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  • 1
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    High-pressure behavior of cuprospinel CuFe2O4: Influence of the Jahn-Teller effect on the spinel structure (2015)
    Mineralogical Society of America
    Details
    Publication Date: 2015-08-15
    Description: The Jahn-Teller effect at Cu 2+ in cuprospinel CuFe 2 O 4 was investigated using high-pressure single-crystal synchrotron X-ray diffraction techniques at beamline BL10A at the Photon Factory, KEK, Japan. Six data sets were collected in the pressure range from ambient to 5.9 GPa at room temperature. Structural refinements based on the data were performed at 0.0, 1.8, 2.7, and 4.6 GPa. The unit-cell volume of cuprospinel decreases continuously from 590.8(6) to 579.5(8) Å 3 up to 3.8 GPa. Least-squares fitting to a third-order Birch-Murnaghan equation of state yields the zero-pressure volume V 0 = 590.7(1) Å 3 and bulk modulus K 0 = 188.1(4.4) GPa with K ' fixed at 4.0. The structural formula determined by electron microprobe analysis and site occupancy refinement is represented as T (Fe 3+ 0.90 Cu 2+ 0.10 ) M (Fe 3+ 1.10 Fe 2+ 0.40 Cu 2+ 0.50 )O 4 . Most of the Cu 2+ are preferentially distributed onto the octahedrally coordinated ( M ) site of the spinel structure. With pressure, the arrangement of the oxygen atoms around the M cation approaches a regular octahedron. This leads to an increase in the electrostatic repulsion between the coordinating oxygen ions and the 3 d z 2 orbital of M Cu 2+ . At 4.6 GPa, a cubic-tetragonal phase transition is indicated by a splitting of the a axis of the cubic structure into a smaller a axis and a longer c axis, with unit-cell parameters a = 5.882(1) Å and c = 8.337(1) Å. The tetragonal structure with space group I 4 1 / amd was refined to R 1 = 0.0332 and wR 2 = 0.0703 using 38 observed reflections. At the M site, the two M -O bonds parallel to the c -axis direction of the unit cell are stretched with respect to the four M -O bonds parallel to the a-b plane, which leads to an elongated octahedron along the c -axis. The cubic-to-tetragonal transition induced by the Jahn-Teller effect at Cu 2+ is attributable to this distortion of the CuO 6 octahedron and involves Cu 3 d z 2 orbital, ab initio quantum chemical calculations support the observation. At the tetrahedrally coordinated ( T ) site, on the other hand, the tetrahedral O- T -O bond angle increases from 109.47° to 111.7(7)°, which generates a compressed tetrahedral geometry along the c -axis. As a result of the competing distortions between the elongated octahedron and the compressed tetrahedron, the a unit-cell parameter is shortened with respect to the c unit-cell parameter, giving a c / a ' ratio ( $${a}^{\prime }=\sqrt{2}\hspace{0.17em}a$$ ) slightly greater than unity as referred to cubic lattice ( c / a ' = 1.002). The c / a ' value increases to 1.007 with pressure, suggesting further distortions of the elongated octahedron and compressed tetrahedron.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 2
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    Brucite chimney formation and carbonate alteration at the Shinkai Seep Field, a serpentinite-hosted vent system in the Southern Mariana Forearc (2016)
    Wiley
    Details
    Publication Date: 2016-09-11
    Description: Brucite-carbonate chimneys were discovered from the deepest known (∼5700 m depth) serpentinite-hosted ecosystem – the Shinkai Seep Field (SSF) in the southern Mariana forearc. Textural observations and geochemical analysis reveal three types (I-III) of chimneys formed by the precipitation and dissolution of constitutive minerals. Type I chimneys are bright white to light yellow, have a spiky crystalline and wrinkled surface with microbial mat and contain more brucite; these formed as a result of rapid precipitation under high fluid discharge conditions. Type II chimneys exhibit white to dull brown coloration, tuberous textures like vascular bundles, and are covered with grayish microbial mats and dense colonies of Phyllochaetopterus . This type of chimney is characterized by inner brucite-rich and outer carbonate rich zones and is thought to have precipitated from lower fluid discharge conditions than type I chimneys. Type III chimneys are ivory colored, have surface depressions and lack living microbial mats or animals. This type of chimney mainly consists of carbonate, and is in a dissolution stage. Stable carbon isotope compositions of carbonates in the two types (I and II) of active chimneys are extremely 13 C-enriched (up to +24.1‰), which may reflect biological 12 C consumption under extremely low dissolved inorganic carbon concentration in alkaline fluid. Type III chimneys have 13 C compositions indicating re-equilibration with seawater. Our findings demonstrate for the first time that carbonate chimneys can be form below carbonate compensation depth and provide new insights about linked geologic, hydrologic, and biological processes of the global deep-sea serpentinite-hosted vent systems. This article is protected by copyright. All rights reserved.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    Spin polarization enhanced by spin-triplet pairing in Sr_{2} RuO_{4} probed by NMR (2015)
    American Physical Society (APS)
    Details
    Publication Date: 2015-09-12
    Description: Author(s): K. Ishida, M. Manago, T. Yamanaka, H. Fukazawa, Z. Q. Mao, Y. Maeno, and K. Miyake The spin susceptibility in strontium ruthenate is shown to undergo an increase when the material goes superconducting, a result in variance with most superconductors that we know. This behavior, once predicted for 3 He too, is the surest sign that strontium ruthenate is a spin-triplet superconductor. [Phys. Rev. B 92, 100502(R)] Published Fri Sep 11, 2015
    Keywords: Superfluidity and superconductivity
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
    Published by American Physical Society (APS)
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  • 4
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    Recurrent insect outbreaks caused by temperature-driven changes in system stability (2013)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2013-08-03
    Description: Insects often undergo regular outbreaks in population density but identifying the causal mechanism for such outbreaks in any particular species has proven difficult. Here, we show that outbreak cycles in the tea tortrix Adoxophyes honmai can be explained by temperature-driven changes in system stability. Wavelet analysis of a 51-year time series spanning more than 200 outbreaks reveals a threshold in outbreak amplitude each spring when temperature exceeds 15 degrees C and a secession of outbreaks each fall as temperature decreases. This is in close agreement with our independently parameterized mathematical model that predicts the system crosses a Hopf bifurcation from stability to sustained cycles as temperature increases. These results suggest that temperature can alter system stability and provide an explanation for generation cycles in multivoltine insects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nelson, William A -- Bjornstad, Ottar N -- Yamanaka, Takehiko -- New York, N.Y. -- Science. 2013 Aug 16;341(6147):796-9. doi: 10.1126/science.1238477. Epub 2013 Aug 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Queen's University, Kingston, Ontario, Canada. nelsonw@queensu.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23907532" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Life Cycle Stages ; Models, Biological ; Moths/growth & development/*physiology ; Population Density ; Population Dynamics ; *Seasons ; *Temperature ; Wavelet Analysis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    Microtremor Array Measurements for Shallow S-Wave Profiles at Strong-Motion Stations in Hatay and Kahramanmaras Provinces, Southern Turkey (2017)
    Seismological Society of America (SSA)
    Details
    Publication Date: 2017-02-03
    Description: We conducted microtremor array exploration of shallow S -wave velocity profiles at 28 sites in Hatay and Kahramanmaras, in the southern part of Turkey, to provide fundamental data to assess seismic hazards in the two areas. A total of 16 and 12 sites were located in Hatay and Kahramanmaras Provinces, respectively. We temporarily installed two small arrays to obtain simultaneous records of vertical microtremors. The spatial autocorrelation method was applied to retrieve Rayleigh-wave phase velocity in a 1–30 Hz frequency range. The phase velocities at most of the sites in Kahramanmaras Province were high in the entire frequency range, whereas those in Hatay Province were widely distributed, suggesting significant variation in soil conditions. Low-phase velocities were identified at sites near the coast in Hatay. Subsequently, the phase velocity observed at each site was inverted to a 1D S -wave velocity profile to a depth of 100 m using a hybrid heuristic inversion. Most of the profiles in Kahramanmaras had very thin near-surface layers with S -wave velocities of less than 300 m/s and thicknesses of less than 10 m. The top layers at the sites in Hatay showed significant variation, with different S -wave velocities from 110 to 760 m/s and thicknesses from 2 to 40 m. These layers were thicker at the sites near the coastal area. We finally discuss amplification factors of S waves using the inverted profiles. The fundamental predominant periods of the amplification factors distributed across a wide frequency range from 0.8 to 10 Hz in Hatay. The peak frequencies concentrated in a high-frequency range of more than 5 Hz in Kahramanmaras. The profiles observed were used to map average S -wave velocities in the top 30 m at strong-motion stations.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America (SSA)
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  • 6
    Electronic Resource
    Electronic Resource
    Purification of a flavoprotein having NADPH-cytochrome c reductase and transhydrogenase activities from Nitrobacter winogradskyi and its molecular and enzymatic properties (1987)
    Springer
    Archives of microbiology 148 (1987), S. 95-99 
    Details
    ISSN: 1432-072X
    Keywords: Nitrobacter winogradskyi ; Chemolithotroph ; NAD(P)+ reductase ; NADPH-cytochrome c reductase ; Transhydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A flavoenzyme which showed NADPH-cytochrome c reductase (NADPH-cytochrome c oxidoreductase EC 1.6.2.4) and transhydrogenase (NADPH-NAD+ oxidoreductase, EC 1.6.1.1) activities was purified to an electrophoretically homogeneous state from Nitrobacter winogradskyi. The reductase was a flavoprotein which contained one FAD per molecule but no FMN. The oxidized form of the enzyme showed absorption maxima at 272, 375 and 459 nm with a shoulder at 490 nm, its molecular weight was estimated to be 36,000 by SDS polyacrylamide gel electrophoresis, and the enzyme seemed to exist as a dimer in aqueous solution. The enzyme catalyzed reduction of cytochrome c, DCIP and benzylviologen by NADPH, oxidation of NADPH with menadione and duroquinone, and showed transhydrogenase activity. NADH was less effective than NADPH as the electron donor in the reactions catalyzed by the enzyme. The NADPH-reduction catalyzed by the enzyme of N. winogradskyi cytochrome c-550 and horse cytochrome c was stimulated by spinach ferredoxin. The enzyme reduced NADP+ with reduced spinach ferredoxin and benzylviologen radical.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425355
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  • 7
    Electronic Resource
    Electronic Resource
    Radiochemistry and secondary reactions for the diagnostics of laser-driven fusion plasmas (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1731-1733 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Radiochemical measurements have been developed for the diagnostics of laser-driven implosion plasmas. The excellent calibration for neutron-yield measurement has been done using β-γ coincidence technique. The multiactivable tracer method has been examined for measuring the pusher areal density by means of a high-purity germanium detector. The first experimental success of the secondary nuclear fusion reaction method is also demonstrated for the direct measurement of the fuel ρR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138562
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  • 8
    Electronic Resource
    Electronic Resource
    Seam pucker simulation (1998)
    Bingley : Emerald
    International journal of clothing science & technology 10 (1998), S. 128-142 
    Details
    ISSN: 0955-6222
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: States that computer simulations of seam pucker were executed. The simulations were based on the computer program which predicts the shape of virtual fabric with an assumption that the relationship between stress and strain of the virtual fabric is linear. The simulations predicted the shape of fabric with the conditions such as material puckering and mechanical properties of fabric. The rating of simulated seam pucker changes according to material puckering. It was shown that bending stiffness and tensile modulus affect the rating of seam pucker. Seam pucker samples were made from fabric for comparison. Computerised seam pucker samples were executed utilising the same properties and shape of seam line as the sample fabric. A fairly similar shape was obtained by the simulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/09556229810213836
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation of Crystalline Pseudomonas cytochrome Oxidase and Some of its Properties (1962)
    [s.l.] : Nature Publishing Group
    Nature 194 (1962), S. 759-760 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] FROM the anaerobically cultivated cells of Pseudo-monas aeruginosa, a cytochrome which has all the properties of a cytochrome oxidase has been purified in an ultracentrifugally homogeneous state, and it was named Pseudomonas (P.) cytochrome oxidase1'2. The P. cytochrome oxidase has two hsems, hsem ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/194759a0
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular cloning of the cytochrome aa"3 gene from the archaeon (Archaebacterium) Halobacterium halobium
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 181 (1991), S. 316-322 
    Details
    ISSN: 0006-291X
    Keywords: [abr] PCR; polymerase chain reaction ; [abr] PS3; thermophilic bacterium PS3
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0006-291X(05)81420-2
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