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Sample records for rb cs phase

  1. The superconducting phase and electronic excitations of (Rb,Cs) Fe 2 As 2

    NASA Astrophysics Data System (ADS)

    Kanter, J.; Shermadini, Z.; Khasanov, R.; Amato, A.; Bukowski, Z.; Batlogg, B.

    2011-03-01

    We present specific heat, transport and Muon-Spin Rotation (μ SR) results on (Rb,Cs) Fe 2 As 2 . RbFe 2 As 2 was only recently found to be superconducting below 2.6 K by Bukowski et al. Compared to the related BaFe 2 As 2 the electron density is lower and no magnetic order is observed. For the superconducting phase the superfluid density was calculated from μ SR data. The temperature dependence of the superfluid density and the magnetic penetration depth is well described by a multi-gap scenario. In addition the electronic contribution the specific heat was studied for different compositions and magnetic fields and reveals a high value for the Sommerfeld coefficient γ .

  2. Vibrational investigation and phase transitions in the KMnF3 doped perovskite crystals (Li+, Na+, Rb+ and Cs+)

    NASA Astrophysics Data System (ADS)

    Kapusta, J.; Daniel, Ph; Ratuszna, A.

    2002-06-01

    The influence of substitution of Li+, Na+, Rb+ and Cs+ ions in the archetype KMnF3 perovskite crystal was studied by the Raman method. The Raman spectra of (K1-xAx)MnF3 mixed crystals (x≤0.15) were recorded in the range between 30 and 300 K and interpreted in terms of a `one-mode' behaviour. Attention was paid to evidence of the static and dynamical disorder. From this point of view the behaviour of hard Raman modes versus temperature has been studied together with two unexpected broad Raman bands in the normally inactive ideal cubic phase. The existence of these two broad peaks in the theoretically inactive cubic phase and also the persistence of the hard Raman modes of the tetragonal phase in cubic symmetry suggest the existence of a large structural disorder far above the cubic-to-tetragonal phase transition. The results of Raman investigations are discussed in the more general framework of structural disorder in perovskite systems.

  3. Comparative Raman spectroscopic study of phase stability and anharmonic effects in AZr2(PO4)3 (A=K, Rb and Cs).

    PubMed

    Kamali, K; Ravindran, T R; Ravi, C

    2016-02-15

    AZr2(PO4)3 (A=Na, K, Rb, Cs) are a set of framework structured compounds that exhibit tunable ultralow thermal expansion over the wide temperature range of 293-1273K. We report a systematic Raman spectroscopic investigation on AZr2(PO4)3 (A=K, Rb and Cs) compounds as a function of temperature in the range 80-860K and pressures of up to 32GPa. To get insight into the thermal expansion property, phonon anharmonicity has been investigated by studying the temperature and pressure dependence of Raman peak shifts and line widths and computed bulk modulus. We have compared the phase transition and amorphization pressures of the various members of AZr2(PO4)3 to account for the stability of the ambient rhombohedral phase. We find that unlike most of the anomalous thermal expansion materials, in AZr2(PO4)3 (A=K, Rb and Cs), the phonons that are anharmonic with temperature do not necessarily exhibit anharmonicity with pressure.

  4. High-resolution {sup 13}C nuclear magnetic resonance evidence of phase transition of Rb,Cs-intercalated single-walled nanotubes

    SciTech Connect

    Bouhrara, M.; Saih, Y.; Waagberg, T.; Goze-Bac, C.; Abou-Hamad, E.

    2011-09-01

    We present 13 C high-resolution magic-angle-turning (MAT) and magic angle spinning nuclear magnetic resonance data of Cs and Rb intercalated single walled carbon nanotubes. We find two distinct phases at different intercalation levels. A simple charge transfer is applicable at low intercalation level. The new phase at high intercalation level is accompanied by a hybridization of alkali (s) orbitals with the carbon (sp2) orbitals of the single walled nanotubes, which indicate bundle surface sites is the most probable alkali site.

  5. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

    NASA Astrophysics Data System (ADS)

    François, B.; Calosso, C. E.; Abdel Hafiz, M.; Micalizio, S.; Boudot, R.

    2015-09-01

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be -109 and -141 dB rad2/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is -105 and -138 dB rad2/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10-14 for the Cs cell clock and 2 × 10-14 for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10-15 level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  6. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

    SciTech Connect

    François, B.; Calosso, C. E.; Micalizio, S.; Abdel Hafiz, M.; Boudot, R.

    2015-09-15

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be −109 and −141 dB rad{sup 2}/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is −105 and −138 dB rad{sup 2}/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10{sup −14} for the Cs cell clock and 2 × 10{sup −14} for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10{sup −15} level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  7. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks.

    PubMed

    François, B; Calosso, C E; Abdel Hafiz, M; Micalizio, S; Boudot, R

    2015-09-01

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be -109 and -141 dB rad(2)/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is -105 and -138 dB rad(2)/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10(-14) for the Cs cell clock and 2 × 10(-14) for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10(-15) level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  8. Crystal structures and topological aspects of the high-temperature phases and decomposition products of the alkali-metal oxalates M2[C2O4] (M=K, Rb, Cs).

    PubMed

    Dinnebier, Robert E; Vensky, Sascha; Jansen, Martin; Hanson, Jonathan C

    2005-02-04

    The high-temperature phases of the alkali-metal oxalates M2[C2O4] (M = K, Rb, Cs), and their decomposition products M2[CO3] (M = K, Rb, Cs), were investigated by fast, angle-dispersive X-ray powder diffraction with an image-plate detector, and also by simultaneous differential thermal analysis (DTA)/thermogravimetric analysis (TGA)/mass spectrometry (MS) and differential scanning calorimetry (DSC) techniques. The following phases, in order of decreasing temperature, were observed and crystallographically characterized (an asterisk denotes a previously unknown modification): *alpha-K2[C2O4], *alpha-Rb2[C2O4], *alpha-Cs2[C2O4], alpha-K2[CO3], *alpha-Rb2[CO3], and *alpha-Cs2[CO3] in space group P6(3)/mmc; *beta-Rb2[C2O4], *beta-Cs2[C2O4], *beta-Rb2[CO3], and *beta-Cs2[CO3] in Pnma; gamma-Rb2[C2O4], gamma-Cs[C2O4], gamma-Rb2[CO3], and gamma-Cs2[CO3] in P2(1)/c; and delta-K2[C2O4] and delta-Rb2[C2O4] in Pbam. With respect to the centers of gravity of the oxalate and carbonate anions, respectively, the crystal structures of all known alkali-metal oxalates and carbonates belong to the AlB2 family, and adopt either the AlB2 or the Ni2In arrangement depending on the size of the cation and the temperature. Despite the different sizes and constitutions of the carbonate and oxalate anions, the high-temperature phases of the alkali-metal carbonates M2[CO3] (M = K, Rb, Cs), exhibit the same sequence of basic structures as the corresponding alkali-metal oxalates. The topological aspects and order-disorder phenomena at elevated temperature are discussed.

  9. Half metallic ferromagnetism in alkali metal nitrides MN (M = Rb, Cs): A first principles study

    SciTech Connect

    Murugan, A. Rajeswarapalanichamy, R. Santhosh, M. Sudhapriyanga, G.; Kanagaprabha, S.

    2014-04-24

    The structural, electronic and elastic properties of two alkali metal nitrides (MN: M= Rb, Cs) are investigated by the first principles calculations based on density functional theory using the Vienna ab-initio simulation package. At ambient pressure the two nitrides are stable in ferromagnetic state with CsCl structure. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that these materials are half metallic in nature. A pressure-induced structural phase transition from CsCl to ZB phase is observed in RbN and CsN.

  10. Measurements of the ground-state polarizabilities of Cs, Rb, and K using atom interferometry

    NASA Astrophysics Data System (ADS)

    Gregoire, Maxwell D.; Hromada, Ivan; Holmgren, William F.; Trubko, Raisa; Cronin, Alexander D.

    2015-11-01

    We measured the ground-state static electric-dipole polarizabilities of Cs, Rb, and K atoms using a three-nanograting Mach-Zehnder atom beam interferometer. Our measurements provide benchmark tests for atomic structure calculations and thus test the underlying theory used to interpret atomic parity-nonconservation experiments. We measured αCs=4 π ɛ0×59.39 (9 ) Å3,αRb=4 π ɛ0×47.39 (8 ) Å3 , and αK=4 π ɛ0×42.93 (7 ) Å3 . In atomic units, these measurements are αCs=401.2 (7 ) ,αRb=320.1 (6 ) , and αK=290.0 (5 ) . We report ratios of polarizabilities αCs/αRb=1.2532 (10 ) ,αCs/αK=1.3834 (9 ) , and αRb/αK=1.1040 (9 ) with smaller fractional uncertainty because the systematic errors for individual measurements are largely correlated. Since Cs atom beams have short de Broglie wavelengths, we developed measurement methods that do not require resolved atom diffraction. Specifically, we used phase choppers to measure atomic beam velocity distributions, and we used electric field gradients to give the atom interference pattern a phase shift that depends on atomic polarizability.

  11. Pressure induced structural transitions in KH, RbH, and CsH

    NASA Astrophysics Data System (ADS)

    Hooper, James; Baettig, Pio; Zurek, Eva

    2012-06-01

    The heavier alkali metal hydrides MH (M = K, Rb, Cs) undergo a series of pressure induced structural phase transitions: B1 (NaCl) → B2 (CsCl) → CrB. Experiments reveal that the latter occurs at 85 and 17.5 GPa for RbH and CsH, but it has not yet been observed for KH. Herein, evolutionary algorithms coupled with density functional theory calculations are employed to explore the potential energy surface of the aforementioned hydrides up to pressures of 300 GPa. The computations support previous theoretical work which predicts that KH will adopt the CrB structure when compressed. In addition, for KH and RbH we find configurations with Pnma and I41/amd symmetry that are thermodynamically competitive with the CrB structure at 300 GPa. Between 100-150 GPa, a Pnma structure which is analogous to a high-pressure form of CsI is found to be the most stable phase for the heaviest alkali hydride considered. At higher pressures a hitherto unknown CsH-P63/mmc arrangement becomes thermodynamically preferred up to at least 400 GPa. A detailed analysis of the geometric and electronic structures of the various phases is provided.

  12. Elastic scattering of electrons from Rb, Cs and Fr atoms

    NASA Astrophysics Data System (ADS)

    Gangwar, R. K.; Tripathi, A. N.; Sharma, L.; Srivastava, R.

    2010-04-01

    Differential, integrated elastic, momentum-transfer and total cross sections as well as differential S, T and U spin parameters for scattering of electrons from rubidium, caesium and francium atoms in the incident energy range up to 300 eV are calculated using a relativistic Dirac equation. The projectile electron-target atom interaction is represented by both real and complex parameter-free optical potentials for obtaining the solution of a Dirac equation for scattered electrons. The Dirac-Fock wavefunctions have been used to represent the Rb, Cs and Fr target atoms. The results of differential cross sections and spin asymmetry parameter S for e-Rb and e-Cs have been compared with the available experimental and theoretical results. Detailed results are reported for the elastic scattering of electrons from the ground states of a francium atom for the first time in the wide range of incident electron energies. The results of electron-Fr elastic scattering show the similar features to those obtained in the case of e-Rb and e-Cs elastic scattering.

  13. Insights into the structures of the gas-phase hydrated cations M⁺(H₂O)(n)Ar (M = Li, Na, K, Rb, and Cs; n = 3-5) using infrared photodissociation spectroscopy and thermodynamic analysis.

    PubMed

    Ke, Haochen; van der Linde, Christian; Lisy, James M

    2015-03-12

    The hydration of alkali cations yields a variety of structural conformers with varying numbers of water molecules in the first solvation shell. How these ions move from the aqueous phase into biological systems, such as at the entrance of an ion channel, depends on the interplay between competing intermolecular forces, which first must involve ion-water and water-water interactions. New infrared action spectra, using argon as a messenger or "spy", for Li(+), Na(+), and K(+), with up to five water molecules are reported, and new structural conformers determined from ab initio calculations, combined with previous results on Rb(+) and Cs(+), have identified structural transitions at each hydration level. These transitions are a result of the delicate balance between competing noncovalent interactions and represent a quantitative microscopic view of the macroscopic enthalpy-entropy competition between energy and structural variety. Smaller cations (Li(+) and Na(+)), with higher charge density, yield structural configurations with extended linear networks of hydrogen bonds. Larger cations (Rb(+) and Cs(+)), with lower charge density, generate configurations with cyclic hydrogen-bonded water subunits. It appears that K(+) is somewhat unique, with very simple (and predominantly) single structural conformers. This has led to the suggestion that K(+) can "move" easily in or through biological systems, concealing its identity as an ion, under the "appearance" or disguise of a water molecule.

  14. Electron Impact Ionization Cross Sections in Rb and Cs.

    NASA Astrophysics Data System (ADS)

    Reddish, T. J.; Lukomski, M.; Sutton, S.; Kedzierski, W.; McConkey, J. W.; Bartschat, K.; Bartlett, P. L.; Stelbovics, A. T.; Bray, I.

    2006-05-01

    We present a new atom trapping technique for determining absolute, total ionisation cross sections (TICS) out of an excited atom. The novel feature of this method is in utilizing Doppler cooling of neutral atoms to determine ionisation cross sections. This fluorescence-monitoring experiment, which is a variant of the `trap loss' technique, has enabled us to obtain the experimental electron impact ionisation cross sections out of the Cs 6^2P3/2 excited state between 7 - 400 eV. New CCC, R-Matrix with Pseudo-States (RMPS), and Born approximation single ionisation cross sections (SICS) are also presented for both the ground and excited states of Cs and Rb, and compared with the available experimental data. The comparison of the results reveals the importance of the autoionisation and multiple ionisation contributions to the TICS. The autoionisation contribution appears to be substantial for ionisation out of the Cs 6^2P and Rb 5^2P excited states; ˜ 3-4 larger than the direct ionisation contribution predicted by CCC at ˜ 30-50 eV. This surprising result shows the importance of multi-electron processes in determining the ionisation cross sections of heavy alkali atoms.

  15. Investigation of substitution effects and the phase transition in type-I clathrates Rb{sub x}Cs{sub 8-x}Sn{sub 44}square{sub 2} (1.3<=x<=2.1) using single-crystal X-ray diffraction, Raman spectroscopy, heat capacity and electrical resistivity measurements

    SciTech Connect

    Kaltzoglou, Andreas; Faessler, Thomas F.; Gold, Christian; Scheidt, Ernst-Wilhelm; Scherer, Wolfgang; Kume, Tetsuji; Shimizu, Hiroyasu

    2009-10-15

    The substitution of cations in Rb{sub x}Cs{sub 8-x}Sn{sub 44}square{sub 2}(1.3<=x<=2.1) is reported. The compounds crystallize at room temperature in the space group la3-bard adopting the type-I clathrate 2x2x2 superstructure with partly ordered framework vacancies (square), whereas at higher temperatures they transform to the primitive, more disordered modification (space group Pm3-barn). The guest atom distributions in the Sn cages on the Rb: Cs ratios is studied by means of single-crystal X-ray diffraction for Rb{sub 2.1(1)}Cs{sub 5.8(1)}Sn{sub 44} at T=293 K (1), Rb{sub 1.42(8)}Cs{sub 6.58(8)}Sn{sub 44} at T=293 K (2a), Rb{sub 1.46(5)}Cs{sub 6.54(5)}Sn{sub 44} at T=373 K (2b) and Rb{sub 1.32(8)}Cs{sub 6.68(8)}Sn{sub 44} at T=293 K (3). The structural order-disorder phase transition influences the electrical resistivity. The hysteresis observed for the electrical resistivity in combination with the symmetric shape of the specific heat anomaly suggests that the transformation is of first-order type and is characterized by an entropy change of about 2.5 J mol{sup -1} K{sup -1}. The Raman spectrum for the low-temperature modification of 2 is also reported. - Graphical Abstract: The effects of substitution of cations in the type-I clathrates Rb{sub x}Cs{sub 8-x}Sn{sub 44} (1.3<=x<=2.1) are reported. The distribution of the guests in the Sn cages under different reaction stoichiometries and annealing times is studied by X-ray diffraction. A structural phase transition in Rb{sub 1.4}Cs{sub 6.6}Sn{sub 44} at 333-363 K affects significantly the electrical resistivity and heat capacity.

  16. Insights into gas-phase structural conformers of hydrated rubidium and cesium cations, M(+)(H2O)(n)Ar (M = Rb, Cs; n = 3-5), using infrared photodissociation spectroscopy.

    PubMed

    Ke, Haochen; van der Linde, Christian; Lisy, James M

    2014-02-27

    Infrared photodissociation (IRPD) spectra of M(+)(H2O)nAr (M = Rb, Cs; n = 3-5) with simultaneous monitoring of [Ar] and [Ar+H2O] fragmentation channels are reported. The comparison between the spectral features in the two channels and corresponding energy analysis provide spectral assignments of the stable structural conformers and insight into the competition between ion-water electrostatic and water-water hydrogen bonding interactions. Results show that as the level of hydration increases, the water-water interaction exhibits the tendency to dominate over the ion-water interaction. Cyclic water tetramer and water pentamer substructures appear in Cs(+)(H2O)4Ar and Cs(+)(H2O)5Ar systems, respectively. However, cyclic water tetramer and pentamer structures were not observed for Rb(+)(H2O)4Ar and Rb(+)(H2O)5Ar systems, respectively, due to the stronger influence of the rubidium ion-water electrostatic interaction. The energy analysis, including the available internal energy and the IR photon energy, helped provide an experimental estimate of water binding energies.

  17. Cation ordering and effect of biaxial strain in double perovskite CsRbCaZnCl{sub 6}

    SciTech Connect

    Pilania, G. Uberuaga, B. P.

    2015-03-21

    Here, we investigate the electronic structure, energetics of cation ordering, and effect of biaxial strain on double perovskite CsRbCaZnCl{sub 6} using first-principles calculations based on density functional theory. The two constituents (i.e., CsCaCl{sub 3} and RbZnCl{sub 3}) forming the double perovskite exhibit a stark contrast. While CsCaCl{sub 3} is known to exist in a cubic perovskite structure and does not show any epitaxial strain induced phase transitions within an experimentally accessible range of compressive strains, RbZnCl{sub 3} is thermodynamically unstable in the perovskite phase and exhibits ultra-sensitive response at small epitaxial strains if constrained in the perovskite phase. We show that combining the two compositions in a double perovskite structure not only improves overall stability but also the strain-polarization coupling of the material. Our calculations predict a ground state with P4/nmm space group for the double perovskite, where A-site cations (i.e., Cs and Rb) are layer-ordered and B-site cations (i.e., Ca and Zn) prefer a rocksalt type ordering. The electronic structure and bandgap in this system are shown to be quite sensitive to the B-site cation ordering and is minimally affected by the ordering of A-site cations. We find that at experimentally accessible compressive strains CsRbCaZnCl{sub 6} can be phase transformed from its paraelectric ground state to an antiferroelectric state, where Zn atoms contribute predominantly to the polarization. Furthermore, both energy difference and activation barrier for a transformation between this antiferroelectric state and the corresponding ferroelectric configuration are predicted to be small. The computational approach presented here opens a new pathway towards a rational design of novel double perovskites with improved strain response and functionalities.

  18. Cation ordering and effect of biaxial strain in double perovskite CsRbCaZnCl6

    SciTech Connect

    Pilania, G.; Uberuaga, B. P.

    2015-03-19

    Here, we investigate the electronic structure, energetics of cation ordering, and effect of biaxial strain on double perovskite CsRbCaZnCl6 using first-principles calculations based on density functional theory. The two constituents (i.e., CsCaCl3 and RbZnCl3) forming the double perovskite exhibit a stark contrast. While CsCaCl3 is known to exist in a cubic perovskite structure and does not show any epitaxial strain induced phase transitions within an experimentally accessible range of compressive strains, RbZnCl3 is thermodynamically unstable in the perovskite phase and exhibits ultra-sensitive response at small epitaxial strains if constrained in the perovskite phase. We show that combining the two compositions in a double perovskite structure not only improves overall stability but also the strain-polarization coupling of the material. Our calculations predict a ground state with P4/nmm space group for the double perovskite, where A-site cations (i.e., Cs and Rb) are layer-ordered and B-site cations (i.e., Ca and Zn) prefer a rocksalt type ordering. The electronic structure and bandgap in this system are shown to be quite sensitive to the B-site cation ordering and is minimally affected by the ordering of A-site cations. We find that at experimentally accessible compressive strains CsRbCaZnCl6 can be phase transformed from its paraelectric ground state to an antiferroelectric state, where Zn atoms contribute predominantly to the polarization. Furthermore, both energy difference and activation barrier for a transformation between this antiferroelectric state and the corresponding ferroelectric configuration are predicted to be small. As a result, the computational approach presented here opens a new pathway towards a rational design of novel double perovskites with improved strain response and functionalities.

  19. Cation ordering and effect of biaxial strain in double perovskite CsRbCaZnCl6

    DOE PAGES

    Pilania, G.; Uberuaga, B. P.

    2015-03-19

    Here, we investigate the electronic structure, energetics of cation ordering, and effect of biaxial strain on double perovskite CsRbCaZnCl6 using first-principles calculations based on density functional theory. The two constituents (i.e., CsCaCl3 and RbZnCl3) forming the double perovskite exhibit a stark contrast. While CsCaCl3 is known to exist in a cubic perovskite structure and does not show any epitaxial strain induced phase transitions within an experimentally accessible range of compressive strains, RbZnCl3 is thermodynamically unstable in the perovskite phase and exhibits ultra-sensitive response at small epitaxial strains if constrained in the perovskite phase. We show that combining the two compositionsmore » in a double perovskite structure not only improves overall stability but also the strain-polarization coupling of the material. Our calculations predict a ground state with P4/nmm space group for the double perovskite, where A-site cations (i.e., Cs and Rb) are layer-ordered and B-site cations (i.e., Ca and Zn) prefer a rocksalt type ordering. The electronic structure and bandgap in this system are shown to be quite sensitive to the B-site cation ordering and is minimally affected by the ordering of A-site cations. We find that at experimentally accessible compressive strains CsRbCaZnCl6 can be phase transformed from its paraelectric ground state to an antiferroelectric state, where Zn atoms contribute predominantly to the polarization. Furthermore, both energy difference and activation barrier for a transformation between this antiferroelectric state and the corresponding ferroelectric configuration are predicted to be small. As a result, the computational approach presented here opens a new pathway towards a rational design of novel double perovskites with improved strain response and functionalities.« less

  20. Long-term selective retention of natural Cs and Rb by highly weathered coastal plain soils.

    PubMed

    Wampler, J M; Krogstad, Eirik J; Elliott, W Crawford; Kahn, Bernd; Kaplan, Daniel I

    2012-04-03

    Naturally occurring Cs and Rb are distinctly more abundant relative to K in the highly weathered upland soils of the Savannah River Site, South Carolina, than in average rock of Earth's upper continental crust (UCC), by factors of 10 and 4, respectively. Naturally occurring Cs has been selectively retained during soil evolution, and Rb to a lesser extent, while K has been leached away. In acid extracts of the soils, the Cs/K ratio is about 50 times and the Rb/K ratio about 15 times the corresponding ratios for the UCC, indicating that relatively large amounts of natural Cs and Rb have been sequestered in soil microenvironments that are highly selective for these elements relative to K. Cation exchange favoring Cs and Rb ions, and subsequent fixation of the ions, at sites in interlayer wedge zones within hydroxy-interlayered vermiculite particles may account for the observations. The amounts of stable Cs retained and the inferred duration of the soil evolution, many thousands of years, provide new insights regarding long-term stewardship of radiocesium in waste repositories and contaminated environments. Study of natural Cs in soil adds a long-term perspective on Cs transport in soils not available from studies of radiocesium.

  1. Hyperfine frequencies of {sup 87}Rb and {sup 133}Cs atoms in Xe gas

    SciTech Connect

    McGuyer, B. H.; Xia, T.; Jau, Y.-Y.; Happer, W.

    2011-09-15

    The microwave resonant frequencies of ground-state {sup 87}Rb and {sup 133}Cs atoms in Xe buffer gas are shown to have a relatively large nonlinear dependence on the Xe pressure, presumably because of RbXe or CsXe van der Waals molecules. The nonlinear shifts for Xe are opposite in sign to the previously measured shifts for Ar and Kr, even though all three gases have negative linear shifts. The Xe data show striking discrepancies with the previous theory for nonlinear shifts. Most of this discrepancy is eliminated by accounting for the spin-rotation interaction, {gamma}N{center_dot}S, in addition to the hyperfine-shift interaction, {delta} A I{center_dot}S, in the molecules. To the limit of our experimental accuracy, the shifts of {sup 87}Rb and {sup 133}Cs in He, Ne, and N{sub 2} were linear with pressure.

  2. The distribution of (137)Cs, K, Rb and Cs in plants in a Sphagnum-dominated peatland in eastern central Sweden.

    PubMed

    Vinichuk, M; Johanson, K J; Rydin, H; Rosén, K

    2010-02-01

    We record the distribution of (137)Cs, K, Rb and Cs within individual Sphagnum plants (down to 20cm depth) as well as (137)Cs in vascular plants growing on a peatland in eastern central Sweden. In Calluna vulgaris(137)Cs was mainly located within the green parts, whereas Andromeda polifolia, Eriophorum vaginatum and Vaccinium oxycoccos showed higher (137)Cs activity in roots. Carex rostrata and Menyanthes trifoliata showed variable distribution of (137)Cs within the plants. The patterns of (137)Cs activity concentration distribution as well as K, Rb and Cs concentrations within individual Sphagnum plants were rather similar and were usually highest in the capitula and/or in the subapical segments and lowest in the lower dead segments, which suggests continuous relocation of those elements to the actively growing apical part. The (137)Cs and K showed relatively weak correlations, especially in capitula and living green segments (0-10cm) of the plant (r=0.50). The strongest correlations were revealed between (137)Cs and Rb (r=0.89), and between (137)Cs and stable Cs (r=0.84). This suggests similarities between (137)Cs and Rb in uptake and relocation within the Sphagnum, but that (137)Cs differs from K.

  3. UV laser induced desorption of CsI and RbI ion clusters

    NASA Astrophysics Data System (ADS)

    Fernández-Lima, F. A.; Ponciano, C. R.; Filho, H. D. Fonseca; Pedrero, E.; Chaer Nascimento, M. A.; da Silveira, E. F.

    2006-09-01

    Experimental results of laser sputtering of cesium and rubidium iodide secondary ions are presented. A TOF mass spectrometer, operating in linear mode, continuous extraction for positive or negative ions, was used for the analysis of (CsI) nCs +, (CsI) nI -, (RbI) nRb + and (RbI) nI - ion emission as a function of the laser irradiance. Experimental data show that the cluster ion emission yields decrease exponentially with n, for all the laser irradiances applied. Theoretical analysis of the clusters structure was performed using density functional theory at the B3LYP/LACV3P level, for the positive and negative cluster series. A quasi-equilibrium evolution of the clusters is proposed to extract a parameter characteristic of the cluster recombination process: the effective temperature. The hypothesis of the atomic species' recombination (during the expansion of a high density highly ionized cloud) leading to cluster formation is confirmed to some extent in a second set of experiments: the UV laser ablation of a mixed and non-mixed cesium iodide and potassium bromide targets. These experiments show that the emission yields contain contributions from both the recombination process and from the sample stoichiometry, even for high laser irradiances.

  4. Collisions of alkali-metal atoms Cs and Rb in the ground state. Spin exchange cross sections

    NASA Astrophysics Data System (ADS)

    Kartoshkin, V. A.

    2016-09-01

    Collisions of alkali-metal atoms 133Cs and 85Rb in the ground state are considered in the energy interval of 10-4-10-2 au. Complex cross sections of the spin exchange, which allow one to calculate the processes of polarization transfer and the relaxation times, as well as the magnetic resonance frequency shifts caused by spin exchange Cs-Rb collisions, are obtained.

  5. Ground electronic states of RbO2+, CsO2+ and FrO2: the ionization energies of RbO2 and CsO2.

    PubMed

    Lee, Edmond P F; Wright, Timothy G

    2005-04-14

    Calculations are performed to establish the ground electronic states of RbO2+, CsO2+, and FrO2. In the case of the cations, both linear and C2v orientations were considered; for FrO2, the two lowest electronic states, 2A2 and 2B2, were considered in C2v symmetry. In addition, calculations were also performed on the x2 A2 ground states of RbO2 and CsO2 to derive ionization energies. Binding energies and heats of formation are also derived. The bonding in FrO2 is found to be less ionic than that of RbO2 and CsO2.

  6. Intergrowth of hexagonal tungsten bronze and perovskite-like structures: The oxides ACu 3M7O 21 ( A = K, Rb, Cs, TI; M = Nb, Ta)

    NASA Astrophysics Data System (ADS)

    Benmoussa, A.; Groult, D.; Studer, F.; Raveau, B.

    1982-02-01

    Seven oxides ACu 3M7O 21 have been isolated with A = K, Rb, Tl, Cs for M = Ta and A = K, Rb, Cs for M = Nb. These phases are orthorhombic: a ⋍ 28 Å, b ⋍ 7.50 Å, and c ⋍ 7.55 Å, probable space group Cmmm. Their structure has been established from an X-ray diffraction study and from high-resolution microscopy observations. The structure consists of an intergrowth of single hexagonal tungsten bronze AM3O 9 slices and double distorted perovskite Cu 3M4O 12 slabs ( M = Nb, Ta) in which copper has a square coordination. The host lattice of these compounds can be considered as the member " n = 1; n' = 2" of a series of intergrowths corresponding to the formulation | M3O 9| Hn| M2O 6| Pn' .

  7. Room temperature light emission from the low-dimensional semiconductors AZrPS6 (A = K, Rb, Cs).

    PubMed

    Banerjee, Santanu; Szarko, Jodi M; Yuhas, Benjamin D; Malliakas, Christos D; Chen, Lin X; Kanatzidis, Mercouri G

    2010-04-21

    The new semiconducting thiophosphate compounds KZrPS(6), RbZrPS(6), and CsZrPS(6) exhibit red light emission at room temperature. The materials have longer photoluminescence lifetimes than most of the inorganic chalcogenide semiconductors. They can be solution processed into thin films for potential device fabrication.

  8. First-principles study on the bulk and (1 1 1) surface half-metallicity of KS and RbS in CsCl structure

    SciTech Connect

    Li, Lei; Lei, Gang; Gao, Qiang; Deng, Jian-Bo; Hu, Xian-Ru

    2015-08-15

    Graphical abstract: Spin-polarized total and atomic DOS at S-(1 1 1) terminated slab and bulk in CsCl-type RbS. - Highlights: • The half metallic properties of CsCl-type RbS and KS have been studied. • The RbS's and KS's (1 1 1) slabs have been investigated. • Surface energy of RbS's and KS's (1 1 1) slabs are calculated. - Abstract: The electronic and magnetic properties of RbS and KS in CsCl structure have been investigated by using the full-potential local-orbital minimum-basis method. Calculating the relation between the total energies and lattice parameters for RbS and KS, we find out that the equilibrium lattice parameters are 4.02 Å and 3.84 Å for RbS and KS, respectively. According to our calculations in generalized gradient approximation approximation, both RbS and KS are half-metallic ferromagnets with the magnetic moments of 1 μ{sub B} per formula unit, and band gap of 4.287 eV for RbS and 4.395 eV for KS. We also have studied the electronic and magnetic properties of (1 1 1) surfaces of RbS and KS, and have found out that the half-metallicity of their bulk is preserved in all of those surfaces. Finally, through the calculations of formation energy of RbS and KS, it is found that their thin films are stable in the equilibrium conditions, and the Rb-terminated (1 1 1) slab of RbS and the K-terminated (1 1 1) slab of KS are more stable than their S-terminated (1 1 1) slabs. All of the above properties lead the compounds of RbS and KS in CsCl structure to be promising candidates for spintronic applications.

  9. Intercalation of heavy alkali metals (K, Rb and Cs) in the bundles of single wall nanotubes

    NASA Astrophysics Data System (ADS)

    Duclaux, L.; Méténier, K.; Lauginie, P.; Salvetat, J. P.; Bonnamy, S.; Beguin, F.

    2000-11-01

    The electric-arc discharge carbon deposits (collaret) containing Single Wall Carbon Nanotubes (SWNTs) were heat treated at 1600 °C during 2 days under N2 flow in order to eliminate the Ni catalyst by sublimation, without modifications of the SWNTs ropes. Sorting this deposit by gravity enabled to obtain in the coarsest particles higher amount of SWNTs ropes than in other particle sizes. The coarser particles of the carbon deposits were reacted with the alkali metals vapor giving intercalated samples with a MC8 composition. The intercalation led to an expansion of the 2D lattice of the SWNTs so that the alkali metals were intercalated in between the tubes within the bundles. Disordered lattices were observed after intercalation of Rb and Cs. The simulations of the X-ray diffractograms of SWNTs reacted with K, gave the best fit for three K ions occupying the inter-tubes triangular cavities. The investigations by EPR, and 13C NMR, showed that doped carbon deposits are metallic.

  10. Investigation on ultracold RbCs molecules in (2)0{sup +} long-range state below the Rb(5S{sub 1/2}) + Cs(6P{sub 1/2}) asymptote by high resolution photoassociation spectroscopy

    SciTech Connect

    Yuan, Jinpeng; Ji, Zhonghua; Li, Zhonghao; Zhao, Yanting Xiao, Liantuan; Jia, Suotang

    2015-07-28

    We present high resolution photoassociation spectroscopy of RbCs molecules in (2)0{sup +} long-range state below the Rb(5S{sub 1/2}) + Cs(6P{sub 1/2}) asymptote and derive the corresponding C{sub 6} coefficient, which is used to revise the potential energy curves. The excited state molecules are produced in a dual-species dark spontaneous force optical trap and detected by ionizing ground state molecules after spontaneous decay, using a high sensitive time-of-flight mass spectrum. With the help of resonance-enhanced two-photon ionization technique, we obtain considerable high resolution photoassociation spectrum with rovibrational states, some of which have never been observed before. By applying the LeRoy-Bernstein method, we assign the vibrational quantum numbers and deduce C{sub 6} coefficient, which agrees with the theoretical value of A{sup 1}Σ{sup +} state correlated to Rb(5S{sub 1/2}) + Cs(6P{sub 1/2}) asymptote. The obtained C{sub 6} coefficient is used to revise the long-range potential energy curve for (2)0{sup +} state, which possesses unique A − b mixing characteristic and can be a good candidate for the production of absolutely ground state molecule.

  11. Rydberg States of rb and cs Atoms on Helium Nanodroplets: a Rydberg-Ritz Analysis

    NASA Astrophysics Data System (ADS)

    Lackner, Florian; Krois, Gunter; Ernst, Wolfgang E.

    2013-06-01

    Rydberg series of Rb and Cs atoms on the surface of helium nanodroplets (He_{N}) have been studied by resonance enhanced multi-photon ionization spectroscopy and laser induced fluorescence spectroscopy. The recorded excitation spectra are analyzed by using a Rydberg-Ritz approach. The dependence of the quantum defects on the principal quantum number within a Rydberg series gives insight into the interaction between the alkali atom's valence electron and the superfluid helium droplet. For higher excited states a screening of the valence electron from the alkali atom core by the helium droplet is observed. For lower states the strength of the screening effect decreases and the quantum defects are found to lie closer to free atom values. In addition, the large spin-orbit (SO) constant of the Cs-He_{N} nP(^{2}Π) states allows a detailed study of the influence of the helium droplet on the SO splitting as function of the principal quantum number. Within the pseudo-diatomic picture the alkali-He_{N} system represents a diatomic molecule. The coupling of the Cs valence electrons spin and the orbital angular momentum with the intermolecular axis, which is defined by the connection between the droplet center and the alkali nucleus, depends on the strength of the atomic SO interaction. While the splitting of the 6^{2}P_{1/2}(^{2}Π_{1/2}) and 6^{2}P_{3/2}(^{2}Π_{3/2}) components has an atom-like character (Hund's case (c) coupling), the SO splitting of higher n states is lower than the atomic value (Hund's case (a) coupling). C. Callegari and W. E. Ernst, Helium Droplets as Nanocryostats for Molecular Spectroscopy - from the Vacuum Ultraviolet to the Microwave Regime, in: Handbook of High-Resolution Spectroscopy, eds. M. Quack and F. Merkt, John Wiley & Sons, Chichester, (2011) F. Lackner, G. Krois, M. Theisen, M. Koch, and W.E. Ernst, Phys. Chem. Chem. Phys., 13, 18781-18788 (2011) F. Lackner, G. Krois, and W.E. Ernst, J. Phys. Chem. Lett., 3, 1404-1408 (2012)

  12. Analysis of strongly coupled electronic states in diatomic molecules: Low-lying excited states of RbCs

    SciTech Connect

    Bergeman, T.; Fellows, C.E.; Gutterres, R.F.; Amiot, C.

    2003-05-01

    Analysis and assignment of spectra involving the lowest excited states of the heavier alkali-metal atom dimers are complicated by the strong spin-orbit coupling elements. Here we report an analysis of the Fourier-transform spectroscopy data from laser-induced fluorescence of the coupled A {sup 1}{sigma}{sup +} and b {sup 3}{pi} states of RbCs, using the discrete variable representation. Fitted parameters are given and special effects due to strong coupling are discussed.

  13. Theoretical study of the low-lying electronic states of the RbCs+ molecular ion

    NASA Astrophysics Data System (ADS)

    Korek, M.; Allouche, A. R.

    2001-09-01

    The potential energy has been calculated over a wide range of internuclear distance for the 64 lowest molecular states of symmetry 2Σ+, 2Π, 2Δ, and Ω = ½, 3/2, 3/2 of the molecular ion RbCs+. This calculation has been done by using an ab initio method based on non-empirical pseudopotentials and parametrized l-dependent polarization potentials. We used Gaussian basis sets for both atoms and the spin-orbit effect has been taken into account through a non-empirical spin-orbit pseudopotential. For the four bound states (1) 2Σ+, (1) 2Π, (1) Ω = ½ and (1) Ω = 3/2 the main spectroscopic constants ωe, Be, and De have been derived. By replacing the rovibrational differential Schrödinger equation by a Volterra integral equation the wavefunction is given by Ψ = ∑i = 01{aifi}, where the coefficients ai are obtained from the boundary conditions of the wavefunction and fi are two well defined canonical functions. Using these functions the eigenvalues Ev, the rotational constants Bv and the centrifugal distortion constants Dv have been calculated for the four considered bound states up to v = 121 as well as the dipole moment functions and oscillator strengths for transitions between (1) 2Σ+ and (1) 2Π. No comparison of these values with other results is yet possible because they are given here for the first time. Extensive tables of energy values versus internuclear distance and the values of Ev, Bv and Dv are displayed at the following address: http://lasim.univ-lyon1.fr/allouche/rbcsplus

  14. Two-Step Excitation of rb and cs Atoms on he Nanodroplets

    NASA Astrophysics Data System (ADS)

    Theisen, Moritz; Lackner, Florian; Ernst, Wolfgang E.; Ancilotto, Francesco; Callegari, Carlo

    2010-06-01

    We present the first sequential excitation of atom-doped helium nanodroplets. Rubidium atoms on the surface of a helium nanodroplet are selectively excited to the 5^2P1/2 state so as not to desorb from the droplet. From there they are excited by a laser pulse to the 5^2D state; a laser-induced fluorescence (LIF) spectrum is recorded by monitoring the 62P→52S1/2 emission. We find some difference in the LIF spectrum as compared to that of the two-photon one-color direct excitation spectrum 5^2D←5^2S1/2. This indicates that the system does relax vibrationally during the lifetime of the 5^2P1/2 state. To model the LIF spectra we calculate the energy levels of the Rb atom as a function of its distance R from the center of the droplet. The Franck-Condon factors of the resulting potential energy curves agree with the experimental findings. A similar behavior has been found for cesium. New measurements predict that it also stays bound on the surface of the droplet in its 6^2P1/2 state. From there we further excited Cs monomers into their 6^2D state, where also the LIF spectrum is recorded by watching the 72P→62S1/2 emission. In the future these states can be used as a springboard to reach high-lying 2S and 2D states, and possibly create an artificial super-atom. G. Auböck, J. Nagl, C. Callegari, and W. E. Ernst, Phys. Rev. Lett. 101, 035301 (2008) F. Ancilotto, M. Pi, R. Mayol, M. Barranco, and K. Lehmann, J. Phys. Chem. A 111, 12695-12701 (2007)

  15. Calculation of spectroscopic constants and radiative parameters for the A 1Σ+- X 1Σ+ electronic transitions of the CsLi and CsRb molecules

    NASA Astrophysics Data System (ADS)

    Smirnov, A. D.

    2016-12-01

    Vibrational, rotational, and centrifugal spectroscopic constants; radiative parameters (the Einstein coefficients for spontaneous emission, the oscillator strengths for absorption, and the Franck-Condon factors), the r v' v″-centroids; the wavenumbers of rotational lines of rovibronic transitions in the systems of bands A 1Σ+- X 1Σ+ of CsLi (0 ≤ v' ≤ 25, 0 ≤ v″ ≤ 51, j = 0, 30, 50, 70, 100) and CsRb (0 ≤ v' ≤ 30, 0 ≤ v″ ≤ 64, j = 0, 50, 100) molecules; and the radiative lifetimes for excited electronic states are calculated. The calculations are carried out on the basis of semiempirical potential curves constructed in this work. The calculated spectroscopic constants are compared with the experimental data. The lifetimes have been obtained for the first time.

  16. Interrelationship between Number of Mobile Protons, Diffusion Coefficient, and AC Conductivity in Superprotonic Conductors, CsHSO4 and Rb3H(SeO4)2

    NASA Astrophysics Data System (ADS)

    Kamazawa, Kazuya; Harada, Masashi; Araki, Toru; Matsuo, Yasumitsu; Tyagi, Madhusudan; Sugiyama, Jun

    2014-07-01

    Using quasielastic neutron scattering (QENS), we investigated the proton dynamics for two superprotonic conductors, CsHSO4 and Rb3H(SeO4)2. To evaluate the self-diffusion coefficients and the number of mobile protons on both superprotonic and normal phases, we focused on proton dynamics not only in the phase above Tc, but also in the phase below Tc. In Rb3H(SeO4)2, the self-diffusion of protons was observed even below the Tc phase. In contrast to popular belief, no large changes in the self-diffusion coefficients were observed across Tc. Nevertheless, the increase in the number of mobile protons across Tc was about 14.5 times, which was estimated from the integrated intensity of QENS spectra, and this change could not account for the increased magnitude of proton conductivity, which is about 500 times. As a large translational self-diffusion coefficient has not been reported in previous works by QENS experiments, there are still unknown factors that contribute to the Nernst-Einstein relation that need to be discovered.

  17. Synthesis and characterization of ASnF{sub 3} (A=Na{sup +}, K{sup +}, Rb{sup +}, Cs{sup +})

    SciTech Connect

    Thao Tran, T.; Shiv Halasyamani, P.

    2014-02-15

    A family of alkali metal tin(II) fluorides, ASnF{sub 3} (A=Na{sup +}, K{sup +}, Rb{sup +}, or Cs{sup +}), has been synthesized through a low temperature solvothermal technique. A fluorine free solvent, methanol, was used in the synthesis. NaSnF{sub 3}, KSnF{sub 3}, and RbSnF{sub 3} have been reported previously; however for RbSnF{sub 3} the reported space group is incorrect. CsSnF{sub 3} is a new alkali tin(II) fluoride, and exhibits a ‘zero-dimensional’ crystal structure with isolated SnF{sub 3}{sup −} anions separated by Cs{sup +} cations. In addition to the synthesis, infrared, UV–vis, thermogravimetric and differential thermal analysis measurements were performed. - Graphical abstract: Ball-and-stick diagrams of CsSnF{sub 3}. Display Omitted - Highlights: • A family of ASnF{sub 3} (A=Na{sup +}, K{sup +}, Rb{sup +} or Cs{sup +}) has been synthesized solvothermally at low temperatures. • Fluorine-free solvent, methanol, was used instead of conventional fluorinating agents. • RbSnF{sub 3} described in the correct space group exhibits infinite chains of corner-sharing SnF{sub 4} polyhedra. • New CsSnF{sub 3} exhibits a ‘zero-dimensional’ crystal structure consisting of isolated SnF{sub 3}{sup −} anionic polyhedra.

  18. Interactions in cation permeation through the gramicidin channel. Cs, Rb, K, Na, Li, Tl, H, and effects of anion binding.

    PubMed Central

    Eisenman, G; Sandblom, J; Neher, E

    1978-01-01

    As a prototype for binding and interaction in biological Na and K channels, the single channel conductances for Li, Na, K, Rb, Cs, H, and Tl and the membrane potentials for Tl-K mixtures are characterized for gramicidin A over wider concentration rangers than previously and analyzed using an "equilibrium domain" model that assumes a central rate-determining barrier. Peculiarities in the conductance-concentration relationship for TlF, TlNO3, and TlAc suggest that anions bind to Tl-loaded channels, and the theory is extended to allow for this. For concreteness, the selectivity of cation permeation is characterized in terms of individual binding and rate constants of this model, with the conclusions that the strongest site binds Cs greater than Rb greater than K greater than Na greater than Li, while the next strongest binds Na greater than K greater than Li greater than Rb greater than Cs. However, because Schagina, Grinfeldt, and Lev's recent finding of single filing (personal communication) indicates that the channel sites in gramicidin cannot be at equilibrium with the solution, and work in progress with Hägglund and Enos (Biophys. J. 21:26a. [Abstr.]) indicates that the simplest model adequate to account for the observed concentration-dependences of flux-ratio, conductance, I--V characteristic, and permeability has three barriers and four sites, some implications of additional rate-determining barriers at the mouth of the channel are discussed. The results are summarized using phenomenological "experimental" parameters that provide a model-independent way to represent that data concisely and which can be interpreted physically in terms of any desired model. PMID:77689

  19. Two spatially separated phases in semiconducting Rb0.8Fe1.5S2

    DOE PAGES

    Wang, Meng; Tian, Wei; Valdivia, P.; ...

    2014-09-26

    We report neutron scattering and transport measurements on semiconducting Rb0.8Fe1.5S2, a compound isostructural and isoelectronic to the well-studied A0.8FeySe2(A = K, Rb, Cs, Tl/K) superconducting systems. Both resistivity and DC susceptibility measurements reveal a magnetic phase transition at T = 275 K. Neutron diffraction studies show that the 275 K transition originates from a phase with rhombic iron vacancy order which exhibits an in-plane stripe antiferromagnetic ordering below 275 K. In addition, the stripe antiferromagnetic phase interdigitates mesoscopically with an ubiquitous phase with √5 x√5 iron vacancy order. This phase has a magnetic transition at TN = 425 K andmore » an iron vacancy order-disorder transition at TS = 600 K. These two different structural phases are closely similar to those observed in the isomorphous Se materials. Based on the close similarities of the in-plane antiferromagnetic structures, moments sizes, and ordering temperatures in semiconducting Rb0.8Fe1.5S2 and K0.81Fe1.58Se2, we argue that the in-plane antiferromagnetic order arises from strong coupling between local moments. Superconductivity, previously observed in the A0.8FeySe2₋ zSz system, is absent in A0.8Fe1.5S2, which has a semiconducting ground state. We discuss the implied relationship between stripe and block antiferromagnetism and superconductivity in these materials as well as a strategy for further investigation.« less

  20. Strain-Driven Approach to Quantum Criticality in AFe_{2}As_{2} with A=K, Rb, and Cs.

    PubMed

    Eilers, Felix; Grube, Kai; Zocco, Diego A; Wolf, Thomas; Merz, Michael; Schweiss, Peter; Heid, Rolf; Eder, Robert; Yu, Rong; Zhu, Jian-Xin; Si, Qimiao; Shibauchi, Takasada; Löhneysen, Hilbert V

    2016-06-10

    The iron-based superconductors AFe_{2}As_{2} with A=K, Rb, Cs exhibit large Sommerfeld coefficients approaching those of heavy-fermion systems. We have investigated the magnetostriction and thermal expansion of this series to shed light on this unusual behavior. Quantum oscillations of the magnetostriction allow identifying the band-specific quasiparticle masses which by far exceed the band-structure derived masses. The divergence of the Grüneisen ratio derived from thermal expansion indicates that with increasing volume along the series a quantum critical point is approached. The critical fluctuations responsible for the enhancement of the quasiparticle masses appear to weaken the superconducting state.

  1. Strain-Driven Approach to Quantum Criticality in A Fe2 As2 with A =K , Rb, and Cs

    NASA Astrophysics Data System (ADS)

    Eilers, Felix; Grube, Kai; Zocco, Diego A.; Wolf, Thomas; Merz, Michael; Schweiss, Peter; Heid, Rolf; Eder, Robert; Yu, Rong; Zhu, Jian-Xin; Si, Qimiao; Shibauchi, Takasada; Löhneysen, Hilbert v.

    2016-06-01

    The iron-based superconductors A Fe2 As2 with A =K , Rb, Cs exhibit large Sommerfeld coefficients approaching those of heavy-fermion systems. We have investigated the magnetostriction and thermal expansion of this series to shed light on this unusual behavior. Quantum oscillations of the magnetostriction allow identifying the band-specific quasiparticle masses which by far exceed the band-structure derived masses. The divergence of the Grüneisen ratio derived from thermal expansion indicates that with increasing volume along the series a quantum critical point is approached. The critical fluctuations responsible for the enhancement of the quasiparticle masses appear to weaken the superconducting state.

  2. Heavier alkali-metal monosulfides (KS, RbS, CsS, and FrS) and their cations.

    PubMed

    Lee, Edmond P F; Wright, Timothy G

    2005-10-08

    The heavier alkali-metal monosulfides (KS, RbS, CsS, and FrS) have been studied by high-level ab initio calculations. The RCCSD(T) method has been employed, combined with large flexible valence basis sets. All-electron basis sets are used for potassium and sulfur, with effective core potentials being used for the other metals, describing the core electrons. Potential-energy curves are calculated for the lowest two neutral and cationic states: all neutral monosulfide species have a (2)Pi ground state, in contrast with the alkali-metal monoxide species, which undergo a change in the electronic ground state from (2)Pi to (2)Sigma(+) as the group is descended. In the cases of KS, RbS, and CsS, spin-orbit curves are also calculated. We also calculate potential-energy curves for the lowest (3)Sigma(-) and (3)Pi states of the cations. From the potential-energy curves, spectroscopic constants are derived, and for KS the spectroscopic results are compared to experimental spectroscopic values. Ionization energies, dissociation energies, and heats of formation are also calculated; for KS, we explore the effects of relativity and basis set extrapolation on these values.

  3. M + Ng potential energy curves including spin-orbit coupling for M = K, Rb, Cs and Ng = He, Ne, Ar.

    PubMed

    Blank, L; Weeks, David E; Kedziora, Gary S

    2012-03-28

    The X(2)Σ(1/2)(+), A(2)Π(1∕2), A(2)Π(3∕2), and B(2)Σ(1/2)(+) potential energy curves and associated dipole matrix elements are computed for M + Ng at the spin-orbit multi-reference configuration interaction level, where M = K, Rb, Cs and Ng = He, Ne, Ar. Dissociation energies and equilibrium positions for all minima are identified and corresponding vibrational energy levels are computed. Difference potentials are used together with the quasistatic approximation to estimate the position of satellite peaks of collisionally broadened D2 lines. The comparison of potential energy curves for different alkali atom and noble gas atom combinations is facilitated by using the same level of theory for all nine M + Ng pairs.

  4. Driving the formation of the RbCs dimer by a laser pulse: A nonlinear-dynamics approach

    NASA Astrophysics Data System (ADS)

    Chandre, C.; Mahecha, Jorge; Salas, J. Pablo

    2017-03-01

    We study the formation of the RbCs molecule by an intense laser pulse using nonlinear dynamics. Under the Born-Oppenheimer approximation, the system is modeled by a two-degree-of-freedom rovibrational Hamiltonian, which includes the ground electronic potential energy curve of the diatomic molecule and the interaction of the molecular polarizability with the electric field of the laser. As the laser intensity increases, we observe that the formation probability first increases and then decreases after reaching a maximum. We show that the analysis can be simplified to the investigation of the long-range interaction between the two atoms. We conclude that the formation is due to a very small change in the radial momentum of the dimer induced by the laser pulse. From this observation, we build a reduced one-dimensional model which allows us to derive an approximate expression of the formation probability as a function of the laser intensity.

  5. Activity of vanadium catalysts for sulfuric acid production, promoted with Na, K, Rb, Cs, and Mg compounds, at various pressures of sulfur oxides

    SciTech Connect

    Ivanenko, S.V.; Dzhoraev, R.R.

    1995-12-10

    The activities of vanadium catalysts promoted with Na, K, Rb, Cs, and Mg sulfates (ratio Me:V = 4) were studied in conditions of low (up to 1 kPa) and high (up to 70 kPa) partial pressures of sulfur oxides at 693 and 758 K. The authors report results of reaction kinetic studies.

  6. Role of Acentric Displacements on the Crystal Structure and Second-Harmonic Generating Properties of RbPbCO3F and CsPbCO3F

    PubMed Central

    2015-01-01

    Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet–visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6̅m2 (crystal class 6̅m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × α-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even–odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb2+. The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates. PMID:24867361

  7. Role of acentric displacements on the crystal structure and second-harmonic generating properties of RbPbCO3F and CsPbCO3F.

    PubMed

    Tran, T Thao; Halasyamani, P Shiv; Rondinelli, James M

    2014-06-16

    Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet-visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6m2 (crystal class 6m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × α-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even-odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb(2+). The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates.

  8. SUMOylation of Rb enhances its binding with CDK2 and phosphorylation at early G1 phase.

    PubMed

    Meng, Fengxi; Qian, Jiang; Yue, Han; Li, Xiaofeng; Xue, Kang

    2016-07-02

    Retinoblastoma protein (Rb) is a prototypical tumor suppressor that is vital to the negative regulation of the cell cycle and tumor progression. Hypo-phosphorylated Rb is associated with G0/G1 arrest by suppressing E2F transcription factor activity, whereas Rb hyper-phosphorylation allows E2F release and cell cycle progression from G0/G1 to S phase. However, the factors that regulate cyclin-dependent protein kinase (CDK)-dependent hyper-phosphorylation of Rb during the cell cycle remain obscure. In this study, we show that throughout the cell cycle, Rb is specifically small ubiquitin-like modifier (SUMO)ylated at early G1 phase. SUMOylation of Rb stimulates its phosphorylation level by recruiting a SUMO-interaction motif (SIM)-containing kinase CDK2, leading to Rb hyper-phosphorylation and E2F-1 release. In contrast, a SUMO-deficient Rb mutant results in reduced SUMOylation and phosphorylation, weakened CDK2 binding, and attenuated E2F-1 sequestration. Furthermore, we reveal that Rb SUMOylation is required for cell proliferation. Therefore, our study describes a novel mechanism that regulates Rb phosphorylation during cell cycle progression.

  9. Low-lying {sup 3}P{sup o} and {sup 3}S{sup e} states of Rb{sup -}, Cs{sup -}, and Fr{sup -}

    SciTech Connect

    Bahrim, C.; Thumm, U.

    2000-02-01

    Our Dirac R-matrix calculations suggest that none of the heavy alkali-metal negative ions, Rb, Cs, and Fr, has an excited bound state. Their lowest excited state appears to be a multiplet of {sup 3}P{sub J}{sup o}-shape resonances, the J=1 component of which was recently observed in photodetachment experiments on Cs{sup -}. We analyze these {sup 3}P{sub J}{sup o} and the {sup 3}S{sup e} excited negative ion states in partial and converged total scattering cross sections for slow electrons with incident kinetic energies below 120 meV. Our results are in excellent agreement with available experimental data. We also propose a new value for the electron affinity of Fr, provide the scattering length for electronic collisions with Rb, Cs, and Fr, and discuss the nuclear charge dependence of relativistic effects in the resonance profiles. (c) 2000 The American Physical Society.

  10. Structural studies and electrical properties of Cs/Al/Te/O phases with the pyrochlore structure.

    PubMed

    Li, Jun; Siritanon, Theeranun; Stalick, Judith K; Sleight, Arthur W; Subramanian, M A

    2011-06-20

    A series of polycrystalline and single crystal cesium aluminum tellurates with the pyrochlore structure have been prepared and characterized. The variations in cell edge for the Cs/Al/Te/O phases range from 10.06 Å for the Al rich limit to 10.14 Å for the Te rich limit. Rietveld structural analyses based on both X-ray and neutron diffraction data were performed on 5 different compositions. Single crystals of 3 compositions were prepared and studied by X-ray diffraction. The anharmonic component of the thermal motion for Cs was small but became significant on replacing Cs with Rb. A maximum in the electrical conductivity of about 0.1 S/cm is found in the middle of this range close to the ideal composition of CsAl(1/3)Te(5/3)O(6). The conductivity is attributed to filled Te 5s states associated with Te(4+) lying just below the conduction band based on empty Te 5s states associated with Te(6+). The relatively large Te(4+) ion is compressed by the lattice, and as this compression increases the filled 5s states approach the conduction band and thereby increases conductivity.

  11. Scattering parameters for cold Li-Rb and Na-Rb collisions derived from variable phase theory

    SciTech Connect

    Ouerdane, H.; Jamieson, M.J.

    2004-08-01

    We show how the scattering phase shift, the s-wave scattering length, and the p-wave scattering volume can be obtained from Riccati equations derived in variable phase theory. We find general expressions that provide upper and lower bounds for the scattering length and the scattering volume. We show how, in the framework of the variable phase method, Levinson's theorem yields the number of bound states supported by a potential. We report results from a study of the heteronuclear alkali-metal dimers NaRb and LiRb. We consider ab initio molecular potentials for the X {sup 1}{sigma}{sup +} and a {sup 3}{sigma}{sup +} states of both dimers and compare and discuss results obtained from experimentally based X {sup 1}{sigma}{sup +} and a {sup 3}{sigma}{sup +} potentials of NaRb. We explore the mass dependence of the scattering data by considering all isotopomers and we calculate the numbers of bound states supported by the molecular potentials for each isotopomer.

  12. New alkali metal diphosphates how materials to preserve the security of the environment: CsNaCu(P2O7), Rb2Cu(P2O7) and CsNaCo(P2O7) synthesis and crystal structure determination

    NASA Astrophysics Data System (ADS)

    Chernyatieva, Anastasiya; Filatova, Alyona; Spiridonova, Dariya; Krivovichev, Sergey

    2013-04-01

    In this work we describe preliminary results of the synthesis and of a crystal-chemical study of synthetic phosphates with transition metals. Due to the increasing requirements for environmental safety specialists from various industries, we are searching for sustainable forms of immobilization of hazardous waste during storage. We are also developing a component-based waste for new materials. In our continued exploratory synthesis of compounds containing transition-metals, we were able to produce the new diphosphate phases CsNaCu(P2O7), Rb2Cu(P2O7) and CsNaCo(P2O7). A crystal chemical study has allowed us to identify new phosphates. Crystals of CsNaCu(P2O7) (Phase 1) is orthorhombic, crystallizes in space group Pmn21, with a = 5.147(8), b = 15.126(2), c = 9.717(2) Å, V = 756.20 Å3, R1 = 0.066 and Rb2Cu(P2O7) (Phase 2) is orthorhombic as well, crystallizes in space group Pmcn, with a = 5.183(8), b = 10.096(1), c = 15.146(3) Å, V = 793.55 Å3, R1 = 0.063, they have been obtained by high-temperature reaction of RbNO3, CsNO3, Cu(NO3)2, NaOH and (NH4)4P2O7. Synthetic crystals of the phosphate of copper and rubidium were studied in detail by us on the structures of Rb2Cu(P2O7) and Rb2Cu3(P2O7)2 - new alkali metal copper diphosphates (CHERNYATIEVA et al., 2008). Here we report the synthesis, the structure and the properties of the title compounds and we compare these phases with the previously discovered K2CuP2O7 (ELMAADI et al., 1995) and CsNaMnP2O7 (HUANG et al., 1998). These structures crystallize in other space groups, although their structures are also based on 2-D layers, formed by P2O7 groups combined with polyhedra of the transition metals (CHERNYATIEVA et al., 2012). A crystal chemical study has allowed us to identify even new diphosphates CsNaCu(P2O7) (Phase 3). Crystals of CsNaCoP2O7 is monoclinic, space group P 21/n, with a = 7,424(2), b = 7,648(1), c = 12,931(3)Å, β = 90,71(2)° , V = 734.2(3) Å3 and R1 = 0.060. The structure is based framework of Co

  13. Phase Transitions in CsSnCl3 and CsPbBr3 An NMR and NQR Study

    NASA Astrophysics Data System (ADS)

    Sharma, Surendra; Weiden, Norbert; Weiss, Alarich

    1991-04-01

    The phase transitions in CsSnCl3 and CsPbBr3 have been studied by X-ray powder diffraction, by 81Br-NQR and by 'H-, 119Sn-, and 113Cs-NMR. At room temperature in air CsSnCl3 forms a hydrate which can be dehydrated to the monoclinic phase II of CsSnCl3. The high temperature phase I has the Perovskite structure, as the X-ray and NMR experiments show. The three phases of CsPbBr3, known from literature, have been corroborated. The results are discussed in the framework of the group ABX3, A = alkalimetal ion, B = IV main group ion, and X = Halogen ion

  14. Shape resonances in ground-state diatomic molecules: General trends and the example of RbCs

    SciTech Connect

    Londono, B. E.; Mahecha, J. E.; Luc-Koenig, E.; Crubellier, A.

    2010-07-15

    The presence of shape resonances due to tunneling through the centrifugal barrier modifies strongly the dynamics of cold atom scattering. As shown on the example of the ground and lowest triplet electronic states of the {sup 85}Rb{sup 133}Cs molecule, the crucial parameter is, as usual for cold collisions, the scattering length. A general description of shape resonances of diatomic molecules is given from three simple single channel asymptotic models, whose respective performances are discussed. The first model, which consists of a R{sup -6} potential limited at short range by a repulsive wall, positioned to reproduce the s-wave scattering length, accounts satisfactorily for the main system-independent properties of shape resonances. Introduction in the model of energy- and angular-momentum-dependent nodal lines specific to the inner part of the potential greatly improves its efficiency. When the energy and angular momentum dependence of the nodal lines cannot be deduced from full potential calculations or from experiment, a rough, but universal, estimate of these properties is obtained by extending the R{sup -6} behavior of the potential up to the origin.

  15. Measurement of the binding energy of ultracold 87Rb133Cs molecules using an offset-free optical frequency comb

    NASA Astrophysics Data System (ADS)

    Molony, Peter K.; Kumar, Avinash; Gregory, Philip D.; Kliese, Russell; Puppe, Thomas; Le Sueur, C. Ruth; Aldegunde, Jesus; Hutson, Jeremy M.; Cornish, Simon L.

    2016-08-01

    We report the binding energy of 87Rb133Cs molecules in their rovibrational ground state measured using an offset-free optical frequency comb based on difference frequency generation technology. We create molecules in the absolute ground state using stimulated Raman adiabatic passage (STIRAP) with a transfer efficiency of 88%. By measuring the absolute frequencies of our STIRAP lasers, we find the energy-level difference from an initial weakly bound Feshbach state to the rovibrational ground state with a resolution of ˜5 kHz over an energy-level difference of more than 114 T Hz ; this lets us discern the hyperfine splitting of the ground state. Combined with theoretical models of the Feshbach-state binding energies and ground-state hyperfine structure, we determine a zero-field binding energy of h ×114 268 135.24 (4 )(3 )M Hz . To our knowledge, this is the most accurate determination to date of the dissociation energy of a molecule.

  16. Phase transitions in CsCl-type intemetallic compounds

    SciTech Connect

    Chen, Bai-Hao.

    1990-06-13

    Phase transitions in binary intermetallic compounds with the CsCl-type structure have been studied by a novel combination of high-temperature powder X-ray diffraction and Rietveld Landau theory of symmetry and phase transitions and the Gibbs-Knonvalow equation have been applied to understand the phase behavior of some systems with the CsCl-type structure. The nonstoichiometric compounds RhTi, NbRu, and RuTa with the CsCl-type structure at high temperature undergo thermal symmetry breaking transitions upon cooling. The transitions are first to the AuCu-type tetragonal, and taken to the orthorhombic NbRu-type with Cmmm symmetry. Alloys Ir-Ti which are titanium rich have the CsCl-type structure. This cubic structure transforms to the AuCu-type tetragonal structure and then to the NbRu-type structure with increasing atomic percent iridium. New partial phase diagrams for the composition ranges in near equiatomic MnAu, NbRu, and RuTa are also presented.

  17. Synthesis and structural characterization of the new clathrates K8Cd4Ge42, Rb8Cd4Ge42, and Cs8Cd4Ge42

    DOE PAGES

    Schafer, Marion; Bobev, Svilen

    2016-03-25

    This paper presents results from our exploratory work in the systems K-Cd-Ge, Rb-Cd-Ge, and Cs-Cd-Ge, which yielded the novel type-I clathrates with refined compositions K8Cd3.77(7)Ge42.23, Rb8Cd3.65(7)Ge42.35, and Cs7.80(1)Cd3.65(6)Ge42.35. The three compounds represent rare examples of clathrates of germanium with the alkali metals, where a d10 element substitutes a group 14 element. The three structures, established by single-crystal X-ray diffraction, indicate that the framework-building Ge atoms are randomly substituted by Cd atoms on only one of the three possible crystallographic sites. Furthermore, this and several other details of the crystal chemistry are elaborated.

  18. Optically isotropy in scintillator host compounds M{sub 2}LaCl{sub 5} (M=Rb, and Cs): Ab-initio study

    SciTech Connect

    Shwetha, G.; Kanchana, V.; Vaitheeswaran, G.

    2015-06-24

    Full potential linearized augmented plane wave method (FP-LAPW) has been used to calculate the electronic structure and optical properties of high light output scintillator host compounds M{sub 2}LaCl{sub 5} (M=Rb, and Cs) with in the Tran Blaha modified Becke Johnson (TB-mBJ) potential. These are wide band gap materials with the band gap of 4.75, and 4.72 eV for Rb{sub 2}LaCl{sub 5}, and Cs{sub 2}LaCl{sub 5} respectively. From the calculated optical properties of these compounds, we find these compounds to be optically isotropic, though they are structurally anisotropic, which is an important criteria for the ceramic scintillators.

  19. Antiferromagnetic phase transition of K-Rb alloy nanoclusters incorporated in sodalite

    NASA Astrophysics Data System (ADS)

    Nakano, Takehito; Ishida, Yuko; Hanazawa, Atsufumi; Nozue, Yasuo

    2013-06-01

    We prepared Rb-rich K-Rb alloy nanoclusters arrayed in the regular nanospace of aluminosilicate sodalite which has a bcc arrangement of cages. The average chemical formula of the cluster is (K1.5Rb2.5)3+, where one unpaired s-electron is shared by four alkali cations and is confined in a cage. The magnetic susceptibility and the electron spin resonance clearly show an antiferromagnetic phase transition at a Néel temperature T N of approximately 90-100 K. The observed T N is higher than that in K{4/3+} ( T N = 72 K) and (K3Rb)3+ clusters ( T N = 80 K) in sodalites. This result indicates a systematic enhancement of the antiferromagnetic exchange coupling between the adjacent nanoclusters by substituting Rb atoms for K ones. The size and the spatial distribution of the s-electron wave function in the nanocluster play a key role in the exchange coupling.

  20. Quaternary neptunium compounds: syntheses and characterization of KCuNpS(3), RbCuNpS(3), CsCuNpS(3), KAgNpS(3), and CsAgNpS(3).

    PubMed

    Wells, Daniel M; Jin, Geng Bang; Skanthakumar, S; Haire, Richard G; Soderholm, L; Ibers, James A

    2009-12-21

    The five quaternary neptunium compounds KCuNpS3, RbCuNpS3, CsCuNpS3, KAgNpS3, and CsAgNpS3 (AMNpS3) have been synthesized by the reaction of Np, Cu or Ag, S, and K2S or Rb2S3 or Cs2S3 at 793 K (Rb) or 873 K. These isostructural compounds crystallize as black rectangular plates in the KCuZrS3 structure type in space group Cmcm of the orthorhombic system. The structure comprises MS4 (M = Cu or Ag) tetrahedra and NpS6 octahedra that edge share to form infinity 2[MNpS3-] layers. These layers are separated by the alkali-metal cations. The Np-S bond lengths vary from 2.681(2) to 2.754(1) A. When compared to the corresponding isostructural Th and U compounds these bond distances obey the expected actinide contraction. As the structure contains no S-S bonds, formal oxidation states of +1/+1/+4/-2 may be assigned to A/M/Np/S, respectively. From these results a value of 2.57 for the bond-valence parameter r0 for Np(4+)-S(2-) has been derived and applied to the estimation of the formal oxidation states of Np in the binary NpxSy compounds whose structures are known.

  1. Spin Polarization of Rb and Cs np ^{2}P_{3/2} (n=5, 6) Atoms by Circularly Polarized Photoexcitation of a Transient Diatomic Molecule.

    PubMed

    Mironov, A E; Hewitt, J D; Eden, J G

    2017-03-17

    We report the selective population of Rb or Cs np ^{2}P_{3/2} (n=5, 6; F=4, 5) hyperfine states by the photodissociation of a transient, alkali-rare gas diatomic molecule. Circularly polarized (σ^{-}), amplified spontaneous emission (ASE) on the D_{2} line of Rb or Cs (780.0 and 852.1 nm, respectively) is generated when Rb-Xe or Cs-Xe ground state collision pairs are photoexcited by a σ^{+}-polarized optical field having a wavelength within the D_{2} blue satellite continuum, associated with the B^{2}Σ_{1/2}^{+}←X^{2}Σ_{1/2}^{+} (free←free) transition of the diatomic molecule. The degree of spin polarization of Cs (6p ^{2}P_{3/2}), specifically, is found to be dependent on the interatomic distance (R) at which the excited complex is born, a result attributed to the structure of the B^{2}Σ_{1/2}^{+} state. For Cs-Xe atomic pairs, tuning the wavelength of the optical field from 843 to 848 nm varies the degree of circular polarization of the ASE from 63% to almost unity because of the perturbation, in the 5≤R≤6  Å interval, of the ^{2}Σ_{1/2}^{+} potential by a dσ molecular orbital associated with a higher ^{2}Λ electronic state. Monitoring only the Cs 6p ^{2}P_{3/2} spin polarization reveals a previously unobserved interaction of CsXe (B^{2}Σ_{1/2}^{+}) with the lowest vibrational levels of a ^{2}Λ state derived from Cs (5d)+Xe. By inserting a molecular intermediate into the alkali atom excitation mechanism, these experiments realize electronic spin polarization through populating no more than two np ^{2}P_{3/2} hyperfine states, and demonstrate a sensitive spectroscopic probe of R-dependent state-state interactions and their impact on interatomic potentials.

  2. Residues beyond the selectivity filter of the K+ channel kir2.1 regulate permeation and block by external Rb+ and Cs+.

    PubMed

    Thompson, G A; Leyland, M L; Ashmole, I; Sutcliffe, M J; Stanfield, P R

    2000-07-15

    1. Kir2.1 channels are blocked by Rb+ and Cs+ in a voltage-dependent manner, characteristic of many inward rectifier K+ channels. Mutation of Ser165 in the transmembrane domain M2 to Leu (S165L) abolished Rb+ blockage and lowered Cs+ blocking affinity. At negative voltages Rb+ carried large inward currents. 2. A model of the Kir2.1 channel, built by homology with the structure of the Streptomyces lividans K+ channel KcsA, suggested the existence of an intersubunit hydrogen bond between Ser165 and Thr141 in the channel pore-forming P-region that helps stabilise the structure of this region. However, mutations of Thr141 and Ser165 did not produce effects consistent with a hydrogen bond between these residues being essential for blockage. 3. An alternative alignment between the M2 regions of Kir2.1 and KcsA suggested that Ser165 is itself a pore-lining residue, more directly affecting blockage. We were able to replace Ser165 with a variety of polar and non-polar residues, consistent with this residue being pore lining. Some of these changes affected channel blockage. 4. We tested the hypothesis that Asp172 - a residue implicated in channel gating by polyamines - formed an additional selectivity filter by using the triple mutant T141A/S165L/D172N. Large Rb+ and Cs+ currents were measured in this mutant. 5. We propose that both Thr141 and Ser165 are likely to provide binding sites for monovalent blocking cations in wild-type channels. These residues lie beyond the carbonyl oxygen tunnel thought to form the channel selectivity filter, which the blocking cations must therefore traverse.

  3. A combined metal-halide/metal flux synthetic route towards type-I clathrates: crystal structures and thermoelectric properties of A8Al8Si38 (A = K, Rb, and Cs).

    PubMed

    Baran, Volodymyr; Senyshyn, Anatoliy; Karttunen, Antti J; Fischer, Andreas; Scherer, Wolfgang; Raudaschl-Sieber, Gabriele; Fässler, Thomas F

    2014-11-10

    Single-phase samples of the compounds K8Al8Si38 (1), Rb8Al8Si38 (2), and Cs7.9Al7.9Si38.1 (3) were obtained with high crystallinity and in good quantities by using a novel flux method with two different flux materials, such as Al and the respective alkali-metal halide salt (KBr, RbCl, and CsCl). This approach facilitates the removal of the product mixture from the container and also allows convenient extraction of the flux media due to the good solubility of the halide salts in water. The products were analyzed by means of single-crystal X-ray structure determination, powder X-ray and neutron diffraction experiments, (27)Al-MAS NMR spectroscopy measurements, quantum chemical calculations, as well as magnetic and transport measurements (thermal conductivity, electrical resistivity, and Seebeck coefficient). Due to the excellent quality of the neutron diffraction data, the difference between the nuclear scattering factors of silicon and aluminum atoms was sufficient to refine their mixed occupancy at specific sites. The role of variable-range hopping for the interpretation of the resistivity and the Seebeck coefficient is discussed.

  4. Evaluation of in vivo detection properties of 22Na, 65Zn, 86Rb, 109Cd and 137Cs in plant tissues using real-time radioisotope imaging system.

    PubMed

    Sugita, Ryohei; Kobayashi, Natsuko I; Hirose, Atsushi; Tanoi, Keitaro; Nakanishi, Tomoko M

    2014-02-21

    In plant research, radioisotope imaging provides useful information about physiological activities in various tissues and elemental transport between plant organs. To expand the usage of imaging techniques, a new system was developed to visualize beta particles, x-rays and gamma-rays emitted from plant bodies. This real-time radioisotope imaging system (RRIS) visualizes radioactivity after conversion into light with a CsI(Tl) scintillator plate. Herein, the RRIS detection properties of the gamma-ray emitters (22)Na, (65)Zn, (86)Rb, (109)Cd and (137)Cs were evaluated in comparison with those of radioluminography (RLG) using an imaging plate. The lower quantitative detection limit (Bq mm(-2)) during a 15 min period ranged from 0.1 to 4, depending on the nuclide, similar to that of RLG. When the quantitative ability to detect radiation from various Arabidopsis tissues was analyzed, the quantitative capability in silique and the thick internode tended to be low. In an EGS5 simulation, beta particles were the greatest contributors to RRIS imaging of (22)Na, (86)Rb and (137)Cs, and low-energy x-rays contributed significantly to (65)Zn and (109)Cd detection. Thus, both self-absorption and air space between the sample and scintillator surface could impair quantitative RRIS imaging. Despite these issues, RRIS is suggested for quantitative time-course measurements of radionuclide motion within plants.

  5. Structure and superconductivity of (Li1-x Fe x )OHFeSe single crystals grown using A x Fe2-y Se2 (A  =  K, Rb, and Cs) as precursors.

    PubMed

    Yu, G; Zhang, G Y; Ryu, G H; Lin, C T

    2016-01-13

    We present results on the hydrothermal growth of ([Formula: see text])OHFeSe single crystals using floating-zone-grown [Formula: see text] (A  =  K, Rb, and Cs) as precursors. The growth proceeds by the hydrothermal ion exchange of Li/Fe-O-H for K, Rb, and Cs, resulting in a stacking layer of ([Formula: see text])OH sandwiched between the FeSe layers. Optimal growth parameters are achieved using high quality A 0.80Fe1.81Se2 single crystals added to the mixtures of LiOH, H2O, Fe and C(NH2)2Se in an autoclave and subsequently heated to 120 °C for 2 d, to obtain highest quality single crystals. The obtained crystals have lateral dimensions up to centimeters, with the final size related to that of the precursor crystal used. All ([Formula: see text])OHFeSe single crystals show a superconducting transition temperature T c  >  42 K, regardless of the phase of the precursor such as superconducting K0.80Fe1.81Se2 (T c  =  29.31 K) or non-superconducting Rb0.80Fe1.81Se2 or poor-superconducting Cs0.80Fe1.81Se2 (T c  =  28.67 K). The T c and transition width ΔT vary in the obtained single crystals, due to the inhomogeneity of the ionic exchange. X-ray diffraction analysis demonstrates that the 245 insulating phase is absent in the ion-exchanged single crystals, while it is observed in the [Formula: see text] precursors. Comparative studies of the structure, magnetization, and superconductivity on the parent A 0.80Fe1.81Se2 and the ion-exchanged ([Formula: see text])OHFeSe crystals are discussed. A phase diagram including antiferromagnetic spin density wave and superconducting phases is also proposed.

  6. Crystal structures and hydrogen bonding in the isotypic series of hydrated alkali metal (K, Rb and Cs) complexes with 4-amino­phenyl­arsonic acid

    PubMed Central

    Smith, Graham; Wermuth, Urs D.

    2017-01-01

    The structures of the alkali metal (K, Rb and Cs) complex salts with 4-amino­phenyl­arsonic acid (p-arsanilic acid) manifest an isotypic series with the general formula [M 2(C6H7AsNO3)2(H2O)3], with M = K {poly[di-μ3-4-amino­phenyl­arsonato-tri-μ2-aqua-dipotassium], [K2(C6H7AsNO3)2(H2O)3], (I)}, Rb {poly[di-μ3-4-amino­phenyl­arsonato-tri-μ2-aqua-dirubidium], [Rb2(C6H7AsNO3)2(H2O)3], (II)}, and Cs {poly[di-μ3-4-amino­phenyl­arsonato-tri-μ2-aqua-dirubidium], [Cs2(C6H7AsNO3)2(H2O)3], (III)}, in which the repeating structural units lie across crystallographic mirror planes containing two independent and different metal cations and a bridging water mol­ecule, with the two hydrogen p-arsanilate ligands and the second water mol­ecule lying outside the mirror plane. The bonding about the two metal cations in all complexes is similar, one five-coordinate, the other progressing from five-coordinate in (I) to eight-coordinate in both (II) and (III), with overall M—O bond-length ranges of 2.694 (5)–3.009 (7) (K), 2.818 (4)–3.246 (4) (Rb) and 2.961 (9)–3.400 (10) Å (Cs). The additional three bonds in (II) and (III) are the result of inter-metal bridging through the water ligands. Two-dimensional coordination polymeric structures with the layers lying parallel to (100) are generated through a number of bridging bonds involving the water mol­ecules (including hydrogen-bonding inter­actions), as well as through the arsanilate O atoms. These layers are linked across [100] through amine N—H⋯O hydrogen bonds to arsonate and water O-atom acceptors, giving overall three-dimensional network structures. PMID:28217343

  7. Crystal structures and hydrogen bonding in the isotypic series of hydrated alkali metal (K, Rb and Cs) complexes with 4-amino-phenyl-arsonic acid.

    PubMed

    Smith, Graham; Wermuth, Urs D

    2017-02-01

    The structures of the alkali metal (K, Rb and Cs) complex salts with 4-amino-phenyl-arsonic acid (p-arsanilic acid) manifest an isotypic series with the general formula [M2(C6H7AsNO3)2(H2O)3], with M = K {poly[di-μ3-4-amino-phenyl-arsonato-tri-μ2-aqua-dipotassium], [K2(C6H7AsNO3)2(H2O)3], (I)}, Rb {poly[di-μ3-4-amino-phenyl-arsonato-tri-μ2-aqua-dirubidium], [Rb2(C6H7AsNO3)2(H2O)3], (II)}, and Cs {poly[di-μ3-4-amino-phenyl-arsonato-tri-μ2-aqua-dirubidium], [Cs2(C6H7AsNO3)2(H2O)3], (III)}, in which the repeating structural units lie across crystallographic mirror planes containing two independent and different metal cations and a bridging water mol-ecule, with the two hydrogen p-arsanilate ligands and the second water mol-ecule lying outside the mirror plane. The bonding about the two metal cations in all complexes is similar, one five-coordinate, the other progressing from five-coordinate in (I) to eight-coordinate in both (II) and (III), with overall M-O bond-length ranges of 2.694 (5)-3.009 (7) (K), 2.818 (4)-3.246 (4) (Rb) and 2.961 (9)-3.400 (10) Å (Cs). The additional three bonds in (II) and (III) are the result of inter-metal bridging through the water ligands. Two-dimensional coordination polymeric structures with the layers lying parallel to (100) are generated through a number of bridging bonds involving the water mol-ecules (including hydrogen-bonding inter-actions), as well as through the arsanilate O atoms. These layers are linked across [100] through amine N-H⋯O hydrogen bonds to arsonate and water O-atom acceptors, giving overall three-dimensional network structures.

  8. Local and Cooperative Jahn-Teller Effect and Resultant Magnetic Properties of M2AgF4 (M = Na-Cs) Phases.

    PubMed

    Kurzydłowski, Dominik; Jaroń, Tomasz; Ozarowski, Andrew; Hill, Stephen; Jagličić, Zvonko; Filinchuk, Yaroslav; Mazej, Zoran; Grochala, Wojciech

    2016-11-07

    The crystal structure, magnetic properties, heat capacity, and Raman spectra of double-perovskite M2AgF4 (M = K, K3/4Rb1/4, K1/2Rb1/2, K1/4Rb3/4, and Rb) phases have been examined, adding to the body of previous results for the M = Na, Cs derivatives. The results suggest that double-perovskite K2AgF4 adopts a disordered orthorhombic Bmab structure with an antiferrodistortive arrangement of the elongated and tilted [AgF6] octahedra rather than the structure with the ferrodistortive arrangement of compressed octahedra, as suggested previously (Mazej, Z.; Goreshnik, E.; Jagličić, Z.; Gaweł, B.; Łasocha, W.; Grzybowska, D.; Jaroń, T.; Kurzydłowski, D.; Malinowski, P. J.; Koźmiński, W.; Szydłowska, J.; Leszczyński, P. J.; Grochala, W. KAgF3, K2AgF4 and K3Ag2F7: important steps towards a layered antiferromagnetic fluoroargentate(II). CrystEngComm 2009, 11, 1702-1710). A re-examination of the previously collected single-crystal X-ray diffraction data confirms the current structure assignment, and it is also in agreement with recent theoretical calculations. High-field electron paramagnetic resonance spectra reaffirm the presence of elongated [AgF6] octahedra in the crystal structure of all M2AgF4 phases studied. The local structure of the M = K derivative is most complex, with regions of the sample that are quite orthorhombically distorted, whereas other regions more closely resemble the tetragonal phase. The mixed-cation K/Rb phases are also inhomogeneous, containing regions of the pure K compound and regions of another high-symmetry phase (likely tetragonal) of a mixed (Rb-richer) compound with unknown composition. The temperature-resolved phase diagram of all K/Rb phases has been established and positioned within the entire M = Na, K, Rb, Cs series.

  9. Effect of Rb2O and Cs2O on Inclusion Removal in 321 Stainless Steels Using Novel Basic Tundish Fluxes

    NASA Astrophysics Data System (ADS)

    Choi, Kyunsuk; Kang, Youngjo; Sohn, Il

    2016-06-01

    Inclusion removal and modification of the 321 stainless steel using Rb2O- and Cs2O-containing novel basic tundish flux has been investigated. The average inclusion diameter was significantly lowered after reaction of the liquid metal with the flux after 45 minutes in an induction furnace set at 1823 K (1550 °C) under an Ar atmosphere. The number of inclusions was also decreased with increased reaction time and the majority of the inherent TiN inclusions were removed after reaction with the proposed novel basic tundish flux. Spinel inclusions were also observed after the reaction, which was due to the reaction of the MgO crucible and the CaO-Al2O3-SiO2-MgO-` x'wt pct R2O flux system at fixed CaO/(Al2O3 + SiO2) of 1.45. The Rb2O and Cs2O seemed to have allowed significant removal of the TiN inclusions due to its ion compensation effect and the supplement of free oxygen ions, while increasing the viscosity of the slag to retain the absorbed inclusions.

  10. Simultaneous use of Cs and Rb Rydberg atoms for dipole moment assessment and RF electric field measurements via electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Simons, Matt T.; Gordon, Joshua A.; Holloway, Christopher L.

    2016-09-01

    We demonstrate simultaneous electromagnetically-induced transparency (EIT) with cesium (Cs) and rubidium (Rb) Rydberg atoms in the same vapor cell with coincident (overlapping) optical fields. Each atomic system can detect radio frequency (RF) electric (E) field strengths through the modification of the EIT signal (Autler-Townes (AT) splitting), which leads to a direct International System of Unit traceable RF E-field measurement. We show that these two systems can detect the same RF E-field strength simultaneously, which provides a direct in situ comparison of Rb and Cs RF measurements in Rydberg atoms. In effect, this allows us to perform two measurements of the same E-field strength, providing a relative comparison of the dipole moments of the two atomic species. This gives two measurements that help rule out systematic effects and uncertainties in this E-field metrology approach, which are important when establishing an international measurement standard for an E-field strength, and is a necessary step for this method to be accepted as a standard calibration technique. We use this approach to measure E-fields at 9.2 GHz, 11.6 GHz, and 13.4 GHz, which correspond to three different atomic states (different principal atomic numbers and angular momentums) for the two atom species.

  11. Electronic structure in a one-Fe Brillouin zone of the iron pnictide superconductors CsFe2As2 and RbFe2As2

    NASA Astrophysics Data System (ADS)

    Kong, S.; Liu, D. Y.; Cui, S. T.; Ju, S. L.; Wang, A. F.; Luo, X. G.; Zou, L. J.; Chen, X. H.; Zhang, G. B.; Sun, Z.

    2015-11-01

    Using angle-resolved photoemission spectroscopy, we studied the electronic structures of CsFe2As2 and RbFe2As2 . Contrary to other iron-based superconductors where the band structures are usually depicted in the two-Fe Brillouin zone (BZ), we found that the distribution of electronic spectral weight in CsFe2As2 and RbFe2As2 follows the one-Fe BZ, and that the emerging band structure is qualitatively consistent with theoretical band calculations of the one-Fe BZ except for some shadow band effect. Our data suggest that the interlayer separation is an important tuning factor for the physics of FeAs layers, the increase of which can reduce the coupling between Fe and As and lead to the emergence of the electronic structure in accord with the one-Fe symmetry of the Fe square lattice. Our finding puts strong constraints on the theoretical models constructed on the basis of the one-Fe BZ.

  12. 87Rb spin-lattice relaxation times in ferroelectric-paraelectric-incommensurate phases of Rb2CoBr4 using static NMR and MAS NMR

    NASA Astrophysics Data System (ADS)

    Lim, Ae Ran

    2017-04-01

    To better elucidate the structural properties of Rb2CoBr4 in paraelectric, incommensurate, and ferroelectric phases, we studied the 87Rb nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times in laboratory frame T1 and in rotating frame T1ρ. The resonance frequency and the chemical shift do not change abruptly near the phase transition temperature of Ti = 333 K and TC = 192 K, whereas T1 and T1ρ display discontinuous changes near Ti and TC. The abrupt changes in the relaxation times near these temperatures seem to be a result of the structural phase transitions. The results are distinctly different from those reported for Rb2CoCl4.

  13. Low-Temperature Antiferromagnetic Behavior of α-Rb 2FeF 5 · H 2O and α-Cs 2FeF 5 · H 2O

    NASA Astrophysics Data System (ADS)

    Calage, Y.; Reiff, W. M.

    1994-08-01

    D.C. susceptibility and zero field Mössbauer spectroscopy measurements are used to characterize the low-temperature magnetism of α-Rb2FeF5 · H2O and α-Cs2FeF5 · H2O. The compounds are rigorously isotypic quasi-1D Heisenberg magnets based on hydrogen bonded chains of-{FeF5H2O}2- - pseudo-octahedra with intervening Rb+ and Cs+ cations that enhance the low dimensionality. The 1D antiferromagnetic effects appear comparable, Txmax(1D) ∼5 K, while their 3D ordering temperatures are quite different, TN(Rb+) = 4.0 K, TN (Cs+) = 2.7 K. The internal hyperfine fields extrapolated to T = 0 K are ∼ 51 T suggesting zero point spin reduction (∼15%) consistent with 1D behavior. High field d.c. susceptibility measurements for polycrystalline Cs2FeF5 · H2O suggest spin-flop behavior with HSF < 1 T. A qualitative comparison of the low-temperature magnetic properties of the F- and Cl- analogues for the series M2 FeX5 · H2O (M = NH+4, K+, Rb+, Cs+) is given.

  14. Structure and magnetism in hexagonal tungsten bronze metal oxides AM1/3W8/3O9 (A-K, Rb, Cs; M-Cr, Fe)

    NASA Astrophysics Data System (ADS)

    Ivanov, S. A.; Sahu, J. R.; Voronkova, V. I.; Mathieu, R.; Nordblad, P.

    2015-02-01

    The structure and magnetic properties of hexagonal tungsten bronzes AM1/3W8/3O9 (A-K+, Rb+, Cs+; M- Cr3+, Fe3+) have been investigated. Pure ceramic samples were synthesized by solid-state reaction. The samples have been studied by X-ray powder diffraction in combination with magnetic measurements. The compounds crystallize in hexagonal space group P63/mcm. The substitution of magnetic ions into the WO6 octahedra yields dilute antiferromagnetic Cr3+-O2--Cr3+ (or Fe3+-O2--Fe3+) superexchange interaction causing the appearance of short-range magnetic order at low temperatures. The antiferromagnetic character of the interaction is supported by negative values of the derived Curie-Weiss temperatures, θCW. The magnitude of θCW is found to decrease with increasing ionic radius of the A cation.

  15. Preparation of Porous Three-Dimensional Quaternary Thioantimonates(III) ACuSb2 S4 (A = Rb, Cs) through a Surfactant-Thermal Method.

    PubMed

    Shen, Yaying; Liu, Chang; Hou, Peipei; Zhi, Mingjia; Zhou, Chunmei; Chai, Wenxiang; Cheng, Jian-Wen; Liu, Yi; Zhang, Qichun

    2015-12-01

    Two novel porous three-dimensional (3D) quaternary thioantimonates(III) ACuSb2S4 (A = Rb, Cs) were successfully synthesized by employing the neutral surfactant PEG-400 (PEG = polyethyleneglycol) as reaction media, these are significantly different from the known quaternary A-Cu-Sb-S thioantimonates(III) with two-dimensional (2D) crystal structures. This is the first time that crystalline quaternary chalcogenides have been prepared in surfactant media. Both experimental and theoretical studies confirm they are semiconductors with narrow band gaps. Our results demonstrated that the surfactant-thermal strategy could offer a new opportunity to explore novel chalcogenides with diverse crystal structures and interesting physicochemical properties.

  16. Double Salts Obtained from Me+X-Cu X2-H 2O Systems ( Me+ = K +, NH +4, rb +, cs +; X- = cl -, br -)

    NASA Astrophysics Data System (ADS)

    Tepavitcharova, St.; Balarew, Chr.; Trendafilova, St.

    1995-02-01

    The solubility diagrams of the Me+ Br-CuBr2-H2O (Me+ = K+, NH+4, Rb+, Cs+) systems are studied. The results obtained are compared with literature data on the corresponding chloride systems in order to estimate the effect of the halide ion (Br- or Cl-) on the solubility diagrams and on the compositions of the double salts formed in these systems. The differences in composition and structure of the double salts are explained by the metal-ligand interactions on the basis of Pearson's concept of hard and soft Lewis acids and bases, as well as by crystal chemistry considerations for the most probable spacial situation of the building elements in the crystal structure.

  17. First-principles study of the magnetic and electronic properties of AMnAs (A=Li, Na, K, Rb, Cs)

    NASA Astrophysics Data System (ADS)

    Zhou, Wenqi; Wu, Shuxiang; Li, Shuwei

    2016-12-01

    Recent studies have demonstrated that antiferromagnetic (AFM) semiconductors are promising alternative materials for spintronic applications. In this work, we report a detailed investigation of the magnetic and electronic properties of AMnAs (A=Li, Na, K, Rb, Cs) using density functional theory. It is found that all studied compounds are ordered antiferromagnetically in the MnAs ab plane, however, along the c axis, NaMnAs is ordered ferromagnetically which is different from the AFM coupling of other materials. These results on magnetic structures are in good agreement with observed facts. Furthermore, our calculations predict that all materials have a semiconducting band structure, which indicates the potential of device applications.

  18. Giant magnetoresistance of novel ferromagnets AMg4Mn6O15 (A=K, Rb, and Cs) with highly symmetric structure

    NASA Astrophysics Data System (ADS)

    Tanaka, Yudai; Sato, Hirohiko

    2017-04-01

    A novel family of cubic manganese oxides, AMg4Mn6O15 (A=K, Rb, and Cs), were discovered. In this type of structure, the MnO6 octahedra share edges, constructing a highly symmetric framework where Mn atoms form a three-dimensional network of truncated octahedra. The crystallographic site of Mn is unique and the average oxidation state of Mn is 3.5, indicating a mixed-valence electronic state where Mn3+ and Mn4+ sites are completely indistinguishable. These compounds become ferromagnetic with fully polarized magnetic moments of Mn ions. The ferromagnetic transition temperature TC is 170 K, that is considerably high for manganese oxides. The electric resistivity of KMg4Mn6O15 is about 105 Ωcm at 300 K and exhibits a non-metallic temperature dependence. It reveals a large negative magnetoresistance; about 40% of the resistivity is suppressed by 5 T of magnetic field at TC.

  19. Synthesis and structure of R{sub 2}[UO{sub 2}(NO{sub 3}){sub 2}(NCS){sub 2}] (R = Rb or Cs)

    SciTech Connect

    Serezhkin, V. N.; Peresypkina, E. V.; Grigor’eva, V. A.; Virovets, A. V.; Serezhkina, L. B.

    2015-01-15

    Crystals Rb{sub 2}[UO{sub 2}(NO{sub 3}){sub 2}(NCS){sub 2}] (I) and Cs{sub 2}[UO{sub 2}(NO{sub 3}){sub 2}(NCS){sub 2}] (II) have been synthesized and studied by IR spectroscopy and X-ray diffraction. Crystals I are monoclinic, with the following parameters: a = 12.2118(5) Å, b = 10.2545(3) Å, c = 11.8754(4) Å, β = 110.287(1)°, sp. gr. C2/c, Z = 4, and R = 0.0523. Crystals II are orthorhombic, with a = 13.7309(3) Å, b = 10.5749(2) Å, c = 10.1891(2) Å, sp. gr. Pnma, Z = 4, and R = 0.0411. The basic structural units of crystals I and II are one-core complexes [UO{sub 2}(NO{sub 3}){sub 2}(NCS){sub 2}]{sup 2−}, which belong to the crystallochemical group cis-AB{sub 2}{sup 01}M{sub 2}{sup 1} (A = UO{sub 2}{sup 2+}, B{sup 01} = NO{sub 3}{sup −}, M{sup 1} = NCS{sup −}), which are combined into a framework via electrostatic interactions with ions of alkaline metals R (R = Rb or Cs). The structural features of crystals I and II, which condition the formation of [UO{sub 2}(NO{sub 3}){sub 2}(NCS){sub 2}]{sup 2−} complexes with a cis rather than a trans position of isothiocyanate ions in the coordination sphere of uranyl ions, are discussed.

  20. Incoherence-coherence crossover and low-temperature Fermi-liquid-like behavior in AFe2As2 (A  =  K, Rb, Cs): evidence from electrical transport properties

    NASA Astrophysics Data System (ADS)

    Xiang, Z. J.; Wang, N. Z.; Wang, A. F.; Zhao, D.; Sun, Z. L.; Luo, X. G.; Wu, T.; Chen, X. H.

    2016-10-01

    We study the normal-state transport properties of AFe2As2 (A  =  K, Rb and Cs) single crystals using Hall coefficient, resistivity and magnetoresistance (MR) measurements. In all three materials, the Hall coefficient R H shows a strong temperature dependence, which is typical for multi-band systems. In particular, R H develops an upturn below a characteristic temperature {{T}\\ast} , which is in agreement with the incoherence-coherence crossover reported in recent nuclear magnetic resonance studies. A Fermi-liquid-like state, characterized by T 2 behavior of the resistivity and a positive orbital MR obeying Kohler’s rule, emerges below T FL  ˜0.4 ~{{T}\\ast} . The superconducting transition temperature T c experiences a simultaneous suppression with {{T}\\ast} and T FL as the alkali ion’s radius increases from A  =  K to A  =  Cs, suggesting that the unconventional superconductivity in the AFe2As2 series is related to the strength of the electronic coherence. A phase diagram, similar to that in the heavy fermion Kondo lattice system, is obtained. Based on all the experimental evidence, we argue that the physical properties of this family of heavily hole-doped Fe-based superconductors are controlled by the hybridization between itinerant carriers and localized orbitals, and the Kondo scenario could be effective in such a case.

  1. Off-resonance nutation nuclear magnetic resonance study of framework aluminosilicate glasses with Li, Na, K, Rb or Cs as charge-balancing cation.

    PubMed

    Dirken, P J; Nachtegaal, G H; Kentgens, A P

    1995-11-01

    Framework aluminosilicate glasses with varying charge-balancing cation (Li, Na, K, Rb and Cs) have been studied with 27Al and 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) and 27Al on-resonance and off-resonance nutation NMR spectroscopy. This first application of off-resonance nutation NMR to disordered samples proves that it is a promising technique for the determination of mean quadrupole interactions in amorphous systems. Linewidths for Al decrease systematically with increasing size of the cation, due to a decrease in the quadrupole interaction from 5.0 MHz for the Li glass to 2.8 MHz for the Cs glass. A simple point-charge model effectively predicts the decrease in the quadrupole interaction. This indicates that the alkali ion is located close to aluminum. Looking at the residual linewidth after subtraction of the quadrupole broadening, the Al chemical shift distribution does not change significantly with the type of alkali ion. The same is true for the observed Si linewidth.

  2. Pressure-induced phase transitions in multiferroic RbFe(MoO{sub 4}){sub 2}-Raman scattering study

    SciTech Connect

    Maczka, M.; Ptak, M.; Luz-Lima, C.; Freire, P.T.C.; Paraguassu, W.; Guerini, S.; Hanuza, J.

    2011-10-15

    High pressure Raman scattering experiments were performed on RbFe(MoO{sub 4}){sub 2}. These experiments revealed that two phase transitions take place in RbFe(MoO{sub 4}){sub 2} at very low pressures, i.e. between ambient pressure and 0.2 GPa and between 0.4 and 0.7 GPa. Raman results showed that at the first phase transition the room temperature P3-bar m1 phase transforms into the P3-bar phase, which is also observed at ambient pressure below 190 K. The second pressure-induced phase transition occurs into a low symmetry phase of unknown symmetry. The performed lattice dynamics calculations for the P3-bar m1 phase and ab initio calculation of the structural changes under hydrostatic pressure helped us to get better insights into the mechanism of the observed phase transitions. - Graphical abstract: Raman spectra of RbFe(MoO{sub 4}){sub 2} crystal in the high wavenumber region recorded at different pressures during compression experiment. Highlights: > RbFe(MoO{sub 4}){sub 2} exhibits two pressure-induced phase transitions below 0.7 GPa. > First phase transition is from the P3-bar m1 into P3-bar structure. > Phase transitions in RbFe(MoO{sub 4}){sub 2} are similar as in KFe(MoO{sub 4}){sub 2}. > Transitions' pressures are much lower for the rubidium compound.

  3. Pressure-induced phase transition in synthetic trioctahedral Rb-mica

    NASA Astrophysics Data System (ADS)

    Comodi, P.; Drábek, M.; Montagnoli, M.; Rieder, M.; Weiss, Z.; Zanazzi, P. F.

    The crystal structure of a synthetic Rb analog of tetra-ferri-annite (Rb-TFA) 1M with the composition Rb0.99Fe2+3.03(Fe3+ 1.04 Si2.96)O10.0(OH)2.0 was determined by the single-crystal X-ray diffraction method. The structure is homooctahedral (space group C2/m) with M1 and M2 occupied by divalent iron. Its unit cell is larger than that of the common potassium trioctahedral mica, and similar lateral dimensions of the tetrahedral and octahedral sheets allow a small tetrahedral rotation angle α=2.23(6)°. Structure refinements at 0.0001, 1.76, 2.81, 4.75, and 7.2 GPa indicate that in some respects the Rb-TFA behaves like all other micas when pressure increases: the octahedra are more compressible than the tetrahedra and the interlayer is four times more compressible than the 2:1 layer. However, there is a peculiar behavior of the tetrahedral rotation angle α: at lower pressures (0.0001, 1.76, 2.81 GPa), it has positive values that increase with pressure [from 2.23(6)° to 6.3(4)°] as in other micas, but negative values -7.5(5)° and -8.5(9)° appear at higher pressures, 4.75 and 7.2 GPa, respectively. This structural evidence, together with electrostatic energy calculations, shows that Rb-TFA has a Franzini A-type 2:1 layer up to at least 2.81 GPa that at higher pressure yields to a Franzini B-type layer, as shown by the refinements at 4.75 and 7.2 GPa. The inversion of the α angle is interpreted as a consequence of an isosymmetric displacive phase transition from A-type to B-type structure between 2.81 and 4.75 GPa. The compressibility of the Rb-TFA was also investigated by single-crystal X-ray diffraction up to a maximum pressure of 10 GPa. The lattice parameters reveal a sharp discontinuity between 3.36 and 3.84 GPa, which was associated with the phase transition from Franzini-A to Franzini-B structure.

  4. Experimental observation of structural phase transition in CsBr clusters

    NASA Astrophysics Data System (ADS)

    Hautala, L.; Jänkälä, K.; Löytynoja, T.; Mikkelä, M.-H.; Prisle, N.; Tchaplyguine, M.; Huttula, M.

    2017-01-01

    Formation and growth of CsBr clusters embedded in unsupported Ar clusters was studied using synchrotron radiation photoelectron spectroscopy. The development of the core-level electronic structure for cluster sizes between a few and a few hundred atoms contained information about the local coordination of the constituent particles. The experimental results indicate that a gradual structural phase transition from NaCl structure to CsCl structure for CsBr clusters takes place at around 160 atoms per cluster.

  5. A low phase noise microwave source for atomic spin squeezing experiments in 87Rb

    NASA Astrophysics Data System (ADS)

    Chen, Zilong; Bohnet, Justin G.; Weiner, Joshua M.; Thompson, James K.

    2012-04-01

    We describe and characterize a simple, low cost, low phase noise microwave source that operates near 6.800 GHz for agile, coherent manipulation of ensembles of 87Rb. Low phase noise is achieved by directly multiplying a low phase noise 100 MHz crystal to 6.8 GHz using a nonlinear transmission line and filtering the output with custom band-pass filters. The fixed frequency signal is single sideband modulated with a direct digital synthesis frequency source to provide the desired phase, amplitude, and frequency control. Before modulation, the source has a single sideband phase noise near -140 dBc/Hz in the range of 10 kHz-1 MHz offset from the carrier frequency and -130 dBc/Hz after modulation. The resulting source is estimated to contribute added spin-noise variance 16 dB below the quantum projection noise level during quantum nondemolition measurements of the clock transition in an ensemble 7 × 105 87Rb atoms.

  6. A low phase noise microwave source for atomic spin squeezing experiments in {sup 87}Rb

    SciTech Connect

    Chen Zilong; Bohnet, Justin G.; Weiner, Joshua M.; Thompson, James K.

    2012-04-15

    We describe and characterize a simple, low cost, low phase noise microwave source that operates near 6.800 GHz for agile, coherent manipulation of ensembles of {sup 87}Rb. Low phase noise is achieved by directly multiplying a low phase noise 100 MHz crystal to 6.8 GHz using a nonlinear transmission line and filtering the output with custom band-pass filters. The fixed frequency signal is single sideband modulated with a direct digital synthesis frequency source to provide the desired phase, amplitude, and frequency control. Before modulation, the source has a single sideband phase noise near -140 dBc/Hz in the range of 10 kHz-1 MHz offset from the carrier frequency and -130 dBc/Hz after modulation. The resulting source is estimated to contribute added spin-noise variance 16 dB below the quantum projection noise level during quantum nondemolition measurements of the clock transition in an ensemble 7 x 10{sup 5} {sup 87}Rb atoms.

  7. A low phase noise microwave source for atomic spin squeezing experiments in 87Rb.

    PubMed

    Chen, Zilong; Bohnet, Justin G; Weiner, Joshua M; Thompson, James K

    2012-04-01

    We describe and characterize a simple, low cost, low phase noise microwave source that operates near 6.800 GHz for agile, coherent manipulation of ensembles of (87)Rb. Low phase noise is achieved by directly multiplying a low phase noise 100 MHz crystal to 6.8 GHz using a nonlinear transmission line and filtering the output with custom band-pass filters. The fixed frequency signal is single sideband modulated with a direct digital synthesis frequency source to provide the desired phase, amplitude, and frequency control. Before modulation, the source has a single sideband phase noise near -140 dBc/Hz in the range of 10 kHz-1 MHz offset from the carrier frequency and -130 dBc/Hz after modulation. The resulting source is estimated to contribute added spin-noise variance 16 dB below the quantum projection noise level during quantum nondemolition measurements of the clock transition in an ensemble 7 × 10(5) (87)Rb atoms.

  8. Structural, electronic and thermodynamic properties of R{sub 3}ZnH{sub 5} (R=K, Rb, Cs): A first-principle calculation

    SciTech Connect

    Li, Jia; Zhang, Shengli; Huang, Shiping; Wang, Peng; Tian, Huiping

    2013-02-15

    R{sub 3}ZnH{sub 5} (R=K, Rb, Cs) series have been investigated with respect to the crystal structure, electronic and thermodynamic properties using first-principle methods based on density functional theory with generalized gradient approximation. The optimized structures and atomic coordinates are in good agreement with the experimental data. The strong covalent interactions are obtained between Zn and H atoms in the 18-electron [ZnH{sub 4}]{sup 2-} complex, while an ionic interaction is found between [ZnH{sub 4}]{sup 2-} and R atom. The formation enthalpies show that the formations of R{sub 3}ZnH{sub 5} hydrides are all exothermic at 298 K. The vibration free energies of R{sub 3}ZnH{sub 5} show that the thermodynamic stabilities of R{sub 3}ZnH{sub 5} hydrides decrease with the increasing diameter of R atom. Two possible decomposition reactions of R{sub 3}ZnH{sub 5} series have been suggested in our work. One (reaction one) is that R{sub 3}ZnH{sub 5} hydrides decomposes to elements directly, and the other (reaction two) is that R{sub 3}ZnH{sub 5} hydrides decomposes to RH hydride. The results show that the first decomposition reaction is more favorable one. The spontaneous decomposition reaction of K{sub 3}ZnH{sub 5} hydrides occur upon 465 K via reaction one, and 564 K via reaction two, respectively. - Graphical abstract: Total charge density of K{sub 3}ZnH{sub 5}. Highlights: Black-Right-Pointing-Pointer Electronic and thermodynamic properties of R{sub 3}ZnH{sub 5} (R=K, Rb, Cs) were calculated. Black-Right-Pointing-Pointer The formations of R{sub 3}ZnH{sub 5} hydrides are all exothermic at 298 K. Black-Right-Pointing-Pointer The thermodynamic stabilities decrease with the increasing diameter of R atom. Black-Right-Pointing-Pointer Two possible decomposition pathways of R{sub 3}ZnH{sub 5} were investigated.

  9. Structural, electronic and thermodynamic properties of R3ZnH5 (R=K, Rb, Cs): A first-principle calculation

    NASA Astrophysics Data System (ADS)

    Li, Jia; Zhang, Shengli; Huang, Shiping; Wang, Peng; Tian, Huiping

    2013-02-01

    R3ZnH5 (R=K, Rb, Cs) series have been investigated with respect to the crystal structure, electronic and thermodynamic properties using first-principle methods based on density functional theory with generalized gradient approximation. The optimized structures and atomic coordinates are in good agreement with the experimental data. The strong covalent interactions are obtained between Zn and H atoms in the 18-electron [ZnH4]2- complex, while an ionic interaction is found between [ZnH4]2- and R atom. The formation enthalpies show that the formations of R3ZnH5 hydrides are all exothermic at 298 K. The vibration free energies of R3ZnH5 show that the thermodynamic stabilities of R3ZnH5 hydrides decrease with the increasing diameter of R atom. Two possible decomposition reactions of R3ZnH5 series have been suggested in our work. One (reaction one) is that R3ZnH5 hydrides decomposes to elements directly, and the other (reaction two) is that R3ZnH5 hydrides decomposes to RH hydride. The results show that the first decomposition reaction is more favorable one. The spontaneous decomposition reaction of K3ZnH5 hydrides occur upon 465 K via reaction one, and 564 K via reaction two, respectively.

  10. The decays of three top contributors to the reactor ve high-energy spectrum, 92Rb, 96gsY, and 142Cs, studied with total absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Rasco, Bertis; MTAS Collaboration

    2016-09-01

    We report total absorption spectroscopy measurements of 92Rb, 96gsY, and 142Cs β decays, which are the most important contributors to the high energy ve spectral shape in nuclear reactors. The measurements were performed with the NaI(Tl) based Modular Total Absorption Spectrometer (MTAS). MTAS was constructed specifically to measure improved β-decay feeding patterns from neutron-rich nuclei, because it is difficult to measure β-decay feeding intensities with high energy precision γ-ray measurements due to the low efficiency of high precision detectors. Besides the impact to the high energy ve spectral shape in nuclear reactors, there are several other important applications of improved measurements of β-decay feeding patterns by total absorption spectroscopy; improve understanding of elemental abundances in the universe, help with stockpile stewardship, contribute to understanding of underlying nuclear structure, and improve measurements of decay heat. We will demonstrate some of the techniques for analyzing MTAS γ-decay data. This research was also sponsored by the Office of Nuclear Physics, U. S. Department of Energy under Contracts DE-AC05-00OR22725, DE-FG02-96ER40983, DE-FG02-96ER40978, and by the Polish National Science Center under Contract UMO-2013/08/T/ST2/00624.

  11. Vibrational properties of polymer and quenched CsC{60} phases

    NASA Astrophysics Data System (ADS)

    Sauvajol, J.-L.; Anglaret, E.; Chesnel, K.; Palpacuer, M.; Girard, A.; Moreac, A.; Ameline, J.-C.; Delugeard, Y.; Hennion, B.

    1998-06-01

    We report new results on the vibrational dynamics of polymer and quenched CSC{60} phases. Both the splitting and the structure of new activated lines of polymer CsC{60} are in agreement with the lowering of C{60} molecular symmetry from Ih to D{2h}. An inelastic neutron investigation on polymer and quenched CsC{60} is reported. It allows one to identify the vibrational signature of the low-temperature (T < 150 K) ordered monomer phase on quenched CsC{60}. Nous présentons un certain nombre de résultats originaux concernant la dynamique vibrationnelle de la phase polymère et des phases obtenues par trempe du CsC{60}. Les spectres infrarouge de la phase polymère sont interprétés dans le cadre d'un abaissement de la symétrie du monomère C{60} de Ih à D{2h}. Une étude par diffusion neutronique de la phase polymère et des phases obtenues par trempe a été réalisée. Elle a permis en particulier de déterminer la 'signature' vibrationnelle d'une phase ordonnée monomère à très basse température (T < 150 K) dans le CsC{60} trempé.

  12. The studies of density, apparent molar volume, and viscosity of bovine serum albumin, egg albumin, and lysozyme in aqueous and RbI, CsI, and DTAB aqueous solutions at 303.15 K.

    PubMed

    Singh, Man; Chand, Hema; Gupta, K C

    2005-06-01

    Density (rho), apparent molar volume (V(phi)), and viscosity (eta) of 0.0010 to 0.0018% (w/v) of bovine serum albumin (BSA), egg albumin, and lysozyme in 0.0002, 0.0004, and 0.0008 M aqueous RbI and CsI, and (dodecyl)(trimethyl)ammonium bromide (DTAB) solutions were obtained. The experimental data were regressed against composition, and constants are used to elucidate the conformational changes in protein molecules. With salt concentration, the density of proteins is found to decrease, and the order of the effect of additives on density is observed as CsI > RbI > DTAB. The trend of apparent molar volume of proteins is found as BSA > egg-albumin > lysozyme for three additives. In general, eta values of BSA remain higher for all compositions of RbI than that of egg-albumin for CsI and DTAB. These orders of the data indicate the strength of intermolecular forces between proteins and salts, and are helpful for understanding the denaturation of proteins.

  13. An unusual structural phase transition in Rb2HfF6

    NASA Astrophysics Data System (ADS)

    Dey, C. C.

    2015-03-01

    An unusual structural phase transition in the crystalline compound Rb2HfF6 near room temperature has been observed from perturbed angular correlation (PAC) spectroscopy. Our measurements in this compound produce two different crystalline configurations characterized by ωQ=74.1(1) Mrad/s, η~0, δ~0 and ωQ=24.7(2) Mrad/s, η=0.53(1), and δ=4(2)%. From PAC measurements in different samples, it is found that crystal structure corresponding to ωQ=74 Mrad/s, η~0 transforms to the other quite arbitrarily with temperature and no definite temperature corresponding to this transition has been observed. This can possibly be attributed to displacive phase transition.

  14. Rich structural chemistry in new alkali metal yttrium tellurites: three-dimensional frameworks of NaYTe4O10, KY(TeO3)2, RbY(TeO3)2, and a novel variant of hexagonal tungsten bronze, CsYTe3O8.

    PubMed

    Kim, Youngkwon; Lee, Dong Woo; Ok, Kang Min

    2015-01-05

    Pure polycrystalline phases and single crystals of four new quaternary alkali metal yttrium tellurites, NaYTe4O10, KY(TeO3)2, RbY(TeO3)2, and CsYTe3O8, have been prepared by solid-state and hydrothermal reactions using A2CO3 (A = Na, K, Rb, and Cs), Y(NO3)3·6H2O, Y2O3, and TeO2 as starting reagents. X-ray diffraction analyses suggest that NaYTe4O10 exhibits a highly symmetric three-dimensional (3D) framework consisting of YO8 square antiprisms and chains of TeO4 polyhedra. Within the framework, six- (6-) and eight-membered ring (8-MR) channels are observed. KY(TeO3)2 and RbY(TeO3)2 are isostructural to each other and reveal another 3D framework with structures containing YO6 octahedra and TeO3 trigonal pyramids with 4-MR and 12-MR channels. CsYTe3O8 shows a hexagonal tungsten bronze (HTB)-like topology composed of hexagonal tungsten oxide-like layers of TeO4 polyhedra and YO6 octahedral linkers with 3-MR and 6-MR channels. Thermal analyses, elemental analyses, and spectroscopic characterizations, such as UV-vis diffuse reflectance and infrared spectra, are presented, as are local dipole moment calculations for the constituent asymmetric polyhedra TeO3 and TeO4.

  15. Various disordered ground states and 1/3 magnetization-plateau-like behavior in the S =1/2 Ti3 + kagome lattice antiferromagnets Rb2NaTi3F12 , Cs2NaTi3F12 , and Cs2KTi3F12

    NASA Astrophysics Data System (ADS)

    Goto, Masato; Ueda, Hiroaki; Michioka, Chishiro; Matsuo, Akira; Kindo, Koichi; Yoshimura, Kazuyoshi

    2016-09-01

    We have investigated the crystal structure and magnetic properties of three kagome lattice antiferromagnets, Rb2Na Ti3F12 , Cs2Na Ti3F12 , and Cs2K Ti3F12 , using single crystals. These compounds represent a S =1 /2 kagome system consisting of magnetic Ti3 + ions, which is expected to have negligibly small Dzyaloshinsky-Moriya interaction. The structural analyses revealed that each of the three compounds has a slightly distorted kagome lattice. The distortion of the kagome lattice becomes small as the ionic radii of constituent alkali metals increase. All three compounds have nearly the same Weiss temperature of -45 K, and the ground states are disordered and strongly depend on the distortion. The ground states of Rb2Na Ti3F12 , Cs2Na Ti3F12 , and Cs2K Ti3F12 are found to be a two-component state including approximately 1/3 nearly free spins, a gapless disordered state, and a gapped disordered state, respectively. Our experimental results suggest that the ground state of the ideal S =1 /2 Heisenberg kagome lattice antiferromagnet is gapped. In addition, the magnetization curves of Cs2Na Ti3F12 and Cs2K Ti3F12 show anomalies at approximately 1/3 of the full magnetic moment of Ti3 +, which are a notable observation of signs of the theoretically proposed 1/3 magnetization plateau in S =1 /2 kagome antiferromagnets.

  16. A raman study of hydrostatic pressure induced phase transitions in Rb2KInF6 crystals

    NASA Astrophysics Data System (ADS)

    Vtyurin, A. N.; Krylov, A. S.; Goryainov, S. V.; Krylova, S. N.; Oreshonkov, A. S.; Voronov, V. N.

    2012-05-01

    The Raman spectra of the elpasolite (Rb2KInF6) crystal have been studied in the pressure range from 0 to 5.3 GPa at a temperature of 295 K. A phase transition at a pressure of approximately 0.9 GPa has been found. An analysis of the variations in the spectral parameters has led to the conclusion that the phase transition to a distorted phase is accompanied by the doubling of the volume of the primitive cell of the initial cubic phase. Numerical calculations of the lattice dynamics in the Rb2KInF6 crystal have been performed. The numerical simulation has established that the phase transition at a pressure of 0.9 GPa is associated with condensation of the F lg mode. A probable high-pressure phase is the phase with space group C2/ m.

  17. Pin1 inhibits PP2A-mediated Rb dephosphorylation in regulation of cell cycle and S-phase DNA damage

    PubMed Central

    Tong, Y; Ying, H; Liu, R; Li, L; Bergholz, J; Xiao, Z-X

    2015-01-01

    Inactivation of the retinoblastoma protein (Rb) has a key role in tumorigenesis. It is well established that Rb function is largely regulated by a dynamic balance of phosphorylation and dephosphorylation. Although much research has been done to understand the mechanisms and function of RB phosphorylation, the regulation of Rb dephosphorylation is still not well understood. In this study, we demonstrate that Pin1 has an important role in the regulation of Rb function in cell cycle progression and S-phase checkpoint upon DNA damage. We show that the Rb C-pocket directly binds to the Pin1 WW domain in vitro and in vivo, and that the phosphorylation of Rb C-pocket by G1/S Cyclin/Cyclin-dependent kinase complexes is critical for mediating this interaction. We further show that Rb-mediated cell cycle arrest and Rb-induced premature cellular senescence are effectively inhibited by Pin1 expression. In addition, DNA damage induces Rb dephosphorylation in a PP2A-dependent manner, and this process is inhibited by Pin1. Furthermore, the overexpression of Pin1 promotes Rb hyperphosphorylation upon S-phase DNA damage. Importantly, both the Pin1 WW domain and isomerase activity are required for its effect on S-phase checkpoint. Moreover, the overexpression of Pin1 is correlated with Rb hyperphosphorylation in breast cancer biopsies. These results indicate that Pin1 has a critical role in the modulation of Rb function by the regulation of Rb dephosphorylation, which may have an important pathological role in cancer development. PMID:25675300

  18. Pin1 inhibits PP2A-mediated Rb dephosphorylation in regulation of cell cycle and S-phase DNA damage.

    PubMed

    Tong, Y; Ying, H; Liu, R; Li, L; Bergholz, J; Xiao, Z-X

    2015-02-12

    Inactivation of the retinoblastoma protein (Rb) has a key role in tumorigenesis. It is well established that Rb function is largely regulated by a dynamic balance of phosphorylation and dephosphorylation. Although much research has been done to understand the mechanisms and function of RB phosphorylation, the regulation of Rb dephosphorylation is still not well understood. In this study, we demonstrate that Pin1 has an important role in the regulation of Rb function in cell cycle progression and S-phase checkpoint upon DNA damage. We show that the Rb C-pocket directly binds to the Pin1 WW domain in vitro and in vivo, and that the phosphorylation of Rb C-pocket by G1/S Cyclin/Cyclin-dependent kinase complexes is critical for mediating this interaction. We further show that Rb-mediated cell cycle arrest and Rb-induced premature cellular senescence are effectively inhibited by Pin1 expression. In addition, DNA damage induces Rb dephosphorylation in a PP2A-dependent manner, and this process is inhibited by Pin1. Furthermore, the overexpression of Pin1 promotes Rb hyperphosphorylation upon S-phase DNA damage. Importantly, both the Pin1 WW domain and isomerase activity are required for its effect on S-phase checkpoint. Moreover, the overexpression of Pin1 is correlated with Rb hyperphosphorylation in breast cancer biopsies. These results indicate that Pin1 has a critical role in the modulation of Rb function by the regulation of Rb dephosphorylation, which may have an important pathological role in cancer development.

  19. Spin Polarization of Rb and Cs n p P2 3/2 (n =5 , 6) Atoms by Circularly Polarized Photoexcitation of a Transient Diatomic Molecule

    NASA Astrophysics Data System (ADS)

    Mironov, A. E.; Hewitt, J. D.; Eden, J. G.

    2017-03-01

    We report the selective population of Rb or Cs n p P2 3/2 (n =5 , 6; F =4 , 5) hyperfine states by the photodissociation of a transient, alkali-rare gas diatomic molecule. Circularly polarized (σ-), amplified spontaneous emission (ASE) on the D2 line of Rb or Cs (780.0 and 852.1 nm, respectively) is generated when Rb-Xe or Cs-Xe ground state collision pairs are photoexcited by a σ+-polarized optical field having a wavelength within the D2 blue satellite continuum, associated with the B Σ2 1/2 +←X Σ2 1/2 + (free←free ) transition of the diatomic molecule. The degree of spin polarization of Cs (6 p P3/2 2 ), specifically, is found to be dependent on the interatomic distance (R ) at which the excited complex is born, a result attributed to the structure of the B Σ2 1/2 + state. For Cs-Xe atomic pairs, tuning the wavelength of the optical field from 843 to 848 nm varies the degree of circular polarization of the ASE from 63% to almost unity because of the perturbation, in the 5 ≤R ≤6 Å interval, of the Σ2 1/2 + potential by a d σ molecular orbital associated with a higher Λ 2 electronic state. Monitoring only the Cs 6 p P3/2 2 spin polarization reveals a previously unobserved interaction of CsXe (B Σ2 1/2 + ) with the lowest vibrational levels of a Λ 2 state derived from Cs (5 d )+Xe . By inserting a molecular intermediate into the alkali atom excitation mechanism, these experiments realize electronic spin polarization through populating no more than two n p P2 3/2 hyperfine states, and demonstrate a sensitive spectroscopic

  20. Rb(16)Cd(25.39(3))sb(36): an electron-deficient zintl phase containing infinite dodecahedron chains.

    PubMed

    Zheng, Wu-Zui; Wang, Peng; Wu, Li-Ming; Liu, Yi; Chen, Ling

    2010-07-05

    A novel ternary antimonide Rb(16)Cd(25.39(3))Sb(36) has been synthesized by a solid-state reaction of the appropriate amount of elements in a welded niobium tube at 530 degrees C. The compound crystallizes in orthorhombic space group Cmcm (No. 63) with a = 16.499(5) A, b = 12.391(4) A, c = 12.400(4) A, and Z = 1. The structure features a new 3D network constructed of chains of Rb(+)-centered dodecahedra running along [001]. The atomic distribution of the Cd(8)Sb(12) dodecahedron presents an energetically favored pattern without any Cd-Cd bonding. The formation of the phase and the occurrence of a very narrow phase width of Rb(16)Cd(24+x)Sb(36) [0.94(2) < or = x < or = 1.47(3)] have been studied in detail. The Fermi level of the title compound is expected to be located between those of the hypothetical models of "[Rb(16)Cd(24)Sb(36)](0)" (I, poor metallic) and "[Rb(16)Cd(24)Sb(36)] + 4e" (II, narrow-band-gap semiconductor), which agrees well with the experimental measurements. In the temperature range of 300-473 K, the as-synthesized Rb(16)Cd(25.39(3))Sb(36) exhibits p-type semiconductor behavior and shows temperature-independent thermal conductivities (around 0.49 W/m.K). The electrical conductivity, Seebeck coefficient, and figure of merit (ZT) of Rb(16)Cd(25.39(3))Sb(36) are temperature-dependent; these values are 57.4 S/cm, +81.4 microV/K, and 0.04, respectively, at 466 K.

  1. Phase stability, electronic structure and phonons in CsGeI3

    NASA Astrophysics Data System (ADS)

    Huang, Ling-Yi; Lambrecht, Walter

    Because Ge is smaller than Sn and Pb, CsGeI3 is promising to overcome the stability problems of the perovskite forms of CsSnI3 and CsPbI3 halides toward the denser yellow phase in which octahedra are edge as well as cornersharing in one dimensional chains. This phase has higher gaps and is unsuitable for photovoltaics. CsGeI3 and other trihalide germanates are found to exist in the cubic perovskite phase at high temperature but in a rhombohedral phase in which the Ge is displaced toward three of the halogen neighbors in its surrounding octahedron, accompanied by a rhombohedral distortion of the lattice vectors. We will present density functional total energy calculations and band structures obtained within the quasi-particle self-consistent GW method for both the cubic and rhombohedral phase of CsGeI3. For the latter, we find a gap of 1.6 eV in excellent agreement with recent experiments on its absorption edge. We will also present optical dielectric function and effective mass results for this material and discuss the trends for different types of distortions in halides depending on the chemical composition. The phonons at the Brillouin zone center are calculated and compared to experimental Raman spectra. NSF and DOE.

  2. Variable dimensionality and framework found in a series of quaternary zinc selenites, A2Zn3(SeO3)4·xH2O (A = Na, Rb, and Cs; 0≤x≤1) and Cs2Zn2(SeO3)3·2H2O

    NASA Astrophysics Data System (ADS)

    Lü, Minfeng; Jo, Hongil; Oh, Seung-Jin; Ok, Kang Min

    2017-01-01

    Five new alkali metal zinc selenites, A2Zn3(SeO3)4·xH2O (A = Na, Rb, and Cs; 0≤x≤1) and Cs2Zn2(SeO3)3·2H2O have been synthesized by heating a mixture of ZnO, SeO2 and A2CO3 (A = Na, Rb, and Cs), and characterized by X-ray diffraction (XRD) and spectroscopic analyses techniques. All of the reported materials revealed a rich structural chemistry with different frameworks and connection modes of Zn2+. While Rb2Zn3(SeO3)4 and Cs2Zn3(SeO3)4·H2O revealed three-dimensional frameworks consisting of isolated ZnO4 tetrahedra and SeO3 polyhedra, Na2Zn3(SeO3)4, Cs2Zn3(SeO3)4, and Cs2Zn2(SeO3)3·2H2O contained two-dimensional [Zn3(SeO3)4]2- layers. Specifically, whereas isolated ZnO4 tetrahedra and SeO3 polyhedra are arranged into two-dimensional [Zn3(SeO3)4]2- layers in two cesium compounds, circular [Zn3O10]14- chains and SeO3 linkers are formed in two-dimensional [Zn3(SeO3)4]2- layers in Na2Zn3(SeO3)4. Close structural examinations suggest that the size of alkali metal is significant in determining the framework geometry as well as connection modes of transition metal cations.

  3. High temperature redox reactions with uranium: Synthesis and characterization of Cs(UO2)Cl(SeO3), Rb2(UO2)3O2(SeO3)2, and RbNa5U2(SO4)7

    NASA Astrophysics Data System (ADS)

    Babo, Jean-Marie; Albrecht-Schmitt, Thomas E.

    2013-10-01

    Cs(UO2)Cl(SeO3) (1), Rb2(UO2)3O2(SeO3)3 (2), and RbNa5U2(SO4)7 (3) single crystals were synthesized using CsCl, RbCl, and a CuCl/NaCl eutectic mixture as fluxes, respectively. Their lattice parameters and space groups are as follows: P21/n (a=6.548(1) Å, b=11.052(2) Å, c=10.666(2) Å and β=93.897(3)°), P1bar (a=7.051(2) Å, b=7.198(2) Å, c=8.314(2) Å, α=107.897(3)°, β=102.687(3)° and γ=100.564(3)°) and C2/c (a=17.862(4) Å, b=6.931(1) Å, c=20.133(4) Å and β=109.737(6)°. The small anionic building units found in these compounds are SeO32- and SO42- tetrahedra, oxide, and chloride. The crystal structure of the first compound is composed of [(UO2)2Cl2(SeO3)2]2- chains separated by Cs+ cations. The structure of (2) is constructed from [(UO2)3O11]16- chains further connected through selenite units into layers stacked perpendicularly to the [0 1 0] direction, with Rb+ cations intercalating between them. The structure of compound (3) is made of uranyl sulfate layers formed by edge and vertex connections between dimeric [U2O16] and [SO4] polyhedra. These layers contain unusual sulfate-metal connectivity as well as large voids.

  4. Syntheses and crystal structures of two novel alkaline uranyl chromates A{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2} (A=Rb, Cs) with bidentate coordination mode of uranyl ions by chromate anions

    SciTech Connect

    Siidra, Oleg I.

    2012-03-15

    Single crystals of Cs{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2} and Rb{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2} were prepared by solid state reactions. The structures are based upon the [(UO{sub 2})(CrO{sub 4}){sub 2}]{sup 2-} chains. Within the chains, UrO{sub 5} pentagonal bipyramids (Ur=uranyl) form Ur{sub 2}O{sub 8} dimers, which are linked via CrO{sub 4} tetrahedra into one-dimensional chains. The CrO{sub 4} tetrahedra coordinate uranyl ions in both mono- and bidentate fashion, which is unusual for uranyl chromates. The bidentate coordination has a strong influence upon geometrical parameters of both U and Cr coordination polyhedra. The conformation of the chains in 1 and 2 is different due to the different size of the Cs{sup +} and Rb{sup +} cations. - Graphical abstract: Uranyl chromate chain with monodentate and bidentate coordination mode of uranyl cations by CrO{sub 4} tetrahedra in Cs{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2}. Highlights: Black-Right-Pointing-Pointer Single crystals of novel uranyl chromates were prepared by solid state reactions. Black-Right-Pointing-Pointer The CrO{sub 4} tetrahedra coordinate uranyl ions in both mono- and bidentate fashion. Black-Right-Pointing-Pointer The bidentate coordination has a strong influence upon geometrical parameters.

  5. Spectroscopic data, spin-orbit functions, and revised analysis of strong perturbative interactions for the A {sup 1{Sigma}+} and b {sup 3{Pi}} states of RbCs

    SciTech Connect

    Docenko, O.; Tamanis, M.; Ferber, R.; Bergeman, T.; Kotochigova, S.; Stolyarov, A. V.

    2010-04-15

    The current interest in producing ultracold RbCs molecules by optical excitation from weakly bound Feshbach resonances and stimulated decay to the absolute ground state requires detailed analyses of the intermediate excited states. In this study, we present two sets of experimental Fourier-transform spectroscopic data of the A {sup 1{Sigma}+}-b {sup 3{Pi}} complex. The A-b mixed vibrational levels are the most likely candidates to be intermediates in the molecular formation. The more recent and more accurate data set is from mixed A-b{yields}X transitions, while the second is derived in large part from (4) {sup 1{Sigma}+{yields}}A-b emission and extends to higher A-b energy levels. From a detailed analysis of the spectroscopic data we obtain term values which allow one to construct potentials and spin-orbit functions. Vibrational numbering of the A state has been raised by one quantum over a previous report [T. Bergeman et al., Phys. Rev. A 67, 050501 (2003)] while the numbering of the b state is established with a considerable degree of certainty with help of data on the {sup 85}Rb{sup 133}Cs and {sup 87}Rb{sup 133}Cs isotopomers. In addition, we have performed calculations of spin-orbit functions by two distinct methods. The fitted spin-orbit coupling matrix element between the two {Omega}{sup p}=0{sup +} states, A {sup 1{Sigma}+} and b {sup 3{Pi}}{sub 0+}, happens to agree rather well with the results from both of these methods, while for the diagonal b {sup 3{Pi}} state spin-orbit function, the fitted function agrees fairly well with that obtained by the other method.

  6. Syntheses and characterization of one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs)

    SciTech Connect

    Yohannan, Jinu P.; Vidyasagar, Kanamaluru

    2015-01-15

    Three new isostructural quaternary antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) have been synthesized by using alkali metal thiosulfate flux and structurally characterized by X-ray diffraction. Their structures contain A{sup +} ions around the [Sb{sub 2}Sn{sub 3}S{sub 10}]{sup 2−} chains, which are built from SbS{sub 3} pyramids, SnS{sub 6} octahedra and SnS{sub 4} tetrahedra. Raman and Mössbauer spectroscopic measurements corroborate the oxidation states and coordination environments of Sb(III) and Sn(IV). All three compounds are wide band gap semiconductors. Potassium compound undergoes partial exchange with strontium, cadmium and lead ions. - Graphical abstract: Syntheses, crystal structure, spectroscopic and partial ion-exchange studies of new one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) are described. - Highlights: • Syntheses of new alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs). • Wide band gap semiconductors with one-dimensional structure. • Topotactic partial exchange of K{sup +} ions of K{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} with Sr{sup 2+}, Cd{sup 2+} and Pb{sup 2+} ions.

  7. Pressure-induced phase transitions of β-type pyrochlore CsTaWO6

    DOE PAGES

    Zhang, F. X.; Tracy, C. L.; Shamblin, J.; ...

    2016-09-30

    The β-type pyrochlore CsTaWO6 was studied by synchrotron X-ray diffraction (XRD) and Raman scattering methods up to pressures of 43 GPa using a diamond anvil cell (DAC). With increasing pressure, the cubic pyrochlore in space group of Fd-3¯m with combining macron]m transforms to an orthorhombic structure (space group: Pnma) at 5.9 GPa and then to a monoclinic structure (space group: P21/c) at ~18 GPa. The structural evolution in CsTaWO6 is a continuous process and experimental results suggest that the initial cubic phase has a tetragonal distortion at ambient conditions. Both XRD and Raman measurements indicate that the pressure-induced phase transitionsmore » in CsTaWO6 are reversible. Lastly, these results may provide a structural explanation of previous experimental resistivity measurement results for the isostructural superconductor K(Cs)Os2O6 at high pressure conditions.« less

  8. The determination of potential energy curve and dipole moment of the (5)0{sup +} electronic state of {sup 85}Rb{sup 133}Cs molecule by high resolution photoassociation spectroscopy

    SciTech Connect

    Yuan, Jinpeng; Zhao, Yanting Ji, Zhonghua; Li, Zhonghao; Xiao, Liantuan; Jia, Suotang; Kim, Jin-Tae

    2015-12-14

    We present the formation of ultracold {sup 85}Rb{sup 133}Cs molecules in the (5)0{sup +} electronic state by photoassociation and their detection via resonance-enhanced two-photon ionization. Up to v = 47 vibrational levels including the lowest v = 0 vibrational and lowest J = 0 levels are identified with rotationally resolved high resolution photoassociation spectra. Precise Dunham coefficients are determined for the (5)0{sup +} state with high accuracy, then the Rydberg-Klein-Rees potential energy curve is derived. The electric dipole moments with respect to the vibrational numbers of the (5)0{sup +} electronic state of {sup 85}Rb{sup 133}Cs molecule are also measured in the range between 1.9 and 4.8 D. These comprehensive studies on previously unobserved rovibrational levels of the (5)0{sup +} state are helpful to understand the molecular structure and discover suitable transition pathways for transferring ultracold atoms to deeply bound rovibrational levels of the electronic ground state.

  9. Decays of the Three Top Contributors to the Reactor ν[over ¯]_{e} High-Energy Spectrum, ^{92}Rb, ^{96gs}Y, and ^{142}Cs, Studied with Total Absorption Spectroscopy.

    PubMed

    Rasco, B C; Wolińska-Cichocka, M; Fijałkowska, A; Rykaczewski, K P; Karny, M; Grzywacz, R K; Goetz, K C; Gross, C J; Stracener, D W; Zganjar, E F; Batchelder, J C; Blackmon, J C; Brewer, N T; Go, S; Heffron, B; King, T; Matta, J T; Miernik, K; Nesaraja, C D; Paulauskas, S V; Rajabali, M M; Wang, E H; Winger, J A; Xiao, Y; Zachary, C J

    2016-08-26

    We report total absorption spectroscopy measurements of ^{92}Rb, ^{96gs}Y, and ^{142}Cs β decays, which are the most important contributors to the high energy ν[over ¯]_{e} spectral shape in nuclear reactors. These three β decays contribute 43% of the ν[over ¯]_{e} flux near 5.5 MeV emitted by nuclear reactors. This ν[over ¯]_{e} energy is particularly interesting due to spectral features recently observed in several experiments including the Daya Bay, Double Chooz, and RENO Collaborations. Measurements were conducted at Oak Ridge National Laboratory by means of proton-induced fission of ^{238}U with on-line mass separation of fission fragments and the Modular Total Absorption Spectrometer. We observe a β-decay pattern that is similar to recent measurements of ^{92}Rb, with a ground-state to ground-state β feeding of 91(3)%. We verify the ^{96gs}Y ground-state to ground-state β feeding of 95.5(20)%. Our measurements substantially modify the β-decay feedings of ^{142}Cs, reducing the β feeding to ^{142}Ba states below 2 MeV by 32% when compared with the latest evaluations. Our results increase the discrepancy between the observed and the expected reactor ν[over ¯]_{e} flux between 5 and 7 MeV, the maximum excess increases from ∼10% to ∼12%.

  10. Decays of the Three Top Contributors to the Reactor ν¯e High-Energy Spectrum, 92Rb, Ygs96 , and 142Cs, Studied with Total Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rasco, B. C.; Wolińska-Cichocka, M.; Fijałkowska, A.; Rykaczewski, K. P.; Karny, M.; Grzywacz, R. K.; Goetz, K. C.; Gross, C. J.; Stracener, D. W.; Zganjar, E. F.; Batchelder, J. C.; Blackmon, J. C.; Brewer, N. T.; Go, S.; Heffron, B.; King, T.; Matta, J. T.; Miernik, K.; Nesaraja, C. D.; Paulauskas, S. V.; Rajabali, M. M.; Wang, E. H.; Winger, J. A.; Xiao, Y.; Zachary, C. J.

    2016-08-01

    We report total absorption spectroscopy measurements of 92Rb, Ygs96 , and 142Cs β decays, which are the most important contributors to the high energy ν¯e spectral shape in nuclear reactors. These three β decays contribute 43% of the ν¯e flux near 5.5 MeV emitted by nuclear reactors. This ν¯e energy is particularly interesting due to spectral features recently observed in several experiments including the Daya Bay, Double Chooz, and RENO Collaborations. Measurements were conducted at Oak Ridge National Laboratory by means of proton-induced fission of 238U with on-line mass separation of fission fragments and the Modular Total Absorption Spectrometer. We observe a β -decay pattern that is similar to recent measurements of 92Rb, with a ground-state to ground-state β feeding of 91(3)%. We verify the Ygs96 ground-state to ground-state β feeding of 95.5(20)%. Our measurements substantially modify the β -decay feedings of 142Cs, reducing the β feeding to 142Ba states below 2 MeV by 32% when compared with the latest evaluations. Our results increase the discrepancy between the observed and the expected reactor ν¯e flux between 5 and 7 MeV, the maximum excess increases from ˜10 % to ˜12 %.

  11. Low temperature phase transition and crystal structure of CsMgPO{sub 4}

    SciTech Connect

    Orlova, Maria; Khainakov, Sergey; Michailov, Dmitriy; Perfler, Lukas; Langes, Christoph; Kahlenberg, Volker; Orlova, Albina

    2015-01-15

    CsMgPO{sub 4} doped with radioisotopes is a promising compound for usage as a radioactive medical source. However, a low temperature phase transition at temperatures close to ambient conditions (∼−40 °C) was observed. Information about such kind of structural changes is important in order to understand whether it can cause any problem for medical use of this compound. The phase transition has been investigated in detail using synchrotron powder diffraction, Raman spectroscopy and DFT calculations. The structure undergoes a transformation from an orthorhombic modification, space group Pnma (RT phase) to a monoclinic polymorph, space group P2{sub 1}/n (LT phase). New LT modification adopts similar to RT but slightly distorted unit cell: a=9.58199(2) Å, b=8.95501(1) Å, c=5.50344(2) Å, β=90.68583(1)°, V=472.198(3) Å{sup 3}. CsMgPO{sub 4} belongs to the group of framework compounds and is made up of strictly alternating MgO{sub 4}- and PO{sub 4}-tetrahedra sharing vertices. The cesium counter cations are located in the resulting channel-like cavities. Upon the transformation a combined tilting of the tetrahedra is observed. A comparison with other phase transitions in ABW-type framework compounds is given. - Graphical abstract: Structural behavior of β-tridymite-type phosphate CsMgPO{sub 4}, considered as potential chemical form for radioactive Cs-source has been studied at near ambient temperatures. A phase transition at (∼−40 °C) has been found and investigated. It has been established that the known orthorhombic RT modification, space group Pnma, adopts a monoclinic cell with space group P2{sub 1}/n at low temperatures. In this paper, we present results of structural analysis of changes accompanying this phase transition and discuss its possible impact on the application properties. - Highlights: • β-Tridymite type phosphate CsMgPO{sub 4} undergoes so called translationengleiche phase transition of index 2 at −40 °C. • The structure

  12. High-Pressure Phase Transition in Cs 2KMnF 6

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Söderberg, K.; Norrestam, R.

    2000-09-01

    The stability of the cubic high-temperature (HT) form of Cs2KMnF6, with an elpasolite structure, is studied at elevated pressures. The present study shows that the HT form of Cs2KMnF6 undergoes a pressure-induced phase transition at 40 kbar to a more ordered high-pressure (HP) phase of lower symmetry. The space group symmetry of the HP phase, I4/mmm, is the same as that observed for the low-temperature (LT) phase. High-pressure studies performed on the LT phase indicated no transitions up to 50 kbar and gave compressibility features similar to those obtained for the HP phase. Single-crystal X-ray diffraction data for the HP phase were collected at 44 kbar. Refining nine structural parameters against 69 independent significant reflections gave a linear R value of 0.072 (wR=0.086). The values of the positional parameters are in agreement with those observed for the LT phase under ambient conditions. The transition characteristics for the HT form depend on the crystal quality and/or the pressure transmitting media used. With liquid argon, loaded into the pressure cell at low temperature and ambient pressure, the transition pressure became 30 kbar. With methanol:ethanol:water, loaded under ambient conditions, the transition was observed at 40 kbar.

  13. A Phase Ia Study to Assess the Safety and Immunogenicity of New Malaria Vaccine Candidates ChAd63 CS Administered Alone and with MVA CS

    PubMed Central

    de Barra, Eoghan; Hodgson, Susanne H.; Ewer, Katie J.; Bliss, Carly M.; Hennigan, Kerrie; Collins, Ann; Berrie, Eleanor; Lawrie, Alison M.; Gilbert, Sarah C.; Nicosia, Alfredo

    2014-01-01

    Background Plasmodium falciparum (P. falciparum) malaria remains a significant cause of mortality and morbidity throughout the world. Development of an effective vaccine would be a key intervention to reduce the considerable social and economic impact of malaria. Methodology We conducted a Phase Ia, non-randomized, clinical trial in 24 healthy, malaria-naïve adults of the chimpanzee adenovirus 63 (ChAd63) and modified vaccinia virus Ankara (MVA) replication-deficient viral vectored vaccines encoding the circumsporozoite protein (CS) of P. falciparum. Results ChAd63-MVA CS administered in a heterologous prime-boost regime was shown to be safe and immunogenic, inducing high-level T cell responses to CS. With a priming ChAd63 CS dose of 5×109 vp responses peaked at a mean of 1947 SFC/million PBMC (median 1524) measured by ELIspot 7 days after the MVA boost and showed a mixed CD4+/CD8+ phenotype. With a higher priming dose of ChAd63 CS dose 5×1010 vp T cell responses did not increase (mean 1659 SFC/million PBMC, median 1049). Serum IgG responses to CS were modest and peaked at day 14 post ChAd63 CS (median antibody concentration for all groups at day 14 of 1.3 µg/ml (range 0–11.9), but persisted throughout late follow-up (day 140 median antibody concentration groups 1B & 2B 0.9 µg/ml (range 0–4.7). Conclusions ChAd63-MVA is a safe and highly immunogenic delivery platform for the CS antigen in humans which warrants efficacy testing. Trial Registration ClinicalTrials.gov NCT01450280 PMID:25522180

  14. Quantum Dot-Induced Phase Stabilization of ..alpha..-CsPbI3 Perovskite for High-Efficiency Photovoltaics

    SciTech Connect

    Swarnkar, Abhishek; Marshall, Ashley R.; Sanehira, Erin M.; Chernomordik, Boris D.; Moore, David T.; Christians, Jeffrey A.; Chakrabarti, Tamoghna; Luther, Joseph M.

    2016-10-07

    We show nanoscale phase stabilization of CsPbI3 quantum dots (QDs) to low temperatures that can be used as the active component of efficient optoelectronic devices. CsPbI3 is an all-inorganic analog to the hybrid organic cation halide perovskites, but the cubic phase of bulk CsPbI3 (..alpha..-CsPbI3) -- the variant with desirable band gap -- is only stable at high temperatures. We describe the formation of ..alpha..-CsPbI3 QD films that are phase-stable for months in ambient air. The films exhibit long-range electronic transport and were used to fabricate colloidal perovskite QD photovoltaic cells with an open-circuit voltage of 1.23 volts and efficiency of 10.77%. These devices also function as light-emitting diodes with low turn-on voltage and tunable emission.

  15. Quantum dot-induced phase stabilization of α-CsPbI3 perovskite for high-efficiency photovoltaics.

    PubMed

    Swarnkar, Abhishek; Marshall, Ashley R; Sanehira, Erin M; Chernomordik, Boris D; Moore, David T; Christians, Jeffrey A; Chakrabarti, Tamoghna; Luther, Joseph M

    2016-10-07

    We show nanoscale phase stabilization of CsPbI3 quantum dots (QDs) to low temperatures that can be used as the active component of efficient optoelectronic devices. CsPbI3 is an all-inorganic analog to the hybrid organic cation halide perovskites, but the cubic phase of bulk CsPbI3 (α-CsPbI3)-the variant with desirable band gap-is only stable at high temperatures. We describe the formation of α-CsPbI3 QD films that are phase-stable for months in ambient air. The films exhibit long-range electronic transport and were used to fabricate colloidal perovskite QD photovoltaic cells with an open-circuit voltage of 1.23 volts and efficiency of 10.77%. These devices also function as light-emitting diodes with low turn-on voltage and tunable emission.

  16. Superconductivity Emerging from an Electronic Phase Separation in the Charge Ordered Phase of RbFe2As2

    NASA Astrophysics Data System (ADS)

    Civardi, E.; Moroni, M.; Babij, M.; Bukowski, Z.; Carretta, P.

    2016-11-01

    75As, 87Rb, and 85Rb nuclear quadrupole resonance (NQR) and 87Rb nuclear magnetic resonance measurements in a RbFe2As2 iron-based superconductor are presented. We observe a marked broadening of the 75As NQR spectrum below T0≃140 K which is associated with the onset of a charge order in the FeAs planes. Below T0 we observe a power-law decrease in the 75As nuclear spin-lattice relaxation rate down to T*≃20 K . Below T* the nuclei start to probe different dynamics owing to the different local electronic configurations induced by the charge order. A fraction of the nuclei probes spin dynamics associated with electrons approaching a localization while another fraction probes activated dynamics possibly associated with a pseudogap. These different trends are discussed in light of an orbital selective behavior expected for the electronic correlations.

  17. High temperature redox reactions with uranium: Synthesis and characterization of Cs(UO{sub 2})Cl(SeO{sub 3}), Rb{sub 2}(UO{sub 2}){sub 3}O{sub 2}(SeO{sub 3}){sub 2}, and RbNa{sub 5}U{sub 2}(SO{sub 4}){sub 7}

    SciTech Connect

    Babo, Jean-Marie; Albrecht-Schmitt, Thomas E.

    2013-10-15

    Cs(UO{sub 2})Cl(SeO{sub 3}) (1), Rb{sub 2}(UO{sub 2}){sub 3}O{sub 2}(SeO{sub 3}){sub 3} (2), and RbNa{sub 5}U{sub 2}(SO{sub 4}){sub 7} (3) single crystals were synthesized using CsCl, RbCl, and a CuCl/NaCl eutectic mixture as fluxes, respectively. Their lattice parameters and space groups are as follows: P2{sub 1}/n (a=6.548(1) Å, b=11.052(2) Å, c=10.666(2) Å and β=93.897(3)°), P1{sup ¯} (a=7.051(2) Å, b=7.198(2) Å, c=8.314(2) Å, α=107.897(3)°, β=102.687(3)° and γ=100.564(3)°) and C2/c (a=17.862(4) Å, b=6.931(1) Å, c=20.133(4) Å and β=109.737(6)°. The small anionic building units found in these compounds are SeO{sub 3}{sup 2−} and SO{sub 4}{sup 2−} tetrahedra, oxide, and chloride. The crystal structure of the first compound is composed of [(UO{sub 2}){sub 2}Cl{sub 2}(SeO{sub 3}){sub 2}]{sup 2−} chains separated by Cs{sup +} cations. The structure of (2) is constructed from [(UO{sub 2}){sub 3}O{sub 11}]{sup 16−} chains further connected through selenite units into layers stacked perpendicularly to the [0 1 0] direction, with Rb{sup +} cations intercalating between them. The structure of compound (3) is made of uranyl sulfate layers formed by edge and vertex connections between dimeric [U{sub 2}O{sub 16}] and [SO{sub 4}] polyhedra. These layers contain unusual sulfate–metal connectivity as well as large voids. - Graphical abstract: A new family of uranyl selenites and sulfates has been prepared by high-temperature redox reactions. This compounds display new bonding motifs. Display Omitted - Highlights: • Low-dimensional Uranyl Oxoanion compounds. • Conversion of U(IV) to U(VI) at high temperatures. • Dimensional reduction by both halides and stereochemically active lone-pairs.

  18. High-pressure phase transition and equation of state of CsI

    NASA Technical Reports Server (NTRS)

    Mao, H. K.; Hemley, R. J.; Chen, L. C.; Shu, J. F.; Wu, Y.

    1990-01-01

    Stuructural properties of CsI at high pressure have been investigated by the use of synchrotron X-ray-diffraction techniques with the diamond-anvil cell at 300 K. The results indicate that the material undergoes a continuous distortion from B2 to an hcp-like phase, which is stable to at least 302 GPa. The intermediate orthorhombic phase is geometrically different from previous assignments and about 10 percent denser. With the new structure, the p-V results of static pressure experiments, shock-wave studies, and theoretical calculations are now in good agreement.

  19. Structures of the metallic and superconducting high pressure phases of solid CS2

    PubMed Central

    Zarifi, Niloofar; Liu, Hanyu; Tse, John S.

    2015-01-01

    First principles structural prediction and molecular dynamics (MD) calculations have been performed to examine the structures responsible for the recently reported metallic and superconducting phases of highly compressed CS2. The low pressure experimental molecular crystal structure was found to be metastable and transformed into a disordered structure above 10 GPa. At 60 GPa, the predicted low energy structures show molecular CS2 is separated into C and S dominant regions. A crystalline structure with the P21/m symmetry was found to be most stable from 60 to 120 GPa. The structure is formed from alternate layers of hexagonal C rings and S 2D-square-nets linked by C-S bonds. A non-crystalline structure with similar features structure is also predicted by MD calculations. Electron-phonon coupling calculations show this crystalline phase is superconductive. Contrary to the suggestions made from the experiments, no magnetism was found in all predicted low enthalpy high pressure structures. Moreover, the theoretical results do not support the proposal on the existence of hypervalent 6-coordinated carbon at 120 GPa. PMID:25982346

  20. Structures of the metallic and superconducting high pressure phases of solid CS2.

    PubMed

    Zarifi, Niloofar; Liu, Hanyu; Tse, John S

    2015-05-18

    First principles structural prediction and molecular dynamics (MD) calculations have been performed to examine the structures responsible for the recently reported metallic and superconducting phases of highly compressed CS2. The low pressure experimental molecular crystal structure was found to be metastable and transformed into a disordered structure above 10 GPa. At 60 GPa, the predicted low energy structures show molecular CS2 is separated into C and S dominant regions. A crystalline structure with the P21/m symmetry was found to be most stable from 60 to 120 GPa. The structure is formed from alternate layers of hexagonal C rings and S 2D-square-nets linked by C-S bonds. A non-crystalline structure with similar features structure is also predicted by MD calculations. Electron-phonon coupling calculations show this crystalline phase is superconductive. Contrary to the suggestions made from the experiments, no magnetism was found in all predicted low enthalpy high pressure structures. Moreover, the theoretical results do not support the proposal on the existence of hypervalent 6-coordinated carbon at 120 GPa.

  1. Extended Fourier-transform spectroscopy studies and deperturbation analysis of the spin-orbit coupled A{sup 1}Σ{sup +} and b{sup 3}Π states in RbCs

    SciTech Connect

    Kruzins, A.; Alps, K.; Docenko, O.; Klincare, I.; Tamanis, M.; Ferber, R.; Pazyuk, E. A.; Stolyarov, A. V.

    2014-11-14

    The article presents a study of the strongly spin-orbit coupled singlet A{sup 1}Σ{sup +} and triplet b{sup 3}Π states of the RbCs molecule, which provide an efficient optical path to transfer ultracold molecules to their rovibrational ground state. Fourier-transform A{sup 1}Σ{sup +} − b{sup 3}Π → X{sup 1}Σ{sup +} and (4){sup 1}Σ{sup +} → A{sup 1}Σ{sup +} − b{sup 3}Π laser-induced fluorescence (LIF) spectra were recorded for the natural mixture of the {sup 85}Rb{sup 133}Cs and {sup 87}Rb{sup 133}Cs isotopologues produced in a heat pipe oven. Overall 8730 rovibronic term values of A{sup 1}Σ{sup +} and b{sup 3}Π states were determined with an uncertainty of 0.01 cm{sup −1} in the energy range [9012, 14087] cm{sup −1}, covering rotational quantum numbers J ∈ [6, 324]. An energy-based deperturbation analysis performed in the framework of the four A{sup 1}Σ{sup +} − b{sup 3}Π{sub Ω=0,1,2} coupled-channels approach reproduces 97% of the experimental term values of both isotopologues with a standard deviation of 0.0036 cm{sup −1}. The reliability of the deperturbed mass-invariant potentials and spin-orbit coupling functions of the interacting A{sup 1}Σ{sup +} and b{sup 3}Π states is additionally proved by a good reproduction of the A − b → X and (4){sup 1}Σ{sup +} → A − b relative intensity distributions. The achieved accuracy of the A − b complex description allowed us to use the latter to assign the observed (5){sup 1}Σ{sup +} → A − b and (3){sup 1}Π → A − b transitions. As is demonstrated, LIF to the A − b complex becomes as informative as to the ground X{sup 1}Σ{sup +} state, which is confirmed by comparing the results of (4){sup 1}Σ{sup +} state analysis based on (4){sup 1}Σ{sup +} → A − b LIF with the data from V. Zuters et al. [Phys. Rev. A 87, 022504 (2013)] based on (4){sup 1}Σ{sup +} → X LIF.

  2. Synthesis and characterization of new fluoride-containing manganese vanadates A2Mn2V2O7F2 (A=Rb, Cs) and Mn2VO4F

    NASA Astrophysics Data System (ADS)

    Sanjeewa, Liurukara D.; McGuire, Michael A.; Smith Pellizzeri, Tiffany M.; McMillen, Colin D.; Ovidiu Garlea, V.; Willett, Daniel; Chumanov, George; Kolis, Joseph W.

    2016-09-01

    Large single crystals of A2Mn2V2O7F2 (A=Rb, Cs) and Mn2VO4F were grown using a high-temperature (~600 °C) hydrothermal technique. Single crystal X-ray diffraction and powder X-ray diffraction were utilized to characterize the structures, which both possess MnO4F2 building blocks. The A2Mn2V2O7F2 series crystallizes as a new structure type in space group Pbcn (No. 60), Z=4 (Rb2Mn2V2O7F2: a=7.4389(17) Å, b=11.574(3) Å, c=10.914(2) Å; Cs2Mn2V2O7F2: a=7.5615(15) Å, b=11.745(2) Å, c=11.127(2) Å). The structure is composed of zigzag chains of edge-sharing MnO4F2 units running along the a-axis, and interconnected through V2O7 pyrovanadate groups. Temperature dependent magnetic susceptibility measurements on this interesting one-dimensional structural feature based on Mn2+ indicated that Cs2Mn2V2O7F2 is antiferromagnetic with a Neél temperature, TN=~3 K and a Weiss constant, θ, of -11.7(1) K. Raman and infrared spectra were also analyzed to identify the fundamental V-O vibrational modes in Cs2Mn2V2O7F2. Mn2(VO4)F crystalizes in the monoclinic space group of C2/c (no. 15), Z=8 with unit cell parameters of a=13.559(2) Å, b=6.8036(7) Å, c=10.1408(13) Å and β=116.16(3)°. The structure is associated with those of triplite and wagnerite. Dynamic fluorine disorder gives rise to complex alternating chains of five-and six-coordinate Mn2+. These interpenetrating chains are additionally connected through isolated VO4 tetrahedra to form the condensed structure.

  3. RbCu 1.2Ag 3.8Se 3 and Cs 2Cu 2Sb 2Se 5: Novel Quaternary Intermetallics Synthesized from Superheated Organic Media

    NASA Astrophysics Data System (ADS)

    Chen, Zhen; Wang, Ru-Ji; Dilks, Kieran J.; Li, Jing

    1999-10-01

    Reactions in superheated ethylenediamine (en) solutions at 160°C resulted in two novel quaternary intermetallic copper selenides, RbCu1.2Ag3.8Se3(I) and Cs2Cu2Sb2Se5(II). Both I and II are metal rich and represent new layered structure types. Compound I crystallizes in the tetragonal crystal system, space group P4/nbm (No. 125) with a=5.991(1) Å, c=10.918(2) Å, Z=2, V=391.9(1) Å3, R1/wR2=0.0373/0.0458 for all reflections. Compound II belongs to the triclinic crystal system, space group Poverline1 (No. 2), a=7.645(1) Å, b=8.768(2) Å, c=10.264(1) Å, α=91.97(2)°, β=92.07(2)°, γ=103.05(1)°, Z=2, V=669.2(3) Å3, R1/wR2=0.0685/0.0740 for all reflections. I consists of 2∞[(Cu1.2Ag3.8Se3)-] layers and Rb+ counterions located between these layers. There are two types of metal-to-selenium coordination, a square planar (Ag) and a trigonal pyramidal (Cu/Ag). The Se(1) atom displays an unusual eight coordination with Ag and Cu. II contains alternating 2∞[(Cu2Sb2Se5)2-] anionic and Cs+ cationic layers. Each copper atom has a distorted tetrahedral coordination to four Se atoms, and each antimony atom bonds to three Se atoms to result in a trigonal pyramidal geometry. Both I and II are semiconductors with estimated band gaps of 0.7-0.8 and 1.2-1.3 eV, respectively.

  4. Diffusion of Ag, Au and Cs implants in MAX phase Ti3SiC2

    SciTech Connect

    Jiang, Weilin; Henager, Charles H.; Varga, Tamas; Jung, Hee Joon; Overman, Nicole R.; Zhang, Chonghong; Gou, Jie

    2015-05-16

    MAX phases (M: early transition metal; A: elements in group 13 or 14; X: C or N), such as titanium silicon carbide (Ti3SiC2), have a unique combination of both metallic and ceramic properties, which make them attractive for potential nuclear applications. Ti3SiC2 has been considered as a possible fuel cladding material. This study reports on the diffusivities of fission product surrogates (Ag and Cs) and a noble metal Au (with diffusion behavior similar to Ag) in this ternary compound at elevated temperatures, as well as in dual-phase nanocomposite of Ti3SiC2/3C-SiC and polycrystalline CVD 3C-SiC for behavior comparisons. Samples were implanted with Ag, Au or Cs ions and characterized with various methods, including x-ray diffraction, electron backscatter diffraction, energy dispersive x-ray spectroscopy, Rutherford backscattering spectrometry, helium ion microscopy, and transmission electron microscopy. The results show that in contrast to immobile Ag in 3C-SiC, there is a significant outward diffusion of Ag in Ti3SiC2 within the dual-phase nanocomposite during Ag ion implantation at 873 K. Similar behavior of Au in polycrystalline Ti3SiC2 was also observed. Cs out-diffusion and release from Ti3SiC2 occurred during post-implantation thermal annealing at 973 K. This study suggests caution and further studies in consideration of Ti3SiC2 as a fuel cladding material for advanced nuclear reactors operating at very high temperatures.

  5. Crystal structure and phase transition mechanisms in CsFe{sub 2}F{sub 6}

    SciTech Connect

    Molokeev, M.S.; Bogdanov, E.V.; Misyul, S.V.; Tressaud, A.; Flerov, I.N.

    2013-04-15

    For the first time, structural phase transitions induced by the temperature were found in A{sub x}M{sub x}{sup II}M{sub (1−x)}{sup III}F{sub 3} fluorides with the defect pyrochlore structure (Fd3{sup ¯}m, Z=8). The room temperature structure of CsFe{sub 2}F{sub 6} was determined using X-ray powder diffraction technique. This phase was found to be ordered with the Pnma space group. The study of the temperature stability of orthorhombic structure by differential scanning calorimeter between 100 K and 700 K has shown a succession of phase transitions. The Pnma (Z=4)→Imma (Z=4)→I4{sub 1}/amd (Z=4)→Fd3{sup ¯}m (Z=8) structural sequence was proposed to occur within a rather narrow temperature range 500–560 K. The mechanism of structural transition has been mainly associated with the rotation of (MF{sub 6}) octahedra and small displacements of some Fe atoms. This assumption is in good agreement with the low experimental entropy value, which is characteristic for displacive transformations. - Graphical abstract: Mechanism of phase transition between the HT cubic form of CsFe{sub 2}F{sub 6} at 573 K (left) and the room temperature orthorhombic form at 298 K (right). The grey rectangles are clusters of five FeF{sub 6} octahedra. Highlights: ► Structural transition found for the first time in CsFe{sub 2}F{sub 6} with defect pyrochlore type. ► Fe{sup II} and Fe{sup III} atoms are ordered in room temperature Pnma form of CsFe{sub 2}F{sub 6}. ► Pnma(Z=4)→Imma(Z=4)→I4{sub 1}/amd(Z=4)→Fd-3m(Z=8) transition sequence is proposed. ► Structural transition due to rotation of MF{sub 6} groups+small displacements of Fe atoms. ► The low value of the entropy is in agreement with a displacive-type transition.

  6. Mixed-metal uranium(VI) iodates: hydrothermal syntheses, structures, and reactivity of Rb[UO(2)(CrO(4))(IO(3))(H(2)O)], A(2)[UO(2)(CrO(4))(IO(3))(2)] (A = K, Rb, Cs), and K(2)[UO(2)(MoO(4))(IO(3))(2)].

    PubMed

    Sykora, Richard E; McDaniel, Steven M; Wells, Daniel M; Albrecht-Schmitt, Thomas E

    2002-10-07

    The reactions of the molecular transition metal iodates A[CrO(3)(IO(3))] (A = K, Rb, Cs) with UO(3) under mild hydrothermal conditions provide access to four new, one-dimensional, uranyl chromatoiodates, Rb[UO(2)(CrO(4))(IO(3))(H(2)O)] (1) and A(2)[UO(2)(CrO(4))(IO(3))(2)] (A = K (2), Rb (3), Cs (4)). Under basic conditions, MoO(3), UO(3), and KIO(4) can be reacted to form K(2)[UO(2)(MoO(4))(IO(3))(2)] (5), which is isostructural with 2 and 3. The structure of 1 consists of one-dimensional[UO(2)(CrO(4))(IO(3))(H(2)O)](-) ribbons that contain uranyl moieties bound by bridging chromate and iodate anions as well as a terminal water molecule to create [UO(7)] pentagonal bipyramidal environments around the U(VI) centers. These ribbons are separated from one another by Rb(+) cations. When the iodate content is increased in the hydrothermal reactions, the terminal water molecule is replaced by a monodentate iodate anion to yield 2-4. These ribbons can be further modified by replacing tetrahedral chromate anions with MoO(4)(2)(-) anions to yield isostructural, one-dimensional [UO(2)(MoO(4))(IO(3))(2)](2)(-) ribbons. Crystallographic data: 1, triclinic, space group P(-)1, a = 7.3133(5) A, b = 8.0561(6) A, c = 8.4870(6) A, alpha = 88.740(1) degrees, beta = 87.075(1) degrees, gamma = 71.672(1) degrees, Z = 2; 2, monoclinic, space group P2(1)/c, a = 11.1337(5) A, b = 7.2884(4) A, c = 15.5661(7) A, beta = 107.977(1) degrees, Z = 4; 3, monoclinic, space group P2(1)/c, a = 11.3463(6) A, b = 7.3263(4) A, c = 15.9332(8) A, beta = 108.173(1) degrees, Z = 4; 4, monoclinic, space group P2(1)/n, a = 7.3929(5) A, b = 8.1346(6) A, c = 22.126(2) A, beta = 90.647(1) degrees, Z = 4; 5, monoclinic, space group P2(1)/c, a = 11.3717(6) A, b = 7.2903(4) A, c = 15.7122(8) A, beta = 108.167(1) degrees, Z = 4.

  7. Hard Mode Raman Study of the Structural Phase Transitions in Mixed Rb(_1-x)K(_x)CaF(_3)

    NASA Astrophysics Data System (ADS)

    Daniel, P.; Toulouse, J.; Rousseau, M.

    1996-03-01

    The vibrational properties of mixed Rb(_1-x)K(_x)CaF(_3) (RKCF) perovskite crystals have been investigated by Raman spectroscopy between 10K and 325K. Over this temperature range, RKCF undergoes three structural phase transitions each marked by the appearance of new lines or splitting of the previously broad lines. We have indexed the spectrum focusing our attention on those lines corresponding to the broad modes. Their early appearances in the higher temperature cubic phase in which they should normally be Raman inactive is associated with the growth of precursor clusters and an intermediate disordered phase. Concurrently a central peak is observed at low frequency, the strength of which increases rapidly as the first transition is approached. The integrated intensities of the hard mode lines exhibit reproducible maxima at the two lower transitions. These effects and the extent of the precursor order are examined as a function of concentration (0.1

  8. Cs7Sm11[TeO3]12Cl16 and Rb7Nd11[TeO3]12Br16, the new tellurite halides of the tetragonal Rb6LiNd11[SeO3]12Cl16 structure type

    NASA Astrophysics Data System (ADS)

    Charkin, Dmitri O.; Black, Cameron; Downie, Lewis J.; Sklovsky, Dmitry E.; Berdonosov, Peter S.; Olenev, Andrei V.; Zhou, Wuzong; Lightfoot, Philip; Dolgikh, Valery A.

    2015-12-01

    Two new rare-earth - alkali - tellurium oxide halides were synthesized by a salt flux technique and characterized by single-crystal X-ray diffraction. The structures of the new compounds Cs7Sm11[TeO3]12Cl16 (I) and Rb7Nd11[TeO3]12Br16 (II) (both tetragonal, space group I4/mcm) correspond to the sequence of [MLn11(TeO3)12] and [M6X16] layers and bear very strong similarities to those of known selenite analogs. We discuss the trends in similarities and differences in compositions and structural details between the Se and Te compounds; more members of the family are predicted.

  9. Optical properties of Pb2 -based aggregated phases in CsBr Thin film and single crystal matrices

    NASA Astrophysics Data System (ADS)

    Nikl, M.; Nitsch, K.; Mihokova, E.; Polak, K.; Fabeni, P.; Pazzi, G. P.; Gurioli, M.; Phani, R.; Santucci, S.; Scacco, A.; Somma, F.

    Emission characteristics of CsPbBr3 and Cs4PbBr6 aggregates in CsBr bulk and thin film matrices are reported. The emission of the former aggregated phase is peaking about 520-560 nm. It shows small Stokes shift (50 meV) related to narrow free exciton emission line of sub-nanosecond decay times. Quantum size effect was evidenced for the aggregates of 6-7 nm in diameter. The Cs4PbBr6 aggregates show emission peak at 375 nm and overall emission characteristics are similar to those of KBr: Pb, which is explained by very close local arrangement of emission centres-(PbBr6)4- octahedra-in both structures.

  10. Vortex dynamics in phase separated Tl0.58Rb0.42Fe1.72Se2 crystals

    NASA Astrophysics Data System (ADS)

    Haberkorn, N.; Troiani, H.; Condó, A. M.; Wang, Hangdong; Mao, Qianhui; Fang, Minghu

    2016-12-01

    We report the critical current density Jc and the vortex dynamics in phase-separated Tl0.58Rb0.42Fe1.72Se2 crystals by performing magnetization measurements. Structural investigation reveals micro- and nanoscopic phase separation between 122 (superconducting) and 245 (not superconducting) phases. Micrometric phase separation refers to 245 islands with typical diameters of 2 μm embedded in a multiply-connected 122 superconducting network. Nanoscopic phase separation refers to 245 nanoprecipitates embedded in the 122 superconducting paths. The 245 nanoprecipitates with size comparable to the coherence length produce strong vortex pinning. It was observed that the temperature dependence of the flux creep rate presents a peak at intermediate temperatures and magnetic fields lower than 0.5 T. The peak is systematically suppressed as the magnetic field is increased, and it could be related with relaxation generated by double-kink excitations. Double-kinks are low-energy depinning excitations usually associated with strong pinning produced by correlated disorder.

  11. Direct ICP-MS determination of trace and ultratrace elements in geological materials after decomposition in a microwave oven. Part II. Quantitation of Ba, Cs, Ga, Hf, In, Mo, Nb, Pb, Rb, Sn, Sr, Ta and Tl.

    PubMed

    Gupta, J G; Bertrand, N B

    1995-12-01

    A new method has been developed for the rapid determination of traces of Ba, Cs, Ga, Hf, In, Mo, Nb, Pb, Rb, Sn, Sr, Ta and Tl in silicate rocks and lake, stream and river sediments. The method involved dissolution of samples in a microwave oven by heating in a pressure decomposition Teflon vessel with a mixture of HF + HNO(3) + HCl + H(3)BO(3) + EDTA followed by direct multielement determination using inductively coupled plasma-mass spectrometry (ICP MS ). The method is faster than conventional dissolution of samples by open vessel acid digestion and fusion and determination by instrumental methods. The accuracy and precision of the developed method were tested by replicate analyses of a number of international geochemical reference samples of established trace element contents. Satisfactory correlation with the "recommended" or "consensus" values was found and recoveries were in most cases 95-100%. New values for Ga, In, Nb and Tl in several international geochemical reference materials are first reported in this paper.

  12. Non-centrosymmetric Rb2Mn2(MoO4)3

    PubMed Central

    Bouzidi, Chahira; Zid, Mohamed Faouzi; Driss, Ahmed; Souilem, Amira

    2014-01-01

    The title compound, dirubidium dimanganese(II) tris­(tetra­oxo­molyb­date), Rb2Mn2(MoO4)3, was prepared by solid-state reactions. The structure can be described as being composed of MnO6 octa­hedra sharing corners with MoO4 tetra­hedra. The three-dimensional framework contains cavities in which the rubidium ions are located. The Rb+ cations are within distorted nine- and 12-vertex polyhedra. The pairs of different Mn2+ and Rb+ cations are each located on threefold rotation axes.. Rb2Mn2(MoO4)3 is isotypic with compounds of the Cs2 M 2Mo3O12 (M = Ni, Fe) family. A comparative structural description is provided between the structure of the title compound and those of related phases. Differences with structures such as alluaudite are discussed. PMID:25161508

  13. Effects of thermal and quantum fluctuations on the phase diagram of a spin-1 {sup 87}Rb Bose-Einstein condensate

    SciTech Connect

    Phuc, Nguyen Thanh; Kawaguchi, Yuki; Ueda, Masahito

    2011-10-15

    We investigate the effects of thermal and quantum fluctuations on the phase diagram of a spin-1 {sup 87}Rb Bose-Einstein condensate (BEC) under the quadratic Zeeman effect. Due to the large ratio of spin-independent to spin-dependent interactions of {sup 87}Rb atoms, the effect of noncondensed atoms on the condensate is much more significant than that in scalar BECs. We find that the condensate and spontaneous magnetization emerge at different temperatures when the ground state is in the broken-axisymmetry phase. In this phase, a magnetized condensate induces spin coherence of noncondensed atoms in different magnetic sublevels, resulting in temperature-dependent magnetization of the noncondensate. We also examine the effect of quantum fluctuations on the order parameter at absolute zero and find that the ground-state phase diagram is significantly altered by quantum depletion.

  14. Crystal Structure and Ionic Conductivity of Three Polymorphic Phases of Rubidium Trefluoromethyl Sulfonate, RbSO3CF3

    SciTech Connect

    Hildebrandt,L.; Dinnebier, R.; Jansen, M.

    2006-01-01

    The crystal structures of three polymorphic phases of rubidium trifluoromethyl sulfonate (RbSO{sub 3}CF{sub 3}, rubidium 'triflate') were solved from X-ray powder diffraction data. At room temperature, rubidium triflate crystallizes in the monoclinic space group Cm with lattice parameters of a = 19.9611(5) Angstroms, b = 23.4913(7) Angstroms, c = 5.1514(2) Angstroms, = 102.758(2); Z = 16. At T = 321 K, a first-order phase transition occurs toward a monoclinic phase in space group P2{sub 1} with lattice parameters at T = 344 K of a = 10.3434(5) Angstroms, b = 5.8283(3) Angstroms, c = 5.1982(3) Angstroms, = 104.278(6); Z = (2). At T = 461 K, another phase transition, this time of second order, occurs toward an orthorhombic phase in space group Cmcm with lattice parameters at T = 510 K of a = 5.3069(2) Angstroms, b = 20.2423(10) Angstroms, c = 5.9479(2) Angstroms; Z = 4. As a common feature within all three crystal structures of rubidium triflate, the triflate anions are arranged in double layers with the lipophilic CF{sub 3} groups facing each other. The rubidium ions are located between the SO{sub 3} groups. The general packing is similar to the packing in cesium triflate. Rubidium triflate can be classified as a solid electrolyte with a specific ionic conductivity of = 9.89 x 10{sup -9} S/cm at T = 384 K and = 3.84 x 10{sup -6} S/cm at T = 481 K.

  15. Theoretical investigation on reactivity of Ag and Au atoms toward CS2 in gas phase

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Yang, Ling; Tian, An-Min; Wong, Ning-Bew

    2008-02-01

    The reaction mechanisms of Ag and Au atoms with CS2 on both doublet and quartet potential energy surfaces (PESs) have been investigated using UBPW91 and UCCSD(T) methods. The two studied reactions proceed via a similar insertion-elimination mechanism instead of a direct abstract mechanism. The reaction Ag + CS2 --> SAgCS is endothermic by about 21E0 kcal/mol. But another reaction Au + CS2 --> SAuCS is slightly exothermic by about 8.8 kcal/mol, which is different from the previous theoretical prediction. In the overall reactions, the rate-determining step is found to be the C-S bond cleavage step with a high-activation barrier of about 40 kcal/mol. The calculated vibration frequencies are in good agreement with the experiment values and show that the BPW91 method is very good for the calculation of small molecules containing Ag and Au. The reactivity of the two atoms toward CS2 is compared with those of the first-row transition-metal atoms. The present study provides a detailed picture of the C-S bond activation and cleavage in carbon disulfide mediated by second and the third row transition-metal atoms Ag and Au.

  16. RABL6A promotes G1-S phase progression and pancreatic neuroendocrine tumor cell proliferation in an Rb1-dependent manner

    PubMed Central

    Hagen, Jussara; Muniz, Viviane P.; Falls, Kelly; Reed, Sara M.; Taghiyev, Agshin F.; Quelle, Frederick W.; Gourronc, Francoise; Klingelhutz, Aloysius J.; Major, Heather J.; Askeland, Ryan; Sherman, Scott K.; O'Dorisio, Thomas M.; Bellizzi, Andrew M.; Howe, James R.; Darbro, Benjamin W.; Quelle, Dawn E.

    2014-01-01

    Mechanisms of neuroendocrine tumor (NET) proliferation are poorly understood and therapies that effectively control NET progression and metastatic disease are limited. We found amplification of a putative oncogene, RABL6A, in primary human pancreatic NETs(PNETs) that correlated with high level RABL6A protein expression. Consistent with those results, stable silencing of RABL6A in cultured BON-1 PNET cells revealed that it is essential for their proliferation and survival. Cells lacking RABL6A predominantly arrested in G1 phase with a moderate mitotic block. Pathway analysis of microarray data suggested activation of the p53 and retinoblastoma (Rb1) tumor suppressor pathways in the arrested cells. Loss of p53 had no effect on the RABL6A knockdown phenotype, indicating RABL6A functions independent of p53 in this setting. By comparison, Rb1 inactivation partially restored G1 to S phase progression in RABL6A knockdown cells although it was insufficient to override the mitotic arrest and cell death caused by RABL6A loss. Thus, RABL6A promotes G1 progression in PNET cells by inactivating Rb1, an established suppressor of PNET proliferation and development. This work identifies RABL6A as a novel negative regulator of Rb1 that is essential for PNET proliferation and survival. We suggest RABL6A is a new potential biomarker and target for anticancer therapy in PNET patients. PMID:25273089

  17. RABL6A promotes G1-S phase progression and pancreatic neuroendocrine tumor cell proliferation in an Rb1-dependent manner.

    PubMed

    Hagen, Jussara; Muniz, Viviane P; Falls, Kelly C; Reed, Sara M; Taghiyev, Agshin F; Quelle, Frederick W; Gourronc, Francoise A; Klingelhutz, Aloysius J; Major, Heather J; Askeland, Ryan W; Sherman, Scott K; O'Dorisio, Thomas M; Bellizzi, Andrew M; Howe, James R; Darbro, Benjamin W; Quelle, Dawn E

    2014-11-15

    Mechanisms of neuroendocrine tumor (NET) proliferation are poorly understood, and therapies that effectively control NET progression and metastatic disease are limited. We found amplification of a putative oncogene, RABL6A, in primary human pancreatic NETs (PNET) that correlated with high-level RABL6A protein expression. Consistent with those results, stable silencing of RABL6A in cultured BON-1 PNET cells revealed that it is essential for their proliferation and survival. Cells lacking RABL6A predominantly arrested in G1 phase with a moderate mitotic block. Pathway analysis of microarray data suggested activation of the p53 and retinoblastoma (Rb1) tumor-suppressor pathways in the arrested cells. Loss of p53 had no effect on the RABL6A knockdown phenotype, indicating that RABL6A functions independent of p53 in this setting. By comparison, Rb1 inactivation partially restored G1 to S phase progression in RABL6A-knockdown cells, although it was insufficient to override the mitotic arrest and cell death caused by RABL6A loss. Thus, RABL6A promotes G1 progression in PNET cells by inactivating Rb1, an established suppressor of PNET proliferation and development. This work identifies RABL6A as a novel negative regulator of Rb1 that is essential for PNET proliferation and survival. We suggest RABL6A is a new potential biomarker and target for anticancer therapy in PNET patients.

  18. X-ray powder diffraction, vibration and thermal studies of [A{sub 0.92}(NH{sub 4}){sub 0.08}]{sub 2}TeCl{sub 4}Br{sub 2} with A = Cs, Rb: Influence of mixed cationic and anionic substitutions

    SciTech Connect

    Aribia, W. Ben; Abdelmouleh, M.; Kabadou, A.; Van Der Lee, A.

    2012-05-15

    Graphical abstract: The structures of [A{sub 0.92}(NH{sub 4}){sub 0.08}]{sub 2}TeCl{sub 4}Br{sub 2} with A = Cs, Rb belong to the tetragonal {beta}-K{sub 2}SnCl{sub 6} structure type. Highlights: Black-Right-Pointing-Pointer The two new compound crystallises in P4/mnc tetragonal space group. Black-Right-Pointing-Pointer The structure is considered as isolated octahedred TeCl{sub 4}Br{sup 2-}. Black-Right-Pointing-Pointer The octahedra connected by ionic and hydrogen bonding through the Cs/Rb or N atoms. Black-Right-Pointing-Pointer A DTA/TGA experiment reveals one endothermic peak at 780 K for these compounds. Black-Right-Pointing-Pointer One endothermic peak is detected at around 213 K by DSC experiment. -- Abstract: The crystal structures of [A{sub 0.92}(NH{sub 4}){sub 0.08}]{sub 2}TeCl{sub 4}Br{sub 2} with A = Cs, Rb have been determined using X-ray powder diffraction techniques. The two compounds crystallize in the tetragonal space group P4/mnc, with the unit cell parameters: a = 7.452(1) Angstrom-Sign , c = 10.544(3) Angstrom-Sign , Z = 2 and a = 7.315(2) Angstrom-Sign , c = 10.354(4) Angstrom-Sign , Z = 2 in the presence of Cs and Rb, respectively. These two compounds have an antifluorite-type arrangement of NH{sub 4}{sup +}/Rb{sup +}/Cs{sup +} and octahedral TeCl{sub 4}Br{sub 2}{sup 2-} anions. The stability of these structure is by ionic and hydrogen bonding contacts: A Midline-Horizontal-Ellipsis Cl, A Midline-Horizontal-Ellipsis Br and N-H Midline-Horizontal-Ellipsis Cl, N-H Midline-Horizontal-Ellipsis Br. The different vibrational modes of these powders were analysed by FTIR and Raman spectroscopic studies. A DTA/TGA experiment reveals one endothermic peak at 780 K implicating the decomposition of the sample. At low temperature, one endothermic peak in thermal behavior is detected at around 213 K by DSC experiment. This transition was confirmed by dielectric measurements.

  19. Series of M(I)[Co(bpy)3][Mo(CN)8] x nH2O (M(I) = Li (1), K (2), Rb (3), Cs (4); n = 7-8) exhibiting reversible diamagnetic to paramagnetic transition coupled with dehydration-rehydration process.

    PubMed

    Kozieł, Marcin; Podgajny, Robert; Kania, Rafał; Lebris, Rémy; Mathonière, Corine; Lewiński, Krzysztof; Kruczała, Krzysztof; Rams, Michał; Labrugère, Christine; Bousseksou, Azzedine; Sieklucka, Barbara

    2010-03-15

    In this paper we report the synthesis and the structural and magnetic properties of the series of ionic compounds with general formula: M(I)[Co(bpy)(3)][Mo(CN)(8)] x nH(2)O (M(I) = Li, n = 8 (1), M(I) = K, n = 8 (2), M(I) = Rb, n = 8 (3), M(I) = Cs, n = 7.5 (4)). Solids 1-4 are characterized by the optical outer-sphere metal-to-metal charge transfer (MMCT) transition from Mo(IV) center to Co(III) center in the visible region and the Co(III)Mo(IV) <==> Co(II)Mo(V) spin equilibrium strongly dominated by the Co(III)Mo(IV) form. We show a gentle thermal treatment of diamagnetic compounds 1-4 leading to the dehydrated forms 1a-4a, which reveal a significant increase of paramagnetic contribution (from 0.5 to 2% to 30-40%). The rehydration allows to recover the diamagnetic phases 1b-4b of compositions and properties similar to those of 1-4. The irradiation of the dehydrated form 2a within the MMCT band in the Superconducting Quantum Interference Device (SQUID) cavity at T = 10 K causes further increase of the Co(II)Mo(V) contribution giving the metastable phase annealed back to the 2a phase after heating above T = 290 K. The IR, electron paramagnetic resonance (EPR), and X-ray photoelectron spectroscopy (XPS) spectroscopic data along with the magnetic data are interpreted in terms of strong modification of the Co(III)Mo(IV) <==> Co(II)Mo(V) equilibrium occurring in these systems.

  20. Pressure-induced phase transitions of β-type pyrochlore CsTaWO6

    SciTech Connect

    Zhang, F. X.; Tracy, C. L.; Shamblin, J.; Palomares, R. I.; Lang, M.; Park, S.; Park, C.; Tkachev, S.; Ewing, R. C.

    2016-09-30

    The β-type pyrochlore CsTaWO6 was studied by synchrotron X-ray diffraction (XRD) and Raman scattering methods up to pressures of 43 GPa using a diamond anvil cell (DAC). With increasing pressure, the cubic pyrochlore in space group of Fd-3¯m with combining macron]m transforms to an orthorhombic structure (space group: Pnma) at 5.9 GPa and then to a monoclinic structure (space group: P21/c) at ~18 GPa. The structural evolution in CsTaWO6 is a continuous process and experimental results suggest that the initial cubic phase has a tetragonal distortion at ambient conditions. Both XRD and Raman measurements indicate that the pressure-induced phase transitions in CsTaWO6 are reversible. Lastly, these results may provide a structural explanation of previous experimental resistivity measurement results for the isostructural superconductor K(Cs)Os2O6 at high pressure conditions.

  1. Structures of Hydrated Alkali Metal Cations, M+(H2O)nAr (m = Li, Na, K, rb and Cs, n = 3-5), Using Infrared Photodissociation Spectroscopy and Thermodynamic Analysis

    NASA Astrophysics Data System (ADS)

    Ke, Haochen; van der Linde, Christian; Lisy, James M.

    2014-06-01

    Alkali metal cations play vital roles in chemical and biochemical systems. Lithium is widely used in psychiatric treatment of manic states and bipolar disorder; Sodium and potassium are essential elements, having major biological roles as electrolytes, balancing osmotic pressure on body cells and assisting the electroneurographic signal transmission; Rubidium has seen increasing usage as a supplementation for manic depression and depression treatment; Cesium doped compounds are used as essential catalysts in chemical production and organic synthesis. Since hydrated alkali metal cations are ubiquitous and the basic form of the alkali metal cations in chemical and biochemical systems, their structural and thermodynamic properties serve as the foundation for modeling more complex chemical and biochemical processes, such as ion transport and ion size-selectivity of ionophores and protein channels. By combining mass spectrometry and infrared photodissociation spectroscopy, we have characterized the structures and thermodynamic properties of the hydrated alkali metal cations, i.e. M+(H2O)nAr, (M = Li, Na, K, Rb and Cs, n = 3-5). Ab initio calculations and RRKM-EE (evaporative ensemble) calculations were used to assist in the spectral assignments and thermodynamic analysis. Results showed that the structures of hydrated alkali metal cations were determined predominantly by the competition between non-covalent interactions, i.e. the water---water hydrogen bonding interactions and the water---cation electrostatic interactions. This balance, however, is very delicate and small changes, i.e. different cations, different levels of hydration and different effective temperatures clearly impact the balance.

  2. Critical Phenomena at the Normal-Incommensurate Phase Transition in Rb2ZnCl4

    NASA Astrophysics Data System (ADS)

    Mashiyama, Hiroyuki

    1981-08-01

    The X-ray reflection intensity and the dielectric constant are measured around the normal-incommensurate phase transition. From the temperature dependence of a satellite reflection at \\includegraphics{dummy.eps}, the critical exponent 2β is determined to be 0.69± 0.01. This value is very close to the exponent of the three-dimensional n{=}2-vector model. The dielectric constant along the ferroelectric axis shows a weak anomaly at the transition point, which is discussed with the aid of the remormalization-group method.

  3. Shape and phase evolution from CsPbBr3 perovskite nanocubes to tetragonal CsPb2Br5 nanosheets with an indirect bandgap.

    PubMed

    Li, Guopeng; Wang, Hui; Zhu, Zhifeng; Chang, Yajing; Zhang, Ting; Song, Zihang; Jiang, Yang

    2016-09-13

    Tetragonal CsPb2Br5 nanosheets were obtained by an oriented attachment of orthorhombic CsPbBr3 nanocubes, involving a lateral shape evolution from octagonal to square. Meanwhile, the experimental results, together with DFT simulation results, indicated that the tetragonal CsPb2Br5 is an indirect bandgap semiconductor that is PL-inactive with a bandgap of 2.979 eV.

  4. Phase separation in iron chalcogenide superconductor Rb0.8+xFe1.6+ySe2 as seen by Raman light scattering and band structure calculations

    NASA Astrophysics Data System (ADS)

    Pashkevich, Yu.; Gnezdilov, V.; Lemmens, P.; Shevtsova, T.; Gusev, A.; Lamonova, K.; Wulferding, D.; Gnatchenko, S.; Pomjakushina, E.; Conder, K.

    2016-06-01

    We report Raman light scattering in the phase separated superconducting single crystal Rb0.77Fe1.61Se2 with Tc = 32 K over a wide temperature region 3-500 K. The observed phonon lines from the majority vacancy ordered Rb2Fe4Se5 (245) antiferromagnetic phase with TN = 525 K demonstrate modest anomalies in the frequency, intensity and halfwidth at the superconductive phase transition. We identify phonon lines from the minority compressed RbδFe2Se2 (122) conductive phase. The superconducting gap with d x 2 - y 2 symmetry has been detected in our spectra. In the range 0-600 cm-1 we observe a weak but highly polarized B1g-type background which becomes well-structured upon cooling. A possible magnetic or multiorbital origin of this background is discussed. We argue that the phase separation in M0.8+xFe1.6+ySe2 is of pure magnetic origin. It occurs below the Néel temperature when the magnetic moment of iron reaches a critical value. We state that there is a spacer between the majority 245 and minority 122 phases. Using ab initio spin-polarized band structure calculations we demonstrate that the compressed vacancy ordered Rb2Fe4Se5 phase can be conductive and therefore may serve as a protective interface spacer between the purely metallic RbδFe2Se2 phase and the insulating Rb2Fe4Se5 phase providing percolative Josephson-junction like superconductivity all throughout of Rb0.8+xFe1.6+ySe2. Our lattice dynamics calculations show significant differences in the phonon spectra of the conductive and insulating Rb2Fe4Se5 phases.

  5. Phase Transition in Cs 2KMnF 6: Crystal Structures of Low- and High-Temperature Modifications

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Carlson, S.; Sjödin, A.; Norrestam, R.

    2000-03-01

    Crystalline Cs2KMnF6, when prepared below 500°C, adopts a tetragonal elpasolite structure type. Differential scanning calorimetric investigations indicated that Cs2KMnF6 undergoes a phase transition from the low-temperature tetragonal phase (LT) to a high-temperature phase (HT) at about 530°C. Single crystals of the new HT phase could be obtained by annealing a crystalline LT specimen at 600°C followed by rapid quenching to room temperature. In the present study the structures of both phases have been studied by single-crystal X-ray diffraction techniques. The LT phase has the tetragonal space group symmetry I4/mmm, with unit-cell parameters a=6.319(1) (a·2=8.936) and c=9.257(2) Å, and Z=2. The HT phase has the cubic symmetry Fm3m, with the cell parameter a=9.067 Å and Z=4. Structural models of the LT and HT phases have been refined vs collected single-crystal X-ray reflection data to R values of 0.034 and 0.022, respectively. The uneven Mn-F bond distance distribution in the LT form, four bonds of 1.860(6) two of 2.034(9) Å, are typical for an octahedrally coordinated high-spin Mn3+ ion affected by Jahn-Teller effects. Due to symmetry constraints, all six octahedral Mn-F bonds in the HT form are equal to 1.931(5) Å. However, the mean square atomic displacement parameters of the fluorine atoms increases significantly from about 0.022 Å2 for the LT phase to 0.042 Å2 for the HT phase. The increased displacement parameters indicate that the phase transition from the LT to the HT form is associated with a directional disorder of the Jahn-Teller distortions around the Mn3+ ions.

  6. Synthesis and structural characterization of AMV2O8 (A = K, Rb, Tl, Cs; M = Nb, Ta) vanadates: a structural comparison of A(+)M(5+)V2O8 vanadates and A(+)M(5+)P2O8 phosphates.

    PubMed

    Paidi, Anil Kumar; Devi, R Nandini; Vidyasagar, Kanamaluru

    2015-10-21

    Eight new quaternary vanadates of niobium and tantalum, AMV2O8 (A = K, Rb, Tl, Cs; M = Nb, Ta), have been prepared by solid state reactions and structurally characterized by single crystal and powder X-ray diffraction (XRD) techniques. The two cesium compounds, unlike the known CsSbV2O8 with a layered yavapaiite structure, have a new three-dimensional structure and the other six compounds possess the known KSbV2O8 structure type. The three types of [(MV2O8)(-)]∞ anionic frameworks of twelve A(+)M(5+)V2O8 (A = K, Rb, Tl, Cs; M = Nb, Ta, Sb) vanadates could be conceived to be built by different connectivity patterns of M2V4O18 ribbons, which contain MO6 octahedra and VO4 tetrahedra. A structural comparison of these twelve vanadates and the nineteen A(+)M(5+)P2O8 phosphates has been made. The spectroscopic studies of these eight new quaternary vanadates are presented.

  7. Epitaxial growth of hexagonal tungsten bronze Cs x WO3 films in superconducting phase region exceeding bulk limit

    NASA Astrophysics Data System (ADS)

    Soma, Takuto; Yoshimatsu, Kohei; Ohtomo, Akira

    2016-07-01

    We report epitaxial synthesis of superconducting Cs x WO3 (x = 0.11, 0.20, and 0.31) films on Y-stabilized ZrO2 (111) substrates. The hexagonal crystal structure was verified not only for the composition within the stable region of the bulk (x = 0.20 and 0.31), but also for the out-of-range composition (x = 0.11). The onset of the superconducting transition was recorded at 5.8 K for x = 0.11. We found a strong correlation between the superconducting transition temperature (T C) and the c-axis length, irrespective of the Cs content. These results indicated that the hidden superconducting phase region of hexagonal tungsten bronze is accessible using epitaxial synthesis of lightly doped films.

  8. Two spatially separated phases in semiconducting Rb0.8Fe1.5S2

    SciTech Connect

    Wang, Meng; Tian, Wei; Valdivia, P.; Chi, Songxue; Bourret-Courchesne, E.; Dai, Pengcheng; Birgeneau, R. J.

    2014-09-26

    We report neutron scattering and transport measurements on semiconducting Rb0.8Fe1.5S2, a compound isostructural and isoelectronic to the well-studied A0.8FeySe2(A = K, Rb, Cs, Tl/K) superconducting systems. Both resistivity and DC susceptibility measurements reveal a magnetic phase transition at T = 275 K. Neutron diffraction studies show that the 275 K transition originates from a phase with rhombic iron vacancy order which exhibits an in-plane stripe antiferromagnetic ordering below 275 K. In addition, the stripe antiferromagnetic phase interdigitates mesoscopically with an ubiquitous phase with √5 x√5 iron vacancy order. This phase has a magnetic transition at TN = 425 K and an iron vacancy order-disorder transition at TS = 600 K. These two different structural phases are closely similar to those observed in the isomorphous Se materials. Based on the close similarities of the in-plane antiferromagnetic structures, moments sizes, and ordering temperatures in semiconducting Rb0.8Fe1.5S2 and K0.81Fe1.58Se2, we argue that the in-plane antiferromagnetic order arises from strong coupling between local moments. Superconductivity, previously observed in the A0.8FeySe2₋ zSz system, is absent in A0.8Fe1.5S2, which has a semiconducting ground state. We discuss the implied relationship between stripe and block antiferromagnetism and superconductivity in these materials as well as a strategy for further investigation.

  9. Cs{sub 7}Sm{sub 11}[TeO{sub 3}]{sub 12}Cl{sub 16} and Rb{sub 7}Nd{sub 11}[TeO{sub 3}]{sub 12}Br{sub 16}, the new tellurite halides of the tetragonal Rb{sub 6}LiNd{sub 11}[SeO{sub 3}]{sub 12}Cl{sub 16} structure type

    SciTech Connect

    Charkin, Dmitri O.; Black, Cameron; Downie, Lewis J.; Sklovsky, Dmitry E.; Berdonosov, Peter S.; Olenev, Andrei V.; Zhou, Wuzong; Lightfoot, Philip; Dolgikh, Valery A.

    2015-12-15

    Two new rare-earth – alkali – tellurium oxide halides were synthesized by a salt flux technique and characterized by single-crystal X-ray diffraction. The structures of the new compounds Cs{sub 7}Sm{sub 11}[TeO{sub 3}]{sub 12}Cl{sub 16} (I) and Rb{sub 7}Nd{sub 11}[TeO{sub 3}]{sub 12}Br{sub 16} (II) (both tetragonal, space group I4/mcm) correspond to the sequence of [MLn{sub 11}(TeO{sub 3}){sub 12}] and [M{sub 6}X{sub 16}] layers and bear very strong similarities to those of known selenite analogs. We discuss the trends in similarities and differences in compositions and structural details between the Se and Te compounds; more members of the family are predicted. - Graphical abstract: Two new rare-earth – alkali – tellurium oxide halides were predicted and synthesized. - Highlights: • Two new rare-earth – alkali – tellurium oxide halides were synthesized. • They adopt slab structure of rare earth-tellurium-oxygen and CsCl-like slabs. • The Br-based CsCl-like slabs have been observed first in this layered family.

  10. Guided ion beam and theoretical studies of the reaction of Ag{sup +} with CS{sub 2}: Gas-phase thermochemistry of AgS{sup +} and AgCS{sup +} and insight into spin-forbidden reactions

    SciTech Connect

    Armentrout, P. B.; Kretzschmar, Ilona

    2010-01-14

    The gas-phase reactivity of the atomic transition metal cation, Ag{sup +}, with CS{sub 2} is investigated using guided-ion beam mass spectrometry. Endothermic reactions forming AgS{sup +} and AgCS{sup +} are observed but are quite inefficient. This observation is largely attributed to the stability of the closed shell Ag{sup +}({sup 1}S,4d{sup 10}) ground state, but is also influenced by the fact that the reactions producing ground state AgS{sup +} and AgCS{sup +} products are both spin forbidden. Analysis of the kinetic energy dependence of the cross sections for formation of these two products yields the 0 K bond energies of D{sub 0}(Ag{sup +}-S)=1.40{+-}0.12 eV and D{sub 0}(Ag{sup +}-CS)=1.98{+-}0.14 eV. Quantum chemical calculations are used to investigate the electronic structure of the two product ions as well as the potential energy surfaces for reaction. The primary mechanism involves oxidative addition of a CS bond to the metal cation followed by simple Ag-S or Ag-CS bond cleavage. Crossing points between the singlet and triplet surfaces are located near the transition states for bond activation. Comparison with analogous work on other late second-row transition metal cations indicates that the location of the crossing points bears directly on the efficiency of these spin-forbidden processes.

  11. Temperature and composition phase diagram in the iron-based ladder compounds Ba 1 - x Cs x Fe 2 Se 3

    DOE PAGES

    Hawai, Takafumi; Nambu, Yusuke; Ohgushi, Kenya; ...

    2015-05-28

    We investigated the iron-based ladder compounds (Ba,Cs)Fe₂Se₃. Their parent compounds BaFe₂Se₃ and CsFe₂Se₃ have different space groups, formal valences of Fe, and magnetic structures. Electrical resistivity, specific heat, magnetic susceptibility, x-ray diffraction, and powder neutron diffraction measurements were conducted to obtain a temperature and composition phase diagram of this system. Block magnetism observed in BaFe₂Se₃ is drastically suppressed with Cs doping. In contrast, stripe magnetism observed in CsFe₂Se₃ is not so fragile against Ba doping. A new type of magnetic structure appears in intermediate compositions, which is similar to stripe magnetism of CsFe₂Se₃, but interladder spin configuration is different. Intermediatemore » compounds show insulating behavior, nevertheless a finite T-linear contribution in specific heat was obtained at low temperatures.« less

  12. Synthesis and structural characterization of the new clathrates K8Cd4Ge42, Rb8Cd4Ge42, and Cs8Cd4Ge42

    SciTech Connect

    Schafer, Marion; Bobev, Svilen

    2016-03-25

    This paper presents results from our exploratory work in the systems K-Cd-Ge, Rb-Cd-Ge, and Cs-Cd-Ge, which yielded the novel type-I clathrates with refined compositions K8Cd3.77(7)Ge42.23, Rb8Cd3.65(7)Ge42.35, and Cs7.80(1)Cd3.65(6)Ge42.35. The three compounds represent rare examples of clathrates of germanium with the alkali metals, where a d10 element substitutes a group 14 element. The three structures, established by single-crystal X-ray diffraction, indicate that the framework-building Ge atoms are randomly substituted by Cd atoms on only one of the three possible crystallographic sites. Furthermore, this and several other details of the crystal chemistry are elaborated.

  13. Low-temperature ordered phases of the spin-1/2 XXZ chain system Cs2CoCl4

    NASA Astrophysics Data System (ADS)

    Breunig, O.; Garst, M.; Rosch, A.; Sela, E.; Buldmann, B.; Becker, P.; Bohatý, L.; Müller, R.; Lorenz, T.

    2015-01-01

    In this study the magnetic order of the spin-1/2 XXZ chain system Cs2CoCl4 in a temperature range from 50 mK to 0.5 K and in applied magnetic fields up to 3.5 T is investigated by high-resolution measurements of the thermal expansion and the specific heat. Applying magnetic fields along a or c suppresses TN completely at about 2.1 T. In addition, we find an adjacent intermediate phase before the magnetization saturates close to 2.5 T. For magnetic fields applied along b , a surprisingly rich phase diagram arises. Two additional transitions are observed at critical fields μ0HS F 1≃0.25 T and μ0HS F 2≃0.7 T , which we propose to arise from a two-stage spin-flop transition.

  14. Magnetoelastic coupling within a Landau model of phase transitions: Application to the frustrated triangular antiferromagnet CsNiCl3

    NASA Astrophysics Data System (ADS)

    Quirion, G.; Han, X.; Plumer, M. L.

    2011-07-01

    A model Landau free energy is proposed in order to describe elastic coupling to spin degrees of freedom in systems exhibiting phase transitions which involve long-range magnetic order. Using rigourous symmetry arguments, various interaction terms are derived for magnetic materials with a hexagonal crystal structure. The model is applied to the frustrated triangular antiferromagnet CsNiCl3 and used to analyze and correlate a wide variety of experimental results such as the magnetic phase diagram, magnetization, strains, and elastic constant measurements at low temperatures. Good agreement between the model and the data is obtained for the temperature and magnetic field dependence of C33 and C66 in the vicinity of phase transitions. In particular, the analysis shows that the anomaly observed in the field dependence of C33, close to the spin-flop phase boundary (HSF≃2 T), is dominated by the field dependence of the magnetic susceptibility. It is also found that higher order magnetoelastic coupling terms are required to reproduce the qualitative behavior of the elastic constants in the vicinity of the phase transitions. Our results demonstrate that a straightforward mean-field model which incorporates the correct system symmetries provides a powerful tool for relating complex spin configurations to the elastic and other response functions. The present work also serves to complement and expand our earlier results [G. Quirion , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.97.077202 97, 077202 (2006)].

  15. Anomalous magnetic phase diagrams in the site-diluted Heisenberg antiferromagnets, A2Fe1- xInxCl5.H2O (A = Rb, K)

    NASA Astrophysics Data System (ADS)

    Campo, Javier; Palacio, Fernando; Morón, M. Carmen; Becerra, Carlos C.; Paduan-Filho, Armando

    1999-06-01

    The effect of the substitution of diamagnetic ions for paramagnetic ones in the magnetic phase diagrams of the low-anisotropy antiferromagnets A2Fe1-xInxCl5.H2O (A = Rb,K) is investigated. In the region where the spin-flop (SF) transition occurs, the consequences of dilution are manifested as the appearance of a structure of secondary transition lines and a substantial enhancement of the transition width. In the SF region a multiple-peak structure is observed in the ac susceptibility measurements which is associated with the secondary transition lines. This behaviour is discussed in terms of several mechanisms proposed previously. When the sample is cooled in applied fields below HSF(T) we observe the presence of a remanent magnetization (Mr) in the antiferromagnetic (AF) phase. Such magnetization was previously found in these solid solutions at very low fields (a few Oe). Here we also find that Mr follows a temperature dependence that is independent of the concentration x and is the same for the K and Rb derivatives.

  16. Status of U.S./Japan collaborative program phase II HFIR target and RB{sup *} capsules

    SciTech Connect

    Pawel, J.E.; Lenox, K.E.; Longest, A.W.

    1995-04-01

    The objective of the HFIR irradiations is to determine the response of various U.S. and Japanese austenitic and ferritic steels with different pretreatments and alloy compositions to the combined effects of displacement damage and helium generation. Specimen temperatures during irradiation range from 60 to 600{degrees}C and fluences range up to 60 dpa. The RB{sup *} experiments are a continuation of the ORR spectrally tailored experiments in which the spectrum is modified with a hafnium shield to simulate the expected fusion helium to damage (He/dpa) ratio. In the HFIR target capsules, many specimens have been isotopically tailored in order to achieve fusion helium generation rates.

  17. Modulated structure of Rb{sub 2}ZnCl{sub 4} in the soliton regime close to the lock-in phase transition

    SciTech Connect

    Aramburu, I.; Morgenroth, W.; Breczewski, T.

    2006-01-01

    The structure of the incommensurate phase of Rb{sub 2}ZnCl{sub 4} has been determined at 194 K (2 K above the lock-in transition) within the soliton regime using satellites up to fifth order. The rather anharmonic modulation functions agree with the expected steplike functions supported by theoretical arguments. In addition, the constancy of the ratio between the amplitudes of the fifth-order and first-order harmonics, a relation predicted by theory, indicate the correctness of the model and imply a value of 0.4 for the soliton density n{sub s}. A symmetry mode analysis shows that the incommensurate structure is consistent with the one of the lock-in phase in the sense that the displacement pattern of every symmetry mode remains unaltered in the transition except for a global change in the amplitudes.

  18. Correlations between potassium, rubidium and cesium ((133)Cs and (137)Cs) in sporocarps of Suillus variegatus in a Swedish boreal forest.

    PubMed

    Vinichuk, M; Rosén, K; Johanson, K J; Dahlberg, A

    2011-04-01

    An analysis of sporocarps of ectomycorrhizal fungi Suillus variegatus assessed whether cesium ((133)Cs and (137)Cs) uptake was correlated with potassium (K) or rubidium (Rb) uptake. The question was whether intraspecific correlations of Rb, K and (133)Cs mass concentrations with (137)Cs activity concentrations in sporocarps were higher within, rather than among, different fungal species, and if genotypic origin of sporocarps within a population affected uptake and correlation. Sporocarps (n = 51) from a Swedish forest population affected by the fallout after the Chernobyl accident were studied. The concentrations were 31.9 ± 6.79 g kg(-1) for K (mean ± SD, dwt), 0.40 ± 0.09 g kg(-1) for Rb, 8.7 ± 4.36 mg kg(-1) for (133)Cs and 63.7 ± 24.2 kBq kg(-1) for (137)Cs. The mass concentrations of (133)Cs correlated with (137)Cs activity concentrations (r = 0.61). There was correlation between both (133)Cs concentrations (r = 0.75) and (137)Cs activity concentrations (r = 0.44) and Rb, but the (137)Cs/(133)Cs isotopic ratio negatively correlated with Rb concentration. Concentrations of K and Rb were weakly correlated (r = 0.51). The (133)Cs mass concentrations, (137)Cs activity concentrations and (137)Cs/(133)Cs isotopic ratios did not correlate with K concentrations. No differences between, within or, among genotypes in S. variegatus were found. This suggested the relationships between K, Rb, (133)Cs and (137)Cs in sporocarps of S. variegatus is similar to other fungal species.

  19. Vapor-Phase Epitaxial Growth of Aligned Nanowire Networks of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I).

    PubMed

    Chen, Jie; Fu, Yongping; Samad, Leith; Dang, Lianna; Zhao, Yuzhou; Shen, Shaohua; Guo, Liejin; Jin, Song

    2017-01-11

    With the intense interest in inorganic cesium lead halide perovskites and their nanostructures for optoelectronic applications, high-quality crystalline nanomaterials with controllable morphologies and growth directions are desirable. Here, we report a vapor-phase epitaxial growth of horizontal single-crystal CsPbX3 (X = Cl, Br, I) nanowires (NWs) and microwires (MWs) with controlled crystallographic orientations on the (001) plane of phlogopite and muscovite mica. Moreover, single NWs, Y-shaped branches, interconnected NW or MW networks with 6-fold symmetry, and, eventually, highly dense epitaxial network of CsPbBr3 with nearly continuous coverage were controllably obtained by varying the growth time. Detailed structural study revealed that the CsPbBr3 wires grow along the [001] directions and have the (100) facets exposed. The incommensurate heteroepitaxial lattice match between the CsPbBr3 and mica crystal structures and the growth mechanism of these horizontal wires due to asymmetric lattice mismatch were proposed. Furthermore, the photoluminescence waveguiding and good performance from the photodetector device fabricated with these CsPbBr3 networks demonstrated that these well-connected CsPbBr3 NWs could serve as straightforward platforms for fundamental studies and optoelectronic applications.

  20. Pressure-induced phase transitions in rubidium azide: Studied by in-situ x-ray diffraction

    SciTech Connect

    Li, Dongmei; Wu, Xiaoxin; Jiang, Junru; Zhang, Jian; Cui, Qiliang; Zhu, Hongyang; Wang, Xiaoli

    2014-08-18

    We present the in-situ X-ray diffraction studies of RbN{sub 3} up to 42.0 GPa at room temperature to supplement the high pressure exploration of alkali azides. Two pressure-induced phase transitions of α-RbN{sub 3} → γ-RbN{sub 3} → δ-RbN{sub 3} were revealed at 6.5 and 16.0 GPa, respectively. During the phase transition of α-RbN{sub 3} → γ-RbN{sub 3}, lattice symmetry decreases from a fourfold to a twofold axis accompanied by a rearrangement of azide anions. The γ-RbN{sub 3} was identified to be a monoclinic structure with C2/m space group. Upon further compression, an orthogonal arrangement of azide anions becomes energetically favorable for δ-RbN{sub 3}. The compressibility of α-RbN{sub 3} is anisotropic due to the orientation of azide anions. The bulk modulus of α-RbN{sub 3} is 18.4 GPa, quite close to those of KN{sub 3} and CsN{sub 3}. By comparing the phase transition pressures of alkali azides, their ionic character is found to play a key role in pressure-induced phase transitions.

  1. High temperature synthesis of two open-framework uranyl silicates with ten-ring channels: Cs{sub 2}(UO{sub 2}){sub 2}Si{sub 8}O{sub 19} and Rb{sub 2}(UO{sub 2}){sub 2}Si{sub 5}O{sub 13}

    SciTech Connect

    Babo, Jean-Marie; Albrecht-Schmitt, Thomas E.

    2013-01-15

    The uranyl silicates Cs{sub 2}(UO{sub 2}){sub 2}Si{sub 8}O{sub 19} and Rb{sub 2}(UO{sub 2}){sub 2}Si{sub 5}O{sub 13} were obtained by mixing stoichiometric amounts of uranium metal, tellurium dioxide, silicon dioxide, and an excess of correspondent alkali metal halide flux. These compounds crystallize in the orthorhombic space groups Pnma and C222 with eight and two units per unit cell, respectively. Their crystal structures are dominated by zippered pentagonal bipyramidal chains of UO{sub 7} and silicates layer that are further connected into 3D frameworks. The cesium compound has silicate double layers while rubidium has a single layer. Six-ring voids and ten-ring channels are found in both compounds. - Graphical abstract: A view of the three-dimensional network structure of Cs{sub 2}(UO{sub 2}){sub 2}Si{sub 8}O{sub 19}. Highlights: Black-Right-Pointing-Pointer Three-dimensional uranium silicates. Black-Right-Pointing-Pointer Analogs of natural uranyl silicate minerals. Black-Right-Pointing-Pointer Complexity and symmetry ambiguity of uranyl silicates.

  2. The Rb problem in massive AGB stars.

    NASA Astrophysics Data System (ADS)

    Pérez-Mesa, V.; García-Hernández, D. A.; Zamora, O.; Plez, B.; Manchado, A.; Karakas, A. I.; Lugaro, M.

    2017-03-01

    The asymptotic giant branch (AGB) is formed by low- and intermediate-mass stars (0.8 M_{⊙} < M < 8 M_{⊙}) in their last nuclear-burning phase, when they develop thermal pulses (TP) and suffer extreme mass loss. AGB stars are the main contributor to the enrichment of the interstellar medium (ISM) and thus to the chemical evolution of galaxies. In particular, the more massive AGB stars (M > 4 M_{⊙}) are expected to produce light (e.g., Li, N) and heavy neutron-rich s-process elements (such as Rb, Zr, Ba, Y, etc.), which are not formed in lower mass AGB stars and Supernova explosions. Classical chemical analyses using hydrostatic atmospheres revealed strong Rb overabundances and high [Rb/Zr] ratios in massive AGB stars of our Galaxy and the Magellanic Clouds (MC), confirming for the first time that the ^{22}Ne neutron source dominates the production of s-process elements in these stars. The extremely high Rb abundances and [Rb/Zr] ratios observed in the most massive stars (specially in the low-metallicity MC stars) uncovered a Rb problem; such extreme Rb and [Rb/Zr] values are not predicted by the s-process AGB models, suggesting fundamental problems in our present understanding of their atmospheres. We present more realistic dynamical model atmospheres that consider a gaseous circumstellar envelope with a radial wind and we re-derive the Rb (and Zr) abundances in massive Galactic AGB stars. The new Rb abundances and [Rb/Zr] ratios derived with these dynamical models significantly resolve the problem of the mismatch between the observations and the theoretical predictions of the more massive AGB stars.

  3. CsSnI3: Semiconductor or metal? High electrical conductivity and strong near-infrared photoluminescence from a single material. High hole mobility and phase-transitions.

    PubMed

    Chung, In; Song, Jung-Hwan; Im, Jino; Androulakis, John; Malliakas, Christos D; Li, Hao; Freeman, Arthur J; Kenney, John T; Kanatzidis, Mercouri G

    2012-05-23

    CsSnI(3) is an unusual perovskite that undergoes complex displacive and reconstructive phase transitions and exhibits near-infrared emission at room temperature. Experimental and theoretical studies of CsSnI(3) have been limited by the lack of detailed crystal structure characterization and chemical instability. Here we describe the synthesis of pure polymorphic crystals, the preparation of large crack-/bubble-free ingots, the refined single-crystal structures, and temperature-dependent charge transport and optical properties of CsSnI(3), coupled with ab initio first-principles density functional theory (DFT) calculations. In situ temperature-dependent single-crystal and synchrotron powder X-ray diffraction studies reveal the origin of polymorphous phase transitions of CsSnI(3). The black orthorhombic form of CsSnI(3) demonstrates one of the largest volumetric thermal expansion coefficients for inorganic solids. Electrical conductivity, Hall effect, and thermopower measurements on it show p-type metallic behavior with low carrier density, despite the optical band gap of 1.3 eV. Hall effect measurements of the black orthorhombic perovskite phase of CsSnI(3) indicate that it is a p-type direct band gap semiconductor with carrier concentration at room temperature of ∼ 10(17) cm(-3) and a hole mobility of ∼585 cm(2) V(-1) s(-1). The hole mobility is one of the highest observed among p-type semiconductors with comparable band gaps. Its powders exhibit a strong room-temperature near-IR emission spectrum at 950 nm. Remarkably, the values of the electrical conductivity and photoluminescence intensity increase with heat treatment. The DFT calculations show that the screened-exchange local density approximation-derived band gap agrees well with the experimentally measured band gap. Calculations of the formation energy of defects strongly suggest that the electrical and light emission properties possibly result from Sn defects in the crystal structure, which arise

  4. ``Cs-tetra-ferri-annite:`` High-pressure and high-temperature behavior of a potential nuclear waste disposal phase

    SciTech Connect

    Comodi, P.; Zanazzi, P.F.; Weiss, Z.; Rieder, M.; Drabek, M.

    1999-03-01

    Structure deformations induced by pressure and temperature in synthetic Cs-tetra-ferri-annite 1M [Cs{sub 1.78}(Fe{sup 2+}{sub 5.93}Fe{sup 3+}{sub 0.07})(Si{sub 6.15}Fe{sup 3+}{sub 1.80}Al{sub 0.05})O{sub 20}(OH){sub 4}], space group C2/m, were analyzed to investigate the capability of the mica structure to store the radiogenic isotopes {sup 135}Cs and {sup 137}Cs. Cs-tetra-ferri-annite is not a mineral name, but for the sake of brevity is used here to designate a synthetic analog of the mineral tetra-ferri-annite. The bulk modulus and its pressure derivative determined by fitting the unit-cell volumes between 0 a/nd 47 kbar to a third-order Birch-Murnaghan equation of state are K{sub 0} = 257(8) kbar and K{prime}{sub 0} = 21(1), respectively. Between 23 C and 582 C, the a and b lattice parameters remain essentially unchanged, but the thermal expansion coefficient of the c axis is {alpha}{sub c} = 3.12(9) {times} 10{sup {minus}5} {degree}C{sup {minus}1}. High pressure (P) and high temperature (T) produce limited internal strain in the structure. The tetrahedral rotation angle, {alpha}, is very small and does not change significantly throughout the P and T range investigated. Above 450 C in air, Cs-tetra-ferri-annite underwent an oxidation of octahedral iron in the M2cis site, balanced by the loss of H and shown by a decrease of the unit-cell volume. Independent isobaric data on thermal expansion and isothermal compressibility data define the geometric equation of state for Cs-tetra-ferri-annite. On the whole, the data confirm that the structure of Cs-tetra-ferri-annite may be a suitable candidate for the storage of large ions, such as Cs in the interlayer and should be considered as a potential Synroc component.

  5. Characterization of the Natural Organic Matter (NOM) in groundwater contaminated with (60)Co and (137)Cs using ultrafiltration, Solid Phase Extraction and fluorescence analysis.

    PubMed

    Caron, François; Siemann, Stefan; Riopel, Rémi

    2014-12-01

    Spot samples of shallow groundwaters have been taken between the years 2004 and 2010 near a site formerly used for the dispersal of radioactive liquid wastes. Three sampling points, one clean (upstream), and two downstream of the contamination source, were processed by ultrafiltration (5000 Da cut-off) and Solid Phase Extraction (SPE) to determine the association of selected artificial radionuclides ((60)Co, (137)Cs) with Natural Organic Matter (NOM). The last two sampling episodes (2008 and 2010) also benefited from fluorescence analysis to determine the major character of the NOM. The fluorescence signals are reported as humic-like, fulvic-like and protein-like, which are used to characterize the different NOM types. The NOM from the clean site comprised mostly fine material, whereas the colloidal content (retained by ultrafiltration) was higher (e.g., 15-40% of the Total Organic Carbon - TOC). Most of the 137Cs was present in the colloidal fraction, whereas (60)Co was found in the filtered fraction. Fluorescence analysis, on the other hand, indicated a contrasting behavior between the clean and contaminated sites, with a dominance of protein-like material, a feature usually associated with human impacts. Finally, SPE removed almost quantitatively the protein-like material (>90%), whereas it removed a much smaller fraction of the (137)Cs (<28%). This finding indicates that the (137)Cs preferential binding occurs with a fraction other than the protein-like NOM, likely the fulvic-like or humic-like portion.

  6. The Natural Enrichment of Stable Cesium in Weathered Micaceous Materials and Its Implications for 137Cs Sorption.

    SciTech Connect

    Elliott, W. Crawford; Kahn, Bernd; Rosson, Robert; Wampler, J. Marion; Rose, Seth E.; Krogstad, Eirik J.; Kaplan, Daniel

    2011-11-14

    In this exploratory project, we are testing two interrelated hypotheses about the sorption of Cs within weathered micaceous materials in subsurface regolith materials from the Savannah River Site (SRS) located on the Atlantic Coastal Plain: 1) that stable cesium has become significantly enriched relative to potassium in subsurface micaceous particles as a result of chemical weathering processes; and 2) that the Cs so present is sufficient to be a major factor determining the ability of the subsurface materials to take up and hold 137Cs. To test these hypotheses, we collected by hand augur soil samples corresponding to soils representative at the SRS: upland regolith (Fuquay series); soils formed on Tobacco Road Sandstone; and, soils formed on Quaternary Alluvium. From our data, the quantification of the amounts of stable cesium concentrated in various sites within 2:1 phyllosilicates by natural processes is highly relevant toward understanding the future sorption of 137Cs by the mica, illite, vermiculite, and hydroxyl interstratified vermiculite (HIV) phases present in the subsurface at and in proximity to SRS. Studying sorption and fixation of Cs in these micaceous phases interlayers potentially leads to increased knowledge to the extent that stable Cs resists exchange with ion exchange cations (Mg, NH4, or even alkyl ammonium compounds) and to the extent that Cs can become fixed over the long term. Such knowledge will help in the development of 137Cs remediation strategies for the long-term, which is a critical aspect of the SBR goals. We characterized the mineralogy, K-Ar ages of the soil and soil clay fractions (before and after acid treatment), and alkali element chemistry (K, Rb, Cs) of the clay fractions of soils collected from these three different types of soils. The clay fractions of the Fuquay soils are composed of kaolinite, and hydroxy interstratified vermiculite (HIV). Kaolinite, HIV, quartz, gibbsite and illite are

  7. Alkali metal and ammonium fluoro(trifluoroacetato)metallates M Prime [M Prime Prime {sub 3}({mu}{sub 3}-F)(CF{sub 3}COO){sub 6}(CF{sub 3}COOH){sub 3}], where M Prime = Li, Na, K, NH{sub 4}, Rb, or Cs and M Prime Prime = Ni or Co. Synthesis and crystal structures

    SciTech Connect

    Tereshchenko, D. S.; Morozov, I. V. Boltalin, A. I.; Karpova, E. V.; Glazunova, T. Yu.; Troyanov, S. I.

    2013-01-15

    A series of fluoro(trifluoroacetato)metallates were synthesized by crystallization from solutions in trifluoroacetic acid containing nickel(II) or cobalt(II) nitrate hydrates and alkali metal or ammonium fluorides: Li[Ni{sub 3}({mu}{sub 3}-F)(CF{sub 3}COO){sub 6}(CF{sub 3}COOH){sub 3}](CF{sub 3}COOH){sub 3} (I), M Prime [Ni{sub 3}({mu}{sub 3}-F)(CF{sub 3}COO){sub 6}(CF{sub 3}COOH){sub 3}] (M Prime = Na (II), NH{sub 4} (IV), Rb (V), and Cs (VI)), NH{sub 4}[Co{sub 3}({mu}{sub 3}-F) (CF{sub 3}COO){sub 6}(CF{sub 3}COOH){sub 3}] (III), and Cs[Ni{sub 3}({mu}{sub 3}-F)(CF{sub 3}COO){sub 6}(CF{sub 3}COOH){sub 3}](CF{sub 3}COOH){sub 0.5} (VII). The crystal structures of these compounds were determined by single-crystal X-ray diffraction. All structures contain triangular trinuclear complex anions [M{sub 3} Double-Prime ({mu}{sub 3}-F)(CF{sub 3}COO){sub 6}(CF{sub 3}COOH){sub 3}]{sup -} (M Double-Prime = Ni, Co) structurally similar to trinuclear 3d metal oxo carboxylate complexes. The three-coordinated F atom is located at the center of the triangle formed by Ni(II) or Co(II) atoms. The metal atoms are linked in pairs by six bridging trifluoroacetate groups located above and below the plane of the [M Double-Prime {sub 3} F] triangle. The oxygen atoms of the axial CF{sub 3}COOH molecules complete the coordination environment of M Double-Prime atoms to an octahedron.

  8. Adsorption of polycations on clays: A comparative in situ study using {sup 133}Cs and {sup 23}Na solution phase NMR

    SciTech Connect

    Billingham, J.; Breen, C.; Rawson, J.O.; Yarwood, J.; Mann, B.E.

    1997-09-15

    {sup 23}Na solution phase NMR has been evaluated as an in situ probe to study the adsorption of tetramethylammonium (TMA{sup +}) and two polycations, FL17 and Magnafloc 1697, onto clays in aqueous suspensions containing 2.5 mass% low iron Texas bentonite. The NMR data shows the effectiveness of the organocations at displacing Na{sup +} from the bentonite surface. This information has been correlated with that obtained from particle-size and electrophoretic measurements in aqueous solution, together with information from adsorption isotherms. These results have been compared to those obtained in parallel studies using {sup 133}Cs solution phase NMR. FL17 and 1697 both exhibited high affinity adsorption isotherms on Na{sup +}- and Cs{sup +}-clay, whereas the adsorption of TMA{sup +}, which represents the cationic portion of the polymers was of lower affinity. Na{sup +}-bentonite adsorbed almost twice the amount of polycation required to fulfill the cation-exchange capacity (CEC) of the bentonite. The electrophoretic and particle size data indicated significant differences in the size of the polycation/clay flocs and the amount of polymer adsorbed on the external faces of the flocs in the presence of Na{sup +}- and Cs{sup +}-exchange ions. Correlation of this data with the NMR results suggests that the Na{sup +}-bentonite/polycation flocs are large, of low density, and that the polycation is concentrated in the interior while the Na{sup +}-ions occupy exchange sites on the external faces.

  9. Pressure Effects on Phase Transitions in Several Hexagonal Antiferromagnets of ABX_3 Type

    NASA Astrophysics Data System (ADS)

    Sasaki, Y.; Goto, K.; Ono, T.; Tanaka, H.; Goto, T.

    Magnetic measurements under high pressures have been performed on the hexagonal ABX_3 type antiferromagnets, CsFeCl_3, CsNiCl_3 and RbNiCl_3 to investigate the pressure effect on the magnetic phase transitions. CsFeCl_3 has the singlet ground state due to the large single-ion anisotropy of the easy-plane type at ambient pressure. Above the critical pressure Pc≃ 0.9 GPa, CsFeCl_3 exhibits the long range magnetic ordering at zero field as the result of the collapse of the energy gap between the singlet state and the lowest excited doublet. CsNiCl_3 and RbNiCl_3 having the easy-axis type magnetic anisotropy undergo the successive phase transitions in the temperature variations and exhibit the spin-flop phase transition in the field parallel to the c-axis. With increasing pressure, the temperature range of the collinear intermediate phase and the spin-flop field HSF are enhanced. This fact indicates that the easy-axis anisotropies of CsNiCl_3 and RbNiCl_3 are enhanced by the pressure as compared with the increase of the intra- and inter-chain interactions.

  10. The happy marriage between electron-phonon superconductivity and Mott physics in Cs3C60: A first-principle phase diagram

    NASA Astrophysics Data System (ADS)

    Capone, Massimo; Nomura, Yusuke; Sakai, Shiro; Giovannetti, Gianluca; Arita, Ryotaro

    The phase diagram of doped fullerides like Cs3C60 as a function of the spacing between fullerene molecules is characterized by a first-order transition between a Mott insulator and an s-wave superconductor with a dome-shaped behavior of the critical temperature. By means of an ab-initio modeling of the bandstructure, the electron-phonon interaction and the interaction parameter and a Dynamical Mean-Field Theory solution, we reproduce the phase diagram and demonstrate that phonon superconductivity benefits from strong correlations confirming earlier model predictions. The role of correlations is manifest also in infrared measurements carried out by L. Baldassarre. The superconducting phase shares many similarities with ''exotic'' superconductors with electronic pairing, suggesting that the anomalies in the ''normal'' state, rather than the pairing glue, can be the real common element unifying a wide family of strongly correlated superconductors including cuprates and iron superconductors

  11. Magnegtic Phase Diagram and Specific Heat of the Quasi-Two-Dimensional S=1/2 Antiferromagnet Cs2CuBr4

    NASA Astrophysics Data System (ADS)

    Sherline, Todd E.; Rotundu, Costel R.; Andraka, Bohdan; Takano, Yasu; Tsujii, Hiroyuki; Ono, Toshio; Tanaka, Hidekazu

    2006-03-01

    The S=1/2 Heisenberg antiferromagnet on a triangular lattice is very well represented by Cs2CuBr4 due to its small anisotropy. An unique feature of this system, as predicted by theory and borne out by experiment, is the magnetization plateau at 1/3 of the saturation magnetization. Previous specific heat and magnetocaloric effect measurements in DC fields of up to 20T have been used to determine the magnetic phase diagram in this regime. However, the nature of the phase diagram is unclear in higher fields. Further specific heat and magnetocaloric effect measurements have been made in DC fields up to 33T, the results of which will be presented in order to elucidate the nature of the phase diagram above the magnetization plateau.

  12. Low temperature structural modification in Rb2ZrF6: Investigations by perturbed angular correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Dey, S. K.; Dey, C. C.; Saha, S.

    2016-06-01

    Temperature dependent perturbed angular correlation (PAC) measurements in crystalline compounds Rb2ZrF6 and Cs2HfF6 have been performed in the temperature range 298-753 K. In Rb2ZrF6, four discrete quadrupole interaction frequencies have been observed at room temperature which correspond to four minor structural modifications. From previous measurements, on the other hand, two structural modifications of this compound were known. A displacive phase transition, probably, occurs at low temperature due to rotation of the ZrF62- octahedron and produces different structural modifications. From present measurements in Rb2ZrF6, two quadrupole interaction frequencies [ωQ=26.1(3) Mrad/s, η=0.55(2), δ=5(1)% and ωQ=148.7(3) Mrad/s, η=0.538(5), δ=1.2%] have been found at room temperature which were not found from previous studies. In Cs2HfF6, these new structural modifications have not been observed.

  13. Deuteron NMR study of dynamics and of coexistence of paraelectric and ferroelectric phases in Rb0.90(ND4)0.10D2AsO4

    NASA Astrophysics Data System (ADS)

    Pinto, Nicholas J.; Howell, Francis L.; Schmidt, V. Hugo

    1993-09-01

    The deuteron glass Rb1-x(ND4)xD2AsO4 (DRADA) is a mixed crystal of RbD2AsO4 (DRDA) and ND4D2AsO4 (DADA). Deuteron nuclear magnetic resonance has been performed on the acid and ammonium deuterons. The crystal studied has an ammonium concentration (x=0.10) that puts it in the coexistence region of the phase diagram. Line-shape measurements of the ammonium deuterons show the coexistence of the ferroelectric (FE) and paraelectric (PE) phases as the temperature is lowered below the ferroelectric-phase-transition temperature Tc. The acid deuteron line shape on the other hand is found to broaden as the temperature is reduced but is unaffected by the ferroelectric transition. Spin-lattice-relaxation measurements have been performed and the activation energies for the relaxation processes have been computed. The relaxation-rate anomaly for acid deuterons in the ferroelectric-transition range indicates a short correlation length for the FE phase in the coexistence region of the phase diagram.

  14. New hypodiphosphates of the alkali metals: Synthesis, crystal structure and vibrational spectra of the hypodiphosphates(IV) M{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] (M=Rb and Cs)

    SciTech Connect

    Wu, Peng; Wiegand, Thomas; Eckert, Hellmut

    2012-10-15

    The new hypodiphosphates(IV) Rb{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] (1) and Cs{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] (2) were synthesized by soft chemistry reactions from aqueous solutions of hypophosphoric acid and the corresponding heavy alkali-metal carbonates. Their crystal structures were determined by single crystal X-ray diffraction. Both compounds crystallize isotypic in the triclinic space group P-1 with one formula unit in the unit cell. The structures are built up by discrete (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) units in staggered conformation for the P{sub 2}O{sub 6} skeleton and the corresponding alkali-metal cations. In the (H{sub 2}P{sub 2}O{sub 6}){sup 2-} ion the hydrogen atoms are in a 'trans-trans' conformation. O{center_dot}H-O hydrogen bonds between the (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) groups consolidate the structures into a three-dimensional network. The FT-Raman and {sup 31}P and {sup 1}H and MAS NMR spectra of the title compounds have been recorded and interpreted, especially with respect to their assignment to the (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) groups. Thermogravimetric data of 2 have been interpreted in terms of a thermal decomposition model. - Graphical Abstract: The layered compounds Rb{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] and Cs{sub 2}[(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})] have been synthesized and investigated. Both crystallize isotypic. The structures are built up by discrete (H{sub 2}P{sub 2}O{sub 6}){sup 2-} and (H{sub 4}P{sub 2}O{sub 6}) units and the corresponding alkali-metal cations. Highlights: Black-Right-Pointing-Pointer Synthesis and single-crystal structure of new alkali hypodiphosphates. Black-Right-Pointing-Pointer Structures are characterized by [(H{sub 2}P{sub 2}O{sub 6})(H{sub 4}P{sub 2}O{sub 6})]{sup 2-} units and M{sup +} cations

  15. High-Temperature Phase Transitions in CsH2PO4 Under Ambient and High-Pressure Conditions: A Synchrotron X-ray Diffraction Study

    SciTech Connect

    Botez,C.; Hermosillo, J.; Zhang, J.; Qian, J.; Zhao, Y.; Majzlan, J.; Chianelli, R.; Pantea, C.

    2007-01-01

    To clarify the microscopic origin of the temperature-induced three-order-of-magnitude jump in the proton conductivity of CsH2PO4 (superprotonic behavior), we have investigated its crystal structure modifications within the 25-300 C temperature range under both ambient- and high-pressure conditions using synchrotron x-ray diffraction. Our high-pressure data show no indication of the thermal decomposition/polymerization at the crystal surface recently proposed as the origin of the enhanced proton conductivity. Instead, we found direct evidence that the superprotonic behavior of the title material is associated with a polymorphic structural transition to a high-temperature cubic phase. Our results are in excellent agreement with previous high-pressure ac impedance measurements.

  16. Phase transitions and equation of state of CsI under high pressure and the development of a focusing system for x-rays

    SciTech Connect

    Wu, Yan.

    1990-11-01

    The phase transitions and equation of state of ionic solid cesium iodide were studied under high pressure and room temperature in a diamond anvil cell. The studies were carried out using both energy dispersive and angular dispersive diffraction methods on synchrotron radiation sources over the pressure range from atmospheric pressure to over 300 gigapascals (3 million atmospheres). CsI undergoes a distinct phase transition at about 40 GPa, a pressure that is much lower than the reported insulator-metal transition at 110 GPa, from the atmospheric pressure B2(CsCl) structure to an orthorhombic structure. At higher pressures, a continuous distortion in the structure was observed with a final structure similar to a hcp lattice under ultra high pressure. No volume discontinuity was observed at the insulator-metal transition. The newly found transition sequence is different from the result of previous static compression studies. The current structure has a smaller unit cell volume than the previous assignment. This has resolved a long existing controversy among the previous static compression studies, the dynamic compression studies, and the theoretical studies. The current results also explain the apparent discrepancy between the present study and the previous static studies. We also present the development of a focusing system for high energy x-rays (> 12 keV) that is particularly suited for high pressure diffraction studies. This system uses a pair of multilayer coated spherical mirrors in a Kirkpatrick-Baez geometry. A focused beam size less than 10 micron in diameter can be readily achieved with sufficient intensity to perform diffraction studies. 93 refs., 46 figs., 15 tabs.

  17. What's so special about RB?

    PubMed

    Burd, Christin E; Sharpless, Norman E

    2010-04-13

    RB, p107, and p130 are highly related proteins, each capable of regulating cellular proliferation. However, only RB is frequently mutated in cancer. In this issue of Cancer Cell, Chicas et al. shed new light on this conundrum, defining a "special," nonredundant role for RB in promoting cellular senescence.

  18. High-pressure behaviour of Cs2V3O8 fresnoite

    NASA Astrophysics Data System (ADS)

    Grzechnik, Andrzej; Yeon, Jeongho; Zur Loye, Hans-Conrad; Friese, Karen

    2016-06-01

    Crystal structure of Cs2V3O8 fresnoite (P4bm, Z=2) has been studied using single-crystal X-ray diffraction in a diamond anvil cell to 8.6 GPa at room temperature. Cs2V3O8 undergoes a reversible first-order phase transition at about 4 GPa associated with anomalies in the pressure dependencies of the lattice parameters and unit-cell volume but without any symmetry change. Both structures consist of layers of corner-sharing V5+O4 tetrahedra and V4+O5 tetragonal pyramids separated by the Cs+ cations located between the layers. At low pressures, the compression has little effect on the polarity of the structure. Above 4 GPa, the pseudosymmetry with respect to the corresponding centrosymmetric space group P4/mbm abruptly increases. The effects of external pressure and of the A+ cation substitution in the vanadate fresnoites A2V3O8 (A+: K+, Rb+, NH4+, Cs+) are discussed.

  19. Guided-Ion-Beam and ab Initio Study of the Li+, K+, and Rb+ Association Reactions with Gas-Phase Butanone and Cyclohexanone in Their Ground Electronic States

    NASA Astrophysics Data System (ADS)

    Lucas, J. M.; de Andrés, J.; López, E.; Albertí, M.; Bofill, J. M.; Bassi, D.; Ascenzi, D.; Tosi, P.; Aguilar, A.

    2009-08-01

    The association reactions between Li+, K+, and Rb+ (M) and butanone and cyclohexanone molecules under single collision conditions have been studied using a radiofrequency-guided ion-beam apparatus, characterizing the adducts by mass spectrometry. The excitation function for the [M-(molecule)]+ adducts (in arbitrary units) has been obtained at low collision energies in the 0.10 eV up to a few eV range in the center of mass frame. The measured relative cross sections decrease when collision energy increases, showing the expected energy dependence for adduct formation. The energetics and structure of the different adducts have been calculated ab initio at the MP2(full) level, showing that the M+-molecule interaction takes place through the carbonyl oxygen atom, as an example of a nontypical covalent chemical bond. The cross-section energy dependence and the role of radiative cooling rates allowing the stabilization of the collision complexes are also discussed.

  20. Growth of PbX2 and CsPbX3 (X = Cl, Br) mesoscopic phases in alkali halide host lattices

    NASA Astrophysics Data System (ADS)

    Polak, K.; Nitsch, K.; Nikl, M.

    Formation of PbCl2 and CsPbBr3 microphases in NaCl and CsBr respectively is studied using mainly an absorption spectroscopy. The absorption of NaCl: Pb crystal was investigated as a function of annealing temperature and duration of thermal treatment. Changes in the position and shape of the exciton band were studied in CsBr: Pb absorption spectrum. The results showed that the shape of CsPbBr3 microcrystals is far from a spherical one. The microcrystals probably grow as highly elongated discs.

  1. Defining a new vision for the retinoblastoma gene: report from the 3rd International Rb Meeting.

    PubMed

    Rubin, Seth M; Sage, Julien

    2013-11-21

    The retinoblastoma tumor suppressor (Rb) pathway is mutated in most, if not all human tumors. In the G0/G1 phase, Rb and its family members p107 and p130 inhibit the E2F family of transcription factors. In response to mitogenic signals, Cyclin-dependent kinases (CDKs) phosphorylate Rb family members, which results in the disruption of complexes between Rb and E2F family members and in the transcription of genes essential for S phase progression. Beyond this role in early cell cycle decisions, Rb family members regulate DNA replication and mitosis, chromatin structure, metabolism, cellular differentiation, and cell death. While the RB pathway has been extensively studied in the past three decades, new investigations continue to provide novel insights into basic mechanisms of cancer development and, beyond cancer, help better understand fundamental cellular processes, from plants to mammals. This meeting report summarizes research presented at the recently held 3rd International Rb Meeting.

  2. Overproduction of Rb protein after the G1/S boundary causes G2 arrest.

    PubMed Central

    Karantza, V; Maroo, A; Fay, D; Sedivy, J M

    1993-01-01

    The Rb protein is known to exert its activity at decision points in the G1 phase of the cell cycle. To investigate whether it may also play some role(s) at later points in the cell cycle, we used a system of rapid inducible gene amplification to conditionally overexpress Rb protein during G2 phase. A cell line expressing a temperature-sensitive simian virus 40 large T antigen (T-Ag) was stably transfected with plasmids containing the Rb cDNA linked to the simian virus 40 origin of replication: pRB-wt, pRB-fs, and pRB-Dra, carrying wild-type murine Rb cDNA, a frameshift mutation close to the beginning of the Rb coding region, and a single-amino-acid deletion in the E1A/T-Ag binding pocket, respectively. Numerous independent cell lines were isolated at the nonpermissive temperature; cell lines displaying a high level of episomal amplification of an intact Rb expression cassette following shiftdown to the permissive temperature were chosen for further analysis. Plasmid pRB-fs did not express detectable Rb antigen, while pRB-Dra expressed full-length Rb protein. The Dra mutation has previously been shown to abrogate phosphorylation as well as T-Ag binding. Fluorescence-activated cell sorting (FACS) analysis revealed that cultures induced to overexpress either wild-type or Dra mutant Rb proteins were significantly enriched for cells with a G2 DNA content. Cultures that amplified pRB-fs or rearranged pRB-wt and did not express Rb protein had normal cell cycle profiles. Double-label FACS analysis showed that cells overexpressing Rb or Rb-Dra proteins were uniformly accumulating in G2, whereas cells expressing endogenous levels of Rb were found throughout the cell cycle. These results indicate that Rb protein is interacting with some component(s) of the cell cycle-regulatory machinery during G2 phase. Images PMID:8413260

  3. Developments towards detection of 135Cs at VERA

    NASA Astrophysics Data System (ADS)

    Lachner, Johannes; Kasberger, Magdalena; Martschini, Martin; Priller, Alfred; Steier, Peter; Golser, Robin

    2015-10-01

    Radioisotopes produced in natural or anthropogenic fission are widely used for tracer studies of environmental processes, in nuclear forensics, and are important for nuclear waste disposal. Besides the well-known 137Cs, the longer-lived sister isotope 135Cs (T1/2 = 2.3 Myr) is also produced, and the combined measurement of the two isotopes would allow for assessment of contaminating sources. The insufficient suppression of the stable isobar 135Ba presently prevents AMS measurements down to expected natural levels of 135Cs/133Cs ≈ 10-11. Via the difference in electron affinities between Cs and Ba further isobar suppression should be achievable after the installation of the Ion-Laser-Interaction System (ILIAS) at VERA. We present a preparatory study on the performance of the 3 MV VERA AMS facility for 135Cs concerning ion formation, transmission and detection. Since the usual Cs sputtering would obscure the 135Cs/133Cs ratio of a sample, Rb sputtering was successfully applied and tested also for various other typical AMS elements. Partial suppression of 135Ba is possible with the extraction of Cs- and negative Cs-fluorides. Cs- currents of several 10 nA were extracted over hours from mg amounts of Cs2SO4 material. The transmission to various charge states was tested with gas (Ar, He) and foil stripping. Experiments showed that no suppression in the detection system is possible at high beam energies with the VERA facility. For this reason, gas stripping to low charge states (2+, 3+) with transmissions up to 30% is favorable to guarantee optimal beam transport to the detector. In the present setup, utilizing a simple Bragg-type detector, the blank 135Cs/133Cs ratios from chemically pure samples are determined by the 135Ba background to a value of (4.0 ± 1.3)·10-9.

  4. Communication: Evidence for dipole-bound excited states in gas-phase I- ṡ MI (M = Na, K, Cs) anionic salt microclusters

    NASA Astrophysics Data System (ADS)

    Harvey, Andrew J. A.; Yoshikawa, Naruo; Wang, Jin-Guo; Dessent, Caroline E. H.

    2015-09-01

    We report the first UV laser photodissociation spectra of gas-phase I- ṡ MI (M = Na, K, Cs) alkali halide anionic microclusters. The photodepletion spectra of these clusters display strong absorption bands just below the calculated vertical detachment energies, indicative of the presence of dipole-bound excited states. Photoexcitation at the peak of the transition to the dipole-bound excited state results in production of a primary [MI]- photofragment along with a less intense I- ion. The photofragmentation mechanism of the excited state cluster is discussed in the context of an initial dipole-bound excited state that subsequently relaxes via a vibrational Feschbach resonance. The experiments described have been performed in an electrospray source laser-interfaced quadrupole ion-trap instrument and demonstrated for the first time that dipole-bound excited states can be identified in the relatively high-collision environment of a quadrupole ion-trap, in particular for systems with large dipole moments associated with the presence of charge separation. This indicates considerable potential for future experiments that identify dipole-bound excited states as a "low-resolution" structural probe of biomolecules and molecular charge separation using the instrumentation employed in this work.

  5. Etude des transitions de phases dans les systèmes K 3MO 3F 3- A3MO 3F 3( A= Na, Rb; M= Mo, W)

    NASA Astrophysics Data System (ADS)

    Fouad, M.; Chaminade, J. P.; Ravez, J.; Sadel, A.

    1996-06-01

    RésuméX-ray diffraction, differential thermal analysis, polarized light microscopy, and dielectric measurements have been used to study phase transitions and solid solutions in the K3MO3F3-A3MO3F3(A= Rb, Na;M= Mo, W) systems. K3MO3F3-Na3MO3F3(M= Mo, W) systems show two solid solutions; the first (SSI) nearx= 0 (K3-xNaxMO3F3) involves only one transition atTCwhich is practically independent of composition. The sharp transition atT1(Rb3MO3F3-K3MO3F3systems show three solid solutions. The SS1 and SS3 exist close to the rubidium and potassium extremes of the binary lines. The pure phases display transitions atT1andTC. For compositions far fromy= 0 ory= 3 (Rb3-yKyMO3F3),TCdecreases andT1decreases abruptly and for SS1 becomes indetectable. The solid solution SS2 (neary= 1) has cubic symmetry down to 80 K forM= W, and a cubic-noncubic transition at low temperature forM= Mo. In any case, the phase transitions are of first order, reversible, and improper character. The transition atTCis ferroelectric, ferroelastic-paraelectric, prototype. The extent of each solid solution depends on the ratio of alcaline cations present in the 6- and 12-fold coordination sites of the perovskite structure. Des techniques expérimentales variées ont permis d'étudier les transitions de phases au sein des différentes solutions solides obtenues dans les systèmes K3MO3F3-A3MO3F3(A= Na, Rb;M= Mo, W): diffraction des rayons X, analyse thermique différentielle, microscopie optique en lumière polarisée. Les systèmes K3MO3F3-Na3MO3F3(M= Mo, W) présentent deux solutions solides. La première (SS1) au voisinage dex= 0 (K3-xNaxMO3F3) ne présente qu'une seule transition àTCqui reste pratiquement constante lorsque la composition varie; la transition qui était franche pourx= 0 àT1

  6. [Prognosis of dynamics and risk of exceeding permissible levels of 137Cs and 90Sr contents in fish in the Kiev Reservoir at the late phase of the Chernobyl accident].

    PubMed

    Homutinin, Iu V; Kashparov, V A; Kuz'menko, A V; Pavliuchenko, V V

    2013-01-01

    On the basis of the radionuclide specific activity measurements made on 832 samples of fish in 2009-2011 and taking into account literature data, the parameters of the stochastic model have been derived to describe the 137Cs and 90Sr contents in typical commercial fish species in the Kiev Reservoir at the late phase of the Chernobyl accident, including: statistical variability, seasonal changes and monotonous long-term trends. At any fixed moment of the year the standard deviations of logarithms of the 137Cs and 90Sr specific activities in carnivorous and benthophage fish species do not reliably differ, making up at average 0.4. The maximum vari- ation of the 137Cs specific activity (a four-fold decrease from April to November) was observed in pike. The obtained values of the ecological half-life periods for 137Cs and 90Sr (1.3-14 years) in fish of the Kiev reservoir in 2002-2012 were significantly lower than both the radioactive decay periods and the estimates of the IAEA Chernobyl Forum. Based on the obtained model parameters, the dynamics of the 137Cs and 90Sr specific ac- tivities in main commercial fish of the Kiev reservoir has been described and the risk of exceeding the permis- sible levels of these radionuclides in fish at the late phase of the Chernobyl accident has been estimated. Now the risk of catching fish with the specific activities of 137Cs and 90Sr above the permissible levels (150 Bq/kg and 35 Bq/kg, respectively) does not exceed 10% (except perch in the spring spawning period that is banned for fishing in Ukraine). Corresponding risks for roach, white bream and rudd are less than 0.1%.

  7. Integrated experimental and computational methods for structure determination and characterization of a new, highly stable cesium silicotitanate phase, Cs{sub 2}TiSi{sub 6}O{sub 15} (SNL-A)

    SciTech Connect

    NYMAN,MAY D.; BONHOMME,FRANCOIS R.; TETER,DAVID M.; MAXWELL,R.S.; GU,B.X.; WANG,L.M.; EWING,R.C.; NENOFF,TINA M.

    2000-04-24

    Exploratory hydrothermal synthesis in the system Cs{sub 2}O-SiO{sub 2}-TiO{sub 2}-H{sub 2}O has produced a new polymorph of Cs{sub 2}TiSi{sub 6}O{sub 15} (SNL-A) whose structure was determined using a combination of experimental and theoretical techniques ({sup 29}Si and {sup 133}Cs NMR, X-ray Rietveld refinement, and Density Functional Theory). SNL-A crystallizes in the monoclinic space-group Cc with unit cell parameters: a = 12.998(2) {angstrom}, b = 7.5014(3) {angstrom}, c = 15.156(3) {angstrom}, {eta} = 105.80(3) {degree}. The SNL-A framework consists of silicon tetrahedra and titanium octahedra which are linked in 3-, 5-, 6-, 7- and 8-membered rings in three dimensions. SNL-A is distinctive from a previously reported C2/c polymorph of Cs{sub 2}TiSi{sub 6}O{sub 15} by different ring geometries. Similarities and differences between the two structures are discussed. Other characterizations of SNL-A include TGA-DTA, Cs/Si/Ti elemental analyses, and SEM/EDS. Furthermore, the chemical and radiation durability of SNL-A was studied in interest of ceramic waste form applications. These studies show that SNL-A is durable in both radioactive and rigorous chemical environments. Finally, calculated cohesive energies of the two Cs{sub 2}TiSi{sub 6}O{sub 15} polymorphs suggest that the SNL-A phase (synthesized at 200 C) is energetically more favorable than the C2/c polymorph (synthesized at 1,050 C).

  8. Cdk5-mediated inhibition of APC/C-Cdh1 switches on the cyclin D1-Cdk4-pRb pathway causing aberrant S-phase entry of postmitotic neurons.

    PubMed

    Veas-Pérez de Tudela, Miguel; Maestre, Carolina; Delgado-Esteban, María; Bolaños, Juan P; Almeida, Angeles

    2015-12-10

    The anaphase-promoting complex/cyclosome (APC/C) is an E3 ubiquitin ligase that regulates cell cycle progression in proliferating cells. To enter the S-phase, APC/C must be inactivated by phosphorylation of its cofactor, Cdh1. In post-mitotic cells such as neurons APC/C-Cdh1 complex is highly active and responsible for the continuous degradation of mitotic cyclins. However, the specific molecular pathway that determines neuronal cell cycle blockade in post-mitotic neurons is unknown. Here, we show that activation of glutamatergic receptors in rat cortical primary neurons endogenously triggers cyclin-dependent kinase-5 (Cdk5)-mediated phosphorylation of Cdh1 leading to its cytoplasmic accumulation and disassembly from the APC3 core protein, causing APC/C inactivation. Conversely, pharmacological or genetic inhibition of Cdk5 promotes Cdh1 ubiquitination and proteasomal degradation. Furthermore, we show that Cdk5-mediated phosphorylation and inactivation of Cdh1 leads to p27 depletion, which switches on the cyclin D1-cyclin-dependent kinase-4 (Cdk4)-retinoblastoma protein (pRb) pathway to allow the S-phase entry of neurons. However, neurons do not proceed through the cell cycle and die by apoptosis. These results indicate that APC/C-Cdh1 actively suppresses an aberrant cell cycle entry and death of neurons, highlighting its critical function in neuroprotection.

  9. Accumulation of potassium, rubidium and caesium (133Cs and 137Cs in various fractions of soil and fungi in a Swedish forest.

    PubMed

    Vinichuk, M; Taylor, A F S; Rosén, K; Johanson, K J

    2010-05-15

    Radiocaesium ((137)Cs) was widely deposited over large areas of forest in Sweden as a result of the Chernobyl accident in 1986 and many people in Sweden eat wild fungi and game obtained from these contaminated forests. In terms of radioisotope accumulation in the food chain, it is well known that fungal sporocarps efficiently accumulate radiocaesium ((137)Cs), as well as the alkali metals potassium (K), rubidium (Rb) and caesium (Cs). The fungi then enhance uptake of these elements into host plants. This study compared the accumulation of these three alkali metals in bulk soil, rhizosphere, soil-root interface, fungal mycelium and sporocarps of mycorrhizal fungi in a Swedish forest. The soil-root interface was found to be distinctly enriched in K and Rb compared with the bulk soil. Potassium concentrations increased in the order: bulk soilRb concentration in the order: bulk soilRb and K than Cs, so the uptake of (137)Cs could be prevented by providing additional Rb or K at contaminated sites. The levels of K, Rb, and Cs found in sporocarps were at least one order of magnitude higher than those in fungal mycelium. These results provide new insights into the use of transfer factors or concentration ratios. The final step, the transfer of alkali metals from fungal mycelium to sporocarps, raised some specific questions about possible mechanisms.

  10. RB1, development, and cancer

    PubMed Central

    Chinnam, Meenalakshmi; Goodrich, David W.

    2013-01-01

    The RB1 gene is the first tumor suppressor gene identified whose mutational inactivation is the cause of a human cancer, the pediatric cancer retinoblastoma. The twenty five years of research since its discovery has not only illuminated a general role for RB1 in human cancer, but also its critical importance in normal development. Understanding the molecular function of the RB1 encoded protein, pRb, is a long-standing goal that promises to inform our understanding of cancer, its relationship to normal development, and possible therapeutic strategies to combat this disease. Achieving this goal has been difficult, complicated by the complexity of pRb and related proteins. The goal of this review is to explore the hypothesis that, at its core, the molecular function of pRb is to dynamically regulate the location specific assembly or disassembly of protein complexes on the DNA in response to the output of various signaling pathways. These protein complexes participate in a variety of molecular processes relevant to DNA including gene transcription, DNA replication, DNA repair, and mitosis. Through regulation of these processes, RB1 plays a uniquely prominent role in normal development and cancer. PMID:21295686

  11. High-pressure behaviour of Cs{sub 2}V{sub 3}O{sub 8} fresnoite

    SciTech Connect

    Grzechnik, Andrzej; Yeon, Jeongho; Zur Loye, Hans-Conrad; Friese, Karen

    2016-06-15

    Crystal structure of Cs{sub 2}V{sub 3}O{sub 8} fresnoite (P4bm, Z=2) has been studied using single-crystal X-ray diffraction in a diamond anvil cell to 8.6 GPa at room temperature. Cs{sub 2}V{sub 3}O{sub 8} undergoes a reversible first-order phase transition at about 4 GPa associated with anomalies in the pressure dependencies of the lattice parameters and unit-cell volume but without any symmetry change. Both structures consist of layers of corner-sharing V{sup 5+}O{sub 4} tetrahedra and V{sup 4+}O{sub 5} tetragonal pyramids separated by the Cs{sup +} cations located between the layers. At low pressures, the compression has little effect on the polarity of the structure. Above 4 GPa, the pseudosymmetry with respect to the corresponding centrosymmetric space group P4/mbm abruptly increases. The effects of external pressure and of the A{sup +} cation substitution in the vanadate fresnoites A{sub 2}V{sub 3}O{sub 8} (A{sup +}: K{sup +}, Rb{sup +}, NH{sub 4}{sup +}, Cs{sup +}) are discussed. - Graphical abstract: Non-centrosymmetric Cs{sub 2}V{sub 3}O{sub 8} undergoes a reversible first-order phase transition at about 4 GPa associated with an abrupt change of the pseudosymmetry with respect to the centrosymmetric space group P4/mbm. Display Omitted - Highlights: • High-pressure behaviour of vanadate fresnoites depends on alkali metal cations. • The size of the alkali metal cation determines whether the high-pressure phase is centrosymmetric. • No incommensurate structures are observed upon compression.

  12. 250W diode laser for low pressure Rb vapor pumping

    NASA Astrophysics Data System (ADS)

    Podvyaznyy, A.; Venus, G.; Smirnov, V.; Mokhun, O.; Koulechov, V.; Hostutler, D.; Glebov, L.

    2010-02-01

    The diode pumped alkali vapor lasers operating at subatmospheric pressure require developing of a new generation of high-power laser diode sources with about 10 GHz wide emission spectrum. The latest achievements in the technology of volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass opened new opportunities for the design and fabrication of compact external cavity laser diodes, diode bars and stacks with reflecting VBGs as output couplers. We present a diode laser system providing up to 250 W output power and emission spectral width of 20 pm (FWHM) at the wavelength of 780 nm. The stability and position of an emission wavelength is determined by the resonant wavelength of a VBG which is controlled by temperature. Stability of an emitting wavelength is within 5 pm. Thermal tuning of the wavelength provides maximum overlapping of emitting line with absorption spectrum of a Rb (rubidium)- cell. The designed system consists of 7 modules tuned to the same wavelength corresponding to D2 spectral line of Rb87 or Rb85 and coupled to a single output fiber. Analogous systems could be used for other Rb isotopes spectral lines as well as for lasers based on other alkali metal vapors (Cs and K) or any agents with narrow absorption lines.

  13. Cyclin D activates the Rb tumor suppressor by mono-phosphorylation.

    PubMed

    Narasimha, Anil M; Kaulich, Manuel; Shapiro, Gary S; Choi, Yoon J; Sicinski, Piotr; Dowdy, Steven F

    2014-06-04

    The widely accepted model of G1 cell cycle progression proposes that cyclin D:Cdk4/6 inactivates the Rb tumor suppressor during early G1 phase by progressive multi-phosphorylation, termed hypo-phosphorylation, to release E2F transcription factors. However, this model remains unproven biochemically and the biologically active form(s) of Rb remains unknown. In this study, we find that Rb is exclusively mono-phosphorylated in early G1 phase by cyclin D:Cdk4/6. Mono-phosphorylated Rb is composed of 14 independent isoforms that are all targeted by the E1a oncoprotein, but show preferential E2F binding patterns. At the late G1 Restriction Point, cyclin E:Cdk2 inactivates Rb by quantum hyper-phosphorylation. Cells undergoing a DNA damage response activate cyclin D:Cdk4/6 to generate mono-phosphorylated Rb that regulates global transcription, whereas cells undergoing differentiation utilize un-phosphorylated Rb. These observations fundamentally change our understanding of G1 cell cycle progression and show that mono-phosphorylated Rb, generated by cyclin D:Cdk4/6, is the only Rb isoform in early G1 phase.

  14. Ternary K2Zn5As4-type pnictides Rb2Cd5As4 and Rb2Zn5Sb4, and the solid solution Rb2Cd5(As,Sb)4.

    PubMed

    He, Hua; Stoyko, Stanislav S; Mar, Arthur; Bobev, Svilen

    2013-05-01

    Dirubidium pentacadmium tetraarsenide, Rb2Cd5As4, dirubidium pentazinc tetraantimonide, Rb2Zn5Sb4, and the solid-solution phase dirubidium pentacadmium tetra(arsenide/antimonide), Rb2Cd5(As,Sb)4 [or Rb2Cd5As3.00(1)Sb1.00(1)], have been prepared by direct reaction of the component elements at high temperature. These compounds are charge-balanced Zintl phases and adopt the orthorhombic K2Zn5As4-type structure (Pearson symbol oC44), featuring a three-dimensional [M5Pn4](2-) framework [M = Zn or Cd; Pn is a pnicogen or Group 15 (Group V) element] built of linked MPn4 tetrahedra, and large channels extending along the b axis which host Rb(+) cations. The As and Sb atoms in Rb2Cd5(As,Sb)4 are randomly disordered over the two available pnicogen sites. Band-structure calculations predict that Rb2Cd5As4 is a small-band-gap semiconductor and Rb2Zn5Sb4 is a semimetal.

  15. Interaction of the cesium cation with mono-, di-, and tricarboxylic acids in the gas phase. A Cs+ affinity scale for cesium carboxylates ion pairs.

    PubMed

    Mayeux, Charly; Tammiku-Taul, Jaana; Massi, Lionel; Lohu, Ene-Liis; Burk, Peeter; Maria, Pierre-Charles; Gal, Jean-François

    2009-10-01

    Humic substances (HS), including humic and fulvic acids, play a significant role in the fate of metals in soils. The interaction of metal cations with HS occurs predominantly through the ionized (anionic) acidic functions. In the context of the effect of HS on transport of radioactive cesium isotopes in soils, a study of the interaction between the cesium cation and model carboxylic acids was undertaken. Structure and energetics of the adducts formed between Cs+ and cesium carboxylate salts [Cs+RCOO-] were studied by the kinetic method and density functional theory (DFT). Clusters generated by electrospray ionization mass spectrometry from mixtures of a cesium salt (nitrate, iodide, trifluoroacetate) and carboxylic acids were quantitatively studied by CID. By combining the results of the kinetic method and the energetic data from DFT calculations, a scale of cesium cation affinity, CsCA, was built for 33 cesium carboxylates representing the first scale of cation affinity of molecular salts. The structural effects on the CsCA values are discussed.

  16. Rb based alkali antimonide high quantum efficiency photocathodes for bright electron beam sources and photon detection applications

    NASA Astrophysics Data System (ADS)

    Cultrera, L.; Gulliford, C.; Bartnik, A.; Lee, H.; Bazarov, I.

    2017-02-01

    High quantum efficiency alkali antimonide photocathodes have been grown over both stainless steel and glass substrates using sequential evaporation of Sb, K, Rb, and Cs. Quantum efficiencies well above 25% have been measured at 400 nm. A bi-alkali Rb-K-Sb photocathode grown on a stainless steel substrate has been installed in a high voltage DC gun at Cornell University and the intrinsic electron beam emittance was measured at different photon energies.

  17. Magnetic dipole bands in 82Rb, 83Rb and 84Rb

    NASA Astrophysics Data System (ADS)

    Schwengner, R.; Schnare, H.; Frauendorf, S.; Dönau, F.; Käubler, L.; Prade, H.; Grosse, E.; Jungclaus, A.; Lieb, K. P.; Lingk, C.; Skoda, S.; Eberth, J.; de Angelis, G.; Gadea, A.; Farnea, E.; Napoli, D. R.; Ur, C. A.; Lo Bianco, G.

    1998-12-01

    We have studied the isotopes 82Rb45, 83Rb46 and 84Rb47 to search for magnetic rotation which is predicted in the tilted-axis cranking model for a certain mass region around A=80. Excited states in these nuclei were populated via the reaction 11B+76Ge with E=50 MeV at the XTU tandem accelerator of the LNL Legnaro. Based on a γ-coincidence experiment using the spectrometer GASP we have found magnetic dipole bands in each studied nuclide. The regular M1 bands observed in the odd-odd nuclei 82Rb and 84Rb include B(M1)/B(E2) ratios decreasing smoothly with increasing spin in a range of 13-⩽Jπ⩽16-. These bands are interpreted in the tilted-axis cranking model on the basis of four-quasiparticle configurations of the type π(fp)πg9/22νg9/2. This is the first evidence of magnetic rotation in the A≈80 region. In contrast, the M1 sequences in the odd-even nucleus 83Rb are not regular, and the B(M1)/B(E2) ratios show a pronounced staggering.

  18. Distribution of sup 137 Cs in soils due to the Goiania accident and decisions for remedial action during the recovery phase

    SciTech Connect

    Amaral, E.C.; Vianna, M.E.; Godoy, J.M.; Rochedo, E.R.; Campos, M.J.; do Rio, M.A.; Oliveira, J.P.; Pereira, J.C.; Reis, W.G. )

    1991-01-01

    In September 1987, a powder radioactive source was removed from a teletherapy machine in Goiania, Brazil. Subsequently, it was ruptured in a residential garden causing the dissemination of {sup 137}Cs throughout the city. Soil resuspension processes and burial of contaminated house waste in unused gardens were the major contributors to the Cs dissemination in soils at the secondary contaminated sites. Only locations within a radius of 50 m from the primary contaminated sites presented the need for remedial action. The radiation dose-rate measurements and the soil profiles were good indicators of the extent of the secondary contamination and were fundamental for the decisions taken regarding decontamination procedures. In cases of surface contamination, 60% on average of the total activity remained in the upper 1.5-cm layer over the first 5 mo after the accident, and topsoil removal proved to be an effective procedure for decontamination.

  19. Cs 728 nm Laser Spectroscopy and Faraday Atomic Filter

    NASA Astrophysics Data System (ADS)

    Liu, Zhong-Zheng; Tao, Zhi-Ming; Jiang, Zhao-Jie; Chen, Jing-Biao

    2014-12-01

    We mainly present the 728 nm laser spectroscopy and Faraday atomic filter of Cs atoms with 650 MHz linewidth and 2.6% transmission based on an electrodeless discharge vapor lamp, compared with Rb 728 nm laser spectroscopy. Accidentally, this remarkably strong Cs 728 nm transition from the 6F7/2 state to the 5D5/2 state is only about 2.5 GHz away from the Rb 728 nm transition of the future potential four-level active optical clock, once laser cooled and trapped from the 7S1/2 state to the 5P1/2 state, as we proposed previously. A Faraday atomic filter stabilized 728 nm laser using a Cs electrodeless discharge vapor lamp with a power of 10mW will provide a frequency reference to evaluate the performance of the potential Rb four-level active optical clock at 728 nm with power less than 1 nW by 2.5 GHz heterodyne measurements.

  20. Cortical excitatory neurons become protected from cell division during neurogenesis in an Rb family-dependent manner.

    PubMed

    Oshikawa, Mio; Okada, Kei; Nakajima, Kazunori; Ajioka, Itsuki

    2013-06-01

    Cell cycle dysregulation leads to abnormal proliferation and cell death in a context-specific manner. Cell cycle progression driven via the Rb pathway forces neurons to undergo S-phase, resulting in cell death associated with the progression of neuronal degeneration. Nevertheless, some Rb- and Rb family (Rb, p107 and p130)-deficient differentiating neurons can proliferate and form tumors. Here, we found in mouse that differentiating cerebral cortical excitatory neurons underwent S-phase progression but not cell division after acute Rb family inactivation in differentiating neurons. However, the differentiating neurons underwent cell division and proliferated when Rb family members were inactivated in cortical progenitors. Differentiating neurons generated from Rb(-/-); p107(-/-); p130(-/-) (Rb-TKO) progenitors, but not acutely inactivated Rb-TKO differentiating neurons, activated the DNA double-strand break (DSB) repair pathway without increasing trimethylation at lysine 20 of histone H4 (H4K20), which has a role in protection against DNA damage. The activation of the DSB repair pathway was essential for the cell division of Rb-TKO differentiating neurons. These results suggest that newly born cortical neurons from progenitors become epigenetically protected from DNA damage and cell division in an Rb family-dependent manner.

  1. Pressure-induced metathesis reaction to sequester Cs.

    PubMed

    Im, Junhyuck; Seoung, Donghoon; Lee, Seung Yeop; Blom, Douglas A; Vogt, Thomas; Kao, Chi-Chang; Lee, Yongjae

    2015-01-06

    We report here a pressure-driven metathesis reaction where Ag-exchanged natrolite (Ag16Al16Si24O80·16H2O, Ag-NAT) is pressurized in an aqueous CsI solution, resulting in the exchange of Ag(+) by Cs(+) in the natrolite framework forming Cs16Al16Si24O80·16H2O (Cs-NAT-I) and, above 0.5 GPa, its high-pressure polymorph (Cs-NAT-II). During the initial cation exchange, the precipitation of AgI occurs. Additional pressure and heat at 2 GPa and 160 °C transforms Cs-NAT-II to a pollucite-related, highly dense, and water-free triclinic phase with nominal composition CsAlSi2O6. At ambient temperature after pressure release, the Cs remains sequestered in a now monoclinic pollucite phase at close to 40 wt % and a favorably low Cs leaching rate under back-exchange conditions. This process thus efficiently combines the pressure-driven separation of Cs and I at ambient temperature with the subsequent sequestration of Cs under moderate pressures and temperatures in its preferred waste form suitable for long-term storage at ambient conditions. The zeolite pollucite CsAlSi2O6·H2O has been identified as a potential host material for nuclear waste remediation of anthropogenic (137)Cs due to its chemical and thermal stability, low leaching rate, and the large amount of Cs it can contain. The new water-free pollucite phase we characterize during our process will not display radiolysis of water during longterm storage while maintaining the Cs content and low leaching rate.

  2. Improving CS regulations.

    SciTech Connect

    Nesse, R.J.; Scheer, R.M.; Marasco, A.L.; Furey, R.

    1980-10-01

    President Carter issued Executive Order 12044 (3/28/78) that required all Federal agencies to distinguish between significant and insignificant regulations, and to determine whether a regulation will result in major impacts. This study gathered information on the impact of the order and the guidelines on the Office of Conservation and Solar Energy (CS) regulatory practices, investigated problems encountered by the CS staff when implementing the order and guidelines, and recommended solutions to resolve these problems. Major tasks accomplished and discussed are: (1) legislation, Executive Orders, and DOE Memoranda concerning Federal administrative procedures relevant to the development and analysis of regulations within CS reviewed; (2) relevant DOE Orders and Memoranda analyzed and key DOE and CS staff interviewed in order to accurately describe the current CS regulatory process; (3) DOE staff from the Office of the General Counsel, the Office of Policy and Evaluation, the Office of the Environment, and the Office of the Secretary interviewed to explore issues and problems encountered with current CS regulatory practices; (4) the regulatory processes at five other Federal agencies reviewed in order to see how other agencies have approached the regulatory process, dealt with specific regulatory problems, and responded to the Executive Order; and (5) based on the results of the preceding four tasks, recommendations for potential solutions to the CS regulatory problems developed. (MCW)

  3. Temperature and composition phase diagram in the iron-based ladder compounds Ba 1 - x Cs x Fe 2 Se 3

    SciTech Connect

    Hawai, Takafumi; Nambu, Yusuke; Ohgushi, Kenya; Du, Fei; Hirata, Yasuyuki; Avdeev, Maxim; Uwatoko, Yoshiya; Sekine, Yurina; Fukazawa, Hiroshi; Ma, Jie; Chi, Songxue; Ueda, Yutaka; Yoshizawa, Hideki; Sato, Taku J.

    2015-05-28

    We investigated the iron-based ladder compounds (Ba,Cs)Fe₂Se₃. Their parent compounds BaFe₂Se₃ and CsFe₂Se₃ have different space groups, formal valences of Fe, and magnetic structures. Electrical resistivity, specific heat, magnetic susceptibility, x-ray diffraction, and powder neutron diffraction measurements were conducted to obtain a temperature and composition phase diagram of this system. Block magnetism observed in BaFe₂Se₃ is drastically suppressed with Cs doping. In contrast, stripe magnetism observed in CsFe₂Se₃ is not so fragile against Ba doping. A new type of magnetic structure appears in intermediate compositions, which is similar to stripe magnetism of CsFe₂Se₃, but interladder spin configuration is different. Intermediate compounds show insulating behavior, nevertheless a finite T-linear contribution in specific heat was obtained at low temperatures.

  4. Fluorine speciation analysis using reverse phase liquid chromatography coupled off-line to continuum source molecular absorption spectrometry (CS-MAS): identification and quantification of novel fluorinated organic compounds in environmental and biological samples.

    PubMed

    Qin, Zhiwei; McNee, David; Gleisner, Heike; Raab, Andrea; Kyeremeh, Kwaku; Jaspars, Marcel; Krupp, Eva; Deng, Hai; Feldmann, Jörg

    2012-07-17

    Driven by increasing demand for the monitoring of industrial perfluorinated compounds (PFCs), the identification of novel fluorine containing compounds (FOCs) and the tracking of organofluorine drugs and their degradation products, there is a clear need for sensitive, fluorine-specific detection of unknown FOCs. Here we report the first ever direct fluorine-specific (speciation) method; capable of individually detecting untargeted FOCs in environmental and biological samples through the application of continuum source molecular absorption spectrometry (CS-MAS) using a commercial CS-AAS. Two model FOCs (2,4,6, trifluorobenzoic acid (TFBA) and 5-fluoroindol-5-carboxylic acid (FICA)) were used, achieving fluorine-specific detection across a range of 0.1 to 300 ng/mL fluorine, corresponding to a limit of detection of 4 pg F and 5.26 nM for both compounds. Both TFBA and FICA showed a similar response to CS-MAS detection, potentially enabling the quantification of fluorine content in novel FOCs without having molecular standards available. This paper also reports the use of reverse-phase high performance liquid chromatography (RP-HPLC) coupled off-line with CS-MAS for the identification of single organofluorines in a mixture of FOCs via fraction collection. The linear range of both FOCs was determined to be from 1 to 500 ng/mL. The limits of detection of those species were just above 1 ng/mL (100 pg) and can therefore compete with targeted analytical methods such as ESI-MS. Finally, as a proof of principle the analysis of a fluoride-containing groundwater sample from Ghana demonstrated that this method can be used in the detection of novel FOCs, with identification achieved through parallel ESI-MS. Coupled HPLC-CS-MAS/ESI-MS is the first analytical methodology capable of selectively detecting and identifying novel FOCs, making possible the quantification of all fluorine containing compounds in one sample. This is the necessary analytical requirement to perform

  5. Phase diagram and thermodynamic calculations of alkali and alkaline earth metal zirconates

    NASA Astrophysics Data System (ADS)

    Dash, Smruti; Sood, D. D.; Prasad, R.

    1996-02-01

    The ternary phase diagrams and partial pressures of various gaseous species over the equilibrium phase fields have been calculated for the MZrO (M = Li, Na, K, Rb, Cs, Sr and Ba) systems by using the SOLGASMIX-PV program, which computes equilibrium composition by direct minimization of the Gibbs energy of a system. The available experimental Gibbs energy data reported in the literature for binary and ternary compounds were used for these calculations. Where no data exist, values were estimated. These ternary phase diagrams are being reported for the first time, except for the lithium system.

  6. RB1 in cancer: different mechanisms of RB1 inactivation and alterations of pRb pathway in tumorigenesis.

    PubMed

    Di Fiore, Riccardo; D'Anneo, Antonella; Tesoriere, Giovanni; Vento, Renza

    2013-08-01

    Loss of RB1 gene is considered either a causal or an accelerating event in retinoblastoma. A variety of mechanisms inactivates RB1 gene, including intragenic mutations, loss of expression by methylation and chromosomal deletions, with effects which are species-and cell type-specific. RB1 deletion can even lead to aneuploidy thus greatly increasing cancer risk. The RB1gene is part of a larger gene family that includes RBL1 and RBL2, each of the three encoding structurally related proteins indicated as pRb, p107, and p130, respectively. The great interest in these genes and proteins springs from their ability to slow down neoplastic growth. pRb can associate with various proteins by which it can regulate a great number of cellular activities. In particular, its association with the E2F transcription factor family allows the control of the main pRb functions, while the loss of these interactions greatly enhances cancer development. As RB1 gene, also pRb can be functionally inactivated through disparate mechanisms which are often tissue specific and dependent on the scenario of the involved tumor suppressors and oncogenes. The critical role of the context is complicated by the different functions played by the RB proteins and the E2F family members. In this review, we want to emphasize the importance of the mechanisms of RB1/pRb inactivation in inducing cancer cell development. The review is divided in three chapters describing in succession the mechanisms of RB1 inactivation in cancer cells, the alterations of pRb pathway in tumorigenesis and the RB protein and E2F family in cancer.

  7. What’s So Special about RB?

    PubMed Central

    Burd, Christin E.; Sharpless, Norman E.

    2013-01-01

    RB, p107, and p130 are highly related proteins, each capable of regulating cellular proliferation. However, only RB is frequently mutated in cancer. In this issue of Cancer Cell, Chicas et al. shed new light on this conundrum, defining a “special,” nonredundant role for RB in promoting cellular senescence. PMID:20385355

  8. First-principles study of paraelectric and ferroelectric CsH2PO4 including dispersion forces: Stability and related vibrational, dielectric, and elastic properties

    NASA Astrophysics Data System (ADS)

    Van Troeye, Benoit; van Setten, Michiel Jan; Giantomassi, Matteo; Torrent, Marc; Rignanese, Gian-Marco; Gonze, Xavier

    2017-01-01

    Using density functional theory (DFT) and density functional perturbation theory (DFPT), we investigate the stability and response functions of CsH2PO4 , a ferroelectric material at low temperature. This material cannot be described properly by the usual (semi)local approximations within DFT. The long-range e--e- correlation needs to be properly taken into account, using, for instance, Grimme's DFT-D methods, as investigated in this work. We find that DFT-D3(BJ) performs the best for the members of the dihydrogenated alkali phosphate family (KH2PO4 , RbH2PO4 , CsH2PO4 ), leading to experimental lattice parameters reproduced with an average deviation of 0.5%. With these DFT-D methods, the structural, dielectric, vibrational, and mechanical properties of CsH2PO4 are globally in excellent agreement with the available experiments (<2 % MAPE for Raman-active phonons). Our study suggests the possible existence of a new low-temperature phase of CsH2PO4 , not yet reported experimentally. Finally, we report the implementation of DFT-D contributions to elastic constants within DFPT.

  9. EXTRAGALACTIC CS SURVEY

    SciTech Connect

    Bayet, E.; Viti, S.; Aladro, R.; MartIn, S.; MartIn-Pintado, J.

    2009-12-10

    We present a coherent and homogeneous multi-line study of the CS molecule in nearby (D < 10 Mpc) galaxies. We include, from the literature, all the available observations from the J = 1-0 to the J = 7-6 transitions toward NGC 253, NGC 1068, IC 342, Henize 2-10, M 82, the Antennae Galaxies, and M 83. We have, for the first time, detected the CS(7-6) line in NGC 253, M 82 (both in the northeast and southwest molecular lobes), NGC 4038, M 83 and tentatively in NGC 1068, IC 342, and Henize 2-10. We use the CS molecule as a tracer of the densest gas component of the interstellar medium in extragalactic star-forming regions, following previous theoretical and observational studies by Bayet et al. In this first paper out of a series, we analyze the CS data sample under both local thermodynamical equilibrium (LTE) and non-LTE (large velocity gradient) approximations. We show that except for M 83 and Overlap (a shifted gas-rich position from the nucleus NGC 4039 in the Antennae Galaxies), the observations in NGC 253, IC 342, M 82-NE, M 82-SW, and NGC 4038 are not well reproduced by a single set of gas component properties and that, at least, two gas components are required. For each gas component, we provide estimates of the corresponding kinetic temperature, total CS column density, and gas density.

  10. DFT study of Rb-TFA structure after high-pressure action

    NASA Astrophysics Data System (ADS)

    Scholtzová, Eva

    2011-12-01

    The pressure-induced A-B phase transition of synthetic Rb-tetra-ferri-annite (Rb-TFA) mica was studied theoretically by means of Density Functional Theory (DFT) method. The calculations show that Rb-TFA keeps a Franzini A-type structure up to at least 5.39 GPa of pressure, whereas at higher pressure, it transforms to a Franzini B-type structure. The negative value of the tetrahedral rotation angle α = -4.68° has appeared at 5.56 GPa of calculated pressure. This result is in a relatively good agreement with experimentally estimated phase transition area in the range of 3.36-3.84 GPa. The energy difference between the A and B structures is very small (ΔE = 8 kJ/mol). The detailed analysis of the optimized structural data shows minimal changes in the structure of Rb-TFA after the pressure-induced phase transition.

  11. Luminescence of the elpasolite series M{sup I}{sub 2}M{sup II}MCl{sub 6} (M{sup I}=Cs, Rb; M{sup II}=Li, Na; M=Lu, Y, Sc, In) doped with europium using synchrotron radiation excitation

    SciTech Connect

    Tanner, Peter A.; Duan Changkui; Jia Guohua; Cheng, Bing-Ming

    2012-04-15

    The excitation and emission spectra of a series of cubic hexachloroelpasolites doped with europium have been investigated using synchrotron radiation at 10 K. Besides the Eu{sup 3+} emission from {sup 5}D{sub J} (J=0-3) multiplets, emission from {sup 5}H{sub 3} is also observed for Cs{sub 2}NaIn{sub 0.995}Eu{sub 0.005}Cl{sub 6}, since the gap to the next lowest level is spanned by seven phonons. The excitation spectra of samples indicate impurities due to oxygen and divalent europium. Broad band emission from Eu{sup 2+} is reported from the crystalline samples grown in vacuum by the Bridgman process, with the maximum wavelength shifting to the red with increasing lattice parameter for the series Cs{sub 2}NaMCl{sub 6}:Eu{sup 2+} (M=Lu, Y, Eu). - Graphical abstract: Luminescence of Eu{sup 3+} and Eu{sup 2+} in elpasolite hosts under synchrotron radiation is observed and assigned. Highlights: Black-Right-Pointing-Pointer Synthesis of M{sup I}{sub 2}M{sup II}MCl{sub 6}-doped with europium. Black-Right-Pointing-Pointer 10 K spectra indicate broad bands due to Eu-O CT, Eu-Cl CT and Eu{sup 2+} transitions. Black-Right-Pointing-Pointer Ultraviolet emission from the {sup 3}H{sub 5} level of Eu{sup 3+}, not only restricted to fluorides. Black-Right-Pointing-Pointer Correlation between Eu{sup 2+} emission maximum and host lattice parameter.

  12. High-accuracy measurement of the 87Rb ground-state hyperfine splitting in an atomic fountain

    NASA Astrophysics Data System (ADS)

    Bize, S.; Sortais, Y.; Santos, M. S.; Mandache, C.; Clairon, A.; Salomon, C.

    1999-03-01

    We describe the operation of a laser-cooled rubidium 87Rb frequency standard. We present a new measurement of the 87Rb hyperfine frequency with a 1.3 × 10-14 relative accuracy, by comparison with a Cs fountain primary standard. The measured 87Rb ground-state hyperfine splitting is ν87 = 6 834 682 610.90429(9) Hz. This value differs from previously published values (see Essen L., Hope E. G. and Sutcliffe D., Nature 189 1961 298; Penselin S., Moran T., Cohen W. and Wscinkler G., Phys. Rev. 127 1962 524; Arditi M. and Cerez P. IEEE Trans. Instrum. Meas. IM-21 1972 391) by about 2 - 3 Hz and is 104 times more accurate. Because of the low collisional shift in 87Rb, future improvements may lead to a stability of 1 × 10-14τ-1/2 and a relative accuracy in the 10-17 range.

  13. Inorganic materis for anomalous-dispersion phase-matched second harmonic generation: Rubidium titanyl arsenate isomorphs, Rb[Ti{sub 1-2x}Ln{sub x}Nb{sub x}]OAsO{sub 4}

    SciTech Connect

    Anderson, M.T.; Phillips, M.L.F.; Stucky, G.D.

    1993-12-31

    We report the synthesis and optical properties of Rb[Ti{sub 1-2x}Ln{sub x}Nb{sub x}]OAsO{sub 4}. The solid solubility of lanthanide ions in the materials decreases exponentially as the size of the lanthanide ion increases. The materials exhibit absorption spectra characteristic of the particular lanthanide ion in the structure. The spectral regions between absorption peaks are transparent and will allow the transmission of fundamental and second-harmonic radiation. The charge transfer band is red-shifted 0 to 27 nm relative to RbTiOAsO{sub 4} (midpoint 331 nm). Second-harmonic intensities measured at 532 nm decrease exponentially as lanthanide ion concentration increases.

  14. Rb depletion in biotites and whole rocks across an amphibolite to granulite facies transition zone, Tamil Nadu, South India

    NASA Astrophysics Data System (ADS)

    Hansen, Edward; Ahmed, Khurram; Harlov, Daniel E.

    2002-09-01

    Relatively low concentrations of Rb and high K/Rb ratios are characteristic of many granulite facies terranes. This depletion in Rb has been attributed to both the removal of a partial melt and exchange with a metamorphic fluid phase. These models have been tested using Rb concentrations in biotites and whole rocks from intermediate and felsic gneisses collected along a traverse from just north of Krishnagiri to just north of Salem in Tamil Nadu State, South India. Along this traverse, the northern amphibolite-facies zone gives way to a clinopyroxene zone in which clinopyroxene appears in intermediate and felsic gneisses. Further south is the lowland charnockite zone characterised by the presence of orthopyroxene and the scarcity of clinopyroxene in intermediate to felsic gneisses. The abundance of orthopyroxene increases southwards and it is the dominant ferromagnesium silicate in the highland charnockite zone. There is a good correlation between Rb in biotite and whole-rock Rb in samples collected throughout the traverse. Intermediate and felsic gneisses in the northern portion of this traverse have relatively high modal abundances of biotite, low Ti concentrations in the biotites, high whole-rock Rb concentrations, low K/Rb ratios and high Rb concentrations within the biotites. Ti concentrations in the biotites increase southward into the clinopyroxene zone and then remain relatively constant. High K/Rb ratios first appear at the southern boundary of the clinopyroxene zone. In the lowland and highland charnockite zones, the majority of the rocks have relatively low Rb concentrations and high K/Rb ratios. Low Rb concentrations in biotites (at or near the detection limit of 65 ppm) first appear in the lowland charnockite zone and persist into the highland charnockite zone. A smaller group of rocks in the highland charnockite zone contain biotites with moderate Rb concentrations. Most of these rocks also contain anomalously high biotite concentrations and low K/Rb

  15. Observation of broad p -wave Feshbach resonances in ultracold 85Rb-87Rb mixtures

    NASA Astrophysics Data System (ADS)

    Dong, Shen; Cui, Yue; Shen, Chuyang; Wu, Yewei; Tey, Meng Khoon; You, Li; Gao, Bo

    2016-12-01

    We observe Feshbach resonances in ultracold mixtures of 85Rb and 87Rb atoms in the 85Rb|2 ,+2 >+87Rb|1 ,+1 > and 85Rb|2 ,-2 >+87Rb|1 ,-1 > scattering channels. The positions and properties of the resonances are predicted and characterized using the semianalytic multichannel quantum-defect theory by Gao. Of particular interest, a number of broad entrance-channel-dominated p -wave resonances are identified, implicating exciting opportunities for studying a variety of p -wave interaction-dominated physics.

  16. HAUSP, a novel deubiquitinase for Rb - MDM2 the critical regulator.

    PubMed

    Bhattacharya, Seemana; Ghosh, Mrinal K

    2014-07-01

    Tumor suppressor retinoblastoma-associated protein (Rb) is an important cell cycle regulator, arresting cells in early G1. It is commonly inactivated in cancers and its level is maintained during the cell cycle. Rb is regulated by various post-translational modifications such as phosphorylation, acetylation, ubiquitination and so on. Several E3 ligases including murine double minute 2 (MDM2) promote the degradation of Rb. This study focuses on the role of HAUSP (herpes virus associated ubiquitin specific protease) on Rb. Here, we show that HAUSP colocalizes and interacts with Rb to stabilize it from proteasomal degradation by removing wild-type and K48-linked ubiquitin chains in human embryonic kidney 293 (HEK293) cells. HAUSP deubiquitinates Rb in vivo and in vitro, leading to an increased cell population in the G1 phase. Hence, HAUSP is a novel deubiquitinase for Rb. Immunohistochemistry, western blotting and cell-based assays show that HAUSP is overexpressed in glioma and contributes towards glioma progression. However, HAUSP activity on Rb is abrogated in glioma (cancer), where these two proteins show an inverse relationship. MDM2 (a known substrate of HAUSP) serves as a better target for HAUSP-mediated deubiquitination in cancer cells, facilitating degradation of Rb and oncogenic progression. This novel regulatory axis is proteasome mediated, p53 independent, and the level of MDM2 is critical. The shift in equilibrium by differential deubiquitination in regulation of Rb explains a subtle difference existing between normal and cancer cells. This leads to speculation about a new possibility for distinguishing cancer cells from normal cells at the molecular level, which may be investigated for therapeutic intervention in the future.

  17. Layered polymeric nitrogen in RbN3 at high pressures

    PubMed Central

    Wang, Xiaoli; Li, Jianfu; Xu, Ning; Zhu, Hongyang; Hu, Ziyu; Chen, Li

    2015-01-01

    The structural evolutionary behaviors of nitrogen in RbN3 have been studied up to 300 GPa using a particle swarm optimization structure searching method combined with density functional calculations. Three stable new phases with P-1, P6/mmm and C2/m structure at pressure of 30, 50 and 200 GPa are identified for the first time. The analysis of the crystal structures of three new predicated phases reveals that the transition of N3− ions goes from linear molecules to polymeric chains, benzene-like rings and then to polymeric layers induced by pressure. The electronic structures of three predicted phases reveal that the structural changes are accompanied and driven by the change of orbital hybridization of N atoms from sp to sp2 and finally to partial sp3. Most interestingly, the Rb atoms show obvious transition metal-like properties through the occupation of 4d orbitals in high-pressure phases. Moreover, the Rb atoms are characterized by strong hybridization between 4d orbitals of Rb and 2p orbitals of N in C2/m structure. Our studies complete the structural evolution of RbN3 under pressure and reveal for the first time that the Rb atoms in rubidium nitride possess transition element-like properties under pressure. PMID:26564812

  18. Ba2+-inhibitable /sup 86/Rb+ fluxes across membranes of vesicles from toad urinary bladder

    SciTech Connect

    Garty, H.; Civan, M.M.

    1987-01-01

    /sup 86/Rb+ fluxes have been measured in suspensions of vesicles prepared from the epithelium of toad urinary bladder. A readily measurable barium-sensitive, ouabain-insensitive component has been identified; the concentration of external Ba2+ required for half-maximal inhibition was 0.6 mM. The effects of externally added cations on /sup 86/Rb+ influx and efflux have established that this pathway is conductive, with a selectivity for K+, Rb+ and Cs+ over Na+ and Li+. The Rb+ uptake is inversely dependent on external pH, but not significantly affected by internal Ca2+ or external amiloride, quinine, quinidine or lidocaine. It is likely, albeit not yet certain, that the conductive Rb+ pathway is incorporated in basolateral vesicles oriented right-side-out. It is also not yet clear whether this pathway comprises the principle basolateral K+ channel in vivo, and that its properties have been unchanged during the preparative procedures. Subject to these caveats, the data suggest that the inhibition by quinidine of Na+ transport across toad bladder does not arise primarily from membrane depolarization produced by a direct blockage of the basolateral channels. It now seems more likely that the quinidine-induced elevation of intracellular Ca2+ activity directly blocks apical Na+ entry.

  19. Activation of CS2 and CS by ML3 complexes.

    PubMed

    Ariafard, Alireza; Brookes, Nigel J; Stranger, Robert; Yates, Brian F

    2008-09-10

    The aim of this study was to determine the best neutral ML3 metal complexes for activating and cleaving the multiple bonds in CS2 and CS. Current experimental results show that, so far, only one bond in CS2 can be cleaved, and that CS can be activated but the bond is not broken. In the work described in this paper, density functional theory calculations have been used to evaluate the effectiveness of different ML3 complexes to activate the C-S bonds in CS2 and CS, with M = Mo, Re, W, and Ta and L = NH2. These calculations show that the combination of Re and Ta in the L3Re/CS2/TaL3 complex would be the most promising system for the cleavage of both C-S bonds of CS2. The reaction to cleave both C-S bonds is predicted to be exothermic by about 700 kJ mol(-1) and to proceed in an almost barrierless fashion. In addition, we are able to rationalize why the breaking of the C-S bond in CS has not been observed experimentally with M = Mo: this reaction is strongly endothermic. There is a subtle interplay between charge transfer and pi back-donation, and it appears that the Mo-C and Mo-S bonds are not strong enough to compensate for the breaking of the C-S bond. Our results suggest that, instead, CS could be cleaved with ReL3 or, even better, with a combination of ReL3 and TaL3. Molecular orbitals and Mulliken charges have been used to help explain these trends and to make predictions about the most promising systems for future experimental exploration.

  20. CsEuBr3: Crystal structure and its role in the photostimulation of CsBr :Eu2+

    NASA Astrophysics Data System (ADS)

    Hesse, S.; Zimmermann, J.; von Seggern, H.; Ehrenberg, H.; Fuess, H.; Fasel, C.; Riedel, R.

    2006-10-01

    CsBr :Eu2+ has recently been investigated as a photostimulable x-ray storage phosphor with great potential for application in high-resolution image plates. In a recent paper Hackenschmied et al. [J. Appl. Phys. 93, 5109 (2003)] suggested that segregations of CsEuBr3 or Cs4EuBr6 formed within CsBr :Eu2+ during annealing are responsible for an increase in the photostimulated luminescence (PSL) yield. In this work single crystals of CsEuBr3 were prepared by a one step synthesis and identified by x-ray diffraction (XRD) analysis as single phase perovskites. It was concluded that, after preparation, CsEuBr3 degrades in normal atmosphere into at least two phases, one of which is the orthorhombic structure of Cs2EuBr5•10H2O. The XRD powder diffraction pattern of this compound is very similar to that of the segregations observed within CsBr :Eu2+ and reported by Hackenschmied et al. However, the increased PSL yield in CsBr :Eu2+ after annealing cannot be due to the segregations, because the trivalent nature of the europium in the segregations renders them PSL inactive.

  1. Near-yrast, medium-spin, excited states of {sup 91}Rb, {sup 93}Rb, and {sup 95}Rb

    SciTech Connect

    Simpson, G. S.; Sieja, K.; Dare, J. A.; Orlandi, R.; Smith, A. G.; Tsekhanovich, I.; Varley, B. J.; Durell, J. L.; Smith, J. F.; Jolie, J.; Linneman, A.; Scherillo, A.; Soldner, T.; Faust, H.; Zlomaniec, A.; Rzaca-Urban, T.; Ahmad, I.; Greene, J. P.

    2010-08-15

    The medium-spin structure of the nuclei {sup 93}Rb and {sup 95}Rb is studied following the neutron-induced fission of {sup 235}U at the PF1B neutron guide, using the FIFI spectrometer, and at the Lohengrin mass spectrometer of the Institut Laue-Langevin Grenoble. These nuclei, plus {sup 91}Rb, are also studied following the spontaneous fission of {sup 248}Cm and {sup 252}Cf sources, using the EUROGAM-II and Gammasphere detector arrays, respectively. A high-spin isomeric state, with a half-life of 111(11) ns, is found in {sup 93}Rb at an excitation energy of 4422.4 keV, which most likely corresponds to the fully aligned [{pi}(g{sub 9/2}) x {nu}(g{sub 7/2}h{sub 11/2})]{sub 27/2}{sup -} configuration. An analogous configuration is proposed for the 5297.9-keV level observed in {sup 91}Rb. A new E3 decay branch of the 1133.9-keV isomer in {sup 91}Rb is found, for which the rather low transition rate of B(E3)=3.8(10) W.u. is determined. The energy of the isomeric state of {sup 95}Rb is now proposed to be at 810.6 keV, with a spin of (9/2{sup +}), and its half-life determined to be T{sub 1/2}=94(7) ns. A cascade of prompt transitions is observed on top of the 810.6-keV isomer in {sup 95}Rb. The near-yrast structures of {sup 91}Rb, {sup 93}Rb, and {sup 95}Rb are compared to the results of shell-model calculations, which support the proposed 27/2{sup -} interpretation of states in {sup 91}Rb and {sup 93}Rb. An analogous 27/2{sup -} state is expected to occur in {sup 95}Rb, as a long-lived isomer at 3.24 MeV. No such isomeric decay could be observed in a measurement using the Lohengrin spectrometer, which shows that, if it exists, its population, following the fission of {sup 235}U, is at least four times lower than that of the analogous 27/2{sup -} isomer in {sup 97}Y.

  2. The N-Terminal Phosphorylation of RB by p38 Bypasses Its Inactivation by CDKs and Prevents Proliferation in Cancer Cells.

    PubMed

    Gubern, Albert; Joaquin, Manel; Marquès, Miriam; Maseres, Pedro; Garcia-Garcia, Javier; Amat, Ramon; González-Nuñez, Daniel; Oliva, Baldo; Real, Francisco X; de Nadal, Eulàlia; Posas, Francesc

    2016-10-06

    Control of the G1/S phase transition by the Retinoblastoma (RB) tumor suppressor is critical for the proliferation of normal cells in tissues, and its inactivation is one of the most fundamental events leading to cancer. Cyclin-dependent kinase (CDK) phosphorylation inactivates RB to promote cell cycle-regulated gene expression. Here we show that, upon stress, the p38 stress-activated protein kinase (SAPK) maximizes cell survival by downregulating E2F gene expression through the targeting of RB. RB undergoes selective phosphorylation by p38 in its N terminus; these phosphorylations render RB insensitive to the inactivation by CDKs. p38 phosphorylation of RB increases its affinity toward the E2F transcription factor, represses gene expression, and delays cell-cycle progression. Remarkably, introduction of a RB phosphomimetic mutant in cancer cells reduces colony formation and decreases their proliferative and tumorigenic potential in mice.

  3. Reaction-transport-mechanical (RTM) simulator Sym.CS: Putting together water-rock interaction, multi-phase and heat flow, composite petrophysics model, and fracture mechanics

    NASA Astrophysics Data System (ADS)

    Paolini, C.; Park, A. J.; Mellors, R. J.; Castillo, J.

    2009-12-01

    A typical CO2 sequestration scenario involves the use of multiple simulators for addressing multiphase fluid and heat flow, water-rock interaction and mass-transfer, rock mechanics, and other chemical and physical processes. The benefit of such workflow is that each model can be constrained rigorously; however, the drawback is final modeling results may achieve only a limited extent of the theoretically possible capabilities of each model. Furthermore, such an approach in modeling carbon sequestration cannot capture the nonlinearity of the various chemical and physical processes. Hence, the models can only provide guidelines for carbon sequestration processes with large margins of error. As an alternative, a simulator is being constructed by a multi-disciplinary team with the aim of implementing a large array of fundamental phenomenologies, including, but not limited to: water-rock interaction using elemental mass-balance and explicit mass-transfer and reaction coupling methods; multi-phase and heat flow, including super-critical CO2 and oil; fracture mechanics with anisotropic permeabilities; rheological rock mechanics based on incremental stress theory; and a composite petrophysics model capable of describing changing rock composition and properties. The modules representing the processes will be solved using a layered iteration method, with the goal of capturing the nonlinear feedback among all of the processes. The simulator will be constructed using proven optimization and modular, object-oriented, and service-oriented programming methods. Finally, a novel AJAX (asynchronous JavaScript and XML) user interface is being tested to host the simulator that will allow usage through an Internet browser. Currently, the water-rock interaction, composite petrophysics, and multi-phase fluid and heat flow modules are available for integration. Results of the water-rock interaction and petrophysics coupling has been used to model interaction between a CO2-charged water and

  4. Rb-Sr Isotopic Systematics of Alkali-Rich Fragments in the Yamato-74442 LL-Chondritic Breccia

    NASA Technical Reports Server (NTRS)

    Yokoyama, T.; Misawa, K.; Okano, O.; Shih, C.-Y.; Nyquist, L. E.; Simo, J. I.; Tappa, M. J.; Yoneda, S.

    2012-01-01

    Alkali-rich igneous fragments were identified in the brecciated LL-chondrites, Kr henberg (LL5)], Bhola (LL3-6) and Yamato (Y)-74442 (LL4), and show characteristic fractionation patterns of alkaline elements. The K-Rb-Cs-rich fragments in Kr henberg, Bhola, and Y-74442 are very similar in mineralogy and petrography (olivine + pyroxene + glass), suggesting that they could have come from related precursor materials. We have undertaken Rb-Sr isotopic studies on alkali-rich fragments in Y-74442 to precisely determine their crystallization ages and the isotopic signatures of their precursor material(s).

  5. RB Loss Promotes Prostate Cancer Metastasis.

    PubMed

    Thangavel, Chellappagounder; Boopathi, Ettickan; Liu, Yi; Haber, Alex; Ertel, Adam; Bhardwaj, Anshul; Addya, Sankar; Williams, Noelle; Ciment, Stephen J; Cotzia, Paolo; Dean, Jeffry L; Snook, Adam; McNair, Chris; Price, Matt; Hernandez, James R; Zhao, Shuang G; Birbe, Ruth; McCarthy, James B; Turley, Eva A; Pienta, Kenneth J; Feng, Felix Y; Dicker, Adam P; Knudsen, Karen E; Den, Robert B

    2017-02-15

    RB loss occurs commonly in neoplasia but its contributions to advanced cancer have not been assessed directly. Here we show that RB loss in multiple murine models of cancer produces a prometastatic phenotype. Gene expression analyses showed that regulation of the cell motility receptor RHAMM by the RB/E2F pathway was critical for epithelial-mesenchymal transition, motility, and invasion by cancer cells. Genetic modulation or pharmacologic inhibition of RHAMM activity was sufficient and necessary for metastatic phenotypes induced by RB loss in prostate cancer. Mechanistic studies in this setting established that RHAMM stabilized F-actin polymerization by controlling ROCK signaling. Collectively, our findings show how RB loss drives metastatic capacity and highlight RHAMM as a candidate therapeutic target for treating advanced prostate cancer. Cancer Res; 77(4); 982-95. ©2016 AACR.

  6. Luminescence of CsPbBr 3-like quantum dots in CsBr single crystals

    NASA Astrophysics Data System (ADS)

    Nikl, M.; Nitsch, K.; Mihóková, E.; Polák, K.; Fabeni, P.; Pazzi, G. P.; Gurioli, M.; Santucci, S.; Phani, R.; Scacco, A.; Somma, F.

    Luminescence and decay kinetics of the Pb 2+ aggregates in CsBr host crystals were measured in the 4-300 K temperature interval and in 10 -10-10 -3 time scale. Their emission properties are similar to those of CsPbBr 3 bulk crystal showing a subnanosecond free exciton emission in the 520-540 nm spectral region and slower trapped exciton emission in the 530-580 nm spectral region. An efficient energy exchange between the free and trapped exciton states is shown by the temperature dependencies of emission spectra. The quantum size effect is demonstrated in the high energy shift and broadening of the absorption and emission spectra and an estimate of the size of the CsPbBr 3-like aggregates is provided. Independent evidence of the presence of the CsPbBr 3 and Cs 4PbBr 6 aggregated phases in the CsBr host was obtained by X-ray structural studies.

  7. On the possibility for Rb- and Eu-cation ordering in type-I clathrates: synthesis and homogeneity range of the novel compounds Rb(8-x)Eu(x)(In,Ge)46 (0.6 ≤ x ≤ 1.8).

    PubMed

    Schäfer, Marion C; Bobev, Svilen

    2013-12-15

    Studies in the Rb-Eu-In-Ge system confirm the existence of the phase Rb(8-x)Eu(x)(In,Ge)46 (0.6 ≤ x ≤ 1.8), crystallizing with the cubic clathrate type-I structure. The In and Ge content can be varied, concomitant with changes in the Rb-Eu ratio. Two of the three framework sites are occupied by statistical mixtures of Ge and In atoms, while the site with the lowest multiplicity is taken by the In atoms only. Based on the three refined formulae [heptarubidium europium nonaindium heptatriacontagermanide, Rb7.39(3)Eu0.61(3)In8.88(5)Ge37.12(5), and two forms of hexarubidium dieuropium decaindium hexatriacontagermanide, Rb6.30(3)Eu1.70(3)In9.76(4)Ge36.24(4) and Rb6.24(2)Eu1.76(2)In10.16(5)Ge35.84(5)] and the explored different synthetic routes, it can be suggested that the known ternary phase Rb8In8Ge38 and the hypothetical quaternary phase Rb6Eu2In10Ge36 represent the boundaries of the homogeneity range. In the former limiting composition, both the (Ge,In)20 and the (Ge,In)24 cages are fully occupied by Rb atoms only, whereas Rb6Eu2In10Ge36 has Rb atoms encapsulated in the larger tetrakaidecahedra, with Eu atoms filling the smaller pentagonal dodecahedra. For the solid solutions Rb(8-x)Eu(x)(In,Ge)46, Rb and Eu are statistically disordered in the dodecahedral cage, and the tetrakaidecahedral cage is only occupied by Rb atoms.

  8. High-temperature crystal structures and chemical modifications in RbH2PO4

    NASA Astrophysics Data System (ADS)

    Botez, Cristian E.; Martinez, Heber; Tackett, Ronald J.; Chianelli, Russell R.; Zhang, Jianzhong; Zhao, Yusheng

    2009-08-01

    We have used laboratory and synchrotron x-ray diffraction to investigate the structural and chemical changes undergone by polycrystalline RbH2PO4 upon heating within the 30-250 °C temperature interval. Our data show no evidence of the previously reported onset of partial polymerization at T = 96 °C (Park et al 2001 J. Phys.: Condens. Matter 13 9411) which was proposed as an explanation for the high-temperature proton conductivity enhancement in phosphate-based solid acids. Instead, we found that a tetragonal \\to monoclinic polymorphic transition initiates at T≈90 °C. The transition is complete at T≈130 °C, and the new monoclinic RbH2PO4 polymorph is stable upon further heating to T = 200 °C. Moreover, its crystal structure is isomorphic to that of monoclinic CsH2PO4. This remarkable similarity suggests that the microscopic structures and dynamics responsible for the high-temperature superprotonic behavior of RbH2PO4 could be the same as those of its Cs-based counterpart.

  9. High-temperature crystal structures and chemical modifications in RbH(2)PO(4).

    PubMed

    Botez, Cristian E; Martinez, Heber; Tackett, Ronald J; Chianelli, Russell R; Zhang, Jianzhong; Zhao, Yusheng

    2009-08-12

    We have used laboratory and synchrotron x-ray diffraction to investigate the structural and chemical changes undergone by polycrystalline RbH(2)PO(4) upon heating within the 30-250 °C temperature interval. Our data show no evidence of the previously reported onset of partial polymerization at T = 96 °C (Park et al 2001 J. Phys.: Condens. Matter 13 9411) which was proposed as an explanation for the high-temperature proton conductivity enhancement in phosphate-based solid acids. Instead, we found that a tetragonal [Formula: see text] monoclinic polymorphic transition initiates at T≈90 °C. The transition is complete at T≈130 °C, and the new monoclinic RbH(2)PO(4) polymorph is stable upon further heating to T = 200 °C. Moreover, its crystal structure is isomorphic to that of monoclinic CsH(2)PO(4). This remarkable similarity suggests that the microscopic structures and dynamics responsible for the high-temperature superprotonic behavior of RbH(2)PO(4) could be the same as those of its Cs-based counterpart.

  10. Antiferromagnetism in a bosonic mixture of rubidium ({sup 87}Rb) and potassium ({sup 41}K)

    SciTech Connect

    Shrestha, Uttam

    2010-10-15

    We simulate the experimental possibility of observing antiferromagnetic (AF) order in bosonic mixtures of rubidium ({sup 87}Rb) and potassium ({sup 41}K) in a two-dimensional optical lattice in the presence of harmonic confinement. By tuning the interspecies interactions and the lattice heights, we have found the ground states, within the mean-field approximation, that interpolate from phase separation to AF order. For a moderate lattice height, the coexistence of the Mott and AF phases is possible for the Rb atoms whereas the K atoms remain in the AF-superfluid phase. This observation may provide an experimentally feasible route to hitherto unobserved AF order for {sup 87}Rb-{sup 41}K mixtures.

  11. Diode laser 87Rb optical pumping in an evacuated wall-coated cell

    NASA Technical Reports Server (NTRS)

    Lee, W. K.; Robinson, H. G.; Johnson, C. E.

    1984-01-01

    The evacuated wall coated sealed cell coupled with diode laser optical pumping offers a number of attractive potential advantages for use in Rb or Cs atomic frequency standards. An investigation of systematic effects is required to explore possible limitations of the technique. The use of diode laser optical pumping of 87 Rb in an evacuated wall coated sealed cell is presented. Experimental results/discussion to be presented include the signal strength and line broadening of the 0 - 0 hyperfine resonance as a function of light intensity for the D1 optical transitions (F - F prime) - (2 1 prime) and (2 - 2 prime), shift of the 0 - 0 hyperfine frequency as a function of laser intensity and de-tuning from optical resonance, and diode laser frequency stabilization techniques.

  12. Dephosphorylation of threonine-821 of the retinoblastoma tumor suppressor protein (Rb) is required for apoptosis induced by UV and Cdk inhibition.

    PubMed

    Lentine, Brandon; Antonucci, Lisa; Hunce, Ray; Edwards, Justina; Marallano, Valerie; Krucher, Nancy A

    2012-09-01

    The Retinoblastoma protein (Rb) is important in the control of cell proliferation and apoptosis. Its activity is controlled by reversible phosphorylation on several serine and threonine residues. When Rb is hypophosphorylated, it inhibits proliferation by preventing passage through the G 1- S phase transition. Hyperphosphorylated Rb promotes cell cycle progression. The role of Rb phosphorylation in the control of apoptosis is largely unknown, although several apoptotic stimuli result in dephosphorylation of Rb. It may be that dephosphorylation of specific amino acids signals apoptosis vs. cell cycle arrest. Using glutamic acid mutagenesis, we have generated 15 single phosphorylation site mutants of Rb to alter serine/threonine to glutamic acid to mimic the phosphorylated state. By calcium phosphate transfection, mutant plasmids were introduced into C33A Rb-null cells, and apoptosis was induced using UV. Apoptosis was measured by ELISA detection of degraded DNA and by immunoblotting to assess proteolytic cleavage of PARP. Our results show that only mutation of threonine-821 to glutamic acid (T821E) blocked apoptosis by 50%, whereas other sites tested had little effect. In Rb-null Saos-2 and SKUT-1 cells, the T821E mutation also blocked apoptosis induced by the cdk inhibitor, Roscovitine, by 50%. In addition, we show that endogenous Rb is dephosphorylated on threonine-821 when cells are undergoing apoptosis. Thus, our data indicates that dephosphorylation of threonine-821 of Rb is required for cells to undergo apoptosis.

  13. RB: An essential player in adult neurogenesis.

    PubMed

    Fong, Bensun C; Slack, Ruth S

    2017-01-01

    The fundamental mechanisms underlying adult neurogenesis remain to be fully clarified. Members of the cell cycle machinery have demonstrated key roles in regulating adult neural stem cell (NSC) quiescence and the size of the adult-born neuronal population. The retinoblastoma protein, Rb, is known to possess CNS-specific requirements that are independent from its classical role as a tumor suppressor. The recent study by Vandenbosch et al. has clarified distinct requirements for Rb during adult neurogenesis, in the restriction of proliferation, as well as long-term adult-born neuronal survival. However, Rb is no longer believed to be the main cell cycle regulator maintaining the quiescence of adult NSCs. Future studies must consider Rb as part of a larger network of regulatory effectors, including the other members of the Rb family, p107 and p130. This will help elucidate the contribution of Rb and other pocket proteins in the context of adult neurogenesis, and define its crucial role in regulating the size and fate of the neurogenic niche.

  14. CsAlSi/sub 5/O/sub 12/: a possible host for /sup 137/Cs immobilization

    SciTech Connect

    Adl, T.; Vance, E.R.

    1982-03-31

    CsAlSi/sub 5/O/sub 12/ exhibits more acid resistance than pollucite (CsAlSi/sub 2/O/sub 6/). At pH values of 1.02 and 1.40, the extraction of Cs from CsAlSi/sub 5/O/sub 12/ at 25/sup 0/C was approximately proportional to the square root of leach time. The Cs extraction at 25/sup 0/C varied as (H/sup +/)/sup 0/ /sup 36/ over the pH range of 1 to 6. Also, the Cs extraction in various brines at 300/sup 0/C/30 MPa was comparable with that for pollucite. CsAlSi/sub 5/O/sub 12/ can be crystallized at about 1000/sup 0/C from calcines if a small amount of CaO is present, but in the absence of such sintering acids, crystallization temperatures of about 1400/sup 0/C are necessary. Compatibility data were also obtained with respect to several other phases with which CsAlSi/sub 5/O/sub 12/ might be expected to coexist in tailored ceramics designed for high-level defense waste.

  15. Mentoring and the 6Cs.

    PubMed

    Young, Lorna

    2016-02-10

    As a staff nurse in a rehabilitation unit, I have been involved in patient care initiatives using the 6Cs of nursing: care, compassion, competence, communication, courage and commitment. However, I had not appreciated the benefits of using the 6Cs of nursing in the mentorship role.

  16. LIMD1 antagonizes E2F1 activity and cell cycle progression by enhancing Rb function in cancer cells.

    PubMed

    Mayank, Adarsh K; Sharma, Shipra; Deshwal, Ravi K; Lal, Sunil K

    2014-07-01

    Tumour suppressor genes restrain inappropriate cell growth and division, as well as stimulate cell death to maintain tissue homeostasis. Loss of function leads to abnormal cellular behaviour, including hyperproliferation of cell and perturbation of cell cycle regulation. LIMD1 is a tumour suppressor gene located at chromosome 3p21.3, a region commonly deleted in many solid malignancies. LIMD1 interacts with retinoblastoma (Rb) and is involved in Rb-mediated downregulation of E2F1-target genes. However, the role of LIMD1 in cell cycle regulation remains unclear. We propose that LIMD1 induces cell cycle arrest, utilising Rb-E2F1 axis, and show that ectopic expression of LIMD1 in A549 cells results in hypo-phosphorylation that potentiates Rb function, which correlates with downregulation of E2F1. In agreement with these observations, LIMD1 overexpression retards cell cycle progression and blocks S-phase entry, as cells accumulate in G0/G1 phase and have reduced incorporation of BrdU. Most significantly, LIMD1-dependent effects on Rb function and cell cycle are reversed on depletion of endogenous LIMD1, underscoring its centrality in Rb-mediated cell cycle regulation. Hence, our findings provide new insight into cell cycle control by Rb-LIMD1 nexus.

  17. Trapping of Rb Atoms by ac Electric Fields

    SciTech Connect

    Schlunk, Sophie; Marian, Adela; Geng, Peter; Meijer, Gerard; Schoellkopf, Wieland; Mosk, Allard P.

    2007-06-01

    We demonstrate trapping of an ultracold gas of neutral atoms in a macroscopic ac electric trap. Three-dimensional confinement is obtained by switching between two saddle-point configurations of the electric field. Stable trapping is observed in a narrow range of switching frequencies around 60 Hz. The dynamic confinement of the atoms is directly visualized at different phases of the ac switching cycle. We observe about 10{sup 5} Rb atoms in the 1 mm{sup 3} large and several microkelvins deep trap with a lifetime of approximately 5 s.

  18. High-temperature, high-pressure hydrothermal synthesis, crystal structure, and solid-state NMR spectroscopy of Cs2(UO2)(Si2O6) and variable-temperature powder X-ray diffraction study of the hydrate phase Cs2(UO2)(Si2O6) x 0.5H2O.

    PubMed

    Chen, Chih-Shan; Chiang, Ray-Kuang; Kao, Hsien-Ming; Lii, Kwang-Hwa

    2005-05-30

    A new uranium(VI) silicate, Cs2(UO2)(Si2O6), has been synthesized by a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction and solid-state NMR spectroscopy. It crystallizes in the orthorhombic space group Ibca (No. 73) with a = 15.137(1) A, b = 15.295(1) A, c = 16.401(1) A, and Z = 16. Its structure consists of corrugated achter single chains of silicate tetrahedra extending along the c axis linked together via corner-sharing by UO6 tetragonal bipyramids to form a 3-D framework which delimits 8- and 6-ring channels. The Cs+ cations are located in the channels or at sites between channels. The 29Si and 133Cs MAS NMR spectra are consistent with the crystal structure as determined from X-ray diffraction, and the resonances in the spectra are assigned. Variable-temperature in situ powder X-ray diffraction study of the hydrate Cs2(UO2)(Si2O6) x 0.5H2O indicates that the framework structure is stable up to 800 degrees C and transforms to the structure of the title compound at 900 degrees C. A comparison of related uranyl silicate structures is made.

  19. αB-crystallin promotes oncogenic transformation and inhibits caspase activation in cells primed for apoptosis by Rb inactivation.

    PubMed

    Petrovic, Vladimir; Malin, Dmitry; Cryns, Vincent L

    2013-04-01

    The retinoblastoma (Rb) tumor suppressor gene is frequently inactivated in cancer, resulting in deregulated activation of E2F transcription factors, which promote S-phase entry, p53-dependent and p53-independent apoptosis. Transformed cells evade p53-dependent apoptosis initiated by Rb inactivation by TP53 mutation. However, the mechanisms by which cancer cells circumvent p53-independent apoptosis in this context are poorly understood. Because Rb inactivation primes cells for apoptosis by p53-independent induction of procaspases, we postulated that αB-crystallin, an inhibitor of procaspase-3 activation, would suppress caspase activation in cells with combined Rb and p53 inactivation. Notably, αB-crystallin is commonly expressed in ER/PR/HER2 "triple-negative" breast carcinomas characterized by frequent Rb loss and TP53 mutation. We report that αB-crystallin (-/-) knock out (KO) MEFs immortalized by dominant negative (DN) p53 are resistant to transformation by the adenovirus E1A oncoprotein, which inactivates Rb, while wild-type (WT) MEFs are readily transformed by DN p53 and E1A. αB-crystallin (-/-) KO MEFs stably expressing DN p53 and E1A were more sensitive to chemotherapy-induced caspase-3 activation and apoptosis than the corresponding WT MEFs, despite comparable induction of procaspases by E1A. Similarly, silencing Rb in WT and αB-crystallin (-/-) KO MEFs immortalized by DN p53 increased procaspase levels and sensitized αB-crystallin (-/-) KO MEFs to chemotherapy. Furthermore, silencing αB-crystallin in triple-negative breast cancer cells, which lack Rb and express mutant p53, enhanced chemotherapy sensitivity compared to non-silencing controls. Our results indicate that αB-crystallin inhibits caspase activation in cells primed for apoptosis by Rb inactivation and plays a novel oncogenic role in the context of combined Rb and p53 inactivation.

  20. Phosphorylated retinoblastoma protein (p-Rb) is involved in neuronal apoptosis after traumatic brain injury in adult rats.

    PubMed

    Liu, Wei; Liu, Xiaojuan; Yang, Huilin; Zhu, Xinhui; Yi, Hong; Zhu, Xuesong; Zhang, Jie

    2013-04-01

    Phosphorylated retinoblastoma protein (p-Rb), a well identified cell cycle related protein, is involved in regulating the biological functions of various cell types including neurons. One attractive biological function of p-Rb is releasing E2F transcription factor to induce S-phase entry and cellular proliferation of mitotic cells. However, some studies point out that the role of p-Rb in post-mitotic cells such as mature neurons is unique; it may induce cellular apoptosis rather than proliferation via regulating cell cycle reactivation. Up to now, the knowledge of p-Rb function in CNS is still limited. To investigate whether p-Rb is involved in CNS injury and repair, we performed a traumatic brain injury model in adult rats. Up-regulation of p-Rb was observed in the injured brain cortex by western blot analysis and immunohistochemistry staining. Terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling (TUNEL) and 4',6-diamidino-2-phenylindole (DAPI) staining suggested that p-Rb was relevant to neuronal apoptosis after brain injury. In addition, glutamate excitotoxic model of primary cortex neurons was introduced to further investigate the role of p-Rb in neuronal apoptosis; the result implied p-Rb was associated with cell cycle activation in the apoptotic neurons. Based on our data, we suggested that p-Rb might play an important role in neuronal apoptosis after traumatic brain injury in rat; which might also provide a basis for the further study on its role in regulating cell cycle re-entry in apoptotic neurons, and might gain a novel strategy for the clinical therapy for traumatic brain injury.

  1. FGF signaling targets the pRb-related p107 and p130 proteins to induce chondrocyte growth arrest

    PubMed Central

    Laplantine, Emmanuel; Rossi, Ferdinand; Sahni, Malika; Basilico, Claudio; Cobrinik, David

    2002-01-01

    Unregulated FGF signaling affects endochondral ossification and long bone growth, causing several genetic forms of human dwarfism. One major mechanism by which FGFs regulate endochondral bone growth is through their inhibitory effect on chondrocyte proliferation. Because mice with targeted mutations of the retinoblastoma (Rb)-related proteins p107 and p130 present severe endochondral bone defects with excessive chondrocyte proliferation, we have investigated the role of the Rb family of cell cycle regulators in the FGF response. Using a chondrocyte cell line, we found that FGF induced a rapid dephosphorylation of all three proteins of the Rb family (pRb, p107, and p130) and a blockade of the cells in the G1 phase of the cell cycle. This cell cycle block was reversed by inactivation of Rb proteins with viral oncoproteins such as polyoma large T (PyLT) antigen and Adenovirus E1A. Expression of a PyLT mutant that efficiently binds pRb, but not p107 and p130, allowed the cells to be growth inhibited by FGF, suggesting that pRb itself is not involved in the FGF response. To investigate more precisely the role of the individual Rb family proteins in FGF-mediated growth inhibition, we used chondrocyte micromass culture of limb bud cells isolated from mice lacking Rb proteins individually or in combination. Although wild-type as well as Rb−/− chondrocytes were similarly growth inhibited by FGF, chondrocytes null for p107 and p130 did not respond to FGF. Furthermore, FGF treatment of metatarsal bone rudiments obtained from p107−/−;p130−/− embryos failed to inhibit proliferation of growth plate chondrocytes, whereas rudiments from p107-null or p130-null embryos showed only a slight inhibition of growth. Our findings indicate that p107 and p130, but not pRb, are critical effectors of FGF-mediated growth inhibition in chondrocytes. PMID:12177046

  2. Local structure of solid Rb at megabar pressures

    SciTech Connect

    De Panfilis, S.; Gorelli, F.; Santoro, M.; Ulivi, L.; Gregoryanz, E.; Irifune, T.; Shinmei, T.; Kantor, I.; Mathon, O.; Pascarelli, S.

    2015-06-07

    We have investigated the local and electronic structure of solid rubidium by means of x-ray absorption spectroscopy up to 101.0 GPa, thus doubling the maximum investigated experimental pressure. This study confirms the predicted stability of phase VI and was completed by the combination of two pivotal instrumental solutions. On one side, we made use of nanocrystalline diamond anvils, which, contrary to the more commonly used single crystal diamond anvils, do not generate sharp Bragg peaks (glitches) at specific energies that spoil the weak fine structure oscillations in the x-ray absorption cross section. Second, we exploited the performance of a state-of-the-art x-ray focussing device yielding a beam spot size of 5 × 5 μm{sup 2}, spatially stable over the entire energy scan. An advanced data analysis protocol was implemented to extract the pressure dependence of the structural parameters in phase VI of solid Rb from 51.2 GPa up to the highest pressure. A continuous reduction of the nearest neighbour distances was observed, reaching about 6% over the probed pressure range. We also discuss a phenomenological model based on the Einstein approximation to describe the pressure behaviour of the mean-square relative displacement. Within this simplified scheme, we estimate the Grüneisen parameter for this high pressure Rb phase to be in the 1.3–1.5 interval.

  3. Crystal structure of Rb-elpasolite Rb{sub 2}NaAlF{sub 6}

    SciTech Connect

    Yakubovich, O. V. Kiryukhina, G. V.; Dimitrova, O. V.

    2013-05-15

    Single crystals of Rb{sub 2}NaAlF{sub 6}, the Rb analogue of the mineral elpasolite, are obtained in the NaF-Rb{sub 2}CO{sub 3}-Al{sub 2}O{sub 3}-Rb{sub 3}PO{sub 4}-H{sub 2}O system under hydrothermal conditions, and their structure is determined by X-ray diffraction (R = 0.0188): a = 8.3087(1) A, space group Fm3bar m, Z = 4, and {rho}{sub calcd} = 3.88 g/cm{sup 3}. The hypothesis that Rb elpasolite exists in nature in late associations of pegmatites enriched in rubidium is proposed.

  4. Materials Data on Cs2RbNF6 (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-11

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. Materials Data on Cs2RbPbF6 (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-11

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  6. Materials Data on Cs2RbGaF6 (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-11

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  7. Materials Data on CsRb2InF6 (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-11

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  8. Materials Data on Cs2RbInBr6 (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-04-20

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  9. Materials Data on Cs2RbTlF6 (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-11

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  10. Materials Data on CsRb2GaF6 (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-11

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  11. Materials Data on Cs2RbInF6 (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-11

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  12. Materials Data on Cs11Rb7O3 (SG:19) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-04-22

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  13. Materials Data on Cs3Rb (SG:194) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-08-20

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. Bichromatic state-insensitive trapping of cold 133Cs-87Rb atomic mixtures

    NASA Astrophysics Data System (ADS)

    Metbulut, M. M.; Renzoni, F.

    2015-12-01

    We investigate simultaneous state-insensitive trapping of a mixture of two different atomic species, Caesium and Rubidium. The magic wavelengths of the Caesium and Rubidium atoms are different, 935.6 and 789.9 nm respectively, thus single-frequency simultaneous state-insensitive trapping is not possible. We thus identify bichromatic trapping as a viable approach to tune the two magic wavelengths to a common value. Correspondingly, we present several common magic wavelength combinations appropriate for simultaneous state-insensitive trapping of the two atomic species.

  15. Materials Data on CsRbN (SG:216) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-09-21

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  16. Materials Data on CsRbP (SG:216) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-09-21

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Materials Data on CsRbAs (SG:216) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-09-21

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  18. Bandhead Energies in 125Cs

    NASA Astrophysics Data System (ADS)

    Sun, Ji; Hu, Xue-Yuan; Ma, Ying-Jun; Liu, Yun-Zuo; Tetsuro, Komatsubara; Kohei, Furuno; Zhang, Yu-Hu; Zhou, Wen-Ping; Wang, Shou-Yu

    Excited states in 125Cs have been studied with the fusion-evaporation-reaction 116Cd(14N,5n)125Cs at 65 MeV beam energy, using the Nordball-multidetector-system at the Niels-Bohr-Institute in Denmark. The level scheme of 125Cs was extended with the addition of more than 40 new γ-transitions. Moreover, the bandhead excitation energies of the previously known g9/2 and h11/2 bands were unambiguously corrected with plenty of hard evidence.

  19. Transformation of Sintered CsPbBr3 Nanocrystals to Cubic CsPbI3 and Gradient CsPbBrxI3-x through Halide Exchange.

    PubMed

    Hoffman, Jacob B; Schleper, A Lennart; Kamat, Prashant V

    2016-07-13

    All-inorganic cesium lead halide (CsPbX3, X = Br(-), I(-)) perovskites could potentially provide comparable photovoltaic performance with enhanced stability compared to organic-inorganic lead halide species. However, small-bandgap cubic CsPbI3 has been difficult to study due to challenges forming CsPbI3 in the cubic phase. Here, a low-temperature procedure to form cubic CsPbI3 has been developed through a halide exchange reaction using films of sintered CsPbBr3 nanocrystals. The reaction was found to be strongly dependent upon temperature, featuring an Arrhenius relationship. Additionally, film thickness played a significant role in determining internal film structure at intermediate reaction times. Thin films (50 nm) showed only a small distribution of CsPbBrxI3-x species, while thicker films (350 nm) exhibited much broader distributions. Furthermore, internal film structure was ordered, featuring a compositional gradient within film. Transient absorption spectroscopy showed the influence of halide exchange on the excited state of the material. In thicker films, charge carriers were rapidly transferred to iodide-rich regions near the film surface within the first several picoseconds after excitation. This ultrafast vectorial charge-transfer process illustrates the potential of utilizing compositional gradients to direct charge flow in perovskite-based photovoltaics.

  20. Rotational bands in {sup 76}Rb

    SciTech Connect

    Harder, A.; Kabadiyski, M.K.; Lieb, K.P.; Rudolph, D.; Gross, C.J.; Cunningham, R.A.; Hannachi, F.; Simpson, J.; Warner, D.D.; Roth, H.A.; Skeppstedt, O.; Gelletly, W.; Varley, B.J.

    1995-06-01

    High spin states in {sup 76}Rb were investigated via the reaction {sup 40}Ca({sup 40}Ca,3{ital pn}){sup 76}Rb at 128 MeV. The level scheme was established from {gamma}{gamma}, {gamma}{gamma}{gamma} and recoil-{gamma} coincidences measured in the EUROGAM I array in combination with the Daresbury recoil separator. The known rotational bands were extended up to the excitation energy {ital E}{sub {ital x}}{approx}9.2 MeV and spins {ital I}{sup {pi}}=(21{sup +}) and (19{sup {minus}}). The band head energies could be fixed by many interband transitions. Two new bands were identified. The level scheme is discussed in terms of the cranked shell model. In the negative parity bands {sup 76}Rb behaves like a rigid rotor until the first band crossings.

  1. Atomic and electronic structures of rubidium adsorption on Si(001)(2 x 1) surface: Comparison with Cs/Si(001) surface

    SciTech Connect

    Xiao, H Y.; Zu, Xiaotao; Zhang, Yanfeng; Gao, Fei

    2006-04-21

    First-principles calculations based on DFT-GGA method have been performed on rubidium adsorption on Si(001)(2?1) surface. The atomic and electronic structures of Si(001)(2?1)-Rb have been calculated and compared with those of Cs adsorption (J.Chem. Phys.122 (2005) 174704). It turns out that the saturation coverage of Rb is one monolayer rather than half a monolayer, similar to that of Cs adsorption. Comparison of Rb on Si(001)(2?1) with Cs adsorption showed that at saturation coverage larger alkali metal (AM) atom leads to stronger AM-AM interaction and weaker AM-Si interaction. However, for low coverage of 0.25 and 0.5 ML the Rb-Si interaction is surprisingly weaker than Cs-Si interaction. Further detailed analysis suggested that this is a consequence of depolarization effect with decreasing AM size below 1 ML coverage. For the saturation coverage the dispersion curves show that the surface is of semi-conducting character. This result does not support the direct and inverse angle-resolved photoemission investigation where a metallization is observed at saturation coverage.

  2. Inoculation of Pichia kudriavzevii RB1 degrades the organic acids present in raw compost material and accelerates composting.

    PubMed

    Nakasaki, Kiyohiko; Araya, Shogo; Mimoto, Hiroshi

    2013-09-01

    In this study, the yeast strain Pichia kudriavzevii RB1 was used as an inoculum to accelerate organic matter degradation of rabbit food with added organic acids, which was used as a model food waste for composting. The RB1 strain rapidly degraded the organic acids present in the raw compost material, leading to an increase in pH beyond the neutral level, within 2 days. Both mesophilic and thermophilic bacteria proliferated faster in the compost with RB1 inoculation than in that without inoculation. Although the yeast died with the increase in compost temperature, it affected the early stages of composting prior to the thermophilic stage and accelerated the composting process by 2 days by eliminating the initial lag phase seen in the growth of other microorganisms. Moreover, populations of Bacillus thermoamylovorans, Bacillus foraminis, and Bacillus coagulans became dominant during the thermophilic stages of both composting with and without RB1 inoculation.

  3. Ras Regulates Rb via NORE1A.

    PubMed

    Barnoud, Thibaut; Donninger, Howard; Clark, Geoffrey J

    2016-02-05

    Mutations in the Ras oncogene are one of the most frequent events in human cancer. Although Ras regulates numerous growth-promoting pathways to drive transformation, it can paradoxically promote an irreversible cell cycle arrest known as oncogene-induced senescence. Although senescence has clearly been implicated as a major defense mechanism against tumorigenesis, the mechanisms by which Ras can promote such a senescent phenotype remain poorly defined. We have shown recently that the Ras death effector NORE1A plays a critical role in promoting Ras-induced senescence and connects Ras to the regulation of the p53 tumor suppressor. We now show that NORE1A also connects Ras to the regulation of a second major prosenescent tumor suppressor, the retinoblastoma (Rb) protein. We show that Ras induces the formation of a complex between NORE1A and the phosphatase PP1A, promoting the activation of the Rb tumor suppressor by dephosphorylation. Furthermore, suppression of Rb reduces NORE1A senescence activity. These results, together with our previous findings, suggest that NORE1A acts as a critical tumor suppressor node, linking Ras to both the p53 and the Rb pathways to drive senescence.

  4. Magnetic merging of ultracold atomic gases of {sup 85}Rb and {sup 87}Rb

    SciTech Connect

    Haendel, S.; Wiles, T. P.; Marchant, A. L.; Hopkins, S. A.; Adams, C. S.; Cornish, S. L.

    2011-05-15

    We report the magnetic merging of ultracold atomic gases of {sup 85}Rb and {sup 87}Rb by the controlled overlap of two initially spatially separated magnetic traps. We present a detailed analysis of the combined magnetic-field potential as the two traps are brought together that predicts a clear optimum trajectory for the merging. We verify this prediction experimentally using {sup 85}Rb and find that the final atom number in the merged trap is maximized with minimal heating by following the predicted optimum trajectory. Using the magnetic-merging approach allows us to create variable-ratio isotopic Rb mixtures with a single laser-cooling setup by simply storing one isotope in a magnetic trap before jumping the laser frequencies to the transitions necessary to laser cool the second isotope.

  5. RB1: a prototype tumor suppressor and an enigma

    PubMed Central

    Dyson, Nicholas J.

    2016-01-01

    The retinoblastoma susceptibility gene (RB1) was the first tumor suppressor gene to be molecularly defined. RB1 mutations occur in almost all familial and sporadic forms of retinoblastoma, and this gene is mutated at variable frequencies in a variety of other human cancers. Because of its early discovery, the recessive nature of RB1 mutations, and its frequency of inactivation, RB1 is often described as a prototype for the class of tumor suppressor genes. Its gene product (pRB) regulates transcription and is a negative regulator of cell proliferation. Although these general features are well established, a precise description of pRB's mechanism of action has remained elusive. Indeed, in many regards, pRB remains an enigma. This review summarizes some recent developments in pRB research and focuses on progress toward answers for the three fundamental questions that sit at the heart of the pRB literature: What does pRB do? How does the inactivation of RB change the cell? How can our knowledge of RB function be exploited to provide better treatment for cancer patients? PMID:27401552

  6. RB1: a prototype tumor suppressor and an enigma.

    PubMed

    Dyson, Nicholas J

    2016-07-01

    The retinoblastoma susceptibility gene (RB1) was the first tumor suppressor gene to be molecularly defined. RB1 mutations occur in almost all familial and sporadic forms of retinoblastoma, and this gene is mutated at variable frequencies in a variety of other human cancers. Because of its early discovery, the recessive nature of RB1 mutations, and its frequency of inactivation, RB1 is often described as a prototype for the class of tumor suppressor genes. Its gene product (pRB) regulates transcription and is a negative regulator of cell proliferation. Although these general features are well established, a precise description of pRB's mechanism of action has remained elusive. Indeed, in many regards, pRB remains an enigma. This review summarizes some recent developments in pRB research and focuses on progress toward answers for the three fundamental questions that sit at the heart of the pRB literature: What does pRB do? How does the inactivation of RB change the cell? How can our knowledge of RB function be exploited to provide better treatment for cancer patients?

  7. Dielectric breakdown during Cs+ sputtering of polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Wahoud, F.; Guillot, J.; Audinot, J. N.; Bertrand, P.; Delcorte, A.; Migeon, H. N.

    2014-02-01

    Thin films of insulating polymers are sometimes analyzed by secondary ion mass spectrometry (SIMS) or by X-ray photoelectron spectroscopy (XPS) without the use of an electron gun. In this work, both SIMS and XPS have been used to study the chemical and structural modifications due to the charge effect during Cs+ sputtering of a thin film of polyvinyl chloride (PVC). The kinetic energy distribution study shows that at a small primary fluence ˜1015 Cs+ ions/cm2, the dielectric breakdown voltage of the PVC film is reached, i.e. the minimum voltage that causes a portion of an insulator to become electrically conductive. XPS study indicates that the conducting phase created in the PVC film after energetic Cs+ bombardment consists of graphitized carbon and metallic cesium clusters. After the dielectric breakdown of the film, the positive charge, previously accumulated on the surface, is neutralized through the conductive regions, which are created in the insulating film. During Cs+ sputtering of a PVC film, the chemical structure of the analyzed surface is completely modified and some ionic bonds such as CsC and CsCl are also created.

  8. CS1 is a novel topoisomerase IIα inhibitor with favorable drug resistance profiles

    SciTech Connect

    Shen, Yan; Chen, Wang; Zhao, Baobing; Hao, Huilin; Li, Zhenyu; Lu, Chunhua; Shen, Yuemao

    2014-10-24

    Highlights: • CS1 is a novel nonintercalating topoisomerase IIα poison. • CS1 shows potent in vitro and in vivo antitumor activity. • CS1 shows 6–10-fold less toxicity to normal cells compared with etoposide. • CS1 is not a substrate of P-glycoprotein and multidrug resistance irrelevant. - Abstract: DNA topoisomerase II (Topo II) is an essential nuclear enzyme and a validated target for anticancer agent screening. CS1, a novel 2-phenylnaphthalene, had potent cytotoxicity against nine tested tumor cell lines and showed 6–10-fold less toxicity against normal cell lines compared with etoposide. In addition, CS1 showed potential anti-multidrug resistance capabilities. kDNA decatenation, DNA relaxation and cleavage complex assays indicated that CS1 acted as a nonintercalating topoisomerase IIα (Topo IIα) inhibitor by stabilizing the DNA-Topo IIα cleavage complex. CS1 also induced DNA breaks in MDA-MB-231 cells evidenced by comet tails and the accumulation of γH2AX foci. The ability of CS1 in inducing DNA breaks mediated by Topo II resulted in G2/M phase arrest and apoptosis. Moreover, CS1 exhibited dramatic in vivo antitumor activity and lower toxicity compared with etoposide. This work supports the development of CS1 as a promising candidate for the treatment of cancer by targeting Topo IIα.

  9. Ultracold thermalization of {sup 7}Li and {sup 87}Rb

    SciTech Connect

    Marzok, C.; Deh, B.; Courteille, Ph. W.; Zimmermann, C.

    2007-11-15

    We report on measurements of cross-species thermalization inside a magnetically trapped spin-polarized mixture of {sup 87}Rb and {sup 7}Li atoms with both atoms in their respective low-field-seeking magnetic substates |F=2,m{sub F}=2>. Measurement of the thermalization velocity in the ultracold regime below 10 {mu}K allows for the derivation of the absolute value of the pure triplet s-wave scattering length governing the interaction. We find |a{sub 7,87}|=(59{+-}19)a{sub B}. We propose to study both species in the condensed regime to derive the sign of a{sub 7,87}. In this context, we present numerical solutions to the coupled Gross-Pitaevskii equation based on the hypothesis of a positive sign. According to the simulations, phase separation of the Li and Rb |2,2> clouds occurs along with a mean-field stabilization allowing for larger atom numbers of condensed {sup 7}Li atoms before collapse sets in. Observation of this mean-field stabilization would directly fix the sign of a{sub 7,87}. We discuss our results in the light of this proposal.

  10. Two dimensional fluoride ion conductor RbSn {2}F {5} studied by impedance spectroscopy and {19}F, {119}Sn, and {87}Rb NMR

    NASA Astrophysics Data System (ADS)

    Yamada, K.; Ahmad, M. M.; Ogiso, Y.; Okuda, T.; Chikami, J.; Miehe, G.; Ehrenberg, H.; Fuess, H.

    2004-07-01

    RbSn2F5 is a two-dimensional fluoride ion conductor. It undergoes a first-order phase transition to a superionic state at 368 K. The structure of the low temperature phase has been determined from the Rietveld analysis of the X-ray powder diffraction. The dynamic properties of the fluoride ions in RbSn2F5 have been studied by impedance spectroscopy and solid state NMR. The dc ionic conductivity of this sample shows an abrupt increase at the phase transition temperature. We have obtained the hopping frequency and the concentration of the charge carriers (F- ions) at different temperatures from the analysis of the conductivity spectra using Almond-West formalism. The estimated values of the charge carriers’ concentration agree well with that determined from the structure and were found to be independent of temperature. The relatively small value of the power-law exponent, n ≈ 0.55, supports the two-dimensional property of the investigated material. Furthermore, 19F NMR with simulation has suggested the diffusive motions of the fluoride ions between different sites. In contrast, 119Sn and 87Rb NMR spectra below 250 K supported the intrinsic disordered nature due to the random distribution of the fluoride ion vacancies.

  11. Static electric field effects in photodetachment of Cs^-

    NASA Astrophysics Data System (ADS)

    Khuskivadze, Amiran; Fabrikant, Ilya; Thumm, Uwe

    2003-05-01

    We calculate near-threshold photodetachment cross sections for Cs^- in the presence of a dc electric field using three different approaches: the frame transformation method (i) including and (ii) not including the rescattering effect and (iii) the Kirchhoff integral approach^1. Radial wavefunctions for electron motion were obtained by using the Pauli-equation method with a model potential describing the effective electron-atom interaction^2. Our calculations show the inadequacy of the frame transformation method in the ^3P resonance region even for weak fields (<10 kV/cm). We show that the triplet and singlet contributions to the total cross section can be manipulated by variation of the electric field. This allows the controlled enhancement of the spin-orbit effects in the photodetachment process and creation of more favorable conditions for observations of the ^3P resonance in Cs^- and other negative ions, such as, e.g. Rb^- ^3. ^1I.I. Fabrikant, J. Phys. B 26, 2533 (1993). ^2C. Bahrim, U. Thumm, A. A. Khuskivadze, and I. I. Fabrikant, Phys. Rev. A 66, 052712 (2002). ^3C. Bahrim, U. Thumm, and I. I. Fabrikant, Phys. Rev. A 63, 042710 (2001).

  12. CHeCS Commanding Hardware

    NASA Technical Reports Server (NTRS)

    Moore, Jamie

    2010-01-01

    This slide presentation reviews the Crew Health Care System (CHeCS) commanding hardware. It includes information on the hardware status, commanding plan, and command training status with specific information the EV-CPDS 2 and 3, TEPC, MEC, and T2

  13. RB localizes to DNA double-strand breaks and promotes DNA end resection and homologous recombination through the recruitment of BRG1.

    PubMed

    Vélez-Cruz, Renier; Manickavinayaham, Swarnalatha; Biswas, Anup K; Clary, Regina Weaks; Premkumar, Tolkappiyan; Cole, Francesca; Johnson, David G

    2016-11-15

    The retinoblastoma (RB) tumor suppressor is recognized as a master regulator that controls entry into the S phase of the cell cycle. Its loss leads to uncontrolled cell proliferation and is a hallmark of cancer. RB works by binding to members of the E2F family of transcription factors and recruiting chromatin modifiers to the promoters of E2F target genes. Here we show that RB also localizes to DNA double-strand breaks (DSBs) dependent on E2F1 and ATM kinase activity and promotes DSB repair through homologous recombination (HR), and its loss results in genome instability. RB is necessary for the recruitment of the BRG1 ATPase to DSBs, which stimulates DNA end resection and HR. A knock-in mutation of the ATM phosphorylation site on E2F1 (S29A) prevents the interaction between E2F1 and TopBP1 and recruitment of RB, E2F1, and BRG1 to DSBs. This knock-in mutation also impairs DNA repair, increases genomic instability, and renders mice hypersensitive to IR. Importantly, depletion of RB in osteosarcoma and breast cancer cell lines results in sensitivity to DNA-damaging drugs, which is further exacerbated by poly-ADP ribose polymerase (PARP) inhibitors. We uncovered a novel, nontranscriptional function for RB in HR, which could contribute to genome instability associated with RB loss.

  14. The Origin of the RB1 Imprint

    PubMed Central

    Kanber, Deniz; Buiting, Karin; Roos, Christian; Gromoll, Jörg; Kaya, Sabine; Horsthemke, Bernhard; Lohmann, Dietmar

    2013-01-01

    The human RB1 gene is imprinted due to a differentially methylated CpG island in intron 2. This CpG island is part of PPP1R26P1, a truncated retrocopy of PPP1R26, and serves as a promoter for an alternative RB1 transcript. We show here by in silico analyses that the parental PPP1R26 gene is present in the analysed members of Haplorrhini, which comprise Catarrhini (Old World Monkeys, Small apes, Great Apes and Human), Platyrrhini (New World Monkeys) and tarsier, and Strepsirrhini (galago). Interestingly, we detected the retrocopy, PPP1R26P1, in all Anthropoidea (Catarrhini and Platyrrhini) that we studied but not in tarsier or galago. Additional retrocopies are present in human and chimpanzee on chromosome 22, but their distinct composition indicates that they are the result of independent retrotransposition events. Chimpanzee and marmoset have further retrocopies on chromosome 8 and chromosome 4, respectively. To examine the origin of the RB1 imprint, we compared the methylation patterns of the parental PPP1R26 gene and its retrocopies in different primates (human, chimpanzee, orangutan, rhesus macaque, marmoset and galago). Methylation analysis by deep bisulfite sequencing showed that PPP1R26 is methylated whereas the retrocopy in RB1 intron 2 is differentially methylated in all primates studied. All other retrocopies are fully methylated, except for the additional retrocopy on marmoset chromosome 4, which is also differentially methylated. Using an informative SNP for the methylation analysis in marmoset, we could show that the differential methylation pattern of the retrocopy on chromosome 4 is allele-specific. We conclude that the epigenetic fate of a PPP1R26 retrocopy after integration depends on the DNA sequence and selective forces at the integration site. PMID:24282601

  15. Selective disruption of rb-raf-1 kinase interaction inhibits pancreatic adenocarcinoma growth irrespective of gemcitabine sensitivity.

    PubMed

    Treviño, José G; Verma, Monika; Singh, Sandeep; Pillai, Smitha; Zhang, Dongyu; Pernazza, Daniele; Sebti, Said M; Lawrence, Nicholas J; Centeno, Barbara A; Chellappan, Srikumar P

    2013-12-01

    Inactivation of the retinoblastoma (Rb) tumor suppressor protein is widespread in human cancers. Inactivation of Rb is thought to be initiated by association with Raf-1 (C-Raf) kinase, and here we determined how RRD-251, a disruptor of the Rb-Raf-1 interaction, affects pancreatic tumor progression. Assessment of phospho-Rb levels in resected human pancreatic tumor specimens by immunohistochemistry (n = 95) showed that increased Rb phosphorylation correlated with increasing grade of resected human pancreatic adenocarcinomas (P = 0.0272), which correlated with reduced overall patient survival (P = 0.0186). To define the antitumor effects of RRD-251 (50 μmol/L), cell-cycle analyses, senescence, cell viability, cell migration, anchorage-independent growth, angiogenic tubule formation and invasion assays were conducted on gemcitabine-sensitive and -resistant pancreatic cancer cells. RRD-251 prevented S-phase entry, induced senescence and apoptosis, and inhibited anchorage-independent growth and invasion (P < 0.01). Drug efficacy on subcutaneous and orthotopic xenograft models was tested by intraperitoneal injections of RRD-251 (50 mg/kg) alone or in combination with gemcitabine (250 mg/kg). RRD-251 significantly reduced tumor growth in vivo accompanied by reduced Rb phosphorylation and lymph node and liver metastasis (P < 0.01). Combination of RRD-251 with gemcitabine showed cooperative effect on tumor growth (P < 0.01). In conclusion, disruption of the Rb-Raf-1 interaction significantly reduces the malignant properties of pancreatic cancer cells irrespective of their gemcitabine sensitivity. Selective targeting of Rb-Raf-1 interaction might be a promising strategy targeting pancreatic cancer.

  16. Host range and cell cycle activation properties of polyomavirus large T-antigen mutants defective in pRB binding

    SciTech Connect

    Freund, R.; Bauer, P.H.; Benjamin, T.L.; Crissman, H.A.; Bradbury, E.M. |

    1994-11-01

    The authors have examined the growth properties of polyomavirus large T-antigen mutants that ar unable to bind pRB, the product of the retinoblastoma tumor suppressor gene. These mutants grow poorly on primary mouse cells yet grow well on NIH 3T3 and other established mouse cell lines. Preinfection of primary baby mouse kidney (BMK) epithelial cells with wild-type simian virus 40 renders these cells permissive to growth of pRB-binding polyomavirus mutants. Conversely, NIH 3T3 cells transfected by and expressing wild-type human pRB become nonpermissive. Primary fibroblasts for mouse embryos that carry a homozygous knockout of the RB gene are permissive, while those from normal littermates are nonpermissive. The host range of polyomavirus pRB-binding mutants is thus determined by expression or lack of expression of functional pRB by the host. These results demonstrate the importance of pRB binding by large T antigen for productive viral infection in primary cells. Failure of pRB-binding mutants to grow well in BMK cells correlates with their failure to induce progression from G{sub 0} or G{sub 1} through the S phase of the cell cycle. Time course studies show delayed synthesis and lower levels of accumulation of large T antigen, viral DNA, and VP1 in mutant compared with wild-type virus-infected BMK cells. These results support a model in which productive infection by polyomavirus in normal mouse cells is tightly coupled to the induction and progression of the cell cycle. 48 refs., 6 figs., 5 tabs.

  17. In-situ Rb-Sr geochronology

    NASA Astrophysics Data System (ADS)

    Anderson, F. S.; Nowicki, K.; Whitaker, T.

    This paper reports on the first rubidium-strontium (Rb-Sr) radiometric dates using a Laser Desorption Resonance Ionization Mass Spectrometry (LDRIMS) instrument capable of being miniaturized for flight to another planet. The LDRIMS instrument produces dates in under 24 hours, requires minimal sample preparation, and avoids the interference and mass resolution issues associated with other geochronology measurements. We have begun testing the bench-top prototype on the Boulder Creek Granite (BCG), from Colorado, comprised primarily of a gneissic quartz monzonite and granodiorite; whole rock Rb-Sr TIMS measurements result in dates of 1700± 40 Ma [1]. Data reduction of the LDRIMS Rb-Sr measurements on calibrated repeat runs result in a date for the BCG of 1.727± 0.087 Ga (n=288, MSWD=1). Most geochronology applications are willing to accept an MSWD up to ~2.7; at MSWD=2, the precision improves to ± 0.062 Ga. This technology is moving from lab prototype to field deployable instrument, and provides an opportunity to directly address the science goals of Mars Sample Return (MSR) within the bounds posed by current scientific, fiscal, and political pressures on the Mars program. Additionally, LDRIMS could potentially be flown to the Moon under the Discovery or New Frontiers program. We posit that in-situ geochronology missions to Mars to triage and validate samples for Mars Sample Return (MSR) are technically feasible in the 2018-2022 time frame.

  18. Mass spectrometry studies of fission product behavior: 2, Gas phase species

    SciTech Connect

    Blackburn, P.E.; Johnson, C.E.

    1987-01-01

    Revaporization of fission products from reactor system surfaces has become a complicating factor in source term definition. Critical to this phenomena is understanding the nature and behavior of the vapor phase species. This study characterizes the stability of the CsI . CsOH vapor phase complex. Vapor pressures were measured with a mass spectrometer. Thermodynamic data were obtained for CsOH(g), Cs/sub 2/(OH)/sub 2/(g), CsI(g), Cs/sub 2/I/sub 2/(g) and CsI . CsOH(g). Activity coefficients were derived for the CsI-CsOH system. The relative ionization cross section of CsOH is about ten times the cross section of CsI(g). CsI . CsOH fragments to Cs/sub 2/OH/sup +/ and an iodine atom. 17 refs., 4 figs., 6 tabs.

  19. Rb suppresses human cone-precursor-derived retinoblastoma tumours.

    PubMed

    Xu, Xiaoliang L; Singh, Hardeep P; Wang, Lu; Qi, Dong-Lai; Poulos, Bradford K; Abramson, David H; Jhanwar, Suresh C; Cobrinik, David

    2014-10-16

    Retinoblastoma is a childhood retinal tumour that initiates in response to biallelic RB1 inactivation and loss of functional retinoblastoma (Rb) protein. Although Rb has diverse tumour-suppressor functions and is inactivated in many cancers, germline RB1 mutations predispose to retinoblastoma far more strongly than to other malignancies. This tropism suggests that retinal cell-type-specific circuitry sensitizes to Rb loss, yet the nature of the circuitry and the cell type in which it operates have been unclear. Here we show that post-mitotic human cone precursors are uniquely sensitive to Rb depletion. Rb knockdown induced cone precursor proliferation in prospectively isolated populations and in intact retina. Proliferation followed the induction of E2F-regulated genes, and depended on factors having strong expression in maturing cone precursors and crucial roles in retinoblastoma cell proliferation, including MYCN and MDM2. Proliferation of Rb-depleted cones and retinoblastoma cells also depended on the Rb-related protein p107, SKP2, and a p27 downregulation associated with cone precursor maturation. Moreover, Rb-depleted cone precursors formed tumours in orthotopic xenografts with histological features and protein expression typical of human retinoblastoma. These findings provide a compelling molecular rationale for a cone precursor origin of retinoblastoma. More generally, they demonstrate that cell-type-specific circuitry can collaborate with an initiating oncogenic mutation to enable tumorigenesis.

  20. Infrared multiple photon dissociation spectroscopy of cationized histidine: effects of metal cation size on gas-phase conformation.

    PubMed

    Citir, Murat; Hinton, Christopher S; Oomens, Jos; Steill, Jeffrey D; Armentrout, P B

    2012-02-16

    The gas phase structures of cationized histidine (His), including complexes with Li(+), Na(+), K(+), Rb(+), and Cs(+), are examined by infrared multiple photon dissociation (IRMPD) action spectroscopy utilizing light generated by a free electron laser, in conjunction with quantum chemical calculations. To identify the structures present in the experimental studies, measured IRMPD spectra are compared to spectra calculated at B3LYP/6-311+G(d,p) (Li(+), Na(+), and K(+) complexes) and B3LYP/HW*/6-311+G(d,p) (Rb(+) and Cs(+) complexes) levels of theory, where HW* indicates that the Hay-Wadt effective core potential with additional polarization functions was used on the metals. Single point energy calculations were carried out at the B3LYP, B3P86, and MP2(full) levels using the 6-311+G(2d,2p) basis set. On the basis of these experiments and calculations, the only conformation that reproduces the IRMPD action spectra for the complexes of the smaller alkali metal cations, Li(+)(His) and Na(+)(His), is a charge-solvated, tridentate structure where the metal cation binds to the backbone carbonyl oxygen, backbone amino nitrogen, and nitrogen atom of the imidazole side chain, [CO,N(α),N(1)], in agreement with the predicted ground states of these complexes. Spectra of the larger alkali metal cation complexes, K(+)(His), Rb(+)(His), and Cs(+)(His), have very similar spectral features that are considerably more complex than the IRMPD spectra of Li(+)(His) and Na(+)(His). For these complexes, the bidentate [CO,N(1)] conformer in which the metal cation binds to the backbone carbonyl oxygen and nitrogen atom of the imidazole side chain is a dominant contributor, although features associated with the tridentate [CO,N(α),N(1)] conformer remain, and those for the [COOH] conformer are also clearly present. Theoretical results for Rb(+)(His) and Cs(+)(His) indicate that both [CO,N(1)] and [COOH] conformers are low-energy structures, with different levels of theory predicting different

  1. Rb selectively inhibits innate IFN-β production by enhancing deacetylation of IFN-β promoter through HDAC1 and HDAC8.

    PubMed

    Meng, Jun; Liu, Xingguang; Zhang, Peng; Li, Dong; Xu, Sheng; Zhou, Qingqing; Guo, Meng; Huai, Wanwan; Chen, Xiang; Wang, Quanxing; Li, Nan; Cao, Xuetao

    2016-09-01

    Type I IFN production is tightly controlled by host to generate efficient viral clearance without harmful immunopathology or induction of autoimmune disorders. Epigenetic regulation of type I IFN production in innate immunity and inflammatory disorders remains to be fully understood. Several tumor suppressors have been shown to regulate immune response and inflammation. However, the non-classical functions of tumor suppressors in innate immunity and inflammatory diseases need further identification. Here we report retinoblastoma protein (Rb) deficiency selectively enhanced TLR- and virus-triggered production of IFN-β which thus induced more IFN-α generation in the later phase of innate stimuli, but had no effect on the production of TNF, IL-6 and early phase IFN-α in macrophages. Rb1(fl/fl)Lyz2cre(+) Rb-deficient mice exhibited more resistant to lethal virus infection and more effective clearance of influenza virus. Rb selectively bound Ifnb1 enhancer region, but not the promoter of Ifna4, Tnf and Il6, by interacting with c-Jun, the component of IFN-β enhanceosome. Then Rb recruited HDAC1 and HDAC8 to attenuate acetylation of Histone H3/H4 in Ifnb1 promoter, resulting in suppression of Ifnb1 transcription. Therefore, Rb selectively inhibits innate IFN-β production by enhancing deacetylation of Ifnb1 promoter, exhibiting a previous unknown non-classical role in innate immunity, which also suggests a role of Rb in the regulation of type I IFN production in inflammatory or autoimmune diseases.

  2. ITER CS Intermodule Support Structure

    SciTech Connect

    Myatt, R.; Freudenberg, Kevin D

    2011-01-01

    With five independently driven, bi-polarity power supplies, the modules of the ITER central solenoid (CS) can be energized in aligned or opposing field directions. This sets up the possibility for repelling modules, which indeed occurs, particularly between CS2L and CS3L around the End of Burn (EOB) time point. Light interface compression between these two modules at EOB and wide variations in these coil currents throughout the pulse produce a tendency for relative motion or slip. Ideally, the slip is purely radial as the modules breathe without any accumulative translational motion. In reality, however, asymmetries such as nonuniformity in intermodule friction, lateral loads from a plasma Vertical Disruption Event (VDE), magnetic forces from manufacturing and assembly tolerances, and earthquakes can all contribute to a combination of radial and lateral module motion. This paper presents 2D and 3D, nonlinear, ANSYS models which simulate these various asymmetries and determine the lateral forces which must be carried by the intermodule structure. Summing all of these asymmetric force contributions leads to a design-basis lateral load which is used in the design of various support concepts: the CS-CDR centering rings and a variation, the 2001 FDR baseline radial keys, and interlocking castles structures. Radial key-type intermodule structure interface slip and stresses are tracked through multiple 15 MA scenario current pulses to demonstrate stable motion following the first few cycles. Detractions and benefits of each candidate intermodule structure are discussed, leading to the simplest and most robust configuration which meets the design requirements: match-drilled radial holes and pin-shaped keys.

  3. Conditional Mutation of Rb Causes Cell Cycle Defects without Apoptosis in the Central Nervous System

    PubMed Central

    MacPherson, D.; Sage, J.; Crowley, D.; Trumpp, A.; Bronson, R. T.; Jacks, T.

    2003-01-01

    Targeted disruption of the retinoblastoma gene in mice leads to embryonic lethality in midgestation accompanied by defective erythropoiesis. Rb−/− embryos also exhibit inappropriate cell cycle activity and apoptosis in the central nervous system (CNS), peripheral nervous system (PNS), and ocular lens. Loss of p53 can prevent the apoptosis in the CNS and lens; however, the specific signals leading to p53 activation have not been determined. Here we test the hypothesis that hypoxia caused by defective erythropoiesis in Rb-null embryos contributes to p53-dependent apoptosis. We show evidence of hypoxia in CNS tissue from Rb−/− embryos. The Cre-loxP system was then used to generate embryos in which Rb was deleted in the CNS, PNS and lens, in the presence of normal erythropoiesis. In contrast to the massive CNS apoptosis in Rb-null embryos at embryonic day 13.5 (E13.5), conditional mutants did not have elevated apoptosis in this tissue. There was still significant apoptosis in the PNS and lens, however. Rb−/− cells in the CNS, PNS, and lens underwent inappropriate S-phase entry in the conditional mutants at E13.5. By E18.5, conditional mutants had increased brain size and weight as well as defects in skeletal muscle development. These data support a model in which hypoxia is a necessary cofactor in the death of CNS neurons in the developing Rb mutant embryo. PMID:12529408

  4. Optimal High-TC Superconductivity in Cs3C60

    NASA Astrophysics Data System (ADS)

    Harshman, Dale; Fiory, Anthony

    The highest superconducting transition temperatures in the (A1-xBx)3C60 superconducting family are seen in the A15 and FCC structural phases of Cs3C60 (optimized under hydrostatic pressure), exhibiting measured values for near-stoichiometric samples of TC0 meas . = 37.8 K and 35.7 K, respectively. It is argued these two Cs-intercalated C60 compounds represent the optimal materials of their respective structures, with superconductivity originating from Coulombic e- h interactions between the C60 molecules, which host the n-type superconductivity, and mediating holes associated with the Cs cations. A variation of the interlayer Coulombic pairing model [Harshman and Fiory, J. Supercond. Nov. Magn. 28 ̲, 2967 (2015), and references therein] is introduced in which TC0 calc . ~ 1 / lζ , where l relates to the mean spacing between interacting charges on surfaces of the C60 molecules, and ζ is the average radial distance between the surface of the C60 molecules and the neighboring Cs cations. For stoichiometric Cs3C60, TC0 calc . = 38.08 K and 35.67 K for the A15 and FCC macrostructures, respectively; the dichotomy is attributable to differences in ζ.

  5. Encapsulation of Cs/Sr contaminated clinoptilolite in geopolymers produced from metakaolin

    NASA Astrophysics Data System (ADS)

    Kuenzel, C.; Cisneros, J. F.; Neville, T. P.; Vandeperre, L. J.; Simons, S. J. R.; Bensted, J.; Cheeseman, C. R.

    2015-11-01

    The encapsulation of caesium (Cs) and strontium (Sr) contaminated clinoptilolite in Na and K based metakaolin geopolymers is reported. When Cs or Sr loaded clinoptilolite is mixed with a metakaolin geopolymer paste, the high pH of the activating solution and the high concentration of ions in solution cause ion exchange reactions and dissolution of clinoptilolite with release of Cs and Sr into the geopolymer matrix. The leaching of Cs and Sr from metakaolin-based geopolymer has therefore been investigated. It was found that Na-based geopolymers reduce leaching of Cs compared to K-based geopolymers and the results are in agreement with the hard and soft acids and bases (HSAB) theory. Cs ions are weak Lewis acids and aluminates are a weak Lewis base. During the formation of the geopolymer matrix Cs ions are preferentially bound to aluminate phases and replace Na in the geopolymer structure. Sr uptake by Na-geopolymers is limited to 0.4 mol Sr per mole of Al and any additional Sr is immobilised by the high pH which causes precipitation of Sr as low solubility hydroxide and carbonate phases. There was no evidence of any other phases being formed when Sr or Cs are added to metakaolin geopolymers.

  6. TGF{beta}-mediated formation of pRb-E2F complexes in human myeloid leukemia cells

    SciTech Connect

    Hu Xiaotang

    2008-05-02

    TGF{beta} is well known for its inhibitory effect on cell cycle G1 checkpoint kinases. However, its role in the control of pRb-E2F complexes is not well established. TGF{beta} inhibits phosphorylation of pRb at several serine and threonine residues and regulates the association of E2F transcription factors with pRb family proteins. Recent studies found that predominantly E2F-4, p130, and histone deacetylase (HDAC) are found to bind to corresponding E2F-responsive promoters in G0/G1 phase. As cells progress through mid-G1, p130-E2F4 complex are replaced by p107-E2F4 followed by activators E2F1, 2, and 3. pRb was not detectable in the promoters containing the E2F-responsive site in cycling cells but was associated with E2F4-p130 complexes or E2F4-p107 complexes during G0/G1 phase. In human myeloid leukemia cell line, MV4-11, TGF{beta} upregulated pRb-E2F-4 and p130-E2F-4, and downregulated p107-E2F-4 complexes. However, pRB-E2F1 and pRb-E2F3 complexes were found in proliferating cells but not in TGF{beta} arrested G1 cells. In addition, electrophoretic gel mobility shift assay (EMSA) could not detect pRb-E2F DNA-binding activities either in S or G1 phase but exhibited the existence of p107-E2F4 in proliferating cells and p130-E2F4 complexes in TGF{beta}-arrested G1 cells, respectively. Our data suggest that p107 and p130, but not pRb, and the repressor E2F, but not activator E2Fs, play a critical role in regulating E2F-responsive gene expression in TGF{beta}-mediated cell cycle control in human myeloid leukemia cells.

  7. Dual Hg-Rb magneto-optical trap.

    PubMed

    Witkowski, Marcin; Nagórny, Bartłomiej; Munoz-Rodriguez, Rodolfo; Ciuryło, Roman; Żuchowski, Piotr Szymon; Bilicki, Sławomir; Piotrowski, Marcin; Morzyński, Piotr; Zawada, Michał

    2017-02-20

    We present a two-species laser cooling apparatus capable of simultaneously collecting Rb and Hg atomic gases into a magneto-optical trap (MOT). The atomic sources, laser system, and vacuum set-up are described. While there is a loss of Rb atoms in the MOT due to photoionization by the Hg cooling laser, we show that it does not prevent simultaneous trapping of Rb and Hg. We also demonstrate interspecies collision-induced losses in the 87Rb-202Hg system.

  8. Quorum Sensing Activity in Pandoraea pnomenusa RB38

    PubMed Central

    Ee, Robson; Lim, Yan-Lue; Kin, Lin-Xin; Yin, Wai-Fong; Chan, Kok-Gan

    2014-01-01

    Strain RB38 was recovered from a former dumping area in Malaysia. MALDI-TOF mass spectrometry and genomic analysis identified strain RB-38 as Pandoraea pnomenusa. Various biosensors confirmed its quorum sensing properties. High resolution triple quadrupole liquid chromatography–mass spectrometry analysis was subsequently used to characterize the N-acyl homoserine lactone production profile of P. pnomenusa strain RB38, which validated that this isolate produced N-octanoyl homoserine lactone as a quorum sensing molecule. This is the first report of the production of N-octanoyl homoserine lactone by P. pnomenusa strain RB38. PMID:24919016

  9. RB tumor suppressive function in response to xenobiotic hepatocarcinogens.

    PubMed

    Reed, Christopher; Hutcheson, Jack; Mayhew, Christopher N; Witkiewicz, Agnieszka K; Knudsen, Erik S

    2014-06-01

    Diverse etiologic events are associated with the development of hepatocellular carcinoma. During hepatocarcinogenesis, genetic events likely occur that subsequently cooperate with long-term exposures to further drive the progression of hepatocellular carcinoma. In this study, the frequent loss of the retinoblastoma (RB) tumor suppressor in hepatocellular carcinoma was modeled in response to diverse hepatic stresses. Loss of RB did not significantly affect the response to a steatotic stress as driven by a methionine- and choline-deficient diet. In addition, RB status did not significantly influence the response to peroxisome proliferators that can drive hepatomegaly and tumor development in rodents. However, RB loss exhibited a highly significant effect on the response to the xenobiotic1,4-Bis-[2-(3,5-dichloropyridyloxy)] benzene. Loss of RB yielded a unique proliferative response to this agent, which was distinct from both regenerative stresses and genotoxic carcinogens. Long-term exposure to 1,4-Bis-[2-(3,5-dichloropyridyloxy)] benzene yielded profound tumor development in RB-deficient livers that was principally absent in RB-sufficient tissue. These data demonstrate the context specificity of RB and the key role RB plays in the suppression of hepatocellular carcinoma driven by xenobiotic stress.

  10. Dual Hg-Rb magneto-optical trap

    NASA Astrophysics Data System (ADS)

    Witkowski, Marcin; Nagórny, Bartłomiej; Munoz-Rodriguez, Rodolfo; Ciuryło, Roman; Żuchowski, Piotr Szymon; Bilicki, Sławomir; Piotrowski, Marcin; Morzyński, Piotr; Zawada, Michał

    2017-02-01

    We present a two-species laser cooling apparatus capable of simultaneously collecting Rb and Hg atomic gases into a magneto-optical trap (MOT). The atomic sources, laser system, and vacuum set-up are described. While there is a loss of Rb atoms in the MOT due to photoionization by the Hg cooling laser, we show that it does not prevent simultaneous trapping of Rb and Hg. We also demonstrate interspecies collision-induced losses in the ${}^{87}$Rb-${}^{202}$Hg system.

  11. Rb regulates fate choice and lineage commitment in vivo

    PubMed Central

    Calo, Eliezer; Quintero-Estades, Jose A.; Danielian, Paul S.; Nedelcu, Simona; Berman, Seth D.; Lees, Jacqueline A.

    2010-01-01

    Mutation of the RB-1 tumour suppressor occurs in one third of all human tumours and is particularly associated with retinoblastoma and osteosarcoma1. Numerous functions have been ascribed to the product of the human RB-1 gene, pRB. The best known is pRB’s ability to promote cell cycle exit through inhibition of the E2F transcription factors and the transcriptional repression of genes encoding cell cycle regulators1. In addition, pRB has been shown in vitro to regulate several transcription factors that are master differentiation inducers2. Depending on the differentiation factor and cellular context, pRB can either suppress or promote their transcriptional activity. For example, pRB binds to Runx2 and potentiates its ability to promote osteogenic differentiation program in vitro3. In contrast, pRB acts together with E2F to suppress PPARγ, the master activator of adipogenesis4,5. Since osteoblasts and adipocytes can both arise from mesenchymal stem cells, these observations suggest that pRB might play a role in the choice between these two fates. However, to date, there is no evidence for this in vivo. Here we use mouse models to address this hypothesis in the context of mesenchymal tissue development and tumorigenesis. Our data show that Rb status plays a key role in establishing fate choice between bone and brown adipose tissue in vivo. PMID:20686481

  12. Thermodynamic studies on Cs 4U 5O 17(s) and Cs 2U 2O 7(s) by emf and calorimetric measurements

    NASA Astrophysics Data System (ADS)

    Jayanthi, K.; Iyer, V. S.; Venugopal, V.

    1997-12-01

    The oxygen potentials over the phase field: Cs 4U 5O 17(s)+Cs 2U 2O 7(s)+Cs 2U 4O 12(s) was determined by measuring the emf values between 1048 and 1206 K using a solid oxide electrolyte galvanic cell. The oxygen potential existing over the phase field for a given temperature can be represented by: Δ μ(O 2) (kJ/mol) (±0.5)=-272.0+0.207 T (K). The differential thermal analysis showed that Cs 4U 5O 17(s) is stable in air up to 1273 K. The molar Gibbs energy formation of Cs 4U 5O 17(s) was calculated from the above oxygen potentials and can be given by, Δ fG0 (kJ/mol)±6=-7729+1.681 T (K). The enthalpy measurements on Cs 4U 5O 17(s) and Cs 2U 2O 7(s) were carried out from 368.3 to 905 K and 430 to 852 K respectively, using a high temperature Calvet calorimeter. The enthalpy increments, ( H0T- H0298), in J/mol for Cs 4U 5O 17(s) and Cs 2U 2O 7(s) can be represented by, H0T- H0298.15 (Cs 4U 5O 17) kJ/mol±0.9=-188.221+0.518 T (K)+0.433×10 -3T2 (K)-2.052×10 -5T3 (K) (368 to 905 K) and H0T- H0298.15 (Cs 2U 2O 7) kJ/mol±0.5=-164.210+0.390 T (K)+0.104×10 -4T2 (K)+0.140×10 5(1/ T (K)) (411 to 860 K). The thermal properties of Cs 4U 5O 17(s) and Cs 2U 2O 7(s) were derived from the experimental values. The enthalpy of formation of (Cs 4U 5O 17, s) at 298.15 K was calculated by the second law method and is: Δ fH0298.15=-7645.0±4.2 kJ/mol.

  13. Solid-phase epitaxy of silicon amorphized by implantation of the alkali elements rubidium and cesium

    SciTech Connect

    Maier, R.; Haeublein, V.; Ryssel, H.; Voellm, H.; Feili, D.; Seidel, H.; Frey, L.

    2012-11-06

    The redistribution of implanted Rb and Cs profiles in amorphous silicon during solid-phase epitaxial recrystallization has been investigated by Rutherford backscattering spectroscopy and secondary ion mass spectroscopy. For the implantation dose used in these experiments, the alkali atoms segregate at the a-Si/c-Si interface during annealing resulting in concentration peaks near the interface. In this way, the alkali atoms are moved towards the surface. Rutherford backscattering spectroscopy in ion channeling configuration was performed to measure average recrystallization rates of the amorphous silicon layers. Preliminary studies on the influence of the alkali atoms on the solid-phase epitaxial regrowth rate reveal a strong retardation compared to the intrinsic recrystallization rate.

  14. Transfer kinetics and coefficients of {sup 90}Sr, {sup 134}Cs, and {sup 137}Cs from forage contaminated by Chernobyl fallout to milk of cows

    SciTech Connect

    Fabbri, S.; Sogni, R.; Lusardi, E.

    1994-04-01

    A experiment was conducted to study kinetics, transfer coefficients, and biological half-lives of {sup 90}Sr, {sup 134}Cs, and {sup 137}Cs from feed to milk. A cow was fed a diet containing alfalfa hay contaminated by Chernobyl fallout for 14.5 wk. The time-dependent activity in milk was approximated by a two-compartment model with fast biological half-lives of 2, 0.9, and 1 d and slow biological half-lives of 36.9, 8.7, and 12.4 d for {sup 90}Sr, {sup 134}Cs, and {sup 137}Cs respectively. The transfer coefficients determined in the experiment were 0.0008 d L{sup -1} for {sup 90}Sr, 0.0029 d L{sup -1} for {sup 137}Cs, and 0.0031 d L{sup -1} for {sup 137}Cs. The biological elimination phases of {sup 134}Cs and {sup 137}Cs were described by a two-compartment model while a one-compartment model was proposed for {sup 90}Sr. 18 refs., 4 figs., 2 tabs.

  15. Antiferromagnetic resonance in the Mott insulator fcc-Cs3C60.

    PubMed

    Suzuki, Yuta; Shibasaki, Seiji; Kubozono, Yoshihiro; Kambe, Takashi

    2013-09-11

    The magnetic ground state of the fcc phase of the Mott insulator Cs3C60 was studied using a low-temperature electron spin resonance technique, and antiferromagnetic resonance (AFMR) below 1.57 K was directly observed at ambient pressure. The AFMR modes for the fcc phase of Cs3C60 were investigated using a conventional two-sublattice model with uniaxial anisotropy, and the spin-flop field was determined to be 4.7 kOe at 1.57 K. The static magnetic exchange interactions and anisotropy field for fcc-Cs3C60 were also estimated.

  16. Identification of the genomic mutation in Epha4(rb-2J/rb-2J) mice.

    PubMed

    Mohd-Zin, Siti W; Abdullah, Nor-Linda; Abdullah, Aminah; Greene, Nicholas D E; Cheah, Pike-See; Ling, King-Hwa; Yusof, Hadri; Marwan, Ahmed I; Williams, Sarah M; York, Kerri T; Ahmad-Annuar, Azlina; Abdul-Aziz, Noraishah M

    2016-07-01

    The EphA4 receptor tyrosine kinase is involved in numerous cell-signalling activities during embryonic development. EphA4 has the ability to bind to both types of ephrin ligands, the ephrinAs and ephrinBs. The C57BL/6J-Epha4rb-2J/GrsrJ strain, denoted Epha4(rb-2J/rb-2J), is a spontaneous mouse mutant that arose at The Jackson Laboratory. These mutants exhibited a synchronous hind limb locomotion defect or "hopping gait" phenotype, which is also characteristic of EphA4 null mice. Genetic complementation experiments suggested that Epha4(rb-2J) corresponds to an allele of EphA4, but details of the genomic defect in this mouse mutant are currently unavailable. We found a single base-pair deletion in exon 9 resulting in a frame shift mutation that subsequently resulted in a premature stop codon. Analysis of the predicted structure of the truncated protein suggests that both the kinase and sterile α motif (SAM) domains are absent. Definitive determination of genotype is needed for experimental studies of mice carrying the Epha4(rb-2J) allele, and we have also developed a method to ease detection of the mutation through RFLP. Eph-ephrin family members are reportedly expressed as numerous isoforms. Hence, delineation of the specific mutation in EphA4 in this strain is important for further functional studies, such as protein-protein interactions, immunostaining and gene compensatory studies, investigating the mechanism underlying the effects of altered function of Eph family of receptor tyrosine kinases on phenotype.

  17. Upper Cenozoic basalts with high Sr-87/Sr-86 and Sr/Rb ratios, southern Great Basin, western United States.

    NASA Technical Reports Server (NTRS)

    Hedge, C. E.; Noble, D. C.

    1971-01-01

    The initial strontium isotopic composition of 15 mafic volcanic rocks from the southern Great Basin has been determined. Results indicate that the basalts must have been derived from unusual mantle material in which an originally high Rb/Sr ratio was markedly lowered during an earlier phase of magmatic activity.

  18. Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})]·H{sub 2}O and anhydrous Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})

    SciTech Connect

    Yu, Na; Klepov, Vladislav V.; Villa, Eric M.; Bosbach, Dirk; Suleimanov, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.; Alekseev, Evgeny V.

    2014-07-01

    The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})]·H{sub 2}O (α-, β-RbUAs) and the anhydrous phase Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions. - Graphical abstract: Three different layer geometries observed in the structures of Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})] and α- and β- Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})]·H{sub 2}O. Two different coordination environments of uranium polyhedra (types I and II) are shown schematically on the top of the figure. - Highlights: • Three new uranyl arsenates were synthesized from the hydrothermal reactions. • The phases consist of the topologically identical but geometrically different layers. • Topotactic transitions were observed in the processes of mono-hyrates dehydration.

  19. Involvement of retinoblastoma (Rb) and E2F transcription factors during photodynamic therapy of human epidermoid carcinoma cells A431.

    PubMed

    Ahmad, N; Gupta, S; Mukhtar, H

    1999-03-11

    Photodynamic therapy (PDT), a promising new therapeutic modality for the management of a variety of solid malignancies and many non-malignant diseases, is a bimodal therapy using a porphyrin based photosensitizing chemical and visible light. The proper understanding of the mechanism of PDT-mediated cancer cell-kill may result in improving the efficacy of this treatment modality. Earlier we have shown (Proc. Natl. Acad. Sci. USA; 95: 6977-6982, 1998) that silicon phthalocyanine (Pc4)-PDT results in an induction of the cyclin kinase inhibitor WAF1/CIP1/p21 which, by inhibiting cyclins (E and D1) and cyclin dependent kinases (cdk2 and cdk6), results in a G0/G1-phase arrest followed by apoptosis in human epidermoid carcinoma cells A431. We have also demonstrated the generation of nitric oxide during PDT-mediated apoptosis (Cancer Res.; 58: 1785-1788, 1998). Retinoblastoma (pRb) and E2F family transcription factors are important proteins, which regulate the G1-->S transition in the cell cycle. Here, we provide evidence for the involvement of pRb-E2F/DP machinery as an important contributor of PDT-mediated cell cycle arrest and apoptosis. Western blot analysis demonstrated a decrease in the hyper-phosphorylated form of pRb at 3, 6 and 12 h post-PDT with a relative increase in hypo-phosphorylated pRb. Western blot analysis also revealed that PDT-caused decrease in phosphorylation of pRb occurs at serine-780. The ELISA data demonstrated a time dependent accumulation of hypo-phosphorylated pRb by PDT. This response was accompanied with down-regulation in the protein expression of all five E2F (1-5) family transcription factors, and their heterodimeric partners DP1 and DP2. These results suggest that Pc4-PDT of A431 cells results in a down regulation of hyper-phosphorylated pRb protein with a relative increase in hypo-phosphorylated pRb that, in turn, compromises with the availability of free E2F. We suggest that these events result in a stoppage of the cell cycle

  20. Dielectric, electromechanical, and elastic properties of Rb1- x (NH4) x H2PO4 single crystals

    NASA Astrophysics Data System (ADS)

    Korotkov, L. N.; Likhovaya, D. V.; Levitskii, R. R.; Zachek, I. R.

    2017-01-01

    The longitudinal dielectric, piezoelectric, and elastic characteristics of ferroelectric RbH2PO4 and antiferroelectric NH4H2PO4 crystals are calculated in terms of the modified model of proton ordering with allowance for the piezoelectric coupling in an approximation of a four-particle cluster. The results obtained agree well with known experimental data. Along with this, the electromechanical properties of a Rb0.2(NH4)0.8H2PO4 single crystal undergoing an antiferroelectric phase transition have been studied experimentally over a wide temperature range. The model predictions and the experimental data agree qualitatively.

  1. Reactive barriers for {sup 137}Cs retention

    SciTech Connect

    KRUMHANSL,JAMES L.; BRADY,PATRICK V.; ANDERSON,HOWARD L.

    2000-05-19

    {sup 137}Cs was dispersed globally by cold war activities and, more recently, by the Chernobyl accident. Engineered extraction of {sup 137}Cs from soils and groundwaters is exceedingly difficult. Because the half life of {sup 137}Cs is only 30.2 years, remediation might be more effective (and less costly) if {sup 137}Cs bioavailability could be demonstrably limited for even a few decades by use of a reactive barrier. Essentially permanent isolation must be demonstrated in those few settings where high nuclear level wastes contaminated the environment with {sup 135}Cs (half life 2.3x10{sup 6} years) in addition to {sup 137}Cs. Clays are potentially a low-cost barrier to Cs movement, though their long-term effectiveness remains untested. To identify optimal clays for Cs retention Cs resorption was measured for five common clays: Wyoming Montmorillonite (SWy-1), Georgia Kaolinites (KGa-1 and KGa-2), Fithian Illite (F-Ill), and K-Metabentonite (K-Mbt). Exchange sites were pre-saturated with 0.16 M CsCl for 14 days and readily exchangeable Cs was removed by a series of LiNO{sub 3} and LiCl washes. Washed clay were then placed into dialysis bags and the Cs release to the deionized water outside the bags measured. Release rates from 75 to 139 days for SWy-1, K-Mbt and F- 111 were similar; 0.017 to 0.021% sorbed Cs released per day. Both kaolinites released Cs more rapidly (0.12 to 0.05% of the sorbed Cs per day). In a second set of experiments, clays were doped for 110 days and subjected to an extreme and prolonged rinsing process. All the clays exhibited some capacity for irreversible Cs uptake so most soils have some limited ability to act as a natural barrier to Cs migration. However, the residual loading was greatest on K-Mbt ({approximately} 0.33 wt% Cs). Thus, this clay would be the optimal material for constructing artificial reactive barriers.

  2. Rietveld refinement of the crystal structures of Rb2 XSi5O12 (X = Ni, Mn).

    PubMed

    Bell, Anthony M T; Henderson, C Michael B

    2016-02-01

    The synthetic leucite silicate framework mineral analogues Rb2 XSi5O12 {X = Ni [dirubidium nickel(II) penta-silicate] and Mn [dirubidium manganese(II) penta-silicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using Cu Kα X-rays, show that the title compounds crystallize in the space group Pbca and adopt the cation-ordered structure of Cs2CdSi5O12 and other leucites. The structures consist of tetra-hedral SiO4 and XO4 units sharing corners to form a partially substituted silicate framework. Extraframework Rb(+) cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetra-hedrally coordinated sites (T-sites). However, the Ni displacement parameter and the Ni-O bond lengths suggest that for the X = Ni sample, there may actually be some T-site cation disorder.

  3. Rietveld refinement of the crystal structures of Rb2 XSi5O12 (X = Ni, Mn)

    PubMed Central

    Bell, Anthony M. T.; Henderson, C. Michael B.

    2016-01-01

    The synthetic leucite silicate framework mineral analogues Rb2 XSi5O12 {X = Ni [dirubidium nickel(II) penta­silicate] and Mn [dirubidium manganese(II) penta­silicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using Cu Kα X-rays, show that the title compounds crystallize in the space group Pbca and adopt the cation-ordered structure of Cs2CdSi5O12 and other leucites. The structures consist of tetra­hedral SiO4 and XO4 units sharing corners to form a partially substituted silicate framework. Extraframework Rb+ cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetra­hedrally coordinated sites (T-sites). However, the Ni displacement parameter and the Ni—O bond lengths suggest that for the X = Ni sample, there may actually be some T-site cation disorder. PMID:26958399

  4. ^3He Polarization by Rb Spin Exchange in a Multistage System

    NASA Astrophysics Data System (ADS)

    Coulter, K. P.; Chupp, T. E.; Smith, T. B.; Welsh, R. C.; Zerger, J. N.

    1999-10-01

    Polarization of ^3He by spin exchange with optically pumped Rb has benefited greatly from the use of high powered laser diode arrays. Efficient use of these lasers requires operation of cells with high ^3He densities to match better the pressure broadened Rb absorption line to the wide laser spectral profile. However, lower delivery pressures are often required. For example, for low energy neutron spin filters the optimum ^3He thickness (for practical polarizations) would produce impractically thin cells. A multistage system is practical for applications requiring high ^3He polarization delivered at variable pressure because the optical pumping stage can be separated from the delivery/refilling stages. Additionally, operation can be improved by choosing the appropriate glass for each stage. We have constructed a multistage system that consists of a 70 cc pump cell (Corning 7056 glass), a transition region (Pyrex Glass), and a 350 cc receiving cell (Cs-coated Fused Silica). The cells are connected using commercial Viton-rubber o-ring sealed Pyrex glass valves and ball and socket joints. The transition region is connected to a vacuum pump and gas fill system so that cells may be refilled in situ. Both pump cells and receiving cells have exhibited intrinsic ^3He relaxation times of >35 hours. We will report on tests of this prototype system.

  5. RB, the conductor that orchestrates life, death and differentiation.

    PubMed

    Khidr, L; Chen, P-L

    2006-08-28

    The retinoblastoma susceptibility gene was the first tumor suppressor gene identified in humans and the first tumor suppressor gene knocked out by targeted deletion in mice. RB serves as a transducer between the cell cycle machinery and promoter-specific transcription factors, its most documented activity being the repression of the E2F family of transcription factors, which regulate the expression of genes involved in cell proliferation and survival. Recent investigations of RB function suggest that it works as a fundamental regulator to coordinate pathways of cellular growth and differentiation. In this review, we unravel the novel role of an equally important aspect of RB in downregulating the differentiation inhibitor EID-1 during cellular differentiation by teasing apart the signal, which elicit differentiation and limit cell cycle progression, since the molecular mechanisms relating to RB activation of differentiation is much less understood. We review the various roles for RB in differentiation of neurons, muscle, adipose tissue, and the retina. In addition, we provide an update for the current models of the role of RB in cell cycle to entry and exit, extending the view toward chromatin remodeling and expose the dichotomies in the regulation of RB family members. We conclude with a discussion of a novel RB regulatory network, incorporating the dynamic contribution of EID family proteins.

  6. Measurement of the hyperfine splitting of 133Cs atoms in superfluid helium

    NASA Astrophysics Data System (ADS)

    Imamura, K.; Furukawa, T.; Yang, X. F.; Mitsuya, Y.; Fujita, T.; Hayasaka, M.; Kobayashi, T.; Hatakeyama, A.; Ueno, H.; Odashima, H.; Matsuo, Y.

    2015-04-01

    We have been developing a new nuclear laser spectroscopy method named "OROCHI" (Optical RI-atom Observation in Condensed Helium as Ion-catcher). OROCHI utilizes superfluid helium (He II) not only as an efficient stopping medium of highly energetic ions but also as a host matrix of in-situ atomic laser spectroscopy. Using these characteristic of He II, we produce atomic spin polarization and measure Zeeman and hyperfine structure (HFS) splitting using laser-RF (radio frequency) / MW (microwave) double resonance method. From the measured energy splittings, we can deduce nuclear spins and moments. So far, we have conducted a series of experiments using both stable (85,87Rb, 133Cs, 197Au, 107,109Ag) and unstable isotopes (84,86Rb) to confirm the feasibility of OROCHI method, especially observing Zeeman resonance and determining nuclear spins. The measurement of HFS splitting of atoms introduced into He II is indispensable to clarify the nuclear properties by deducing nuclear moments as well as the study of nuclear spins. For this purpose, we perform a precision measurement of HFS of 133Cs atoms immersed in He II using laser ablation technique. In this paper, we describe the result of the experiment.

  7. Uncommon RB1 somatic mutations in a unilateral retinoblastoma patient.

    PubMed

    Ottaviani, Daniela; Alonso, Cristina; Szijan, Irene

    2015-01-01

    Retinoblastoma (RB) is the most common primary intraocular malignancy in children. Somatic inactivation of both alleles of the RB1 tumor suppressor gene in a developing retina is a crucial event in the initiation of tumorigenesis in most cases of isolated unilateral retinoblastoma. We analyzed the DNA from tumor tissue and peripheral blood of a unilateral retinoblastoma patient to determine the RB1 mutation status and to provide an accurate genetic counseling. A comprehensive approach, based on our previous experience, was used to identify the causative RB1 mutations. Screening for RB1 mutations was performed by PCR direct sequencing, multiplex ligation-dependent probe amplification (MLPA) and Real Time-PCR analyses. Three different mutations were identified in the tumor DNA, which were absent in blood DNA. The somatic origin of these mutations was vital to rule out the heritable condition in this patient.

  8. [Interaction of two tumor suppressors: Phosphatase CTDSPL and Rb protein].

    PubMed

    Beniaminov, A D; Krasnov, G S; Dmitriev, A A; Puzanov, G A; Snopok, B A; Senchenko, V N; Kashuba, V I

    2016-01-01

    Earlier we established that CTDSPL gene encoding small carboxy-terminal domain serine phosphatase can be considered a classical tumor suppressor gene. Besides, transfection of tumor cell line MCF-7 with CTDSPL led to the content decrease of inactive phosphorylated form of another tumor suppressor, retinoblastoma protein (Rb), and subsequently to cell cycle arrest at the G1/S boundary. This result implied that small phosphatase CTDSPL is able to specifically dephosphorylate and activate Rb protein. In order to add some fuel to this hypothesis, in the present work we studied the interaction of two tumor suppressors CTDSPL and Rb in vitro. GST pool-down assay revealed that CTDSPL is able to precipitate Rb protein from MCF-7 cell extracts, while surface plasmon resonance technique showed that interaction of the two proteins is direct. Results of this study reassert that phosphatase CTDSPL and Rb could be involved in the common mechanism of cell cycle regulation.

  9. 75 FR 51654 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-22B and RB211-524 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ...-10] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR) RB211-22B and RB211-524 Series.... The FAA amends Sec. 39.13 by adding the following new AD: 2010-17-10 Rolls-Royce plc: Amendment 39... AD applies to Rolls-Royce plc RB211-22B series and RB211-524B4-D-02, RB211-524D4-19,...

  10. Fischer–Tropsch Synthesis: Characterization Rb Promoted Iron Catalyst

    SciTech Connect

    Sarkar,A.; Jacobs, G.; Ji, Y.; Hamdeh, H.; Davis, B.

    2008-01-01

    Rubidium promoted iron Fischer-Tropsch synthesis (FTS) catalysts were prepared with two Rb/Fe atomic ratios (1.44/100 and 5/100) using rubidium nitrate and rubidium carbonate as rubidium precursors. Results of catalytic activity and deactivation studies in a CSTR revealed that rubidium promoted catalysts result in a steady conversion with a lower deactivation rate than that of the corresponding unpromoted catalyst although the initial activity of the promoted catalyst was almost half that of the unpromoted catalyst. Rubidium promotion results in lower methane production, and higher CO2, alkene and 1-alkene fraction in FTS products. M{umlt o}ssbauer spectroscopic measurements of CO activated and working catalyst samples indicated that the composition of the iron carbide phase formed after carbidization was -Fe5 C2 for both promoted and unpromoted catalysts. However, in the case of the rubidium promoted catalyst, '-Fe2.2C became the predominant carbidic phase as FTS continued and the overall catalyst composition remained carbidic in nature. In contrast, the carbide content of the unpromoted catalyst was found to decline very quickly as a function of synthesis time. Results of XANES and EXAFS measurements suggested that rubidium was present in the oxidized state and that the compound most prevalent in the active catalyst samples closely resembled that of rubidium carbonate.

  11. Rb silencing mediated by the down-regulation of MeCP2 is involved in cell transformation induced by long-term exposure to hydroquinone.

    PubMed

    Liu, Linhua; Ling, Xiaoxuan; Wu, Minhua; Chen, Jialong; Chen, Shaoqiao; Tan, Qiang; Chen, Jiansong; Liu, Jiaxian; Zou, Fei

    2017-02-01

    Hydroquinone (HQ), a metabolite of benzene, is a well-known human carcinogen; however, its molecular mechanisms of action remain unclear. MeCP2 has been traditionally described as a transcriptional repressor, though growing evidence indicates that it also activates gene expression. Here, we investigated whether some epigenetic machinery genes are aberrantly expressed as target tumor suppressor genes in HQ-transformed TK6 lymphoblastoid cells. Our results showed that treatment with 5-Aza-2'-deoxycytidine or trichostatin A enhanced the expression of Rb, resulting in cell arrest in G1-phase, and subsequently, an increase in apoptosis and a decrease in cell growth. Moreover, we hypothesised that Rb was silenced by the down-regulation of MeCP2 in HQ-transformed cells, resulting in the dynamic expression of Rb and epigenetic machinery proteins in HQ-transformed cells at different time points. The expression of Rb and MeCP2 in patients with B-cell non-Hodgkin's lymphoma (B-NHL) showed that positive staining for MeCP2 or Rb was significantly lower in B-NHL tumor tissues, and these changes were significantly and negatively correlated with the grade of B-NHL. The restoration of MeCP2 in HQ-transformed cells enhanced the expression of Rb, promoted cell apoptosis, and inhibited cell growth. The changes in the expression patterns of MeCP2 and Rb were inversely correlated with the degree of DNA methylation. A ChiP assay revealed that MeCP2 proteins were recruited to the Rb promoter with lower 5'-methylcytosine levels. In conclusion, we demonstrated that the down-regulation of MeCP2 silences Rb, a process involved in cell transformation resulting from long-term exposure to HQ. © 2016 Wiley Periodicals, Inc.

  12. Microscopic dynamics of AC{sub 60} compounds in the plastic, polymer, and dimer phases investigated by inelastic neutron scattering

    SciTech Connect

    Schober, H.; Toelle, A.; Renker, B.; Heid, R.; Gompf, F.

    1997-09-01

    We present inelastic neutron-scattering results for AC{sub 60} (A=K,Rb,Cs) compounds. The spectra of the high-temperature fcc phases strongly resemble the ones of pristine C{sub 60} in the plastic phase. At equal temperatures we find identical rotational diffusion constants for pristine C{sub 60} and Rb{sub 1}C{sub 60} (D{sub r}=2.4 10{sup 10} s{sup {minus}1} at 400 K). The changes taking place in the inelastic part of the spectra on cooling AC{sub 60} indicate the formation of strong intermolecular bonds. The buildup of intensities in the gap region separating internal and external vibrations in pure C{sub 60} is the most prominent signature of this transition. The spectra of the low-temperature phases depend on their thermal history. The differences can be explained by the formation of a polymer phase (upon slow cooling from the fcc phase) and a dimer phase (upon fast cooling), respectively. The experimental data are analyzed on the basis of lattice dynamical calculations. The density-of-states are well modeled assuming a [2+2] bond for the polymer and a single intercage bond for the dimer. Indications for different intercage bonding are also found in the internal mode spectra, which, on the other hand, react only weakly to the charge transfer. The dimer phase is metastable and converts into the polymer phase with a strongly temperature-dependent time constant. The transition from the polymer to the fcc phase is accompanied by inelastic precursor effects which are interpreted as the signature of inhomogeneities arising from plastic monomer regions embedded in the polymer phase. In the polymer phase AC{sub 60} compounds show strong anharmonic behavior in the low-temperature region. The possible connection with the metal-to-insulator transition is discussed. {copyright} {ital 1997} {ital The American Physical Society}

  13. Electronic structure of β-RbNd(MoO4)2 by XPS and XES

    NASA Astrophysics Data System (ADS)

    Atuchin, V. V.; Khyzhun, O. Y.; Chimitova, O. D.; Molokeev, M. S.; Gavrilova, T. A.; Bazarov, B. G.; Bazarova, J. G.

    2015-02-01

    β-RbNd(MoO4)2 microplates have been prepared by the multistage solid state synthesis method. The phase composition and micromorphology of the final product have been evaluated by XRD and SEM methods. The electronic structure of β-RbNd(MoO4)2 molybdate has been studied employing the X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES). For the molybdate, the XPS core-level and valence-band spectra, as well as XES bands representing energy distribution of the Mo 4d- and O 2p-like states, have been measured. It has been established that the O 2p-like states contribute mainly to the upper portion of the valence band with also significant contributions throughout the whole valence-band region. The Mo 4D-like states contribute mainly to a lower valence band portion.

  14. RB1 Methylation by SMYD2 Enhances Cell Cycle Progression through an Increase of RB1 Phosphorylation12

    PubMed Central

    Cho, Hyun-Soo; Hayami, Shinya; Toyokawa, Gouji; Maejima, Kazuhiro; Yamane, Yuka; Suzuki, Takehiro; Dohmae, Naoshi; Kogure, Masaharu; Kang, Daechun; Neal, David E; Ponder, Bruce AJ; Yamaue, Hiroki; Nakamura, Yusuke; Hamamoto, Ryuji

    2012-01-01

    It is well known that RB functions are regulated by posttranslational modifications such as phosphorylation and acetylation, but the significance of lysine methylation on RB has not been fully elucidated. Our expression analysis of SMYD2 by quantitative real-time polymerase chain reaction showed that expression levels of SMYD2 are significantly elevated in human bladder carcinomas compared with nonneoplastic bladder tissues (P < .0001), and its expression levels in tumor tissues were much higher than those of any other normal tissues. SMYD2 knockdown resulted in the suppression of cancer cell growth, and cell cycle analysis indicated that SMYD2 might play a crucial role in the G1/S transition. According to an in vitro methyltransferase assay, we found that SMYD2 methylates RB1 protein, and liquid chromatography-tandem mass spectrometry analysis revealed lysine 810 of RB1 to be methylated by SMYD2. Importantly, this methylation enhanced Ser 807/811 phosphorylation of RB1 both in vitro and in vivo. Furthermore, we demonstrated that methylated RB1 accelerates E2F transcriptional activity and promotes cell cycle progression. SMYD2 is an important oncoprotein in various types of cancer, and SMYD2-dependent RB1 methylation at lysine 810 promotes cell cycle progression of cancer cells. Further study may explore SMYD2-dependent RB1 methylation as a potential therapeutic target in human cancer. PMID:22787429

  15. Microstructure of Cs-implanted zirconia: Role of temperature

    NASA Astrophysics Data System (ADS)

    Vincent, L.; Thomé, L.; Garrido, F.; Kaitasov, O.; Houdelier, F.

    2008-12-01

    The aim of this study was to identify experimentally the phase which includes cesium in yttria stabilized zirconia (YSZ). The solubility and retention of cesium in YSZ were studied at high temperature (HT). Cesium was ion implanted (at 300 keV) into YSZ at room temperature (RT), 750 °C, or 900 °C at fluences up to 5×1016 cm-2. The temperature dependence of the radiation-induced damage and of the cesium distribution in YSZ single crystals was investigated by Rutherford backscattering spectrometry and ion channeling. Transmission electron microscopy (TEM) studies were performed in order to determine the damage nature and search for a predicted ternary phase of cesium zirconate. Whatever the implantation temperature, the thickness of the damaged layer increases inwards with ion fluence. At RT, amorphization occurs, caused by the high Cs concentration (7at.%). In situ TEM during postannealing shows recrystallization of cubic zirconia after release of cesium. A high implantation temperature has a significant influence on the nature of radiation defects and on the retained Cs concentration. At HT, dislocation loops and voids are formed but no amorphization is observed whereas polygonization occurs at high fluence. The implanted cesium concentration reaches a saturation value of 1.5 at. % above which Cs can no longer be retained in the matrix and is then released at the surface. At that concentration, cesium forms a solid solution in YSZ; no other phase is formed, neither during irradiation nor after thermal annealing.

  16. Emergent Noncentrosymmetry and Piezoelectricity Driven by Oxygen Octahedral Rotations in n = 2 Dion-Jacobson Phase Layer Perovskites

    SciTech Connect

    Strayer, Megan E.; Gupta, Arnab Sen; Akamatsu, Hirofumi; Lei, Shiming; Benedek, Nicole A.; Gopalan, Venkatraman; Mallouk, Thomas E.

    2016-04-29

    We demonstrate the loss of centrosymmetry via oxygen octahedral rotations in the n = 2 Dion–Jacobson family of layered oxide perovskites, A'LaB2O7 (A' = Rb, Cs; B = Nb, Ta). Ab initio density functional theory calculations predict that all four materials should adopt polar space groups, in contrast to the results of previous experimental studies that have assigned these materials to the centrosymmetric P4/mmm space group. Optical second harmonic generation experiments confirm the presence of a noncentrosymmetric phase at ambient temperature. Piezoresponse force microscopy experiments also show that this phase is piezoelectric. Moreover, to elucidate the symmetry-breaking and assign the appropriate space groups, the crystal structure of CsLaNb2O7is refined as a function of temperature from synchrotron X-ray diffraction data. Above 550 K, CsLaNb2O7 adopts the previously determined centrosymmetric P4/mmm space group. Between 550 and 350 K, the symmetry is lowered to the noncentrosymmetric space group Amm2. Below 350 K, additional symmetry lowering is observed as peak splitting, but the space group cannot be unambiguously identified.

  17. Direct Observation of Charge Transfer in Double-Perovskite-Like RbMn[Fe(CN)6

    NASA Astrophysics Data System (ADS)

    Kato, K.; Moritomo, Y.; Takata, M.; Sakata, M.; Umekawa, M.; Hamada, N.; Ohkoshi, S.; Tokoro, H.; Hashimoto, K.

    2003-12-01

    The charge density distribution has been determined for a transition metal cyanide, RbMn[Fe(CN)6], by means of the maximum entropy Rietveld method combined with the highly angularly resolved synchrotron radiation x-ray powder diffraction at SPring-8 BL02B2. We directly observed a charge transfer from the Mn site to the Fe site in the low-temperature phase. On the basis of a local density approximation calculation, we discuss the origin for the anisotropic bonding electron distribution around the Mn3+ ion in the low-temperature phase.

  18. Ternary chalcogenides Cs2Zn3Se4 and Cs2Zn3Te4 : Potential p -type transparent conducting materials

    DOE PAGES

    Shi, Hongliang; Saparov, Bayrammurad; Singh, David J.; ...

    2014-11-11

    Here we report prediction of two new ternary chalcogenides that can potentially be used as p-type transparent conductors along with experimental synthesis and initial characterization of these previously unknown compounds, Cs2Zn3Ch4 (Ch = Se, Te). In particular, the structures are predicted based on density functional calculations and confirmed by experiments. Phase diagrams, electronic structure, optical properties, and defect properties of Cs2Zn3Se4 and Cs2Zn3Te4 are calculated to assess the viability of these materials as p-type TCMs. Cs2Zn3Se4 and Cs2Zn3Te4, which are stable under ambient air, display large optical band gaps (calculated to be 3.61 and 2.83 eV, respectively) and have smallmore » hole effective masses (0.5-0.77 me) that compare favorably with other proposed p-type TCMs. Defect calculations show that undoped Cs2Zn3Se4 and Cs2Zn3Te4 are p-type materials. However, the free hole concentration may be limited by low-energy native donor defects, e.g., Zn interstitials. Lastly, non-equilibrium growth techniques should be useful for suppressing the formation of native donor defects, thereby increasing the hole concentration.« less

  19. Optical pumping in a microfabricated Rb vapor cell using a microfabricated Rb discharge light source

    SciTech Connect

    Venkatraman, V.; Kang, S.; Affolderbach, C.; Mileti, G.; Shea, H.

    2014-02-03

    Miniature (Rb discharge lamp light source, as well as (2) a conventional glass-blown Rb discharge lamp. The microfabricated Rb lamp cell is a dielectric barrier discharge (DBD) light source, having the same inner cell volume of around 40 mm{sup 3} as that of the resonance cell, both filled with suitable buffer gases. A miniature (∼2 cm{sup 3} volume) test setup based on the M{sub z} magnetometer interrogation technique was used for observation of optical-radiofrequency double-resonance signals, proving the suitability of the microfabricated discharge lamp to introduce efficient optical pumping. The pumping ability of this light source was found to be comparable to or even better than that of a conventional glass-blown lamp. The reported results indicate that the micro-fabricated DBD discharge lamp has a high potential for the development of a new class of miniature atomic clocks, magnetometers, and quantum sensors.

  20. Growth suppression by an E2F-binding-defective retinoblastoma protein (RB): contribution from the RB C pocket.

    PubMed

    Whitaker, L L; Su, H; Baskaran, R; Knudsen, E S; Wang, J Y

    1998-07-01

    Growth suppression by the retinoblastoma protein (RB) is dependent on its ability to form complexes with transcription regulators. At least three distinct protein-binding activities have been identified in RB: the large A/B pocket binds E2F, the A/B pocket binds the LXCXE peptide motif, and the C pocket binds the nuclear c-Abl tyrosine kinase. Substitution of Trp for Arg 661 in the B region of RB (mutant 661) inactivates both E2F and LXCXE binding. The tumor suppression function of mutant 661 is not abolished, because this allele predisposes its carriers to retinoblastoma development with a low penetrance. In cell-based assays, 661 is shown to inhibit G1/S progression. This low-penetrance mutant also induces terminal growth arrest with reduced but detectable activity. We have constructed mutations that disrupt C pocket activity. When overproduced, the RB C-terminal fragment did not induce terminal growth arrest but could inhibit G1/S progression, and this activity was abolished by the C-pocket mutations. In full-length RB, the C-pocket mutations reduced but did not abolish RB function. Interestingly, combination of the C-pocket and 661 mutations completely abolished RB's ability to cause an increase in the percentage of cells in G1 and to induce terminal growth arrest. These results suggest that the A/B or C region can induce a prolongation of G1 through mechanisms that are independent of each other. In contrast, long-term growth arrest requires combined activities from both regions of RB. In addition, E2F and LXCXE binding are not the only mechanisms through which RB inhibits cell growth. The C pocket also contributes to RB-mediated growth suppression.

  1. Fixation of Cs to marine sediments estimated by a stochastic modelling approach.

    PubMed

    Børretzen, Peer; Salbu, Brit

    2002-01-01

    Dumping of nuclear waste in the Kara Sea represents a potential source of radioactive contamination to the Arctic Seas in the future. The mobility of 137Cs ions leached from the waste will depend on the interactions with sediment particles. Whether sediments will act as a continuous permanent sink for released 137Cs, or contaminated sediments will serve as a diffuse source of 137Cs in the future, depends on the interaction kinetics and binding mechanisms involved. The main purpose of this paper is to study the performance of different stochastic models using kinetic information to estimate the time needed for Cs ions to become irreversibly fixed within the sediments. The kinetic information was obtained from 134Cs tracer sorption and desorption (sequential extractions) experiments, conducted over time, using sediments from the Stepovogo Fjord waste dumping site, on the east coast of Novaya Zemlya. Results show that 134Cs ions interact rapidly with the surfaces of the Stepovogo sediment, with an estimated distribution coefficient Kd(eq) of 300 ml/g (or 13m2/g), and the 134Cs ions are increasingly irreversibly fixed to the sediment over time. For the first time, stochastic theory has been utilised for sediment-seawater systems to estimate the mean residence times (MRTs) of Cs ions in operationally defined sediment phases described by compartment models. In the present work, two different stochastic models (i) a Markov process model (MP) being analogous to deterministic compartment models, and (ii) a semi-Markov process model (SMP) which should be physically more relevant for inhomogeneous systems, have been compared. As similar results were obtained using the two models, the less complicated MP model was utilised to predict the time needed for an average Cs ion to become irreversibly fixed in the Stepovogo sediments. According the model, approximately 1100 days of contact time between Cs ions and sediments is needed before 50% of the 134Cs ion becomes fixed in the

  2. Structure and optical properties of a noncentrosymmetric borate RbSr{sub 4}(BO{sub 3}){sub 3}

    SciTech Connect

    Xia, M.J.; Li, R.K.

    2013-01-15

    A new noncentrosymmetric borate, RbSr{sub 4}(BO{sub 3}){sub 3} (abbreviated as RSBO), has been grown from Rb{sub 2}O--B{sub 2}O{sub 3}--RbF flux and its crystal structure was determined by single crystal x-ray diffraction. It crystallizes in space group Ama2 with cell parameters of a=11.128(10) A, b=12.155(15) A, c=6.952(7) A, Z=4. The basic structural units are isolated planar BO{sub 3} groups. Second harmonic generation (SHG) test of the title compound by the Kurtz-Perry method shows that RSBO can be phase matchable with an effective SHG coefficient about two-thirds as large as that of KH{sub 2}PO{sub 4} (KDP). Finally, based on the anionic group approximation, the optical properties of the title compound are compared with those of the structure-related apatite-like compounds with the formula 'A{sub 5}(TO{sub n}){sub 3}X'. - Graphical abstract: RbSr{sub 4}(BO{sub 3}){sub 3} and some other borate NLO compounds, namely Ca{sub 5}(BO{sub 3}){sub 3}F RCa{sub 4}(BO{sub 3}){sub 3}O (R=Y or Gd) and Na{sub 3}La{sub 2}(BO{sub 3}){sub 3} can be viewed as the derivatives of apatite. They have similar formula composed of five cations and three anion groups (we call them 5/3 structures). The detailed SHG coefficients and optical properties of the apatite-like NLO crystals were compared and summarized. Highlights: Black-Right-Pointing-Pointer A new noncentrosymmetric borate RbSr{sub 4}(BO{sub 3}){sub 3} was grown from flux. Black-Right-Pointing-Pointer The RbSr{sub 4}(BO{sub 3}){sub 3} can be viewed as a derivative of the apatite-like structure. Black-Right-Pointing-Pointer The structure and its relationship to the optical properties of RbSr{sub 4}(BO{sub 3}){sub 3} are compared with other NLO crystals with apatite-like structures. Black-Right-Pointing-Pointer The basic structural units are the planar BO{sub 3} groups in the structure. Black-Right-Pointing-Pointer Second harmonic generation (SHG) test shows that RbSr{sub 4}(BO{sub 3}){sub 3} can be phase matchable with an

  3. Micelle and microemulsion properties of cesium di-dodecyl-dimethylsulfosuccinate, Cs-AOT

    SciTech Connect

    Sheu, E.Y.; Nostro, P.L.; Capuzzi, G.; Baglioni, P.

    1999-09-28

    Cesium di-2-ethylsulfosuccinate (Cs-AOT) micelles in aqueous solutions and Cs-AOT/water/n-decane microemulsions were investigated, at 22 {plus{underscore}minus} 0.1 C, by small angle neutron scattering (SANS). The critical micelle concentration of Cs-AOT is {approximately}2mM, comparable to that of Na-AOT. However, their solution properties and micellar structures were found to be very different. The solubility of Na-AOT in water is approximately 1 wt %, and the micelles grow from spherical (at a concentration of about 0.1 wt %) to oblate objects with eccentricity equal to about 0.8 (at a concentration of 1 wt %), whereas Cs-AOT is largely soluble in water, over 30 wt %, and its micelles are disklike at 1 wt %. As the surfactant concentration increases, micelles may go through an L{sub 3} region, and enter the lamellar phase. Cs-AOT/water/n-decane microemulsions, with a [water]/[Cs-AOT] = 29.1, form isotropic L{sub 2} phases only at very low Cs-AOT + ater volume fractions (below 0.0165), whereas Na-AOT has a large L{sub 2} region. These differences are probably due to the degree of charge condensation near the AOT polar headgroups. A theoretical description is needed to better understand this behavior.

  4. Microdistributions of Rb and Sr in ALH84001 carbonates: Chronological implications for secondary alteration on Mars

    SciTech Connect

    Wadhwa, M.; Sutton, S.R.; Flynn, G.J.

    2005-04-22

    Concentrations of Rb and Sr were analyzed on the micron-scale in various compositional zones of the ALH84001 carbonates. Implications of the measured Rb/Sr ratios for the chronology of these carbonates are discussed. ALH84001 is unique among the Martian meteorites in that it has an ancient crystallization age of {approx}4.5 Ga defined by Sm-Nd isotope systematics. Another aspect that differentiates this Martian meteorite from the others is the presence of Ca-Fe-Mg carbonates (modal abundance {approx}1%) that are thought to have been precipitated during alteration in a near-surface environment. Precise age dating of these carbonates is important since it could provide constraints on the timing of surficial secondary alteration processes on Mars. However, this has been a challenging problem owing to the relatively small abundance of the carbonates in ALH84001 and because these carbonates are difficult to separate from the other minerals in the rock by physical and chemical means. Previous investigations have attempted to separate the carbonates by leaching of carbonate-rich mineral fractions. The single 'bulk carbonate' fraction analyzed by Wadhwa and Lugmair was characterized by a low {sup 87}Rb/{sup 86}Sr ratio of {approx}0.05, the lowest of any mineral in ALH84001, and the corresponding Rb-Sr age estimate ({approx}1.39 Ga) was dependent on the assumption of isotopic equilibrium between the carbonates and plagioclase. As pointed out by Borg et al., such an assumption may not be assured and, therefore, they obtained multiple carbonate-rich leachates with a range of {sup 87}Rb/{sup 86}Sr ratios (0.12-2.62) from which they estimated an age of {approx}3.9 Ga. Although these authors performed painstaking chemical characterization to determine contributions in the leachates from minerals such as phosphates and silicates, it is nevertheless difficult to positively rule out contributions from other as yet unidentified phases. Therefore, the goal of the present

  5. Tailoring to RB: tumour suppressor status and therapeutic response

    PubMed Central

    Knudsen, Erik S.; Knudsen, Karen E.

    2010-01-01

    The retinoblastoma tumour suppressor (RB) is a crucial regulator of cell-cycle progression that is invoked in response to a myriad of anti-mitogenic signals. It has been hypothesized that perturbations of the RB pathway confer a synonymous proliferative advantage to tumour cells; however, recent findings demonstrate context-specific outcomes associated with such lesions. Particularly, loss of RB function is associated with differential response to wide-ranging therapeutic agents. Thus, the status of this tumour suppressor may be particularly informative in directing treatment regimens. PMID:19143056

  6. Chloride-dependent acceleration of cell cycle via modulation of Rb and cdc2 in osteoblastic cells

    SciTech Connect

    Maki, Masahiro; Miyazaki, Hiroaki; Nakajima, Ken-ichi; Yamane, Junko; Niisato, Naomi; Morihara, Toru; Kubo, Toshikazu; Marunaka, Yoshinori

    2007-10-05

    In the present study, we investigated if Cl{sup -} regulates the proliferation of the MC3T3-E1 osteoblastic cells. The proliferation of MC3T3-E1 osteoblastic cells was diminished by lowering the extracellular Cl{sup -} concentration ([Cl{sup -}]{sub o}) in the culture medium. The lowered in [Cl{sup -}]{sub o} increased the periods of the G{sub 0}/G{sub 1} and the G{sub 2}/M phases in cell cycle. We further studied the effects of [Cl{sup -}]{sub o} on the key enzymes, Rb and cdc2, playing key roles in checking points of the G{sub 0}/G{sub 1} and the G{sub 2}/M phases in cell cycle. The lowered in [Cl{sup -}]{sub o} diminished the active forms of enzymes, Rb and cdc2. We further found that the action of lowered [Cl{sup -}]{sub o} on the cell proliferation, the cell cycle, Rb and cdc2 was abolished by the presence of 2 mM glutamine, but not by that of pyruvate as another Krebs cycle substrate. Taken together, these observations indicate here for the first time that Cl{sup -} modulates Rb and cdc2, enhancing the proliferation of the MC3T3-E1 osteoblastic cells.

  7. Pressure induced tetragonal to monoclinic transition in RbN3 studied from first principles theory

    NASA Astrophysics Data System (ADS)

    Vaitheeswaran, G.; Babu, K. Ramesh

    2014-04-01

    Alkali metal azides are well known for their application as explosives and gas generators. They are used as precursors in synthesis of polymeric nitrogen, an ultimate green high energy density material. Among the alkali metal azides, rubidium azide RbN3 crystallizes in tetragonal structure with linear azide ions arranged in layers and binds through weak dispersive interactions. In this present work, we have studied the structural stability, electronic structure and optical properties of solid RbN3 by using van der Waals corrected density functional theory. We find that the ambient tetragonal structure undergoes a structural transition to monoclinic structure at 0.72 GPa, which is in good agreement with the experimental transition pressure of less than 1 GPa. The phonon frequencies at the gamma point are calculated and found that the lattice mode Eg softens under pressure which may supports the structural phase transition. The electronic band structure and optical properties are calculated by using Tran Blaha-modified Becke Johnson (TB-mBJ) functional and found that solid RbN3 is an insulator with a gap of 5.976 eV and the optical absorption starts with the UV light of wave length 207.5 nm.

  8. Crystal structure and superconductivity of rubidium tungsten bronzes Rb{sub x}WO{sub 3} prepared by a hybrid microwave method

    SciTech Connect

    Guo Juan Dong Cheng; Yang Lihong; Chen Hong

    2008-04-01

    The rubidium tungsten bronzes Rb{sub x}WO{sub 3} have been prepared from Rb{sub 2}CO{sub 3}, WO{sub 3} and W powders using hybrid microwave method. The single hexagonal phase samples can be obtained as actual rubidium content x in the range of 0.21-0.33, and their lattice parameters a and c linearly drop and rise with the increase of rubidium content respectively. For samples with x = 0.14, 0.16, 0.18, the superconducting transition temperature T{sub c} from resistivity measurements does not change with the rubidium content, while T{sub c} from susceptibility measurements shows a decrease from 5.3 K for x = 0.14 to 4.8 K for x = 0.18. The charge density wave (CDW) transition appears in Rb{sub 0.21}WO{sub 3}, Rb{sub 0.23}WO{sub 3} and Rb{sub 0.25}WO{sub 3} at about 200-260 K. The CDW transition is most obvious in Rb{sub 0.23}WO{sub 3} which shows the lowest degree of crystallization among the samples.

  9. Rb-Sr Chronology of Chondrules from Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

    Rotenberg, E.; Amelin, Y.

    2002-03-01

    Chondritic silicates and individual chondrules have been shown to be precise U-Pb chronometers. Rb-Sr has been analysed in those same materials to compare the behaviour of the two isotopic systems in silicates and phosphates.

  10. Unit 3, STA. 158+ 40 RB, Hinckson Run culvertdetail ...

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

    Unit 3, STA. 158+ 40 RB, Hinckson Run culvert-detail - Johnstown Local Flood Protection Project, Beginning on Conemaugh River approx 3.8 miles downstream from confluence of Little Conemaugh & Stony Creek Rivers at Johnstown, Johnstown, Cambria County, PA

  11. .sup.82 Sr-.sup.82 Rb Radioisotope generator

    DOEpatents

    Grant, Patrick M.; Erdal, Bruce R.; O'Brien, Harold A.

    1976-01-01

    An improved .sup.82 Sr-.sup.82 Rb radioisotope generator system, based upon the complexing ion exchange resin Chelex-100, has been developed. Columns of this material can be easily and rapidly milked, and the Rb-Sr separation factor for a fresh generator was found to be > 10.sup.7. Approximately 80 percent of the .sup.82 Rb present was delivered in a 15-ml volume of aqueous 0.2 M NH.sub.4 Cl solution. After more than 6 liters of eluant had been put through the generator, the Rb-Sr separation factor was still observed to be > 10.sup.5, and no unusual strontium breakthrough behavior was seen in the system over nearly three .sup.82 Sr half lives.

  12. Control of glutamine metabolism by the tumor suppressor Rb.

    PubMed

    Reynolds, M R; Lane, A N; Robertson, B; Kemp, S; Liu, Y; Hill, B G; Dean, D C; Clem, B F

    2014-01-30

    Retinoblastoma (Rb) protein is a tumor suppressor that is dysregulated in a majority of human cancers. Rb functions to inhibit cell cycle progression in part by directly disabling the E2F family of cell cycle-promoting transcription factors. Because the de novo synthesis of multiple glutamine-derived anabolic precursors is required for cell cycle progression, we hypothesized that Rb also may directly regulate proteins involved in glutamine metabolism. We examined glutamine metabolism in mouse embryonic fibroblasts (MEFs) isolated from mice that have triple knock-outs (TKO) of all three Rb family members (Rb-1, Rbl1 and Rbl2) and found that loss of global Rb function caused a marked increase in (13)C-glutamine uptake and incorporation into glutamate and tricarboxylic acid cycle (TCA) intermediates in part via upregulated expression of the glutamine transporter ASCT2 and the activity of glutaminase 1 (GLS1). The Rb-controlled transcription factor E2F-3 altered glutamine uptake by direct regulation of ASCT2 mRNA and protein expression, and E2F-3 was observed to associate with the ASCT2 promoter. We next examined the functional consequences of the observed increase in glutamine uptake and utilization and found that glutamine exposure potently increased oxygen consumption, whereas glutamine deprivation selectively decreased ATP concentration in the Rb TKO MEFs but not the wild-type (WT) MEFs. In addition, TKO MEFs exhibited elevated production of glutathione from exogenous glutamine and had increased expression of gamma-glutamylcysteine ligase relative to WT MEFs. Importantly, this metabolic shift towards glutamine utilization was required for the proliferation of Rb TKO MEFs but not for the proliferation of the WT MEFs. Last, addition of the TCA cycle intermediate α-ketoglutarate to the Rb TKO MEFs reversed the inhibitory effects of glutamine deprivation on ATP, GSH levels and viability. Taken together, these studies demonstrate that the Rb/E2F cascade directly

  13. Development of Composite Adsorbents for LLW Treatment and Their Adsorption Properties for Cs and Sr - 13127

    SciTech Connect

    Susa, Shunsuke; Mimura, Hitoshi; Ito, Yoshiyuki; Saito, Yasuo

    2013-07-01

    In this study, the composite adsorbents (KCoFC-NM (NM: natural mordenite), KCoFC-SG (SG: porous silica gel), AMP-SG and so on) were prepared by impregnation-precipitation methods. As for the distribution properties, the largest K{sub d,Cs} value of 3.8 x 10{sup 4} cm{sup 3}/g was obtained for KCoFC-SG (Davi.) composite. KCoFC-SG (NH, MB5D) and T-KCFC also had relatively large K{sub d,Cs} values above 1.0 x 10{sup 4} cm{sup 3}/g. The uptake rate of Cs{sup +} ions was examined by batch method. KCoFC-SG (NH, MB5D) and AMP-SG (Davi.) had relatively large uptake rate of Cs{sup +}, and the uptake attained equilibrium within 1 h. The maximum uptake capacity of Cs{sup +} ions was estimated to be above 0.5 mmol/g for KCoFC-NM and KCoFC-CP composites. KCoFC-X composite had a relatively large uptake capacity of Cs{sup +} ions (0.23 mmol/g > 0.17 mmol/g (T-KCFC)) and this composite also had a selectivity towards Sr{sup 2+} ions; KCoFC-X is effective adsorbent for both Cs{sup +} and Sr{sup 2+} ions. The largest value of K{sub d,Sr} was estimated to be 218 cm{sup 3}/g for titanic acid-PAN. Titanic acid-PAN had the largest uptake rate of Sr{sup 2+} ions, and the uptake attained equilibrium within 8 h. Adsorbability of other nuclides was further examined by batch method. All adsorbents had adsorbability for Rb{sup +} and RuNO{sup 3+} ions. KCoFC-SG (NH), KCoFC-CP and T-KCFC had higher selectivity towards Cs{sup +} than other adsorbents; these adsorbents had adsorbability to Cs{sup +} ions even in the presence of Ba{sup 2+}, Ca{sup 2+} and Mg{sup 2+} ions. The separation factor of K{sub d,Sr}/K{sub d,Ba} for titanic acid-PAN was about 1, indicating that the K{sub d,Sr} for titanic acid-PAN tends to decrease with Ba{sup 2+} concentration. As for the breakthrough properties, the largest 5 % breakpoint and 5 % breakthrough capacity of Cs{sup +} ions were estimated to be 47.1 cm{sup 3} and 0.07 mmol/g for the column of KCoFC-SG (NH), respectively. The order of 5 % breakthrough capacity

  14. [Study on the Effects of Ginsenoside Rb1 on DPPC Bilayers by Using Thermo-Raman Spectrum and DSC].

    PubMed

    Hui, Ge; Liu, Wei; Zhang, Jing-zhou; Zhou, Tie-li; Wang, Si-ming; Zhao, Yu; Zhao, Bing

    2015-08-01

    The research on the interactions between Ginsenosides and biomembranes plays a crucial role in thorough understanding the pharmacological activity and biologyical effect of Chinese medicine Panax ginseng. With the bilayer structure, DPPC often serves as an simulation model of the cell membrane to study the role of drug molecules and cell membranes. Ginsenoside Rb1, one of the most important components of Panaxginseng, playing the significant roles of pharmacological effects and biological properties. Raman and differential scanning calorimetry (DSC) are respectively a powerful tool for discussing the molecular interaction, and a kind of general technology by which researching the bilayer monomer structures and its interactions with drug molecules. However, rarely research reports on the interactions between drug molecules and biomembranes by means of both technologies above. In this paper, the influence of ginsenoside monomer Rb1 on DPPC membrane bilayers was investigated by thermo-Raman and DSC. In Raman spectra, the changes of DPPC molecule have been observed before and after interacted with ginsenoside Rb1, the data analysis indicates three aspects: the O-C-C-N+ polar head group skeleton, C-C stretching vibration area, and the C-H bond stretching vibrarion in terminated methyl group of alkyl chains. The results showed that ginsenoside Rb1 molecule with certain concentration has not changed the gauche conformation of the polar head backbone group in DPPC bilayers, the order of the internal molecular chain and the lateral chain-chain packing have been decreased as the temperature increased, the lateral disposed disorder has been increased. The changes of some thermodynamic constants obtained by DSC experiment such as phase transition temperature (Tm), the temperature at which the transition is half completed (ΔT1/2), and the transition enthalpy normalized per mol of DPPC (AH) have been showed further results of the thermo Raman experiments, with increasing the

  15. Towards ultracold RbCa molecules

    NASA Astrophysics Data System (ADS)

    Kleinert, Michaela

    2011-10-01

    Ultracold heteronuclear molecules have received much attention lately because of their potential applications in high-precision spectroscopy, studies of fundamental symmetries and quantum information processing. So far the focus has been on alkaline/alkaline dimers since their constituent atoms have been studied extensively. Recently, several groups have begun work on more challenging alkaline/alkaline-earth or alkaline/rare-earth combinations. In addition to a permanent electric dipole moment, which makes the alkaline/alkaline dimers such an intriguing system, alkaline/alkaline-earth molecules also possess a permanent magnetic dipole moment, thus allowing the manipulation with electric and magnetic fields. In addition, the molecular ground state of an alkaline/alkaline-earth dimer has a non-vanishing spin. Interesting collision dynamics, for example the suppression of collisions in carefully tailored external fields, have been predicted. At Willamette University, we will trap ultracold gases of rubidium and calcium together to form the molecular dimer RbCa via photoassociation of the constituent atoms. In this talk we will discuss the current state of the experiment and our future plans.[4pt] In collaboration with Hayley Whitson, Garrett Potter, and Kristen Norton, Willamette University.

  16. Potential value of Cs-137 capsules

    SciTech Connect

    Bloomster, C.H.; Brown, D.R.; Bruno, G.A.; Hazelton, R.F.; Hendrickson, P.L.; Lezberg, A.J.; Tingey, G.L.; Wilfert, G.L.

    1985-04-01

    We determined the value of Cs-137 compared to Co-60 as a source for the irradiation of fruit (apples and cherries), pork and medical supplies. Cs-137, in the WESF capsule form, had a value of approximately $0.40/Ci as a substitute for Co-60 priced at approximately $1.00/Ci. The comparison was based on the available curies emitted from the surface of each capsule. We developed preliminary designs for fourteen irradiation facilities; seven were based on Co-60 and seven were based on Cs-137. These designs provided the basis for estimating capital and operating costs which, in turn, provided the basis for determining the value of Cs-137 relative to Co-60 in these applications. We evaluated the effect of the size of the irradiation facility on the value of Cs-137. The cost of irradiation is low compared to the value of the product. Irradiation of apples for disinfestation costs $.01 to .02 per pound. Irradiation for trichina-safe pork costs $.02 per pound. Irradiation of medical supplies for sterilization costs $.07 to .12 per pound. The cost of the irradiation source, either Co-60 or Cs-137, contributed only a minor amount to the total cost of irradiation, about 5% for the fruit and hog cases and about 20% for the medical supply cases. We analyzed the sensitivity of the irradiation costs and Cs-137 value to several key assumptions.

  17. Memory Is Not Extinguished along with CS Presentation but within a Few Seconds after CS-Offset

    ERIC Educational Resources Information Center

    Perez-Cuesta, Luis Maria; Hepp, Yanil; Pedreira, Maria Eugenia; Maldonado, Hector

    2007-01-01

    Prior work with the crab's contextual memory model showed that CS-US conditioned animals undergoing an unreinforced CS presentation would either reconsolidate or extinguish the CS-US memory, depending on the length of the reexposure to the CS. Either memory process is only triggered once the CS is terminated. Based on these results, the following…

  18. Role of Rb family in the epigenetic definition of chromatin.

    PubMed

    Gonzalo, Susana; Blasco, María A

    2005-06-01

    Epigenetic changes can influence a variety of cellular processes from regulation of gene transcription to proper chromosome segregation. The molecular activities that dictate the assembly, maintenance and regulation of chromatin structure are beginning to be identified. A recent study demonstrates that the Rb family of tumor suppressors plays a major role in global chromatin structure. In addition to the well-known function of Rb family inducing a repressive chromatin state around euchromatic promoters, Rb proteins have a direct role in the assembly of pericentric and telomeric heterochromatin domains. In particular, the Rb family maintains histone 4 lysine 20 tri-methylation (H4K20) at these constitutive heterochromatin domains. Lack of the Rb family results in decreased H4K20 tri-methylation, coincidental with chromosome segregation defects and abnormal telomere elongation, two processes frequently altered in human cancer. Maintenance of heterochromatic domains, such as those of centromeres and telomeres, may represent a novel tumor suppressor function for the Rb family by ensuing genomic stability.

  19. Efficacy of degarelix in prostate cancer patients following failure on luteinizing hormone-releasing hormone agonist treatment: results from an open-label, multicentre, uncontrolled, phase II trial (CS27)

    PubMed Central

    Simson, Gabriele; Goble, Sandra; Persson, Bo-Eric

    2015-01-01

    Objective: To evaluate the efficacy of second-line degarelix in patients with prostate cancer (PCa) after treatment failure with a luteinizing hormone-releasing hormone (LHRH) agonist. Methods: This 1-year exploratory, multicentre, open-label phase II trial was performed in 2 patient cohorts (Cohort 1, n = 25; Cohort 2, n = 12) in Germany. Patients with castrate-resistant PCa after primary hormonal treatment received degarelix 240 mg, followed by 11 monthly maintenance doses of 80 mg. The primary endpoint was the proportion of patients with decreasing/stable prostate-specific antigen (PSA) (relative change ⩽+10% of baseline PSA) after 3 months. Results: At Month 3, the response rate (intention-to-treat, last observation carried forward analysis) was 16.7% [95% confidence interval (CI): 4.74–37.38] in Cohort 1 and 33.3% (95% CI: 9.92–65.11) in Cohort 2. The probability of completing 12 months without PSA progression was 8.8% (95% CI: 1.51–24.3) in Cohort 1 and 8.3% (95% CI: 0.5–31.1) in Cohort 2. Degarelix was well tolerated; the most frequently reported adverse events were local injection-site reactions. Conclusions: In PCa patients who failed LHRH therapy, degarelix was well tolerated and achieved a limited PSA response. Phase III trials show that disease control benefits with degarelix versus agonists are more clearly demonstrated as first-line therapy. PMID:26161141

  20. Immune Response of Calves Vaccinated with Brucella abortus S19 or RB51 and Revaccinated with RB51.

    PubMed

    Dorneles, Elaine M S; Lima, Graciela K; Teixeira-Carvalho, Andréa; Araújo, Márcio S S; Martins-Filho, Olindo A; Sriranganathan, Nammalwar; Al Qublan, Hamzeh; Heinemann, Marcos B; Lage, Andrey P

    2015-01-01

    Brucella abortus S19 and RB51 strains have been successfully used to control bovine brucellosis worldwide; however, currently, most of our understanding of the protective immune response induced by vaccination comes from studies in mice. The aim of this study was to characterize and compare the immune responses induced in cattle prime-immunized with B. abortus S19 or RB51 and revaccinated with RB51. Female calves, aged 4 to 8 months, were vaccinated with either vaccine S19 (0.6-1.2 x 1011 CFU) or RB51 (1.3 x 1010 CFU) on day 0, and revaccinated with RB51 (1.3 x 1010 CFU) on day 365 of the experiment. Characterization of the immune response was performed using serum and peripheral blood mononuclear cells. Blood samples were collected on days 0, 28, 210, 365, 393 and 575 post-immunization. Results showed that S19 and RB51 vaccination induced an immune response characterized by proliferation of CD4+ and CD8+ T-cells; IFN-ɣ and IL-17A production by CD4+ T-cells; cytotoxic CD8+ T-cells; IL-6 secretion; CD4+ and CD8+ memory cells; antibodies of IgG1 class; and expression of the phenotypes of activation in T-cells. However, the immune response stimulated by S19 compared to RB51 showed higher persistency of IFN-ɣ and CD4+ memory cells, induction of CD21+ memory cells and higher secretion of IL-6. After RB51 revaccination, the immune response was chiefly characterized by increase in IFN-ɣ expression, proliferation of antigen-specific CD4+ and CD8+ T-cells, cytotoxic CD8+ T-cells and decrease of IL-6 production in both groups. Nevertheless, a different polarization of the immune response, CD4+- or CD8+-dominant, was observed after the booster with RB51 for S19 and RB51 prime-vaccinated animals, respectively. Our results indicate that after prime vaccination both vaccine strains induce a strong and complex Th1 immune response, although after RB51 revaccination the differences between immune profiles induced by prime-vaccination become accentuated.

  1. Emission mechanism of polyatomic ions Cs2Cl+ and Cs2BO2(+) in thermal ionization mass spectrometry with various carbon materials.

    PubMed

    Wei, Hai-Zhen; Jiang, Shao-Yong; Hemming, Gary N; Yang, Jing-Hong; Xiao, Ying-Kai; Yang, Tao; Yan, Xiong; Yan, Yan

    2011-12-29

    The emission behavior of polyatomic ions Cs(2)Cl(+) and Cs(2)BO(2)(+) in the presence of various carbon materials (Graphite, Carbon, SWNTs, and Fullerenes) in the ionization source of thermal ionization mass spectrometry (TIMS) has been investigated. The emission capacity of various carbon materials are remarkably different as evidenced by the obvious discrepancy in signal intensity of polyatomic ions and accuracy/precision of boron and chlorine isotopic composition determined using Cs(2)Cl(+)-graphite-PTIMS/Cs(2)BO(2)(+)-graphite-PTIMS methods. Combined with morphology and microstructure properties of four selected carbon materials, it could be concluded that the emission behavior of the polyatomic ions strongly depends on the microstructure of the carbon materials used. A surface-induced collision mechanism for formation of such kinds of polyatomic ions in the ionization source of TIMS has been proposed based on the optimized configuration of Cs(2)BO(2)(+) and Cs(2)Cl(+) ions in the gas phase using a molecular dynamics method. The combination of the geometry of the selected carbon materials with the configuration of two polyatomic ions explains the structure effect of carbon materials on the emission behavior of polyatomic ions, where graphite samples with perfect parallels and equidistant layers ensure the capacity of emission to the maximum extent, and fullerenes worsen the emission of polyatomic ions by blocking their pathway.

  2. Le nitrate double NaRb2(NO3)3, composé intermédiaire du système binaire isobare NaNO3 + RbNO3: études thermiques et cristallographiques

    PubMed Central

    Ksiksi, Nesrine; Driss, Mohamed; Hellali, Dalila; Guesmi, Abderrahmen; Zamali, Hmida

    2015-01-01

    Crystallographic and thermodynamic investigations of the binary (NaNO3 + RbNO3) phase diagram at atmospheric pressure reveal the existence of an inter­mediate compound NaRb2(NO3)3 (sodium dirubidium trinitrate) previously predicted and now reported experimentally for the first time. According to a DSC analysis, the compound exhibits three allotropic forms. In its low-temperature allotropic form (α form, ortho­rhom­bic) there are two Rb (m.. site symmetry) and one Na (m..) independent crystallographic positions and three planar nitrate groups. The bond-valence-sum calculations for all atoms agree well with their oxidation states. The Rb cations are located in the (100) plane at x = ½ with 11 oxygen coordination. The Na ones are in the same plane at x = 0 and are coordinated to eight O atoms from six nitrate groups. The charge-distribution method has been used to evaluate the degree of distortion of the alkali polyhedra. PMID:25995854

  3. Le nitrate double NaRb2(NO3)3, composé intermédiaire du système binaire isobare NaNO3 + RbNO3: études thermiques et cristallographiques.

    PubMed

    Ksiksi, Nesrine; Driss, Mohamed; Hellali, Dalila; Guesmi, Abderrahmen; Zamali, Hmida

    2015-05-01

    Crystallographic and thermodynamic investigations of the binary (NaNO3 + RbNO3) phase diagram at atmospheric pressure reveal the existence of an inter-mediate compound NaRb2(NO3)3 (sodium dirubidium trinitrate) previously predicted and now reported experimentally for the first time. According to a DSC analysis, the compound exhibits three allotropic forms. In its low-temperature allotropic form (α form, ortho-rhom-bic) there are two Rb (m.. site symmetry) and one Na (m..) independent crystallographic positions and three planar nitrate groups. The bond-valence-sum calculations for all atoms agree well with their oxidation states. The Rb cations are located in the (100) plane at x = ½ with 11 oxygen coordination. The Na ones are in the same plane at x = 0 and are coordinated to eight O atoms from six nitrate groups. The charge-distribution method has been used to evaluate the degree of distortion of the alkali polyhedra.

  4. Proteomic analysis of pRb loss highlights a signature of decreased mitochondrial oxidative phosphorylation

    PubMed Central

    Nicolay, Brandon N.; Danielian, Paul S.; Kottakis, Filippos; Lapek, John D.; Sanidas, Ioannis; Miles, Wayne O.; Dehnad, Mantre; Tschöp, Katrin; Gierut, Jessica J.; Manning, Amity L.; Morris, Robert; Haigis, Kevin; Bardeesy, Nabeel; Lees, Jacqueline A.; Haas, Wilhelm; Dyson, Nicholas J.

    2015-01-01

    The retinoblastoma tumor suppressor (pRb) protein associates with chromatin and regulates gene expression. Numerous studies have identified Rb-dependent RNA signatures, but the proteomic effects of Rb loss are largely unexplored. We acutely ablated Rb in adult mice and conducted a quantitative analysis of RNA and proteomic changes in the colon and lungs, where RbKO was sufficient or insufficient to induce ectopic proliferation, respectively. As expected, RbKO caused similar increases in classic pRb/E2F-regulated transcripts in both tissues, but, unexpectedly, their protein products increased only in the colon, consistent with its increased proliferative index. Thus, these protein changes induced by Rb loss are coupled with proliferation but uncoupled from transcription. The proteomic changes in common between RbKO tissues showed a striking decrease in proteins with mitochondrial functions. Accordingly, RB1 inactivation in human cells decreased both mitochondrial mass and oxidative phosphorylation (OXPHOS) function. RBKO cells showed decreased mitochondrial respiratory capacity and the accumulation of hypopolarized mitochondria. Additionally, RB/Rb loss altered mitochondrial pyruvate oxidation from 13C-glucose through the TCA cycle in mouse tissues and cultured cells. Consequently, RBKO cells have an enhanced sensitivity to mitochondrial stress conditions. In summary, proteomic analyses provide a new perspective on Rb/RB1 mutation, highlighting the importance of pRb for mitochondrial function and suggesting vulnerabilities for treatment. PMID:26314710

  5. Altered expression of cell cycle regulators Cyclin D1, p14, p16, CDK4 and Rb in nodular melanomas.

    PubMed

    Bachmann, Ingeborg M; Straume, Oddbjørn; Akslen, Lars A

    2004-12-01

    Cell cycle regulating proteins are important in tumour development. To investigate whether alterations in Cyclin D1, p14, CDK4 and Rb are associated with tumour cell proliferation, tumour progression and patient survival in malignant melanoma, we examined 202 vertical growth phase tumours and 68 corresponding metastases for expression of Cyclin D1, p14, CDK4 and Rb, and compared the results with Ki-67 expression, p16 and p53 expression, clinico-pathological variables, and survival data. Nuclear staining of Cyclin D1 was strong in 35% of cases, and correlated with high levels of Rb (p=0.05), but not with survival or other markers tested. Strong staining of p14 was found in 63% of nodular melanomas and was associated with strong p53 expression (p=0.014), and with high levels of CDK4 (p<0.0001). Low p14 expression was associated with increased tumour thickness (p=0.008) and increasing level of invasion (p=0.020). Strong nuclear staining for CDK4 was found in 81% of cases and was associated with tumour thickness below the median value of 3.7 mm and improved survival (log-rank test, p=0.024). Further, 56% of the tumours showed strong nuclear staining for Rb, and these cases were significantly associated with absent/low levels of p16 staining (p=0.030), high levels of p14 (p=0.010), as well as high Ki-67 expression (p=0.005). Our results seem to confirm that the p16-Rb pathway plays an important role in tumour progression and prognosis in vertical growth phase melanomas, whereas alterations in the p14-p53 pathway might be less important.

  6. One-dimensional decavanadate chains in the crystal structure of Rb4[Na(H2O)6][HV10O28]·4H2O.

    PubMed

    Yakubovich, Olga V; Steele, Ian M; Yakovleva, Ekaterina V; Dimitrova, Olga V

    2015-06-01

    New decavanadate minerals, the products of the leaching or metasomatic processes, are possible in nature via Na/Rb removal/inclusion reactions. As part of our search for novel vanadate phases with varying functionalities, a new phase, tetrarubidium hexaaquasodium hydrogen decavanadate tetrahydrate, Rb4[Na(H2O)6][HV10O28]·4H2O, has been synthesized by the hydrothermal technique at 553 K. Ten shared edges of V-centred octahedra form monoprotonated decavanadate cages, which are joined together via hydrogen bonds into one-dimensional chains parallel to the [101] direction. Within these chains, H atoms are sandwiched between neighbouring polyanions. Na and Rb atoms and H2O molecules occupy interstices flanked by the anionic chains providing additional crosslinking in the structure. This compound is the second decavanadate with P2/n symmetry. Structural relationships among protonated and deprotonated decavanadates with inorganic cations, including minerals of the pascoite group, are discussed.

  7. Light and buffer-gas frequency shifts in the Rb-85 maser frequency standard.

    NASA Technical Reports Server (NTRS)

    Stern, W. A.; Novick, R.

    1972-01-01

    The effect of buffer gas and pumping light on the output frequency of the Rb-85 maser is discussed. In contrast to a primary standard, these frequency shifts can be used to advantage when it is necessary to operate the maser at a frequency which differs from the ground-state hyperfine frequency by a few kilohertz. Using appropriate mixtures of buffer gas and carefully shaped lamp spectral profiles, it is also possible to operate the maser exactly at the ground-state hyperfine frequency. It is pointed out that the short-term phase stability of the maser is not impaired by these shifts.

  8. Joint Raman spectroscopic and quantum chemical analysis of the vibrational features of Cs2RuO4

    PubMed Central

    Naji, M; Di Lemma, F; Kovács, A; Beneš, O; Manara, D; Colle, J-Y; Pagliosa, G; Raison, P; Konings, R J M

    2015-01-01

    The Raman spectroscopic characterization of the orthorhombic phase of Cs2RuO4 was carried out by means of group theory and quantum chemical analysis. Multiple models based on ruthenate (VI+) tetrahedra were tested, and characterization of all the active Raman modes was achieved. A comparison of Raman spectra of Cs2RuO4, Cs2MoO4, and Cs2WO4 was also performed. Raman laser heating induced a phase transition from an ordered to a disordered structure. The temperature-phase transition was calculated from the anti-Stokes/Stokes ratio and compared with the ones measured at macroscopic scale. The phase transition is connected with tilting and/or rotations of RuO4 tetrahedra, which lead to a disorder at the RuO4 sites. © 2015 The Authors. Journal of Raman Spectroscopy published by John Wiley & Sons Ltd. PMID:26494941

  9. The "Seven Cs" for Employee Retention.

    ERIC Educational Resources Information Center

    Taguchi, Sherrie Gong

    2001-01-01

    Defines the "Seven Cs," traditional yet effective business fundamentals used to engage employees. Discusses how many companies are leveraging the basics of good employee relations in order to inspire staff productivity and loyalty. (GCP)

  10. Unlike morphine the endogenous enkephalins protected by RB101 are unable to establish a conditioned place preference in mice.

    PubMed

    Noble, F; Fournié-Zaluski, M C; Roques, B P

    1993-01-12

    The mixed inhibitor prodrug, RB101, was used to study the motivational properties of the endogenous opioid peptides, the enkephalins. In the conditioned place preference test, which is commonly used to investigate the reinforcing properties of drugs, mice alternately treated with morphine (3 mg/kg i.p.) on the initially non-preferred compartment and with saline on the preferred one, for four place pairings, spent more time in the drug-associated compartment. This shift in place preference after the conditioning procedure was not found after treatment with RB101 (80 mg/kg i.p.). Administration of naloxone (1 mg/kg s.c.) after the conditioning phase increased the preference for the drug-associated compartment of mice treated with 6 mg/kg (i.p.) of morphine. This illustrates the negative motivational properties of morphine withdrawal or the establishment of psychic dependence on the drug. In contrast, no modification of preference was observed after injection of naloxone in animals treated with a high dose of RB101 (160 mg/kg i.p.). The failure to establish conditioned place preference by inhibiting endogenous enkephalin metabolism, and the lack of development of psychic dependence after RB101 administration demonstrate for the first time the interest of mixed inhibitors of enkephalin-degrading enzymes as potent new non-addictive analgesics.

  11. Magnetic properties of quasi two-dimensional antiferromagnet Rb2MnCl4 with XXZ interaction anisotropy

    NASA Astrophysics Data System (ADS)

    Radošević, S.; Pavkov-Hrvojević, M.; Pantić, M.; Rutonjski, M.; Kapor, D.; Krinjar, M. Å.

    2009-04-01

    Two-dimensional Heisenberg antiferromagnet with XXZ spin anisotropy Rb2MnCl4, is studied using the method of double-time-temperature Green’s functions (GF) with arbitrary spin S (in particular case S = 5/2) within random-phase approximation (RPA) and Callen approximation (CA). Exchange field and anisotropy field are extracted from experimental data on the magnon frequencies in Rb2MnCl4. They are used to calculate dispersion relation and the sublattice magnetization in the self-consistent way in the whole temperature range. The results obtained using RPA and CA are compared. The existence of a finite temperature transition is investigated, probably describing the low-temperature critical behavior experimentally observed in many layered compounds. The Néel temperature TN is calculated employing both methods. Calculated transition temperature within RPA agrees rather well with the measured values for the quasi two-dimensional antiferromagnet Rb2MnCl4 in zero magnetic field, while CA overestimates the critical temperature. The dependence of critical temperature on parameter of spin anisotropy η is also analysed. The good agreement found between our theoretical results and the experimental data relative to the real compound Rb2MnCl4 shows that the inclusion of this type of spin anisotropy with quantum effect properly taken into account, provides a quantitative description and explanation of the experimental data.

  12. PyCS : Python Curve Shifting

    NASA Astrophysics Data System (ADS)

    Tewes, Malte

    2015-09-01

    PyCS is a software toolbox to estimate time delays between multiple images of strongly lensed quasars, from resolved light curves such as obtained by the COSMOGRAIL monitoring program. The pycs package defines a collection of classes and high level functions, that you can script in a flexible way. PyCS makes it easy to compare different point estimators (including your own) without much code integration. The package heavily depends on numpy, scipy, and matplotlib.

  13. 135Cs activity and 135Cs/137Cs atom ratio in environmental samples before and after the Fukushima Daiichi Nuclear Power Plant accident

    NASA Astrophysics Data System (ADS)

    Yang, Guosheng; Tazoe, Hirofumi; Yamada, Masatoshi

    2016-04-01

    135Cs/137Cs is a potential tracer for radiocesium source identification. However, due to the challenge to measure 135Cs, there were no 135Cs data available for Japanese environmental samples before the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. It was only 3 years after the accident that limited 135Cs values could be measured in heavily contaminated environmental samples. In the present study, activities of 134Cs, 135Cs, and 137Cs, along with their ratios in 67 soil and plant samples heavily and lightly contaminated by the FDNPP accident were measured by combining γ spectrometry with ICP-MS/MS. The arithmetic means of the 134Cs/137Cs activity ratio (1.033 ± 0.006) and 135Cs/137Cs atom ratio (0.334 ± 0.005) (decay corrected to March 11, 2011), from old leaves of plants collected immediately after the FDNPP accident, were confirmed to represent the FDNPP derived radiocesium signature. Subsequently, for the first time, trace 135Cs amounts before the FDNPP accident were deduced according to the contribution of global and FDNPP accident-derived fallout. Apart from two soil samples with a tiny global fallout contribution, contributions of global fallout radiocesium in other soil samples were observed to be 0.338%–52.6%. The obtained 135Cs/137Cs database will be useful for its application as a geochemical tracer in the future.

  14. 135Cs activity and 135Cs/137Cs atom ratio in environmental samples before and after the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Yang, Guosheng; Tazoe, Hirofumi; Yamada, Masatoshi

    2016-04-07

    (135)Cs/(137)Cs is a potential tracer for radiocesium source identification. However, due to the challenge to measure (135)Cs, there were no (135)Cs data available for Japanese environmental samples before the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. It was only 3 years after the accident that limited (135)Cs values could be measured in heavily contaminated environmental samples. In the present study, activities of (134)Cs, (135)Cs, and (137)Cs, along with their ratios in 67 soil and plant samples heavily and lightly contaminated by the FDNPP accident were measured by combining γ spectrometry with ICP-MS/MS. The arithmetic means of the (134)Cs/(137)Cs activity ratio (1.033 ± 0.006) and (135)Cs/(137)Cs atom ratio (0.334 ± 0.005) (decay corrected to March 11, 2011), from old leaves of plants collected immediately after the FDNPP accident, were confirmed to represent the FDNPP derived radiocesium signature. Subsequently, for the first time, trace (135)Cs amounts before the FDNPP accident were deduced according to the contribution of global and FDNPP accident-derived fallout. Apart from two soil samples with a tiny global fallout contribution, contributions of global fallout radiocesium in other soil samples were observed to be 0.338%-52.6%. The obtained (135)Cs/(137)Cs database will be useful for its application as a geochemical tracer in the future.

  15. 135Cs activity and 135Cs/137Cs atom ratio in environmental samples before and after the Fukushima Daiichi Nuclear Power Plant accident

    PubMed Central

    Yang, Guosheng; Tazoe, Hirofumi; Yamada, Masatoshi

    2016-01-01

    135Cs/137Cs is a potential tracer for radiocesium source identification. However, due to the challenge to measure 135Cs, there were no 135Cs data available for Japanese environmental samples before the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. It was only 3 years after the accident that limited 135Cs values could be measured in heavily contaminated environmental samples. In the present study, activities of 134Cs, 135Cs, and 137Cs, along with their ratios in 67 soil and plant samples heavily and lightly contaminated by the FDNPP accident were measured by combining γ spectrometry with ICP-MS/MS. The arithmetic means of the 134Cs/137Cs activity ratio (1.033 ± 0.006) and 135Cs/137Cs atom ratio (0.334 ± 0.005) (decay corrected to March 11, 2011), from old leaves of plants collected immediately after the FDNPP accident, were confirmed to represent the FDNPP derived radiocesium signature. Subsequently, for the first time, trace 135Cs amounts before the FDNPP accident were deduced according to the contribution of global and FDNPP accident-derived fallout. Apart from two soil samples with a tiny global fallout contribution, contributions of global fallout radiocesium in other soil samples were observed to be 0.338%–52.6%. The obtained 135Cs/137Cs database will be useful for its application as a geochemical tracer in the future. PMID:27052481

  16. Ionic ASi2N3 (A=Li, Na, K and Rb) stabilized by the covalent Si-N bonding: First-principles calculations

    NASA Astrophysics Data System (ADS)

    Zhang, Huijun; Ren, Jiadong; Wu, Lailei; Zhang, Jingwu

    2017-01-01

    The structural, elastic and electronic properties of LiSi2N3 and its substitutions by Na, K and Rb were investigated through first-principles computations. The expansion of lattice parameters of ASi2N3 from Li, Na, K to Rb is found to be determined by the bond angle of Si-N1-Si, which suggests a possible way to improve the lithium ionic conductivity by substitutions. ASi2N3 (A=Li, Na, K and Rb) shows the similar elastic behaviors, while the electronic band gap gradually decreases from 5.1 to 3.4 eV from LiSi2N3 to RbSi2N3. Interestingly, the analysis of electronic structure, crystal orbital Hamiltonian populations and Bader charges shows that the covalence of Si-N bonding is critical for the stability of ASi2N3 phase. Among ASi2N3 phases, there is a relatively high ionicity in NaSi2N3; the Si-N bond strength in [Si2N3]- net for KSi2N3 and RbSi2N3 is comparable to LiSi2N3, but stronger than NaSi2N3.

  17. Local microscopic properties and annealing effect of Rb0.85Fe1.9Se2 single crystals

    NASA Astrophysics Data System (ADS)

    Szymański, K.; Olszewski, W.; Satuła, D.; Matwiejczyk, A.; Gawryluk, D. J.; Krztoń-Maziopa, A.; Puźniak, R.; Wiśniewski, A.

    2017-04-01

    Investigation of mesoscopically phase-separated Rb0.85Fe1.9Se2 single crystals has been performed and two iron sites: nonmagnetic and magnetic ones, were observed by Mössbauer spectroscopy. The softening of the nonmagnetic one, having clearly more soft dynamics, was found to be gained further by the annealing of the single crystals at phase separation temperature, T p, leading to the reduction of size of initially separated domains and their more homogenous distribution in the tetragonal matrix of the studied sample. The magnetic Fe sites of Rb0.85Fe1.9Se2 show strong magnetic texture, indicating the perpendicular to the ab-plane orientation of the iron magnetic moments. It was found that the annealing at T p causes a systematic decrease of the isomer shift of the doublet by 0.02(1) mm s‑1.

  18. Cs(3)Sm(7)Se(12).

    PubMed

    Schneck, Christof; Elbe, Andreas; Schurz, Christian M; Schleid, Thomas

    2012-01-01

    The title compound, tricaesium hepta-samarium(III) dodeca-selenide, is setting a new starting point for realization of the channel structure of the Cs(3)M(7)Se(12) series, now with M = Sm, Gd-Er. This Cs(3)Y(7)Se(12)-type arrangement is structurally based on the Z-type sesquiselenides M(2)Se(3) adopting the Sc(2)S(3) structure. Thus, the structural set-up of Cs(3)Sm(7)Se(12) consists of edge- and vertex-connected [SmSe(6)](9-) octa-hedra [d(Ø)(Sm(3+) - Se(2-)) = 2.931 Å], forming a rock-salt-related network [Sm(7)Se(12)](3-) with channels along [001] that are apt to take up monovalent cations (here Cs(+)) with coordination numbers of 7 + 1 for one and of 6 for the second cation. The latter cation has a trigonal-prismatic coordination and shows half-occupancy, resulting in an impossible short distance [2.394 (4) Å] between symmetrically coupled Cs(+) cations of the same kind. While one Sm atom occupies Wyckoff position 2b with site symmetry ..2/m, all other 11 crystallographically different atoms (namely 2 × Cs, 3 × Sm and 6 × Se) are located at Wyckoff positions 4g with site symmetry ..m.

  19. Fast CsI-phoswich detector

    DOEpatents

    Langenbrunner, J.R.

    1996-05-07

    An improved phoswich radiation detector used pure CsI crystal and a fast plastic scintillator and a single photomultiplier tube. The plastic is arranged to receive incident radiation, and that which passed through then strikes the CsI crystal. Scintillation light from both the plastic and CsI crystal are applied to the photomultiplier tube, with the light from the plastic passing through the crystal without absorption therein. Electronics are provided for analyzing the output of the photomultiplier tube to discriminate responses due to the plastic and the CsI crystal, through short gate and long gate integration, to produce results which are indicative of the characteristics of the different types of incident radiation, even in the presence of large amounts of radiation. The phoswich detector has excellent timing resolution. The scintillators of the CsI- phoswich were chosen for their fast risetimes, of about 3 ns for NE102A, and 30 ns for the pure CsI. 5 figs.

  20. Fast CsI-phoswich detector

    DOEpatents

    Langenbrunner, James R.

    1996-01-01

    An improved phoswich radiation detector used pure CsI crystal and a fast plastic scintillator and a single photomultiplier tube. The plastic is arranged to receive incident radiation, and that which passed through then strikes the CsI crystal. Scintillation light from both the plastic and CsI crystal are applied to the photomultiplier tube, with the light from the plastic passing through the crystal without absorption therein. Electronics are provided for analyzing the output of the photomultiplier tube to discriminate responses due to the plastic and the CsI crystal, through short gate and long gate integration, to produce results which are indicative of the characteristics of the different types of incident radiation, even in the presence of large amounts of radiation. The phoswich detector has excellent timing resolution. The scintillators of the CsI- phoswich were chosen for their fast risetimes, of about 3 ns for NE102A, and 30 ns for the pure CsI.

  1. Distribution of radioactive cesium ((134)Cs plus (137)Cs) in rice fractions during polishing and cooking.

    PubMed

    Hachinohe, Mayumi; Okunishi, Tomoya; Hagiwara, Shoji; Todoriki, Setsuko; Kawamoto, Shinichi; Hamamatsu, Shioka

    2015-03-01

    We investigated the distribution of cesium-134 ((134)Cs) and cesium-137 ((137)Cs) during polishing and cooking of rice to obtain their processing factors (Pf) and food processing retention factors (Fr) to make the information available for an adequate understanding of radioactive Cs dynamics. Polishing brown rice resulted in a decreased radioactive Cs concentration of the polished rice, but the bran and germ (outer layers) exhibited higher concentrations than brown rice. The Pf values for 100% polished rice and outer layers ranged from 0.47 to 0.48 and 6.5 to 7.8, respectively. The Fr values for 100% polished rice and outer layers were 0.43 and 0.58 to 0.60, respectively. The distribution of radioactive Cs in polished rice and outer layers was estimated at approximately 40 and 60%, respectively. On the other hand, cooked rice showed significantly lower levels of radioactive Cs than polished rice, and transfer of radioactive Cs into wash water was observed. The Pf and Fr values for cooked rice were 0.28 and 0.65 to 0.66, respectively. From these results, we can calculate that if the radioactive Cs concentration in brown rice is 100 Bq/kg, the concentrations of Cs in polished rice and cooked rice will be 47 to 48 Bq/kg and 13 Bq/kg, respectively.

  2. Scattering lengths in isotopologues of the RbYb system

    NASA Astrophysics Data System (ADS)

    Borkowski, Mateusz; Żuchowski, Piotr S.; Ciuryło, Roman; Julienne, Paul S.; Kędziera, Dariusz; Mentel, Łukasz; Tecmer, Paweł; Münchow, Frank; Bruni, Cristian; Görlitz, Axel

    2013-11-01

    We model the binding energies of rovibrational levels of the RbYb molecule using experimental data from two-color photoassociation spectroscopy in mixtures of ultracold 87Rb with various Yb isotopes. The model uses a theoretical potential based on state-of-the-art ab initio potentials, further improved by least-squares fitting to the experimental data. We have fixed the number of bound states supported by the potential curve, so that the model is mass scaled, that is, it accurately describes the bound-state energies for all measured isotopic combinations. Such a model enables an accurate prediction of the s-wave scattering lengths of all isotopic combinations of the RbYb system. The reduced mass range is broad enough to cover the full scattering lengths range from -∞ to +∞. For example, the 87Rb174Yb system is characterized by a large positive scattering length of +880(120) a.u., while 87Rb173Yb has a=-626(88) a.u. On the other hand 87Rb170Yb has a very small scattering length of -11.5(2.5) a.u. confirmed by the pair's extremely low thermalization rate. For isotopic combinations including 85Rb the variation of the interspecies scattering lengths is much smoother ranging from +39.0(1.6) a.u. for 85Rb176Yb to +230(12) a.u. in the case of 85Rb168Yb. Hyperfine corrections to these scattering lengths are also given. We further complement the fitted potential with interaction parameters calculated from alternative methods. The recommended value of the van der Waals coefficient is C6=2837(13) a.u. agrees with but is more precise than the current state-of-the-art theoretical predictions [M. S. Safronova, S. G. Porsev, and C. W. Clark, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.109.230802 109, 230802 (2012)].

  3. {sup 87}Rb D{sub 1} isoclinic point

    SciTech Connect

    Wells, N. P.; Camparo, J. C.

    2010-12-15

    In the research presented here, we reconsider the problem of obtaining stable resonant features in linear absorption spectroscopy, which has application to ultraminiature atomic physics where sub-Doppler spectroscopic techniques are not always optimal. In particular, we consider the applicability of isoclinic points for precision atomic spectroscopy. These are defined as ''[a] wavelength, wave number, or frequency at which the first derivative of an absorption spectrum of a sample does not change upon a chemical reaction or physical change of the sample,'' and we demonstrate the existence of isoclinic points in the D{sub 1} spectra of I=3/2 alkali-metal isotopes, where I is the nuclear spin. We then consider the D{sub 1} isoclinic point of {sup 87}Rb in detail, showing that a slight {sup 85}Rb contamination in real {sup 87}Rb samples should have no significant effect on the frequency stability of the isoclinic point and that optical pumping by a linearly polarized laser should also not affect the isoclinic point's stability (i.e., the isoclinic point is insensitive to laser intensity). Finally, we perform an experiment demonstrating that the {sup 87}Rb D{sub 1} isoclinic point has a temperature shift more than an order of magnitude smaller than that of the most isolated transition in the {sup 87}Rb D{sub 1} spectrum.

  4. Expression of retinoblastoma gene product (pRb) in mantle cell lymphomas. Correlation with cyclin D1 (PRAD1/CCND1) mRNA levels and proliferative activity.

    PubMed Central

    Jares, P.; Campo, E.; Pinyol, M.; Bosch, F.; Miquel, R.; Fernandez, P. L.; Sanchez-Beato, M.; Soler, F.; Perez-Losada, A.; Nayach, I.; Mallofré, C.; Piris, M. A.; Montserrat, E.; Cardesa, A.

    1996-01-01

    Mantle cell lymphomas (MCLs) are molecularly characterized by bcl-1 rearrangement and constant cyclin D1 (PRAD-1/CCND1) gene overexpression. Cyclin D1 is a G1 cyclin that participates in the control of the cell cycle progression by interacting with the retinoblastoma gene product (pRb). Inactivation of the Rb tumor suppressor gene has been implicated in the development of different types of human tumors including some high grade non-Hodgkin's lymphomas. To determine the role of the retinoblastoma gene in the pathogenesis of MCLs and its possible interaction with cyclin D1, pRb expression was examined in 23 MCLs including 17 typical and 6 blastic variants by immunohistochemistry and Western blot. Rb gene structure was studied in 13 cases by Southern blot. Cytogenetic analysis was performed in 5 cases. The results were compared with the cyclin D1 mRNA levels examined by Northern analysis, and the proliferative activity of the tumors was measured by Ki-67 growth fraction and flow cytometry. pRb was expressed in all MCLs. The expression varied from case to case (mean, 14.1% of positive cells; range, 1.3 to 42%) with a significant correlation with the proliferative activity of the tumors (mitotic index r = 0.85; Ki-67 r = 0.7; S phase = 0.73). Blastic variants showed higher numbers of pRb-positive cells (mean, 29%) than the typical cases (10%; P < 0.005) by immunohistochemistry and, concordantly, higher levels of expression by Western blot. In addition, the blastic cases also had an increased expression of the phosphorylated protein. No alterations in Rb gene structure were observed by Southern blot analysis. Cyclin D1 mRNA levels were independent of pRb expression and the proliferative activity of the tumors. These findings suggest that pRb in MCLs is normally regulated in relation to the proliferative activity of the tumors. Cyclin D1 overexpression may play a role in the maintenance of cell proliferation by overcoming the suppressive growth control of pRb. Images

  5. Correlation between transcript abundance of the RB gene and the level of the RB-mediated late blight resistance in potato.

    PubMed

    Kramer, Lara C; Choudoir, Mallory J; Wielgus, Susan M; Bhaskar, Pudota B; Jiang, Jiming

    2009-04-01

    Numerous disease-resistance genes have been cloned and characterized in various plant species. Only a few of these reported genes were transcriptionally induced or had enhanced transcription upon pathogen infection. Here, we report that transcription of the RB gene, which was cloned from the wild potato species Solanum bulbocastanum and confers resistance to potato late blight, was significantly increased after inoculation with the late blight pathogen Phytophthora infestans. Different RB transgenic lines showed different levels of resistance, which were correlated with the amounts of RB transcript in the transgenic plants. Different transgenic lines also showed different patterns of RB transcription 1, 3, and 5 days after P. infestans inoculation. Interestingly, the RB gene showed a higher basal level of transcription and a more dramatic transcriptional increase upon inoculation in S. bulbocastanum than in all potato transgenic lines. Our results revealed a predictive correlation between transcript abundance of the RB gene and the level of the RB-mediated late blight resistance. High level of resistance was associated with a combination of rapid RB transcript induction immediately after pathogen infection followed by the steady production of RB transcript. Thus, the transcription level of the RB gene provides a valuable marker for selecting and deploying RB-containing potato lines for late blight control.

  6. Rb-Raf-1 interaction disruptor RRD-251 induces apoptosis in metastatic melanoma cells and synergizes with dacarbazine.

    PubMed

    Singh, Sandeep; Davis, Rebecca; Alamanda, Vignesh; Pireddu, Roberta; Pernazza, Daniel; Sebti, Said; Lawrence, Nicholas; Chellappan, Srikumar

    2010-12-01

    Metastatic melanoma is an aggressive cancer with very low response rate against conventional chemotherapeutic agents such as dacarbazine (DTIC). Inhibitor of Rb-Raf-1 interaction RRD-251 was tested against the melanoma cell lines SK-MEL-28, SK-MEL-5, and SK-MEL-2. RRD-251 was found to be a potent inhibitor of melanoma cell proliferation, irrespective of V600E B-Raf mutation status of the cell lines. In a SK-MEL-28 xenograft experiment, RRD-251 exerted a significant suppression of tumor growth compared with vehicle (P = 0.003). Similar to in vitro effects, tumors from RRD-251-treated animals showed decreased Rb-Raf-1 interaction in vivo. Growth suppressive effects of RRD-251 were associated with induction of apoptosis as well as a G(1) arrest, with an accompanying decrease in S-phase cells. RRD-251 inhibited Rb phosphorylation and downregulated E2F1 protein levels in these cells. Real-time PCR analysis showed that RRD-251 caused downregulation of cell-cycle regulatory genes thymidylate synthase (TS) and cdc6 as well as the antiapoptotic gene Mcl-1. Combinatorial treatment of RRD-251 and DTIC resulted in a significantly higher apoptosis in DTIC resistant cell lines SK-MEL-28 and SK-MEL-5, as revealed by increased caspase-3 activity and PARP cleavage. Because aberrant Rb/E2F pathway is associated with melanoma progression and resistance to apoptosis, these results suggest that the Rb-Raf-1 inhibitor could be an effective agent for melanoma treatment, either alone or in combination with DTIC.

  7. Deregulation of the pRb-E2F4 axis alters epidermal homeostasis and favors tumor development

    PubMed Central

    Costa, Clotilde; Santos, Mirentxu; Martínez-Fernández, Mónica; Lorz, Corina; Lázaro, Sara; Paramio, Jesús M.

    2016-01-01

    E2F/RB activity is altered in most human tumors. The retinoblastoma family of proteins plays a key role in regulating the progression of the cell cycle from the G1 to S phases. This is achieved through negative regulation of E2F transcription factors, important positive regulators of cell cycle entry. E2F family members are divided into two groups: activators (E2F1-E2F3a) and repressors (E2F3b-E2F8). E2F4 accounts for a large part of the E2F activity and is a main E2F repressor member in vivo. Perturbations in the balance from quiescence towards proliferation contribute to increased mitotic gene expression levels frequently observed in cancer. We have previously reported that combined Rb1-Rbl1 or Rb1-E2f1 ablation in epidermis produces important alterations in epidermal proliferation and differentiation, leading to tumor development. However, the possible roles of E2F4 in this context are still to be determined. Here, we show the absence of any discernible phenotype in the skin of mice lacking of E2f4. In contrast, the inducible loss of Rb1 in the epidermis of E2F4-null mice produced multiple skin abnormalities including altered differentiation and proliferation, spontaneous wounds, carcinoma in situ development and stem cell perturbations. All these phenotypic alterations are associated with extensive gene expression changes, the induction of c-myc and the Akt activation. Moreover the whole transcriptome analyses in comparison with previous models generated also revealed extensive changes in multiple repressive complexes and in transcription factor activity. These results point to E2F4 as a master regulator in multiple steps of epidermal homeostasis in Rb1 absence. PMID:27708231

  8. The Estherville mesosiderite: U-Pb, Rb-Sr, and Sm-Nd isotopic study of a polymict breccia

    SciTech Connect

    Brouxel, M.; Tatsumoto, M. )

    1991-04-01

    A systematic U-Pb, Sm-Nd, and Rb-Sr isotopic study shows that the Estherville mesosiderite was formed between 4.56 and 4.43 Ga. Observed isotopic heterogeneity is in agreement with multiple generations of meteoritic impacts described in other mesosiderites. At least part of the Estherville silicate fraction was formed early in solar system history as indicated by the Pb-Pb (4555 {plus minus} 35 Ma), U-Pb (4560 {plus minus} 31 Ma), Rb-Sr (4542 {plus minus} 203 Ma), and Sm-Nd (4533 {plus minus} 94 Ma) ages. Mesosiderites therefore present not only petrological but also geochronological similarities with eucrites. The Pb isotopic composition of the metal phase plots on the same isochron as the silicates, indicating formation and subsequent mixing with silicates early in the history of the solar system. This is consistent with previous observations indicating that iron was reduced during the silicate-magmatic stage, most likely a consequence of mixing with metal. In addition to these more-ancient portions of the Estherville breccia, other parts were formed later as suggested by the Pb-Pb (4422 {plus minus} 50 Ma) and U-Pb (4437 {plus minus} 11 Ma) ages observed in a second group of leaches and residues. This age is similar to some cumulate eucrite ages and may represent the formation of a second mesosiderite component. The Sm-Nd and the Rb-Sr ages obtained on Estherville show large errors that may be a consequence of the mixing between the 4.56 and 4.43 Ga endmembers. Estherville, like most mesosiderites, was affected by a major heating event around 3.5-3.7 Ga as shown by the Ar-Ar ages. This heating event partially disturbed the Rb-Sr isotopic system (Rb-Sr metamorphic ages range between 3.81 and 4.08 Ga).

  9. Stability of (Cs, K)Al4Be5B11O28 (londonite) at high pressure and high temperature: a potential neutron absorber material

    NASA Astrophysics Data System (ADS)

    Gatta, G. Diego; Vignola, Pietro; Lee, Yongjae

    2011-06-01

    The stability and the thermo-elastic behaviour of a natural londonite [^{{1a}} ( {Cs_{{0.36}} K_{{0.34}} Rb_{{0.15}} Ca_{{0.04}} Na_{{0.02}} } )_{Σ 0.91}{}^{{4e}} ( {Al_{{3.82}} Li_{{0.05}} Fe_{{0.02}} } )_{{Σ 3.89}}{}^{{4e}} ( {Be_{{3.82}} B_{{0.18}} } )_{{Σ 4}}{}^{{12h}} ( {B_{{10.97}} Be1 Si_{{0.01}} } )_{{Σ 11.98}} O_{{28}}] has been investigated up to 1,273(3) K (at 0.0001 GPa) and up to 4.85(5) GPa (at 298 K) by means of in situ X-ray powder diffraction. Up to 973 K, no evidence of phase transition or anomalous thermo-elastic behaviour was observed. At T > 973 K, londonite shows the first evidence of an irreversible structure destabilisation. The volume thermal expansion coefficient between 298 and 973 K is α0 = 2.38(6)·10-5 K-1. Londonite shows an elastic behaviour up to 4.85 GPa. No phase transition has been observed within the pressure range investigated. P- V data fitted with a second-order Birch-Murnaghan equation of state give V 0 = 389.1(1)Å3 and K T0 = 280(12) GPa. On the basis of the good thermo-elastic behaviour, substantiated by the significantly low compressibility, the modest thermal expansion up to 1,000 K and the significantly high amount of boron (B2O3 50wt%), londonite-type materials could be considered as potential inorganic host for 10B in composite neutron-absorbing materials.

  10. Plant uptake of cations under nutrient limitation: An environmental tracer study using Ca/Sr and K/Rb ratios

    NASA Astrophysics Data System (ADS)

    Shi, Z.; Keller, C. K.; Stacks, D.; Grant, M.; Harsh, J. B.; Letourneau, M.; Gill, R. A.; Balogh-Brunstad, Z.; Thomashow, L.; Dohnalkova, A.

    2012-12-01

    Vascular plant growth builds soils and ecosystem nutrient capital by sequestering and partitioning atmospheric CO2 into organic matter and continental runoff and driving terrestrial water and energy balances. Plant root-system functions, e.g. nutrient mobilization and uptake, are altered by environmental stress. However, the stress-response relationships are poorly understood. Chemical tracers have potential for assessing contributions of nutrients from various nutrient pools. Our objective is to quantitatively study how varying degrees of nutrient limitation (and corresponding needs to extract base cations from mineral sources) influence Ca and K uptake functions in a plant-root-mineral system. We are studying plant-driven mineral weathering in column experiments with red pine (Pinus resinosa) seedlings. The columns contain quartz sand amended with anorthite and biotite that constitute the sole mineral sources of Ca and K. These minerals also contain known amounts of Sr and Rb, which exhibit chemical behavior similar to Ca and K, respectively. The solution source of Ca and K was varied by adding 0% (no dissolved Ca and K), 10%, 30%, or 100% of a full strength Ca and K nutrient solution through irrigation water in which both Sr and Rb concentrations were negligible. Selected columns were destructively sampled at 3, 6 and 9 months to harvest biomass and measure plant uptake of cations. We used Ca/Sr and K/Rb ratio results to estimate the contributions of Ca and K from mineral and solution sources. For the 0% nutrient treatment, the Ca/Sr and K/Rb ratios in total biomass at 3 months, compared with those in the mineral phases, suggested preferential uptake of Ca and K over Sr and Rb, respectively, and allowed us to determine uptake discrimination factors for both cations. The K/Rb ratios in total biomass increased with greater K availability in the solution source, as expected, but Ca/Sr ratios did not show any dependence on Ca availability in the solution source

  11. Potential role of CS2 photooxidation in tropospheric sulfur chemistry

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Chameides, W. L.; Ravishankara, A. R.

    1981-01-01

    Absorption cross section measurements and model calculations indicate that CS2 photooxidation may be an important tropospheric sink for the CS2, giving a lifetime on the order of a week or two. If background CS2 levels are 10-20 pptv, then CS2 photooxidation may be an important global source of OCS as well.

  12. Optical transitions of Er3+ ions in RbMgF3 and RbMgF3: Mn

    NASA Astrophysics Data System (ADS)

    Shinn, M. D.; Windscheif, J. C.; Sardar, D. K.; Sibley, W. A.

    1982-09-01

    Optical absorption, emission, and excitation spectra, as well as lifetime values, are presented for Er3+ ions in RbMgF3. Previous workers have demonstrated that Er3+ ions can reside in a number of different site symmetries in crystalline hosts such as CaF2 and CdF2. The numerous sites in this type lattice are most likely due to compensating fluorine interstitials which are necessarily present for charge compensation. In a unit cell of RbMgF3 there are two nonequivalent Mg2+ sites with C3v symmetry. Evidence is presented in this paper that Er3+ ions in RbMgF3 substitute for Mg2+ ions in both types of sites. The charge compensation is not local, which leaves the symmetry of the Er3+ sites unchanged. Absorption data for Er3+-ion transitions in both sites are shown. Emission from Er3+ ions is observed from one type of site in RbMgF3 and from both types of sites in RbMgF3: Mn. Lifetime values for the 4S32 and 4F92 transitions are shorter than those normally measured in fluoride host lattices, and the emissions are quenched above 200 K. Energy migration among Er3+ ions and subsequent energy transfer to Mn2+-ion impurities are responsible for the steady-state and transient-emission behavior.

  13. Ab initio study of reactive collisions between Rb((2)S) or Rb((2)P) and OH(-)((1)Σ(+)).

    PubMed

    Kas, Milaim; Loreau, Jérôme; Liévin, Jacques; Vaeck, Nathalie

    2016-05-28

    A theoretical rate constant for the associative detachment reaction Rb((2)S) + OH(-)((1)Σ(+)) → RbOH((1)Σ(+)) + e(-) of 4 × 10(-10) cm(3) s(-1) at 300 K has been calculated. This result agrees with the experimental rate constant of 2-1 (+2)×10(-10)cm(3)s(-1) obtained by Deiglmayr et al. [Phys. Rev. A 86, 043438 (2012)] for a temperature between 200 K and 600 K. A Langevin-based dynamics which depends on the crossing point between the anion (RbOH(-)) and neutral (RbOH) potential energy surfaces has been used. The calculations were performed using the ECP28MDF effective core potential to describe the rubidium atom at the CCSD(T) level of theory and extended basis sets. The effect of ECPs and basis set on the height of the crossing point, and hence the rate constant, has been investigated. The temperature dependence of the latter is also discussed. Preliminary work on the potential energy surface for the excited reaction channel Rb((2)P) + OH(-)((1)Σ(+)) calculated at the CASSCF-icMRCI level of theory is presented. We qualitatively discuss the charge transfer and associative detachment reactions arising from this excited entrance channel.

  14. Geometrical and electronic properties of neutral and charged cesium clusters Cs(n) (n=2-10): a theoretical study.

    PubMed

    Ali Basu, M; Maity, D K; Das, D; Mukherjee, T

    2006-01-14

    We have investigated the structure and electronic properties of cesium clusters following all electron ab initio theoretical methods based on configuration interaction, second-order Moller-Plesset (MP2) perturbation theory, and density-functional theory. Becke's three-parameter nonlocal hybrid exchange-correlation functional (B3LYP) is found to perform best on the present systems with a split valence 3-21G basis function. We have calculated the optimized geometries of neutral and singly charged cesium clusters having up to ten atoms, their binding energy per atom, ionization potentials (IPs), and adiabatic electron affinity (EA). Geometry optimizations for all the clusters are carried out without imposing any symmetry restriction. The neutral clusters having up to six atoms prefer planar structure and three-dimensional structure is preferred only when the number of atoms in a cluster is more than six. There is a good agreement between the present theoretical and reported experimental IP values for the neutral clusters with cluster size nCs clusters. Similar calculations have also been carried out for small Rb clusters and the performance of B3LYP is equally good. Thermodynamic properties such as enthalpy and entropy for small Cs and Rb clusters have also been calculated and are well compared with the experimental data.

  15. A biokinetic model for {sup 137}Cs

    SciTech Connect

    Melo, D.R.; Lipsztein, J.L.; Oliveira, C.A.N.; Lundgren, D.L.

    1997-08-01

    An improved biokinetic model for {sup 137}Cs in humans was developed based on an analysis of data obtained from individuals internally contaminated during an accident in Goiania, Brazil, and other data. Seventeen children (ten girls and seven boys 1-10 y old), ten adolescents (four females and six males), and thirty adults, (fifteen females and fifteen males) contaminated in the accident in Goiania contributed to this study. {sup 137}Cs retention was determined through periodic measurements in a whole-body counter. In addition to the data on {sup 137}Cs retention from these individuals, data from a study on the metabolism of {sup 137}Cs in immature, adult, and aged Beagle dogs and data from the literature were used in the formulation of the {sup 137}Cs biokinetic model presented. Mathematically, the retention of cesium is described by three exponential terms, and the retention model is based on a step function of body weight. When the ICRP Publication 56 model for cesium was compared to the model suggested in this paper, it was determined that the ICRP model predicts lower effective doses in 5-y-old children and higher effective doses in infants, adolescents, and adults.

  16. CS Unplugged and Middle-School Students' Views, Attitudes, and Intentions regarding CS

    ERIC Educational Resources Information Center

    Taub, Rivka; Armoni, Michal; Ben-Ari, Mordechai

    2012-01-01

    Many students hold incorrect ideas and negative attitudes about computer science (CS). In order to address these difficulties, a series of learning activities called Computer Science Unplugged was developed by Tim Bell and his colleagues. These activities expose young people to central concepts in CS in an entertaining way without requiring a…

  17. Dielectric dispersion due to weak domain wall pinning in RbH2PO4

    NASA Astrophysics Data System (ADS)

    Mueller, Volkmar; Shchur, Yaroslav; Beige, Horst; Mattauch, Stefan; Glinnemann, Jürgen; Heger, Gernot

    2002-04-01

    Dielectric spectroscopy experiments are carried out in the ferroelectric phase of rubidium dihydrogen phosphate (RbH2PO4), within the frequency range 0.1 Hzphase transition temperature Tc, the dispersion is observed both in the range Tc>T>Tf~117 K of the anomalously high domain wall contribution and in the low-temperature range TRbH2PO4 and randomly distributed impurities.

  18. Retinoblastoma protein (RB) interacts with E2F3 to control terminal differentiation of Sertoli cells.

    PubMed

    Rotgers, E; Rivero-Müller, A; Nurmio, M; Parvinen, M; Guillou, F; Huhtaniemi, I; Kotaja, N; Bourguiba-Hachemi, S; Toppari, J

    2014-06-05

    The retinoblastoma protein (RB) is essential for normal cell cycle control. RB function depends, at least in part, on interactions with the E2F family of DNA-binding transcription factors (E2Fs). To study the role of RB in the adult testis, a Sertoli cell (SC)-specific Rb knockout mouse line (SC-RbKO) was generated using the Cre/loxP recombination system. SC-RbKO mice exhibited an age-dependent testicular atrophy, impaired fertility, severe SC dysfunction, and spermatogenic defects. Removal of Rb in SC induced aberrant SC cycling, dedifferentiation, and apoptosis. Here we show that E2F3 is the only E2F expressed in mouse SCs and that RB interacts with E2F3 during mouse testicular development. In the absence of RB, the other retinoblastoma family members p107 and p130 began interacting with E2F3 in the adult testes. In vivo silencing of E2F3 partially restored the SC maturation and survival as well as spermatogenesis in the SC-RbKO mice. These results point to RB as a key regulator of SC function in adult mice and that the RB/E2F3 pathway directs SC maturation, cell cycle quiescence, and RB protects SC from apoptosis.

  19. 30/20 GHz and 6/4 GHz band transponder development for communications satellite CS-3

    NASA Astrophysics Data System (ADS)

    Tanaka, Masayoshi; Nakamura, Makoto; Okamoto, Teruki; Kumazawa, Hiroyuki

    The next phase communications satellite CS-3 will be launched in 1988 as a successor to CS-2. The CS-3 is composed of two 6/4 GHz band and ten 30/20 GHz band transponders and its mission life is seven years. This paper describes the newly developed CS-3 transponder, especially a 4 GHz band 7 watt GaAs FET amplifier, Ka-band frequency single-conversion, a 30 GHz band low noise amplifier, and a 20 GHz band 10 watt TWTA. The introduction of these new technologies contributes significantly to reducing the CS-3 transponder weight and size, and to improving performance characteristics and insuring a long life.

  20. CS Emission Near MIR-bubbles

    NASA Astrophysics Data System (ADS)

    Watson, C.; Devine, Kathryn; Quintanar, N.; Candelaria, T.

    2016-02-01

    We survey 44 young stellar objects located near the edges of mid-IR-identified bubbles in CS (1-0) using the Green Bank Telescope. We detect emission in 18 sources, indicating young protostars that are good candidates for being triggered by the expansion of the bubble. We calculate CS column densities and abundances. Three sources show evidence of infall through non-Gaussian line-shapes. Two of these sources are associated with dark clouds and are promising candidates for further exploration of potential triggered star formation. We obtained on-the-fly maps in CS (1-0) of three sources, showing evidence of significant interactions between the sources and the surrounding environment.

  1. CS EMISSION NEAR MIR-BUBBLES

    SciTech Connect

    Watson, C.; Devine, Kathryn; Quintanar, N.; Candelaria, T. E-mail: KDevine@collegeofidaho.edu E-mail: tcandela@nmt.edu

    2016-02-10

    We survey 44 young stellar objects located near the edges of mid-IR-identified bubbles in CS (1–0) using the Green Bank Telescope. We detect emission in 18 sources, indicating young protostars that are good candidates for being triggered by the expansion of the bubble. We calculate CS column densities and abundances. Three sources show evidence of infall through non-Gaussian line-shapes. Two of these sources are associated with dark clouds and are promising candidates for further exploration of potential triggered star formation. We obtained on-the-fly maps in CS (1–0) of three sources, showing evidence of significant interactions between the sources and the surrounding environment.

  2. Beryllium-Free KBBF Family of Nonlinear-Optical Crystals: AZn2BO3X2 (A = Na, K, Rb; X = Cl, Br).

    PubMed

    Huang, Qian; Liu, Lijuan; Wang, Xiaoyang; Li, Rukang; Chen, Chuangtian

    2016-12-19

    A series of a novel beryllium-free KBBF family of nonlinear-optical materials AZn2BO3X2 (A = K, Rb and X = Cl; A = Na, K, Rb and X = Br) were successfully synthesized through molecular engineering design, and single crystals of AZn2BO3Cl2 (A = K, Rb) were grown by a spontaneous nucleation technique from self-flux systems. As a representative for the halogen KBBF family of crystals, KZn2BO3Cl2 features the infinite lattice layer [Zn2BO3Cl2]∞ made up of BO3 and ZnO3Cl anionic groups, and the in-layer BO3 groups are completely coplanar and well-aligned. Besides, KZn2BO3Cl2 exhibits high transmittance in the range of 300-2000 nm with a UV-transmission cutoff of around 200 nm according to transmission spectra. The compounds of AZn2BO3Cl2 (A = K, Rb) are both phase-matchable with powder second-harmonic-generation efficiencies of 1.3 and 1.17 times that of KH2PO4 for KZn2BO3Cl2 and RbZn2BO3Cl2, respectively, which are similar to that of KBBF.

  3. RB but not R-HCVAD is a feasible induction regimen prior to auto-HCT in frontline MCL: results of SWOG Study S1106.

    PubMed

    Chen, Robert W; Li, Hongli; Bernstein, Steven H; Kahwash, Samir; Rimsza, Lisa M; Forman, Stephen J; Constine, Louis; Shea, Thomas C; Cashen, Amanda F; Blum, Kristie A; Fenske, Timothy S; Barr, Paul M; Phillips, Tycel; Leblanc, Michael; Fisher, Richard I; Cheson, Bruce D; Smith, Sonali M; Faham, Malek; Wilkins, Jennifer; Leonard, John P; Kahl, Brad S; Friedberg, Jonathan W

    2017-03-01

    Aggressive induction chemotherapy followed by autologous haematopoietic stem cell transplant (auto-HCT) is effective for younger patients with mantle cell lymphoma (MCL). However, the optimal induction regimen is widely debated. The Southwestern Oncology Group S1106 trial was designed to assess rituximab plus hyperCVAD/MTX/ARAC (hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone, alternating with high dose cytarabine and methotrexate) (RH) versus rituximab plus bendamustine (RB) in a randomized phase II trial to select a pre-transplant induction regimen for future development. Patients had previously untreated stage III, IV, or bulky stage II MCL and received either 4 cycles of RH or 6 cycles of RB, followed by auto-HCT. Fifty-three of a planned 160 patients were accrued; an unacceptably high mobilization failure rate (29%) on the RH arm prompted premature study closure. The estimated 2-year progression-free survival (PFS) was 81% vs. 82% and overall survival (OS) was 87% vs. 88% for RB and RH, respectively. RH is not an ideal platform for future multi-centre transplant trials in MCL. RB achieved a 2-year PFS of 81% and a 78% MRD negative rate. Premature closure of the study limited the sample size and the precision of PFS estimates and MRD rates. However, RB can achieve a deep remission and could be a platform for future trials in MCL.

  4. A Novel Retinoblastoma Protein (RB) E3 Ubiquitin Ligase (NRBE3) Promotes RB Degradation and Is Transcriptionally Regulated by E2F1 Transcription Factor.

    PubMed

    Wang, Yingshuang; Zheng, Zongfang; Zhang, Jingyi; Wang, You; Kong, Ruirui; Liu, Jiangying; Zhang, Ying; Deng, Hongkui; Du, Xiaojuan; Ke, Yang

    2015-11-20

    Retinoblastoma protein (RB) plays critical roles in tumor suppression and is degraded through the proteasomal pathway. However, E3 ubiquitin ligases responsible for proteasome-mediated degradation of RB are largely unknown. Here we characterize a novel RB E3 ubiquitin ligase (NRBE3) that binds RB and promotes RB degradation. NRBE3 contains an LXCXE motif and bound RB in vitro. NRBE3 interacted with RB in cells when proteasome activity was inhibited. NRBE3 promoted RB ubiquitination and degradation via the ubiquitin-proteasome pathway. Importantly, purified NRBE3 ubiquitinated recombinant RB in vitro, and a U-box was identified as essential for its E3 activity. Surprisingly, NRBE3 was transcriptionally activated by E2F1/DP1. Consequently, NRBE3 affected the cell cycle by promoting G1/S transition. Moreover, NRBE3 was up-regulated in breast cancer tissues. Taken together, we identified NRBE3 as a novel ubiquitin E3 ligase for RB that might play a role as a potential oncoprotein in human cancers.

  5. Neutron scattering studies of spin excitations in superconducting Rb0.82Fe1.68Se2

    SciTech Connect

    Wang, Miaoyin; Li, Chunhong; Abernathy, Douglas L; Song, Yu; Carr, Scott V.; Lu, Xiangye; Li, Shiliang; Yamari, Zahra; Hu, Jiangping; Xiang, Tao; Dai, Pengcheng

    2012-01-01

    We use inelastic neutron scattering to show that superconducting (SC) rubidium iron selenide Rb0.82Fe1.68Se2 exhibits antiferromagnetic (AF) spin excitations near the in-plane wave vector Q = ( ,0) identical to that for iron arsenide superconductors. Moreover, we find that these excitations change from incommensurate to commensurate with increasing energy and occur at the expense of spin waves associated with the coexisting 5 5 block AF phase. Since these spin excitations cannot come from Fermi surface nesting based on angle resolved photoemission experiments, our results indicate the presence of local moments in SC Rb0.82Fe1.68Se2 that may have a similar origin as the hourglass-like spin excitations in copper oxide superconductors.

  6. Structure and stability of the low-temperature modification compounds Cs[sub 3]LnCl[sub 6] (Ln = La-Gd)

    SciTech Connect

    Seifert, H.J.; Fink, H. ); Baumgartner, B. )

    1993-11-01

    The crystal structure of the low-temperature modification of Cs[sub 3]LaCl[sub 6] has been determined from X-ray powder diffraction data by the Rietveld method. The monoclinic lattice with a = 27.286(5) [angstrom]; b = 8.291(1) [angstrom]; c = 13.305(2) [angstrom]; [beta] = 99.64(1)[degrees] belongs to the Cs[sub 3]BiCl[sub 6]-type (space group C2/c). All other compounds Cs[sub 3]LnCl[sub 6] (Ln = Gd) and the analogous Rb-compounds are isotypic. Emf measurements in a galvanic cell for solid electrolytes for the reactions CsCl + Cs[sub 2]LnCl[sub 5] = Cs[sub 3]LnCl[sub 6] reveal that the compounds with Ln = La,Ce,Pr,Nd are formed with a loss of lattice enthalpy, compensated by a considerable gain in entropy; they therefore are stable only at temperatures higher than O K. The compounds with Ln = Sm,Eu,Dg are formed with a gain in lattice enthalpy and are stable at T = OK, too. This difference is attributed to the different crystal structures of the neighboring compounds Cs[sub 2]LnCl[sub 5]: they crystallize with the K[sub 2]PrCl[sub 5]-structure (CN = 7 for Ln[sup 3+]) for the compounds with Ln = La-Nd, while the other compounds belong to the Cs[sub 2]DyCl[sub 5]-type with octahedral surroundings for the Ln[sup 3+] ions.

  7. Near-yrast structure of {sup 142}Cs and {sup 144}Cs

    SciTech Connect

    RzaPca-Urban, T.; Sadowski, M. P.; Genevey, J.; Pinston, J. A.; Urban, W.; Smith, A. G.; Simpson, G. S.; Bail, A.; Mathieu, L.; Serot, O.; Michel-Sendis, F.; Ahmad, I.

    2009-12-15

    Excited states in {sup 142}Cs and {sup 144}Cs, populated in the spontaneous fission of {sup 248}Cm and {sup 252}Cf and in thermal neutron-induced fission of {sup 235}U and {sup 242}Am were studied by means of {gamma} spectroscopy using the EUROGAM2 and Gammasphere multidetector Ge arrays and the LOHENGRIN fission-fragment separator, respectively. In {sup 142}Cs, a band and an isomer with a half-life of T{sub 1/2}=11(3) ns have been identified. Spins and parities have been proposed for excited levels in this nucleus. In {sup 144}Cs excited levels have been observed. A T{sub 1/2}=1.1(1) {mu}s isomer was found with a {gamma} cascade, which probably feeds this isomer. There is also an indication of a nanosecond isomer in {sup 144}Cs. Quasiparticle-rotor model calculations done in this work allowed proton-neutron configurations to be proposed for levels in {sup 142}Cs and {sup 144}Cs.

  8. 135Cs/137Cs isotopic composition of environmental samples across Europe: Environmental transport and source term emission applications

    DOE PAGES

    Snow, Mathew S.; Snyder, Darin C.

    2015-11-02

    135Cs/137Cs isotopic analyses represent an important tool for studying the fate and transport of radiocesium in the environment; in this work the 135Cs/137Cs isotopic composition in environmental samples taken from across Europe is reported. Surface soil and vegetation samples from western Russia, Ukraine, Austria, and Hungary show consistent aged thermal fission product 135Cs/137Cs isotope ratios of 0.58 ± 0.01 (age corrected to 1/1/15), with the exception of one sample of soil-moss from Hungary which shows an elevated 135Cs/137Cs ratio of 1.78 ± 0.12. With the exception of the outlier sample from Hungary, surface soil/vegetation data are in quantitative agreement withmore » values previously reported for soils within the Chernobyl exclusion zone, suggesting that radiocesium at these locations is primarily composed of homogenous airborne deposition from Chernobyl. Seawater samples taken from the Irish Sea show 135Cs/137Cs isotope ratios of 1.22 ± 0.11 (age corrected to 1/1/15), suggesting aged thermal fission product Cs discharged from Sellafield. Furthermore, the differences in 135Cs/137Cs isotope ratios between Sellafield, Chernobyl, and global nuclear weapons testing fallout indicate that 135Cs/137Cs isotope ratios can be utilized to discriminate between and track radiocesium transport from different nuclear production source terms, including major emission sources in Europe.« less

  9. Photoassociation of Rb atoms in an optical dipole trap

    NASA Astrophysics Data System (ADS)

    Menegatti, Carlos; Marangoni, Bruno; Bouloufa, Nadia; Dulieu, Olivier; Marcassa, Luis

    2012-06-01

    Laser cooling and trapping techniques are nowadays routinely used to produce atomic samples at temperatures around 1 mK or below. An old ambition in this research field is the direct application of such techniques to molecules, however due to the absence of closed optical transitions in molecules this is not straightforward. Nevertheless, cold and dense atomic trapped samples can be used to produce cold molecules trough photoassociation. In our experiment, we have trapped Rb atoms in a crossed broadband optical dipole trap. Our crossed beam configuration uses 25 W of power (at 1064 n, bandwidth of 2 nm) in each beam with about 50 micron waist radius at the focus and a depth of about 700 μK. In the typical condition, we have about 3 x 10^6 trapped atoms at a density of 3 x 10^12 cm-3. We have observed that the Rb atom population presents a non-exponential decay in such a trap. We believe that such observation suggests that the sample is been photoassociated by the 1064 nm laser, forming an excited state Rb2 molecule, which further decays forming Rb2 in the ground state. The results are compared with a theoretical model.

  10. LXCXE-independent chromatin remodeling by Rb/E2f mediates neuronal quiescence.

    PubMed

    Andrusiak, Matthew G; Vandenbosch, Renaud; Dick, Fred A; Park, David S; Slack, Ruth S

    2013-05-01

    Neuronal survival is dependent upon the retinoblastoma family members, Rb1 (Rb) and Rb2 (p130). Rb is thought to regulate gene repression, in part, through direct recruitment of chromatin modifying enzymes to its conserved LXCXE binding domain. We sought to examine the mechanisms that Rb employs to mediate cell cycle gene repression in terminally differentiated cortical neurons. Here, we report that Rb loss converts chromatin at the promoters of E2f-target genes to an activated state. We established a mouse model system in which Rb-LXCXE interactions could be induciblely disabled. Surprisingly, this had no effect on survival or gene silencing in neuronal quiescence. Absence of the Rb LXCXE-binding domain in neurons is compatible with gene repression and long-term survival, unlike Rb deficiency. Finally, we are able to show that chromatin activation following Rb deletion occurs at the level of E2fs. Blocking E2f-mediated transcription downstream of Rb loss is sufficient to maintain chromatin in an inactive state. Taken together our results suggest a model whereby Rb-E2f interactions are sufficient to maintain gene repression irrespective of LXCXE-dependent chromatin remodeling.

  11. Distinct patterns of expression of the RB gene family in mouse and human retina.

    PubMed

    Spencer, Clarellen; Pajovic, Sanja; Devlin, Hollie; Dinh, Quynh-Dao; Corson, Timothy W; Gallie, Brenda L

    2005-06-01

    Although RB1 function is disrupted in the majority of human cancers, an undefined cell of developing human retina is uniquely sensitive to cancer induction when the RB1 tumor suppressor gene is lost. Murine retinoblastoma is initiated only when two of the RB family of genes, RB1 and p107 or p130, are inactivated. Although whole embryonic retina shows RB family gene expression by several techniques, when E14 developing retina was depleted of the earliest differentiating cells, ganglion cells, the remaining proliferating murine embryonic retinal progenitor cells clearly did not express RB1 or p130, while the longer splice form of p107 was expressed. Each retinal cell type expressed some member of the RB family at some stage of differentiation. Rod photoreceptors stained for the RB1 protein product, pRB, and p107 in only a brief window of postnatal murine development, with no detectable staining for any of the RB family proteins in adult human and mouse rod photoreceptors. Adult mouse and human Muller glia, ganglion and rare horizontal cells, and adult human, but not adult mouse, cone photoreceptors stained for pRB. The RB gene family is dynamically and variably expressed through retinal development in specific retinal cells.

  12. LXCXE-independent chromatin remodeling by Rb/E2f mediates neuronal quiescence

    PubMed Central

    Andrusiak, Matthew G.; Vandenbosch, Renaud; Dick, Fred A.; Park, David S.; Slack, Ruth S.

    2013-01-01

    Neuronal survival is dependent upon the retinoblastoma family members, Rb1 (Rb) and Rb2 (p130). Rb is thought to regulate gene repression, in part, through direct recruitment of chromatin modifying enzymes to its conserved LXCXE binding domain. We sought to examine the mechanisms that Rb employs to mediate cell cycle gene repression in terminally differentiated cortical neurons. Here, we report that Rb loss converts chromatin at the promoters of E2f-target genes to an activated state. We established a mouse model system in which Rb-LXCXE interactions could be induciblely disabled. Surprisingly, this had no effect on survival or gene silencing in neuronal quiescence. Absence of the Rb LXCXE-binding domain in neurons is compatible with gene repression and long-term survival, unlike Rb deficiency. Finally, we are able to show that chromatin activation following Rb deletion occurs at the level of E2fs. Blocking E2f-mediated transcription downstream of Rb loss is sufficient to maintain chromatin in an inactive state. Taken together our results suggest a model whereby Rb-E2f interactions are sufficient to maintain gene repression irrespective of LXCXE-dependent chromatin remodeling. PMID:23574720

  13. Immune responses of bison and efficacy after booster vaccination with Brucella abortus strain RB51

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thirty-one bison heifers were randomly assigned to saline (control; n=7) or single vaccination (n=24) with 1010 CFU of B. abortus strain RB51 (RB51). Some vaccinated bison were randomly selected for booster vaccination with 10**10 CFU of RB51 at 11 months after initial vaccination (n=16). When comp...

  14. Transverse-pumped Cs vapor laser

    NASA Astrophysics Data System (ADS)

    Zhdanov, B. V.; Shaffer, M. K.; Sell, J.; Knize, R. J.

    2009-02-01

    Scaling of alkali lasers to higher powers requires combining beams of multiple diode laser pump sources. For longitudinal pumping this can be very complicated if more than four beams are to be combined. In this paper we report a first demonstration of a transversely pumped Cs laser with fifteen laser diode arrays. The LDA pump beams were individually collimated with a beam size of about 1 x 4 cm as measured at a 1 m distance from the diodes. All these beams were incident on a cylindrical lens to be focused and coupled through the side slit of a hollow, cylindrical diffuse reflector which contained the Cs vapor cell. We measured the output power and efficiency of the Cs laser for pump powers up to 200 W at different cell temperatures. Although the values of output power and slope efficiency obtained for this laser system were less than those for a longitudinally pumped alkali laser, these recent results can be significantly improved by using a more optimal laser cavity design. The demonstrated operation of Cs laser with transverse pumping opens new possibilities in power scaling of alkali lasers.

  15. Atmospheric oxidation of carbon disulfide (CS2)

    NASA Astrophysics Data System (ADS)

    Zeng, Zhe; Altarawneh, Mohammednoor; Dlugogorski, Bogdan Z.

    2017-02-01

    This contribution investigates primary steps governing the OH-initiated atmospheric oxidation of CS2. Our approach comprises high-level density functional theory calculation of energies and optimisation of molecular structures as well as RRKM-ME analysis for estimating pressure-dependent reaction rate constants. We find the overall reaction OH + CS2 → OCS + SH too slow to account for the formation of the reported experimental products. The initial reaction of OH with CS2 proceeds to produce an S-adduct, SCS(OH). Species-formation history for the system OH + CS2 indicates that, the S-adduct represents the most plausible product with a barrier-less addition process and a stability amounting to 48.5 kJ/mol, in reference to the separated reactants. This adduct then undergoes a bimolecular reaction with atmospheric O2 yielding OCS and HOSO, rather than dissociating back into its separated reactants. We also find that further atmospheric oxidation of the C-adduct (if formed) yields two of the major experimental products namely OCS and SO2. The kinetic analysis provided in this study explains the atmospheric fate of reduced sulfur species, an important S-bearing group in the global cycle of sulfur.

  16. Platinum-mediated coupling of methane and small nucleophiles (H{sub 2}O, PH{sub 3}, H{sub 2}S, CH{sub 3}NH{sub 2}) as a model for C-N, C-O, C-P, and C-S bond formation in the gas phase

    SciTech Connect

    Broenstrup, M.; Schroeder, D.; Schwarz, H.

    1999-05-10

    The reactions of Pt{sup +} and PtCH{sub 2}{sup +} with the nucleophiles H{sub 2}O, PH{sub 3}, H{sub 2}S, HCl, CH{sub 3}NH{sub 2}, and CH{sub 3}OH are studied by Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry. In the reactions of PtCH{sub 2}{sup +}, carbon-heteroatom bond formation can be accomplished for all substrates except CH{sub 3}OH and HCl. The reaction of PtCH{sub 2}{sup +} with two molecules of water yields Pt(CO)(H{sub 2}O){sup +} and constitutes a gas-phase model for the platinum-mediated generation of water gas according to CH{sub 4} + H{sub 2}O {r_arrow} CO + 3H{sub 2}. In the reactions with PH{sub 3} and H{sub 2}S, carbon-phosphorus and carbon-sulfur bond formation to PtCPH{sup +} and PtCS{sup +} competes with demethanation and dehydrogenation of the substrates to yield PtS{sub n}{sup +} (n = 1--4) and PtP{sub n}H{sub m}{sup +} (n = 1--6; m = 0--3) compounds, respectively. For organic nucleophiles such as CH{sub 3}NH{sub 2} and CH{sub 3}OH, C-N and C-O coupling is much less efficient than platinum-mediated C-H bond activation of the substrates.

  17. Baicalein induces G1 arrest in oral cancer cells by enhancing the degradation of cyclin D1 and activating AhR to decrease Rb phosphorylation

    SciTech Connect

    Cheng, Ya-Hsin; Li, Lih-Ann; Lin, Pinpin; Cheng, Li-Chuan; Hung, Chein-Hui; Chang, Nai Wen; Lin, Chingju

    2012-09-15

    Baicalein is a flavonoid, known to have anti-inflammatory and anti-cancer effects. As an aryl hydrocarbon receptor (AhR) ligand, baicalein at high concentrations blocks AhR-mediated dioxin toxicity. Because AhR had been reported to play a role in regulating the cell cycle, we suspected that the anti-cancer effect of baicalein is associated with AhR. This study investigated the molecular mechanism involved in the anti-cancer effect of baicalein in oral cancer cells HSC-3, including whether such effect would be AhR-mediated. Results revealed that baicalein inhibited cell proliferation and increased AhR activity in a dose-dependent manner. Cell cycle was arrested at the G1 phase and the expression of CDK4, cyclin D1, and phosphorylated retinoblastoma (pRb) was decreased. When the AhR was suppressed by siRNA, the reduction of pRb was partially reversed, accompanied by a decrease of cell population at G1 phase and an increase at S phase, while the reduction of cyclin D1 and CDK4 did not change. This finding suggests that the baicalein activation of AhR is indeed associated with the reduction of pRb, but is independent of the reduction of cyclin D1 and CDK4. When cells were pre-treated with LiCl, the inhibitor of GSK-3β, the decrease of cyclin D1 was blocked and the reduction of pRb was recovered. The data indicates that in HSC-3 the reduction of pRb is both mediated by baicalein through activation of AhR and facilitation of cyclin D1 degradation, which causes cell cycle arrest at the G1 phase, and results in the inhibition of cell proliferation. -- Highlights: ► Baicalein causes the G1 phase arrest by decreasing Rb phosphorylation. ► Baicalein modulates AhR-mediated cell proliferation. ► Both AhR activation and cyclin D1 degradation results in hypophosphorylation of Rb. ► Baicalein facilitates cyclin D1 degradation by signalling the GSK-3β pathway.

  18. First-principles calculations of two cubic fluoropervskite compounds: RbFeF3 and RbNiF3

    NASA Astrophysics Data System (ADS)

    Mubarak, A. A.; Al-Omari, Saleh

    2015-05-01

    We present first-principles calculations of the structural, elastic, electronic, magnetic and optical properties for RbFeF3 and RbNiF3. The full-potential linear augmented plan wave (FP-LAPW) method within the density functional theory was utilized to perform the present calculations. We employed the generalized gradient approximation as exchange-correlation potential. It was found that the calculated analytical lattice parameters agree with previous studies. The analysis of elastic constants showed that the present compounds are elastically stable and anisotropic. Moreover, both compounds are classified as a ductile compound. The calculations of the band structure and density functional theory revealed that the RbFeF3 compound has a half-metallic behavior while the RbNiF3 compound has a semiconductor behavior with indirect (M-Γ) band gap. The ferromagnetic behavior was studied for both compounds. The optical properties were calculated for the radiation of up to 40 eV. A beneficial optics technology is predicted as revealed from the optical spectra.

  19. Anomalous non-Prussian blue structures and magnetic ordering of K(2)Mn(II)[Mn(II)(CN)(6)] and Rb(2)Mn(II)[Mn(II)(CN)(6)].

    PubMed

    Her, Jae-Hyuk; Stephens, Peter W; Kareis, Christopher M; Moore, Joshua G; Min, Kil Sik; Park, Jong-Won; Bali, Garima; Kennon, Bretni S; Miller, Joel S

    2010-02-15

    The reaction of Mn(II) and KCN in aqueous and non-aqueous media leads to the isolation of three-dimensional (3-D) Prussian blue analogues, K(2)Mn[Mn(CN)(6)] (1a-d, 1e, respectively). Use of RbCN forms Rb(2)Mn[Mn(CN)(6)] (2). 1 and 2 are isomorphic {monoclinic, P2(1)/n: 1 [a = 10.1786(1) A, b = 7.4124(1) A, c = 6.9758(1) A, beta = 90.206(1)(o)]; 2 [a = 10.4101(1) A, b = 7.4492(1) A, c = 7.2132(1) A, beta = 90.072(1)(o)]}, with a small monoclinic distortion from the face centered cubic (fcc) structure that is typical of Prussian blue structured materials that was previously reported for K(2)Mn[Mn(CN)(6)]. Most notably the average Mn-N-C angles are 148.8 degrees and 153.3 degrees for 1 and 2, respectively, which are significantly reduced from linearity. This is attributed to the ionic nature of high spin Mn(II) accommodating a reduced M-CN-M' angle and minimizing void space. Compounds 1a,b have a sharp, strong nu(OH) band at 3628 cm(-1), while 1e lacks a nu(OH) absorption. The nu(OH) absorption in 1a,b is attributed to surface water, as use of D(2)O shifts the nu(OH) absorption to 2677 cm(-1), and that 1a-e are isostructural. Also, fcc Prussian blue-structured Cs(2)Mn[Mn(CN)(6)] (3) has been structurally [Fm3m: a = 10.6061(1) A] and magnetically characterized. The magnetic ordering temperature, T(c), increases as K(+) (41 K) > Rb(+) (34.6 K) > Cs(+) (21 K) for A(2)Mn[Mn(CN)(6)] in accord with the increasing deviation for linearity of the Mn-N-C linkages [148.8 (K(+)) > 153.3 (Rb(+)) > 180 degrees (Cs(+))], decreasing Mn(II)...Mn(II) separations [5.09 (K(+)) < 5.19 (Rb(+)) < 5.30 A (Cs(+))], and decreasing size of the cation (increasing electrostatic interactions). Hence, the bent cyanide bridges play a crucial role in the superexchange mechanism by increasing the coupling via shorter Mn(II)...Mn(II) separations, and perhaps enhanced overlap. In addition, the temperature dependent magnetic behavior of K(4)[Mn(II)(CN)(6)].3H(2)O is reported.

  20. 75 FR 33738 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series and RB211 Trent 500, 700, and 800...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-15

    ... plc (RR) RB211-524 Series and RB211 Trent 500, 700, and 800 Series Turbofan Engines AGENCY: Federal... holidays. Fax: (202) 493-2251. Contact Rolls-Royce plc, P.O. Box 31, Derby, DE24 8BJ, United Kingdom; phone... Information Rolls-Royce plc has issued Alert Service Bulletin RB.211-72-AF964, Revision 1, dated June 6,...

  1. Deletion of Rb1 induces both hyperproliferation and cell death in murine germinal center B cells.

    PubMed

    He, Zhiwen; O'Neal, Julie; Wilson, William C; Mahajan, Nitin; Luo, Jun; Wang, Yinan; Su, Mack Y; Lu, Lan; Skeath, James B; Bhattacharya, Deepta; Tomasson, Michael H

    2016-03-01

    The retinoblastoma gene (RB1) has been implicated as a tumor suppressor in multiple myeloma (MM), yet its role remains unclear because in the majority of cases with 13q14 deletions, un-mutated RB1 remains expressed from the retained allele. To explore the role of Rb1 in MM, we examined the functional consequences of single- and double-copy Rb1 loss in germinal center B cells, the cells of origin of MM. We generated mice without Rb1 function in germinal center B cells by crossing Rb1(Flox/Flox) with C-γ-1-Cre (Cγ1) mice expressing the Cre recombinase in class-switched B cells in a p107(-/-) background to prevent p107 from compensating for Rb1 loss (Cγ1-Rb1(F/F)-p107(-/-)). All mice developed normally, but B cells with two copies of Rb1 deleted (Cγ1-Rb1(F/F)-p107(-/-)) exhibited increased proliferation and cell death compared with Cγ1-Rb1(+/+)-p107(-/-) controls ex vivo. In vivo, Cγ1-Rb1(F/F)-p107(-/-) mice had a lower percentage of splenic B220+ cells and reduced numbers of bone marrow antigen-specific secreting cells compared with control mice. Our data indicate that Rb1 loss induces both cell proliferation and death in germinal center B cells. Because no B-cell malignancies developed after 1 year of observation, our data also suggest that Rb1 loss is not sufficient to transform post-germinal center B cells and that additional, specific mutations are likely required to cooperate with Rb1 loss to induce malignant transformation.

  2. Dephosphorylation of the Retinoblastoma protein (Rb) inhibits cancer cell EMT via Zeb.

    PubMed

    Egger, Jacklynn V; Lane, Maria V; Antonucci, Lisa A; Dedi, Brixhilda; Krucher, Nancy A

    2016-11-01

    The tumor suppressor Retinoblastoma (Rb) protein is highly phosphorylated in cancer cells largely due to the overexpression of cyclins or the loss of expression of cyclin dependent kinase inhibitors (cdki). Hyperphosphorylation of Rb promotes proliferation, and plays a role in the regulation of apoptosis. Recently, inhibition of cyclin dependent activity toward Rb has been identified as a strategy that has shown clinical efficacy. We utilized a method to induce phosphatase activity toward Rb in cells by shRNA silencing of PNUTS (Phosphatase Nuclear Targeting Subunit) that regulates PP1-mediated dephosphorylation of Rb. In this study, the effect of Rb dephosphorylation on the epithelial to mesenchymal transition (EMT) was determined. The EMT transition is observed in cancer cells that have acquired invasive characteristics. In breast cancer cells grown in 3D Matrigel cultures, MCF7 cells undergo apoptosis in response to Rb dephosphorylation, whereas MDA-MB-231 and Hs578T cells exhibit a reduction in the EMT. Cells devoid of phosphorylated Rb (nontransformed MCF10A and Rb-null MDA-MB-468) lacked any response to PNUTS depletion, showing the effect is Rb-dependent. In addition, these studies showed that Rb dephosphorylation in 3D Matrigel cultures of highly invasive HT1080 cells led to the inhibition of the EMT. Furthermore we observed association between dephosphorylated Rb with ZEB1, a zinc-finger E-box-binding transcription factor that regulates expression of E- and N-cadherins. Finally Rb dephosphorylation led to inhibition of ZEB1 transcriptional activity, this data supports the notion that Rb dephosphorylation modulates the EMT. These studies suggest targeting Rb phosphorylation in mesenchymal cancer cells may decrease invasiveness.

  3. Dephosphorylation of the Retinoblastoma protein (Rb) inhibits cancer cell EMT via Zeb

    PubMed Central

    Egger, Jacklynn V.; Lane, Maria V.; Antonucci, Lisa A.; Dedi, Brixhilda; Krucher, Nancy A.

    2016-01-01

    ABSTRACT The tumor suppressor Retinoblastoma (Rb) protein is highly phosphorylated in cancer cells largely due to the overexpression of cyclins or the loss of expression of cyclin dependent kinase inhibitors (cdki). Hyperphosphorylation of Rb promotes proliferation, and plays a role in the regulation of apoptosis. Recently, inhibition of cyclin dependent activity toward Rb has been identified as a strategy that has shown clinical efficacy. We utilized a method to induce phosphatase activity toward Rb in cells by shRNA silencing of PNUTS (Phosphatase Nuclear Targeting Subunit) that regulates PP1-mediated dephosphorylation of Rb. In this study, the effect of Rb dephosphorylation on the epithelial to mesenchymal transition (EMT) was determined. The EMT transition is observed in cancer cells that have acquired invasive characteristics. In breast cancer cells grown in 3D Matrigel cultures, MCF7 cells undergo apoptosis in response to Rb dephosphorylation, whereas MDA-MB-231 and Hs578T cells exhibit a reduction in the EMT. Cells devoid of phosphorylated Rb (nontransformed MCF10A and Rb-null MDA-MB-468) lacked any response to PNUTS depletion, showing the effect is Rb-dependent. In addition, these studies showed that Rb dephosphorylation in 3D Matrigel cultures of highly invasive HT1080 cells led to the inhibition of the EMT. Furthermore we observed association between dephosphorylated Rb with ZEB1, a zinc-finger E-box-binding transcription factor that regulates expression of E- and N-cadherins. Finally Rb dephosphorylation led to inhibition of ZEB1 transcriptional activity, this data supports the notion that Rb dephosphorylation modulates the EMT. These studies suggest targeting Rb phosphorylation in mesenchymal cancer cells may decrease invasiveness. PMID:27645778

  4. First Principles Study of Electronic and Crystallographic Structure and Elastic Properties of RbNiF3

    NASA Astrophysics Data System (ADS)

    Antonov, V.; Krezhov, K.; Trendafilova, N.

    2010-01-01

    First principles calculations, based on density functional theory (DFT) with ultra-soft pseudo potentials were performed to simulate the electronic, magnetic and crystallographic structure and elastic properties of RbNiF3, a candidate for magneto optical applications. The transparent magnetodielectric RbNiF3 is of interest because in contrast to the majority of other ABF3 compounds, which are orthorhombic perovskites, it is a representative of a much smaller group of chalcogenides with hexagonal crystal symmetry. In fact, this is the structural phase at normal pressure and it is isomorphous with the hexagonal modification of BaTiO3. The compound becomes ferrimagnetically ordered below a Néel temperature reported as 135 K. Synthesis at elevated temperature and pressure yields another phase that is a cubic perovskite (a0 = 4.077 Ǻ), reported as antiferromagnetic. Computer simulations were performed using the generalized gradient approximation exchange-correlation functional with included Hubbard correction term; (GGA+U) approach. The relative stabilities of the hexagonal and cubic phases versus applied pressure were investigated. The stability of different magnetic structures available from theoretical calculations and experimental results has been studied. The elastic constants have been evaluated via the Birch-Murnaghan equation of state. According to the DFT calculations RbNiF3 is an insulator in both phase structures. The present results for calculated electronic band structure, magnetic structures, lattice parameters, atomic positions and elastic constants can reproduce reasonably well the available own and literature data. For the cubic phase G type antiferromagnetic ordering with magnetization collinear to axis <111> was predicted.

  5. Strongly Enhanced Free-Exciton Luminescence in Microcrystalline CsPbBr3 Films

    NASA Astrophysics Data System (ADS)

    Kondo, Shin-ichi; Kakuchi, Mitsugu; Masaki, Atsushi; Saito, Tadaaki

    2003-07-01

    The luminescence properties of CsPbBr3 films prepared via the amorphous phase by crystallization are dominated by free-exciton emission, and only a weak trace of emission due to trapped excitons was observed, in contrast to the case of bulk CsPbBr3 crystals. In particular, the films in the microcrystalline state show by more than an order of magnitude stronger free-exciton emission than in the polycrystalline state. The enhanced free-exciton emission is suggestive of excitonic superradiance.

  6. Electric Field Cancellation on Quartz by Rb Adsorbate-Induced Negative Electron Affinity.

    PubMed

    Sedlacek, J A; Kim, E; Rittenhouse, S T; Weck, P F; Sadeghpour, H R; Shaffer, J P

    2016-04-01

    We investigate the (0001) surface of single crystal quartz with a submonolayer of Rb adsorbates. Using Rydberg atom electromagnetically induced transparency, we investigate the electric fields resulting from Rb adsorbed on the quartz surface, and measure the activation energy of the Rb adsorbates. We show that the adsorbed Rb induces negative electron affinity (NEA) on the quartz surface. The NEA surface allows low energy electrons to bind to the surface and cancel the electric field from the Rb adsorbates. Our results will be important for integrating Rydberg atoms into hybrid quantum systems, as fundamental probes of atom-surface interactions, and for studies of 2D electron gases bound to surfaces.

  7. Infrared multiple photon dissociation spectroscopy of cationized asparagine: effects of metal cation size on gas-phase conformation.

    PubMed

    Heaton, A L; Bowman, V N; Oomens, J; Steill, J D; Armentrout, P B

    2009-05-14

    Gas-phase structures of cationized asparagine (Asn) including complexes with Li(+), Na(+), K(+), Rb(+), Cs(+), and Ba(2+), as well as protonated Asn, are examined by infrared multiple photon dissociation (IRMPD) action spectroscopy utilizing light generated by a free electron laser. Experimental spectra for the alkali metal cation complexes exhibit systematic trends, whereas spectra for Ba(2+)(Asn) and H(+)(Asn) are more distinct. To identify the structures formed experimentally, measured IRMPD spectra are compared to spectra calculated at a B3LYP/6-311+G(d,p) level with several effective core potentials and basis sets evaluated for the heavy metal systems. The dominant conformation ascertained for complexes with the smaller metal cations, Li(+)(Asn) and Na(+)(Asn), is a charge-solvated, tridentate [N,CO,CO] structure that binds the metal cation with the amine group of the amino acid backbone and to the carbonyl oxygen atoms of the backbone and amino acid side chain. For the larger alkali metal cation complexes, K(+)(Asn), Rb(+)(Asn), and Cs(+)(Asn), an additional charge-solvated, tridentate [COOH,CO] structure that binds the metal cation with the two oxygen atoms of the backbone carboxylic acid group and the carbonyl oxygen atom of the Asn side chain may also be present. The Ba(2+)(Asn) spectrum is characteristic of a single charge-solvated [N,CO,CO] conformation, in contrast to Gly, Trp, Arg, Gln, Pro, Ser, Val, and Glu, which all take on a zwitterionic structure when complexed to Ba(2+). In no case do the cationized Asn complexes show definitive evidence of forming a zwitterionic structure in the complexes studied here. For H(+)(Asn), a mixture of two [N,CO] structures, which differ only in the orientation the side chain and are calculated to be nearly identical in energy, explains the experimental spectrum well.

  8. Electronic and magnetic phase diagram in KxFe2-ySe2 superconductors

    PubMed Central

    Yan, Y. J.; Zhang, M.; Wang, A. F.; Ying, J. J.; Li, Z. Y.; Qin, W.; Luo, X. G.; Li, J. Q.; Hu, Jiangping; Chen, X. H.

    2012-01-01

    The correlation and competition between antiferromagnetism and superconductivity are one of the most fundamental issues in high temperature superconductors. Superconductivity in high temperature cuprate superconductors arises from suppressing an antiferromagnetic (AFM) Mott insulator1 while in iron-pnictide superconductors arises from AFM semimetals and can coexist with AFM orders23456789. This difference raises many intriguing debates on the relation between the two classes of high temperature superconductors. Recently, superconductivity at 32 K has been reported in iron-chalcogenide superconductors AxFe2−ySe2 (A = K, Rb, and Cs)101112. They have the same structure as that of iron-pnictide 122-system131415. Here, we report electronic and magnetic phase diagram of KxFe2−ySe2 system as a function of Fe valence. We find a superconducting phase sandwiched between two AFM insulating phases. The two insulating phases are characterized by two distinct superstructures caused by Fe vacancy orders with modulation wave vectors of q1 = (1/5, 3/5, 0) and q2 = (1/4, 3/4, 0), respectively. PMID:22355726

  9. Monitoring 137Cs and 134Cs at marine coasts in Indonesia between 2011 and 2013.

    PubMed

    Suseno, Heny; Prihatiningsih, Wahyu Retno

    2014-11-15

    Environmental samples (seawater, sediments and biota) were collected along the eastern and western Indonesian coasts between 2011 and 2013 to anticipate the possible impacts of the Fukushima radioactive releases in Indonesia. On the eastern coasts (south and north Sulawesi), the (137)Cs concentrations in the seawater and sediments were 0.12-0.32 Bq m(-3) and 0.10-1.03 Bq kg(-1), respectively. On the western coasts (West Sumatra, Bangka Island, North Java, South Java and Madura island), the (137)Cs concentrations in the seawater and sediments were 0.12-0.66 Bq m(-3) and 0.19-1.64 Bq kg(-1), respectively. In general, the (137)Cs concentrations in the fish from several Indonesian coasts were Cs concentrations in mollusk, crab and prawn were 10.65-38.78, 4.02 and 6.16 mBq kg(-1), respectively. (134)Cs was not detected in the seawater, sediments or biota. Thus, it was concluded that (137)Cs on the eastern and western Indonesian coasts originated from global fallout.

  10. Crystal Structure and Thermodynamic Stability of Ba/Ti-Substituted Pollucites for Radioactive Cs/Ba Immobilization

    SciTech Connect

    Xu, Hongwu; Chavez, Manuel E.; Mitchell, Jeremy N.; Garino, Terry J.; Schwarz, Haiqing L.; Rodriguez, Mark A.; Rademacher, David X.; Nenoff, Tina Maria

    2015-04-23

    An analogue of the mineral pollucite (CsAlSi2O6), CsTiSi2O6.5 has a potential host phase for radioactive Cs. However, as 137Cs and 135Cs transmute to 137Ba and 135Ba, respectively, through the beta decay, it is essential to study the structure and stability of this phase upon Cs → Ba substitution. In this work, two series of Ba/Ti-substituted samples, CsxBa(1-x)/2TiSi2O6.5 and CsxBa1-xTiSi2O7-0.5x, (x = 0.9 and 0.7), were synthesized by high-temperature crystallization from their respective precursors. Synchrotron X-ray diffraction and Rietveld analysis reveal that while CsxBa(1-x)/2TiSi2O6.5 samples are phase-pure, CsxBa1-xTiSi2O7-0.5x samples contain Cs3x/(2+x)Ba(1-x)/(2+x)TiSi2O6.5 pollucites (i.e., also two-Cs-to-one-Ba substitution) and a secondary phase, fresnoite (Ba2TiSi2O8). Thus, the CsxBa1-xTiSi2O7-0.5x series is energetically less favorable than CsxBa(1-x)/2TiSi2O6.5. To study the stability systematics of CsxBa(1-x)/2TiSi2O6.5 pollucites, high-temperature calorimetric experiments were performed at 973 K with or without the lead borate solvent. Enthalpies of formation from the constituent oxides (and elements) have thus been derived. Our results show that with increasing Ba/(Cs + Ba) ratio, the thermodynamic stability of these phases decreases with respect to their component oxides. Hence, from the energetic viewpoint, continued Cs → Ba transmutation tends to destabilize the parent silicotitanate pollucite structure. However, the Ba-substituted pollucite co-forms with fresnoite (which incorporates the excess Ba

  11. RB1 dual role in proliferation and apoptosis: Cell fate control and implications for cancer therapy

    PubMed Central

    Indovina, Paola; Pentimalli, Francesca; Casini, Nadia; Vocca, Immacolata; Giordano, Antonio

    2015-01-01

    Inactivation of the retinoblastoma (RB1) tumor suppressor is one of the most frequent and early recognized molecular hallmarks of cancer. RB1, although mainly studied for its role in the regulation of cell cycle, emerged as a key regulator of many biological processes. Among these, RB1 has been implicated in the regulation of apoptosis, the alteration of which underlies both cancer development and resistance to therapy. RB1 role in apoptosis, however, is still controversial because, depending on the context, the apoptotic cues, and its own status, RB1 can act either by inhibiting or promoting apoptosis. Moreover, the mechanisms whereby RB1 controls both proliferation and apoptosis in a coordinated manner are only now beginning to be unraveled. Here, by reviewing the main studies assessing the effect of RB1 status and modulation on these processes, we provide an overview of the possible underlying molecular mechanisms whereby RB1, and its family members, dictate cell fate in various contexts. We also describe the current antitumoral strategies aimed at the use of RB1 as predictive, prognostic and therapeutic target in cancer. A thorough understanding of RB1 function in controlling cell fate determination is crucial for a successful translation of RB1 status assessment in the clinical setting. PMID:26160835

  12. Expression and regulation of RB1CC1 in developing murine and human tissues.

    PubMed

    Bamba, Noriko; Chano, Tokuhiro; Taga, Takashi; Ohta, Shigeru; Takeuchi, Yoshihiro; Okabe, Hidetoshi

    2004-10-01

    RB1-inducible coiled-coil 1 (RB1CC1) is a novel molecule implicated in the regulation of RB1 (retinoblastoma 1) expression. However, information about the RB1CC1 gene is limited and its function remains somewhat obscure. The present study analyzes the expression and promoter activities of RB1CC1 in developing murine and human tissues. Rb1cc1 was abundantly expressed from an early stage of the mouse embryo throughout development. Immunohistochemical analyses revealed that Rb1cc1 was ubiquitous in the mouse, rather than in the human embryo, especially in the musculoskeletal system, heart and neural tissues. Promoter activity was highest in a region located about 300 bp immediately upstream of exon 1 in both the mouse and human RB1CC1 genes, suggesting that this region is a core promoter. The promoter activity of RB1CC1 was generally higher in mice than in humans, and suppressive with intron 1, especially in humans. These results suggested that more Rb1cc1 is expressed throughout developing murine than in human tissues, and that RB1CC1 expression is controlled more stringently by modification at intron 1 in humans than in mice.

  13. Inhibition of pluripotency networks by the Rb tumor suppressor restricts reprogramming and tumorigenesis.

    PubMed

    Kareta, Michael S; Gorges, Laura L; Hafeez, Sana; Benayoun, Bérénice A; Marro, Samuele; Zmoos, Anne-Flore; Cecchini, Matthew J; Spacek, Damek; Batista, Luis F Z; O'Brien, Megan; Ng, Yi-Han; Ang, Cheen Euong; Vaka, Dedeepya; Artandi, Steven E; Dick, Frederick A; Brunet, Anne; Sage, Julien; Wernig, Marius

    2015-01-08

    Mutations in the retinoblastoma tumor suppressor gene Rb are involved in many forms of human cancer. In this study, we investigated the early consequences of inactivating Rb in the context of cellular reprogramming. We found that Rb inactivation promotes the reprogramming of differentiated cells to a pluripotent state. Unexpectedly, this effect is cell cycle independent, and instead reflects direct binding of Rb to pluripotency genes, including Sox2 and Oct4, which leads to a repressed chromatin state. More broadly, this regulation of pluripotency networks and Sox2 in particular is critical for the initiation of tumors upon loss of Rb in mice. These studies therefore identify Rb as a global transcriptional repressor of pluripotency networks, providing a molecular basis for previous reports about its involvement in cell fate pliability, and implicate misregulation of pluripotency factors such as Sox2 in tumorigenesis related to loss of Rb function.

  14. SENP1-modulated sumoylation regulates retinoblastoma protein (RB) and Lamin A/C interaction and stabilization.

    PubMed

    Sharma, P; Kuehn, M R

    2016-12-15

    The retinoblastoma tumor suppressor protein (RB) plays a critical role in cell proliferation and differentiation and its inactivation is a frequent underlying factor in tumorigenesis. While the regulation of RB function by phosphorylation is well studied, proteasome-mediated RB protein degradation is emerging as an important regulatory mechanism. Although our understanding of RB turnover is currently limited, there is evidence that the nuclear lamina filament protein Lamin A/C protects RB from proteasomal degradation. Here we show that SUMO1 conjugation of RB and Lamin A/C is modulated by the SUMO protease SENP1 and that sumoylation of both proteins is required for their interaction. Importantly, this SUMO1-dependent complex protects both RB and Lamin A/C from proteasomal turnover.

  15. Translocation of (133)Cs administered to Cryptomeria japonica wood.

    PubMed

    Aoki, Dan; Asai, Ryutaro; Tomioka, Rie; Matsushita, Yasuyuki; Asakura, Hiroyuki; Tabuchi, Masao; Fukushima, Kazuhiko

    2017-04-15

    To reveal the in planta behaviour of caesium (Cs), the stable isotope (133)Cs was administered into 3-year-old Cryptomeria japonica seedlings by the application of (133)CsCl aqueous solution to the bark surface. The administered (133)Cs was quantified by ICP-MS measurements, which showed transportation of (133)Cs in an ascending direction in the stem. Distribution of (133)Cs was visualized using freeze-fixed C. japonica woody stem samples and cryo-time-of-flight secondary ion mass spectrometry/scanning electron microscopy (cryo-TOF-SIMS/SEM) analysis. Cryo-TOF-SIMS/SEM visualization suggested that (133)Cs was rapidly transported radially by ray parenchyma cells followed by axial transportation by pith and axial parenchyma cells. Adsorption experiments using powdered C. japonica wood samples and X-ray absorption fine structure (XAFS) analysis suggested that (133)Cs was in the hydrated state following its deposition into tracheid cell walls.

  16. RB/PLK1-dependent induced pathway by SLAMF3 expression inhibits mitosis and control hepatocarcinoma cell proliferation

    PubMed Central

    Bouhlal, Hicham; Singh, Amrathlal Rabbind; Ossart, Christèle; Reignier, Aline; Hocini, Hakim; Fouquet, Gregory; Baghami, Mohammed Al; Eugenio, Mélanie Simoes; Nguyen-Khac, Eric; Regimbeau, Jean-Marc; Marcq, Ingrid

    2016-01-01

    Polo-like kinase PLK1 is a cell cycle protein that plays multiple roles in promoting cell cycle progression. Among the many roles, the most prominent role of PLK1 is to regulate the mitotic spindle formation checkpoint at the M-phase. Recently we reported the expression of SLAMF3 in Hepatocytes and show that it is down regulated in tumor cells of hepatocellular carcinoma (HCC). We also show that the forced high expression level of SLAMF3 in HCC cells controls proliferation by inhibiting the MAPK ERK/JNK and the mTOR pathways. In the present study, we provide evidence that the inhibitory effect of SLAMF3 on HCC proliferation occurs through Retinoblastoma (RB) factor and PLK1-dependent pathway. In addition to the inhibition of MAPK ERK/JNK and the mTOR pathways, expression of SLAMF3 in HCC retains RB factor in its hypophosphorylated active form, which in turn inactivates E2F transcription factor, thereby repressing the expression and activation of PLK1. A clear inverse correlation was also observed between SLAMF3 and PLK expression in patients with HCC. In conclusion, the results presented here suggest that the tumor suppressor potential of SLAMF3 occurs through activation of RB that represses PLK1. We propose that the induction of a high expression level of SLAMF3 in cancerous cells could control cellular mitosis and block tumor progression. PMID:26799423

  17. Pressure induced tetragonal to monoclinic transition in RbN{sub 3} studied from first principles theory

    SciTech Connect

    Vaitheeswaran, G. Babu, K. Ramesh

    2014-04-24

    Alkali metal azides are well known for their application as explosives and gas generators. They are used as precursors in synthesis of polymeric nitrogen, an ultimate green high energy density material. Among the alkali metal azides, rubidium azide RbN{sub 3} crystallizes in tetragonal structure with linear azide ions arranged in layers and binds through weak dispersive interactions. In this present work, we have studied the structural stability, electronic structure and optical properties of solid RbN{sub 3} by using van der Waals corrected density functional theory. We find that the ambient tetragonal structure undergoes a structural transition to monoclinic structure at 0.72 GPa, which is in good agreement with the experimental transition pressure of less than 1 GPa. The phonon frequencies at the gamma point are calculated and found that the lattice mode Eg softens under pressure which may supports the structural phase transition. The electronic band structure and optical properties are calculated by using Tran Blaha-modified Becke Johnson (TB-mBJ) functional and found that solid RbN{sub 3} is an insulator with a gap of 5.976 eV and the optical absorption starts with the UV light of wave length 207.5 nm.

  18. Mixing unmixables: Unexpected formation of Li-Cs alloys at low pressure.

    PubMed

    Desgreniers, Serge; Tse, John S; Matsuoka, Takahiro; Ohishi, Yasuo; Tse, Justin J

    2015-10-01

    Contrary to the empirical Miedema and Hume-Rothery rules and a recent theoretical prediction, we report experimental evidence on the formation of Li-Cs alloys at very low pressure (>0.1 GPa). We also succeeded in synthesizing a pure nonstoichiometric and ordered crystalline phase from an approximately equimolar mixture and resolved its structure using the maximum entropy method. The new alloy has a primitive cubic cell with the Li atom situated in the center and the Cs at the corners. This structure is stable to at least 10 GPa and has an anomalously high coefficient of thermal expansion at low pressure. Analysis of the valence charge density shows that electrons are donated from Cs to the Li "p"-orbitals, resulting in a rare formal oxidation state of -1 for Li. The observation indicates the diversity in the bonding of the seeming simple group I Li element.

  19. Influence of Li-codoping on the radiation hardness of CsBr:Eu{sup 2+}

    SciTech Connect

    Zimmermann, J.; Hesse, S.; Seggern, H. von; Fuchs, M.; Knuepfer, W.

    2007-06-01

    The poor radiation hardness of the otherwise excellent x-ray storage phosphor CsBr:Eu{sup 2+} constitutes a problem for its commercial application in medical diagnostics. X-ray induced vacancy centers such as M-centers enhance the diffusion of Eu{sup 2+} activators resulting in a formation of photostimulated luminescence (PSL) inactive europium clusters or second phases of europium compounds. The present study investigates the influence of Li-codoping on the radiation hardness of CsBr:Eu{sup 2+}. It is reported that the integration of Li{sup +} into the CsBr:Eu{sup 2+} suppresses the generation of M-centers during x-irradiation and thereby partially improves the radiation hardness.

  20. A subset of malignant phyllodes tumors harbors alterations in the Rb/p16 pathway.

    PubMed

    Cimino-Mathews, Ashley; Hicks, Jessica L; Sharma, Rajni; Vang, Russell; Illei, Peter B; De Marzo, Angelo; Emens, Leisha A; Argani, Pedram

    2013-11-01

    Breast phyllodes tumors are fibroepithelial neoplasms with variable risk of aggressive local recurrence and distant metastasis, and the molecular pathogenesis is unclear. Here, we systematically study p16 and Rb expression in 34 phyllodes tumors in relation to proliferation. Tissue microarrays were constructed from 10 benign, 10 borderline, and 14 malignant phyllodes (5 cores/tumor) and from 10 fibroadenomas (2 cores/tumor). Tissue microarrays were labeled by immunohistochemistry for p16, Rb, and Ki-67 and by in situ hybridization for high-risk human papillomavirus. Cytoplasmic and nuclear p16 were scored by percentage labeling (0%-100%, diffuse >95%) and intensity. Nuclear Rb was scored by percentage labeling (0%-100%, diffuse >75%) and intensity. p16 and Rb labeling were repeated on whole sections of cases with Rb loss on the tissue microarray. Twenty-nine percent (4/14) malignant phyllodes showed diffuse strong p16 labeling with Rb loss in malignant cells (diffuse p16+/Rb-), whereas 21% (3/14) malignant phyllodes showed the reverse pattern of p16 loss with diffuse strong Rb (p16-/diffuse Rb+). Results were consistent between tissue microarrays and whole sections. No borderline phyllodes, benign phyllodes, or fibroadenoma showed diffuse p16+/Rb- or p16-/diffuse Rb+ phenotypes. No cases contained high-risk human papillomavirus. Average Ki-67 proliferation indices were 15% in malignant phyllodes, 1.7% in borderline phyllodes, 0.5% in benign phyllodes, and 0% in fibroadenoma. Ki-67 was highest in malignant phyllodes with diffuse p16+/Rb- labeling. In summary, 50% malignant phyllodes display evidence of Rb/p16 pathway alterations, likely reflecting p16 or Rb inactivation. These and other mechanisms may contribute to the increased proliferation in malignant phyllodes relative to other fibroepithelial neoplasms.

  1. Phosphorylation of the Retinoblastoma protein (Rb) on serine-807 is required for association with Bax.

    PubMed

    Antonucci, Lisa A; Egger, Jacklynn V; Krucher, Nancy A

    2014-01-01

    The recent finding that the Retinoblastoma protein (Rb) is able to regulate apoptosis in a non-transcriptional manner directly at the mitochondria by interaction with the pro-apoptotic protein Bax prompted this investigation of the complex formed between Rb and Bax. Because the function of Rb in the cellular processes of proliferation, apoptosis, senescence and differentiation is regulated by phosphorylation we endeavored to elucidate the phosphorylation status of Rb with respect to its association with Bax and its role in apoptosis. In this study we found that Rb phosphorylated on at least 4 C-terminal phosphorylation sites (S608, S795, S807/S811, and T821) is present at the mitochondria under non-stressed cellular conditions. An in vitro binding assay showed that Bax binds to Rb phosphorylated at S807/S811 in 3 cancer cell types. Physiologically relevant association between Bax and Rb phosphorylated on S807/S811 was demonstrated by reciprocal co-immunoprecipitation experiments using antibodies specific for Rb phosphorylated on S807/S811 and Bax. Mutant Rb proteins expressed in Rb-null C33A cells showed that phosphorylation of S807 of Rb promotes association with Bax and that mimicking phosphorylation at S807 of Rb can block the induction of apoptosis due to PNUTS downregulation. Finally using siRNA to activate phosphatase activity in MCF7 cells, Rb is dephosphorylated at several sites including S807/S811, dissociates from Bax and apoptosis is triggered. These studies show that phosphorylation of Rb regulates its association with Bax and its role in apoptosis.

  2. Alterations in the RB1 gene in Pakistani patients with retinoblastoma using direct sequencing analysis

    PubMed Central

    Wasim, Muhammad; Afzal, Sibtain; Shahzad, Muhammad Saqib; Ramzan, Shaiqa; Awan, Ali Raza; Anjum, Aftab Ahmed; Ramzan, Khushnooda

    2015-01-01

    Purpose Retinoblastoma (RB) is a rare intraocular malignant tumor of the developing retina with an estimated incidence of 1:20,000 live births in children under the age of 5 years. In addition to the abnormal whitish appearance of the pupil or leukocoria, strabismus has also been reported as a clinical symptom of the disease. RB1 is the first cloned tumor suppressor gene, and mutational inactivation of this gene is responsible for the development of RB during early childhood. The purpose of this study was to identify mutational alterations in the RB1 gene in Pakistani patients with RB. Methods During this study, 70 clinically evaluated patients with RB were recruited from different regions of Pakistan. The cases included 23 sporadic bilateral (32.9%), 34 sporadic unilateral (48.6%), nine familial bilateral (12.8%), and four familial unilateral (5.7%) cases. Constitutional causative mutations in the RB1 gene were screened via direct sequencing of all RB1 exons and their flanking regions. Results In this report, genetic testing resulted in the identification of 18 mutations in 25 patients with RB including six novel RB1 mutations. Of the total mutations identified, 13 (72.22%) were found to be null mutations caused by nine nonsense, three deletions, and one insertion. Two (11.11%) missense, two (11.11%) splice site mutations, and one (5.55%) base substitution in the promoter region were also found. Moreover, ten intronic variants were identified, one of which is novel. Conclusions Molecular screening and identification of these mutations in Pakistani patients with RB provide the mutational variants of the RB1 gene in the Pakistani population. The detection of oncogenic mutations in patients with RB and genetically predisposed individuals is a major step in clinical management, prognosis, follow-up care, accurate genetic counseling, and presymptomatic diagnosis of RB. PMID:26396485

  3. Communications satellite no. 2 (CS-2)

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The purpose of the Japanese CS-2 satellite is to provide national communications and industrial communications, such as special emergency and remote communications, and to contribute to the development of technology pertaining to communications satellites. Description and operating parameters of the following satellite components are presented: structure, communications system, telemetry/command system, electric power system, attitude and antenna control system, secondary propulsion system, apogee motor, framework, and heat control system.

  4. End-Pumped 895 nm Cs Laser

    SciTech Connect

    Beach, R J; Krupke, W F; Kanz, V K; Payne, S A; Dubinskii, M A; Merkle, L D

    2004-02-09

    A scientific demonstration of a Cs laser is described in which the measured slope efficiency is as high as 0.59 W/W using a Ti:Sapphire laser as a surrogate diode-pump. In addition to presenting experimental data, a laser energetics model that accurately predicts laser performance is described and used to model a power-scaled, diode-pumped system.

  5. IR-Improved DGLAP-CS Theory

    DOE PAGES

    Ward, B. F. L.

    2008-01-01

    We show that it is possible to improve the infrared aspects of the standard treatment of the DGLAP-CS evolution theory to take into account a large class of higher-order corrections that significantly improve the precision of the theory for any given level of fixed-order calculation of its respective kernels. We illustrate the size of the effects we resum using the moments of the parton distributions.

  6. New insights on pressure, temperature, and chemical stability of CsAlSi5O12, a potential host for nuclear waste

    NASA Astrophysics Data System (ADS)

    Gatta, G. D.; Brundu, A.; Cappelletti, P.; Cerri, G.; de'Gennaro, B.; Farina, M.; Fumagalli, P.; Guaschino, L.; Lotti, P.; Mercurio, M.

    2016-10-01

    A Cs-bearing polyphase aggregate with composition (in wt%): 76(1)CsAlSi5O12 + 7(1)CsAlSi2O6 + 17(1)amorphous, was obtained from a clinoptilolite-rich epiclastic rock after a beneficiation process of the starting material (aimed to increase the fraction of zeolite to 90 wt%), cation exchange and then thermal treatment. CsAlSi5O12 is an open-framework compound with CAS topology; CsAlSi2O6 is a pollucite-like material with ANA topology. The thermal stability of this polyphase material was investigated by in situ high- T X-ray powder diffraction, the combined P- T effects by a series of runs with a single-stage piston cylinder apparatus, and its chemical stability following the "availability test" ("AVA test") protocol. A series of additional investigations were performed by WDS-electron microprobe analysis in order to describe the P- T-induced modification of the material texture, and to chemically characterize the starting material and the run products. The "AVA tests" of the polyphase aggregate show an extremely modest release of Cs+: 0.05 mg/g. In response to applied temperature and at room P, CsAlSi5O12 experiences an unquenchable and displacive Ama2-to- Amam phase transition at about 770 K, and the Amam polymorph is stable in its crystalline form up to 1600 K; a crystalline-to-amorphous phase transition occurs between 1600 and 1650 K. In response to the applied P = 0.5 GPa, the crystalline-to-amorphous transition of CsAlSi5O12 occurs between 1670 and 1770 K. This leads to a positive Clapeyron slope (i.e., d P/d T > 0) of the crystalline-to-amorphous transition. When the polyphase aggregate is subjected at P = 0.5 GPa and T > 1770 K, CsAlSi5O12 melts and only CsAlSi2O6 (pollucite-like; dominant) and Cs-rich glass (subordinate) are observed in the quenched sample. Based on its thermo-elastic behavior, P- T phase stability fields, and Cs+ retention capacity, CsAlSi5O12 is a possible candidate for use in the immobilization of radioactive isotopes of Cs, or as

  7. Blackbody radiation shift in ^87Rb frequency standard

    NASA Astrophysics Data System (ADS)

    Safronova, Marianna; Safronova, U. I.

    2010-03-01

    The operation of atomic clocks is generally carried out at room temperature, whereas the definition of the second refers to the clock transition in an atom at absolute zero. This implies that the clock transition frequency should be corrected in practice for the effect of finite temperature of which the leading contributor is the blackbody radiation (BBR) shift. Experimental measurements of the BBR shifts are difficult. In this work, we have calculated the blackbody radiation shift of the ground-state hyperfine microwave transition in ^87Rb using the relativistic all-order method and evaluated the accuracy of our final value. Particular care is taken to accurately account for the contributions from highly-excited states. Various Rb atomic properties, including E1, E2, and E3 ground state polarizabilities, np and nd E1 polarizabilities, and hyperfine constants are also calculated. The results are compared with experiment and other theory where available.

  8. The d 3Π state of LiRb

    NASA Astrophysics Data System (ADS)

    Stevenson, I. C.; Blasing, D. B.; Altaf, A.; Chen, Y. P.; Elliott, D. S.

    2016-12-01

    We report our spectroscopic studies of the d 3Π state of ultra-cold 7Li85Rb using resonantly enhanced multi-photon ionization and depletion spectroscopy with bound-to-bound transitions originating from the metastable a 3Σ+ state. We evaluate the potential of this state for use as the intermediate state in a stimulated-Raman-adiabatic-passage transfer scheme from triplet Feshbach LiRb molecules to the X 1Σ+ ground state and find that the lowest several vibrational levels possess the requisite overlap with initial and final states, as well as convenient energies. Using depletion measurements, we measured the well depth and spin-orbit splitting. We suggest possible pathways for short-range photoassociation using deeply bound vibrational levels of this electronic state.

  9. Spinor condensate of {sup 87}Rb as a dipolar gas

    SciTech Connect

    Swislocki, Tomasz; Gajda, Mariusz; RzaPzewski, Kazimierz

    2010-03-15

    We consider a spinor condensate of {sup 87}Rb atoms in the F=1 hyperfine state confined in an optical dipole trap. Putting initially all atoms in the m{sub F}=0 component, we find that the system evolves toward a state of thermal equilibrium with kinetic energy equally distributed among all magnetic components. We show that this process is dominated by the dipolar interaction of magnetic spins rather than spin-mixing contact potential. Our results show that because of a dynamical separation of magnetic components, the spin-mixing dynamics in the {sup 87}Rb condensate is governed by the dipolar interaction which plays no role in a single-component rubidium system in a magnetic trap.

  10. Rolls-Royce RB 211-535 power plant

    SciTech Connect

    Pickerell, D.J.

    1981-01-01

    This paper describes the derivation of the RB 211-525 power plant as a fuel efficient intermediate thrust size engine for short haul twin-engined aircraft. It traces the basic -535C from its conception giving a low risk engine with 25% better fuel burn than existing engines in this category, through to engine certification in 1981 and service in 1983. The paper then describes the later version of the engine, the -535E4, generated in response to the increasing importance of fuel burn as oil prices and scarcity increase. This engine maintains the proven background of the RB 211 family but incorporates further advanced technology giving rise to additional fuel burn improvements and thrust growth potential.

  11. Optimization of buffer gas pressure for Rb atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Chen, Chang; Liu, Xiaohu; Qu, Tianliang; Yang, Kaiyong

    2015-08-01

    The optimization of buffer gas pressure is very important to improve the performance of the rubidium (Rb) atomic magnetometer. In this paper we briefly introduce the basic principle and the experimental method of the rubidium magnetometer based on Faraday rotation effect, and describe the factors affecting the magnetometer sensitivity, then analyze and summarize the mechanism of the influence of spin-exchange, spin-destruction collisions, radiation trapping and the spin diffusion on spin relaxation of Rb atoms. Based on this, the relationship between the rubidium magnetometer sensitivity, the spin relaxation rate and the gas chamber conditions (buffer gas pressure, the bubble radius, measuring temperature) is established. Doing calculations by the simulation software, how the magnetometer sensitivity and the relaxation rate vary with the gas chamber conditions can be seen; finally, the optimal values of the buffer gas pressure under certain gas chamber conditions are obtained. The work is significant for the engineering development of rubidium magnetometer.

  12. High-temperature dehydration behavior and protonic conductivity of RbH{sub 2}PO{sub 4} in humid atmosphere

    SciTech Connect

    Li, Zikun; Tang, Tongbor

    2010-12-15

    The high-temperature (HT) properties of RbH{sub 2}PO{sub 4} have been investigated here by several methods. Two anomalies at T{sub p} ({approx}109 {sup o}C) and T{sup '}{sub p} ({approx}276 {sup o}C) in differential scanning calorimetry (DSC) measurement are due to structural transition from tetragonal (phase III) to monoclinic (phase II) and monoclinic to an unidentified phase I, respectively. The initial dehydration event in RbH{sub 2}PO{sub 4} occurs at {approx}250 {sup o}C, leading to the formation of dimer crust (Rb{sub 2}H{sub 2}P{sub 2}O{sub 7}) on the external surface of crystal particles which decelerates the further dehydration process. The conductivity measurement was performed under a highly humidified N{sub 2} condition P{sub H{sub 2O}}{approx}0.56atm to suppress its dehydration. It revealed two reversible superprotonic phase transition at T{sub p} and T{sup '}{sub p}. For the one at T{sup '}{sub p}, the conductivity increases sharply by {approx}2 orders of magnitude and the high-conductivity phase I was stable till melting. However, the other one at T{sub p} shows a relatively small jump in conductivity.

  13. Cesium Platinide Hydride 4Cs2 Pt⋅CsH: An Intermetallic Double Salt Featuring Metal Anions.

    PubMed

    Smetana, Volodymyr; Mudring, Anja-Verena

    2016-11-14

    With Cs9 Pt4 H a new representative of ionic compounds featuring metal anions can be added to this rare-membered family. Cs9 Pt4 H exhibits a complex crystal structure containing Cs(+) cations, Pt(2-) and H(-) anions. Being a red, transparent compound its band gap is in the visible range of the electromagnetic spectrum and the ionic type of bonding is confirmed by quantum chemical calculations. This cesium platinide hydride can formally be considered as a double salt of the "alloy" cesium-platinum, or better cesium platinide, Cs2 Pt, and the salt cesium hydride CsH according to Cs9 Pt4 H≡4 Cs2 Pt⋅CsH.

  14. Cesium Platinide Hydride 4Cs 2 Pt-CsH: An Intermetallic Double Salt Featuring Metal Anions

    SciTech Connect

    Smetana, Volodymyr; Mudring, Anja-Verena

    2016-10-24

    With Cs9Pt4H a new representative of ionic compounds featuring metal anions can be added to this rare-membered family. Cs9Pt4H exhibits a complex crystal structure containing Cs+ cations, Pt2- and H- anions. Being a red, transparent compound its band gap is in the visible range of the electromagnetic spectrum and the ionic type of bonding is confirmed by quantum chemical calculations. This cesium platinide hydride can formally be considered as a double salt of the “alloy” cesium–platinum, or better cesium platinide, Cs2Pt, and the salt cesium hydride CsH according to Cs9Pt4H≡4 Cs2Pt∙CsH.

  15. Electric Polarization Induced by Spin Ordering under Magnetic Fields in Distorted Triangular Lattice Antiferromagnet RbCoBr3

    NASA Astrophysics Data System (ADS)

    Nishiwaki, Yoichi; Tokunaga, Masashi; Sakakura, Ryo; Takeyama, Shojiro; Kato, Tetsuya; Iio, Katsunori

    2017-04-01

    Magnetization and electric polarization are measured for RbCoBr3 in the presence of an applied high magnetic field. The saturation of magnetization is recognized in the magnetization curve. The g-value of pseudospin and the nearest-neighbor intrachain exchange interaction of RbCoBr3, which has the properties of a quasi-one-dimensional Ising antiferromagnet, are evaluated. The electric polarization parallel to the c-axis under a magnetic field alone and also under the simultaneous application of electric and magnetic fields along the c-axis is observed to increase around the magnetic phase transition point from the ferrimagnetic low-temperature phase to the partially disordered high-temperature phase. Experimental results indicate that the electric polarization is induced through the rearrangement of the spin structure accompanied by the magnetic phase transition under an applied magnetic field. A probable reason for the enhancement of electric polarization is given from the viewpoint of the interplay between the distortion of the triangular lattice and the interchain exchange interactions.

  16. Noble Gas Polarimetry Using Rb EPR Frequency Shifts

    NASA Astrophysics Data System (ADS)

    Ma, Z. L.; Jeong, K.; Houghtby, E.; Paskvan, T.; Limes, M. E.; Saam, B.

    2014-05-01

    EPR frequency shifts of optically polarized alkali-metal atoms can be exploited for polarimetry of noble-gas nuclei polarized by spin-exchange optical pumping. Our group recently measured the enhancement factor κ0 = 493 for Rb-129Xe, which characterizes the electron wave-function overlap during collisions and is crucial to the calibration of the frequency-shift for 129Xe polarimetry. This type of polarimetry is useful in several applications involving optically polarized 129Xe; our particular motivation is an in situ measurement of absolute 129Xe polarization within the optical pumping cell of a flow-through 129Xe polarizer. This application has some particular challenges, and we have initially observed some unexpected shifts in the 87Rb EPR frequency measurement on board the polarizer. In effort to disentangle these apparent systematic effects, we have constructed a separate experiment to characterize Rb EPR shifts for both 3He and 129Xe in sealed cells. We present results and analysis of these experiments and discuss implications for using this method in flow-through polarizers. NSF PHY-0855482

  17. Measurement of the tensor differential polarizability between Rb clock states

    NASA Astrophysics Data System (ADS)

    Dallal, Yehonatan; Ozeri, Roee

    2014-05-01

    Atoms subjected to intense electric fields experience a shift in their energy levels. This shift, due to the polarizability of atomic states, enables the trapping of atoms in the focus an intense laser beam. Due to the hyperfine interaction the polarizabilities of the two hyperfine levels of 87Rb differ on the 10-5 level. In general the atomic polarizability can be decomposed into a scalar and a traceless symmetric tensor parts, the latter being 10-2 that of the former. Any anisotropy of the polarizability is due to its tensor part and the shift depends on the relative angle between the electric field and the quantizing magnetic field. In our experiment we trapped 87Rb atoms in an intense quasi-electrostatic field of a, linearly polarized, focused CO2 laser beam and measured the shift in the microwave clock transition frequency using Ramsey spectroscopy. By changing the angle between the electric field of the laser and the magnetic field providing a quantization axis, we were able to isolate the 1 Hz fractional shift caused by the, previously unmeasured, tensor polarizability. The exact knowledge of the scalar and tensor parts of the polarizability are important in order to determine the black body shift of Rb clocks; an important secondary time standard; and can be compared with state-of-the-art atomic structure calculations.

  18. Modelling the petrogenesis of high Rb/Sr silicic magmas

    USGS Publications Warehouse

    Halliday, A.N.; Davidson, J.P.; Hildreth, W.; Holden, P.

    1991-01-01

    Rhyolites can be highly evolved with Sr contents as low as 0.1 ppm and Rb Sr > 2,000. In contrast, granite batholiths are commonly comprised of rocks with Rb Sr 100. Mass-balance modelling of source compositions, differentiation and contamination using the trace-element geochemistry of granites are therefore commonly in error because of the failure to account for evolved differentiates that may have been erupted from the system. Rhyolitic magmas with very low Sr concentrations (???1 ppm) cannot be explained by any partial melting models involving typical crustal source compositions. The only plausible mechanism for the production of such rhyolites is Rayleigh fractional crystallization involving substantial volumes of cumulates. A variety of methods for modelling the differentiation of magmas with extremely high Rb/Sr is discussed. In each case it is concluded that the bulk partition coefficients for Sr have to be large. In the simplest models, the bulk DSr of the most evolved types is modelled as > 50. Evidence from phenocryst/glass/whole-rock concentrations supports high Sr partition coefficients in feldspars from high silica rhyolites. However, the low modal abundance of plagioclase commonly observed in such rocks is difficult to reconcile with such simple fractionation models of the observed trace-element trends. In certain cases, this may be because the apparent trace-element trend defined by the suite of cognetic rhyolites is the product of different batches of magma with separate differentiation histories accumulating in the magma chamber roof zone. ?? 1991.

  19. Brucella abortus RB51 in milk of vaccinated adult cattle.

    PubMed

    Miranda, Karina Leite; Poester, Fernando Padilla; Dorneles, Elaine Maria Seles; Resende, Thiago Magalhães; Vaz, Adil Knackfuss; Ferraz, Sandra Maria; Lage, Andrey Pereira

    2016-08-01

    The aim of this study was to evaluate the shedding of Brucella abortus in the milk of cows vaccinated with a full dose of RB51 during lactation. Eighteen cows, nine previously vaccinated with S19 as calves and nine non-vaccinated, were immunized subcutaneously with 1.3×10(10)CFU of B. abortus RB51, 30-60days after parturition. Milk samples from all animals were collected daily until day 7, and at weekly interval for the next 9 weeks after vaccination. To evaluate the shedding of B. abortus, milk samples were submitted for culture and PCR. No B. abortus was isolated from any sample tested. Only one sample, collected on first day after vaccination from a cow previously vaccinated, was faintly positive in the PCR. In conclusion, the public health hazard associated with milk consumption from cows vaccinated with RB51 in post-partum is very low, despite vaccination with the full dose and regardless of previous S19 vaccination.

  20. Laser cooling of nuclear spin 0 alkali 78Rb

    NASA Astrophysics Data System (ADS)

    Behr, J. A.; Gorelov, A.; Anholm, M.

    2015-05-01

    The textbook example for sub-Doppler cooling is a J = 1/2 I = 0 alkali atom in lin ⊥ lin molasses. In the σ+ σ- configuration of a standard MOT, the main sub-Doppler cooling mechanism relies on changing alignment (MF2 population) with the summed linear polarization orientation, but there is no such variation in AC Stark shift for F = 1/2. We have nevertheless looked for signs of sub-Doppler cooling by trapping I = 0 78Rb in a standard MOT and measuring the cloud size as a function of laser detuning and intensity. The 78Rb cloud size does not change significantly with lowered intensity, and expands slightly with detuning, consistent with minimal to no sub-Doppler cooling. Our geometry does show the well-known substantially smaller cloud size with detuning and intensity for I = 3/2 87Rb. Maintaining an I = 0 alkali cloud size with lowered intensity will help our planned β- ν correlation experiments in 38mK decay by suppressing possible production of photoassisted dimers. Supported by NSERC and NRC Canada through TRIUMF.

  1. Actions of arachidonic acid on erythrocyte membrane Rb permeability.

    PubMed

    Dwight, J F; Hendry, B M

    1995-07-14

    The effects of non-esterified arachidonic acid (AA) on erythrocyte membrane ion permeability have been studied using 86Rb flux measurements. [14C]AA was used to quantify membrane incorporation of AA and to show AA removal by albumin washing. The actions of vitamin E and other antioxidants on the effects of AA were examined. Reversible membrane incorporation of 700-2000 nmol AA per ml cells was achieved without significant haemolysis or morphological change. AA incorporation caused a reversible mean increase in bumetanide-sensitive Rb influx of 34% (S.E.M. 4.5, n = 23). This action could be partially prevented by co-incubation with vitamin E, but not by Trolox or dithioerythritol. AA incorporation caused an irreversible mean increase in residual Rb permeability (bumetanide and ouabain insensitive) of 130% (S.E.M. 22, n = 20), associated with a rise in intracellular Na and a fall in intracellular K concentrations. This action was also partially prevented by co-incubation with vitamin E. The effects of AA incorporation on Na,K-ATPase function were difficult to quantify because of the concomitant rises in intracellular Na but the data are consistent with approximately 20% inhibition of activity. Modulation of membrane ion permeability by AA appears to be partially mediated by lipid peroxidation and may have pathophysiological significance.

  2. Investigation of the RbCa molecule: Experiment and theory

    PubMed Central

    Pototschnig, Johann V.; Krois, Günter; Lackner, Florian; Ernst, Wolfgang E.

    2015-01-01

    We present a thorough theoretical and experimental study of the electronic structure of RbCa. The mixed alkali–alkaline earth molecule RbCa was formed on superfluid helium nanodroplets. Excited states of the molecule in the range of 13 000–23 000 cm−1 were recorded by resonance enhanced multi-photon ionization time-of-flight spectroscopy. The experiment is accompanied by high level ab initio calculations of ground and excited state properties, utilizing a multireference configuration interaction method based on multiconfigurational self consistent field calculations. With this approach the potential energy curves and permanent electric dipole moments of 24 electronic states were calculated. In addition we computed the transition dipole moments for transitions from the ground into excited states. The combination of experiment and theory allowed the assignment of features in the recorded spectrum to the excited 32Σ+, 42Σ+, 32Π, 52Σ+, 42Π, 62Σ+, 62Π, and 72Π states, where the experiment allowed to benchmark the calculation. This is the first experimental work giving insight into the previously unknown RbCa molecule, which offers great prospects in ultracold molecular physics due to its magnetic and electronic dipole moment in the 2Σ+ ground state. PMID:25922550

  3. Anomalous charge transport in RB12 (R = Ho, Er, Tm, Lu)

    NASA Astrophysics Data System (ADS)

    Sluchanko, N.; Bogomolov, L.; Glushkov, V.; Demishev, S.; Ignatov, M.; Khayrullin, Eu.; Samarin, N.; Sluchanko, D.; Levchenko, A.; Shitsevalova, N.; Flachbart, K.

    High precision measurements of Hall RH(T) and Seebeck S(T) coefficients have been carried out for the first time on single crystals of rare earth dodecaborides RB12 (R D Ho, Er, Tm, Lu) at temperatures 1.8-300 K. Low temperature anomalies detected on the temperature dependencies of RH(T) and S(T) are associated with antiferromagnetic phase transitions in HoB12, ErB12 and TmB12 compounds. The observed discrepancy between the change of charge carriers' mobility and de-Gennes factor (g - 1)2 J(J + 1) (J - angular momentum of the 4f shell) in the set of HoB12-TmB12 allows us to conclude about the appreciable influence of spin fluctuations on the charge transport in these compounds with B12 atomic clusters.

  4. Crystal Structure and Thermodynamic Stability of Ba/Ti-Substituted Pollucites for Radioactive Cs/Ba Immobilization

    DOE PAGES

    Xu, Hongwu; Chavez, Manuel E.; Mitchell, Jeremy N.; ...

    2015-04-23

    An analogue of the mineral pollucite (CsAlSi2O6), CsTiSi2O6.5 has a potential host phase for radioactive Cs. However, as 137Cs and 135Cs transmute to 137Ba and 135Ba, respectively, through the beta decay, it is essential to study the structure and stability of this phase upon Cs → Ba substitution. In this work, two series of Ba/Ti-substituted samples, CsxBa(1-x)/2TiSi2O6.5 and CsxBa1-xTiSi2O7-0.5x, (x = 0.9 and 0.7), were synthesized by high-temperature crystallization from their respective precursors. Synchrotron X-ray diffraction and Rietveld analysis reveal that while CsxBa(1-x)/2TiSi2O6.5 samples are phase-pure, CsxBa1-xTiSi2O7-0.5x samples contain Cs3x/(2+x)Ba(1-x)/(2+x)TiSi2O6.5 pollucites (i.e., also two-Cs-to-one-Ba substitution) and a secondary phase, fresnoitemore » (Ba2TiSi2O8). Thus, the CsxBa1-xTiSi2O7-0.5x series is energetically less favorable than CsxBa(1-x)/2TiSi2O6.5. To study the stability systematics of CsxBa(1-x)/2TiSi2O6.5 pollucites, high-temperature calorimetric experiments were performed at 973 K with or without the lead borate solvent. Enthalpies of formation from the constituent oxides (and elements) have thus been derived. Our results show that with increasing Ba/(Cs + Ba) ratio, the thermodynamic stability of these phases decreases with respect to their component oxides. Hence, from the energetic viewpoint, continued Cs → Ba transmutation tends to destabilize the parent silicotitanate pollucite structure. However, the Ba-substituted pollucite co-forms with fresnoite (which incorporates the excess Ba), thereby providing viable ceramic waste forms for all the Ba decay products.« less

  5. The Rb1 tumour suppressor gene modifies telomeric chromatin architecture by regulating TERRA expression

    PubMed Central

    Gonzalez-Vasconcellos, I.; Schneider, R.; Anastasov, N.; Alonso-Rodriguez, S.; Sanli-Bonazzi, B.; Fernández, J. L.; Atkinson, M. J.

    2017-01-01

    The tumour suppressor gene (Rb1) is necessary for the maintenance of telomere integrity in osteoblastic cells. We now show that the compaction of telomeric chromatin and the appropriate histone modifications of telomeric DNA are both dependent upon Rb1-mediated transcription of the telomere-derived long non-coding RNA TERRA. Expression of TERRA was reduced in Rb1 haploinsufficient cells, and further decreased by shRNA-mediated reduction of residual Rb1 expression. Restoration of Rb1 levels through lentiviral transduction was sufficient to reestablish both transcription of TERRA and condensation of telomeric chromatin. The human chromosome 15q TERRA promoter contains predicted retinoblastoma control elements, and was able to confer Rb1-dependent transcription upon a promoterless reporter gene. Chromatin immunoprecipitation revealed preferential binding of phosphorylated over non-phosphorylated Rb1 at the TERRA promoter. As Rb1-deficient cells show increased genomic instability we suggest that this novel non-canonical action of Rb1 may contribute to the tumour suppressive actions of Rb1. PMID:28169375

  6. Role of the RB-Interacting Proteins in Stem Cell Biology.

    PubMed

    Mushtaq, M; Gaza, H Viñas; Kashuba, E V

    2016-01-01

    Human retinoblastoma gene RB1 is the first tumor suppressor gene (TSG) isolated by positional cloning in 1986. RB is extensively studied for its ability to regulate cell cycle by binding to E2F1 and inhibiting the transcriptional activity of the latter. In human embryonic stem cells (ESCs), only a minute trace of RB is found in complex with E2F1. Increased activity of RB triggers differentiation, cell cycle arrest, and cell death. On the other hand, inactivation of the entire RB family (RB1, RBL1, and RBL2) in human ESC induces G2/M arrest and cell death. These observations indicate that both loss and overactivity of RB could be lethal for the stemness of cells. A question arises why inactive RB is required for the survival and stemness of cells? To shed some light on this question, we analyzed the RB-binding proteins. In this review we have focused on 27 RB-binding partners that may have potential roles in different aspects of stem cell biology.

  7. Intermediate-range chemical ordering of cations in molten RbCl-AgCl

    NASA Astrophysics Data System (ADS)

    Tahara, S.; Kawakita, Y.; Shimakura, H.; Ohara, K.; Fukami, T.; Takeda, S.

    2015-07-01

    A first sharp diffraction peak (FSDP) is observed in the X-ray total structure factor of a molten mixture of RbCl-AgCl, while both pure melts of RbCl and AgCl do not exhibit FSDP individually. Molecular dynamics simulations were performed to investigate the origin of the FSDP with the polarizable ion model (PIM). Coexistence of covalent Ag-Cl and ionic Rb-Cl bonds leads the system to evolve intermediate range ordering, which is simulated by introducing the induced polarization in different ways between Ag-Cl with fully polarizable treatment based on Vashishta-Raman potential and Rb-Cl with suppression over-polarization in the nearest neighbor contribution based on Born-Meyer potential. The partial structure factors for both the Ag-Ag and Rb-Rb correlations, SAgAg(Q) and SRbRb(Q), show a positive contribution to the FSDP, while SAgRb(Q) for the Ag-Rb correlation exhibits a negative contribution, indicating that Ag and Rb ions are distributed in an alternating manner within the intermediate-range length scale. The origin of the intermediate-range chemical ordering of cations can be ascribed to the preferred direction of the dipole moments of anions in the PIM.

  8. Reduced expression of PNUTS leads to activation of Rb-phosphatase and caspase-mediated apoptosis.

    PubMed

    De Leon, Gabriel; Sherry, Tara C; Krucher, Nancy A

    2008-06-01

    There is abundant evidence that Retinoblastoma (Rb) activity is important in the control of cell proliferation and apoptosis. Reversible phosphorylation of the Rb protein that is carried out by cyclin dependent kinases and Protein phosphatase 1 (PP1) regulates its functions. A PP1 interacting protein, PNUTS (Phosphatase Nuclear Targeting Subunit) is proposed to be a regulator of Rb phosphorylation. In this study, PNUTS knockdown in MCF7, SKA and HCT116 cancer cells causes a reduction in viability due to increased apoptosis. However, normal cells (MCF10A breast and CCD-18Co colon) do not exhibit reduced viability when PNUTS expression is diminished. PNUTS knockdown has no effect in Rb-null Saos-2 cells. However, when Rb is stably expressed in Saos-2 cells, PNUTS knockdown reduces cell number. Knockdown of PNUTS in p53-/- HCT116 cells indicates that p53 is dispensable for the induction of apoptosis. Loss of PNUTS expression results in increased Rb-phosphatase activity and Rb dephosphorylation. E2F1 dissociates from Rb in cells depleted of PNUTS and the resulting apoptosis is dependent on caspase-8. These results indicate that Rb phosphorylation state can be manipulated by targeting Rb phosphatase activity and suggest that PNUTS may be a potential target for therapeutic pro-apoptotic strategies.

  9. Equilibrium-disequilibrium relations in the Monte Rosa Granite, Western Alps: Petrological, Rb-Sr and stable isotope data

    USGS Publications Warehouse

    Frey, M.; Hunziker, J.C.; O'Neil, J.R.; Schwander, H.W.

    1976-01-01

    between quartz-muscovite and quartz-biotite 'Permian temperatures' implies oxygen isotope equilibrium in Permian time which was undisturbed during Alpine metamorphism. Arguments for equilibrium during the mid-Tertiary metamorphism are as follows: (i) Mid-Tertiary Rb-Sr mineral isochrons of up to six minerals exist, (ii) Oxygen isotope temperatures of coexisting Alpine phengites and biotites are concordant. The major factor for the adjustment of the Permian assemblages to Alpine conditions was the degree of Alpine tectonic overprinting rather than the maximum temperatures reached during the mid-Tertiary Alpine metamorphism. The lack of exchange with externally introduced fluid phases in the samples least affected by tectonism indicates that the Monte Rosa Granite 'stewed in its own juices'. This seems to be the major cause for the persistence of Permian ages and corresponding temperatures. ?? 1976 Springer-Verlag.

  10. Synthesis and phase transitions of oxide-ion conducting compound La{sub 2}Mo{sub 2}O{sub 9} doped with alkaline metals

    SciTech Connect

    Kolesnikova, D. S.; Kharitonova, E. P.; Voronkova, V. I.

    2011-03-15

    The specific features of synthesis, polymorthism, and electric conductivity of oxide-ion conducting compounds La{sub 2-x}Me{sub x}Mo{sub 2}O{sub 9-y}, where Me = Na, K, Rb, or Cs, have been studied. Ceramic samples were obtained by solid-state synthesis in the temperature range of 960-1100 Degree-Sign C. The regions where solid solutions exist have been found to depend on the temperature of the sample firing. According to the calorimetric and electrophysical data, the phase transition from the monoclinic phase ({alpha}) to the cubic phase ({beta}) in samples doped with potassium and rubidium disappears at x = 0.02 and 0.04, respectively. In these cases the only transition from the cubic {beta}{sub ms} phase to the high-temperature cubic {beta} phase is observed near 450 Degree-Sign C. Doping with sodium and cesium does not suppress the {alpha} {yields} {beta} phase transition.

  11. In situ Spectroscopy of Solid-State Chemical Reaction in PbBr2-Deposited CsBr Crystals

    NASA Astrophysics Data System (ADS)

    Kondo, Shin-ichi; Matsunaga, Toshihiro; Saito, Tadaaki; Asada, Hiroshi

    2003-09-01

    It is possible to measure the fundamental optical absorption spectra of CsPbBr3 and Cs4PbBr6, whose stability is predicted by the study of phase diagram in the binary system CsBr-PbBr2, by means of in situ optical absorption and reflection spectroscopy of thermally induced solid-state chemical reaction in PbBr2-deposited CsBr crystals. On heavy annealing of the crystals, the Pb2+ ions are uniformly dispersed in the crystal matrix. The present experiment provides a novel method for measuring intrinsic optical absorption of ternary metal halides and also for in situ monitoring of doping metal halide crystal with impurities (metal ions or halogen ions).

  12. Fabrication and characterization of CH3NH3(Cs)Pb(Sn)I3(Br) perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Ueoka, Naoki; Ohishi, Yuya; Shirahata, Yasuhiro; Suzuki, Atsushi; Oku, Takeo

    2017-01-01

    Perovskite-type CH3NH3(MA)PbI3-based photovoltaic devices were fabricated and characterized. Doping effects of cesium iodide (CsI), cesium bromide (CsBr) and tin bromide (SnBr2) on the photovoltaic properties and surface microstructures of the perovskite phase were investigated. Short-circuit current densities, open-circuit voltages and fill factors increased by CsI and SnBr2 addition. The surface coverage of the perovskite crystals was also improved by SnBr2 doping, which resulted in improvement of the fill factor. The cell prepared by a starting composition of MA0.95Cs0.05Pb0.95Sn0.05I2.90Br0.10 showed the best photovoltaic performance in the present work.

  13. A GWAS follow-up study reveals the association of the IL12RB2 gene with systemic sclerosis in Caucasian populations

    PubMed Central

    Bossini-Castillo, Lara; Martin, Jose-Ezequiel; Broen, Jasper; Gorlova, Olga; Simeón, Carmen P.; Beretta, Lorenzo; Vonk, Madelon C.; Luis Callejas, Jose; Castellví, Ivan; Carreira, Patricia; José García-Hernández, Francisco; Fernández Castro, Mónica; Coenen, Marieke J.H.; Riemekasten, Gabriela; Witte, Torsten; Hunzelmann, Nicolas; Kreuter, Alexander; Distler, Jörg H.W.; Koeleman, Bobby P.; Voskuyl, Alexandre E.; Schuerwegh, Annemie J.; Palm, Øyvind; Hesselstrand, Roger; Nordin, Annika; Airó, Paolo; Lunardi, Claudio; Scorza, Raffaella; Shiels, Paul; van Laar, Jacob M.; Herrick, Ariane; Worthington, Jane; Denton, Christopher; Tan, Filemon K.; Arnett, Frank C.; Agarwal, Sandeep K.; Assassi, Shervin; Fonseca, Carmen; Mayes, Maureen D.; Radstake, Timothy R.D.J.; Martin, Javier

    2012-01-01

    A single-nucleotide polymorphism (SNP) at the IL12RB2 locus showed a suggestive association signal in a previously published genome-wide association study (GWAS) in systemic sclerosis (SSc). Aiming to reveal the possible implication of the IL12RB2 gene in SSc, we conducted a follow-up study of this locus in different Caucasian cohorts. We analyzed 10 GWAS-genotyped SNPs in the IL12RB2 region (2309 SSc patients and 5161 controls). We then selected three SNPs (rs3790567, rs3790566 and rs924080) based on their significance level in the GWAS, for follow-up in an independent European cohort comprising 3344 SSc and 3848 controls. The most-associated SNP (rs3790567) was further tested in an independent cohort comprising 597 SSc patients and 1139 controls from the USA. After conditional logistic regression analysis of the GWAS data, we selected rs3790567 [PMH= 1.92 × 10−5 odds ratio (OR) = 1.19] as the genetic variant with the firmest independent association observed in the analyzed GWAS peak of association. After the first follow-up phase, only the association of rs3790567 was consistent (PMH= 4.84 × 10−3 OR = 1.12). The second follow-up phase confirmed this finding (Pχ2 = 2.82 × 10−4 OR = 1.34). After performing overall pooled-analysis of all the cohorts included in the present study, the association found for the rs3790567 SNP in the IL12RB2 gene region reached GWAS-level significant association (PMH= 2.82 × 10−9 OR = 1.17). Our data clearly support the IL12RB2 genetic association with SSc, and suggest a relevant role of the interleukin 12 signaling pathway in SSc pathogenesis. PMID:22076442

  14. Structure of Cs{sub 4}(HSO{sub 4}){sub 3}(H{sub 2}PO{sub 4}) single crystals

    SciTech Connect

    Makarova, I. P. Grebenev, V. V.; Vasil’ev, I. I.; Dmitricheva, E. V.; Komornikov, V. A.; Dolbinina, V. V.; Mikheikin, A. S.

    2016-01-15

    Single crystals of Cs{sub 4}(HSO{sub 4}){sub 3}(H{sub 2}PO{sub 4}) are synthesized and studied for the first time. The new compound is found in the course of studies of the phase diagram of the CsHSO{sub 4}–CsH{sub 2}PO{sub 4}–H{sub 2}O triple system. Data on the atomic crystal structure of single-crystalline and powder specimens, as well as on structural phase transitions, are obtained.

  15. Spin waves and magnetic exchange interactions in the spin-ladder compound RbFe2Se3

    DOE PAGES

    Wang, Meng; Yi, Ming; Jin, Shangjian; ...

    2016-07-20

    In this paper, we report an inelastic neutron scattering study of the spin waves of the one-dimensional antiferromagnetic spin ladder compound RbFe2Se3. The results reveal that the products, SJ's, of the spin S and the magnetic exchange interaction J along the antiferromagnetic (leg) direction and the ferromagnetic (rung) direction are comparable with those for the stripe ordered phase of the parent compounds of the iron-based superconductors. Also, the universality of the SJ's implies nearly universal spin wave dynamics and the irrelevance of the fermiology for the existence of the stripe antiferromagnetic order among various Fe-based materials.

  16. Spin accumulation in thin Cs salts on contact with optically polarized Cs vapor

    SciTech Connect

    Ishikawa, Kiyoshi

    2011-09-15

    The spin angular momentum accumulates in the Cs nuclei of salt on contact with optically pumped Cs vapor. The spin polarization in stable chloride as well as dissociative hydride indicates that nuclear dipole interaction works in spin transferring with a lesser role of atom exchange. In the solid film, not only the spin buildup but also the decay of enhanced polarization is faster than the thermal recovery rate for the bulk salt. Eliminating the signal of thick salt, we find that the nuclear spin polarization in the chloride film reaches over 100 times the thermal equilibrium.

  17. Synthesis and characterization of phosphates in molten systems Cs 2O-P 2O 5-CaO- MIII2O 3 ( MIII—Al, Fe, Cr)

    NASA Astrophysics Data System (ADS)

    Zatovsky, Igor V.; Strutynska, Nataliya Yu.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.; Ogorodnyk, Ivan V.; Shishkin, Oleg V.

    2011-03-01

    The crystallization of complex phosphates from the melts of Cs 2O-P 2O 5-CaO- MIII2O 3 ( MIII—Al, Fe, Cr) systems have been investigated at fixed value Cs/P molar ratios equal to 0.7, 1.0 and 1.3 and Са/Р=0.2 and Ca/ МIII=1. The fields of crystallization of CsCaP 3O 9, β-Ca 2P 2O 7, Cs 2CaP 2O 7, Cs 3CaFe(P 2O 7) 2, Ca 9MIII(PO 4) 7 ( MIII—Fe, Cr), Cs 0.63Ca 9.63Fe 0.37(PO 4) 7 and CsCa 10(PO 4) 7 were determined. Obtained phosphates were investigated using powder X-ray diffraction and FTIR spectroscopy. Novel whitlockite-related phases CsCa 10(PO 4) 7 and Cs 0.63Ca 9.63Fe 0.37(PO 4) 7 have been characterized by single crystal X-ray diffraction: space group R3c, a=10.5536(5) and 10.5221(4) Å, с=37.2283(19) and 37.2405(17) Å, respectively.

  18. Lack of cyclin D-Cdk complexes in Rb-negative cells correlates with high levels of p16INK4/MTS1 tumour suppressor gene product.

    PubMed Central

    Parry, D; Bates, S; Mann, D J; Peters, G

    1995-01-01

    D-type cyclins, in association with the cyclin-dependent kinases Cdk4 or Cdk6, regulate events in the G1 phase of the cell cycle and may contribute to the phosphorylation of the retinoblastoma gene product (Rb). However, in cells in which the function of Rb has been compromised, either by naturally arising mutations or through binding to proteins encoded by DNA tumour viruses, Cdk4 and Cdk6 are not associated with D cyclins. Instead, both kinases form binary complexes with a stable 16 kDa protein (p16) encoded by the putative tumour suppressor gene INK4/MTS1 on human chromosome 9p21. Here we show an inverse correlation between Rb status and the expression of p16. Since Rb-negative cells express high levels of p16, we suggest that in these cells p16 competes with D cyclins for binding to Cdk4 and Cdk6 and prevents formation of active complexes. In line with these predictions, DNA tumour virus oncoproteins do not disrupt cyclin D1-Cdk4 complexes in cells lacking p16. Images PMID:7859739

  19. K2CsSb Cathode Development

    SciTech Connect

    Smedley,J.; Rao, T.; Wang, E.

    2008-10-01

    K{sub 2}CsSb is an attractive photocathode for high current applications. With a quantum efficiency of >4% at 532nm and >10% at 355nm, it is the only cathode to have demonstrated an average current of 35mA in an accelerator environment We describe ongoing cathode development work. for the energy recovery linac being constructed at BNL Several cathodes have been created on both copper and stainless steel substrates, and their spatial uniformity and spectral response have been characterized. Preliminary lifetime measurements have been performed at high average current densities (>1 mA/mm{sup 2}).

  20. Photodissociation of Trapped Rb2+: Implications for Simultaneous Trapping of Atoms and Molecular Ions

    NASA Astrophysics Data System (ADS)

    Jyothi, S.; Ray, Tridib; Dutta, Sourav; Allouche, A. R.; Vexiau, Romain; Dulieu, Olivier; Rangwala, S. A.

    2016-11-01

    The direct photodissociation of trapped 85Rb2+ (rubidium) molecular ions by the cooling light for the 85Rb magneto-optical trap (MOT) is studied, both experimentally and theoretically. Vibrationally excited Rb2+ ions are created by photoionization of Rb2 molecules formed photoassociatively in the Rb MOT and are trapped in a modified spherical Paul trap. The decay rate of the trapped Rb2+ ion signal in the presence of the MOT cooling light is measured and agreement with our calculated rates for molecular ion photodissociation is observed. The photodissociation mechanism due to the MOT light is expected to be active and therefore universal for all homonuclear diatomic alkali metal molecular ions.

  1. Photodissociation of Trapped Rb_{2}^{+}: Implications for Simultaneous Trapping of Atoms and Molecular Ions.

    PubMed

    Jyothi, S; Ray, Tridib; Dutta, Sourav; Allouche, A R; Vexiau, Romain; Dulieu, Olivier; Rangwala, S A

    2016-11-18

    The direct photodissociation of trapped ^{85}Rb_{2}^{+} (rubidium) molecular ions by the cooling light for the ^{85}Rb magneto-optical trap (MOT) is studied, both experimentally and theoretically. Vibrationally excited Rb_{2}^{+} ions are created by photoionization of Rb_{2} molecules formed photoassociatively in the Rb MOT and are trapped in a modified spherical Paul trap. The decay rate of the trapped Rb_{2}^{+} ion signal in the presence of the MOT cooling light is measured and agreement with our calculated rates for molecular ion photodissociation is observed. The photodissociation mechanism due to the MOT light is expected to be active and therefore universal for all homonuclear diatomic alkali metal molecular ions.

  2. Effect of gamma irradiation on the conversion of ginsenoside Rb1 to Rg3

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Hun; Kwon, Sun-Kyu; Sung, Nak-Yun; Jung, Pil-Mun; Choi, Jong-il; Kim, Jae-Kyung; Sharma, Arun K.; Lee, Ju-Woon

    2012-08-01

    Ginsenosides, the most important secondary metabolites in ginseng, have various biological activities. Many studies have focused on the conversion of one of the major ginsenosides, Rb1, to the more active minor ginsenoside, Rg3. This study was carried out to investigate the effect of gamma irradiation on the conversion of Rb1 to Rg3. Rb1 solutions were gamma-irradiated at doses of 10 and 30 kGy and analyzed by high performance liquid chromatography (HPLC). HPLC chromatograms showed a decreased content of Rb1 with increasing irradiation dose, but the content of Rg3 was increased. The highest content of Rg3 was present in the 30 kGy-irradiated Rb1 sample. The cytotoxic effects tested in cancer cell lines were increased in the gamma-irradiated group. Therefore, these results suggest that gamma irradiation can be an effective method for the conversion of the ginsenoside Rb1 to Rg3.

  3. Melanin Biosynthesis Inhibition Effects of Ginsenoside Rb2 Isolated from Panax ginseng Berry.

    PubMed

    Lee, Dae Young; Jeong, Yong Tae; Jeong, Sang Chul; Lee, Mi Kyoung; Min, Jin Woo; Lee, Jae Won; Kim, Geum Soog; Lee, Seung Eun; Ahn, Young Sup; Kang, Hee Cheol; Kim, Jin Hee

    2015-12-28

    Ginsenoside Rb2 (Gin-Rb2) was purified from the fruit extract of Panax ginseng. Its chemical structure was measured by spectroscopic analysis, including HR-FAB-MS, (1)H-NMR, and IR spectroscopy. Gin-Rb2 decreased potent melanogenesis in melan-a cells, with 23.4% at 80 μM without cytotoxicity. Gin-Rb2 also decreased tyrosinase and MITF protein expression in melan-a cells. Furthermore, Gin-Rb2 presented inhibition of the body pigmentation in the zebrafish in vivo system and reduced melanin contents and tyrosinase activity. These results show that Gin-Rb2 isolated from P. ginseng may be an effective skin-whitening agent via the in vitro and in vivo systems.

  4. The RB/E2F pathway and regulation of RNA processing

    SciTech Connect

    Ahlander, Joseph; Bosco, Giovanni

    2009-07-03

    The retinoblastoma tumor suppressor protein (RB) is inactivated in a majority of cancers. RB restricts cell proliferation by inhibiting the E2F family of transcription factors. The current model for RB/E2F function describes its role in regulating transcription at gene promoters. Whether the RB or E2F proteins might play a role in gene expression beyond transcription initiation is not well known. This review describes evidence that points to a novel role for the RB/E2F network in the regulation of RNA processing, and we propose a model as a framework for future research. The elucidation of a novel role of RB in RNA processing will have a profound impact on our understanding of the role of this tumor suppressor family in cell and developmental biology.

  5. The crystal structure of cesium biuranyl trisulphate, Cs2(UO2)2(SO4)3

    USGS Publications Warehouse

    Ross, M.; Evans, H.T.

    1960-01-01

    The crystal structure of the new compound Cs(UO2)2(SO4)3 has been determined by X-ray diffraction methods. The compound is tetragonal, space group P421m (D2d3), with a = 9??62 ?? 0??02, c = 8??13 ?? 0??01 A ??, and Z = 2; s.g. (calc.) = 4??80 ?? 0??03, s.g. (obs.) = 4??74 ?? 0??05. The compound forms plates parallel to (001) bounded by the form (110). Intensity data were obtained from Buerger precession photographs of the (hk0) and (0kl) reciprocal lattice nets. No corrections for absorption were made. The co-ordinates of the U and Cs atoms were obtained by interpretation of the Patterson projections normal to (001) and (100) and a plausible structure was derived from electron density projections. The final parameters of the structure were determined from subtraction electron density maps, least squares analysis of the structure factors, and spatial considerations. The compound has a layer structure consisting of (UO2)2(SO4)3]n2n- sheets paralle to (001), tied together by cesium ions. The UO22+ group is co-ordinated by five sulphate oxygens which form a nearly plane pentagon approximately normal to the uranyl axis. The Cs2 atom is co-ordinated by twelve oxygen atoms and the Cs1 atom by eight oxygen atoms. X-ray and optical data are also given for the compound Rb2UO2(SO4)2??2H2O. ?? 1960.

  6. Ion-modulated nonlinear electronic transport in carbon nanotube bundle/RbAg{sub 4}I{sub 5} thin film composite nanostructures

    SciTech Connect

    Sun, Jia-Lin; Zhang, Wei; Wei, Jinquan; Gu, Bingfu

    2014-01-28

    We have explored the ion-modulated electronic transport properties of mixed ionic-electronic conductor (MIEC) composite nanostructures made of superionic conductor RbAg{sub 4}I{sub 5} films and carbon nanotube (CNT) bundle spiderwebs. Our experimental and theoretical studies indicate that the formation of ion-electron bound states (IEBSs) leads to strong ion-electron interference effect and interesting electronic transport of CNT, such as nonlinear current-voltage (I–V) characteristics and novel temperature dependence of the current. With increasing temperature, the hybrid nanostructures show rich phases with different dependence of current on temperature, which is related to the structural phase transition of RbAg{sub 4}I{sub 5} and the transition of dissociation of IEBSs. The ion-modulation of the electric conductivity in such MIEC composite nanostructures with great tunability has been used to design new ionic-electronic composite nano-devices with function like field effect transistor.

  7. Spectrum of germ-line RB1 gene mutations in Malaysian patients with retinoblastoma

    PubMed Central

    Yakob, Yusnita; Md Yasin, Rohani; Wee Teik, Keng; Gaik Siew, Ch’ng; Rahmat, Jamalia; Ramasamy, Sunder; Alagaratnam, Joseph

    2015-01-01

    Purpose The availability of molecular genetic testing for retinoblastoma (RB) in Malaysia has enabled patients with a heritable predisposition to the disease to be identified, which thus improves the clinical management of these patients and their families. In this paper, we presented our strategy for performing molecular genetic testing of the RB1 gene and the findings from our first 2 years of starting this service. Methods The peripheral blood of 19 RB probands, including seven bilateral and 12 unilateral cases, was obtained, and genomic DNA was extracted. Analysis of the RB1 exons and the promoter region was conducted first using PCR and direct sequencing. Next, multiplex ligation-dependent probe amplification (MLPA) analysis was performed for patients whom the first results were negative. For patients whom either the first or second method results were positive, parental samples were analyzed to determine the origin of the mutation. Results Ten RB1 mutations were identified in ten (52.6%) of the 19 probands (seven bilateral and three unilateral cases), of which 30.0% (3/10) was identified with MLPA. The detection rates in the bilateral and unilateral cases were 100.0% (7/7) and 25.0% (3/12), respectively. Three new RB1 mutations were discovered, two in patients with bilateral RB and one in patient with unilateral RB. Interestingly, all mutations detected with the PCR-sequencing method were predicted to create a premature stop codon. Eight mutations were proven to be de novo while one mutation was inherited from the mother in a family with a positive history of RB. Conclusions Our results confirmed the heterogeneous nature of RB1 mutations and the predominantly de novo origin. The high prevalence of pathogenic truncating mutations was evident among local patients with RB. The combination of PCR sequencing and MLPA is recommended for sensitive identification of heritable RB cases. PMID:26539030

  8. Rb/Sr isotopic and compositional retentivity of muscovite during deformation

    NASA Astrophysics Data System (ADS)

    Eberlei, T.; Habler, G.; Wegner, W.; Schuster, R.; Körner, W.; Thöni, M.; Abart, R.

    2015-06-01

    Permian metapegmatite muscovite from the Upper-Austroalpine Matsch Unit in Southern Tyrol (Italy) was investigated regarding its Rb/Sr and compositional retentivity during Cretaceous Upper-greenschist facies deformation. The data imply that microstructurally relic Permian magmatic muscovite largely maintained its major and trace element compositions during deformation, whereas the Rb/Sr geochronometer is strongly affected by a net loss of Sr. Lower Sr concentrations of muscovite correlate with higher 87Rb/86Sr and 87Sr/86Sr ratios. In most samples, the muscovite grain size- and magnetic-fractions with the lowest 87Rb/86Sr and 87Sr/86Sr ratios preserve a Permo-Triassic muscovite-whole rock Rb/Sr apparent age interpreted as to reflect formation during or cooling after pegmatite emplacement. Contrastingly, muscovite fractions with higher 87Rb/86Sr and 87Sr/86Sr ratios are arranged along a roughly linear array with a positive correlation of the 87Rb/86Sr and 87Sr/86Sr ratios in the 87Rb/86Sr vs 87Sr/86Sr space. They yield successively lower muscovite-whole rock Rb/Sr apparent ages. We explain the variations in the Rb/Sr isotopic character of microstructurally relic muscovite by a, presumably deformation-related, loss of Sr during the Cretaceous event. Contemporaneously, only very limited amounts of isotopically different Sr from the matrix reservoir might possibly have entered the muscovite. Consequently, the Rb/Sr of the relic muscovite is affected by a net loss of Sr. The results imply that at temperatures of < 500 °C, deformation is supposed to be the predominant factor in controlling the Rb/Sr geochronometer of relic muscovite, by significantly reducing the characteristic length scale for volume diffusion. However, variations of the major and trace element compositions within Permian relic muscovite are interpreted to rather reflect primary compositional instead of deformation-related variations.

  9. Integrin-linked kinase regulates senescence in an Rb-dependent manner in cancer cell lines.

    PubMed

    Duminuco, Rose; Noble, Jake W; Goody, Joseph; Sharma, Manju; Ksander, Bruce R; Roskelley, Calvin D; Cox, Michael E; Mills, Julia

    2015-01-01

    Anti-integrin-linked kinase (ILK) therapies result in aberrant mitosis including altered mitotic spindle organization, centrosome declustering and mitotic arrest. In contrast to cells that expressed the retinoblastoma tumor suppressor protein Rb, we have shown that in retinoblastoma cell lines that do not express Rb, anti-ILK therapies induced aberrant mitosis that led to the accumulation of temporarily viable multinucleated cells. The present work was undertaken to: 1) determine the ultimate fate of cells that had survived anti-ILK therapies and 2) determine whether or not Rb expression altered the outcome of these cells. Our data indicate that ILK, a chemotherapy drug target is expressed in both well-differentiated, Rb-negative and relatively undifferentiated, Rb-positive retinoblastoma tissue. We show that small molecule targeting of ILK in Rb-positive and Rb-deficient cancer cells results in increased centrosomal declustering, aberrant mitotic spindle formation and multinucleation. However, anti-ILK therapies in vitro have different outcomes in retinoblastoma and glioblastoma cell lines that depend on Rb expression. TUNEL labeling and propidium iodide FACS analysis indicate that Rb-positive cells exposed to anti-ILK therapies are more susceptible to apoptosis and senescence than their Rb-deficient counterparts wherein aberrant mitosis induced by anti-ILK therapies exhibit mitotic arrest instead. These studies are the first to show a role for ILK in chemotherapy-induced senescence in Rb-positive cancer lines. Taken together these results indicate that the oncosuppressive outcomes for anti-ILK therapies in vitro, depend on the expression of the tumor suppressor Rb, a known G1 checkpoint and senescence regulator.

  10. Genomic landscape of retinoblastoma in Rb(-/-) p130(-/-) mice resembles human retinoblastoma.

    PubMed

    Kooi, Irsan E; van Mil, Saskia E; MacPherson, David; Mol, Berber M; Moll, Annette C; Meijers-Heijboer, Hanne; Kaspers, Gertjan J L; Cloos, Jacqueline; Te Riele, Hein; Dorsman, Josephine C

    2017-03-01

    Several murine retinoblastoma models have been generated by deleting the genes encoding for retinoblastoma susceptibility protein pRb and one of its family members p107 or p130. In Rb(-/-) p107(-/-) retinoblastomas, somatic copy number alterations (SCNAs) like Mdm2 amplification or Cdkn2a deletion targeting the p53-pathway occur, which is uncommon for human retinoblastoma. In our study, we determined SCNAs in retinoblastomas developing in Rb(-/-) p130(-/-) mice and compared this to murine Rb(-/-) p107(-/-) tumors and human tumors. Chimeric mice were made by injection of 129/Ola-derived Rb(-/-) p130(-/-) embryonic stem cells into wild type C57BL/6 blastocysts. SCNAs of retinoblastoma samples were determined by low-coverage (∼0.5×) whole genome sequencing. In Rb(-/-) p130(-/-) tumors, SCNAs included gain of chromosomes 1 (3/23 tumors), 8 (1/23 tumors), 10 (1/23 tumors), 11 (2/23 tumors), and 12 (4/23 tumors), which could be mapped to frequently altered chromosomes in human retinoblastomas. While the altered chromosomes in Rb(-/-) p130(-/-) tumors were similar to those in Rb(-/-) p107(-/-) tumors, the alteration frequencies were much lower in Rb(-/-) p130(-/-) tumors. Most of the Rb(-/-) p130(-/-) tumors (16/23 tumors, 70%) were devoid of SCNAs, in strong contrast to Rb(-/-) p107(-/-) tumors, which were never (0/15 tumors) SCNA-devoid. Similarly, to human retinoblastoma, increased age at diagnosis significantly correlated with increased SCNA frequencies. Additionally, focal loss of Cdh11 was observed in one Rb(-/-) p130(-/-) tumor, which enforces studies in human retinoblastoma that identified CDH11 as a retinoblastoma suppressor. Moreover, based on a comparison of genes altered in human and murine retinoblastoma, we suggest exploring the role of HMGA1 and SRSF3 in retinoblastoma development. © 2016 Wiley Periodicals, Inc.

  11. Composite-type Rb-87 optical-pumping light source for the rubidium frequency standard

    NASA Technical Reports Server (NTRS)

    Oura, N.; Kuramochi, N.; Naritsuka, S.; Hayashi, T.

    1982-01-01

    The light source is composed of a cylindrical Rb-87 lamp 10 mm diameter and a Rb-85 filter cell 3-7 mm long attached to the front flat face of the lamp. This composite type device is operated in an oven at about 100 C. Thus a light source for Rb-87 hyperfine optical pumping less than 4 cm long by 3 cm diameter was constructed.

  12. RB loss contributes to aggressive tumor phenotypes in MYC-driven triple negative breast cancer.

    PubMed

    Knudsen, Erik S; McClendon, A Kathleen; Franco, Jorge; Ertel, Adam; Fortina, Paolo; Witkiewicz, Agnieszka K

    2015-01-01

    Triple negative breast cancer (TNBC) is characterized by multiple genetic events occurring in concert to drive pathogenic features of the disease. Here we interrogated the coordinate impact of p53, RB, and MYC in a genetic model of TNBC, in parallel with the analysis of clinical specimens. Primary mouse mammary epithelial cells (mMEC) with defined genetic features were used to delineate the combined action of RB and/or p53 in the genesis of TNBC. In this context, the deletion of either RB or p53 alone and in combination increased the proliferation of mMEC; however, the cells did not have the capacity to invade in matrigel. Gene expression profiling revealed that loss of each tumor suppressor has effects related to proliferation, but RB loss in particular leads to alterations in gene expression associated with the epithelial-to-mesenchymal transition. The overexpression of MYC in combination with p53 loss or combined RB/p53 loss drove rapid cell growth. While the effects of MYC overexpression had a dominant impact on gene expression, loss of RB further enhanced the deregulation of a gene expression signature associated with invasion. Specific RB loss lead to enhanced invasion in boyden chambers assays and gave rise to tumors with minimal epithelial characteristics relative to RB-proficient models. Therapeutic screening revealed that RB-deficient cells were particularly resistant to agents targeting PI3K and MEK pathway. Consistent with the aggressive behavior of the preclinical models of MYC overexpression and RB loss, human TNBC tumors that express high levels of MYC and are devoid of RB have a particularly poor outcome. Together these results underscore the potency of tumor suppressor pathways in specifying the biology of breast cancer. Further, they demonstrate that MYC overexpression in concert with RB can promote a particularly aggressive form of TNBC.

  13. Superconductivity in the tungsten bronze Rb{sub x}WO{sub 3} (0.20{<=}x{<=}0.33) in connection with its structure, electronic density of states, and phonon density of states

    SciTech Connect

    Brusetti, R.; Bordet, P.; Bossy, J.; Schober, H.; Eibl, S.

    2007-11-01

    We have measured the magnetic susceptibility of the Rb{sub x}WO{sub 3} compound (0.20{<=}x{<=}0.33) and examined its structural properties and lattice dynamics, using elastic and inelastic neutron scattering (INS) experiments, in order to gain further insight into the unusual features of its superconducting state, namely (i) the stabilizing effect resulting from the reduction of rubidium content, i.e., of the conduction electron density [what we shall name the ''T{sub c} (x) paradox''], and (ii) the destabilizing effect of the ordering of the Rb ions. We also performed density-functional calculations of the phonon dispersion in the ''stoichiometric'' Rb{sub 0.33}WO{sub 3} and Cs{sub 0.33}WO{sub 3} to identify the main features of the phonon spectra. These calculations give a very satisfactory description of the INS data and confirm the assignment to these bronzes of a lower (orthorhombic) symmetry than previously proposed. Our results contradict the previous interpretations of the T{sub c} (x) paradox and of the ordering effect: (i) no general softening of the lattice accompanies the increase of the Rb-vacancy population and (ii) no general decrease of the electron density of states D{sub EF} distinguishes the ordered nonsuperconducting Rb{sub 0.25}WO{sub 3} from its neighboring disordered parents. It appears, therefore, that the electron-electron coupling in this system probably proceeds through well-defined electronic states and phonons. This is a feature these ''hexagonal'' tungsten bronzes (HTB) apparently share with several high-T{sub c} materials. We discuss what could be the mechanisms responsible for the very selective electron-phonon coupling in the HTB.

  14. Thermal Beam Spectroscopy of 133 Cs

    NASA Astrophysics Data System (ADS)

    Gerginov, Vladislav; Tanner, Carol E.

    2001-05-01

    We report our progress towards high resolution frequency measurements of the cesium excited states hyperfine structure (HFS). A thermal beam apparatus is used to eliminate the Doppler background and collision effects present in vapor cells. A tubing array expands the beam size without increasing its divergence. The beam is collimated using thin parallel glass plate collimator. The optical detection system and the photo detector amplifier circuit allow measurements of extremely low fluorescence signals. The direct computer based measurement of the photo detector amplifier output assures a good signal linearity and no systematic line shape distortion. The estimations of different broadening effects are based on Cs D2 line HFS measurements. The spectra are fitted with exactly calculated Voigt profiles using a Fortran fitting program based on Levenberg-Marquardt method. The diode laser linewidth is determined from the beat note between two separate laser systems. The natural linewidth of Cs 6 2P3/2 is taken from our precise lifetime measurements. The residual Doppler broadening due to the finite angular beam distribution and optical alignment is estimated from the data. Financial support for this work is provided by the Division of Chemical Sciences, Office of Basic Energy Sciences, Office of Energy Research at the U. S. Department of Energy under contract number DE-FG02-95ER14579.

  15. Antibodies derived from an enterotoxigenic Escherichia coli (ETEC) adhesin tip MEFA (multiepitope fusion antigen) against adherence of nine ETEC adhesins: CFA/I, CS1, CS2, CS3, CS4, CS5, CS6, CS21 and EtpA.

    PubMed

    Nandre, Rahul M; Ruan, Xiaosai; Duan, Qiangde; Sack, David A; Zhang, Weiping

    2016-06-30

    Diarrhea continues to be a leading cause of death in children younger than 5 years in developing countries. Enterotoxigenic Escherichia coli (ETEC) is a leading bacterial cause of children's diarrhea and travelers' diarrhea. ETEC bacteria initiate diarrheal disease by attaching to host receptors at epithelial cells and colonizing in small intestine. Therefore, preventing ETEC attachment has been considered the first line of defense against ETEC diarrhea. However, developing vaccines effectively against ETEC bacterial attachment encounters challenge because ETEC strains produce over 23 immunologically heterogeneous adhesins. In this study, we applied MEFA (multiepitope fusion antigen) approach to integrate epitopes from adhesin tips or adhesive subunits of CFA/I, CS1, CS2, CS3, CS4, CS5, CS6, CS21 and EtpA adhesins and to construct an adhesin tip MEFA peptide. We then examined immunogenicity of this tip MEFA in mouse immunization, and assessed potential application of this tip MEFA for ETEC vaccine development. Data showed that mice intraperitoneally immunized with this adhesin tip MEFA developed IgG antibody responses to all nine ETEC adhesins. Moreover, ETEC and E. coli bacteria expressing these nine adhesins, after incubation with serum of the immunized mice, exhibited significant reduction in attachment to Caco-2 cells. These results indicated that anti-adhesin antibodies induced by this adhesin tip MEFA blocked adherence of the most important ETEC adhesins, suggesting this multivalent tip MEFA may be useful for developing a broadly protective anti-adhesin vaccine against ETEC diarrhea.

  16. Selective detection of divalent nickel ions based on wet-chemically prepared Cs-doped ZnO nanosheets

    NASA Astrophysics Data System (ADS)

    Rahman, Mohammed M.; Khan, Sher Bahadar; Marwani, Hadi M.; Asiri, Abdullah M.

    2014-07-01

    The current study depicts a selective detection of divalent metal ions based on Cs-doped ZnO nanosheets (NSs) materials. A large-scale synthesis of NSs by wet-chemical technique is executed using alkaline reducing agents at higher pH medium. The prepared doped NSs are characterized in terms of their morphological, structural and optical properties, and efficiently applied for the divalent metal ions detection. The detailed structural, elemental, and optical characterization of NSs are evaluated by powder X-ray diffraction (XRD), Fourier-transform Infra-red spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), XEDS, and UV-visible spectroscopy, which confirmed that the obtained NSs are well-crystalline Cs-doped ZnO and possessed good optical behaviours. The Cs-ZnO NS morphology is investigated by FE-SEM, which confirmed that the NS possesses microstructure shape and growth in large-quantity. The analytical potential of the Cs-ZnO NSs phase was evaluated for a selective extraction of divalent nickel ions prior to its determination by inductively coupled plasma-optical emission spectrometry (ICP-OES). The selectivity of Cs-ZnO NSs was investigated toward different metal ions, including Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Ni(II), Zn(II), and Zr(IV). Data obtained from the selectivity study showed that the selectivity of Cs-ZnO NSs phase was the most toward divalent nickel ions [Ni(II)]. The uptake capacity for divalent nickel ions was experimentally calculated to be ˜88.85 mg g-1. Moreover, adsorption isotherm data of divalent nickel ions on Cs-ZnO NSs phase were well fit with the Langmuir adsorption isotherm, strongly supporting that the adsorption process was mainly monolayer on homogeneous adsorbent surfaces.

  17. RB 101, a purported pro drug inhibitor of enkephalin metabolism, is antinociceptive in pregnant mice.

    PubMed

    Jayaram, A; Singh, P; Noreuil, T; Fournié-Zaluski, M C; Carp, H M

    1997-02-01

    In an earlier study, we demonstrated the enhancement of pregnancy-induced analgesia with an inhibitor of endogenous enkephalin metabolism. The purpose of the present study was to evaluate the antinociceptive effect of another inhibitor of enkephalin metabolism, RB 101, on pregnant mice. Further, since other studies have shown RB 101 to be free of opioid side effects, we examined its effect on respiratory rate. Analgesia was assessed using the hot plate test, and respiratory rate was measured by recording the output from an end-tidal carbon dioxide detector. In pregnant mice, experiments were conducted on Day 17 or Day 18 of pregnancy; mice usually deliver on Day 19. For the hot plate test, animals were tested in the following groups: Group 1, RB 101 150 mg/kg (n = 15); Group 2, RB 101 50 mg/kg (n = 15); Group 3, RB 101 vehicle (n = 15); Group 4, morphine 5 mg/kg (n = 14); and Group 5, RB 101 150 mg/kg + naloxone 5 mg/kg (n = 10). The test was repeated on the second day after delivery in animals in Groups 1 and 3 (given RB 101 150 mg/kg and RB 101 vehicle, respectively). RB 101 150 mg/kg and morphine 5 mg/kg were significantly different (mean percentage of maximum possible effect 30.0 and 37.7, respectively, at 30 min and 41.6 and 32.6, respectively, at 60 min) in their antinociceptive effect in pregnant animals from all other groups. Naloxone, when coadministered with RB 101, prevented the development of antinociception. RB 101 150 mg/kg was not antinociceptive after delivery. Depression of respiratory rate was tested in a separate set of animals in the following groups: Group 1, RB 101 150 mg/kg (n = 16); Group 2, morphine 5 mg/kg (n = 16); Group 3, RB 101 vehicle (n = 15). Morphine 5 mg/kg produced significant depression of respiratory rate at 30 min postinjection when compared with RB 101 150 mg/kg and RB 101 vehicle (mean percent change in respiratory rate was 78.5% compared with 87.7% and 92.4%, respectively, where 100% = no change). These results suggest that

  18. Emerging roles of RB family: new defense mechanisms against tumor progression.

    PubMed

    Indovina, Paola; Marcelli, Eleonora; Casini, Nadia; Rizzo, Valeria; Giordano, Antonio

    2013-03-01

    The retinoblastoma (RB) family of proteins, including RB1/p105, retinoblastoma-like 1 (RBL1/p107), and retinoblastoma-like 2 (RBL2/p130), is principally known for its central role on cell cycle regulation. The inactivation of RB proteins confers a growth advantage and underlies multiple types of tumors. Recently, it has been shown that RB proteins have other important roles, such as preservation of chromosomal stability, induction and maintenance of senescence and regulation of apoptosis, cellular differentiation, and angiogenesis. RB proteins are involved in many cellular pathways and act as transcriptional regulators able to bind several transcription factors, thus antagonizing or potentiating their functions. Furthermore, RB proteins might control the expression of specific target genes by recruiting chromatin remodeling enzymes. Although many efforts have been made to dissect the different functions of RB proteins, it remains still unclear which are necessary for cancer suppression and the role they play at distinct steps of carcinogenesis. Moreover, RB proteins can behave differently in various cell types or cell states. Elucidating the intricate RB protein network in regulating cell fate might provide the knowledge necessary to explain their potent tumor suppressor activity and to design novel therapeutic strategies.

  19. p21 suppresses inflammation and tumorigenesis on pRB-deficient stratified epithelia

    PubMed Central

    Garín, Marina; Ruiz, Sergio; Santos, Mirentxu; Lorz, Corina; García-Escudero, Ramón; Martínez-Fernández, Mónica; Bravo, Ana; Fernández-Capetillo, Oscar; Segrelles, Carmen; Paramio, Jesús M

    2016-01-01

    The retinoblastoma gene product (pRb) controls proliferation and differentiation processes in stratified epithelia. Importantly, an in contrast to other tissues, Rb deficiency does not lead to spontaneous skin tumor formation. As the cyclin dependent kinase inhibitor p21 regulates proliferation and differentiation in the absence of pRb, we analyzed the consequences of deleting p21 in pRb-ablated stratified epithelia (hereafter pRbΔEpi;p21-/-). These mice display an enhancement of the phenotypic abnormalities observed in pRbΔEpi animals, indicating that p21 partially compensates pRb absence. Remarkably, pRbΔEpi;p21-/- mice show an acute skin inflammatory phenotype and develop spontaneous epithelial tumors, particularly affecting tongue and oral tissues. Biochemical analyses and transcriptome studies reveal changes affecting multiple pathways, including DNA damage and p53-dependent signaling responses. Comparative metagenomic analyses, together with the histopathological profiles, indicate that these mice constitute a faithful model for human head and neck squamous cell carcinomas. Collectively, our findings demonstrate that p21, in conjunction with pRb, plays a central role in regulating multiple epithelial processes and orchestrating specific tumor suppressor functions. PMID:24121270

  20. Leptin-LepRb Expressed in Gastric Cancer Patients and Related to Cancer-Related Depression

    PubMed Central

    He, Chenyan; Hui, Lingyun; Huang, Tianhe

    2017-01-01

    Depression is the most common psychiatric disorder among cancer patients. Studies have not only highlighted that leptin and its receptor (LepRb) are independent poor prognostic factors in gastric cancer (GC) patients but also shown that the leptin-LepRb is necessary for antidepressant-like behaviors. In this study, we examined the serum and tissue leptin-LepRb expression in GC patients. Enzyme-linked immunosorbent assay showed that depressive GC patients had significantly higher serum leptin-LepRb than healthy donors. Leptin-LepRb levels in GC tissues were also significantly higher than in matched paracarcinoma tissues using real-time RT-PCR. Moreover, we observed that both serum and tissue leptin-LepRb were significantly higher in depressive GC patients than those in nondepressive GC patients. Further, the patients with high tumor stage tend to have higher leptin-LepRb mRNA levels than that with low tumor stage. Together, our findings suggest that leptin-LepRb plays an important role in the pathogenesis and depression in GC. Leptin-LepRb therefore could be a potential diagnostic marker and therapeutic target in GC patients with depression. PMID:28316984

  1. Changing US Attributes After CS-US Pairings Changes CS-Attribute-Assessments: Evidence for CS-US Associations in Attribute Conditioning.

    PubMed

    Förderer, Sabine; Unkelbach, Christian

    2016-03-01

    Attribute Conditioning (AC) refers to people's changed assessments of stimuli's (CSs) attributes due to repeated pairing with stimuli (USs) possessing these attributes; for example, when an athletic person (US) is paired with a neutral person (CS), the neutral person is judged to be more athletic after the pairing. We hypothesize that this AC effect is due to CSs' associations with USs rather than direct associations with attributes. Three experiments test this hypothesis by changing US attributes after CS-US pairings. Experiments 1 and 2 conditioned athleticism by pairing neutral men (CSs) with athletic and non-athletic USs. Post-conditioning, USs' athleticism was reversed, which systematically influenced participants' assessment of CS athleticism. Experiment 3 conditioned athleticism and changed USs' musicality after CS-US pairings. This post-conditioning change affected musicality assessments of CSs but did not influence athleticism-assessments. The results indicate that AC effects are based on an associative CS-US-attribute structure.

  2. On the 57-us isomer in 93Rb

    SciTech Connect

    Miernik, Krzysztof A; Gross, Carl J; Grzywacz, Robert Kazimierz; Madurga, M; Mendez, II, Anthony J; Rykaczewski, Krzysztof Piotr; Stracener, Daniel W; Zganjar, E. F.

    2014-01-01

    The 253.3 keV isomeric state located in 93Rb was studied at the HRIBF in Oak Ridge. The state in question was populated in the decay of 93Kr produced by proton induced fission of 238U and separated using the isotope separation on line technique. We report that the 253.3 keV level does not reveal isomerism and the upper limit of the half life from our measurement is 4 ns. Our findings are supported by previously reported results that were not taken into account in the latest nuclear databases.

  3. Anharmonic stabilization and band gap renormalization in the perovskite CsSnI3

    NASA Astrophysics Data System (ADS)

    Patrick, Christopher E.; Jacobsen, Karsten W.; Thygesen, Kristian S.

    2015-11-01

    Amongst the X (Sn,Pb) Y3 perovskites currently under scrutiny for their photovoltaic applications, the cubic B -α phase of CsSnI3 is arguably the best characterized experimentally. Yet, according to the standard harmonic theory of phonons, this deceptively simple phase should not exist at all due to rotational instabilities of the SnI6 octahedra. Here, employing self-consistent phonon theory, we show that these soft modes are stabilized at experimental conditions through anharmonic phonon-phonon interactions between the Cs ions and their iodine cages. We further calculate the renormalization of the electronic energies due to vibrations and find an unusual opening of the band gap, estimated as 0.24 and 0.11 eV at 500 and 300 K, which we attribute to the stretching of Sn-I bonds. Our work demonstrates the important role of temperature in accurately describing these materials.

  4. Efimov Physics in a 6Li-133Cs Atomic Mixture

    NASA Astrophysics Data System (ADS)

    Johansen, Jacob; Feng, Lei; Parker, Colin; Chin, Cheng; Wang, Yujun

    2015-05-01

    We investigate Efimov physics based on three-body recombination in an atomic mixture of 6Li and 133Cs in the vicinity of interspecies Feshbach resonances at 843 and 889 G. This allows us to compare the loss spectra near different resonances and test the universality of Efimov states. Theoretically the Efimov spectrum near 889 G is expected to be similar to that near 843 G, except that the first resonance is absent near the former Feshbach resonance. This is due to the difference in the Cs-Cs scattering length near the two resonances: At 843 G it is negative, whereas at 889 G it is positive. Although it is primarily the Li-Cs interactions that lead to Efimov resonances, the Cs-Cs scattering length is expected to influence the spectrum. This work is supported by NSF and Chicago MRSEC.

  5. Experimental Progress in a 6Li-133Cs Atomic Mixture

    NASA Astrophysics Data System (ADS)

    Feng, Lei; Johansen, Jacob; Parker, Colin; Chin, Cheng

    2015-05-01

    We report experimental progress in a mixture of 6Li and 133Cs. The mass imbalance of this system results in a particular challenge, as gravity has a significant influence on Cs position, but not on Li, separating the two gases at temperatures on the order of 200 nK. We overcome this difficulty using a two color optical dipole trap. We demonstrate mixing of these species below 100 nK in preparation for studies of quantum degenerate mixtures of this system. We further report on progress toward degeneracy and many-body physics measurements in this trap. Finally, we consider Efimov physics in this system, studying the effects of Cs-Cs interaction on the spectrum of LiCsCs trimers by a comparison of Feshbach resonances at 843 and 889 G. This work is supported by NSF and Chicago MRSEC.

  6. Factors affecting 137Cs bio- availability under the application of different fertilizing systems

    NASA Astrophysics Data System (ADS)

    Fedorkova, M. V.; Belova, N. I.

    2012-04-01

    Although it has been 25 years since the Chernobyl accident, it was generally found that radiocaesium remained bio-availability in some regions. Plant uptake of 137Cs is depended from quantity of exchangeable radionuclide and strongly influenced by soil properties. The addition of fertilizers to soil induces chemical and biological changes that influence the distribution of free ions the different phases (soil and soil solution). In this study we try to estimate influence of different soil conditions affecting the 137Cs bio-availability under the application of manure and inorganic fertilizers. Our research carried out in 2001-2008 years on contaminated after Chernobyl accident sod-podzolic soil during of prolonged field experiment. The experimental site was located in south-west of Bryansk region, Russia. Contamination density by 137Cs in the sampling point was equal to 475±30 kBq/m2. The sequence of crops in rotation was: 1) potato; 2) oats 3) lupine 4) winter rye. Three fertilizing systems were compared: organic - 80 tons per hectare of cow manure; inorganic fertilizing system - different rates of NPK (low, temperate and high) and mixed - 40 tons per hectare of cow manure + NPK. Main soil properties and chemical form of 137Cs and K (potassium) were detected. Radiocaesium activity was determined in soil and plant samples by gamma spectrometry, using a high purity Ge detectors. Overall efficiency was known to an accuracy of about 10-12%. Obtained results shows, that various fertilizing systems influence soil properties, chemical forms of 137Cs and K in soil and radionuclide soil-to-plant transfer in different ways. The highest reduction of exchangeable 137Cs in soil was found in case with application of organic fertilizers and also - temperate NPK rates. Part of exchangeable 137Cs is equal 6.8% (from total activity) in case of manure, 7.8% in case of inorganic fertilizers with control value - 10.2%. Caesium mobility in soil is affected by such soil properties as

  7. Analysis of Synchronization Performances and Impacts of Oscillator Noise in Bistatic SAOCOM-CS Mission

    NASA Astrophysics Data System (ADS)

    Mapelli, Daniele; Giudici, Davide

    2016-08-01

    Oscillator phase noise level is negligible for a monostatic Synthetic Aperture Radar (SAR) but can severely worsen the performances of a bistatic SAR. In bistatic SAR systems, there is no cancellation of low frequency phase errors as in monostatic SAR, where the same oscillator is used for both modulation and demodulation. In bistatic systems, uncompensated phase noise may bring about consequences on SLC data and phase - based applications (e.g. interferometry).Our research, focuses on the possibility of retrieving the phase synchronization between the two local Ultra Stable Oscillators (USO), using the direct signal. In addition, we present here an alternative approach that, directly operating on SAR data, does not require any further complexity of SAOCOM - CS receiver. The actual benefits of each synchronization method are measured evaluating the residual phase noise.

  8. The role of cesium suboxides in low-work-function surface layers studied by X-ray photoelectron spectroscopy - Ag-O-Cs

    NASA Technical Reports Server (NTRS)

    Yang, S.-J.; Bates, C. W., Jr.

    1980-01-01

    The oxidation of cesium on silver substrates has been studied using photoyield measurements and X-ray photoelectron spectroscopy. The occurrence of two O1s peaks in the core-level spectrum at 527.5 and 531.5-eV binding energy for cesium and oxygen exposures giving the optimum photoyield proves that two oxides of cesium exist in high-photoyield surfaces, and not Cs2O alone as previously thought. From the shape and position of the cesium peaks and the Auger parameter, the assignment of the O1s peaks at 527.5- and 531.5-eV binding energies to oxygen in Cs2O and Cs11O3, respectively, can be made. Hence the total cesium-oxygen layer is a mixed phase consisting of Cs2O + Cs11O3, approximately 20-40 A thick.

  9. Thermionic work function of /Cs/ZnO

    NASA Technical Reports Server (NTRS)

    Sommer, A. H.; Briere, T. R.

    1976-01-01

    The collector electrode of a thermionic converter requires a material having a low thermionic work function and chemical stability in a Cs atmosphere in the 800-K range. This letter reports that ZnO with an adsorbed Cs film meets these requirements. The work function is approximately 1.3 eV. Various methods of preparing the ZnO film are described as well as an experiment in which Cs was replaced by K.

  10. Synthesis, structural and spectroscopic properties of acentric triple molybdate Cs2NaBi(MoO4)3

    NASA Astrophysics Data System (ADS)

    Savina, A. A.; Atuchin, V. V.; Solodovnikov, S. F.; Solodovnikova, Z. A.; Krylov, A. S.; Maximovskiy, E. A.; Molokeev, M. S.; Oreshonkov, A. S.; Pugachev, A. M.; Khaikina, E. G.

    2015-05-01

    New ternary molybdate Cs2NaBi(MoO4)3 is synthesized in the system Na2MoO4-Cs2MoO4-Bi2(MoO4)3. The structure of Cs2NaBi(MoO4)3 of a new type is determined in noncentrosymmetric space group R3c, a=10.6435(2), c=40.9524(7) Å, V=4017.71(13) Å3, Z=12 in anisotropic approximation for all atoms taking into account racemic twinning. The structure is completely ordered, Mo atoms are tetrahedrally coordinated, Bi(1) and Bi(2) atoms are in octahedra, and Na(1) and Na(2) atoms have a distorted trigonal prismatic coordination. The Cs(1) and Cs(2) atoms are in the framework cavities with coordination numbers 12 and 10, respectively. No phase transitions were found in Cs2NaBi(MoO4)3 up to the melting point at 826 K. The compound shows an SHG signal, I2w/I2w(SiO2)=5 estimated by the powder method. The vibrational properties are evaluated by Raman spectroscopy, and 26 narrow lines are measured.

  11. Sorption of Cs+ to Micaceous Subsurface Sediments from the Hanford Site, USA

    SciTech Connect

    Zachara, John M.; Smith, Steven C.; Liu, Chongxuan; McKinley, James P.; Serne, R. Jeffrey; Gassman, Paul L.

    2002-01-15

    The sorption of Cs{sup +} was investigated over a large concentration range (10{sup -9}-10{sup -2} mol/L) on subsurface sediments from a United States nuclear materials site (Hanford) where high-level nuclear wastes (HLW) have been accidentally released to the vadose zone. The sediment sorbs large amounts of radiocesium, but expedited migration has been observed when HLW (a NaNO{sub 3} brine) is the carrier. Cs{sup +} sorption was measured on homoionic sediments (Na{sup +}, K{sup +}, Ca{sup 2+}) with electrolyte concentrations ranging from 0.01 to 1.0 mol/L. In Na{sup +} electrolyte, concentrations were extended to near saturation with NaNO{sub 3(s)} (7.0 mol/L). The sediment contained nonexpansible (biotite, muscovite) and expansible (vermiculite, smectite) phyllosilicates. The sorption data were interpreted according to the frayed edge-planar site conceptual model. A four-parameter, two-site (high- and low-affinity) numeric ion exchange model was effective in describing the sorption data. The high-affinity sites were ascribed to wedge zones on the micas where particle edges have partially expanded due to the removal of interlayer cations during weathering, and the low-affinity ones to planar sites on the expansible clays. The electrolyte cations competed with Cs{sup +} for both high- and low-affinity sites according to the trend K{sup +} >> Na{sup +} {ge} Ca{sup 2+}. At high salt concentration, Cs{sup +} adsorption occurred only on high-affinity sites. Na{sup +} was an effective competitor for the high-affinity sites at high salt concentrations. In select experiments, silver-thiourea (AgTU) was used as a blocking agent to further isolate and characterize the high-affinity sites, but the method was found to be problematic. Mica particles were handpicked from the sediment, contacted with Cs{sub eq}{sup +}, and analyzed by electron microprobe to identify phases and features important to Cs{sup +} sorption. The microprobe study implied that biotite was the primary

  12. New Scintillator Materials (K2CeBr5) and (Cs2CeBr5)

    NASA Technical Reports Server (NTRS)

    Hawrami, R.; Volz, M. P.; Batra, A. K.; Aggarwal, M. D.; Roy, U. N.; Groza, M.; Burger, A.; Cherepy, Nerine; Niedermayr, Thomas; Payne, Stephen A.

    2008-01-01

    Cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5) are new scintillator materials for X-ray and gamma ray detector applications. Recently halide scintillator materials, such as Ce doped lanthanum bromide has been proved to be very important material for the same purpose. These materials are highly hygroscopic; a search for high light yield non-hygroscopic materials was highly desirable to advance the scintillator technology. In this paper, we are reporting the crystal growth of novel scintillator materials, cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5). Crystals were successfully grown from the melt using the vertical Bridgman-Stockbarger technique, in a comparison with the high performance LaBr3 or LaCl3 crystals, cerium based alkali halides crystals, (Cs2CeBr5) and (K2CeBr5) have similar scintillation properties, while being much less hygroscopic. Furthermore, cesium based compounds will not suffer from the self-activity present in potassium and lanthanum compounds. However the Cs2CeBr5 crystals did not grow properly probably due to non-congruent melting or to some phase transition during cooling. Keywords." Scintillator materials; Ce3+; Energy resolution; Light yield; K2CeBr5

  13. Fractionation of (137)Cs and Pu in natural peatland.

    PubMed

    Mihalík, Ján; Bartusková, Miluše; Hölgye, Zoltán; Ježková, Tereza; Henych, Ondřej

    2014-08-01

    High Cs-137 concentrations in plants growing on peatland inspired us to investigate the quantity of its bioavailable fraction in natural peat. Our investigation aims to: a) estimate the quantity of bioavailable Cs-137 and Pu present in peat, b) verify the similarity of Cs-137 and K-40 behaviours, and c) perform a quantification of Cs-137 and Pu transfer from peat to plants. We analysed the vertical distribution of Cs-137 and Pu isotopes in the peat and their concentrations in plants growing on these places. Bioavailability of radionuclides was investigated by sequential extraction. Sequential analyses revealed that it was the upper layer which contained the majority of Cs-137 in an available form while deeper layers retained Cs-137 in immobile fractions. We can conclude that 18% of all Cs-137 in the peat is still bioavailable. Despite of the low quantity of bioavailable fraction of Cs-137 its transfer factor reached extremely high values. In the case of Pu, 64% of its total amount was associated with fulvic/humic acids which resulted in the high transfer factor from peat to plants. 27 years after the Chernobyl nuclear accident, the significant part of radionuclides deposited in peatland is still bioavailable.

  14. Improved TV-CS Approaches for Inverse Scattering Problem

    PubMed Central

    Bevacqua, M. T.; Di Donato, L.

    2015-01-01

    Total Variation and Compressive Sensing (TV-CS) techniques represent a very attractive approach to inverse scattering problems. In fact, if the unknown is piecewise constant and so has a sparse gradient, TV-CS approaches allow us to achieve optimal reconstructions, reducing considerably the number of measurements and enforcing the sparsity on the gradient of the sought unknowns. In this paper, we introduce two different techniques based on TV-CS that exploit in a different manner the concept of gradient in order to improve the solution of the inverse scattering problems obtained by TV-CS approach. Numerical examples are addressed to show the effectiveness of the method. PMID:26495420

  15. CS-Studio Scan System Parallelization

    SciTech Connect

    Kasemir, Kay; Pearson, Matthew R

    2015-01-01

    For several years, the Control System Studio (CS-Studio) Scan System has successfully automated the operation of beam lines at the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) and Spallation Neutron Source (SNS). As it is applied to additional beam lines, we need to support simultaneous adjustments of temperatures or motor positions. While this can be implemented via virtual motors or similar logic inside the Experimental Physics and Industrial Control System (EPICS) Input/Output Controllers (IOCs), doing so requires a priori knowledge of experimenters requirements. By adding support for the parallel control of multiple process variables (PVs) to the Scan System, we can better support ad hoc automation of experiments that benefit from such simultaneous PV adjustments.

  16. Thermal ionization of Cs Rydberg states

    NASA Astrophysics Data System (ADS)

    Glukhov, I. L.; Ovsiannikov, V. D.

    2009-01-01

    Rates Pnl of photoionization from Rydberg ns-, np-, nd-states of a valence electron in Cs, induced by black-body radiation, were calculated on the basis of the modified Fues model potential method. The numerical data were approximated with a three-term expression which reproduces in a simple analytical form the dependence of Pnl on the ambient temperature T and on the principal quantum number n. The comparison between approximate and exactly calculated values of the thermal ionization rate demonstrates the applicability of the proposed approximation for highly excited states with n from 20 to 100 in a wide temperature range of T from 100 to 10,000 K. We present coefficients of this approximation for the s-, p- and d-series of Rydberg states.

  17. Revealing the optoelectronic and thermoelectric properties of the Zintl quaternary arsenides ACdGeAs{sub 2} (A = K, Rb)

    SciTech Connect

    Azam, Sikander; Khan, Saleem Ayaz; Goumri-Said, Souraya

    2015-10-15

    Highlights: • Zintl tetragonal phase ACdGeAs{sub 2} (A = K, Rb) are chalcopyrite and semiconductors. • Their direct band gap is suitable for PV, optolectronic and thermoelectric applications. • Combination of DFT and Boltzmann transport theory is employed. • The present arsenides are found to be covalent materials. - Abstract: Chalcopyrite semiconductors have attracted much attention due to their potential implications in photovoltaic and thermoelectric applications. First principle calculations were performed to investigate the electronic, optical and thermoelectric properties of the Zintl tetragonal phase ACdGeAs{sub 2} (A = K, Rb) using the full potential linear augmented plane wave method and the Engle–Vosko GGA (EV–GGA) approximation. The present compounds are found semiconductors with direct band gap and covalent bonding character. The optical transitions are investigated via the dielectric function (real and imaginary parts) along with other related optical constants including refractive index, reflectivity and energy-loss spectrum. Combining results from DFT and Boltzmann transport theory, we reported the thermoelectric properties such as the Seebeck’s coefficient, electrical and thermal conductivity, figure of merit and power factor as function of temperatures. The present chalcopyrite Zintl quaternary arsenides deserve to be explored for their potential applications as thermoelectric materials and for photovoltaic devices.

  18. Microhydration of caesium compounds: Cs, CsOH, CsI and Cs₂I₂ complexes with one to three H₂O molecules of nuclear safety interest.

    PubMed

    Sudolská, Mária; Cantrel, Laurent; Cernušák, Ivan

    2014-04-01

    Structure and thermodynamic properties (standard enthalpies of formation and Gibbs free energies) of hydrated caesium species of nuclear safety interest, Cs, CsOH, CsI and its dimer Cs₂I₂, with one up to three water molecules, are calculated to assess their possible existence in severe accident occurring to a pressurized water reactor. The calculations were performed using the coupled cluster theory including single, double and non-iterative triple substitutions (CCSD(T)) in conjunction with the basis sets (ANO-RCC) developed for scalar relativistic calculations. The second-order spin-free Douglas-Kroll-Hess Hamiltonian was used to account for the scalar relativistic effects. Thermodynamic properties obtained by these correlated ab initio calculations (entropies and thermal capacities at constant pressure as a function of temperature) are used in nuclear accident simulations using ASTEC/SOPHAEROS software. Interaction energies, standard enthalpies and Gibbs free energies of successive water molecules addition determine the ordering of the complexes. CsOH forms the most hydrated stable complexes followed by CsI, Cs₂I₂, and Cs. CsOH still exists in steam atmosphere even at quite high temperature, up to around 1100 K.

  19. Influence of Structural Disorder on Hollandites A(x)Ru4O8 (A(+) = K, Rb, Rb(1-x)Na(x)).

    PubMed

    Laurita, Geneva; Grajczyk, Rosa; Stolt, Matthew; Coutinho, Italo; Sleight, Arthur W; Subramanian, M A

    2016-04-04

    Structural disorder can play an important role in the electrical properties of correlated materials. In this work we examine the average and local disorder in hollandites A(x)Ru4O8 (A(+) = K, Rb, Rb(1-x)Na(x)) through neutron total scattering techniques. Samples with A(+) = Rb, Rb(1-x)Na(x) exhibit the largest amount of local disorder as evidenced by higher atomic displacement parameters, and as a result, a weakened temperature dependence of the resistivity is observed upon cooling as compared to K(x)Ru4O8. All samples exhibit anisotropic resistivity that is dominated by metallic conductivity at lower temperatures, and this is corroborated by Pauli paramagnetic behavior throughout the measured temperature regime.

  20. Alkyl group as entropy reservoir in an MMX chain complex, Pt2(n-PenCS2)4I.

    PubMed

    Saito, Kazuya; Ikeuchi, Satoaki; Nakazawa, Yasuhiro; Sato, Akane; Mitsumi, Minoru; Yamashita, Takami; Toriumi, Koshiro; Sorai, Michio

    2005-02-24

    Heat capacity of halogen-bridged one-dimensional binuclear metal complex (so-called MMX chain) having four n-pentyl groups, Pt2(n-PenCS2)4I, was measured by adiabatic calorimetry. A first-order phase transition was observed at 207.4 K when measurement was made after cooling from room temperature. The enthalpy and entropy of transition were determined to be 10.19 kJ mol(-1) and 49.1 J K(-1) mol(-1), respectively. A monotropic phase transition was observed at 324 K on heating, and the entropy of transition was essentially null. The sample once heated above 324 K never returned to the initial phase at room temperature and underwent a higher-order phase transition at 173 K and a first-order phase transition at 220.5 K. The enthalpy and entropy of the first-order phase transition were estimated to be 11.6 kJ mol(-1) and 52.4 J K(-1) mol(-1), respectively. The magnitude of the entropy gain at the phase transition from the initial room-temperature phase to the high-temperature phase at 324 K shows that in Pt2(n-PenCS2)4I a large amount of entropy reserved in alkyl chain is transferred to dithiocarboxylato groups upon the phase transition, as in the cases of Pt2(n-PrCS2)4I and Pt2(n-BuCS2)4I.