778 research outputs found
Geology of the Khor Fakkan 1:50 000 map sheet 50-3, United Arab Emirates
No full textThis report is a description of the 1:50 000 scale Khor Fakkan geological map sheet. It forms part of the published outputs from a contract between the United Arab Emirates (UAE) Federal Government (Ministry of Energy) and the British Geological Survey (BGS) to produce geological maps, at various scales, of the solid and drift geology of the eastern part of the United Arab Emirates. These maps, which have accompanying Sheet Explanations, are listed below.
The geological mapping of the Khor Fakkan sheet was undertaken during three winter seasons from 2002 to 2005 (October to December; January to March). The field mapping was carried out largely on transparent overlays on 1:25 000 scale colour aerial photographs, used in conjunction with LANDSAT imagery and 1:50 000 scale topographical base maps. The field data were transferred onto gridded transparent overlays on georectified LANDSAT images at 1: 25 000 scale.
K M Goodenough, E R Phillips, D Stephenson, M T Styles, R J Thomas and M Warrak carried out the geological mapping of the Khor Fakkan district. A R Farrant and S L B Arkley contributed to the mapping of the Quaternary deposits. Petrographical analyses were completed by K M Goodenough, E R Phillips, M T Styles and R J Thomas on samples collected by the mapping team. The Sheet Explanation was compiled by K M Goodenough.
The word ‘district’ is used here to refer to the area represented by the geological map 1:50 000 series sheet Khor Fakkan. The grid references in the text are UTM Zone 40, using the Nahrawan datum, given in the form [0419633 2826172]. Symbols in brackets after lithostratigraphical names refer to symbols used on the 1:50 000 series geological map. References to other Sheet Explanations in these series are given by Sheet name and number e.g. (Fujairah Sheet, 50-4)
A new target for shigellosis: Rational design and crystallographic studies of inhibitors of tRNA-guanine transglycosylase
No full textEubacterial tRNA-guanine transglycosylase (TGT) is involved in the hyper-modification of cognate tRNAs leading to the exchange of G34 at the wobble position in the anticodon loop by preQ(1) (2-amino-5-(aminomethyl)pyrrolo[2,3-d]pyrimidin-4(3H)-one) as part of the biosynthesis of queuine (Q). Mutation of the tgt gene in Shigella flexneri results in a significant loss of pathogenicity of the bacterium, revealing TGT as a new target for the design of potent drugs against Shigellosis. The X-ray struc ture of Zymomonas mobilis TGT in complex with preQ(1) was used to search for new putative inhibitors with the computer program LUDI. An initial screen of the Available Chemical Directory, a database compiled from commercially available compounds, suggested several hits. Of these, 4-aminophthalhydrazide (APH) showed an inhibition constant in the low micromolar range. The 1.95 Angstrom crystal structure of APH in complex with Z. mobilis TGT served as a starting point for further modification of this initial lead. (C) 2001 Academic Press
Synthesis, Structure and Magnetic Properties of NiFe3O5
No full textA new CaFe3O5-type phase NiFe3O5 (orthorhombic Cmcm symmetry, cell parameters a = 2.89126(7), b = 9.71988(21) and c = 12.52694(27) Å) has been synthesised under pressures of 12-13 GPa at 1200 C. NiFe3O5 has an inverse cation site distribution and reveals an interesting evolution from M2+(Fe3+)2Fe2+O5 to Fe2+(M2+0.5Fe3+0.5)2Fe3+O5 distributions over three distinct cation sites as M2+ cation size decreases from Ca to Ni. Magnetic susceptibility measurements show successive transitions at 275, ∼150, and ∼20 K and neutron diffraction data reveal a series of at least three spin-ordered phases with evolving propagation vectors k = [0 0 0] → [0 k y 0] → [1/2 1/2 0] on cooling. The rich variety of magnetically ordered phases in NiFe3O5 likely results from frustration of Goodenough-Kanamori exchange interactions between the three spin sublattices, and further interesting magnetic materials are expected to be accessible within the CaFe3O5-type family
On high-temperature evolution of passivation layer in Li–10 wt % Mg alloy via in situ SEM-EBSD
No full textLi–10 wt % Mg alloy (Li–10 Mg) is used as an anode material for a solid-state battery with excellent electrochemical performance and no evidence of dendrite formation during cycling. Thermal treatment of Li metal during manufacturing improves the interfacial contact between a Li metal electrode and solid electrolyte to achieve an all solid-state battery with increased performance. To understand the properties of the alloy passivation layer, this paper presents the first direct observation of its evolution at elevated temperatures (up to 325°C) by in situ scanning electron microscopy. We found that the morphology of the surface passivation layer was unchanged above the alloy melting point, while the bulk of the material below the surface was melted at the expected melting point, as confirmed by in situ electron backscatter diffraction. In situ heat treatment of Li-based materials could be a key method to improve battery performance
Geology of the Hatta 1:50 000 map sheet, 50-5, United Arab Emirates
No full textThis report is a description of the 1:50 000 scale Hatta geological map sheet. It forms part of the published outputs from a contract between the United Arab Emirates (UAE) Federal Government (Ministry of Energy) and the British Geological Survey (BGS) to produce geological maps, at various scales, of the solid and drift geology of the eastern part of the United Arab Emirates. These maps, which have accompanying Sheet Explanations, are listed below.
Geological surveying of the Hatta Sheet was completed in three winter field seasons, carried out between October to December and January to March of 2002-2005. Field data was recorded on transparent overlays on 1:25 000 scale colour aerial photographs, used in conjunction with LANDSAT imagery and 1:50 000 topographical base maps. The field data were transferred onto gridded transparent overlays on georectified LANDSAT images at 1:25 000 scale.
The mapping team for the Hatta district consisted of M T Styles, R J Thomas, D I Schofield, K M Goodenough, and E R Phillips, with A R Farrant contributing to mapping of the Quaternary deposits. Petrographic analyses were completed by M T Styles, R J Thomas, E R Phillips and K M Goodenough on samples collected by the mapping team. The Sheet Explanation was compiled by M T Styles.
The word ‘district’ is used here to refer to the area represented by the geological map 1:50 000 series sheet Hatta. The grid references in the text are UTM Zone 40 using the Nahrawan datum, given in the form [0419633 2826172]. Symbols in brackets after lithostratigraphic names refer to symbols used on the 1:50 000 series geological map. References to other Sheet Explanations in these series are given by Sheet name and number e.g. (Fujairah Sheet, 50-4)
Geology of the Hatta 1:25 000 map sheet 25-4, United Arab Emirates
No full textThis report is a description of the 1:25 000 scale Hatta geological map sheet. It forms part of the published outputs from a contract between the United Arab Emirates Federal Government (Ministry of Energy) and the British Geological Survey (BGS) to produce geological maps, at various scales, of the solid and drift geology of the eastern part of the United Arab Emirates. These maps, which have accompanying Sheet Explanations, are listed below.
Geological surveying of the Hatta Sheet was completed in three winter field campaigns carried out between October to December and January to March of 2002-2005. Field data were recorded on transparent overlays on 1:25 000 scale colour aerial photographs, used in conjunction with LANDSAT imagery and 1:50 000 topographic maps. The field data were transferred onto gridded transparent overlays on geo-rectified LANDSAT images at 1:25 000 scale.
Geological mapping of the Hatta district was carried out by M T Styles (ophiolite), R J Thomas (ophiolite, Hatta Zone west, metamorphic rocks), E R Phillips (Hatta Zone east and west, metamorphic rocks), D I Schofield, K M Goodenough (ophiolite), and, A R Farrant contributing to mapping of the Quaternary deposits. Petrographical analyses were completed by E R Phillips, R J Thomas, M T Styles and K M Goodenough on samples collected by the mapping team. The Sheet Explanation was compiled by E R Phillips and R J Thomas.
The word ‘district’ is used here to refer to the area represented by the geological map 1:25 000 series sheet Hatta. The grid references in the text are UTM Zone 40 using the Nahrawan datum, given in the form [0419633 2826172]. Symbols in brackets after lithostratigraphic names refer to symbols used on the 1:25 000 series geological map. Refrences to other Sheet Explanations in these series are given by Sheet name and number (e.g. Fujairah Sheet, 50-4)
Revisiting Goodenough-Kanamori rules in a new series of double perovskites LaSr1-xCaxNiReO6
No full textThe magnetic ground states in highly ordered double perovskites LaSr1-xCaxNiReO6 (x = 0.0, 0.5, 1.0) are studied in view of the Goodenough-Kanamori rules of superexchange interactions in this paper. In LaSrNiReO6, Ni and Re sublattices are found to exhibit curious magnetic states separately, but no long range magnetic ordering is achieved. The magnetic transition at similar to 255 K is identified with the independent Re sublattice magnetic ordering. Interestingly, the sublattice interactions are tuned by modifying the Ni-O-Re bond angles through Ca doping. Upon Ca doping, the Ni and Re sublattices start to display a ferrimagnetically ordered state at low temperature. The neutron powder diffraction data reveals long range ferrimagnetic ordering of the Ni and Re magnetic sublattices along the crystallographic b-axis. The transition temperature of the ferrimagnetic phase increases monotonically with increasing Ca concentration
Long-term memory of subduction processes in the lithospheric mantle: evidence from the geochemistry of basic dykes in the Gardar Province of South Greenland
No full textThe rift-related magmas of the Proterozoic Gardar Igneous Province were emplaced across the contact between the South Greenland Archaean craton and the Palaeoproterozoic Ketilidian mobile belt. It has been suggested that the geochemistry of Gardar intrusive rocks in the two areas varies across the craton margin and that this reflects a lithospheric control. However, comparison of the geochemical and isotopic signatures of basic and ultrabasic dykes from across the area shows that there is no systematic variation related to the age of the country rock. All the Gardar basic rocks are inferred to have been derived from the mantle, with relatively little crustal contamination. We suggest that the lithospheric mantle beneath the Gardar Province was enriched by slab-derived fluids during the Ketilidian orogeny (c. 1800 Ma). Subsequent melting of this mantle source was promoted during Gardar rifting when volatile-rich, small-degree melts from the asthenosphere were introduced into the lithospheric mantle, forming enriched metasomites. Ultrabasic lamprophyre dykes in the Gardar Province represent melts derived largely from these metasomites, whereas basaltic magmas were formed by larger-scale melting of the lithospheric mantle, inheriting a subduction-related signature. There is no evidence that the Gardar magmas were derived from a highly enriched lithospheric keel that had existed since craton formation
Spin-orbital physics for p orbitals in alkali RO<sub>2</sub> hyperoxides-Generalization of the Goodenough-Kanamori rules
No full textWe derive a realistic spin-orbital model at finite Hund's exchange for alkali hyperoxides. We find that, due to the geometric frustration of the oxygen lattice, spin and orbital waves destabilize both spin and p-orbital order in almost all potential ground states. We show that the orbital order induced by the lattice overrules the one favoured by superexchange and that this, together with the large interorbital hopping, leads to generalized Goodenough-Kanamori rules. They i) lift the geometric frustration of the lattice, and ii) explain the observed layered C-type antiferromagnetic order in alkali hyperoxides. This is confirmed by a spin-wave dispersion with no soft-mode behavior presented here as a prediction for future experiments. Copyright (C) EPLA, 201
Role of structural defects in olivine cathodes
No full textThe high rate capability and structural stability of the olivine phosphates attracted a lot of interest as promising cathode materials for high energy density batteries. Alteration on these cathode materials, for instance, reducing particle size, conductive coating and metal ion doping were performed in order to improve the conductivity and to obtain high specific capacity. Wide range of transition metal ions with range of valences (M 1+ to M 5+) was successfully doped both in M 1 site (Li) and M 2 site (M) of olivine LiMPO 4 (M = Fe, Mn, Co and Ni) cathode. The large charge difference between the doped supervalent ions and M cations at the M 2 site, limited the use of supervalent cations in the olivines. However, the supervalent dopants (namely; Cr 3+, Ti 4+, Nb 5+) are reported to be successfully substituted in the olivine with an improvement in electrical and ionic conductivity. The amount of defect can be reduced by low concentration of dopants, choosing suitable synthesis method and optimized reaction conditions. Charge compensation vacancies accomplished through aliovalent doping reduces the grain size and widens the Li + migration path resulting in faster Li + diffusion. However, the drastic improvement in electrical conductivity for the aliovalent doping is still unclear. Rather writing a lengthy standard review, this manuscript intends to describe briefly the lattice defects owing to metal ion doping and its influence in improving the cathode performance of the olivine phosphates. This gives a new approach in this field
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