ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
  • 1
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2007
    Description: 〈span〉〈div〉Abstract〈/div〉Seventy-three ostracode species from 38 genera were recovered from the 55 surface sediment samples in Lützow-Holm Bay, northeastern Antarctica. We investigated bathymetric and geographic distributions of modern benthic ostracode species in the bay and compared this fauna with published modern and fossil ostracode data of Antarctic and southern South American regions. The results show: (1) Four biotopes and three sub-biotopes are recognized based on Q-mode cluster analysis, which suggest distributions of modern ostracodes are mainly controlled by water-mass structure, ice scouring, and light availability. (2) Comparison between the Lützow-Holm Bay fauna and other ostracode faunas from Antarctica and southern South America shows high endemism and homogeneity of Antarctic ostracode fauna, suggesting 〈span〉in situ〈/span〉 evolution of most extant Antarctic species. (3) Most species are endemic to the Antarctica, a few species also inhabit South American waters.〈/span〉
    Print ISSN: 0026-2803
    Electronic ISSN: 1937-2795
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2012-12-11
    Description: Seventy-three ostracode species from 38 genera were recovered from the 55 surface sediment samples in Lützow-Holm Bay, northeastern Antarctica. We investigated bathymetric and geographic distributions of modern benthic ostracode species in the bay and compared this fauna with published modern and fossil ostracode data of Antarctic and southern South American regions. The results show: (1) Four biotopes and three sub-biotopes are recognized based on Q-mode cluster analysis, which suggest distributions of modern ostracodes are mainly controlled by water-mass structure, ice scouring, and light availability. (2) Comparison between the Lützow-Holm Bay fauna and other ostracode faunas from Antarctica and southern South America shows high endemism and homogeneity of Antarctic ostracode fauna, suggesting in situ evolution of most extant Antarctic species. (3) Most species are endemic to the Antarctica, a few species also inhabit South American waters.
    Print ISSN: 0026-2803
    Electronic ISSN: 0026-2803
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2012-10-03
    Description: In both metazoan development and metastatic cancer, migrating cells must carry out a detailed, complex program of sensing cues, binding substrates, and moving their cytoskeletons. The linker cell in Caenorhabditis elegans males undergoes a stereotyped migration that guides gonad organogenesis, occurs with precise timing, and requires the nuclear hormone receptor...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    facet.materialart.
    Unknown
    In:  Geophys. J. Int., Amsterdam, Univ. Tokyo, vol. 106, no. 7, pp. 551-557, pp. L07307, (ISSN: 1340-4202)
    Publication Date: 1991
    Keywords: Seismology ; P-waves ; GJI
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    facet.materialart.
    Unknown
    Center for Acad. Publ. Japan
    In:  Bull., Polar Proj. OP-O3A4, Earthquake Precursors, Tokyo, Center for Acad. Publ. Japan, vol. 22, no. 4, pp. 123-136, (ISBN 0080419208)
    Publication Date: 1978
    Keywords: Earthquake precursor: prediction research ; Earthquake precursor: deformation or strain ; Earth tides ; Proceedings of a conference ; JZSCHAU
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2016-03-27
    Description: Thg1-like protein (TLP) catalyzes the addition of a nucleotide to the 5'-end of truncated transfer RNA (tRNA) species in a Watson-Crick template–dependent manner. The reaction proceeds in two steps: the activation of the 5'-end by adenosine 5'-triphosphate (ATP)/guanosine 5'-triphosphate (GTP), followed by nucleotide addition. Structural analyses of the TLP and its reaction intermediates have revealed the atomic detail of the template-dependent elongation reaction in the 3'-5' direction. The enzyme creates two substrate binding sites for the first- and second-step reactions in the vicinity of one reaction center consisting of two Mg 2+ ions, and the two reactions are executed at the same reaction center in a stepwise fashion. When the incoming nucleotide is bound to the second binding site with Watson-Crick hydrogen bonds, the 3'-OH of the incoming nucleotide and the 5'-triphosphate of the tRNA are moved to the reaction center where the first reaction has occurred. That the 3'-5' elongation enzyme performs this elaborate two-step reaction in one catalytic center suggests that these two reactions have been inseparable throughout the process of protein evolution. Although TLP and Thg1 have similar tetrameric organization, the tRNA binding mode of TLP is different from that of Thg1, a tRNA His -specific G –1 addition enzyme. Each tRNA His binds to three of the four Thg1 tetramer subunits, whereas in TLP, tRNA only binds to a dimer interface and the elongation reaction is terminated by measuring the accepter stem length through the flexible β-hairpin. Furthermore, mutational analyses show that tRNA His is bound to TLP in a similar manner as Thg1, thus indicating that TLP has a dual binding mode.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2016-08-24
    Description: Hydroxyurea (HU) has been used clinically to reduce the frequency of painful crisis and the need for blood transfusion in sickle cell disease (SCD) patients. However, the mechanisms underlying such beneficial effects of HU treatment are still not fully understood. Studies have indicated a weak correlation between clinical outcome and...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2011-06-10
    Description: The valence-band and core-level soft x-ray photoelectron spectroscopy has been applied to investigate the origin of the large thermoelectric power in the off-stoichiometric and partially-substituted Fe-based Heusler-type alloys Fe 2− x − y Ir y V 1+ x Al and Fe 2− x V 1+ x − y Ti y Al. The non-rigid-band-like change in the valence-band electronic structure near the Fermi level E F is found for the off-stoichiometric change x in Fe and V concentrations, whereas the rigid-bandlike shift of E F is recognized on the Ir or Ti substitution y . The non-rigid-band-like change may be induced by the excess-V or Fe (anti-site defects)-derived states in the pseudogap of Fe 2 VAl, while the rigid-band-like shift may be caused by a common band formation, where the d states of the substituted elements are incorporated into the main...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2015-06-03
    Description: Pathway-specific gene delivery is requisite for understanding complex neuronal systems in which neurons that project to different target regions are locally intermingled. However, conventional genetic tools cannot achieve simultaneous, independent gene delivery into multiple target cells with high efficiency and low cross-reactivity. In this study, we systematically screened all receptor–envelope...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...