Accounting for the effects of gravity and density differences between the metal pool and the interdendritic fluid, in combination with the pool and mushy zone profiles, can lead to improved melting solidification practices for IN-718, and allow prediction of macrosegregation tendency to be incorporated into high temperature alloy design.

  7. Manufacturing of 9CrMoCoB Steel of Large Ingot with Homogeneity by ESR Process

    NASA Astrophysics Data System (ADS)

    Kim, D. S.; Lee, G. J.; Lee, M. B.; Hur, J. I.; Lee, J. W.

    2016-07-01

    In case of 9CrMoCoB (COST FB2) steel, equilibrium relation between [B]/[Si] ratio and (B2O3)/(SiO2) ratio is very important to control [Si] and [B] in optimum range. Therefore, in this work, to investigate the thermodynamic equilibrium relation between [B]/[Si] ratio and (B2O3)/(SiO2) ratio, pilot ESR experiments of 9CrMoCoB steel were carried out using the CaF2-CaO-Al2O3-SiO2-B2O3 slag system according to change of Si content in electrode and B2O3 content in the slag. Furthermore, through the test melting of the 20ton-class ESR ingot, the merits and demerits of soft arcing were investigated. From these results, it is concluded that oxygen content in the ESR ingot decrease with decreasing SiO2 content in the slag, relation function between [B]/[Si] ratio and (B2O3)/(SiO2) ratio derived by Pilot ESR test shows a good agreement as compared to the calculated line with a same slope and soft arcing makes interior and surface quality of ingot worse. With the optimized ESR conditions obtained from the present study, a 1000mm diameter (20 tons) and 2200mm diameter (120ton) 9CrMoCoB steel of the ESR ingot were successfully manufactured with good homogeneity by the ESR process.

  8. Hemolysin EthA in Edwardsiella tarda is essential for fish invasion in vivo and in vitro and regulated by two-component system EsrA-EsrB and nucleoid protein HhaEt.

    PubMed

    Wang, Xin; Wang, Qiyao; Xiao, Jingfan; Liu, Qin; Wu, Haizhen; Zhang, Yuanxing

    2010-12-01

    Edwardsiella tarda is a Gram-negative pathogen for hemorrhagic septicemia in fish. Recently, two-component system (TCS) EsrA-EsrB in E. tarda has been found to play key roles in regulating type III secretion system (TTSS) and type VI secretion system (T6SS). In this study, a markedly attenuated ΔesrB mutant was investigated to exhibit enhanced cell-invasion capability, as well as the increased cytotoxicity of its extracellular products (ECPs). Compared with the parental strain, the ΔesrB mutant unexpectedly displayed the significantly increased hemolytic activity, and the restoration of hemolysin production was observed in the complemented strain esrB(+). A hemolysis-associated 147 kDa protein, EthA, was found to be up-regulated in the ECPs of ΔesrB. The deletion of ethA gene in E. tarda wild type and ΔesrB strains drastically decreased their capacities in internalization of epithelial papilloma of carp (EPC) cells. These results indicated that the increased production of EthA was responsible for the enhanced cell-invasion related capabilities in ΔesrB. Furthermore, the expression of EthA in ΔesrB exhibited a temperature-induced manner, and a nucleoid protein Hha(Et) was identified to mediate ethA expression by directly binding to its promoter. These results demonstrated that the virulence determinant EthA was fully required for invasion abilities of E. tarda and was subjected to the control of a complicated and precisely regulated network primed for its invasion, colonization and infection process in fish. PMID:20832475

  9. Preclinical studies of [61Cu]ATSM as a PET radiopharmaceutical for fibrosarcoma imaging.

    PubMed

    Jalilian, Amir R; Rostampour, Nima; Rowshanfarzad, Pejman; Shafaii, Kamaleddin; Kamali-Dehghan, Mohsen; Akhlaghi, Mehdi

    2009-03-01

    [61Cu]diacetyl-bis(N4-methylthiosemicarbazone) ([61Cu] ATSM) was prepared using in house-made diacetyl-bis(N4-methylthiosemicarbazone) (ATSM) ligand and [61Cu]CuCl2 produced via the natZn(p, x)61Cu (180 muA proton irradiation, 22 MeV, 3.2 h) and purified by a ion chromatography method. [61Cu]ATSM radiochemical purity was >98 %, as shown by HPLC and RTLC methods. [61Cu]ATSM was administered into normal and tumor bearing rodents for up to 210 minutes, followed by biodistribution and co-incidence imaging studies. Significant tumor/non-tumor accumulation was observed either by animal sacrification or imaging. [61Cu]ATSM is a positron emission tomography (PET) radiotracer for tumor hypoxia imaging.

  10. Pulse Dipolar ESR and Protein Superstructures and Function

    NASA Astrophysics Data System (ADS)

    Freed, Jack

    2014-03-01

    Pulse dipolar electron-spin resonance (PDS-ESR) has emerged as a powerful methodology for the study of protein structure and function. This technology, in the form of double quantum coherence (DQC) - ESR and double-electron-electron resonance (DEER) in conjunction with site-directed spin-labeling will be described. It enables the measurement of distances and their distributions in the range of 1-9 nm between pairs of spins labeled at two sites in the protein. Many biological objects can be studied: soluble and membrane proteins, protein complexes, etc. Many sample morphologies are possible: uniform, heterogeneous, etc. thereby permitting a variety of sample types: solutions, liposomes, micelles, bicelles. Concentrations from micromolar to tens of millimolar are amenable, requiring only small amounts of biomolecules. The distances are quite accurate, so a relatively small number of them are sufficient to reveal structures and functional details. Several examples will be shown. The first is defining the protein complexes that mediate bacterial chemotaxis, which is the process whereby cells modulate their flagella-driven motility in response to environmental cues. It relies on a complex sensory apparatus composed of transmembrane receptors, histidine kinases, and coupling proteins. PDS-based models have captured key architectural features of the receptor kinase arrays and the flagellar motor, and their changes in conformation and dynamics that accompany kinase activation and motor switching. Another example will be determining the conformational states and cycling of a membrane transporter, GltPh, which is a homotrimer, in its apo, substrate-bound, and inhibitor-bound, states in membrane vesicles providing insight into its energetics. In a third example the structureless (in solution) proteins alpha-synuclein and tau, which are important in Parkinson's disease and in neurodegeneration will be described and the structures they take on in contact with membranes will be

  11. Development of multi-frequency ESR system for high-pressure measurements up to 2.5 GPa.

    PubMed

    Sakurai, T; Fujimoto, K; Matsui, R; Kawasaki, K; Okubo, S; Ohta, H; Matsubayashi, K; Uwatoko, Y; Tanaka, H

    2015-10-01

    A new piston-cylinder pressure cell for electron spin resonance (ESR) has been developed. The pressure cell consists of a double-layer hybrid-type cylinder with internal components made of the ZrO2-based ceramics. It can generate a pressure of 2 GPa repeatedly and reaches a maximum pressure of around 2.5 GPa. A high-pressure ESR system using a cryogen-free superconducting magnet up 10T has also been developed for this hybrid-type pressure cell. The frequency region is from 50 GHz to 400 GHz. This is the first time a pressure above 2 GPa has been achieved in multi-frequency ESR system using a piston-cylinder pressure cell. We demonstrate its potential by showing the results of the high-pressure ESR of the S=1 system with the single ion anisotropy NiSnCl6·6H2O and the S=1/2 quantum spin system CsCuCl3. We performed ESR measurements of these systems above 2 GPa successfully. PMID:26319278

  12. Adsorption of Cu(II) on the (0001) plane of mica: A REFLEXAFS and XPS study

    SciTech Connect

    Farquhar, M.L.; England, K.E.R.; Vaughan, D.J.; Charnock, J.M. |

    1996-02-10

    Using reflection extended X-ray absorption fine structure spectroscopy (REFLEXAFS) and X-ray photoelectron spectroscopy (XPS) it has been established that Cu(II) in low concentration in aqueous media can be chemisorbed onto the (0001) surface of muscovite mica. From the XPS studies it is suggested that the Cu species is in a similar bonding environment to the copper in copper hydroxide. A depth profile of the reacted mica surface was also carried out using XPS and this suggests that there had been no diffusion of the Cu into the mica surface. REFLEXAFS studies of the reacted mica surface provided information about shells of O, AlSi, and Cu surrounding a central Cu absorber. The best-fit bond distances are as follows: O{single_bond}Cu, 1.98 {angstrom}; Cu{single_bond}Cu, 2.64 {angstrom}; Al/Si{single_bond}Cu, 3.09 {angstrom}. This provides direct evidence for Cu being bound to the surface at aluminate or silicate groups and suggests that the Cu species adsorbed onto the surface are similar to the copper species found in copper hydroxide, plancheite, and shattuckite. It is proposed that Cu is chemisorbed at atomic imperfections, such as steps and kinks, on the mica surface.

  13. Clinical significance of monitoring ESR1 mutations in circulating cell-free DNA in estrogen receptor positive breast cancer patients

    PubMed Central

    Takeshita, Takashi; Yamamoto, Yutaka; Yamamoto-Ibusuki, Mutsuko; Inao, Toko; Sueta, Aiko; Fujiwara, Saori; Omoto, Yoko; Iwase, Hirotaka

    2016-01-01

    Background The measurement of circulating cell-free DNA (cfDNA) may transform the management of breast cancer patients. We aimed to investigate the clinical significance of sequential measurements of ESR1 mutations in primary breast cancer (PBC) and metastatic breast cancer (MBC) patients. Results ESR1 mutations ratio in the PBC groups was used as the minimum cutoff for determining increases in cfDNA ESR1 mutation ratio. An increase in cfDNA ESR1 mutations was found in 13 samples of cfDNA from 12 (28.6%) out of 42 MBC patients. A total of 10 (83.3%) out of 12 MBC patients with increase cfDNA ESR1 mutations showed a poor response to treatment. In survival analysis, increase cfDNA ESR1 mutations may predict a shorter duration of post-endocrine-therapy effectiveness (P = 0.0033). Methods A total of 119 patients (253 plasma samples) with breast carcinoma were enrolled in this study. Cases were selected if archival plasma samples were available from PBC before and after treatment and from MBC gathered more than twice at the time of progression. cfDNA was isolated from the 77 PBC patients (154 plasma samples) and from the 42 MBC patients (99 plasma samples). To investigate any changes in each cfDNA ESR1 mutation before and after treatment, we analyzed the difference with cfDNA ESR1 mutations ratio in the first blood sample using droplet digital polymerase chain reaction (ddPCR). Conclusions We demonstrate that ddPCR monitoring of the recurrent ESR1 mutation in cfDNA of MBC patients is a feasible and useful method of providing relevant predictive information. PMID:27102299

  14. Study of OSL in NaF: Ca,Cu

    NASA Astrophysics Data System (ADS)

    More, Y. K.; Wankhede, S. P.; Moharil, S. V.

    2013-06-01

    Sodium Fluoride containing Cu+ ions was prepared by R.A.P. followed by melt-quenching technique. Results on photo, thermo and optically stimulated luminescence in NaF:Ca,Cu are reported. OSL sensitivity of NaF:Ca,Cu is approximately 2 times than that of standard phosphor LMP. The rate of OSL depletion for 90% decay for NaF:Ca,Cu is 0.3 times as that of OSL phosphor LMP. NaF:Ca,Cu thus deserves much more attention than it has received up till now.

  15. ESR dating of barite in sulphide deposits formed by the sea-floor hydrothermal activities.

    PubMed

    Toyoda, Shin; Fujiwara, Taisei; Uchida, Ai; Ishibashi, Jun-ichiro; Nakai, Shun'ichi; Takamasa, Asako

    2014-06-01

    Barite is a mineral newly found to be practically useful for electron spin resonance (ESR) dating of sulphide deposits formed by the sea-floor hydrothermal activities. The recent studies for the properties of the ESR dating signal in barite are summarised in the present paper as well as the formulas for corrections for accurate dose-rate estimation are developed including the dose-rate conversion factors, shape correction for gamma-ray dose and decay of (226)Ra. Although development of the techniques for ESR dating of barite has been completed, further comparative studies with other dating techniques such as U-Th and (226)Ra-(210)Pb dating are necessary for the technique to be widely used.

  16. ESR of copper and iron complexes with antitumor and cytotoxic properties.

    PubMed

    Antholine, W E; Kalyanaraman, B; Petering, D H

    1985-12-01

    The relatively few iron and copper metal complexes which have been examined in cells and tissues for their redox properties, radical generation properties, and antitumor activity are discussed for studies which utilized electron spin resonance spectroscopy (ESR). A common property of a number of metal complexes, which include bleomycin, adriamycin, and thiosemicarbazones described in this review, is that they are readily reduced by thiol compounds and oxidized by oxygen or reduced species of oxygen to produce radicals. Structural features of these reactions are identified by ESR spectroscopy in model systems and often in cells. Furthermore, ESR spectroscopy has been most useful to probe the environment of the complexes in cells and to measure the rate of reduction of their oxidized forms. As a result of these studies, it is anticipated that more attention will be given to the exploration of redox-active metal complexes as drugs.

  17. ESR of copper and iron complexes with antitumor and cytotoxic properties.

    PubMed Central

    Antholine, W E; Kalyanaraman, B; Petering, D H

    1985-01-01

    The relatively few iron and copper metal complexes which have been examined in cells and tissues for their redox properties, radical generation properties, and antitumor activity are discussed for studies which utilized electron spin resonance spectroscopy (ESR). A common property of a number of metal complexes, which include bleomycin, adriamycin, and thiosemicarbazones described in this review, is that they are readily reduced by thiol compounds and oxidized by oxygen or reduced species of oxygen to produce radicals. Structural features of these reactions are identified by ESR spectroscopy in model systems and often in cells. Furthermore, ESR spectroscopy has been most useful to probe the environment of the complexes in cells and to measure the rate of reduction of their oxidized forms. As a result of these studies, it is anticipated that more attention will be given to the exploration of redox-active metal complexes as drugs. PMID:2420582

  18. Effects of high-temperature annealing on ESR properties of solid solutions of garnet minerals

    NASA Astrophysics Data System (ADS)

    Gundu Rao, T. K.; Cano, Nilo F.; Chubaci, Jose F. D.; Watanabe, S.

    2016-04-01

    A garnet (G7) silicate mineral belonging to pyralspite subgroup was studied using the technique of electron spin resonance (ESR). This study shows that iron is present in G7 as isolated species as well as species coupled by dipolar interactions. The ESR data shows a gradual increase of cluster of Fe3+ ions accompanied by decrease of dipolar interactions and increase of possible exchange interactions at high temperature. The Fe2+→Fe3+ oxidation process occurs in the garnets as a function of annealing temperature. Thermoluminescence (TL) peaks at approximately 190 and 340 °C are observed in the irradiated G7 garnet. Investigations using the technique of ESR were carried out to identify the centers involved in the TL process.

  19. Positron lifetime studies of decomposition in 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) alloys

    SciTech Connect

    Dlubek, G. |; Lademann, P.; Krause, H.; Krause, S.; Unger, R.

    1998-09-04

    In the current paper, the decomposition behavior of the engineering alloys 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) is studied using positron lifetime measurements. Positrons probe open volume defects such as vacancies and dislocations. However, they may also be used to investigate coherent zones and incoherent precipitates. In order to understand the rather complicated precipitation sequences and the response of positrons to different type of precipitates occurring in 2024 and 7010 alloys, binary and ternary laboratory alloys were also investigated under the same experimental conditions as the engineering alloys. The interpretations of the results are based on experiences of the group from extensive positron studies of laboratory alloys such as Al-Zn, Al-Zn-Mg, Al-Cu, and further Al alloys (see also the review (4)). Their collected results are shown as lifetimes and curve-shape parameters S of the electron-positron momentum distribution curves characteristic for different precipitates in Al alloys.

  20. First-principles study for ferromagnetism of Cu-doped ZnO with carrier doping

    SciTech Connect

    Kang, Byung-Sub; Kim, Kyeong-Sup; Yu, Seong-Cho; Chae, Heejoon

    2013-02-15

    We studied the effects on the ferromagnetism of carrier doping in Zn{sub 1-x}Cu{sub x}O with x=0.0277-0.0833 by using the first-principles calculations. The total magnetic moment of Cu is about 1, 2, and 3 {mu}{sub B}/cell at the concentration of 2.77%, 5.55%, and 8.33%, respectively. For Zn{sub 1-x}Cu{sub x}O{sub 1-y}N{sub y}, we obtained the ferromagnetic and half-metallic ground state. The Cu magnetic moment in low Cu concentration is increased by the N-doping. However, for the F-doping it decreases. The ferromagnetism in Cu-doped ZnO is controllable by changing the carrier density. The N 2p states hybridize well with Cu 3d states instead of the O 2p states. Due to the hybridization between N 2p and Cu 3d states, the holes are itinerant with keeping its 3d states. For (Cu,N)-codoped ZnO, it is recognized that the width of 3d states is larger than that of (Cu,F)-codoped ZnO. - Graphical abstract: Considered clean wurtzite ZnO structure, the Cu magnetic moments for Zn{sub 1-x}Cu{sub x}O{sub 1-y}N{sub y} or Zn{sub 1-x}Cu{sub x}O{sub 1-y}F{sub y} of the ferromagnetic state (left), and the charge density difference of Zn{sub 1-x}Cu{sub x}O (x=0.0277) (right). Highlights: Black-Right-Pointing-Pointer The ferromagnetism of Cu-doped ZnO is controllable by N or F carrier density. Black-Right-Pointing-Pointer The Cu magnetic moment in low Cu concentration is increased by hole doping. Black-Right-Pointing-Pointer The N 2p states hybridize well with the Cu 3d states instead of the O 2p states. Black-Right-Pointing-Pointer For (Cu,F)-codoped ZnO, the Cu 3d band is narrower than that for (Cu,N)-codoped ZnO.

  1. Synthesis, characterization, antimicrobial, DNA binding and cleavage studies of mixed ligand Cu(II), Co(II) complexes.

    PubMed

    Leela, D Shiva; Ushaiah, B; Anupama, G; Sunitha, M; Kumari, C Gyana

    2015-01-01

    The mixed ligand complexes MLA of Cu(II) and Co(II) with Schiff base derived from 4-amino antipyrine and 5-NO(2) salicylaldehyde (2,3 -dimethyl-1-phenyl-4-(2-hydroxy-5-nitro benzylideneamino)-pyrazol-5-one) as ONO donor (L) and A = 2,2 bipyridine (bpy),1,10 phenonthroline (1,10 phen) as N, N donor ligands have been prepared, owing to their biological and other applications. The structural features have arrived from their elemental analyses, magnetic susceptibility, molar conductance, Mass, IR, UV-VIS, powdered XRD and ESR spectral studies, that established MLA type of composition for the metal complexes. The electronic absorption spectral data of the complexes suggest an octahedral geometry around the central metal ion. The interaction of the complexes with Calf Thymus (CT) DNA has been studied using absorption spectra, viscosity measurements and fluorescence spectra. The binding constants (K(b)) of the complexes were determined as 2.1 × 10(6) M(-1) for complex 1, 2.5x10(6)M(-1) for complex 2, 1.16 × 10(6) M(-1) for complex 3,1.25x10(6)M(-1) for complex 4, DNA cleavage experiments performed on pBR-322 plasmids using metal complexes in the presence of H(2)O(2) showed that all the complexes afford a pronounced DNA cleavage. Molecular modelling studies were also performed to confirm the geometries of the complexes. The ligand and their metal complexes were screened for their antimicrobial activity against bacteria. The results showed that the metal complexes are biologically active. PMID:25548074

  2. ESR response of phenol compounds for dosimetry of gamma photon beams

    NASA Astrophysics Data System (ADS)

    Marrale, M.; Longo, A.; Panzeca, S.; Gallo, S.; Principato, F.; Tomarchio, E.; Parlato, A.; Buttafava, A.; Dondi, D.; Zeffiro, A.

    2014-11-01

    In the present paper we investigate the features of IRGANOX® 1076 phenols as a material for electron spin resonance (ESR) dosimetry. We experimentally analyzed the ESR response of pellets of IRGANOX® 1076 phenols irradiated with 60Co photons. The best experimental parameters (modulation amplitude and microwave power) for dosimetric applications have been obtained. The dependence of ESR signal as function of γ dose is found to be linear in the dose range studied (12-60 Gy) and the lowest measurable dose is found to be of the order of 1 Gy. The signal after irradiation is very stable in the first thirty days. From the point of view of the tissue equivalence, these materials have mass energy absorption coefficient values comparable with those of soft tissue.

  3. Weak ferromagnetic behavior, crystal structure, and electronic studies of novel [Cu(II)(Br)(PhCO 2)(Sp)] (Sp=(-)-sparteine) complex

    NASA Astrophysics Data System (ADS)

    Reyes-Ortega, Yasmi; Alcántara-Flores, José Luis; Hernández-Galindo, María del Carmen; Gutiérrez-Pérez, René; Ramírez-Rosales, Daniel; Bernès, Sylvain; Cabrera-Vivas, Blanca Martha; Durán-Hernández, Alejandro; Zamorano-Ulloa, Rafael

    2006-05-01

    Complex [Cu(II)(Br)(PhCO 2)(Sp)] 1 is obtained starting from copper(0), (-)-sparteine (sp) and benzoyl bromide. 1 Crystallizes in the monoclinic space group P2 1 with a=14.8857(11), b=8.9257(9), c=17.4456(14) Å, β=111.689(5)°, and Z=4. The UV-vis spectrum is characteristic of Cu(II) complexes with tetragonally distorted square pyramidal geometry. The far IR spectrum of 1 shows characteristic vibrations of Cu-Br (239 cm -1), Cu-N (437 cm -1) and Cu-O (466 cm -1) bonds. The 1H NMR broad chemical shifts of 1 integrated for a total of 31 protons and are typical of Cu(II) complexes. ESR spectra of polycrystalline 1 at 77 and 300 K show axial spectra with areas in the ratio A77/ A300=4.02, suggesting a very weak Cu-Cu ferromagnetic interaction. Complex 1-doped with Zn(II) gives hfs with hyperfine interaction constant value A∥=112.45×10 -4 cm -1. The magnetization vs temperature data in the 2-299 K range, show that cupric ion pairs interact through a small antiferromagnetic Heisenberg exchange energy— JS1· S2 with a ground singlet state S=0, separated by J=-1.3 cm -1 from the excited triplet state S=1. The sign of the very weak interchange interaction constant, J, does not agree with the ESR spectra areas ratio of 1 at 77 and 300 K, which is a more accurate quantification of the weak ferromagnetic interaction Cu-Cu through the space.

  4. Role of defects in radiation chemistry of crystalline organic materials. 3. Geometrical and electronic structures of alkene radical anion and cation in alkene/n-alkane mixed crystals as studied by ESR spectroscopy

    SciTech Connect

    Matsuura, Kaoru; Muto, Hachizo; Nunome, Keichi )

    1991-11-14

    An ESR study has been made in order to elucidate the electronic structures of alkene radical anions and cations, the former radicals being first detected in the hexene/n-hexene mixed crystals irradiated at 4.2 K along with the cation. The present work extended to the hexene and butene isomers has resulted in evidence that both anions with vinylene and vinylidene groups have pyramidal structures with {sigma}-character, which differ from the planar or twisted structures of corresponding cations. The proton hyperfine couplings of their anions were only about one-third as large as those for the cations: {vert bar}A{vert bar}(two {alpha}-H) = {vert bar}0.45, 0.1, {minus}0.25{vert bar} mT; a (two pairs of {beta}-H) = 1.38 and 0.56 mT for the 3-hexene anion, and a(two {alpha}-H) = 1.3 mT and a(two pairs of {beta}-H) = 4.6 and 2.9 mT for the cation. The differences in the geometrical structures and in the sizes of the proton couplings of the anion and cation radicals were discussed on the basis of a simple molecular orbital calculation. It has been found that the anion is stabilized by admixing {vert bar}2s;C> atomic orbitals (AO) with a lower core integral than {vert bar}2p;C> AO to the unpaired electron orbital and that the small {beta}-proton couplings mainly originate from low extent of hyperconjugation due to a wide energy separation of C{double bond}C {pi}-antibonding and C-H pseudo-{pi}-bonding orbitals.

  5. Characterization of thermally separated poly (alkylene glycol) polymer quenchants by ESR spectroscopy

    SciTech Connect

    McLeod, D. Jr.; Totten, G.E.; Webster, G.M.

    1996-12-31

    Poly(alkylene glycol) - PAG copolymers are the most commonly used polymer quenchants in the world today. One of the distinguishing and advantageous features of these polymers is their ability to undergo thermal separation. This may occur at the hot metal interface during quenching or in solution as a means of recycling contaminated quench baths. In this paper, the use of electron spin resonance (ESR) spectroscopy to characterize PAG polymers that have been thermally separated from aqueous solution will be reported. Exploratory studies using ESR spectroscopy to characterize thermally separated polymer films during quenching will also be reported.

  6. A computational study on N2 adsorption in Cu-ZSM-5.

    PubMed

    Morpurgo, Simone; Moretti, Giuliano; Bossa, Mario

    2007-01-21

    The present computational study investigates the adsorption of N(2) by Cu-ZSM-5, with particular regard to the interaction with pairs of Cu(+) ions, employing simple cluster models in the calculations. It shows that several interaction patterns between N(2) and couples of Cu(+) sites are possible within the Cu-ZSM-5 structure. In particular, when pairs of Cu(+) ions are located at opposite sides of ten-membered rings, in the region where linear and sinusoidal channels intersect each other, a quasi-linear Cu-N-N-Cu adsorption occurs. Although lattice restraints cause small deviations from linearity, such interaction turned out to be more favourable than other adsorption patterns within the Cu-ZSM-5 structure. The linearity of the Cu-N-N-Cu fragment and the relatively low concentration of the related sites cause a low extinction coefficient for the N-N IR stretching mode, which is usually detected with very low intensity or not detected at all. The results of the present calculations may explain the experimental evidence for a nearly IR-silent fraction of nitrogen strongly adsorbed in the Cu-ZSM-5 catalyst which, as shown in a previous work, is linearly related to the number of active sites for NO decomposition.

  7. A Cu NQR study in a d-electron heavy-fermion system, CaCu3Ru4O12

    NASA Astrophysics Data System (ADS)

    Kato, Harukazu; Tsuruta, Takuya; Nishioka, Takashi; Matsumura, Masahiro; Sakai, Hironori; Kambe, Shinsaku

    2007-11-01

    Cu nuclear quadrupole resonance (NQR) studies have been carried out for CaCu3Ru4O12, which has been suggested to show a heavy-fermion-like behavior although it possess no f electron. A Lorentzian shape of the Cu NQR line with a narrow width implies that no magnetic ordering appears, at least, down to 5 K. The spin lattice relaxation rate of the Cu nuclei probes a change of the Cu 3d electron nature, resulting in the Fermi liquid state at a low temperature. These facts strongly support that the heavy fermion picture is available in the concerned compound.

  8. Incidence and clinical significance of ESR1 mutations in heavily pretreated metastatic breast cancer patients

    PubMed Central

    Niu, Jiaxin; Andres, Grant; Kramer, Kim; Kundranda, Madappa N; Alvarez, Ricardo H; Klimant, Eiko; Parikh, Ankur R; Tan, Bradford; Staren, Edgar D; Markman, Maurie

    2015-01-01

    Background ESR1 mutation has recently emerged as one of the important mechanisms involved in endocrine resistance. The incidence and clinical implication of ESR1 mutation has not been well evaluated in heavily pretreated breast cancer patients. Methods We conducted a retrospective review of advanced breast cancer patients with tumors who underwent next-generation sequencing genomic profiling using Foundation One test at Cancer Treatment Centers of America® regional hospitals between November 2012 and November 2014. Results We identified a total of 341 patients including 217 (59%) estrogen receptor (ER)+, 177 (48%) progesterone receptor (PR)+, 30 (8%) hormone receptor+/HER2 positive, and 119 (32%) triple negative patients. ESR1 mutation was noted in 27/222 (12.1%) ER+ or PR+ breast cancer patients. All ER+ patients received at least one line of an aromatase inhibitor. All 28 patients were found to harbor ESR1 mutations affecting ligand-binding domain with the most common mutations affecting Y537 (17/28, 60.7%) and D538 (9/28, 32.1%). In this cohort, 19 (67.9%) patients carried three or more, seven (25%) patients had one or two additional genomic alterations and one (3.6%) patient had an ESR1 mutation only. Of 28 patients, three patients were treated with fulvestrant immediately before and two patients were treated after next-generation sequencing testing; only one patient achieved stable disease for 8 months and the other four patients had progression of disease. In all, 3/3 (100%) patients before testing and 2/4 (50%) after testing treated with exemestane and everolimus achieved stable disease for at least 6 months. Conclusion ESR1 mutation was found in 12.1% of a large cohort of advanced breast cancer patients. Exemestane in combination with everolimus might be a reasonable option. Prospective studies are warranted to validate these findings. PMID:26648736

  9. Synthesis, spectral characterization and antioxidant activity studies of a bidentate Schiff base, 5-methyl thiophene-2-carboxaldehyde-carbohydrazone and its Cd(II), Cu(II), Ni(II) and Zn(II) complexes

    NASA Astrophysics Data System (ADS)

    Harinath, Y.; Harikishore Kumar Reddy, D.; Naresh Kumar, B.; Apparao, Ch.; Seshaiah, K.

    2013-01-01

    A new Schiff base bidentate ligand (L), 5-methyl thiophene-2-carboxaldehyde-carbohydrazone and its metal (Cu(II), Cd(II), Ni(II) and Zn(II)) complexes with general stoichiometry [M(L)2X2] (where X = Cl) were synthesized. The ligand and its metal complexes were characterized by elemental analyses, IR, 1H NMR, ESR spectral analyses, and molar conductance studies. The molar conductance data revealed that all the metal chelates are non-electrolytes. IR spectra showed that ligand (L) is coordinated to the metal ions in a bidentate manner with N and O donor sites of the azomethine-N, and carbonyl-O. ESR and UV-Vis spectral data showed that the geometrical structure of the complexes are Orthorhombic. Furthermore, the antioxidant activity of the ligand and its complexes was determined by hydroxyl radical scavenging, DPPH, NO, reducing power methods in vitro. The obtained IC50 value of the DPPH activity for the copper complex (IC50 = 66.4 μm) was higher than other compounds. Microbial assay of the above complexes against Staphylococcus aureus, Escherichia coli, Rhizocotonia bataticola and Alternaria alternata showed that copper complex exhibited higher activity than the other complexes.

  10. First principles study of CuAlO2 doping with S

    NASA Astrophysics Data System (ADS)

    Gao, Haigen; Zhou, Jian; Lu, Minghui

    2010-07-01

    We study the electronic properties of CuAlO2 doped with S by the first principles calculations and find that the band gap of CuAlO2 is reduced after the doping. At the same time, the effective masses are also reduced and the density of states could cross the Fermi level. These results show that the conductivity of CuAlO2 could be enhanced by doping the impurities of S, which needs to be further studied.

  11. Gamma radiation effects on seed germination, growth and pigment content, and ESR study of induced free radicals in maize (Zea mays).

    PubMed

    Marcu, Delia; Damian, Grigore; Cosma, Constantin; Cristea, Victoria

    2013-09-01

    The effects of gamma radiation are investigated by studying plant germination, growth and development, and biochemical characteristics of maize. Maize dry seeds are exposed to a gamma source at doses ranging from 0.1 to 1 kGy. Our results show that the germination potential, expressed through the final germination percentage and the germination index, as well as the physiological parameters of maize seedlings (root and shoot lengths) decreased by increasing the irradiation dose. Moreover, plants derived from seeds exposed at higher doses (≤0.5 kGy) did not survive more than 10 days. Biochemical differences based on photosynthetic pigment (chlorophyll a, chlorophyll b, carotenoids) content revealed an inversely proportional relationship to doses of exposure. Furthermore, the concentration of chlorophyll a was higher than chlorophyll b in both irradiated and non-irradiated seedlings. Electron spin resonance spectroscopy used to evaluate the amount of free radicals induced by gamma ray treatment demonstrates that the relative concentration of radiation-induced free radicals depends linearly on the absorbed doses.

  12. Application of high resolution NMR, ESR, and gamma-ray scintillation spectroscopy to the study of ligand binding in proteins. [Torpedo californica

    SciTech Connect

    Lancione, G.V.

    1982-01-01

    Electron spin resonance spectroscopy has been employed to study the nature of the ligand binding site of alpha-1-antitrypsin. Spectra of spin-labeled alpha-1-antitrypsin were recorded at pH's ranging from 2.4 to 12.5. This data demonstrates the tight binding of the spin-label to the protease, and the sensitivity of the bound spin-label to informational changes in the protease inhibitor. A molecular dipstick approach has also been applied to this system and has yielded information on the geometry of the cleft accommodating the spin-label. /sup 160/Terbium(III) exchange experiments have been performed on the acetylcholine receptor protein isolated from Torpedo californica, employing a specially designed flow dialysis apparatus constructed in the laboratory. The apparatus is designed to allow continuous monitoring of /sup 160/Tb(III) gamma-ray emission from the protein compartment of the flow dialysis cell. Nicotinic ligand-induced displacement of /sup 160/Tb(III) from the nicotinic binding site of the receptor was monitored as a funtion of (1) the concentration of nicotinic ligand in the washout buffer, and (2) the nature of the nicotinic ligand in the buffer. Measured /sup 160/Tb(III) exchange half-lives indicate (1) a direct relationship between /sup 160/Tb(III) displacement and nicotinic ligand concentration in the wash-out buffer, and (2) an enhanced /sup 160/Tb(III) displacement for nicotinic agents possessing quaternary ammonium functions.

  13. In situ radiolysis time-resolved ESR studies of spin trapping by DMPO: Re-evalution of hydroxyl radical and hydrated electron trapping rates and spin adduct yields

    SciTech Connect

    Madden, K.P.; Taniguchi, Hitoshi

    1996-05-02

    The second-order rate constants for the reaction of 5, 5-dimethyl-1-pyrroline N-oxide (DMPO) with radiolytically produced hydroxyl radicals and hydrated electrons have been measured in aqueous solution by direct observation of spin adduct initial yield using time-resolved electron spin resonance. The rate constants are 2.8 x 10{sup 9} mol{sup -1} dm{sup 3} S{sup -1} for the DMPO-hydroxyl radical reaction and 3.2 x 10{sup 9} mol{sup -1} dm{sup 3} s{sup -1} for the reaction of DMPO and hydrated electron, using sodium formate and chloroacetic acid as competitive scavengers of the hydroxyl radical and hydrated electron, respectively. The hydrated electron-DMPO competition study determined the fraction of DMPO-H produced directly from radiolytically produced hydrogen atoms as 0.082 of the total DMPO-H yield, indicating that approximately half of the hydrogen atoms react with DMPO to produce non-aminoxyl products. The fraction of the total hydroxyl radical yield leading to DMPO-OH spin adduct was determined to be 0.94, using the bleach of 2,2,6,6-tetramethylpiperidone-N-oxyl by carbon dioxide radical anion as a reference standard. 36 refs., 8 figs., 1 tab.

  14. An in situ radiolysis time-resolved ESR study of the kinetics of spin trapping by 5,5-dimethyl-1-pyrroline-N-oxide

    SciTech Connect

    Taniguchi, Hitoshi; Madden, K.P.

    1999-12-22

    The authors have measured the reaction rate constants of the nitrone spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) with a number of small alkyl and {sigma} parent radicals in dilute aqueous solution using in situ radiolysis time-resolved electron spin resonance spectroscopy. Unsubstituted alkyl parent radicals (methyl, ethyl, propyl, and 1-methylethyl (2-propyl)) had rate constants ranging from 5.6 x 10{sup 6} to 1.6 x 10{sup 7} M{sup {minus}1} s{sup {minus}1}. Electron-releasing {alpha}-hydroxyalkyl radicals (hydroxymethyl, 1-hydroxyethyl, 1-hydroxypropyl, and 1-hydroxy-1-methylethyl (2-hydroxy-2-propyl)) reacted more rapidly than the unsubstituted radicals with rate constants of (2.2--6.8) x 10{sup 7} M{sup {minus}1} s{sup {minus}1}, while the electron-withdrawing carboxymethyl radical was slower (4.4 x 10{sup 6} M{sup {minus}1} s{sup {minus}1}). The bulky 2-hydroxy-2-methylpropyl radical reacted with DMPO, but with a rate constant smaller than 10{sup 6} M{sup {minus}1} s{sup {minus}1}. {Sigma} radicals such as sulfite anion and carboxyl anion were trapped quickly, with rate constants of 1.2 x 10{sup 7} and 6.6 x 10{sup 7} M{sup {minus}1} s{sup {minus}1}, respectively. These results show that the zwitterionic structure of DMPO results in sensitivity to polar effects in the parent radical-spin trap encounter complex, while steric effects are also influential in the reaction of DMPO with bulky alkyl radicals. The rate constants for the reaction of DMPO with the radicals studied herein are, in general, an order of magnitude slower than the same radicals reacting with the nitroso spin trap 2-methyl-2-nitrosopropane.

  15. Unusual narrowing of the ESR line width in ordered structures with linear chains of Ge/Si quantum dots

    NASA Astrophysics Data System (ADS)

    Zinovieva, A. F.; Smagina, Zh. V.; Nenashev, A. V.; Kulik, L. V.; Dvurechenskii, A. V.

    2015-07-01

    Electron states in ordered Ge/Si heterostructures with linear chains of quantum dots (QDs) were studied by the electron spin resonance (ESR) method. A new ESR signal with principal g-factor values g zz = 1.9993 ± 0.0001, g xx = g yy = 1.9990 ± 0.0001 was detected. Unlike disordered QD structures, where ESR line broadening is usually observed (evidence of Dyakonov-Perel mechanism efficiency), the structures under study demonstrate the narrowing of ESR line when the external magnetic field deviates from the growth direction. The ESR line width is Δ H = 1.2 Oe for perpendicular magnetic field (along the growth direction) and Δ H = 0.8 Oe for in-plane magnetic field. The narrowing of ESR line can be explained by combination of two mechanisms. The first one is suppression of Dyakonov-Perel spin relaxation due to a settled direction of electron motion and finiteness of QD chains. The second one is cancelation of the wavefunction shrinking effect with decreasing the perpendicular component of the magnetic field.

  16. Droplet digital polymerase chain reaction assay for screening of ESR1 mutations in 325 breast cancer specimens.

    PubMed

    Takeshita, Takashi; Yamamoto, Yutaka; Yamamoto-Ibusuki, Mutsuko; Inao, Toko; Sueta, Aiko; Fujiwara, Saori; Omoto, Yoko; Iwase, Hirotaka

    2015-12-01

    Droplet digital polymerase chain reaction (ddPCR), which could perform thousands of PCRs on a nanoliter scale simultaneously, would be an attractive method to massive parallel sequencing for identifying and studying the significance of low-frequency rare mutations. Recent evidence has shown that the key potential mechanisms of the failure of aromatase inhibitors-based therapy involve identifying activating mutations affecting the ligand-binding domain of the ESR1 gene. Therefore, the detection of ESR1 mutations may be useful as a biomarker predicting an effect of the treatment. We aimed to develop a ddPCR-based method for the sensitive detection of ESR1 mutations in 325 breast cancer specimens, in which 270 primary and 55 estrogen receptor-positive (ER+) metastatic breast cancer (MBC) specimens. Our ddPCR assay could detect the ESR1 mutant molecules with low concentration of 0.25 copies/μL. According to the selected cutoff, ESR1 mutations occurred in 7 (2.5%) of 270 primary breast cancer specimens and in 11 (20%) of 55 ER+ MBC specimens. Among the 11 MBC specimens, 5 specimens (45.5%) had the most common ESR1 mutation, Y537S, 4 specimens (36.3%) each had D538G, Y537N, and Y537C. Interestingly, 2 patients had 2 ESR1 mutations, Y537N/D538G and Y537S/Y537C, and 2 patients had 3 ESR1 mutations, Y537S/Y537N/D538G. Biopsy was performed in heterochrony in 8 women twice. In 8 women, 4 women had primary breast cancer and MBC specimens and 4 women had 2 specimens when treatment was failure. Four of these 8 women acquired ESR1 mutation, whereas no ESR1 mutation could be identified at first biopsy. ddPCR technique could be a promising tool for the next-generation sequencing-free precise detection of ESR1 mutations in endocrine therapy resistant cases and may assist in determining the treatment strategy.

  17. Co(II), Cu(II), Cd(II), Fe(III) and U(VI) complexes containing a NSNO donor ligand: Synthesis, characterization, optical band gap, in vitro antimicrobial and DNA cleavage studies

    NASA Astrophysics Data System (ADS)

    Yousef, T. A.; Abu El-Reash, G. M.; El-Gammal, O. A.; Bedier, R. A.

    2012-12-01

    A new series of [Co(HPTP)Cl(H2O)2], [Cu(HPTP)Cl], [Cd(HPTP)Cl](H2O)4, [Fe(PTP)Cl(H2O)2](H2O), [UO2(HPTP)(OAc)(H2O)2] complexes of Schiff-bases derived from 4-(2-pyridyl)-3-thiosemicarbazide and pyruvic acid (H2PTP) have been synthesized and characterized by spectroscopic studies. Schiff-base exhibit thiol-thione tautomerism wherein sulfur plays an important role in the coordination. The coordination possibility of the Schiff-bases towards metal ions have been proposed in the light of elemental analyses, spectral (IR, UV-vis, 1H NMR, 13C NMR and ESR), magnetic and thermal studies. IR spectra show that H2PTP is coordinated to the metal ions in a mono or binegative tridentate manner. The electronic spectra of the complexes and their magnetic moments provide information about geometries. The room temperature solid state ESR spectra of the Cu(II) complexes show dx2-y2 as a ground state, suggesting square-planar geometry around Cu(II) center. The molecular parameters: total energy, binding energy, isolated atomic energy, electronic energy, heat of formation, dipole moment, HOMO and LUMO were calculated for the ligand and its complexes. Furthermore, the kinetic and thermodynamic parameters for the different decomposition steps were calculated using the Coats-Redfern and Horowitz-Metzger methods. Also, the optical band gap (Eg) of the metal complexes has been calculated. The optical transition energy (Eg) is direct and equals 3.25, 3.26, 3.34 and 3.27 eV for Co, Cu, Fe and U complexes, respectively. The synthesized ligand, in comparison to its metal complexes is screened for its antibacterial activity against bacterial species, Bacillus thuringiensis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The activity data show that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species. Finally, the biochemical studies showed that, Cu, Cd and Fe complexes have powerful and complete

  18. ESR Studies of a Reorienting Nickel Complex

    NASA Astrophysics Data System (ADS)

    Kowert, Bruce

    2007-03-01

    Electron spin resonance spectra of the planar bis(maleonitriledithiolato)nickel anion radical (BMNT) in the intermediate motional region have been simulated in several polar solvents using axially symmetric reorientation. The rotational diffusion about the long in-plane axis is three to four times faster than that about the two axes perpendicular to it. The reorientational model needed to produce agreement with experiment is either in or close to the Brownian rotational diffusion limit. The solvents are 4-allyl-2-methoxyphenol (eugenol), dimethyl phthalate, tri-n-butyl phosphate, tris(2-ethyl-hexyl)phosphate, and 2-methoxyethyl ether (diglyme), ethyl alcohol, and a dimethylformamide-chloroform mixed solvent. The reorientational rates from the simulations are in general agreement with those from line width analyses carried out from the fast to the slow motional regions. The temperature dependence of the diffusion rates is discussed in terms of the Stokes-Einstein-Debye (SED) model and the Vogel-Tammann-Fulcher equation.

  19. ESR study of gamma irradiated Nylon3

    NASA Astrophysics Data System (ADS)

    Çatiker, Efkan; Güven, Olgun; Özarslan, Özdemir; Chipara, Mircea

    2013-03-01

    Nylon3 (poly-β-alanine) gamma irradiated in nitrogen was investigated by Electron Spin Resonance Spectroscopy to elucidate the type of radicals generated, their relative abundance, conversion into other radicalic species and their room temperature stability. Two types of radiation induced primary radicals have been detected. One of them (R1) occurs by hydrogen abstraction from methylene group next to the carbonyl group, while the other (R2) by hydrogen abstraction from methylene group next to amide group. R1 is observed to be converted into an alkoxy radical (R3). Decay kinetics of the radicals in nitrogen was also examined and decay mechanisms have been proposed for each radical.

  20. Origin of electrically heterogeneous microstructure in CuO from scanning tunneling spectroscopy study

    NASA Astrophysics Data System (ADS)

    Sarkar, Sudipta; Jana, Pradip Kumar; Chaudhuri, B. K.

    2008-04-01

    We report electronic structure of the grains and grain boundaries (GBs) of the high permittivity (κ˜104) ceramic CuO from scanning tunneling spectroscopy (STS) studies. The p-type semiconducting character of the CuO grains and insulating behavior of the corresponding GBs, observed from STS studies, have been explained. This type of electrically inhomogeneous microstructure leads to the formation of barrier layer capacitance elements in CuO and, hence, provides an explanation of the colossal-κ response exhibited by CuO.

  1. Study of Cu and Pb partitioning in mine tailings using the Tessier sequential extraction scheme

    SciTech Connect

    Andrei, Mariana Lucia; Senila, Marin; Hoaghia, Maria Alexandra; Levei, Erika-Andrea; Borodi, Gheorghe

    2015-12-23

    The Cu and Pb partitioning in nonferrous mine tailings was investigated using the Tessier sequential extraction scheme. The contents of Cu and Pb found in the five operationally defined fractions were determined by inductively coupled plasma optical emission spectrometry. The results showed different partitioning patterns for Cu and Pb in the studied tailings. The total Cu and Pb contents were higher in tailings from Brazesti than in those from Saliste, while the Cu contents in the first two fractions considered as mobile were comparable and the content of mobile Pb was the highest in Brazesti tailings. In the tailings from Saliste about 30% of Cu and 3% of Pb were found in exchangeable fraction, while in those from Brazesti no metals were found in the exchangeable fraction, but the percent of Cu and Pb found in the bound to carbonate fraction were high (20% and 26%, respectively). The highest Pb content was found in the residual fraction in Saliste tailings and in bound to Fe and Mn oxides fraction in Brazesti tailings, while the highest Cu content was found in the fraction bound to organic matter in Saliste tailings and in the residual fraction in Brazesti tailings. In case of tailings of Brazesti medium environmental risk was found both for Pb and Cu, while in case of Saliste tailings low risk for Pb and high risk for Cu were found.

  2. Study of Cu and Pb partitioning in mine tailings using the Tessier sequential extraction scheme

    NASA Astrophysics Data System (ADS)

    Andrei, Mariana Lucia; Senila, Marin; Hoaghia, Maria Alexandra; Borodi, Gheorghe; Levei, Erika-Andrea

    2015-12-01

    The Cu and Pb partitioning in nonferrous mine tailings was investigated using the Tessier sequential extraction scheme. The contents of Cu and Pb found in the five operationally defined fractions were determined by inductively coupled plasma optical emission spectrometry. The results showed different partitioning patterns for Cu and Pb in the studied tailings. The total Cu and Pb contents were higher in tailings from Brazesti than in those from Saliste, while the Cu contents in the first two fractions considered as mobile were comparable and the content of mobile Pb was the highest in Brazesti tailings. In the tailings from Saliste about 30% of Cu and 3% of Pb were found in exchangeable fraction, while in those from Brazesti no metals were found in the exchangeable fraction, but the percent of Cu and Pb found in the bound to carbonate fraction were high (20% and 26%, respectively). The highest Pb content was found in the residual fraction in Saliste tailings and in bound to Fe and Mn oxides fraction in Brazesti tailings, while the highest Cu content was found in the fraction bound to organic matter in Saliste tailings and in the residual fraction in Brazesti tailings. In case of tailings of Brazesti medium environmental risk was found both for Pb and Cu, while in case of Saliste tailings low risk for Pb and high risk for Cu were found.

  3. Synthesis, spectral, antitumor, antioxidant and antimicrobial studies on Cu(II), Ni(II) and Co(II) complexes of 4-[(1H-Benzoimidazol-2-ylimino)-methyl]-benzene-1,3-diol

    NASA Astrophysics Data System (ADS)

    El-wakiel, Nadia; El-keiy, Mai; Gaber, Mohamed

    2015-08-01

    A new Schiff base of 2-aminobenzimidazole with 2,4-dihydroybezaldehyde (H3L), and its Cu(II), Ni(II) and Co(II) complexes have been synthesized and characterized by elemental analyses, molar conductance, thermal analysis (TGA), inductive coupled plasma (ICP), magnetic moment measurements, IR, EI-mass, UV-Vis. and ESR spectral studies. On the basis of spectral studies and analytical data, it is evident that the Schiff base acts as dibasic tridentate ligand coordinating via deprotonated OH, NH and azomethine nitrogen atom. The results showed that Co(II) and Ni(II) complexes have tetrahedral structure while Cu(II) complexes has octahedral geometry. The kinetic and thermodynamic parameters of the thermal decomposition stages have been evaluated. The studied complexes were tested for their in vitro antimicrobial activities against some bacterial strains. The anticancer activity of the ligand and its metal complexes is evaluated against human liver Carcinoma (HEPG2) cell. These compounds exhibited a moderate and weak activity against the tested HEPG2 cell lines with IC50 of 9.08, 18.2 and 19.7 μg/ml for ligand, Cu(II) and Ni(II) complexes, respectively. In vitro antioxidant activity of the newly synthesized compounds has also been evaluated.

  4. Studies on the active site of pig plasma amine oxidase.

    PubMed Central

    Collison, D; Knowles, P F; Mabbs, F E; Rius, F X; Singh, I; Dooley, D M; Cote, C E; McGuirl, M

    1989-01-01

    Amine oxidase from pig plasma (PPAO) has two bound Cu2+ ions and at least one pyrroloquinoline quinone (PQQ) moiety as cofactors. It is shown that recovery of activity by copper-depleted PPAO is linear with respect to added Cu2+ ions. Recovery of e.s.r. and optical spectral characteristics of active-site copper parallel the recovery of catalytic activity. These results are consistent with both Cu2+ ions contributing to catalysis. Further e.s.r. studies indicate that the two copper sites in PPAO, unlike those in amine oxidases from other sources, are chemically distinct. These comparative studies establish that non-identity of the Cu2+ ions in PPAO is not a requirement for amine oxidase activity. It is shown through the use of a new assay procedure that there are two molecules of PQQ bound per molecule of protein in PPAO; only the more reactive of these PQQ moieties is required for activity. PMID:2559715

  5. NMR and ESR characterization of activated carbons produced from pecan shells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A large number of solid-state NMR and ESR experiments were explored as potential tools to study chemical structure, mobility, and pore volume of activated carbon. We used a model system where pecan shells were activated with phosphoric acid, and carbonized at 450ºC for 4 h with varying amounts of ai...

  6. Double quantum coherence electron spin resonance on coupled Cu(II)-Cu(II) electron spins

    NASA Astrophysics Data System (ADS)

    Becker, James S.; Saxena, Sunil

    2005-10-01

    We demonstrate for the first time the ability to generate double quantum coherences (DQCs) for the case of Cu(II). We show that small splittings (˜7 MHz) from the Cu(II)-Cu(II) electron-electron magnetic dipolar interaction can be reliably resolved even though the inhomogeneously broadened Cu(II) linewidth is ˜2 GHz. A Cu(II)-Cu(II) distance of 2.0 nm was measured on a model peptide system, thus, demonstrating that distances on the nanometer scale may be measured using DQC electron spin resonance (ESR).

  7. EPR and optical absorption study of Cu2+ doped lithium sulphate monohydrate (LSMH) single crystals

    NASA Astrophysics Data System (ADS)

    Sheela, K. Juliet; Krishnan, S. Radha; Shanmugam, V. M.; Subramanian, P.

    2016-05-01

    EPR study of Cu2+ doped NLO active Lithium Sulphate monohydrate (Li2SO4.H2O) single crystals were grown successfully by slow evaporation method at room temperature. The principal values of g and A tensors indicate existence of orthorhombic symmetry around the Cu2+ ion. From the direction cosines of g and A tensors, the locations of Cu2+ in the lattice have been identified as interstitial site. Optical absorption confirms the rhombic symmetry and ground state wave function of the Cu2+ ion in a lattice as dx2-y2.

  8. SDSL-ESR-based protein structure characterization.

    PubMed

    Strancar, Janez; Kavalenka, Aleh; Urbancic, Iztok; Ljubetic, Ajasja; Hemminga, Marcus A

    2010-03-01

    As proteins are key molecules in living cells, knowledge about their structure can provide important insights and applications in science, biotechnology, and medicine. However, many protein structures are still a big challenge for existing high-resolution structure-determination methods, as can be seen in the number of protein structures published in the Protein Data Bank. This is especially the case for less-ordered, more hydrophobic and more flexible protein systems. The lack of efficient methods for structure determination calls for urgent development of a new class of biophysical techniques. This work attempts to address this problem with a novel combination of site-directed spin labelling electron spin resonance spectroscopy (SDSL-ESR) and protein structure modelling, which is coupled by restriction of the conformational spaces of the amino acid side chains. Comparison of the application to four different protein systems enables us to generalize the new method and to establish a general procedure for determination of protein structure.

  9. The aqueous reference for ESR oximetry

    NASA Astrophysics Data System (ADS)

    Diakova, Galina; Bryant, Robert G.

    2006-02-01

    The interaction of molecular oxygen with derivatives of nitroxide EPR spin labels has been investigated using nuclear spin-relaxation spectroscopy in aqueous and nonaqueous solvents. The proton spin-lattice relaxation rate induced by oxygen provides a measure of the local concentration of oxygen, which we find is dependent on solvent. In water, the hydrophobic effect increases the local concentration of oxygen in the nonpolar portions of solute molecules. For nitroxides reduced to the hydroxylamine in aqueous solutions, we find that the local concentration of oxygen is approximately twice that associated with a free diffusion hard sphere limit, while in octane, this effect is absent. These results show that nitroxide based ESR oximetry may suffer a reference concentration shift of order a factor of two if the aqueous nitroxide spectrum or relaxation is used as the reference.

  10. Recognition of malignant processes with neural nets from ESR spectra of serum albumin.

    PubMed

    Seidel, Peter; Gurachevsky, Andrey; Muravsky, Vladimir; Schnurr, Kerstin; Seibt, Günter; Matthes, Gert

    2005-01-01

    Cancer diseases are the focus of intense research due to their frequent occurrence. It is known from the literature that serum proteins are changed in the case of malignant processes. Changes of albumin conformation, transport efficiency, and binding characteristics can be determined by electron spin resonance spectroscopy (ESR). The present study analysed the binding/dissociation function of albumin with an ESR method using 16-doxyl stearate spin probe as reporter molecule and ethanol as modifier of hydrophobic interactions. Native and frozen plasma of healthy donors (608 samples), patients with malignant diseases (423 samples), and patients with benign conditions (221 samples) were analysed. The global specificity was 91% and the sensitivity 96%. In look-back samples of 27 donors, a malignant process could be detected up to 30 months before clinical diagnosis. To recognise different entities of malignant diseases from the ESR spectra, Artificial neural networks were implemented. For 48 female donors with breast cancer, the recognition specificity was 85%. Other carcinoma entities (22 colon, 18 prostate, 12 stomach) were recognised with specificities between 75% and 84%. Should these specificity values be reproduced in larger studies, the described method could be used as a new specific tumour marker for the early detection of malignant processes. Since transmission of cancer via blood transfusion cannot be excluded as yet, the described ESR method could also be used as a quality test for plasma products.

  11. Electron Spin Resonance (ESR) Dating of Calcareous Fault Gouge of the Ushikubi Fault, Central Japan.

    PubMed

    Fantong, Emilia Bi; Takeuchi, Akira; Doke, Ryosuke

    2013-01-01

    The ages of fault events of active faults have been estimated using electron spin resonance (ESR) signals of siliceous gouges. This technique of ESR method is limited by obtaining only ages that are greater than tens of millennia. So this study focuses on developing a new technique of using calcareous gouges to gain an insight into the ages of latest seismogenic event within the Holocene. For the first time, signal B of the ESR method has been used to estimate the age of the Ushikubi fault from calcareous gouge. This technique proved reliable because the mean age (1.9 ka) obtained agrees with previous works on indirect age determination of latest fault events by utilizing radiocarbon dating in the study area. However, the result from the ESR technique showed an increase relative to the age of 1 ka that was obtained by the radiocarbon dating method. This disparity may be due to a high dose rate value of 50 Gy/h of artificial irradiation that was used to determine the equivalent dose (ED). Moreover, isochronal experiment revealed that the gouge did not comprise pure carbonates but consisted of a mixture of calcite and quartz grains. A younger age value would have been obtained if a lower artificial irradiation dose rate and a relatively pure carbonate fault gouge were used in the ED determination.

  12. The use of ESR technique for assessment of heating temperatures of archaeological lentil samples.

    PubMed

    Aydaş, Canan; Engin, Birol; Dönmez, Emel Oybak; Belli, Oktay

    2010-01-01

    Heat-induced paramagnetic centers in modern and archaeological lentils (Lens culinaris, Medik.) were studied by X-band (9.3GHz) electron spin resonance (ESR) technique. The modern red lentil samples were heated in an electrical furnace at increasing temperatures in the range 70-500 degrees C. The ESR spectral parameters (the intensity, g-value and peak-to-peak line width) of the heat-induced organic radicals were investigated for modern red lentil (Lens culinaris, Medik.) samples. The obtained ESR spectra indicate that the relative number of heat-induced paramagnetic species and peak-to-peak line widths depends on the temperature and heating time of the modern lentil. The g-values also depend on the heating temperature but not heating time. Heated modern red lentils produced a range of organic radicals with g-values from g=2.0062 to 2.0035. ESR signals of carbonised archaeological lentil samples from two archaeological deposits of the Van province in Turkey were studied and g-values, peak-to-peak line widths, intensities and elemental compositions were compared with those obtained for modern samples in order to assess at which temperature these archaeological lentils were heated in prehistoric sites. The maximum temperatures of the previous heating of carbonised UA5 and Y11 lentil seeds are as follows about 500 degrees C and above 500 degrees C, respectively.

  13. The use of ESR technique for assessment of heating temperatures of archaeological lentil samples

    NASA Astrophysics Data System (ADS)

    Aydaş, Canan; Engin, Birol; Dönmez, Emel Oybak; Belli, Oktay

    2010-01-01

    Heat-induced paramagnetic centers in modern and archaeological lentils ( Lens culinaris, Medik.) were studied by X-band (9.3 GHz) electron spin resonance (ESR) technique. The modern red lentil samples were heated in an electrical furnace at increasing temperatures in the range 70-500 °C. The ESR spectral parameters (the intensity, g-value and peak-to-peak line width) of the heat-induced organic radicals were investigated for modern red lentil ( Lens culinaris, Medik.) samples. The obtained ESR spectra indicate that the relative number of heat-induced paramagnetic species and peak-to-peak line widths depends on the temperature and heating time of the modern lentil. The g-values also depend on the heating temperature but not heating time. Heated modern red lentils produced a range of organic radicals with g-values from g = 2.0062 to 2.0035. ESR signals of carbonised archaeological lentil samples from two archaeological deposits of the Van province in Turkey were studied and g-values, peak-to-peak line widths, intensities and elemental compositions were compared with those obtained for modern samples in order to assess at which temperature these archaeological lentils were heated in prehistoric sites. The maximum temperatures of the previous heating of carbonised UA5 and Y11 lentil seeds are as follows about 500 °C and above 500 °C, respectively.

  14. [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.

  15. First-principles study of carbon impurities in CuInSe{sub 2} and CuGaSe{sub 2}, present in non-vacuum synthesis methods

    SciTech Connect

    Bekaert, J. Saniz, R.; Partoens, B.; Lamoen, D.

    2015-01-07

    A first-principles study of the structural and electronic properties of carbon impurities in CuInSe{sub 2} and CuGaSe{sub 2} is presented. Carbon is present in organic molecules in the precursor solutions used in non-vacuum growth methods for CuInSe{sub 2} and CuGaSe{sub 2} based photovoltaic cells. These growth methods make more efficient use of material, time, and energy than traditional vacuum methods. The formation energies of several carbon impurities are calculated using the hybrid HSE06 functional. C{sub Cu} acts as a shallow donor, C{sub In} and interstitial C yield deep donor levels in CuInSe{sub 2}, while in CuGaSe{sub 2} C{sub Ga} and interstitial C act as deep amphoteric defects. So, these defects reduce the majority carrier (hole) concentration in p-type CuInSe{sub 2} and CuGaSe{sub 2} by compensating the acceptor levels. The deep defects are likely to act as recombination centers for the photogenerated charge carriers and are thus detrimental for the performance of the photovoltaic cells. On the other hand, the formation energies of the carbon impurities are high, even under C-rich growth conditions. Thus, few C impurities will form in CuInSe{sub 2} and CuGaSe{sub 2} in thermodynamic equilibrium. However, the deposition of the precursor solution in non-vacuum growth methods presents conditions far from thermodynamic equilibrium. In this case, our calculations show that C impurities formed in non-equilibrium tend to segregate from CuInSe{sub 2} and CuGaSe{sub 2} by approaching thermodynamic equilibrium, e.g., via thorough annealing.

  16. Characterization of structure and thermophysical properties of three ESR slags

    NASA Astrophysics Data System (ADS)

    Plotkowski, A.; deBarbadillo, J.; Krane, Matthew J. M.

    2016-07-01

    The structure and properties of electroslag remelting (ESR) slags were characterized. Slags samples of three compositions were obtained from industrial remelting processes at Special Metals Corporation and from casting in a laboratory vacuum induction melter. The structure of the slag samples was observed using optical and electron microscopy, and phases were identified and their relative amounts quantified using X-ray diffraction. Laser flash thermal diffusivity, density, and differential scanning calorimetry measurements for specific heat were performed to determine the bulk thermal conductivity of the samples. Sample porosity was measured as a function of depth using a serial sectioning technique, and a onedimensional computational model was developed to estimate the thermal conductivity of the fully dense slags. These results are discussed in context with previous studies, and opportunities for future research are identified. AFRL Case Number: 88ABW-2015-1871.

  17. ESR dating of tooth enamel from yunxian homo erectus site, China

    NASA Astrophysics Data System (ADS)

    Chen, Tie-Mei; Yang, Quan; Hu, Yan-Qiu; Bao, Wen-Bo; Li, Tian-Yuan

    Two almost complete fossil hominid crania (EV9001 and EV9002) were found in 1989 and 1990 in Middle Pleistocene terrace deposit of Han River, Yunxian county, Hubei province, China. They are classified as Homo erectus. Nine fossil animal teeth stratigraphically associated with the skulls were selected for electron spin resonance (ESR) dating. The simple exponential function was used for determination of the accumulated dose De and its appropriateness was discussed on the base of the experimental study. The closed system assumption was checked and the early uranium uptake model was applied to age determination. A mean age value was yielded to be 581±93 ka. It deviates from the palaeomagnetic dating result of 830-870 ka. Micro-regional complete saturation of ESR signal in enamel of very high U-content may account for the underestimation of ESR ages. Nevertheless both ESR and palaeomagnetic dating results place Yunxian crania in between the Homo erectus of Lantian and Zhoukoudian, which means that Yunxian crania constitute an important link in the human evolutionary lineage of China.

  18. ESR spectroscopy for detecting gamma-irradiated dried vegetables and estimating absorbed doses

    NASA Astrophysics Data System (ADS)

    Kwon, Joong-Ho; Chung, Hyung-Wook; Byun, Myung-Woo

    2000-03-01

    In view of an increasing demand for food irradiation technology, the development of a reliable means of detection for the control of irradiated foods has become necessary. Various vegetable food materials (dried cabbage, carrot, chunggyungchae, garlic, onion, and green onion), which can be legally irradiated in Korea, were subjected to a detection study using ESR spectroscopy. Correlation coefficients ( R2) between absorbed doses (2.5-15 kGy) and their corresponding ESR signals were identified from ESR signals. Pre-established threshold values were successfully applied to the detection of 54 coded unknown samples of dried clean vegetables ( chunggyungchae, Brassica camestris var. chinensis), both non-irradiated and irradiated. The ESR signals of irradiated chunggyungchae decreased over a longer storage time, however, even after 6 months of ambient storage, these signals were still distinguishable from those of non-irradiated samples. The most successful estimates of absorbed dose (5 and 8 kGy) were obtained immediately after irradiation using a quadratic fit with average values of 4.85 and 8.65 kGy being calculated.

  19. Evaluating the Potential of Q-Band ESR Spectroscopy for Dose Reconstruction of Fossil Tooth Enamel.

    PubMed

    Guilarte, Verónica; Trompier, François; Duval, Mathieu

    2016-01-01

    The potential of Q-band Electron Spin Resonance (ESR) for quantitative measurements has been scarcely evaluated in the literature and its application for dose reconstruction of fossil tooth enamel with dating purposes remains still quite unknown. Hence, we have performed a comparative study based on several Early to Middle Pleistocene fossil tooth samples using both X- and Q-band spectroscopies. Our results show that Q-band offers a significant improvement in terms of sensitivity and signal resolution: it allows not only to work with reduced amounts of valuable samples (< 4 mg), but also to identify different components of the main composite ESR signal. However, inherent precision of the ESR intensity measurements at Q-band is clearly lower than that achieved at X-band, highlighting the necessity to carry out repeated measurements. All dose values derived from X- and Q-band are nevertheless systematically consistent at either 1 or 2 sigma. In summary, our results indicate that Q-band could now be considered as a reliable tool for ESR dosimetry/dating of fossil teeth although further work is required to improve the repeatability of the measurements. PMID:26930398

  20. Evaluating the Potential of Q-Band ESR Spectroscopy for Dose Reconstruction of Fossil Tooth Enamel.

    PubMed

    Guilarte, Verónica; Trompier, François; Duval, Mathieu

    2016-01-01

    The potential of Q-band Electron Spin Resonance (ESR) for quantitative measurements has been scarcely evaluated in the literature and its application for dose reconstruction of fossil tooth enamel with dating purposes remains still quite unknown. Hence, we have performed a comparative study based on several Early to Middle Pleistocene fossil tooth samples using both X- and Q-band spectroscopies. Our results show that Q-band offers a significant improvement in terms of sensitivity and signal resolution: it allows not only to work with reduced amounts of valuable samples (< 4 mg), but also to identify different components of the main composite ESR signal. However, inherent precision of the ESR intensity measurements at Q-band is clearly lower than that achieved at X-band, highlighting the necessity to carry out repeated measurements. All dose values derived from X- and Q-band are nevertheless systematically consistent at either 1 or 2 sigma. In summary, our results indicate that Q-band could now be considered as a reliable tool for ESR dosimetry/dating of fossil teeth although further work is required to improve the repeatability of the measurements.

  1. Evaluating the Potential of Q-Band ESR Spectroscopy for Dose Reconstruction of Fossil Tooth Enamel

    PubMed Central

    Guilarte, Verónica; Trompier, François; Duval, Mathieu

    2016-01-01

    The potential of Q-band Electron Spin Resonance (ESR) for quantitative measurements has been scarcely evaluated in the literature and its application for dose reconstruction of fossil tooth enamel with dating purposes remains still quite unknown. Hence, we have performed a comparative study based on several Early to Middle Pleistocene fossil tooth samples using both X- and Q-band spectroscopies. Our results show that Q-band offers a significant improvement in terms of sensitivity and signal resolution: it allows not only to work with reduced amounts of valuable samples (< 4 mg), but also to identify different components of the main composite ESR signal. However, inherent precision of the ESR intensity measurements at Q-band is clearly lower than that achieved at X-band, highlighting the necessity to carry out repeated measurements. All dose values derived from X- and Q-band are nevertheless systematically consistent at either 1 or 2 sigma. In summary, our results indicate that Q-band could now be considered as a reliable tool for ESR dosimetry/dating of fossil teeth although further work is required to improve the repeatability of the measurements. PMID:26930398

  2. DNA cleavage, antimicrobial, spectroscopic and fluorescence studies of Co(II), Ni(II) and Cu(II) complexes with SNO donor coumarin Schiff bases

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Naik, Vinod H.; Kulkarni, Ajaykumar D.; Badami, Prema S.

    2010-01-01

    A series of Co(II), Ni(II) and Cu(II) complexes of the type ML 2 have been synthesized with Schiff bases derived from methylthiosemicarbazone and 5-formyl-6-hydroxy coumarin/8-formyl-7-Hydroxy-4-methylcoumarin. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMF indicate that, the complexes are non-electrolytes in nature. In view of analytical, spectral (IR, UV-vis, ESR, FAB-mass and fluorescence), magnetic and thermal studies, it has been concluded that, all the metal complexes possess octahedral geometry in which ligand is coordinated to metal ion through azomethine nitrogen, thione sulphur and phenolic oxygen atom via deprotonation. The redox behavior of the metal complexes was investigated by using cyclic voltammetry. The Schiff bases and their complexes have been screened for their antibacterial ( Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi) and antifungal activities ( Aspergillus niger, Aspergillus flavus and Cladosporium) by Minimum Inhibitory Concentration method. The DNA cleavage is studied by agarose gel electrophoresis method.

  3. Quantum chemical study of ZnO, Cu/ZnO, Cu/sub 2/O, and CuO clusters and CO chemisorption on ZnO(0001), CuZnO(0001), and Cu/ZnO(0001) surfaces

    SciTech Connect

    Rodriguez, J.A.; Campbell, C.T.

    1987-12-31

    Copper/zinc oxide mixtures show strong synergistic effects when used together as catalysts, particularly in methanol synthesis and water-gas-shift reactions. The authors have employed semiempirical quantum-mechanical calculations (INDO) to study the electronic properties of ZnO, CuO, and CuO/sub 2/ clusters (less than or equal to 26 atoms), of Cu absorbed on or substituted in these ZnO clusters, and of CO chemisorbed on ZnO(0001) and Cu/ZnO clusters. The results are discussed in light of models previously proposed to explain the unique properties of Cu/ZnO catalysts, which often involve Cu/sup +/ impurities in (on) the ZnO lattice. They use mainly the calculated charge on the Cu atom and its interaction with CO to address the electronic properties of Cu substituted in and adsorbed on ZnO clusters. Their results for neutral clusters indicate that, with respect to atomic charge, this Cu is quite similar in nature to the Cu atoms of bulk CuO or the Zn atoms of ZnO, where the metal has a formal oxidation state of +2. The Cu site in these ZnO clusters shows unique electron affinity properties, accepting a major fraction of the added electron density for anionic clusters. The mechanisms of CO chemisorptive bond formation on Cu(100), ZnO(0001), and Cu-doped ZnO are compared and contrasted based on the present results and those in the literature.

  4. Experimental and computational simulation studies on creep deformation mechanisms of a novel nanostructured Cu and Cu-10%Sn Alloy

    NASA Astrophysics Data System (ADS)

    Abo-Elsoud, Mohamed A.

    2015-04-01

    This work presents experimental and computational simulation studies on creep deformation mechanisms of a novel nanostructured Cu and Cu-10%Sn alloy that prepared by mechanical alloying (MA) copper with elemental Tin. Mechanical Newtonian creep model is employed for computational simulation of creep deformation mechanism under low stress-high temperature and to justify the experimental findings. The observed behaviors are discussed and compared with the predications of the Nabarro-Herring (N-H) theory of directional diffusion. A simple theory based on the climb controlled generation of dislocations from a fixed density of sources is developed to explain the observed behavior. TEM and SEM investigations are convenient and powerful techniques for characterization of phases and a novel nano-grain structured of the resulting materials. The reduction of grain size to the nanometer scale improves their mechanical properties.

  5. A multireference configuration interaction study of CuB and CuAl molecular constants and photoionization spectra.

    PubMed

    Ferrão, Luiz F A; Spada, Rene F K; Roberto-Neto, Orlando; Machado, Francisco B C

    2013-09-28

    Accurate potential energy curves and molecular constants for the low-lying electronic states of CuX(y) (X = B, Al; y = 0, +1) were investigated using the complete active space self-consistent field/multireference configuration interaction (MRCI) methodology with aug-cc-pV5Z basis set. The photoionization spectra of CuX were computed, showing electron detachment in the region of far ultraviolet. The results complement the previous theoretical characterizations and the few experimental studies. A comparative analysis was carried out concerning the different choices of reference configuration state functions in the MRCI calculations with and without the contribution of scalar relativistic effects. The results obtained with a small reference set adequately constructed are competitive to those using a much larger number of configuration state functions, and also the scalar relativistic effects improve significantly the molecular constants in this kind of system containing a 3d metal atom.

  6. Strong resistance of Arabidopsis thaliana and Raphanus sativus seeds for ionizing radiation as studied by ESR, ENDOR, ESE spectroscopy and germination measurement: Effect of long-lived and super-long-lived radicals

    NASA Astrophysics Data System (ADS)

    Kumagai, Jun; Katoh, Hiromi; Kumada, Takayuki; Tanaka, Atsushi; Tano, Shigemitsu; Miyazaki, Tetsuo

    2000-01-01

    Resistance of seeds for ionizing radiation effects on Arabidopsis thaliana and Raphanus sativus seeds were investigated by ESR, ENDOR, ESE spectroscopy and germination measurement. Two types of free radicals, such as long-lived (LL) and super-long-lived (SL) radicals, were produced by the γ-irradiation in the seeds. More than 90% of the 1 kGy-irradiated-seeds can germinate probably by decreasing the LL radicals by absorbing water. 10 kGy-irradiated-seeds cannot germinate at all probably due to the existence of significant amounts of the SL radicals even after absorbing water.

  7. Modified Ni-Cu catalysts for ethanol steam reforming

    SciTech Connect

    Dan, M.; Mihet, M.; Almasan, V.; Borodi, G.; Katona, G.; Muresan, L.; Lazar, M. D.

    2013-11-13

    Three Ni-Cu catalysts, having different Cu content, supported on γ-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N{sub 2} adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

  8. Modified Ni-Cu catalysts for ethanol steam reforming

    NASA Astrophysics Data System (ADS)

    Dan, M.; Mihet, M.; Almasan, V.; Borodi, G.; Katona, G.; Muresan, L.; Lazar, M. D.

    2013-11-01

    Three Ni-Cu catalysts, having different Cu content, supported on γ-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N2 adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

  9. ESR measurement of radical clearance in lung of whole mouse

    SciTech Connect

    Takeshita, K.; Utsumi, H.; Hamada, A. )

    1991-06-14

    Clearance of the nitroxide radicals, hydroxy-TEMPO and carboxy-PROxYL, in whole-mouse lung was directly measured by in vivo ESR. After injecting a nitroxide radical, distribution of the nitroxide radical all over the lung was confirmed by ESR imaging. The ESR signal of hydroxy-TEMPO was reduced in the lung and the clearance obeyed first-order kinetics, whereas the signal of carboxy-PROxYL remained constant. Comparison of the clearance rates of live and dead mice indicated the presence of 2 different clearance systems in the lung: loss of its paramagnetism in the lung, and transfer from alveolar to the blood circulation system.

  10. The Comparison of The Effects of Silybin and Silybin-Phosphatidylcholine on Viability and ESR Expression in Human Breast Cancer T47D Cell Line

    PubMed Central

    Mahmoodi, Narges; Motamed, Nasrin; Paylakhi, Seyed Hassan

    2014-01-01

    Objective Silybin is a polyphenol with anti-oxidant and anti-cancer properties. The poor bioavailability of some polyphenols can be improved by binding to phosphatidylcholine. In recent years, studies have been conducted to evaluate the anti-cancer effect of silybin. We studied the effect of silybin and silybin-phosphatidylcholine on ESR1 and ESR2 gene expression and viability in the T47D breast cancer cell line. Materials and Methods In this experimental study, a 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide test (MTT test) was used to determine doses for cell treatment, and the gene expression was analyzed by real-time reverse transcriptase-polymerase chain reaction (real-time RT- PCR). Results Significant dose- and time-dependent cell growth inhibitory effects of silybin and silybin-phosphatidylcholine along with ESR1 down-regulation were observed in T47D cells. In contrast to ESR1, the T47D cell line showed negligible ESR2 expression. Conclusion This study suggests that silybin and silybin-phosphatidylcholine down-regulate ESR1 in ER+breast cancers. Results also show that in the T47D cell line, silybindown-regulation of ESR1 compared with silybin. PMID:24611152

  11. ESR dating of submarine hydrothermal activities using barite in sulfide deposition

    NASA Astrophysics Data System (ADS)

    Toyoda, S.; Fujiwara, T.; Ishibashi, J.; Isono, Y.; Uchida, A.; Takamasa, A.; Nakai, S.

    2012-12-01

    The temporal change of submarine hydrothermal activities has been an important issue in the aspect of the evolution of hydrothermal systems which is related with ore formation (Urabe, 1995) and biological systems sustained by the chemical species arising from hydrothermal activities (Macdonald et al., 1980). Determining the ages of the hydrothermal deposit will provide essential information on such studies. Dating methods using disequilibrium between radioisotopes such as U-Th method (e.g. You and Bickle, 1998), 226}Ra-{210Pb and 228}Ra-{228Th method (e.g. Noguchi et al., 2011) have been applied to date submarine hydrothermal deposits. ESR (electron spin resonance) dating method is commonly applied to fossil teeth, shells, and quartz of Quaternay period where the natural accumulated dose is obtained from the intensities of the ESR signals which are created by natural radiation. The natural dose is divided by the dose rate to the mineral/sample to deduce the age. Okumura et al., (2010) made the first practical application of ESR (electron spin resonance) dating technique to a sample of submarine hydrothermal barite (BaSO4) to obtain preliminary ages, where Kasuya et al. (1991) first pointed out that barite can be used for ESR dating. Knowing that ESR dating of barite is promising, in this paper, we will present how we have investigated each factor that contributes ESR dating of barite in submarine hydrothermal sulfide deposition. (1) The best ESR condition for measuring the SO3- signal in barite is with the microwave power of 1mW and modulation amplitude of 0.1mT. (2) As results of heating experiments, the signal was found to be stable for the dating age range of several thousands. (3) 226Ra replacing Ba in barite is the source of the radiation. The amount of radioactive elements in sulfide mineral surrounding barite is negligible. (4) The external radiation from the sea water is negligible even in the submarine hydrothermal area where the radiation level is much

  12. Comparative study of the alloying effect on the initial oxidation of Cu-Au(100) and Cu-Pt(100)

    SciTech Connect

    Luo, Langli; Zhou, Guangwen; Kang, Yihong; Yang, Judith C.; Su, Dong; Stach, Eric A.

    2014-03-24

    Using in situ transmission electron microscopy, we show that the oxidation of the Cu-Au(100) results in the formation of Cu{sub 2}O islands that deeply embed into the Cu-Au substrate while the oxidation of the Cu-Pt(100) leads to the formation of Cu{sub 2}O islands that highly protrude above the Cu-Pt substrate. Their difference is attributed to the different mobilities of Pt and Au in the Cu base alloys for which the sluggish mobility of Pt in Cu results in trapped Pt atoms at the oxide/alloy interface while the faster mobility of Au in Cu leads to enhanced rehomogenization of the alloy composition.

  13. The investigation of the action of fillers by XPS studies of the transfer films of PEEK and its composites containing CuS and CuF2

    NASA Astrophysics Data System (ADS)

    Bahadur, S.; Gong, Deli; Anderegg, J. W.

    1993-01-01

    The wear behavior of polyetheretherketone (PEEK) and CuS-PEEK composite rubbing at 1 m/s speed and 19.6 N load against both the steel and glass disks is examined. While CuS filler decreased considerably the wear rate of PEEK in rubbing against the steel disk, the wear rate of both the filled and untilled materials in rubbing against the glass disk was almost the same. The wear rate of CuF2-PEEK composite sliding against a steel surface was also considerably lower than that of PEEK. The transfer films of the polymer and its composites containing CuS and CuF2 formed against the steel disk surfaces were studied by X-ray photoelectron spectroscopy (XPS). The analysis of the XPS spectra revealed that both CuS and CuF2 decomposed under the rubbing conditions. The analysis at two different depths in the transfer film of CuF2-PEEK revealed that the concentrations of Cu and FeF2 were greater close to the transfer film-counterface interface. However, there was no chemical change detected when unfilled PEEK rubbed against the steel disk surface.

  14. First-Principles Study of CuGaO2 Polymorphs: Delafossite α-CuGaO2 and Wurtzite β-CuGaO2.

    PubMed

    Suzuki, Issei; Nagatani, Hiraku; Kita, Masao; Iguchi, Yuki; Sato, Chiyuki; Yanagi, Hiroshi; Ohashi, Naoki; Omata, Takahisa

    2016-08-01

    The electronic structures of delafossite α-CuGaO2 and wurtzite β-CuGaO2 were calculated based on density functional theory using the local density approximation functional including the Hubbard correction (LDA+U). The differences in the electronic structure and physical properties between the two polymorphs were investigated in terms of their crystal structures. Three major structural features were found to influence the electronic structure. The first feature is the atomic arrangements of cations. In the conduction band of α-CuGaO2 with a layered structure of Cu2O and Ga2O3, Cu and Ga states do not mix well; the lower part of the conduction band mainly consists of Cu 4s and 4p states, and the upper part consists of Ga 4s and 4p states. By contrast, in β-CuGaO2, which is composed of CuO4 and GaO4 tetrahedra, Cu and Ga states are well-mixed. The second feature is the coordination environment of Cu atoms; the breaking of degeneracy of Cu 3d orbitals is determined by the crystal field. Dispersion of the Cu 3d valence band of β-CuGaO2, in which Cu atoms are tetrahedrally coordinated to oxygen atoms, is smaller than those in α-CuGaO2, in which Cu atoms are linearly coordinated to oxygen atoms; this results in a larger absorption coefficient and larger hole effective mass in β-CuGaO2 than in α-CuGaO2. The interatomic distance between Cu atoms-the third feature-also influences the dispersion of the Cu 3d valence band (i.e., the effective hole mass); the effective hole mass decreases with decreasing interatomic distance between Cu atoms in each structure. The results obtained are valuable for understanding the physical properties of oxide semiconductors containing monovalent copper and silver. PMID:27438905

  15. Magnetic structure of the low-dimensional magnet NaCu{sub 2}O{sub 2}: {sup 63,65}Cu and {sup 23}Na NMR studies

    SciTech Connect

    Sadykov, A. F. Gerashchenko, A. P.; Piskunov, Yu. V.; Ogloblichev, V. V.; Smol’nikov, A. G.; Verkhovskii, S. V.; Buzlukov, A. L.; Arapova, I. Yu.; Furukawa, Y.; Yakubovskii, A. Yu.; Bush, A. A.

    2014-11-15

    The magnetic structure of a quasi-one-dimensional frustrated NaCu{sub 2}O{sub 2} magnet single crystal is studied by NMR. The spatial orientation of the planar spin spirals in the copper-oxygen Cu{sup 2+}-O chains is determined, and its evolution as a function of the applied magnetic field direction is analyzed.

  16. Association between VDR and ESR1 gene polymorphisms with bone and obesity phenotypes in Chinese male nuclear families

    PubMed Central

    Gu, Jie-mei; Xiao, Wen-jin; He, Jin-wei; Zhang, Hao; Hu, Wei-wei; Hu, Yun-qiu; Li, Miao; Liu, Yu-juan; Fu, Wen-zhen; Yu, Jin-bo; Gao, Gao; Yue, Hua; Ke, Yao-hua; Zhang, Zhen-lin

    2009-01-01

    Aim: The goal of this study was to determine whether polymorphisms in the vitamin D receptor (VDR) and estrogen receptor alpha (ESR1) genes are associated with variations of peak bone mineral density (BMD) and obesity phenotypes in young Chinese men. Methods: A total of 1215 subjects from 400 Chinese nuclear families were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele-specific multiple PCR (ASM-PCR) analysis at the ApaI, FokI, and CDX2 sites in the VDR gene and the PvuII and XbaI sites in the ESR1 gene. BMD at the lumbar spine and hip, total fat mass, and total lean mass were measured using dual energy X-ray absorptiometry. The associations between VDR and ESR1 gene polymorphisms with peak BMD, body mass index (BMI), total fat mass, total lean mass, and percentage fat mass (PFM) were determined using quantitative transmission disequilibrium tests (QTDTs). Results: Using QTDTs, no significant within-family associations were obtained between genotypes or haplotypes of the VDR and ESR1 genes and peak BMD. For the obesity phenotypes, the within-family associations were significant between CDX2 genotypes and BMI (P=0.046), fat mass (P=0.004), and PFM (P=0.020). Further, PvuII was significantly associated with the variation of fat mass and PFM (P=0.002 and P=0.039, respectively). A subsequent 1000 permutations were in agreement with these within-family association results. Conclusion: Our findings showed that VDR and ESR1 polymorphisms were associated with total fat mass in young Chinese men, but we failed to find a significant association between VDR and ESR1 genotypes and peak BMD. These findings suggested that the VDR and ESR1 genes are quantitative trait loci (QTL) underlying fat mass variation in young Chinese men. PMID:19960008

  17. Lack of Association between ESR1 and CYP1A1 Gene Polymorphisms and Susceptibility to Uterine Leiomyoma in Female Patients of Iranian Descent

    PubMed Central

    Taghizade Mortezaee, Fatemeh; Tabatabaiefar, Mohammad Amin; Hashemzadeh Chaleshtori, Morteza; Miraj, Sepideh

    2014-01-01

    Uterine leiomyoma (UL) is the most common benign smooth muscle cell tumor with as yet unknown etiology and pathogenesis. This study was carried out to investigate the association of ESR1-351 A>G, ESR1 -397 T>C and CYP1A1 (Ile462Val) polymorphisms with UL in female patients of Iranian origin. In this case-control study, 276 patients with UL and 156 healthy women were recruited. The genetic polymorphisms ESR1-351 A>G, ESR1-397 T>C and CYP1A1 (Ile462Val) were genotyped by polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP). No significant difference were found in frequencies of both genotypes and alleles of ESR1-351 A>G, ESR1-397 T>C and CYP1A1 (Ile462Val) polymorphisms between the two groups (p>0.05). Our findings indicated that these ESR1 and CYP1A1 polymorphisms were not associated with the development of UL in the cases reported here. PMID:24567938

  18. Near-edge study of gold-substituted YBa2Cu3O(7-delta)

    NASA Technical Reports Server (NTRS)

    Ruckman, Mark W.; Hepp, Aloysius F.

    1991-01-01

    The valence of Cu and Au in YBa2Au0.3Cu2.7O7-delta was investigated using x-ray absorption near edge structure (XANES). X-ray and neutron diffraction studies indicate that Au goes on the Cu(1) site and Cu K-edge XANES shows that this has little effect on the oxidation state of the remaining copper. The Au L3 edge develops a white line feature whose position lies between that of trivalent gold oxide and monovalent potassium gold cyanide, and whose height relative to the edge step is smaller than in the two reference compounds. The appearance of the Au L3 edge suggests that fewer Au 3d states are involved in forming the Au-O bond in YBa2Au0.3Cu2.7O7-delta than in trivalent gold oxide.

  19. Near-edge study of gold-substituted YBa2Cu3O(7-delta)

    NASA Technical Reports Server (NTRS)

    Ruckman, Mark W.; Hepp, Aloysius F.

    1991-01-01

    The valence of Cu and Au in YBa2Au0.3Cu2.7O7-delta was investigated using X-ray absorption near edge structure (XANES). X-ray and neutron diffraction studies indicate that Au goes on the Cu(1) site and Cu K-edge XANES shows that this has little effect on the oxidation state of the remaining copper. The Au L3 edge develops a white line feature whose position lies between that of trivalent gold oxide and monovalent potassium gold cyanide, and whose height relative to the edge step is smaller than in the two reference compounds. The appearance of the Au L3 edge suggests that fewer Au 3d states are involved in forming the Au-O bond in YBa2Au0.3Cu2.7O7-delta than in trivalent gold oxide.

  20. Ab-initio study of donor-acceptor codoping for n-type CuO

    SciTech Connect

    Peng, Yuan; Wang, Junling; Zheng, Jianwei; Wu, Ping

    2014-10-28

    Single n-type dopant in CuO has either a deep donor level or limited solubility, inefficient in generating free electrons. We have performed ab-initio study of the donor-acceptor codoping to obtain n-type CuO. Our results show that N codoping can slightly improve the donor level of Zr and In by forming shallower n-type complexes (Zr{sub Cu}-N{sub O} and 2In{sub Cu}-N{sub O}), but their formation energies are too high to be realized in experiments. However, Li codoping with Al and Ga is found to be relatively easy to achieve. 2Al{sub Cu}-Li{sub Cu} and 2Ga{sub Cu}-Li{sub Cu} have shallower donor levels than single Al and Ga by 0.14 eV and 0.08 eV, respectively, and their formation energies are reasonably low to act as efficient codopants. Moreover, Li codoping with both Al and Ga produce an empty impurity band just below the host conduction band minimum, which may reduce the donor ionization energy at high codoping concentrations.

  1. Preferential Cu precipitation at extended defects in bcc Fe: An atomistic study

    SciTech Connect

    Zhang, Yongfeng; Millett, Paul C.; Tonks, Michael R.; Bai, Xian-Ming; Biner, S. Bulent

    2015-04-01

    As a starting point to understand Cu precipitation in RPV alloys, molecular dynamics and Metropolis Monte-Carlo simulations are carried out to study the effect of lattice defects on Cu precipitation by taking Fe-Cu system as a model alloy. Molecular dynamics simulations show that owing to the high heat of mixing and positive size mismatch, Cu is attracted by vacancy type defects such as vacancies and voids, and tensile stress fields. In accordance, preferential precipitation of Cu is observed in Metropolis Monte-Carlo simulations at dislocations, prismatic loops and voids. The interaction of Cu with a stress field, e.g., that associated with a dislocation or a prismatic loop, is dominated by elastic effect and can be well described by the linear-elasticity theory. For prismatic loops, the attraction to Cu is found to be size-dependent with opposite trends displayed by vacancy and interstitial loops. The size-dependences can be explained by considering the stress fields produced by these loops. The current results will be useful for understanding the effect of neutron irradiation on Cu precipitation in reactor-pressure-vessel steels.

  2. Spectroscopic studies of interaction between CuO nanoparticles and bovine serum albumin.

    PubMed

    Esfandfar, Paniz; Falahati, Mojtaba; Saboury, AliAkbar

    2016-09-01

    Recently, the great interests in manufacturing and application of metal oxide nanoparticles in commercial and industrial products have led to focus on the potential impact of these particles on biomacromolecules. In the present study, the interaction of copper oxide (CuO) nanoparticles with bovine serum albumin (BSA) was studied by spectroscopic techniques. The zeta potential value for BSA and CuO nanoparticles with average diameter of around 50 nm at concentration of 10 μM in the deionized (DI) water were -5.8 and -22.5 mV, respectively. Circular dichroism studies did not show any changes in the content of secondary structure of the protein after CuO nanoparticles interaction. Fluorescence data revealed that the fluorescence quenching of BSA by CuO nanoparticles was the result of the formed complex of CuO nanoparticles - BSA. Binding constants and other thermodynamic parameters were determined at three different temperatures. The hydrogen bond interactions are the predominant intermolecular forces to stabilize the CuO nanoparticle - BSA complex. This study provides important insight into the interaction of CuO nanoparticles with proteins, which may be of importance for further application of these nanoparticles in biomedical applications. PMID:26555383

  3. ESR spin probes in ionic liquids.

    PubMed

    Stoesser, Reinhard; Herrmann, Werner; Zehl, Andrea; Strehmel, Veronika; Laschewsky, André

    2006-05-12

    The spin probes 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL), and 2,2,6,6-tetramethyl-4-trimethylammoniumpiperidine-1-oxylIodide (CAT-1) are examined in a number of ionic liquids based on substituted imidazolium cations and tetrafluoroborate and hexafluorophosphate anions, respectively. The reorientation correlation times tau(R) of the spin probes in these systems have been determined by complete spectra simulation and, for rapid reortientation, by analysis of the intensities of the hyperfine lines of the electron spin resonance (ESR) spectra. A comparison of the results with those from the model system glycerol/water and selected organic solvents is made. Additions of diamagnetic and paramagnetic ions allow the conclusion that salt effects and spin exchange are present, and that both are superimposed by motional effects. Specific interactions in the ionic liquids, as well as between the spin-probe molecules and the constituents of the ionic liquids are reflected in the spectra of the spin probes, depending on their molecular structure.

  4. Growth and microtopographic study of CuInSe2 single crystals

    NASA Astrophysics Data System (ADS)

    Chauhan, Sanjaysinh M.; Chaki, Sunil; Tailor, J. P.; Deshpande, M. P.

    2016-05-01

    The CuInSe2 single crystals were grown by chemical vapour transport (CVT) technique using iodine as transporting agent. The elemental composition of the as-grown CuInSe2 single crystals was determined by energy dispersive analysis of X-ray (EDAX). The unit cell crystal structure and lattice parameters were determined by X-ray diffraction (XRD) technique. The surface microtopographic study of the as-grown CuInSe2 single crystals surfaces were done to study the defects, growth mechanism, etc. of the CVT grown crystals.

  5. Junction studies on electrochemically fabricated p-n Cu(2)O homojunction solar cells for efficiency enhancement.

    PubMed

    McShane, Colleen M; Choi, Kyoung-Shin

    2012-05-01

    p-n Cu(2)O homojunction solar cells were electrochemically fabricated by consecutively depositing an n-Cu(2)O layer on a p-Cu(2)O layer. In order to better understand the Fermi levels of the electrochemically grown polycrystalline p- and n-Cu(2)O layers and maximize the overall cell performance, the back and front contacts of the Cu(2)O homojunction cells were systematically changed and the I-V characteristics of the resulting cells were examined. The result shows that the intrinsic doping levels of the electrochemically prepared p-Cu(2)O and n-Cu(2)O layers are very low and they made almost Ohmic junctions with Cu metal with which previously studied p-Cu(2)O layers prepared by thermal oxidation of Cu foils are known to form Schottky junctions. The best cell performance (an η of 1.06%, a V(OC) of 0.621 V, an I(SC) of 4.07 mA cm(-2), and a fill factor (ff) of 42%) was obtained when the p-Cu(2)O layer was deposited on a commercially available ITO substrate as the back contact and a sputter deposited ITO layer was used as the front contact on the n-Cu(2)O layer. The unique features of the p-n Cu(2)O homojunction solar cell are discussed in comparison with other Cu(2)O-based heterojunction solar cells.

  6. The use of ESR spectroscopy for the identification and dose assessment of irradiated pink shrimp (Parapenaeus longirostris) from Turkey

    NASA Astrophysics Data System (ADS)

    Aydaş, Canan; Tepe Çam, Semra; Engin, Birol; Aydın, Talat; Polat, Mustafa

    2013-03-01

    Turkish pink shrimp (Parapenaeus longirostris) samples were studied by electron spin resonance (ESR) spectroscopy for identification and dose assessment purposes. In this work, the calcified shells of shrimps were used as a sample material. Before irradiation, all shrimp shell samples exhibit one weak ESR singlet with a g-factor of 2.0047. After irradiation, all samples exhibit two asymmetric ESR signal components centered at g-values of 2.0013 and 1.9959. The dose-response curves of the samples exposed to gamma radiations were found to be described well by a single saturation exponential function. Variation of ESR signal intensity of irradiated samples at room and-20 °C temperatures with time in a long-term showed that free radicals responsible from the ESR spectrum of shrimp shells were not stable but still detectable after 87 days. Also, the kinetic behavior of signal at g=2.0013 was studied and the additive dose method was used to evaluate the dose in the product.

  7. Multifrequency EPR studies of [Cu(1.5)Cu(1.5)](+) for Cu2(mu-NR2)2 and Cu2(mu-PR2)2 diamond cores.

    PubMed

    Mankad, Neal P; Harkins, Seth B; Antholine, William E; Peters, Jonas C

    2009-08-01

    Multifrequency electron paramagnetic resonance (EPR) spectroscopy is used to explore the electronic structures of a series of dicopper complexes of the type {(LXL)Cu}(2)(+). These complexes contain two four-coordinate copper centers of highly distorted tetrahedral geometries linked by two [LXL](-) ligands featuring bridging amido or phosphido ligands and associated thioether or phosphine chelate donors. Specific chelating [LXL](-) ligands examined in this study include bis(2-tert-butylsulfanylphenyl)amide (SNS), bis(2-di-iso-butylphosphinophenyl)amide (PNP), and bis(2-di-iso-propylphosphinophenyl)phosphide (PPP). To better map the electronic coupling to copper, nitrogen, and phosphorus in these complexes, X-, S-, and Q-band EPR spectra have been obtained for each complex. The resulting EPR parameters implied by computer simulation are unusual for typical dicopper complexes and are largely consistent with previously published X-ray absorption spectroscopy and density functional theory data, where a highly covalent {Cu(2)(mu-XR(2))(2)}(+) diamond core has been assigned in which removal of an electron from the neutral {Cu(2)(mu-XR(2))(2)} can be viewed as ligand-centered to a substantial degree. To our knowledge, this is the first family of dicopper diamond core model complexes for which the compendium of X-, S-, and Q-band EPR spectra have been collected for comparison to Cu(A). PMID:19572723

  8. Synthesis, spectroscopic, antimicrobial and DNA cleavage studies of new Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes with naphthofuran-2-carbohydrazide Schiff base

    NASA Astrophysics Data System (ADS)

    Halli, Madappa B.; Sumathi, R. B.

    2012-08-01

    A series of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes have been synthesized with newly synthesized Schiff base derived from naphthofuran-2-carbohydrazide and cinnamaldehyde. The elemental analyses of the complexes are confined to the stoichiometry of the type MLCl2 [M = Co(II) and Cu(II)], ML2Cl2 [M = Ni(II), Cd(II), Zn(II) and Hg(II)] respectively, where L is Schiff base ligand. Structures have been proposed from elemental analyses, IR, electronic, mass, 1H NMR, ESR spectral data, magnetic, and thermal studies. The measured low molar conductance values in DMF indicate that the complexes are non-electrolytes. Spectroscopic studies suggest coordination occurs through azomethine nitrogen and carbonyl oxygen of the ligand with the metal ions. The Schiff base and its complexes have been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal (Aspergillus niger, Aspergillus flavus, Cladosporium and Candida albicans) activities by minimum inhibitory concentration (MIC) method. The DNA cleavage studies by agarose gel electrophoresis method was studied for all the complexes.

  9. Synthesis, spectral, thermal and theoretical studies of Cu(II) complexes with 3-[4‧-dimethylaminophenyl]-1-(2-pyridyl)prop-2-en-1-one (DMAPP)

    NASA Astrophysics Data System (ADS)

    Gaber, M.; El-Daly, S. A.; El-Sayed, Y. S. Y.

    2009-03-01

    Cu(II) complexes of 3-[4'-dimethylaminophenyl]-1-(2-pyridyl) prop-2-en-1-one (DMAPP) are prepared and characterized by elemental analysis as well as spectral studies (IR and UV-vis), ESR, magnetic susceptibilities and thermal studies. The effect of different alcoholic solvents as well as the temperature on the complex formation is studied. The effect of Cu(II) ion on the emission spectrum of the free chalcone is also assigned. The stoichiometry, stability constant, absorption maximum and molar absorptivity of the metal complexes as well as the effect of pH, temperature on complex formation are determined spectrophotometrically. Adherence to Beer's law and Ringbom optimum concentration ranges are determined. The thermal decomposition of the metal complexes is studied by TGA technique. The kinetic parameters like activation energy, pre-exponential factor and entropy of activation are estimated. The structure of complexes was energetically optimized through molecular mechanics applying MM + force field coupled with molecular dynamics simulation.

  10. HREM and Simulation Study in the Bi-Sr-Ca-Cu-O System

    NASA Astrophysics Data System (ADS)

    Boussiri, K. El.; Snoeck, E.; Clin, M.; Toledano, J. C.; Rais, T.

    1997-08-01

    We have studied the Bi-Sr-Ca-Cu-O family by high resolution electron microscopy (HREM). We have simulated the HREM images using a phenomenological model. The experimental and calculated results agree quite well.

  11. Study on multicaloric effect of CuO induced multiferroic

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Yadav, K. L.

    2014-08-01

    One of the induced multiferroic materials, CuO has the magnetic as well as ferroelectric phase transition at same temperature (TN1 ˜ 213 K, TC and TN2 ˜ 230 K). These type of materials can show two types of entropy; magnetic field induced entropy (Magnetocaloric Effect) as well as electeric field induced entropy (Electrocaloric Effect). The presence of both type of entropy may be called "Multicaloric Entropy" (M. Vopson, Solid State Commun. 152, 2067 (2012) and Meng et al., Phys. Lett. A 377, 567 (2013)). We observed that "Multicaloric Entropy" in the induced multiferroic materials also depends on the magnetoelectric interaction (γ). Therofore, this numerical attempt to calculate the entropy of CuO may be useful for the future "electro-magnetic" based refrigerator technology.

  12. High resolution electron microscopy study of a high Cu variant of Weldalite (tm) 049 and a high strength Al-Cu-Ag-Mg-Zr alloy

    NASA Technical Reports Server (NTRS)

    Herring, R. A.; Gayle, Frank W.; Pickens, Joseph R.

    1991-01-01

    Weldalite (trademark) 049 is an Al-Cu-Li-Ag-Mg alloy that is strengthened in artificially aged tempers primarily by very thin plate-like precipitates lying on the set of (111) matrix planes. This precipitate might be expected to be the T(sub 1) phase, Al2CuLi, which has been observed in Al-Cu-Li alloys. However, in several ways this precipitate is similar to the omega phase which also appears as the set of (111) planes plates and is found in Al-Cu-Ag-Mg alloys. The study was undertaken to identify the set of (111) planes precipitate or precipitates in Weldalite (trademark) 049 in the T8 (stretched and artificially aged) temper, and to determine whether T(sub 1), omega, or some other phase is primarily responsible for the high strength (i.e., 700 MPa tensile strength) in this Al-Cu-Li-Ag-Mg alloy.

  13. Molecular Dynamics study of Pb overlayer on Cu(100)

    NASA Technical Reports Server (NTRS)

    Karimi, M.; Tibbits, P.; Ila, D.; Dalins, I.; Vidali, G.

    1991-01-01

    Isothermal-isobaric Molecular Dynamics (MD) simulation of a submonolayer Pb film in c(2x2) ordered structure adsorbed on a Cu(100) substrate showed retention of order to high T. The Embedded Atom Method (EAM) calculated the energy of atoms of overlayer and substrate. The time-averaged squared modulus of the two dimensional structure factor for the Pb overlayer measured the order of the overlayer. The results are for increasing T only, and require verification by simulated cooling.

  14. Nuclear Quadrupole Resonance Study of the High-T c Related Cu Oxide La4BaCu5O13+δ

    NASA Astrophysics Data System (ADS)

    Ohno, Takashi; Yasuoka, Hiroshi; Ueda, Yutaka

    1994-10-01

    63Cu and 65Cu NQR line shapes, spin-spin and spin-lattice relaxation rates in a high-T c related Cu oxide, La4BaCu5O13+δ, have been measured to clarify the difference between superconducting and non-superconducting Cu oxides from a microscopic view point. Although there are two crystallographically inequivalent Cu sites, only one pair of 63Cu and 65Cu NQR frequency spectra was observed. From the detailed study of the Fourier transformed spin-echo signal and that of the envelope decay, we attribute the above fact to an accidental coincidence of the NQR frequencies for these two sites. It is shown that the spin-lattice relaxation is manifested by the magnetic interactions in the measured temperature range of 1.4 K 420 K. The relaxation rate, 1/63T1, increases monotonically with increasing temperature, obeying 1/63T1=aT+bT3 above about 80 K, but shows a small swelling at low temperatures, suggesting a magnetic instability.

  15. Electronic properties of transition metal atoms on Cu2 N/Cu(100): a DFT comparative study

    NASA Astrophysics Data System (ADS)

    Ferron, Alejandro; Lado, José; Fernández-Rossier, Joaquín

    2015-03-01

    We study the electronic and magnetic properties of individual transition metal atoms (Ti, V, Cr, Mn, Fe, Co and Ni) deposited on a Cu2N /Cu(100) surface by means of spin-polarized density functional theory (DFT) calculations. We focus our work on a comparative study of the various quantities, such as magnetic moment, orbital occupation, structural properties, hybridization with the substrate and spin polarization of the substrate, paying attention to the trends as the transition metal is changed. In this work we try to go beyond existing theoretical works by providing a comprehensive and comparative study of the electronic, magnetic and structural properties of these seven atoms including also Ni, for which there are no published calculations to the best of our knowledge. In the case of Mn, Fe and Co, we connect our results with the existing scanning tunneling microscope experiments. A.F. acknowledges funding from the European Union's Seventh Framework Programme for research, technological development and demonstration, under the PEOPLE programme, Marie Curie COFUND Actions, grant agreement number 600375 and CONICET.

  16. Implication of the estrogen receptors GPER, ESR1, ESR2 in post-testicular maturations of equine spermatozoa.

    PubMed

    Gautier, Camille; Barrier-Battut, Isabelle; Guénon, Isabelle; Goux, Didier; Delalande, Christelle; Bouraïma-Lelong, Hélène

    2016-07-01

    Estrogen receptors ESR1, ESR2 and GPER are present on mature ejaculated horse spermatozoa, suggesting these cells as putative targets for estrogens. Indeed, spermatozoa are exposed to high level of estrogens during the transit in the male and female genital tracts but their roles are not investigated. So, we evaluated in vitro the role of 17β-estradiol during post-testicular maturations: regulation of motility, capacitation and acrosome reaction. Moreover according to the pseudo-seasonal breeder status of the stallion, we analyzed the putative seasonal variations in the presence of ESRs in spermatozoa. We showed that ESRs are more present on stallion sperm during the breeding season. We showed that capacitation and acrosome reaction are independent of estradiol action in horse. Estradiol can weakly modulate the motility and this effect is strictly associated with GPER and not with ESR1 and ESR2. The subcellular localization of GPER in the neck on stallion sperm is coherent with this effect. It seems that estrogens are not major regulators of sperm maturations associated to mare genital tract, so they could act during the epididymal maturations. PMID:27222348

  17. Antiferromagnetism of La2CuO(4-y) studied by muon-spin rotation

    NASA Technical Reports Server (NTRS)

    Uemura, Y. J.; Kossler, W. J.; Yu, X. H.; Kempton, J. R.; Schone, H. E.

    1987-01-01

    Zero-field spin precession of positive muons has been observed in the antiferromagnetic state of La2CuO(4-y). Sharp onsets of the sublattice magnetization are found at temperatures close to those of the susceptibility maxima of different specimens. The long-lived precession signal indicates a microscopically homogeneous distribution of spin density at each Cu atom below the Neel temperature. A combination of the present results and neutron-scattering studies indicates the ordered moment per Cu atom to be significantly less than 1 mu(B).

  18. Atomic-scale studies on the effect of boundary coherency on stability in twinned Cu

    SciTech Connect

    Niu, Rongmei; Han, Ke Su, Yi-Feng; Salters, Vincent J.

    2014-01-06

    The stored energy and hardness of nanotwinned (NT) Cu are related to interaction between dislocations and (111)-twin boundaries (TBs) studied at atomic scales by high-angle annular dark-field scanning transmission electron microscope. Lack of mobile dislocations at coherent TBs (CTBs) provides as-deposited NT Cu a rare combination of stability and hardness. The introduction of numerous incoherent TBs (ITBs) reduces both the stability and hardness. While storing more energy in their ITBs than in the CTBs, deformed NT Cu also exhibits high dislocation density and TB mobility and therefore has increased the driving force for recovery, coarsening, and recrystallization.

  19. Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios.

    PubMed

    Giordanino, Filippo; Vennestrøm, Peter N R; Lundegaard, Lars F; Stappen, Frederick N; Mossin, Susanne; Beato, Pablo; Bordiga, Silvia; Lamberti, Carlo

    2013-09-21

    Cu-SSZ-13 has been characterized by different spectroscopic techniques and compared with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios and prepared by the same ion exchange procedure. On vacuum activated samples, low temperature FTIR spectroscopy allowed us to appreciate a high concentration of reduced copper centres, i.e. isolated Cu(+) ions located in different environments, able to form Cu(+)(N2), Cu(+)(CO)n (n = 1, 2, 3), and Cu(+)(NO)n (n = 1, 2) upon interaction with N2, CO and NO probe molecules, respectively. Low temperature FTIR, DRUV-Vis and EPR analysis on O2 activated samples revealed the presence of different Cu(2+) species. New data and discussion are devoted to (i) [Cu-OH](+) species likely balanced by one framework Al atom; (ii) mono(μ-oxo)dicopper [Cu2(μ-O)](2+) dimers observed in Cu-ZSM-5 and Cu-β, but not in Cu-SSZ-13. UV-Vis-NIR spectra of O2 activated samples reveal an intense and finely structured d-d quadruplet, unique to Cu-SSZ-13, which is persistent under SCR conditions. This differs from the 22,700 cm(-1) band of the mono(μ-oxo)dicopper species of the O2 activated Cu-ZSM-5, which disappears under SCR conditions. The EPR signal intensity sets Cu-β apart from the others. PMID:23842567

  20. Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions at √{sNN}=62.4 and 200 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Al-Jamel, A.; Alexander, J.; Aoki, K.; Aphecetche, L.; Armendariz, R.; Aronson, S. H.; Asai, J.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Baksay, G.; Baksay, L.; Baldisseri, A.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Bathe, S.; Batsouli, S.; Baublis, V.; Bauer, F.; Bazilevsky, A.; Belikov, S.; Bennett, R.; Berdnikov, Y.; Bickley, A. A.; Bjorndal, M. T.; Boissevain, J. G.; Borel, H.; Boyle, K.; Brooks, M. L.; Brown, D. S.; Bucher, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Burward-Hoy, J. M.; Butsyk, S.; Campbell, S.; Chai, J.-S.; Chang, B. S.; Charvet, J.-L.; Chernichenko, S.; Chi, C. Y.; Chiba, J.; Chiu, M.; Choi, I. J.; Chujo, T.; Chung, P.; Churyn, A.; Cianciolo, V.; Cleven, C. R.; Cobigo, Y.; Cole, B. A.; Comets, M. P.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Das, K.; David, G.; Deaton, M. B.; Dehmelt, K.; Delagrange, H.; Denisov, A.; D'Enterria, D.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drachenberg, J. L.; Drapier, O.; Drees, A.; Dubey, A. K.; Durum, A.; Dzhordzhadze, V.; Efremenko, Y. V.; Egdemir, J.; Ellinghaus, F.; Emam, W. S.; Enokizono, A.; En'yo, H.; Espagnon, B.; Esumi, S.; Eyser, K. O.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Forestier, B.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fung, S.-Y.; Fusayasu, T.; Gadrat, S.; Garishvili, I.; Gastineau, F.; Germain, M.; Glenn, A.; Gong, H.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Hachiya, T.; Hadj Henni, A.; Haegemann, C.; Haggerty, J. S.; Hagiwara, M. N.; Hamagaki, H.; Han, R.; Harada, H.; Hartouni, E. P.; Haruna, K.; Harvey, M.; Haslum, E.; Hasuko, K.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Heuser, J. M.; Hiejima, H.; Hill, J. C.; Hobbs, R.; Hohlmann, M.; Holmes, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Hur, M. G.; Ichihara, T.; Iinuma, H.; Imai, K.; Inaba, M.; Inoue, Y.; Isenhower, D.; Isenhower, L.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Jacak, B. V.; Jia, J.; Jin, J.; Jinnouchi, O.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kaneta, M.; Kang, J. H.; Kanou, H.; Kawagishi, T.; Kawall, D.; Kazantsev, A. V.; Kelly, S.; Khanzadeev, A.; Kikuchi, J.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, Y.-S.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kiyomichi, A.; Klay, J.; Klein-Boesing, C.; Kochenda, L.; Kochetkov, V.; Komkov, B.; Konno, M.; Kotchetkov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Kroon, P. J.; Kubart, J.; Kunde, G. J.; Kurihara, N.; Kurita, K.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Le Bornec, Y.; Leckey, S.; Lee, D. M.; Lee, M. K.; Lee, T.; Leitch, M. J.; Leite, M. A. L.; Lenzi, B.; Li, X.; Li, X. H.; Lim, H.; Liška, T.; Litvinenko, A.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mao, Y.; Mašek, L.; Masui, H.; Matathias, F.; McCain, M. C.; McCumber, M.; McGaughey, P. L.; Miake, Y.; Mikeš, P.; Miki, K.; Miller, T. E.; Milov, A.; Mioduszewski, S.; Mishra, G. C.; Mishra, M.; Mitchell, J. T.; Mitrovski, M.; Morreale, A.; Morrison, D. P.; Moss, J. M.; Moukhanova, T. V.; Mukhopadhyay, D.; Murata, J.; Nagamiya, S.; Nagata, Y.; Nagle, J. L.; Naglis, M.; Nakagawa, I.; Nakamiya, Y.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Norman, B. E.; Nouicer, R.; Nyanin, A. S.; Nystrand, J.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Ohnishi, H.; Ojha, I. D.; Oka, M.; Okada, K.; Omiwade, O. O.; Oskarsson, A.; Otterlund, I.; Ouchida, M.; Ozawa, K.; Pak, R.; Pal, D.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, J.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Pinkenburg, C.; Pisani, R. P.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reuter, M.; Reygers, K.; Riabov, V.; Riabov, Y.; Roche, G.; Romana, A.; Rosati, M.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Rykov, V. L.; Ryu, S. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Sakata, H.; Samsonov, V.; Sato, H. D.; Sato, S.; Sawada, S.; Seele, J.; Seidl, R.; Semenov, V.; Seto, R.; Sharma, D.; Shea, T. K.; Shein, I.; Shevel, A.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shohjoh, T.; Shoji, K.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, C. P.; Singh, V.; Skutnik, S.; Slunečka, M.; Smith, W. C.; Soldatov, A.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Staley, F.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Suire, C.; Sullivan, J. P.; Sziklai, J.; Tabaru, T.; Takagi, S.; Takagui, E. M.; Taketani, A.; Tanaka, K. H.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Taranenko, A.; Tarján, P.; Thomas, T. L.; Todoroki, T.; Togawa, M.; Toia, A.; Tojo, J.; Tomášek, L.; Torii, H.; Towell, R. S.; Tram, V.-N.; Tserruya, I.; Tsuchimoto, Y.; Tuli, S. K.; Tydesjö, H.; Tyurin, N.; Vale, C.; Valle, H.; van Hecke, H. W.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wagner, M.; Walker, D.; Wang, X. R.; Watanabe, Y.; Wessels, J.; White, S. N.; Willis, N.; Winter, D.; Woody, C. L.; Wysocki, M.; Xie, W.; Yamaguchi, Y. L.; Yanovich, A.; Yasin, Z.; Ying, J.; Yokkaichi, S.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zaudtke, O.; Zhang, C.; Zhou, S.; Zimányi, J.; Zolin, L.; Phenix Collaboration

    2015-09-01

    We have studied the dependence of azimuthal anisotropy v2 for inclusive and identified charged hadrons in Au +Au and Cu +Cu collisions on collision energy, species, and centrality. The values of v2 as a function of transverse momentum pT and centrality in Au +Au collisions at √{s NN}=200 and 62.4 GeV are the same within uncertainties. However, in Cu +Cu collisions we observe a decrease in v2 values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au +Au and Cu +Cu collisions we find that v2 depends both on eccentricity and the number of participants, Npart. We observe that v2 divided by eccentricity (ɛ ) monotonically increases with Npart and scales as Npart1 /3. The Cu +Cu data at 62.4 GeV falls below the other scaled v2 data. For identified hadrons, v2 divided by the number of constituent quarks nq is independent of hadron species as a function of transverse kinetic energy K ET=mT-m between 0.1 Cu +Cu data at 62.4 GeV, of v2/(nq.ɛ .Npart1 /3) vs K ET/nq for all measured particles.

  1. Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions at √sNN = 62.4 and 200 GeV

    DOE PAGESBeta

    Adare, A.

    2015-09-23

    We have studied the dependence of azimuthal anisotropy v2 for inclusive and identified charged hadrons in Au+Au and Cu+Cu collisions on collision energy, species, and centrality. The values of v2 as a function of transverse momentum pT and centrality in Au+Au collisions at √sNN=200 and 62.4 GeV are the same within uncertainties. However, in Cu+Cu collisions we observe a decrease in v2 values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au+Au and Cu+Cu collisions we find that v2 depends both on eccentricity and themore » number of participants, Npart. We observe that v2 divided by eccentricity (ε) monotonically increases with Npart and scales as N1/3part. Thus, the Cu+Cu data at 62.4 GeV falls below the other scaled v2 data. For identified hadrons, v2 divided by the number of constituent quarks nq is independent of hadron species as a function of transverse kinetic energy KET=mT–m between 0.1T/nq<1 GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the Cu+Cu data at 62.4 GeV, of v2/(nq∙ε∙N1/3part) vs KET/nq for all measured particles.« less

  2. Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions at √sNN = 62.4 and 200 GeV

    SciTech Connect

    Adare, A.

    2015-09-23

    We have studied the dependence of azimuthal anisotropy v2 for inclusive and identified charged hadrons in Au+Au and Cu+Cu collisions on collision energy, species, and centrality. The values of v2 as a function of transverse momentum pT and centrality in Au+Au collisions at √sNN=200 and 62.4 GeV are the same within uncertainties. However, in Cu+Cu collisions we observe a decrease in v2 values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au+Au and Cu+Cu collisions we find that v2 depends both on eccentricity and the number of participants, Npart. We observe that v2 divided by eccentricity (ε) monotonically increases with Npart and scales as N1/3part. Thus, the Cu+Cu data at 62.4 GeV falls below the other scaled v2 data. For identified hadrons, v2 divided by the number of constituent quarks nq is independent of hadron species as a function of transverse kinetic energy KET=mT–m between 0.1T/nq<1 GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the Cu+Cu data at 62.4 GeV, of v2/(nq∙ε∙N1/3part) vs KET/nq for all measured particles.

  3. Study of the superconducting properties of the Bi-Ca-Sr-Cu-O system

    NASA Technical Reports Server (NTRS)

    Khan, Musheer H.; Naqvi, S. M. M. R.; Zia-Ul-haq, S. M.

    1991-01-01

    High Temperature Superconductivity in the Bi-Ca-Sr-Cu-O System has been observed and has attracted considerable attention in 1988. The 80 K superconductivity phase has been identified to have a composition of Bi2CaSr2Cu2Ox, while the 110 K phase as reported in the literature has a possible composition of Bi2Ca2Sr2Cu3O(x). Researchers present here a study of the electrical properties of bulk samples of the slowly cooled and rapidly quenched 2:1:2:2 system. The samples used in this study were prepared from appropriate amounts of Bi2O3, CuO, SrCO3, CaCO3.

  4. First-principles study of roles of Cu and Cl in polycrystalline CdTe

    DOE PAGESBeta

    Yang, Ji -Hui; Yin, Wan -Jian; Park, Ji -Sang; Metzger, Wyatt; Wei, Su -Huai

    2016-01-25

    In this study, Cu and Cl treatments are important processes to achieve high efficiency polycrystalline cadmium telluride (CdTe) solar cells, thus it will be beneficial to understand the roles they play in both bulk CdTe and CdTe grain boundaries (GBs). Using first-principles calculations, we systematically study Cu and Cl-related defects in bulk CdTe. We find that Cl has only a limited effect on improving p-type doping and too much Cl can induce deep traps in bulk CdTe, whereas Cu can enhance ptype doping of bulk CdTe. In the presence of GBs, we find that, in general, Cl and Cu willmore » prefer to stay at GBs, especially for those with Te-Te wrong bonds, in agreement with experimental observations.« less

  5. Study of the superconducting properties of the Bi-Ca-Sr-Cu-O system

    NASA Technical Reports Server (NTRS)

    Khan, Musheer H.; Qidwai, A. A.; Zia-Ul-haq, S. M.; Binsaif, Rashid

    1990-01-01

    High Temperature Superconductivity in the Bi-Ca-Sr-Cu-O System has been observed and has attracted considerable attention in 1988. The 80 K superconductivity phase has been identified to have a composition of Bi2CaSr2Cu2Ox, while the 110 K phase as reported in the literature has a possible composition of Bi2Ca2Sr2Cu3Ox. Researchers present here a study of the electrical properties of bulk samples of the slowly cooled and rapidly quenched 2:1:2:2 system. The samples used in this study were prepared from appropriate amounts of Bi2O3, CuO, SrCO3, CaCO3.

  6. Comparative Study of the Defect Point Physics and Luminescence of the Kesterites Cu2ZnSnS4 and Cu2ZnSnSe4 and Chalcopyrite Cu(In,Ga)Se2: Preprint

    SciTech Connect

    Romero, M. J.; Repins, I.; Teeter, G.; Contreras, M.; Al-Jassim, M.; Noufi, R.

    2012-08-01

    In this contribution, we present a comparative study of the luminescence of the kesterites Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) and their related chalcopyrite Cu(In,Ga)Se2 (CIGSe). Luminescence spectroscopy suggests that the electronic properties of Zn-rich, Cu-poor kesterites (both CZTS and CZTSe) and Cu-poor CIGSe are dictated by fluctuations of the electrostatic and chemical potentials. The large redshift in the luminescence of grain boundaries in CIGSe, associated with the formation of a neutral barrier is clearly observed in CZTSe, and, to some extent, in CZTS. Kesterites can therefore replicate the fundamental electronic properties of CIGSe.

  7. Temperature dependence diode parameters studies of Al/CuPc/n-Si/Al structure

    NASA Astrophysics Data System (ADS)

    Kumar, Ratnesh; Kaur, Ramneek; Sharma, Mamta; Kaur, Maninder; Tripathi, S. K.

    2015-08-01

    This paper presents the fabrication of Al/CuPc/n-Si/Al metal-organic-semiconductor diode. The copper phthalocyanine as organic layer is deposited on Si substrate by thermal evaporation technique. The temperature dependent current-voltage measurements are performed on Al/CuPc/n-Si structure. The important diode parameters i.e. the barrier height and ideality factor have been calculated. The temperature dependence of barrier height and ideality factor has been studied.

  8. The Luminescence and ESR of a Synthetic Emerald and the Natural Ones Mined from Santa Terezinha in Brazil

    NASA Astrophysics Data System (ADS)

    Ohkura, Hiroshi; Hashimoto, Hisashi; Mori, Yuzo; Chiba, Yoshinori; Isotani, Sadao

    1987-09-01

    Both the luminescence and ESR of a synthetic (KC-) emerald and a natural (ST-) type, mined from Santa Terezinha in Brazil, have been studied. The luminescence spectra of the impurity Cr3+ ions in both emeralds consist of two zerophonon lines followed by satellite bands. The satellite band of the ST-emerald shows huge intensity and broad width compared with that of the KC-emerald. The ESR of the Cr3+ ions in the ST-emerald is specific in the anisotropy of the g-factor and has a wider peak-to-peak value than the KC-emerald. We propose that these differences are caused by an interaction induced by the presence of a large number of impurity Fe3+ ions contained in the ST-emerald. The existence of Fe3+ and their concentrations were estimated by ESR.

  9. ESR1 Gene Polymorphisms and Prostate Cancer Risk: A HuGE Review and Meta-Analysis

    PubMed Central

    Wang, Yu-Mei; Liu, Zu-Wang; Guo, Jing-Bo; Wang, Xiao-Fang; Zhao, Xin-Xin; Zheng, Xuan

    2013-01-01

    Background Many published data on the association between single nucleotide polymorphisms (SNPs) in the ESR1 gene and prostate cancer susceptibility are inconclusive. The aim of this Human Genome Epidemiology (HuGE) review and meta-analysis is to derive a more precise estimation of this relationship. Methods A literature search of PubMed, Embase, Web of Science and Chinese Biomedical (CBM) databases was conducted from their inception through July 1st, 2012. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the strength of association. Results Twelve case-control studies were included with a total 2,165 prostate cancer cases and 3,361 healthy controls. When all the eligible studies were pooled into the meta-analysis, ESR1 PvuII (C>T) and XbaI (A>G) polymorphisms showed no association with the risk of prostate cancer. However, in the stratified analyses based on ethnicity and country, the results indicated that ESR1 PvuII (C>T) polymorphism was significantly associated with increased risk of prostate cancer among Asian populations, especially among Indian population; while ESR1 XbaI (A>G) polymorphism may significantly increase the risk of prostate cancer among American population. Furthermore, we also performed a pooled analysis for all eligible case-control studies to explore the role of codon 10 (T>C), codon 325 (C>G), codon 594 (G>A) and +261G>C polymorphisms in prostate cancer risk. Nevertheless, no significant associations between these polymorphisms and the risk of prostate cancer were observed. Conclusion Results from the current meta-analysis indicate that ESR1 PvuII (C>T) polymorphism may be a risk factor for prostate cancer among Asian populations, especially among Indian population; while ESR1 XbaI (A>G) polymorphism may increase the risk of prostate cancer among American population. PMID:23805288

  10. Effect of annealing on Cu precipitates in H ion irradiated Fe-0.6%Cu studied by positron annihilation

    NASA Astrophysics Data System (ADS)

    Jin, Shuoxue; Zhang, Peng; Lu, Eryang; Wang, Baoyi; Yuan, Daqing; Wei, Long; Cao, Xingzhong

    2016-10-01

    Fe-0.6%Cu alloy was irradiated with H ions to 0.1 dpa, and then annealed for 30 min from 150 °C to 500 °C. We focused the evolution of Cu precipitates in irradiated Fe-0.6%Cu alloy after the isochronal annealing from the perspective of positron annihilation. The ΔW parameters after thermal annealing (400 °C and 500 °C) were much larger than that induced by 0.1 dpa H irradiation. Annealing could promote the aggregation of the Cu-vacancy complexes, and form the Cu cluster-vacancies complexes. When the vacancy-like defects recovered around 500 °C, it meant the formation and growing of the defect-free Cu precipitates.

  11. Nuclear astrophysics experiments with stored, highly-charged ions at FRS-ESR at GSI

    SciTech Connect

    Scheidenberger, Christoph

    2010-08-12

    At the FRS-ESR complex of GSI a nuclear physics program with exotic nuclei has been established in last 18 years, which also addresses key questions and nuclear properties relevant in nuclear astrophysics. The paper summarizes production of exotic nuclei, lifetime studies of highly-charged ions, direct mass measurements and reactions at internal targets. A few comments on the analysis of two-body weak decays are given.

  12. ESR, U-series and paleomagnetic dating of Gigantopithecus fauna from Chuifeng Cave, Guangxi, southern China

    NASA Astrophysics Data System (ADS)

    Shao, Qingfeng; Wang, Wei; Deng, Chenglong; Voinchet, Pierre; Lin, Min; Zazzo, Antoine; Douville, Eric; Dolo, Jean-Michel; Falguères, Christophe; Bahain, Jean-Jacques

    2014-07-01

    Several Gigantopithecus faunas associated with taxonomically undetermined hominoid fossils and/or stone artifacts are known from southern China. These faunas are particularly important for the study of the evolution of humans and other mammals in Asia. However, the geochronology of the Gigantopithecus faunas remains uncertain. In order to solve this problem, a program of geochronological studies of Gigantopithecus faunas in Guangxi Province was recently initiated. Chuifeng Cave is the first studied site, which yielded 92 Gigantopithecus blacki teeth associated with numerous other mammalian fossils. We carried out combined ESR/U-series dating of fossil teeth and sediment paleomagnetic studies. Our ESR results suggest that the lower layers at this cave can be dated to 1.92 ± 0.14 Ma and the upper layers can be dated to older than 1.38 ± 0.17 Ma. Correlation of the recognized magnetozones to the geomagnetic polarity timescale was achieved by combining magnetostratigraphic, biostratigraphic and ESR data. The combined chronologies establish an Olduvai subchron (1.945-1.778 Ma) for the lowermost Chuifeng Cave sediments. We also analyzed the enamel δ13C values of the Gigantopithecus faunas. Our results show that southern China was dominated by C3 plants during the early Pleistocene and that the Gigantopithecus faunas lived in a woodland-forest ecosystem.

  13. Spin Labeling ESR Investigation of Covalently Bound Residues in Soil

    NASA Astrophysics Data System (ADS)

    Aleksandrova, Olga; Steinhoff, Heinz-Juergen; Klasmeier, Joerg; Schulz, Marcus; Matthies, Michael

    2013-04-01

    Organic xenobiotic chemicals, such as pesticides, biocides and veterinary pharmaceuticals, interact with soil, which results in the simultaneous formations of metabolites, mineralization products, and bound or non-extractable residues (NER). Substances or metabolites with reactive functional groups, such as aniline or phenol, have a tendency to give a larger proportion of NER. Despite numerous studies on NER, the majority of their chemical structures is still unknown. Reversible sequestration and irreversible formation of NER were also observed for veterinary antibiotic pharmaceuticals, after their application to soil with and without manure. For this purpose, we hypothesized a key role of specific functional groups of soil contaminants, via which contaminants are covalently bound to soil constituents, and advance a method of spin labeling ESR investigation of reaction products using a membrane method. Spin labels (SL) represent chemically stable paramagnetic molecules used as molecular labels and molecular probes for testing the covalent binding, structural properties, and molecular mobility of different physical, chemical, and biological systems. In the case of covalent binding of SL, their ESR spectra become broadened. We used stable nitroxide radicals (NR) as SL. These radicals modeled organic chemical contaminants and differed only in one functional group. The paramagnetic SL 4-Amino Tempo (4-amino-2,2,6,6-tetramethyl-1-piperidinylox) differed from Tempo (2,2,6,6-Tetramethylpiperidinooxy) in a substituent at the para-position of the piperidine ring, whereas Aniline Tempo (1-Piperidinyloxy, 2,2,6,-tetramethyl, 6-Aniline) differed from Tempo in an Aniline substituting one CH3 functional group. Before experimental analysis, we tested temporal changes in the concentration of both NR incubated with soil and found that the life-times of them in soil exceeded 3 days. We contaminated and labeled soil samples with NR, adding to soil the aqueous solution, which already

  14. Surface Study of Nb/Cu Films for Cavity Deposition by ECR Plasma

    SciTech Connect

    A.T. Wu; R.C. Ike; H.L. Phillips; A-M. Valente; H. Wang; G. Wu

    2005-05-16

    Deposition of thin niobium (Nb) films on copper (Cu) cavities, using an electron cyclotron resonance (ECR) plasma appears to be an attractive alternative technique for fabricating superconducting radio frequency cavities to be used in particle accelerators. The performance of these Nb/Cu cavities is expected to depend on the surface characteristics of the Nb films. In this paper, we report on an investigation of the influence of deposition energy on surface morphology, microstructure, and chemical composition of Nb films deposited on small Cu disks employing a metallographic optical microscope, a 3-D profilometer, a scanning electron microscope, and a dynamic secondary ion mass spectrometer. The results will be compared with those obtained on Nb surfaces treated by buffered chemical polishing, electropolishing, and buffered electropolishing. Possible implications from this study for Nb deposition on real Cu cavities will be discussed.

  15. First-principles study of nitrogen-doped CuAlO2

    NASA Astrophysics Data System (ADS)

    Xu, Ying; Ao, Zhi Min; Yuan, Ding Wang

    2012-08-01

    The electronic structure and formation energies of N-doped CuAlO2 are studied using first-principles calculations. It is found that, when a N atom is doped into CuAlO2, the N atom prefers to substitute an O atom rather than to occupy an interstitial site of the Cu layer. The NO acts as a shallow accepter while the Ni acts as a deep accepter. The results of the electronic structure show that the N-doping doesn't alter the band gap of CuAlO2 for the both cases. In the substitutional case, the N impurity states occur at the top of valance band maximum (VBM), which provides holes and increases the p-type conductivity. However, in the interstitial case, the N impurity states occur in the middle of the band gap, which are more localized and this indicates that it is not good for p-type conductivity.

  16. Shallow donor states induced by in-diffused Cu in ZnO: a combined HREELS and hybrid DFT study.

    PubMed

    Qiu, Hengshan; Gallino, Federico; Di Valentin, Cristiana; Wang, Yuemin

    2011-02-11

    A combined experimental and first principles study of Cu defects in bulk ZnO is presented. Cu particles are epitaxially deposited on the polar O-ZnO(0001) surface at room temperature. Upon heating, a broadening of the quasielastic peak in high resolution electron energy loss spectra is observed, corresponding to an electronic doping effect of Cu atoms in bulk ZnO with an ionization energy of 88 meV. Cu impurities in ZnO, although commonly acting as acceptors, are presently observed to induce shallow donor states. We assign these to interstitial Cu species on the basis of a hybrid density functional study. PMID:21405480

  17. Synthesis, characterization and equilibrium studies of some potential antimicrobial and antitumor complexes of Cu(II), Ni(II), Zn(II) and Cd(II) ions involving 2-aminomethylbenzimidazole and glycine

    NASA Astrophysics Data System (ADS)

    Aljahdali, M.

    2013-08-01

    The ternary complexes of Cu(II), Zn(II), Ni(II) and Cd(II) with 2-aminomethylbenzimidazole (AMBI) and glycine as a representative example of amino acids have been isolated and characterized by elemental analyses, IR, ESR, UV-vis, magnetic moment, molar conductance and 1H NMR spectra. AMBI behaves as neutral bidentate ligands with coordination through imidazole and amino group nitrogens while the glycine amino acid behaves as a monodenate anion with coordination involving the amino group and carboxylate oxygen after deprotonation. The magnetic and spectral data indicates a square planar geometry for both Cu2+ and Ni2+ complexes and a tetrahedral geometry for both Zn2+ and Cd2+ complexes. The isolated chelates have been screened for their antifungal and antibacterial activities using the disc diffusion method. A cytotoxicity of the compounds against colon (HCT116) and larynx (HEP2) cancer cells have been studied. The stability constants of ternary M-AMBI-Gly complexes were determined potentiometrically in aqueous solution at I = 0.1 mol dm-3 NaCl.

  18. CRYRING@ESR: present status and future research

    NASA Astrophysics Data System (ADS)

    Lestinsky, M.; Bräuning-Demian, A.; Danared, H.; Engström, M.; Enders, W.; Fedotova, S.; Franzke, B.; Heinz, A.; Herfurth, F.; Källberg, A.; Kester, O.; Litvinov, Y.; Steck, M.; Reistad, D.; Simonsson, A.; Skeppstedt, Ö.; Stöhlker, T.; Vorobjev, G.; the CRYRING@ESR working Group

    2015-11-01

    The former storage ring CRYRING has been shipped from the Manne Siegbahn Laboratory in Stockholm to Darmstadt as a Swedish in-kind contribution to FAIR. At its new location downstream of ESR all ion species presently accessible in ESR can be transferred to CRYRING, in which ions with rigidities between 1.44 and 0.054 Tm can be stored. The original Swedish layout has been modified by reconfiguring the sequence of straight sections and by slightly increasing the circumference to ESR/2. Ions can be injected from ESR or from an independent 300 keV/u RFQ test injector. The instrumentation of the ring includes an RF drift tube system for acceleration and deceleration (1 T s-1, with a possibility for an upgrade to 7 T s-1), electron cooling, a free experimental section, and both fast and slow extraction of ions. We report on the present progress of this project, give a prospective timeline, and summarize the new research which will be enabled by this project. First beam for commissioning of the storage ring is expected for 2015, final bakeout to restore ultrahigh vacuum conditions in 2016 and ion beams injected through ESR in ˜2017.

  19. Comparative study of flux pinning, creep and critical currents between YBaCuO crystals with and without Y2BaCuO5 inclusions

    NASA Technical Reports Server (NTRS)

    Murakami, Masato; Gotoh, Satoshi; Fujimoto, Hiroyuki; Koshizuka, Naoki; Tanaka, Shoji

    1991-01-01

    In the Y-Ba-Cu-O system, YBa2Cu3O(x) phase is produced by the following peritectic reaction: Y2BaCuO5 + liquid yields 2YBa2Cu3O(x). Through the control of processing conditions and starting compositions, it becomes possible to fabricate large crystals containing fine Y2BaCuO5(211) inclusions. Such crystals exhibit Jc values exceeding 10000 A/sq cm at 77 K and 1T. Recently, researchers developed a novel process which can control the volume fraction of 211 inclusions. Elimination of 211 inclusions is also possible. In this study, researchers prepared YBaCuO crystals with and without 211 inclusions using the novel process, and compared flux pinning, flux creep and critical currents. Magnetic field dependence of Jc for YBaCuO crystals with and with 211 inclusions is shown. It is clear that fine 211 inclusions can contribute to flux pinning. It was also found that flux creep rate could be reduced by increasing flux pinning force. Critical current density estimates based on the conventional flux pinning theory were in good agreement with experimental results.

  20. Comparative study of flux pinning flux creep and critical currents between YBaCuO crystals with and without Y2BaCuO5 inclusions

    NASA Technical Reports Server (NTRS)

    Murakami, Masato; Gotoh, Satoshi; Fujimoto, Hiroyuki; Koshizuka, Naoki; Tanaka, Shoji

    1990-01-01

    In the Y-Ba-Cu-O system YBa2Cu3Ox phase is produced by the following peritectic reaction: Y2BaCuO5 + liquid yields 2YBa2Cu3Ox. Through the control of processing conditions and starting compositions it becomes possible to fabricate large crystals containing fine Y2BaCuO5(211) inclusions. Such crystals exhibit Jc values exceeding 10000 A/sq cm at 77 K and 1T. Recently, researchers developed a novel process which can control the volume fraction of 211 inclusions. Elimination of 211 inclusions is also possible. In this study, researchers prepared YBaCuO crystals with and without 211 inclusions using the novel process and compared flux pinning, flux creep and critical currents. Magnetic field dependence of Jc for YBaCuO crystals with and without 211 inclusions is shown. It is clear that fine 211 inclusions can contribute to flux pinning. It was also found that flux creep rate could be reduced by increasing flux pinning force. Critical current density estimates based on the conventional flux pinning theory were in good agreement with experimental results.

  1. NO dissociation on Cu(111) and Cu2O(111) surfaces: a density functional theory based study

    NASA Astrophysics Data System (ADS)

    Padama, A. A. B.; Kishi, H.; Arevalo, R. L.; Moreno, J. L. V.; Kasai, H.; Taniguchi, M.; Uenishi, M.; Tanaka, H.; Nishihata, Y.

    2012-05-01

    NO dissociation on Cu(111) and Cu2O(111) surfaces is investigated using spin-polarized density functional theory. This is to verify the possibility of using Cu-based catalyst for NO dissociation which is the rate limiting step for the NOx reduction process. The dissociation of molecularly adsorbed NO on the surface is activated for both cases. However, from the reaction path of the NO-Cu2O(111) system, the calculated transition state lies below the reference energy which indicates the possibility of dissociation. For the NO-Cu(111) system, the reaction path shows that NO desorption is more likely to occur. The geometric and electronic structure of the Cu2O(111) surface indicates that the surface Cu atoms stabilize themselves with reference to the O atom in the subsurface. The interaction results in modification of the electronic structure of the surface Cu atoms of Cu2O(111) which greatly affects the adsorption and dissociation of NO. This phenomenon further explains the obtained differences in the dissociation pathways of NO on the surfaces.

  2. In situ study of heavy ion irradiation response of immiscible Cu/Fe multilayers

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Li, N.; Bufford, D. C.; Li, J.; Hattar, K.; Wang, H.; Zhang, X.

    2016-07-01

    Recent studies show that immiscible metallic multilayers with incoherent interfaces can effectively reduce defect density in ion irradiated metals by providing active defect sinks that capture and annihilate radiation induced defect clusters. Although it is anticipated that defect density within the layers should vary as a function of distance to the layer interface, there is, to date, little in situ TEM evidence to validate this hypothesis. In this study monolithic Cu films and Cu/Fe multilayers with individual layer thickness, h, of 100 and 5 nm were subjected to in situ Cu ion irradiation at room temperature to nominally 1 displacement-per-atom inside a transmission electron microscope. Rapid formation and propagation of defect clusters were observed in monolithic Cu, whereas fewer defects with smaller dimensions were generated in Cu/Fe multilayers with smaller h. Furthermore in situ video shows that the cumulative defect density in Cu/Fe 100 nm multilayers indeed varies, as a function of distance to the layer interfaces, supporting a long postulated hypothesis.

  3. Spin probe dynamics in relation to free volume in crystalline organics from ESR and PALS: Cyclohexane

    NASA Astrophysics Data System (ADS)

    Švajdlenková, H.; Zgardzinska, B.; Lukešová, M.; Bartoš, J.

    2016-01-01

    A joint external probe ESR and PALS study on cyclohexane (CHX) using stable free radical 2,2,6,6-tetra-methyl-1-piperidinyloxy (TEMPO) or ortho-positronium (o-Ps), respectively, is reported. The slow to fast transition of TEMPO occurs at the characteristic ESR temperature T50G coinciding with the solid to solid transition temperature, TSS. Moreover, o-Ps lifetime τ3(T50G) = 2.0 ns is close to an empirical rule τ3(T50G) = 2.17 ± 0.15 ns found for a series of amorphous glass-formers indicating that main transition of the TEMPO connected with the 'rigid' to plastic crystalline state transition in CHX occurs under the similar local free volume condition as in amorphous media.

  4. Alanine blends for ESR measurements of thermal neutron fluence in a mixed radiation field.

    PubMed

    Marrale, M; Brai, M; Gennaro, G; Triolo, A; Bartolotta, A; D'Oca, M C; Rosi, G

    2007-01-01

    In this paper, the results of a study on the electron spin resonance (ESR) dosimetry to measure thermal neutron fluence in a mixed radiation field (neutron and photons) are presented. The ESR responses of alanine dosemeters with different additives are compared. In particular, the (10)B-acid boric and the Gd-oxide were chosen to enhance the sensitivity of alanine dosemeters to thermal neutrons. Irradiations were carried out inside the thermal column of the TAPIRO reactor of the ENEA center, Casaccia Rome. The main results are a greater neutron sensitivity and a smaller lowest detectable fluence for the dosemeters with gadolinium than for dosemeters of alanine with (10)B, which is well known to be much more sensitive to thermal neutrons than simple alanine.

  5. Electronic structure and magnetic properties of monoclinic β-Cu2V2O7 : A GGA+U study

    NASA Astrophysics Data System (ADS)

    Yashima, Masatomo; Suzuki, Ryosuke O.

    2009-03-01

    A first-principles study on monoclinic C2/c copper pyrovanadate β-Cu2V2O7 has been performed using the generalized gradient approximation (GGA) and GGA+U method. The optimized unit-cell parameters and atomic coordinates of β-Cu2V2O7 agree well with experimental data. The optimized crystal structure of β-Cu2V2O7 indicates the existence of one-dimensional -Cu-Cu-Cu-Cu- chains. The electronic structure and magnetic properties were evaluated by the GGA+U calculations, which indicate that the β-Cu2V2O7 is a semiconducting antiferromagnetic material with an indirect band gap and local magnetic moment per Cu atom of 0.73μB . The intrachain exchanges for short and long Cu-Cu couples are estimated to be 6.4 and 4.1 meV, respectively, while the calculated interchain exchange (2.1 meV) is smaller, which indicate the one-dimensional character. The top of the valence band is composed of V3d , O2p , and Cu3d electrons while the bottom of the conduction band is primarily composed of Cu3d electrons. Valence electron-density distribution map indicates the V-O and Cu-O covalent bonds. Calculated partial electronic density of states strongly suggests that the V-O and Cu-O covalent bonds are mainly attributed to the overlaps of V3d and O2p atomic orbitals and of Cu3d and O2p , respectively.

  6. Thermally stimulated luminescence studies of undoped, Cu- and Mn-doped CaSO4 compounds

    NASA Astrophysics Data System (ADS)

    Manam, J.; Das, S.

    Thermally stimulated luminescence (TSL) of undoped and doped CaSO4 with activators such as Cu and Mn has been investigated. The polycrystalline samples of undoped and doped CaSO4 are prepared by the melting method. The formation of CaSO4 compound is confirmed by X-ray diffraction and Fourier transform infrared studies. Scanning electron microscopic studies of CaSO4 are also carried out. The TSL glow curves of undoped CaSO4, Cu- and Mn-doped CaSO4 are studied. Comparison of the thermoluminescence (TL) intensity of the most intensive glow peak of Cu-doped CaSO4 compound with that of undoped CaSO4 shows that addition of Cu impurity in CaSO4 compound enhances the TL intensity by about four times. However, the addition of Mn impurity to undoped CaSO4 increases the TL intensity by about three times when compared with that of undoped CaSO4. The TL-dose dependence of all three samples was studied and was observed to be almost linear in the studied range of irradiation time. Among the samples studied, namely undoped CaSO4 and Cu- and Mn-doped CaSO4, Cu-doped CaSO4 is found to be the most sensitive. The trap parameters, namely order of kinetics (b), activation energy (E) and frequency factor (s) associated with the most intensive glow peaks of CaSO4:Mn, CaSO4:Cu and CaSO4 phosphors were determined using the glow curve shape (Chen's) method.

  7. Computational and ESR studies of electron attachment to decafluorocyclopentane, octafluorocyclobutane, and hexafluorocyclopropane: electron affinities of the molecules and the structures of their stable negative ions as determined from 13C and 19F hyperfine coupling constants.

    PubMed

    ElSohly, Adel M; Tschumper, Gregory S; Crocombe, Richard A; Wang, Jih Tzong; Williams, Ffrancon

    2005-08-01

    High-resolution ESR spectra of the ground-state negative ions of hexafluorocyclopropane (c-C3F6*-), octafluorocyclobutane (c-C4F8*-), and decafluorocyclopentane (c-C5F10*-) are reported and their isotropic 19F hyperfine coupling constants (hfcc) of 198.6 +/- 0.4 G, 147.6 +/- 0.4 G, and 117.9 +/- 0.4 G, respectively, are in inverse ratio to the total number of fluorine atoms per anion. Together with the small value of 5.2 +/- 0.4 G determined for the isotropic 13C hfcc of c-C4F8*-, these results indicate that in each case the singly occupied molecular orbital (SOMO) is delocalized over the equivalent fluorines and possesses a nodal plane through the carbon atoms of a time-averaged D(nh) structure. A series of quantum chemical computations were carried out to further characterize these anions and their neutral counterparts. Both the B3LYP density functional and second-order Møller-Plesset perturbation theory (MP2) indicate that c-C3F6*- adopts a D(3h) geometry and a (2)A2'' ground electronic state, that c-C4F8*- adopts a D(4h) geometry and a (2)A2u ground electronic state, and that c-C5F10*- adopts a C(s) structure and a (2)A' electronic state. Moreover, the 19F hyperfine coupling constants computed with the MP2 method and a high quality triple-zeta basis set are within 1% of the experimental values. Also, the values computed for the 13C hfcc of c-C4F8*- are consistent with the experimental value of 5.2 G. Therefore, in keeping with the ESR results, these negative ions derived from first-row elements can be characterized as pi* species. In addition, the hypervalency of these perfluorocycloalkane radical anions has been clarified.

  8. Experimental and molecular dynamics studies in copper electro chemical mechanical polishing (Cu-ECMP)

    NASA Astrophysics Data System (ADS)

    Kandasamy Arulmozhi, Anant

    In recent times, copper electrochemical mechanical polishing (Cu ECMP) has received a great deal of interest from electrochemists and the semiconductor manufacturing industry. This attention is primarily due to its potential for yielding relatively defect-free surfaces with improved surface integrity compared to chemical mechanical planarization (CMP). In this work, Cu ECMP apparatus integrated with a sensing and data acquisition system was developed to polish phi4 inch (phi100 mm) blank Cu wafer surfaces to a finish of Ra< 15nm, and continuously gather voltage and current signals during Cu ECMP process at a sampling rate of 100Hz. Experimental studies were carried out to understand the effects of anodic voltage, pH, and pad pressure on the material removal rate (MRR) and surface roughness (Ra). Understanding the process from an atomistic standpoint helps us gain better control over the process and aids us in optimizing the key process output variables (KPOV). In order to gain a better understanding of the process, the molecular dynamic simulation (MDS) technique was adopted to develop a model to depict the real-time formation of copper (II) hexa-hydrate molecule Cu[(H2O)6] 2+, which is one of the key elements of the passivation layer formed over the Cu surface during ECMP. The behavior of the complex molecule under an electric force field was simulated to observe the process from a molecular perspective. From the trajectory of Cu2+, it was found that the velocity of copper ion increased with increase in applied voltage. Furthermore, the current carried by a single Cu2+ ion was computed based on the applied voltage and velocity of the ion.

  9. Analysis of parameters that influence the amplitude of the ESR/alanine signal after irradiation.

    PubMed

    Dolo, J M; Feaugas, V

    2005-02-01

    When ESR/alanine dosimetry is used for comparison, the time elapsed between irradiation and measurement is critical. Several publications have already mentioned the need for monitoring some of the parameters before, during and after irradiation for accurate normalization of ESR measurements. Nevertheless, neither classification nor coupling effects have yet been mentioned. By application of an experimental design approach, some parameters such as temperature and humidity during storage, before and after irradiation, have been studied. Results are given about the way the signal tends to evolve, ranking the parameters according to their influence and the effects of parameter coupling. A comparison with a conventional approach (study of one parameter at a time) is made. It is proposed to use a normalized ESR measurement that better accounts for the chemical aspect. A better fit of the results (amplitude versus time) is observed when amplitude is corrected taking into account the water content of the dosimeter for a given relative humidity of the surrounding atmosphere during storage.

  10. In vitro study on an antibacterial Ti-5Cu alloy for medical application.

    PubMed

    Ma, Zheng; Li, Mei; Liu, Rui; Ren, Ling; Zhang, Yu; Pan, Haobo; Zhao, Ying; Yang, Ke

    2016-05-01

    Health of human beings is subjected to severe threats from the spread of harmful bacteria and the implant-associated infection remains a serious problem in clinic. In this study, a copper-bearing antibacterial titanium alloy, Ti-5Cu, has been developed for dental and orthopedic implant applications. The microstructure, mechanical property, electrochemical corrosion behavior, in vitro antibacterial performance, cytocompatibility and hemocompatibility of the alloy are systematically investigated. The results reveal that the Ti-5Cu alloy which consists of α-phase matrix and intermetallic compound Ti2Cu not only possesses strong antibacterial activity against both E. coli and S. aureus, but also exhibits better mechanical properties than the commercial pure titanium. It is confirmed that the release of trace amount of Cu ions from the alloy plays an important role in killing bacteria. In spite of the ion release, Ti-5Cu alloy still reveals excellent corrosion resistance. Moreover, good cytocompatibility and superior hemocompatibility make Ti-5Cu alloy to be a potential solution that could prevent the peri-implant infection in dental and orthopaedic applications. PMID:26975748

  11. XPS and Raman study of slope-polished Cu(In,Ga)Se2 thin films

    NASA Astrophysics Data System (ADS)

    Beak, Gun Yeol; Jeon, Chan-Wook

    2016-05-01

    The growth of quality Cu(In,Ga)Se2 photovoltaic absorber without secondary phases is very important for improving the solar cell efficiency. Although X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy can identify the secondary phases, they provide insufficient information because of their insufficient resolution and complexity in analysis. In general, normal Raman spectroscopy is better for the analysis of secondary phases. On the other hand, the Raman signal provides information for film depths of less than 300 nm, and the Raman information cannot represent the properties of the entire film. In this regard, the authors introduce a new way of identifying secondary phases in Cu(In,Ga)Se2 films using depth Raman analysis. The as-prepared film was polished using a dimple grinder, which expanded a 2 μm thick film to approximately 1 mm, which is more than sufficient to resolve the depth distribution. Raman analysis indicated that the Cu(In,Ga)Se2 film showed different secondary phases, such as CuIn3Se5, InSe and CuSe, present in different depths of the film, whereas XPS provided complex information about the phases. Overall, the present study emphasizes that the Raman depth profile is more efficient for the identification of secondary phases in Cu(In,Ga)Se2 thin films than XPS and XRD. [Figure not available: see fulltext.

  12. Computer enhancement of ESR spectra of magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Dobosz, B.; Krzyminiewski, R.; Koralewski, M.; Hałupka-Bryl, M.

    2016-06-01

    We present ESR measurements of non-interacting magnetic nanoparticle systems. Temperature and orientational dependence of ESR spectra were measured for Fe3O4 nanoparticle coated by dextran or oleic acid, frozen in different magnetic field. Several parameters describing magnetic properties such as g-factor, line width, the anisotropy constant were calculated and discussed. The ESR spectra of investigated nanoparticles were also subjected to Computer Resolution Enhancement Method (CREM). This procedure allows to separate a narrow line on the background of the broad line, which presence in this type of materials was recognized in the recent literature and have been further discussed in the paper. CREM is a valuable tool for monitoring of changes on the surface of magnetic core of nanoparticles.

  13. ESR dating: is it still an 'experimental' technique?

    PubMed

    Skinner, A R

    2000-05-01

    Nearly 25 years ago, Motoji Ikeya demonstrated the potential of ESR dating. From a single substance (stalagmitic carbonate) and a single site (Akiyoshi Cavern), the field has grown to include materials from all over the world and time periods from a few thousand years ago to several million years ago. A vigorous program of instrumentation development has increased the precision of measurements as well as opening up new ways of collecting and interpreting spectra. Yet there are still references to ESR dating as an 'experimental' technique, one which cannot be trusted to produce dates that are accurate or precise. This paper discusses areas for which this is true and suggests what should be done to convince skeptics. Other areas for which the evidence suggests that ESR is at least as reliable as 'standard' methods will also be covered.

  14. Application of ESR spin label oximetry in food science.

    PubMed

    Zhou, Yu-Ting; Yin, Jun-Jie; Lo, Y Martin

    2011-12-01

    Lipid oxidation attributed to the presence of oxygen has long been a focal area for food science research due in early years mainly to its broad impact on the quality and shelf stability. The need to effectively strategize interventions to detect and eventually eliminate lipid oxidation in food remains as evidence on nutritional and health implications continue to accumulate. Electron spin resonance (ESR) spin label oximetry has been shown capable of detecting dissolved oxygen concentration in both liquid and gaseous phases based on the collision between oxygen and stable free radicals. This review aimed to summarize not just the principles and rationale of ESR spin label oximetry but also the wide spectrum of ESR spin label oximetry applications to date. The feasibility to identify in very early stage oxygen generation and consumption offers a promising tool for controlling lipid oxidation in food and biological systems.

  15. ESR1 mutations affect anti-proliferative responses to tamoxifen through enhanced cross-talk with IGF signaling.

    PubMed

    Gelsomino, Luca; Gu, Guowei; Rechoum, Yassine; Beyer, Amanda R; Pejerrey, Sasha M; Tsimelzon, Anna; Wang, Tao; Huffman, Kenneth; Ludlow, Andrew; Andò, Sebastiano; Fuqua, Suzanne A W

    2016-06-01

    The purpose of this study was to address the role of ESR1 hormone-binding mutations in breast cancer. Soft agar anchorage-independent growth assay, Western blot, ERE reporter transactivation assay, proximity ligation assay (PLA), coimmunoprecipitation assay, silencing assay, digital droplet PCR (ddPCR), Kaplan-Meier analysis, and statistical analysis. It is now generally accepted that estrogen receptor (ESR1) mutations occur frequently in metastatic breast cancers; however, we do not yet know how to best treat these patients. We have modeled the three most frequent hormone-binding ESR1 (HBD-ESR1) mutations (Y537N, Y537S, and D538G) using stable lentiviral transduction in human breast cancer cell lines. Effects on growth were examined in response to hormonal and targeted agents, and mutation-specific changes were studied using microarray and Western blot analysis. We determined that the HBD-ESR1 mutations alter anti-proliferative effects to tamoxifen (Tam), due to cell-intrinsic changes in activation of the insulin-like growth factor receptor (IGF1R) signaling pathway and levels of PIK3R1/PIK3R3. The selective estrogen receptor degrader, fulvestrant, significantly reduced the anchorage-independent growth of ESR1 mutant-expressing cells, while combination treatments with the mTOR inhibitor everolimus, or an inhibitor blocking IGF1R, and the insulin receptor significantly enhanced anti-proliferative responses. Using digital drop (dd) PCR, we identified mutations at high frequencies ranging from 12 % for Y537N, 5 % for Y537S, and 2 % for D538G in archived primary breast tumors from women treated with adjuvant mono-tamoxifen therapy. The HBD-ESR1 mutations were not associated with recurrence-free or overall survival in response in this patient cohort and suggest that knowledge of other cell-intrinsic factors in combination with ESR1 mutation status will be needed determine anti-proliferative responses to Tam. PMID:27178332

  16. Active phase of a Pd-Cu/ZSM-5 catalyst for benzene hydroxylation: In-situ XAFS studies

    NASA Astrophysics Data System (ADS)

    Cho, Kye-Sung; Lee, Yong-Kul

    2012-07-01

    The gas-phase hydroxylation of benzene by using a mixture of oxygen and hydrogen has been carried out over Cu/ZSM-5 catalysts modified with palladium. In-situ X-ray absorption studies employed in the course of H2-tempereature programmed reduction (H2-TPR) followed by benzene hydroxylation confirmed that the oxidic phase of Cu2+ was transformed to Cu+ during the reaction. The addition of Pd to Cu/ZSM-5 noticeably improved the reducibility of the oxidic Cu phase, which resulted in an increase in the activity of the reaction.

  17. Comparative study of radiation damage accumulation in Cu and Fe

    NASA Astrophysics Data System (ADS)

    Caturla, M. J.; Soneda, N.; Alonso, E.; Wirth, B. D.; Díaz de la Rubia, T.; Perlado, J. M.

    2000-01-01

    Bcc and fcc metals exhibit significant differences in behavior when exposed to neutron or heavy ion irradiation. Transmission electron microscopy (TEM) observations reveal that damage in the form of stacking fault tetrahedra (SFT) is visible in copper irradiated to very low doses, but that no damage is visible in iron irradiated to the same total dose. In order to understand and quantify this difference in behavior, we have simulated damage production and accumulation in fcc Cu and bcc Fe. We use 20 keV primary knock-on atoms (PKAs) at a homologous temperature of 0.25 of the melting point. The primary damage state was calculated using molecular dynamics (MD) with empirical, embedded-atom interatomic potentials. Damage accumulation was modeled using a kinetic Monte Carlo (kMC) algorithm to follow the evolution of all defects produced in the cascades. The diffusivities and binding energies of defects are input data for this simulation and were either extracted from experiments, the literature, or calculated using MD. MD simulations reveal that vacancy clusters are produced within the cascade core in the case of copper. In iron, most of the vacancies do not cluster during cooling of the cascade core and are available for diffusion. In addition, self-interstitial atom (SIA) clusters are produced in copper cascades but those observed in iron are smaller in number and size. The combined MD/kMC simulations reveal that the visible cluster densities obtained as a function of dose are at least one order of magnitude lower in Fe than in Cu. We compare the results with experimental measurements of cluster density and find excellent agreement between the simulations and experiments when small interstitial clusters are considered to be mobile as suggested by recent MD simulations.

  18. A study of the semiconductor compound СuAlO2 by the method of nuclear quadrupole resonance of Cu

    NASA Astrophysics Data System (ADS)

    Matukhin, V. L.; Khabibulin, I. Kh.; Shul'gin, D. A.; Smidt, S. V.

    2012-07-01

    The method of nuclear quadrupole resonance of Cu (NQR Cu) is used to study the samples of a semiconductor compound CuAlO2. The crystal structure of CuAlO2 belongs to the family of delafossite - the mineral of a basic CuFeO2 structure. Transparent semiconductor oxides, such as CuAlO2, have attracted recent attention as promising thermoelectric materials.

  19. Wetting and spontaneous infiltration: the case study of TaC/(Au, Al and Cu) compared to TiC/Cu

    NASA Astrophysics Data System (ADS)

    Aizenshtein, M.; Froumin, N.; Nafman, O.; Frage, N.

    2016-06-01

    Spontaneous infiltration of molten metals in to ceramic skeletons, in the course MMCs' production, is related to improved wetting of the ceramic by metals. TiC is considered a "metal-like" carbide and is supposed to be wetted well by metals through metallic bonding mechanism. Nevertheless, TiC/Cu exhibit an unusual behavior since spontaneous infiltration of molten Cu takes place, while TiC is partially wetted by Cu (θ=90°).In this work we studied the relation between wetting and spontaneous infiltration in the TaC/Au, Al and Cu systems. TaC is also considered a "metal-like" carbide and indeed no chemical interaction was observed at the interfaces of the studied systems.Sessile drop experiments showed almost perfect wetting in the three system but spontaneous infiltration occurred only in the first two (e.g. TaC/Au or Al). Thermodynamic calculation shows the difference between the systems which also has its' influence on the mechanical properties of the MMCs'. Further calculation clarifies the difference between TaC/Cu and TiC/Cu infiltration behavior, but is unable to explain the wetting results differences.Correlation between wetting and spontaneous infiltration in some cases is not straight forward and more studies and calculations on the atomistic level should be done in order to clarify this matter.

  20. The Association between ESR and CRP and Systemic Hypertension in Sarcoidosis

    PubMed Central

    Mirsaeidi, Mehdi; Omar, Hesham R.; Ebrahimi, Golnaz; Campos, Micheal

    2016-01-01

    Introduction. The association between the level of systemic inflammation and systemic hypertension (sHTN) among subjects with sarcoidosis has not been previously explored. Methods. A retrospective study was conducted to investigate the relation between the level of systemic inflammation in sarcoidosis, measured by various serum inflammatory markers, and sHTN. Results. Among a total of 108 cases with sarcoidosis (mean age: 53.4 years, 76.9% females), 55 (50.9%) had sHTN and 53 (49.1%) were normotensive. ESR was highly associated with sHTN. The patients with sHTN had higher mean ESR levels compared with normotensives (48.8 ± 35 versus 23.2 ± 27 mm/hr, resp.; P = 0.001). ROC curve analysis for ESR revealed an AUC value of 0.795 (95% CI: 0.692–0.897; P = 0.0001). With regard to CRP, there was a trend towards higher mean values in sHTN group (3.4 versus 1.7 mg/L; P = 0.067) and significantly higher prevalence of sHTN in the highest CRP quartile compared to the lowest one (69.6% versus 30%; OR 4.95; P = 0.017). ROC curve analysis for CRP revealed an AUC value of 0.644 (95% CI: 0.518–0.769; P = 0.03). On multivariate analysis, ESR and the CRP remained independent predictors for sHTN among subjects with sarcoidosis. Conclusion. Systemic inflammation is associated with the presence of sHTN in sarcoidosis. PMID:27433355

  1. Nitrogen addition using a gas blow in an ESR process

    NASA Astrophysics Data System (ADS)

    Yamamoto, S.; Momoi, Y.; Kajikawa, K.

    2016-07-01

    A new nitrogen method for adding in an ESR process using nitrogen gas blown in through the electrode was investigated. Nitrogen gas blown through a center bore of the electrode enabled contact between the nitrogen gas and the molten steel directly underneath the electrode tip. A ɸ 145mm diameter, laboratory-sized PESR furnace was used for the study on the reaction kinetics. Also, we carried out a water-model experiment in order to check the injection depth of the gas blown in the slag. The water model showed that the gas did not reach the upper surface of the molten metal and flowed on the bottom surface of the electrode only. An EPMA was carried out for a droplet remaining on the tip of the electrode after melting. The molten steel from the tip of the electrode shows that nitrogen gas absorption occurred at the tip of the electrode. The mass transfer coefficient was around 1.0x10-2 cm/sec in the system. This value is almost the same as the coefficient at the molten steel free surface.

  2. Role of valence states of adsorbates in inelastic electron tunneling spectroscopy: A study of nitric oxide on Cu(110) and Cu(001)

    NASA Astrophysics Data System (ADS)

    Shiotari, Akitoshi; Okuyama, Hiroshi; Hatta, Shinichiro; Aruga, Tetsuya; Alducin, Maite; Frederiksen, Thomas

    2016-08-01

    We studied nitric oxide (NO) molecules on Cu(110) and Cu(001) surfaces with low-temperature scanning tunneling microscopy (STM) and density functional theory (DFT). NO monomers on the surfaces are characterized by STM images reflecting 2 π* resonance states located at the Fermi level. NO is bonded vertically to the twofold short-bridge site on Cu(110) and to the fourfold hollow site on Cu(001). When NO molecules form dimers on the surfaces, the valence orbitals are modified due to the covalent bonding. We measured inelastic electron tunneling spectroscopy (IETS) for both NO monomers and dimers on the two surfaces, and detected characteristic structures assigned to frustrated rotation and translation modes by density functional theory simulations. Considering symmetries of valence orbitals and vibrational modes, we explain the intensity of the observed IETS signals in a qualitative manner.

  3. ESR dosimetry of fossil enamel: some comments about measurement precision, long-term signal fading and dose-response curve fitting.

    PubMed

    Duval, M; Guilarte Moreno, V; Grün, R

    2013-12-01

    This work deals with the specific studies of three main sources of uncertainty in electron spin resonance (ESR) dosimetry/dating of fossil tooth enamel: (1) the precision of the ESR measurements, (2) the long-term signal fading the selection of the fitting function. They show a different influence on the equivalent dose (D(E)) estimates. Repeated ESR measurements were performed on 17 different samples: results show a mean coefficient of variation of the ESR intensities of 1.20 ± 0.23 %, inducing a mean relative variability of 3.05 ± 2.29 % in the D(E) values. ESR signal fading over 5 y was also observed: its magnitude seems to be quite sample dependant but is nevertheless especially important for the most irradiated aliquots. This fading has an apparent random effect on the D(E) estimates. Finally, the authors provide new insights and recommendations about the fitting of ESR dose-response curves of fossil enamel with a double saturating exponential (DSE) function. The potential of a new variation of the DSE was also explored. Results of this study also show that the choice of the fitting function is of major importance, maybe more than the other sources previously mentioned, in order to get accurate final D(E) values.

  4. Electron spin resonance (ESR) probe for interventional MRI instrument localization.

    PubMed

    Ehnholm, G J; Vahala, E T; Kinnunen, J; Nieminen, J E; Standertskjöld-Nordenstam, C; Uusitalo, M A

    1999-08-01

    This article presents a miniaturized electron spin resonance (ESR) probe for deducing the position of a surgical instrument on an MR image. The ESR probe constructed was small enough to fit inside a 14-G biopsy needle sheath, and position information of the sheath could be acquired using a simple gradient sequence. The position accuracy was estimated from needle trajectories as inferred from the needle artifact, the actual physical trajectory, and measured coordinates. The probe was able to track the tip of a biopsy needle quickly (10 samples/sec) and precisely with accuracy better than +/-2 mm. J. Magn. Reson. Imaging 1999;10:216-219.

  5. Superconducting microstrip resonator for pulsed ESR of thin films.

    PubMed

    Benningshof, O W B; Mohebbi, H R; Taminiau, I A J; Miao, G X; Cory, D G

    2013-05-01

    This article describes a superconducting microstrip resonator operating at 9.5 GHz (X-band) that is specially designed for pulsed ESR on thin films. A novel configuration consisting of an array of half-wave length microstrip transmission lines generates a uniform magnetic field over a 2-D region of 100×1000 μm(2) with field homogeneity better than 5×10(-2). Using the device, we demonstrate strong coupling of the resonator to an electron spin ensemble and pulsed ESR on Si:P.

  6. Combined ESR and thermodynamic studies of the superoxide adduct of 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DEPMPO): hindered rotation around the O-O bond evidenced by two-dimensional simulation of temperature-dependent spectra.

    PubMed

    Rockenbauer, Antal; Clément, Jean-Louis; Culcasi, Marcel; Mercier, Anne; Tordo, Paul; Pietri, Sylvia

    2007-06-14

    Experiments were performed to elucidate the origin of the superhyperfine structure and line width alternation (LWA) seen in the ESR spectrum of the major diastereoisomer (1) of DEPMPO-OOH, the remarkably persistent superoxide adduct of 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DEPMPO). Using selectively deuterated DEPMPO derivatives, we demonstrated that the superhyperfine pattern can be unambiguously attributed to long-range couplings. The recording in pyridine of highly resolved spectra in a wide temperature range, combined with two-dimensional simulation, allowed us to characterize an inverted LWA in 1 and revealed a uniform line broadening in the spectrum of the minor DEPMPO-OOH diastereoisomer (2), with both effects originating from a chemical exchange between conformers. When the individual spectra of 1 presenting LWA in the fast-exchange regime were simulated, four equally good fits were obtained and this ambiguity could be resolved by using a two-dimensional simulation technique. The thermodynamic and kinetic constants of this exchange were consistent with a rotation around the O-O bond. We propose that line broadening effects in 1 and 2 result from this O-O rotation concerted with the pseudo-rotation of the pyrrolidine ring. PMID:17518450

  7. Djurleite (Cu1.94S) and low chalcocite (Cu2S): New crystal structure studies

    USGS Publications Warehouse

    Evans, H.T.

    1979-01-01

    Additional x-ray structure studies on low chalcocite generally confirm the previously reported structure but show that either disorder is present or the true space group is not P21/c but Pc, four of the 96 copper atoms in the monoclinic unit cell taking on twofold (linear) coordination. The crystal structure of djurleite has been solved in space group P21/n, the monoclinic cell having parameters a = 26.897, b = 15.745, and c = 13.565 angstroms; ?? = 90.13??; and a content of 248 copper and 128 sulfur atoms. Of the 62 different copper atoms in the structure, 52 are in threefold, triangular coordination with sulfur, nine in tetrahedral, and one in linear coordination.

  8. ESR imaging of the rat brain with a nitroxide radical perfused by in vivo microdialysis.

    PubMed

    Ueda, Y; Yokoyama, H; Ohya-Nishiguchi, H; Kamada, H

    1997-01-01

    We report here our investigation of the spatial distribution of free radicals using an electron spin resonance (ESR)-imaging system combined with an in vivo brain microdialysis method, which was performed in the resonator of the ESR-imaging system. A nonmagnetic cannula, newly developed in this study, was used for the perfusion of the exogenous free radicals agent. A nitroxide, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (carbamoyl PROYXL), was used as the imaging agent in saline solution at a concentration of 0.3 M, which was perfused into the right caudate putamen of the rat at 2 microliters/min by a microinfusion pump. Two-dimensional ESR projection of the Z-X plane, which was clearly distinguished (about phi 10 mm) from the nonperfused brain area, was obtained 6 h after the beginning of perfusion of carbamoyl PROXYL. The present method is considered to be a useful tool to introduce stable free radicals into a specific area of the brain.

  9. Development of a compact electron spin resonance system for measuring ESR signals of irradiated fingernails.

    PubMed

    Suzuki, Hirosuke; Tamukai, Kenji; Yoshida, Naoki; Ohya, Hiroaki; Kato, Katsuhisa; Anzai, Kazunori; Swartz, Harold M

    2010-02-01

    The aims of this study were to develop and improve the sensitivity of an electron spin resonance (ESR) spectrometer and to demonstrate its functionality for dosimetry in measuring ESR signals from radiation-exposed fingernails. The newly-developed spectrometer was a lightweight (22 kg) one-box ESR device with a resonator showing a Q-factor higher than that of a previous Keycom model, which is quieter, without influence from magnetic modulation, and contains a fingernail positioner. The authors obtained the best measurement result after the cavity Q-factor was increased to more than 7,200 by continuous polishing of the inner surface of the cavity using deerskin. The common mode noise of "magic T" was also successfully decreased to as low as one-half by completely tuning the arm balance. Moreover, the flatness of the modulated magnetic field was increased by as much as two-fold by changing the coil conformation. These efforts markedly decreased the noise level and extended downwardly the linear portion of dose dependence.

  10. Adsorption studies of Cu(II) on Boston fern (Nephrolepis exaltata Schott cv. Bostoniensis) leaves

    NASA Astrophysics Data System (ADS)

    Rao, Rifaqat Ali Khan; Khan, Umra

    2016-02-01

    Adsorption studies were done on Boston fern leaves for the effective removal of Cu(II) ions from aqueous solution. It has been tested for the first time for heavy metal adsorption from aqueous solution. This promising material has shown remarkable adsorption capacity towards Cu(II) ions which confirm its novelty, ease of availability, non-toxic nature, cheapness, etc., and give the main innovation to the present study. The adsorbent was analyzed by FT-IR, SEM and EDS. The effect of pH, contact time, initial metal ion concentration and temperature on the adsorption was investigated using batch process to optimize conditions for maximum adsorption. The adsorption of Cu(II) was maximum (96 %) at pH 4. The experimental data were analyzed by Langmuir, Freundlich and Tempkin isotherms. The kinetic studies of Cu(II)were carried out at room temperature (30 °C) in the concentration range 10-100 mg L-1. The data obtained fitted well with the Langmuir isotherm and pseudo-second-order kinetics model. The maximum adsorption capacity (q m) obtained from Langmuir adsorption isotherm was found to be 27.027 mg g-1 at 30 °C. The process was found to be exothermic and spontaneous in nature. The breakthrough and exhaustive capacities were found to be 12.5 and 37.5 mg g-1, respectively. Desorption studies showed that 93.3 % Cu(II) could be desorbed with 0.1 M HCl by continuous mode.

  11. Synthesis, Characterization, and Cu(2+) Coordination Studies of a 3-Hydroxy-4-pyridinone Aza Scorpiand Derivative.

    PubMed

    López-Martínez, Luis M; Pitarch-Jarque, Javier; Martínez-Camarena, Àlvar; García-España, Enrique; Tejero, Roberto; Santacruz-Ortega, Hisila; Navarro, Rosa-Elena; Sotelo-Mundo, Rogerio R; Leyva-Peralta, Mario Alberto; Doménech-Carbó, Antonio; Verdejo, Begoña

    2016-08-01

    The synthesis, acid-base behavior, and Cu(2+) coordination chemistry of a new ligand (L1) consisting of an azamacrocyclic core appended with a lateral chain containing a 3-hydroxy-2-methyl-4(1H)-pyridinone group have been studied by potentiometry, cyclic voltammetry, and NMR and UV-vis spectroscopy. UV-vis and NMR studies showed that phenolate group was protonated at the highest pH values [log K = 9.72(1)]. Potentiometric studies point out the formation of Cu(2+) complexes of 1:2, 2:2, 4:3, 1:1, and 2:1 Cu(2+)/L1 stoichiometries. UV-vis analysis and electrochemical studies evidence the implication of the pyridinone moieties in the metal coordination of the 1:2 Cu(2+)/L1 complexes. L1 shows a stronger chelating ability than the reference chelating ligand deferiprone. While L1 shows no cytotoxicity in HeLa and ARPE-19 human cell lines (3.1-25.0 μg/mL), it has significant antioxidant activity, as denoted by TEAC assays at physiological pH. The addition of Cu(2+) diminishes the antioxidant activity because of its coordination to the pyridinone moiety phenolic group.

  12. Synthesis, Characterization, and Cu(2+) Coordination Studies of a 3-Hydroxy-4-pyridinone Aza Scorpiand Derivative.

    PubMed

    López-Martínez, Luis M; Pitarch-Jarque, Javier; Martínez-Camarena, Àlvar; García-España, Enrique; Tejero, Roberto; Santacruz-Ortega, Hisila; Navarro, Rosa-Elena; Sotelo-Mundo, Rogerio R; Leyva-Peralta, Mario Alberto; Doménech-Carbó, Antonio; Verdejo, Begoña

    2016-08-01

    The synthesis, acid-base behavior, and Cu(2+) coordination chemistry of a new ligand (L1) consisting of an azamacrocyclic core appended with a lateral chain containing a 3-hydroxy-2-methyl-4(1H)-pyridinone group have been studied by potentiometry, cyclic voltammetry, and NMR and UV-vis spectroscopy. UV-vis and NMR studies showed that phenolate group was protonated at the highest pH values [log K = 9.72(1)]. Potentiometric studies point out the formation of Cu(2+) complexes of 1:2, 2:2, 4:3, 1:1, and 2:1 Cu(2+)/L1 stoichiometries. UV-vis analysis and electrochemical studies evidence the implication of the pyridinone moieties in the metal coordination of the 1:2 Cu(2+)/L1 complexes. L1 shows a stronger chelating ability than the reference chelating ligand deferiprone. While L1 shows no cytotoxicity in HeLa and ARPE-19 human cell lines (3.1-25.0 μg/mL), it has significant antioxidant activity, as denoted by TEAC assays at physiological pH. The addition of Cu(2+) diminishes the antioxidant activity because of its coordination to the pyridinone moiety phenolic group. PMID:27433814

  13. Effect of Cu2+ Activation on Interfacial Water Structure at the Sphalerite Surface as Studied by Molecular Dynamics Simulation

    SciTech Connect

    Jin, Jiaqi; Miller, Jan D.; Dang, Liem X.; Wick, Collin D.

    2015-12-10

    In the first part of this paper, an experimental contact angle study of the fresh and Cu2+ activated sphalerite-ZnS surface as well as the covellite-CuS (001) surface is reported describing the increased hydrophobic character of the surface during Cu2+ activation. In addition to these experimental results, the fresh sphalerite-ZnS (110), copper-zinc sulfide-CuZnS2 (110), villamaninite- CuS2 (100), and covellite-CuS (001) surfaces were examined using Molecular Dynamics Simulation (MDS). Our MDS results on the behavior of interfacial water at the fresh sphalerite-ZnS (110), copper-zinc sulfide-CuZnS2 (110), villamaninite-CuS2 (100), and covellite-CuS (001) surfaces include simulated contact angles, water number density distribution, water dipole orientation, water residence time, and hydrogen-bonding considerations. The copper content at the Cu2+ activated sphalerite surface seems to account for the increased hydrophobicity as revealed by both experimental and MD simulated contact angle measurements. The relatively greater hydrophobic character developed at the Cu2+ activated sphalerite surface and at the copper-zinc sulfide surface has been described by MDS, based on the structure of interfacial water and its dynamic properties. L.X.D. acknowledges funding from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences.

  14. A mesocosm study of fate and effects of CuO nanoparticles on endobenthic species (Scrobicularia plana, Hediste diversicolor).

    PubMed

    Buffet, Pierre-Emmanuel; Richard, Marion; Caupos, Fanny; Vergnoux, Aurore; Perrein-Ettajani, Hanane; Luna-Acosta, Andrea; Akcha, Farida; Amiard, Jean-Claude; Amiard-Triquet, Claude; Guibbolini, Marielle; Risso-De Faverney, Christine; Thomas-Guyon, Helene; Reip, Paul; Dybowska, Agnieska; Berhanu, Deborah; Valsami-Jones, Eugenia; Mouneyrac, Catherine

    2013-02-01

    The fate and effects of CuO nanoparticles (CuO NPs) were examined in endobenthic species (Scrobicularia plana , Hediste diversicolor), under environmentally realistic conditions in outdoor mesocosms (exposure to Cu at 10 μg L(-1) in particulate (CuO NPs) or soluble salt (CuNO(3)) forms) for 21 days. Labile Cu was determined in water and sediment by using diffusive gradient in thin films. No labile Cu being detected from CuO NPs; the observed effects in invertebrates exposed to CuO NPs were mainly attributed to the toxicity of nanoparticulate rather than dissolved Cu toxicity. Bioaccumulation of CuO NPs was observed in both species. Biomarkers were examined at different levels of biological organization: biochemical markers of defense and damage, biomarkers of genotoxicity (comet assay), and behavioral biomarkers (feeding and burrowing). Behavioral biomarkers, antioxidant defenses (catalase, glutathion S-transferase, metallothionein), and genotoxicity are the most sensitive tools to highlight the effect of soluble or nanoparticulate metal forms. Concerning other biomarkers of defense (superoxide dismutase, lactate dehydrogenase, laccase) and damage (thiobarbituric acid reactive substances, acetylcholinesterase, acid phosphatase), no significant effects were detected. This experiment shows the suitability of mesocosms for studying the environmental effects of nanoparticles.

  15. Free and Cued Selective Reminding Test: an Italian normative study.

    PubMed

    Frasson, P; Ghiretti, R; Catricalà, E; Pomati, S; Marcone, A; Parisi, L; Rossini, P M; Cappa, S F; Mariani, C; Vanacore, N; Clerici, F

    2011-12-01

    The presence of episodic memory impairment is required for the diagnosis of Alzheimer's dementia by all current diagnostic criteria. The new research criteria proposed by Dubois et al. (Lancet Neurol 6:734-746, 2007) require that the impairment should not improve significantly with cueing, recognition testing nor after the control of effective encoding. This is considered to be the core deficit of "prodromal Alzheimer's disease". The Free and Cued Selective Reminding Test (FCSRT) is a memory test that allows in assessing these specific features of memory impairment. Here, we report normative data for an Italian version of the FCSRT. The test is based on the 12 pictorial stimuli, 6 belonging to the living domain, and 6 to the non-living domain. Six scores were derived from the performance of 227 healthy Italian adults, with age, sex and education homogenously distributed across subgroups: immediate free recall (IFR), immediate total recall (ITR), delayed-free recall (DFR), delayed total recall (DTR), Index of Sensitivity of Cueing (ISC), number of intrusions. In multiple regression analyses, age emerged as an influencing factor for both IFR and DFR, with older people obtaining lower scores. Education and gender appear to influence only IFR, with better performance by more educated subjects and females. Adjusted scores were used to determine inferential cutoff scores and to compute equivalent scores. PMID:21594655

  16. Optical, microstructural, vibrational, and theoretical studies of p-type SrCu2O2 and BaCu2O2 transparent conductive oxides

    NASA Astrophysics Data System (ADS)

    Even, J.; Pedesseau, L.; Modreanu, M.; Huyberechts, G.; Servet, B.; Garry, Guy; Chaix-Pluchery, O.; Durand, O.

    2013-03-01

    Transparent conducting metal oxides (TCO) are unusual semiconducting materials displaying transparency to visible light. TCO materials are used for electrostatic shielding, antistatic screens, transparent heating devices, solar cells and even organic light emitting diodes. However, most TCOs are n-type, while p-type TCOs are scarce. SrCu2O2 is a leading candidate as a p-type transparent conductive oxide. In this paper, we report theoretical calculations and experimental studies on the vibrational, optical and microstructural properties of both bulk and thin films of polycrystalline undoped SrCu2O2 obtained by pulsed laser deposition (PLD). Barium doping of the SrCu2O2 by substitution of Sr atoms is also reported. The simulated crystal structures of both SrCu2O2 and BaCu2O2 materials, obtained through a state-of-the-art implementation of the Density functional theory, are compared with experimental X-ray diffraction data of undoped and Ba-doped SrCu2O2 bulk materials. Raman spectra of both SCO and BCO materials are simulated from the derivatives of the dielectric susceptibility and a symmetry analysis of the optical phonon eigenvectors at the Brillouin zone center is proposed. Good agreement with Raman scattering experimental results is demonstrated.

  17. Comparative Study of Cu Films Prepared by DC, High-Power Pulsed and Burst Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Solovyev, A. A.; Oskirko, V. O.; Semenov, V. A.; Oskomov, K. V.; Rabotkin, S. V.

    2016-08-01

    A comparative study of deposition rate, adhesion, structural and electrical properties of nanocrystalline copper thin films deposited using direct current magnetron sputtering (DCMS) and different regimes of high power pulsed magnetron sputtering is presented. High-power impulse magnetron sputtering (HIPIMS) and burst regime (pulse packages) of magnetron sputtering are investigated. The ion and atomic flows toward the growing film during magnetron sputtering of a Cu target are determined. X-ray diffraction, scanning electron microscopy and atomic force microscopy were used to observe the structural characterization of the films. The resistivity of the films was measured using four-point probe technique. In all sputtering regimes, Cu films have mixture crystalline orientations of [111], [200], [311] and [220] in the direction of the film growth. As peak power density in studied deposition regimes was different in order of magnitude (from 15 W/cm2 in DC regime to 3700 W/cm2 in HIPIMS), film properties were also greatly different. DCMS Cu films exhibit a porous columnar grain structure. In contrast, HIPIMS Cu films have a slightly columnar and denser composition. Cu films deposited using burst regimes at peak power density of 415 W cm-2 and ion-to-atom ratio of about 5 have the densest composition and smallest electrical resistance.

  18. Local structure analysis of some Cu(II) theophylline complexes

    NASA Astrophysics Data System (ADS)

    David, L.; Cozar, O.; Forizs, E.; Cr ăciun, C.; Ristoiu, D.; B ălan, C.

    1999-10-01

    The CuT 2L 2·2H 2O complexes [T=Theophylline (1,3-dimethylxanthine); L=NH 3, n-propylamine (npa), 2-aminoethanol (ae)] were prepared and investigated by ESR spectroscopy. Powder ESR spectrum of CuT 2(NH 3) 2·2H 2O is axial ( g||=2.255, g⊥=2.059). ESR spectrum of CuT 2(npa) 2·2H 2O with ( g||=2.299, g⊥=2.081) is a superposition of one axial ( g||=2.299, g⊥=2.073) and one isotropic component ( g0≈2.089), in the same amount. The axial spectra of the former complexes are due to a static Jahn-Teller effect ( EJT≈2880 cm -1). ESR spectrum of CuT 2(ae) 2·2H 2O is orthorhombic ( g1c=2.199, g2c=2.095, g3c=2.037). The local symmetries around the Cu(II) ions remain unchanged by DMF solvating, by adsorbing these solutions on NaY zeolite or by lowering the temperature.

  19. Estrogen Receptor Alpha (ESR1) Gene Polymorphisms in Pre-eclamptic Saudi Patients

    PubMed Central

    El-Beshbishy, Hesham A.; Tawfeek, Manal A.; Al-Azhary, Nevin M.; Mariah, Reham A.; Habib, Fawzia A.; Aljayar, Lamya; Alahmadi, Abrar F.

    2015-01-01

    Objectives: Pre-eclampsia causes maternal mortality worldwide. Estrogen receptor alpha (ESR1) gene polymorphisms were responsible for cardiovascular diseases. This case control study was conducted to investigate whether 2 polymorphic genes of ESR1 are associated with pre-eclampsia among Saudi women in Madina city, Saudi Arabia. Methods: Blood samples from 97 pre-eclamptic and 94 healthy pregnant women were analyzed using restriction fragment length polymorphism-polymerase chain reaction method. All the subjects were recruited randomly from outpatient clinics of Madina Maternity Children Hospital (MMCH), Madina, Saudi Arabia, between Dec. 2012 and Jan. 2014. Results: There was no association between pre-eclampsia and PvuII and XbaI ESR1 gene polymorphisms individually. TT/AA and TT/AG genotype combination existed significantly in pre-eclamptic patients compared to control. The frequency of PvuII and XbaI combined TT/AA genotypes between pre-eclamptic women was 36.1% vs 9.6%, however, frequency of PvuII and XbaI combined TT/AG genotypes between pre-eclamptic women was 3.1% vs 17%, compared to control. The homozygous T-A haplotype carriers showed high pre-eclampsia risk, independent of pregnancy, BMI and smoking status (adjusted odds ratio (OR): 3.26, 95% confidence interval (CI):1.71-9.21). The heterozygous T-A haplotype carriers did not differ from that of non-carriers (adjusted OR: 1.12, 95% CI: 0.47-2.75). No association was observed between pre-eclampsia and T-G, C-G and C-A haplotype of PvuII and XbaIESR1 gene polymorphisms. Conclusions: T-A haplotype of homozygous associated with pre eclampsia not heterozygous carriers of ESR 1 PvuII and XbaI gene polymorphisms elicited high risk of pre-eclampsia. GG genotype of XbaI polymorphism decreased pre-eclampsia risk. Further studies using larger sample size are recommended to investigate the ESR 1 gene polymorphisms associated with pre-eclampsia. PMID:26430422

  20. Ab-initio study of encapsulated and functionalized silicon nanotube with a monoatomically thin Cu wire

    NASA Astrophysics Data System (ADS)

    Chandel, Surjeet Kumar; Kumar, Arun; Ahluwalia, P. K.; Sharma, Raman

    2015-06-01

    First principle calculations based on DFT have been performed to study the interaction of monoatomically thin Cu wire with silicon nanotube in armchair configuration having chirality (6, 6) both by placing it inside (encapsulation) and outside (functionalisation) the tube. The lowest energy for positioning monoatomically thin Cu wire inside and outside surfaces of SiNT were found to possess cohesive energies of 4.03 eV and 4.02 eV respectively and hence the stability of both SiNTs is found to be almost same. However, From the electronic band structures study, the conductance in case of SiNT for the encapsulated and functionalized positioning of the Cu wire have been found to be 2G0 and 4G0 respectively showing enhanced conductance for the functionalized SiNT.

  1. Experimental studies on CHF enhancement in pool boiling with CuO-water nanofluid

    NASA Astrophysics Data System (ADS)

    Hegde, Ramakrishna N.; Rao, Shrikantha S.; Reddy, R. P.

    2012-06-01

    Critical heat flux enhancement (CHF) in pool boiling with CuO nanofluids was experimentally studied using a 36 gauge NiCr wire at atmospheric pressure. Experimentation included (1) subjecting the wire surface to multiple heating cycles with constant volume concentration of CuO nanofluid and (2) subjecting the wire surface to a single heating cycle with different volume concentrations of CuO nanofluid. Boiling of nanofluid in both the cases resulted in nanoparticle deposition and subsequent smoothing of the wire surface. To substantiate the nanoparticle deposition and its effect on critical heat flux, investigation was done by studying the surface roughness and SEM images of the wire surface. The experimental results show the evidence of nanoparticle deposition on the wire surface and its effect on CHF enhancement.

  2. Ab-initio study of encapsulated and functionalized silicon nanotube with a monoatomically thin Cu wire

    SciTech Connect

    Chandel, Surjeet Kumar; Ahluwalia, P. K.; Sharma, Raman; Kumar, Arun

    2015-06-24

    First principle calculations based on DFT have been performed to study the interaction of monoatomically thin Cu wire with silicon nanotube in armchair configuration having chirality (6, 6) both by placing it inside (encapsulation) and outside (functionalisation) the tube. The lowest energy for positioning monoatomically thin Cu wire inside and outside surfaces of SiNT were found to possess cohesive energies of 4.03 eV and 4.02 eV respectively and hence the stability of both SiNTs is found to be almost same. However, From the electronic band structures study, the conductance in case of SiNT for the encapsulated and functionalized positioning of the Cu wire have been found to be 2G{sub 0} and 4G{sub 0} respectively showing enhanced conductance for the functionalized SiNT.

  3. A Theoretical Study of Methanol Synthesis from CO(2) Hydrogenation on Metal-doped Cu(111) Surfaces

    SciTech Connect

    Liu P.; Yang, Y.; White, M.G.

    2012-01-12

    Density functional theory (DFT) calculations and Kinetic Monte Carlo (KMC) simulations were employed to investigate the methanol synthesis reaction from CO{sub 2} hydrogenation (CO{sub 2} + 3H{sub 2} {yields} CH{sub 3}OH + H{sub 2}O) on metal-doped Cu(111) surfaces. Both the formate pathway and the reverse water-gas shift (RWGS) reaction followed by a CO hydrogenation pathway (RWGS + CO-Hydro) were considered in the study. Our calculations showed that the overall methanol yield increased in the sequence: Au/Cu(111) < Cu(111) < Pd/Cu(111) < Rh/Cu(111) < Pt/Cu(111) < Ni/Cu(111). On Au/Cu(111) and Cu(111), the formate pathway dominates the methanol production. Doping Au does not help the methanol synthesis on Cu(111). Pd, Rh, Pt, and Ni are able to promote the methanol production on Cu(111), where the conversion via the RWGS + CO-Hydro pathway is much faster than that via the formate pathway. Further kinetic analysis revealed that the methanol yield on Cu(111) was controlled by three factors: the dioxomethylene hydrogenation barrier, the CO binding energy, and the CO hydrogenation barrier. Accordingly, two possible descriptors are identified which can be used to describe the catalytic activity of Cu-based catalysts toward methanol synthesis. One is the activation barrier of dioxomethylene hydrogenation, and the other is the CO binding energy. An ideal Cu-based catalyst for the methanol synthesis via CO{sub 2} hydrogenation should be able to hydrogenate dioxomethylene easily and bond CO moderately, being strong enough to favor the desired CO hydrogenation rather than CO desorption but weak enough to prevent CO poisoning. In this way, the methanol production via both the formate and the RWGS + CO-Hydro pathways can be facilitated.

  4. Edge Stabilized Ribbon (ESR); Stress, Dislocation Density and Electronic Performance

    NASA Technical Reports Server (NTRS)

    Sachs, E. M.

    1984-01-01

    The edge stabilized ribbon (ESR) silicon ribbon was grown in widths of 1, 2.2 and 4.0 inches at speeds ranging from .6 to 7 in/min, which result in ribbon thicknesses of 5 to 400 microns. One of the primary problems remaining in ESR growth is that of thermally induced mechanical stresses. This problem is manifested as ribbon with a high degree of residual stress or as ribbon with buckled ribbon. Thermal stresses result in a high dislocation density in the grown material, resulting in compromised electronic performance. Improvements in ribbon flatness were accomplished by modification of the ribbon cooling profile. Ribbon flatness and other experimental observations of ESR ribbon are discussed. Laser scanner measurements show a good correlation between diffusion length and dislocation density which indicates that the high dislocation densities are the primary cause of the poor current performance of ESR materials. Dislocation densities were reduced and improved electronic performance resulted. Laser scanner data on new and old material are presented.

  5. ESR dating of barite in sea-floor hydrothermal sulfide deposits at Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Fujiwara, T.; Toyoda, S.; Uchida, A.; Ishibashi, J.; Nakai, S.; Takamasa, A.

    2013-12-01

    The temporal change of submarine hydrothermal activities has been an important issue in the aspect of the evolution of hydrothermal systems which is related with ore formation and biological systems sustained by the chemical species arising from hydrothermal activities (Macdonald et al., 1980). With this aspect, Okumura et al. (2010) made the first practical application of ESR (electron spin resonance) dating technique to a sample of submarine hydrothermal barite to obtain preliminary ages, while Kasuya et al. (1991) first pointed out that barite can be used for ESR dating. ESR is a method to observe radicals having unpaired electrons. As natural radiation creates unpaired electrons in minerals, the age is deduced by dividing the natural radiation dose (obtained from the amount of unpaired electrons) by the dose rate which is estimated by the amount of environmental radioactive elements. The samples were taken by the research cruises, NT12-10 and NT11-20 and NT12-06 operated by JAMSTEC from Hatoma, Yoron, Izena, North Iheya, and Yonaguni IV Knolls of Okinawa Trough. The blocks of sulfide deposits were cut into pieces, and about 2.0g was crushed. The samples were soaked in 12M hydrochloric acid, left for approximately 24 hours. Then, 13M nitric acid was added. Finally, after rinsing in distilled water, the sample was filtered and dried. Impurities were removed by handpicking. A X-ray diffraction study was made to confirm that the grains are pure barite. After γ-ray irradiation at Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, they were measured at room temperature with an ESR spectrometer (JES-PX2300) with a microwave power of 1mW, and the magnetic field modulation amplitude of 0.1mT. The equivalent natural radiation doses were obtained from the increase of ESR signal intensity of SO3- by irradiation. The bulk Ra concentration was measured by the low background pure Ge gamma ray spectrometer. Assuming that Ra is populated only in barite

  6. Scanning tunneling microscopy study of molecular growth structures of Gd@C82 on Cu(111)

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Qin, Zhi-Hui; Pan, Jin-Bo; Lu, Shuang-Zan; Du, Shi-Xuan; Gao, Hong-Jun; Cao, Geng-Yu

    2013-07-01

    The coverage and temperature-dependent nucleation behaviors of the Gd@C82 metallofullerenes on Cu(111) have been studied by low-temperature scanning tunneling microscopy (LT-STM) in detail. Upon molecular deposition at low temperature, Gd@C82 molecules preferentially decorate the steps and nucleate into single layer islands with increasing coverage. Further annealing treatment leads some of the Gd@C82 molecules to assemble into bright and dim patches, which are correlated to the adsorption induced substrate reconstruction. Upon sufficient thermal activation, Gd@C82 molecules sink into the Cu(111) surface one-copper-layer-deep, forming hexagonal close-packed molecular islands with intra-molecular details observed as striped patterns. By considering the commensurability between the Gd@C82 nearest-neighbor distance and the lattice of the underlying Cu(111), we clearly identified two kinds of in-plane molecular arrangements as (√19 × √19)R23.4° and (√19 × √19)R36.6° with respect to Cu(111). Within the assembled Gd@C82 molecular, island molecules with dim—bright contrast are spatially distributed, which may be modulated by the preexisted species on Cu(111).

  7. Study of Cu diffusion in porous dielectrics using secondary-ion-mass spectrometry

    SciTech Connect

    Rodriguez, Oscar R.; Gill, William N.; Plawsky, Joel L.; Tsui Ting, Y.; Grunow, Stephan

    2005-12-15

    Secondary-ion-mass spectrometry measurements were used to study Cu diffusion in porous silica. The total concentration of Cu{sup +} decreases with increasing porosity of the dielectric. This behavior is the combined result of both the chemistry and the morphology of the dielectric. The injection of Cu is triggered by outgassing of hydroxyl and water-related species from the dielectric; furthermore, the reduced available cross-sectional area of solid for diffusion, due to porosity, leads to reduced diffusion through the porous film. This suggests that surface diffusion does not play an important role in this process. The Cu{sup +} concentration at the Cu/dielectric interface is on the order of 10{sup 23} at./m{sup 3}, but decreases with time and exponentially with porosity, which suggests the occurrence of a chemical reaction at the interface. A model of molecular diffusion and ion drift that considers the porosity of the film is developed and the results are consistent with the experimental data.

  8. Studies on the thermal stability of BiCuSeO

    SciTech Connect

    Barreteau, Celine; Berardan, David Dragoe, Nita

    2015-02-15

    BiCuSeO based materials have been reported as very promising thermoelectric materials, with thermoelectric figure of merit values that make them among the best p-type Pb-free polycrystalline thermoelectric materials, and they could be suitable for applications in thermal to electrical power conversion modules in a 300–650 °C temperature range. In this paper, we report on the phase stability and thermal stability of these materials under inert and oxidizing atmosphere and we discuss their actual potential for wide scale applications. We show that although they are stable in inert atmosphere up to 650 °C, with very slow volatilization rate, it is not the case under oxidizing atmosphere, with a quick oxidation starting at a moderate temperature. - Graphical abstract: BiCuSeO oxidation under air, starting below 300 °C. - Highlights: • Decomposition and oxidation mechanisms of BiCuSeO were studied. • BiCuSeO does not volatilize in inert atmosphere up to 650 °C. • BiCuSeO starts oxidizing for temperatures as low as 200 °C.

  9. Theoretical studies of positron states and annihilation characteristics at the oxidized Cu(100) surface

    SciTech Connect

    Fazleev, N. G.; Weiss, A. H.

    2013-04-19

    In this work we present the results of theoretical studies of positron surface and bulk states and annihilation probabilities of surface-trapped positrons with relevant core electrons at the oxidized Cu(100) surface under conditions of high oxygen coverage. An ab-initio study of the electronic properties of the Cu(100) missing row reconstructed surface at various on surface and sub-surface oxygen coverages has been performed on the basis of the density functional theory (DFT) using the Dmol3 code and the generalized gradient approximation (GGA). Surface structures in calculations have been constructed by adding oxygen atoms to various surface hollow and sub-surface octahedral sites of the 0.5 monolayer (ML) missing row reconstructed phase of the Cu(100) surface with oxygen coverages ranging from 0.5 to 1.5 ML. The charge redistribution at the surface and variations in atomic structure and chemical composition of the topmost layers associated with oxidation and surface reconstruction have been found to affect the spatial extent and localization of the positron surface state wave function and annihilation probabilities of surface trapped positrons with relevant core electrons. Theoretical results are compared with experimental data obtained from studies of oxidation of the Cu(100) surface using positron annihilation induced Auger electron spectroscopy (PAES). It has been shown that positron annihilation probabilities with Cu 3s and 3p core electrons decrease when total (on-surface and sub-surface) oxygen coverage of the Cu(100) surface increases up to 1 ML. The calculations show that for high oxygen coverage when total oxygen coverage is 1. 5 ML the positron is not bound to the surface.

  10. Effects of temperature on Cu structure deposited on Si substrate: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Hidayat, Aulia Fikri; Rosikhin, Ahmad; Syuhada, Ibnu; Winata, Toto

    2016-02-01

    The deposition process of copper onto silicon substrate was studied by the molecular dynamics method. Tersoff, MEAM, and Morse potentials were used to describe the interaction of Si-Si Cu-Cu, and Cu-Si, respectively. Deposition process was performed using NVE ensemble and applying Berendsen thermostat with 0,2 fs timestep for 100 ps. The effect of substrate temperature on the percentage of amorphous structure, radial distribution function (RDF), and coordination number was investigated. The result was indicated that at 300 K, the percentage of amorphous structure was relatively lower compared to another temperature. First peaks of RDF at each temperature were found at radius 3,05 Å and were still relatively wide, indicating short-range order structure.

  11. TL-OSL study of Li{sub 3}PO{sub 4}: Mg, Cu phosphor

    SciTech Connect

    Rahangdale, S. R. Wankhede, S. P.; Dhabekar, B. S.; Palikundwar, U. A.; Moharil, S. V.

    2015-08-28

    In the present work, we report the thermoluminescence and optically stimulated luminescence properties of Mg and Cu doped Li{sub 3}PO{sub 4} phosphor. The phosphor was synthesized by precipitation method. The thermoluminescence dosimetric peak temperature for the phosphor varies with concentrations of Mg and Cu. Li{sub 3}PO{sub 4} shows good response to 470nm optical stimulation. The OSL sensitivity of the phosphor is approximately 12 times than that of standard Lithium magnesium phosphate. This study may help to develop this material for the application in real time dosimetry using optically stimulated luminescence.

  12. XPS and AES Studies of Cu/CdTe(111)-B

    SciTech Connect

    Teeter, G.; Gessert, T. A.; Asher, S. E.

    2005-01-01

    Copper is frequently used as a p-type dopant to improve the performance of back contacts in CdTe thin-film solar cells. In this study, surface-analysis techniques are used to probe fundamental interactions between Cu and the CdTe(111)-B surface. The results presented here were facilitated by the newly constructed surface-analysis cluster tool in the Measurements and Characterization Division at NREL; they reveal a host of fundamental phenomena that occur in the Cu/CdTe system.

  13. Semiconductor bridge, SCB, ignition studies of Al/CuO thermite

    SciTech Connect

    Bickes, R.W. Jr.; Wackerbarth, D.E.; Mohler, J.H.

    1997-04-01

    The authors briefly summarize semiconductor bridge operation and review their ignition studies of Al/CuO thermite as a function of the capacitor discharge unit (CDU) firing set capacitance, charge holder material and morphology of the CuO. Ignition thresholds were obtained using a brass charge holder and a non-conducting fiber-glass-epoxy composite material, G10. At - 18 C and a charge voltage of 50V, the capacitance thresholds were 30.1 {mu}F and 2.0 {mu}F respectively. They also present new data on electrostatic discharge (ESD) and radio frequency (RF) vulnerability tests.

  14. STM study of the atomic structure of the icosahedral Al-Cu-Fe fivefold surface

    NASA Astrophysics Data System (ADS)

    Cai, T.; Fournée, V.; Lograsso, T.; Ross, A.; Thiel, P. A.

    2002-04-01

    We use scanning tunneling microscopy (STM) to investigate the atomic structure of the icosahedral (i-) Al-Cu-Fe fivefold surface in ultra high vacuum (UHV). Studies show that large, atomically flat terraces feature many ten-petal ``flowers'' with internal structure. The observed flower patterns can be associated with features on Al rich dense atomic planes generated from two-dimensional cuts of bulk models based on x-ray and neutron diffraction experiments. The results confirm that the fivefold surface of i-Al-Cu-Fe corresponds to a bulk-terminated plane.

  15. Experimental and Theoretical Studies on Oxidation of Cu-Au Alloy Surfaces: Effect of Bulk Au Concentration.

    PubMed

    Okada, Michio; Tsuda, Yasutaka; Oka, Kohei; Kojima, Kazuki; Diño, Wilson Agerico; Yoshigoe, Akitaka; Kasai, Hideaki

    2016-01-01

    We report results of our experimental and theoretical studies on the oxidation of Cu-Au alloy surfaces, viz., Cu3Au(111), CuAu(111), and Au3Cu(111), using hyperthermal O2 molecular beam (HOMB). We observed strong Au segregation to the top layer of the corresponding clean (111) surfaces. This forms a protective layer that hinders further oxidation into the bulk. The higher the concentration of Au in the protective layer formed, the higher the protective efficacy. As a result, of the three Cu-Au surfaces studied, Au3Cu(111) is the most stable against dissociative adsorption of O2, even with HOMB. We also found that this protective property breaks down for oxidations occurring at temperatures above 300 K. PMID:27516137

  16. Experimental and Theoretical Studies on Oxidation of Cu-Au Alloy Surfaces: Effect of Bulk Au Concentration

    PubMed Central

    Okada, Michio; Tsuda, Yasutaka; Oka, Kohei; Kojima, Kazuki; Diño, Wilson Agerico; Yoshigoe, Akitaka; Kasai, Hideaki

    2016-01-01

    We report results of our experimental and theoretical studies on the oxidation of Cu-Au alloy surfaces, viz., Cu3Au(111), CuAu(111), and Au3Cu(111), using hyperthermal O2 molecular beam (HOMB). We observed strong Au segregation to the top layer of the corresponding clean (111) surfaces. This forms a protective layer that hinders further oxidation into the bulk. The higher the concentration of Au in the protective layer formed, the higher the protective efficacy. As a result, of the three Cu-Au surfaces studied, Au3Cu(111) is the most stable against dissociative adsorption of O2, even with HOMB. We also found that this protective property breaks down for oxidations occurring at temperatures above 300 K. PMID:27516137

  17. A DFT study on the Cu (1 1 1) surface for ethyl acetate synthesis from ethanol dehydrogenation

    NASA Astrophysics Data System (ADS)

    Li, Ruzhen; Zhang, Minhua; Yu, Yingzhe

    2012-07-01

    Copper-based catalysts have shown excellent catalytic performances. Despite extensive studies in the field, the microscopic mechanism of ethanol dehydrogenation to ethyl acetate (EA) on Cu-based catalysts remains controversial. Aiming to provide insight into the catalytic roles of Cu, density functional theory (DFT) calculations have been performed to study the elementary reactions involved in ethanol dehydrogenation to EA on Cu surfaces. In this work, the adsorption properties of ethanol, ethoxy, acetaldehyde, acetyl and EA on the Cu (1 1 1) catalyst surface were investigated. Based on two pathways, many transition states involved are located. The results show that the route proposed by Colley is more likely to happen.

  18. Microstructural study on Kirkendall void formation in Sn-containing/Cu solder joints during solid-state aging.

    PubMed

    Liu, Zhi-Quan; Shang, Pan-Ju; Tan, Feifei; Li, Douxing

    2013-08-01

    Kirkendall void formation at the solder/metallization interface is an important reliability concern for Cu conductors and under-bump metallization in microelectronic packaging industry, whose mechanism is still hard to be understood for different individual cases. In the present work, two typical solder/Cu-diffusing couples, eutectic SnIn/Cu and SnBi/Cu, were studied by scanning/transmission electron microscopy to investigate the microstructural evolution and voiding process after soldering and then solid-state aging. It was concluded that Kirkendall voids formed between two sublayers within Cu2(In,Sn) phase in eutectic SnIn/Cu solder joint, whereas they appeared at the Cu3Sn/Cu interface or within Cu3Sn for eutectic SnBi/Cu solder joint. Besides the effect of impurity elements, the morphological difference within one intermetallic compound layer could change the diffusing rates of reactive species, hence resulting in void formation in the reaction zone. PMID:23920185

  19. Germline ESR2 mutation predisposes to medullary thyroid carcinoma and causes up-regulation of RET expression.

    PubMed

    Smith, Joel; Read, Martin L; Hoffman, Jon; Brown, Rachel; Bradshaw, Beth; Campbell, Christopher; Cole, Trevor; Navas, Johanna Dieguez; Eatock, Fiona; Gundara, Justin S; Lian, Eric; Mcmullan, Dom; Morgan, Neil V; Mulligan, Lois; Morrison, Patrick J; Robledo, Mercedes; Simpson, Michael A; Smith, Vicki E; Stewart, Sue; Trembath, Richard C; Sidhu, Stan; Togneri, Fiona S; Wake, Naomi C; Wallis, Yvonne; Watkinson, John C; Maher, Eamonn R; McCabe, Christopher J; Woodward, Emma R

    2016-05-01

    Familial medullary thyroid cancer (MTC) and its precursor, C cell hyperplasia (CCH), is associated with germline RET mutations causing multiple endocrine neoplasia type 2. However, some rare families with apparent MTC/CCH predisposition do not have a detectable RET mutation. To identify novel MTC/CCH predisposition genes we undertook exome resequencing studies in a family with apparent predisposition to MTC/CCH and no identifiable RET mutation. We identified a novel ESR2 frameshift mutation, c.948delT, which segregated with histological diagnosis following thyroid surgery in family members and demonstrated loss of ESR2-encoded ERβ expression in the MTC tumour. ERα and ERβ form heterodimers binding DNA at specific oestrogen-responsive elements (EREs) to regulate gene transcription. ERβ represses ERα-mediated activation of the ERE and the RET promoter contains three EREs. In vitro, we showed that ESR2 c.948delT results in unopposed ERα mediated increased cellular proliferation, activation of the ERE and increased RET expression. In vivo, immunostaining of CCH and MTC using an anti-RET antibody demonstrated increased RET expression. Together these findings identify germline ESR2 mutation as a novel cause of familial MTC/CCH and provide important insights into a novel mechanism causing increased RET expression in tumourigenesis. PMID:26945007

  20. Synthesis, Characterization, Spectral Studies and Antifungal Activity of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) Complexes with 2-(4- Sulphophenylazo)-1,8-Dihydroxy-3,6-Napthalene Disulphonic Acid Trisodium Salt

    PubMed Central

    Pandey, Gajanan; Narang, K. K.

    2005-01-01

    Complexes of the type Na6[M(HL)2(H2O)2], where M= Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) and Na3H2L= 2-(4-sulphophenylazo)-1,8-dihydroxy 3,6 naphthalene disulphonic acid trisodium salt, have been synthesized and characterized by physico-chemical (elemental analyses, solubility, electrolytic conductance, magnetic susceptibility measurement) and spectral (UV-Visible, IR, ESR, powder x-ray diffraction) techniques for their structure and studied for their antifungal activity against ten fungi. The anionic 1:2 metal:ligand complexes show octahedral geometry around M(II), a significant antifungal activity against Curvularia lunata and Alternaria triticina and a moderate activity against Alternaria brassicicola, Alternaria brassicae, Alternaria solanae, Curvularia species, Helminthosporium oryzae, Collectotrichum capsici, Aspergillus niger, Aspergillus flavus and Fusarium udum. PMID:18365101

  1. Kinetic study of CO oxidation over CuO/MO2 (M = Si, Ti and Ce) catalysts

    NASA Astrophysics Data System (ADS)

    Lu, Ji-Qing; Sun, Chong-Xiang; Li, Na; Jia, Ai-Pin; Luo, Meng-Fei

    2013-12-01

    A series of supported CuO/MO2 catalysts (M = Si, Ti and Ce) were prepared using a chemisorption-hydrolysis method and tested for CO oxidation. Kinetic study was carried out to investigate reaction pathways on these catalysts. The power-rate law reaction expressions over CuO/SiO2, CuO/TiO2 and CuO/CeO2 were r = 1.78 × 10-7Pco0.85Po20.22, r = 1.62 × 10-7Pco0.65Po20.19 and r = 1.5 × 10-7Pco0.7Po20, respectively. Activation energies were calculated to be 74.8, 53.4 and 46.3 kJ mol-1 for the CuO/SiO2, CuO/TiO2 and CuO/CeO2 catalysts respectively. Elementary steps of CO oxidation were also proposed. For the CuO/SiO2 catalysts, a Langmuir-Hinshelwood (L-H) model involving chemisorption of CO and O2 on surface Cu atoms was proposed; for the CuO/TiO2 catalysts, a L-H model involving chemisorption of CO on Cu atoms and chemisorption of O2 on TiO2 was proposed, which resulted in a interfacial reaction between the two species. For the CuO/CeO2 catalysts, a Mars van-Krevelen model involving chemisorbed CO on Cu atoms reacting with lattice oxygen in CeO2 was proposed. Effect of CuO particle size was also evaluated. It was found that the active site on the periphery of the CuO-TiO2 and CuO-CeO2 interface was more active on large CuO crystallite than that on small one. The enhanced activity could be interpreted by the higher concentration of chemisorbed CO on the active site on the larger CuO crystallite.

  2. Study of carbon dioxide adsorption on a Cu-nitroprusside polymorph

    SciTech Connect

    Roque-Malherbe, R.; Lozano, C.; Polanco, R.; Marquez, F.; Lugo, F.; Hernandez-Maldonado, A.; Primera-Pedrozo, J.N.

    2011-05-15

    A careful structural characterization was carried out to unequivocally determine the structure of the synthesized material. The TGA, DRIFTS and a Pawley fitting of the XRD powder profiles indicate that the hydrated and in situ dehydrated polymorph crystallizes in the orthorhombic space group Pnma. Meanwhile, the CO{sub 2} isosteric heat of adsorption appears to be independent of loading with an average value of 30 kJ/mol. This translates to a physisorption type interaction, where the adsorption energy corresponding to wall and lateral interactions are mutually compensated to produce, an apparently, homogeneous adsorption energy. The somewhat high adsorption energy is probably due to the confinement of the CO{sub 2} molecules in the nitroprusside pores. Statistical Physics and the Dubinin theory for pore volume filling allowed model the CO{sub 2} equilibrium adsorption process in Cu-nitroprusside. A DRIFTS test for the adsorbed CO{sub 2} displayed a peak at about 2338 cm{sup -1} that was assigned to a contribution due to physical adsorption of the molecule. Another peak found at 2362 cm{sup -1} evidenced that this molecule interacts with the Cu{sup 2+}, which appears to act as an electron accepting Lewis acid site. The aim of the present paper is to report a Pnma stable Cu-nitroprusside polymorph obtained by the precipitation method that can adsorb carbon dioxide. -- Graphical abstract: The adsorption space of a very well characterized Cu-nitroprusside polymorph, applying carbon dioxide as probe molecule, was studied. Display Omitted Highlights: {yields} Accurate information about the geometry of the adsorption space was provided. {yields} Truthful data about the interactions within the adsorption space was presented. {yields} The structure of the tested Cu-NP polymorph was established. {yields} Was evidenced adsorbed CO{sub 2} molecules in the form of weakly bonded adducts. {yields} Is proposed that adsorbed molecules could change the Cu-NP magnetic properties.

  3. Effects of intrinsic defects on methanthiol monolayers on Cu(111): A density functional theory study

    NASA Astrophysics Data System (ADS)

    Fan, Xiao-Li; Yang, Yong-Liang; Liu, Yan; Lau, Woon-Ming

    2013-04-01

    Density functional theory calculations were used to examine the effects of intrinsic surface defects of Cu(111) on the adsorption of methylthiol (CH3SH). The examination covers both the initial non-dissociative adsorption and the subsequent dissociation reaction pathways to form intermediate and final reaction products. By comparing the most probable adsorption structures likely formed after the adsorption of CH3SH on Cu(111) with and without the presence of adatoms (Cuad) and vacancies, this computational work offers new insights about the geometry and thermodynamic stability of these structures. Particularly, it reveals a new type of surface complexes having two CH3S bonding to one Cuad (referred therein as CH3S-Cuad-CH3S). In addition, this work also yields new reaction dynamics results on transition states and activation barriers. The results reveal that the presence of Cuad indeed significantly changes the kinetics of adsorption and dissociation of CH3SH on Cu(111). The most kinetically favorable reaction pathway turns out to be that involving the formation of a special surface complex formed by one Cuad plus two CH3S fragments from the dissociation of CH3SH, with the two S atoms located at the bridge sites of Cu(111). Finally, this work also gives simulated scanning tunneling microscopic images for the most important adsorption species in the course of the transition from CH3SH/Cu(111) to CH3S/Cu(111), which may stimulate future experimental studies of self-assembled monolayers on practical metal substrates such as thiols on copper.

  4. In Situ XANES Study of CuO/TiO2 Thin Films During Photodegradation of Methylene Blue

    NASA Astrophysics Data System (ADS)

    Hsiung, Tung Li; Wang, H. Paul; Wei, Yu-Ling

    2007-02-01

    Speciation of copper in the CuO/TiO2 thin film (synthesized by the doctor-blade deposition method) during photocatalytic decomposition of methylene blue has been studied by in situ X-ray absorption near-edge structural (XANES) spectroscopy. During the UV/VIS radiation (90 min), in the presence of methylene blue, a decrease of Cu(II) and an increases of Cu(0) and Cu(I) fractions in the CuO/TiO2 thin film are observed by in situ XANES. The r-space Fourier transformation EXAFS (extend X-ray absorption fine structural) spectra also show that the bond distance of Cu-O in the thin film is decreased by 0.03 Å during photocatalytic degradation of methylene blue.

  5. In Situ XANES Study of CuO/TiO2 Thin Films During Photodegradation of Methylene Blue

    SciTech Connect

    Hsiung Tungli; Wang, H. Paul; Wei Yuling

    2007-02-02

    Speciation of copper in the CuO/TiO2 thin film (synthesized by the doctor-blade deposition method) during photocatalytic decomposition of methylene blue has been studied by in situ X-ray absorption near-edge structural (XANES) spectroscopy. During the UV/VIS radiation (90 min), in the presence of methylene blue, a decrease of Cu(II) and an increases of Cu(0) and Cu(I) fractions in the CuO/TiO2 thin film are observed by in situ XANES. The r-space Fourier transformation EXAFS (extend X-ray absorption fine structural) spectra also show that the bond distance of Cu-O in the thin film is decreased by 0.03 A during photocatalytic degradation of methylene blue.

  6. Variations in ESR and CRP in total knee arthroplasty and total hip arthroplasty in Iranian patients from 2009 to 2011

    PubMed Central

    Nazem, Khalilolah; Motififard, Mehdi; Yousefian, Mehdi

    2016-01-01

    Background: Implantation of joint prosthesis, either in the knee or in the hip, may cause some problems such as an infection, so that a timely treatment is essential. In this respect, discovering a marker detecting the incidence of an infection is one of the requirements of arthroplasty. The present study was conducted to determine variations of two markers in arthroplasty and infection incidence in Iranian patients. Materials and Methods: This prospective study was carried out in Isfahan’s educational treatment centers from 2009 to 2011 on patients undergoing total knee arthroplasty (TKA) and total hip arthroplasty (THA) surgical operations. The erythrocyte sedimentation rate (ESR) was measured by Sed rate device (Lena) and C-reactive protein (CRP) by autoanalyzer device (Erba) with the unit of ng/dL. The patients underwent ESR and CRP tests the day before operation, the day of operation, and 1, 2, 5, and 15 days and 1, 3, 6, and 12 months after operation. Results: Mean ESR increased during the first 5 days then decreased gradually lasting for 3 months. After 1 year it increased to a level higher than before the operation. The variations in ESR values were 19.1 ± 12.9 before the operation and 21.14 ± 10.8 after 1 year with significant difference (P < 0.001). The level of CRP had an upward trend from the first day after operation and reached its maximum on the second day, then had a downward trend up to 1 month after the operation; however, it did not reach its preoperative level during 1 year. Conclusion: ESR and CRP and their variations can be suitable factors to detect probable infections in patients undergoing TKA and THA operations.

  7. Variations in ESR and CRP in total knee arthroplasty and total hip arthroplasty in Iranian patients from 2009 to 2011

    PubMed Central

    Nazem, Khalilolah; Motififard, Mehdi; Yousefian, Mehdi

    2016-01-01

    Background: Implantation of joint prosthesis, either in the knee or in the hip, may cause some problems such as an infection, so that a timely treatment is essential. In this respect, discovering a marker detecting the incidence of an infection is one of the requirements of arthroplasty. The present study was conducted to determine variations of two markers in arthroplasty and infection incidence in Iranian patients. Materials and Methods: This prospective study was carried out in Isfahan’s educational treatment centers from 2009 to 2011 on patients undergoing total knee arthroplasty (TKA) and total hip arthroplasty (THA) surgical operations. The erythrocyte sedimentation rate (ESR) was measured by Sed rate device (Lena) and C-reactive protein (CRP) by autoanalyzer device (Erba) with the unit of ng/dL. The patients underwent ESR and CRP tests the day before operation, the day of operation, and 1, 2, 5, and 15 days and 1, 3, 6, and 12 months after operation. Results: Mean ESR increased during the first 5 days then decreased gradually lasting for 3 months. After 1 year it increased to a level higher than before the operation. The variations in ESR values were 19.1 ± 12.9 before the operation and 21.14 ± 10.8 after 1 year with significant difference (P < 0.001). The level of CRP had an upward trend from the first day after operation and reached its maximum on the second day, then had a downward trend up to 1 month after the operation; however, it did not reach its preoperative level during 1 year. Conclusion: ESR and CRP and their variations can be suitable factors to detect probable infections in patients undergoing TKA and THA operations. PMID:27656617

  8. Cu(2+) and Fe(2+) mediated photodegradation studies of soil-incorporated chlorpyrifos.

    PubMed

    Rafique, Nazia; Tariq, Saadia R; Ahad, Karam; Taj, Touqeer

    2016-03-01

    The influences of Cu(2+) and Fe(2+) on the photodegradation of soil-incorporated chlorpyrifos were investigated in the present study. The soil samples spiked with chlorpyrifos and selected metal ions were irradiated with UV light for different intervals of time and analyzed by HPLC. The unsterile and sterile control soil samples amended with pesticides and selected metals were incubated in the dark at 25 °C for the same time intervals. The results of the study evidenced that photodegradation of chlorpyrifos followed the first-order kinetics. The dissipation t0.5 of chlorpyrifos was found to decrease from 41 to 20 days under UV irradiation. The rate of chlorpyrifos photodegradation was increased in the presence of both metals, i.e., Cu(2+) and Fe(2+). Thus, initially observed t0.5 of 19.8 days was decreased to 4.39 days in the case of Cu(+2) and 19.25 days for Fe(+2). Copper was found to increase the rate of photodegradation by 4.5 orders of magnitude while the microbial degradation of chlorpyrifos was increased only twofold. The microbial degradation of chlorpyrifos was only negligibly affected by Fe(2+) amendment. The studied trace metals also affected the abiotic degradation of the pesticide in the order Cu(2+) > Fe(2+).

  9. Covellite CuS as a matrix for "invisible" gold: X-ray spectroscopic study of the chemical state of Cu and Au in synthetic minerals

    NASA Astrophysics Data System (ADS)

    Tagirov, Boris R.; Trigub, Alexander L.; Kvashnina, Kristina O.; Shiryaev, Andrey A.; Chareev, Dmitriy A.; Nickolsky, Maximilian S.; Abramova, Vera D.; Kovalchuk, Elena V.

    2016-10-01

    Geological processes leading to formation of sulfide ores often result in precipitation of gold-bearing sulfides which can contain high concentrations of this metal in "invisible" (or "refractory") state. Covellite (CuS) is ubiquitous mineral in many types of the ore deposits, and numerous studies of the natural ores show that covellite can contain high concentrations of Au. At the same time, Au-bearing covellite withstands cooling in contrast to other minerals of the Cu-Fe-S system (chalcocite, bornite, chalcopyrite), where Au exsolves at low temperatures. This makes covellite a convenient model system for investigation of the chemical state (local environment and valence) of the "invisible" Au in copper-sulfide ores (copper-porphyry, epithermal, volcanogenic massive sulfide, SEDEX deposits). Therefore, it is necessary to determine the location of Au in the covellite matrix as it will have important implications for the methods employed by mineral processing industry to extract Au from sulfide ores. Here we investigate the chemical state of Cu and Au in synthetic covellite containing up to 0.3 wt.% of Au in the "invisible" state. The covellite crystals were synthesized by hydrothermal and salt flux methods. Formation of the chemically bound Au is indicated by strong dependence of the concentration of Au in covellite on the sulfur fugacity in the experimental system (d(log C(Au))/d(log f(S2)) ∼ 0.65). The Au concentration of covellite grows with increasing temperature from 400 to 450 °C, whereas further temperature increase to 500 °C has only minor effect. The synthesized minerals were studied using X-ray absorption fine structure spectroscopy (XAFS) in high energy resolution fluorescence detection (HERFD) mode. Ab initio simulations of Cu K edge XANES spectra show that the Cu oxidation state in two structural positions in covellite (tetrahedral and triangular coordination with S atoms) is identical: the total loss of electronic charge for the 3d shell is ∼0

  10. A DFT study on CO oxidation catalyzed by subnanometer AlCu n ( n = 1-3) clusters

    NASA Astrophysics Data System (ADS)

    Dong, Xiaona; Guo, Ling; Wen, Caixia; Ren, Ningning; Niu, Shuangshu

    2014-07-01

    Through the first-principle density-functional theory (DFT) calculations, we have made an exhaustive study of the mechanism of CO oxidation catalyzed by AlCu n ( n = 1-3) clusters on gas phase. It is shown that mixing two different metals (Al and Cu) can have beneficial effects on the catalytic activity than monometallic Cu n + 1 ( n = 1-3) cluster toward the reaction of CO oxidation and the alloyed AlCu3 cluster is proposed as the best effective nanocatalysts.

  11. Visualization of Ancient Frictional Heat by 2-Dimensional ESR Imaging

    NASA Astrophysics Data System (ADS)

    Fukuchi, T.

    2006-12-01

    Fault gouge in the immediate vicinity of a fault plane is often darkened and magnetized. This fact suggests that paramagnetic iron hydroxides (γ-FeOOH or Fe(OH)3) inside the fault gouge have changed into ferrimagnetic iron oxides, maghemite (γ-Fe2O3), by frictional heating [Fukuchi, 2003; Fukuchi et al., 2005]. Our results from both melting experiments and exhumed faults indicate that granitic rocks without iron hydroxides may be also magnetized by frictional heating due to the production of magnetite (Fe3O4) by thermal decomposition of constituent biotite. Thus ferrimagnetic minerals in fault rocks are available as indicators of ancient frictional heating events. Generally frictional heat generates within a few millimeters wide zone along a fault plane and its temperature suddenly changes in a 1mm unit. Hence continuous magnetic analysis of a fault zone is necessary for elucidating frictional heating events. I thus attempt to two-dimensionally detect ferrimagnetic minerals using the electron spin resonance (ESR) technique. In 2-Dimensional ESR imaging, microwaves leaking out of a 3mmφ pinhole bored on a cavity resonator are directly absorbed by a flat slab sample moving two-dimensionally with an X-Y stage. Though the detective sensitivity is much lower than that in ordinary ESR measurement, ferrimagnetic minerals show very strong ESR absorption due to exchange interaction, namely, ferrimagnetic resonance (FMR) absorption. Furthermore, the FMR signal intensity reflects the total number of spins in ferrimagnetic material and then is proportional to initial magnetic susceptibility. Hence we can carry out highly sensitive magnetic analysis by detecting FMR signals. As a result of 2D ESR imaging of pseudotachylyte layers distributed along the Nojima fault in Japan, high FMR signal intensity, that is, high frictional heat has been detected along a fault plane in the pseudotachylyte layers. At this stage the resolution of 2D ESR images is 0.5mm, however it is possible

  12. Study of Height Reduction of Sn99Cu1/Cu Solder Joints as a Result of Isothermal Aging

    NASA Astrophysics Data System (ADS)

    Chen, Zhiwen; Liu, Changqing; Wu, Yiping; An, Bing; Zhou, Longzao

    2015-11-01

    Sn99Cu1/Cu solder joints were investigated after isothermal aging at 175°C for different lengths of time under vacuum conditions. The results revealed height reduction of the solder of approximately 1.2 μm after aging for 1132.5 h. This was primarily attributed to growth of a layer of interfacial intermetallic compounds. The reduction was measured by use of a copper block containing a recess filled with solder, which was reflowed then polished flat. Height reduction of the solder joint during aging was found to obey the parabolic law Δ h = -0.031√ t, and was in excellent agreement with theoretical calculation.

  13. Adsorption studies of Cu(II) onto biopolymer chitosan and its nanocomposite 5%bentonite/chitosan.

    PubMed

    Moussout, Hamou; Ahlafi, Hammou; Aazza, Mustapha; Zegaoui, Omar; El Akili, Charaf

    2016-01-01

    Chitosan (CS) and nanocomposite 5%bentonite/chitosan (5%Bt/CS) prepared from the natural biopolymer CS were tested to remove Cu(II) ions using a batch adsorption experiment at various temperatures (25, 35 and 45°C). X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis/differential thermal analysis (TGA/DTA) were used in CS and the nanocomposite characterisation. This confirmed the exfoliation of bentonite (Bt) to form the nanocomposite. The adsorption kinetics of copper on both solids was found to follow a pseudo-second-order law at each studied temperature. The Cu(II) adsorption capacity increased as the temperature increased from 25 to 45°C for nanocomposite adsorbent but slightly increased for CS. The data were confronted to the nonlinear Langmuir, Freundlich and Redlich-Peterson models. It was found that the experimental data fitted very well the Langmuir isotherm over the whole temperature and concentration ranges. The maximum monolayer adsorption capacity for the Cu(II) was 404-422 mg/g for CS and 282-337 mg/g for 5%Bt/CS at 25-45°C. The thermodynamic study showed that the adsorption process was spontaneous and endothermic. The complexation of Cu(II) with NH(2) and C = O groups as active sites was found to be the main mechanism in the adsorption processes. PMID:27148722

  14. Structural Study of Cu-Deficient Cu2(1-x)ZnSnSe4 Solar Cell Materials by X-ray Diffraction and X-ray Absorption Fine Structure

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Yamazoe, Seiji; Maeda, Tsuyoshi; Wada, Takahiro

    2012-10-01

    Cu-poor Cu2(1-x)ZnSnSe4 powders were prepared from elemental powders. The crystal structure of Cu-poor Cu2(1-x)ZnSnSe4 was examined by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) analyses. Kesterite-type Cu2(1-x)ZnSnSe4 could be prepared in the range of 0≤x ≤0.0750. The lattice parameters were refined by the Rietveld analysis of X-ray diffraction data. The lattice constants a and c decreased with a decrease in the Cu/(Zn+Sn) ratio. However, there was little change in c/a value. On the other hand, the position of the Se atom (u parameters) changed considerably. The XAFS study showed that the local structure of Sn in Cu2ZnSnSe4 (CZTSe) changed with a decrease in Cu/(Zn+Sn) ratio and the local structural changes in Cu, Zn, or Se could not be clearly observed. These local structural changes around Sn are due to the disordering of Cu, Zn, and Sn atoms. The diffuse reflectance spectra showed that the band gap of Cu2ZnSnSe4 is 0.98 eV and that the band gaps do not depend on Cu/(Zn+Sn) ratio in the range of 0≤x ≤0.0750.

  15. The mining chemical Polydadmac is cytotoxic but does not interfere with Cu-induced toxicity in Atlantic salmon hepatocytes.

    PubMed

    Olsvik, Pål A; Berntssen, Marc H G; Waagbø, Rune; Hevrøy, Ernst; Søfteland, Liv

    2015-12-25

    To speed up sedimentation of suspended solids the mining industry often uses flocculent chemicals. In this work we evaluated the cytotoxic and mechanistic effects of Polydadmac, and its basic component Dadmac, on fish cells. Dose-response effects, temperature-dependent effects and impact of Dadmac and Polydadmac on Cu toxicity were studied in Atlantic salmon hepatocytes. We used the xCELLigence system and the MTT test for cytotoxicity assessments, and real-time RT-qPCR to evaluate molecular effects. The results showed a cytotoxic response for Polydadmac but not for Dadmac. Elevated levels of Cu were cytotoxic. Moderately cytotoxic concentrations of Cu (100-1000 μM) induced significant responses on the transcription of a number of genes in the cells, i.e. cuznsod (sod1), cat, mnsod (sod2), nfe2l2, hmox1, mta, casp3b, casp6, bclx, cyp1a, ccs, atp7a, app, mmp13, esr1, ppara, fads2 and ptgs2. A factorial PLS regression model for mnsod transcription showed a synergistic effect between Dadmac and Cu exposure in the cells, indicating an interaction effect between Dadmac and Cu on mitochondrial ROS scavenging. No interaction effects were seen for Polydadmac on Cu toxicity. In conclusion, Polydadmac is cytotoxic at elevated concentrations but appears to have low ability to interfere with Cu toxicity in Atlantic salmon liver cells.

  16. Magnetic excitations in the spin-1/2 triangular-lattice antiferromagnet Cs2CuBr4

    DOE PAGESBeta

    Zvyagin, S. A.; Ozerov, M.; Kamenskyi, D.; Wosnitza, J.; Krzystek, J.; Yoshizawa, D.; Hagiwara, M.; Hu, Rongwei; Ryu, Hyejin; Petrovic, C.; et al

    2015-11-27

    We present on high- field electron spin resonance (ESR) studies of magnetic excitations in the spin- 1/2 triangular-lattice antiferromagnet Cs2CuBr4. Frequency- field diagrams of ESR excitations are measured for different orientations of magnetic fields up to 25 T. We show that the substantial zero- field energy gap, Δ ≈ 9.5 K, observed in the low-temperature excitation spectrum of Cs2CuBr4 [Zvyagin et al:, Phys. Rev. Lett. 112, 077206 (2014)], is present well above TN. Noticeably, the transition into the long-range magnetically ordered phase does not significantly affect the size of the gap, suggesting that even below TN the high-energy spin dynamicsmore » in Cs2CuBr4 is determined by short-range-order spin correlations. The experimental data are compared with results of model spin-wave-theory calculations for spin-1/2 triangle-lattice antiferromagnet.« less

  17. Magnetic excitations in the spin-1/2 triangular-lattice antiferromagnet Cs2CuBr4

    NASA Astrophysics Data System (ADS)

    Zvyagin, S. A.; Ozerov, M.; Kamenskyi, D.; Wosnitza, J.; Krzystek, J.; Yoshizawa, D.; Hagiwara, M.; Hu, Rongwei; Ryu, Hyejin; Petrovic, C.; Zhitomirsky, M. E.

    2015-11-01

    We report on high-field electron spin resonance (ESR) studies of magnetic excitations in the spin-1/2 triangular-lattice antiferromagnet Cs2CuBr4. Frequency-field diagrams of ESR excitations are measured for different orientations of magnetic fields up to 25 T. We show that the substantial zero-field energy gap, {{Δ }}≈ 9.5 K, observed in the low-temperature excitation spectrum of Cs2CuBr4, (Zvyagin et al 2014 Phys. Rev. Lett.112 077206) is present well above TN. Noticeably, the transition into the long-range magnetically ordered phase does not significantly affect the size of the gap, suggesting that even below TN the high-energy spin dynamics in Cs2CuBr4 is determined by short-range-order spin correlations. The experimental data are compared with results of model spin-wave-theory calculations for spin-1/2 triangular-lattice antiferromagnet.

  18. Density functional theory study of O-H and C-H bond scission of methanol catalyzed by a chemisorbed oxygen layer on Cu(111)

    NASA Astrophysics Data System (ADS)

    Li, Jonathan; Zhou, Guangwen

    2016-04-01

    Using the density-functional theory within the generalized gradient approximation, we have studied the partial oxidation of methanol on a Cu(111) surface covered with a chemisorbed oxygen layer that resembles a Cu2O layer. Adsorption energies and geometries were computed for methanol, methoxy, hydroxymethyl and formaldehyde on both clean Cu(111) and Cu2O/Cu(111) and electronic structures were computed for the reaction intermediates on Cu2O/Cu(111). We also calculated the energy barrier for partial oxidation of methanol to formaldehyde on Cu2O/Cu(111). These results show that the Cu2O monolayer slightly lowers the stability of each of the surface adsorbates and the oxygen strongly promotes hydrogen dissociation by lowering the energy barrier of methanol decomposition and causing the spontaneous dissociation of methanol into methoxy.

  19. Electronic structure calculations of ESR parameters of melanin units.

    PubMed

    Batagin-Neto, Augusto; Bronze-Uhle, Erika Soares; Graeff, Carlos Frederico de Oliveira

    2015-03-21

    Melanins represent an important class of natural pigments present in plants and animals that are currently considered to be promising materials for applications in optic and electronic devices. Despite their interesting properties, some of the basic features of melanins are not satisfactorily understood, including the origin of their intrinsic paramagnetism. A number of experiments have been performed to investigate the electron spin resonance (ESR) response of melanin derivatives, but until now, there has been no consensus regarding the real structure of the paramagnetic centers involved. In this work, we have employed electronic structure calculations to evaluate the ESR parameters of distinct melanin monomers and dimers in order to identify the possible structures associated with unpaired spins in this biopolymer. The g-factors and hyperfine constants of the cationic, anionic and radicalar structures were investigated. The results confirm the existence of at least two distinct paramagnetic centers in melanin structure, identifying the chemical species associated with them and their roles in electrical conductivity.

  20. The Cubesat mission to study Solar Particles (CuSP), an interplanetary cubesat

    NASA Astrophysics Data System (ADS)

    Christian, E. R.; Desai, M. I.; Allegrini, F.; Jahn, J. M.; Kanekal, S.; Livi, S. A.; Murphy, N.; Ogasawara, K.; Paschalidis, N.

    2015-12-01

    The Cubesat mission to study Solar Particles (CuSP) is a funded 6U interplanetary cubesat scheduled to fly on the EM-1 SLS launch in 2018. CuSP has three small but capable instruments from the Southwest Research Institute (SwRI), NASA Goddard Space Flight Center (GSFC), and the NASA Jet Propulsion Laboratory (JPL). Its primary scientific goal is high-cadence precise measurements of the suprathermal (ST) tail in the solar wind. The suprathermal tail is the critical bridge between the thermal solar wind plasma and the dangerous high-energy solar energetic particles. CuSP also measures the energy spectra and composition of the ~1-50 MeV/nucleon H-Fe ions that evolve from the STs and the interplanetary magnetic field that is closely coupled to the particle distributions. CuSP is a stepping-stone to future interplanetary cubesats, smallsats, and constellations for both scientific and space weather applications. The challenges for this mission and future missions will also be discussed.

  1. Biosorption of Cu(II) by immobilized microalgae using silica: kinetic, equilibrium, and thermodynamic study.

    PubMed

    Lee, Hongkyun; Shim, Eunjung; Yun, Hyun-Shik; Park, Young-Tae; Kim, Dohyeong; Ji, Min-Kyu; Kim, Chi-Kyung; Shin, Won-Sik; Choi, Jaeyoung

    2016-01-01

    Immobilized microalgae using silica (IMS) from Micractinium reisseri KGE33 was synthesized through a sol-gel reaction. Green algal waste biomass, the residue of M. reisseri KGE33 after oil extraction, was used as the biomaterial. The adsorption of Cu(II) on IMS was tested in batch experiments with varying algal doses, pH, contact times, initial Cu(II) concentrations, and temperatures. Three types of IMSs (IMS 14, 70, and 100) were synthesized according to different algal doses. The removal efficiency of Cu(II) in the aqueous phase was in the following order: IMS 14 (77.0%) < IMS 70 (83.3%) < IMS 100 (87.1%) at pH 5. The point of zero charge (PZC) value of IMS100 was 4.5, and the optimum pH for Cu(II) adsorption was 5. Equilibrium data were described using a Langmuir isotherm model. The Langmuir model maximum Cu(II) adsorption capacity (q m) increased with the algal dose in the following order: IMS 100 (1.710 mg g(-1)) > IMS 70 (1.548 mg g(-1)) > IMS 14 (1.282 mg g(-1)). The pseudo-second-order equation fitted the kinetics data well, and the value of the second-order rate constant increased with increasing algal dose. Gibbs free energies (ΔG°) were negative within the temperature range studied, which indicates that the adsorption process was spontaneous. The negative value of enthalpy (ΔH°) again indicates the exothermic nature of the adsorption process. In addition, SEM-energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses of the IMS surface reveal that the algal biomass on IMS is the main site for Cu(II) binding. This study shows that immobilized microalgae using silica, a synthesized biosorbent, can be used as a cost-effective sorbent for Cu(II) removal from the aqueous phase.

  2. Biosorption of Cu(II) by immobilized microalgae using silica: kinetic, equilibrium, and thermodynamic study.

    PubMed

    Lee, Hongkyun; Shim, Eunjung; Yun, Hyun-Shik; Park, Young-Tae; Kim, Dohyeong; Ji, Min-Kyu; Kim, Chi-Kyung; Shin, Won-Sik; Choi, Jaeyoung

    2016-01-01

    Immobilized microalgae using silica (IMS) from Micractinium reisseri KGE33 was synthesized through a sol-gel reaction. Green algal waste biomass, the residue of M. reisseri KGE33 after oil extraction, was used as the biomaterial. The adsorption of Cu(II) on IMS was tested in batch experiments with varying algal doses, pH, contact times, initial Cu(II) concentrations, and temperatures. Three types of IMSs (IMS 14, 70, and 100) were synthesized according to different algal doses. The removal efficiency of Cu(II) in the aqueous phase was in the following order: IMS 14 (77.0%) < IMS 70 (83.3%) < IMS 100 (87.1%) at pH 5. The point of zero charge (PZC) value of IMS100 was 4.5, and the optimum pH for Cu(II) adsorption was 5. Equilibrium data were described using a Langmuir isotherm model. The Langmuir model maximum Cu(II) adsorption capacity (q m) increased with the algal dose in the following order: IMS 100 (1.710 mg g(-1)) > IMS 70 (1.548 mg g(-1)) > IMS 14 (1.282 mg g(-1)). The pseudo-second-order equation fitted the kinetics data well, and the value of the second-order rate constant increased with increasing algal dose. Gibbs free energies (ΔG°) were negative within the temperature range studied, which indicates that the adsorption process was spontaneous. The negative value of enthalpy (ΔH°) again indicates the exothermic nature of the adsorption process. In addition, SEM-energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses of the IMS surface reveal that the algal biomass on IMS is the main site for Cu(II) binding. This study shows that immobilized microalgae using silica, a synthesized biosorbent, can be used as a cost-effective sorbent for Cu(II) removal from the aqueous phase. PMID:25953610

  3. Synthesis, characterization, thermal study and biological evaluation of Cu(II), Co(II), Ni(II) and Zn(II) complexes of Schiff base ligand containing thiazole moiety

    NASA Astrophysics Data System (ADS)

    Nagesh, G. Y.; Mahendra Raj, K.; Mruthyunjayaswamy, B. H. M.

    2015-01-01

    The novel Schiff base ligand 2-(4-(dimethylamino)benzylidene)-N-(4-phenylthiazol-2-yl)hydrazinecarboxamide (L) obtained by the condensation of N-(4-phenylthiazol-2-yl)hydrazinecarboxamide with 4-dimethylaminobenzaldehyde and its newly synthesized Cu(II), Co(II), Ni(II) and Zn(II) complexes have been characterized by microanalysis, magnetic susceptibility, molar conductance, thermal analysis, FT-IR, 1H NMR, ESI mass, UV-Visible, ESR spectroscopy and powder X-ray diffraction data. The newly synthesized ligand behaves as a bidentate ON donor. The IR results confirmed the bidentate binding of the ligand involving oxygen atom of amide carbonyl and azomethine nitrogen. 1H NMR spectral data of the ligand (L) and its Zn(II) complex agreed well with the proposed structures. In order to evaluate the effect of antimicrobial activity of metal ions upon chelation, the newly synthesized ligand and its metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleavage activities were studied using plasmid DNA pBR322 as a target molecule by agarose gel electrophoresis method. The brine shrimp bioassay was also carried out to study the in vitro cytotoxicity properties of all the compounds against Artemia salina. Furthermore, the antioxidant activity of the ligand (L) and its metal complexes were determined in vitro by reduction of 1,1-diphenyl-2-picryl hydrazyl (DPPH), the ligand exhibited potent in vitro - antioxidant activity than its metal complexes.

  4. ESR detection procedure of irradiated papaya containing high water content

    NASA Astrophysics Data System (ADS)

    Kikuchi, Masahiro; Shimoyama, Yuhei; Ukai, Mitsuko; Kobayashi, Yasuhiko

    2011-05-01

    ESR signals were recorded from irradiated papaya at liquid nitrogen temperature (77 K), and freeze-dried irradiated papaya at room temperature (295 K). Two side peaks from the flesh at the liquid nitrogen temperature indicated a linear dose response for 3-14 days after the γ-irradiation. The line shapes recorded from the freeze-dried specimens were sharper than those at liquid nitrogen temperature.

  5. Status of the ESR and Prospects for Radioactive Ion Beams

    SciTech Connect

    Franzke, B.; Beckert, K.; Groening, L.; Nolden, F.; Steck, M.

    2000-12-31

    This contribution presents the status of the Experimental Storage Ring ESR at GSI after nearly 10 years of experiments with electron-cooled primary and secondary heavy ion beams, and discusses possible upgrades for the near future. The major fraction of the ESR beam time was dedicated to atomic spectroscopy experiments with fully stripped or few-electron heavy ions up to uranium. Remarkable nuclear physics results came, so far, mainly from the precise Schottky mass spectrometry with cooled radioactive fragments. The experimental program of a future--very likely modified--ESR aims at nuclear physics experiments with secondary, neutron-rich or neutron-deficient nuclides with lifetimes in the order of 1 s. Luminosities of up to 1{times}10{sup 29} cm{sup {minus}2}s{sup {minus}1} for collisions with protons of an internal H{sub 2} target and up to 1{times}10{sup 28} cm{sup {minus}2}s{sup {minus}1} for electron-nucleus interactions in the collider mode will be required. These values might b e in reach by improving both the collection efficiency and the cooling speed for the secondary nuclei and by further increasing the primary beam intensity at the heavy ion accelerator complex UNILAC/SIS.

  6. The Representation of Mixtures in the ESR Model for QM

    SciTech Connect

    Garola, Claudio; Sozzo, Sandro

    2010-05-04

    The extended semantic realism(ESR)model proposes a new theoretical perspective which embodies the mathematical formalism of Hilbert space quantum mechanics (QM) into a broader noncontextual, hence local, framework, reinterpreting quantum probabilities as conditional(in a nonstandard sense). We have proven in a previous paper that each generalized observable introduced by the ESR model is represented by a family of positive operator valued measures(POVM) parametrized by the pure states of the physical system OMEGA that is considered. We show here that each mixture is represented in the ESR model by a family of density operators parametrized by the physical properties characterizing OMEGA. This representation implies predictions that may differ from those of QM and avoids some deep problems that arise in the interpretation of mixtures provided by QM. We also show that the state transformations induced by idealized nondestructive measurements can be obtained by means of a nontrivial generalization of the Lueders postulate, and discuss our results in the special case of discrete generalized observables.

  7. The effect of process parameters on the thermal conditions during moving mold ESR

    SciTech Connect

    Heilman, J.E.; Damkroger, B.K.

    1994-09-01

    Several experimental melts were conducted using a moving mold electroslag remelting furnace. The conditions of electrode immersion depth, slag cap thickness, and melt current were varied. Mold wall temperatures and slag pool temperatures were measured and the heat flux through the mold wall was calculated. The relationships between varying ESR melt parameters and the resultant thermal conditions were examined. The thermal profile of the mold, the heat transfer to the mold coolant total and fractional, and the formation of a slag skin were studied.

  8. Diffusion within α-CuI studied using ab initio molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Mohn, Chris E.; Stølen, Svein; Hull, Stephen

    2009-08-01

    The structure and dynamics of superionic α-CuI are studied in detail by means of ab initio Born-Oppenheimer molecular dynamics simulations. The extreme cation disorder and a soft immobile face centred cubic sublattice are evident from the highly diffuse atomic density profiles. The Cu-Cu pair distribution function and distribution of Cu-I-Cu bond angles possess distinct peaks at 2.6 Å and 60° respectively, which are markedly lower than the values expected from the average cationic density, pointing to the presence of pronounced short-range copper-copper correlations. Comparison with lattice static calculations shows that these correlations and the marked shift in the cationic density profile in the lang111rang directions are associated with a locally distorted cation sublattice, and that the movements within the tetrahedral cavities involve rapid jumps into and out of shallow basins on the system potential energy surface. On average, the iodines are surrounded by three coppers within their first coordination shell, with the fourth copper being located in a transition zone between two neighbouring iodine cavities. However, time-resolved analysis reveals that the local structure actually involves a mixture of threefold-, fourfold- and fivefold-coordinated iodines. Examination of the ionic trajectories shows that the copper ions jump rapidly to nearest neighbouring tetrahedral cavities (aligned in the lang100rang directions) following a markedly curved trajectory and often involving short-lived (~1 ps) interstitial positions. The nature of the correlated diffusion underlying the unusually high fraction of coppers with short residence time can be attributed to the presence of a large number of 'unsuccessful' jumps and the likelihood of cooperative motion of pairs of coppers. The calculated diffusion coefficient at 750 K, DCu = 2.8 × 10-5 cm2 s-1, is in excellent agreement with that found experimentally.

  9. Scanning Tunneling Microscopy Studies of Surface Structures of Icosahedral Al-Cu-Fe Quasicrystals

    SciTech Connect

    Tanhong Cai

    2002-12-31

    Three papers are included in this dissertation. The first paper: ''Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED studies'', is in press with ''Surface Science''. The second paper: ''An STM study of the atomic structure of the icosahedral Al-Cu-Fe fivefold surface'' is submitted to ''Physical Review B, Rapid Communication''. The third paper: ''Pseudomorphic starfish: arrangement of extrinsic metal atoms on a quasicrystalline substrate'' is submitted to ''Nature''. Following the third paper are general conclusions and appendices that document the published paper ''Structural aspects of the three-fold surface of icosahedral Al-Pd-Mn'' (appearing in volume 461, issue 1-3 of ''Surface Science'' on page L521-L527, 2000), the design as well as the specifications of the aluminum evaporator used in the aluminum deposition study in this dissertation, an extended discussion of the aluminum deposition on the quasicrystalline surface, and the STM database.

  10. Matrix isolation ESR spectroscopy and magnetic anisotropy of D{sub 3h} symmetric septet trinitrenes

    SciTech Connect

    Misochko, Eugenii Ya.; Akimov, Alexander V.; Masitov, Artem A.; Korchagin, Denis V.; Aldoshin, Sergei M.; Chapyshev, Sergei V.

    2013-05-28

    The fine-structure (FS) parameters D of a series of D{sub 3h} symmetric septet trinitrenes were analyzed theoretically using density functional theory (DFT) calculations and compared with the experimental D values derived from ESR spectra. ESR studies show that D{sub 3h} symmetric septet 1,3,5-trichloro-2,4,6-trinitrenobenzene with D=-0.0957 cm{sup -1} and E= 0 cm{sup -1} is the major paramagnetic product of the photolysis of 1,3,5-triazido-2,4,6-trichlorobenzene in solid argon matrices at 15 K. Trinitrenes of this type display in the powder X-band ESR spectra intense Z{sub 1}-transition at very low magnetic fields, the position of which allows one to precisely calculate the parameter D of such molecules. Thus, our revision of the FS parameters of well-known 1,3,5-tricyano-2,4,6-trinitrenobenzene [E. Wasserman, K. Schueller, and W. A. Yager, Chem. Phys. Lett. 2, 259 (1968)] shows that this trinitrene has Double-Vertical-Line D Double-Vertical-Line = 0.092 cm{sup -1} and E= 0 cm{sup -1}. DFT calculations reveal that, unlike C{sub 2v} symmetric septet trinitrenes, D{sub 3h} symmetric trinitrenes have the same orientations of the spin-spin coupling tensor D-caret{sub SS} and the spin-orbit coupling tensor D-caret{sub SOC} and, as a result, have negative signs for both the D{sub SS} and D{sub SOC} values. The negative magnetic anisotropy of septet 2,4,6-trinitrenobenzenes is considerably strengthened on introduction of heavy atoms in the molecules, owing to an increase in contributions of various excitation states to the D{sub SOC} term.

  11. Electron spin relaxation time measurements using radiofrequency longitudinally detected ESR and application in oximetry.

    PubMed

    Panagiotelis, I; Nicholson, I; Hutchison, J M

    2001-03-01

    Longitudinally detected ESR (LODESR) involves transverse ESR irradiation with a modulated source and observing oscillations in the spin magnetization parallel to the main magnetic field. In this study, radiofrequency-LODESR was used for oximetry by measuring the relaxation times of the electron. T1e and T2e were measured by investigating LODESR signal magnitude as a function of detection frequency. We have also predicted theoretically and verified experimentally the LODESR signal phase dependence on detection frequency and relaxation times. These methods are valid even for inhomogeneous lines provided that T1e>T2e. We have also developed a new method for measuring T1e, valid for inhomogeneous spectra, for all values of T1e and T2e, based on measuring the spectral area as a function of detection frequency. We have measured T1e and T2e for lithium phthalocyanine crystals, for the nitroxide TEMPOL, and for the single line agent Triarylmethyl (TAM). Furthermore, we have collected spectra from aqueous solutions of TEMPOL and TAM at different oxygen concentrations and confirmed that T1e values are reduced with increased oxygen concentration. We have also measured the spin-lattice electronic relaxation time for degassed aqueous solutions of the same agents at different agent concentrations. T1e decreases as a function of concentration for TAM while it remains independent of free radical concentration for TEMPOL, a major advantage for oxygen mapping. This method, combined with the ability of LODESR to provide images of exogenous free radicals in vivo, presents an attractive alternative to the conventional transverse ESR linewidth based oximetry methods.

  12. Study on the phase evolution of (Pb,Cu)Sr2(Y,Ca)Cu2Oz (z 7)

    NASA Astrophysics Data System (ADS)

    Maeda, T.; Taniwaki, M.

    2006-09-01

    The formation process of (Pb(1+x )/2Cu(1-x )/2)Sr2(Y1-x Cax )Cu2Oz is investigated by means of X-ray diffractometory (XRD), thermal analysis and scanning electron microscopy for nominal compositions of x = 00.5. It is shown by XRD measurement that nearly single-phase samples are obtained at x = 00.4 by firing at 1000 °C in air for only 1 h. In the heating step, the existence of partial melting state slightly below the firing temperature is clearly observed in the results of differential thermal analysis. It is concluded that this causes the extremely rapid formation of this compound.

  13. Study of Zn-Cu Ferrite Nanoparticles for LPG Sensing

    PubMed Central

    Jain, Anuj; Baranwal, Ravi Kant; Bharti, Ajaya; Vakil, Z.; Prajapati, C. S.

    2013-01-01

    Nanostructured zinc-copper mixed ferrite was synthesized using sol-gel method. XRD patterns of different compositions of zinc-copper ferrite, Zn(1−x)CuxFe2O4 (x = 0.0, 0.25, 0.50, 0.75), revealed single phase inverse spinel ferrite in all the samples synthesized. With increasing copper concentration, the crystallite size was found to be increased from 28 nm to 47 nm. The surface morphology of all the samples studied by the Scanning Electron Microscopy there exhibits porous structure of particles throughout the samples. The pellets of the samples are prepared for LPG sensing characteristics. The sensing is carried out at different operating temperatures (200, 225, and 250°C) with the variation of LPG concentrations (0.2, 0.4, and 0.6 vol%). The maximum sensitivity of 55.33% is observed at 250°C operating for the 0.6 vol% LPG. PMID:23864833

  14. The effect of Cu(2+) chelation on the direct photolysis of oxytetracycline: A study assisted by spectroscopy analysis and DFT calculation.

    PubMed

    Jin, Xin; Qiu, Shanshan; Wu, Ke; Jia, Mingyun; Wang, Fang; Gu, Chenggang; Zhang, Aiqian; Jiang, Xin

    2016-07-01

    The extensive usage of OTC and Cu(2+) in livestock and poultry industry caused high residues in natural environment. Co-contamination of OTC and Cu(2+) was a considerable environmental problem in surface waters. In this study, Cu(2+) mediated direct photolysis of OTC was studied. Cu(2+) chelating with OTC was found to greatly inhibit OTC photodegradation. To reveal the chelation mechanism of OTC-Cu complexes, multiple methods including UV-Vis absorption spectra, Infrared (IR) spectra, mass spectroscopy, and density functional theoretical (DFT) modeling were performed. Four OTC-Cu complexes were proposed. Cu(2+) preferably bond to O11O12 site with the binding constants logK = 8.19 and 7.86 for CuHL+ and CuL±, respectively. The second chelating site was suggested to be O2O3 with the binding constants of logK = 4.41 and 4.62 for Cu2HL3+ and Cu2L2+, respectively. The suppressed quantum yield of OTC by Cu2+ chelation was accused for their intra-/inter-molecular electron transfer, by which the energy in activated states was distributed. The occurrence of electron transfer between BCD ring and A ring also from BCD ring to Cu was evidenced by the TD-DFT result only for the OTC-Cu complexes. Besides, the cyclic voltammetry measurement also suggested one OTC-Cu(II)/OTC-Cu(I) redox couple. These results suggested that the persistence of OTC in environmental surface waters will probably be underestimated for neglecting the chelating effect of Cu2+. The photolysis quantum yield of OTC-Cu complexes, as well as the specific molar absorption constants, the equilibrium binding constants of Cu2+ with OTC could contribute to more accurate kinetic models of OTC.

  15. Effects of the substituents in the TpxCu activation of dioxygen: an experimental study.

    PubMed

    Mairena, Miguel A; Urbano, Juan; Carbajo, José; Maraver, J Joaquín; Alvarez, Eleuterio; Díaz-Requejo, M Mar; Pérez, Pedro J

    2007-09-01

    A series of TpxCu(I) complexes (Tpx=homoscorpionate ligand) have been reacted in solution with dioxygen at room temperature. Two different behaviors have been observed: the already described reaction with O2 or the lack of any transformation. The trend has been correlated with the electronic density at the metal center, and that has been evaluated by means of cyclic voltammometry studies as well as by IR studies with the TpxCu(CO) complexes. The data collected indicate that the former could serve as a better tool to predict such transformation, establishing a limit above which the complexes are stable under oxygen in solution. Catalytic tests carried out under oxygen have demonstrated that the use of an inert atmosphere is not a requirement in some cases.

  16. Estrogen receptor 1 (ESR1; ERα), not ESR2 (ERβ), modulates estrogen-induced sex reversal in the American alligator, a species with temperature-dependent sex determination.

    PubMed

    Kohno, Satomi; Bernhard, Melissa C; Katsu, Yoshinao; Zhu, Jianguo; Bryan, Teresa A; Doheny, Brenna M; Iguchi, Taisen; Guillette, Louis J

    2015-05-01

    All crocodilians and many turtles exhibit temperature-dependent sex determination where the temperature of the incubated egg, during a thermo-sensitive period (TSP), determines the sex of the offspring. Estrogens play a critical role in sex determination in crocodilians and turtles, as it likely does in most nonmammalian vertebrates. Indeed, administration of estrogens during the TSP induces male to female sex reversal at a male-producing temperature (MPT). However, it is not clear how estrogens override the influence of temperature during sex determination in these species. Most vertebrates have 2 forms of nuclear estrogen receptor (ESR): ESR1 (ERα) and ESR2 (ERβ). However, there is no direct evidence concerning which ESR is involved in sex determination, because a specific agonist or antagonist for each ESR has not been tested in nonmammalian species. We identified specific pharmaceutical agonists for each ESR using an in vitro transactivation assay employing American alligator ESR1 and ESR2; these were 4,4',4''-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT) and 7-bromo-2-(4-hydroxyphenyl)-1,3-benzoxazol-5-ol (WAY 200070), respectively. Alligator eggs were exposed to PPT or WAY 200070 at a MPT just before the TSP, and their sex was examined at the last stage of embryonic development. Estradiol-17β and PPT, but not WAY 200070, induced sex reversal at a MPT. PPT-exposed embryos exposed to the highest dose (5.0 μg/g egg weight) exhibited enlargement and advanced differentiation of the Müllerian duct. These results indicate that ESR1 is likely the principal ESR involved in sex reversal as well as embryonic Müllerian duct survival and growth in American alligators. PMID:25714813

  17. Polymorphisms in the LPL and CETP Genes and Haplotype in the ESR1 Gene Are Associated with Metabolic Syndrome in Women from Southwestern Mexico.

    PubMed

    Cahua-Pablo, José Ángel; Cruz, Miguel; Méndez-Palacios, Abigail; Antúnez-Ortiz, Diana Lizzete; Vences-Velázquez, Amalia; del Carmen Alarcón-Romero, Luz; Parra, Esteban Juan; Tello-Flores, Vianet Argelia; Leyva-Vázquez, Marco Antonio; Valladares-Salgado, Adán; Pérez-Macedonio, Claudia Paola; Flores-Alfaro, Eugenia

    2015-09-08

    Metabolic syndrome (MetS) is a combination of metabolic disorders associated with an increased risk for cardiovascular disease (CVD). Studies in women reported associations between polymorphisms in ESR1, LPL and CETP genes and MetS. Our aim was to evaluate the association between variants in ESR1, LPL and CETP genes with MetS and its components. Four hundred and eighty women were analyzed, anthropometric features and biochemical profiles were evaluated, and genotyping was performed by real-time PCR. We found an association with elevated glucose levels (odds ratio (OR) = 2.9; p = 0.013) in carrying the AA genotype of rs1884051 in the ESR1 gene compared with the GG genotype, and the CC genotype of rs328 in the LPL gene was associated with MetS compared to the CG or GG genotype (OR = 2.8; p = 0.04). Moreover, the GA genotype of rs708272 in the CETP gene is associated with MetS compared to the GG or AA genotype (OR = 1.8; p = 0.006). In addition the ACTCCG haplotype in the ESR1 gene is associated with a decrease in the risk of MetS (OR = 0.02; p < 0.001). In conclusion, our results show the involvement of the variants of ESR1, LPL and CETP genes in metabolic events related to MetS or some of its features.

  18. Polymorphisms in the LPL and CETP Genes and Haplotype in the ESR1 Gene Are Associated with Metabolic Syndrome in Women from Southwestern Mexico

    PubMed Central

    Cahua-Pablo, José Ángel; Cruz, Miguel; Méndez-Palacios, Abigail; Antúnez-Ortiz, Diana Lizzete; Vences-Velázquez, Amalia; del Carmen Alarcón-Romero, Luz; Parra, Esteban Juan; Tello-Flores, Vianet Argelia; Leyva-Vázquez, Marco Antonio; Valladares-Salgado, Adán; Pérez-Macedonio, Claudia Paola; Flores-Alfaro, Eugenia

    2015-01-01

    Metabolic syndrome (MetS) is a combination of metabolic disorders associated with an increased risk for cardiovascular disease (CVD). Studies in women reported associations between polymorphisms in ESR1, LPL and CETP genes and MetS. Our aim was to evaluate the association between variants in ESR1, LPL and CETP genes with MetS and its components. Four hundred and eighty women were analyzed, anthropometric features and biochemical profiles were evaluated, and genotyping was performed by real-time PCR. We found an association with elevated glucose levels (odds ratio (OR) = 2.9; p = 0.013) in carrying the AA genotype of rs1884051 in the ESR1 gene compared with the GG genotype, and the CC genotype of rs328 in the LPL gene was associated with MetS compared to the CG or GG genotype (OR = 2.8; p = 0.04). Moreover, the GA genotype of rs708272 in the CETP gene is associated with MetS compared to the GG or AA genotype (OR = 1.8; p = 0.006). In addition the ACTCCG haplotype in the ESR1 gene is associated with a decrease in the risk of MetS (OR = 0.02; p < 0.001). In conclusion, our results show the involvement of the variants of ESR1, LPL and CETP genes in metabolic events related to MetS or some of its features. PMID:26370976

  19. The guanine cation radical: investigation of deprotonation states by ESR and DFT.

    PubMed

    Adhikary, Amitava; Kumar, Anil; Becker, David; Sevilla, Michael D

    2006-11-30

    This work reports ESR studies that identify the favored site of deprotonation of the guanine cation radical (G*+) in an aqueous medium at 77 K. Using ESR and UV-visible spectroscopy, one-electron oxidized guanine is investigated in frozen aqueous D2O solutions of 2'-deoxyguanosine (dGuo) at low temperatures at various pHs at which the guanine cation radical, G*+ (pH 3-5), singly deprotonated species, G(-H)* (pH 7-9), and doubly deprotonated species, G(-2H)*- (pH > 11), are found. C-8-deuteration of dGuo to give 8-D-dGuo removes the major proton hyperfine coupling at C-8. This isolates the anisotropic nitrogen couplings for each of the three species and aids our analyses. These anisotropic nitrogen couplings were assigned to specific nitrogen sites by use of 15N-substituted derivatives at N1, N2, and N3 atoms in dGuo. Both ESR and UV-visible spectra are reported for each of the species: G*+, G(-H)*, and G(-2H)*-. The experimental anisotropic ESR hyperfine couplings are compared to those obtained from DFT calculations for the various tautomers of G(-H)*. Using the B3LYP/6-31G(d) method, the geometries and energies of G*+ and its singly deprotonated state in its two tautomeric forms, G(N1-H)* and G(N2-H)*, were investigated. In a nonhydrated state, G(N2-H)* is found to be more stable than G(N1-H)*, but on hydration with seven water molecules G(N1-H)* is found to be more stable than G(N2-H)*. The theoretically calculated hyperfine coupling constants (HFCCs) of G*+, G(N1-H)*, and G(-2H)*- match the experimentally observed HFCCs best on hydration with seven or more waters. For G(-2H)*-, the hyperfine coupling constant (HFCC) at the exocyclic nitrogen atom (N2) is especially sensitive to the number of hydrating water molecules; good agreement with experiment is not obtained until nine or 10 waters of hydration are included.

  20. The Guanine Cation Radical: Investigation of Deprotonation States by ESR and DFT

    PubMed Central

    Adhikary, Amitava; Kumar, Anil; Becker, David; Sevilla, Michael D.

    2008-01-01

    This work reports ESR studies that identify the favored site of deprotonation of the guanine cation radical (G•+) in an aqueous medium at 77 K. Using ESR and UV-visible spectroscopy, one-electron oxidized guanine is investigated in frozen aqueous D2O solutions of 2′-deoxyguanosine (dGuo) at low temperatures at various pHs at which the guanine cation, G•+ (pH 3–5), singly deprotonated species, G(-H)• (pH 7–9) and doubly deprotonated species, G(-2H)•− (pH>11) are found. C-8-deuteration of dGuo to give 8-D-dGuo removes the major proton hyperfine coupling at C-8. This isolates the anisotropic nitrogen couplings for each of the three species and aids our analyses. These anisotropic nitrogen couplings were assigned to specific nitrogen sites by use of 15N substituted derivatives at N1, N2 N3 atoms in dGuo. Both ESR and UV-visible spectra are reported for each of the species: G•+, G(-H)•, and G(-2H)•−. The experimental anisotropic ESR hyperfine couplings are compared to those obtained from DFT calculations for the various tautomers of G(-H)•. Using the B3LYP/6–31G(d) method, the geometries and energies of G•+ and its singly deprotonated state in its two tautomeric forms, G(N1-H)• and G(N2-H)•, were investigated. In a non-hydrated state G(N2-H)• is found to be more stable than G(N1-H)• but on hydration with 7 water molecules G(N1-H)• is found to be more stable than G(N2-H)•. The theoretically calculated hyperfine coupling constants (HFCC) of G•+, G(N1-H)• and G(-2H)•− match the experimentally observed HFCCs best on hydration with 7 or more waters. For G(-2H)•−, the hyperfine coupling constant (HFCC) at the exocyclic nitrogen atom (N2) is especially sensitive to the number of hydrating water molecules; good agreement with experiment is not obtained until 9 or 10 waters of hydration are included. PMID:17125389

  1. Theoretical study of band gap in CuAlO2: Pressure dependence and self-interaction correction

    NASA Astrophysics Data System (ADS)

    Nakanishi, Akitaka; Katayama-Yoshida, Hiroshi

    2012-08-01

    By using first-principles calculations, we studied the energy gaps of delafossite CuAlO2: (1) pressure dependence and (2) self-interaction correction (SIC). Our simulation shows that CuAlO2 transforms from a delafossite structure to a leaning delafossite structure at 60 GPa. The energy gap of CuAlO2 increases through the structural transition due to the enhanced covalency of Cu 3d and O 2p states. We implemented a self-interaction correction (SIC) into first-principles calculation code to go beyond local density approximation and applied it to CuAlO2. The energy gap calculated within the SIC is close to experimental data while one calculated without the SIC is about 1 eV smaller than the experimental data.

  2. Theoretical studies on non-volatile holographic recording for LiNbO3:Cu:Ce crystal

    NASA Astrophysics Data System (ADS)

    Yan, Shen; Guo-Qing, Zhang; Wen-Bin, Yu; Zhi-Zhong, Guo

    2014-03-01

    We have conducted a theoretical study of steady-state, non-volatile, two-step, two-colour holographic recording performance of LiNbO3:Cu:Ce on the basis of the two-centre model (the deep-trap and shallow-trap centres are Cu+/Cu2+ and Ce3+/Ce4+, respectively). The results show that direct electron exchange between the Cu+/Cu2+ and Ce3+/Ce4+ centres due to the tunnelling effect dominates the charge transfer process during non-volatile, two-step, two-colour holography and determines the two-step, two-colour holography performance in LiNbO3:Cu:Ce. We have further compared the performance of the two-step, two-colour holography in LiNbO3:Cu:Ce with that of near-stoichiometric LiNbO3:Fe. It is shown that, in terms of the total space charge field, the non-volatile two-step, two-colour holography performance of near-stoichiometric LiNbO3:Fe is much better than that of LiNbO3:Cu:Ce within the intensity range reachable by continuous-wave lasers.

  3. A comparative study on shock compression of nanocrystalline Al and Cu: Shock profiles and microscopic views of plasticity

    SciTech Connect

    Ma, Wen; Hou, Yong; Zhu, Wenjun

    2013-10-28

    Shock compressions of nanocrystalline (nc) metals Al and Cu with the same grain size and texture are studied by using molecular dynamics simulations. Results have revealed that the shock front of both Al and Cu can be divided into three stages: elastic, grain-boundary-mediated, and dislocation-mediated plastic deformation. The transition planes among these three stages are proven to be non-planar by two-dimensional shock response analysis, including local stress, shear, temperature, and atom configuration. The difference between shocked Al and Cu is that the rise rate of the elastic stage of Cu is slightly higher than that of Al, and that the shock-front width of Al is wider than Cu at the same loading conditions. For the plastic stage, the dislocation density of shocked Al is lower than Cu, and the contribution of grain-boundary-mediated plasticity to shock front and strain for nc Al is more pronounced than for nc Cu. These results are explained through intrinsic material properties and atomistic analysis of the plastic process. In the case of the shocked Al sample, partial dislocations, perfect dislocations, and twins are observed, but few evidence of perfect dislocations and twins are observed in the shocked Cu.

  4. Electrochemical and spectroscopic study of novel Cu and Fe-based catalysts for oxygen reduction in alkaline media

    NASA Astrophysics Data System (ADS)

    He, Qinggang; Yang, Xiaofang; He, Ruihua; Bueno-López, Agustín; Miller, Hamish; Ren, Xiaoming; Yang, Wanli; Koel, Bruce E.

    2012-09-01

    We synthesized two “single-core” Fe-Nx/C and Cu-Nx/C electrocatalysts and a bi-core CuFe-Nx/C composite electrocatalyst using iron and copper phthalocyanine-based precursors and a high-temperature pyrolysis method. The morphology, structure, and activity toward the oxygen reduction reaction (ORR) in alkaline media were evaluated for each electrocatalyst by transmission electron microscopy (TEM), X-ray Diffraction (XRD), and the rotating ring-disk electrode (RRDE) method. Although the Cu-Nx/C catalyst showed lower catalytic activity than Fe-Nx/C, the presence of Cu enhanced the ORR performance of bi-core CuFe-Nx/C, as compared to single-core Fe-Nx/C. To fully understand the synergistic effect between Cu and Fe on this enhancement, high resolution X-ray photoelectron spectroscopy (HR-XPS) and soft X-ray absorption spectroscopy (XAS) was employed to study the electronic structure of as-synthesized electrocatalysts. The HR-XPS analysis showed that metal-nitrogen bonding was maintained and that the oxidation states of Fe and Cu were influenced by the presence of the second metal in the bi-core catalyst. The XAS data revealed that a fraction of an electron was transferred from Fe to Cu, which may help to lower the kinetic barrier during the ORR process. Based on our experimental results and four different models, we briefly discuss ORR mechanisms on these metallic catalysts.

  5. Study of Cu-related Defect States in Single-crystal CdTe

    NASA Astrophysics Data System (ADS)

    Corwine, Caroline; Sites, James; Gessert, Timothy; Metzger, Wyatt; Dippo, Pat; Duda, Anna

    2003-10-01

    We have studied single-crystal CdTe using low-temperature photoluminescence (PL) in an effort to understand the effects of copper on the deep levels, as well as the effect of a bromine methanol (BrMe) etch on subsequent copper diffusion into CdTe. In present polycrystalline CdS/CdTe solar cell technology, the use of a back contact that contains Cu is necessary to produce high-efficiency cells. However, it is not generally understood why Cu is necessary for these devices to function well. In order to obtain further advances in the efficiencies of these solar cells, it is important to know how the back contact process may affect the defect states in CdTe. PL is one tool used to study defect states. However, before PL can be used effectively for polycrystalline CdTe solar cells, relevant spectral features first must be interpreted for single-crystal CdTe. All PL in this study was taken at 4.5 K. We report on PL peaks at 1.40 and 1.45 eV, which are seen only after Cu is diffused into single-crystal CdTe.

  6. Binding of Cu(II) ions to peptides studied by fluorescence spectroscopy and isothermal titration calorimetry

    NASA Astrophysics Data System (ADS)

    Makowska, Joanna; Żamojć, Krzysztof; Wyrzykowski, Dariusz; Uber, Dorota; Wierzbicka, Małgorzata; Wiczk, Wiesław; Chmurzyński, Lech

    2016-01-01

    Steady-state and time-resolved fluorescence quenching measurements supported by Isothermal Titration Calorimetry (ITC) were used to study the interactions of Cu2 + with four peptides. Two of them were taken from the N-terminal part of the FBP28 protein (formin binding protein) WW domain: Tyr-Lys-Thr-Ala-Asp-Gly-Lys-Thr-Tyr-NH2 (D9) and its mutant Tyr-Lys-Thr-Ala-Asn-Gly-Lys-Thr-Tyr-NH2 (D9_M) as well as two mutated peptides from the B3 domain of the immunoglobulin binding protein G derived from Streptococcus: Asp-Val-Ala-Thr-Tyr-Thr-NH2 (J1) and Glu-Val-Ala-Thr-Tyr-Thr-NH2 (J2). The measurements were carried out at 298.15 K in 20 mM 2-(N-morpholino)ethanesulfonic acid (MES) buffer solution with a pH of 6. The fluorescence of all peptides was quenched by Cu2 + ions. The stoichiometry, conditional stability constants and thermodynamic parameters for the interactions of the Cu2 + ions with D9 and D9_M were determined from the calorimetric data. The values of the conditional stability constants were additionally determined from fluorescence quenching measurements and compared with those obtained from calorimetric studies. There was a good correlation between data obtained from the two techniques. On the other hand, the studies revealed that J1 and J2 do not exhibit an affinity towards metal ions. The obtained results prove that fluorescence quenching experiments may be successfully used in order to determine stability constants of complexes with fluorescent ligands. Finally, based on the obtained results, the coordinating properties of the peptides towards the Cu2 + ions are discussed.

  7. Binding of Cu(II) ions to peptides studied by fluorescence spectroscopy and isothermal titration calorimetry.

    PubMed

    Makowska, Joanna; Żamojć, Krzysztof; Wyrzykowski, Dariusz; Uber, Dorota; Wierzbicka, Małgorzata; Wiczk, Wiesław; Chmurzyński, Lech

    2016-01-15

    Steady-state and time-resolved fluorescence quenching measurements supported by Isothermal Titration Calorimetry (ITC) were used to study the interactions of Cu(2+) with four peptides. Two of them were taken from the N-terminal part of the FBP28 protein (formin binding protein) WW domain: Tyr-Lys-Thr-Ala-Asp-Gly-Lys-Thr-Tyr-NH2 (D9) and its mutant Tyr-Lys-Thr-Ala-Asn-Gly-Lys-Thr-Tyr-NH2 (D9_M) as well as two mutated peptides from the B3 domain of the immunoglobulin binding protein G derived from Streptococcus: Asp-Val-Ala-Thr-Tyr-Thr-NH2 (J1) and Glu-Val-Ala-Thr-Tyr-Thr-NH2 (J2). The measurements were carried out at 298.15K in 20mM 2-(N-morpholino)ethanesulfonic acid (MES) buffer solution with a pH of 6. The fluorescence of all peptides was quenched by Cu(2+) ions. The stoichiometry, conditional stability constants and thermodynamic parameters for the interactions of the Cu(2+) ions with D9 and D9_M were determined from the calorimetric data. The values of the conditional stability constants were additionally determined from fluorescence quenching measurements and compared with those obtained from calorimetric studies. There was a good correlation between data obtained from the two techniques. On the other hand, the studies revealed that J1 and J2 do not exhibit an affinity towards metal ions. The obtained results prove that fluorescence quenching experiments may be successfully used in order to determine stability constants of complexes with fluorescent ligands. Finally, based on the obtained results, the coordinating properties of the peptides towards the Cu(2+) ions are discussed.

  8. Binding of Cu(II) ions to peptides studied by fluorescence spectroscopy and isothermal titration calorimetry.

    PubMed

    Makowska, Joanna; Żamojć, Krzysztof; Wyrzykowski, Dariusz; Uber, Dorota; Wierzbicka, Małgorzata; Wiczk, Wiesław; Chmurzyński, Lech

    2016-01-15

    Steady-state and time-resolved fluorescence quenching measurements supported by Isothermal Titration Calorimetry (ITC) were used to study the interactions of Cu(2+) with four peptides. Two of them were taken from the N-terminal part of the FBP28 protein (formin binding protein) WW domain: Tyr-Lys-Thr-Ala-Asp-Gly-Lys-Thr-Tyr-NH2 (D9) and its mutant Tyr-Lys-Thr-Ala-Asn-Gly-Lys-Thr-Tyr-NH2 (D9_M) as well as two mutated peptides from the B3 domain of the immunoglobulin binding protein G derived from Streptococcus: Asp-Val-Ala-Thr-Tyr-Thr-NH2 (J1) and Glu-Val-Ala-Thr-Tyr-Thr-NH2 (J2). The measurements were carried out at 298.15K in 20mM 2-(N-morpholino)ethanesulfonic acid (MES) buffer solution with a pH of 6. The fluorescence of all peptides was quenched by Cu(2+) ions. The stoichiometry, conditional stability constants and thermodynamic parameters for the interactions of the Cu(2+) ions with D9 and D9_M were determined from the calorimetric data. The values of the conditional stability constants were additionally determined from fluorescence quenching measurements and compared with those obtained from calorimetric studies. There was a good correlation between data obtained from the two techniques. On the other hand, the studies revealed that J1 and J2 do not exhibit an affinity towards metal ions. The obtained results prove that fluorescence quenching experiments may be successfully used in order to determine stability constants of complexes with fluorescent ligands. Finally, based on the obtained results, the coordinating properties of the peptides towards the Cu(2+) ions are discussed. PMID:26363471

  9. ELECTRON SPIN RESONANCE STUDIES ON MELANIN.

    PubMed

    BLOIS, M S; ZAHLAN, A B; MALING, J E

    1964-11-01

    Electron spin resonance (e.s.r.) observations of squid melanin have been conducted over the temperature range 500 degrees K to 4.2 degrees K, and the effect of various chemical treatments of the melanin upon the e.s.r. spectrum has been studied. The findings have shown that the paramagnetism of this melanin follows the Curie Law from 500 degrees K to 4.2 degrees K, that the spin signal can be eliminated by the addition of Cu(++) to the melanin, and that the optical and e.s.r. absorptions of melanin are independent since either can be reduced or eliminated without affecting the other. Similar studies on synthetic melanins produced by autoxidation or by enzymatic oxidation of a number of biphenols were carried out. It was found that the e.s.r. signals of these synthetic melanins were strikingly similar (with respect to line width, line shape, and g-value) with those of squid melanin. It is concluded that the unpaired electrons observed are associated with trapped free radicals in the melanin polymer, that the biosynthesis of melanin may involve a free radical mechanism, and that these physical data are in accord with the concept of Nicolaus that melanin is a highly irregular, three-dimensional, polymer. PMID:14232133

  10. [Study on Contents and Budgets of Cu, Zn and Cd in an Arable Soil Using AAS].

    PubMed

    Zhao, Ying; Jiang, Chun-ming; Ma, Qiang; Zhou, Hua; Xu, Yong-gang; Yu, Wan-tai

    2015-12-01

    Based on a long-term experiment in Shenyang Experimental Station, the effect of manure application on the contents and budgets of Cu, Zn and Cd in the arable soil was studied. The experiment included four treatments: no mature addition (CK), mature addition 10 t · ha⁻¹ year⁻¹(M1), 25 t · ha⁻¹ year⁻¹ (M2), and 50 t · ha⁻¹ year⁻¹(M3). The result showed that Cu, Zn and Cd in soil were accumulated with manure application and prolongation of experiment, and the accumulative magnitude increased with increasing of manure application. The average annual growth rates of the heavy metals in the four treatments (CK, M1, M2, M3) were 2.83%, 6.56%, 7.54%, 8.96%; 0.03%, 3.44%, 4.53%, 6.64% and 1.51%, 8.01%, 10. 27%, 16. 08% for Cu, Zn and Cd, respectively. After six years of the experiment, the content of Cd in the M3 treatment was quite close to the threshold of Chinese Soil Quality Standard Grade III (1 mg · kg⁻¹, GB15618-1995). After 12 years of the experiment, the contents of Cu in the mature-amended treatments fell in the Chinese Soil Quality Standard Grade III, which should be paid more attention. Although the heavy metals in soil were gradually accumulated, the Cu, Zn and Cd levels in crop grain were still below the National Food Contamination Standards (GB2762-2005; GB13106-91; GB15199-94), indicating the contents of heavy metals in crop produced from contaminated soil might not exceed the corresponding standards. The contents of Cu, Zn and Cd in the straw were much greater than those in the grain. The removal of heavy metal by crop was in the order of M3 > M2 > M1 > CK. The average amounts of Cu, Zn and Cd annually removed from the soil in the four treatments (CK, M1, M2 and M3) were 35.68, 47.80, 63.65, 69.64; 249.14, 375.22, 375.16, 444.44, and 0.83, 1.39, 1.64, 1.66 g · ha⁻¹, respectively. The contents of heavy metals in organic manure varied in different years: the contents of Cu and Zn increased year by year, while Cd presented a

  11. Characterization and biological studies on Co(II), Ni(II) and Cu(II) complexes of carbohydrazones ending by pyridyl ring

    NASA Astrophysics Data System (ADS)

    Abu El-Reash, G. M.; El-Gammal, O. A.; Ghazy, S. E.; Radwan, A. H.

    2013-03-01

    The chelating behavior of ligands based on carbohydrazone core modified with pyridine end towards Co(II), Ni(II) and Cu(II) ions have been examined. The ligands derived from the condensation of carbohydrazide with 2-acetylpyridine (H2APC) and 4-acetylpyridine (H2APEC). The 1H NMR, IR data and the binding energy calculations of H2APC revealed the presence of two stereoisomers syn and anti in the solid state and in the solution. The 1H NMR, IR data and the binding energy calculations confirmed the presence of H2APEC in one keto form only in the solid state and in the solution. The spectroscopic data confirmed that H2APC behaves as a monobasic pentadentate in Co(II) and Cu(II) complexes and as mononegative tetradentate in Ni(II) complex. On the other hand, H2APEC acts as a mononegative tridentate in Co(II) complex, neutral tridentate in Ni(II) complex and neutral bidentate in Cu(II) complex. The electronic spectra and the magnetic measurements of complexes as well as the ESR of the copper complexes suggested the octahedral geometry. The bond length and bond angles were evaluated by DFT method using material studio program. The thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. The antioxidant (DDPH and ABTS methods), anti-hemolytic and in vitro Ehrlich ascites of the compounds have been screened.

  12. Supercritical hydrothermal synthesis of Cu{sub 2}O(SeO{sub 3}): Structural characterization, thermal, spectroscopic and magnetic studies

    SciTech Connect

    Larranaga, Aitor

    2009-01-08

    Cu{sub 2}O(SeO{sub 3}) has been synthesized in supercritical hydrothermal conditions, using an externally heated steel reactor with coupled hydraulic pump for the application of high pressure. The compound crystallizes in the P2{sub 1}3 cubic space group. The unit cell parameter is a = 9.930(1) A with Z = 12. The crystal structure has been refined by the Rietveld method. The limit of thermal stability is, approximately, 490 deg. C. Above this temperature the compound decomposes to SeO{sub 2}(g) and CuO(s). The IR spectrum shows the characteristic bands of the (SeO{sub 3}){sup 2-} oxoanion. In the diffuse reflectance spectrum two intense absorptions characteristic of the Cu(II) cations in five-coordination are observed. The ESR spectra are isotropic from room temperature to 5 K, with g = 2.11(2). The thermal evolution of the intensity and line width of the signals suggest a ferromagnetic transition in the 50-45 K range. Magnetic measurements, at low temperatures, confirm the existence of a ferromagnetic transition with a critical temperature of 55 K.

  13. Study of structural and optical properties of Fe doped CuO nanoparticles

    NASA Astrophysics Data System (ADS)

    Rani, Poonam; Gupta, Ankita; Kaur, Sarabjeet; Singh, Vishal; Kumar, Sacheen; Kumar, Dinesh

    2016-05-01

    Iron doped Copper oxide nanoparticles were synthesized by the co-precipitation method at different concentration (3%, 6%, 9%) at 300-400° C with Copper Acetate and Ferric Chloride as precursors in presence of Polyethylene Glycol and Sodium Hydroxide as stabilizing agent. Effect of doping on the structural and optical properties is studied. The obtained nanoparticles were characterized by X-Ray Diffraction and UV-Visible Spectroscopy for examining the size and the band gap respectively. The X-Ray Diffraction plots confirmed the monoclinic structure of Copper oxide suggesting the Cu atoms replaced by Fe atoms and no secondary phase was detected. The indirect band gap of Fe doped CuO nanoparticles is 2.4eV and increases to 3.4eV as the concentration of dopant increases. The majority of particle size is in range 8 nm to 35.55 nm investigated by X-ray diffractometer.

  14. Diffusion of anthracene derivatives on Cu(111) studied by STM and DFT

    NASA Astrophysics Data System (ADS)

    Wyrick, Jonathan; Bartels, Ludwig; Einstein, Theodore

    2014-03-01

    Substituted anthracenes have drawn attention due to their ability to diffuse uniaxially on a Cu(111) surface. We compare anthracene to three of its derivatives whose 9,10 hydrogens are replaced by elements of the chalcogen group that act as linkers binding the molecules to a Cu(111) substrate. DFT calculations shed light on STM imaging and diffusion studies on the three substituted species. We present an analysis of the DFT results in which energetic contributions to the diffusion barriers are partitioned among the Kohn-Sham orbitals, allowing us to make assignments as to how each orbital affects diffusion for each species and draw comparisons between them. Present address: Center for Nanoscale Science and Technology, NIST, Gaithersburg, MD.

  15. Ab initio study of heterojunction discontinuities in the ZnO/Cu2O system

    NASA Astrophysics Data System (ADS)

    Zemzemi, M.; Alaya, S.; Ben Ayadi, Z.

    2014-06-01

    Solar cells based on transparent conductive oxides such as ZnO/Cu2O constitute a very advanced way to build high-performance cells. In this work, we are interested in the characterization of the interface through nanoscale modeling based on ab initio approaches (density functional theory, local density approximation, and pseudopotential). This work aims to build a supercell containing a heterojunction ZnO/Cu2O and study the structural properties and the discontinuity of the valence band (band offset) from a semiconducting to another phase. We build a zinc oxide in the wurtzite structure along [0001] on which we place the copper oxide in the hexagonal (CdI2-type) structure. We choose the method of Van de Walle and Martin to calculate the energy offset. This approach fits well the density functional theory. Our calculation of the band offset gives a value that corresponds to other experimental and theoretical values.

  16. -decay studies of the transitional nucleus 75Cu and the structure of 75Zn

    SciTech Connect

    Ilyushkin, S.; Winger, J. A.; Rykaczewski, Krzysztof Piotr; Gross, Carl J; Batchelder, J. C.; Cartegni, L.; Darby, Iain; Grzywacz, Robert Kazimierz; Hamilton, J. H.; Korgul, A.; Krolas, W.; Liddick, Sean; Mazzocchi, C.; Mendez, T; Padgett, Stephen; Rajabali, M. M.; Shapira, Dan; Stracener, Dan; Zganjar, E. F.

    2011-01-01

    The decay of 75Cu [t1/2 = 1.222(8) s] to levels in 75Zn was studied at the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory. The and data were collected at the Low-energy Radioactive Ion Beam Spectroscopy Station using the high-resolution isobar separator to obtain a purified 75Cu beam with a rate of over 2000 ions per second. The excited states in 75Zn have been identified for the first time. A total of 120 -ray transitions were placed in a level scheme containing 59 levels including two states above the neutron separation energy and a previously unknown 1/2 isomeric state at 127 keV. Spins and parities of several states were deduced and interpreted based on the observed feeding and -decay pattern.

  17. Association of ESR1 gene tagging SNPs with breast cancer risk

    PubMed Central

    Dunning, Alison M.; Healey, Catherine S.; Baynes, Caroline; Maia, Ana-Teresa; Scollen, Serena; Vega, Ana; Rodríguez, Raquel; Barbosa-Morais, Nuno L.; Ponder, Bruce A.J.; Low, Yen-Ling; Bingham, Sheila; Haiman, Christopher A.; Le Marchand, Loic; Broeks, Annegien; Schmidt, Marjanka K.; Hopper, John; Southey, Melissa; Beckmann, Matthias W.; Fasching, Peter A.; Peto, Julian; Johnson, Nichola; Bojesen, Stig E.; Nordestgaard, Børge; Milne, Roger L.; Benitez, Javier; Hamann, Ute; Ko, Yon; Schmutzler, Rita K.; Burwinkel, Barbara; Schürmann, Peter; Dörk, Thilo; Heikkinen, Tuomas; Nevanlinna, Heli; Lindblom, Annika; Margolin, Sara; Mannermaa, Arto; Kosma, Veli-Matti; Chen, Xiaoqing; Spurdle, Amanda; Change-Claude, Jenny; Flesch-Janys, Dieter; Couch, Fergus J.; Olson, Janet E.; Severi, Gianluca; Baglietto, Laura; Børresen-Dale, Anne-Lise; Kristensen, Vessela; Hunter, David J.; Hankinson, Susan E.; Devilee, Peter; Vreeswijk, Maaike; Lissowska, Jolanta; Brinton, Louise; Liu, Jianjun; Hall, Per; Kang, Daehee; Yoo, Keun-Young; Shen, Chen-Yang; Yu, Jyh-Cherng; Anton-Culver, Hoda; Ziogoas, Argyrios; Sigurdson, Alice; Struewing, Jeff; Easton, Douglas F.; Garcia-Closas, Montserrat; Humphreys, Manjeet K.; Morrison, Jonathan; Pharoah, Paul D.P.; Pooley, Karen A.; Chenevix-Trench, Georgia

    2009-01-01

    We have conducted a three-stage, comprehensive single nucleotide polymorphism (SNP)-tagging association study of ESR1 gene variants (SNPs) in more than 55 000 breast cancer cases and controls from studies within the Breast Cancer Association Consortium (BCAC). No large risks or highly significant associations were revealed. SNP rs3020314, tagging a region of ESR1 intron 4, is associated with an increase in breast cancer susceptibility with a dominant mode of action in European populations. Carriers of the c-allele have an odds ratio (OR) of 1.05 [95% Confidence Intervals (CI) 1.02–1.09] relative to t-allele homozygotes, P = 0.004. There is significant heterogeneity between studies, P = 0.002. The increased risk appears largely confined to oestrogen receptor-positive tumour risk. The region tagged by SNP rs3020314 contains sequence that is more highly conserved across mammalian species than the rest of intron 4, and it may subtly alter the ratio of two mRNA splice forms. PMID:19126777

  18. Comparative Density Functional Study of Methanol Decomposition on Cu4 and Co4 Clusters

    SciTech Connect

    Mehmood, Faisal; Greeley, Jeffrey P.; Zapol, Peter; Curtiss, Larry A.

    2010-11-18

    A density functional theory study of the decomposition of methanol on Cu4 and Co4 clusters is presented. The reaction intermediates and activation barriers have been determined for reaction steps to form H2 and CO. For both clusters, methanol decomposition initiated by C-H and O-H bond breaking was investigated. In the case of a Cu4 cluster, methanol dehydrogenation through hydroxymethyl (CH2OH), hydroxymethylene (CHOH), formyl (CHO), and carbon monoxide (CO) is found to be slightly more favorable. For a Co4 cluster, the dehydrogenation pathway through methoxy (CH3O) and formaldehyde (CH2O) is slightly more favorable. Each of these pathways results in formation of CO and H2. The Co cluster pathway is very favorable thermodynamically and kinetically for dehydrogenation. However, since CO binds strongly, it is likely to poison methanol decomposition to H2 and CO at low temperatures. In contrast, for the Cu cluster, CO poisoning is not likely to be a problem since it does not bind strongly, but the dehydrogenation steps are not energetically favorable. Pathways involving C-O bond cleavage are even less energetically favorable. The results are compared to our previous study of methanol decomposition on Pd4 and Pd8 clusters. Finally, all reaction energy changes and transition state energies, including those for the Pd clusters, are related in a linear, Broensted-Evans-Polanyi plot.

  19. ESR Microscopy for Biological and Biomedical Applications.

    PubMed

    Shin, C S; Dunnam, C R; Borbat, P P; Dzikovski, B; Barth, E D; Halpern, H J; Freed, J H

    2011-08-01

    We report on electron-spin resonance microscopy (ESRM) providing sub-micron resolution (~700nm) with a high spin concentration sample, i.e. lithium phthalocyanine (LiPc) crystal. For biomedical applications of our ESRM, we have imaged samples containing rat basophilic leukemia (RBL) cells as well as cancerous tissue samples with a resolution of several microns using a water soluble spin probe, Trityl_OX063_d24. Phantom samples with the nitroxide spin label, (15)N PDT, were also imaged to demonstrate that nitroxides, which are commonly used as spin labels, may also be used for ESRM applications. ESRM tissue imaging would therefore be valuable for diagnostic or therapeutic purposes. Also, ESRM can be used to study the motility or the metabolism of cells in various environments. With further modification and/or improvement of imaging probe and spectrometer instrumentation sub-micron biological images should be obtainable, thereby providing a useful tool for various biomedical applications.

  20. A high temperature diffraction-resistance study of chalcopyrite, CuFeS{sub 2}

    SciTech Connect

    Engin, T.E.; Powell, A.V.; Hull, S.

    2011-08-15

    The electrical, magnetic and structural properties of synthetic chalcopyrite, CuFeS{sub 2}, have been studied up to 873 K using DC resistance measurements performed in-situ during neutron powder diffraction experiments. Under ambient conditions the material adopts the accepted structural model for CuFeS{sub 2} in the space group I4-bar 2d, with the magnetic moment of the Fe{sup 3+} cations aligned along [001]. The electrical resistivity is around 0.3 {Omega} cm under ambient conditions, consistent with semiconductor character, and decreases slightly with increase in temperature until a more abrupt fall occurs in the region 750-800 K. This abrupt change in resistivity is accompanied by a structural transition to a cubic zinc blende structured phase (space group F4-bar 3m) in which Cu{sup +} and Fe{sup 3+} cations are disordered over the same tetrahedral crystallographic sites and by a simultaneous loss of long-range magnetic order. The implications of these results are discussed in the context of previous studies of the chalcopyrite system. - Graphical abstract: Structural, magnetic and electrical properties of CuFeS{sub 2} to 873 K have been investigated using DC resistance measurements, performed in-situ during the collection of powder neutron diffraction data. Highlights: > Structural, magnetic and electronic properties are probed simultaneously. > A fall in resistivity at high temperatures is associated with cation disorder. > The order-disorder transition is accompanied by the loss of magnetic order. > The structural and magnetic phase transition is preceded by a 2-phase region. > Sulphur loss at high temperatures causes the phase transitions to be irreversible.

  1. Development of an ESR/MR dual-imaging system as a tool to detect bioradicals.

    PubMed

    Fujii, Hirotada; Aoki, Masaaki; Haishi, Tomoyuki; Itoh, Kouichi; Sakata, Motomichi

    2006-04-01

    A system combining electron spin resonance imaging (ESRI) with another imaging modality capable of enabling visualization of the distribution of bioradicals on an anatomical map of the specimens would be a superior biomedical imaging system. We describe the development of an ESR/MR dual-imaging system with one permanent magnet and the biomedical applications of this system. The magnetic circuit developed for the ESR/MR dual-imaging system consisted of the permanent magnet made of Fe-Nd-B, pole pieces, and poke. The permanent magnet was installed on the MR side only, and the ESR side was made of pole pieces only. The magnetic field was adjusted to 0.5T at MR and to 0.042T at ESR. The overall dimensions of the magnet developed for the ESR/MR imaging system were 460 (W)x440 (D)x460 (H) mm, and it weighed 220 kg. The distance of each center for the magnet for ESR and MR imaging could be set as close as 200 mm. The entire ESR/MR imaging system can be installed in a common laboratory without magnetic shielding. MR images of plants (myoga) and small animals (mice and rats) were successfully acquired with or without ESR operation. ESR spectra of nitroxyl spin probes were also measured, even with MRI operation. ESR signals of triarylmethyl derivatives with narrow line-width (0.026 mT) were observed in living mice while MRI was operating. The ESR/MR imaging dual functions work properly with no electric or magnetic interference. The ESR/MR dual images demonstrate that this system enables visualization of the distribution of bioradicals on the anatomical map of the object.

  2. Glass forming abilities of binary Cu100-xZrx (34, 35.5, and 38.2 at. %) metallic glasses: A LAMMPS study

    NASA Astrophysics Data System (ADS)

    Sha, Z. D.; Wu, R. Q.; Lu, Y. H.; Shen, L.; Yang, M.; Cai, Y. Q.; Feng, Y. P.; Li, Y.

    2009-02-01

    Using large-scale atomic/molecular massively parallel simulator (LAMMPS), we have studied the liquid behaviors of Cu61.8Zr38.2, Cu64.5Zr35.5, and Cu66Zr34 amorphous alloys including their pair distribution functions, distributions of Voronoi clusters with different coordination numbers, and mean square displacements of Cu and Zr atoms. Compared to Cu61.8Zr38.2 and Cu66Zr34, we found high concentrations of distorted icosahedra with indices of ⟨0,2,8,2⟩ and ⟨0,4,4,4⟩, high numbers of Cu-centered Cu8Zr5 and Cu9Zr4 clusters, and reduced atomic diffusivity of Cu and Zr atoms in molten Cu64.5Zr35.5 alloy. These effects would benefit glass formation in Cu64.5Zr35.5 alloy. Meanwhile, from the viewpoints of local cluster structure, the majority of the glue atoms are Cu atoms in Cu64.5Zr35.5 amorphous alloy, which leads to denser packing and better glass forming ability.

  3. First-principles study of the organometallic S =1/2 kagome compound Cu(1,3-bdc)

    NASA Astrophysics Data System (ADS)

    Liu, Zheng; Mei, Jia-Wei; Liu, Feng

    2015-10-01

    Cu(1,3-benzenedicarboxylate) [Cu(1,3-bdc)] contains structurally perfect kagome planes formed by Cu2 + ions without the presence of diamagnetic defects. This organometallic compound should serve as a precious platform to explore quantum frustrated magnetism, yet the experimental results so far are mysterious, leading to questions such as, "Is Cu(1,3-bdc) just a trivial weak ferromagnet?" Using the density functional theory, we have systematically studied the electronic and magnetic properties of Cu(1,3-bdc), putting forth a theoretical basis to clarify this novel material. We present numerical evidence of a dominating antiferromagnetic (AFM) exchange between nearest-neighbor (NN) Cu2 + as experimentally extracted from the high-temperature susceptibility data. We further show that beyond the NN AFM exchange, the additional interactions in Cu(1,3-bdc) have similar strength as those in the well-studied kagome antiferromagnet, herbertsmithite, by designing a comparative study. In the end, we discuss our understanding of the phase transition and FM signals observed under low temperature.

  4. Thermodynamic study of CuO/Cu2O and Co3O4/CoO redox pairs for solar energy thermochemical storage

    NASA Astrophysics Data System (ADS)

    Alonso, Elisa; Gallo, Alessandro; Pérez-Rábago, Carlos; Fuentealba, Edward

    2016-05-01

    Thermochemical storage of solar energy consists in reversible chemical reactions that absorb the solar heat during an endothermic step and release it by means of an exothermic reaction. CuO/Cu2O and Co3O4/CoO redox pairs have a high potential as materials to store solar energy at high temperature. Cobalt oxides have been so far studied by several authors and works while copper oxides suitability has been recently proved. However, in both cases, operation parameters need to be optimized. A theoretical study of the effect of total pressure, gas/solid molar rate and composition of working atmosphere on the systems equilibrium is presented. The equilibrium displacement caused by these parameters is calculated and discussed. Finally, some ideas for tentative implementations of these systems are commented.

  5. Structural study and Raman scattering analysis of Cu2ZnSiTe4 bulk crystals.

    PubMed

    Levcenko, Serghei; Nateprov, Alexandr; Kravtsov, Victor; Guc, Maxim; Pérez-Rodríguez, Alejandro; Izquierdo-Roca, Victor; Fontané, Xavier; Arushanov, Ernest

    2014-12-15

    Bulk crystals of Cu(2)ZnSiTe(4) (CZSiTe) have been prepared by modified Bridgman method and have been investigated by single crystal X-ray method, Energy Dispersive X-Ray analysis and Raman scattering techniques. The structural studies revealed that the CZSiTe compounds crystallizes in the tetragonal space group I4¯2m, with a = b = 5.9612(1) Å and c = 11.7887(4) Å at 293 K. The Raman spectrum characteristic of the crystals exhibits nine peaks, with two dominant peaks at approximately 134 cm(-1) and 151 cm(-1) that can be used as fingerprint peaks for the identification of this compound. The Raman peaks were analyzed on the basis of the derived irreducible representation for the zone center phonons and by comparison with experimental and theoretical data from close related semiconductors as Cu(2)FeSnS(4) and Cu(2)ZnSnSe(4). PMID:25607506

  6. EPR study of Cu(2+) ion doped orotato(nicotinamid)cobalt(II) single crystal.

    PubMed

    Yıldırım, I; Karabulut, B; Büyükgüngör, O

    2016-01-01

    We have studied the Cu(2+) ion doped orotato(nicotinamid)cobalt(II) complex by using EPR spectroscopy and X-ray diffraction. The single crystal is triclinic with the space group P1‾. The unit cell dimensions of the crystal are a=7.2785(4)Å, b=10.2349(5)Å, c=12.7372(6)Å, α=69.297(4)°, β=74.791(4)° and γ=76.995(4)°, with Z=2. We analyzed the EPR spectra of both single crystal and powder of the complex at room temperature. EPR analysis indicates the presence of only one Cu(2+) site. We obtained the spin Hamiltonian parameters from the single crystal data for the complex. The spin Hamiltonian parameters are gx=2.032, gy=2.116, gz=2.319, Ax=28G, Ay=66G, Az=126G. These data indicate that the symmetry of paramagnetic center is rhombic. We constructed the ground state wave function of the Cu(2+) ion.

  7. Using enriched stable isotope technique to study Cu bioaccumulation and bioavailability in Corbicula fluminea from Taihu Lake, China.

    PubMed

    Fan, Wenhong; Ren, Jinqian; Wu, Chenguang; Tan, Cheng; Wang, Xiaolong; Cui, Minming; Wu, Kuang; Li, Xiaomin

    2014-12-01

    In this study, we measured trace metals (Cd, Cr, Cu, Ni, Pb, and Zn) in water and sediment from representative sites of Taihu Lake, with focus on the analysis of trace metal accumulation in Corbicula fluminea (bivalve). The results showed that the quality of water in Taihu Lake was generally good and the correlation was not found between Cu bioaccumulation in C. fluminea and the concentration in water and sediment. Thus, using the stable isotope tracer method, we studied Cu uptake from the water phase, the assimilation of Cu from the food phase, and the efflux of Cu in vivo by C. fluminea. The result revealed that this species exhibited a relatively lower efflux rate constant of Cu compared with other zoobenthos species. Using a simple bioenergetics-based kinetic model, Cu concentrations in the C. fluminea were calculated with the measured efflux rate. We put forward a novel method, which was taking the influence of biological kinetic on metal bioaccumulation into account to explain the field survey data.

  8. Electrically-detected ESR in silicon nanostructures inserted in microcavities

    SciTech Connect

    Bagraev, Nikolay; Danilovskii, Eduard; Gets, Dmitrii; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna; Gehlhoff, Wolfgang; Mashkov, Vladimir; Romanov, Vladimir

    2014-02-21

    We present the first findings of the new electrically-detected electron spin resonance technique (EDESR), which reveal the point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ- barriers. This technique allows the ESR identification without application of an external cavity, as well as a high frequency source and recorder, and with measuring the only response of the magnetoresistance, with internal GHz Josephson emission within frameworks of the normal-mode coupling (NMC) caused by the microcavities embedded in the Si-QW plane.

  9. ESR1 gene promoter region methylation in free circulating DNA and its correlation with estrogen receptor protein expression in tumor tissue in breast cancer patients

    PubMed Central

    2014-01-01

    Background Tumor expression of estrogen receptor (ER) is an important marker of prognosis, and is predictive of response to endocrine therapy in breast cancer. Several studies have observed that epigenetic events, such methylation of cytosines and deacetylation of histones, are involved in the complex mechanisms that regulate promoter transcription. However, the exact interplay of these factors in transcription activity is not well understood. In this study, we explored the relationship between ER expression status in tumor tissue samples and the methylation of the 5′ CpG promoter region of the estrogen receptor gene (ESR1) isolated from free circulating DNA (fcDNA) in plasma samples from breast cancer patients. Methods Patients (n = 110) with non-metastatic breast cancer had analyses performed of ER expression (luminal phenotype in tumor tissue, by immunohistochemistry method), and the ESR1-DNA methylation status (fcDNA in plasma, by quantitative methylation specific PCR technique). Results Our results showed a significant association between presence of methylated ESR1 in patients with breast cancer and ER negative status in the tumor tissue (p = 0.0179). There was a trend towards a higher probability of ESR1-methylation in those phenotypes with poor prognosis i.e. 80% of triple negative patients, 60% of HER2 patients, compared to 28% and 5.9% of patients with better prognosis such as luminal A and luminal B, respectively. Conclusion Silencing, by methylation, of the promoter region of the ESR1 affects the expression of the estrogen receptor protein in tumors of breast cancer patients; high methylation of ESR1-DNA is associated with estrogen receptor negative status which, in turn, may be implicated in the patient’s resistance to hormonal treatment in breast cancer. As such, epigenetic markers in plasma may be of interest as new targets for anticancer therapy, especially with respect to endocrine treatment. PMID:24495356

  10. Dirty Superconductivity in the Electron-Doped Cuprate Pr2-xCexCuO4-δ: Tunneling Study

    NASA Astrophysics Data System (ADS)

    Dagan, Y.; Beck, R.; Greene, R. L.

    2007-10-01

    We report a tunneling study between Pr2-xCexCuO4-δ and lead as a function of doping, temperature, and magnetic field. The temperature dependence of the gap follows the BCS prediction. Our data fit a nonmonotonic d-wave order parameter for the whole doping range studied. From our data we are able to conclude that the electron-doped cuprate Pr2-xCexCuO4-δ is a weak-coupling BCS dirty superconductor.

  11. Analysis of anisotropic spin-label motion in saturation-transfer ESR spectra of spin-labeled cowpea chlorotic mottle virus

    NASA Astrophysics Data System (ADS)

    Hemminga, M. A.; Faber, A. J.

    A saturation-transfer ESR study is carried out on maleimide spin-labeled cowpea chlorotic mottle virus dissolved in various glycerol-water systems. The saturation-transfer ESR spectra were analyzed by comparing them with reference spectra of isotropically reorienting spin labels. The results are interpreted in terms of the overall motion of the virus particle, described by an isotropic rotational correlation time τR, and a local anisotropic spin-label motion with rotational correlation times τ| and τ⊥.

  12. Lack of association between the ESR1 rs9340799 polymorphism and age at menarche: a meta-analysis.

    PubMed

    Wu, H Y; Xing, X K; Wang, K J; Zhang, L

    2016-01-01

    It has been reported that the estrogen receptor alpha (ESR1) rs9340799 polymorphism is associated with age at menarche (AAM). However, recent investigations have generated inconsistent results. This study aimed to establish a more precise estimation of the association between this polymorphism and AAM. A meta-analysis was conducted based on an in silico literature search using PubMed. Six studies presenting continuous data, including ESR1 rs9340799 genotype frequencies, were selected. Effect size was estimated using Hedges' adjusted g with 95% confidence intervals (CIs), which were calculated based on the standardized mean difference between groups of subjects and different genotypes. No evidence of an association between the ESR1 rs9340799 polymorphism and AAM was found in the pooled continuous data under any genotype comparison (AA vs GG+AG: Hedges' g = -0.085, 95%CI = -0.202-0.032, P = 0.156; GG vs AA+AG: Hedges' g = 0.143, 95%CI = -0.041-0.327, P = 0.129; A vs G: Hedges' g = 0.187, 95%CI = -0.032-0.406, P = 0.095). Moreover, a funnel plot generated using this data was found to be symmetrical using the Egger (P = 0.797) and Begg tests (P = 0.851), indicating the absence of publication bias. In summary, our meta-analysis shows that the ESR1 rs9340799 polymorphism is not a significant, independent contributing factor to AAM. To validate this finding, further studies involving larger numbers of participants are needed. PMID:27525849

  13. E-layer dominated ionosphere observed by EISCAT/ESR radars during solar minimum

    NASA Astrophysics Data System (ADS)

    Cai, Hongtao; Li, Fei; Shen, Ge; Zhan, Weijia; Zhou, Kangjun; McCrea, Ian W.; Ma, Shuying

    2014-05-01

    E-layer dominated ionosphere (ELDI) is referred to vertical profiles having peak density at E-layer altitudes (Mayer and Jakowski, 2009). In this paper, characteristics of ELDI were investigated with the help of field-aligned measurements of EISCAT/ESR radars during 2009-2011. ELDI events were identified with simple but reasonable criterions, in which a minimal duration was required to exclude possible 'fake' events induced by random errors in measurements. It was found that ELDI were observed more often in winter than other seasons. In winter, occurrence of ELDI peaks around mid-night at auroral latitude, while it reaches its maximum around geomagnetic local noon at ESR latitude. Our results imply that ELDI looks like a sporadic rather than a regular phenomenon, being contrary to previous results inferred from radio occultation measurements. Discrepancy in duration of ELDI events observed by the two radars is remarkable, being 30 minutes at TromsØ on average and about a half of it at Svalbard. During the presence of ELDI, average thickness of E-layer exhibits undetectable variations at the two sites, as well as HmE and the ratio of NmE/NmF. Case studies reveal that either extra E-layer ionization possible induced by auroral precipitation or density depletion in F-layer caused by plasma convection alone could lead to the presence of ELDI. We suggest that both them play an important role in ELDI formation.

  14. Investigation of irradiated 1H-Benzo[b]pyrrole by ESR, thermal methods and learning algorithm

    NASA Astrophysics Data System (ADS)

    Algul, Gulay; Ceylan, Yusuf; Usta, Keziban; Yumurtaci Aydogmus, Hacer; Usta, Ayhan; Asik, Biray

    2016-05-01

    1H-Benzo[b]pyrrole samples were irradiated in the air with gamma source at 0.969 kGy per hour at room temperature for 24, 48 and 72 h. After irradiation, electron spin resonance, thermogravimetry analysis (TGA) and differential thermal analysis (DTA) measurements were immediately carried out on the irradiated and unirradiated samples. The ESR measurements were performed between 320 and 400 K. ESR spectra were recorded from the samples irradiated for 48 and 72 h. The obtained spectra were observed to be dependent on temperature. Two radical-type centres were detected on the sample. Detected radiation-induced radicals were attributed to R-+•NH and R=•CC2H2. The g-values and hyperfine constants were calculated by means of the experimental spectra. It was also determined from TGA spectrum that both the unirradiated and irradiated samples were decomposed at one step with the rising temperature. Moreover, a theoretical study was presented. Success of the machine learning methods was tested. It was found that bagging techniques, which are widely used in the machine learning literature, could optimise prediction accuracy noticeably.

  15. Distribution of tempo-dichlorotriazine spin label on immunoglobulin molecule. Interpretation of ESR spectra

    SciTech Connect

    Nezlin, R.

    1986-03-05

    Spin label TEMPO-dichlorotriazine (DT) has been used previously for determination of the rotational relaxation times of immunoglobulin (Ig) molecules and evaluation of their flexibility. Well defined outer wide extrema as well as sharp inner extrema are characteristic for ESR spectra of spin labeled Ig molecules. Such patterns of the spectrum can be accounted for either by the existence of the spin label in two states, one corresponding to its rapid and another to its restricted rotation or by varying environments of the spin label located in different areas of the Ig molecule. To choose between these possibilities, the distribution of /sup 14/C-TEMPO-DT on human IgG1(k) was studied. The same amount of the label per mg of protein was found in H and L chains as well as in the Fab fragment, and a smaller amount in the pFc'. The label was detected in most of the L chain tryptic peptides. Thus, the spin label is distributed nearly uniformly on IgG molecule, which is due to the regular distribution of amino acid residues reacted with the spin label. ESR spectra can be interpreted as a sum of individual spectra.

  16. Amine-based extraction recovery of Cu(II) from aqueous solutions in the presence of EDTA. Equilibrium studies

    SciTech Connect

    Juang, R.S.; Chen, Y.J.; Huang, I.P.

    1999-11-01

    The distribution ratios of Cu(II) between kerosene solutions of Aliquat 336 and water containing EDTA (ethylenediaminetetraacetic acid) are measured. Experiments were performed as a function of the pH, the concentration of Cu(II), the concentration ratio of EDTA to Cu(II), and the concentration of amine. It is shown that the distribution ratios first increase with pH and then decrease with further increase in pH up to 7.0. The effect of temperature on the extraction was studied, and the enthalpy of the extraction reaction was determined. Finally, the nonideal behavior of the organic phase is discussed.

  17. A Comparable Study on Structural and Optical Properties of Cu2ZnSnS4 and Cu2ZnSnSe4 Nanocrystallines

    NASA Astrophysics Data System (ADS)

    Gu, Xiuquan; Zhang, Shuang; Zhao, Yulong; Zhu, Lei; Qiang, Yinghuai

    2014-10-01

    In this study, single-kesterite-phase Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) nanocrystallines have been synthesized by a simple solvothermal route. Scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible (UV-vis) absorbance and Raman scattering spectroscopy were used to characterize the optical and micro-structure properties of the as-synthesized samples. The bandgap of CZTS could be tuned in a large range by incorporating a few Se atoms. Both the CZTS and CZTSe exhibited the similar temperature dependence of the Raman "A" modes, including a monotonic redshift in peak position and an irregular variation in peak linewidth. Such a behavior might be due to the cumulative effect of thermal expansion and small crystalline sizes.

  18. Magnetic and dielectric studies of Li-Cu co-doped ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Vivek, S.; Ajith, S. K.; Chitralekha, C. S.; Nair, Swapna S.

    2016-05-01

    Room temperature ferromagnetism has been observed in Li-Cu co-doped ZnO nanoparticles prepared by sol-gel route. Our studies indicated that the observed ferromagnetism is a surface phenomenon which depends on oxygen vacancy and the nature of the dopants. Dependence of ferromagnetism on the annealing temperature indicated the role of oxygen vacancy, and the decrease in coercivity as the particle size increases indicates the surface dependence of ferromagnetism. It is found that the addition of dopants also enhanced ferromagnetism. Dielectric studies indicated an increase in dielectric constant as the doping concentration is increased.

  19. NQR-NMR studies of higher alcohol synthesis Cu-Co catalysts. Final technical progress report

    SciTech Connect

    Murty, A.N.

    1995-03-10

    In recent years, due to the many technical advantages of using alcohol-gasoline blends, various processes for the production of higher alcohols from synthesis gas have been studied. The intent of this project is to conduct a comprehensive investigation into the nature of the electronic charge distribution in the vicinity of copper and cobalt nuclei in selected higher alcohol synthesis catalyst systems. Any strong perturbation in the orbital electronic charge distribution of Cu and Co is expected to sensitively influence both their catalytic properties and magnetic characteristics. The NMR and magnetic characterization studies undertaken in this investigation attempt to provide a better understanding of the correlation between magnetic and catalytic properties.

  20. First-principles study of transparent p-type conductive SrCu2O2 and related compounds

    NASA Astrophysics Data System (ADS)

    Nie, Xiliang; Wei, Su-Huai; Zhang, S. B.

    2002-02-01

    Using first-principles band structure methods we have systematically studied the electronic and optical properties of p-type transparent conductive oxides SrCu2O2 and related compounds AIICu2O2, where A=Mg, Ca, and Ba, as well as their host material Cu2O. We show that all these compounds have direct band gap at the zone center (Γ) with SrCu2O2 having the largest band gap. The trend of band gap variation of AIICu2O2 as a function of AII is explained in terms of atomic energy levels and atomic sizes of the AII elements. Transparency of SrCu2O2 is explained by the calculated dipole transition matrix elements. The calculated effective masses for the conduction band states are found to be larger than those for the valence states for SrCu2O2, opposite to the trend in conventional semiconductors and n-type transparent conductive oxides. We predict that adding a small amount of Ca (~16%) into SrCu2O2 can increase the band gap and reduce the hole effective mass of SrCu2O2, therefore, increase the transparency and conductivity.

  1. Adsorption and dissociation of O 2 on CuCl(1 1 1) surface: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Zhang, Riguang; Liu, Hongyan; Wang, Baojun; Ren, Jun; Li, Zhong

    2011-10-01

    The adsorption and dissociation of O 2 on CuCl(1 1 1) surface have been systematically studied by the density functional theory (DFT) slab calculations. Different kinds of possible modes of atomic O and molecular O 2 adsorbed on CuCl(1 1 1) surface and possible dissociation pathways are identified, and the optimized geometry, adsorption energy, vibrational frequency and Mulliken charge are obtained. The calculated results show that the favorable adsorption occurs at hollow site for O atom, and molecular O 2 lying flatly on the surface with one O atom binding with top Cu atom is the most stable adsorption configuration. The O-O stretching vibrational frequencies are significantly red-shifted, and the charges transferred from CuCl to oxygen. Upon O 2 adsorption, the oxygen species adsorbed on CuCl(1 1 1) surface mainly shows the characteristic of the superoxo (O 2-), which primarily contributes to improving the catalytic activity of CuCl, meanwhile, a small quantity of O 2 dissociation into atomic O also occur, which need to overcome very large activation barrier. Our results can provide some microscopic information for the catalytic mechanism of DMC synthesis over CuCl catalyst from oxidative carbonylation of methanol.

  2. Magnetic excitations in the spin-1/2 triangular-lattice antiferromagnet Cs2CuBr4

    SciTech Connect

    Zvyagin, S. A.; Ozerov, M.; Kamenskyi, D.; Wosnitza, J.; Krzystek, J.; Yoshizawa, D.; Hagiwara, M.; Hu, Rongwei; Ryu, Hyejin; Petrovic, C.; Zhitomirsky, M. E.

    2015-11-27

    We present on high- field electron spin resonance (ESR) studies of magnetic excitations in the spin- 1/2 triangular-lattice antiferromagnet Cs2CuBr4. Frequency- field diagrams of ESR excitations are measured for different orientations of magnetic fields up to 25 T. We show that the substantial zero- field energy gap, Δ ≈ 9.5 K, observed in the low-temperature excitation spectrum of Cs2CuBr4 [Zvyagin et al:, Phys. Rev. Lett. 112, 077206 (2014)], is present well above TN. Noticeably, the transition into the long-range magnetically ordered phase does not significantly affect the size of the gap, suggesting that even below TN the high-energy spin dynamics in Cs2CuBr4 is determined by short-range-order spin correlations. The experimental data are compared with results of model spin-wave-theory calculations for spin-1/2 triangle-lattice antiferromagnet.

  3. ESR response of CFQ-Gd2O3 dosimeters to a mixed neutron-gamma field: Monte Carlo simulation.

    PubMed

    Hoseininaveh, M; Ranjbar, A H

    2015-11-01

    Clear fused quartz (CFQ) may be considered a suitable material for electron and gamma dose measurements using electron spin resonance (ESR) technique. Research has been ongoing to optimize the neutron capture therapy (NCT) mechanism and its effects in cancer treatment. Neutron sources of the mixed neutron-gamma field are a challenge for this treatment method. A reliable dosimetric measurement and treatment should be able to determine various components of this mixed field. In this study, the ESR response of cylindrical and spherical shells of CFQ dosimeters, filled with Gd2O3, when exposed to a thermal neutron beam, has been investigated using Monte Carlo simulation. In order to maximize the ESR response, the dimensions of the outer and inner parts of the samples have been chosen as variables, and the amount of energy deposited in the samples has been determined. The optimum size of the samples has been determined, and the capability of discriminating gamma and neutron dose in a mixed neutron-gamma field regarding the CFQ-Gd2O3 dosimeter has also been widely studied.

  4. Magnetoresistive study of the antiferromagnetic-weak ferromagnetic transition in single-crystal La2CuO4+δ

    NASA Astrophysics Data System (ADS)

    Belevtsev, B. I.; Dalakova, N. V.; Savitsky, V. N.; Panfilov, A. S.; Braude, I. S.; Bondarenko, A. V.

    2004-05-01

    Resistive measurements were made to study the magnetic field-induced antiferromagnetic (AF)—weak ferromagnetic (WF) transition in the La2CuO4 single crystal. The magnetic field (dc or pulsed) was applied normally to the CuO2 layers. The transition manifested itself in a drastic decrease of the resistance in critical fields of 5-7 T. The study is the first to display the effect of the AF-WF transition on the conductivity of the La2CuO4 single crystal in the direction parallel to the CuO2 layers. The results provide support for the three-dimensional nature of the hopping conduction of this layered oxide.

  5. Evolution of atomic structure in Al75Cu25 liquid from experimental and ab initio molecular dynamics simulation studies.

    PubMed

    Xiong, L H; Yoo, H; Lou, H B; Wang, X D; Cao, Q P; Zhang, D X; Jiang, J Z; Xie, H L; Xiao, T Q; Jeon, S; Lee, G W

    2015-01-28

    X-ray diffraction and electrostatic levitation measurements, together with the ab initio molecular dynamics simulation of liquid Al(75)Cu(25) alloy have been performed from 800 to 1600 K. Experimental and ab initio molecular dynamics simulation results match well with each other. No abnormal changes were experimentally detected in the specific heat capacity over total hemispheric emissivity and density curves in the studied temperature range for a bulk liquid Al(75)Cu(25) alloy measured by the electrostatic levitation technique. The structure factors gained by the ab initio molecular dynamics simulation precisely coincide with the experimental data. The atomic structure analyzed by the Honeycutt-Andersen index and Voronoi tessellation methods shows that icosahedral-like atomic clusters prevail in the liquid Al(75)Cu(25) alloy and the atomic clusters evolve continuously. All results obtained here suggest that no liquid-liquid transition appears in the bulk liquid Al(75)Cu(25) alloy in the studied temperature range. PMID:25524926

  6. Evolution of atomic structure in Al75Cu25 liquid from experimental and ab initio molecular dynamics simulation studies.

    PubMed

    Xiong, L H; Yoo, H; Lou, H B; Wang, X D; Cao, Q P; Zhang, D X; Jiang, J Z; Xie, H L; Xiao, T Q; Jeon, S; Lee, G W

    2015-01-28

    X-ray diffraction and electrostatic levitation measurements, together with the ab initio molecular dynamics simulation of liquid Al(75)Cu(25) alloy have been performed from 800 to 1600 K. Experimental and ab initio molecular dynamics simulation results match well with each other. No abnormal changes were experimentally detected in the specific heat capacity over total hemispheric emissivity and density curves in the studied temperature range for a bulk liquid Al(75)Cu(25) alloy measured by the electrostatic levitation technique. The structure factors gained by the ab initio molecular dynamics simulation precisely coincide with the experimental data. The atomic structure analyzed by the Honeycutt-Andersen index and Voronoi tessellation methods shows that icosahedral-like atomic clusters prevail in the liquid Al(75)Cu(25) alloy and the atomic clusters evolve continuously. All results obtained here suggest that no liquid-liquid transition appears in the bulk liquid Al(75)Cu(25) alloy in the studied temperature range.

  7. Spectroscopic Cathodoluminescence Studies of the ZnTe:Cu Contact Process for CdS/CdTe Solar Cells: Preprint

    SciTech Connect

    Gessert, T. A.; Romero, M. J.; Johnston, S.; Keyes, B.; Dippo, P.

    2002-05-01

    This conference paper describes the spectroscopic cathodoluminescence (CL), electron-beam induced current (EBIC), and capacitance-Voltage (C-V) measurements are used to study the formation of CdS/CdTe devices processed using ion-beam milling and a ZnTe:Cu/Ti contact. Results show heating in vacuum at {approx}360 C and ion-beam milling lead to observable changes in the CL emission from the CdCl2-treated CdTe surface. Changes in the CL spectrum are also observed as ZnTe:Cu layer thickness increases. These changes are correlated to published studies of defect levels and shown to be due, possibly, to an n-type region existing between the ZnTe:Cu contact interface and the p-CdTe layers. This n-type region is eliminated once a sufficiently thick ZnTe:Cu layer is produced.

  8. A new 2 methylalanine-PVC ESR dosimeter.

    PubMed

    Rossi, Bruno T; Chen, Felipe; Baffa, Oswaldo

    2005-02-01

    The use of polyvinyl chloride (PVC) as a binder to 2-methylalanine (2MA) dosimeters was investigated. It was recently shown by Olsson et al. (Radiat. Res. 157 (2002) 113), that 2MA is approximately 70% more sensitive than L-alanine which makes this substance a good candidate to replace alanine in ESR dosimetry. PVC is a low yield material for free radical production by ionizing radiation and a good binding material easily processed and widely available. PVC can be prepared at room temperature and mixed up to 50% in weight with 2MA to produce a pellet stable in mass and physical dimensions, in large quantities and with low background signal. Pure PVC pellet irradiated at 50 Gy gave weaker ESR signals compared to 2MA at the region of spectral interest. Spectrometer settings such as microwave power, and modulation amplitude were optimized for the measurements. This dosimeter production scheme allows the addition of Mn2+ ions for an internal reference signal, leading to a self-calibrated dosimeter (J. Radional. Nucl. Chem. 240 (1999) 215).

  9. The p-type conduction mechanism in Cu2O: a first principles study.

    PubMed

    Nolan, Michael; Elliott, Simon D

    2006-12-01

    Materials based on Cu2O are potential p-type transparent semiconducting oxides. Developing an understanding of the mechanism leading to p-type behaviour is important. An accepted origin is the formation of Cu vacancies. However, the way in which this mechanism leads to p-type properties needs to be investigated. This paper presents a first principles analysis of the origin of p-type semiconducting behaviour in Cu2O with 1.5 and 3% Cu vacancy concentrations. Plane wave density functional theory (DFT) with the Perdew-Burke Ernzerhof (PBE) exchange-correlation functional is applied. In order to investigate the applicability of DFT, we firstly show that CuO, with 50% Cu vacancies cannot be described with DFT and in order to obtain a consistent description of CuO, the DFT + U approach is applied. The resulting electronic structure is consistent with experiment, with a spin moment of 0.64 mu(B) and an indirect band gap of 1.48 eV for U = 7 eV. However, for a 3% Cu vacancy concentration in Cu2O, the DFT and DFT + U descriptions of Cu vacancies are similar, indicating that DFT is suitable for a small concentration of Cu vacancies; the formation energy of a Cu vacancy is no larger than 1.7 eV. Formation of Cu vacancies produces delocalised hole states with hole effective masses consistent with the semiconducting nature of Cu2O. These results demonstrate that the p-type semiconducting properties observed for Cu2O are explained by a small concentration of Cu vacancies. PMID:19810413

  10. Estrogen receptor alpha (ESR1)-signaling regulates the expression of the taxane-response biomarker PRP4K.

    PubMed

    Lahsaee, Sara; Corkery, Dale P; Anthes, Livia E; Holly, Alice; Dellaire, Graham

    2016-01-01

    The pre-mRNA splicing factor 4 kinase PRP4K (PRPF4B), is an essential kinase that is a component of the U5 snRNP and functions in spliceosome assembly. We demonstrated that PRP4K is a novel biological marker for taxane response in ovarian cancer patients and reduced levels of PRP4K correlate with intrinsic and acquired taxane resistance in both breast and ovarian cancer. Breast cancer treatments are chosen based on hormone and growth factor receptor status, with HER2 (ERBB2) positive breast cancer patients receiving anti-HER2 agents and taxanes and estrogen receptor alpha (ESR1) positive (ER+) breast cancer patients receiving anti-estrogen therapies such as tamoxifen. Here we demonstrate that PRP4K is expressed in the normal mammary duct epithelial cells of the mouse, and that estrogen induces PRP4K gene and protein expression in ER+ human MCF7 breast cancer cells. Estrogen acts through ESR1 to regulate PRP4K expression, as over-expression of ESR1 in the ER-negative MDA-MB-231 breast cancer cell line increased the expression of this kinase, and knock-down of ESR1 in ER+ T47D breast cancer cells reduced PRP4K levels. Furthermore, treatment with 4-hydroxytamoxifen (4-OHT) resulted in a dose-dependent decrease in PRP4K protein expression in MCF7 cells. Consistent with our previous studies identifying PRP4K as a taxane-response biomarker, reduced PRP4K expression in 4-OHT-treated cells correlated with reduced sensitivity to paclitaxel. Thus, PRP4K is novel estrogen regulated kinase, and its levels can be reduced by 4-OHT in ER+ breast cancer cells altering their response to taxanes. PMID:26712520

  11. Experimental study of enhanced heat transfer by addition of CuO nanoparticle

    NASA Astrophysics Data System (ADS)

    Jesumathy, Stella; Udayakumar, M.; Suresh, S.

    2012-06-01

    An energy storage system has been designed to study the thermal characteristics of paraffin wax with an embedded nano size copper oxide (CuO) particle. This paper presents studies conducted on phase transition times, heat fraction as well as heat transfer characteristics of paraffin wax as phase change material (PCM) embedded with CuO nanoparticles. 40 nm mean size CuO particles of 2, 5 and 10% by weight were dispersed in PCM for this study. Experiments were performed on a heat exchanger with 1.5-10 l/min of heat transfer fluid (HTF) flow. Time-based variations of the temperature distributions are revealed from the results of observations of melting and solidification curves. The results strongly suggested that the thermal conductivity enhances 6, 6.7 and 7.8% in liquid state and in dynamic viscosity it enhances by 5, 14 and 30% with increasing mass fraction of the CNEPs. The thermal conductivity ratio of the composites can be augmented by a factor up to 1.3. The heat transfer coefficient during solidification increased about 78% for the maximum flow rate. The analysis of experimental results reveals that the addition of copper oxide nanoparticles to the paraffin wax enhances both the conduction and natural convection very effectively in composites and in paraffin wax. The paraffin wax-based composites have great potential for energy storage applications like industrial waste heat recovery, solar thermal applications and solar based dynamic space power generation with optimal fraction of copper oxide nanoparticles.

  12. Low microwave-amplitude ESR spectroscopy: measuring spin-relaxation interactions of moderately immobilized spin labels in proteins.

    PubMed

    Hedin, Eva M K; Hult, Karl; Mouritsen, Ole G; Høyrup, Pernille

    2004-08-31

    Electron spin resonance (ESR) spectroscopy in combination with site-directed spin labeling (SDSL) is a powerful tool for determining protein structure, dynamics and interactions. We report here a method for determining interactions between spin labels and paramagnetic relaxation agents, which is performed under subsaturating conditions. The low microwave-field amplitude employed (h(1)<0.36 G) only requires standard, commercially available ESR equipment. The effect of relaxation enhancement on the spin-spin-relaxation time, T(2e), is measured by this method, and compared to classical progressive power saturation performed on a free spin label, (1-oxyl-2,2,5,5-tetramethyl-Delta(3)-pyrroline-3-methyl)methanethiosulfonate (MTSL), and a spin-labeled protein (Thermomyces lanuginosa lipase, TLL-I252C), employing the water-soluble relaxation agent chromium(III) oxalate (Crox) in concentrations between 0-10 mM. The low-amplitude theory showed excellent agreement with that of classical power saturation in quantifying Crox-induced relaxation enhancement. Low-amplitude measurements were then performed using a standard resonator, with Crox, on 11 spin-labeled TLL mutants displaying rotational correlation times in the motional narrowing regime. All spin-labeled proteins exhibited significant changes in T(2e). We postulate that this novel method is especially suitable for studying moderately immobilized spin labels, such as those positioned at exposed sites in a protein. This method should prove useful for research groups with access to any ESR instrumentation.

  13. Neutron diffraction, specific heat and magnetization studies on Nd2CuTiO6

    NASA Astrophysics Data System (ADS)

    Rayaprol, S.; Kaushik, S. D.; Kumar, Naresh; Singh, K.; Guillou, F.; Simon, C.

    2016-05-01

    Structural and physical properties of a double-perovskite compound, Nd2CuTiO6 have been studied using neutron diffraction, magnetization and specific heat measurements. The compound crystallizes in an orthorhombic structure in space group Pnma. The interesting observation we make here is that, though no long range magnetic order is observed between 2 and 300K, the low temperature specific heat and magnetic susceptibility behavior exhibits non-Fermi liquid like behavior in this insulating compound. The magnetization and specific heat data are presented and discussed in light of these observations.

  14. The Study of Copper Zinc Sulphide (CuZnS2) Thin Films

    NASA Astrophysics Data System (ADS)

    Chukwuemeka Uhuegbu, Chidi; Bamidele Babatunde, Elisha; Oluwafemi, Cornelius O.

    2008-01-01

    Thin films of CuZnS2 were successfully deposited on glass substrates from aqueous solution of copper chloride in which EDTA and TEA were used as complexing agents. The optical and solid state properties were studied include: absorbance, transmittance, reflectance, extinction coefficient, refractive index, absorption coefficient, optical conductivity, dielectric constants. The direct and indirect band gaps obtained ranges from 2.2 eV to 2.4 eV for direct band gap and 0.4 eV to 0.9 eV for indirect band gap. The possible applications were also mentioned.

  15. Radiation damage studies on stainless steel, Ni, Cu, Mo for nuclear fusion reactors

    NASA Astrophysics Data System (ADS)

    Constantinescu, B.; Sarbu, C.; Simionescu, Luiza

    1997-04-01

    Studies on dose and energy dependence of blistering and flaking on stainless steels, Ni, Cu, Mo produced by 3.0, 4.7 and 6.8 MeV He + ions irradiation are presented. Using SEM and TEM techniques, irradiation phenomena such as sponge- and wave-like structures, submicronic cracks, microcraters, helium bubbles on matrix, grain boundaries, loops and TiC precipitates are illustrated. The appearance of an amorphous phase in the Ti-modified austenitic steel 12KH18N10T is discussed. QTMD preliminary results on H reemission in He preimplanted Ni samples are reported.

  16. ESR dating pleistocene barnacles from BC and Maine: a new method for tracking sea level change.

    PubMed

    Blackwell, Bonnie A B; Gong, J J J; Skinner, Anne R; Blais-Stevens, Andrée; Nelson, Robert E; Blickstein, Joel I B

    2010-02-01

    Barnacles have never been successfully dated by electron spin resonance (ESR). Living mainly in the intertidal zone, barnacles die when sea level changes cause their permanent exposure. Thus, dating the barnacles dates past sea level changes. From this, we can measure apparent sea level changes that occur due to ocean volume changes, crustal isostasy, and tectonics. ESR can date aragonitic mollusc shells ranging in age from 5 ka to at least 500 ka. By modifying the standard ESR method for molluscs to chemically dissolve 20 microm from off the shells, six barnacle samples from Norridgewock, Maine, and Khyex River, British Columbia, were tested for suitability for ESR dating. Due to Mn2+ interference peaks, the four Maine barnacle samples were not datable by ESR. Two barnacles from BC, which lacked Mn2+ interference, yielded a mean ESR age of 15.1 +/- 1.0 ka. These ages agree well with 14C dates on the barnacles themselves and wood in the overlying glaciomarine sediment. Although stability tests to calculate the mean dating signal lifetime and more ESR calibration tests against other barnacles of known age are needed to ensure the method's accuracy, ESR can indeed date Balanus, and thus, sea level changes.

  17. Density functional theory study of 3R- and 2H-CuAlO2 under pressure

    NASA Astrophysics Data System (ADS)

    Liu, Qi-Jun; Liu, Zheng-Tang; Feng, Li-Ping; Tian, Hao; Liu, Wen-Ting; Yan, Feng

    2010-10-01

    We present a first-principles density-functional theory based study of the impact of pressure on the structural and elastic properties of bulk 3R- and 2H-CuAlO2. The ground state properties of 3R- and 2H-CuAlO2 are obtained, which are in good agreement with previous experimental and theoretical data. The analysis of enthalpy variation with pressure indicates the phase transition pressure between 3R and 2H is 15.4 GPa. The independent elastic constants of 3R- and 2H-CuAlO2 are calculated. As the applied pressure increases, the calculations show the presences of mechanical instability at 26.2 and 27.8 GPa for 3R- and 2H-CuAlO2, which are possibly related with the phase transitions.

  18. A Study on the Electrodeposited Cu-Zn Alloy Thin Films

    NASA Astrophysics Data System (ADS)

    Özdemir, Rasim; Karahan, İsmail Hakkı; Karabulut, Orhan

    2016-09-01

    In this article, electrochemical deposition of the nanocrystalline Cu1-x Zn x alloys on to aluminum substrates from a non-cyanide citrate electrolyte at 52.5, 105, 157.5, and 210 A m-2 current densities were described. The bath solution of the Cu1-x Zn x alloys consisted of 0.08 mol L-1 CuSO4·5H2O, 0.2 mol L-1 ZnSO4·7H2O, and 0.5 mol L-1 Na3C6H5O7. The effect of the current density on the microstrain, grainsize, phase structure, and DC electrical resistivity behavior was investigated. The electrolyte was investigated electrochemically by cyclic voltammetry (CV) studies. A scanning electron microscope (SEM) was used to study the morphologies of the deposits. Deposited alloys were investigated by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and four-point probe electrical resistivity techniques. With an increase in applied current density values from 52.5 to 210 A m-2, the amount of deposited copper in the alloy was decreased significantly from 65.5 to 16.6 pct and zinc increased from 34.4 to 83.4 pct. An increase in the current density was accompanied by an increase in grain size values from 65 to 95 nm. SEM observations indicated that the morphology of the film surface was modified to bigger grained nanostructures by increasing the current density. The XRD analysis showed alloys have a body-centered cubic (bcc) crystal structure with preferential planes of (110) and (211). Furthermore, four-point measurements of the films revealed that the resistivity of the deposited films was tailored by varying current densities in the electrolyte.

  19. A Study on the Electrodeposited Cu-Zn Alloy Thin Films

    NASA Astrophysics Data System (ADS)

    Özdemir, Rasim; Karahan, İsmail Hakkı; Karabulut, Orhan

    2016-11-01

    In this article, electrochemical deposition of the nanocrystalline Cu1- x Zn x alloys on to aluminum substrates from a non-cyanide citrate electrolyte at 52.5, 105, 157.5, and 210 A m-2 current densities were described. The bath solution of the Cu1- x Zn x alloys consisted of 0.08 mol L-1 CuSO4·5H2O, 0.2 mol L-1 ZnSO4·7H2O, and 0.5 mol L-1 Na3C6H5O7. The effect of the current density on the microstrain, grainsize, phase structure, and DC electrical resistivity behavior was investigated. The electrolyte was investigated electrochemically by cyclic voltammetry (CV) studies. A scanning electron microscope (SEM) was used to study the morphologies of the deposits. Deposited alloys were investigated by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and four-point probe electrical resistivity techniques. With an increase in applied current density values from 52.5 to 210 A m-2, the amount of deposited copper in the alloy was decreased significantly from 65.5 to 16.6 pct and zinc increased from 34.4 to 83.4 pct. An increase in the current density was accompanied by an increase in grain size values from 65 to 95 nm. SEM observations indicated that the morphology of the film surface was modified to bigger grained nanostructures by increasing the current density. The XRD analysis showed alloys have a body-centered cubic (bcc) crystal structure with preferential planes of (110) and (211). Furthermore, four-point measurements of the films revealed that the resistivity of the deposited films was tailored by varying current densities in the electrolyte.

  20. Optical spectroscopy study of pulsed excimer laser generated plasma from CuO

    SciTech Connect

    Adhi, K.P.; Kale, S.; Padhye, Y.; Limaye, A.V.; Ogale, S.B.

    1995-12-15

    Optical emissions from pulsed excimer laser induced plasma emanating from CuO target are studied by an Optical Multichannel Analyzer system in the context of its implications for thin film growth by Pulsed Laser Deposition. The plasma is generated in four different ambients viz. hydrogen, helium, oxygen (pressure of 100 mTorr in each case) and vacuum (2 {times} 10{sup {minus}5} Torr) at different energy densities from 1 to 3.5 J/cm{sup 2}. The plasma constituents and their evolution in the growth space (i.e. at a distance of 1.5 cm from the target) has been studied. Various transitions corresponding to Cu(I), H(I), Cu(II) and O(II) are observed. The observation of strong transitions due to O(II) in the plasma formed in vacuum, hydrogen and helium suggests significant degree of ionization of atoms via molecular splitting and inverse Bremsstrahlung process during early plasma formation. The persistence of ionicity in the plasma can be attributed to long recombination lifetimes for the specific conditions used. In the case of ablation in oxygen ambient a very significant and remarkably selective enhancement of the copper vapor lasing transition at 510.5 nm is observed which brings out the role of oxygen molecules in sustaining the radiation trapping condition. The changes in the concentrations of neutrals and ions are a function of the laser energy density are also examined. It is argued that impingement of ions/atoms in an excited state on the growing surface can potentially lead to localized energy deposition via non-radiative deexcitation resulting into enhancement of film quality and density.

  1. NO Chemisorption on Cu/SSZ-13: a Comparative Study from Infrared Spectroscopy and DFT Calculations

    SciTech Connect

    Zhang, Renqin; McEwen, Jean-Sabin; Kollar, Marton; Gao, Feng; Wang, Yilin; Szanyi, Janos; Peden, Charles HF

    2014-11-07

    The locations and energies of Cu ions in a Cu/SSZ-13 zeolite catalyst were investigated by density functional theory (DFT) calculations. For 'naked' Cu2+ ions (i.e., Cu2+ ions with no ligands in their coordination spheres other than zeolite lattice oxygen atoms), the more energetically favorable sites are within a 6-membered ring. However, with the presence of various adsorbates, the energy difference between 6- and 8-membered ring locations greatly diminishes. Specifically, Cu2+ ions are substantially stabilized by -OH ligands (as [CuII(OH)]+), making the extra-framework sites in an 8-membered ring energetically more favorable than 6-membered ring sites. Under fully dehydrated high vacuum conditions with different Si/Al and Cu/Al ratios, three chemisorbed NO species coexist upon exposure of NO to Cu/SSZ-13: NO+, Cu2+-NO and Cu+-NO. The relative signal intensities for these bands vary greatly with Si/Al ratios. The vibrational frequency of chemisorbed NO was found to be very sensitive to the location of Cu2+ ions. On the one hand, with the aid from DFT calculations, the nature for these vibrations can be assigned in detail. On the other hand, the relative intensities for various Cu2+-NO species provide a good measure of the nature of Cu2+ ions as functions of Si/Al and Cu/Al ratios and the presence of humidity. These new findings cast doubt on the generally accepted proposal that only Cu2+ ions located in 6-membered rings are catalytically active for NH3-SCR.

  2. Stabilization of Pb and Cu in contaminated soils using (nano)oxides - a preliminary study

    NASA Astrophysics Data System (ADS)

    Komárek, Michael; Michálková, Zuzana; Vaněk, Aleš

    2013-04-01

    Chemical stabilization techniques (the application of various stabilizing amendments, which by chemical means reduces contaminant mobility, bioavailability and bioaccessibility) have shown to be possible less destructive alternatives to conventional remediation options. Most stabilization techniques aim at rendering less available the metal(loid) fractions that can pose significant environmental and/or toxicological risks and protecting the functionality of the soil environment. Nano-particulate oxides (particle size of 1-100 nm) are important scavengers of contaminants in soils and due to their reactive and relatively large specific surface area, engineered oxide nanoparticles are promising materials for the remediation of soils contaminated with inorganic pollutants. However, studies assessing the efficiency of these amendments in contaminated soils are still rather scarce. Therefore, the aim of this work is to evaluate the stabilization efficiency of four (nano)oxides (maghemite, magnetite, gibbsite and amorphous Mn oxide (AMO)) in two soils contaminated with Cu (400 mg/kg; pH 3.6) and Pb (1500 mg/kg; pH 5.5), respectively, using chemical extraction methods (CaCl2, EDTA and the BCR sequential extraction) and direct sampling of soil solution using rhizons. The results suggest that the application of the oxides did not influence the pH of the soils, with the only exception of the AMO, which increased the pH and resulted into the formation of MnCO3 on the oxide surface (data from SEM and XRD). Additionally, the high reactivity of the oxides led to increased DOC concentrations originating from the dissolved soil organic matter, especially in the case of the AMO. The AMO was also the most efficient stabilizing amendment for Cu (most significant decrease in Cu in soil solution, in the exchangeable fraction and CaCl2/EDTA extracts), promoted by the pH increase. Despite their lower particle size, maghemite, magnetite and gibbsite were less efficient; although partial

  3. Surface chemistry of a Cu(I) beta-diketonate precursor and the atomic layer deposition of Cu{sub 2}O on SiO{sub 2} studied by x-ray photoelectron spectroscopy

    SciTech Connect

    Dhakal, Dileep; Waechtler, Thomas; Schulz, Stefan E.; Gessner, Thomas; Lang, Heinrich; Mothes, Robert; Tuchscherer, André

    2014-07-01

    The surface chemistry of the bis(tri-n-butylphosphane) copper(I) acetylacetonate, [({sup n}Bu{sub 3}P){sub 2}Cu(acac)] and the thermal atomic layer deposition (ALD) of Cu{sub 2}O using this Cu precursor as reactant and wet oxygen as coreactant on SiO{sub 2} substrates are studied by in-situ x-ray photoelectron spectroscopy (XPS). The Cu precursor was evaporated and exposed to the substrates kept at temperatures between 22 °C and 300 °C. The measured phosphorus and carbon concentration on the substrates indicated that most of the [{sup n}Bu{sub 3}P] ligands were released either in the gas phase or during adsorption. No disproportionation was observed for the Cu precursor in the temperature range between 22 °C and 145 °C. However, disproportionation of the Cu precursor was observed at 200 °C, since C/Cu concentration ratio decreased and substantial amounts of metallic Cu were present on the substrate. The amount of metallic Cu increased, when the substrate was kept at 300 °C, indicating stronger disproportionation of the Cu precursor. Hence, the upper limit for the ALD of Cu{sub 2}O from this precursor lies in the temperature range between 145 °C and 200 °C, as the precursor must not alter its chemical and physical state after chemisorption on the substrate. Five hundred ALD cycles with the probed Cu precursor and wet O{sub 2} as coreactant were carried out on SiO{sub 2} at 145 °C. After ALD, in-situ XPS analysis confirmed the presence of Cu{sub 2}O on the substrate. Ex-situ spectroscopic ellipsometry indicated an average film thickness of 2.5 nm of Cu{sub 2}O deposited with a growth per cycle of 0.05 Å/cycle. Scanning electron microscopy and atomic force microscopy (AFM) investigations depicted a homogeneous, fine, and granular morphology of the Cu{sub 2}O ALD film on SiO{sub 2}. AFM investigations suggest that the deposited Cu{sub 2}O film is continuous on the SiO{sub 2} substrate.

  4. Structural and optical properties of Cu doped SnO2 nanoparticles: An experimental and density functional study

    NASA Astrophysics Data System (ADS)

    Chetri, Pawan; Saikia, Bhamyarswa; Choudhury, Amarjyoti

    2013-06-01

    The paper investigates, both theoretically and experimentally, the structural and optical changes in SnO2 system brought about by introduction of Cu in a SnO2 system. On the experimental front, a cost effective sol-gel technique is used to prepare hexagonal shaped Cu doped SnO2 nanoparticles. The prepared pristine SnO2 nanoparticle is found to be of random shape by transmission electron microscope (TEM) studies. A structural and morphological study is carried out using X-ray diffraction and TEM techniques. The different phonon interaction in the system is observed by Raman spectroscopy while electron paramagnetic resonance and UV-Visible spectroscopy confirms the presence of Cu in 2+ state. First principle calculations have been performed using "density functional theory"-based MedeA Vienna Ab Initio Simulation package on a SnO2 system where Cu is introduced. The introduction of Cu in the SnO2 system brings distortion which is corroborated by the variation in the corresponding bond lengths. The Density of State calculation of Sn16O32 and CuSn15O32 is also performed. Finally, a correlation is established between the experiment and the theory.

  5. Improvement of the ESR detection of irradiated food containing cellulose employing a simple extraction method

    NASA Astrophysics Data System (ADS)

    Delincée, Henry; Soika, Christiane

    2002-03-01

    Fruit may be irradiated at rather low doses, below 1 kGy in combination treatments or for quarantine purposes. To improve the ESR detection sensitivity of irradiated fruit de Jesus et al. (Int. J. Food Sci. Technol. 34 (1999) 173.) proposed extracting the fruit pulp with 80% ethanol and measuring the residue with ESR using low power (0.25 mW) for detection of 'cellulosic' radicals. An improvement in ESR sensitivity using the extraction procedure could be confirmed in this paper for strawberries and papayas. In most cases, a radiation dose of 0.5 kGy could be detected in both fruits even after 2-3 weeks storage. In addition, some herbs and spices were also tested, but only for a few of them the ESR detection of the 'cellulosic' signal was improved by previous alcoholic extraction. As an alternative to ESR measurements, other detection methods like DNA Comet Assay and thermoluminescence were also tested.

  6. Further studies on the role of dopants in LiF:Mg,Cu,Si thermoluminescent material.

    PubMed

    Tang, K; Fan, H; Cui, H; Zhu, H; Liu, Z

    2015-02-01

    The 3-D thermoluminescence spectra and glow curves of LiF:Mg,Cu,Si, LiF:Mg,Cu, LiF:Mg,Si and LiF:Cu,Si with low concentrations of Mg and Cu were measured and were compared with those with high concentrations to investigate further the role of dopants in LiF:Mg,Cu,Si material. The shape of glow curves of the four samples is similar; however, LiF:Cu,Si sample had no Mg dopant. It is concluded that the TL emission to be from self-trapped excitons in LiF, and this emission could be enhanced and altered by Mg, Cu and Si dopants in LiF:Mg,Cu,Si; all three dopants are necessary to obtain the bright TL emission and may be involved in the luminescence process; Mg seems to be the most essential dopant and Cu is involved in the trapping although the role of Mg dominates; both Cu and Si play a role in the main emission process and Cu also plays a role in reducing the emission around 610 nm.

  7. Equilibriums between Cu, Fe, and Zn sulfides and oxides in chloride solution: A thermodynamic study

    NASA Astrophysics Data System (ADS)

    Strel'Tsova, N. I.

    2009-10-01

    The results of thermodynamic modeling of equilibriums between Cu, Fe, and Zn sulfides and oxides pertaining to the Cu-Fe-Zn-S-O2 system in water and aqueous chloride solution are presented. The system comprises solid phases of constant composition: pyrite, pyrrhotite, hematite, magnetite, wüstite, γ-iron, chalcocite, covellite, cuprite, native copper, chalcopyrite, and bornite, as well as more than 100 ions, complexes, and molecules in an aqueous solution. The GIBBS program with the UNITHERM thermodynamic dataset used in calculations allows numerical analysis of phase assemblages in a dry system and in equilibrium with an aqueous solution. How the temperature, pressure, and the composition of the solution in the system opened for oxygen and sulfur affects the composition of phase assemblages was considered in temperature and pressure ranges of 50-350 C and 100-1000 bar, respectively. Decrease in temperature leads to a shift in stability fields of the studied phases toward the region of elevated oxygen and sulfur partial pressures. Variation of temperature is an important factor affecting precipitation of ore minerals, primarily, Cu- and Zn-bearing. The calculation results are presented in tables and diagrams. Each point in the (log m_{S_{tot} } - log f_{O_2 } ) diagram is characterized by a single possible assemblage of phases equilibrated with a solution of the given composition within the considered temperature and pressure range. Since the composition of the mineral assemblage is controlled by physicochemical conditions at the moment of mineral formation, comparison of the calculation results with mineral assemblages at ore deposits makes it possible to estimate the parameters of ore deposition at the early stage of investigation, including oxygen and sulfur activity and, occasionally, the composition and salinity of the solution. These parameters control the formation of such assemblages.

  8. Model-based analysis for kinetic complexation study of Pizda and Cu(II).

    PubMed

    Vosough, M; Maeder, M; Jalali-Heravi, M; Norman, S E

    2008-08-01

    In the present work, the multivariate kinetic complexation of a new synthesized ligand, 1-(2''-hydroxyl cyclohexyl)-3'-[aminopropyl]-4-[3'-aminopropyl]piperazine (Pizda) and Cu(2+) in 50% ethanol-water solution is investigated using the UV-vis stopped-flow technique and state-of-the-art multi-wavelength numerical analysis. Model-based least squares fitting analysis or hard modeling is a specific part of chemometrics which is based on mathematical relationships for describing the measurements. Some recent developments include the incorporation of the effects of non-ideal experimental conditions into the fitting algorithm so it can substantially simplify experimental procedures. In this study no buffers are required because pH changes are taken into computations. Some 21 multi-wavelength kinetic measurements, taken at various initial concentrations of [H(+)] were analyzed globally, i.e. simultaneously applying an all inclusive reaction mechanism and a common set of species spectra. Using numerical analysis, the pH of the experimental solutions was allowed to vary as a consequence of the proceeding reactions. This enabled the complete kinetic analysis of the formation and dissociation of Cu(Pizda)(n+). Here protonation equilibria have been directly incorporated into the rate law, so thus variable pH values have been allowed during each measurement. Using the independently estimated stability constants (from spectrophotometric and potentiometric measurements) for the Cu(Pizda)(n+) complexes, a total of six rate constants and one protonation constant could be elucidated. The results of the analysis include the concentration distribution and spectra of all chemical species involved in the reaction. A low standard deviation and residual profiles obtained validate the results.

  9. Mn2+, Co2+, Cu2+ and Zn2+ complexes with two macrocyclic ligands bearing L-lactate-like functions: potentiometric studies and evaluation of superoxide-scavenging properties of the Mn2+ complex.

    PubMed

    Delagrange, S; Delgado, R; Nepveu, F

    2000-07-15

    Some aerobic organisms devoid of SOD use Mn2+ chelates to scavenge the O2- radical. Since the Mn2+-bis(lactato)diaquo complex is known as having a high SOD-like activity, we prepared manganese(II) complexes with triazamacrocyclic ligands bearing L-lactate-like functions in order to obtain model compounds able to disproportionate the superoxide radical. Thus, two macrocyclic ligands, N,N',N"-tris[2(S)-hydroxybutyric acid]-1,4,7-triazacyclononane, L1, and N,N',N"-tris[2(S)-hydroxybutyric acid]-1,5,9-triazacyclododecane, L2, were prepared and their capacity to retain the Mn2+ ion in aqueous solution was determined from potentiometric experiments. The chelating properties in aqueous solution of each ligand towards Co2+, Cu2+ and Zn2+ ions were also determined. L1 forms complexes with Mn2+, Co2+, Cu2+ and Zn2+ ions with stability constants of 8.33(5), 15.78(5), 17.65(3) and 14.32(1), respectively. L2 forms complexes with Cu2+ and Zn2+ ions with stability constants of 10.67(1) and 6.98(3), respectively. But the constants related to the Mn2+ and Co2+ complexes were too low to be determined by the method used. The stability constants values calculated for L2 complexes are significantly lower than those for the corresponding complexes of L1. Additional spectroscopic measurements were carried out on the Mn2+-L1 system. The electronic spectrum of this system showed a pH-dependence that may be consistent with the formation of hydroxo-species as the ESR spectra recorded at 120 K did not show oxidation of the Mn2+ ion in the pH range studied. The superoxide-scavenging activity of the manganese(II)-L1 complex was investigated using the cytochrome c assay. The Mn2+-L1 system showed an IC50 value of 1.7 microM which indicates that it appears as a potent SOD mimic.

  10. Dynamical X-ray Microscopy Study of Stress-Induced Voiding in Cu Interconnects

    NASA Astrophysics Data System (ADS)

    Heim, S.; Friedrich, D.; Guttmann, P.; Rehbein, S.; Chumakov, D.; Ritz, Y.; Schneider, G.; Schmeisser, D.; Zschech, E.

    2009-06-01

    High-resolution x-ray imaging with a spatial resolution in the 20 nm range offers unique capabilities for process development in semiconductor industry. Buried copper on-chip interconnect structures can be studied with excellent element specific contrast. In addition, it is possible to obtain 3-D views of fully embedded copper interconnect lines and vias. Moreover, transmission x-ray microscopy (TXM) is a very suitable technique to study dynamical, reliability-limiting processes like electromigration (EM) or stress-induced voiding (SIV). Stress-induced void formation is investigated in dual damascene Cu/SiOx and Cu/low-k interconnect stacks. The initial pre-stressing of the about 1.5 μm thick focused ion beam(FIB)-prepared cross-sections was performed by heating at a temperature of 175° C for 50 hours. Subsequently, a series of x-ray images was recorded using images after every five hours of heating at the same temperature. The dynamical SIV experiments show for the first time directly that voids are formed and grown further underneath the via.

  11. Passive optical limiting studies of nanostructured Cu doped ZnO-PVA composite thin films

    NASA Astrophysics Data System (ADS)

    Tamgadge, Y. S.; Sunatkari, A. L.; Talwatkar, S. S.; Pahurkar, V. G.; Muley, G. G.

    2016-01-01

    We prepared undoped and Cu doped ZnO semiconducting nanoparticles (NPs) by chemical co-precipitation method and obtained Cu doped ZnO-polyvinyl alcohol (PVA) nanocomposite thin films by spin coating to investigate third order nonlinear optical and optical limiting properties under cw laser excitation. Powder samples of NPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy, transmission electron microscopy, ultraviolet-visible (UV-vis) and Fourier transform infrared spectroscopy. XRD pattern and FE-SEM micrograph revealed the presence of hexagonal wurtzite phase ZnO NPs having uniform morphology with average particle size of 20 nm. The presence of excitons and absorption peaks in the range 343-360 nm, revealed by UV-vis study, were attributed to excitons in n = 1 quantum state. Third order NLO properties of all composite thin films were investigated by He-Ne continuous wave (cw) laser of wavelength 632.8 nm using Z-scan technique. Thermally stimulated enhanced values of nonlinear refraction and absorption coefficients were obtained which may be attributed to self-defocusing effect, reverse saturable absorption, weak free carrier absorption and surface states properties originated from thermo optic effect. Optical limiting properties have been studied using cw diode laser of wavelength 808 nm and results are presented.

  12. Novel bimetallic thiocyanate-bridged Cu(II)-Hg(II) compounds-synthesis, X-Ray studies and magnetic properties

    SciTech Connect

    Machura, B.; Switlicka, A.; Zwolinski, P.; Mrozinski, J.; Kalinska, B.; Kruszynski, R.

    2013-01-15

    Seven novel heterobimetallic Cu/Hg polymers based on thiocyanate bridges have been synthesised and characterised by means of IR, EPR, magnetic measurements and single crystal X-Ray. Three of them, [Cu(pzH){sub 4}Hg(SCN){sub 4}]{sub n} (1) [Cu(indH){sub 4}Hg(SCN){sub 4}]{sub n} (2) and [Cu(ampy){sub 2}Hg(SCN){sub 4}]{sub n} (3), have one-dimensional coordination structure. Two compounds [Cu(pzH){sub 2}Hg(SCN){sub 4}]{sub n} (4) and [Cu(abzimH)Hg(SCN){sub 4}]{sub n} (5) form two-dimensional nets, whereas the complexes [Cu(pyCN){sub 2}Hg(SCN){sub 4}]{sub n} (6) and [Cu(pyCH(OH)(OMe)){sub 2}Hg(SCN){sub 4}]{sub n} (7) are three-dimensional coordination polymers. The chains of 1 are connected by the intermolecular N-H Bullet Bullet Bullet N hydrogen bonds to the three dimensional net. In 2 the N-H Bullet Bullet Bullet S hydrogen bonds link the polymeric chains to the two dimensional layer extending along crystallographic (0 0 1) plane. The polymeric chains of compound 3 are joined by the intermolecular N-H Bullet Bullet Bullet N and N-H Bullet Bullet Bullet S hydrogen bonds to the three dimensional net. The polymeric layers of 4 are connected by the intermolecular N-H Bullet Bullet Bullet N hydrogen bonds to the three dimensional net. - Graphical abstract: Novel bimetallic thiocyanate-bridged Cu(II)-Hg(II) compound-synthesis,X-Ray studies and magnetic properties. Highlights: Black-Right-Pointing-Pointer Novel heterobimetallic Cu/Hg coordination polymers were synthesised. Black-Right-Pointing-Pointer The multidimensional structures have been proved by single X-ray analysIs. Black-Right-Pointing-Pointer A variation in the crystalline architectures was observed depending on auxiliary ligands. Black-Right-Pointing-Pointer Magnetic measurements indicate weak exchange interaction between Cu(II) in the crystal lattices below 10 K.

  13. Testing of variants of the MTHFR and ESR1 genes in 1798 Finnish individuals fails to confirm the association with migraine with aura.

    PubMed

    Kaunisto, M A; Kallela, M; Hämäläinen, E; Kilpikari, R; Havanka, H; Harno, H; Nissilä, M; Säkö, E; Ilmavirta, M; Liukkonen, J; Teirmaa, H; Törnwall, O; Jussila, M; Terwilliger, J; Färkkilä, M; Kaprio, J; Palotie, A; Wessman, M

    2006-12-01

    Among the few independently replicated genetic associations in migraine are polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) and oestrogen receptor (ESR1) genes. We studied the contribution of these genes to migraine susceptibility by genotyping six MTHFR and 26 ESR1 polymorphisms in 898 unrelated migraine with aura (MA) patients and in 900 unrelated healthy controls. There were no differences in the genotype distributions of the previously migraine-associated SNPs C677T (MTHFR) and G2014A (ESR1) between cases and controls (P-values 0.83 and 0.55, respectively). Thus, we were not able to replicate the previous findings, although our study had considerable power. However, five of the ESR1 SNPs (rs6557170, rs2347867, rs6557171, rs4870062 and rs1801132) that were in strong linkage disequilibrium were nominally associated with MA (uncorrected P-values 0.007-0.034). These results did not, however, remain significant after taking multiple testing into account. Thus it seems unlikely that the studied genes are involved in migraine susceptibility, at least in this sample. PMID:17116097

  14. Interaction of NH3 with Cu-SSZ-13 Catalyst: A Complementary FTIR, XANES, and XES Study.

    PubMed

    Giordanino, Filippo; Borfecchia, Elisa; Lomachenko, Kirill A; Lazzarini, Andrea; Agostini, Giovanni; Gallo, Erik; Soldatov, Alexander V; Beato, Pablo; Bordiga, Silvia; Lamberti, Carlo

    2014-05-01

    In the typical NH3-SCR temperature range (100-500 °C), ammonia is one of the main adsorbed species on acidic sites of Cu-SSZ-13 catalyst. Therefore, the study of adsorbed ammonia at high temperature is a key step for the understanding of its role in the NH3-SCR catalytic cycle. We employed different spectroscopic techniques to investigate the nature of the different complexes occurring upon NH3 interaction. In particular, FTIR spectroscopy revealed the formation of different NH3 species, that is, (i) NH3 bonded to copper centers, (ii) NH3 bonded to Brønsted sites, and (iii) NH4(+)·nNH3 associations. XANES and XES spectroscopy allowed us to get an insight into the geometry and electronic structure of Cu centers upon NH3 adsorption, revealing for the first time in Cu-SSZ-13 the presence of linear Cu(+) species in Ofw-Cu-NH3 or H3N-Cu-NH3 configuration. PMID:26270095

  15. Comparative study on the adsorption capacity of raw and modified litchi pericarp for removing Cu(II) from solutions.

    PubMed

    Kong, Zhenglei; Li, Xiaochen; Tian, Jiyu; Yang, Jili; Sun, Shujuan

    2014-02-15

    The adsorption of Cu(II) onto raw litchi pericarp (LP) and modified litchi pericarp (MLP) as a function of pH, adsorbent dose and contact time, were investigated. Adsorption equilibrium isotherms, kinetics, and thermodynamics were studied to characterize the adsorption process. Leaching assays were also conducted to evaluate the potential contamination risk of LP and MLP to aqueous systems. The maximum adsorption of Cu(II) onto MLP was occurred at the pH of 6.0, adsorbent dose of 10.0 g/L, and contact time of 60 min, respectively. The adsorption process of Cu(II) onto LP and MLP were described well by both Langmuir and Freundlich isotherms, and the adsorption kinetics of Cu(II) on MLP was pseudo-second-order. Cu(II) adsorption onto LP and MLP are both exothermic, while it is spontaneous for MLP, and non-spontaneous for LP. The maximum adsorption capacity of Cu(II) onto MLP was 23.70 mg/g, which was about 2.7 times higher than that of LP. Additionally, as compared to LP, the leaching amounts of TOC, TN, and TP from MLP were significantly reduced by a percentage of 27.0%, 90.3%, and 35.3%, respectively. PMID:24473344

  16. Adsorption kinetic and equilibrium study for removal of mercuric chloride by CuCl2-impregnated activated carbon sorbent.

    PubMed

    Li, Xin; Liu, Zhouyang; Lee, Joo-Youp

    2013-05-15

    The intrinsic adsorption kinetics of mercuric chloride (HgCl2) was studied for raw, 4% and 10% CuCl2-impregnated activated carbon (CuCl2-AC) sorbents in a fixed-bed system. An HgCl2 adsorption kinetic model was developed for the AC sorbents by taking into account the adsorption kinetics, equilibrium, and internal and external mass transfer. The adsorption kinetic constants determined from the comparisons between the simulation and experimental results were 0.2, 0.3, and 0.5m(3)/(gs) for DARCO-HG, 4%(wt), and 10%(wt) CuCl2-AC sorbents, respectively, at 140 °C. CuCl2 loading was found to slightly increase the adsorption kinetic constant or at least not to decrease it. The HgCl2 equilibrium adsorption data based on the Langmuir isotherm show that high CuCl2 loading can result in high binding energy of the HgCl2 adsorption onto the carbon surface. The adsorption equilibrium constant was found to increase by ~10 times when CuCl2 loading varied from 0 to 10%(wt), which led to a decrease in the desorption kinetic constant (k2) by ~10 times and subsequently the desorption rate by ~50 times. Intraparticle pore diffusion considered in the model showed good accuracy, allowing for the determination of intrinsic HgCl2 adsorption kinetics.

  17. The rotational spectrum of CuCCH(X̃  1Σ+): a Fourier transform microwave discharge assisted laser ablation spectroscopy and millimeter/submillimeter study.

    PubMed

    Sun, M; Halfen, D T; Min, J; Harris, B; Clouthier, D J; Ziurys, L M

    2010-11-01

    The pure rotational spectrum of CuCCH in its ground electronic state (X̃  (1)Σ(+)) has been measured in the frequency range of 7-305 GHz using Fourier transform microwave (FTMW) and direct absorption millimeter/submillimeter methods. This work is the first spectroscopic study of CuCCH, a model system for copper acetylides. The molecule was synthesized using a new technique, discharge assisted laser ablation spectroscopy (DALAS). Four to five rotational transitions were measured for this species in six isotopologues ((63)CuCCH, (65)CuCCH, (63)Cu(13)CCH, (63)CuC(13)CH, (63)Cu(13)C(13)CH, and (63)CuCCD); hyperfine interactions arising from the copper nucleus were resolved, as well as smaller splittings in CuCCD due to deuterium quadrupole coupling. Five rotational transitions were also recorded in the millimeter region for (63)CuCCH and (65)CuCCH, using a Broida oven source. The combined FTMW and millimeter spectra were analyzed with an effective Hamiltonian, and rotational, electric quadrupole (Cu and D) and copper nuclear spin-rotation constants were determined. From the rotational constants, an r(m)(2) structure for CuCCH was established, with r(Cu-C) = 1.8177(6) Å, r(C-C) = 1.2174(6) Å, and r(C-H) = 1.046(2) Å. The geometry suggests that CuCCH is primarily a covalent species with the copper atom singly bonded to the C≡C-H moiety. The copper quadrupole constant indicates that the bonding orbital of this atom may be sp hybridized. The DALAS technique promises to be fruitful in the study of other small, metal-containing molecules of chemical interest.

  18. Synthesis and characterization of novel Cu (II) complexes with 3-substituted-4-amino-5-mercapto-1,2,4-triazole Schiff bases: A new route to CuO nanoparticles

    NASA Astrophysics Data System (ADS)

    Aly, Hisham M.; Moustafa, Moustafa E.; Nassar, Moustafa Y.; Abdelrahman, Ehab A.

    2015-04-01

    Cu (II) complexes, were synthesized with newly derived biologically active 1,2,4-triazole Schiff bases. The Schiff bases were synthesized by condensation of 3-substituted-4-amino-5-mercapto-1,2,4-triazole with dibenzoylmethane. The synthesized compounds were characterized using elemental analysis, magnetic moment, thermal analysis and spectral tools (FT-IR, 1HNMR, ESR, and UV-Vis spectroscopy). All the synthesized complexes are nonelectrolytes in N,N-dimethylformamide. The synthesized Schiff bases and their Cu (II) complexes have been screened for antibacterial (Escherichia coli &Staphylococcus aureus) and antifungal (Aspergillus flavus &Candida albicans) activity using a modified Bauer-Kirby method. Interestingly, the synthesized Cu (II) complexes were used as precursors for CuO nanoparticles which were characterized using XRD, HR-TEM, FT-IR and UV-Vis spectroscopy. The photocatalytic activity of the prepared CuO nanoparticles was studied by performing the degradation of methylene blue dye under UV illumination in the presence of H2O2 and the results showed that the maximum percent of the degradation of methylene blue dye (MB) was found 96.18% after 360 min.

  19. 75 FR 34260 - Federal Acquisition Regulation; FAR Case 2005-040, Electronic Subcontracting Reporting System (eSRS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-16

    ... ensure that the Federal Procurement Data System-Next Generation (FPDS-NG), eSRS, and agency contract... Acquisition Regulation; FAR Case 2005-040, Electronic Subcontracting Reporting System (eSRS) AGENCIES... Electronic Subcontracting Reporting System (eSRS), rather than Standard Form 294 - Subcontract Report...

  20. Identification of nitrogen acceptor in Cu2O: First-principles study

    NASA Astrophysics Data System (ADS)

    T-Thienprasert, Jiraroj; Limpijumnong, Sukit

    2015-11-01

    The source of p-type carriers observed in nitrogen-doped Cu2O samples [Appl. Phys. Lett. 82, 1060 (2003)] was identified by using accurate hybrid density functional calculations. Similar to the case of ZnO, we found that N is a deep acceptor when substituting for O in Cu2O and cannot be the source of the observed p-type carriers. Detailed investigation of other N-related defects in Cu2O reveals that N2 substitution for Cu, i.e., (N2)Cu, is a shallow acceptor and can give hole carriers in N-doped Cu2O samples. (N2)Cu is not only a shallow acceptor but it also has a lower formation energy than NO in some growth conditions. The calculated emission photo luminescence (PL) peak at 1.89 eV associated with (N2)Cu is also in good agreement with the observed N-related PL peak at ˜1.82 eV in N-doped Cu2O sample. To aid future identification by Raman spectroscopy techniques, the vibrational frequencies of N2 on both Cu and O sites were calculated.

  1. Diffusion of two-dimensional Cu islets on Ag(111) studied with the Molecular Dynamics Method

    NASA Astrophysics Data System (ADS)

    Hayat, Sadar S.; Alcantara Ortigoza, Marisol; Rahman, Talat S.

    2009-03-01

    Our molecular dynamics simulations (at 300, 500 and 700 K) of the diffusion of two-dimensional Cun islets (1<=n<=9) on Ag(111) using many-body potentials yield an Arrhenius behavior. Concerted motion is seen to dominate the diffusion of smaller islets (2-4 atoms) whereas multiple-atom, shape-adjusting processes control the diffusion of the larger ones. Although the effective energy barrier scales with islet size, the barriers do not change considerably for islands containing 4 to 9 atoms (they are ˜ 220 ± 37 meV). While the diffusion barrier for Cu monomers on Ag(111) is higher than that on Cu(111) (both in experiment and theory), the situation reverses starting from the dimer. Our results for monomer and dimer are in excellent agreement with those extracted from experiments.^1 On comparing our results with those for Cu islets on Cu(111), we find that the comparatively large Ag-Ag bond-length sets the contrast between Cu monomer diffusion on Cu(111) and on Ag(111). The diffusivity of Cu dimer, however, is boosted on Ag(111) by the competition between optimizing the Cu-Cu and the Cu-Ag bonds. For larger islets (3-9 atoms) our results reveal several novel diffusion processes, including those in which an islet-atom climbs atop. ^1 Morgenstern et al. PRL93, 056102 (2005). Work supported by NSF-ITR 0428826.

  2. Ab initio study of subsurface diffusion of Cu on the H-passivated Si(001) surface

    NASA Astrophysics Data System (ADS)

    Rodriguez-Prieto, A.; Bowler, D. R.

    2009-10-01

    In this paper we use density-functional theory calculations to analyze both the stability and diffusion of Cu adatoms near and on the H-passivated Si(001) surface. Two different Cu sources are considered: depositing Cu from vacuum, and contaminating Cu outdiffusing from bulk Si. Deposited Cu from vacuum quickly moves subsurface to an interstitial site in the third Si layer (T2). Once there, Cu adatoms enter a subsurface zigzag migration route between T2 and another subsurface site, T2→HSL→T2 , along the dimer row direction. Contaminating Cu outdiffusing from bulk is found to be a fast diffuser along both parallel and perpendicular directions to the dimer row when far from the surface. It is attracted to the layers close to the surface and becomes trapped at an interstitial site located at the sixth Si layer (T3). As the outdiffusing Cu atoms get closer to the surface, a channeling zigzag diffusion along the dimer row direction, similar to that one followed by deposited Cu from vacuum, is favoured over diffusion along the perpendicular direction. These results are consistent with previous experimental work done on similar systems and will motivate further experiments on the interesting interaction between Cu and Si surfaces.

  3. Utilizing various test methods to study the stress corrosion behavior of Al-Li-Cu alloys

    NASA Technical Reports Server (NTRS)

    Pizzo, P. P.; Galvin, R. P.; Nelson, H. G.

    1984-01-01

    Recently, much attention has been given to aluminum-lithium alloys because of rather substantial specific-strength and specific-stiffness advantages offered over commercial 2000and 7000-series aluminum alloys. An obstacle to Al-Li alloy development has been inherent limited ductility. In order to obtain a more refined microstructure, powder metallurgy (P/M) has been employed in alloy development programs. As stress corrosion (SC) of high-strength aluminum alloys has been a major problem in the aircraft industry, the possibility of an employment of Al-Li alloys has been considered, taking into account a use of Al-Li-Cu alloys. Attention is given to a research program concerned with the evaluation of the relative SC resistance of two P/M processed Al-Li-Cu alloys. The behavior of the alloys, with and without an addition of magnesium, was studied with the aid of three test methods. The susceptibility to SC was found to depend on the microstructure of the alloys.

  4. Electronic properties of CuPc and H2Pc: an experimental and theoretical study.

    PubMed

    Nardi, Marco Vittorio; Detto, Francesca; Aversa, Lucrezia; Verucchi, Roberto; Salviati, Giancarlo; Iannotta, Salvatore; Casarin, Maurizio

    2013-08-21

    Phthalocyanine (H2Pc) and its open-shell copper complex (CuPc) deposited on amorphous gold films have been studied by combining the outcomes of several synchrotron based spectroscopic tools (X-ray photoelectron spectroscopy, UV photoelectron spectroscopy and near-edge X-ray absorption fine structure, NEXAFS, spectroscopy) with those of density functional theory (DFT) calculations. The assignment of experimental evidence has been guided by the results of DFT numerical experiments carried out on isolated molecules. With specific reference to CuPc NEXAFS data collected at the N K-edge, they have been assigned by using the open-shell time-dependent DFT (TDDFT) in the framework of the zeroth order regular approximation (ZORA) scalar relativistic approach. The agreement between theory and experiment has been found to be satisfactory, thus indicating that the open-shell TDDFT (F. Wang and T. Ziegler, Mol. Phys., 2004, 102, 2585) may be used with some confidence to look into the X-ray absorption spectroscopy results pertinent to transition metal complexes. As far as the metal-ligand interaction is concerned, the combined use of NEXAFS spectroscopy and DFT outcomes ultimately testified the significant ionic contribution characterizing the bonding between the metal centre and the nitrogen atoms of the phthalocyanine coordinative pocket.

  5. Carbon dioxide adsorption studies on delafossite CuFeO2 hydrothermally synthesized

    NASA Astrophysics Data System (ADS)

    Sarabia, M. A.; Rojas, S. D.; López-Cabaña, Z.; Villalba, R.; González, G.; Cabrera, A. L.

    2016-11-01

    Delafossite CuFeO2 oxide was synthesized by a hydrothermal technique using Cu2O and FeOOH as precursors with the addition of fused NaOH as mineralizer. The amount of rhombohedral and hexagonal delafossite phase formed depends on the synthesis time lapses between 2 and 5 days and on the NaOH concentration. The compounds obtained were analyzed with Raman Spectroscopy, X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) in order to obtain their morphological and structural properties. Optical behavior was studied by UV-vis Spectroscopy and gas adsorption measured with a Quartz-Crystal Microbalance (QCM). Our results show that this type of hydrothermal synthesis is capable of recreating the delafossite-type structure of copper-iron oxide and produces a high yield of material with the right stoichiometry. The highest uptake of carbon dioxide is observed on the sample with the highest ratio between rhombohedral and hexagonal delafossite phase.

  6. NMR Studies of Cu/zeolite SCR Catalysts Hydrothermally Aged with Urea

    SciTech Connect

    Cheng, Yisun; Hoard, John; Lambert, Christine; Kwak, Ja Hun; Peden, Charles HF

    2008-06-26

    The effects of hydrothermal aging of Cu/zeolite urea-SCR catalysts on their reactivity and material properties was assessed by performance tests and multiple characterization techniques that included 27Al NMR and XRD. Three aging protocols were used that consisted of varying temperature during hydrothermal aging with or without exposure to aqueous urea solution. Differences in behavior were even found for samples hydrothermally aged immediately following exposure to the urea solution or if the sample was dried overnight before hydrothermal aging. The combination of urea and high temperature exposure increased the deactivation of Cu/zeolite SCR catalysts beyond that observed by hydrothermal aging alone, with an immediate high temperature exposure following wetting of the catalyst core with aqueous urea causing the most significant deterioration in performance. The impact of urea on SCR catalyst durability was also found to increase with the aging temperature. NMR analysis suggested that aging with urea resulted in relatively more dealumination of the zeolite for the SCR catalysts in this study.

  7. The design of Cu-doped ZnO thermoelectric module (simulation study)

    NASA Astrophysics Data System (ADS)

    Hadi, Syamsul; Suratwan, Agus; Kurniawan, Agus; Budiana, Eko Prasetya; Suyitno

    2016-03-01

    The p-type semiconductor of Cu-doped ZnO-based thermoelectric material has already been synthesized and studied as an energy harvester. The next challenge is manufacturing the thermoelectric module in the development of thermoelectric as an eco-friendly material in the future. This research aims to investigate the effect of thermoelectric geometric design on the electrical output power and voltage and to recommend the most appropriate thermoelectric geometric design. The design of thermoelectric generator (TEG) includes the determinations of dimension (width, length, and height), number of modules, and semiconductor materials. The simulation used the coupled-field analysis of ANSYS APDL 14.5 in the steady state condition. The p- and n- type thermoelectric material used Cu-doped ZnO and Al-doped ZnO, respectively. The width of element and the number of thermoelectric module were varied to obtain a thermoelectric design, which produces the largest current, power, and voltage. The result of research shows that the t hermoelectric generator with the element widths of 0.94 mm, 1.125 mm, 1.05 mm, and 1.2 mm generates the largest power output and voltage, namely: 0.32 W and 0.89 V, 0.38 W and 0.98 V, 0.45 W and 1.06 V, and 0.52 W and 1.13 V, respectively.

  8. High-pressure thermoluminescence and photoluminescence study of ZnS:Mn:Cu:Cl phosphor

    SciTech Connect

    Lang, J.M.; Dreger, Z.A.; Drickamer, H.G. , Urbana, Illinois 61801 )

    1992-02-15

    The effect of pressure has been studied on the thermoluminescence and photoluminescence of a well-characterized sample of ZnS:Mn:Cu:Cl. The thermoluminescence was particularly revealing. Initially two traps were present. As they increased in depth with increasing pressure new shallower traps appeared. The pressure dependence of four traps was established. By comparison with pressure measurements on ZnS doped only with Mn{sup +2} and only with Cu{sup +} and Cl{sup {minus}}, we established that the deepest trap is associated with defects introduced by Mn{sup +2}, while the two traps next lower in energy are associated with defects introduced by Cl{sup {minus}}. The shallowest trap could not be assigned to a specific defect. The photoluminescence emission (from the {sup 4}{ital T}{sub 1}, to the {sup 6}{ital A}{sub 1} energy level of Mn{sup +2}) shifted to lower energy at a rate identical to that previously reported for a less well-characterized ZnS:Mn sample. The shift could be described quantitatively in terms of changes in the ligand field parameters.

  9. Study of polyaniline coated CuFe2O4 nanoparticles and their application in biosensor

    NASA Astrophysics Data System (ADS)

    Sharma, Uma Shankar; Shah, Rashmi

    2016-05-01

    Polyaniline coated with nanoferrite particles has attractive application in enzyme less biosensor. In this paper, we have reported the synthesis of copper ferrite by Chemical Coprecipitation method and polymerization of polyaniline by oxidation method. The polyaniline-ferrite composite was characterized by different techniques such as XRD and VSM. The XRD pattern confirmed the presence of cubic phase and particles size in nano scale. The magnetic properties were studied by vibrating sample magnetometer (VSM) technique at room temperature. The higher values of saturation magnetization attributed to the cation distribution change from normal to spinel structure. Some Fe3+ ions drifted from octahedral site to tetrahedral site through the conversion of some Fe2+ ions to Fe3+ ions with super-exchange interactions and gives rise to saturation magnetization. The saturation magnetization of polyaniline coated CuFe2O4 using ammonium nitrate is much less than by polyaniline coated CuFe2O4 using ammonium peroxidisulphate. The saturation magnetization Ms of the nanocomposite is dependent on the volume fraction of the magnetic ferrite particles and on the contribution of the non-magnetic polyaniline coated layer. Polyaniline worked as an immobilization layer in the enzyme less biosensor because enzyme less biosensor is not affected by environmental factor.

  10. Has NHS reorganisation saved lives? A CuSum study using 65 years of data

    PubMed Central

    Lale, Alice S

    2016-01-01

    Objectives To determine if NHS reforms affect population mortality. Design Retrospective study using routinely published data. Setting & participants Resident population of England and Wales 1948 to 2012 Main outcome measure All cause age sex directly standardised mortality England and Wales 1948 to 2012. Methods Using the CuSum technique and Change-Point Analysis to identify sustained changes in the improving age-standardised mortality rates for the period 1948-2012, and comparing the time of these changes with periods of NHS reform. Where observed changes did not fit with NHS reform, changes external to the NHS were sought as a possible explanation of changes observed. Results CuSum plotting and CPA showed no significant changes in female mortality trend between 1948 and 2012. However, this analysis identified a sustained improvement in the male mortality trend, occurring in the mid-1970s. A further change in the rate of male mortality decline was found around the Millennium. Conclusion The 1974 NHS reorganisation, changing service arrangements predominantly for women and children, is considered an unlikely explanation of the improved rate of male mortality decline. Thus, centrally led NHS reorganisation has never had any detectable effect on either male or female mortality and must be considered ineffective for this purpose. But some evidence supporting the view that increased funding improves outcomes is found. PMID:26432817

  11. Preparation, structural, photoluminescence and magnetic studies of Cu doped ZnO nanoparticles co-doped with Ni by sol-gel method

    NASA Astrophysics Data System (ADS)

    Theyvaraju, D.; Muthukumaran, S.

    2015-11-01

    Zn0.96-xNi0.04CuxO nanoparticles have been synthesized by varying different Cu concentrations between 0% and 4% using simple sol-gel method. X-ray diffraction studies confirmed the hexagonal structure of the prepared samples. The formation of secondary phases, CuO (111) and Zn (101) at higher Cu content is due un-reacted Cu2+ and Zn2+ ions present in the solution which reduces the interaction between precursor ions and surfaces of ZnO. Well agglomerated and rod-like structure noticed at Cu=4% greatly de-generate and enhanced the particle size. The nominal elemental composition of Zn, Cu, Ni and O was confirmed by energy dispersive X-ray analysis. Even though energy gap was increased (blue-shift) from Cu=0-2% by quantum size effect, the s-d and p-d exchange interactions between the band electrons of ZnO and localized d electrons of Cu and Ni led to decrease (red-shift) the energy gap at Cu=4%. Presence of Zn-Ni-Cu-O bond was confirmed by Fourier transform infrared analysis. Ultraviolet emission by band to band electronic transition and defect related blue emission were discussed by photoluminescence spectra. The observed optical properties concluded that the doping of Cu in the present system is useful to tune the emission wavelength and hence acting as the important candidates for the optoelectronic device applications. Ferromagnetic ordering of Cu=2% sample was enhanced by charge carrier concentration where as the antiferromagnetic interaction between neighboring Cu-Cu ions suppressed the ferromagnetism at higher doping concentrations of Cu.

  12. ESR and TL mechanism in CaSO4 : Ag co-doped phosphors

    NASA Astrophysics Data System (ADS)

    Dhabekar, Bhushan; Menon, Sanjeev; Alagu Raja, E.; Sanaye, S. S.; Gundu Rao, T. K.; Bhatt, B. C.; Kher, R. K.

    2006-06-01

    Thermoluminescence (TL) studies have been carried out on CaSO4 : Mn, CaSO4 : Ag,Mn, CaSO4 : Ag,Nd, CaSO4 : Ag,Mn,Nd, CaSO4 : Ag,Zr and CaSO4 : Ag,Mn,Zr phosphors. It is found that TL at 360 °C in CaSO4 : Ag,Mn,Nd is about 40 times that of CaSO4 : Ag,Mn and about 170 times that of CaSO4 : Ag,Nd. This shows that the presence of an efficient luminescent centre (Mn2+) as well as a trivalent impurity (such as Nd3+ or Y3+) is important for enhancement of TL at 360 °C in the CaSO4 : Ag,Mn,Nd phosphor system. Electron spin resonance (ESR) studies show that the peak at 360 °C correlates with an Ag2+ centre formed due to γ-irradiation and observable only below -170 °C. The Ag2+ centre is characterized by an axial g-tensor with principal values g|| = 2.38 and gbottom = 2.41. ESR studies further indicate that the precursor to a centre observable at low temperature (-170 °C) appears to act as the recombination centre for the TL peak at 360 °C. The low temperature centre is characterized by the g-values g|| = 2.0023 and gbottom = 2.0038 and is assigned to the SO_{3}^{ - } radical.

  13. Validation of associations between ESR1 variants and breast cancer risk in Chinese cohorts.

    PubMed

    Li, X; Yao, G Y; Li, F X; Qiu, Y R; Yang, X X

    2016-01-01

    Estrogen receptor-a (ER) protein plays a key role in breast carcinogenesis, and common genetic variants in the corresponding gene locus have been associated with breast cancer risk in different populations. Here, we analyzed estrogen receptor 1 (ESR1) associations in two hospital-based studies of patients from the south of China. Three single-nucleotide polymorphisms (SNPs; rs3757318, rs2046210, and rs3734805) in ESR1 were selected from previous genome-wide association study results and were genotyped using the Sequenom MassARRAY® iPLEX System in 845 breast cancer patients and 882 healthy controls. Association analysis based on unconditional logistic regression was carried out to determine the odds ratio (OR) and 95% confidence interval (95%CI) for each SNP. Stratified analyses according to the status of ER and progesterone receptor (PR) were also performed. Of the three SNPs, rs3757318 did not pass the Hardy-Weinberg equilibrium test and was excluded from the subsequent analysis. The other two SNPs (rs2046210 and rs3734805) were strongly associated with susceptibility to breast cancer. Allele T of rs2046210 and allele C of rs3734805 were risk alleles and the adjusted ORs were 1.348 (95%CI = 1.172-1.550, P = 0.0001) and 1.319 (95%CI = 1.144-1.522, P = 0.0001), respectively. Furthermore, the risk allele of rs2046210 gave negative results for ER and PR expression in an immunohistochemical test, with ORs of 0.602 (95%CI = 0.384-0.944, P = 0.027) and 0.532 (95%CI = 0.338-0.837, P = 0.006), respectively. Our study further supports associations between rs2046210 and rs3734805 and breast cancer risk in Chinese women. PMID:27525837

  14. Transport and Cu NMR studies of charge and spin dynamics in PrBa{sub 2}Cu{sub 4}O{sub 8}

    SciTech Connect

    Kikuchi, Jun; Terasaki, Ichiro; Machi, Takato; Seiji, Nobuaki

    1996-11-01

    The charge and spin dynamics in PrBa{sub 2}Cu{sub 4}O{sub 8} are investigated by means of transport and Cu NMR measurements. The magnetoresistance was found to be very small at high temperatures and increase rapidly with decreasing temperature below {approximately}100 K, which may be ascribed to the dimensional crossover from one to two dimensions in the charge transport in the CuO double chains. While the NMR signal from the chain Cu sites persists down to 4.2 K without any appreciable line broadening, the signal from the planar Cu sites disappears below {approximately}250 K indicating the long-range antiferromagnetic order of plane Cu moments. This is consistent with the view of metallic conduction along the quasi one-dimensional CuO chains.

  15. Multi-frequency EPR evidence for a binuclear CuA center in cytochrome c oxidase: studies with a 63Cu- and 65Cu-enriched, soluble domain of the cytochrome ba3 subunit II from Thermus thermophilus.

    PubMed

    Fee, J A; Sanders, D; Slutter, C E; Doan, P E; Aasa, R; Karpefors, M; Vänngård, T

    1995-07-01

    We have recorded multi-frequency EPR spectra of 63Cu- and 65Cu-labeled, water-soluble CuA-protein from the cytochrome ba3 of T. thermophilus. The spectrum taken at the highest frequency (34.03 GHz) shows no hyperfine structure and is nominally axial with apparent gz approximately 2.18 and gxy approximately 2.00. The spectrum taken at the lowest frequency (3.93 GHz) shows a rich hyperfine structure. Analyses of the spectra show that the observed splitting arises from an interaction of the unpaired electron with two Cu nuclei and support the notion that CuA is a mixed-valent [Cu(II)/Cu(I)] complex in which the unpaired electronic spin is distributed evenly over the two Cu ions.

  16. Study of single crystal CuInSe2 thin films and CuGaSe2/CuInSe2 single quantum well grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Thiru, Sathiabama; Asakawa, Masaki; Honda, Kazuki; Kawaharazuka, Atsushi; Tackeuchi, Atsushi; Makimoto, Toshiki; Horikoshi, Yoshiji

    2015-09-01

    High quality CuGaSe2 and CuInSe2 single crystalline layers are grown on GaAs (001) by employing the deposition sequence of migration enhanced epitaxy using a solid source molecular beam epitaxy system. When CuGaSe2 is grown on CuInSe2 at moderate temperatures, severe interdiffusion takes place at the heterojunction of CuGaSe2/CuInSe2. This problem has been solved by optimizing the growth temperature and deposition rates of the constituent elements. Thus, we have successfully grown CuGaSe2/CuInSe2 single quantum well with sharp interfaces on GaAs (001) for the first time. Intense photoluminescence from the single quantum well with 10 nm well width is demonstrated.

  17. Microstructure study of pinning sites of highly (0001) textured Sm(Co,Cu){sub 5} thin films grown on Ru underlayer

    SciTech Connect

    Zhao Haibao; Wang Hao; Liu Xiaoqi; Wang Jianping

    2012-04-01

    In this paper, microstructure study of pinning sites of highly (0001) textured Sm(Co,Cu){sub 5} thin films was presented. Various types of pinning sites were identified, such as voids, grain/matrix boundaries (or crystalline/amorphous boundaries), grain boundaries between crystalline grains, and composition inhomogeneity in grains. One key finding of TEM elemental mapping was that Cu atoms were rich in the inner part of Sm(Co,Cu){sub 5} grains (defined by Sm and Co concentrations), instead of the outer part of grains, such as grain boundaries. Cu served as an alloying element in Sm(Co,Cu){sub 5} grains, not as a doping element to form Cu-rich grain boundaries. A model of Sm(Co,Cu){sub 5} films with lateral graded anisotropy due to composition/crystallization variation can explain the huge difference between the H{sub C} and H{sub K}.

  18. Pulse studies to decipher the role of surface morphology in CuO/CeO₂ nanocatalysts for the water gas shift reaction

    DOE PAGESBeta

    Rodriguez, Jose A.; Zhao, Fuzhen; Liu, Zongyuan; Xu, Wenqian; Yao, Siyu; Si, Rui; Johnston-Peck, Aaron C.; Martinez-Arias, Arturo; Hanson, Jonathan C.; Senanayake, Sanjaya D.

    2015-01-23

    The water-gas shift reaction (WGS, CO + H₂O → CO₂) was studied over CuO/CeO₂ catalysts with two different ceria particle morphohologies, in the form of nanospheres (ns) and nanocubes (nc). To understand the strong dependence of the WGS reaction activity on the ceria nanoshapes, pulses of CO (without and with water vapor) were employed during in situ X-ray diffraction (XRD) and X-ray absoprtion near edge structure (XANES) measurements done to characterize the catalysts. The results showed that CuO/CeO₂ (ns) exhibited a substantially better activity than CuO/CeO₂ (nc). The higher activity was associated with the unique properties of CuO/CeO₂ (ns), suchmore » as the easier reduction of highly dispersed CuO to metallic Cu, the stability of metallic Cu and a larger concentration Ce³⁺ in CeO₂ (ns).« less

  19. Pulse studies to decipher the role of surface morphology in CuO/CeO₂ nanocatalysts for the water gas shift reaction

    SciTech Connect

    Rodriguez, Jose A.; Zhao, Fuzhen; Liu, Zongyuan; Xu, Wenqian; Yao, Siyu; Si, Rui; Johnston-Peck, Aaron C.; Martinez-Arias, Arturo; Hanson, Jonathan C.; Senanayake, Sanjaya D.

    2015-01-23

    The water-gas shift reaction (WGS, CO + H₂O → CO₂) was studied over CuO/CeO₂ catalysts with two different ceria particle morphohologies, in the form of nanospheres (ns) and nanocubes (nc). To understand the strong dependence of the WGS reaction activity on the ceria nanoshapes, pulses of CO (without and with water vapor) were employed during in situ X-ray diffraction (XRD) and X-ray absoprtion near edge structure (XANES) measurements done to characterize the catalysts. The results showed that CuO/CeO₂ (ns) exhibited a substantially better activity than CuO/CeO₂ (nc). The higher activity was associated with the unique properties of CuO/CeO₂ (ns), such as the easier reduction of highly dispersed CuO to metallic Cu, the stability of metallic Cu and a larger concentration Ce³⁺ in CeO₂ (ns).

  20. Schottky Mass Spectrometry at the ESR with a new data acquisition system

    SciTech Connect

    Falch, M.; Loebner, K.E.G.; Kerscher, Th.; Attallah, F.; Bosch, F.; Franzke, B.; Geissel, H.; Hausmann, M.; Klepper, O.; Kluge, H.; Kozhuharov, C.; Muenzenberg, G.; Nolden, F.; Novikov, Y.; Patyk, Z.; Radon, T.; Scheidenberger, C.; Steck, M.; Winkler, M.; Wollnik, H.

    2000-12-31

    Schottky Mass Spectrometry turned out to be an excellent tool for systematic nuclear mass measurements. The newly developed data acquisition system, which yields several advantages for the data analysis, was used for the first time in Nov. 1997. Instead of online Fourier transformation as in former measurements, the signal is now digitized with a sampling rate of 640 kHz (16-bit resolution) and stored as time-captures. With a continuous data rate of 1.2 MB/s nearly 1 TB of raw data were stored. The Fast Fourier Transformation offline analysis allows the study of the dynamical behavior of the stored ions in the ESR including cooling forces and decay. The new spectra contain enough reference nuclei to determine the deviations from the constant momentum compaction factor {alpha}{sub p}.