Description and geochemistry of DSDP Leg 55 Holes

One of the objectives of Leg 55 was to investigate the Tertiary history of sedimentation and environment on the Emperor Seamounts after their volcanic activity. For the three first sites, 430, 431, and 432, drilled on Ojin, Nintoku, and Yömei Seamounts, the Neogene sedimentary deposits are not well represented and are not typical pelagic sediments. Except for two holes (430A and 432), where we found calcareous oozes, the sediments are heterogeneous sands, gravels, and pebbly mudstones with a wide range in grain size and composition. Two phenomena characterize these deposits: the inheritance of volcaniclastic material and its alteration, and the authigenesis of secondary minerals including silicates, phosphates, and ferromanganese oxides formed under volcanic influence in a marine environment.

Structure and chemistry of TECHNO encrustations

Using as a starting point the results giving 'traditional' growth rates as determined by the decrease of radioelements (part I) and the hypothesis of rapid formation, the different mineralogical, structure and chemical characteristics of the sample have been studied to try to understand the possible mode of formation of this encrustation. A rapid formation would account for (1) the very peculiar structure of the sample composed of oriented botryoids and the bundle-like structure of the outermost oxide layer; (2) the fact that this sample represents a substitution of a preexisting hyaloclastite; (3) the different chemical gradients, mainly iron, thorium and uranium; (4) the fact that this sample which cannot have been maintained at the sediment-water interface by bioturbation is not covered by a great thickness of sediments. On the other hand, an unsolved problem remains: Why different radionuclides used for dating give growth rates of the same order of magnitude and different 'exposition ages'.

Lithology, mineralogy and geochemistry of ODP Hole 118-735B and 176-735B respectively

Ocean Drilling Program (ODP) Hole 735B, located on Atlantis Bank on the Southwest Indian Ridge, penetrated 1508 meters below seafloor with an average recovery of 87%, providing a nearly continuous sample of a significant part of oceanic Layer 3. Based on variations in texture and mineralogy, 12 major lithologic units are recognized in the section, ranging from 39.5 to 354 m thick. The principal lithologies include troctolite, troctolitic gabbro, olivine gabbro and microgabbro, gabbro, gabbronorite and Fe-Ti oxide gabbro, gabbronorite, and microgabbro. Highly deformed mylonites, cataclasites, and amphibole gneisses are locally present, as are small quantities of pyroxenite, anorthositic gabbro, and trondhjemite. Downhole variations in mineral composition, particularly for olivine and clinopyroxene, show a number of cyclic variations. Plagioclase compositions show the widest variations and correspond to different degrees of deformation and alteration as well as primary processes. Downhole chemical variations correspond reasonably well with variations in mineral compositions. Iron and titanium mainly reflect the presence of Fe-Ti oxide gabbros but show some cyclical variations in the lower part of the core where oxide gabbros are sparse. CaO is highly variable but shows a small but consistent increase downhole. MgO is more uniform than CaO and shows a very small downward increase. Sulfur and CO2 contents are generally low, but S shows significant enrichment in lithologic Unit IV, which consists of Fe-Ti oxide gabbro, reflecting the presence of sulfide minerals in the sequence. The lithologic, mineralogical, and geochemical data provided here will allow detailed comparisons with ophiolite sections as well as sections of in situ ocean crust drilled in the future.

Sedimentology, geochemistry and paleomagnetic of ODP Hole 151-913B

The Eocene and Oligocene epochs (55 to 23 million years ago) comprise a critical phase in Earth history. An array of geological records (Zachos et al., 2001, doi:10.1126/science.1059412; Lear et al., 2000, doi:10.1126/science.287.5451.269; Coxall et al., 2005, doi:10.1038/nature03135; Pekar et al., 2005; doi:10.1130/B25486.1; Strand et al., 2003, doi:10.1016/S0031-0182(03)00396-1) supported by climate modelling (DeConto and Pollard, 2003, doi:10.1038/nature01290) indicates a profound shift in global climate during this interval, from a state that was largely free of polar ice caps to one in which ice sheets on Antarctica approached their modern size. However, the early glaciation history of the Northern Hemisphere is a subject of controversy (Coxall et al., 2005, doi:10.1038/nature03135; Tripati et al., 2005, doi:10.1038/nature03874; Wolf-Welling et al., 1996, doi:10.2973/odp.proc.sr.151.139.1996; Moran et al., 2006, doi:10.1038/nature04800). Here we report stratigraphically extensive ice-rafted debris, including macroscopic dropstones, in late Eocene to early Oligocene sediments from the Norwegian-Greenland Sea that were deposited between about 38 and 30 million years ago. Our data indicate sediment rafting by glacial ice, rather than sea ice, and point to East Greenland as the likely source. Records of this type from one site alone cannot be used to determine the extent of ice involved. However, our data suggest the existence of (at least) isolated glaciers on Greenland about 20 million years earlier than previously documented (Winkler et al., 2002, doi:10.1007/s005310100199), at a time when temperatures and atmospheric carbon dioxide concentrations were substantially higher.

Baculus pastoralis : ad dirige[n]dos in via[m] pacis pedes visita[n]tiu[m] [et] visitatoru[m] : cu[m] sit lucerna q[ue]da[m] pedib[us] eoru[m] ... P[salm]o xxij.

Moreau, B. Inventaire,

Bai hu tong de lun : si juan /

Kuang 20.4 x 12.5 cm., 9 hang 25 zi, bai kou, si zhou dan bian, ban xin shang juan "Bai hu tong", zhong juan juan ci.

Cheng tan shan fang gu wen cun gao : si juan ; Cheng tan shan fang shi ji : shi qi juan /

Kuang 19 x 14.5 cm., 9 hang 25 zi, bai kou, zuo you shuang bian, ban xin zhong juan juan ci, xia juan ye ci.

Developments in the Theory of X-ray Absorption and Compton Scattering.

Thesis (Ph.D.)--University of Washington, 2016-06

Evaluation of silicon twinning in hypo-eutectic Al-Si alloys

It is generally accepted that growth of eutectic silicon in aluminium-silicon alloys occurs by a twin plane re-entrant edge (TPRE) mechanism. It has been proposed that modification of eutectic silicon by trace additions occurs due to a massive increase in the twin density caused by atomic effects at the growth interface. In this study, eutectic microstructures and silicon twin densities in samples modified by elemental additions of barium (Ba), calcium (Ca), yttrium (Y) and ytterbium (Yb) (elements chosen due to a near-ideal atomic radii for twinning) in an A356.0 alloy have been determined by optical microscopy, thermal analysis, X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Addition of barium or calcium caused the silicon structure to transform to a fine fibrous morphology, while the addition of yttrium or ytterbium resulted in a refined plate-like eutectic structure. Twin densities in all modified samples are higher than in unmodified alloys, and there are no significant differences between fine fibrous modification (by Ba and Ca) and refined plate-like modification (by Y and Yb). The twin density in all modified samples is less than expected based on the predictions by the impurity induced twining model. Based on these results it is difficult to explain the modification with Ba, Ca, Y and Yb by altered twin densities alone.

[0 0 1] zone-axis bright-field diffraction contrast from coherent Ge(Si) islands on Si(0 0 1): Dedicated to Professor Fang-hua Li on the occasion of her 70th birthday

Coherent Ge(Si)/Si(001) quantum dot islands grown by solid source molecular beam epitaxy at a growth temperature of 700degreesC were investigated using transmission electron microscopy working at 300 kV. The [001] zone-axis bright-field diffraction contrast images of the islands show strong periodicity with the change of the TEM sample substrate thickness and the period is equal to the effective extinction distance of the transmitted beam. Simulated images based on finite element models of the displacement field and using multi-beam dynamical diffraction theory show a high degree of agreement. Studies for a range of electron energies show the power of the technique for investigating composition segregation in quantum dot islands. (C) 2003 Elsevier B.V. All rights reserved.

Liquidus temperatures in calcium ferrite slags in equilibrium with molten copper

Experimental laboratory methods have been developed that enable phase-equilibria studies to be carried out on slags in the system Ca-Cu-Fe-O in equilibrium with metallic copper. These techniques involve equilibration at temperature, rapid quenching, and chemical analysis of the phases using electron-probe X-ray microanalysis (EPNIA). Equilibration experiments have been carried out in the temperature range of 1150 degreesC to 1250 degreesC (1423 to 1523 K) and in the composition range of 4 to 80 wt pct "Cu2O," 0 to 25 wt pct CaO, and 20 to 75 wt pct "Fe2O3" in equilibrium with metallic copper. Liquidus and solidus data are reported for the primary-phase fields of spinel (magnetite) and dicalcium ferrite. The resulting data have been used to construct liquidus isotherms of the CaO-"Cu2O"-"Fe2O3" system at metallic copper saturation.

Phase diagram of the three-band half-filled Cu-O two-leg ladder

We determine the phase diagram of the half-filled two-leg ladder both at weak and strong coupling, taking into account the Cu d(x)(2)-y(2) and the O p(x) and p(y) orbitals. At weak coupling, renormalization group flows are interpreted with the use of bosonization. Two different models with and without outer oxygen orbitals are examined. For physical parameters, and in the absence of the outer oxygen orbitals, the D-Mott phase arises; a dimerized phase appears when the outer oxygen atoms are included. We show that the circulating current phase that preserves translational symmetry does not appear at weak coupling. In the opposite strong-coupling atomic limit the model is purely electrostatic and the ground states may be found by simple energy minimization. The phase diagram so obtained is compared to the weak-coupling one.

Synthetic, EPR spectroscopic, magnetic and X-ray crystallographic structural studies on copper(II) complexes of the tridentate N2S donor ligand formed from 6-methyl-2-formylpyridine and S-methyldithiocarbazate (Hmpsme)

New copper(II) complexes of general empirical formula, Cu(mpsme)X center dot xCH(3)COCH(3) (mpsme = anionic form of the 6-methyl-2-formylpyridine Schiff base of S-methyldithiocarbazate; X = Cl, N-3, NCS, NO3; x = 0, 0.5) have been synthesized and characterized by IR, electronic, EPR and susceptibility measurements. Room temperature mu(eff) values for the complexes are in the range 1.75-2.1 mu(beta) typical of uncoupled or weakly coupled Cu(II) centres. The EPR spectra of the [Cu(mpsme)X] (X = Cl, N-3, NO3, NCS) complexes reveal a tetragonally distorted coordination sphere around the mononuclear Cu(II) centre. We have exploited second derivative EPR spectra in conjunction with Fourier filtering (sine bell and Hamming functions) to extract all of the nitrogen hyperfine coupling matrices. While the X-ray crystallography of [Cu(mpsme)NCS] reveals a linear polymer in which the thiocyanate anion bridges the two copper(II) ions, the EPR spectra in solution are typical of a magnetically isolated monomeric Cu(II) centres indicating dissociation of the polymeric chain in solution. The structures of the free ligand, Hmpsme and the {[Cu(mpsme)NO3] center dot 0.5CH(3)COCH(3)}(2) and [Cu(mpsme)NCS](n) complexes have been determined by X-ray diffraction. The {[Cu(mpsme)NO3]0.5CH(3)COCH(3)}(2) complex is a centrosymmetric dimer in which each copper atom adopts a five-coordinate distorted square-pyramidal geometry with an N2OS2 coordination environment, the Schiff base coordinating as a uninegatively charged tridentate ligand chelating through the pyridine and azomethine nitrogen atoms and the thiolate, an oxygen atom of a unidentate nitrato ligand and a bridging sulfur atom from the second ligand completing the coordination sphere. The [Cu(mpsme)(NCS)](n) complex has a novel staircase-like one dimensional polymeric structure in which the NCS- ligands bridge two adjacent copper(II) ions asymmetrically in an end-to-end fashion providing its nitrogen atom to one copper and the sulfur atom to the other. (c) 2005 Elsevier B.V. All rights reserved.

Temperature dependence of the crystal structure and g-values of [(HC(Ph2PO)(3))(2)Cu] (ClO4)(2)center dot 2H(2)O: Influence of dynamic Jahn-Teller coupling and lattice strain interactions

The temperature dependence of the X-ray crystal structure and powder EPR spectrum of [(HC(Ph2PO)(3))(2)CU]-(ClO4)(2)center dot 2H(2)O is reported, and the structure at room temperature confirms that reported previously. Below similar to 100 K, the data imply a geometry with near elongated tetragonal symmetry for the [(HC(Ph2PO)(3))(2)Cu](2+) complex, but on warming the two higher Cu-O bond lengths and g-values progressively converge, and by 340 K the bond lengths correspond to a compressed tetragonal geometry. The data may be interpreted satisfactorily assuming an equilibrium among the energy levels of a Cu-O-6 polyhedron subjected to Jahn-Teller vibronic coupling and a lattice strain. However, agreement with the experiment is obtained only if the orthorhombic component of the lattice strain decreases to a negligible value as the temperature approaches 340 K.